JP2003500670A - Fuel element purification and / or decontamination equipment - Google Patents

Abstract

(57) Abstract: An apparatus for purifying and / or decontaminating a fuel element (4) is provided. To accommodate the fuel element (4), a purification and / or decontamination solution feed pipe (5), a discharge pipe (6) and a tank (1) having a holder (8) for the fuel element (4) are provided. And place it in the water in the fuel element storage tank. More effective purification and decontamination is possible by insulating the tank from the outside, installing an ultrasonic vibrator in the tank, or reversing the flow direction of the purification or removal solution in the tank. Become.

Description

Detailed Description of the Invention

[0001]   The present invention relates to a device for purifying and / or decontaminating a fuel element.

The components of the primary circulation path of a nuclear power plant are cleaned or decontaminated by chemical treatment at timed intervals. The cleaning or decontamination solution then comes into contact with the structural member to be cleaned. This solution is then clarified.

Purification of fuel elements has not yet been proposed. If the deposits impede the flow through of the coolant, then the fuel element has been replaced.

An object of the present invention is to provide a device capable of simply and reliably purifying or decontaminating a fuel element.

This object is solved according to the invention by providing a tank with a feed pipe for the cleaning or decontamination solution and an exhaust pipe and a holder for the fuel element in order to contain the fuel element.
A plurality of feeding and / or discharging pipes may be provided.

Fuel elements can be arranged in such a tank. The element is then enclosed relatively narrowly by the tank, and a small amount of solvent is sufficient because of the relatively small volume of the tank.

For example, this tank is designed for seven fuel elements. That is, one tank can purify seven fuel elements at the same time. Further, the purification may be performed a plurality of times sequentially. It is also possible to process a few fuel elements in the tank, for example a single fuel element.

The device according to the invention achieves the advantage of being able to treat a certain number of fuel elements quickly and reliably with relatively little cleaning and decontaminating solution.

For example, the tank is formed so that it can be installed in water in the fuel element storage tank. In that case, the fuel element is placed in the tank directly from the reactor pressure vessel by means of the originally existing equipment. There, the fuel element is first surrounded by the water in the storage tank. After closing the tank,
The fuel element will come into contact with the solution required for cleaning or decontamination via the feed and exhaust pipes. Placing the tank within the fuel element storage tank allows the fuel element to be processed very easily.

The tank is insulated from the outside, for example. This insulation can be achieved by a double-walled structure with a well evacuated gap. That is, the tank can be formed similar to a thermos container. Due to the heat insulation, the high temperature required for purification or decontamination can be maintained sufficiently inside the tank. That is, in the ordinary purification method, the temperature up to 95 ° C. necessary for the chemical reaction is general. On the other hand, in the water of the fuel element storage tank, usually 3
The temperature is 0 to 50 ° C. Therefore, the high temperatures required inside the tank cannot be maintained or are hardly maintained without insulation.

Inside the tank, for example, at least one ultrasonic vibrator is arranged. However, typically a plurality of ultrasonic vibrators, for example 18 ultrasonic vibrators, are provided for the seven fuel elements. These ultrasonic vibrators achieve the advantage of better ultrasonic removal of fuel element deposits in the cleaning or decontamination solution.

The tank has a lid that can be rotated, for example, by remote control. This has the advantage that the tank can be opened in a simple manner and then just as easily reclosed after the fuel element has been inserted.

The feed pipe can be connected, for example, to the end face of the fuel element inside the tank, and the discharge pipe can likewise be connected to the opposite side of the fuel element inside the tank. In this way, the individual fuel elements can flow through in a targeted and uniform manner.

These conduits start, for example, from the pipe fittings of the tank and extend into the interior of the tank. In this way, damage to the conduit can be avoided.

From the feed line, for example, individual feed lines for all fuel elements emerge, in which case all individual feed lines can be separated separately. Therefore, one fuel element or a group of fuel elements can be processed as desired.

The flow direction of the cleaning or decontaminating solution can be reversed, for example by exchanging the functions of the feed pipe and the discharge pipe. That is, the solution is supplied into the original discharge pipe and discharged through the original supply pipe. This has the advantage of improving the cleaning or decontamination of the fuel element. That is, after the first treatment is performed, if the solution flows in the opposite direction during the second treatment, it is possible to better remove significant deposits.

