Sources and Migration of Plutonium in Groundwater at the Savannah River Site
详细信息 查看全文
- 作者：Minhan Dai ; James M. Kelley ; and Ken O. Buesseler
- 刊名：Environmental Science & Technology
- 出版年：2002
- 出版时间：September 1, 2002
- 年：2002
- 卷：36
- 期：17
- 页码：3690 - 3699
- 全文大小：164K
- 年卷期：v.36,no.17(September 1, 2002)
- ISSN：1520-5851
文摘
The isotopic composition, size distribution, and redoxspeciation of plutonium (Pu) in the groundwater in thevicinity of the F-area seepage basins at the U.S. Departmentof Energy Savannah River Site (SRS) were examined. Alow 240Pu/239Pu ratio in the upstream control well signifiesa Pu source other than global fallout and indicates reactor-produced Pu. Elevated 240Pu/239Pu atom ratios downstreamfrom the seepage basins are due to the decay oftransplutonium isotopes, mainly 244Cm to 240Pu, whichwere generated at the SRS. Evidence suggests that themigration of basin-released Pu isotopes is minor. Rather,it is the transplutonium isotopes that migrate preferentiallydownstream and in the process decay to yield progenyPu isotopes. Size fractionation studies with cross-flow ultrafiltration show that <4% of the 239Pu or 240Pu isfound in the colloidal fraction, a finding that is consistent withthe higher Pu oxidation states observed in the SRSgroundwater. The observation of a low abundance of colloid-associated Pu in SRS groundwater cannot be extrapolatedto all sites, but is in contrast to the conclusions ofprior groundwater Pu studies at the SRS and elsewhere.This work is unique in its application of a novel combinationof sampling and processing protocols as well as its useof thermal ionization mass spectrometry for the detectionof Pu isotopes. This allows quantification of the Pusource terms and better determination of the ambient Pusize and redox speciation representative of in situ conditions.