JPH07128496A - Cask cleaning equipment - Google Patents

Abstract

PURPOSE:To provide an efficient cask cleaning equipment with small secondary waste generation by combining a cleaning means for fuel treating pit and fuel pool and a cask cleaning means. CONSTITUTION:The cask cleaning equipment is characterized by that each of a fuel treating pit 1 to take out spent fuel, a spent fuel pool 3 placed in connection with this to store spent fuel and a cask 9 containing spent fuel are provided with cleaning means 1a, 3a, 9a for internal water and that cleaning water is supplied from each cleaning means 1a, 3a, 9a for cleaning operation of cask internal water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reprocessing facility for receiving spent fuel, and more particularly to a device for purifying a cask which is a means for transporting spent fuel.

[0002]

Spent fuel generated in a nuclear power plant is stored in each nuclear power plant for a predetermined period and then transferred to a reprocessing facility. While being stored in each nuclear power plant, it is cooled by cooling water in the pool, and this cooling water is circulated and reused.

The system configuration diagram of FIG. 3 shows a cooling water purifying device, in which a fuel assembly (not shown) carried from a nuclear reactor through water is taken out in a fuel handling pit 1 and used through a weir 2. It is stored in the spent fuel pool 3 and cooled.

An undissolved product called a clad (Chalk River Unidentified Dedposit) adheres to this spent fuel in the nuclear reactor, and this insoluble product floats in the water during water transfer and cooling. The floating clad is sent together with water by a pump 4, and is removed by using a hollow fiber membrane filter 5 and a desalting device 6 containing an ion exchange resin, and purified water is treated again as a fuel through a heat exchanger 7. Returned to pit 1 and spent fuel pool 3.

This purifying device has the capability of sufficiently purifying the capacity, temperature, and amount of clad (radioactivity) of treated water, and is highly reliable. However, in general, the ion exchange resin using the hollow fiber membrane filter 5 and the desalting device 6 has low heat resistance and is very suitable for use under the conditions such as the above-mentioned purification device, but at a high temperature (70 ° C. or higher). It has the property that it cannot be used for water filtration.

When the spent fuel from each nuclear power plant is to be centrally stored at a spent fuel reprocessing facility or the like, the spent fuel from each nuclear power plant is transferred by including it. It is transported by a cask (not shown) which is a transportation means.

However, the cask is filled with water together with the spent fuel, but since the internal water becomes high in temperature, its purification is performed with a structure similar to that of the fuel pool purification system of the nuclear power plant described above. A conventional purifying device cannot be applied as it is, and a clad removing device using a ceramic filter having excellent heat resistance has been proposed.

[0008]

Spent fuel in a nuclear power plant is stored in a cask (not shown) and is transferred to a reprocessing facility. At this time, vibration of the clad adhering to the spent fuel causes vibration during transfer. Most of it peels off and floats in the water filled inside the cask. Further, the heat of the spent fuel is transmitted to the water inside the closed cask, and the temperature rises to 80 to 90 ° C.

Therefore, in the reprocessing facility, if the cask is directly put in the fuel handling pit 1 and the spent fuel is taken out, as in the above-mentioned nuclear power plants,
In the internal water of the fuel handling pit 1 and the internal water of the spent fuel pool 3 communicating with this, the clad floating in the cask internal water diffuses to increase pollution.

Further, the heat of the water inside the cask raises the temperature of the water inside each pool, which promotes the deterioration of the ion exchange resin contained in the hollow fiber membrane filter 5 and the desalting device 6, and this result and the above. Due to the increase of pollution by the clad, there was a problem that a large amount of secondary waste was generated on the downstream side.

On the other hand, a clad removing means for purifying only the water inside the cask by using a ceramic filter having a high heat resistance has been proposed, but a large amount of water is required for cooling the water inside the cask. However, there was an economic problem in using a single technology for equipment.

An object of the present invention is to provide an efficient cask purifying apparatus which produces a small amount of secondary waste by combining a fuel handling pit and a spent fuel pool purifying means with a cask purifying means. Especially.

[0013]

In order to achieve the above object, a cask purifying apparatus according to the invention of claim 1 is a fuel handling pit for taking out spent fuel, and a spent fuel installed in communication therewith. In the cask containing the spent fuel pool and the spent fuel for storing the fuel, the fuel handling pit, the spent fuel pool, and the installed cask are each provided with a means for purifying internal water, and at the time of purifying operation of the cask internal water, Purified water is supplied from each of the purifying means.

In the cask purifying apparatus according to the second aspect of the present invention, the fuel handling pit and the spent fuel pool, and the purified water produced by the internal water purifying means provided in each of the cask are the fuel handling pit and the spent fuel pool, It is characterized by returning to a cask.

In the cask purifying apparatus according to the third aspect of the present invention, a hollow fiber membrane filter is used as the purifying means in the fuel handling pit, and a desalting apparatus containing an ion exchange resin is used as the purifying means in the spent fuel pool. A ceramic filter is used for the cask cleaning means.

