APPLICATION OF RECENT IRON EVALUATIONS OF ENDF B, JEF AND JENDL TO NEUTRON-TRANSPORT CALCULATIONS THROUGH LIGHT-WATER REACTOR PRESSURE-VESSEL/

It has been generally known that iron cross section sets derived from ENDF/B-IV and ENDF/B-V evaluations underestimate the transmission of f ast neutrons through light water reactor pressure vessel. In recent ye ars, ENDF/S, JEF and JENDL iron data have been newly revised, To verif y an applicability of the new iron evaluations to neutron transport ca lculations through the pressure vessel, fast neutron spectra and vario us threshold dosimeter activities obtained with the revised iron data have been intercompared. The results calculated with ENDF/B-VI iron da ta among those show good agreements with the measurements. And as far as fast neutron dosimetry application of pressure vessels is concerned , the result of JEF-2.2 iron data is improved a little compared with t hat of JEF-1, and JENDL-3.2 iron data show more or less underpredicted result relative to earlier JENDL iron data.