Compatibility of Non-Metallic Plutonium Fuel with High-Melting Metals

The authors have investigated the compatibility of plutonium monocarbide with tungsten, molybdenum, tantalum and niobium when held for 1900 hours at temperatures of 800, 900 and 1050°C, and of plutonium dioxide with molybdenum, tantalum and niobium when held for 1000 hours at 1400 and 1500°C. Tungsten was found to be the most stable of the metals when in contact with plutonium monocarbide, followed by molybdenum, tantalum and niobium in descending order of stability. It is shown how the carbon content of the carbide affects the compatibility of the carbide with high-melting metals. No interaction was detected between PuO2 and the listed metals when they were held for 110 hours at 1400°C. Similarly, no interaction was detected between PuO, and niobium held for 1000 hours at 1500°C, whereas the depth of the diffusion layer was 40-60 μm in the case of tantalum and 10-20 μm in that of molybdenum. (author)