100-group, 2-D calculation of the Winfrith iron benchmark experiment

The neutron flux measured in the integral iron benchmark experiment at the ASPIS facility (Winfrith) has been calculated by means of the 2-Dimensional DOT Code, using the 100-group EURLIB standard library (based on ENDFB/III). The calculation has been done in a P3/S4 approximation. The results are compared with the experimental ones concerning the neutron spectra at four penetrations into the iron block. For large depths the calculation appreciably underestimates the fast component above 0.8 MeV, indicating possibly an inadequacy of the fast neutron cross-sections for iron in EURLIB. The results of these 100-group calculations are reduced to the agreed 15 group structure and are compared with those using a 15-group library obtained by collapsing EURLIB. Both calculations severely underestimate the flux above 0.1 MeV, at depths greater than 50cm; the finer group structure does not significantly reduce this discrepancy. The 100 group calculation has been repeated with the EURLIB-3 library, based on ENDF/B-IV, and the differences are discussed. (author)