Abstract
236U (t1/2=2.3×107 y) is formed as a result of thermal neutron capture by 235U. In naturally occurring U ores, where a high neutron flux is present from spontaneous fission of 238U, 236U/238U atom ratios are ∼10-4 ppm. In the natural Earth's crust, unaffected by nuclear fallout, these ratios are expected to be on the order of 10-8 ppm. Reactor-irradiated U, however, exhibits high 236U/238U atom ratios approaching 104 ppm. As a result, the presence of very small quantities of reactor-irradiated U will significantly enhance the 'background' 236U/238U atom ratio. When sufficiently elevated 236U/238U ratios are present, the determination of 236U/238U by rapid inductively coupled plasma mass spectrometric (ICPMS) methods is attractive. We have used sector ICPMS at medium resolving power (R=3440) to measure 236U/238U atom ratios with a determination limit of 0.2 ppm. The limiting factors in the measurement are the 235U1H+ isobar and background signal at m/z 236 arising from the 238U+ peak tail. Based upon the analysis of replicates and considerations of possible systematic errors, uncertainties of ±5% are found for 236U/238U atom ratios of 1-100 ppm. This procedure has been demonstrated in studies of anthropogenic 236U in the environment at three locations: (a) offsite soils from the vicinity of the Rocky Flats Environmental Technology site (Golden, Colorado, USA); (b) sediments from the Ashtabula River (Ohio, USA); and (c) sediments from the Mersey estuary (Liverpool, UK). In each of these three locations, definite plumes of elevated 236U/238U are identified and characterized. Maximum 236U/238U atom ratios observed in RFETS-vicinity soils, the Ashtabula River, and the Mersey Estuary are 2.8, 140, and 4.4 ppm, respectively.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 191-206 |
| Number of pages | 16 |
| Journal | Journal of Environmental Radioactivity |
| Volume | 67 |
| Issue number | 3 |
| DOIs | |
| State | Published - 2003 |
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Keywords
- U
- Ashtabula
- Contamination
- Inductively coupled plasma mass spectrometry
- Mersey estuary
- Plutonium
- Rocky flats
- Sediments
- Uranium
ASJC Scopus subject areas
- Environmental Science(all)
Cite this
Anthropogenic 236U at Rocky Flats, Ashtabula river harbor, and Mersey estuary : Three case studies by sector inductively coupled plasma mass spectrometry. / Ketterer, Michael E; Hafer, K. M.; Link, C. L.; Royden, C. S.; Hartsock, W. J.
In: Journal of Environmental Radioactivity, Vol. 67, No. 3, 2003, p. 191-206.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Anthropogenic 236U at Rocky Flats, Ashtabula river harbor, and Mersey estuary
T2 - Three case studies by sector inductively coupled plasma mass spectrometry
AU - Ketterer, Michael E
AU - Hafer, K. M.
AU - Link, C. L.
AU - Royden, C. S.
AU - Hartsock, W. J.
PY - 2003
Y1 - 2003
N2 - 236U (t1/2=2.3×107 y) is formed as a result of thermal neutron capture by 235U. In naturally occurring U ores, where a high neutron flux is present from spontaneous fission of 238U, 236U/238U atom ratios are ∼10-4 ppm. In the natural Earth's crust, unaffected by nuclear fallout, these ratios are expected to be on the order of 10-8 ppm. Reactor-irradiated U, however, exhibits high 236U/238U atom ratios approaching 104 ppm. As a result, the presence of very small quantities of reactor-irradiated U will significantly enhance the 'background' 236U/238U atom ratio. When sufficiently elevated 236U/238U ratios are present, the determination of 236U/238U by rapid inductively coupled plasma mass spectrometric (ICPMS) methods is attractive. We have used sector ICPMS at medium resolving power (R=3440) to measure 236U/238U atom ratios with a determination limit of 0.2 ppm. The limiting factors in the measurement are the 235U1H+ isobar and background signal at m/z 236 arising from the 238U+ peak tail. Based upon the analysis of replicates and considerations of possible systematic errors, uncertainties of ±5% are found for 236U/238U atom ratios of 1-100 ppm. This procedure has been demonstrated in studies of anthropogenic 236U in the environment at three locations: (a) offsite soils from the vicinity of the Rocky Flats Environmental Technology site (Golden, Colorado, USA); (b) sediments from the Ashtabula River (Ohio, USA); and (c) sediments from the Mersey estuary (Liverpool, UK). In each of these three locations, definite plumes of elevated 236U/238U are identified and characterized. Maximum 236U/238U atom ratios observed in RFETS-vicinity soils, the Ashtabula River, and the Mersey Estuary are 2.8, 140, and 4.4 ppm, respectively.
AB - 236U (t1/2=2.3×107 y) is formed as a result of thermal neutron capture by 235U. In naturally occurring U ores, where a high neutron flux is present from spontaneous fission of 238U, 236U/238U atom ratios are ∼10-4 ppm. In the natural Earth's crust, unaffected by nuclear fallout, these ratios are expected to be on the order of 10-8 ppm. Reactor-irradiated U, however, exhibits high 236U/238U atom ratios approaching 104 ppm. As a result, the presence of very small quantities of reactor-irradiated U will significantly enhance the 'background' 236U/238U atom ratio. When sufficiently elevated 236U/238U ratios are present, the determination of 236U/238U by rapid inductively coupled plasma mass spectrometric (ICPMS) methods is attractive. We have used sector ICPMS at medium resolving power (R=3440) to measure 236U/238U atom ratios with a determination limit of 0.2 ppm. The limiting factors in the measurement are the 235U1H+ isobar and background signal at m/z 236 arising from the 238U+ peak tail. Based upon the analysis of replicates and considerations of possible systematic errors, uncertainties of ±5% are found for 236U/238U atom ratios of 1-100 ppm. This procedure has been demonstrated in studies of anthropogenic 236U in the environment at three locations: (a) offsite soils from the vicinity of the Rocky Flats Environmental Technology site (Golden, Colorado, USA); (b) sediments from the Ashtabula River (Ohio, USA); and (c) sediments from the Mersey estuary (Liverpool, UK). In each of these three locations, definite plumes of elevated 236U/238U are identified and characterized. Maximum 236U/238U atom ratios observed in RFETS-vicinity soils, the Ashtabula River, and the Mersey Estuary are 2.8, 140, and 4.4 ppm, respectively.
KW - U
KW - Ashtabula
KW - Contamination
KW - Inductively coupled plasma mass spectrometry
KW - Mersey estuary
KW - Plutonium
KW - Rocky flats
KW - Sediments
KW - Uranium
UR - http://www.scopus.com/inward/record.url?scp=0037260463&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037260463&partnerID=8YFLogxK
U2 - 10.1016/S0265-931X(02)00186-8
DO - 10.1016/S0265-931X(02)00186-8
M3 - Article
VL - 67
SP - 191
EP - 206
JO - Journal of Environmental Radioactivity
JF - Journal of Environmental Radioactivity
SN - 0265-931X
IS - 3
ER -