JP2011099801A - Reactor well cover and reactor inspection method - Google Patents

Abstract

An object of the present invention is to provide a reactor well cover capable of greatly reducing the number of work steps for draining and filling water, shortening the work period, and simplifying the work contents, and a reactor inspection using the same. Provide a method.
A reactor well cover including a plurality of partition walls 202, the ends of which are supported by an operating floor 230 above the reactor well 102 and seal a gap with the operating floor. It has a seal part 202a, a gate seal part 202b that seals the gap between the DSP gate 170 and the SFP gate 172, and a plate seal part 202c that seals the gap between the partition walls, and substantially seals the reactor well. It is characterized by that.
[Selection] Figure 4

Description

  The present invention relates to a reactor well cover that prevents a radiation exposure by shielding a reactor well when the reactor is shut down during a periodic inspection or the like, and a reactor inspection method using the same.

  In a boiling water reactor (BWR) and an improved boiling water reactor (ABWR), the core is accommodated in a reactor pressure vessel, and the reactor pressure vessel is accommodated in a reactor containment vessel. Cooling water (light water) is poured into the reactor pressure vessel, and high-temperature and high-pressure steam is generated by the heat generated from the reactor core, which is used as power for rotating the turbine.

  Such nuclear power plants regularly inspect piping, pumps, various valves and the like for safe operation. Among the equipment to be inspected are piping connected to the reactor pressure vessel (or reactor well) and a submergence valve. The submergence valve is the first valve on the pipe connected to the reactor pressure vessel, and cannot be inspected unless water is drained from the reactor pressure vessel. These pipes and submersion valves are inspected either by draining all the water in the reactor pressure vessel or by stopping the inlets of the pipes to be inspected (sparger nozzles, etc.) with nozzle plugs (closing plugs). It was.

  In the conventional method of draining all the water in the reactor pressure vessel, the reactor well is drained and the reactor pressure vessel is drained separately in order to prevent scattering of radioactive materials. More specifically, in order to drain water from the reactor pressure vessel, it is necessary to first remove the fuel from the reactor pressure vessel and move it to the SFP (spent fuel pool). Therefore, the reactor well, the DSP (dryer separator pool), and the SFP are filled with water after the reactor containment vessel and the reactor pressure vessel lid are removed.

  Then, the water is drained again after the fuel is moved to the SFP. However, since radiation is irradiated from the reactor well and the reactor pressure vessel after the water is drained, it is necessary to drain the water while coping with it. is there. Here, since the radioactive contamination in the reactor well is relatively light, water is drained through the fuel pool cooling and purification system (FPC system) while decontaminating. After draining water from the reactor well, the top flange for attaching the lid of the containment vessel and the bulkhead (which forms part of the floor of the reactor well) inside the top flange are cured. .

  The water in the reactor pressure vessel is relatively severe in radioactive contamination. Also, the radiation dose inside the reactor pressure vessel is extremely high. Therefore, after draining the reactor pressure vessel, in order to shield the diffusion of contamination due to radioactive dust and extremely high radiation from the inside of the reactor pressure vessel, the reactor pressure vessel is covered and the air inside is sucked. While maintaining the negative pressure, water is drained through a reactor recirculation system (PLR system), a reactor coolant purification system (CUW system), or the like. In order to perform air suction, a canal plug (a block installed between the reactor well and SFP and DSP) is stacked on the inner periphery of the reactor well, and a reactor well cover is attached on the canal plug, An exhaust treatment device is installed on the furnace well cover. In addition, the specific setup which takes out a fuel from a reactor pressure vessel is described in patent document 1, for example.

  On the other hand, in the conventional method of stopping water with a nozzle plug, a pipe (or an inspection target) inside the reactor pressure vessel is remotely controlled by using a fuel handling machine installed on the operating floor of the reactor building. The nozzle (connection hole) of the pipe where the valve was installed was closed with a nozzle plug. And the water inside the piping was drained to a sump (reservoir) of a low conductivity waste liquid treatment system (LCW system).

