JPS6290598A - Fuel-pool cooling purification 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 [Technical Field of the Invention] The present invention relates to improved purification flushing of cooling pumps and heat exchangers constituting a fuel pool cooling and purification system in a nuclear power plant.

[Technical background of the invention and its problems]

Conventionally, the fuel pool cooling and purification system of a nuclear power plant is as shown in Figure 3, and when disassembling and inspecting the cooling pump 1 and heat exchanger 2, the cooling pump 1 and heat exchanger 2 are Removes foreign substances such as limescale and rust. After stopping cooling pump 1 for this special number,
After stopping the pool water 5 from the fuel storage pool 4 from flowing into the skimmer surge tank 6 by the skimmer weir 3 and closing the skimmer surge tank outlet valve 7, the cooling pump 1 is closed.
, the pool water 5 in the heat exchanger 2 and the piping before and after it is opened, and the drain valve 8 is discharged through the drain piping 9 to the wastewater treatment equipment (not shown) using electricity, and then the drain valve 8 is closed and the makeup water supply valve is discharged. 10 and fill the skimmer surge tank 6 with clean make-up water, open the skimmer surge tank outlet valve 7 and clean the inside of the cooling pump 1, heat exchanger 2, and the piping before and after them via piping 11. After filling with make-up water, the skimmer surge tank outlet valve 7 is closed, and the drain valve 8 is opened again to drain the make-up water to the wastewater treatment equipment by gravity for flushing. This operation is repeated multiple times as necessary.

In this way, in the conventional flushing method, the cooling pump 1
, it is necessary to fill make-up water into the heat exchanger 2 and the piping before and after it, and to drain it, which is time-consuming, and since the drain relies on gravity, the flushing effect is weak, so it is necessary to repeat the work. Due to the increased frequency, the volume of wastewater also increased, putting a greater burden on not only the drainage basin but also the wastewater treatment equipment, including the treatment of radioactive waste from the wastewater.

If the water is not filled with water after completion, the driving test will not be possible.

There was also the problem that the construction period would be longer because the functionality of the fuel storage pool 4 had to be checked after it was completed.

[Purpose of the invention]

The present invention was made in view of the above-mentioned circumstances, and it reduces the amount of waste water and efficiently and effectively uses a cooling pump.
To provide a fuel pool cooling and purification system that can purify the inside of a heat exchanger and also allow an operation test of a cooling pump even when the fuel storage pool is unfinished and there is no water inside, such as during construction.

[Summary of the Invention] The present invention forms a circulation flow path in a part of a fuel pool cooling and purification system, passes through a filtration and demineralization tower, and circulates purified pool water into a cooling pump and a heat exchanger. This makes it possible to easily and effectively carry out purification flattening, and to test the operation of the cooling pump without using a fuel storage pool.

[Embodiments of the invention]

Hereinafter, one embodiment of the fuel pool cooling and purification system of the present invention will be described in the first embodiment.
This will be explained with reference to the figures and FIG. Note that the same reference numerals are given to the parts described above as the prior art, and detailed explanations are omitted.

The structure of the present invention is that a skimmer surge tank 6 and a cooling pump 1 are connected by a skimmer surge tank outlet valve 7 and a pipe 11, and the cooling pump 1 is connected to the pipe 1 via a heat exchanger 2.
2 is connected to the filtration and demineralization tower 13. This filtration desalination tower 1
3 is provided with an inlet valve 13a and an outlet valve 13b, and from the outlet valve 13b, a pool return valve 14 and a return pipe 15 are provided.
It is connected to the fuel storage pool 4 by a circulation pipe 17 which is further connected to the suction side of the cooling pump 1 and is provided with an isolation valve 16.

Note that the above is the cooling pump 1. viewed from the piping 11. Heat exchanger 2. This is a configuration in which the filtration and demineralization tower 13 are installed in this order, but if the heat exchanger 2 is installed downstream of the filtration and demineralization tower 13, the outlet side of the heat exchanger 2 and the cooling pump A circulation pipe 17 and an isolation valve 16 are connected between the suction side of the valve 1 and the suction side of the valve 1.

