JPH0531955B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to cooling system equipment for nuclear reactors, and in particular, to nuclear reactor cooling systems equipped with reactor shutdown cooling systems (residual heat removal systems), coolant purification systems, etc. This relates to reactor cooling system equipment.

[Conventional technology]

In addition to the reactor water supply system and recirculation system that serve as the main cooling system, the reactor cooling system equipment in a nuclear power plant includes a low-pressure water injection system that supplies suppression pool water to the reactor when coolant is lost as an auxiliary cooling system. , a containment cooling system that cools the reactor containment vessel, a reactor shutdown cooling system that removes residual heat from the reactor when the reactor is shut down, and a reactor cooling system that purifies reactor water (primary coolant) during reactor operation. The system consists of a coolant purification system that resupplies the coolant.

FIG. 3 shows an example of conventional cooling system equipment equipped with these various cooling systems, and the conventional cooling system equipment will be explained below based on the figure.

In the figure, 1 is the reactor pressure vessel, 2 is the reactor containment vessel, 3 is the suppression pool that stores the suppression pool water 4, 8 and 9 are the piping of the recirculation system line, and 15 is during reactor operation. This is piping for a reactor water supply system line L1 that supplies water to the reactor pressure vessel 1 to drive the turbine.

The low-pressure water injection system consists of a suppression pool 3 → piping 17 (pump 5 → heat exchanger 6) → reactor pressure vessel 1, and in the event of a loss of coolant accident, suppression pool water 4 is pumped into the reactor through this route. pressure vessel 1
Inject into the shroud of the

The containment vessel cooling system is the suppression pool 3→
Piping 17 (pump 5 → heat exchanger 6) → piping 16,
20, the suppression pool water 4 is sucked by the pump 5, and after being cooled by the heat exchanger 6, the pipe 1
The atomic containment vessel 2 is cooled by spraying it through the atomic bombs 6 and 20.

The reactor shutdown cooling system (residual heat removal system) runs from the reactor pressure vessel 1 to the outlet side piping 9 of the recirculation system pump 7.
→ Reactor water extraction piping 21 → Valve 22 → Piping 17 (pump 5 → Heat exchanger 6) → Piping 18 → Recirculation system pump 7
When the reactor shutdown cooling system is in operation, reactor water is taken out from the outlet pipe 9 of the recirculation system pump 7, pressurized by the pump 5, and then transferred to the reactor pressure vessel 6 by the heat exchanger 6. After cooling, it is returned to the recirculation system inlet piping 8 to form a closed loop circulation circuit,
Removes residual heat during reactor shutdown.

The coolant purification system includes the inlet side piping 8 of the recirculation system pump 7 → piping 19 → pump 11 → regenerative heat exchanger 12
Primary side → non-regenerative heat exchanger 13 → filtration desalination equipment 1
4 → Secondary side of regenerative heat exchanger 12 → Piping 24 → Water supply system piping 15 → Reactor pressure vessel 1. During reactor operation, the reactor water is purified by the filtration and demineralization device 14 in this route, and the purification system The purified reactor water from the confluence section 25 of the water supply system and the coolant purification system is sent by the pump 11 and returned to the reactor pressure vessel 1 via the water supply system piping 15.

In addition, the reactor cooling system equipment includes a suppression pool water cooling system that sucks suppression pool water 4 with a pump 5, cools it with a heat exchanger 6, and returns it to the suppression pool 3 via test piping 10. During normal operation, suppression pool water 4 is added to the reactor pressure vessel 1 and the reactor containment vessel 2.
The pump 5→test piping 10',
A test system consisting of 10 → suppression pools 3 is provided.

As described above, the reactor cooling system equipment is equipped with various cooling systems to enable smooth and safe operation of the nuclear reactor. In addition, as a conventional technology related to the reactor cooling system, there is also
No. 55-6260, in which the coolant purification system and residual heat removal system lines are shared and connected to the reactor pressure vessel, and other conventional technologies include, for example, JP-A No. 54-20293, There is one described in 1982-150395.

