JPS62161089A - Fuel cooling system of fuel exchanger for pressure tube typereactor - 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 to which the invention pertains]

The present invention relates to a fuel cooling system in a refueling machine for a pressure tube nuclear reactor.

[Prior art and its problems]

As a fuel exchange machine that transfers fuel to and from the reactor core of a pressure tube reactor, a traveling trolley that moves below the reactor core is equipped with two fuel storage magazines, a grab mechanism, and a pressure vessel containing purified water. It is known that the reactor is moved to a predetermined position and then the pressure vessel and the pressure pipe on the reactor core side are connected to load new fuel and remove spent fuel. In this case, in order to remove the decay heat of the spent fuel taken out from the core and collected in the pressure vessel, conventional fuel cooling systems circulate the water contained in the pressure vessel with a heat exchanger installed outside. A cooling method is used. Here, in Fig. 2 which shows the fuel cooling system in a conventional fuel exchanger, 1 is the core of a pressure tube reactor, 2 is a mobile fuel exchanger installed below the core 1, and the fuel exchanger 2 is a pressure vessel 4 mounted on a traveling trolley 3
Purified water is contained therein along with a fuel storage magazine indicated by reference numeral 5 and other grab mechanisms (not shown). Note that 6 is a snout that is connected to the pressure pipe 1a of the core 1. The enclosed water circulation cooling line 7 for the pressure vessel 4 of the heat exchanger 2 is configured as follows. That is, the cooling line 7 connects the pressure vessel 4 and the circulation pump 8.
It is formed as a closed loop with hose piping connected to the separately placed heat exchanger 9. Further, in the middle of the piping route of the cooling line 7, a long hose catenary 10 that expands and contracts in accordance with the travel of the traveling truck 3 is inserted at both the inlet and outlet sides of the pressure vessel 4. Note that 11 is a line of the secondary cooling system of the heat exchanger 9, and cooling water is supplied from the auxiliary equipment cooling system. By circulating the contained water in the pressure vessel 4 between it and the heat exchanger 9 through the contained water circulation cooling line 7, the decay heat of the spent fuel extracted from the reactor core and collected in the pressure vessel 4 can be removed. It will be done. In addition, in the conventional cooling system, in addition to the above-mentioned fuel cooling system, the make-up of the water contained in the pressure vessel 4 and the prevention of crud generated on the core side from entering the pressure vessel while connected to the pressure vessel 4. As a means for this, a condensate supply line 13 is installed between the pressure vessel 4 and a condensate system 12 that stores condensate generated on the furnace side. A drain drainage line 15 is connected to the drain system 14 for draining water. Further, a hose catenary 16 is inserted in the middle of the piping route of the condensate supply line 13 and the drain drainage line 15 so that the piping hose follows the movement of the traveling truck 3, similar to the cooling line 7 described above. There is. Note 17
1 is a pressurized condensate water supply pump, and 18 is a drain pump. As described above, the conventional fuel cooling system of a fuel exchanger includes a circulation cooling line 7 for the water contained in the pressure vessel, which forms a closed loop with respect to the pressure vessel 4, and a condensate supply line 13.
Drain drainage lines 15 are connected to each other, and each line is connected to a hose catenary 1 along the moving route of the traveling vehicle 3 so that the piping hose can follow the movement of the traveling vehicle 3.
0.16 is inserted in four places. On the other hand, the above-mentioned hose catenary is made of a flexible metal tube such as stainless steel according to nuclear power standards.
Furthermore, it is mandatory to replace the used hose catenary after using it for a predetermined period of time and to dispose of the used hose catenary as non-combustible solid waste. In addition, because radioactive fluid flows through this hose catenary during use, radioactive substances in the fluid adhere to the inside of the hose, and when replacing it, there are problems such as workers being exposed to radioactivity. be. From this point of view, in the conventional cooling system configuration shown in FIG. The amount of solid waste generated as a result of catenary replacement increases, which increases the capacity of the waste storage facility, and also increases the time required to replace the catenary, increasing radiation exposure for workers. The heat exchanger 9 installed in the circulation cooling line 7 needs to ensure a predetermined flow rate of primary side cooling water, so it is necessary to circulate a considerable amount of water through the VFI, and furthermore, this downstream side flow rate increases. As the diameter of the metal flexible tube constituting the hose catenary 1o increases, its lifespan according to standard calculations becomes shorter and its replacement frequency increases. It is also possible to consider a method in which the heat exchanger 9 is mounted on the traveling truck 3 of the fuel exchanger and a hose is piped between the heat exchanger 9 and the pressure vessel 4 to omit the hose catenary. In this case, there is a problem that sufficient maintenance space on the traveling truck cannot be secured.

[Purpose of the invention]

This invention was developed in consideration of the above points, and it solves the problems of the conventional fuel cooling system, has a simple configuration, reduces the number of hose catenaries used, extends the service life, and reduces the amount of solid waste generated. It is an object of the present invention to provide a highly economical fuel cooling system for a fuel exchange machine configured to reduce the amount of water used.

[Key points of the invention]

In order to achieve the above object, the present invention connects a pressure vessel to a condensate system and a drain system via a condensate supply line and a drain drainage line each containing a hose catenary, and introduces the condensate directly into the pressure vessel from the condensate system. The structure is configured to remove the decay heat of the spent fuel stored in the pressure vessel using the heat capacity of the condensate that overflows and drains to the drain system, thereby omitting the internal water circulation cooling line in the conventional cooling system and using a hose catenary instead. This is designed to reduce the number of bottles used.

