Increased retention of americium in kidneys as compared with plutonium in an actinide wound contamination model in the rat

Abstract

Purpose: Americium-241 (²⁴¹Am) presents a potential risk for nuclear industry workers associated with reactor decommissioning and aging combustible materials. The purpose of this study was to investigate Am renal retention after actinide contamination by wounding in the rat.

Materials and methods: Anesthetized rats were contaminated with Mixed Oxide (MOX) (7.1% Plutonium [Pu] by mass and containing 27% Am as % total alpha activity), Pu or Am nitrate following an incision wound of the hind leg. Times of euthanasia ranged from 2 hours to 5 months after contamination. Pu and Am levels were quantified following radiochemistry and alpha-spectrophotometry.

Results: Initial data show that over the experimental period the proportion of Am in kidneys as a fraction of total kidney alpha activity was elevated as compared to MOX powder indicating a specific retention in this organ. The percentage of Pu was similar to the powder. After MOX contamination, kidney to liver ratios appeared to increase more markedly for Am (from 0.2 at 7 days to 0.6 at 90 days) as compared with Pu (0.1 at 7 days to 0.2 at 90 days). In accordance with tissue actinide retention the dose from Am to the kidney increases with time. For comparison, the ratio of estimated equivalent doses due to Am to kidney is 1.5-fold greater than for Pu (around 90 versus 60 mSv).

Conclusion: After actinide contamination of wounds, Am is concentrated in the kidneys as compared to Pu leading to potential exposure of renal tissue to both alpha particles and gamma radiation.

Keywords::

• Americium
• wound contamination
• kidney
• MOX

Acknowledgements

The authors wish to thank AREVA NC for financial support, Jean Piechowski for many fruitful discussions, Luc Doublet for Radioprotection advice, Stéphanie Lamart for help with the manuscript and dosimetric questions and Patrick Pochard for animal care.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.