This reversal of the flow direction can be carried out by using a suitable conduit with a blocking plug or by transferring the solution feed pump to another conduit.

A conventional decontamination or purification device, for example having a filter or the like, may be installed in the discharge pipe of the tank in order to suppress contamination. These devices can be attached to other tubes, such as pumps for changing the flow direction.

With the device according to the invention, in particular the advantage of being able to purify fuel elements can be achieved for the first time, and the already existing devices of nuclear power plants, for example fuel element storage tanks and fuel element exchangers, can be used.

A purification and / or decontamination device for a fuel element according to the present invention will be described in detail below with reference to the drawings.

The tank 1 can be arranged in the fuel element storage tank. Therefore, the tank 1 has a bottom 2 for easy installation in the fuel element storage tank. The upper part of the tank 1 is closed by a lid 3 which can be rotated by remote control. Within the tank 1 there is a holder 8 for containing the fuel element 4. In this special holder 8, for example, seven fuel elements 4 (FIG. 2) can be stored. The feed pipe 5 penetrates the wall surface of the tank with a short joining pipe and reaches the fuel element 4.
A specific individual feed pipe 5a may extend from the feed pipe 5 to each fuel element 4. To the opposite ends of the fuel element 4 is connected a discharge pipe 6 which also penetrates the tank wall with a short joint pipe. A pump for a purification or decontamination solution (not shown) is connected to the feeding pipe 5. A decontamination device (not shown) may be connected to the discharge pipe 6 together with, for example, a filter. The flow direction can be changed by exchanging the pump and the decontamination device. Up to 18 ultrasonic vibrators 7 are arranged in the tank to assist the cleaning action.
Six ultrasonic vibrators 7 are arranged around the fuel element 4 (FIG. 2) distributed in three planes (FIG. 1). The ultrasonic waves of the ultrasonic vibrator 7 improve the deposit removal performance of the fuel element 4.

[0022]   The depicted apparatus allows up to seven fuel elements to be simultaneously purified or decontaminated.

[Brief description of drawings]

[Figure 1]   FIG. 3 is a vertical sectional view of a fuel element cleaning tank according to the present invention.

[Fig. 2]   Sectional drawing which cut | disconnected the tank of FIG. 1 along the II-II line.

[Explanation of symbols]

  1 tank   2 bottom   3 lid   4 fuel elements   5 Decontamination solution feed pipe   5a Individual feeding pipe   6 discharge pipe   7 Ultrasonic vibrator   8 holder

Claims (9)

[Claims] 1. A device for purifying or decontaminating a fuel element (4), comprising:
A tank (1) having a feed pipe (5) for the cleaning and / or decontamination solution, a discharge pipe (6) and a holder (8) for the fuel element (4) to accommodate Fuel element cleaning and / or decontamination equipment. 2. Device according to claim 1, characterized in that the tank (1) is arranged in water in a fuel element storage tank. 3. The tank (1) is insulated from the outside.
Or the device according to 2. 4. At least one ultrasonic vibrator (7) inside the tank (1).
The device according to claim 1, wherein the device is arranged. 5. Device according to one of the claims 1 to 4, characterized in that the tank (1) has a lid (3) rotatable by remote control. 6. A feed pipe (5) is connected to the end face of the fuel element (4) inside the tank (1), and a discharge pipe (6) inside the tank (1) opposite the fuel element (4). Device according to one of the preceding claims, characterized in that it is connected on the side of the position. 7. For each fuel element (4) from a feed pipe (5) to an individual feed pipe (
Device according to one of the preceding claims, characterized in that 5a) emerges and each individual feed pipe (5a) can be shut off separately. 8. The flow direction of the cleaning or decontaminating solution is determined by the feed pipe (5) and the discharge pipe (6).
8. It is possible to reverse by exchanging the function of).
The device according to claim 1. 9. Device according to claim 1, characterized in that at least one of a decontamination device, a purification device and a filter is installed in the discharge pipe (6).