241Am INGROWTH AND ITS EFFECT ON INTERNAL DOSE

Abstract

Generally, plutonium has been manufactured to support commercial and military applications involving heat sources, weapons, and reactor fuel. This work focuses on three typical plutonium mixtures while observing the potential of Am ingrowth and its effect on internal dose. The term "ingrowth" is used to describe Am production due solely to the decay of Pu as part of a plutonium mixture, where it is initially absent or present in a smaller quantity. Dose calculation models do not account for Am ingrowth unless the Pu quantity is specified. This work suggested that Am ingrowth be considered in bioassay analysis when there is a potential of a 10% increase to the individual's committed effective dose. It was determined that plutonium fuel mixtures, initially absent of Am, would likely exceed 10% for typical reactor grade fuel aged less than 30 y; however, heat source grade and aged weapons grade fuel would normally fall below this threshold. Although this work addresses typical plutonium mixtures following separation, it may be extended to irradiated commercial uranium fuel and is expected to be a concern in the recycling of spent fuel.

Americium biodistribution in rats after wound contamination with different physicochemical forms in the presence or absence of plutonium: analyses using STATBIODIS

“…Mixtures of actinides like MOX generally contain Pu-241 that decays into Am-241 with a physical half-life of 14.3 years. Hence, proportions of Am-241 can continuously increase not only in contaminated materials but also after intake in the body (Khokhryakov and Yefimov 2007, Suslova et al 2013, Konzen 2016. Like other actinides, Am-241 is an alphaemitter with a physical half-life of 432.6 years.…”

Actinide bioimaging in tissues: Comparison of emulsion and solid track autoradiography techniques with the iQID camera

“…An archival sample of lung tissue had been collected after contamination by inhalation with MOX (Sample identification: « IPAU 7053 » in Table 1). Ageing of this nuclear fuel resulted in the ingrowth of Am-241 [42, 43]. At the time of acquisition, 32% of Am-241 was expected to have been generated in activity from the initial MOX compound.…”