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

Journal Article · Thu May 01 04:00:00 EDT 2014 · Journal of Environmental Radioactivity

DOI:https://doi.org/10.1016/j.jenvrad.2013.10.024· OSTI ID:1117333

Paller, M. H.; Jannik, G. T.; Baker, R. A.

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 (T_e) 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 T_es 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 T_es 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 T_e of 15.9 years (95% CI = 12.3–19.6) for 1965–2011; however, the T_e 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 T_es were for fish 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 T_es 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 T_es beyond this period unless the processes governing ¹³⁷Cs removal are clearly understood.

• Research Organization: Savannah River Site (SRS), Aiken, SC (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC09-08SR22470
• OSTI ID: 1117333
• Report Number(s): SRNL-STI--2013-00725
• Journal Information: Journal of Environmental Radioactivity, Journal Name: Journal of Environmental Radioactivity Journal Issue: C Vol. 131; ISSN 0265-931X
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Cesium
Ecological half-life
Effective half-life
Long-term change