JP3000778B2 - Decontamination equipment for refueling unit of pressure tube reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decontamination apparatus for decontaminating a pressure vessel of a fuel exchanger of a pressure tube reactor.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing the entire fuel handling facility of a pressure tube reactor. In FIG. 3 , a reactor 22 is accommodated in a reactor containment vessel 21, and a number of pressure tubes are arranged in the reactor 22, and a fuel body and a coolant are accommodated in the pressure tubes. A fuel exchange chamber 23 is disposed below the reactor 22, and is exchanged with fuel in the reactor 22 by a fuel exchanger 26 from below the reactor 22. The fuel exchanged by the refueling machine 26 is taken in and out of the refueling pool 24 by the fuel accessor 27, stored in the storage rack 28, and transferred to the fuel transfer pool 25 by the transfer chute 29.

FIG. 4 is a schematic configuration diagram of a refueling machine. The refueling machine houses an internal structure 3 such as an elevating mechanism in a pressure vessel 2 supported by a bogie (not shown), and a glove 4 is provided above the internal structure 3. Below the pressure vessel 2 is a lower head 1. When the fuel is exchanged, the exchanger is connected to the pressure pipe 6 in a watertight manner, and then the glove 4 is inserted from the lower part of the pressure pipe 6 to connect the glove 4 to the fuel 5. Housed within. In the nuclear reactor, cladding generated by corrosion of the primary cooling system piping of the nuclear reactor floats in the primary cooling water and adheres to the surface of the fuel during the flow process. Due to the vibrations and the like generated in the fuel by the refueling operation, the clad attached to this surface is peeled off and falls off, and most of the cladding is affected by the gravity, so that most of the lower head 1 of the refueling machine.
Deposited on Since the clad has high radioactivity, it is necessary to remove the clad so that workers are not exposed when the lower head 1 is opened for overhaul of the refueling machine.

FIG. 5 is a diagram showing a decontamination operation of a conventional refueling machine. In FIG. 5, after refueling, the lower head is opened from the refueling machine, and after removal, the vinyl sheet 8 is put on the periphery of the pressure vessel for curing, and a washing water receiving bucket 9 is placed under the pressure vessel. The worker sprayed water on the internal structure 3 using the hose 10 to remove the clad attached to the internal structure 3.

[0005]

Conventionally, since the internal structure of the refueling machine is sprinkled and washed by an operator from the outside, the radiation exposure can be reduced at the time of disassembly and inspection of the refueling machine after washing. There was a problem that workers were exposed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a decontamination apparatus for a refueling machine which can wash the internal structure of the refueling machine of a pressure tube reactor while maintaining the internal structure of the refueling machine in the lower head of the pressure vessel. And

[0007]

According to a first aspect of the present invention, there is provided a fuel exchanger for exchanging fuel in a pressure pipe of a pressure tube reactor, comprising a pressure vessel having a lower head, and an internal structure housed in the pressure vessel. A decontamination ring connected to a high-pressure water supply nozzle penetrating the head and turned around the inner periphery of the lower head, and a plurality of jet cleaning nozzles disposed on the inner diameter side of the decontamination ring. flange Rutotomoni, of the high-pressure water supply nozzles provided a ring nozzle
The above-mentioned object is achieved by providing a detachable closing plate in the device (claim 1). It is preferable that the decontamination ring nozzles are arranged on the lower head in three stages above and below (claim 2).

[0008]

According to the present invention, a decontamination ring nozzle comprising a decontamination ring and a plurality of jet cleaning nozzles connected to a high-pressure water supply nozzle penetrating the lower head of the refueling machine is provided. A high-pressure water pipe is connected to the high-pressure water supply nozzle, and high-pressure water is jetted from a jet cleaning nozzle to remove a clad attached to the internal structure by remote control. For this reason, the surface dose rate at the time of disassembly of the refueling machine is reduced, and the exposure of workers required for cleaning can be reduced. Further, the Rukoto provided closure plate detachably to the flange of the high-pressure water supply nozzle, fitted with a closure plate at the time of refueling, by combining the high-pressure water pipe and high-pressure water supply nozzle to remove the closure plate during cleaning, high pressure water Can be ejected from the nozzle.

Furthermore, the decontamination ring nozzles are preferably arranged in the upper and lower three stages in the lower head , so that the inside of the head can be cleaned over a wide area.

