JPS59162485A - Maintenance cask - 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 maintenance cask that handles internal equipment of a fast breeder reactor.

[Technical Background of the Invention] Generally, a liquid metal such as metallic sodium is used as a coolant in a fast breeder reactor. This metallic sodium is chemically active and reacts violently with oxygen, water, etc.
A fast breeder reactor is filled with an inert gas called a cover gas to prevent the metal sodium from reacting. Therefore, when handling the in-reactor equipment used in a fast breeder reactor, it is necessary to use a φ container called a maintenance cask to prevent air from crowding inside the reactor. When cleaning the equipment inside the reactor to which the metal has adhered, for safety reasons, it is necessary that the metallic sodium be cooled to room temperature to solidify.

Figure M1 shows such a conventional maintenance cask, and in the figure, reference numeral 1 indicates a cask body that houses equipment 2 to be repaired, such as a control rod upper guide tube. At the lower end of this cask body 1 is a device to be repaired 2.
A cask door valve 3 is provided which forms a passage into the cask body 1 and provides an airtight and shielding partition.

This cask door valve 3 is mounted and fixed on a floor door valve 6 disposed on an equipment through hole 5 formed in a shielding plug 4. A hoisting device 7 is disposed at the upper end of the cask body 1 to perform attachment/detachment and lifting/lowering operations of the equipment 2 to be repaired. The hoisting device 7 is formed from a drum 8 driven by a drive mechanism, and a lifting tool 10 disposed at the lower end of a wire 9 wound around the drum 8.
0 is a device through hole 5 when the maintenance target device 2 is inserted into and removed from the furnace.
An O-ring 12 is disposed in close contact with the upper end opening 11 to maintain airtightness.

The maintenance cask constructed in this manner is used as described below.

That is, first, a floor door valve 6 is arranged above the equipment through hole 5 in which the equipment 2 to be repaired is arranged, and this floor door valve 6
The cask door valve 3 of the maintenance cask is placed and fixed on top, and the atmosphere inside the cask main 1 is replaced with an inert gas. In this state, the cask door valve 3 disposed on the maintenance cask and the floor door valve 6 disposed on the shielding plug 4 are opened, and the hoisting device 7 is driven to move the equipment 2 to be maintained from the equipment through hole 5. The bow 1 is extracted upward and housed in the cask body 1. During this work, the inside of the maintenance cask (in order to prevent the reactor cover gas containing radioactive nuclides from entering), and to cool and solidify the molten metal sodium adhering to the equipment to be repaired 2, was removed from the outside of the maintenance cask. Inert gas at room temperature is supplied into the cask body 1 from the argon gas supply system provided and is blown down into the furnace.After this,
The cask door valve 3 and floor door knob 6 are closed, the maintenance cask is removed leaving the floor door valve 6 on the shielding plug 4, and maintenance or After being transported to the waste treatment building and cleaned and dried in a high-level equipment cleaning tank, it is stored in the underwater solid waste temporary storage pool. (In this case, after storing the repaired equipment 2 in the cask main body 1, this maintenance cask is placed on the floor door valve 6, and the maintenance is carried out by following the procedure reverse to the above-mentioned removal procedure. Equipment penetration 15 through equipment 2 to be repaired
Insert it into the furnace.

[Problems with Background Art] However, the maintenance cask configured as described above has the following problems.

(1) It is necessary to continue flowing inert gas at room temperature into the furnace in order to cool and solidify the metallic sodium adhering to the equipment to be repaired 2. As a result, the amount of waste gas generated increases and the adhering metallic sodium increases. There is a problem in that it is impossible to remove the maintenance cask until it is cooled and solidified.

(2) Since the equipment 2 to be repaired that has undergone maintenance is inserted into the furnace at room temperature, vapor deposition and adhesion of sodium chloride may occur on the equipment 2 to be maintained, which may cause malfunction of the equipment 2 to be maintained. There is.

(3) There is a risk that moisture may remain in the cask body 1 due to maintenance and waste treatment building work, and if this moisture remains on the equipment to be repaired [2], if it is inserted into the furnace with this moisture still attached, There is a risk that the equipment 2 to be repaired may be damaged due to the sodium-water reaction.

(4) Metallic sodium that dripped into the device through hole 5 when the device 2 to be repaired was pulled out was cooled and solidified near the opening of the device through hole 5, and this cooled and solidified metal sodium was repaired in the device 2 to be repaired. There is a risk that the O-ring 12 disposed on the lifting device 10 of the hoisting device 7 may be damaged and an airtight leakage accident may occur. .

(5) In order to blow down the inert gas at room temperature into the furnace, convection occurs in the furnace due to the temperature difference, which promotes the generation of sodium mist from the coolant liquid level in the furnace, and this sodium mist is transferred to the shielding plug. 4 and may cause malfunction of the shielding plug 4.

