JPH0797154B2 - Direct cycle nuclear power plant and its operating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a direct cycle nuclear plant that contributes to a reduction in the dose rate in the main steam system and turbine system due to carryover of radioactive nitrogen atoms ¹⁶ N, and its Regarding driving method.

[Conventional technology]

In a direct cycle nuclear power plant such as a boiling water nuclear power plant (BWR) and a nuclear power plant (ATR) having a new converter, the turbine is driven directly by the steam generated in the nuclear reactor due to the nuclear fission reaction heat. The carryover of radioactive nitrogen atoms ¹⁶ N generated as a result of activation of oxygen atoms in water molecules of reactor water (hereinafter referred to as reactor water) by neutron irradiation causes turbine system dose rate. . The dose rate of the turbine system with ¹⁶ N is several R / h in terms of the surface dose rate of the main steam pipe, but further reduction is necessary in the following two points.

(1) Reduction of radiation exposure during inspection work during reactor operation.

(2) Dose rate regulation at the boundary of the nuclear power plant site. (Skyshine regulation) For the above purpose, both sides and the upper part of the main steam pipe have been conventionally shielded with iron plates, but the measures themselves from the viewpoint of suppressing the generation and release of ¹⁶ N in the nuclear reactor are becoming more understood. It wasn't done for a long time.

At plants where stress and material stress-sensitive stainless steel stress corrosion cracking suppression measures, such as those used in Japan's nuclear reactors, are not implemented, hydrogen injection is widely used to reduce the oxygen concentration in the reactor water. Is being applied, in which case
It has been confirmed in the plants that have undergone the injection test that the concentration of ¹⁶ N in the main steam increases as the hydrogen injection amount increases, and in some plants hydrogen injection cannot be carried out in connection with the above-mentioned Skyshine. For this purpose, for example, JP-A-57-19
A nuclear power plant described in Japanese Patent No. 4399 or Japanese Patent Laid-Open No. 62-151797 has been proposed.

[Problems to be Solved by the Invention]

Among the above-mentioned conventional techniques, the one disclosed in JP-A-57-194399 is provided with a device for removing N ₂ . But,
Virtually ¹⁶ N does not exist in the chemical form of N ₂ , but is entrained in water vapor in the form of NO _X. Accordance connexion, said in N ₂ removal unit ¹⁶
Effective removal of N is impossible. Further, in the case of the N ₂ gas injection device described in JP-A-62-151797,
There is a drawback that the isotope exchange reaction efficiency between ¹⁴ NH ₃ and ¹⁶ NH ₃ is low.

An object of the present invention is to provide a direct cycle nuclear power plant and its operating method which are characterized by suppressing an increase in dose due to N-16 of a turbine system without adversely affecting the dose rate of the plant and the corrosive environment in the furnace. To provide.

[Means for Solving the Problems]

The above object can be achieved by injecting nitrogen oxides into the furnace and injecting an alkaline substance such as sodium ions.

[Action]

The present invention firstly uses the property that ¹⁶ N converts to a non-radioactive oxygen atom with a half-life of 7.2 seconds. That is, if ¹⁶ N can be retained in the liquid phase in the pressure vessel for a time corresponding to the half-life or longer, the concentration of ¹⁶ N in the main steam can be reduced to half or less. The liquid phase retention means is based on the following findings. That is, (i) ¹⁶ N is released into the main steam in the chemical form of ¹⁶ NO.

(Ii) ¹⁶ NO emission increases with increasing hydrogen atom concentration.

Therefore, reduction of ¹⁶ N is achieved by means of reducing the hydrogen atom concentration or increasing the OH radical concentration to reduce the equilibrium concentration of ¹⁶ NO in water.

