A Conceptual design study of a small natural convection lead-bismuth cooled reactor without refueling for 30 years

Chikazawa, Yoshitaka; Konomura, Mamoru; Mizuno, Tomoyasu; Mito, Makoto*; Tanji, Mikio*

Nuclear Technology, 154(2), p.142 - 154, 2006/05

https://doi.org/10.13182/NT06-A3724

Small fast reactors have a potential to be utilized as a power source applicable to diversified social needs and reduce capital risks. In remote sites such as Alaska and Hawaii, power sources without refueling whose capacities are lower than 50 MW-electric are required, because fuel transfer cost is expensive in such sites. In the case of power sources for developing countries, capacities are required in a range 50-300 MW-electric and proliferation resistance must be enhanced. A solution of a power plant without refueling is a fast reactor plant with a very long life core and proliferation resistance in such a plant is supposed to be tough. We have studied concepts of small fast reactor with various attractiveness such as economical competitiveness, reactor safety and very long lived core. In this study, a design concept of a small lead-bismuth cooled reactor, which pursues long operating cycle and inherent safety has been studied. The core is nitride fueled two regions homogeneous core cooled by natural circulated lead-bismuth eutectic. The burnup reactivity is kept 0.93 %dk/k and without refueling 30 years operation with 7.8 GWd/t average burnup. Since lead-bismuth eutectic is chemically inert in lead-bismuth-water contact, a simple tank type design with the steam generator in the reactor vessel is adopted eliminating an intermediate circuit system. The transient analysis shows the reactor has possible capability to keep the reactor system and fuel integrity in UTOP and ULOHS events. The target construction cost for remote sites is achieved by the first plant with 50 MW-electric capacity. The economical target of power sources for developing countries cities is also achieved in the condition of 150 MW electric power regarding series effect.