JP2007071800A - Boiling water type nuclear power generation plant and its piping cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning stagnant water in an emergency core cooling water system of a nuclear power plant. <P>SOLUTION: An equalizing valve 19 is connected with an injection check valve 14 of the emergency core cooling system injection pipe 12 and a pipe for cleaning 101 is branched between upper and lower two step drain valves 21 provided to the drain pipe 20 connected with the equalizing pipe 18 of the equalizing valve 19 to connect to a reactor coolant purification system suction pipe 31 in the constitution. In regular inspection of the nuclear power plant, water in the emergency core cooling system injection pipe 12 is passed in the equalizing pipe 18, the drain pipe 20 and the pipe for cleaning 101 in turn together with reactor water with a reactor coolant cleaning system pump 32 by opening the equalizing valve 19. Thus, water is purified with a reactor coolant purification system equipment 33 and is returned to the reactor pressure vessel 1 by way of a reactor water supply system pipe 34. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a purification technique in an emergency core cooling system injection pipe in a boiling water nuclear power plant.

  The emergency core cooling system of the boiling water nuclear power plant has a total of five systems including three series of low-pressure water injection systems using a residual heat removal system, a low-pressure core spray system, and a high-pressure core spray system.

  The emergency core cooling system has a function of supplying suppression pool water to the reactor pressure vessel and maintaining the water level in the reactor pressure vessel at a safe water level in the event of loss of coolant in the reactor pressure vessel.

  Therefore, during the normal operation of the reactor that is not in the state of the accident, the emergency core cooling system is in a standby state, the emergency core cooling system pump is stopped, and the injection isolation valve to the reactor is fully closed. The fluid (water) in the injection pipe between the isolation valve and the reactor containment vessel is always stagnant for about one year during normal operation of the reactor.

  In addition, during the periodic inspection of the reactor, depending on the inspection frequency of the injection check valve installed on the emergency core cooling system injection pipe in the reactor containment and the planning process, the injection isolation valve and the reactor The fluid (water) in the injection pipe between the containment vessel is stagnant for several years, and corrosion products such as rust may be generated in the injection pipe.

  Note that carbon steel materials are generally used as materials for piping and valves of the emergency core cooling system.

  In general operations during normal operation of the reactor and during regular inspections, corrosion products such as rust generated in the injection pipes of this emergency core cooling system are not poured into the reactor except in an emergency. Absent.

  In recent years, efforts have been made to improve the utilization efficiency of the nuclear power plant by shortening the inspection period of the nuclear power plant and securing a long operation period of the plant. To shorten the inspection period, rationalization of inspection work, review of work procedures, introduction of shift work system, etc. are being studied.

  Although there is no prior art related to purifying the water quality in the injection pipe between the emergency core cooling system injection isolation valve and the containment vessel, there is no prior art for the reactor coolant purification system and the emergency core cooling system. The residual heat removal system, which is the main part, is connected by piping, reducing the radiation of the residual heat removal system heat exchanger as a cooling function when the reactor is shut down, reducing the radiation dose received by workers during regular inspections The invention that describes the invention to be performed is known (see, for example, Patent Document 1).

  In Patent Document 1, an emergency pipe is provided between a reactor coolant purification system that purifies reactor water during normal reactor operation and a residual heat removal system that circulates and cools reactor water when the reactor is shut down. Residual heat removal system, which is one of the core heat cooling systems, is made to flow by constantly passing purified high-temperature cooling water at the outlet of the reactor coolant purification system to the piping and heat exchanger upstream of the injection isolation valve. It is possible to reduce the radioactivity adhering to the heat removal system and reduce the radiation dose received by the workers during the periodic inspection.

JP-A-9-68590

  During regular inspections of nuclear power plants, water is applied to the reactor pressure vessel and a pool called a reactor well formed at a position covering the reactor pressure vessel, and the radiation from the reactor pressure vessel is flushed with water. Implement shielding.

  Water filling to the reactor pressure vessel and reactor well is performed by supplying condensate from the condensate storage tank via the makeup water system piping. It took about a day to fill the water.

  In order to shorten the inspection period of a nuclear power plant and improve the utilization efficiency of the plant, it is also necessary to devise measures to shorten the water filling time to the reactor pressure vessel and the reactor well at the time of periodic inspection.