JP 2002-116284 A

  Considering that thousands of workers are involved in periodic inspections of nuclear power plants and that power generation is not possible while they are stopped, it is desirable that inspections be completed efficiently. Here, since draining is a critical path for a subsequent process (a process that must be performed to go to a certain process), the time required for draining directly affects the time required for the entire periodic inspection. For this reason, there is a problem of whether it is possible to drain water as soon as possible or shorten the period of water filling.

  However, the above-described method for draining all the water in the reactor well and the reactor pressure vessel has a problem that it takes a lot of time to drain the water before the inspection (or work to fill the water after the inspection). . This is a lot of incidental work such as decontamination of the reactor well, curing of the bulkhead of the reactor containment vessel and the flange of the reactor pressure vessel, or loading of the canal plug for attaching the reactor well cover. Because it was necessary. In addition to being unable to drain a large volume due to the limitation of the capacity of the system that drains water, the pump is stopped before draining is completely terminated due to the limitation of the NPSH (Net Positive Suction Head) of the pump, The residual water was drained little by little from the drain line. For this reason, in the above-described method, it took several days to drain the water to such a level that the submersion valve of the reactor recirculation system (PLR system) can be inspected.

  On the other hand, the above-described method of stopping water with the nozzle plug has a problem that cannot be applied to a nozzle in which a baffle plate (baffle plate) is disposed most recently, a jet pump nozzle, or the like. In addition, in the case of plugging a nozzle with a sparger having a large number of openings, the plugging area becomes enormous (about 700) and the plug diameter is small (about 15mm to 45mm). There was a problem that the workability was poor and the working time was increased. In other words, since the plugging time of the plug becomes longer instead of eliminating the time for draining the reactor well and the reactor pressure vessel, it is not possible to shorten the period until the piping and submersion valve can be inspected. It was. In addition, this technique requires remote skill because it is a remote underwater operation.

  The present invention has been made in view of such a problem, and can greatly reduce the work man-hours and shorten the work period for draining and water filling, and simplify work contents. It is an object of the present invention to provide a possible reactor well cover and a reactor inspection method using the same.

  In order to solve the above problems, a typical structure of a reactor well cover according to the present invention is a reactor well cover composed of a plurality of partition walls, and the plurality of partition walls are connected to an operating floor above the reactor wells. A floor seal portion that seals the gap with the operating floor, a gate seal portion that seals the gap between the DSP gate and the SFP gate, and a plate seal portion that seals the gap between the partition walls. The reactor well is substantially sealed.

  If such a reactor well cover is used, it can be attached without a canal plug, and the entire reactor well can be almost sealed. Therefore, it is possible to remove the contaminated air by sucking air from the entire reactor well and the reactor pressure vessel, and to drain the reactor well and the reactor pressure vessel continuously in a short time. It becomes possible.

  Moreover, according to the said structure, the operation | work in a reactor well can be eliminated. That is, the reactor well decontamination work, the bulkhead curing work, the top cover mounting work, the flange curing work, and the like, which are conventionally required, become unnecessary. For this reason, the work man-hour can be greatly reduced. Further, the application range is not limited as in the above-described method of stopping water with the nozzle plug, and no skill is required.

  The floor seal portion may have an inlay structure that fits with a rib provided upright on a cradle provided on the operating floor. As a result, the reactor well cover can be reliably installed on the reactor well, and earthquake resistance can be obtained.

  The gate seal portion may include an adjuster member whose position can be adjusted in a direction of moving forward and backward from the partition wall toward the DSP gate or the SFP gate, and a packing disposed at the tip of the adjuster member. Thereby, packing can be contact | abutted from a horizontal direction with respect to DSP gate and SFP gate, and the clearance gap between these can be reliably sealed (substantially sealed).

  The plate seal portion is formed with stepped portions that are combined with each other in adjacent partition walls, and it is preferable that the plate seal portion has a packing on a horizontal surface opposed to the stepped portion. As a result, the packing is sandwiched between the stepped portions in the vertical direction, and air leakage from between the partitioning walls can be reliably suppressed by simply stacking the stepped portions and sequentially arranging the partitioning walls.