[0016]

According to the first aspect of the present invention, the cask installed at a predetermined position is connected to each pipe through each pipe and the stop valve, and the stop valve is opened to operate the cask purifying apparatus. As a result, the water inside the fuel handling pit and the spent fuel pool is purified from the spent fuel pool purification means, flows into the cask, cools the cask internal water, and discharges it to the outside.

Thus, the water inside the cask containing a large amount of clad at a high temperature is purified and cooled by the cask purifying means having an excellent purifying function at a high temperature. Further, the inside of the cask and the spent fuel are purified and cooled by the purified water in the fuel handling pit and the spent fuel pool.

According to the second aspect of the present invention, the water inside the fuel handling pit and the spent fuel pool is purified by the respective purifying means, and after being purified and cooled in the cask and the water inside the cask is cooled. Purified by the respective purifying means of the fuel handling pit and the spent fuel pool, and returned to the fuel handling pit and the spent fuel pool again.

Further, separately the water inside the cask and the purified water from the fuel handling pit and the spent fuel pool that have cooled the inside of the cask are purified by the purifying means of the cask to be make-up water, and the fuel handling pit and the spent fuel pool and Return to the cask for efficient use of purified water.

According to the third aspect of the present invention, a hollow fiber membrane filter is used as the cleaning means for the fuel handling pit, a desalting device containing an ion exchange resin is used as the cleaning means for the spent fuel pool, and a cask cleaning means. A ceramic filter having an excellent high-temperature function is used for the above, and deterioration of each purifying means due to the treatment temperature is suppressed and the amount of secondary waste is reduced by maintaining the function.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those in the above-described conventional technique are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in the system configuration diagram of FIG. 1, the fuel pool purification system includes a fuel handling pit 1 filled with cooling water and a spent fuel pool 3.
The water in the fuel handling pit 1 communicates with the weir 2, and is pumped by the pump 4 to be purified by the hollow fiber membrane filter 5 which is the purification means 1a of the fuel handling pit.

The internal water of the spent fuel pool 3 is sent by the pump 8 together with the internal water of the fuel handling pit 1 purified by the purification means of the fuel handling pit to the spent fuel pool purification means 3a. It is formed so as to be purified by using a desalting device 6 containing a certain ion exchange resin, further cooled by a heat exchanger 7 and returned to the fuel handling pit 1 and the spent fuel pool 3 again.

As a cask purifying system, the cask purifying means 9a is a stop valve 7a on the outlet side of the heat exchanger 7.
And a cask 9 containing the spent fuel transferred from each power plant is connected to a stop valve 4a on the suction side of the pump 4, and a stop valve 4b and a stop valve on the suction side of the pump 4 are connected. A cask internal water receiving tank 10 for collecting the internal water discharged from the cask 9, a pump 11, a ceramic filter 12, and a purifying facility 13 are connected to and formed with 4a.

From the cask purifying means 9a, washing water is supplied to the cask 9 and the fuel handling pits 1,
Also, makeup water is supplied to the spent fuel pool 3.

As for the purification facility 13, as shown in the detailed configuration diagram of FIG. 2, a filtered water tank 14 for collecting the filtered water filtered by the ceramic filter 12, a heat exchanger 15 for cooling the filtered water, and A collection tank 16, a pump 17, a hollow fiber membrane filter 18, a desalting device 19, a sampling tank 20 for confirming the water quality, a makeup water tank 22 and a pump 23.

Next, the operation of the above configuration will be described. The cask 9 containing the spent fuel transferred from each nuclear power plant is installed at the predetermined position shown in FIG. 1 and connected to various pipes through the stop valves 4a and 7a to purify the spent fuel pool 3. The heat exchanger 7 in the means 3a,
Also, it is connected to the cask internal water receiving tank 10 in the purifying means 9a of the cask 9.

Initially, the stop valve 4b is closed, and the stop valve 4 is closed.
By opening a and 7a and operating the cask purification device, purified water obtained by purifying the internal water of the fuel handling pit 1 and the spent fuel pool 3 from the heat exchanger 7 flows into the cask 9, so that the water temperature 80 The water inside the hot cask at ~ 90 ° C
The water is discharged to the water tank 10 inside the cask while being cooled to about 70 ° C.

As described above, when the cask internal water containing a large amount of clad at a high temperature is discharged to the outside of the cask 9, and then the temperature of the internal water discharged from the cask 9 and the clad mixed amount decrease, the stop valve 4b is opened. Then, a part of the internal water discharged from the cask 9 is returned to the purification means 1a of the fuel handling pit 1 and the purification means 3a of the spent fuel pool 3 via the stop valve 4b to be purified and cooled.

As a result, a large amount of internal water stored in the fuel handling pit 1 and the spent fuel pool 3 is purified and cooled by the purifying means 1a of the fuel handling pit 1 and the purifying means 3a of the spent fuel pool 3. Becomes purified water and becomes a cask 9
Flowing in, the cask 9 and the spent fuel in the cask 9 are purified and cooled.

Further, the cask 9 is removed from the cleaning means 9a.
The water inside the cask, which flowed out into the water and was collected in the water tank for receiving the water inside the cask 10 together with the clad separated from the spent fuel, was purified and cooled in the ceramic filter 12, which has excellent high-temperature function, and further in the purification equipment 13, to be supplied. It becomes water.

