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Conference Article: Irradiation of High Temperature Reactor Fuel Pebbles At VHTR Conditions In The HFR Petten

Michael A. Fütterer, Harald Lohner, Rainer Conrad, European Commission, Joint Research Center, Institute for Energy, Petten, THE NETHERLANDS; Klaas Bakker, Sander de Groot, Carla M. Sciolla, EC, Nuclear Research and Consultancy Group Petten, THE NETHERLANDS

Abstract

The irradiation experiment HFR-EU1bis aims at testing 5 spherical High Temperature Reactor (HTR) fuel pebbles with TRISO coated particles for their potential for very high temperature performance and high burn up. The irradiation will start on 10 September 2004 in the HFR Petten for up to 350 fpd. The main objective of HFR-EU1bis is the demonstration of the feasibility of low particle failure rates at very high temperature (relevance for the Generation IV concept VHTR) and burn-up for the existing German LEU-TRISO fuel. The design of HFR-EU1bis is based on previous experience of HTR fuel irradiations within the European Union [1]. In the rig, the pebbles are double contained and their temperature is controlled by adjusting He/Ne mixtures in the gas gaps. The two containments remain normally closed with stagnant gas mixtures. They can be purged to modify the gas mixtures for temperature adjustment and for taking gas samples to monitor release of gaseous fission products. To accelerate the burn-up, the neutron spectrum is strongly moderated using a custom filler element with increased water fraction. Cycle-by-cycle turning of the experiment by 180º reduces radial gradients in neutron fluence and burn-up across the pebbles. A vertical displacement unit (VDU) enables an optimized position of the fuel pebbles with evolving neutron flux buckling of the reactor. This paper describes the irradiation facility and its ancillary equipment. First irradiation results will be presented orally during the HTR 2004 conference.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Proceedings of the Conference on High Temperature Reactors, Beijing, China, September, 22-24, 2004
International Atomic Energy Agency, Vienna (Austria)
HTR-2004, pp:1-15