  Since the piping of the make-up water system is for cleaning before maintenance and inspection of the emergency core cooling system piping and equipment, etc., the cleaning piping is also connected upstream of the injection isolation valve of the emergency core cooling system. An operation for shortening the water filling time can be considered by supplying condensate to the reactor pressure vessel and the reactor well using the cleaning pipe of the emergency core cooling water system.

  However, the following issues are encountered when such operations are performed. In other words, in order to shorten the water filling time to the reactor pressure vessel and the reactor well, when using as the water filling line to the reactor pressure vessel and the reactor well using the cleaning pipe of the emergency core cooling water system, Of the core cooling system injection piping, stagnant water that has been stagnating for a long time in the piping between the injection isolation valve and the reactor pressure vessel is supplied to the reactor pressure vessel and reactor well along with corrosion products, temporarily. Water transparency decreases. Therefore, it becomes difficult to carry out inspection work and fuel loading work in the nuclear reactor performed after water filling. In order to expedite the implementation of each work, water in the reactor pressure vessel and reactor well is purified by the reactor coolant purification system, but the work start time is delayed until the purification proceeds, and the water filling time is shortened. May be damaged.

  Further, in the region where the carbon steel pipe is stagnant for a long time, not only the accumulated amount of corrosion products increases, but also the accumulated corrosion products are aggregated.

  If this agglomerated corrosion product settles at the bottom of the reactor pressure vessel, it becomes difficult to purify by the reactor coolant purification system, and if many corrosion products are precipitated in the reactor pressure vessel, The amount of corrosion products adhering to the surface of the fuel cladding tube increases, and further, radiation emitted from the fuel results in an increase in the amount of radioactive material in the corrosion products, which is not preferable.

  As described above, in order to reduce the water filling time to the reactor pressure vessel and the reactor well using the emergency core cooling system that is a long-term stagnant water with carbon steel material, It is desirable to remove the corrosion products that accumulate in the area that becomes stagnant water and to prevent the accumulated corrosion products from aggregating.

  Therefore, an object of the present invention is to purify stagnant water in the emergency core cooling system injection pipe of a boiling water nuclear power plant, thereby shortening the periodic inspection of the plant and improving the operation efficiency of the plant. It is in.

Means for achieving the object of the present invention includes an emergency core cooling system for injecting water into a reactor pressure vessel with an injection pipe equipped with an injection isolation valve,
A purification device for purifying cooling water in the reactor pressure vessel;
A reactor coolant purification system for supplying the cooling water purified by the purification device to the reactor pressure vessel;
It is a boiling water nuclear power plant provided with a pipe line connecting the downstream portion of the injection pipe with respect to the injection isolation valve and the upstream portion of the reactor coolant purification system with respect to the purification device.

  Also, the water in the injection pipe downstream from the injection isolation valve of the emergency core cooling system of the boiling water nuclear power plant is sucked into the reactor coolant purification system of the boiling water nuclear power plant and purified. The water after the purification is returned to the reactor pressure vessel of the boiling water nuclear power plant, and the water in the reactor pressure vessel is caused to flow into the injection pipe on the downstream side of the injection isolation valve. This is a piping purification method for a boiling water nuclear power plant.

  According to the present invention, the formation of corrosion products in the injection pipe between the injection isolation valve of the emergency core cooling system and the reactor pressure vessel in the boiling water nuclear power plant can be suppressed. Even if the reactor pressure vessel and the reactor well are filled with water during the periodic inspection of the power plant via the injection pipe, there is an effect that the operation efficiency of the plant can be improved without prolonging the periodic inspection.

  The light water nuclear power plant is a plant that generates high-temperature and high-pressure steam in the reactor pressure vessel 1, drives a steam turbine with the steam, and drives a generator with the steam turbine to generate electric power. The reactor pressure vessel 1 contains a core loaded with nuclear fuel, and the coolant in the reactor pressure vessel 1 is passed through the reactor coolant recirculation system piping 6 by the reactor coolant recirculation pump 5. The steam is generated by heating the cooling water in the reactor core. Thus, since the reactor pressure vessel 1 is provided with a core loaded with nuclear fuel, the reactor pressure vessel 1 is placed in the reactor containment vessel 2 so that radiation and radioactive materials do not leak in an unintended situation. Stored.

