JPS6244700A - Radioactive waste vessel - 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] [Field of Application of the Invention] The present invention relates to a container for radioactive waste, and in particular to a radioactive waste container suitable for removing water from the container after filling the container with waste in water. It is related to.

[Background of the invention]

Solid waste such as metal and concrete from facilities handling radioactive materials such as nuclear power plants is stored in containers and then transferred to a designated storage location for storage. The conventional requirements for this waste container are to prevent the leakage of radioactivity to the outside, and to provide a shielding effect to reduce the dose rate on the surface of the container when storing medium to high level radioactive waste. The three points are that it is durable enough to allow the radioactivity contained in the waste to decay. To satisfy such items.

For example, more containers have been proposed than before.

Patent 57-143416. This is patent application No. 58-142403. However, when targeting control rods and reactor internals, which are high-level radioactive waste, in addition to the three necessary items above, functions for draining water from the container and drying the interior are required. This is because high-level waste has a high specific radioactivity, so if it is stored in a container in the air, the air dose rate will increase and the radiation exposure of workers will increase significantly. It is desirable to remove the container from the water and transport it to a waste storage area; simply closing the lid will leave water in the container, which will accelerate corrosion of the container.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a waste container suitable for solving the above-mentioned disadvantage of water remaining in the container.

[Summary of the invention]

The present invention facilitates draining the water remaining in the container and drying the container by providing the container with drain holes and air holes that do not affect the shielding effect.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. This is a case where the present invention is applied to the dismantling of reactor internals accompanying the decommissioning of a nuclear power plant. When dismantling the reactor internals, remove the lid of the pressure vessel 1, fill the fuel pool 2 with water, and carry out the disassembly work underwater to prevent radioactivity from scattering and to protect workers from the water's shielding effect. reduce the amount of radiation exposure. The disassembly procedure is to first remove the metal fittings of removable equipment using a manipulator, and then put them through water into the fuel pool 2.
Transfer to. For equipment that cannot be removed, the joints are cut by plasma arc and one piece of equipment is transferred to the fuel pool 2. As shown in Fig. 2, the waste container 3 has a plate thickness of 30Ql.
It is a cast steel container with an internal space rln! Yo 0. Cubic,. Four, I say. S: o container. 1) Remove the lid and submerge it in the fuel pool.

The longest equipment in fuel pool 2 should be 90cm.
Cut into small pieces using a plasma arc. The cut pieces are stored in a container 3 using a manipulator. after that.

Lower the lid 4 with the crane 5, tighten the four bolts 6 with a manipulator, and seal the container.Next, use the four hanging fittings 7 to lift the container with the crane 5, take it out of the water, and place it on the floor. put it on.

This container 3 is provided with a drain hole 8 and an air hole 9. Each hole has two bends at right angles so as not to impede the shielding effect of the container, and the structure is such that the radiation that enters the hole never collides with the wall and escapes to the outside. The details of the drain hole are shown in FIG. 3, where the inlet 10 is located on the floor of the container and is bent twice at right angles, and the outlet 11 is oriented horizontally.

The structure of the outlet 11 is a joint that is normally closed and opens when connected to the other pipe, and has a thread on the outside, and the pipe diameter is 3. /8B, and there is a slight downward slope from the inlet 1o to the outlet 11, so water does not accumulate in the middle.The air hole 9 is the same as the drain hole 8, except that it is provided on the wall at the top of the container. It has a structure of Figure 4 shows a flow diagram when piping is connected to the container on the floor. First, 3-way valve 12
By operating steps 13 and 13, the surrounding air flows from air hole 9 to container 3.
First, water remaining in the container 3 is dried so that the water inside flows down into the fuel pool 2 from the drain hole 8 by the action of gravity. For this reason, the three-way valves 12 and 1
3 to let dry air in through the air hole 9 and out through the drain hole 8. The humid air leaving the drain 8 is heated to 80 DEG C. by a heater 16 using a blower 15 after its moisture is removed by a dehumidifier 14, and then supplied to the container 3 again.

The condensed water kept in the dehumidifier 14 is continuously measured by a differential pressure gauge, and when there is no increase, the operation of the blower 15 is stopped and the valve 17 is opened to return it to the fuel pool by gravity. After removing the piping for the drain hole 8 and air hole 9, a plug with an internal thread is attached to improve sealing performance. Thereafter, the crane 5 is transferred to a trailer and transported to a storage location. According to this embodiment, there is an effect that the moisture inside the container can be easily removed.

〔Effect of the invention〕

According to the present invention, since the water inside the container can be removed, corrosion of the container can be suppressed.

[Brief explanation of the drawing]

Figure 1 is a layout diagram showing the location of the waste container during reactor dismantling, Figure 2 is a structural diagram of the waste container, Figure 3 is a detailed view of the exit part of Figure 2, and Figure 4 is water removal. It is a flow diagram of time. 3...Waste container, 8...Drain hole, 9...Air hole.

Claims (1)

[Claims] 1. A radioactive waste container characterized by having a hole in the container wall that corresponds to a hole when the inlet and outlet are connected in a straight line.