JP3357779B2 - Water handling equipment and water handling method for pressure and leak inspection of nuclear reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, the construction of a light water nuclear power plant, in which a pressure test and a leak test for a reactor, its attached piping and valves, and the like are performed. The present invention relates to a water handling device and a water handling method in a pressure and leak inspection of a nuclear reactor applied for drainage and the like.

[0002]

2. Description of the Related Art In a boiling water nuclear power plant, for example, a reactor pressure vessel 2 is housed in a reactor containment vessel 1 as shown in FIG. The control rod drive mechanism housing 4 and the neutron flux measurement housing 5 and the like protrude in large numbers. The reactor pressure vessel 2 is provided with a large number of auxiliary pipes 6 having valves connected by welding or the like, and a sump tank 7 is provided below the reactor pressure vessel 2.

At the time of construction of such a boiling water nuclear power plant, the reactor pressure vessel 2 must be used during a test operation.
Also, a pressure resistance / leakage inspection is performed on the attached pipe 6 or the valve.

[0004] In the pressure resistance / leakage inspection, various preparation conditions are required before the inspection. For example, it is necessary that the welded portion of the attached pipe 6 to be inspected of the reactor pressure vessel 2 is not coated or heat-treated, and is in a state that can be visually confirmed. It is also necessary that rust, oil, dust, and the like have been removed from the surface to be inspected in advance. Furthermore, it is necessary that the designated nondestructive inspection has been completed for the welded parts to be inspected, that the specified pipe cleaning has been completed, and that the installation of the test pipes and equipment has been completed. . Furthermore, the construction of the piping support structure and the removal of the furnace internal structures (steam dryer, shroud head, etc.) have been completed, and the valves related to the pressure resistance / leak test have been completely opened and closed. (To secure the boundary) is also required.

For the control rod drive mechanism housing 4 and the neutron flux measurement housing 5 protruding from the furnace bottom 3 of the reactor pressure vessel 2, a flange-shaped closing lid, that is, a closing flange is prepared as a preparation work for leak inspection. Need to be installed.

FIG. 6 shows the structure of a conventionally used closing flange. As shown in FIG.
The closing flange 8 is provided at the lower end flange portions 4a, 5a of the control rod drive mechanism housing 4 or the neutron flux measuring housing 5.
And is joined to the lower end surface thereof. The closing flange 8 includes a control rod driving mechanism housing 4 or a scrum piping hole 10 together with a bolt hole 9 and a scrum piping hole 10 for connecting to the control rod driving mechanism housing 4 or the lower end flange portions 4a, 5a of the neutron flux measuring housing 5. A drain hole 11 opening inside the neutron flux measurement housing 5 is formed. As means for opening and closing the drain hole 11 of the closing flange 8, conventionally, the drain hole 1 is used.
1 and a female screw 12 is formed on the female screw 12.
Plug 14 with external thread 13 that can be screwed into
Is provided. Then, the plug 14 is normally screwed into the drain hole 11 of the closing flange 8 from below and is inserted in a watertight manner to seal the drain hole 11.

[0007] Conventionally, when a pressure resistance / leakage inspection of the reactor pressure vessel 2 is performed, first, after the above-described preparation conditions are prepared, the following steps are taken.
Test water (pure water) heated to 0 ° C. or more is injected into the reactor pressure vessel 2 from each attached pipe 6. Then, it is confirmed that the test water overflows from a vent pipe (not shown) at the top of the reactor pressure vessel 2, and the injection is stopped. Thereafter, it is confirmed that the temperature of the reactor pressure vessel 2 has reached 10 ° C. or higher, and the top flange 15 of the reactor pressure vessel 2 is tightened. A pressure is applied to the attached pipe 6 and the like using a mechanism pump.

FIG. 7 is a graph showing an example of this pressurizing method, in which the vertical axis represents pressure and the horizontal axis represents time. As shown in FIG. 7, every time the inside of the furnace reaches the set pressure, the pressure is increased while holding for a predetermined time. For example, after confirming that the test pressure and the test temperature have reached a predetermined value, and after holding for 30 minutes, the inspection target part of each pipe is divided into each group, and a pressure resistance / leakage inspection of a pipe welded flange or the like is performed. .

When the inspection is completed, the pressure is reduced, and then the test water is drained. The drain in the control rod drive mechanism housing 4 and the neutron flux measurement housing 5 is removed from the closing flange 8 attached to the flanges 4 and 5 by opening the plug 14 to open the drain hole 11 and flowing down to the lower sump tank. Let it. In addition, re-install the main parts removed for the test, and remove the temporary piping and test equipment.

