JP5595682B2 - Hydraulic control unit for control rod drive hydraulic system - Google Patents

Description

The present invention relates to a hydraulic control unit of a control rod drive hydraulic system that operates a control rod drive mechanism, and more particularly to a hydraulic control unit of a control rod drive hydraulic system that has an improved structure around a valve seat of a scram valve that constitutes the hydraulic control unit. .

  A boiling water reactor is provided with a number of control rod drive mechanisms at the bottom of the reactor pressure vessel. In the control rod drive mechanism, control rod insertion / extraction and scram operation are performed by the control rod drive hydraulic system to control the operation of the reactor. The control rod drive water pressure system is mainly composed of a control rod drive water pump, a scram discharge volume, and a water pressure control unit (hereinafter referred to as HCU).

  The water pressure control unit is composed of various valves such as a scram valve and a flow path selection valve, an accumulator and a nitrogen gas container, and in particular during scrum operation, the scram inlet valve and scram outlet valve of the water pressure control unit are opened, The water pressure of the accumulator is applied to the lower part of the drive piston of the control rod drive mechanism to give a large acceleration to the control rod and to perform a scram operation.

A conventional water pressure control unit (HCU) is provided in an HCU chamber as shown in Patent Document 1, and has a unit structure in which an N ₂ gas container, an accumulator, and a scram valve are accommodated in a unit frame.

  The scram valve is composed of a scram inlet valve and a scram outlet valve. The scram valve is a composite valve that is integrated by incorporating a valve seat mechanism in a valve box (upper valve box and lower valve box) of a scram inlet valve and a scram outlet valve, as shown in Patent Document 2. The upper valve box and the lower valve box of the scram valve are integrated by fastening four corners with stud bolts. A valve body and a valve seat are accommodated in the upper valve box and the lower valve box, and the scram valve is held openably and closably.

  In the scram valve, particularly in the case of scram operation, the scram inlet valve and the scram outlet valve of the water pressure control unit are opened, and the high pressure water pressure in the accumulator is applied to the lower part of the drive piston of the CRD. The coolant on the upper side of the drive piston escapes from the scram outlet valve to the scram discharge volume, gives a large acceleration to the control rod, and inserts the control rod urgently for scram operation.

  Further, the scram valve of the water pressure control unit shown in FIG. 9 is used. In this scram valve 1, a valve seat mechanism 3 is integrally held between an upper valve box 2a and a lower valve box 2b. The valve seat mechanism 3 has a sandwich structure in which the valve seat 4 is sandwiched between a sheet receiver 5a made of SUS steel and a disc-shaped sheet presser 5b.

The valve body 6 seated on the valve seat 4 is integrally provided at the tip of a valve stem 6A that is driven up and down by a main body drive unit (not shown) of the scram valve 1. The scram valve 1 is closed when the valve body 6 is seated on the valve seat 4, and the scram valve 1 is opened when the valve body 6 is separated from the valve seat 4. Reference numerals 7a and 7b are ring-shaped gaskets.

  Further, for example, four corners of the upper valve box 2a and the lower valve box 2b of the scram valve 1 are fastened and fixed by stud bolts (not shown). The valve seat mechanism 3 is sandwiched between the upper valve box 2a and the lower valve box 2b, and is installed integrally.

JP 2002-181980 A Japanese Patent Laid-Open No. 2-16494

  As shown in FIG. 9, the scram valve 1 of the water pressure control unit is configured such that the valve seat mechanism 3 has a sandwich structure, and the valve seat 4 is sandwiched between the seat receiver 5a and the disc-shaped seat presser 5b. The disk-shaped sheet presser 5b has a peripheral rib 8 protruding on the lower surface, and the peripheral rib 8 is in contact with a recess formed on the upper surface of the sheet receiver 5a by metal touch. As a result, the sheet presser 5b fits into the recess on the upper surface of the sheet receiver 5a, and the sheet presser 5b is prevented from sliding and is held stably.

  The valve seat mechanism 3 of the scram valve 1 is clamped and clamped between the upper valve box 2a and the lower valve box 2b. The valve seat 4 is fixed between the sheet receiver 5a and the sheet retainer 5b, while the sheet retainer 5b is held on the sheet receiver 5a via the peripheral rib 8 by a metal touch (metal contact).