To this end, in order to convert radioactive nitrogen oxides into anions in the reactor water, it is necessary to inject into the reactor water a hydrogen radical scavenger that has the action of reacting with hydrogen atoms and reducing the concentration of hydrogen atoms. Good. The injection into the reactor water does not necessarily have to be directly inserted into the water inside the reactor, and the water supply area may be injected from the condensate system. In addition, the effectiveness of the measures considered in terms of the reduction of hydrogen atom concentration or the increase of OH concentration is evaluated by the analysis of ¹⁶ NO by taking NO as an example. Figure 3 shows the ¹⁶ NO concentration in water vapor when the injection amount was changed,
It shows the calculated values of oxygen, hydrogen peroxide, nitric acid, and nitrite concentration in the reactor water. To the core inlet concentration It can be seen that the concentration of ¹⁶ NO can be reduced by about one digit by maintaining the concentration of ¹⁶ NO. Furthermore, it can be seen that an effect of reducing oxidation and hydrogen peroxide can be expected.

The above results can be interpreted as follows. That is, as a result of the injected components reacting with the radiation products of water, in the process of increasing the concentration of NO, for example, Due to such reactions, the equilibrium concentration of hydrogen atoms decreases, and the reactions such as H + OH → H ₂ O (3) become difficult to proceed, and the concentration of OH radicals increases relatively. Therefore, even if ¹⁶ N generated in the core becomes ¹⁶ NO, Therefore, it easily takes the form of nitrite, and once it becomes nitrite, The reaction of is difficult to proceed because the hydrogen atom concentration is low. As described above, the equilibrium concentration of ¹⁶ NO is lowered, so the ¹⁶ NO concentration in the main steam is also reduced. On the other hand, the concentration of hydrogen peroxide and oxygen decreases It is thought to be due to the reaction of

on the other hand, Nitrogen and sulfite become high in concentration and oxygen concentration increases when injected to a certain degree, so it can be seen that there is a problem in injecting too much. NO in reactor water and Increasing ion concentration affects reactor water pH and conductivity. It is generally thought that the decrease in pH of reactor water and the increase in conductivity affect material corrosion and radioactivity. For this reason, it is expected to cause adverse effects such as increasing the dose level of the plant, so it is necessary to control water quality with these points in mind.

In the present invention, when nitrogen oxide is further injected, the alkaline substance such as sodium ion is added to control the water quality so that the reactor water pH is always in the neutral to alkaline side.

Further, in a system in which nitrate ions and nitrite ions are present as impurities, the electrical conductivity of the reactor water increases due to the high hydrogen ion concentration, which has a high equivalent conductivity. However, when the sodium ion is added to control the water quality on the weakly alkaline side, the hydrogen ion concentration decreases due to the relation of the dissociation constant, so that the fluctuation of the conductivity becomes relatively small.

From the above, the pH and conductivity of the reactor water are controlled so as not to change as much as possible even when nitrogen oxide is injected. This allows
In addition to controlling the corrosion of materials, we will also control the increase in the radioactivity concentration of reactor water.

Since the injection amount of the alkaline substance is controlled so as to keep the reactor water pH and the conductivity as constant as possible, the pH and the conductivity of the reactor water hardly change even when the nitrogen oxide injection is interrupted.

The above points will be described with reference to the following drawings and data.

Figure 2 shows the concept of the generation mechanism of ¹⁶ N in the turbine system. During normal operation, ¹⁶ N in the turbine system is considered to be transferred from reactor water to main steam as nitric oxide (NO). Further, it is considered that the nitrogen compounds exist as nitrite ions and nitrate ions in the furnace and are balanced as shown in FIG. It is considered that when the reactor water is reduced by hydrogen injection, etc., the volatile NO is relatively increased and the NO concentration in the main steam is increased. Since ¹⁶ NO also accompanies ¹⁶ NO, it is thought that the dose rate of the turbine system will also increase. NO ₂ , NO, N ₂ O in reactor water, It is considered to suppress the transfer amount of NO into the main steam by injecting nitrogen oxides such as. As shown in FIG. 3, the injection of NO reduces the ¹⁶ NO concentration in the main steam.
On the other hand, due to the injection of NO, Have been shown to increase in concentration. The injection amount is the NO concentration at the core inlet. , The generated NO ₂ − is about 90 ppb, Has been shown to be about 30 ppb. As a result, the injection amount of alkaline substance is The concentration should be at least stoichiometrically neutralizable. For example, in the case of NaNO ₃ (molecular weight 85), Na: NO ₃ = 23: 62
Can be used as a guide for the injection amount.