[Problem to be solved by the invention]

Among the system configurations having various types of cooling systems, especially in the reactor shutdown cooling system and coolant purification system that circulate reactor water from the reactor pressure vessel 1, the reactor shutdown cooling system piping 18, In order for crud generated from the coolant purification system piping 19 and the inner surface of the reactor pressure vessel to become radioactive as the plant operating time passes, these piping 18, 19, etc.
Alternatively, there is a risk that workers may be exposed to radiation during maintenance and inspection work on valves and supports installed in this type of piping, and during disassembly work on pumps, valves, etc., and it was necessary to take sufficient safety measures.

In addition, the diameter of the cooling system piping 18 during reactor shutdown is
Normally, the diameter is about 400A, the diameter of the coolant purification system piping 19 is about 200A, and the length is considerable (for example, about 50m for the cooling system piping 18 when stopped)
The pipes 8 and 9 of the recirculation system are routed all around the floor where maintenance and inspections are frequently performed. It was necessary.

Furthermore, when the reactor shutdown cooling system is in operation, the fluids in the reactor recirculation system piping 8 and the reactor shutdown cooling system piping 18 merge (portion indicated by symbol P in FIG. 3).
Since the internal fluid temperatures of the recirculation system piping and the reactor shutdown cooling system return piping are approximately 180℃ and approximately 70℃, respectively, the temperature difference between the two systems is approximately 110℃ or more, and as a result, the fluid There was a possibility that the confluence part P would suffer thermal fatigue over time and the piping would be damaged.

Furthermore, even if the coolant purification system and reactor shutdown cooling system are made common as in JP-A No. 55-6260,
In order to directly connect these common reactor water return piping to the reactor pressure vessel, this return piping must be routed through the reactor containment vessel. Maintenance and inspection safety issues and piping, piping supports, insulation materials,
There was a problem with the increase in the number of panelists.

The present invention has been made in view of the above points, and its purpose is to improve the safety of work inspections of these types of piping by rationally configuring the system configuration of cooling system piping during reactor shutdown, coolant purification system piping, etc. In addition, we aim to reduce the amount of piping used in the reactor shutdown cooling system, coolant purification system piping, piping support, etc., and also reduce thermal fatigue at the confluence of the conventional reactor shutdown cooling system piping and recirculation system piping. The object of the present invention is to provide a nuclear reactor cooling system facility that can solve the problem.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. Note that the symbols attached to the constituent elements are as follows:
For convenience, the example shown in FIG. 1 has been cited.

That is, in a reactor cooling system facility equipped with a reactor water supply system, a recirculation system, a reactor shutdown cooling system (residual heat removal system), a coolant purification system, etc., the reactor shutdown cooling system and coolant purification system are The system is
It has a common pipe 21' that takes in reactor water from part 9 of the line of the recirculation system, and the downstream side of this common pipe 21' is branched, and one of the branch pipes 17 performs heat exchange sequentially from the upstream side. 6 and pump 5 to constitute the piping of the reactor shutdown cooling system line L2, and the other branch piping 26 connects the heat exchanger 1 in order from the upstream side.
3. A pump 11, a purification device 14, etc. are provided to configure the piping of the coolant purification system line L3, and a purification device for the downstream side of the pump 5 of the cooling system line L2 during reactor shutdown and the coolant purification system line L3. 14 on the downstream side are unified by a common pipe 24' and connected to the pipe 15 of the reactor water supply system line L1, and these lines are connected to the reactor shutdown cooling system line L2 and the coolant purification system line L3. line L2,L
line selection switching valves 22, 2 for selectively connecting the reactor water supply system line L1 with the reactor water supply system line L1;
7 is provided.

[Effect]

With the above configuration, the pipe 9 of the recirculation system and the common pipe 21' connected thereto are
Reactor water is taken from the reactor pressure vessel 1 through the reactor pressure vessel 1.