[0010]

In the conventional water handling method described above, the drain in the control rod drive mechanism housing 4 and the neutron flux measurement housing 5 is drained by removing the plug 14 from the closing flange 8 and draining the drain. 7 was flowing down.

In this case, there is no particular problem in the conventional boiling water reactor, but in a recently improved boiling water reactor (improved boiling water reactor), a fine adjustment type using an electric motor is used. The control rod drive mechanism is adopted and the reactor pressure vessel 2
At the time of the pressure resistance / leak test, a large number of electric components, particularly cables, are laid below the control rod drive mechanism housing 4. For this reason, if the plug 14 is simply removed from the plug flange 8 of the control rod drive mechanism housing 4 and the neutron flux measurement housing 5 after the pressure resistance / leakage test and drained, a large amount of water is sprayed on electric parts such as cables. Could be done. Therefore, the subsequent work will require an extra curing period for drying etc.
There are disadvantages such as extending the construction period. In some cases, there is a possibility that cables and connectors may be damaged, and replacement may be required.

In the case of the above-mentioned improved boiling water reactor, the internal pump is used for the purpose of preventing foreign matter from entering the sliding portion of the internal pump when water is filled by employing the internal pump. It is necessary to fill about 100 tons of water until the impeller sinks. About this work, 7.8 from the purge line of the internal pump
Since it is filled with water at a rate of liters / minute, it takes a lot of time, which is a waste of time in a limited inspection process, and may have a great effect on securing the entire process. .

Further, in the conventional boiling water reactor, a reactor recirculation pump provided outside the reactor pressure vessel is provided, so that the reactor pressure vessel can be easily heated by hot water circulation. However, in the improved boiling water reactor, circulation heating is difficult due to the internal pump.

[0014] The above-mentioned difficulty is a problem that also occurs in the periodic inspection after the operation of the nuclear power plant.
Countermeasures from that aspect are also needed.

The present invention has been made in view of such circumstances, and has been made to improve the efficiency of water filling in a reactor, prevent the wetting of peripheral electric components at the time of draining water from the reactor, and increase the temperature of the reactor by circulating hot water. It is possible to increase the efficiency of temperature, etc., which in turn shortens the construction period and man-hours of nuclear power plants, shortens time and man-hours in periodic inspections, and effectively reduces radioactive waste, radiation exposure, quality control, etc. It is an object of the present invention to provide a water handling apparatus and a water handling method for a pressure and leak inspection of a nuclear reactor that can be achieved.

[0016]

In order to achieve the above object, according to the first aspect of the present invention, the lower end of a control rod drive mechanism housing provided at the bottom of a nuclear reactor is closed with a closing flange, and the closing is performed. In one in which the drain hole formed in the flange can be opened and closed, as a means for opening and closing the drain hole of the closing flange, a one-touch coupler including a female element and a male element that can be attached to and detached from the female element is provided. The female element of this one-touch coupler is watertightly inserted into the drain hole of the closing flange to form a normally closed structure, while the male element of the one-touch coupler is connected to a water supply / drainage hose, and the two elements are connected to each other. The inner space of the housing and the hose communicate with each other to allow water to flow therethrough.
Provide a water handling device for leak inspection.

According to a second aspect of the present invention, the lower end of the neutron flux measurement housing provided at the bottom of the reactor is closed with a closing flange, and a drain hole formed in the closing flange can be opened and closed. As means for opening and closing the drain hole of the flange, a one-touch coupler comprising a female element and a male element detachable from the female element is provided, and the female element of this one-touch coupler is watertightly connected to the drain hole of the closing flange. On the other hand, the male element of the one-touch coupler is connected to a water supply / drainage hose, and the inner space of the housing and the hose communicate with each other by connecting the two elements to allow water to flow. Reactor pressure resistance
Provide a water handling device for leak inspection.

According to a third aspect of the present invention, there is provided a method for filling a water in a nuclear reactor at the time of pressure resistance / leakage inspection of the nuclear reactor using the water handling apparatus according to the first or second aspect, wherein The hose connected to the side element is connected to the water supply means, and in a state where the male element of the one-touch coupler is connected to the female element, water is supplied from the water supply means into the reactor via the hose. Provide a water handling method for pressure and leak inspection of reactors.

According to a fourth aspect of the present invention, there is provided a method for circulating hot water in a nuclear reactor at the time of pressure and leak inspection of a nuclear reactor using the water handling apparatus according to the first or second aspect. A hose connected to the side element is connected to the hot water discharge side of the hot water supply means, and a drainage pipe led from the top of the reactor is connected to the hot water suction side of the hot water supply means to form a closed loop hot water circulation system. Wherein the male element of the one-touch coupler is connected to the female element, and hot water is circulated through the hot water circulation system into the reactor through the hot water circulation system. Provide handling methods.