LObject of the Invention The present invention has been made to solve the problems of the conventional art, and is aimed at cooling the liquid metal attached to the furnace equipment housed in the maintenance cask when the furnace equipment is removed from the furnace. By heating the furnace equipment housed in the maintenance fusk when it is inserted into the furnace, various accidents caused by liquid metal can be prevented. The aim is to provide a maintenance cask.

[Summary of the Invention] That is, the present invention provides a maintenance 3 cask for removing the in-core equipment installed in a liquid metal fast breeder reactor and inserting it into the reactor. Collection i
a cask body, a hoisting device disposed at the upper end of the cask body for attaching/detaching and lifting/lowering the in-furnace equipment, and a hoisting device disposed at the lower end of the cask body for moving the in-furnace equipment into the cask body. A cask door valve that forms a passage and provides an airtight and shielding partition, and a cask door valve that cools liquid metal that adheres to the furnace equipment housed in the cask body when the furnace and internal equipment are removed from the furnace. and a heating device that heats the furnace equipment housed in the cask body when the furnace equipment is inserted into the furnace.

[Embodiment 1 of the Invention] Details of the present invention will be described below with reference to an embodiment shown in the drawings. Note that in FIG. 2, parts common to those in FIG. 1 are designated by the same reference numerals, and explanations thereof will be omitted.

In the figure, reference numeral 13 indicates a cooling device. Opening/closing valve 1 inserted in order from upstream to 14
5, on-off valve 16, paper trap 17, cooler 18,
Dehumidifier 19, blower 20, and on/off valve 21 to 41
It is equipped with a cooling base 18 and a paper trap 17.
It branches from between and is connected upstream of the C on-off valve 21.

A piping 23 into which an on-off valve 22 is inserted is provided.

In the figure, reference numeral 24 indicates a heating device arranged in parallel to the cooling device 13, and this heating device 24 has one end connected between the on-off valve 15 and the on-off valve 16 of the cooling pipe 14, and the other end. A heating pipe 25 whose end is connected between the air blower 120 and the on-off valve 21, and an on-off valve 26, a heater 27, and an on-off valve 28 arranged in this heating pipe 25 in order from the on-off valve 21 side.
The heater 29 of the heater 27, which has a spiky structure and is disposed surrounding the heating pipe 25, is surrounded by a heat insulating material 3o.

In the figure, reference numeral 31 indicates an argon gas supply pipe installed in the argon gas supply system. This argon gas supply pipe 31 is connected upstream of the closing valve 26 of the heating pipe 25, and an on-off valve 32 is arranged has been done. Note that a waste gas nozzle 33 and a cleaning agent nozzle 34 are arranged at the upper part of the cask body 1.

The maintenance cask configured as described above has the first
Like the conventional maintenance cask shown in the figure, it is placed on a floor door valve 6 disposed on a shielding plug 4, and after the atmosphere inside the cask body 1 is replaced with argon gas, which is an inert gas. , the equipment 2 to be repaired is pulled out from the equipment through hole 5 by the hoisting device 7, and is housed in the cask body 1. During this storage operation, in order to prevent the in-furnace cover gas containing radioactive nuclides from rising into the cask body 1, argon gas is supplied from the argon gas supply system into the cask body 1 through the heating device 24 at a pressure higher than the in-furnace cover gas pressure. Gas is supplied and blown down into the furnace.

That is, at this time, the on-off valves 32.26.28.15,
Cask door valve 3, floor door valve 6 open, on/off valve 2
1.16 is closed, the heater 27 is activated, and the blower 20 is stopped. Then, the argon gas from the argon gas supply system passes through the on-off valve 32.26 to the heater 2 of the heating pipe 25.
7, flows into the cask body 1 through the #J closing valve 28.15, and is blown down into the furnace.

After the equipment 2 to be repaired is stored in the cask body 1, the cask door valves 3 and 6, which had been open, are closed, and the open/close valves 32, 26, 28, and 15 are closed, respectively, and the heater 27 is closed. Operation is stopped. After this, the on-off valve 21
．． 15.16, the on-off valves 32, 26, 28, and 22 were closed, and the blower 20 installed in the cooling device 13 was activated, causing particles to adhere to the equipment 2 to be repaired housed in the cask body 1. Metallic sodium is cooled and solidified.

