Determination of Airborne Release Fractions from Loose Powder Contamination Under Impact Stress

Abstract

Safety basis calculations support the safety considerations necessary for legacy nuclear facilities as they transition from active use, through limited operations and standby modes, until final disposition is achieved. Many of the calculations are governed heavily by the coefficients presented in DOE-HDBK-3010 in the form of airborne release of radioactive material resulting from penetration of the facility per seismic activity, full facility fires, and/or explosions. The main objective of this study is to validate the original data for airborne release fractions (ARFs) for powder contaminants under impact, as determined in DOE-HDBK-3010. The limited data available for impact experiments was generated at the Rocky Flats Plant in 1987, where the median ARFs for surrogate powder contamination were 4E-4 with a bounding value of 1E-2. However, estimating the level of uncertainty was challenging in the absence of multiple measurements conducted under identical test conditions. Moreover, the uncertainty was significantly increased due to the restricted range of the test conditions. A more modern approach has been developed for the experimental design in this study, utilizing standardized techniques and analytical instruments. An impact apparatus was employed to be able deliver repeatable impact forces up to 369 kg·cm (320 in.·lb.). Cesium chloride was used as the surrogate powder contaminant in these experiments as it is extremely soluble in water and is even more so in the acidic media used to leach/dissolve the air filters for concentration analysis using mass spectrometry The developed approach leveraged multiple international standards and historical documents in an attempt to recreate a valid testing system that can be used for future analysis and to analyze mitigation factors such as contamination fixative technologies. The current ARFs were found to be consistent with the original values in DOE-HDBK-3010, 3.47E-4 and 4E-4, respectively.