  At least the lower surface of the partition wall is preferably made of substantially flat steel. Thereby, even if the lower surface is contaminated with radioactive material, the lower surface can be easily cleaned. Further, if the lower surface is flat, it is possible to easily perform decontamination by applying a coating film peeling type decontamination agent in advance and peeling it off after the operation.

  The reactor well cover may further include a plurality of nozzles formed on the partition wall, and at least a part of the nozzles may be inclined so as to intersect with radiation emitted from the center of the reactor. Thereby, even if it is a case where a some nozzle is provided, the leakage of the radiation to the exterior can be suppressed.

  In order to solve the above-described problems, a typical configuration of a nuclear reactor inspection method according to the present invention includes a step of installing a reactor well cover that is supported on an operating floor and substantially seals a reactor well, Attaching an exhaust treatment device for sucking air to a duct connection formed in the well cover; operating the exhaust treatment device to maintain the air inside the reactor well cover at a negative pressure; and A step of draining water from the reactor pressure vessel; and a step of inspecting a pipe connected to the reactor well or the reactor pressure vessel and a submergence valve provided in the pipe.

  In such a configuration, since the reactor well cover that substantially seals the reactor well is used, water stretched on the reactor well and the reactor pressure vessel can be continuously removed. Therefore, it is possible to greatly reduce the work man-hours and shorten the work period. In addition, the component corresponding to the technical idea in the reactor well cover mentioned above, and its description are applicable also to the said reactor inspection method.

  To remove the reactor well cover, open the valve of the nozzle for sucking outside air formed in the reactor well cover while the exhaust treatment device is in operation, and remove the air inside the reactor well cover from the exhaust treatment. It is good to carry out after letting the apparatus suck. Thereby, radiation emission into the reactor building can be prevented.

  According to the present invention, a reactor well cover that can greatly reduce the number of work steps for draining and filling water and shorten the work period, and can simplify the work contents, and the same are used. A nuclear inspection method can be provided.

It is a figure explaining a nuclear reactor pool. It is a figure which illustrates the state which inserted the DSP gate and SFP gate into the nuclear reactor pool of FIG. It is a figure explaining the operating floor of a reactor building. It is a figure explaining the reactor well cover concerning this embodiment. It is each sectional drawing of FIG. It is a figure which illustrates the detail of a gate seal part. It is a figure explaining the nuclear reactor inspection method concerning this embodiment. It is a figure which illustrates the state which drained the suppression pool. It is a figure which illustrates the state which finished draining of a reactor well and a reactor pressure vessel It is a figure which illustrates the state which finished water filling of a reactor pressure vessel and a reactor well.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

[Reactor pool]
FIG. 1 is a diagram illustrating a nuclear reactor pool. In particular, FIG. 1A is a top view of the reactor pool, and FIG. 1B is a diagram illustrating the reactor pool. FIG. 2 is a diagram illustrating a state where a DSP gate and an SFP gate are inserted into the nuclear reactor pool of FIG. 1 and 2 exemplify a state in which the water after the spent fuel rods are taken out is illustrated, the upper cover of the reactor pressure vessel 108 is removed.

  As illustrated in FIGS. 1 and 2, the reactor pool includes a reactor well 102, a DSP (dryer separator pool: storage pool such as a steam separator) 104, and an SFP (spent fuel pool) 106, and a DSP gate. 170 and the SFP gate 172 are inserted so that each can be isolated. These pool gates are inserted using a reactor building overhead crane (not shown).

  The nuclear reactor well 102 shields radiation by being filled with shielding water in a fuel exchange operation or the like. The DSP 104 is also referred to as an equipment temporary storage pool, and temporarily stores in-furnace structures contaminated by radiation. The SFP 106 is a pool that stores spent fuel rods and is generally filled with water at all times.