That is, the argon gas contained in the cask body 1 passes through the on-off valves 15 and 16 and flows into the paper trap 17, is cooled by the cooler 18, and passes through the dehumidifier 19, the air blower 120 and the on-off valve 21. Metal sodium circulating within the cask body 1 and attached to the equipment 2 to be repaired is cooled. Thereafter, the equipment 2 to be repaired is transported to a maintenance and waste treatment building while being housed in the maintenance cask, where it is subjected to processing such as cleaning, repair, and drying. Then, the equipment 2 to be repaired thus repaired is again accommodated in the maintenance cask and placed on the floor door valve 6 of the shielding plug 4. Note that during this period, the on-off valves 32, 21, and 16 are opened, and the on-off valves 1
5.26.28.22 are opened and the blower 20 and heater 27 are activated.

That is, the argon gas in the cask body 1 passes through the on-off valve 22 disposed in the branch pipe, the cooler 18, the dehumidifier 19, and the blower 20, and then passes through the on-off valve 2 disposed on the heating pipe 25.
After passing through the six heaters 27 and the on-off valves 28 and 25, the air is recirculated into the cask body 1 and preheats the equipment 2 to be repaired. After preheating the equipment 2 to be repaired, the air blower 120 is stopped, the cask door valve 3 and the floor door valve 6 are opened, and the on-off valves 32, 15, 26, .
28 is opened, on-off valves 21, 16, and 22 are closed, and the heated argon gas is blown down into the furnace.

The following table summarizes the opening/closing operation status of the opening/closing valve 32.21.15.16.26.28.22, cask door valve 3, floor door valve 6, ventilation #M20, and heater 27 during blowdown, cooling, and preheating. indicate. In this embodiment, the cooling device 13 and the heating device 24 are controlled by a control device (not shown).

(Hereafter the margin) (Hereafter the margin) In the maintenance cask configured as described above, the metal that adhered to the maintenance target equipment 2 during the time when the maintenance target equipment 2 is removed from the furnace and cleaned in the waste treatment building. Cooling and assimilation of sodium can be easily performed by operating the cooling device 13, and the flow rate of feed gas and waste gas blown down into the furnace can be reduced.

In addition, since the removal, transportation, and installation of the maintenance cask can be carried out in parallel with the cooling and assimilation of metallic sodium, the work in the upper part of the furnace can be shortened. Furthermore, before the repaired equipment 2 is returned to the furnace, it is possible to transport and install it in parallel with the work by preheating and drying adhering moisture, which makes the sodium-water reaction effective during storage in the furnace. It is also possible to prevent evaporation and adhesion of metallic sodium to the maintenance target equipment 2.

By blowing down the heated argon gas into the furnace when the equipment 2 to be repaired is roughly inserted into the furnace, the metallic sodium dripping onto the inner surface of the equipment through hole 5 can be easily melted. Damage to the ring 12 and the like can be prevented.

Moreover, this makes it possible to prevent the generation of sodium mist in the furnace, and to smoothly drive the shielding plug 4.

[Effects of the Invention] As described above, according to the maintenance cask of the present invention, liquid metal adhering to the furnace equipment housed in the maintenance cask is cooled when the furnace equipment is removed from the furnace, and Since the furnace equipment housed in the maintenance cask is heated when the furnace equipment is inserted into the furnace, various accidents caused by liquid metal can be prevented from occurring.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing a conventional maintenance cask.
FIG. 2 is a longitudinal sectional view showing a maintenance cask according to an embodiment of the present invention. 1... Cask body 2...
・・・・・・Equipment to be repaired 3・・・・・・・・・・・・
・Cask door valve 6...! ......Floor door valve 7...Hoisting device 13...Cooling device 18...
......Cooler 20...Blower 24...Heating device 31...
・・・・・・Patent attorney representing argon gas supply piping
Satoshi Suyama - Figure 1

Claims (3)

[Claims] (1) In a maintenance cask for removing reactor equipment installed in a liquid metal fast breeder reactor to the outside of the reactor and inserting it into the reactor, - a cask body that houses the reactor equipment, and this cask body; a hoisting device disposed at the upper end for attaching/detaching and lifting/lowering the in-furnace equipment; and a hoisting device disposed at the lower end of the cask body for forming a passage for the in-furnace equipment into the cask body for airtightness and shielding. a cask door valve that partitions the furnace equipment; a cooling device that cools liquid metal adhering to the furnace equipment housed in the cask body when the furnace equipment is removed from the furnace; A maintenance cask comprising a heating device that heats the furnace equipment housed in the cask body when inserted into the furnace. (2) The cooling device is composed of a cooling pipe that opens at the bottom of the cask body at one end and opens at the top of the cask body at the other end, and a cooler and a blower inserted into the cooling pipe. Maintenance cask described in scope 1. (3) The heating device includes a heating pipe whose one end is connected to the lower part of the cask body and the other end is connected to the upper part of the cask body;
The maintenance cask according to claim 1 or 2, comprising a heater disposed in the heating pipe.