Evaluation of Melting Temperature in (Pu_(0.43)Am_(0.03)U_(0.54))O_(2.00)

摘要

Japan Atomic Energy Agency has developed plutonium and uranium mixed oxide (MOX) fuel containing 20-32%Pu content for the fast breeder reactor, Monju. During irradiation, a large temperature gradient in the radial direction of a fuel pellet causes redistribution of Pu and U, and the Pu content increases to about 40% at the pellet center. The maximum temperature of the fuel pellet during irradiation is limited within the design criterion to prevent fuel melting. So, it is important to evaluate melting points of MOX containing 40%Pu . Lyon and Baily [1] and Adamson et al [2] measured the melting points of MOX systematically using the thermal arrest technique and reported the solidus temperatures of 40%Pu-MOX were 2908K [1] and 2935K [2]. Recently, the authors measured the melting points of MOX when using a Re inner capsule to hold the sample and prevent its reaction with a W outer capsule. They reported the MOX with Pu content of 40% had a solidus temperature of 3001±35K[4]. In this work, it was confirmed that the MOX with 43%Pu content was not melted by heat treatment just below the melting point. The heat treatment was done by using the Re inner capsule.