The Transmutation of Strontium-90 and Cesium-137 in a High-Flux Fast Reactor with a Thermalized Central Region

The fission products ⁹⁰Sr and ¹³⁷Cs produced by fission reactors of 30 GW(th) can be transmutated into stable nuclides by neutron irradiation with a thermal flux of 2 × 10¹⁶ n cm⁻² s⁻¹. The rates of transmutation are 15 and 3.3 times greater, respectively, than that of spontaneous beta decay. The transmutation would take place in a central thermalized region of a high-flux fast burner reactor of 7 GW(th). In the case where the power reactors of 23 GW(th) are breeders with a high breeding gain of G = 0.38, the total system, inclusive of the high-flux burner, remains a breeding system, with G_total = 0.09. Details of the neutronics calculations and simplified thermohydraulics are given. The high-flux burner is fueled with a molten salt of chlorides of plutonium and sodium with a power density of 10 kW cm⁻³. The “self-liquidation” of such a system is discussed.