[Circulation system]
Hereinafter, the water circulation system of the reactor pressure vessel 108 will be briefly described. The circulation system around the reactor pressure vessel 108 includes a fuel pool cooling and purification system (FPC system), a reactor recirculation system (PLR system), a residual heat removal system (RHR system), and a reactor coolant purification system (CUW). System), low-conductivity waste liquid treatment system (LCW system), and condensate makeup water system (MUWC system). Water injection into the reactor pressure vessel 108 or drainage from the reactor pressure vessel 108 is performed through nozzles of each system connected to the reactor pressure vessel 108. For example, in the case of water injection, water is sprinkled into the reactor pressure vessel 108 by a water supply sparger 160 or a sparger 162 having a number of nozzles.

  The FPC system is a system connected to the lower part of the skimmer surge tank 110 and plays a role of keeping the water in the SFP 106 at a predetermined standard. The water that has entered the skimmer surge tank 110 through the weir flows into the FPC pump 112, the FPC filter demineralizer 114, and the FPC heat exchanger 116, and then returns to the SFP 106. The FPC filter demineralizer 114 is made of an ion exchange resin or the like and removes impurities. The FPC heat exchanger 116 cools in order to remove the heat generated in the SFP 106. The FPC system is also connected to the suppression pool 124 via the RHR system. The suppression pool 124 is a storage tank for condensing the steam in the reactor containment vessel and reducing the pressure.

  The PLR system is a system for controlling the output (reaction rate) by adjusting the core flow rate, and is provided on both sides of the reactor pressure vessel 108. Specifically, PLR pumps 130a and 130b are provided in the vicinity of the annulus portion of the reactor pressure vessel 108, respectively.

  The RHR system is mainly responsible for removing the decay heat of the fuel when the reactor is shut down and maintaining the reactor water in an emergency. Although the RHR system has many functions, it is well known to those skilled in the art and will not be described. In the present embodiment, the RHR system is branched from the PLR system and is also connected to the MUWC system. The RHR system includes an RHR pump 140 and an RHR heat exchanger 142.

  The CUW system is a purification system for removing impurities in the reactor water and maintaining the water quality. It is also used to control the water level of the reactor by discharging surplus water during reactor start-up, shutdown, and regular inspection. In the present embodiment, a CUW pump 150 is provided in the middle of the PLR PLR pump 130b in front of the reactor and connected to the lower part of the reactor pressure vessel 108.

  The LCW system is a system that treats water that is clean in terms of water quality, using wastewater from various devices (pumps, piping, etc.) in the reactor building, leaked water, and wastewater from the sampling line. The water purified by the LCW system is sent to the MUWC system and used again.

  The MUWC system is a system that supplies condensate with the capacity and pressure necessary for smooth operation and maintenance of the power plant to equipment, piping, valves, etc. installed in the reactor building and incidental facilities. It is. Specifically, condensate is supplied from a condensate storage tank (CST) (not shown) to the reactor pressure vessel 108 and the SFP 106.

[Operating floor]
FIG. 3 is a diagram illustrating the operating floor 230 of the reactor building. In particular, FIG. 3A is a top view illustrating the operating floor 230, FIG. 3B is a cross-sectional view taken along the line AA in FIG. 3A, and FIG. It is -B sectional drawing. As illustrated in FIG. 3A, an operating floor 230 is provided in the upper part of the reactor well 102, and a cradle 214 is disposed around the operating floor 230.

  As illustrated in FIGS. 3B and 3C, a rib 214 a is erected on the cradle 214. A backer plate 212 is provided between the floor surface of the operating floor 230 and the cradle 214 to ensure horizontality. That is, the backer plate 212 is a plate material made of steel or the like that plays a role of adjusting the height at the time of equipment installation. The cradle 214 is provided with a fastening bolt 232 upward. Further, the cradle 214 is installed on the operating floor 230 by installation bolts 234.

[Reactor well cover]
FIG. 4 is a diagram illustrating the reactor well cover 200 according to the present embodiment. 4A illustrates the state before the reactor well cover 200 is assembled, and FIG. 4B illustrates the state after the reactor well cover 200 is assembled. FIG. 5 is a cross-sectional view of FIG.

  As illustrated in FIGS. 4A and 4B, the reactor well cover 200 includes a plurality of partition walls 202, and a gap between the partition walls 202 is sealed by a plate seal portion 202c. The partition 202 is moved, installed, and removed using a reactor building overhead crane (not shown).

