JPS5923295A - Fuel pool cooling and cleaning device - 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 a spent fuel pool cooling and purification device in an atomic couplant.

[Takuma's technique O to j target 11 feet and their melting point] Nuclear power tf
1 Atomic carburetors such as l'Ir are equipped with a spent fuel sole for storing spent fuel and a fuel pool purification device, and the fuel pool water is cooled and used by the fuel pool cooling and purification device. This is to remove the decay heat of the fuel and purify the fuel pool water at the same time. This fuel pool cooling and purification system is also designed to drain the reactor well and equipment pit filled with water for fuel exchange during periodic inspections.

FIG. 1 is a system diagram showing a conventional fuel pool cooling and purification device. The fuel pool cooling and purification device is used for spent fuel pool 1.
1 as a starting point and an end point, and in the circulation path, a gap passage 12 provided at the upper part of the spent fuel pool 11 connects to the spent fuel pool 11 from the upstream side. Surge tank 13. A pair of pumps 14 connected in a parallel circuit to the bottom of the surge tack 13
．． A filter 15 for purification and a heat exchanger 16 for cooling are arranged in this order. In addition, the surge tank 13 is connected to a reactor well 18 provided at the top of the reactor pressure vessel 17 by a clearance passage 19 provided at the top of the reactor well 18, and the reactor well 18 is connected to a drainage line. Pump 14 is connected to the population side. Furthermore, in the embodiment shown in FIG. 1, the pump 14 outlet side and the heat exchanger 16
Bypass piping 21 connecting the inlet side of filter Demine 15
It is provided by bypassing the In addition, Surge Tack 1
3 is provided with a water level detection device, and when the water level falls below a predetermined depth, a pump (IJ) knob signal is issued to protect the pump, and the operation of the pump 14 can be automatically stopped.

According to such a conventional fuel pool cooling and purification system, during normal operation of the nuclear coupler, the fuel pool water above the spent fuel pool 11 flows into the surge tank 13 through the gap passage 12, and is then drained there. The fuel boule water flowing into the
The pump 14 supplies the fuel to the filter demine 15 and the heat exchanger 16 for purification and cooling, and returns it to the fuel pool H through the re-grinding pipe 22 1131.

In addition, the fuel exchange during the fixed (υ1 inspection)
This is done by filling the adjacent equipment pit 1-23 with water, and then this water is passed through the filter demine I5 by the pump 14 and discharged from the branch pipe 24 to a condensate storage tank (not shown). In the case of , filter demine 15
(In ii%j, the water in the reactor well 18 is sucked in by the pump 14 from both the surge tank J3 and the drainage line, and the piping 21 bypasses the
A part of the fuel is discharged while adjusting the discharge flow rate with a valve 5 installed on the fuel tank 4, and the remainder is passed through a heat exchanger 16 to the fuel pool 11.
Cooling and evacuation are performed at the same time. However, when draining the reactor well 18 and equipment pit 23 using this method, the degree of opening and closing of the valve 5 is adjusted,
It is necessary to perform this while constantly monitoring fluctuations in the water level of the surge tank 13.

If the valve 5 is throttled too much, the amount of water returned to the solvent pool 11 will exceed the flow rate from the surge tank 13 to the pump 14.
The water level in the surge tack J3 rises, and when the valve 5 is opened too far, the water discharge exceeds the pump flow from the equipment pit 23 of the reactor well 181, so the water level in the surge tank 13 decreases, and the pump trip signal is activated. is generated and pump J4
will be automatically stopped. In addition, as drainage progresses, the water level in the reactor well 18 and equipment pit 23 decreases, and the balance of pump pushing pressure changes, resulting in a change in the suction amount balance between the reactor well side and the surge tank side. It is also necessary to adjust emissions accordingly. As described above, when draining water using the above method, the flow rate is adjusted while giving priority to maintaining the water level in the surge tank, so it is difficult to accurately adjust the water temperature in the spent fuel pool.

On the other hand, in an atomic coupler having a bypass pipe 21 of the filter temmine 15, the wells 26 and 27 in the parallel circuit of the pump 14 and the outlet (11
The valve 29 provided in the bypass pipe 21 is closed, the valve 28 provided in the bypass pipe 21 is opened, and the two pops 14 are connected to the valve 26.
゜27 partition, one pump is connected to the reactor well 18,
It is used exclusively for draining water from the 4-piece pit 23, and the curved pump is used to bury water in the fuel bottle for cooling only. According to this method, the water level of the surge tack 13 will not be increased, but during the discharge operation (1 (1 regular time about 9 hours)
hi, unable to convert fuel pool water f,
C,'/-p conversion takes a long time. Furthermore, since the flow meter that controls the fuel pool water is limited to the flow rate of one pump, it is difficult to freely adjust the temperature of the fuel pool water.

[Purpose of the invention]

The present invention was developed in consideration of these points,
It is an object of the present invention to provide a fuel pool cooling and purifying device that can drain a reactor well and an equipment pit with a simple operation and can purify a spent fuel pool even during this draining operation.

[Summary of the invention]

The fuel pool cooling and purification device according to the present invention is characterized in that the bottom of the surge tank is made deeper than the bottom of the reactor well, and the surge tank (!: the bottom of the reactor well is connected to the bottom of the reactor well by piping via a gate valve. There is.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a system diagram showing a water pool cooling and purifying device according to the present invention. In this embodiment as well, the spent fuel pool 11 is connected to a surge tank 13 through a gap passage 12 provided in the upper part, and two pumps 14 are installed downstream of the surge tack 13. They are connected in a parallel circuit. On the discharge side of the pump] 4, a filter Demio J5 and a heat exchanger 16 are further arranged in sequence.
A circulation flow path is formed by connecting the return pipe Yf22 to the fuel pool 11 again. In addition, piping 2J that bypasses Filter Demio 15 is arranged to connect the pump outlet side and the outlet side of Filter Demio 15.
There is.