  At that time, since the metal touch area of the sheet holder 5a and the sheet presser 5b is regulated by the small contact area of the peripheral rib 8, the contact area (pressure receiving area) of the sheet presser 5b is small and locally on the peripheral rib 8 of the sheet presser 5b. In particular, a large deformation load exceeding the elastic limit load may be applied.

  The tightening force of the upper valve box 2a and the lower valve box 2b is adjusted by tightening stud bolts and nuts, but the tightening state of the four stud bolts provided at the corners is adjusted in a well-balanced manner. Is difficult. Depending on the tightening force and tightening state of each stud bolt, the tightening state becomes unbalanced, making it difficult to adjust during tightening, and the peripheral rib 8 of the sheet presser 5b can be accommodated by deformation of the elastic deformation region. In other words, plastic deformation may occur locally, compressing the valve seat 4 excessively and hindering the seat function.

  The structure around the valve seat of the scram valve 1 is easily influenced by the tightening force and tightening procedure when the scram valve upper valve box 2a and the lower valve box 2b are tightened, and the tightening state is well balanced when the scrum valve 1 is assembled. It is difficult to make an overall adjustment, and due to the difficulty in balancing the tightening force, a great amount of work time is required for maintenance and maintenance work.

The present invention was made in consideration of the above-described circumstances, improves the workability of disassembling and assembling the scram valve, and prevents the constituent members of the valve seat mechanism from plastically deforming in advance and reliably. An object of the present invention is to provide a water pressure control unit of a control rod drive water pressure system that can cope with deformation in an elastic deformation region.

Another object of the present invention is to prevent a deformation load exceeding the elastic deformation region from acting on the valve seat mechanism of the scram valve in advance and surely, making the scram valve maintenance and maintenance work easy and improving workability. And providing a hydraulic control unit for a control rod drive hydraulic system with improved reliability.

Another object of the present invention is to provide a hydraulic control unit for a control rod drive hydraulic system that simplifies the disassembly / assembly work and facilitates maintenance / maintenance work without changing the overall shape of the scram valve and the external form of the external dimensions. To provide.

In order to solve the above-described problems, a water pressure control unit of a control rod driving water pressure system according to the present invention is connected to a nitrogen gas container for storing high-pressure nitrogen gas and the nitrogen gas container as described in claim 1. In a hydraulic control unit of a control rod drive hydraulic system comprising an accumulator that supplies high pressure water to the control rod drive mechanism, a scram valve that opens the high pressure water in the accumulator upon emergency insertion of the control rod, and a pipe connecting them The scram valve includes a two-divided structure valve box in which an upper valve box and a lower valve box are integrally coupled, and a valve seat mechanism that is housed and held in the valve box. , stacked in a sandwich structure constituted by sandwiching a valve seat between the seat receiving the sheet retainer, integral with said sheet hold-down or sheet receiving, or the sheet hold-down or sheet receiving Integrally attach seen, the peripheral sleeve is provided, the upper and lower surfaces of the peripheral sleeve is contacted with metal touch the lower surface and the upper surface of the lower valve body of the upper valve body, is characterized in that is sandwiched .

The hydraulic control unit of the control rod drive hydraulic system according to the present invention has good workability in disassembling and assembling the scram valve, and prevents plastic deformation of the valve seat structure in the valve box in advance and reliably. Maintenance work can be performed easily and efficiently, and the compression force of the valve seat is determined by the dimensional difference between the seat retainer and the seat holder due to the tightening force of the outer sleeve, resulting in excessive compression of the valve seat. Rather, the function of the valve seat mechanism can be maintained with high reliability.

The unit structure figure which shows the water pressure control unit with which the control rod drive hydraulic system which operates a control rod drive mechanism is equipped. The system diagram which shows the water pressure control unit at the time of control rod insertion. The system diagram which shows the water pressure control unit at the time of control rod extraction. The system diagram which shows the water pressure control unit at the time of a control-rod scram. The longitudinal cross-sectional view which shows embodiment of the scram valve of the hydraulic-pressure control unit which concerns on this invention. The fragmentary sectional view which shows the valve seat periphery structure of the scram valve of the water pressure control unit shown in FIG. The fragmentary sectional view which shows 2nd Embodiment of the valve seat periphery structure of a scram valve. The fragmentary sectional view which shows 3rd Embodiment of the valve seat periphery structure of a scram valve. The fragmentary sectional view which shows the valve seat periphery structure of the conventional scram valve.