According to a fifth aspect of the present invention, there is provided a method for pressurizing the inside of a nuclear reactor at the time of a withstand pressure / leakage inspection of the nuclear reactor using the water handling apparatus according to the first or second aspect. The pressurized water is supplied from the pressurizing means to the reactor via the hose while the male element of the one-touch coupler is connected to the female element in advance with the hose connected to the pressurizing means connected to the hose. Provided is a water handling method for pressure and leak inspection of a nuclear reactor, characterized in that:

According to a sixth aspect of the present invention, there is provided a method for draining water from a nuclear reactor at the time of pressure resistance / leakage inspection of a nuclear reactor using the water handling apparatus according to the first or second aspect. The hose connected to the element is connected to the sump tank, and the water in the reactor is guided to the sump tank via the hose while the male element of the one-touch coupler is connected to the female element. Provide a water handling method for pressure and leak inspection of reactors.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 4, an embodiment of a water handling apparatus and a water handling method in a pressure and leak inspection of a nuclear reactor according to the present invention will be described with reference to an improved boiling water reactor. A description will be given of a case where the present invention is applied.

FIG. 1 is a system diagram showing an overall configuration of a reactor pressure vessel and a water handling apparatus, and FIG. 2 is an enlarged view showing a furnace bottom of the reactor pressure vessel shown in FIG. FIG. 3 is a plan view of the closing flange, and FIG. 4 is a diagram showing the closing flange shown in FIG.

In this embodiment, as shown in FIGS. 1 and 2, a reactor pressure vessel 2 having an internal pump 20 is provided.
A number of control rod drive mechanism housings 22 and neutron flux measurement housings 23 are provided at the bottom of the housing 1.

As shown in FIGS. 1, 3, and 4, lower end flanges 22a, 23a of the control rod drive mechanism housings 22 and the neutron flux measurement housings 23 have
Each of the closing flanges 24 is connected from below.
Each closing flange 24 is connected to the control rod drive mechanism housing 22.
And the lower end flange portions 22a, 23a of the neutron flux measurement housing 23 are formed in a disk shape having substantially the same shape as the control rod drive mechanism housing 2.
2 and a control rod drive mechanism housing 22 together with a bolt hole 25 and a scrum pipe hole 26 for connection to the lower end flange portions 22a, 23a of the neutron flux measurement housing 23.
In addition, a drain hole 27 that opens inside the neutron flux measurement housing 23 is formed.

In this embodiment, as means for opening and closing the drain hole 27 of the closing flange 24, the female element 2
8 and a one-touch coupler 30 comprising a male element 29 that can be attached to and detached from the female element 28.
The female element 28 of the one-touch coupler 30 is watertightly inserted into the drain hole 27 of the closing flange 24 via an O-ring 30a to have a normally closed structure. On the other hand, the male element 29 of the one-touch coupler 30 is connected to a hose 31 for water supply and drainage, and the hose 31 for water supply and drainage is provided with a manual open / close valve 32.

The drain hole 27 of the closing flange 24
Female element 2 of one-touch coupler 30 inserted in
By connecting the male side element 29 connected to the water supply / drainage hose 31 to the water supply / drainage hose 8, the internal space of the control rod drive mechanism housing 22 and the neutron flux measurement housing 23 and the water supply / drainage hose 31 are communicated. I have.

In this embodiment, as shown in FIG.
The hose 31 connected to the male element 28 of the one-touch coupler 30 is connected to a water supply pump 35 via a header 33 and a water supply pipe 34, and the drain pipe 3
6 is connected to a sump tank 37. Further, the hose 31 is connected to the boiler 3 as a hot water supply means.
8 is connected to the hot water discharge side via a discharge pipe 39, and a drain pipe 40 led from the top of the reactor pressure vessel 21 is connected to the suction side of the boiler 38, thereby forming a closed loop hot water circulation system. 41 are formed. In addition,
Each of the pipes 34, 36, 39, 40 has an on-off valve 4
2, 43, 44 and 45 are provided.

Using the water handling apparatus according to the present embodiment having the above-described configuration, a pressure resistance / leakage inspection is performed by the following method during a test operation during construction of a nuclear power plant.

At the time of this inspection, the same preparation conditions as those of the prior art, that is, the coating portion and the heat retaining process were not applied to the welded portion of the attached piping to be inspected of the reactor pressure vessel 21 were visually confirmed. It must be possible, rust, oil, dust, etc. have been removed from the surface to be inspected in advance, specified non-destructive inspection has been completed for the welded parts to be inspected, etc. That the installation of test pipes and equipment has been completed, that the installation of pipe support structures and the removal of furnace internal structures (steam dryers, shroud heads, etc.) have been completed, It is necessary that the valves related to the pressure resistance / leakage test are completely opened and closed (to secure the boundary).

