Characterization of historical {sup 131}I emissions from Oak Ridge radioactive lanthanum processing
- McLaren/Hart Environmental Services, Alameda, CA (United States)
- Shonka Research Associates, Marietta, GA (United States)
As part of the Oak Ridge Dose Reconstruction, a detailed assessment of {sup 131}I releases from radioactive lanthanum (RaLa) processing is being conducted. From 1944 through 1956, fuel slugs from Oak Ridge (X-10) and Hanford reactors were dissolved and processed at Oak Ridge to separate {sup 140}La for Los Alamos weapons development. Fuel cooling times were as short as several hours, and dissolver off-gas passed through a caustic scrubber. In an earlier feasibility study, simple screening analyses identified RaLa processing as one of the largest potential contributors to off-site risk from the three Oak Ridge plants, with releases over 3.7 PBq (100,000 Ci) considered likely. With the close proximity of surrounding populations and potential {sup 131}I releases comparable to those established in the Hanford dose reconstruction, a detailed investigation was initiated. Inventories of {sup 131}I and {sup 140}Ba in X-10 slugs were calculated using the ORIGEN 2.1 code, detailed slug exposure records, and neutron flux distributions determined in the X-10 reactor in 1945. Informal expert elicitation was used to estimate a {sup 131}I release fraction for use in the initial iteration of the assessment. For later iterations, a simple numerical model of iodine distribution in RaLa chemical processing was prepared to predict releases from the dissolver and waste neutralizer tank based on five mass-balance equations. The critical caustic scrubber was then modeled with a kinetic-based model of iodine mass transfer. Separate analyses of release fractions are necessary for a number of off-normal conditions and accidents. The models were integrated for estimation of time histories of {sup 131}I release, interfacing with calculations of environmental transport, off-site exposure, and ranges of historical doses and health risks in a manner that reflects the uncertainty of all components.
- OSTI ID:
- 393996
- Report Number(s):
- CONF-9607135--
- Journal Information:
- Health Physics, Journal Name: Health Physics Journal Issue: Suppl.6 Vol. 70; ISSN HLTPAO; ISSN 0017-9078
- Country of Publication:
- United States
- Language:
- English
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