An embodiment of a hydraulic control unit of a control rod drive hydraulic system according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a water pressure control unit (hereinafter referred to as HCU) 10 provided in a control rod drive hydraulic system for operating a control rod drive mechanism (hereinafter referred to as CRD). The HCU 10 is installed corresponding to the CRD in an HCU room (not shown) in the reactor building of the boiling water nuclear power plant. The HCU 10 includes a nitrogen gas container 12 that stores high-pressure nitrogen gas (N2 gas) in the unit frame 11, an accumulator 13 that is connected to the nitrogen gas container 12 and supplies high-pressure water to the CRD 27 (see FIGS. 2 to 4), The main unit constituting member is configured by incorporating the scram valve 14 for releasing the high-pressure water in the accumulator 13 at the time of emergency insertion of the control rod 28 (during scram). The scrum valve 14 is configured by combining a scram inlet valve 15 that applies high-pressure water in the accumulator to the lower part of the CRD drive piston and a scram outlet valve 16 that releases the coolant in the upper part of the drive piston to the scram discharge volume during scram. .

  The HCU 10 constitutes a main component of the control rod drive hydraulic system 18 shown in FIGS. The control rod drive hydraulic system 18 includes a control rod drive water pump 19 and a scram discharge volume 20 in addition to the HCU 10. The scrum discharge volume 20 is provided with a scrum discharge container 21, and the scram discharge container 21 is discharged with scram drainage during scrum.

  In addition to the scram valve 14, the HCU 10 includes a flow path selection valve 22 having four directional control valves 22a, 22b, 22c, and 22d, and a plurality of gate valves that partition the HCU 10 from the control rod drive hydraulic system 18. 23 and various valves such as a check valve 24. Reference numeral 25 denotes a filter that removes dust, foreign matter, and the like.

  Further, the control rod drive water pressure system 18 discharges the coolant (water) on the upper side of the drive piston 27a and the insertion pipe 29 for supplying the drive water from the control rod drive water pump 19 to the lower side of the drive piston 27a of the CRD 27. There are various pipes such as a drawing pipe 31 for drawing out to the water header 30, an accumulator filling pipe 32 for filling the accumulator 13 with cooling water, and a scram discharge pipe 33 branched from the HCU 10 and for discharging scram water to the scram discharge volume 20.

[First Embodiment]
The scrum valve 14 provided in the HCU 10 has a longitudinal sectional structure shown in FIG. The scram valve 14 includes a scram inlet valve 15 and a scram outlet valve 16. The inlet valve 15 and the outlet valve 16 are similar in configuration, so only one scram inlet valve 15 will be described.

  The scram valve 14 (15) includes a main body drive unit 37 on the upper portion of the case main body 36. The main body drive unit 37 has a diaphragm mechanism 39 that is pressed against the urging force of the spring 38 by applying air pressure. The diaphragm mechanism 39 is provided with a connecting rod 41 guided by the guide sleeve 40 in the case body 36, and a valve stem 45 is integrally connected to a lower end of the connecting rod 41 via a connector 44.

  A valve box (valve case) 46 for the scram valve 14 is provided at the lower end of the case body 36. The valve box 46 is composed of an upper valve box 47 and a lower valve box 48 in a two-part structure. The upper valve box 47 and the lower valve box 48 are integrally formed with a valve box 46 by tightening corners, for example, four corners, with stud bolts 56 with nuts penetrating in the vertical direction. The valve stem 45 of the upper valve box 47 extends downward through a gland packing 50 that slidably seals, and a valve body 51 is integrally provided at the lower end of the valve stem 45.

When the valve body 51 is seated on the valve seat 53 of the valve seat mechanism 52, the scram valve 14 is closed, and when the valve body 51 moves up and away from the valve seat 53, the scram valve 14 is opened.

  The valve seat mechanism 52 is integrally assembled with the valve seat 53 sandwiched between the seat receiver 54 and the seat presser 55. The valve seat mechanism 52 is housed in a mating housing portion formed by an inner circumferential recess on the lower surface of the upper valve box 47 and an inner circumferential recess on the upper surface of the lower valve box 48. In the upper valve box 47 and the lower valve box 48, the valve seat mechanism 52 is fastened by passing stud bolts 56 at four corners and fastening the upper and lower ends of the stud bolts 56 with the fastening nuts 57.

