POTENTIAL FOR AND CONSEQUENCES OF CRITICALITY RESULTING FROM HYDROGEOCHEMICALLY CONCENTRATED FISSILE URANIUM BLENDED WITH SOIL IN LOW-LEVEL WASTE DISPOSAL FACILITIES

摘要

Evaluations were done to determine conditions that could permit nuclear criticality with fissile uranium in low-level-waste (LLW) facilities and to estimate potential radiation exposures to personnel if there were such an accident. Simultaneous hydrogeochemical and nuclear criticality studies' were done (1) to identify some realistic scenarios for uranium migration and concentration increase at LLW disposal facilities, (2) to model groundwater transport and subsequent concentration via sorption or precipitation of uranium, (3) to evaluate the potential for nuclear criticality resulting from potential increases in uranium concentration over disposal limits, and (4) to estimate potential radiation exposures to personnel resulting from criticality consequences. The scope of the referenced work was restricted to uranium at an assumed 100 wt% ~(235)U enrichment. Three outcomes of uranium concentration are possible: 1.uranium concentration is increased to levels that do pose a criticality safety concern; 2.uranium concentration is increased, but levels do not pose a criticality safety concern; or 3.uranium concentration does not increase.