UCB-NE-108 USER'S MANUAL

The purpose of this manual is to provide users of UCB-NE-108 with the information necessary to use UCB-NE-108 effectively. UCB-NE-108 is a computer code for calculating the fractional release rate of readily soluble radionuclides that are released from nuclear waste emplaced in water-saturated porous media, and transported through layers of porous media. Waste placed in such environments will gradually dissolve. For many species such as actinides and rare earths, the process of dissolution is governed by the exterior flow field, and the chemical reaction rate or leaching rate. In a spent-fuel waste package the soluble cesium and iodine accumulated in fuel-cladding gaps, voids, and grain boundaries of spent fuel rods are expected to dissolve rapidly when groundwater penetrates the fuel cladding. UCB-NE-108 is a code for calculating the release rate at the interface of two layers of porous material, such as the backfill around a high-level waste package and natural rock, to check compliance with the US Nuclear Regulatory Commission's (USNRC) subsystem performance objective. It is an implementation of the analytic solution given below. 6 refs., 2 figs.