  A valve chamber 58 is formed in the upper valve box 47 of the valve box 46, and the scram flow path 59 extends from the valve chamber 58 above the valve seat mechanism 52 in a substantially orthogonal direction. The flow path is closed by a valve (not shown). The scram channel 59 communicates with the insertion pipe 29 of the CRD 27 and constitutes a part of the insertion pipe 29.

  In addition, a flow path 60 that leads from the inlet of the valve seat mechanism 52 to the accumulator 13 is formed in the lower valve box 48 of the valve box 46, and the high-pressure water of the accumulator 12 is supplied to the scram valve 14 through the flow path 60. It is acting.

Further, a piston 62 is supported in the accumulator 13 so as to be movable up and down, and the high pressure N ₂ gas in the N ₂ gas container 12 is caused to act on the piston 62. The pressure in the N ₂ gas container 12 is constantly measured by a pressure gauge 63 shown in FIG.

  By the way, the valve seat mechanism 52 of the scram valve 14 (15) constitutes a valve seat peripheral structure together with the upper valve box 47 and the lower valve box 48. The structure around the valve seat of the scram valve 14 has a cross-sectional structure shown in FIG. The valve seat mechanism 52 of the scram valve 14 has a valve seat 53 interposed between a seat retainer 55 with a skirt or sleeve and a block-shaped seat receiver 54, and is sandwiched. The seat receiver 54 is inserted so as to fit the outer sleeve of the seat retainer 55, and the outer peripheral top surface of the seat retainer 55, that is, the upper surface of the outer sleeve and the lower surface of the outer sleeve are the inner peripheral side of the lower surface of the upper valve box 47. The recess and the inner peripheral recess on the upper surface of the lower valve box 48 are contacted by metal touch (metal contact), and the upper and lower surfaces of the outer periphery of the sheet presser 55 are in contact with the upper valve box 47 and the lower valve box 48 by metal touch, respectively. Pinched. The outer sleeve has a wide contact area with the upper valve box 47 and the lower valve box 48, and the pressure receiving area can be increased as compared with the conventional valve seat mechanism.

  In addition, the seat retainer 55 and the seat receiver 54 of the valve seat mechanism 52 are made of heat-resistant stainless steel nuclear power generation standard GXM-1 or GXM-2 austenitic SUS steel, and have a greater pressure load than conventional SUS steel. The valve seat 53 is made of, for example, a fluororesin material containing carbon fiber or glass fiber, such as PTFE (polytetrafluoroethylene) or ETFE (tetrafluoroethylene / ethylene copolymer). The PTFE used for the valve seat 53 can change the sheet form on the side to relieve the tightening stress, and can disperse the pressure receiving stress and make it uniform.

  Further, tightening is performed by the outer peripheral sleeve of the seat retainer 55, and the compression allowance of the valve seat 53 is defined by the dimensional difference between the seat retainer 55 and the seat retainer 54, and the valve seat 53 is not excessively compressed.

  In FIG. 6, reference numeral 65 is a ring-shaped gasket for preventing leak flow, reference numeral 66 is a guide groove for guiding the leak flow, reference numeral 67 in FIG. 5 is a packing presser for the laminated gland packing, and reference numeral 68 is a stopper. It is.

[When inserting control rod]
When the control rod drive mechanism (CRD) 27 is operated to insert the control rod 28 into the reactor core, the control rod drive hydraulic system 18 is shown in FIG. To work. On the other hand, the opening / closing relationship of the various valves of the HCU 10 is controlled as shown in FIG. 2, and the direction control valves 22a and 22c of the flow path selection valve 22 are closed and the other direction control valves 22b and 22d are opened. The scram inlet valve 15 and the scram outlet valve 16 constituting the scram valve 14 are both closed, and the gate valve 23 of the HCU 10 is opened. The direction control valves 22a and 22d of the flow path selection valve 22 are provided with a flow rate adjustment valve.

  When the control rod drive water pump 19 is driven and the various valves of the HCU 10 are in the open / closed state shown in FIG. 2, the drive water from the condenser and the condensate reservoir (both not shown) It passes through the flow path in the valve 22 and is supplied from the insertion pipe 29 to the lower side of the drive piston 27a of the CRD 27. The control rod 28 is pushed up and inserted into the reactor core.

