PORFLOW Implementation of Vadose Zone Conceptual Model for Naval Reactor Component Disposal Area in the E-Area Low Level Waste Facility Performance Assessment

Abstract

PORFLOW models have been developed to implement the proposed conceptual models for the two Naval Reactor Component Disposal Areas (NRCDAs), 643-7E and 643-26E, for the purpose of evaluating dose impacts and producing disposal limits for the E-Area Low-Level Facility (LLWF). New NRCDA conceptual models were proposed by Wohlwend and Butcher (2019) for two areas within/adjacent to the E-Area LLWF used as storage/disposal sites for reactor components from the U.S. Navy since 1987. Naval Reactor (NR) waste is comprised of highly radioactive components consisting of activated corrosionresistant metal alloy contained within welded thick-walled steel casks, and auxiliary equipment primarily contaminated with lower levels of Activated Corrosion Products (ACPs) residing on the metal surfaces and contained within thinner-walled bolted containers.Separate three-dimensional models have been developed for each NR Pad to capture the unique geometry/features of the waste zone and subsurface hydrostratigraphic units, and chronology of facility events for each disposal unit. Radionuclide, chemical and material properties, as well as subsurface features represented in the models, were obtained from data packages containing key performance assessment (PA)

FY2021 Savannah River Site Composite Analysis Annual Summary Review

“…The model is designed to be used for Monte Carlo uncertainty analysis in support of the ELLWF PA. This report describes the model and shows results obtained from benchmarking/calibrating the model to best-estimate deterministic results obtained using a PORFLOW model of NRCDA vadose zone transport (Hang and Hamm 2020). The GoldSim model was able to accurately reproduce PORFLOW results with some adjustment to the nominal dispersion coefficient and vadose zone flow area used as "tuning" parameters.…”