Quantification of actinide α-radiation damage in minerals and ceramics

Farnan, I. and Cho, H. and Weber, W. J. (2007) Quantification of actinide α-radiation damage in minerals and ceramics. Nature, 445 (7124). pp. 190-193. DOI 10.1038/nature05425

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Abstract

There are large amounts of heavy α-emitters in nuclear waste and nuclear materials inventories stored in various sites around the world1. These include plutonium and minor actinides such as americium and curium. In preparation for geological disposal there is consensus2 that actinides that have been separated from spent nuclear fuel should be immobilized within mineral-based ceramics rather than glass2-4 because of their superior aqueous durability and lower risk of accidental criticality. However, in the long term, the α-decay taking place in these ceramics will severely disrupt their crystalline structure2-4 and reduce their durability5,6. A fundamental property in predicting cumulative radiation damage is the number of atoms permanently displaced per α-decay. At present, this number is estimated to be 1,000-2,000 atoms/a in zircon4. Here we report nuclear magnetic resonance, spin-counting experiments that measure close to 5,000 atoms/a in radiation-damaged natural zircons. New radiological nuclear magnetic resonance measurements on highly radioactive, 239Pu zircon show damage similar to that caused by 238U and 232Th in mineral zircons at the same dose, indicating no significant effect of half-life or loading levels (dose rate). On the basis of these measurements, the initially crystalline structure of a 10 weight per cent 239 Pu zircon would be amorphous after only 1,400 years in a geological repository (desired immobilization timescales are of the order of 250,000 years). These measurements establish a basis for assessing the long-term structural durability of actinide-containing ceramics in terms of an atomistic understanding of the fundamental damage event.

Item Type: Article
Uncontrolled Keywords: 2007 AREP IA53 2007 P
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Nature
Volume: 445
Page Range: pp. 190-193
Identification Number: 10.1038/nature05425
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:02
Last Modified: 23 Jul 2013 10:07
URI: http://eprints.esc.cam.ac.uk/id/eprint/284

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