JP3905392B2 - Reactor equipment, reactor core, and operating method of reactor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pebble bed type nuclear reactor core, a nuclear reactor equipped with the same, and a method of operating the nuclear reactor.
[0002]
[Prior art]
In general, in a pebble bed type reactor, a large number of fuel balls are introduced into the reactor from the upper part of the vessel to constitute a core, and a high-temperature gas such as helium (He) is used as a coolant.
[0003]
This fuel ball has a structure in which, for example, the diameter is about 6 cm, and the fuel region is surrounded by a graphite shell. The fuel region is composed of a large number of coated fuel particles and a graphite matrix containing them.
[0004]
The coated fuel particles have a diameter of 0.5 to 1.0 mm and are substantially spherical. This coated fuel particle is composed of a fuel nucleus having a diameter of 200 to 600 μm composed of an oxide or carbide of fissile material such as uranium (U), plutonium (Pu), thorium (Th) or a mixture thereof at the center. The fuel core is composed of a pyrolytic carbon layer, a silicon carbide layer, and the like that cover the fuel core in multiple layers. These coating layers such as pyrolytic carbon layer and silicon carbide layer have a function as a barrier against the leakage of fission products, and the fission gas can be held almost completely inside the coated fuel particles even under high temperature irradiation. ing.
[0005]
On the other hand, in some cases, a deceleration ball is loaded together with a fuel ball on the core of a pebble bed reactor. The decelerating sphere is used to decelerate neutrons and is made of graphite.
[0006]
These fuel balls and deceleration balls are continuously charged from the upper part of the core during the operation of the reactor, move from the upper part of the core to the lower part of the core, and are taken out from the lower part of the core. Thus, the greatest feature of a pebble bed reactor is that fuel can be changed during the operation of the reactor. As a reactor facility for that purpose, for example, the MEDUL method as described in US Pat. No. 4,372,912 or the multi-pass method is used. A pebble bed type reactor facility called is used.
[0007]
This type of pebble bed type reactor equipment detects the burnup of the core and the fuel ball taken out from the lower part of the core according to the presence or absence of breakage, and the burnup of the non-damaged fuel ball. And a fuel injector that again injects fuel balls that have not reached the predetermined degree of combustion with the degree of burnup detected by the burnup detector. As a result, fuel balls that are not damaged and have not reached the predetermined burn-up can be put into the core again. In this way, it is possible to eliminate variations in the degree of burnout of each fuel ball, and to flatten the average burnup distribution of the fuel ball in the axial direction of the core, thus reducing the output peaking in the core axis direction.
[0008]
By the way, it goes without saying that in such a pebble bed reactor, increasing the output per reactor as in other light water reactors or the like leads to an improvement in the economy of the entire power plant. The pebble bed type fuel is considered to maintain its soundness at temperatures up to about 1600 ° C, and even if an accident is assumed, the maximum fuel temperature will not exceed it, The maximum output is limited. From these viewpoints, in the pebble bed type reactor, by reducing the power peaking in the core axis direction and the power peaking in the core radial direction as much as possible, the power density of the core per reactor is kept within the above limit range. It is desirable to increase the output as much as possible.
[0009]
Here, in general, the pebble bed type reactor is small and has a feature of being long in the vertical direction. That is, the ratio of the core height to the core diameter is 1 or more, and neutron leakage from the side surface of the core is large. Therefore, the power distribution tends to be large at the center in the core radial direction, and the value of the radial power peaking tends to be large. There is a tendency.
[0010]
However, in the MEDUL type or multipass type pebble bed reactor, reduction of power peaking in the core radial direction is not taken into consideration, which is sufficient from the viewpoint of improving the economic efficiency of the power plant as described above. I couldn't say that.
[0011]
Against this background, in recent years, for example, as described in the IAEA report (IAEA-TECCDOC-1198), the core is divided into two regions in the radial direction while using the MEDUL method or the multi-pass method, and is decelerated inward in the radial direction. A pebble-bed modular reactor (hereinafter referred to as PBMR) has been proposed in which only a sphere and only a fuel sphere are loaded radially outward. According to this PBMR, it is possible to bring the power peak at the center in the radial direction when the core is composed of only fuel balls to the outside in the radial direction, and reduce the output peaking in the axial direction while reducing the output peak in the radial direction. Can also be reduced.
[0012]
[Problems to be solved by the invention]
According to the above prior art, both the power peaking in the core axis direction and the power peaking in the radial direction can be reduced, and the economic efficiency of the entire power plant can be improved.
[0013]
By the way, the output peak of the core is highly dependent on the arrangement of the fuel sphere or the deceleration sphere in the core. Therefore, there is room for further improvement in the reduction of the output peaking in the core radial direction in which the arrangement of the fuel spheres or deceleration spheres can be easily manipulated artificially as compared with the core axis direction. In that sense, it cannot be said that the above-described prior art is sufficient to flatten the power in the core radial direction.
[0014]
From the viewpoint of increasing the output of the core, for example, as described in JP-A-63-133304, the core is divided into two regions in the radial direction, and the proportion of graphite in the radially inner region is larger than that in the radially outer region. However, in this prior art, no particular consideration is given to reducing the output peaking in the core radial direction. That is, since the ratio of graphite contained in the fuel balls in the radially inner region is larger than that in the radially outer region, the output peak may be biased toward the center in the core radial direction. Therefore, even in this conventional technique, it cannot be said that the core radial output is sufficiently flattened.
[0015]
The present invention has been made in view of these problems of the prior art, and an object of the present invention is to provide a pebble bed reactor capable of further flattening the power in the core radial direction and improving economy, and the reactor. And a method of operating the nuclear reactor.
[0016]
[Means for Solving the Problems]
(1) In order to achieve the above object, the nuclear reactor facility of the present invention introduces a number of fuel balls discharged from a pebble bed type reactor core, and a detecting means for detecting the burnup of the fuel balls. And a first distribution unit that distributes the injection position in the radial direction when the fuel ball is reintroduced into the reactor core according to the detection result of the detection unit.
[0017]
Generally, since the reactivity of a nuclear fuel decreases as the combustion progresses, the output of a fuel with a low burnup tends to be high, and the output of a fuel with a high burnup tends to be low.
[0018]
In the present invention, the degree of burnup of the fuel spheres discharged from the reactor core is detected by the detection means, and the radial introduction position when the fuel sphere is re-introduced is distributed by the first distribution means according to the detection result. In this way, it is possible to realize a core in which, for example, the average burnup of all the fuel spheres in the inner region in the inner diameter direction of the reactor core is larger than the average burnup of all the fuel spheres in the outer region. As a result, the power in the outer region in the core radial direction is relatively increased from the inner region, so that the tendency to increase the power in the vicinity of the center of the normal core is alleviated, and the power in the core radial direction can be flattened. it can. In the present invention, since the core is composed only of fuel balls, PBMR in which only the deceleration spheres are loaded on the inner side in the core radial direction so as to flatten the radial output, or graphite on the inner side in the core radial direction. The number of fuel balls can be increased as compared with the prior art loaded with large-diameter fuel balls with a larger proportion of By these two, the maximum output burden per fuel ball can be lowered relatively. As a result, on the contrary, the power per core can be increased by raising the maximum power per ball to the limit value at which soundness can be maintained. Therefore, economic efficiency can be improved.
[0019]
Further, as described above, since the inside of the core is composed of only the fuel balls, the amount of fuel loaded in the entire core becomes larger than that in the prior art using the speed reduction balls. Therefore, the fuel economy is improved, and this can also achieve the effect of improving the economy as seen in the whole reactor.
[0020]
(2) In the above (1), preferably, the first distribution means distributes the radially inserted positions of the fuel balls having a relatively small burnup to the outside in the radial direction and has a relatively high burnup. The fuel ball radial input position is distributed radially inward.
[0021]
(3) In the above (1) or (2), and preferably, the first distribution means includes a plurality of fuel balls provided so that one end portions thereof are located at different radial positions in the upper part of the reactor core. A supply pipe and a first selective introduction means for selectively introducing the fuel sphere into the plurality of fuel sphere supply pipes according to a detection result of the detection means.
[0022]
(4) In the above (3), more preferably, the first selective introduction means is provided on the downstream side of the detection means, and is a switching means for switching a fuel ball derivation path for which the degree of combustion has been detected by the detection means. Is provided.
[0023]
(5) In the above (4), more preferably, the switching means guides the fuel ball having a predetermined burnup to the take-out side passage.
[0024]
(6) In any one of the above (1) to (5), and preferably, the detection means is means for detecting radiation relating to a predetermined nuclide contained in the fuel ball.
[0025]
(7) In order to achieve the above object, the reactor equipment of the present invention introduces a large number of reduction spheres discharged from a pebble bed type reactor core, and the reduction gear occupies the fuel sphere and the entire reduction sphere. A first derivation means capable of deriving the deceleration sphere so as to switch and set the mixing ratio of the spheres to a plurality of values, and the resumption of the deceleration sphere derived from the first derivation means into the reactor core. And a second distribution unit that distributes the radial insertion position for each set value of the mixing ratio of the deceleration balls.
[0026]
For example, uranium 235 (one of the nuclear fuel materials contained in the fuel ball)²³⁵U) has the property of causing fission by colliding with neutrons having a soft spectrum. That is, in the reactor core composed of the fuel sphere and the deceleration sphere, in a region where the mixing ratio of the deceleration sphere in the entire fuel sphere and the deceleration sphere is large, for example, the neutron is sufficiently decelerated by the deceleration sphere composed of graphite. The spectrum becomes soft and uranium 235 (²³⁵U) fission reaction is likely to occur. Therefore, the output tends to increase in an area where there are many deceleration balls.
[0027]
In the present invention, the first derivation means can switch the deceleration sphere mixing ratio to a plurality of values while setting the deceleration sphere to be derived, and the second distribution means can change the radial direction when the deceleration sphere is re-introduced for each set value. Sort the input position. In this way, for example, it is possible to realize a core in which the number density of reduction spheres in the inner radial region of the reactor core is smaller than the number density of reduction spheres in the outer region. As a result, similarly to the above (1), the output of the outer region in the core radial direction is relatively increased compared to the inner region, and the tendency to increase the output near the center of the normal core is alleviated. The output can be flattened. As a result, the maximum output burden per fuel ball can be relatively lowered and the output per core can be increased, so that the economic efficiency of the entire reactor can be improved.
[0028]
(8) In the above (7), preferably, the second distributing means distributes a radially inserted position of a group of fuel spheres and deceleration spheres having a relatively large mixing ratio of the deceleration spheres to the outside in the radial direction, The positions in the radial direction of a group of fuel balls and deceleration balls having a relatively small mixing ratio of the deceleration balls are distributed radially inward.
[0029]
(9) In the above (7) or (8), and preferably, the second distribution means includes a plurality of fuel balls provided so that one end portions thereof are at different radial positions in the upper part of the reactor core. A supply pipe; and second selective introduction means for selectively introducing the fuel sphere and the deceleration sphere into the plurality of fuel sphere supply pipes according to a set value of a mixing ratio of the deceleration spheres.