Next, the effect of injecting an alkaline substance will be shown from the viewpoint of suppressing the radioactive concentration in reactor water. Figure 4 shows the experimental results on the cobalt elution rate from the fuel rod surface cladding when the reactor water pH was changed. As shown in this figure, by controlling the pH of the reactor water to the alkaline side, the elution rate of cobalt from cobalt ferrite decreases. In other words, when the pH of the reactor water is on the acidic side such as 6, the elution rate of cobalt increases, and the radioactivity concentration of the reactor water increases, but by making it alkaline, it becomes possible to prevent it.

Furthermore, an example of evaluating the influence of nitrate ions in terms of the corrosive environment of the material will be described.

Figure 5 shows CORROSION Vol44, No. 11, 1988, p791-799, WE
From the results of the impurity concentration in water and the material test reported by Ruther et al., Only the results related to nitrate ion are extracted. As shown in this figure, in the reactor water, The presence of HNO _{3 in} the form of HNO ₃ increases the susceptibility of the material to stress corrosion cracking for pure water. However It can be seen that when is present in the form of a salt with sodium ion such as NaNO ₃ , the susceptibility to stress corrosion cracking is rather lowered, and the effect as an impurity is negligible at the same level as pure water. In this experiment I am evaluating the impact of Is considered to have the same effect.

From the above, nitrogen oxides are generated by injection and in combination. By injecting an alkaline substance that only neutralizes with, for example, NaOH, the concentration increase of reactor water radioactivity due to the elution of radionuclides from the clad adhering to the fuel rod surface and the increase in the dose of the plant are suppressed. In addition, the susceptibility to stress corrosion cracking can be suppressed. Also, regarding the general corrosion of the material, if the water quality is alkaline rather than neutral, a passive film is formed on the material surface, and corrosion is suppressed,
It can be said that this is also desirable. In addition, this can be expected to have the effect of suppressing the accumulation of radionuclides in the carbon steel piping of the primary reactor system.

Next, as a method of reducing the dissolved oxygen concentration in the reactor water by binding it with hydrogen atoms, a method of injecting hydrogen into the primary cooling water has been considered. It is known that as the amount of hydrogen injection increases, the concentration of radioactive nitrogen ¹⁶ N in the main steam increases and the turbine system dose rate increases. In order to avoid this problem, it is necessary to keep ¹⁶ N in the reactor water and reduce the amount transferred to the gas phase. ¹⁶ N is considered to move into the gas phase in the form of ¹⁶ NO and increase the turbine dose rate. Therefore, ¹⁶ NO is changed to an anion component, and ¹⁶ N
Is an effective means to reduce the amount of gas phase transfer by keeping it in the reactor water. Concentration of each component at the core outlet and ¹⁶ NO in steam when hydrogen and nitrogen compounds are simultaneously injected into reactor water
The concentration was simulated. As an example, 100 ppb of hydrogen was injected into the reactor water, and NO, NO ₂ , Table 1 shows the results of the simulation for the injection.

