Fuel Cycle Performance of the Wielenga Innovation Static Salt Reactor

Abstract

This work presents a detailed fuel cycle analysis of an innovative static molten salt fast reactor called Wielenga Innovation Static Salt Reactor (WISSR). The fuel salt is a mixture of 55 mol% NaCl and 45 mol% (U,TRU)Cl3, and the reactivity is controlled by moving a variable amount of liquid fuel pneumatically. The pneumatic transfer of fuel salt allows flexible fuel management. To flatten the power distribution, a simple out-in fuel management scheme was adopted by discharging burned fuel from the interior core region, moving fuel salts across the radial regions inward, and adding fresh fuel to the outermost region. The current design of WISSR features a burner design for efficiently burning transuranic nuclides (TRU) recovered from pressurized water reactor used nuclear fuels. Using a fresh fuel with 57.4 at.% TRU in heavy metals, an equilibrium cycle length of 102.5 days could be maintained with a refueling rate of 403 L/cycle. In an equilibrium cycle, the discharged fuel burnup could reach 19.6 at.%, with 25% of the charged TRU destroyed at a low TRU conversion ratio of 0.18. Detailed cycle-by-cycle analyses showed that major neutronics performance parameters converged to the equilibrium cycle values in about 30 cycles by employing enrichment zoning in the startup core in a way to approximate the equilibrium cycle core compositions. During the transition cycles, the prematurely discharged fuel salt was recycled into the core without chemical processing to improve resource utilization.