JPS5885198A - Method and device for removing metal corrosion product of contaminated material - 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 The present invention relates to a method for removing metal corrosion products that adhere to reactor fuel bundles used, for example, in boiling water nuclear power plants during operation.

Metals leached into the primary cooling water from the reactor-subsystem piping cape may adhere to the fuel cladding tubes and block the coolant flow path when they enter the reactor. Furthermore, the radioactive metal corrosion products (hereinafter referred to as crud) are returned to the coolant and deposited in various places, raising the radiation level and increasing radiation exposure during work.

It is also considered difficult to handle in the reprocessing process.

Traditionally, it takes from one fuel bundle to remove this crud.
After removing the fuel channel, a method is used in which a jet of water is injected and the water is passed through a filter to collect the crud. However, this method only removes the fuel rods from the outer periphery of the fuel bundle from the bottle, and it also requires removing the channels from the bundle, which has the drawback of lengthening the process.

Therefore, the present invention has been devised to eliminate these drawbacks, and to provide a method for removing metal corrosion products from a contaminated object, which does not require removing the channel and easily removes the crud from the entire fuel bundle. With the goal.

The present invention deals with metal corrosion that adheres to contaminated objects due to the impact when steam or air is pumped into a container in which contaminated objects are stored and isolated, and the steam or air is crushed. It is an object of the present invention to provide a method for removing metal corrosion products from dirt contaminants, which removes the products.

An embodiment of the present invention will be explained below with reference to the drawings. Fig. 1 shows a fuel collector of a boiling water reactor, and a fuel bundle 1 bundles several tens of fuel rods 1a.
Its upper and lower parts are fixed by an upper tie plate 1b and a lower tie plate 1e. Although the fuel nozzle 1 is surrounded by a channel 1d, crud adheres to the surface of the fuel bundle 10. This crud is removed by a removing device shown in FIG. A container 2, a pipe 3 and a pump 4 connected to the lower part of the container 2, a pipe 5, an electric valve 6, and a filter 7 connected in sequence to the upper part of the container 2, and a steam pipe connected in the middle of the pipe 3. It consists of piping 8, a solenoid valve 9, and a steam generator 10.

Next, the removal method of the present invention will be explained. First, the lid 2a of the container 2 is opened and the fuel bundle 1 is installed inside the container 2. Close the lid 2- and secure it with bolts, etc. Next, the pump 4 is started at the same time as steam is generated from the steam generator 1o, and a water flow containing the steam 1 is created in the fuel bundle 1 as shown in FIG. When the electric valves 6 and 9 are closed after a certain period of time, the pressure inside the container 2 increases due to the discharge pressure of the pump 4, and the steam chamber 11 collapses. The impact at this time causes the cladding on the fuel rod 1 to peel off.

Next, when the electromagnetic valves 6 and 9 are opened, the separated crud is collected by the filter 7 through the pipe 5 by a water flow.

By changing the timing of opening and closing of the solenoid valve 6.9, the position where the steam can collapse is changed and the fuel bundle l is
The cladding can be removed over the entire length of the cladding.

lI shown in the drawing! In the embodiment, a case has been described in which the crud adhering to a fuel bundle is removed, but the present invention is not limited to this and can be applied to any contaminated object.

As described above, the present invention makes it possible to completely decontaminate crud attached to contaminated objects such as fuel bundles, saves time since there is no need to remove the fuel channel, and uses water vapor to decontaminate the fuel. It does no harm to. The same effect can also be obtained by using DK raw air instead of steam.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a fuel bundle, Fig. 2 is a configuration diagram showing an apparatus to which the method for removing metal corrosion products from contaminated objects of the present invention is applied, and Fig. 3 is a state of water vapor infiltration according to the present invention. FIG.

Claims (3)

[Claims] (1) After isolating a contaminated object such as a fuel bundle of a boiling wood reactor in a container, a steam slough is sent in and the pressure of the container is adjusted to collapse the steam slough;
A method for removing metal corrosion products from a contaminated object, characterized by removing metal corrosion products attached to the contaminated object due to impact when crushed. (2) A method for removing metal corrosion products from a contaminated object as set forth in claim 1, characterized in that an air inlet is used instead of a steam inlet. (3) A container for storing and isolating contaminated objects such as fuel bundles of boiling water reactors, a generator and its system for sending steam or gas into the container, and a system for sending steam or gas into the container. A device for removing metal corrosion products from a contaminated object, consisting of a device for increasing the pressure inside the container to crush the trapped steam or gas container.