When the reactor is operating, the switching valve 22 is closed.
The switching valve 27 is controlled to open and the mode of the coolant purification system is selected, and the taken coolant (reactor water) is transferred to the pipe 26 (heat exchanger 12, pump 11, purification system) that branches from the reactor water intake pipe 21'. After being cooled and purified (filtration desalination) through this pipe,
Common piping 24' and piping 15 of water supply system line L1
is returned to the reactor pressure vessel 1 via the reactor pressure vessel 1.

When the reactor is shut down, the switching valve 22 is opened and the switching valve 27 is closed to select the reactor shutdown cooling system, and water is taken in through the common pipe 21' connected to the recirculation system in the same manner as described above. After the reactor water passes through the branch pipe 17 (heat exchanger 6, pump 5) and is cooled by this pipe, it is returned to the reactor via the common pipe 24' and the pipe 15 of the water supply system line L1.

Therefore, according to the present invention, there is no need for the reactor water take-out piping 19 dedicated to the coolant purification system as shown in FIG. Since it is shared with piping 15 of the reactor water supply system, it can be used as a return piping exclusively for reactor water (corresponding to the reference numeral 18 in Figure 3) of the cooling system during reactor shutdown as in the past, or as described in JP-A-55-6260. Eliminates the need for dedicated reactor water return piping for the material purification system and reactor shutdown cooling system.

As a result, there is no need to provide a dedicated reactor water return pipe that penetrates the reactor containment vessel 2, and the return pipe (common pipe) 24' of the reactor shutdown cooling system and coolant purification system is connected to the reactor containment vessel. 2 can be connected to the reactor water supply system piping 15 outside.

Further, return water from the cooling system during shutdown can be returned to the reactor pressure vessel without having to join the recirculation system line, unlike in the conventional system.

Furthermore, according to the present invention, in the reactor shutdown cooling system, the residual heat removal system pump 5 is provided downstream of the heat exchanger 6.
, and in the coolant purification system, the pump 11 was placed downstream of the heat exchanger 13, so cooling water lowered in temperature by the heat exchanger flows through each pump.
The rate of radioactivity adhesion to the pump can be reduced (the rate of radioactivity adhesion is temperature dependent, increasing as the reactor water temperature rises; details of this are described in Examples).

〔Example〕

An embodiment of the present invention will be described based on FIGS. 1 and 2.

FIG. 1 shows a piping diagram of the cooling system equipment of this embodiment. In the figure, the same reference numerals as those of the conventional cooling system equipment of FIG. 3 described above indicate the same parts.

That is, in the figure, 1 is a reactor pressure vessel, 2 is a reactor containment vessel, 3 is a suppression pool, and 4 is suppression pool water.

5 is a pump for the residual heat removal system that operates during the operation of the low-pressure water injection system, the reactor containment vessel cooling system, and the reactor shutdown cooling system, and the pump 5 is used to pump reactor water and suppression pool water in the reactor shutdown cooling system. The heat exchanger 6 is disposed in the pipe 17 that conveys the heat exchanger to an intermediate route, and is disposed on the downstream side of the heat exchanger 6.

In the event of a loss of coolant accident, the suppression pool 3 → heat exchanger 6 → pump 5 → piping 17,
17'→Suppression pool water 4 is supplied into the shroud of the reactor pressure vessel 1 by the low pressure water injection system of the reactor pressure vessel 1.

In addition, the reactor containment cooling system consists of the suppression pool 3 → heat exchanger 6 → part of the piping 17 and piping 16, 20, and if a loss of coolant accident occurs through this route, the suppression pool water 4
is sprayed into the reactor containment vessel 2.

7 is a recirculation system pump, 8 is an inlet side piping of the recirculation system pump 7, and 9 is an outlet side piping.

A common reactor water take-out pipe 21' is connected to the outlet side pipe 9 of the recirculation system pump 7 to take out reactor water to the outside of the reactor containment vessel 2 when the reactor shutdown cooling system and coolant purification system are operated. , the downstream side of the outer isolation valve 35 of the reactor water extraction pipe 21' is branched, and on one of the branch pipes 26, the primary side of the regenerative heat exchanger 12 → non-regenerative heat exchanger 13 → filtration desalination equipment 14 → The secondary sides of the regenerative heat exchanger 12 are sequentially connected and arranged from the upstream side,
It constitutes the main piping of the coolant purification system line L2.