[0010]

1 is a sectional view of a lower head of a refueling machine provided with a decontamination apparatus according to an embodiment of the present invention. An internal structure 3 is accommodated in a lower head 1 of the refueling machine. The decontamination apparatus according to the embodiment of the present invention includes a decontamination ring 12a connected to a high-pressure water supply nozzle 16 penetrating the lower head 1 and turned around the inner periphery of the lower head 1, and an inner diameter of the decontamination ring 12a. A decontamination ring nozzle 12 comprising eight jet cleaning nozzles 12b arranged on the side was provided. The high-pressure water supply nozzle 16 has a detachable closing plate 17 provided on the flange 11 thereof. Further, the decontamination ring nozzles 12 are arranged on the lower head 1 in three upper and lower stages.

FIG. 2 is an enlarged sectional view of the decontamination ring nozzle of FIG. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals. The decontamination ring 12 composed of the decontamination ring 12a and eight jet cleaning nozzles 12b arranged on the circumference of the decontamination ring 12 is fixed to the inner wall of the lower head 1 by bolts with brackets 13. The high-pressure water supply nozzles 16 penetrating the lower head 1 are arranged in three upper and lower stages.

The decontamination ring 12a has a high-pressure water supply nozzle 1
6, the connecting nozzles 15 are attached one by one in the same direction. Between the high-pressure water supply nozzle 16 and the coupling nozzle 15,
In order to facilitate the connection, they are connected by a connecting pipe 14 sealed by an O-ring 19. In order to prevent the connection pipe 14 from jumping outward due to a pressure load when supplying high-pressure water, the connection pipe 14 is connected to the surface of the flange 11 of the high-pressure water supply nozzle 16.
A distance pipe (18) is provided between the pipe ( 14) and an end of the distance pipe (18) is fixed to the flange (11). The decontamination ring nozzles 12 configured as described above are arranged in three stages above, below, and below the lower head 1.

At the time of refueling (during normal use), a closing plate 17 is attached to the high-pressure water supply nozzle 16 to seal the water contained in the refueling machine. After draining the water contained in the refueling machine during the decontamination work, the closing plate 17 is removed, and the high-pressure water supply nozzle 16 in the upper stage, the high-pressure water supply nozzle 16 in the middle stage, and the high-pressure water supply nozzle 16 in the lower stage are sequentially pumped by the high-pressure water pump. Is installed, and washing is performed with a high-pressure water jet. In the embodiment, the decontamination ring nozzles 12 are provided in three stages, but the number of stages may be increased or decreased as necessary.

[0014]

According to the present invention, a decontamination ring is provided in a lower head of a pressure vessel, and a high-pressure water jet is jetted on an internal structure in the pressure vessel while the lower head is attached, thereby producing a high-dose internal structure. Since the cladding on the object surface is cleaned and removed, the exposure dose received during the overhaul work of the refueling machine can be reduced to 1/10 or less as compared with the conventional case.

[Brief description of the drawings]

FIG. 1 is a sectional view of a lower head of a fuel exchanger provided with a decontamination apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the anti-staining ring nozzle of FIG.

FIG. 3 is a configuration diagram showing the entire fuel handling facility of the pressure tube reactor.

FIG. 4 is a schematic configuration diagram of the fuel exchanger in FIG. 3;

FIG. 5 is a diagram showing a cleaning operation of a conventional refueling machine.

[Explanation of symbols]

 Reference Signs List 1 lower head 2 pressure vessel 3 internal structure 5 fuel 6 pressure pipe 11 flange 12 decontamination ring nozzle 12a decontamination ring 12b jet cleaning nozzle 14 connecting pipe 15 connection nozzle 16 high-pressure water supply nozzle 17 closing plate 18 distance pipe 22 Reactor 26 Refueling machine

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21F 9/28 G21C 19/02

Claims (2)

(57) [Claims] 1. A fuel exchanger for exchanging fuel in a pressure tube of a pressure tube reactor, comprising a pressure vessel having a lower head, and an internal structure housed in the pressure vessel, wherein the fuel tank penetrates the lower head. A decontamination ring connected to a high pressure water supply nozzle and turned along the inner circumference of the lower head;
Rutotomo provided decontamination ring nozzle and a plurality of jet cleaning nozzle disposed on the inner diameter side of the decontamination ring
And a removable closure on the flange of the high-pressure water supply nozzle.
A decontamination device for a refueling machine of a pressure tube reactor, comprising a plate. 2. A decontamination apparatus for a fuel exchanger of a pressure tube reactor according to claim 1, wherein the decontamination ring nozzles are arranged in a lower head in three upper and lower stages. Decontamination equipment of furnace refueling machine.