[0030]
(10) In the above (7), and preferably, according to a detection means for introducing a large number of fuel balls discharged from the reactor core and detecting the burnup of the fuel balls, and a detection result of the detection means And a first allocating means for allocating a radial injection position when the fuel sphere is re-entered into the reactor core, wherein the first allocating means has a relatively high burnup of the fuel sphere. The charging position is distributed to one side of the radially inner side and the outer side, and the charging position of the fuel ball having a relatively low burnup is distributed to the other side of the radial inner side and the outer side. The throwing position of the decelerating sphere when the setting value of the mixing ratio is relatively large is distributed to the one side in the radial direction, and the throwing position of the decelerating sphere when the setting value of the mixing ratio is relatively small is the diameter. Distributed to toward the other side.
[0031]
In general, when the neutron spectrum is hard (shifts to the higher energy side), uranium 235 (²³⁵The reactivity of fuel material such as U) is small (fission is less likely to occur) instead of uranium 238 (²³⁸Since the neutron absorption rate of the parent nuclide material such as U) is large, uranium 238 (²³⁸U) plutonium 239 (²³⁹A fissile material such as Pu) is easily generated (converted). That is, the conversion ratio tends to be large. Conversely, if the neutron spectrum is soft (shifts to the lower energy side), uranium 235 (²³⁵Since the reactivity of the fuel material such as U) is high (fission is likely to occur), the fissionable material is hardly generated. That is, the conversion ratio tends to be small.
[0032]
In the present invention, the degree of burnup of the fuel spheres discharged from the reactor core is detected by the detection means, and the radial introduction position when the fuel sphere is re-introduced is distributed by the first distribution means according to the detection result. At the same time, the first derivation means can switch the deceleration sphere mixing ratio to a plurality of values while setting the deceleration sphere to be derived, and the second allocating means can change the radial direction when the deceleration sphere is re-introduced for each set value. Sort the input position. In this way, the average burnup of all the fuel balls in one region out of the radially inner region and the outer region of the core becomes larger than the average burnup of all the fuel balls in the other region, It is possible to realize a reactor core in which the number density of speed reducing spheres in this area is larger than the number density of speed reducing spheres in the other area. That is, in the other region, where the average burnup is relatively small, the conversion of fissionable material in the fuel sphere is promoted by making the hard neutron spectrum with relatively few decelerating spheres. In one region, which is a relatively late combustion period, a soft neutron spectrum with a relatively large number of deceleration spheres is used to promote the combustion of the fissionable material converted and produced earlier. Thus, fuel economy can be greatly improved by promoting the reaction of the fissionable material increased by being generated in the early stage of combustion in the late stage of combustion (spectrum shift effect). At this time, the output of the nuclear fuel usually decreases with combustion as described in the above (1), but the decrease in the output can be moderated by this spectral shift effect.
[0033]
On the other hand, when performing spectral shift operation in this way, from the viewpoint of flattening the radial output, either the average burnup distribution of the fuel spheres or the number density of the deceleration spheres has a dominant influence on the core power. There are two methods depending on the situation. If the average burnup distribution is dominant, the average burnup of all fuel balls in the inner radial region of the core is set to be larger than the average burnup of all fuel balls in the outer region. The number density of the speed reduction spheres is made larger than the number density of the speed reduction spheres in the outer region). Thereby, the core radial direction output can be flattened in the same manner as in the above (1). If the number density of the deceleration spheres is dominant, the number density of the deceleration spheres in the outer area is made larger than the number density of the deceleration spheres in the inner area (in addition, the average burnup of all the fuel balls in the outer area) Is greater than the average burnup of all fuel balls in the inner region). Thereby, the core radial output can be flattened in the same manner as in the above (7).
[0034]
(11) In order to achieve the above object, the nuclear reactor facility according to the present invention includes a large number of large particle size fuel spheres and relatively large particles discharged from a pebble bed type reactor core. A plurality of small particle size fuel spheres having a small diameter are introduced, and the small particle size fuel spheres can be derived so that the mixing ratio of the small particle size fuel spheres occupying the entire fuel sphere is switched to a plurality of values. 2 and the introduction position in the radial direction when the small particle diameter fuel sphere derived from the second derivation means is reintroduced into the reactor core for each set value of the mixture ratio of the small particle diameter fuel spheres. And a third sorting means for sorting.
[0035]
In the present invention, the small particle size fuel sphere is derived by switching the setting ratio of the small particle size fuel spheres to a plurality of values by the second deriving unit, and the small particle size fuel for each set value by the third distribution unit. Sort the radial throwing position when refilling the ball. In this way, for example, a core in which the number density of small particle size fuel spheres in the inner region of the reactor core is smaller than the number density of small particle size fuel spheres in the outer region can be realized. As a result, the fuel filling rate on the outer side of the core can be increased and the amount of fuel loaded can be relatively increased. Therefore, as in the above (1) and (7), the output of the outer region in the core radial direction is relatively higher than the inner region. Therefore, it is possible to relieve the tendency of the power around the center of the core to become large and to flatten the power in the radial direction of the core. In the present invention, since the core is composed only of fuel balls, PBMR in which only the deceleration spheres are loaded on the inner side in the core radial direction so as to flatten the radial output, or graphite on the inner side in the core radial direction. The number of fuel balls can be increased as compared with the prior art loaded with large-diameter fuel balls with a larger proportion of By these two, the maximum power burden per fuel ball can be relatively lowered and the power per core can be increased, so that the economic efficiency of the entire reactor can be improved. In addition, since the inside of the core is composed of only the fuel balls, the fuel loading amount of the entire core becomes larger than that of the conventional technique using the deceleration sphere, and in particular, in the outer region by increasing the fuel loading amount outside the core. The number of years that the fuel stays in the furnace can be increased, and the fuel economy is improved. Accordingly, the economic efficiency of the entire nuclear reactor can be improved also by this.
[0036]
(12) In the above (11), preferably, the third distribution unit is configured such that the large particle size fuel sphere and the small particle size fuel sphere in the radial direction have a relatively large mixing ratio of the small particle size fuel spheres. The charging position is assigned to the outside in the radial direction, and the charging position in the radial direction of the group of the large particle size fuel sphere and the small particle size fuel ball having a relatively small mixing ratio of the small particle size fuel sphere is assigned to the inside in the radial direction.
[0037]
(13) In order to achieve the above object, the nuclear reactor facility according to the present invention includes a large number of mixed oxide fuel spheres using uranium / plutonium mixed oxide discharged from a pebble bed type reactor core as a nuclear fuel material, and Introducing a large number of uranium fuel spheres with uranium oxide as nuclear fuel material, and deriving the mixed oxide fuel spheres so that the mixing ratio of the mixed oxide fuel spheres occupying the entire fuel sphere is switched to multiple values. The possible third derivation means, and the radial introduction position when the mixed oxide fuel sphere derived from the third derivation means is reintroduced into the reactor core, are expressed by the mixing ratio of the mixed oxide fuel spheres. And fourth distribution means for distributing each set value.
[0038]
In the present invention, the mixed oxide fuel spheres are derived by switching the setting ratio of the mixed oxide fuel spheres occupying the entire fuel sphere to a plurality of values by the third deriving means, and each set value is obtained by the fourth distributing means. The radial injection position at the time of re-injection of the mixed oxide fuel sphere is assigned to.
[0039]
Here, in general, in a pebble bed type reactor, neutrons are gradually decelerated by graphite having a small absorption cross section, so that the probability of escaping resonance is smaller than in a light water reactor. Therefore, the nuclear fuel material is a mixed oxide (MOX) of depleted uranium (U) and plutonium (Pu), and the isotope composition of plutonium (Pu) is the parent nuclide plutonium 240 (²⁴⁰In the case of containing a relatively large amount of Pu), even if the enrichment of plutonium (Pu) (Pu / (Pu + U)) is relatively large, the rate of increase in reactivity remains at a relatively small value. That is, when the plutonium (Pu) contained in the mixed oxide is plutonium (Pu) obtained by reprocessing spent fuel of a nuclear reactor such as a light water reactor, the reactivity of the mixed oxide fuel sphere is It tends to be smaller than the uranium fuel sphere that uses uranium oxide as a nuclear fuel material.
[0040]
In the present invention, by configuring as described above, for example, a core in which the number density of mixed oxide fuel spheres in the inner region of the reactor core is larger than the number density of mixed oxide fuel spheres in the outer region. Can be realized. As a result, similarly to the above (1), the power in the outer region in the core radial direction is increased relative to the inner region, and the tendency to increase the power in the vicinity of the normal core center is alleviated. The output can be flattened. In the present invention, since the core is composed only of fuel balls, PBMR in which only the deceleration spheres are loaded on the inner side in the core radial direction so as to flatten the radial output, or graphite on the inner side in the core radial direction. The number of fuel balls can be increased as compared with the prior art loaded with large-diameter fuel balls with a larger proportion of By these two, the maximum power burden per fuel ball can be relatively lowered and the power per core can be increased, so that the economic efficiency of the entire reactor can be improved.
[0041]
In addition, as described above, since the inside of the core is composed of only the fuel balls, the amount of fuel loaded in the entire core becomes larger than that of the conventional technology using the deceleration sphere, and the spent fuel of the nuclear reactor such as a light water reactor is further increased. By reusing plutonium obtained by reprocessing, it is possible to save uranium fuel, thereby improving fuel economy. Accordingly, the economic efficiency of the entire nuclear reactor can be improved also by this.
[0042]
(14) In the above (13), it is preferable that the fourth distributing means is a radial insertion position of the group of the mixed oxide fuel sphere and the uranium fuel sphere having a relatively large mixing ratio of the mixed oxide fuel sphere. Are distributed radially inward, and the positions of the mixed oxide fuel spheres and uranium fuel spheres in which the mixing ratio of the mixed oxide fuel spheres is relatively small are distributed radially outward.
[0043]
(15) In order to achieve the above object, according to the present invention, in a pebble bed type reactor core configured by inserting a large number of fuel balls into the inside from the upper part of the vessel, the inside of the vessel is radially When the inner area and the outer area are divided so as to have an equal area, the average burnup of all the fuel balls in the inner area is larger than the average burnup of all the fuel balls in the outer area. Insert the fuel ball.
[0044]
(16) In order to achieve the above object, the present invention also provides a pebble bed type reactor core configured by introducing a number of fuel balls and deceleration balls into the interior from the top of the container. When the fuel ball is divided into an inner region and an outer region so as to be equal to each other in the radial direction, the number of deceleration spheres in the inner region is smaller than the number density of the reduction spheres in the outer region. And the deceleration ball is inserted.
[0045]
(17) In the above (16), preferably, a plurality of mixed layers in which the fuel spheres and the speed reducing spheres are substantially uniformly mixed are formed in the container in the radial direction at different mixing ratios. The fuel ball and the deceleration ball are inserted.
[0046]
(18) In order to achieve the above object, the present invention also provides a pebble bed type reactor core configured by introducing a large number of fuel balls and deceleration balls into the interior from the top of the container. When it is divided into two regions of an inner region and an outer region so as to have the same area in the radial direction, the average burnup of all fuel balls in one region is greater than the average burnup of all fuel balls in the other region. And the fuel spheres and the deceleration spheres are introduced so that the number density of the deceleration spheres in the one region is larger than the number density of the deceleration spheres in the other region.
