Abstract:The small nuclear power plant enjoys advantages of long life and passive safety and is an important choice in the future nuclear power development. A conceptual core is designed for the small nuclear power plant. It is a pool-type fast reactor with sodium as coolant, the movable reflector and the fixed absorber as the reactivity control system for long-life. Further calculation results show that the life of the reactor could be as long as 30 years, with a reasonable power distribution, all the reactivity coefficients negative, enough reactivity control worth, and all parameters satisfy the design requirements.