AIR DISPERSION MODELING AT THE WASTE ISOLATION PILOT PLANT

Rucker, D.F.

Environmental Evaluation Group, Albuquerque, NM (United States)

关键词: Safety Analysis;    Alpha-Bearing Wastes;    Air Pollution;    Wipp;    Radionuclide Migration;   

DOI  :  10.2172/769584
RP-ID  :  EEG-76
RP-ID  :  AC04-89AL58309
RP-ID  :  769584

美国|英语

来源: UNT Digital Library

【 摘 要 】

One concern at the Waste Isolation Pilot Plant (WIPP) is the amount of alpha-emitting radionuclides or hazardous chemicals that can become airborne at the facility and reach the Exclusive Use Area boundary as the result of a release from the Waste Handling Building (WHB) or from the underground during waste emplacement operations. The WIPP Safety Analysis Report (SAR), WIPP RCRA Permit, and WIPP Emergency Preparedness Hazards Assessments include air dispersion calculations to address this issue. Meteorological conditions at the WIPP facility will dictate direction, speed, and dilution of a contaminant plume of respirable material due to chronic releases or during an accident. Due to the paucity of meteorological information at the WIPP site prior to September 1996, the Department of Energy (DOE) reports had to rely largely on unqualified climatic data from the site and neighboring Carlsbad, which is situated approximately 40 km (26 miles) to the west of the site. This report examines the validity of the DOE air dispersion calculations using new meteorological data measured and collected at the WIPP site since September 1996. The air dispersion calculations in this report include both chronic and acute releases. Chronic release calculations were conducted with the EPA-approved code, CAP88PC and the calculations showed that in order for a violation of 40 CFR61 (NESHAPS) to occur, approximately 15 mCi/yr of 239Pu would have to be released from the exhaust stack or from the WHB. This is an extremely high value. Hence, it is unlikely that NESHAPS would be violated. A site-specific air dispersion coefficient was evaluated for comparison with that used in acute dose calculations. The calculations presented in Section 3.2 and 3.3 show that one could expect a slightly less dispersive plume (larger air dispersion coefficient) given greater confidence in the meteorological data, i.e. 95% worst case meteorological conditions. Calculations show that dispersion will decrease slightly if a more stable wind class is assumed, where very little vertical mixing occurs. It is recommended that previous reports which used fixed values for calculating the air dispersion coefficient be updated to reflect the new meteorological data, such as the WIPP Safety Analysis Report and the WIPP Emergency Preparedness Hazards Assessment. It is also recommended that uncertainty be incorporated into the calculations so that a more meaningful assessment of risk during accidents can be achieved.