[0047]
  (19) In the above (18), preferably, the average burnup distribution depends on which of the average burnup distribution of the fuel balls and the number density of the deceleration balls has a dominant influence on the core power. Is the inner region and the other region is the outer region, and when the number density of the decelerating spheres is dominant, the one region is The outer region, andotherThis area is defined as the inner area.
[0048]
  (20) Above (18)Preferably, the one region is the inner region, and the other region is the outer region.
[0049]
  (21) Above (18)Preferably, the one region is the outer region,otherThis area is defined as the inner area.
[0050]
  (22) In order to achieve the above object, the present invention also provides a large number of large particle size fuel spheres having a relatively large particle size and a large number of small particle size fuels having a relatively small particle size from the top to the inside of the container. In a pebble bed type reactor core constructed by introducing spheres, when the inside of the vessel is divided into an inner region and an outer region so as to have an equal area in the radial direction,To introduce the large particle size fuel and the small particle size fuel sphere into both the outer region and the inner region, and to increase the fuel filling rate of the outer region than the inner region,The number density of the small particle size fuel spheres in the inner region is smaller than the number density of the small particle size fuel spheres in the outer region.Do.
[0051]
(23) In order to achieve the above object, the present invention also provides a large number of mixed oxide fuel spheres containing uranium / plutonium mixed oxide as a nuclear fuel material and a large number of uranium oxides as nuclear fuel material. In the pebble bed type reactor core constructed by introducing the uranium fuel balls of the vessel, when the inside of the vessel is divided into an inner region and an outer region so as to be equal to each other in the radial direction, The mixed oxide fuel sphere and the uranium fuel sphere are introduced so that the number density of the mixed oxide fuel sphere is smaller than the number density of the mixed oxide fuel sphere in the outer region.
[0052]
(24) In the above (23), preferably, the plutonium contained in the uranium / plutonium mixed oxide is obtained by reprocessing spent fuel in a nuclear reactor.
[0053]
(25) In order to achieve the above object, according to the operation method of the present invention, the burnup of the fuel sphere discharged from the pebble bed type reactor core is detected, and the fuel sphere is placed in the fuel sphere according to the detection result. The radial injection position when re-entering the reactor core is assigned.
[0054]
  (26) In order to achieve the above object, the operation method of the present invention is a fuel ball to be introduced into a pebble bed type reactor core.WhenDeceleration ballWithWhen the mixing ratio of the speed reduction spheres in the whole is switched to a plurality of values, the speed reduction sphere is re-injected into the reactor core.Nuclear reactorThe position in the radial direction is assigned for each set value of the mixing ratio of the deceleration balls.
[0055]
(27) In the above (26), preferably, the injection position of the fuel sphere having a relatively high burnup is distributed to one of the radially inner side and the outer side, and the fuel sphere having a relatively low burnup is provided. The charging position is assigned to the other of the radially inner side and the outer side, and the setting position of the deceleration sphere when the setting value of the mixing ratio is relatively large is assigned to the one radial side, and the setting value of the mixing ratio Is placed to the other side in the radial direction.
[0056]
  (28) In order to achieve the above object, the operation method of the present invention is a large particle fuel sphere having a relatively large particle size and a relatively small particle size to be charged into a pebble bed type reactor core. Switch the mixture ratio to the whole fuel sphere consisting of small particle spheres to multiple values,At least the large particle size fuel sphere of the large particle size fuel sphere and the small particle size fuel sphereThe radial injection position when re-injecting the reactor into the reactor core is assigned to each set value of the mixing ratio of the small particle size fuel spheres.The fuel filling rate of the outer region is higher than that of the inner region.
[0057]
(29) In order to achieve the above object, the operation method of the present invention is a mixed oxide fuel sphere and uranium oxide having a uranium / plutonium mixed oxide charged into a pebble bed reactor core as a nuclear fuel material. The mixing ratio of the mixed oxide fuel spheres occupying the entire fuel sphere composed of uranium fuel spheres having the nuclear fuel material as a nuclear fuel material is switched to a plurality of values, and the diameter when the mixed oxide fuel spheres are re-entered into the reactor core The direction injection position is assigned for each set value of the mixture ratio of the mixed oxide fuel balls.
[0058]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a reactor facility, a reactor core, and a reactor operating method according to the present invention will be described with reference to the drawings.
First, a first embodiment of a reactor facility, a reactor core, and a reactor operating method according to the present invention will be described below with reference to FIGS.
[0059]
FIG. 1 is a side sectional view schematically showing the entire structure of a nuclear reactor provided with a first embodiment of a nuclear reactor core according to the present invention, and FIG. 2 is a transverse sectional view taken along line II-II in FIG. is there. 1 and 2, the nuclear reactor shown in the figure is a pebble bed type nuclear reactor, and a large number of fuel balls 3 are loaded in a core 2 housed in a nuclear reactor vessel 1.
[0060]
For example, the core 2 has a diameter of 3.5 m and a height of 8.5 m, and the ratio of the core height to the core diameter is 2.4. The upper portion, lower portion, and periphery of the core 2 are covered with a reflector 4 made of graphite blocks (only the space for loading the reflector 4 is shown in FIG. 1) so as to minimize the amount of neutron leakage to the outside. It has become.
[0061]
Further, the control material operating mechanism 5 that controls the reactivity of the reactor core 2 at the time of start-up, shut-down, and transition is penetrated through the upper mirror part 1a of the reactor vessel 1 so as to surround the reactor core 2 in the circumferential direction. It is disposed at a plurality of positions (see FIG. 2).
[0062]
Further, a coolant inlet pipe 6 and a coolant outlet pipe 7 are connected to the upper and lower parts of the core 2, respectively. Through this coolant inlet pipe 6, helium as a coolant flows into the core 2 from the upper part of the core 2, is heated in the core 2, and passes through the coolant outlet pipe 7 from the lower part of the core 2 to the turbine ( (Not shown). Thereafter, the helium returned from the turbine flows into the core 2 again through the coolant inlet pipe 6.
[0063]
The fuel sphere 3 has a diameter of about 6 cm, and in the same manner as the conventional one described above, for example, a fuel region composed of a large number of coated fuel particles containing uranium oxide as a nuclear fuel material and a graphite matrix containing the particles. The structure is surrounded by graphite shells.
[0064]
In the nuclear reactor thus configured, in the present embodiment, the burnup of the fuel ball 3 taken out from the lower part of the core 2 is measured, and the predetermined burnup is achieved, as in the MEDUL method or the multipass method described above. For the fuel balls 3 that have not reached, the operation system is used to return them to the core 2 again. The reactor equipment for performing such operation will be described below.
[0065]
FIG. 3 is a conceptual diagram showing the overall configuration of the first embodiment of the nuclear reactor facility of the present invention. In FIG. 3, a solid line (thick line) arrow indicates the flow of the fuel ball 3, and a broken line arrow indicates the signal flow.
[0066]
In FIG. 3, the reactor facility includes a core 2 loaded with a large number of fuel balls 3, a fuel ball input pipe 8, a singulated pipe 9, a sorter 10, a damaged fuel storage 11, and a buffer pipe 12. A burn-up detector 13 for detecting the burn-up of the fuel ball 3, a take-out fuel storage 14, a fuel input device 15, and a switcher 16 for switching a lead-out route to the take-out fuel storage 14 or the fuel input device 15. , A new fuel storage 17, a new fuel loading facility 18, and a process computer 19.
[0067]
The burnup detector 13 detects the burnup of the fuel sphere 3 by detecting the amount of radiation emitted from the fission product (FP) contained in the fuel sphere 3.
[0068]
The process computer 19 receives information on the burnup of each fuel sphere 3 from the burnup detector 13, and sends the fuel sphere 3 whose input burnup reaches a predetermined burnup to the extracted fuel storage 14. The switch 16 is controlled so that the fuel ball 3 that has been derived and the input burnup does not reach the predetermined burnup is led to the fuel injector 15. Further, the process computer 19 controls the new fuel loading equipment 18 in accordance with signals such as reactivity, power distribution and the like input from various in-core measuring devices (not shown) provided in the core 2, for example. A new fuel ball 3 is taken out from the new fuel storage 17 and inserted into the burnup detector 13.
[0069]
In this way, new fuel balls 3 having the same amount as the fuel balls 3 that have reached the predetermined burn-up and are taken out together with the fuel balls 3 that have not reached the predetermined burn-up are again thrown into the core 2. ing.
[0070]
In the nuclear reactor core of the present invention having the basic configuration as described above and the nuclear reactor equipment equipped with the same, the greatest feature of the present embodiment is that when the fuel ball 3 is reintroduced into the core 2, the inner region B That is, the average burnup of all the fuel balls 3 in is increased to be greater than the average burnup of all the fuel balls 3 in the outer region A. The details will be described below.
[0071]
Returning to FIG. 1, the fuel ball introduction pipe 8 is composed of an outer introduction pipe 8a and an inner introduction pipe 8b, and the outer and inner introduction pipes 8a and 8b have the respective inlets 8a1 and 8b1 at the core 2. Are provided so as to have different radial positions in the upper part of each other. That is, the outer charging tube 8 a is provided so as to introduce the fuel ball 3 into a relatively radially outer region of the core 2, and the inner charging tube 8 b is disposed in a relatively radially inner region of the core 2. Is provided.
[0072]
4 is a cross-sectional view taken along the line IV-IV in FIG. In FIG. 4 and FIG. 1 described above, the outer charging pipes 8a are disposed, for example, at four locations every 90 degrees in the circumferential direction of the reactor core 2 and penetrate the lower mirror portion 1b from the lower side of the reactor vessel 1 to the reactor. Along the inner peripheral surface of the vessel 1 is provided up to above the top plate 2a of the core 2, bent from there and extended substantially parallel to the top plate 2a toward the center of the core 2 in the radial direction, and from there It is bent so as to pass through the top plate 2a from the upper side to the lower side so as to lower the inlet 8a1 in a relatively radially outer region of the core 2.
[0073]
On the other hand, the inner charging tube 8b is arranged at four positions, for example, every 90 degrees in the circumferential direction of the core 2 at a position shifted by 45 degrees from the outer charging tube 8a. From the lower side, it penetrates the lower mirror part 1b, is erected up to the top of the top plate 2a of the core 2 along the inner peripheral surface of the reactor vessel 1, is bent, and is centered in the radial direction of the core 2 substantially parallel to the top plate 2a It extends longer than the outer charging pipe 8a, and further bends so as to penetrate the top plate 2a downward from above and lower the charging port 8b1 in a relatively radially inner region of the core 2. Is provided.
[0074]
At this time, the fuel injector 15 for injecting the fuel ball 3 into the core 2 through the outer and inner input tubes 8a and 8b is similar to the fuel ball input tube 8, for example, with four outer injectors 15a. It is comprised by the four inner side insertion devices 15b. These outer and inner charging devices 15a and 15b are connected to outer and inner charging tubes 8a and 8b, respectively (see FIG. 3; however, in FIG. 3, two outer charging devices 15a and two inner charging devices are used to prevent congestion. Only one feeder 15b is shown).
[0075]
Further, the process computer 19 controls the switch 16 as described above to lead the fuel ball 3 whose burnup has not reached the predetermined burnup to the fuel injector 15 at this time. Further, the switch 16 is controlled so that the fuel balls 3 having a relatively low burnup are distributed to the outer charger 15a, and the fuel balls 3 having a relatively high burnup are distributed to the inner charger 15b. Note that the switch 16 is controlled so that all of the new fuel balls 3 sent from the new fuel loading facility 18 are distributed to the outer charging device 15a.
