Comparison of RBWR and SFR Design and Performance Characteristics - 14277

Sodium-cooled fast reactor (SFR) cores and fuel cycles are usually considered for fuel-self-sustaining operation and for actinide incineration. Recently, several reduced-moderation BWR (RBWR) cores have been designed to achieve these same missions, but while operating within an ABWR pressure vessel; they rely upon near-term LWR technologies. The RBWR-AC and RBWR-Th are two such fuel-self-sustaining core designs: in their equilibrium state they are charged only with depleted urania and thoria, respectively. The former was designed by Hitachi and the latter at the University of California, Berkeley, in collaboration with the University of Michigan, MIT, and BNL. The fuel cycle and performance characteristics of these two RBWR designs are compared with those of the ARR-a fuel-self-sustaining SFR. The RBWR-TB2-an RBWR core designed by Hitachi for transmutation of LWR transuranium (TRU)- is compared with the ABR - an SFR designed to incinerate actinides. It is found that, relative to the sodium-cooled ARR, the RBWR-AC has a smaller fissile plutonium fraction (due to a softer neutron spectrum) and more proliferation resistant fuel; but requires more than twice the specific inventory of heavy metal (HM) and trans-fertile material (TRF); has significantly larger burnup reactivity swing; and has lower discharge burnup that, along with its lower thermodynamic efficiency, results in larger mass of plutonium, TRF, and HM to be recycled per unit of electricity generated. Similar conclusions are found for the comparison between the RBWR-TB2 and the ABR. Compared to the RBWR-AC, the RBWR-Th offers 50% higher discharge burnup and requires a smaller mass of HM to be recycled per unit of electricity generated when using the same critical power and void fraction models and constraints. However, the safety of the RBWR-Th design is yet to be determined. (authors)