[Embodiments of the invention]

FIG. 1 shows a fuel cooling system diagram of a fuel exchanger according to an embodiment of the present invention, and the same members corresponding to those in FIG. 2 are given the same reference numerals. That is, according to the present invention, compared to the conventional system configuration shown in FIG. Only the condensate supply line 13 and the drain drainage line 15 with the pipe 16 inserted therein are connected. Further, the condensate supply line 13 is opened at the bottom of the pressure vessel 4, and the other drain drainage line 15 is opened at the top of the pressure vessel 4, so that the condensate introduced into the pressure vessel flows through the entire area of the vessel. That's what I do. Furthermore, a drain tank 19 mounted on a traveling truck is inserted into the drain drainage line 15. Note that 20 is a condensate valve inserted in the condensate supply line 13, and 21 is a drain valve inserted in the drain drainage line 15. With this configuration, the inside of the pressure vessel 4 is always filled with condensate supplied from the condensate system 12 through the condensate supply line 13. At the time of fuel exchange, the pumps 17 and 18 are operated to introduce condensate from the condensate system 12 into the pressure vessel 4, and the overflow water is discharged into the pressure vessel 4 through the drain line 15 into the drain system 14. By allowing the condensate to flow through, the decay heat of the spent fuel pulled out from the pressure pipe 1a of the reactor core 1 and collected into the fuel storage magazine 5 of the pressure vessel 4 is removed by the heat capacity of the condensate flowing through the pressure vessel 4. It will be. In this case, the condensate flow rate is set so as to obtain a heat capacity commensurate with the amount of decay heat of the spent fuel collected in the pressure vessel 4, so that the decay heat of the spent fuel is absorbed by the condensate. Finally, the heat is radiated to the drain system 14. In particular, in the fuel exchange process where the pressure vessel 4 and the pressure pipe 1a on the furnace side are connected via the snout 6, the drain valve 21 inserted in the drain drainage line mentioned above is closed, and the pressure pipe 1a The pressure is balanced with the pressure water on the side, and the condensate is transferred from the pressure vessel side to the pressure pipe 1.
The decay heat of the spent fuel is released to the core side.

【Effect of the invention】

As described above, according to the present invention, the pressure vessel is connected to the condensate system and the drain system through the condensate supply line and the drain drainage line, respectively, each including a hose catenary, and the condensate is directly introduced into the pressure vessel from the condensate system. By using the heat capacity of the condensate that overflows into the drain system and removes the decay heat of the spent fuel stored in the pressure vessel, the cooling system has an increase of +11 compared to the conventional cooling system. Since the water circulation cooling line is omitted, the overall configuration of the cooling system is simplified, and costs including its auxiliary equipment and piping can be significantly reduced. (2) According to Section 111 above, two hose catenaries used in the circulation cooling line will be deleted.
The radiation exposure of workers and the amount of solid waste generated due to hose catenary replacement are reduced accordingly. (33) The supply amount of condensate flowing through the pressure vessel should be set according to the heat capacity of the condensate that corresponds to the decay heat of the spent fuel, without being restricted by the specifications of the heat exchanger as in conventional systems. Therefore, the flow rate of condensate throughflow is smaller than the amount of conventional contained water circulation, and the diameter of the hose catenary can be reduced accordingly, extending its life and reducing the frequency of replacing the hose catenary. You can obtain practical effects such as:

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a fuel cooling system of a fuel exchanger according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a fuel cooling system of a conventional fuel exchanger. In each figure, 1: Core of pressure tube reactor, 2: Fuel exchange machine, 3: Traveling truck, 4: Pressure vessel, 5: Fuel storage magazine, 12: Condensate system, 13: Condensate supply line, 14: Drain Series, 15:
Drain drain line, 16: Hose catenary, 19: Drain tank, 21: Drain valve. , nee, °, :.・・１． E- Figure 1

Claims (1)

[Scope of Claims] 1) A fuel exchange machine that transfers fuel to and from the core of a pressure tube nuclear reactor, in which purified water is contained in a pressure vessel containing a fuel storage magazine, etc. mounted on a traveling truck. , in which the spent fuel contained in the pressure vessel is cooled by the contained water, the pressure vessel is connected to a condensate system via a condensate supply line and a drain drainage line each including a hose catenary;
The method is characterized in that the heat capacity of the condensate that is connected to the drain system via piping, is directly introduced into the pressure vessel from the condensate system, and is overflowed and drained to the drain system is used to remove the decay heat of the spent fuel stored in the pressure vessel. The fuel cooling system of the fuel exchanger for the pressure tube reactor. 2) The fuel cooling system according to claim 1, characterized in that the condensate supply line opens at the bottom of the pressure vessel, and the drain drainage line opens at the top of the pressure vessel. Fuel cooling system for a pressure tube type nuclear reactor refueling machine. 3) The fuel cooling system according to claim 1, for use in a pressure tube nuclear reactor, characterized in that a drain tank for temporarily storing overflow water of the pressure vessel is inserted in the drain drainage line. Fuel cooling system of fuel exchanger. 4) In the fuel cooling system according to claim 1, the pressure pipe is characterized in that a drain valve is inserted in the drain drainage line to close the drain drainage line when the pressure vessel and the nuclear reactor are connected. Fuel cooling system for a refueling machine for type nuclear reactors.