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THE PREPARATION AND PROPERTIES OF ZIRCONIUM-URANIUM-HYDROGEN ALLOYS

Technical Report ·
OSTI ID:4316310

Zirconium hydride was chesen as the moderator for a group of solid homogeneous reactors currently on the market. The fuel material for these reactors is prepared by first making a zirconium-enriched uranium alloy by conventional melting techniques and then adding hydrogen at elevated temperature in a gas-handling system. All necessary forming operations are performed on the zirconium- uranium alloy before the hydrogen is added, so that the relatively brittle final alloy is ready for cladding without further handling. Zirconiumhydrogen and zirconium- uranium- hydrogen alloys containing up to 10.9 hydrogen atoms per zirconium atom have been prepared by this direct hydriding technique. The hydriding conditions must he somewhat carefully controlled if cracking or disintegration of the material during hydriding is to be avoided. The physical disruption which often accompanies such a process can be understood in terms of the phase changes which occur during the hydriding. Thus, at the temperatures employed, approximately one mole of hydrogen can be added per mole of zirconium before the solubility of hydrogen in beta zirconium is exceeded. Further hydrogen additions cause precipitation of a brittle hydride phase, with the result that proper control of this portion of the procedure is particulyarly important. An investigation of a portion of the zirconium-uranium-hydrogen phase diagram has been made to help determine the optimum conditions for preparing the ternary alloy. This investigation was carried out, in part, by an unusual dilatometric technique in which one alloy component, hydrogen was added isothermally in the dilatometer. This technique gave directly the most useful quantities, the density changes which occurred on hydriding. Measurements of physical properties and observation of gross radiation effects have shown the ternary alloy to be suitable for the low-power use intended, and have begun to define tbe general operating conditions under which the material is useful. (auth)

Research Organization:
General Atomic Div., General Dynamics Corp., San Diego, Calif.
NSA Number:
NSA-12-014826
OSTI ID:
4316310
Report Number(s):
A/CONF.15/P/789
Country of Publication:
Country unknown/Code not available
Language:
English