DE1901784A1 - Dry reprocessing ceramic nuclear fuel - waste - Google Patents

Abstract

Dry reprocessing ceramic UO2 nuclear fuel waste To improve the microhomogeneity of the sintered dioxide power, as in 1667851, it is passed through a cylindrical screen with a rotating hammer mill inside. The mesh size of the screen may be 63 to 200 mu m but preferably 100 mu m.

Description

Process for the dry processing of ceramic UO2 nuclear fuel scrap.

Addition to the patent. (Registration P 16 67 851.6) During the implementation of the process forming the subject of the main patent has shown that the mixing of the finely divided scrap powder, which tends to form agglomerates with the U02 starting powder in any mixer to achieve good macro homogeneity leads to the microhomogeneity of the mixture due to the formation of larger agglomerates (> 150 / u) left to be desired in certain cases when mixing the components leaves.

This insufficient microhomogeneity is reflected in the ground pellet noticeable through the appearance of larger pores with a diameter of several hundred. These Pores are created by the different sintering behavior of soot powder agglomerates in the surrounding starting powder.

Pores of the size mentioned in the sintered body are not created in any case tolerated, eo that, depending on the speciiication, the reject rates can be unsustainable reachable.

It has now been found that the disadvantages described are thereby eliminated prevent the uranium dioxide powder produced from being subjected to sieving will. This passport screening is preferably carried out in a. Sieve with one mesh size from 63 µ to 200 µ.

Carrying out the sieving process is also essential Simplification of the previous process step, since it is now being introduced the powder components in a simple free-fall mixer and with the attached Mixing is no longer necessary.

In the picture is a device for carrying out the sieving shown. The unscreened material is transported through a cyclone 1 and a screw conveyor 2 of the screening device 3 supplied, which consists of a cylindrical screen basket with an internal rotating racket. That out of the cylindrical strainer basket emerging powder falls through a conical powder outlet 4 into a pipeline 5, from which the screened material is pneumatically conveyed directly into a storage container will.

Example: The production of the finely divided U02 or U308 powder from the various types of scrap produced during pressing during lXellet production, Sintering and grinding occur and the misery of this so-called scrap powder with the sinterable U02 starting powder as in the main application P 16 67 851.6 in Examples 1 to 4.

The desired microhomogeneity (no agglomerates 100 / u) of these powder mixtures was duroh a pass sieve at 100 / u mesh size with a high-performance pass sieve (Durohsatz: 19 to U02 / n2U) achieved. The powder mixtures thus produced became pneumatic conveyed directly into the press bunker and in a known way to UO2 sintered bodies processed. A difference in quality and output between these powder mixtures and a fresh sinterable U0s powder was not established.

Claims (4)

PATENT CLAIMS 1. Process for the dry reprocessing of ceramic U02 nuclear fuel scrap according to patent ........ (Registration P 16 67 851.6), characterized in that the generated Uranium dioxide powder is subjected to sieving. 2. The method according to claim 1, characterized in that the pass sieving with a mesh size of the sieve from 63 / u to 200 / u, but preferably at 100 is achieved. 3. The method according to claim 1, characterized in that the pass sieving with a strainer consisting of a cylindrical strainer basket with an inside rotating racket is carried out. 4. The method according to claim 1, characterized in that the pass sieving is carried out continuously.