JPH03200000A - Apparatus for reducing internal pressure attached to container with radioactive waste - Google Patents

Abstract

PURPOSE: To widely use the final storage of radioactive wastes by housing an oxidation catalyst which oxides hydrogen with oxygen in the air into water at a prescribed storage temperature with a prescribed treating ability in the transmissive opening of the wall of a container, etc., from the inside to the outside of the container. CONSTITUTION: An internal pressure dropping device is composed mainly of a bowl-shaped pot 1 and is incorporated in the lid 3 of a final storage cask for radioactive waste in the opening 2 of the wall of a container, etc. For this purpose, a connecting ring 4 is welded to the opening 2 from the inside and the pot 1 is screwed in the outer connecting section of the ring 4 from the outside. The clearance between the pot 1 and lid 3 is sealed by putting a packing 6 in the clearance. The inside of the pot 1 into which a catalyst or catalyst pack 7 is inserted has a connecting opening 8 for the inside 9 of the cask and a gas transmissive sintered metallic candle 10 is incorporated in the opening 8. The outside of the catalyst 7 is covered with a wire gauge, steam transmissive plate 11, or a sintered metallic cap.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention reduces the internal pressure of a container containing radioactive waste due to hydrogen generated in the waste, thereby reducing the total hydrogen release from the container. The present invention relates to a device for

[Conventional technology]

Many, weak and moderately radioactive waste filling drums (
In Abfallgebinde), the formation of gases, in particular hydrogen, is in principle based on the reaction of metal components with water, on the one hand, and on the other hand, by the formation of radiolytic gases from the cement/piteumene matrix material. is also possible. This first formation mechanism is particularly important in the case of high-pressure compacted mixed waste. For intermediate and final storage, this formation/release rate per container and unit time is limited so that the container can be designated as final storage capable.

Previously known solutions to the problem suggested limiting the specific activity or, in the case of compressed and mixed waste, careful sorting of the crude waste or rather time-consuming and therefore very expensive vacuum drying. has been done.

A complete screening of the waste introduced into the container, which should be completely free of water, is not possible industrially, ie water exclusion has not been successful in principle.

Therefore, the reactions of many important metals, such as iron-based alloys, with water are thermodynamically possible under all relevant temperature and pressure conditions (6), such as the so-called chikorr-reaction. Happens: 3 Fe + 4 H20= Fe3O4+ 4 H2
Drying of container contents, for example vacuum drying, is very expensive for high throughputs due to long drying times of several days. This is difficult, since this requires very expensive equipment.

[Problem to be solved by the invention]

The object of the invention is, on the one hand, to reduce the overpressure caused by the hydrogen in the container or the filling drum, or to bring it back to zero, but at the same time to significantly reduce the rate of hydrogen release. However, a limiting condition for this task setting is that the level of inspection and container technology should be slightly changed, ie that the industrial implementation of this final storage should be as widely available as possible.

[Means to solve the problem]

(4) To solve this problem, the present invention provides a device of the kind described above, in which hydrogen at storage temperature and oxygen from the blast are added in a permeable opening in the wall of the container or its lid. We propose that an oxidation catalyst that performs oxidation to produce oxidation at a predetermined processing capacity be housed from the inside of the container to the outside.

A particularly advantageous embodiment of this catalyst arrangement can be seen from the features set out in the characterizing part of patent claims 2 and 6.

〔Example〕

The details of the invention will now be explained in detail with reference to the accompanying drawings: As shown in FIG. Incorporated into the lid 3 of the final storage cask
There are n. For this purpose, a connecting ring 4 is welded from the inside to the opening 2, into which the pot 1 is screwed from the outside by means of its outer connecting part 5. The surface between the pot 1 and the lid 3 is sealed by a gasket 6 located therebetween.

The interior of the pot 1, into which the catalyst or catalyst pack 7 is inserted, has a connecting opening 8 to the cask interior 9;
A gas-permeable sintered metal candle 10 is installed therein. To the outside 12, the catalyst 7 is covered by a wire mesh, a water vapor permeable plate 11 or a sintered metal lid.

This structure allows gas to escape from this container or from the waste cask, not shown. The hydrogen produced in each vessel passes through an opening 8 and a sintered metal candle 10, and is conducted through a catalyst 7 where, at ambient temperature, the hydrogen is oxidized by oxygen from the ambient air and converted into water. Become. The catalyst used is a system of noble metals on an inert support, for example palladium on aluminum oxide. During the experiment, a palladium catalyst (Kat, lysator E 221
It has been proven that the ratio P/D - 0.5 (Pd) is suitable.

Due to the oxidation outside the vessel, the oxidation product of hydrogen, water, is excluded from the new reaction. This catalyst, combined with any oxygen present in the air, is more easily consumed by reactions with other components and is therefore no longer available for H2-oxidation. Avoid adding oxidizing agents.

p is suitable.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the apparatus of the present invention. 1... Pot, 2... Opening, 3... Container lid, 4
... Connection ring, 5 ... External connection part, 6 ... Packing, 7 ... Catalyst back, 8 ... Connection opening, 9.
...Container interior, 10...Sintered metal candle, 11.
...Transparent plate, 12... External procedure amendment (method) 1. Indication of the case 1990 Patent application No. 286072, Name of invention 3゜Relationship with the case

Claims (1)

[Claims] 1. A device attached to a container containing radioactive waste for reducing the internal pressure due to hydrogen generated in the waste and reducing hydrogen release from the container, which includes: this container or its lid; Radioactive waste, characterized in that an oxidation catalyst is housed in a permeable opening in the wall from the inside of the container to the outside, which performs the oxidation of hydrogen and oxygen to water at a storage temperature with a predetermined processing capacity. A device attached to a container containing something that reduces the internal pressure. 2. The following characteristics: a) the catalyst pack (7) is present in a bowl-shaped pot (1) screwed or screwed into the opening (2) of the externally sealed container lid; b) the bottom of the pot (1) facing towards the container interior (9) has a permeable opening (8); c) a gas-permeable sintered metal candle (10) is placed within the permeable opening (8); ) is inserted, and d) the catalyst pack (7) is covered with a wire mesh or a water vapor permeable sintered metal plate (11) on the side opposite the sintered metal candle (10) in the pot (1). 2. The device of claim 1, wherein: 3. Pd0.5 on Al_2O_3-support matrix
2. A device according to claim 1, comprising a palladium-catalyst having a weight percent of palladium.