Criticality safety analysis for remote handled TRU waste at the Waste Isolation Pilot Plant

The Waste Isolation Pilot Plant (WIPP) is a facility designed to store transuranic (TRU) waste underground in a mined salt bed. All fissile nuclides except U235 are considered TRU nuclides. This report presents the results of the nuclear criticality analysis for Remote-Handled (RH) TRU waste stored at the WIPP site. The RH waste material will be contained in steel canisters that are five feet or ten feet long. Each ten foot canister is capable of holding three 55 gallon drums of waste material. The five foot canisters are to be welded together to form one ten foot long canister. In general the fissile waste material is mainly surface contamination on clothing, wipes, wrappings, tools, etc., or mixed in a borosilicate glass matrix or concrete. Other fissile material may be contained in absorbent mixtures. As a result, the fissile material will typically be spread over a large fraction of the volume in most of the waste storage canisters. Typical isotopic content of the fissile/other radioactive material is shown in Table 1-1. This analysis will analyze the RH waste storage and handling configurations at the WIPP site to show that up to 600 grams of fissile material per ten foot canister can be received and stored at the site without criticality safety concerns. 6 refs., 14 figs., 1 tab