[0076]
Due to such a structure of the reactor equipment, in the present embodiment, the fuel ball 3 having a relatively low burnup is burned in a relatively outer region of the core 2 by the outer injector 15a via the outer injector tube 8a. The fuel ball 3 having a relatively high degree is introduced into the relatively inner region of the core 2 by the inner injector 15b via the inner injector tube 8b, and as shown by the broken line in FIG. Is divided into a radially outer region A and an inner region B so that they have the same area, the average burnup of all fuel balls 3 in the inner region B is equal to the average burnup of all fuel balls 3 in the outer region A. It is possible to drive while making it larger.
[0077]
In the above, the burnup detector 13 constitutes a detecting means for detecting the burnup degree of the fuel ball described in the claims. Further, the switcher 16 constitutes a switching unit that switches the fuel ball derivation path for which the burnup has been detected by the detecting unit, and the fuel ball injection tube 8 has radial ends that are different from each other in the upper part of the reactor core. The switch 16, the fuel injector 15, and the process computer 19 are configured to selectively introduce the fuel sphere into the plurality of fuel sphere supply pipes. The fuel introduction device 15, the switching device 16, the process computer 19, and the fuel ball introduction pipe 8 constitute a selective introduction means, and the first introduction of the radial introduction position when the fuel ball is introduced again into the reactor core. The distribution means is configured.
[0078]
Next, the operation and action of the first embodiment of the nuclear reactor equipment of the present invention having the above-described configuration will be described below.
The fuel balls 3 loaded in the core 2 are continuously moved from the upper part to the lower part in the core 2 as the nuclear reactor is operated, and are selected one by one by the single tube 9 provided at the lower part of the core 2. Sent to the vessel 10. The fuel balls 3 detected as damaged by the selector 10 are sent to the damaged fuel storage 11, and the fuel balls 3 whose damage was not detected are sent to the burnup detector 13 via the buffer pipe 12.
[0079]
In this burn-up detector 13, each fuel ball 3 detects its burn-up, and information on the burn-up is output as a signal to the process computer 19. The process computer 19 controls the switch 16 so that the fuel ball 3 is taken out to the fuel storage 14 when the detected burnup reaches a predetermined burnup. As a result, the fuel ball 3 that has reached a predetermined burnup is sent to the removed fuel storage 14.
[0080]
On the other hand, when the detected burnup does not reach the predetermined burnup, the process computer 19 introduces the fuel balls 3 having a relatively low burnup out of the fuel balls 3 to the outer charger 15a. The switch 16 is controlled so that the fuel ball 3 having a relatively high burnup is led out to the inner charger 15b. As a result, among the fuel balls 3 that have not reached the predetermined burn-up, the relatively low burn-up fuel balls 3 are moved from the outer charger 15a to the relatively outer region in the core 2 through the outer injector 8a. The fuel balls 3b having a relatively high burnup are recharged to the relatively inner region in the core 2 through the inner charge tube 8b from the inner charge device 15b.
[0081]
Thus, according to the present embodiment, when the inside of the core 2 is divided as described above, the average burnup of all the fuel balls 3 in the inner region B is equal to all the fuel balls in the outer region A. Therefore, it is possible to realize the core 2 that is larger than the average burnup of 3. As a result, the output of the outer region A of the core 2 can be increased relative to the inner region B, the tendency of the output near the center of the core to be increased, and the core radial output can be flattened.
[0082]
Further, in the present embodiment, because the inside of the core 2 is composed of only the fuel balls 3, the above-described PBMR in which only the deceleration spheres are loaded on the inner side in the core radial direction and the radial output is flattened, The number of fuel balls 3 loaded in the core 2 can be increased as compared with the prior art in which large-diameter fuel balls with a large proportion of graphite contained inside the core diameter direction are loaded.
[0083]
In this way, by increasing the number of loaded fuel balls 3 while flattening the radial output in the core 2, the maximum output burden per fuel ball 3 can be relatively lowered. . As a result, the output per core 2 can be increased as much as possible by raising the maximum output per ball to the limit value within the range where the soundness of the fuel ball 3 can be maintained. Therefore, the economic efficiency of the entire reactor can be improved.
[0084]
Furthermore, in the present embodiment, as described above, since the amount of fuel loaded in the entire core is large as compared with the above-described conventional technique using the reduction sphere, fuel economy is improved. Therefore, the effect of improving the economic efficiency as seen in the whole reactor can be obtained also by this.
[0085]
In the first embodiment of the present invention, the description has been made on the assumption that the core 2 is a balanced core. However, for example, when the core 2 is initially loaded, all the fuel balls 3 to be loaded are loaded. Because of the new fuel ball, there is a tendency for a high power peak to occur in the center of the core. Furthermore, since the burnup detected by the burnup detector 13 is substantially the same in the initial stage, it is difficult to set the re-feeding standard in the process computer 19. In order to avoid this, two or more types of fuel balls 3 having different enrichments may be used when the core 2 is initially loaded. That is, a highly enriched fuel sphere 3 is arranged in the outer region A, and a low enriched fuel sphere 3 is arranged in the inner region B, so that the enrichment as well as the burnup is detected in the lower part of the core. The fuel spheres 3 with high reactivity may be reintroduced into the outer region A, and the fuel spheres with low reactivity may be reintroduced into the inner region B. Thereby, even when the core 2 is initially loaded, the same effect as that of the first embodiment can be obtained.
[0086]
Further, in the first embodiment of the present invention, only the fuel ball 3 is loaded in the core 2, but the present invention is not limited to this, and the fuel ball 3 may be mixed and loaded. This also makes it possible to flatten the core radial output.
[0087]
Next, a second embodiment of the reactor facility, the reactor core, and the operation method of the reactor according to the present invention will be described with reference to FIGS. In the present embodiment, a deceleration sphere is used to make the mixing ratio of the fuel sphere 3 in the outer region C and the deceleration sphere occupying the entire reduction sphere relatively larger than that in the inner region D.
[0088]
FIG. 5 is a conceptual diagram showing the overall configuration of the second embodiment of the nuclear reactor facility of the present invention. In FIG. 5, the thick black arrow indicates the flow of the fuel sphere 3, the white arrow indicates the flow of the deceleration sphere 20, the gray arrow indicates the flow of the mixture of the fuel sphere 3 and the deceleration sphere 20, and a broken line. The arrows indicate the signal flow. In addition, the same code | symbol is attached | subjected to the part similar to FIG. 3 in the 1st Embodiment of the above-mentioned this invention, and description is abbreviate | omitted.
[0089]
In FIG. 5, the reactor facility is divided into a core 2 loaded with a large number of fuel balls 3 and deceleration balls 20, and an outer region C and an inner region D so that the inside of the core 2 has the same area in the radial direction. A fuel ball introduction pipe 8 'provided so that it can be introduced, a sorter 10' having a function of sorting the deceleration ball 20, a deceleration ball deriving device 21 for deriving the deceleration ball 20 at a predetermined pace, A switch 16 'having a function of mixing the deceleration sphere 20 derived from the deceleration sphere deriving device 21 with the fuel ball 3 is provided.
[0090]
The fuel ball introduction pipe 8 'can be provided with an outer introduction pipe 8a' provided so that the fuel ball 3 and the deceleration sphere 20 can be introduced into the outer area C, and with the fuel ball 3 and the deceleration sphere 20 in the inner area D. And an inner charging pipe 8b 'provided on the inside.
[0091]
The deceleration ball 20 is made of graphite and has the same size as the fuel ball 3. The decelerating sphere deriving device 21 and the switching device 16 'are controlled by a process computer 19, and a decelerating sphere deriving device for the fuel ball 3 sent from the burnup detector 13 to the switching device 16' at a constant pace. 21 can switch the pace at which the decelerating sphere 20 is sent to the switch 16 'in accordance with an instruction from the process computer 19, and the switch 16' mixes the fuel ball 3 and the decelerating sphere 20 and puts them outside. The device 15a or the inner charging device 15b is selected and sent. That is, when the pace of the deceleration sphere deriving device 21 is relatively fast and the mixing ratio of the deceleration spheres 20 occupying the entire fuel sphere 3 and the deceleration sphere 20 is large, the pace of the deceleration sphere deriving device 21 is relatively large in the outer thrower 15a. Slowly, when the mixing ratio of the deceleration spheres 20 occupying the entire fuel sphere 3 and the deceleration sphere 20 is small, the mixture is led out to the inner thrower 15b.
[0092]
In the above, the decelerating sphere deriving device 21 is capable of deriving the decelerating sphere so as to switch and set the mixing ratio of the decelerating sphere to the fuel sphere and the entire decelerating sphere as described in the claims. Configure the means. Further, the fuel injector 15, the switcher 16 ′, and the process computer 19 selectively introduce the fuel sphere and the deceleration sphere into the plurality of fuel sphere supply pipes according to the set value of the mixing ratio of the deceleration spheres. These means and the fuel ball introduction pipe 8 'constitute second distribution means for distributing the set values for the mixing ratio of the deceleration spheres.
[0093]
Next, the operation and action of the second embodiment of the nuclear reactor equipment of the present invention having the above configuration will be described below.
The mixture of the fuel spheres 3 and the speed reduction spheres 20 loaded in the core 2 continuously moves from the upper part to the lower part in the core 2 as the reactor operates, and a unitized tube provided at the lower part of the core 2 9 is sent one by one to the sorter 10 '. The sorter 10 ′ sorts the fuel sphere 3 and the deceleration sphere 20 and sends the deceleration sphere 20 to the deceleration sphere deriving device 21. On the other hand, the fuel ball 3 whose breakage is detected by the selector 10 ′ is sent to the broken fuel storage 11, and the fuel ball 3 whose breakage is not detected is sent to the burnup detector 13 via the buffer pipe 12.
[0094]
In this burn-up detector 13, each fuel ball 3 has its burn-up detected and sent to the switch 16 'at a constant pace. Here, the fuel ball 3 whose burnup detected by the burnup detector 13 has reached a predetermined burnup is led out to the take-out fuel storage 14 as in the first embodiment.
[0095]
At this time, under the control of the process computer 19, the decelerating sphere deriving device 21 increases the deriving pace of the decelerating sphere 20, so that the mixing ratio of the fuel sphere 3 and the decelerating sphere 20 occupying the entire decelerating sphere 20 in the switch 16 ′ When it becomes larger, the switch 16 'sends the mixture to the outer feeder 15a. On the other hand, when the decelerating sphere deriving device 21 delays the deriving pace of the decelerating sphere 20 and the mixing ratio of the decelerating sphere 20 in the switching unit 16 ′ becomes relatively small, the switching unit 16 ′ throws the mixture into the inside. To the container 15b. As a result, the mixture of the fuel spheres 3 and the deceleration spheres 20 having a relatively large mixing ratio of the deceleration spheres 20 is reintroduced into the outer region C in the reactor core 2 from the outer injector 15a through the outer injector tube 8a '. The mixture of the fuel sphere 3 and the deceleration sphere 20 having a relatively small mixing ratio of the deceleration sphere 20 is reintroduced into the inner region D in the core 2 from the inner injector 15b through the inner injection tube 8b '.