  As illustrated in FIGS. 5A to 5D, the plate seal portion 202 c is formed with stepped portions that are combined with each other in the adjacent partition wall 202. And it has the packing 240 in the horizontal surface which a step part opposes. The partition 202 is assembled by inserting the other fastening hole 233 through the fastening bolt 232 provided on one side and tightening the nut from above. At this time, since the packing 240 has elasticity, the gap between the partition walls 202 is reliably sealed.

  At least the lower surface of the partition wall 202 is made of substantially flat steel. Thereby, even if the lower surface is contaminated with radioactive material, the lower surface can be easily cleaned. Further, if the lower surface is flat, it is possible to easily perform decontamination by applying a coating film peeling type decontamination agent in advance and peeling it after the operation.

  The partition wall 202 has a shielding thickness corresponding to the intensity of radiation from the reactor pressure vessel 108 in order to satisfy the function as a shielding material. Assuming that the nuclear power plant is currently in operation, the dose rate on the reactor well cover 200 is about 0.15 to 0.18 mS / h when the partition wall shielding thickness is 150 mm. Continuous work for about two and a half to four hours is possible. If the shielding thickness is 165 mm, the dose is halved and continuous work for 5 to 8 hours becomes possible.

  By assembling the plurality of partition walls 202, the reactor well cover 200 illustrated in FIG. 4B is formed from the state illustrated in FIG. A floor seal portion 202 a that seals a gap with the operating floor 230 is provided at an end of the partition wall 202 (periphery of the reactor well cover 200).

  As illustrated in FIG. 5E, the floor seal portion 202 a has an inlay structure that fits with the rib 214 a of the cradle 214. In this embodiment, the floor seal portions 202a at both ends of the partition wall 202 are fitted to the outsides of the ribs 214a on both edges of the reactor well, and the reactor well cover 200 is crowned as an inlay structure. . However, the rib 214a may be positioned outside the floor seal portion 202a. The floor seal portion 202a is nut-tightened by a fastening bolt 232 through an elastic packing 240. As a result, the peripheral edge of the reactor well 102 can be reliably sealed, and vibration resistance can be obtained.

  Normally, when the fuel rod is moved from the reactor pressure vessel 108 to the SFP 106, the water level of the shielding water is stretched almost to the position of the operating floor 230. However, since it is desired to avoid contact between the reactor well cover 200 and the contaminated shielding water, the reactor well cover is installed after the DSP gate 170 and the SFP gate 172 are installed and before the reactor well cover 200 is installed. It is preferable to lower the water level so that 200 does not come into contact with the shielding water.

  As illustrated in FIGS. 4A and 4B, a plurality of nozzles 204 are provided on the reactor well cover 200. The nozzle 204 includes a DSP gate 170, an inspection window 204a for water leakage confirmation provided in the vicinity of the SFP gate 172, a duct connection portion 204b for connecting a duct of the demister 262, which will be described later, and a drain for absorbing the moisture absorbed by the demister 262. There are a moisture discharge unit 204c, a manometer mounting unit 204d for connecting a manometer for pressure measurement, a water level meter mounting unit 204e for mounting a water level meter for measuring the water level, and an outside air suction unit 204f for sucking outside air into the reactor well cover 200. Provided. The outside air suction part 204f is provided with a valve, and outside air is sucked and blocked by opening and closing the valve.

  FIG. 5 (f) shows details of the duct connecting portion 204 b as an example of the nozzle 204. As shown in FIG. 5 (f), the duct connecting portion 204 b is inclined so as to intersect with the radiation emitted from the nuclear reactor central portion. Therefore, the radiation radiated from the reactor pressure vessel 108 can be prevented from leaking outside the reactor well cover 200 through the duct connection portion 204b. Such an inclination is provided not only in the duct connection portion 204b but also in the observation window 204a, the moisture discharge portion 204c, the manometer mounting portion 204d, and the outside air suction portion 204f.