When compared with the conventional coolant purification system shown in FIG. The reactor water is taken out using the outlet side pipe 9 of the circulation system pump 7 and the reactor water take-out pipe 21' which is common to the reactor shutdown cooling system described later.
The difference is that the purification system pump 11 is arranged downstream of the non-regenerative heat exchanger 13.

The other branch pipe is constituted by pipe 17. One of the branch pipes 17 includes a heat exchanger 6 and a pump 5 in this order from the upstream side, and constitutes the main pipe of the reactor shutdown cooling system line L2. In addition, the downstream side of the pump 5 of the reactor shutdown cooling system line L2 and the downstream side of the purifier 14 of the coolant purification system line L3 are integrated by a common piping 24', and the piping of the reactor water supply system line L1 is integrated. It is connected to the confluence section 25 of No. 15 outside the reactor containment vessel 2.

That is, in this embodiment, since the pipe 17 also serves as the low-pressure water injection system halfway in addition to the reactor shutdown cooling system line L2, the reactor containment vessel provided between the pipe 17 and the water injection system pipe 17' The upstream side of the outer isolation valve 30 is branched to connect a communication pipe 29 having a remote control valve 28, and the other end of this communication pipe 29 is connected to the common pipe (water supply system communication pipe) 24' together with the coolant purification system pipe 26. Connected.

By adopting such a piping configuration, the reactor shutdown cooling system is constructed such that the piping on the reactor water return side is connected to the piping 18 and the recirculation system pump 7, as in the conventional example shown in FIG.
Piping 17 without going through the route of inlet side piping 8.
Reactor water is returned to the reactor pressure vessel 1 through the route of →connection piping 29, 24'→water supply system piping 15 to remove residual heat when the reactor is shut down.

The various cooling systems described above control the opening and closing of the remote control valves 35, 22, 27, 30, etc. arranged in each system, and the turning on of the residual heat removal system pump 5 and the coolant purification system pump 11. - This is performed by off control, and the operations of the coolant purification system and the stoppage cooling system, which are the main points of this embodiment, will be explained below.

During normal operation of the reactor, for coolant purification, reactor water is taken out from the recirculation system pump outlet pipe 8 through the reactor water take-out pipe 21', and this reactor water is transferred to the inside of the reactor containment vessel. Isolation valve 34, outer remote valve 35, piping 26, regenerative heat exchanger (primary side) 1
2. After passing through the non-regenerative heat exchanger 13, the pressure is increased by the coolant purification system pump 11, and after being purified by the filtration demineralizer 14, the water supply system piping 1 is passed through the pipes 24 and 24'.
5 to the reactor pressure vessel 1. By repeating these operations, the water quality inside the reactor is maintained at a specified level. Note that during such operation of the coolant purification system, that is, while the coolant purification system pump 11 is operating, the remote control valve 2 of the cooling system during reactor shutdown is activated.
2, 23, and 29 are interlocked to maintain the closed state, so that the primary coolant (reactor water) does not flow into the cooling system piping 17 when the reactor is shut down, and the stored water in the cooling system piping is cooled when the reactor is shut down. Material purification system piping 26, 24
There is no leakage or flow into the side, and the independence and integrity of the coolant purification system's functions are guaranteed.

In addition, during the reactor shutdown stage, approximately 20 hours of shutdown cooling operation will be carried out before complete shutdown is achieved.