In the above nuclear reactor equipment, the speed reduction sphere 20 is re-introduced into the core 20 if there is no damage.
[0096]
Thus, according to the present embodiment, as shown in FIG. 6, the mixing ratio of the fuel spheres 3 in the outer region C and the deceleration spheres 20 occupying the entire deceleration sphere 20 is relatively larger than that in the inner region D. Core can be realized.
[0097]
As a result, as in the first embodiment described above, the output of the outer region C of the core 2 can be made relatively greater than the inner region D, and the core radial output can be flattened.
[0098]
In the present embodiment, since the injection positions are not distributed according to the burnup degree of the fuel balls 3, the initial loading of the core 2 as described in the modification of the first embodiment described above is performed. However, it is possible to cope with the distribution of the mixing ratio of the deceleration spheres 20, and it is not necessary to prepare fuel balls having different enrichments. Therefore, an effect of improving fuel economy can be obtained.
[0099]
In the second embodiment of the present invention described above, a group in which the mixing ratio of the speed reduction spheres 20 is large between the outer region C and the inner region D in which the inside of the core 2 is radially divided into equal areas, Although the small group is distributed and supplied via the outer and inner charging pipes 8a 'and 8b', the present invention is not limited to this. That is, as shown in FIG. 7, a group having a large mixing ratio and a group having a small reduction sphere 20 are distributed and supplied to the outer region C ′ and the inner region D ′, which are divided so as to have different areas. Good. Even in this case, when the inside of the core 2 is divided into the outer region C and the inner region D so as to have the same area in the radial direction, the above relationship is satisfied between the outer region C and the inner region D. As long as this is done, the same effects as those of the second embodiment of the present invention can be obtained.
[0100]
Next, a third embodiment of the reactor facility, the reactor core, and the operation method of the reactor according to the present invention will be described with reference to FIGS. 8 and 9 and FIG. 5 described above. In the present embodiment, the average burnup of all the fuel balls 3 in the outer region C is smaller than that in the inner region D, and the mixing of the fuel balls 3 in the outer region C and the deceleration balls 20 occupying the entire deceleration ball 20 is performed. The ratio is relatively smaller than the inner region D.
[0101]
The configuration of the third embodiment of the nuclear reactor according to the present invention is the same as the configuration described with reference to FIG. 5 in the second embodiment of the present invention, and the description thereof will be omitted.
[0102]
Next, the operation and action of the third embodiment of the reactor facility of the present invention will be described below.
The mixture of the fuel spheres 3 and the speed reduction spheres 20 loaded in the core 2 continuously moves from the upper part to the lower part in the core 2 as the reactor operates, and a unitized tube provided at the lower part of the core 2 9 is sent one by one to the sorter 10 '. Thereafter, in the same manner as in the second embodiment, the fuel sphere 3 and the deceleration sphere 20 are selected, the deceleration sphere 20 is sent to the deceleration sphere deriving device 21, and the detected fuel sphere 3 is damaged. The fuel ball 3 that has been sent to the fuel storage 11 and has not been detected as damaged is sent to the burnup detector 13 via the buffer tube 12. The fuel ball 3 whose burnup detected by the burnup detector 13 has reached a predetermined burnup is led to the extracted fuel storage 14 as in the first embodiment.
[0103]
At this time, under the control of the process computer 19, the deceleration sphere deriving device 21 operates the deceleration sphere deriving device 21 for the fuel sphere 3 having a relatively low combustion degree among the fuel spheres 3 whose detected burnup does not reach the predetermined burnup. 20 is slowed down so that the mixing ratio of the fuel sphere 3 and the speed reduction sphere 20 in the entire speed reduction sphere 20 in the switch 16 'becomes relatively small, and the switch 16' Send to 15a. On the other hand, for the fuel ball 3 having a relatively high burn-up among the fuel balls 3 whose detected burn-up has not reached the predetermined burn-up, the decelerating ball deriving device 21 increases the deriving pace of the decelerating ball 20. The mixing ratio of the decelerating sphere 20 in the switching device 16 ′ is made relatively large, and the switching device 16 ′ sends the mixture to the inner charging device 15b.
As a result, the mixture of the fuel sphere 3 and the speed reduction sphere 20 having a relatively small burnup of the fuel sphere 3 and a relatively small mixing ratio of the speed reduction sphere 20 is transferred from the outer input device 15a through the outer input tube 8a '. The mixture of the fuel sphere 3 and the deceleration sphere 20 is re-introduced into the outer region C in the reactor core 2 and the combustion degree of the fuel sphere 3 is relatively large and the mixing ratio of the deceleration sphere 20 is relatively large. The vessel 15b is recharged into the inner region D in the core 2 through the inner charging tube 8b '.
[0104]
Thus, according to the present embodiment, as shown in FIG. 8, the average burnup of all the fuel balls 3 in the outer region C is smaller than that in the inner region D, and the fuel balls and deceleration balls in the outer region C are used. It is possible to realize a reactor core in which the mixing ratio of the speed reduction balls occupying the whole is relatively smaller than that of the inner region D.
[0105]
Here, normally, the average burnup distribution of the fuel balls 3 has a dominant influence on the output of the core 2 rather than the number density of the deceleration balls 20. That is, as in the present embodiment, the mixing ratio of the deceleration sphere 20 is relatively small with respect to the fuel sphere 3 having a small average burnup (the former), and the deceleration sphere 20 is compared with the fuel sphere 3 having a large average burnup. Even in a configuration in which the mixing ratio is relatively large (the latter), the former still tends to have a higher output.
[0106]
According to the present embodiment, since the former in which the output is increased is arranged in the outer region C in the core 2 by adopting the above-described core configuration, as in the first embodiment of the present invention described above, It is possible to alleviate the tendency for the output near the center of the core to increase and to flatten the output in the core radial direction.
[0107]
Further, by adopting the above-described core configuration, the fissile material in the fuel sphere 3 is obtained by forming a hard neutron spectrum with relatively few decelerating spheres 20 in the outer region C where the average burnup is relatively small. In the inner region D, which is the late stage of combustion with a relatively high average burnup, the soft neutron spectrum with a relatively large number of decelerating spheres 20 is used, so that the fissile material that has been converted and generated earlier is promoted. Can promote combustion. In this way, the fuel economy can be greatly improved by the spectrum shift effect by promoting the reaction of the fissile material increased by the conversion generated in the early stage of combustion in the late stage of combustion.
[0108]
In the third embodiment of the present invention, the description has been made on the assumption that the core 2 is a balanced core. However, for example, when the core 2 is initially loaded, all the fuel balls 3 to be loaded are loaded. Is a new fuel ball and the mixing ratio of the speed reduction spheres 20 in the inner region D is large, the tendency to generate a high output peak at the center of the core becomes even stronger. In order to avoid this, two or more types of fuel balls 3 having different enrichments may be used when the core 2 is initially loaded, as in the first embodiment of the present invention described above. Thereby, even when the core 2 is initially loaded, the same effect as that of the third embodiment can be obtained.
[0109]
Further, in the third embodiment of the present invention, the burnup of the fuel spheres 3 is small and decelerated into an outer region C and an inner region D that are divided in the core 2 so as to have the same area in the radial direction. A group having a small mixing ratio of the spheres 20 and a group having a large burnup ratio of the fuel spheres 3 and a large mixing ratio of the deceleration spheres 20 are distributed and supplied via the outer and inner charging pipes 8a and 8b. That is, as described in the second embodiment of the present invention described above, the fuel balls 3 are distributed so as to have different areas, so that the burnup of the fuel balls 3 is small and the mixing ratio of the deceleration balls 20 is small. You may make it supply a small group and a group with a large burnup of the fuel ball | bowl 3, and a large mixing ratio of the deceleration ball | bowl 20. FIG. Even in this case, when the inside of the core 2 is divided into the outer region C and the inner region D so as to have the same area in the radial direction, the above relationship is satisfied between the outer region C and the inner region D. As long as this is done, the same effect as in the third embodiment of the present invention can be obtained.
[0110]
In the third embodiment of the present invention, it is assumed that the average burnup distribution of the fuel balls 3 has a dominant influence on the output of the core 2 rather than the number density of the deceleration balls 20. The average burnup of all the fuel balls 3 in the outer region C of the core 2 is smaller than that in the inner region D, and the mixing ratio of the fuel balls 3 in the outer region C and the deceleration balls 20 occupying the entire deceleration ball 20 is larger than that in the inner region D. However, the present invention is not limited to this. For example, when the number of the deceleration spheres 20 is relatively large, the number density of the deceleration spheres 20 is higher than the average burnup distribution of the fuel spheres 3. If the output is dominantly affected, the arrangement may be reversed. That is, as shown in FIG. 9, the average burnup of all the fuel balls 3 in the outer region C is larger than that in the inner region D, and the mixing ratio of the fuel balls 3 in the outer region C and the deceleration balls 20 occupying the entire deceleration ball 20. May be configured to be relatively larger than the inner region D. As a result, the same effects as those of the third embodiment can be obtained, and the radial output can be flattened without using the fuel balls 3 having different enrichments even when the core 2 is initially loaded. Therefore, fuel economy can be further improved.
[0111]
In the second embodiment and the third embodiment described above, the selector 10 'performs the selection of the fuel sphere 3 and the deceleration sphere 20. However, the fuel sphere 3 is not limited to this. The burn-up detector 13 may be provided with a function for selecting the deceleration ball 20.
[0112]
Next, a fourth embodiment of a reactor facility, a reactor core, and a reactor operating method according to the present invention will be described with reference to FIGS. 10 and 11. In the present embodiment, a large-diameter fuel sphere having a relatively large particle diameter and a small-diameter fuel sphere having a relatively small particle diameter are used. The mixture is charged and only the large particle diameter fuel sphere is charged into the inner region D.
[0113]
FIG. 10 is a conceptual diagram showing the overall configuration of the fourth embodiment of the nuclear reactor facility of the present invention. In FIG. 10, the black thick arrow indicates the flow of the large particle size fuel sphere 3a, the white arrow indicates the flow of the small particle size fuel sphere 3b, and the gray arrow indicates the large particle size fuel sphere 3a and the small particle size fuel sphere. 3b shows a mixed flow, and a broken arrow indicates a signal flow. In addition, the same code | symbol is attached | subjected to the part similar to FIG. 5 in the above-mentioned 2nd Embodiment of this invention, and description is abbreviate | omitted.
[0114]
In FIG. 10, the nuclear reactor facility includes a core 2 loaded with a large number of large particle size fuel spheres 3a and small particle size fuel balls 3b, and a classifier 10 ″ having a function of selecting the small particle size fuel balls 3b. A small particle size burnup detector 22 for detecting the burnup of the small particle size fuel ball 3b, a small particle size fuel ball deriving device 23 for deriving the small particle size fuel ball 3b at a predetermined pace, and the small particle size A switch 16 ″ having a function of mixing the small particle size fuel sphere 3b derived from the diameter fuel sphere deriving device 23 with the large particle size fuel sphere 3a, and a large particle size serving as a storage for the new large particle size fuel sphere 3a. New fuel storage 17a, a new large particle size fuel sphere 3a that is loaded into the burnup detector 13, and a new small particle size fuel sphere 3b. The new fuel storage 17b and the new small particle size fuel sphere 3b are connected to the small particle size burn-up detector 22 described above. And a small diameter contouring new fuel loading facility 18b to be introduced.
