Transient behaviour of low-enriched uranium silicide plate-type fuel for research reactors during a reactivity-initiated accident

摘要

In many research reactors and test reactors, a low enriched (<20 wt% ~(235)U) silicide fuel is to be used in the replacement of a high (93wt% ~(235)U) to medium (45wt% ~(235)U) enrichment aluminide fuel because a peaceful use of nuclear energy. At the Nuclear Safety Research Reactor (NSRR), the pulse irradiation tests were conducted on silicide mini-plate fuels to study the fuel reliability under transient temperature conditions. In the study energy deposition ranged from 32 to 164 cal/g · fuel plate. The given energies were corresponded to the peak cladding surface temperatures ranged from 140℃ to 970℃. The major findings from the study are: (1) neither failure nor degradation of dimensional stability of the tested silicide mini-plate fuel occurred in the temperature below 174℃ (T_(DNB); departure from nucleate boiling temperature). Above temperatures of T_(DNB), the dimensional stability was gradually degraded with temperature; (2) the tested silicide mini-plate fuels were intact at energy depositions <82 cal/g · fuel plate but were damaged at energy depositions of >94 cal/g · fuel plate. A failure threshold must be existed between these two values.