This reactor shutdown cooling system operates the shutdown cooling system pump 5 and controls the opening of the remote control valves 22, 23, and 28 to control the recirculation system outlet side piping 9.
The reactor water taken out from the reactor passes through the reactor inner isolation valve 34, the outer isolation valve 35, and the remote control valve 22, is cooled by the heat exchanger 6, is pressurized by the shutdown cooling system pump 5, and is then transferred to the pipes 17, 29, and the remote control valve 22. Operation valve 28, piping 2
4', reactor pressure vessel 1 via water supply system piping 15
It will be returned to. By repeating this cooling system operation, the temperature of the cooling water in the reactor pressure vessel 1 is cooled to a predetermined temperature (approximately 50° C.) or lower. In addition, when the cooling system at the time of stoppage is operated, the remote control valve 27 of the coolant purification system is controlled to be closed in advance by remote control before the cooling system pump 5 is started at the time of stoppage, and the low pressure water injection system valve 26 is controlled to be closed. Therefore, the functional independence and soundness of the cooling system during shutdown are guaranteed.

The broken line shown in FIG. 1 indicates the coolant purification system mentioned above,
This shows the operation control system of the cooling system during reactor shutdown.
The valve 35 provided in the branch pipe 21' from the recirculation system is
It is controlled to be in a normally open state so that it can be used in common when both systems are in operation. The cooling system remote control valves 22, 23, and 28 are interlocked to close when the coolant purification system pump 11 is activated or the remote control valve 27 is open. In this embodiment, the reactor shutdown cooling system is divided into two systems, the A system and the B system, and the B system is not shown and only its remote control valve 23 is shown.

As described above, according to this embodiment, the operation of the coolant purification system during reactor operation can be carried out using the reactor water extraction pipe 21' and the pipe 26, which are shared with the cooling system during reactor shutdown. The dedicated pipe 19 for the coolant purification system (see FIG. 3) can be omitted. Furthermore, the operation of the cooling system at the time of shutdown of the nuclear reactor is controlled by the piping 17, the branch piping 29, and the water supply system connecting piping 24'.
This can be done by returning the water to the water supply system piping 15 via the
8 (see FIG. 3) can be omitted. Therefore, the piping 19 dedicated to the coolant purification system and the piping 18 dedicated to the cooling system during shutdown, or the piping dedicated to the reactor water return of the coolant purification system and the cooling system during reactor shutdown, which are arranged inside the reactor containment vessel 2, are used. In particular, this kind of piping was used by increasing the diameter of expensive stainless steel pipes and increasing the length of the pipes, so by reducing the number of pipes, the amount of piping, piping support, piping insulation,
It is possible to reduce the number of valve staff and realize an economical plant with a rational system configuration.

Furthermore, because the number of pipes 18 and 19 is reduced due to the above reasons, the penetration of pipes (nominal diameter of approximately 550 mm to 600 mm) that penetrates the containment vessel 2 can be reduced, and it is possible to reduce the number of atoms that need to be maintained to prevent radioactivity leakage. The reliability of the reactor containment vessel can be improved.

In addition, the shutdown cooling system piping (nominal diameter 350 mm) installed in the narrow space inside the reactor containment vessel
degree), so every year,
It can reduce the burden of cumbersome inspection work such as shutdown cooling system piping and piping support that is carried out inside the reactor containment vessel, and also eliminates the risk of exposure to radiation during inspection work and maintenance inspection work of this type of piping. can be reduced.

Furthermore, according to this embodiment, the cooling water cooled by the heat exchanger 6 is transferred to the pipe 1 during the operation of the reactor shutdown cooling system.
Since the reactor pressure vessel 1 can be returned to the reactor pressure vessel 1 via the branch piping 29 branching from the reactor recirculation system piping 8 and the water supply system piping 15, the return reactor water from the shutdown cooling system can be returned to the confluence of the reactor recirculation system piping 8, as in the past. (Symbol P in FIG. 4) is no longer necessary, thermal fatigue caused by the difference in internal fluid temperature between the two systems can be prevented, and the soundness of these pipes can be improved.