From this, it is understood that the concentration of ¹⁶ NO in the vapor can be reduced when any of the nitrogen compounds is injected, compared with the case where no nitrogen compound is injected. Further, in this case, it is understood that the dissolved oxygen concentration can be reduced by one digit or more as compared with the case where only hydrogen is injected. The above results can be interpreted as follows. That is, the injected nitrogen compound is, for example, As a result, the concentration of hydrogen atoms decreases, and the reaction of H + OH → H ₂ O becomes difficult to proceed, and the concentration of OH radicals increases relatively. Since hydrogen and oxygen become water through the OH radical, it is considered that the binding reaction between dissolved oxygen in the reactor water and injected hydrogen is accelerated, and the dissolved oxygen concentration decreases. Also in this case, it is generated when a nitrogen compound is injected. The pH change of the reactor water due to can be adjusted by adding alkaline ions to the feed water for neutralization.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of BWR. FIG. 1 shows a schematic configuration of a boiling water nuclear power plant, in which the nitrogen oxide injection device 2 is connected to a water supply system and the alkaline substance injection device is connected to a reactor cleaning system 7. In addition to the water supply system, the injection point of the nitrogen oxide injection device may be the reactor cleaning system 7, control rod drive device, in-reactor instrumentation pipe, etc. On the other hand, the alkaline substance injection device 1 controls the injection amount according to the water quality of the reactor water, that is, the system in which the reactor water exists, that is, the reactor recirculation system 6
And the reactor coolant purification system 7. In the present embodiment, the injection amount of the alkaline substance is controlled so that the pH of the reactor water falls within the range of 7.0 to 8.5 while measuring the water quality with the water quality monitor 3 such as the pH monitor of the reactor water. In this embodiment, the water quality of the reactor water is monitored by pH, but it is also possible to control the injection amount while measuring the conductivity. In addition, it is possible to control the injection amount while monitoring the material corrosion potential and the crack growth rate. Furthermore, a method of controlling the injection amount based on the measured value of nitrate ion concentration by online ion chromatography in the reactor water sampling system is also conceivable. Further, if the injection point of the alkaline substance is changed to the water supply system, there is a concern that the quality of the water supply may be changed.

Next, the effect of the present invention on the pH of the reactor water and the conductivity will be described with reference to FIG. As shown in this figure, examples of evaluation of pH and conductivity are shown for three cases: water quality without injection, injection of nitrogen oxides only, and injection of nitrogen oxides and alkaline substances simultaneously. As shown in this figure, injection of nitrogen oxides alone as in Case 2 results in a shift of pH to the acid side and an increase in conductivity, but by adding an alkaline substance such as sodium ion Can be suppressed. However, although Fig. 6 is based on the case where impurities are not included, generally in reactor water
Since it is common for impurity ions such as SO ₄ ²⁻ ions to coexist, it is considered that the amount of change in water quality with respect to the injection amount will vary somewhat depending on the plant due to their influence.

Therefore, controlling the injection amount while directly monitoring the reactor water quality is effective for proper control.

FIG. 7 shows an evaluation example for explaining the effects of pH and conductivity on the injection amount of nitrogen oxide. The upper figure shows the case where the alkaline substance is not added, and the lower figure shows the case where the alkaline substance is added in advance and the injection amount of nitrogen oxide is changed. As can be seen from this figure, in the case where no alkaline substance is added, the water quality changes due to nitrogen oxide injection, but in the case where nitrogen oxide is injected in the presence of alkali ions, the conductivity and pH are lower. It is shown that the impacts on the According to water quality standards, BWR reactor water has pH and conductivity standard values of 5.6 to 8.6 and <1μ, respectively.
S / cm is decided, and basically, it is a characteristic that the direction is sufficiently satisfied without deviating from this standard.

Figure 8 shows the intergranular stress corrosion cracking (IG
The relationship between conductivity and corrosion potential with or without SCC is shown. As shown in this figure, it is generally understood that the number of cases where stress corrosion cracking occurs increases as the conductivity increases. From this, it is considered that the reduction of conductivity by addition of alkali ions is an effective measure from the viewpoint of measures against stress corrosion cracking.

As the alkaline substance to be injected, alkali metal hydroxides such as NaOH, KOH and LiOH, alkaline earth metal oxides such as Ca (OH) _{2 and} the like can be considered. Among these, alkali metal hydroxides are more common, and among them, normal BW
A trace amount has been confirmed in R reactor water Ions are considered promising.

