Keywords: transient behaviour, low-enriched silicide fuel, research reactors, reactivity initiated accidents, failure threshold, uranium silicide, nuclear accidents, nuclear safety, pulse irradiation tests, nuclear power, nuclear energy
Transient behaviour of low-enriched uranium silicide plate-type fuel for research reactors during a reactivity-initiated accident
In many research reactors and test reactors, a low enriched (<20 wt% 235U) silicide fuel is to be used in the replacement of a high (93wt% 235U) to medium (45wt% 235U) 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°C to 970°C. 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°C (TDNB; departure from nucleate boiling temperature). Above temperatures of TDNB, 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.