JP6705730B2 - Nuclear power generation system - Google Patents

Description

The present invention relates to a nuclear power generation system.

When an emergency situation occurs in the spent fuel pool of the nuclear power generation system where all cooling functions are lost due to an accident, etc., the flooding of the fuel stored in the spent fuel pool is maintained by continuing water injection by the alternative water injection facility. However, it is not possible to suppress the generation of steam. If the cooling function continues to be lost, it is necessary to release the vapor to the outside, but to suppress the release of radioactive materials as much as possible.

Non-Patent Document 1 below discloses a safety system having an SFP blowout panel provided with a HEPA filter. It also describes the inclusion of condensate collection in the design.

"Generic Design Assessment - New Civil Reactor Build Step 4 Mechanical Engineering Assessment of the Westinghouse AP 1000 (Copy Reight) Reactor", ONR-GDA-AR-11-010 Revision 0, Office for Nuclear Regulation, 11 November 2011, p. 115.

If the loss of the cooling function of the spent fuel pool occurs independently, it is possible to restart the cooling of the spent fuel pool and stop the generation of steam by using the residual heat removal system after the reactor cold shutdown. However, considering the simultaneous occurrence of the loss of all cooling functions including the residual heat removal system, the generation of steam cannot be avoided.

When the decay heat is large, such as immediately after a reactor shutdown, the amount of steam generated is large, so there is a possibility that the flow rate that can be processed by the emergency gas processing facility will be exceeded. It will be necessary to release directly from the building opening on the installation floor of the spent fuel pool. In this case, there is a concern that the dose of public exposure will increase compared to the case where the emergency gas treatment facility releases the gas from the stack at a high place.

The blowout panel described in Non-Patent Document 1 is provided with a HEPA filter, but the dominant radionuclide in the steam released from the spent fuel pool of a boiling water reactor is tritium, This is a nuclide that cannot be expected to be collected by a filter.

In view of the above circumstances, an object of the present invention is to reduce the amount of radioactive material released when the steam generated in the spent fuel pool is released to the outside of the reactor building, and to reduce the risk of public exposure. To provide a nuclear power generation system.

In order to solve the above problems, the nuclear power generation system according to the present invention guides steam generated from a spent fuel pool housed in a reactor building to a condenser, and in the condenser, radioactive substances in the steam are converted into water. After being condensed, the water vapor that has passed through the condenser is discharged from the exhaust stack. The condenser has a cooling fan, and the steam generated from the spent fuel pool rotates the cooling fan.

More specific configurations of the present invention are described in the claims.

According to the present invention, it is possible to reduce the amount of radioactive substances contained in water vapor before releasing the water vapor generated in the spent fuel pool to the outside of the reactor building, thereby reducing the risk of public exposure. A nuclear power generation system can be provided.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a schematic diagram showing a part of a nuclear power generation system according to a first embodiment. It is a schematic diagram which shows in detail the structure of the installation floor of the spent fuel pool in the reactor building of FIG. 1, and its periphery. It is a schematic diagram which shows an example of the condenser of FIG. FIG. 5 is a schematic diagram showing a condenser that constitutes a nuclear power generation system according to a second embodiment.

FIG. 1 is a schematic diagram showing a part of the nuclear power generation system according to the first embodiment. As shown in FIG. 1, a nuclear power generation system 100 according to the present embodiment includes a reactor pressure vessel 1 that accommodates devices necessary for generating and controlling nuclear reactions such as fuel, cooling water, and control rods; Reactor containment vessel 2 containing reactor pressure vessel 1, spent fuel pool 3 storing fuel used in reactor pressure vessel 1, reactor pressure vessel 1, reactor containment vessel 2 and spent fuel pool 3, a reactor building 5 for housing 3 and an exhaust pipe 8 connected to the reactor building 5 for exhausting gas inside the reactor building 5 to the outside of the reactor building 5.

A reactor well 4 and a steam dryer/steam separator pit 6 are provided above the reactor containment vessel 2. The reactor well 4 is filled with water to the same level as the water surface of the spent fuel pool 3 when exchanging the fuel in the reactor pressure vessel, so that fuel etc. is filled between the reactor pressure vessel 1 and the spent fuel pool 3. It is a space used for underwater transportation. The steam dryer/steam separator pit 6 is provided to store the steam dryer and steam separator during the periodic inspection.

FIG. 2 is a schematic diagram showing in detail the structure of the installation floor of the spent fuel pool 3 and its surroundings in the reactor building of FIG. As shown in FIG. 2, spent fuel 30 is stored in the spent fuel pool 3 and is filled with water 31 for flooding. As described above, in the event of an emergency in which all cooling functions are lost due to an accident, etc., it is possible to maintain flooding of the spent fuel 30 by continuing water injection by the alternative water injection equipment, but Since it cannot be cooled, the generation of water vapor 32 cannot be suppressed. As described above, the dominant radionuclide in the steam released from the spent fuel pool of a boiling water reactor is tritium (tritium). Unlike particulate radioactive material, tritium in water vapor cannot be removed by filters.

Therefore, in the present invention, the water vapor 32 released from the spent fuel pool 3 is condensed by the condenser (steam condenser) 10 before being transported to the exhaust stack 8 and released to the outside of the reactor building 5. Then, the water vapor 33 after a predetermined amount of tritium is removed as water through the condenser 10 is transported to the exhaust stack 8. With such a configuration, the tritium in the water vapor 32, which cannot be removed by the filter, is removed as the water 34, the concentration of tritium contained in the water vapor is reduced, and then the tritium is diffused from the exhaust stack 8 to a high place. , Can reduce the risk of public exposure.

