482. 粉末充填型セラミック燃料体と被覆管との間に挿入したビスマス熱媒体の挙動

Abstract

Evaluation by out-of-pile heating experiment was made on two types of bismuth heat transfer bonding between powder compacted ceramic fuel and cladding, 1) vibration compaction of a mixture of ceramic fuel powder and bismuth powder in cladding tube, 2) vibration compaction of ceramic fuel powder in cladding tube with bismuth lamella formed on the inner surface of cladding. The principal results were as follows:(1) In the first case of mixed UO2 and bismuth powder, the bismuth originally distributed in the central region of the compact (2, 600°-2, 700°C) evaporated and moved toward the periphery (800°-900°C) where it assembled to serve as good liquid heat transfer medium.(2) In the second case, the bismuth lamella served as good liquid heat transfer medium without permeating into the inner regions of the compact.(3) There was no appreciable reaction between the bismuth and UO2 up to 2, 600°- 2, 700°C, nor between the bismuth and UN or UC up to 1, 20O°-1, 300°C.