DEVELOPMENT OF AN EQUIVALENCE RELATION AND A NEW DISADVANTAGE FACTOR APPLICABLE TO BOTH FAST AND THERMAL ENERGY REGIONS

An improved approach for generating cell-homogenized cross-section has been developed. The key to this approach is a simple expression for the disadvantage factor applicable to both thermal and fast energy regions. The aformentioned disadvantage factor is used in the equation defining a cell averaged cross-section to yield a new equivalence relation. The method is applied to U-238 self-shielding in thermal and fast reactor applications. Utilizing ENDF/B-IV cross-section sets, the results obtained using the present method in the epithermal region agree with LEOPARD results within about +2% for typical PWR lattices. The results for the developed disadvantage factor agree to within acceptable range with the results obtained using transport theory.