  In the reactor well cover 200, a gate seal portion 202 b is provided at a portion that contacts the DSP gate 170 and the SFP gate 172. FIG. 6 is a diagram illustrating details of the gate seal portion 202b. In particular, FIG. 6A illustrates a state before adjustment of the adjuster member 250, and FIG. 6B is a cross-sectional view taken along the line II. Moreover, FIG.6 (c) has illustrated the state after adjustment of the adjuster member 250, and FIG.6 (d) is the JJ sectional drawing.

  As illustrated in FIGS. 6A to 6D, the gate seal portion 202b includes an adjuster member 250 and a packing 240 disposed at the tip thereof. The adjuster member 250 has bolts inserted through a plurality of elongated holes, and can be fixed by tightening nuts. Therefore, the position can be adjusted in a direction of moving back and forth from the partition wall 202 toward the DSP gate 170 or the SFP gate 172. The elongated hole is formed loosely with respect to the diameter of the bolt, and the adjuster member 250 can be slightly inclined with respect to the partition wall 202. Thereby, the position of the adjuster member 250 can be adjusted so that the packing 240 can be brought into contact with the DSP gate 170 or the SFP gate 172, and the reactor well 102 can be reliably sealed (substantially sealed).

  As described above, since the end portion of the reactor well cover 200 is supported by the operating floor 230, it can be attached without requiring a canal plug, and the entire reactor well 102 can be substantially sealed. Therefore, since radioactive contaminants can be removed by sucking air from the entire reactor well 102, it is possible to continuously drain the reactor well 102 and drain the reactor pressure vessel 108. Become.

  Therefore, the reactor well decontamination work, the bulkhead curing work, the top cover mounting work, the flange curing work, etc., which are conventionally required, are unnecessary. For this reason, the work man-hour can be greatly reduced. Further, the range of application is not limited like the method of stopping water with a nozzle plug, and skill is not required.

  For these reasons, it is possible to greatly reduce the work man-hours and shorten the work period for draining and water filling, and to simplify the work contents.

[Reactor inspection method]
Hereinafter, a reactor inspection method using the reactor well cover 200 described above (a method for inspecting piping connected to the reactor pressure vessel 108 and the submergence valve 300) will be described. FIG. 7 is a diagram for explaining the nuclear reactor inspection method according to the present embodiment. In particular, FIG. 7A is a top view of the reactor pool to which the reactor well cover 200 and the exhaust treatment apparatus 268 are attached, and FIG. 7B is an atom to which the reactor well cover 200 and the exhaust treatment apparatus 268 are attached. It is a figure explaining a furnace pool.

  First, it is assumed that the fuel rod is moved from the reactor pressure vessel 108 to the SFP 106 and the DSP gate 170 and the SFP gate 172 are inserted. At this time, the reactor well 102 and the reactor pressure vessel 108 are filled with shielding water. In this state, the reactor well cover 200 is attached to the operating floor 230. Specifically, a coating-peeling type decontamination agent is applied in advance to a flat steel lower surface, and the partition wall 202 of the reactor well cover 200 is hung on the cradle 214 by a lifting machine such as a reactor building overhead crane, Fixing with fastening bolts 232. Then, the gap between the DSP gate 170 and the SFP gate 172 is sealed by adjusting the adjuster member 250.

  Next, as illustrated in FIGS. 7A and 7B, a demister 262 that sucks air in the reactor well 102 (and the reactor pressure vessel 108), a filter 264, and the like on the reactor well cover 200. A control valve 266 and an exhaust treatment device 268 are installed.

  The air in the reactor well 102 is sucked from the duct connecting portion 204b and flows into the demister 262 through the duct. The demister 262 has a hygroscopic action and discharges the absorbed moisture from the moisture discharging unit 204c. The air that has passed through the demister 262 flows into the filter 264 and is removed. Then, the air is sucked into the exhaust treatment device 268 through the control valve 266 and discharged.

  By operating the exhaust treatment device 268, the internal air can be maintained at a negative pressure. This prevents the reactor well cover 200 from leaking air contaminated by radioactivity to the outside even if the reactor well 102 is not completely sealed (even if a slight gap remains). it can. The exhaust treatment device 268 may be operated before the draining of the suppression pool 124 described below is completed. However, before draining water from the reactor well 102 (reactor pressure vessel 108), the exhaust treatment device 268 may be temporarily operated to check whether the reactor well cover 200 is almost sealed (becomes negative pressure). .