The reactor well 18 and equipment bin l-23 are connected to the surge tack 13 by a gap shunt 19 provided at the bottom of the reactor well 8, and are also connected to the bottom 18a of the reactor well 8 and the → no. The surge tank 13 is connected to the reactor via two gate valves 31 and 32 arranged in series. Well 18
) is deeper than Mr. i1i 18a.

FIG. 3 is a partially enlarged view showing the surge tuck-over in the present invention. The surge tank 13 is provided with a water level detection device (not shown), which generates a pump trip signal when the water level falls below a predetermined level, so that the pump 14 is automatically stopped. In Fig. 3 1, the symbol ■
(This is the surge tank 1 that generates pump trip No. 18.)
3, and this set water level H is set to a value Δh lower than the level L of the bottom 18a of the reactor well 18. This Δh is a value larger than the head loss of the piping 30. Further, the bottom 13a of the surge tank 13 is deeper than the bottom 18a of the reactor well 18. Other parts similar to those in the embodiment of FIG. 1 are indicated using the same reference numerals.

Next, the operation of this embodiment having such a configuration will be explained.

First, cooling of the spent fuel pool during normal operation of the nuclear coupler is performed in the same manner as in conventional systems. That is, the fuel pool water flowing out from the spent fuel boule 11 into the surge tank 13 through the gap passage 12 is transferred to the pump 1.
4, the fuel pool water is circulated through the filter Demio 15 and the heat exchanger 16 to cool and purify the fuel pool water.

In addition, when draining water from the reactor well 18 and equipment pit 23 after fuel exchange, the gate valve 31
, 32 are fully opened, and valve 3 on the line of piping branching from the downstream side of Filter Demio J5 and leading to the condensate storage tank is opened. Through this operation, the water level difference between the water level in the reactor well [8] and the equipment pit 23 and the water level in the surge tank 13 is such that the reactor well side is higher than the water head loss of the piping (capital), and water is drained from the piping and pipes 24. With the same water level difference, the inland water level continues to fall. The pressure loss of the pipe 30 is extremely small because the pipe length is short, and the water level difference mentioned above is actually small. Therefore, even if the valve 5 is opened to an arbitrary opening degree and the drainage is set to an arbitrary value, the reactor well 1
8 and the water level difference between the equipment pit 23 and the surge tank J, 3 is small, and the flow being discharged to the summer water storage tank is always equal to the flow sleeve that flows through the pipe 30 to the reactor well 18111. ! It flows into the surge tank 13 from l and C. In addition, the water 1)'L in the surge tank where the pump trip signal is generated is set to a value lower than the head loss of the piping 30 from the bottom of the reactor well, and only the water level in the surge tank is 1)'L. - Since it cannot rise or fall, there will be no pot trips during drainage.

Moreover, since two gate valves 31 and 32 are arranged in series on the piping 30, no leakage occurs during normal operation.

〔Effect of the invention〕

As explained above, according to the present invention, when draining the reactor well and equipment pit, there is no need to monitor the water level in the surge tank or adjust the discharge flow rate, and the workers performing the drainage work can significantly reduce the burden on In addition, most of the drainage work can be performed automatically and remotely from the central control room, reducing radiation exposure for workers. In addition, drainage work can be performed while constantly purifying the fuel pool water, which improves drainage work efficiency, maintains the quality of the fuel pool water, and is effective in reducing radiation exposure to workers. In addition, drainage work can be performed by setting the amount of water discharged from the reactor well and equipment pit and the flow rate of circulating water in the fuel pool at any ratio, so that it can be adjusted according to the process requirements during periodic nuclear coupler plant inspections. It is possible to increase the amount of fuel pool water circulated and drain the spent fuel pool water while keeping the water temperature low, thereby improving work safety by improving the working environment near the fuel pool. Can be done.

[Brief explanation of drawings]

Figure 1 is a system diagram showing a conventional fuel pool cooling and purification system.
FIG. 2 is a system diagram showing a fuel pool cooling and purifying device according to the present invention, and FIG. 3 is an explanatory diagram of the vicinity of the surge tank of the device according to the present invention. 11... Fuel pool, 13... Surge tank, 14...
...Pump, 15...Filter Temine, 16 Jifu exchanger, 18.Reactor well, Ku..Equipment pit, 30.
G, 31, 32...Gate valve.

Claims (1)

[Claims] 1. Fuel pool water flowing into a surge tank from a gap passage provided at the top of a spent fuel pool that is placed in instant contact with a reactor well is connected to the bottom of the surge tank. In the fuel pool cooling and purification system in the nuclear power plant, the bottom of the surge tank is connected to the reactor. A fuel pool cooling and purification system characterized in that, even when the surge tank is deeper than the bottom of the well, the surge tank is connected to the bottom of the reactor well through a gate valve. 2. The fuel pool cooling and purifying device according to claim 1, wherein the pump connected to the lower part of the surge tank is automatically stopped by a pump trip signal when the water level in the surge tank becomes below a predetermined water level. . 3. The predetermined water level in the surge tank at which the pump trip signal is issued is set to a value that is lower than the water loss Vα in front of the bottom of the reactor well.
2. A fuel pool cooling and purifying device according to claim 2.