Calculated k-effectives for plutonium critical experiments. Consolidated Fuel Reprocessing Program

Design criteria for a reprocessing facility for Liquid Metal Fast Breeder Reactor fuel are presently being developed. One major issue of concern is the criticality safety of all equipment (dissolver, centrifuge, holding tanks, etc.) that is used to contain the plutonium solution. The purpose of this work is to evaluate the validity of the SCALE code system for application to plutonium systems when used with cross section data from the 27-group ENDF/B-IV and 16-group Hansen-Roach libraries (available in SCALE). Previous work has been done in this area, but it was limited to one-dimensional discrete ordinates calculations. Twelve sets of critical plutonium experiments yielding a total of thirty-eight computational models are considered. The experiments were performed in spherical, cylindrical, and slab geometries covering a wide range of fuel composition. The hydrogen-to-plutonium atom ratio varied from 3695 for an infinite dilute system to 0.04 for damp, plutonium oxide polystyrene experiments. The SCALE system employs several codes for criticality calculations, but only two are used in this work. Criticality Safety Analysis Sequence Number 1 (CSAS1) uses discrete ordinates theory to calculate k-eff, and its application is limited to one-dimensional calculations. Criticality Safety Analysis Sequence Number 2 (CSAS2) uses Monte Carlo methods to calculatemore » k-eff, and its application includes three dimensional systems. Calculated results of the 38 models using both cross sections libraries are presented. The calculated k-effectives vary from a high of 1.04119 +- 4.87E-3 to a low of 0.99458 +- 4.66E-3. The majority of the k-effectives vary between 1.01 and 1.03 illustrating a systematic overestimation of k-eff. Some of the one dimensional experiments were modeled with both CSAS1 and CSAS2 to see if the calculated k-effectives show any significant dependency on the code used.« less