Influence of nuclear data uncertainties on thorium fusion-fission hybrid blanket nucleonic performance

The fusion-fission hybrid blanket proposed for the Tandem Mirror Hybrid Reactor employs thorium metal as the fertile material. Based on the ENDF/B-IV nuclear data, the 233U and tritium production rate and blanket energy multiplication averaged over the blanket lifetime of about 9 MW-yr/m2 are 0.76 and 1.12 per D-T neutron and 4.8, respectively. At the time of the blanket discharge, the 233U enrichment in the thorium metal is about 3%. The thorium cross sections given by the ENDF/B-IV and V were reviewed, and the important partial cross sections such as (n,2n), (n,3n), and (n,γ) were found to be known to +-10 to 20% in the respective energy range of interest. A sensitivity study showed that the 233U and tritium production rate and blanket energy multiplication are relatively sensitive to the thorium capture and fission cross section uncertainties. In order to predict the above parameters within +-1%, the Th(n,γ) and Th(n,νf) cross sections must be measured within about +-2% in the energy range 3 to 3000 keV and 13.5 to 15 MeV, respectively