DD204173A1 - DEVICE FOR THE LEAKAGE TESTING OF NUCLEAR FUEL ELEMENTS - Google Patents

Abstract

The device for leakage testing of nuclear fuel elements is used to distinguish dense and defective, in particular spent fuel assemblies of a nuclear reactor plant. The object of the test device is to ensure a tightness control of spent nuclear fuel elements stored for a relatively long time before their removal from the reactor system or before their storage in the interim storage facility.The production-related leaks in the upper area of nuclear fuel elements prevent a complete detection of the gas volume excluded by a Zwischenstueckes between gripper head of the manipulator rod and the nuclear fuel element and wrapping the same by a container. The sealing of the intermediate piece and the upper region of the nuclear fuel element within the container takes place by means of Blaehkoerpern, which can be expanded by compressed air. The spigot attached to the container allows both a water restriction from the nuclear fuel element as well as the sample gas transport to the analyzer. Another closable nozzle is used for havariemaessigen venting.

Description

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Title of the invention

Apparatus for checking the durability of nuclear fuel elements

Field of application of the invention

The invention relates to a device for leak testing of nuclear fuel elements (fuel elements), in particular τοπ spent fuel elements-

Characterization of the known technical solutions

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The state of the art corresponds to processes in which the escape of characteristic fission products from defective fuel elements is accelerated by pressurisation (DE-OS 2 249 721) or heating (DE-OS 2818782) or the ratio of active noble gas isotopes is determined (DE). OS 2603031) * These methods "are only applicable" as long as the activity of the characteristic fission products has not yet subsided ".

Furthermore, methods are known, ¹ in which by temperature measurement at the.Stabenden of the fuel elements by means of infrared temperature measurement (DT-OS 2314650) or ultrasonic pulse echo method (DS-OS 2642156) GB-PS 1541 761, DE-OS 2817859) Defects are displayed in the fuel assemblies. However, these procedures are very

manoeuvrable and require pivoting about 180 ⁰ C or dismantling of fuel, which is not possible with VVER fuel assemblies.

Finally, a method is known in which by residual heat development after removal of the coolant (DD-WP 106731) fuel assembly leaks can be detected. This method is applicable in principle for the leak control of spent fuel assemblies of a 440 MW pressurized water reactor. However, the described device is not feasible for technological reasons, since, resulting from the locking technology of conventional Umlademaschinen, the container described can not be coupled directly to the gripper bar and provided for sealing the container in the coupling container head cassette cuff whose tight sheath not guaranteed ,

Object of the invention

The object of the invention is to ensure, by means of a simply executed device, a check of the tightness of the spent fuel elements, mainly after their longer storage time, if necessary for further treatment of the fuel elements for their removal from the reactor plant or for their intermediate storage.

Explanation of the essence of the invention

The technical problem to be solved is to include the production-related leaks of nuclear fuel elements, especially in their upper area, which are without adverse effects for use in the nuclear reactor-r, such that the displacement of the water column for testing after , the dry procedure in the cassette is ensured and the complete detection of the gas volume is not hindered.

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This is inventively achieved in that 'an intermediate piece is coupled between rapier head of the manipulator rod and fuel assembly · The intermediate piece and the upper part of the fuel assembly are enveloped by a container that ensures the tight seal by inflated by compressed air inflatable body. On the container, a nozzle is attached, which is used both to displace water from the fuel assembly and to transport the sample gas sum analyzer. Furthermore, a closable Havariestutzen is arranged in the container,

embodiment

The invention will be explained in more detail below on an exemplary embodiment. The figure shows the device in section in working position. The fuel element (4) coupled via the gripper head (1) of a manipulator rod (2) (for example the gripper bar of the transhipment machine or separate gripper bar of a trolley) and an intermediate piece (3) becomes so far into a container (5) a holder (6) is attached, pulled, that the upper Blähkörperdichtung (7) of the container (5) at the upper end of the intermediate piece (3) and the lower Blähkörperdichtung (3) in height of the fuel rod ends (9) of the fuel assembly (4) , located below the leaky fuel jacket sheaths (10). Thereafter, via the compressed gas line (11) in the upper and lower Blähkörperdichtung (7; 3) to the complete or sealing spread compressed gas preferably compressed air is fed.

Subsequently, via the compressed gas line (12) and the opening (13) in the downwardly open intermediate piece (3), the displacement of the water from the interior of the fuel assembly (4), while the ride height of the water via a Höhenstands- or, pressure gauge, not shown controlled. After switching off the compressed air is at

Presence of defective fuel rods (9) in the fuel assembly (4) by, the rising water level with z. B. Kr-85 enriched air via an unillustrated valve system, which guarantees a separation of the compressed gas line (12) in Meßgas- · compressed gas line, also led to Uachweisgerät also not shown and analyzed there. For safety reasons. ·. In the intermediate piece (3) for measuring the heat radiation of the dried fuel element (4), an infrared sensor (14) was enclosed, which can be swiveled away via the stationary contact (15) on the intermediate piece (3) and via the electrically insulated supply leads (16) Contact receiver (17) is coupled. Furthermore, a fast flooding of the container (5) is possible for special cases of operation via the so-called emergency air line (18).

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Claims (2)

- 5 SrfindungsansOruche 1. A device for leak testing of nuclear fuel elements (Brenneleaienten), in particular of spent fuel after the dry process, wherein the fuel assembly is gripped by a suitable manipulator, characterized in that between gripper head (1) of the manipulator rod (2) and fuel assembly (4) an intermediate passage provided with a passage (13). piece (3) is coupled, and a, intermediate piece (3) and upper part of the fuel assembly (4) enveloping container (5) is arranged for the tight seal by inflatable body (7, · 8), which are spread by means of compressed air, and on the container (5) has a nozzle (12) is attached, both the water displacement from the fuel assembly (4) as well as the transport of the measuring gas to the analyzer ensures. 2. Device according to item 1, characterized in that in the container (5) a closable Havariestutzen (13) is arranged. For this 1 page drawing r «nn ^ QQO * ΠΠ0 88 * 7