The Enhanced Variance Propagation Code for the Idaho Chemical Processing Plant

The Variance Propagation (VP) Code was developed by the Los Alamos National Laboratory's Safeguard's Systems Group to provide off-line variance propagation and systems analysis for nuclear material processing facilities. The code can also be used as a tool in the design and evaluation of material accounting systems. In this regard, the VP code was enhanced to incorporate a model of the material accountability measurements used in the Idaho Chemical Processing Plant operated by the Westinghouse Idaho Nuclear Company. Inputs to the code were structured to account for the dissolver/ headend process, the waste streams, process sweepdowns, intercycle measurements, and nuclear material products. Tradeoff studies were performed to determine the sensitivity of measurement and sampling errors to the overall material balance error. We determined that the material balance error is very sensitive to changes in the sampling errors.