Ions are activated by irradiation to produce ²³ Na (half-life of 15
As the concentration in the reactor water increases, the carryover of ²³ Na into the main steam also increases. However, according to the present invention, the reactor water Na concentration is Since it is on the order of several tens of ppb to neutralize, the increase in turbine system dose rate due to carryover of ²³ Na can be ignored. Therefore, the nitrogen oxide injection itself does not adversely affect the expected reduction effect of the turbine system dose rate. According to the above-mentioned embodiment, during the operation of the direct cycle nuclear power plant by injecting nitrogen oxides into the reactor water, the oxygen atoms in the water molecules of the reactor water are activated by neutron irradiation to generate radioactivity. Carryover from the reactor containing ¹⁶ N nitrogen atoms to the main steam system and further to the turbine system can be significantly suppressed, and the dose rate can be significantly reduced. Further, by simultaneously injecting the alkaline substance into the reactor water, the pH of the reactor water is controlled on the neutral to weakly alkaline side, and it is possible to suppress the nuclide elution from the radioactive cladding from the surface of the fuel rod. Further, since the air dose rate inside the turbine building can be reduced, the entire turbine building can be downsized.

In the present invention, the injection of nitrogen oxides is considered to be performed temporarily for the purpose of temporarily reducing the turbine system dose rate, but at this time, the water quality of the reactor water changes or the injection amount. Since the injection amount of the alkaline substance is controlled according to the increase and decrease of, the pH of the reactor water and the conductivity do not change greatly. As a result, transient fluctuations in reactor water quality, such as an increase in Cr ions, can be suppressed. In addition to this, in controlling the injection quality of alkaline substances, it is considered that the pH of the reactor water is controlled to a weak alkaline side pH of 7.0 to 8.5. Precision is not required. Therefore, as a water quality control method for weakening the alkaline water quality of the reactor water, alkali ion is loaded in advance on the ion exchange resin in the condensate demineralizer 14 or the reactor coolant purification system filter desalinator 11. Therefore, a method of controlling the water quality of the reactor water while leaking alkali ions from the resin in a water-flowing state during plant operation can be considered. According to this method, the facility can be simplified. Further, by further providing an injection device on the inlet side of the reactor coolant purification system filtration desalination device and providing an injection device capable of supplying alkali ions to the resin, it is possible to easily carry out the operation of loading the resin alkali ions. .

FIG. 9 illustrates changes in the water quality when the water quality of the reactor water is controlled by such a method. As shown in this figure, it becomes possible to control the water quality while changing the injection amount of nitrogen oxide in a stepwise manner.

Next, another embodiment of the present invention is shown in FIG. 10, FIG. 11 and FIG.

Fig. 10 shows that the injection amount of nitrogen oxide and the change in reactor water quality are evaluated in advance and the correlation is controlled, and the injection amount of alkaline substance is controlled accordingly according to the injection amount of nitrogen oxide. Is. As a result, other factors that fluctuate the reactor water pH and conductivity, such as the inflow of impurities into the reactor due to resin leaks and the pH and conductivity due to the inflow of chlorine ions in seawater into the reactor due to condenser tube leaks. Even if the fluctuation occurs, on the other hand, a malfunction such that the injection amount of the alkaline substance increases more than necessary does not occur.

FIG. 11 shows the system configuration when the injection point of nitrogen oxides is the reactor cooling purification system. As a result, the injection points of the nitrogen oxide and the alkaline substance can be made at one place, and the system can be simplified. Also, there is no possibility that nitrogen oxides will affect the materials and water quality in the water supply system. Other similar injection points include control rod drive (CR
D) Cooling water system and reactor instrumentation pipes are possible.

Fig. 12 shows an example of application in a plant where hydrogen is injected to reduce dissolved oxygen in reactor water. As a result, the concentration of dissolved oxygen in the furnace was lowered by hydrogen injection and nitrogen oxides, the corrosive environment in the furnace was maintained more relaxed, and the dose rate of the turbine system was further improved without being affected by the generated nitric acid and nitrite ions. Can be reduced.