  When an accident is assumed in which the cooling water is lost from the reactor pressure vessel 1, there is a concern that the core may be exposed upward from the surface of the cooling water due to the loss of the cooling water and cannot be cooled. An emergency core cooling system that supplies cooling water into the reactor pressure vessel 1 is provided to eliminate the concern and safely end the accident of loss of cooling water.

  The emergency core cooling system in the light water nuclear power plant has a configuration of three series of low-pressure water injection systems 7 using a residual heat removal system, and a total of five series of low-pressure core spray systems 8 and high-pressure core spray systems 9. Since the five systems of the emergency core cooling system are basically the same, the high pressure core spray system 9 is referred to as an emergency core cooling system and is exemplified below as representative of the five systems.

  The emergency core cooling system uses the suppression pool water 4 in the suppression pool 3 installed in the reactor containment vessel 2 as one water source. In the emergency core cooling system, one end of the emergency core cooling system injection pipe 12 communicates with the suppression pool 3 and the other end communicates with the reactor pressure vessel 1. An emergency core cooling system pump 11 is provided in the middle of the emergency core cooling system injection pipe 12. The emergency core cooling system pump 11 exerts a driving force that sucks the suppression pool 3 water into the emergency core cooling system injection pipe 12 and supplies the water into the reactor pressure vessel 1 through the emergency core cooling system injection pipe 12. . Therefore, in the emergency core cooling system, the water flow is such that the suppression pool 3 side is upstream and the reactor pressure vessel 1 side is downstream.

  An injection isolation valve 13 is provided outside the reactor containment vessel 2 in the middle of the emergency core cooling system injection pipe 12 downstream of the emergency core cooling system pump 11 of the emergency core cooling system injection pipe 12. The suppression pool 3 is responsible for supplying and stopping water into the reactor pressure vessel 1.

  An injection check valve 14 is provided in a portion of the emergency reactor cooling system injection pipe 12 in the reactor containment vessel 2 so as to prevent a back flow from the reactor pressure vessel 1 to the suppression pool 3 side. ing. Further, a maintenance stop valve 15 is provided in the emergency core cooling system injection pipe 12 closer to the reactor pressure vessel 1 than the injection check valve 14. The maintenance stop valve 15 closes the emergency core cooling system injection pipe 12 so that the cooling water in the reactor pressure vessel 1 does not reach the injection check valve 14 when the injection check valve 14 is overhauled. It is used at all times and is always open at times other than the inspection.

  One end of a pipe forming a test line 17 is connected to a portion of the emergency core cooling system injection pipe 12 between the emergency core cooling system pump 11 and the injection isolation valve 13, and the other end of the pipe is the suppression pool. 3 is connected. A test valve 16 is provided in the middle of the test line 17, and the emergency core cooling system pump 11 is opened during a test operation when the emergency core cooling system is tested, and is closed in other cases.

  In the portion of the emergency core cooling system injection pipe 12 between the injection isolation valve 13 and the connection portion of the test line 17 to the emergency core cooling system injection pipe 12, an emergency core cooling system cleaning pipe 41 is provided. The cleaning valve 42 and the check valve are connected to each other. This emergency core cooling system cleaning pipe 41 is a pipe constituting the condensate makeup water system, and the water contained in the condensate storage tank or the like by the pump in the condensate makeup water system is used at a high pressure for the emergency core cooling system. It is possible to clean the emergency core cooling system injection pipe 12 and the emergency core cooling system pump 11 by injecting into the injection pipe 12. During the cleaning, the cleaning valve 42 is opened.

  As shown in part A (detailed view) showing an enlarged part A of the emergency core cooling system, the injection check valve 14 provided in the emergency core cooling system injection pipe 12 includes an injection check valve. 14 is equipped with a pressure equalizing valve 19 that equalizes the pressure difference between the upstream side and the downstream side. The pressure equalizing valve 19 and the injection check valve 14 are connected by a pair of pressure equalizing pipes 18, a pressure equalizing pipe near the reactor pressure vessel 1 that receives the same pressure as the inside of the reactor pressure vessel 1, and an emergency core cooling system. A pair of pressure equalizing pipes close to the injection isolation valve 13 receiving the same pressure as in the injection pipe 12 is paired. In the check of the injection check valve 14, etc., the pressure equalizing valve 19 is opened so that the pressure difference between the upstream side and the downstream side of the injection check valve 14 can be eliminated. Except during the inspection of the nuclear power plant, the pressure equalizing valve 19 is closed so that the function of the injection check valve 14 can be exhibited.

