Technical basis document for the unplanned excavation/drilling of 200 area soils

This technical basis document was developed to support the Tank Farms Documented Safety Analysis (DSA) and describes the risk binning process and the technical basis for assigning risk bins for the unplanned excavation/drilling of 200 Area soils representative accident and associated represented hazardous conditions. The purpose of the risk binning process is to determine the need for safety-significant structures, systems, and components (SSC) and/or technical safety requirement (TSR)-level controls for a given representative accident or represented hazardous conditions based on an evaluation of the frequency and consequence. Note that the risk binning process is not applied to facility workers, because all facility worker hazardous conditions are considered for safety-significant SSCs and/or TSR-level controls. Determination of the need for safety-class SSCs was performed in accordance with DOE-STD-3009-94, Preparation Guide for US. Department of Energy Nonreactor Nuclear Facility Documented Safety Analyses, as described in this report