Next, a case where hydrogen and nitrogen oxide are simultaneously injected will be described.
In this case, it is necessary to deal with the following technical issues.

Since nitrogen oxides react with hydrogen and water decomposition products, for example, when both are injected from a water supply system, the radiation chemical reaction proceeds in a downcomer with a relatively high dose rate and the injected nitrite is separated. It changes into the chemical form of.

The injected nitrogen oxides are partially volatile NOx gas, and the rest are nonvolatile nitrous acid, nitric acid, and other N / H-based radicals. Non-volatile components accumulate in the reactor water during circulation in the recirculation system. Almost all of the volatile components are transferred to the vapor phase in the boiling channel, upper plenum, and riser of the core, so the steady concentration is determined by the balance between the emission amount and the injection amount.

A volatile component such as NO is formed by reducing nitrogen oxides with hydrogen, and thus the amount of release thereof is determined by the amount of hydrogen injection.

FIG. 13 is a calculation example showing this. The calculation is a numerical analysis of the chemical reaction that progresses during the process of circulating the BWR primary cooling system using nitrous oxide as the injected nitrogen oxide.
The horizontal axis is the number of circulations around the primary cooling system, and the vertical axis is the core outlet nitrite concentration. According to the calculation results shown in Table 1, the concentration at the core inlet or core outlet Must be secured. Calculation result is nitric acid concentration in feed water When the hydrogen injection rate is high Most of the nitrite injected by the reducing action of hydrogen is NO.
It is replaced with gas and released into the main steam system. That is, in this case, the total amount of hydrogen and nitrous acid injected from the feed water is discharged into the gas phase in the core and its vicinity, and the entire system becomes equal to the one-through system, so the steady concentration is reached with a relatively small number of circulations. However, when the hydrogen injection amount is small,
(In Fig. 13, no hydrogen injection, and hydrogen concentration in feed water Since the concentration of non-volatile components is relatively high, it accumulates in the reactor water with each circulation. As described above, even if hydrogen and ¹⁶ NO reducing agent are injected at the same time, the most technically difficult problems are the control of dissolved oxygen concentration by hydrogen injection and the concentration control and monitoring method of the component generated from the additive. The additive component only needs to be present in the vicinity of the core, but hydrogen is ideal for injection from the vicinity of the water supply nozzle because hydrogen is intended to reduce dissolved oxygen in the downcomer, recirculation piping, and lower plenum of the pressure vessel.
Therefore, it is desirable to inject hydrogen from the feed water pipe, and the additive for reducing ¹⁶ N in the range from the downcomer downstream to the core inlet. In particular, ¹⁶ N reduction should be effective only in the boiling channel of the core. Ideally, a separate injection system is used, in which nitrogen oxides are used directly in the boiling channel of the core, and hydrogen is used in the downcomer, recirculation piping, and to improve the corrosive environment of the pressure vessel lower plenum.

As the nitrogen oxide to be injected, in addition to NO, NO ₂ , N ₂ O, etc. can be considered, but in any case, injection causes an increase in sulfite ions and nitrate ions in the reactor water, and both have similar problems. Therefore, the above method can be applied to any case.

〔The invention's effect〕

According to the present invention, during the operation of a direct cycle nuclear power plant by injecting nitrogen oxides into reactor water, oxygen atoms in water molecules of reactor water are activated by neutron irradiation to produce radioactive nitrogen. The carry-over of ¹⁶ N from the reactor to the main steam system and further to the turbine system can be significantly suppressed, and the dose rate can be greatly reduced.