  A drain pipe 20 is connected to the pressure equalizing pipe 18 near the injection isolation valve 13. The drain pipe 20 is equipped with two drain valves 21 in series. When the maintenance stop valve 15 is closed and the drain valve 21 and the pressure equalizing valve 19 are opened, the water in the emergency core cooling system injection pipe 12 between the maintenance stop valve 15 and the injection isolation valve 13 becomes drain pipe 20 or drain. It is sent to the wastewater treatment facility through the valve 21, and the check of the injection check valve 14 becomes possible.

  Next, the reactor coolant purification system will be described. The reactor coolant purification system equipped in the light water nuclear power plant has a reactor coolant purification system suction pipe 31 that connects the reactor coolant recirculation system pipe 6 and the reactor water supply system pipe 34. . The reactor water supply system pipe 34 is connected to the reactor pressure vessel 1 and serves as a flow path for supplying condensate condensed with steam used in the steam turbine into the reactor pressure vessel 1.

  The reactor coolant purification system suction pipe 31 is connected in series with a reactor coolant purification system pump 32 and a reactor coolant purification system purification facility (for example, a demineralizer is used) 33. In such a reactor coolant purification system, the reactor coolant purification system pump 32 is operated to supply coolant from the reactor coolant recirculation system pipe 6 or the reactor pressure vessel 1 to the reactor coolant purification system suction pipe. It can be sucked into 31 and supplied to the reactor coolant purification system purification equipment 33 through the same pipe. Here, the cooling water is purified by the reactor coolant purification system purification equipment 33. Cooling water purified by the reactor coolant purification system purification equipment 33 is supplied from the reactor coolant purification system suction pipe 31 into the reactor feed water system pipe 34 and passes through the reactor feed water system pipe 34 to the inside of the nuclear pressure vessel 1. Can supply.

  Such a reactor coolant purification system and an emergency core cooling system can be connected as follows. That is, one end of the purification pipe 101 is connected to the portion of the drain pipe 20 located between the two drain valves 21, and the other end is the reactor coolant of the reactor coolant purification system suction pipe 31. It is connected to a portion located between the purification system pump 32 and the reactor coolant recirculation system pipe 6.

  A stop valve 102 is provided near the drain pipe 20 of the purification pipe 101, and a stop valve 103 is provided near the reactor coolant purification system suction pipe 31 of the purification pipe 101. These stop valves 102 and 103 are opened during the periodic inspection of the nuclear power plant, and are closed at other times.

During the periodic inspection, if the stop valves 102 and 103 on the purification pipe 101 are opened while the maintenance stop valve 15, the pressure equalizing valve 19, and the drain valve 21 near the pressure equalizing valve 19 are opened, the reactor cooling Water in the emergency core cooling system injection pipe 12 between the injection check valve 14 and the reactor pressure vessel 1 is transported from the pressure equalizing pipe 18 through the drain pipe 20 with the corrosion product. Then, it is sucked into the purification pipe 101. Further, the water sucked into the purification pipe 101 enters the reactor coolant purification system suction pipe 31 and is purified by removing the corrosion products by the reactor coolant purification system purification equipment 33. It is supplied into the reactor pressure vessel 1 via the water supply system pipe 34.

As the water in the emergency core cooling system injection pipe 12 is sucked into the purification pipe 101 side by the reactor coolant purification system pump 32, the cooling water in the reactor pressure vessel 1 becomes the emergency core cooling system. The same purification action is again performed with the corrosion products entering the injection pipe 12 and remaining in the emergency core cooling system injection pipe 12. By repeatedly performing such purification action, the inside of the emergency core cooling system injection pipe 12 between the check valve and the reactor pressure vessel 1 is cleaned.

  When water is filled in the reactor pressure vessel 1 or the reactor well, the cleaning valve 42, the injection isolation valve 13 and the maintenance stop valve 15 are opened. In this state, water can be supplied from the condensate makeup water system into the reactor pressure vessel 1 and the reactor well through the emergency core cooling system injection pipe 12. When the water is supplied into the reactor pressure vessel 1 or into the reactor well, the emergency core cooling system injection pipe 12 is purified for each periodic inspection, so the transparency of water such as corrosive organisms deteriorates. Therefore, the periodic inspection work can be performed at an early stage without accompanying the factor to the reactor pressure vessel 1 or the reactor well.