  FIG. 8 is a diagram illustrating a state in which water has been drained into the suppression pool 124. As illustrated in FIG. 8, the water from the reactor well 102 and the annulus portion (outer periphery of the shroud) in the reactor pressure vessel 108 is drained from the PLR system to the suppression pool 124 through the RHR system. As a specific example, as shown by a solid line in FIG. 8, water may be drained into the suppression pool 124 via the RHR pump 140 and the globe valve 290 (although it passes through the RHR pump 140 as a route, the RHR pump 140 is You don't need to make it work). Further, as indicated by a dotted line in FIG. 8, water may be drained directly to the suppression pool 124 without using the RHR pump 140. Furthermore, these two paths may be used simultaneously. At this time, since it is not necessary to distinguish between the reactor well 102 and the reactor pressure vessel 108, water can be continuously drained. Either method can drain water only by the difference in water level, and does not require a power source such as a pump.

  In addition, it is good to confirm that the water level of DSP104 and SFP106 does not fall at the beginning by draining a small amount of water. Thereby, it can be confirmed that there is no water leakage from the DSP gate 170 and the SFP gate 172 to the reactor well 102.

Conventionally, the water in the reactor well 102 is drained through the high-position FPC system, and the water outside the shroud is drained through the CUW pump 150. When these pumps are used, the flow rate is limited. However, in the configuration of the present embodiment, since the pump is not operated, it is possible to drain about 1,300 m ³ per hour without being limited by NPSH. Note that the RHR pump 140 may be operated in the path indicated by the solid line in FIG. 8, but even in that case, the position difference between the reactor well 102 and the suppression pool 124 having a low position is large, so that the HRSH restriction is still imposed. Absent.

  Before draining is completed, the exhaust treatment device 268 is started to maintain the negative pressure. This is because there is a possibility that the inside of the reactor well cover 200 is contaminated with radioactivity as the conventional decontamination operation has drained water. When draining is completed, it is possible to inspect the PLR piping, the submergence valve 300, and the like that have taken the longest time in the conventional inspection.

  FIG. 9 is a diagram illustrating a state where draining of the reactor well 102 and the reactor pressure vessel 108 has been completed. As illustrated in FIG. 9, the water inside the shroud of the reactor pressure vessel 108 is drained from the CUW system to the LCW system. When this draining is completed, all the water is drained from the reactor pressure vessel 108. Thereby, inspection of all the piping and the submergence valve 300 is attained.

  As described above, in the atomic inspection method according to the present embodiment, since the reactor well cover 200 that substantially seals the reactor well 102 is used, water stretched on the reactor well 102 and the reactor pressure vessel 108 is continuously removed. Can do. In this way, the number of work steps can be greatly reduced, and water can be continuously drained at a large flow rate, so that the work period can be greatly shortened.

  FIG. 10 is a diagram exemplifying a state in which water filling of the reactor pressure vessel 108 and the reactor well 102 is completed. As illustrated in FIG. 10, after the above-described inspection work of the piping and the submergence valve 300, new fuel rods need to be loaded into the reactor pressure vessel 108, so that the reactor pressure vessel 108 and the reactor well 102 are again loaded. Water is filled. In the water filling, the water filling state is monitored by a water level gauge installed in the water level gauge mounting portion 204e, and is terminated when a predetermined water level in the reactor well 102 is reached.

  There is no work in the reactor well 102 (removal of the reactor pressure vessel lid, removal of the canal plug and the conventional reactor well cover, etc.) that has been necessary in the past even in the water filling operation. Can be reduced. Further, water can be continuously poured from the reactor pressure vessel 108 to the reactor well 102 without stopping on the way. Therefore, the work period can be greatly shortened.