  On the other hand, the coolant (cooling water) on the upper side of the drive piston 27 a of the CRD 27 passes through the flow path in the flow path selection valve 22 from the drawing pipe 31 and is discharged to the discharged water header 30 through the drain pipe 71.

  As a result, the drive piston 27a of the CRD 27 moves upward, and the control rod 28 coupled to the upper end of the piston operating rod is inserted into the reactor core, and is controlled in a direction to reduce the output of the reactor.

[When pulling out the control rod]
When the control rod 28 is pulled out from the reactor core, the flow path selection valve 22 of the water pressure control unit (HCU) 10 is controlled to open and close as shown in FIG. The direction control valves 22b and 22d of the flow path selection valve 22 are closed, and the other direction control valves 22a and 22c are opened. When the flow paths are switched while the various valves of the HCU 10 are opened and closed, the insertion pipe 29 in FIG. 2 is shifted to the drain side from the CRD 27 and the extraction pipe 31 is shifted to the supply side of the CRD 27.

  When the control rod drive water pump 19 is driven and the various valves of the HCU 10 are opened and closed as shown in FIG. 3, the drive water passes through the flow path in the flow path selection valve 22 from the drawing pipe 31 and the drive piston of the CRD 27. It is supplied to the upper side of 27a and pushes down the drive piston 27a.

  On the other hand, the coolant (water) below the drive piston 27 a passes through the flow path in the flow path selection valve 22 from the insertion pipe 29 and is discharged from the drain pipe 71 to the drain water header 30.

  By supplying and discharging cooling water above and below the drive piston 27a of the CRD 27, the drive piston 27a is lowered, and with this drop, the control rod 28 is pulled out from the reactor core so that the output of the reactor is improved. I have control.

[When scrum]
When the control rod 28 of the CRD 27 is scrammed, the various valves of the HCU are controlled to open and close as shown in FIG. During this scrum operation, the inlet valve 15 and the outlet valve 16 of the scrum valve 14 are opened.

  During this scrum, the supply of pressurized air to the diaphragm mechanism 39 shown in FIG. 5 is stopped. Then, the diaphragm of the diaphragm mechanism 39 is moved upward by the spring force (biasing force) of the spring 38 to move the connecting rod 41 upward. Following the upward movement of the connecting rod 41, the connector 44 and the valve stem 45 are moved upward, and the valve body 51 is separated from the valve seat 53 of the valve seat mechanism 52. When the valve body 51 moves up, the valve is opened, the scram valve 14 (inlet valve 15 and outlet valve 16) is opened, and the scrum operation is started.

  When the scram valve 14 is opened, the high-pressure water in the accumulator 13 enters the valve chamber 58 from the flow path 60, and then passes from the valve chamber 58 to the scram flow path 59 and the insertion pipe 29 shown in FIG. It is supplied to the lower side of the drive piston 27a. When the scram valve 14 (inlet valve 15 and outlet valve 16) of the HCU 10 is opened, high-pressure water from the accumulator 13 is applied to the lower part of the drive piston 27a of the CRD 27.

  On the other hand, the coolant above the drive piston 27 a of the CRD 27 is drawn out from the drawing pipe 31, led to the scram discharge pipe 33 through the scram outlet valve 16, and escapes to the scram discharge container 21 of the scram discharge volume 20. In the scram outlet valve 16, the coolant above the drive piston 27 a of the CRD 27 is discharged from the scram flow path 50 to the scram discharge container 21 side through the flow path 60, the valve port 53 a, and the valve chamber 58.

  As a result, a large acceleration is applied to the drive piston 27a of the CRD 27, and the control rod 28 is urgently inserted into the reactor core.

  If for some reason the outlet pressure of the accumulator 13 falls below the reactor pressure, the ball position of the ball check valve (not shown) of the CRD 27 changes, the reactor pressure is applied to the lower part of the drive piston 27a, and the scram The operation is complete.