Further, it is possible to suppress adverse effects on material corrosion and stress corrosion cracking resistance.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a BWR equipped with a water quality control system consisting of a nitrogen compound injection device and an alkaline substance injection device according to an embodiment of the present invention, and FIG. 2 is a reaction showing a behavior mechanism of nitrogen oxides in a furnace. Formula, Fig. 3 is a graph showing the effect of nitrogen oxide injection on the reduction of ¹⁶ N in the main steam system and changes in reactor water quality, and Fig. 4 is the pH of the cobalt elution rate from cobalt ferrite.
Fig. 5 is a graph showing the dependence, Fig. 5 is a graph showing the corrosion resistance of the material in the presence of nitric acid or sodium nitrate, Fig. 6 is a graph showing the pH and conductivity when nitrogen oxides and alkaline substances are injected, and Fig. 7 is nitrogen. Graph showing the relationship between pH and conductivity with the oxide injection amount as a parameter, Fig. 8 is a graph showing the relationship between corrosion potential, conductivity and the presence or absence of IGSCC generation, and Fig. 9 is nitrogen oxidation after alkali water injection. Graphs showing changes in pH and conductivity with respect to material injection time, FIGS. 10 to 12 are application examples of the present invention, and are schematic views of a BWR for controlling injection of an alkaline substance according to the injection amount of nitrogen oxides. , Fig. 11 is a schematic diagram of BWR in which the injection point is a reactor cleaning system, and Fig. 12 is a schematic diagram of BWR combined with hydrogen injection. FIG. 13 is a diagram showing changes in reactor water quality when hydrogen and nitrogen oxides are simultaneously injected. 1 ... Alkaline substance injection device, 2 ... Nitrogen oxide injection device, 3 ... Reactor water quality monitor (pH monitor, etc.), 4 ...
Controller for controlling water quality of reactor water, 5 ... Reactor, 6 ... Reactor recirculation system, 7 ... Reactor coolant purification system, 8 ... Reactor cooling and purification pump, 9 ... Regenerative heat exchanger, 10 ...... Non-regenerative heat exchanger, 11 …… Reactor coolant purification system filtration desalination equipment, 12
…… Turbine condenser, 13 …… Condensate pump, 14 …… Condensate demineralizer, 15 …… Feed water heater, 16 …… Water feed pump, 17 …… Feed and condensate line, 18 …… Hydrogen injection equipment .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisao Ito 3-1-1, Saiwaicho, Hitachi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Hidefumi Ibe 1168 Moriyama-cho, Hitachi-shi, Ibaraki Shares Company Hiritsu Manufacturing Co., Ltd. Energy Research Institute (72) Inventor Hidetoshi Karasawa 1168 Moriyama-cho, Hitachi, Ibaraki Prefecture 1168 Hiritsu Manufacturing Co., Ltd. Energy Research Institute (72) Hisato Tagawa 1168 Moriyama-cho, Hitachi City, Ibaraki Japan (72) Inventor Makoto Nagase 1168 Moriyama-cho, Hitachi City, Ibaraki Prefecture Hiritsu Seisakusho Co., Ltd. (72) Inventor Shunsuke Uchida 1168 Moriyama-cho, Hitachi City, Ibaraki Hitachi Energy Research Co., Ltd. In-house (72) Inventor Eiji Kikuchi 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Japan In Plant Hitachi Research Laboratory (56) Reference Patent Sho 63-103999 (JP, A) JP flat 1-102396 (JP, A)

Claims (12)