  In the nuclear power plant having the above-described configuration, the emergency core cooling system is in a standby state during the normal operation of the reactor, the emergency core cooling system pump 11 is in a stopped state, and The injection / isolation valve 13 to the furnace pressure vessel 1 is also fully closed.

  However, in order to confirm that the function of the emergency core cooling system pump 11 is healthy, the emergency core cooling system pump 11 is started once a month. At this time as well, the injection isolation valve 13 to the reactor pressure vessel 1 remains fully closed, but the test valve 16 is open. In such a state, the suppression pool water 4 is sucked from the suppression pool 3 by the emergency core cooling system pump 11, and the suppression pool water 4 sucked through the test valve 16 and the test line 17 is returned to the suppression pool 3. The soundness of the emergency core cooling system pump 11 is confirmed by performing a pump test operation.

  In addition, regarding the function of the injection isolation valve 13 to the reactor pressure vessel 1 being sound, an opening operation test of the injection isolation valve 13 is conducted once a month separately from the pump test operation described above. Yes. At this time, the injection check valve 14 functions on the downstream side of the injection isolation valve 13 so that the high-pressure water in the reactor pressure vessel 1 does not flow back to the system side.

Thus, in the test of the components of the emergency core cooling system, the emergency core cooling system injection pipe 12 (reactor containment vessel) installed between the injection isolation valve 13 of the emergency core cooling system and the reactor pressure vessel The fluid inside is always stagnant for about one year during normal operation of the reactor.

  During periodic inspections of nuclear power plants, when performing an open check of the injection check valve 14 or the pressure equalizing valve 19 installed on the emergency core cooling system injection pipe 12 in the reactor containment vessel 2, Water in the reactor core cooling system injection pipe 12 is drained to a treatment facility such as a drain system and a waste treatment system using a drain pipe 20. Here, when draining using the drain pipe 20, water is drained while paying attention to the opening of the drain valve 21 so that water does not scatter from the drain receiving port which is an open end. Among the corrosion products such as rust generated in the emergency core cooling system injection pipe 12 which is a material, fine particles that change the color of water to reddish brown can be drained by draining.

  However, an area where stagnant water is generated in the emergency core cooling system injection pipe 12 which is a carbon steel pipe, that is, an emergency installed between the injection isolation valve 13 of the emergency core cooling system and the reactor pressure vessel. In the core cooling system injection pipe 12, not only the accumulated amount of corrosion products increases, but also the accumulated corrosion products aggregate. In particular, in an environment where carbon steel pipes remain stagnant for a long time, there is a constant supply of oxygen, and in the region where the corrosion product crystal growth occurs and is maintained at a moderate temperature of about 100 ° C. or less, the corrosion product It is believed that aggregation has the potential to accelerate.

  Here, the injection pipe of the emergency core cooling system rises in the reactor containment vessel 2 and is connected to the reactor pressure vessel 1 as shown in the detailed view of part A of FIG. For this reason, the high-temperature water up to about 280 ° C. in the reactor pressure vessel 1 has the same conditions up to the connecting portion horizontal piping region, but although there is a heat transfer effect from the upper portion of the rising piping portion to the lower side, the temperature gradually increases. In the vicinity of the horizontal pipe where the injection check valve 14 is installed, the temperature drops to about 80 ° C., which is the ambient temperature in the reactor containment vessel 2.

  Further, oxygen is generated in the cooling water while the nuclear reactor is in operation by the decomposition reaction of the cooling water by the radiation in the reactor pressure vessel 1. Therefore, it can be said that there is sufficient oxygen supply in the emergency core cooling system injection pipe 12 between the reactor pressure vessel 1 and the injection check valve 14. Note that the route of the emergency core cooling system injection pipe having the rising shape is unavoidable due to the structure of the reactor containment vessel 2 having a wide lower portion and a narrow upper portion.

  Therefore, as an effective means for preventing the formation of agglomerated corrosive organisms, the cooling water is prevented from being kept stagnant for a long period. Alternatively, the agglomerated corrosion products are removed before the reactor pressure vessel 1 and the reactor well are filled.

