JPS62280689A - Nuclear reactor coolant purifying system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a reactor coolant purification system for improving the water quality of a nuclear reactor, and particularly relates to a nuclear reactor coolant purification system for improving the water quality of a nuclear reactor, and particularly for a nuclear reactor equipped with a boric acid water injection device as a cold shutdown function of a nuclear reactor. Relating to a reactor coolant purification system.

[Prior art]

Boric acid water is injected into a boiling water reactor using a boric acid injection play system pump as a reactor shutdown device, as described in Japanese Patent Application Laid-Open No. 112489/1983. This high-pressure core spray pump is used to restore the water level of the reactor core by spraying cooling water in the event of a loss of reactor water accident, and generally has a rating of approximately 350rd.
It has a large capacity of /h.

[Problems that the invention attempts to resolve]

However, the tank that stores boric acid has a small capacity of about 200 kg, and it is common to inject this amount in about 1 hour, so the above-mentioned high-pressure core spray system pump has a problem that the capacity is too large and is not suitable. was there. The reason for this is that when the water level inside the reactor rises to a certain level, the high-pressure core spray system injection valve closes, which may not reach the boric acid concentration required for an emergency shutdown of the reactor.

The present invention has been made in view of the above circumstances, and provides a reactor coolant purification system that can increase the concentration of boron in the reactor to a required concentration within an appropriate time during an emergency shutdown of a nuclear reactor. The purpose is to provide.

Means for Solving Problem C] In order to achieve the above object, the present invention provides a solution of boric acid solution in parallel with the piping, upstream of the filter provided in the piping connected to the nuclear reactor and forming a closed loop. It is equipped with an injection device.

[Effect]

According to the above configuration, the reactor coolant purification system is a normally operating system with a high-pressure, low-flow pump, and forms a closed loop for purifying the reactor water of the yK sub-reactor. Even if the system is equipped with a boric acid water injection device, the water level in the reactor is kept constant, so the concentration of boron in the reactor can be easily controlled.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the nuclear reactor coolant purification system according to the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

The reactor 1 is equipped with a coolant recirculation pump 2 for recirculating reactor water within the reactor 1.
Closed loop piping 3 for extracting reactor water is installed on the upstream side of
is connected at one end. This piping 3 is connected to a regenerative heat exchanger 4. A non-regenerative heat exchanger 5. Two reactor coolant purification system pumps 6 and a filter 7 are provided, and the other end of this pipe 3 is connected to the reactor 1 through the regenerative heat exchanger 4 again. ing. The filter 7 is made of resin or the like and has the function of absorbing iron cladding to which radioactive substances have adhered, and isolating valves 8 are provided at the front and rear of the filter 7. A first bypass 9 is provided in the piping 3 on the upstream side of the filter 7, and a boric acid water tank bypass valve 10 is provided in a portion of the piping 3 parallel to the bypass 9. This bypass 9 is provided with a boric acid water tank 12 to which inlet and outlet valves 11 are attached at the front and rear. A small diameter heating pipe 13 is provided which is connected between the outer sides of the inlet and outlet valves 11 and penetrates through the boric acid water tank 12. Also, in parallel with the filter s+s*#e;? The second bypass 14 is located between the outside of the slippery
This second bypass 14 is connected by a filter bypass valve 15 . Also, piping 3
A condenser 17 is connected to the downstream side of the filter 7 via a condenser blowdown valve 16 . 18 is nuclear fuel.

19 is a control rod.

Next, the operation of this embodiment will be explained. The nuclear fission reaction in the reactor fuel is suppressed when the boron in the reactor water reaches 11,000 PP, allowing the reactor to enter a cold shutdown state.

For this reason, in current nuclear power plants, the concentration of boron in the reactor is reduced to about 8 P per minute in order to bring the reactor to cold shutdown.
The pump 6 of this embodiment, which is equipped with a dedicated pump that can increase the rate of PM, is a high-pressure, low-flow pump that has performance exceeding this condition. In addition, two pumps 6 are installed in parallel, and one
Even if the stand breaks down, there will be no problem with injection. And by using this pump 6, compared to the conventional one, approximately 1
The required sodium borate can be injected into the reactor 1 within a time of /4.

