Open AccessOUT-OF-PILE PROPERTIES OF MIXED URANIUM-PLUTONIUM CARBIDES. Final Report
Author(s) -
D. Stahl,
A. Strasser,
K. Taylor,
John W. Anderson
Publication year - 1963
Language(s) - English
Resource type - Reports
DOI - 10.2172/4111496
Subject(s) - sintering , materials science , pellets , carbide , analytical chemistry (journal) , uranium , melting point , metallurgy , solid solution , nuclear chemistry , composite material , chemistry , chromatography
Fabrication studies to produce high density solid solutions of 80% UC-- 20% PuC, with reproducible structure, composition, and density, were completed. Solid solution (U,Pu)C powder was produced by the oxide-carbon reaction, and the powders were consolidated by cold pressing and sintering. The studies were a continuation of work performed on Contract AT(30-1)-2899 with the USAEC. Two types of material were produced: 1. (U/sub 0.8/Pu/sub 0.2/)C/sub 0.95/, single,phase monocarbide pellets with average densities of 12.8 g/cm/sup 3/ (94% of theoretical), sintered at 1925 deg C; 2. (U/subn 0.95/ at 0.1 wt% Ni sintering aid, major monocarbide phase and minor amount of sesquicarbide phase pellets, with average densities of 13.1 g/cm/sup 3/ (96.5% of theoretical), sintered at 1550 deg C. The coefficient of thermal expansion was measured as 11.9 x 10/sup -6/ / deg C for (U/sub 0.8/Pu/sub 0.2/) x C/sub 0.95/ at 25 to 1400 deg C and 12.3 x 10/sup -6// deg C for (U/sub 0.8/Pu/sub 0 .2/)C/sub 0.95/ 0.1 wt% Ni at 25 to 1400 deg C. The presence of the nickel sintering aid did not make a significant difference. the values are similar to those of UC, compared at 950 deg C, the maximum temperature to which UC has been measured. The melting point of (U/sub 0.8/ Pu/sub 0.2/)C/sub 0.95/ was found to be 2480 P 20 deg C. The solidus is estimated to be about 2430 deg C. The vapor pressure data in the temperature range of 2100 to 2600 deg K show that the pressure of plutonium is about the same as uranium over (U/sub 0.8/Pu/sub 0.2/C/sub 0.95/. While the uranium data are about an order of magnitude higher than anticipated, based on data for U over UC (probably due to carbon diffusion across the cell), the thermal stability of the fuel in the temperature range of power reactors is still quite good. Thermal conductivity capsules containing (U/sub 0.8/Pu/sub 0.2/) x C/sub 0.95/, (U/sub 0.8/Pu/sub 0.2/)C/sub 0.95/ plus 0.12 wt% Ni, and UC plus 0.12 wt% Ni (standard) were fabricated. Repairs required by the Mound Laboratory equipment have delayed the measurements. (U/sub 0.8/Pu/sub 0.2/)C/sub 0.95/ with and without nickel sintering aid, was compatible with type 316 stainless steel, niobium, niobium-- 1% zirconium, 2 1/4 Cr-- 1 Mo steel, and vanadium at 593 deg C and 816 deg C for 1000 and 4000 hr. There was no reaction with Inconel-X after 1000 hr at 593 deg C, but there was a slight reaction after 1000 hr at 816 deg C. A reaction was noted with Zircaloy-2 after 1000 hr at both 593 deg and 816 deg C. The results were similar to those obtained with UC under AEC Contract AT(30-1)-2899. (D.L.C.