Plutonium from Mayak:  Measurement of Isotope Ratios and Activities Using Accelerator Mass Spectrometry

Abstract

Accelerator mass spectrometry (AMS) has been used to measure Pu activities and 240 Pu/ 239 Pu isotope ratios in samples contaminated by releases from the Mayak nuclear installation. Determination of Pu isotopes in high-level samples indicated that the ratio of 240 Pu/ 239 Pu in waste has increased toward the present. The lowest 240 Pu/ 239 Pu atom ratios, 0.012-0.024, were found at the Asanov Swamp, where the primary source of contamination was discharge of intermediate-level radioactive waste between 1949 and 1951. The highest ratios, 0.06-0.29, were found in industrial reservoirs contaminated by various sources of waste up to the present day. Measurement of Pu isotopes in low-level samples collected from the Techa, Iset, and Ob Rivers showed that while activity levels decrease with distance from Mayaksfrom 2000 Bq/kg at 7 km downstream to less than 1 Bq/kg sediment at 250 kms 240 Pu/ 239 Pu isotope ratios increase. Results suggest that most of the plutonium in the Upper Techa River originates from the early waste discharges, although enhanced atom ratios in surface sediments downstream (0.035-0.099) indicate a contribution from other sources. On the basis of procedural blanks, detection limits for AMS were below 1 fg of Pu.

Importance of the process of mass-exchange between main stream of a river and underflow for modelling of concentration of radioactive substances in river water and bed sediments

“…The observed data on water contamination at the 44th km were used as data input. One can see that the observed concentrations of radionuclides in water at the 44th km are in a good agreement with those calculated through the formula (11) if the values of 'C 0 ' and 'k' from Table 2 are used (the discrepancy varies within 0.74 -4%).…”

Plutonium isotopes as tracers for ocean processes: A review

“…Hrnecek, E., Steier, P., Wallner, A., 2005 (Beasley et al, 1998;Yamamoto et al, 2004) Chernaya Bay, underwater nuclear tests 0.0320 ± 0.0024 0.023 ± 0.009 Smith et al, 2000b) Releases from the nuclear industry (Oughton et al, 2000;Skipperud et al, 2004;Børretzen et al, 2005;Lind et al, 2006;GauthierLafaye et al, 2008;Skipperud et al, 2009) Accidental releases Chernobyl accident, 19860.38 ± 0.07 0.42 ± 0.04 (Boulyga et al, 1997Wendt et al, 1999;Muramatsu et al, 2000;Boulyga and Becker, 2002 …”

The distribution and history of nuclear weapons related contamination in sediments from the Ob River, Siberia as determined by isotopic ratios of Plutonium, Neptunium, and Cesium

“…The isotopic ratios observed at both locations are quite low and easily distinguishable from global fallout. Additionally, 24°Pu¡239pu ratios provided by Oughton, Fifield et al (2000) for soils and sediments proceeding downstream from Mayak to its confluence with the Iset River generally increase and approach a value -0.10, suggesting the influence of global .. I'…”

“…soils, sediments, ice and water). (HASL 1973;Koide, Goldberg et al 1977;Koide, Michel et al 1979;Perkins and Thomas 1980;Koide, Michel et al 1982;Buesseler, Livingston et al 1985;Koide, Bertine et al 1985;Buesseler and Anonymous 1986;Buesseler and Sholkovitz 1987;Buesseler and Sholkovitz 1987;Trapeznikov, Pozolotina et al 1993;Yamamoto, Tsukatani et al 1996;Yamamoto, Tsumura et al 1996;Buesseler 1997, Beasley, Kelley et al 1998Kelley, Bond et al 1998;Yamamoto, Hoshi et al 1999;Muramatsu, Ruhm et al 2000;Oughton, Fifield et al 2000). The available isotopic information for each potential source to Ob River sediments is discussed below…”

“…Available data that document the isotopic composition of materials at Mayak consist of soils and sediments collected from the Techa River and the region contaminated by the 1957 Kyshtym explosion (the East Ural Trace or EURT) (Trapeznikov, Pozolotina et al 1993;Beasley, Kelley et al 1998;Oughton, Fifield et al 2000). Where data overlap (see Table 2:3), there is good agreement (i.e.…”