Next, the transition from normal reactor coolant purification operation to reactor cold shutdown operation will be explained.

During normal reactor operation, the boric acid water tank 12 is closed to the inlet/outlet valve 1.
1, the bypass valve 10 is open, and the reactor water cooled from about 280°C to about 60°C by the heat exchangers 4 and 5 is pumped by the pump 6 at a flow rate of about 60 ref/sec per unit. It is pumped, purified by a filter 7, and then returned to the reactor 1.

Even if tosodium pentaborate leaks into the system from the boric acid water tank 12 at this time, it will be removed by the filter 7 installed downstream of the tank 12, so the concentration of sodium pentaborate in the reactor water will increase. It has no effect on reactor output.

Note that the bypass valve 15 is closed at this time.

During reactor cold shutdown operation, the bypass valve 15 of the filter 7 is opened and the isolation valve 8 is closed to prevent sodium pentaborate from flowing into the filter 7. Next, the boric acid water tank inlet/outlet valve 11 is opened, the bypass valve 1o is closed, and boric acid water is injected into the reactor 1.

In this example, the reactor coolant purification system used when injecting boric acid water is a closed loop that returns reactor water extracted from the reactor to the reactor. However, the reactor water level does not change, and while the water level remains stable, the boron concentration within the reactor can be raised to the required concentration in about 174 hours compared to conventional methods. Further, since the boric acid water in the boric acid water tank 12 is in contact with reactor water having a normal operating width of about 60° C. through the heating line 13, a heater for preventing sodium borate precipitation, which was conventionally necessary, is no longer necessary. Also, a dedicated pump for injecting boric acid water is not required.

Furthermore, since the leaked boric acid water can be adsorbed and treated by the filter 7, the boron concentration in the reactor water is not affected. Furthermore, since the normally operating pump is used for injecting boric acid water, there is no need for surveillance tests performed on emergency equipment, improving the reliability of the pump as a dynamic equipment. Furthermore, since the boric acid water tank 12 can be installed in a low temperature area (60° C. or lower), abnormal pressure increases in the tank can be prevented.

Further, since the temperature of the boric acid water injected into the reactor 1 is raised to about 200° C. by the regenerative heat exchanger 4, the thermal shock of the nozzle portion of the reactor pressure vessel, which conventionally occurs due to the injection of boric acid water, can be prevented. Note that even if the heating line 13 is not provided, the inlet/outlet valve 11 is always in contact with reactor water at about 60° C., so it is not necessary.

〔Effect of the invention〕

As described above, according to the present invention, since the boric acid water tank is provided in the reactor coolant purification system, it is possible to raise the boron concentration in the reactor to the required concentration within an appropriate time during an emergency shutdown of the 1M sub-reactor. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the reactor coolant purification system of the present invention. 1... Nuclear reactor, 2... Pump, 3... Piping, 4,
5... Heat exchanger, 7... Filter, 10... Boric acid water tank bypass valve, 12... - Boric acid water tank, 1
4... Bypass, 15... Filter bypass valve.

Claims (1)

[Claims] 1. In a reactor coolant purification system that includes a pump, a filter, and a heat exchanger in piping that is connected to a nuclear reactor and forms a closed loop, the piping is provided upstream of the filter. A reactor coolant purification system characterized by having a boric oxide injection device installed in parallel with the reactor coolant purification system. 2. The reactor coolant purification system according to claim 1, wherein the boric acid water injection device and the piping can be switched by a bypass valve. 3. Claims characterized in that the filter provided in the pipe is capable of switching between passing and not passing the fluid flowing through the pipe by a bypass having a bypass valve provided in parallel to the filter. The reactor coolant purification system according to item 1.