Conceptual design of a small lead-bismuth cooled reactor

Small sized fast reactors have a potential to use a power source applicable to diversified social needs. In the feasibility studies on commercialized fast breeder reactor cycle system of Japan Nuclear Cycle Development Institute (JNC), we will make a concept of small sized fast reactor with various requirements of economical competitiveness, reactor safety, very long lived core, etc. One of promising concepts is a small lead-bismuth cooled fast reactor. In this design, the reactor type is tank type and the steam generator is placed inside the reactor vessel, because there is no high reactivity between lead-bismuth and steam. Inherent and passive safety is enhanced to avoid a core disruptive accident even at anticipated transient without scram. The construction cost of the plant is estimated at 800,000 yen/kWe which is much higher than the target value, that is, 350,000 yen/kWe (5.5 yen/kWh), because of a scale demerit coming from a low power and a usage of heavy reactor components for lead-bismuth coolant. But it would have some possibility to reduce the construction cost with a improvement of core efficiency, an increasing of a reactor power, a common use of some BOP components among reactors and a learning effect of construction. (author)