DE1148663B - Process for the production of nuclear reactor fuel elements from a uranium oxide mixture - Google Patents

Description

GERMAN

PATENT OFFICE

U6072Vnic / 21g

REGISTRATION DATE: MARCH 20, 1959

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: MAY 16, 1963

The invention relates to a method for producing nuclear reactor fuel elements from a Uranium oxide mixture whose sintering properties are comparable to those of non-stoichiometric uranium dioxide is.

Uranium has the property of forming non-stoichiometric oxides. Some of these oxides with the composition UO ₂₀₂ to about UO ₂₃ are of interest in the production of sintered bodies, since they result in denser bodies than they are obtained with stoichiometric oxides sintered at the same temperature. In addition, the sintering temperature of non-stoichiometric oxides can be kept lower than that of stoichiometric oxides in order to produce sintered bodies of the same density.

So far, three types of processes have been proposed _{for the production of non-stoichiometric UO 2:}

a) the controlled reduction of UO ₃ or U ₃ O ₈ in hydrogen in order to thereby obtain the desired non-stoichiometric deviation or variant;

b) converting ammonium diuranate into UO ₃ by calcining or roasting in air, ^a5 followed by a hydrogen reduction in order _{to generate UO 2} with a correspondingly sufficient reactivity; this UO ₂ absorbs when exposed to air at room temperature and results in a non-stoichiometric uranium oxide compound;

c) the controlled oxidation of the stoichiometric UO ₂ .

In the method according to the invention, a mixture of UO ₂ - and U ₃ O ₈ powder, the U ₃ O ₈ moiety is 5 to 45 weight percent, prepared and compressed, the compressed mixture is then in an inert atmosphere at a temperature of 1200 Pressed and sintered up to 1500 ° C.

Thus, according to the invention, for. B. a mixture of 70:30 parts by weight of UO ₂ / U ₃ O ₈ (about UO _{2> 20} corresponding) can be ground in a ball mill to compress it, and then brought into a granular shape by a drum process or circulation. The granules thus formed can be loosely sintered in argon to form sintered bodies in the form of dense spheres; but they can also be compressed cold and sintered in argon, in a tempera process for production

of nuclear reactor fuel elements

from a uranium oxide mixture

Applicant:

United Kingdom Atomic Energy Authority, London

Representative: Dipl.-Ing. E. Schubert, patent attorney,
Siegen, Oranienstr. 14th

Claimed priority:
Great Britain July 19, 1958 (No. 23 257)

George Elliot Christie, London,
has been named as the inventor

ture range from 1200 to 1500 ° C over a period of ¹ Ii to 2 hours in order to obtain sintered fuel bodies of approximately 97%> of the theoretically achievable density.

Claims (4)

PATE N TA N PROBLEM ΕΙ. Process for the production of nuclear reactor fuel elements from a uranium oxide mixture whose sintering property is comparable to that of non-stoichiometric uranium dioxide, characterized in that a mixture of UO., - and UoOc powder, its U ₃ O _a proportion 5 to 45 percent by weight is prepared and compacted, then the compacted mixture in is pressed and sintered in a protective atmosphere at a temperature of 1200 to 1500 ° C. 2. The method according to claim 1, characterized in that the compressed mixture in drum to produce granular bodies. 3. The method according to claim 1, characterized in that the granular body in the temperature range from 1200 to 1500 ⁰ C to be sintered. 4. The method according to claim 2, characterized in that the granular body compacts and sintered in the temperature range from 1200 to 1500 ° C.