JRC Research on High Temperature Reactor Fuels

Within the Generation IV International Forum (GIF), considerable efforts are devoted in Europe to research and development of the (Very) High Temperature Reactor system. This is one of the six reactor systems which GIF had selected and recommended for further development, in particular for industrial process heat applications. The Joint Research Centre (JRC), through its Institutes in Petten and in Karlsruhe, disposes of the complete HTR fuel qualification string required for the development, qualification and licensing of HTR fuels including fabrication and quality control, the possibility of irradiation testing, post-irradiation examinations and safety testing. At the JRC, a vigorous experimental program is being pursued the goal of which is to irradiate HTR fuels (in particular pebbles available from external sources) at high temperature to high burn-ups in the High Flux Reactor Petten and to measure and confirm low fission product release rates. Since 2002, two such irradiation tests have been completed and several others are under preparation. The irradiations are followed by measurement of fission product release during out-of-pile simulation of accident conditions, again to confirm low release rates. For this purpose, a cold finger device (KÜFA), is being used to perform heating experiments on several irradiated HTR fuel pebbles from the AVR in Jülich, Germany, as well as from dedicated irradiation campaigns in the HFR. In KÜFA, gaseous fission products (FPs) released during the high temperature post-irradiation tests are collected in a liquid-nitrogen-cooled charcoal trap, while volatiles are plated out on a cooled condensation plate. In both cases, a quantitative measurement of the release is obtained by gamma spectroscopy. At present, interest in HTR fuels concentrates on UO2, which will undoubtedly be the fuel deployed in the next HTR. However, plutonium oxide fuel is considered in a further step, for the incineration of excess stocks of military Pu, and even potentially for transmutation of minor actinides (¿deep burn¿). It is the reason why the development of a transuranium elements - bearing fuel fabrication and characterisation chain is being pursued at ITU. Future work may cover experimental production of ¿deep burn¿ fuel as well as thorium fuel. In this paper, we present an overview (including the most recent status of results) of: - two HFR irradiation tests including fission gas release measurements; - experimental results from KÜFA tests as well as the status of the on-going development of new experimental facilities (for corrosion tests under simulated accident conditions involving air or water ingress, and for the spectroscopic analysis of particle integrity); - the status of achievements in the fabrication of Pu-bearing kernels and coated particles, together with their fuel characterisation; - results from fuel fragmentation tests with dummy particles. It will be also highlighted how the research pursued by the JRC is fully integrated in the European goals and priorities set up by SNE-TP and its Strategic Research Area and Deployment Strategy, and also within the broader international context.

HAAS Didier;  FUETTERER Michael;  LAURIE Mathias;  MARMIER Alain;  RONDINELLA Vincenzo;  SOMERS Joseph; 

2010-06-28

European Nuclear Society

JRC54324