  Further, the structure around the valve seat of the scram valve 14 (15, 16) is configured as shown in FIG. The valve box 46 has a two-part structure of an upper valve box 47 and a lower valve box 48, and is integrated by tightening and clamping the four corners of the upper valve box 47 and the lower valve box 48 with stud bolts 56 and nuts 57. The valve seat mechanism 52 is configured in a sandwich structure. Thereafter, the valve seat mechanism 52 is integrally configured as an outer sleeve (or skirt) in which the outer peripheral portion of the seat retainer 55 has a larger bearing area than the conventional peripheral rib, and the outer peripheral sleeve integrated with the seat retainer 55 is the upper surface ( The upper surface and the lower surface of the outer periphery of the sheet presser are in contact with the lower surface of the upper valve box 47 and the upper surface of the lower valve box 48 by metal touch (contact) and are sandwiched.

  Specifically, the upper and lower surfaces of the outer periphery sleeve (integrated with the seat presser 55) are in contact with the inner peripheral recesses on the lower surface of the upper valve box 47 and the inner peripheral recesses on the upper surface of the lower valve box 48 by metal touch. It is pinched. The valve seat 53 and the block-shaped sheet receiver 54 are accommodated in a laminated state in the outer peripheral sleeve of the sheet presser 55. The sheet receiver 54 is in contact with the sheet presser 55 at the outer peripheral portion, but is not in direct contact with the axial direction.

  In addition, the sheet retainer 55 and the sheet receiver 54 are formed of a heat-resistant stainless steel standard for nuclear power generation GXM-1 or GXM-2, which has a greater load resistance than conventional SUS steel. For this reason, the deformation of the sheet presser 55 that receives the tightening load is always performed within the elastic deformation region. Therefore, the valve seat mechanism 52 can surely prevent the seat retainer 55 and the seat receiver 54 from being damaged due to plastic deformation or permanent deformation.

  Even if the valve seat mechanism 52 receives a tightening load or a variation in tightening force occurs, the seat presser 55 of the valve seat mechanism 52 can cope with the deformation of the elastic deformation region, and plastic deformation does not occur. .

  Regardless of the tightening method, the valve seat mechanism 52 is not plastically deformed by receiving a load exceeding the elastic limit. Therefore, the assembly operation of the scram valve 14 including the valve seat mechanism 52 is facilitated, and the scram valve 14 (15, The maintenance / maintenance work 16) can be performed easily and easily.

  In addition, the valve seat 53 held in the sandwich structure is made of PTFE or ETFE containing carbon fiber. When the tightening load is applied, a cold flow is generated, and the stress relief side is formed. The sheet function can be sufficiently maintained.

  Further, the outer shape and dimensions of the valve seat mechanism 52 of the scram valve 14 (15, 16) are the same as the outer shape and dimensions of the conventional valve seat mechanism and can be accommodated in the conventional valve box 46. It is configured in the same external form. In addition, the valve seat mechanism 52 integrally forms an outer sleeve on the outer periphery of the seat retainer 55 that holds the valve seat 53, and a three-piece valve that houses the valve seat 53 and the seat receiver 54 in the outer sleeve of the seat retainer 55. Since the sheet sandwich storage structure is adopted, the sheet presser 55, the valve seat 53, and the sheet receiver 54 are not plastically deformed by receiving a tightening load or an impact load.

[Second Embodiment]
FIG. 7 shows a second embodiment of the water pressure control unit of the control rod drive water pressure system .

  Since the overall configuration of the water pressure control unit (HCU) is not different from that of the HCU 10 shown in FIGS. 1 to 5, the same reference numerals are used for the same configurations and operations, and description thereof is omitted or simplified.

  The scram valve 14A of the hydraulic pressure control unit (HCU) shown in the second embodiment has the same outer shape and dimensions as the scrum valve 14 shown in the first embodiment, and the valve seat 46 has a valve seat. The mechanism 52A is stored and held. The valve seat mechanism 52A is configured by assembling three pieces of a seat receiver 54A, a valve seat 53, and a seat retainer 55A. Although the valve seat mechanism 52A has a three-piece sandwich housing structure, an outer sleeve provided in the valve seat mechanism 52A is integrally formed with the seat receiver 54A.