That is, the cask internal water in the cask internal water receiving tank 10 is filtered by the ceramic filter 12 to remove the clad in the water. This filtered water is collected by the filtered water tank 14 of the purification facility 13 shown in FIG. 2, further cooled by the heat exchanger 15, and then temporarily stored in the collection tank 16.

The filtered water whose temperature has dropped is sent from the collection tank 16 by the pump 17, filtered by the hollow fiber membrane filter 18, and further filtered by the ion exchange resin incorporated in the desalting apparatus 19. This filtered water is a sampling tank 20
In (1), a part of the water is extracted, the water quality is checked, and then collected as makeup water in the makeup water tank 22. This makeup water is supplied to the cask 9 or the fuel handling pit 1 and the spent fuel pool 3 by the pump 23 as needed.

As a result of the purification treatment by the cask purifying apparatus of the present invention, the cask 9 is in a state in which the internal water containing the floating clad is discharged and the clad heat is removed. Next, the cask purification device is temporarily stopped, the stop valves 4a and 7a are closed to disconnect the cask 9 from the cask purification device, and the cask 9 is transported to the fuel handling pit 1 to take out the spent fuel from the cask 9 in the water. It is transferred to and stored in the spent fuel pool 3 through the cough 2.

In the cask 9 at this time, the clad has been removed from the cask internal water as well as the spent fuel, and the cask internal water has a low temperature. Therefore, the spent fuel taken out into the fuel handling pit 1 and the water inside the cask do not contaminate the water inside the fuel handling pit 1 and the spent fuel pool 3 and do not raise the water temperature.

When the cask 9 is not cleaned, the fuel handling pit 1 and the spent fuel pool 3 are operated by operating the purifying means 1a of the fuel handling pit 1 and the spent fuel pool purifying means. Purification and cooling of internal water is performed.

According to the present invention, before the spent fuel is taken out from the cask 9 and before the clad in the cask 9 diffuses to the other, it can be discharged from the cask 9 and captured. Further, the purified water purified and cooled by the respective purifying means 1a and 3a is supplied from the fuel handling pit 1 and the spent fuel pool 3 of the fuel pool purification system which always holds a large amount of cooling water as compared with the cask purification system. Therefore, the cask 9 can be efficiently cooled, and it is not necessary to separately store a large amount of purified water as a cask purifying system or to perform a purifying treatment, thereby simplifying the purifying equipment for the cask internal water.

Further, since the inside of the cask 9 carried into the fuel handling pit 1 is sufficiently cooled including the spent fuel and there is no clad, the inside of the fuel handling pit 1 and the spent fuel pool 3 are Since the water temperature does not rise and the contamination by the clad does not occur, heat deterioration of the hollow fiber membrane filter 5 of the purifying means, the ion exchange resin and the like contained in the desalting device 6 can be prevented, and the purifying function can be maintained for a long time. The amount of secondary waste generated will be reduced.

[0038]

As described above, according to the present invention, the efficiency of the cask and spent fuel purification and purification facilities in the spent fuel reprocessing facility, etc. is improved, and the amount of secondary waste generated in the purified water and the purification system is reduced. Since it can be reduced, it has an effect of improving the economical efficiency.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a cask purification device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a purification facility according to an embodiment of the present invention.

FIG. 3 is a system configuration diagram of a conventional cask purification device.

[Explanation of symbols]

1 ... Fuel handling pit, 1a ... Purification means for fuel handling pit, 2 ... Cough, 3 ... Spent fuel pool, 3a ... Spent fuel pool purification means, 4, 8, 11, 17, 21, 23 ... Pump, 4a, 4b, 7a ... Stop valve, 5, 18 ... Hollow fiber membrane filter, 6, 19 ... Desalination device, 7, 15 ... Heat exchanger, 9 ... Cask, 9a ... Cask purification means, 10 ... Cask internal water Receiving tank, 12 ... Ceramic filter, 13 ... Purification equipment, 14
... filtered water tank, 16 ... waste liquid collection tank, 20 ... sampling tank, 22 ... makeup water tank.

Claims (3)

[Claims] 1. A fuel handling pit for taking out spent fuel from an underwater cask, a spent fuel pool for storing spent fuel installed in communication therewith, and a cask containing spent fuel, wherein the fuel handling is performed. An apparatus for purifying internal water is provided in each of the pit, the spent fuel pool, and the installed cask, and the purified water is supplied from each of the purification means during the operation for purifying the internal water of the cask. 2. Purified water by internal water purification means provided in each of the fuel handling pit, the spent fuel pool, and the cask is returned to each fuel handling pit, the spent fuel pool, and the cask. 1. The cask purification device according to 1. 3. A hollow fiber membrane filter is used for the purification means of the fuel handling pit, a desalting device containing an ion exchange resin is used for the purification means of the spent fuel pool, and a ceramic filter is used for the cask purification means. The cask purification device according to claim 1 or 2, characterized in that.