  Although there is an effect of preventing formation of agglomerated corrosion products even if water is replaced by draining water filling by opening inspection of the injection check valve 14 or the pressure equalizing valve 19, the inspection of opening of the injection check valve and the like is periodically inspected. There is also an emergency core cooling system that always remains stagnant even during periodic inspections, since it is not always necessary to carry out all of them, and once aggregated corrosion products are formed, they cannot be removed by draining with the drain pipe 20 .

  Therefore, regardless of the opening check of the injection check valve 14 and the like of the emergency core cooling system, it is possible to purify the stagnant water in the emergency core cooling system injection pipe 12 at the time of each periodic inspection. This is the most effective means for preventing the formation.

  In the embodiment of the present invention, the water in the emergency core cooling system injection pipe 12 in which the cooling water may be maintained stagnant for a long period of time can be easily and effectively made at the regular inspection as follows. Purify.

  The injection check valve 14 installed in the emergency core cooling system injection pipe 12 in the reactor containment vessel 2 in which the cooling water is always stagnated has a check valve function by opening / closing operation during the normal operation of the reactor. A pressure equalizing valve 19 for equalizing the pressure before and after the injection check valve 14 is installed so that it can be confirmed that the pressure is maintained. Further, since the pressure equalizing valve 19 is often installed at the lowest part of the emergency core cooling system injection pipe 12 in the reactor containment vessel 2, a drain for draining water is added to the pressure equalizing pipe 18 of the pressure equalizing valve 19. A pipe 20 and a drain valve 21 are installed.

  The purification pipe 101 and the stop valves 102 and 103 connected to the drain pipe 20 can be installed in all of the five series including the three series of low-pressure water injection systems 7, the low-pressure core spray system 8, and the high-pressure core spray system 9. desirable.

  When purifying the emergency core cooling system injection pipe 12 at the portion installed in the reactor containment vessel 2, the emergency core cooling system injection pipe 12 side (upper side) of the upper and lower drain valves 21 is provided. The first drain valve 21 and the stop valves 102 and 103 provided in the purification pipe 101 are opened, so that the water in each emergency core cooling system injection pipe 12 can be obtained by the reactor coolant purification system pump 32. Is also sucked in parallel with the water in the reactor pressure vessel 1, purified by the reactor coolant purification system purification equipment 33, and then returned again to the reactor pressure vessel 1 through the reactor water supply system piping 34. Repeat the cycle.

  In this way, the stagnant water in the emergency core cooling system injection pipe 12 between the injection isolation valve 13 and the reactor pressure vessel 1 where the cooling water of the emergency core cooling system is always stagnating is purified. After the purification, the cleaning pipe 41 from the condensate makeup water system connected to the upstream side of the injection isolation valve 13 of the emergency core cooling system is used for the reactor pressure vessel 1 and the reactor well. It is possible to prevent the adverse effect on the water quality of the stretched water as well as shortening the filling time.

  Next, another embodiment will be described with reference to FIG. That is, a drain pipe 20 is connected to the pressure equalizing pipe 18 of the injection check valve 14, and a double drain valve 21 is provided on the drain pipe 20, and a purification pipe is connected from the drain pipe 20 between the drain valves 21. Dividing 101 and connecting to the reactor coolant purification system suction pipe 31 is the same as in the previous embodiment, except that the intermediate portion of the purification pipe 101 is replaced with a temporary hose 106. ing.

  A stop valve 102 is installed in the purification pipe 101 on the drain pipe 20 side, and a stop valve 103 is installed in the purification pipe 101 on the reactor coolant purification system suction pipe 31 side. One-touch couplers 104 and 105 are provided at the connection port of the temporary hose 106 to the purification pipe 101. A temporary hose 106 can be detachably connected to the one-touch couplers 104 and 105.

  The temporary hose 106 is removed from the one-touch couplers 104 and 105 and stored in a storage place during the operation of the nuclear reactor. Other configurations are the same as those of the previous embodiment.

  The temporary hose 106 is connected between the one-touch couplers 104 and 105 during periodic inspection of the nuclear power plant, and the drain valve 21 and the stop valves 102 and 103 are opened. The water in the system injection pipe 12 and the water in the reactor pressure vessel 1 are sucked through the temporary hose 106 and purified by the reactor coolant purification system purification equipment 33, and the purified water is supplied to the reactor water supply system. It returns to the reactor pressure vessel 1 again via the pipe 34.

