Atmospheric pressure fluctuations and oxygen enrichment in waste tanks

Abstract

AtmosphericPressureFluctuations and OxygenEnrichmentin Waste Tanks Atmospheric Pressure Fluctuations and Oxygen Enrichment in Waste TanksExecutive Summary .Oxygen enrichment in waste tanks can reach and SRTC's Climatology Site were analyzed to hazardouslevels if normalpurging is interruptedby determinethe mean andmaximumpressureincreases power failures. In such cases it is necessary to ina5-yearperiod 1986-1990. estimate the time it would take for oxygen buildup to reachacriticalconcentration.The mean pressure increase in an 8-hr period was found to be 1.7 mb and 5.0 mb for a 24-hr period. Mixing of outside air into closed tanksthrough smallThese pressure increases would induce an air leaks will be slow without externalforcing. One such enrichment of ,...0.2%and -0.5% for 8 and 24-hour external forcing mechanism is natural atmospheric periods,respectively. Since oxygen is 21%of air by pressure fluctuations, which can force air into tanks volumethe in-tankoxygen enrichmentwouldbe -1/5 throughsmall cracks or vent holes. The efficiency of of the percentageslistedabove. this process is a functionof the atmospheric pressure increases over time periodscomparable to the in-tankThe above values over-estimate the enrichmentrate mixing rate.becausethey do not include the reductionin efficiency as the in-tank oxygen level increases and becausethey Two in-tank mixing rates were assumed (8 and 24 assume complete mixing of oxygen entering the tank. hours) and pressure measurements from Bush Field