Next, we will discuss the effects of Ichihiki structure 1. The drain valve 8 is closed, and the isolation valve 16 is gradually opened while closing the pool return valve 14. Cooling pump 1 → heat exchanger 2 → filtration and demineralization tower 13 → circulation piping 17 → isolation valve 16 → cooling pump 1
A circulation flow path is formed to perform circulation operation, and the cooling pump 1
Radioactive substances such as limescale and rust that have separated from the heat exchanger 2 and piping 12 and are mixed into the pool water 5 flowing in the flow path are filtered and captured by the filtration demineralization tower 13, and the purified pool water 5 is It circulates within the cooling pump 1 and the heat exchanger 2.

After running for the required time and purifying the circulation flow path, stop the cooling pump 1, close the skimmer surge tank outlet valve 7, the inlet valve +3a and outlet valve 13b of the filtration and demineralization tower 13, and the isolation valve 16, and then drain the drain. The work is completed by opening the valve 8 and discharging the pool water 5 in the cooling pump 1, the heat exchanger 2, and the pipes 12 before and after the cooling pump 1 and the heat exchanger 2 through the drain pipe 9 to a wastewater treatment facility (not shown).

After that, disassemble and inspect the cooling pump 1 and heat exchanger 2, and after completing the disassembly and inspection, close the drain valve 8, open the make-up water supply valve 10, and then open the skimmer surge tank outlet valve 7, filtration drain valve, etc. Inlet valve 13a and outlet valve 13 of salt tower 13
b and the isolation valve 16 are opened to fill the system with clean make-up water, and when the system is full, the make-up water supply valve 10 and the isolation valve 16 are closed to prepare for restarting the system.

Note that the filtration and demineralization tower is backwashed at appropriate times as necessary to renew the filtration agent.

4 is under construction and cannot be filled with water, close the pool return valve I4 and drain valve 8, then close the make-up water supply valve 10,
Open the skimmer surge tank outlet valve 7, isolation valve 16, as well as the inlet valve 13a and outlet valve L3b of the filtration and demineralization tower 13, fill the system with makeup water, and heat exchange the cooling pump 1.

exchanger 2 → filtration demineralization tower 13 → @ ring pipe 17 → isolation valve 16 →
An operation test of the cooling pump 1 can be performed by forming the fI circulation path of the cooling pump 1.

〔Effect of the invention〕

As described above, the following effects can be obtained by the present invention.

1) The brushing water that flows through the cooling pump and heat exchanger has a certain flow rate, so the flushing effect is large and purification can be done in a short time, reducing the radiation exposure of disassembly and inspection workers.

2) The cooling pump and heat exchanger can be flushed by simply opening and closing the valve, and the cleaning time is short, improving work efficiency.

3) Since the amount of wastewater discharged to wastewater treatment equipment, including radioactive waste treatment, is reduced, the burden on the equipment can be reduced.

4) Since the cooling pump can be operated and tested during the construction period without waiting for the completion of the fuel storage pool construction, the performance of the cooling pump can be confirmed early and the process can be shortened.

[Brief explanation of drawings]

FIG. 1 is a piping system diagram showing the circulation operation of the present invention;
This figure is a piping system diagram showing the time of draining the pool water in FIG. 1, and FIG. 3 is a piping system diagram showing the time of supplying make-up water in the conventional fuel pool cooling and purification system. 1...Cooling pump, 2...Heat exchanger. 4...Fuel storage pool, 5...Pool water. 6... Skimmer surge tank, 7... Skimmer surge tank outlet valve, 8... Drain valve, 9... Drain piping, 10... Makeup water supply valve, II, 12... Piping 13. ...filtration demineralization tower, 13a...inlet valve, 13b...outlet valve,
14...Pool return valve. Work 5...Return piping, 16...Isolation valve. 17...Circulation piping. Agent Patent Attorney Noriyuki Chika Yudo Hirofumi Mitsumata Figure 1 Figure 2

Claims (1)

[Claims] In a fuel pool cooling and purification system, the pool water in the fuel storage pool of a nuclear power plant is circulated by a cooling pump via a heat exchanger and a filtration and demineralization tower to cool and purify it.
A fuel pool cooling and purification system characterized in that a circulation flow path is formed by connecting an isolation valve and circulation piping between the suction side of a cooling pump and a return flow path to a fuel storage tank.