[Claims] 1. A device for injecting nitrogen oxides and an alkaline substance for suppressing transfer of radioactive nitrogen compounds produced by a nuclear reaction in a nuclear reactor in a direct cycle nuclear power plant from reactor water into main steam. A direct cycle nuclear power plant characterized by being provided with an injection device. 2. A device for injecting nitrogen oxides for suppressing the transfer of radioactive nitrogen compounds produced by a nuclear reaction in a nuclear reactor in a direct cycle nuclear power plant from reactor water into main steam, and an alkaline substance are injected. The pH of the reactor water is 7.0-8.5 while monitoring the water quality of the equipment and the water quality of the reactor water.
A direct cycle nuclear power plant, which is provided with a device for controlling the injection amount of the alkaline substance so as to be in the range. 3. An apparatus for injecting nitrogen oxides for suppressing transfer of radioactive nitrogen compounds generated by a nuclear reaction in a nuclear reactor in a direct cycle nuclear power plant from reactor water into main steam, and reactor water. And a device for injecting an alkaline substance, which is provided in a primary system of a nuclear reactor in which a direct cycle is circulated, and a direct cycle nuclear power plant. 4. A device for injecting nitrogen oxides and a non-volatile alkali for suppressing transfer of radioactive nitrogen compounds produced by a nuclear reaction in a nuclear reactor in a direct cycle nuclear power plant from reactor water into main steam. A direct cycle nuclear power plant characterized by having a device for injecting a substance. 5. An apparatus for injecting nitrogen oxides for suppressing transfer of radioactive nitrogen compounds generated by a nuclear reaction in a nuclear reactor of a direct cycle nuclear power plant from reactor water into main steam, and reactor water. And a device for injecting a non-volatile alkaline substance provided in a primary system of a nuclear reactor that circulates a direct cycle nuclear power plant. 6. A device and an ion for injecting nitrogen oxides for suppressing the transfer of radioactive nitrogen compounds produced by a nuclear reaction in a nuclear reactor in a direct cycle nuclear power plant from reactor water into main steam. By making a part of the cation exchange resin filled in the exchange resin into an alkali metal type in advance, during condensate water or reactor water purification, an alkali ion is generated by an ion exchange reaction with a cation in the water. A direct cycle nuclear power plant, which is equipped with a device for injecting an alkaline substance. 7. A device for injecting nitrogen oxides for suppressing transfer of radioactive nitrogen compounds generated by a nuclear reaction in a reactor in a direct cycle nuclear power plant from reactor water into main steam, and reactor water. Is installed in the primary system of the nuclear reactor in which the water is circulated, and when a part of the cation exchange resin filled in the ion exchange resin is made into an alkali metal type in advance, when purifying the reactor water, an alkali ion is generated by an ion exchange reaction with the cation in the water. And a device for injecting an alkaline substance configured so as to generate a direct cycle nuclear power plant. 8. An apparatus for injecting nitrogen oxides for suppressing transfer of radioactive nitrogen compounds produced by a nuclear reaction in a reactor in a direct cycle nuclear power plant from reactor water into main steam, and reactor water. Is installed in the primary system of the circulating reactor, and a part of the cation exchange resin filled in the ion exchange resin is preliminarily made into an alkali metal type, and when the reactor water is purified, the alkali ion is generated by the ion exchange reaction with the cation in the water. And a device for injecting a non-volatile alkaline substance configured so as to generate a direct cycle nuclear power plant. 9. A method for operating a direct cycle nuclear power plant, which is operated by injecting nitrogen oxides and an alkaline substance into reactor water of the direct cycle nuclear power plant. 10. A nitrogen oxide is injected for suppressing the transfer of radioactive nitrogen compounds produced by a nuclear reaction in a nuclear reactor in a direct cycle nuclear power plant from reactor water into main steam, and an alkaline substance is added. Injection, while monitoring the water quality of the reactor water, so that the pH of the reactor water is in the range of 7.0 ~ 8.5, operating while controlling the injection amount of the alkaline substance of the direct cycle nuclear power plant characterized by how to drive. 11. A hydrogen injection facility for reducing the dissolved oxygen concentration in a nuclear reactor in a direct cycle nuclear power plant by combining it with hydrogen atoms, and a radioactive nitrogen compound produced by the reaction from reactor water into main steam. Direct cycle nuclear power plant characterized by being provided with a device for injecting nitrogen oxides for suppressing migration 12. A hydrogen injection facility for reducing the dissolved oxygen concentration in a nuclear reactor in a direct cycle nuclear power plant by combining it with hydrogen atoms, and a radioactive nitrogen compound produced by the reaction from reactor water into main steam. A direct cycle nuclear power plant, which is provided with a device for injecting nitrogen oxides and a device for injecting an alkaline substance for suppressing migration.