[0115]
Like the fuel sphere 3, the large particle sphere 3a and the small particle sphere 3b are each composed of, for example, a large number of coated fuel particles containing uranium oxide as a nuclear fuel material and a graphite matrix containing them. The formed fuel region is surrounded by a graphite shell. At this time, the diameters of the large and small particle diameter fuel balls 3a and 3b are respectively d₁, D₂Then, this d₁And d₂For example d₂≦ (2√3 / 3−1) d₁There is a relationship that satisfies. As a result, the small particle diameter fuel spheres 3b can enter the gaps between the densely arranged large particle diameter fuel spheres 3a. The diameter d of the large particle size fuel sphere 3a₁Is about 6 cm as in the conventional case.
[0116]
The burnup detector 13 and the burnup detector 22 for small particle size detect the burnup of the large and small particle size fuel balls 3a and 3b sorted by the sorter 10 ″ and output them to the process computer 19. The process computer 19 controls the switch 16 ″ so that the large and small particle size fuel balls 3a and 3b whose input burnup reaches a predetermined burnup are taken out and sent to the fuel storage 14. It has become.
[0117]
On the other hand, the large and small particle size fuel balls 3a and 3b whose burnup level does not reach the predetermined burnup level are transferred to the large particle size fuel ball 3a sent from the burnup level detector 13 to the switch 16 ″ at a constant pace. On the other hand, the small particle size fuel sphere deriving device 23 can switch the pace at which the small particle size fuel spheres 3b are sent to the switch 16 ″ in accordance with an instruction from the process computer 19, and these large particle size fuel spheres 3a and 3 The switch 16 ″ mixes the small particle size fuel spheres 3b and sends them to the outer input device 15a or the inner input device 15b. That is, the large particle size fuel spheres 3a and the small particle size fuel spheres 3b are entirely fed. The mixing ratio of the occupying small particle size fuel spheres 3b can be switched to a plurality of values, which can be selected and sent to the outer feeder 15a or 15b (however, in this embodiment, the inner charging is performed) Place to send to vessel 15b Mixing ratio 0, i.e. only large 径燃 fee balls 3a sent from burn detector 13 is adapted to be fed into the inner insertion unit 15b is).
[0118]
In the above, the small particle size fuel sphere deriving device 23 sets the small particle size fuel sphere so that the mixing ratio of the small particle size fuel spheres occupying the entire fuel sphere described in the claims is switched to a plurality of values. Derivable second deriving means is configured. In addition, the fuel ball input pipe 8 ', the fuel input device 15, the switching device 16 ", and the process computer 19 constitute third distribution means that distributes for each set value of the mixing ratio of the small particle size fuel balls.
[0119]
Next, operation | movement and an effect | action of 4th Embodiment of the nuclear reactor equipment of this invention of the said structure are demonstrated below.
The large particle size fuel spheres 3a and the small particle size fuel spheres 3b loaded in the reactor core 2 are continuously moved from the upper part to the lower part in the reactor core 2 along with the operation of the nuclear reactor, and are provided in the lower part of the reactor core 2. Balls are sent one by one to the sorter 10 "by the unified tube 9. In this sorter 10", the broken one of the large particle size fuel sphere 3a and the small particle size fuel sphere 3b is sorted, and the broken fuel storage 11 Sent to. On the other hand, those that are not damaged are sorted into a large particle size fuel sphere 3a and a small particle size fuel sphere 3b, and the small particle size fuel sphere 3b is sent to the small particle size burn-up detector 22 and the large particle size fuel sphere 3a. Is sent to the burnup detector 13 via the buffer tube 12.
[0120]
With respect to the large and small particle size fuel balls 3a and 3b in which the burnup detected by the burnup detector 13 and the burnup detector 22 for small particle size does not reach the predetermined burnup, the process computer 19 controls The switch 16 ″ is mixed so that the mixing ratio of the small particle fuel spheres 3a and the small particle fuel spheres 3b occupying the whole small particle fuel spheres 3b becomes a predetermined value, and is sent to the outer charger 15a. Further, only the large particle diameter fuel sphere 3a is sent to the inner charging device 15b, whereby the large particle size fuel sphere 3a and the small particle size fuel sphere 3b mixed at a predetermined mixing ratio are supplied from the outer charging device 15a. It is recharged into the outer region C in the core 2 through the outer charging tube 8a ', and only the large particle diameter fuel sphere 3a is re-introduced from the inner charging device 15b to the inner region D in the core 2 through the inner charging tube 8b'. It is thrown in.
[0121]
Thus, according to the present embodiment, as shown in FIG. 11, the mixture of the large particle size fuel spheres 3a and the small particle size fuel spheres 3b mixed at a predetermined mixing ratio is introduced into the outer region C, In the inner region D, it is possible to realize a core in which only the large particle diameter fuel balls 3a are charged. As a result, the fuel filling rate of the outer region C can be increased and the amount of fuel loaded can be relatively increased as compared with the inner region D, so that the output of the outer region C can be increased more than the inner region D. Therefore, the core radial output can be flattened in the same manner as in the first embodiment of the present invention described above.
[0122]
In addition, according to the present embodiment, it is possible to increase the number of years the fuel stays in the outer region C of the core 2 by increasing the amount of fuel loaded in the outer region C, thereby improving fuel economy. it can.
[0123]
In the fourth embodiment of the present invention described above, the mixing ratio of the small particle size fuel spheres 3b is divided into the outer region C and the inner region D that are divided so that the core 2 has the same area in the radial direction. The large group and the small group are distributed and supplied via the outer and inner charging pipes 8a ′ and 8b ′, but the present invention is not limited to this. That is, as described in the third embodiment, the group having a large mixing ratio of the small particle size fuel balls 3b and the group having a small mixing size are distributed and supplied to the regions divided so as to have different areas. May be. Even in this case, when the inside of the core 2 is divided into the outer region C and the inner region D so as to have the same area in the radial direction, the above relationship is satisfied between the outer region C and the inner region D. As long as this is done, the same effect as in the fourth embodiment of the present invention can be obtained.
[0124]
In the fourth embodiment of the present invention, only the large particle size fuel spheres are introduced into the inner region D. However, the present invention is not limited to this. That is, the small particle size fuel spheres 3b are mixed in both the outer and inner regions C and D, and the mixing ratio of the small particle size fuel spheres 3b in the entire large and small particle size fuel spheres 3a and 3b in the outer region C is set. It may be made relatively larger than the inner region D. Also by this, the same effect as that of the fourth embodiment of the present invention can be obtained.
[0125]
Next, a fifth embodiment of the reactor facility, the reactor core, and the operation method of the reactor according to the present invention will be described with reference to FIGS. This embodiment uses a uranium fuel sphere that uses uranium oxide as a nuclear fuel material and a mixed oxide fuel sphere that uses uranium / plutonium mixed oxide as a nuclear fuel material, so that the mixed oxide occupies the entire fuel sphere in the outer region A. The mixing ratio of the fuel balls is made relatively smaller than that of the inner region B.
[0126]
FIG. 12 is a conceptual diagram showing the overall configuration of the fifth embodiment of the nuclear reactor equipment of the present invention. In FIG. 12, the thick black arrow indicates the flow of the uranium fuel sphere 24, the open arrow indicates the flow of the mixed oxide fuel sphere 25, and the gray arrow indicates that the uranium fuel sphere 24 and the mixed oxide fuel sphere 25 are mixed. The broken arrows indicate the signal flow. In addition, the same code | symbol is attached | subjected to the part similar to FIG. 10 in the above-mentioned 4th Embodiment of this invention, and description is abbreviate | omitted.
[0127]
In FIG. 12, the nuclear reactor facility includes a core 2 loaded with a large number of uranium fuel balls 24 and mixed oxide fuel balls 25, and a relatively large number of reactors 2 in the core 2 as in the first embodiment of the present invention described above. A fuel ball injection tube 8 provided so as to be divided into a radially outer region and a relatively inner region, and a selector for detecting breakage of a mixture of the uranium fuel ball 24 and the mixed oxide fuel ball 25 10, a burnup detector 13 for detecting the burnup of a mixture of the uranium fuel sphere 24 and the mixed oxide fuel sphere 25, and the burnup detected by the burnup detector 13 does not reach a predetermined burnup A mixed oxide fuel sphere detector 26 for selecting the mixed oxide fuel sphere 25 from the mixture of the uranium fuel sphere 24 and the mixed oxide fuel sphere 25, and the mixed oxidation selected by the mixed oxide fuel sphere detector 26 The physical fuel ball 25 is A mixed oxide fuel sphere deriving device 27 derived from the catalyst and a switch 16 ′ having a function of mixing the mixed oxide fuel sphere 25 derived from the mixed oxide fuel sphere deriving device 27 with the uranium fuel sphere 24. '', A new fuel storage 17 ′ for storing a mixture of the uranium fuel sphere 24 and the mixed oxide fuel sphere 25 to be newly input, and a mixture of the uranium fuel sphere 24 and the mixed oxide fuel sphere 25 are burned. And a new fuel loading facility 18 ′ for the mixture to be fed to the degree detector 13.
[0128]
The uranium fuel sphere 24 uses, for example, uranium oxide as a nuclear fuel material, and the mixed oxide fuel sphere 25 uses, for example, uranium / plutonium using plutonium obtained by reprocessing spent fuel in a nuclear reactor such as a light water reactor. Mixed oxide is used as nuclear fuel material.
[0129]
The burnup detector 13 detects the burnup of the mixture of the uranium fuel spheres 24 and the mixed oxide fuel spheres 25 sorted by the sorter 10 and is output to the process computer 19, and the process computer 19 receives the input. The mixture of the uranium fuel spheres 24 and the mixed oxide fuel spheres 25 whose burnup has reached a predetermined burnup is controlled by the switch 16 '' 'and sent to the fuel storage 14. .
[0130]
On the other hand, the mixture of the uranium fuel sphere 24 and the mixed oxide fuel sphere 25 whose burnup does not reach the predetermined burnup is sent from the burnup detector 13 to the mixed oxide fuel sphere detector 26. The mixed oxide fuel sphere detector 26 selects the uranium fuel sphere 24 and the mixed oxide fuel sphere 25 by detecting the neutron beam intensity from the plutonium (particularly Pu 240) in the fuel sphere. Yes. The uranium fuel balls 24 selected by the mixed oxide fuel ball detector 26 are sent to the switch 16 '' 'at a constant pace, and the mixed oxide fuel balls 25 are sent to the mixed oxide fuel ball deriving device 27. It is done. That is, for the uranium fuel sphere 24 sent from the mixed oxide fuel sphere detector 26 to the switch 16 ′ ″ at a constant pace, the mixed oxide fuel sphere deriving device 27 performs a predetermined response according to an instruction from the process computer 19. The mixed oxide fuel spheres 25 are sent to the changer 16 ′ ″ at a pace, and the uranium fuel spheres 24 and the mixed oxide fuel spheres 25 are mixed by the changer 16 ′ ″ to be supplied to the outer input device 15a or the inner input device. The device 15b is selected and sent. Thus, when the mixing ratio of the mixed oxide fuel spheres 25 occupying the entire uranium fuel spheres 24 and the mixed oxide fuel spheres 25 is relatively small, the uranium fuel spheres 24 and the mixed oxide fuels are supplied to the outer charger 15a. When the mixing ratio of the mixed oxide fuel spheres 25 occupying the entire sphere 25 is relatively large, the mixture is led out to the inner charging device 15b.
