CS259555B1 - Device for electrochemical decontamination of the main shut-off valve body of a nuclear power plant - Google Patents

Abstract

The device is intended for electrochemical decontamination of the main shut-off valve body of a nuclear power plant. Rotating and gear-coupled electrodes mounted on a support frame are driven by a drive unit. Reversal of the electrodes is ensured by a switch. The support frame is clamped to the main shut-off valve body via a sealing ring.

Description

BACKGROUND OF THE INVENTION The present invention relates to an apparatus for electrochemical decontamination of a main shut-off valve body of a nuclear power plant.

So far known methods of electrochemical decontamination, eg by a manually operated electrode, are demanding on time and radiation load of the service personnel. Due to the segmentation and poor access to some surfaces, the inner surface of the main shut-off valve body cannot be sufficiently decontaminated in this way.

Another way of decontamination, e.g. by chemical method, requires a complex heating device of the decontamination solutions to an optimum temperature, it is slow, compared to electrochemical decontamination, a lower decontamination effect is achieved with several times higher volume of liquid radioactive waste.

The aforementioned drawbacks are eliminated by the device according to the invention, the basis of which are the upper and the height-adjustable lower electrode bases which are coupled to each other by a transmission. The electrodes are mounted on the support frame and rotated by the drive unit. Reversing the rotation of the electrodes is provided by a switch controlled by the extreme positions of the upper electrode. At the end of the support frame arms is a sealing ring over which the entire device is clamped to the main enclosed body. There is lighting in the arms of the supporting frame.

The upper electrodes rotating about the vertical axis decontaminate the cylindrical portion and the dividing plane of the main shut-off valve body, the lower electrodes rotating about the horizontal axis decontaminate the sleeves and the spherical portion of the main shut-off valve body, while the active electrode surface follows the decontaminated surface at the same distance thereby it achieves a uniform degree of decontamination and allows the entire inner surface of the main shut-off valve body to be decontaminated with a single filling of the main shut-off valve body with the electrolyte.

The sealing ring makes it possible to fill the main shut-off valve body with the electrolyte above the dividing plane. Height adjustable bottom electrodes allow to eliminate dispersion of manufacturing tolerances! the main shut-off valve body when adjusting the gap between the lower electrodes and the decontaminated surface. The lighting is used to set up the device in the body of the main shut-off valve.

In the accompanying drawing, a device of the invention is shown fitted in the body of the main shut-off valve.

The upper electrodes 1 and the height-adjustable lower electrodes 2 coupled to each other by the transmission 3 are rotatably mounted on the support frame 4, which is supported by the sealing ring 5. The electrodes are rotated by the drive unit 6. In the support frame arms there is a switch 7 and a lighting 8.

Claims (1)

Apparatus for electrochemical decontamination of a main shut-off valve body of a nuclear power plant, characterized in that it comprises upper electrodes (1) and lower electrodes (2) which are coupled by a transmission (3), rotated by the drive unit (6) and rotatably mounted on the support frame (4) ), on the arms of which there is a sealing ring (5), wherein the switch (7) and the lighting (8) are arranged in the arms of the support frame.