Further, in this embodiment, unlike the conventional case, a residual heat removal system pump 5 is disposed downstream of the heat exchanger 6 of the piping 17, and a coolant purification system is disposed downstream of the regenerative heat exchanger 12 of the coolant purification system. Since the pump 11 is arranged, the rate of radioactivity adhesion to the pumps 5 and 11 can be reduced. In other words, the relationship between the amount of cobalt 60 ( ⁶⁰ Co) deposited on piping and the amount of oxide film as shown in Figure 2 (the graph in Figure 2 is based on the ``Atomic Energy Society of Japan Annual Meeting Abstracts'' published in 1982). As is clear from the 22nd issue), the amount of ⁶⁰ Co deposited is
It reaches its maximum at around 250°C, and rapidly decreases as the temperature decreases.The amount of ⁶⁰ Co deposited, the amount of oxide film, and temperature dependence show similar trends, and at temperatures above Considering the characteristics, the radioactivity deposition rate can be further reduced by providing the pumps 5 and 11 downstream of the regenerative heat exchanger where the reactor water temperature is lowered. In particular, the reactor water temperature during normal reactor operation is approximately 280°C, whereas the internal fluid temperature on the downstream side of the heat exchanger is approximately 50°C, so the pump is placed on the upstream side of the heat exchanger. It is possible to reduce the dose rate to about 1/10 compared to the installation. Note that if pumps 5 and 11 are moved to the low temperature section downstream of the heat exchanger, the reactor water will be cooled by the heat exchanger.
Sufficient NPSH is ensured and there is no problem with pump operation.

〔Effect of the invention〕

As described above, according to the present invention, by rationally configuring the system configuration of the reactor shutdown cooling system piping, the coolant purification system piping, etc., it is possible to ensure the safety of work inspections of these types of piping, and to It is possible to reduce the amount of cooling system piping during reactor shutdown, coolant purification system piping, piping support, etc., and also eliminate thermal fatigue at the junction of cooling system piping and recirculation system piping during reactor shutdown.

[Brief explanation of the drawing]

Figure 1 is a piping diagram showing one embodiment of the present invention, Figure 2 is a piping diagram showing an embodiment of the present invention.
The figure shows a characteristic diagram showing the adhesion and temperature-dependent characteristics of ⁶⁰ Co.
FIG. 3 is a piping diagram showing a conventional example of nuclear reactor cooling system equipment. 1...Reactor pressure vessel, 2...Reactor containment vessel, 3
... Suppression pool, 4 ... Suppression pool water, 5 ... Pump, 6 ... Heat exchanger, 8, 9 ... Recirculation system line, 12 ... Regeneration heat exchanger, 14 ... Filtration means (filtration desalination device) , 15...Water supply system line (water supply piping), 17...Piping, 17'...Low pressure water injection line,
21'...Reactor water extraction piping, 24'...Water supply system connection piping,
26... Coolant purification system piping, 22, 27, 28, 3
0...Switching valve, 29...Branch piping.

Claims (1)

[Scope of Claims] 1. In a reactor cooling system equipment comprising a reactor water supply system, a recirculation system, a reactor shutdown cooling system (residual heat removal system), a coolant purification system, etc., the reactor cooling system comprises: system and coolant purification system.
It has a common pipe 21' that takes in reactor water from part 9 of the line of the recirculation system, and the downstream side of this common pipe 21' is branched, and one of the branch pipes 17 performs heat exchange sequentially from the upstream side. 6 and pump 5 to constitute the piping of the reactor shutdown cooling system line L2, and the other branch piping 26 connects the heat exchanger 1 in order from the upstream side.
3. A pump 11, a purification device 14, etc. are provided to configure the piping of the coolant purification system line L3, and a purification device for the downstream side of the pump 5 of the cooling system line L2 during reactor shutdown and the coolant purification system line L3. 14 on the downstream side are unified by a common pipe 24' and connected to the pipe 15 of the reactor water supply system line L1, and these lines are connected to the reactor shutdown cooling system line L2 and the coolant purification system line L3. line L2,L
line selection switching valves 22, 2 for selectively connecting the reactor water supply system line L1 with the reactor water supply system line L1;
Nuclear reactor cooling system equipment characterized by being provided with 7.