[0131]
In the above, the mixed oxide fuel sphere deriving device 27 sets the mixed oxide fuel sphere so that the mixture ratio of the mixed oxide fuel sphere occupying the entire fuel sphere described in the claims is switched to a plurality of values. Derivable third derivation means is configured. Further, the fuel ball introduction pipe 8, the fuel introduction device 15, the switching device 16 ′ ″, and the process computer 19 constitute fourth distribution means that distributes for each set value of the mixture ratio of the mixed oxide fuel balls.
[0132]
Next, operation | movement and effect | action of 5th Embodiment of the nuclear reactor equipment of this invention of the said structure are demonstrated below.
The uranium fuel ball 24 and the mixed oxide fuel ball 25 loaded in the core 2 continuously move from the upper part to the lower part in the core 2 with the operation of the nuclear reactor, and a single unit provided in the lower part of the core 2. One ball is sent to the sorter 10 by the chemical tube 9. In this sorter 10, a broken one of the mixture of the uranium fuel sphere 24 and the mixed oxide fuel sphere 25 is sorted and sent to the broken fuel storage 11. On the other hand, those that are not damaged are sent to the burnup detector 13 via the buffer tube 12.
[0133]
The uranium fuel sphere 24 and the mixed oxide fuel sphere 25 whose burnup detected by the burnup detector 13 does not reach the predetermined burnup is sent to the mixed oxide fuel sphere detector 26, where uranium fuel is used. The uranium fuel sphere 24 is selected by the switch 16 '' 'at a constant pace, and the mixed oxide fuel sphere 25 is selected by the mixed oxide fuel sphere deriver 27 at a predetermined pace. It is sent to the switch 16 '' 'at a pace. At this time, when the mixing ratio of the mixed oxide fuel spheres 25 occupying the entire uranium fuel spheres 24 and the mixed oxide fuel spheres 25 is relatively small under the control of the process computer 19, the mixture is sent to the outer charger 15 a, When the mixing ratio of the mixed oxide fuel spheres 25 occupying the entire sphere 24 and the mixed oxide fuel spheres 25 is relatively large, the mixture is sent to the inner charging device 15b. As a result, the uranium fuel sphere 24 and the mixed oxide fuel sphere 25 having a relatively small mixing ratio of the mixed oxide fuel spheres 25 are relatively radial in the core 2 from the outer injector 15a through the outer injector tube 8a. The uranium fuel sphere 24 and the mixed oxide fuel sphere 25, which are re-introduced into the outer region and have a relatively large mixing ratio of the mixed oxide fuel spheres 25, enter the core 2 from the inner injector 15b through the inner injector 8b. Is re-introduced into the relatively radially inner region.
[0134]
In this way, according to the present embodiment, as shown in FIG. 13, the inside of the core 2 is divided and viewed so as to have, for example, an equal area in the radial direction as in the first embodiment described above. A core in which the mixing ratio of the mixed oxide fuel spheres 25 occupying the entire uranium fuel sphere 24 and the mixed oxide fuel sphere 25 in the outer region A is relatively smaller than that in the inner region B can be realized.
[0135]
Here, as described above, the reactivity of the mixed oxide fuel sphere 25 tends to be smaller than that of the uranium fuel sphere 24. That is, according to the present embodiment, by adopting the above-described configuration, the output of the outer region A is relatively increased as compared with the inner region B, as in the first embodiment of the present invention described above, and the core Flattening of radial output can be achieved.
[0136]
In addition, according to the present embodiment, as described above, plutonium obtained by reprocessing spent fuel in a nuclear reactor such as a light water reactor is reused by using the mixed oxide fuel sphere 25. It is possible to save the fuel balls 24, thereby improving fuel economy.
[0137]
In each of the embodiments of the nuclear reactor core of the present invention described above, the fuel ball injection tube 8 is provided so as to divide the inside of the core 2 into two regions, an outer region and an inner region. Not limited to this, it may be divided into three or more areas. Even in this case, when the inside of the core 2 is divided into the outer region A (or C) and the inner region B (or D) so as to have the same area in the radial direction, it is defined in each of the above embodiments. As long as such a relationship is satisfied, the same effect as that of each embodiment can be obtained.
[0138]
Further, in each of the embodiments of the nuclear reactor core of the present invention described above, the fuel ball (or deceleration ball) moves in the core 2 only downward in the axial direction of the core without moving in the horizontal direction from the input position. For this reason, the core 2 is not provided with a limit, but the present invention is not limited thereto, and a partition may be provided to divide the region in the core 2. Also by this, the same effect as each embodiment of the present invention can be obtained.
[0139]
In each of the embodiments of the nuclear reactor facility of the present invention described above, the switch 16 (or the switch 16 (or the burn-up detector 22 (or small particle size burn-up detector 22)) is detected according to the burn-up detected by the burn-up detector 13 (or the burn-up detector 22 for small particle size). The switch 16 ′ or the switch 16 ′ ″) is a fuel storage tank 14 or fuel for the fuel ball 3 (or the large / small particle size fuel balls 3a and 3b, or the uranium fuel ball 24 and the mixed oxide fuel ball 25). Although the derivation route to the input device 15 is switched, the present invention is not limited to this, and the fuel input device 15 may be provided with a function of switching the derivation route. Further, in each embodiment of the nuclear reactor facility of the present invention described above, new fuel balls 3 (or large / small particle size fuel balls 3a, 3b, or uranium fuel balls 24 and mixed oxide fuel balls 25) are replaced with new ones. The burnup detector 13 (or the burnup detector 22 for small particle size) is input from the fuel loading facility 18 (or the new fuel loading facility 18a, 18b for large / small particle size, or the new fuel loading facility 18 'for the mixture). However, the present invention is not limited to this, and the fuel may be directly fed into the fuel feeder 15. In these cases, the same effects as those of the embodiments of the present invention can be obtained.
[0140]
Further, in each of the embodiments of the reactor core of the present invention described above, helium is used as the coolant, but the present invention is not limited to this, and carbon dioxide gas (CO₂), Or an inert gas such as nitrogen or neon / argon. Further, instead of using a gas as a coolant, water or a liquid metal such as sodium or lead may be used.
[0141]
In each of the embodiments of the reactor core of the present invention described above, uranium or plutonium is used as the fuel. However, the present invention is not limited to this, and thorium may be used.
[0142]
【The invention's effect】
According to the first aspect of the present invention, the degree of burnup of the fuel balls discharged from the pebble bed nuclear reactor core is detected by the detection means, and the burnup degree on the radially outer side is detected by the first distribution means according to the detected value. Since the fuel ball radial injection position is distributed and re-entered so as to be relatively small with respect to the radial inner side, the core radial output can be flattened. Therefore, economic efficiency can be improved.
[0143]
According to the seventh aspect of the present invention, the mixing ratio of the reduction spheres occupied by the fuel balls and the reduction spheres discharged from the pebble bed type reactor core in the group of the fuel spheres and the reduction spheres on the radially outer side by the second distribution means. Since the injection positions of the fuel spheres and the deceleration spheres in the radial direction are distributed and re-entered so that becomes relatively larger with respect to the radially inner side, the core radial output can be flattened. Therefore, economic efficiency can be improved.
[0144]
According to the invention of claim 10, the fuel sphere and the deceleration sphere discharged from the pebble bed type reactor core have the burnup on the radially outer side by the first distribution means according to the detected value of the burnup of the fuel sphere. The fuel ball radial insertion position is distributed so as to be relatively small with respect to the radially inner side, and the mixing ratio of the fuel sphere and the deceleration sphere occupying the group of the fuel spheres on the radially outer side by the second distributing means is radially inner. The radial injection positions of the groups of fuel balls and deceleration balls are distributed and re-entered so as to be relatively small. Thereby, the core radial direction output can be flattened and the fuel economy can be improved. Therefore, economic efficiency can be further improved.
[0145]
According to the eleventh aspect of the present invention, the large particle size fuel spheres and small particle size fuel spheres discharged from the pebble bed reactor core are separated from the large particle size fuel spheres and small particles on the radially outer side by the third distribution means. Reposition and re-enter the radial injection positions of the large and small particle size fuel balls so that the mixing ratio of the small particle size fuel spheres in the group of diameter fuel balls is relatively larger than the inside in the radial direction. To do. As a result, the core radial direction output can be flattened, and thus the economy can be improved.
[0146]
According to the invention of claim 13, the mixed oxidation fuel spheres and mixed oxide fuel spheres discharged from the core are mixed and oxidized in the group of mixed oxide fuel spheres and uranium fuel spheres on the radially outer side by the fourth distribution means. The radial injection positions of the mixed oxide fuel sphere and uranium fuel sphere groups are sorted and re-entered so that the mixing ratio of the physical fuel spheres becomes relatively small with respect to the radially inner side. As a result, the core radial direction output can be flattened, and thus the economy can be improved.
[Brief description of the drawings]
FIG. 1 is a side cross-sectional view schematically showing the overall structure of a nuclear reactor provided with a first embodiment of a nuclear reactor core according to the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is a conceptual diagram showing the overall configuration of the first embodiment of the nuclear reactor facility of the present invention.
4 is a cross-sectional view taken along the line IV-IV in FIG.
FIG. 5 is a conceptual diagram showing the overall configuration of a second embodiment of the nuclear reactor equipment of the present invention.
FIG. 6 is a cross-sectional view showing a core configuration of a second embodiment of a nuclear reactor core according to the present invention.
FIG. 7 is a cross-sectional view showing a core configuration of a modification of the second embodiment of the reactor core of the present invention.
FIG. 8 is a cross-sectional view showing a core configuration of a third embodiment of a nuclear reactor core according to the present invention.
FIG. 9 is a cross-sectional view showing a core configuration of a modification of the third embodiment of the reactor core of the present invention.
FIG. 10 is a conceptual diagram showing an overall configuration of a fourth embodiment of a nuclear reactor facility of the present invention.
FIG. 11 is a cross-sectional view showing a core configuration of a fourth embodiment of a nuclear reactor core according to the present invention.
FIG. 12 is a conceptual diagram showing the overall configuration of a fifth embodiment of a nuclear reactor facility of the present invention.
FIG. 13 is a transverse sectional view showing a core configuration of a fifth embodiment of a reactor core of the present invention.