  When the water filling is completed, the valve of the outside air suction unit 204f is opened while the exhaust treatment device 268 is operated, and the outside air is caused to flow into the reactor well cover 200 from the outside air suction unit 204f. Then, the suction of the exhaust treatment device 268 is continued to replace the air sealed in the reactor well cover 200 and the outside air (the sealed air is sucked into the exhaust treatment device 268). This is because the sealed air may be contaminated with radioactive material. The removal of the reactor well cover 200 is performed thereafter. The lower surface of the reactor well cover 200 can be easily decontaminated by peeling off the pre-coated coating film decontamination agent.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used as a reactor well cover that shields a reactor well and prevents radiation exposure when the reactor is shut down during periodic inspection and the like and a reactor inspection method using the same.

DESCRIPTION OF SYMBOLS 102 ... Reactor well, 104 ... DSP (dryer separator pool), 106 ... SFP (spent fuel pool), 108 ... Reactor pressure vessel, 110 ... Skimmer surge tank, 112 ... FPC pump, 114 ... FPC filter demineralizer 116 ... FPC heat exchanger, 124 ... suppression pool, 130 ... RHR heat exchanger, 130a, 130b ... PLR pump, 140 ... RHR pump, 142 ... RHR heat exchanger, 150 ... CUW pump, 160 ... feed water sparger, 162 DESCRIPTION OF SYMBOLS ... Splace bar, 170 ... DSP gate, 172 ... SFP gate, 200 ... Reactor well cover, 202 ... Partition wall, 202a ... Floor seal part, 202b ... Gate seal part, 202c ... Plate seal part, 204 ... Base (204a ... view window, 204b ... duct connection part, 04c: Moisture discharging part, 204d: Manometer mounting part, 204e ... Water level gauge mounting part, 204f ... Outside air suction part), 212 ... Backer plate, 214 ... Receptacle, 214a ... Rib, 230 ... Operating floor, 232 ... Fastening bolt, 233 ... Fastening hole, 234 ... Installation bolt, 240 ... Packing, 250 ... Adjuster member, 262 ... Demister, 264 ... Filter, 266 ... Control valve, 268 ... Exhaust treatment device, 290 ... Globe valve, 300 ... Submergence valve

Claims (8)

A reactor well cover comprising a plurality of partition walls,
The plurality of partition walls are supported at the ends by an operating floor above the reactor well;
A floor seal that seals the gap with the operating floor;
A gate seal portion for sealing a gap between the DSP gate and the SFP gate;
A plate seal portion for sealing the gap between the partition walls,
Reactor well cover characterized by substantially sealing the reactor well.   The reactor well cover according to claim 1, wherein the floor seal portion has an inlay structure that fits with a rib provided upright on a cradle provided on an operating floor.   The gate seal portion includes an adjuster member whose position can be adjusted in a direction of moving forward and backward from the partition wall toward the DSP gate or the SFP gate, and a packing disposed at a tip of the adjuster member. The reactor well cover according to claim 1.   2. The reactor well cover according to claim 1, wherein the plate seal portion is formed with stepped portions that are combined with each other in the adjacent partition walls, and has a packing on a horizontal surface opposite to the stepped portion.   The reactor well cover according to claim 1, wherein at least a lower surface of the partition wall is made of substantially flat steel. The reactor well cover further includes a plurality of nozzles formed on the partition wall,
2. The reactor well cover according to claim 1, wherein at least a part of the nozzle is inclined so as to intersect with radiation emitted from a central part of the reactor. Installing a reactor well cover that is supported by the operating floor and that substantially seals the reactor well;
Attaching an exhaust treatment device for sucking air to a duct connection formed in the reactor well cover;
Operating the exhaust treatment device and maintaining the air inside the reactor well cover at a negative pressure;
Draining water from the reactor well or reactor pressure vessel;
Inspecting piping connected to the reactor well or reactor pressure vessel, and a submergence valve provided in the piping;
A method for inspecting a nuclear reactor, comprising:   The reactor well cover is removed by opening a valve of a nozzle for sucking outside air formed in the reactor well cover while the exhaust treatment apparatus is in operation, and exhausting the air inside the reactor well cover to the exhaust. The method for inspecting a nuclear reactor according to claim 6, wherein the method is performed after the processing apparatus is aspirated.

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