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Title: Effective Half-Life of Caesium-137 in Various Environmental Media at the Savannah River Site

During the operational history of the Savannah River Site (SRS), many different radionuclides have been released from site facilities into the SRS environment. However, only a relatively small number of pathways, most importantly 137Cs in fish and deer, have contributed significantly to doses and risks to the public. The “effective” half-lives (Te) of 137Cs (which include both physical decay and environmental dispersion) in Savannah River floodplain soil and vegetation and in fish and white-tailed deer from the SRS were estimated using long-term monitoring data. For 1974–2011, the Tes of 137Cs in Savannah River floodplain soil and vegetation were 17.0 years (95% CI = 14.2–19.9) and 13.4 years (95% CI = 10.8–16.0), respectively. These Tes were greater than in a previous study that used data collected only through 2005 as a likely result of changes in the flood regime of the Savannah River. Field analyses of 137Cs concentrations in deer collected during yearly controlled hunts at the SRS indicated an overall Te of 15.9 years (95% CI = 12.3–19.6) for 1965–2011; however, the Te for 1990–2011 was significantly shorter (11.8 years, 95% CI = 4.8–18.8) due to an increase in the rate of 137Cs removal. The shortest Tes were for fishmore » in SRS streams and the Savannah River (3.5–9.0 years), where dilution and dispersal resulted in rapid 137Cs removal. Long-term data show that Tes are significantly shorter than the physical half-life of 137Cs in the SRS environment but that they can change over time. Therefore, it is desirable have a long period of record for calculating Tes and risky to extrapolate Tes beyond this period unless the processes governing 137Cs removal are clearly understood.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
1117333
Report Number(s):
SRNL-STI--2013-00725
Journal ID: ISSN 0265-931X
DOE Contract Number:
AC09-08SR22470
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Environmental Radioactivity; Journal Volume: 131; Journal Issue: C
Publisher:
Elsevier
Research Org:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES Cesium; Effective half-life; Ecological half-life; Long-term change