[Explanation of symbols]
2 core
3 Fuel ball
3a Large particle size fuel ball
3b Small particle size fuel ball
8 Fuel sphere injection pipe (fuel sphere supply pipe; first distribution means; fourth distribution means)
8 'Fuel ball injection pipe (second distribution means; third distribution means)
13 Burnup detector (detection means)
15 Fuel input device (first selection introduction means; first distribution means; second selection introduction means; second distribution means; third distribution means; fourth distribution means)
16 switching device (switching means; first selection introducing means; first sorting means)
16 'switch (2nd selection introduction means; 2nd distribution means)
16 ″ switch (third sorting means)
16 '' 'switcher (fourth sorting means)
19 process computer (first selection introduction means; first distribution means; second selection introduction means; second distribution means; third distribution means; fourth distribution means)
20 Deceleration sphere
21 Deceleration sphere deriving device (first deriving means)
23 Small particle size fuel sphere deriving device (second deriving means)
24 Uranium fuel ball
25 Mixed oxide fuel ball
27 Mixed oxide fuel ball deriving device (third deriving means)

Claims (29)

Detecting means for introducing a large number of fuel balls discharged from a pebble bed type reactor core and detecting the degree of combustion of the fuel balls;
Reactor equipment, comprising: a first distribution unit that distributes a radial injection position when re-injecting the fuel ball into the reactor core according to a detection result of the detection unit.   2. The nuclear reactor equipment according to claim 1, wherein the first distribution means distributes the radially inserted position of the fuel sphere having a relatively small burnup to the outside in the radial direction and the fuel sphere having a relatively large burnup. Reactor equipment characterized by allocating the radial injection position to the inside in the radial direction.   3. The nuclear reactor facility according to claim 1, wherein the first distribution unit includes a plurality of fuel ball supply pipes provided so that one end portions thereof are located at different radial positions in the upper part of the reactor core, and Reactor equipment, comprising: first selective introduction means for selectively introducing the fuel spheres into the plurality of fuel sphere supply pipes according to a detection result of the detection means.   4. The nuclear reactor equipment according to claim 3, wherein the first selective introduction means includes a switching means that is provided on the downstream side of the detection means and switches a fuel ball derivation path for which burnup has been detected by the detection means. Reactor equipment characterized by   5. The nuclear reactor equipment according to claim 4, wherein the switching means guides the fuel ball having a predetermined burnup to a take-out side passage.   The nuclear reactor equipment according to any one of claims 1 to 5, wherein the detection means is means for detecting radiation relating to a predetermined nuclide contained in the fuel ball. Introduces a large number of decelerating spheres discharged from a pebble bed reactor core, and the decelerating sphere can be derived so that the mixing ratio of the decelerating spheres in the fuel sphere and the entire decelerating sphere is switched to multiple values. First derivation means,
A second sorting unit that sorts the throwing position in the radial direction when the speed reducing sphere derived from the first deriving unit is recharged into the reactor core for each set value of the mixing ratio of the speed reducing spheres; Characteristic reactor equipment.   8. The nuclear reactor equipment according to claim 7, wherein the second distribution means distributes a radially inserted position of a group of fuel balls and deceleration balls having a relatively large mixing ratio of the reduction balls to the outside in the radial direction. Reactor equipment characterized in that a radial injection position of a group of fuel spheres and deceleration spheres having a relatively small mixing ratio is distributed radially inward.   9. The nuclear reactor equipment according to claim 7, wherein the second distribution means includes a plurality of fuel ball supply pipes provided so that one end portions thereof are at different radial positions in the upper part of the reactor core, and Reactor equipment, comprising: a second selective introduction means for selectively introducing the fuel sphere and the deceleration sphere into the plurality of fuel sphere supply pipes in accordance with a set value of a reduction sphere mixing ratio.   The nuclear reactor facility according to claim 7, wherein a plurality of fuel balls discharged from the nuclear reactor core are introduced, a detection means for detecting a burnup of the fuel balls, and according to a detection result of the detection means, First distribution means for assigning a radial injection position when the fuel ball is re-introduced into the reactor core, and the first distribution means has a fuel ball injection position with a relatively high burnup. The fuel ball is distributed to one of the radially inner side and the outer side, and the injection position of the fuel ball having a relatively low burnup is distributed to the other side of the radially inner side and the outer side. The throwing position of the decelerating sphere when the set value is relatively large is distributed to one side in the radial direction, and the throwing position of the decelerating sphere is set to the other side in the radial direction when the set value of the mixing ratio is relatively small Nuclear reactor equipment, characterized in that it distributes. Introduce a large number of large-sized fuel spheres with a relatively large particle diameter and a large number of small-sized fuel spheres with a relatively small particle diameter discharged from the pebble bed type reactor core and occupy the whole fuel sphere Second derivation means capable of deriving the small particle size fuel sphere so as to switch and set the mixing ratio of the small particle size fuel sphere to a plurality of values;
A third allocation that allocates the radial injection position when the small particle size fuel sphere derived from the second deriving means is reintroduced into the reactor core for each set value of the mixture ratio of the small particle size fuel spheres. And a reactor facility.   12. The nuclear reactor facility according to claim 11, wherein the third distribution means is a radial insertion position of the group of the large particle size fuel sphere and the small particle size fuel sphere in which the mixing ratio of the small particle size fuel sphere is relatively large. And the charging position of the group of the large particle size fuel sphere and the small particle size fuel sphere in the radial direction is allocated to the inside in the radial direction. Reactor equipment to do. Introduced many mixed oxide fuel spheres with uranium / plutonium mixed oxide discharged from pebble bed reactor core as nuclear fuel material and many uranium fuel spheres with uranium oxide as nuclear fuel material, Third derivation means capable of deriving the mixed oxide fuel sphere so as to switch and set the mixing ratio of the mixed oxide fuel sphere in the whole to a plurality of values;
A fourth allocation in which the radial injection position when the mixed oxide fuel sphere derived from the third deriving means is reintroduced into the reactor core is allocated for each set value of the mixing ratio of the mixed oxide fuel sphere. And a reactor facility.   14. The nuclear reactor facility according to claim 13, wherein the fourth distribution means is configured to set a radial insertion position of the group of the mixed oxide fuel sphere and the uranium fuel sphere having a relatively large mixing ratio of the mixed oxide fuel sphere. A nuclear reactor characterized by allocating radially inwardly and allocating radially input positions of the group of mixed oxide fuel spheres and uranium fuel spheres having a relatively small mixing ratio of the mixed oxide fuel spheres to the radially outer side Facility. In a pebble bed type reactor core constructed by putting many fuel balls into the inside from the top of the vessel,
When the inside of the container is divided into an inner region and an outer region so as to have the same area in the radial direction, the average burnup of all fuel balls in the inner region is the average combustion of all fuel balls in the outer region. A nuclear reactor core in which the fuel balls are introduced so as to be larger than a predetermined degree. In a pebble bed type reactor core configured by inserting a number of fuel balls and deceleration balls into the inside from the top of the vessel,
When the inside of the container is divided into an inner region and an outer region so as to have the same area in the radial direction, the number density of the deceleration spheres in the inner region is smaller than the number density of the deceleration spheres in the outer region. The reactor core, wherein the fuel ball and the deceleration ball are inserted into the reactor core.   17. The nuclear reactor core according to claim 16, wherein a plurality of mixed layers in which the fuel spheres and the deceleration spheres are substantially uniformly mixed are formed in the vessel in a radial direction at different mixing ratios. A nuclear reactor core in which a sphere and the deceleration sphere are introduced. In a pebble bed type reactor core configured by inserting a number of fuel balls and deceleration balls into the inside from the top of the vessel,
When the inside of the container is divided into two regions of an inner region and an outer region so as to have the same area in the radial direction, the average burnup of all the fuel balls in one region is all the fuel balls in the other region. The fuel spheres and the deceleration spheres are introduced so that the number burnup spheres in the one region are larger than the number density of the deceleration spheres in the other region. Reactor core. 19. The nuclear reactor core according to claim 18, wherein the average burnup distribution is controlled according to which of the average burnup distribution of the fuel balls and the number density of the speed reduction balls has a dominant influence on the core power. The one region as the inner region and the other region as the outer region, and when the number density of the speed reduction spheres is dominant, the one region is the outer region. reactor core of the region, characterized in that the region of the other side was the inner region. In claims 1-8 Symbol mounting reactor core, said the one of the regions said inner region, a nuclear reactor core, characterized in that the other area was the outer region. In claims 1-8 Symbol mounting reactor core, said the one region of the outer region, a nuclear reactor core, characterized in that the region of the other side was the inner region. In a pebble bed type reactor core constructed by introducing a large number of large particle size fuel spheres with a relatively large particle size and a large number of small particle size fuel spheres with a relatively small particle size from the top to the inside of the vessel ,
When the inside of the container is divided into an inner region and an outer region so as to have an equal area in the radial direction, the large particle size fuel and the small particle size fuel sphere are put into both the outer region and the inner region. together, to increase the fuel filling rate of the outer region than the inner region, the number density of the small径燃fee spheres in the inner region is smaller than the number density of the small径燃fee spheres in the outer region Reactor core characterized by A pebble bed type atom which is composed of a large number of mixed oxide fuel spheres with uranium / plutonium mixed oxide as nuclear fuel material and a large number of uranium fuel balls with uranium oxide as nuclear fuel material. In the reactor core,
When the inside of the container is divided into an inner region and an outer region so as to have an equal area in the radial direction, the number density of the mixed oxide fuel spheres in the inner region is the mixed oxide fuel sphere in the outer region. The nuclear reactor core, wherein the mixed oxide fuel sphere and the uranium fuel sphere are introduced so as to be smaller than the number density of the reactor.   24. The nuclear reactor core according to claim 23, wherein the plutonium contained in the uranium / plutonium mixed oxide is obtained by reprocessing spent fuel of the nuclear reactor.   The degree of burnup of the fuel balls discharged from the pebble bed type reactor core is detected, and according to the detection result, the radial injection position when the fuel balls are reintroduced into the reactor core is distributed. Reactor operation method. And switching setting the mixing ratio of the reduction sphere to the total of the fuel spheres are charged into the reactor core of the pebble bed and the deceleration sphere to multiple values,
A method of operating a nuclear reactor, comprising: allocating positions in a radial direction of the reactor core when the deceleration sphere is reintroduced into the reactor core for each set value of the mixing ratio of the deceleration spheres.   27. The method of operating a nuclear reactor according to claim 26, wherein the charging position of the fuel sphere having a relatively high burnup is distributed to one of the radially inner side and the outer side and the fuel sphere having a relatively low burnup degree. The charging position is assigned to the other of the radially inner side and the outer side, and the setting position of the deceleration sphere when the setting value of the mixing ratio is relatively large is assigned to the one radial side, and the setting value of the mixing ratio A method of operating a nuclear reactor according to claim 1, wherein the charging position of the decelerating sphere is distributed to the other side in the radial direction when is relatively small. The mixing ratio in the entire fuel sphere composed of a large particle size fuel sphere and a relatively small particle size fuel sphere charged into the pebble bed reactor core is set to a plurality of values. Switch settings,
A setting value of a mixing ratio of the small particle size fuel spheres is a radial injection position when at least the large particle size fuel spheres are reintroduced into the reactor core among the large particle size fuel spheres and the small particle size fuel spheres. A method of operating a nuclear reactor core, characterized in that the fuel filling rate in the outer region is higher than that in the inner region .   The mixed oxide occupies the entire fuel sphere composed of a uranium fuel ball having a uranium / plutonium mixed oxide as a nuclear fuel material and a uranium fuel ball having a uranium oxide as a nuclear fuel material. The mixture ratio of the fuel spheres is switched to a plurality of values, and the radial injection position when the mixed oxide fuel spheres are reintroduced into the reactor core is set for each set value of the mixture ratio of the mixed oxide fuel spheres. Reactor operating method characterized by sorting.

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