  The valve seat mechanism 52A is provided with a cylindrical outer sleeve that rises from the periphery of the seat receiver 54A. The valve seat 53 and the valve presser 55A are stacked and stored in an outer peripheral sleeve integral with the seat receiver 54A. Sandwich storage structure. The upper surface and the lower surface of the outer peripheral sleeve of the seat receiver 54A, that is, the upper surface (top surface) and the lower surface (bottom surface) of the sheet receiver 54A are the inner peripheral recesses on the lower surface of the upper valve box 47 and the upper surface of the lower valve box 48. It is in contact with the circumferential recess by metal touch (metal contact). The upper surface of the outer sleeve and the lower surface of the outer sleeve (sheet receiving bottom surface) of the seat receiver 54A are located in the inner peripheral recess on the lower surface of the upper valve box 47 and the inner peripheral recess on the upper surface of the lower valve box 48 (partially via a ring-shaped gasket 65). ) Touch and hold with metal touch.

  The outer peripheral surfaces of the valve seat 53 and the seat presser 55A of the valve seat mechanism 52A are fitted and accommodated in the outer peripheral sleeve of the seat receiver 54A, thereby preventing radial sliding.

  Similarly to the valve seat mechanism 52 of the first embodiment, the valve seat mechanism 52A of the second embodiment also receives a tightening load in the elastic deformation region of the seat receiver 54A and undergoes plastic deformation in advance. And it can prevent reliably. For this reason, the valve seat mechanism 52A is not plastically deformed and damaged. Further, since the tightening force is received by the outer peripheral sleeve of the seat receiver 54A, the compression allowance of the valve seat 53 is defined by the dimensional difference between the seat receiver 54A and the seat presser 55A, and thus the valve seat 53 may be excessively compressed. Therefore, as with the valve seat mechanism 52 of the first embodiment, the assembling workability of the scram valve 14 including the valve seat mechanism 52A is improved, and maintenance and maintenance work can be performed easily and efficiently.

[Third Embodiment]
FIG. 8 shows a third embodiment of the water pressure control unit of the control rod drive water pressure system .

  Since the overall configuration of the water pressure control unit (HCU) is not different from the HCU 10 shown in FIGS. 1 to 5, the same reference numerals are used for the same configurations and operations, and description thereof is omitted or simplified.

  The scram valve 14B of the hydraulic pressure control unit (HCU) shown in the third embodiment has the same outer shape and dimensions as the scrum valve 14 shown in the first embodiment. In the scram valve 14B, the valve seat mechanism 52B is housed and held in the valve box 46 as in the first embodiment. The valve seat mechanism 52B includes the seat receiver 54B, the valve seat 53, the seat presser 55B, and the outer periphery. This is a four-piece sandwich housing structure configured by assembling four pieces of the sleeve 70, and is different from the valve seat mechanisms 52, 52A having a three-piece sandwich structure.

  The outer peripheral sleeve 70 of the valve seat mechanism 52B has an upper surface and a lower surface that are in contact with an inner peripheral recess on the lower surface of the upper valve box 47 and an inner peripheral recess on the upper surface of the lower valve box 48 by a metal touch (metal contact). 70, a sheet receiver 54B, a valve seat 53, and a sheet retainer 55B are stacked in a sandwich structure, and the sandwiched sheet receiver 54B, valve seat 53, and sheet retainer 55B are stored in a laminated state in the outer sleeve 70, and the sheet receiver 54B, the sliding of the valve seat 53 and the seat presser 55B in the radial direction is restricted.

  The valve seat mechanism 52B of the third embodiment also receives a tightening load with a larger bearing area (contact area) than the peripheral ribs of the conventional valve seat mechanism, and the outer sleeve 70 is made of XM-19 or heat resistant stainless steel. Nuclear power generation standard GXM-1 or GXM-2 is used.

  The valve seat mechanism 52B of the third embodiment can receive a tightening load in the elastic deformation region of the outer sleeve 70, and can surely prevent the valve seat mechanism 52B from being plastically deformed.

  Therefore, the valve seat mechanism 52B used in the third embodiment can also reliably prevent the sheet receiver 54B, the seat presser 55B, and the outer peripheral sleep 70 from being plastically deformed, and the assembling work of the scram valve 14B including the valve seat mechanism 52B. Therefore, maintenance and maintenance work can be performed easily and efficiently.

