| Neutron reaction cross sections for 235U, 238U, 239Pu, hydrogen, beryllium, and carbon-12
are obtained from the National Nuclear Data Center. These data are processed and formatted for
use with the deterministic DISNEL reactor physics code which currently uses neutron reaction
cross section data produced in the 1950s. Three reactor models are developed, and the critical
dimensions are determined using MCNP. The configurations are water-moderated and reflected
sphere of 235U, and unreflected spheres of either highly enriched 235U or pure 239Pu. Those models
are then duplicated in DISNEL using the original and updated cross sections. The neutron
multiplication factors, and computational times are compared between the MCNP calculations and
the DISNEL calculations with the original and new cross sections. The updated cross sections
yield improved results for the water-moderated and reflected uranium model. The updated cross
sections in the unreflected configurations yielded multiplication factors further from critical when
compared to the results using the original cross sections.
Keywords: cross sections, DISNEL, multigroup diffusion theory |