The control rod drive mechanism housing 22 and the neutron flux measurement housing 23 projecting from the bottom of the reactor pressure vessel 21 are provided with the above-mentioned closing flange 2.
4 is mounted in advance, and the female element 28 of the one-touch coupler 30 is water-tightly mounted in the drain hole 27 of the closing flange 24, and the male element 29 is connected to the female element 28 to drive the control rod. The mechanism housing 22 and the neutron flux measurement housing 23 are connected to the hose 31. The on-off valves 42, 4 of the pipes 34, 36, 39, 40 shown in FIG.
3, 44 and 45 are initially closed.

When the hot water is circulated in the reactor pressure vessel 21, the feed water is heated by the boiler 38 and the open / close valves 44, 45 of the pipes 39, 40 of the hot water circulation system 41 are opened. , And on-off valve 3 for each hose 31
Open 2 Thereby, the hot water is circulated into the reactor pressure vessel 21 via the hot water circulation system 41, and when the reactor pressure vessel 21 becomes, for example, 10 ° C. or more, the opening and closing of each pipe 39, 40 of the hot water circulation system 41 is performed. The valves 44 and 45 are closed, and the heating of the feed water by the boiler 38 is stopped, thereby stopping the circulation of the hot water.

According to the method of the present embodiment as described above, even in the improved boiling water reactor without the inter-reactor circulation pump, the hot water circulation to the reactor pressure vessel 21 can be efficiently performed,
The heating of the reactor pressure vessel 21 can be performed in a short time.

To pressurize the reactor pressure vessel, the water supply pump 35 shown in FIG. 2 is driven, the open / close valve 42 of the water supply pipe 34 is opened, and each hose 3
The first on-off valve 32 is opened. Thereby, the water supply pump 3
From 5, water is supplied into the reactor pressure vessel 21 via a hose 31. By performing the pressurizing operation in such a manner, water can be supplied through the large number of control rod drive mechanism housings 22 and the neutron flux measuring housings 23, so that high-efficiency pressurization becomes possible and the pressurizing time can be reduced. . As for the pressure resistance / leakage inspection by pressurization, as shown in FIG.
Each time the inside of the furnace reaches the set pressure, the pressure is increased while holding for a predetermined time, for example, confirming that the test pressure and the test temperature have reached the predetermined values, and after holding for 30 minutes, each piping The inspection target parts are divided into groups, and the flanges of the welded pipes are inspected.

After the inspection is completed, the open / close valve 4 of the water supply pipe 34
2 and the on / off valve 32 of each hose 31 are closed, the water supply pump 35 is stopped, and the following pressure reduction and drainage are performed.

That is, the control rod drive mechanism housing 22
And, in a state where the inside of the neutron flux measurement housing 23 is connected to the sump tank 37 via the one-touch coupler 30, the hose 31, the header 33, and the drainage pipe 36, the open / close valve 43 of the drainage pipe 36 is opened,
The water in the reactor pressure vessel 21 is led to the sump tank 37.

According to such a drainage method, since the drainage is guided to the sump tank 37 in a certain system, even if a large number of electric parts such as wiring are disposed below the reactor pressure vessel 21. , There is no danger of splashing them. Therefore, there is no need to cure the electric components and the like, and there is no possibility of damage or the like.

Although the above embodiment has been described with respect to the pressure resistance / leakage inspection at the time of construction of the nuclear power plant, the inspection can be performed in the same manner as described above at the time of the periodic inspection.

As described above, according to the water handling method of the present embodiment, it is possible to shorten the time for filling the water in the reactor pressure vessel, draining water, and the like during the construction and periodic inspection of the nuclear power plant. In addition, since the cable work around the housing can be performed in parallel during the inspection of the reactor pressure vessel, the construction period can be shortened. In addition, it is possible to reduce man-hours and radiation exposure because there is no water scattering, and it is also possible to reduce radioactive waste and radiation exposure in a friendly manner.

[0040]

As described above in detail, according to the water handling apparatus and the water handling method for pressure and leak inspection of a nuclear reactor according to the present invention, the water filling efficiency in the reactor can be improved, Prevention of wetting of surrounding electrical products when draining water,
It is possible to increase the efficiency of reactor heating by hot water circulation, thereby shortening the construction period and man-hours of nuclear power plants, reducing the time and man-hours required for periodic inspections, reducing radioactive waste, reducing exposure, and quality control. Effects such as effective improvement can be achieved.