The configuration of the present invention will be described more specifically. As shown in FIG. 2, the spent fuel pool 3 is connected to the first pipe 9 via the installation floor 7 of the spent fuel pool 3 of the reactor building 5. A condenser 10 is arranged between the first pipe 9 and the exhaust pipe 8. The condenser 10 is connected to the first pipe 9, and the steam 32 generated from the spent fuel pool 3 is transported to the condenser 10 via the first pipe 9.

Part of the water vapor 32 transported to the condenser 10 is condensed and water 34 is generated. A second pipe 11 is connected to the condenser 10 and the exhaust pipe 8, and the water vapor 33 that has passed through the condenser 10 is transported to the exhaust pipe 8 through the second pipe 11 and is transferred from the exhaust pipe 8 to the atoms. High places are spread outside the reactor building 5. On the other hand, a third pipe 12 is arranged between the spent fuel pool 3 and the condenser 10. The third pipe 12 is connected to each of the condenser 10 and the spent fuel pool 3, and the water 34 produced in the condenser 10 is transported to the spent fuel pool 3 through the third pipe 12. To be done. By having the third pipe 12, it is possible to prevent the water containing tritium from flowing out, and it is possible to save water in the pool used for submerging the spent fuel.

In the conventional nuclear power generation system, the condenser was sometimes provided as a condenser or the like provided in the turbine building, but as in the present invention, the condenser is condensed between the pipes connecting the spent fuel pool 3 and the exhaust stack 8. There is no configuration provided with a vessel. The above Non-Patent Document 1 also does not disclose where the device for collecting condensate is specifically provided.

As the condenser 10, a conventionally known one can be used. Considering the generation amount of the steam 32, it is preferable to use the water-cooled type (water is the refrigerant) rather than the air-cooled type (the refrigerant is air). FIG. 3 is a schematic diagram showing an example of the condenser of FIG. As shown in FIG. 3, it is preferable that the refrigerant pipe 14 that conveys the refrigerant be formed of a meandering tubular member or a corrugated member. When the refrigerant pipe 14 has such a shape, the contact area with the steam 32 containing tritium increases, and the condensation efficiency can be improved.

According to the above configuration, even in an emergency in which all cooling functions are lost due to an accident or the like, the condensing effect of the tritium in the steam by the condenser 10 and the diffusion effect by the high discharge from the exhaust stack 8 are combined. As a result, the risk of public exposure can be further reduced as compared with the case where steam is directly discharged from the building opening on the floor where the spent fuel pool is installed.

FIG. 4 is a schematic diagram showing a condenser that constitutes the nuclear power generation system according to the second embodiment. The nuclear power generation system according to the present embodiment differs from the first embodiment in that the condenser 10 has a cooling fan 13. The cooling fan 13 has a structure driven by the steam 32 released from the spent fuel pool 3. With such a configuration, even if the refrigerant in the refrigerant pipe 14 of the condenser 10 cannot be cooled due to an accident or the like, the water vapor 32 passing through the condenser rotates the cooling fan 13 to cause the refrigerant and the water vapor to pass through. Since 32 can be cooled, condensation of the steam 32 can be promoted.

Further, the condenser 10 may be provided with only the cooling fan without providing the refrigerant pipe. In this case, since no refrigerant is required, it is possible to suppress an increase in drainage.

As explained above, according to the nuclear power generation system of the present invention, before releasing the steam generated in the spent fuel pool to the outdoor part of the reactor building, the amount of radioactive material contained in the steam is reduced, It was shown that it is possible to provide a nuclear power generation system capable of reducing the risk of exposure.

It should be noted that the present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, with respect to a part of the configuration of each embodiment, other configurations can be added/deleted/replaced.

DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 2... Reactor containment vessel, 3... Spent fuel pool, 30... Spent fuel, 31... Water of spent fuel pool, 32... Steam released from spent fuel pool, 33... Water vapor after passing through the condenser, 34... Water produced in the condenser, 4... Reactor well, 5... Reactor building, 6... Steam dryer/water separator pit, 7... Reactor building spent fuel pool Installation floor, 8... Exhaust pipe, 9... First pipe (reactor building-condenser connection pipe), 10... Condenser, 11... Second pipe (condenser-exhaust pipe connection pipe), 12... 3 pipes (condenser-spent fuel pool connection pipe), 13... Cooling fan, 14... Refrigerant pipe, 100... Nuclear power generation system.

Claims (3)

A reactor pressure vessel containing a reactor, a reactor containment vessel containing the reactor pressure vessel, a spent fuel pool for storing fuel used in the reactor, the reactor pressure vessel, the atom A reactor building that houses the reactor containment vessel and the spent fuel pool; and an exhaust pipe that is connected to the reactor building and exhausts gas inside the reactor building to the outside of the reactor building,
A first pipe connected to the spent fuel pool for transporting water vapor released from the spent fuel pool;
A condenser that is connected to the first pipe and that condenses a portion of the water vapor transported through the first pipe to generate water;
A second pipe connected to the condenser and the exhaust stack, for transporting the steam that has passed through the condenser to the exhaust stack,
The nuclear power generation system, wherein the condenser has a cooling fan, and the steam cools the steam by rotating the cooling fan. Furthermore, it has 3rd piping connected to the said spent fuel pool and the said condenser, and the 3rd piping which transports the said water produced|generated in the said condenser to the said spent fuel pool. Nuclear power generation system. The condenser has a refrigerant pipe made of a tubular member or a corrugated plate-shaped member arranged in a meandering shape, and a refrigerant filled in the refrigerant pipe, and the water vapor contacts the refrigerant pipe. The nuclear power generation system according to claim 1, wherein the water vapor is condensed by exchanging heat with the refrigerant to generate the water.

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