Proposed beryllium metal bounding airborne release fractions (ARFs)/rates (ARRs) and respirable fractions (RFs) for DOE facility accidents analyses

摘要

Beryllium metal has special properties for nuclear applications and is used widely within the Department of Energy (DOE) complex. Beryllium is toxic and has the potential to cause health effects (sensitization and chronic beryllium disease) to workers. Due to the type of processing involving large quantities of beryllium metal and powders and potential for significant airborne release under accident conditions, a comprehensive hazard analysis is required by DOE in a safety analysis document that evaluates potential accidents that can cause beryllium releases to the workplace and public or to the environment. The goal of the safety analysis is to identify and evaluate hazards so that appropriate controls or safeguards can be specified to protect the workers and public from potential accidents. A hazard assessment is also required to comply with 10 CFR Part 850, Chronic Beryllium Disease Prevention Program (1999) to protect the workers.rnDOE safety analyses include a quantitative estimate of releases and downwind concentrations for purposes of hazard classification and determination of the need for additional hazards analysis, accident analysis, and risk assessments. There are no complex-wide accepted Airborne Release Fractions (ARFs) and Respirable Fractions (RFs) that can be used to evaluate the potential downwind consequences of releases of beryllium under various accident conditions (e.g., spill, fire, stress, explosion, etc.). The purpose is to recommend DOE complex-wide ARFs and RFs that can be used to evaluate the potential downwind consequences of accidents.rnThis paper proposes various values for ARFs and RFs that are based on review of the published information and data on the oxidation and ignition behavior of beryllium metal encased in a thin coat of non-porous, adherent oxide ("blue oxide"); the typical form of this material found in DOE facilities. Information is also presented as a function of the morphology of the metal (i.e., large, coherent, pieces; turnings/swarfs; chips/powder; and dust) because the surface to volume ratio is an important factor in evaluating both the amount of beryllium released and the potential for ignition of the metal that may increase the amount of release significantly.rnGuidance is also provided for the use of the DOE-HDBK-3010-94. Airborne Release Fractions /Rates and Respirable Fraction for Nonreactor Nuclear Facilities, values for oxide releases that result in a more liberal, allowable limiting airborne concentration for determining consequences and hazard classification of the facility. Detailed explanations of the proposed ARF/RF values for the various beryllium metal forms (large coherent pieces, chips/powder, turning/swarfs from processing, and dust) and other aspects of beryllium are provided in a report by Mishima et al. (April 2005). A short version of this report and a summary of the ARF/RF values are presented here.