Radiation effects in actinide compounds with the fluorite structure

Radiation damage in actinide compounds with the fluorite structure and especially on UO2 and (U, Pu)O2 has been extensively studied for more than 50 years in view of the better understanding of the behavior of these materials as fuel for nuclear power reactors. The studies cover single effects from various damage sources (mostly by ion implantation) up to combined effects in e.g. irradiated nuclear fuels. The second practical issue related to the understanding of the damage formation in UO2 but also in mixed oxides fuels (MOX) lies in the forecast of its long term behavior (several millenaries and beyond). The minor actinides present in the spent fuel will produce alpha-damage and radiogenic helium that will impact the long term properties of the spent fuel. The prediction of the long term behavior of such compounds is therefore of major importance for safety assessments of storage/disposal facilities. A third aspect of radiation damage in minor actinide (MA) compounds (with the fluorite structure) becomes more and more important and namely the use of fuel with MA. The key issue for reducing the MA radiotoxicity is their partitioning and transmutation in fast neutron reactors or accelerator driven systems. This implies to know how these compounds will behave not only against their self-irradiation damage build-up but also how they will be affected by their irradiation in reactor systems. Basic processes of energy loss are described and stopping power and ranges of various ions/particles defined for the specific case of UO2. The radiation effects produced by these ions/particles are subsequently described as well as their impact on the physico-chemical properties of the nuclear fuel UO2. The PuO2 has also been studied more in detail as radio-isotopic thermal generator (RTG) to be used for satellite batteries for example but also as stockpile from weapon material after the conversion into oxide. Some studies on the aging of PuO2 due to alpha-decay and helium formation are discussed hereafter. As a global outcome of studies concerning the fluorite structure based actinide compounds it could be shown that they exhibited generally a remarkable resistance against radiation effects, hardly ever amorphizing. Nevertheless the stability of these compounds degrades in the order PuO2, AmO2, CmO2, CfO2 as can be also observed for their thermal stability. Also the irradiated fuel UO2 and MOX shows a remarkable resistance to radiation damage build-up considering the tough irradiation conditions.

WISS Thierry;  KONINGS Rudy; 

2013-08-20

NOVA SCIENCE PUBLISHERS, INC.

JRC70197

978-1-62417-458-2,