Seasonal changes in the composition of passively ventilated waste tank headspaces

The headspaces of four passively ventilated high-level radioactive waste tanks were sampled five times over a one-year period to evaluate seasonal changes in composition. Tanks BX-104, BY-108, C-107, and SX-102 were selected for the study on the bases of their widely varying headspace compositions, waste types, and physical headspace conditions. Samples were collected and analyzed for inorganic vapors, permanent gases, and organic vapors. Data from the 20 sampling events were compiled and reviewed. Raw mass spectral data for organic vapors were reprocessed by a single analyst. Measurement precision for results within individual sampling events, which includes both sampling and analytical random errors, was generally within the requirement of a 25% relative standard deviation. Data were fit to an analysis of variance (ANOVA) model and tested for correlation with headspace temperature. The ANOVA results indicate that the majority of headspace constituents studied were at relatively constant levels during the year-long study. The percent relative standard deviation (RSD{sub TIME}) of analyte means obtained for the five sampling events were generally low; only 15 of the 152 analytes had RSD{sub TIME} values above 60%. These highest RSD{sub TIME} values were obtained for 13 organic vapors in Tank BX-104 and two permanent gases in Tank C-107