[Brief description of the drawings]

FIG. 1 shows one embodiment of the present invention, and is a system diagram showing an overall configuration of a reactor pressure vessel and a water handling device.

FIG. 2 is an enlarged view showing a reactor bottom of the reactor pressure vessel shown in FIG.

FIG. 3 is a plan view of a closing flange according to the embodiment.

FIG. 4 is a diagram showing a longitudinal section of the closing flange shown in FIG. 3 and a side view showing a state in which a hose is attached to the closing flange.

FIG. 5 is an overall view showing a configuration around a reactor pressure vessel of a boiling water reactor.

FIG. 6 is a sectional view showing a conventional water handling apparatus.

FIG. 7 is a graph showing a pressurizing method of a pressure resistance / leakage inspection.

[Explanation of symbols]

 Reference Signs List 20 internal pump 21 reactor pressure vessel 22 control rod drive mechanism housing 23 neutron flux measurement housing 22a, 23a lower end flange 24 closing flange 25 bolt hole 26 scrum piping hole 27 drain hole 28 female side element 29 male side element 30 one-touch coupler 30a O-ring 31 Supply / drain hose 32 Open / close valve 33 Header 34 Water supply pipe 35 Water supply pump 36 Drainage pipe 37 Sump tank 38 Boiler 39 Discharge pipe 40 Drainage pipe 41 Hot water circulation system 42, 43, 44, 45 Open / close valve

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21C 17/00 G21C 17/02

Claims (6)

(57) [Claims] 1. A control rod drive mechanism housing provided at the bottom of a nuclear reactor, wherein a lower end of the housing is closed by a closing flange, and a drain hole formed in the closing flange is openable and closable. A one-touch coupler composed of a female element and a male element detachable from the female element, and the female element of the one-touch coupler is inserted into the drain hole of the closing flange to be normally closed. On the other hand, the male element of the one-touch coupler is connected to a hose for water supply and drainage, and the connection between the two elements allows the internal space of the housing to communicate with the hose to allow water to flow. Water handling equipment for pressure and leak inspection of nuclear reactors. 2. The method according to claim 1, wherein a lower end of the neutron flux measurement housing provided at the bottom of the reactor is closed with a closing flange, and a drain hole formed in the closing flange can be opened and closed. As a means for opening and closing, a one-touch coupler comprising a female element and a male element detachable from the female element is provided, and the female element of the one-touch coupler is inserted into the drain hole of the closing flange to form a normally closed structure. On the other hand, the male element of the one-touch coupler is connected to a water supply / drainage hose, and the connection between the two elements allows the internal space of the housing to communicate with the hose to allow water to flow. Water handling equipment for furnace pressure and leak inspection. 3. A method for filling a reactor with water at the time of pressure resistance / leakage inspection of a reactor using the water handling apparatus according to claim 1 or 2, wherein the water handling apparatus is connected to a male element of a one-touch coupler. A reactor connected to a water supply means and a male element of the one-touch coupler connected to the female element, and water is supplied from the water supply means into the reactor via the hose. Water handling method for pressure resistance and leak inspection. 4. A method for circulating hot water in a nuclear reactor at the time of pressure resistance / leakage inspection of a nuclear reactor using the water handling device according to claim 1 or 2, wherein the hot water is connected to a male element of a one-touch coupler. A hose is connected to the hot water discharge side of the hot water supply means, and a drainage pipe led from the top of the reactor is connected to the hot water suction side of the hot water supply means to form a closed loop hot water circulation system. And a method for handling water in a pressure resistance / leakage inspection, wherein hot water is circulated in the reactor via the hot water circulation system in a state where the male element of the one-touch coupler is connected to the female element. 5. A method for pressurizing the inside of a nuclear reactor at the time of pressure and leak inspection of a nuclear reactor using the water handling apparatus according to claim 1 or 2, wherein a hose connected to a male element of a one-touch coupler is provided. In a state where the male element of the one-touch coupler is connected to the female element, pressurized water is supplied from the pressurizing means to the reactor through the hose while the one-touch coupler is connected to the female element. Water handling method for pressure and leak inspection of reactors. 6. A method for draining water from a nuclear reactor at the time of pressure and leak inspection of a nuclear reactor using the water handling apparatus according to claim 1 or 2, wherein the hose is connected to a male element of a one-touch coupler. Is connected to the sump tank,
A water handling method for pressure and leak inspection of a reactor, wherein water in the reactor is guided to the sump tank through the hose in a state where the male element of the one-touch coupler is connected to the female element. .