  Thus, the merit of connecting with the one-touch couplers 104 and 105 and the temporary hose 106 is that the inside of the reactor containment vessel 2 is narrow, and if it is connected with the main pipe as shown in FIG. There are also concerns that the installation of all three lines of the three series of low-pressure water injection systems 7 and the low-pressure core spray system 8 and the high-pressure core spray system 9 may affect the passage in the reactor containment vessel 2 and the equipment maintenance space. Therefore, after selecting a system that does not perform open inspection of the injection check valve of the emergency core cooling system during the periodic inspection, a period when there is no problem in maintenance and inspection work in the reactor containment vessel 2 (for example, at night Only), the temporary hose 106 is connected to perform purification, and the emergency passage without affecting the current passage in the reactor containment vessel 2 and the equipment maintenance space. In which it can purify the stagnant water of the cooling system injection pipe 12.

  As described above, according to the embodiment of the present invention, between the emergency core cooling system injection isolation valve and the reactor pressure vessel, which may be constantly stagnated for several years during the normal operation of the reactor and the periodical inspection. It is possible to purify the stagnant water in the emergency core cooling meter injection pipe and purify the injection pipe. Therefore, it is possible to suppress deterioration of water quality when water is filled in the reactor pressure vessel or the reactor well from the condensate replenishment water system via the injection pipe to shorten the time for water filling.

  In another embodiment, in consideration of securing the space in the reactor containment vessel, the emergency core cooling system injection pipe can be purified by using a temporary hose only when necessary.

  The present invention is applied to a nuclear power plant.

1 is an emergency core cooling system and a related system diagram in a nuclear power plant according to an embodiment of the present invention. It is an emergency core cooling system in the nuclear power plant by the other Example of this invention, and its related systematic diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Reactor containment vessel, 3 ... Suppression pool, 4 ... Suppression pool water, 5 ... Reactor coolant recirculation pump, 6 ... Reactor coolant recirculation system piping, 7 ... Low pressure Water injection system, 8 ... Low pressure core spray system, 9 ... High pressure core spray system, 11 ... Emergency core cooling system pump, 12 ... Emergency core cooling system injection piping, 13 ... Injection isolation valve, 14 ... Injection check valve, 15 Stop valve for maintenance, 16 ... Test valve, 17 ... Test line, 18 ... Pressure equalizing pipe, 19 ... Pressure equalizing valve, 20 ... Drain pipe, 21 ... Drain valve, 31 ... Reactor coolant purification system suction pipe, 32 ... Reactor coolant purification system pump, 33 ... Reactor coolant purification system purification equipment, 34 ... Reactor water supply system piping, 41 ... Emergency core cooling system cleaning piping, 42 ... Cleaning valve, 101 ... Purification piping,
102, 103 ... Stop valve, 104, 105 ... One-touch coupler, 106 ... Temporary hose.

Claims (5)

An emergency core cooling system for injecting water into the reactor pressure vessel with an injection pipe equipped with an injection isolation valve;
A purification device for purifying cooling water in the reactor pressure vessel;
A reactor coolant purification system for supplying the coolant purified by the purification device to the reactor pressure vessel; a portion downstream of the injection isolation valve of the injection pipe; and the reactor coolant purification system A boiling water nuclear power plant including a pipe that communicates with a portion upstream of the purification device.   The boiling water nuclear power plant according to claim 1, wherein the pipe includes a valve that controls a flow rate of cooling water flowing through the pipe.   The suction pipe according to claim 1, wherein the pipe includes a valve that controls a flow rate in the pipe, and at least a middle portion of the pipe supplies the cooling water to the injection pipe and the purification device. A boiling water nuclear power plant that consists of a temporary hose that is detachable from the side.   The boiling water nuclear power generation according to any one of claims 1 to 3, wherein the pipe line is connected to a pressure equalizing pipe of a pressure equalizing valve provided in a check valve of the emergency core cooling system. plant. Water in the injection pipe downstream of the injection isolation valve of the emergency core cooling system of the boiling water nuclear power plant is purified by sucking into the reactor coolant purification system of the boiling water nuclear power plant, The water after purification is returned to the reactor pressure vessel of the boiling water nuclear power plant, and the water in the reactor pressure vessel flows into the injection pipe downstream of the injection isolation valve. Pipe purification method for a nuclear power plant.

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