ANALYSIS OF AVAILABLE HYDROGEN DATA & ACCUMULATION OF HYDROGEN IN UNVENTED TRANSURANIC (TRU) DRUMS

Abstract

This document provides a response to the second action required in the approval for the Justification for Continued Operations (JCO) Assay and Shipment of Transuranic (TRU) Waste Containers in 218-W-4C. The Waste Management Project continues to make progress toward shipping certified TRU waste to the Waste Isolation Pilot Plant (WIPP). As the existing inventory of TRU waste in the Central Waste Complex (CWC) storage buildings is shipped, and the uncovered inventory is removed from the trenches and prepared for shipment from the Hanford Site, the covered inventory of suspect TRU wastes must be retrieved and prepared for processing for shipment to WIPP. Accumulation of hydrogen in unvented TRU waste containers is a concern due to the possibility of explosive mixtures of hydrogen and oxygen. The frequency and consequence of these gas mixtures resulting in an explosion must be addressed. The purpose of this study is to recommend an approach and schedule for venting TRU waste containers in the low-level burial ground (LLBG) trenches in conjunction with TRU Retrieval Project activities. This study provides a detailed analysis of the expected probability of hydrogen gas accumulation in significant quantities in unvented drums. Hydrogen gas accumulation in TRU drums is presented and evaluatedmore » in the following three categories: Hydrogen concentrations less than 5 vol%; Hydrogen between 5-15 vol%; and Hydrogen concentrations above 15 vol%. This analysis is based on complex-wide experience with TRU waste drums, available experimental data, and evaluations of storage conditions. Data reviewed in this report includes experience from the Idaho National Environmental Engineering Laboratories (INEEL), Savannah River Site (SRS), Los Alamos National Laboratories (LANL), Oak Ridge National Laboratories, (ORNL), Rocky Flats sites, Matrix Depletion Program and the National Transportation and Packaging Program. Based on this analysis, as well as an assessment of the probability and frequency of postulated credible accident scenarios, this study presents a plan and schedule for accomplishing necessary venting for segregated unvented TRU drums. A recommended method for venting TRU drums is proposed. Upon revision of the authorization basis document to include TRU drum venting, and successful completion of readiness activities; TRU drum venting will be implemented in the LLBG.« less