10 Water pressure control unit (HCU)
11 Unit frame (body frame)
12 nitrogen (N ₂ ) gas container 13 accumulator 14 scram valve 15 scram inlet valve 16 scram outlet valve 18 control rod drive hydraulic system 19 control rod drive water pump 20 scram discharge volume 21 scram discharge container 22 flow path selection valves 22a, 22b, 22c, 22d Directional control valve 23 Gate valve 24 Check valve 25 Filter 27 Control rod drive mechanism (CRD)
27a Drive Piston 29 Insertion Pipe 30 Drain Water Header 31 Extraction Pipe 32 Accumulator Filling Pipe 33 Scram Discharge Pipe 36 Case Body 37 Body Drive Unit 38 Spring 39 Diaphragm Mechanism 40 Guide Sleeve 41 Connecting Rod 44 Connector 45 Valve Stem 46 Valve Box 47 Upper Valve Box 48 Lower valve box 50 Gland packing 51 Valve body 52 Valve seat mechanism 53 Valve seat 53a Valve port 54 Sheet receiver 55 Sheet retainer 56 Stud bolt 57 Nut 58 Valve chamber 59 Scrum flow path 60 Flow path 62 Piston 63 Pressure gauge 65 Gasket 66 Guide groove 67 Packing presser 68 Stopper 70 Sleeve guide 71 Drain piping

Claims (8)

A nitrogen gas container for storing high-pressure nitrogen gas, an accumulator connected to the nitrogen gas container for supplying high-pressure water to the control rod drive mechanism, a scram valve for releasing the high-pressure water in the accumulator at the time of emergency insertion of the control rod, and In the water pressure control unit of the control rod drive water pressure system provided with the piping to be connected,
The scram valve has a two-divided structure valve box in which an upper valve box and a lower valve box are integrally coupled, and a valve seat mechanism that is housed and held in the valve box,
The valve seat mechanism is configured by sandwiching a valve seat between a sheet receiver and a sheet presser and laminating them in a sandwich structure,
An outer peripheral sleeve is provided integrally with the sheet presser or the sheet receiver , or integrally with the sheet presser or the sheet receiver, and the upper surface and the lower surface of the outer sleeve are provided on the lower surface of the upper valve box and the upper surface of the lower valve box. A hydraulic control unit of a control rod drive hydraulic system characterized by being brought into contact with and held by a metal touch. The valve seat mechanism is integrally provided with an outer sleeve that falls from the periphery of the seat presser, and stores the valve seat and the seat receiver in the outer sleeve,
The upper surface and the lower surface of the outer peripheral sleeve integral with the seat presser are brought into contact with and held by an inner peripheral recess on the lower surface of the upper valve box and an inner peripheral recess on the upper surface of the lower valve box. Hydraulic control unit for control rod drive hydraulic system . The valve seat mechanism is integrally provided with an outer sleeve that rises from the periphery of the seat receiver, and stores the valve seat and the seat presser in the outer sleeve,
2. The control according to claim 1, wherein the upper and lower surfaces of the outer peripheral sleeve integral with the seat receiver are brought into contact with and held by the metal valve with the lower surface of the upper valve box, the inner peripheral recess, and the inner peripheral recess of the lower valve box upper surface. Hydraulic control unit for rod drive hydraulic system . The valve seat mechanism includes an outer sleeve that stores a sheet presser, a valve seat, and a sheet receiver in a stacked state,
2. The control rod drive hydraulic system according to claim 1, wherein the upper and lower surfaces of the outer sleeve are brought into contact with and held by an inner peripheral recess on the lower surface of the valve box and an inner peripheral recess on the upper surface of the lower valve box. Water pressure control unit . The valve seat mechanism uses a sheet material of ETFE (tetrafluoroethylene and ethylene), PTFE (polytetrafluoroethylene) or PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) for the valve seat. The hydraulic control unit of the control rod drive hydraulic system according to claim 1. The hydraulic pressure control unit of the control rod drive hydraulic system according to claim 1, wherein the valve seat mechanism includes a sheet presser and a sheet receiver that are not in contact with each other in the axial direction. 2. The hydraulic pressure control unit of a control rod drive hydraulic system according to claim 1, wherein the material of the outer sleeve of the valve seat mechanism is a material having an allowable stress exceeding a bearing stress acting on the outer sleeve. The hydraulic pressure control unit for a control rod drive hydraulic system according to claim 1, wherein the material of the outer sleeve of the valve seat mechanism is XM-19 or heat resistant stainless steel nuclear standard GXM-1 or GXM-2.

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