International Conference Nuclear Energy for New Europe 2004 Nuclear Energy for New Europe 2004 Nuclear Energy for New Europe 2004 Nuclear Energy for New Europe 2004 Portorož • Slovenia • September 6-9 port2004@ijs.si www.drustvo-js.si/port2004 +386 1 588 5247, fax +386 1 561 2276 PORT2004, Nuclear Society of Slovenia, Jamova 39, SI-1000 Ljubljana, Slovenia 209.1 Three-Batch Reloading Scheme for IRIS Reactor Extended Cycles Radomir Ječmenica, Dubravko Pevec, Davor Grgić University of Zagreb Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia radomir.jecmenica@fer.hr , dubravko.pevec@fer.hr , davor.grgic@fer.hr ABSTRACT To fully exploit the IRIS reactor optimized maintenance, and at the same time improve fuel utilization, a core design enabling a 4-year operating cycle together with a three-batch reloading scheme is desirable. However, this requires not only the increased allowed burnup but also use of fuel with uranium oxide enriched beyond 5%. This paper considers three-batch reloading scheme for a 4-year operating cycle with the assumptions of increased discharge burnup and fuel enrichment beyond 5%. Calculational model of IRIS reactor core has been developed based on FER FA2D code for group constants generation and NRC’s PARCS nodal code for global core analysis. Studies have been performed resulting in a preliminary design of a three-batch core configuration for the first cycle. It must be emphasized that this study is outside the current IRIS licensing efforts, which rely on the present fuel technology (enrichment below 5%), but it is of long-term interest for potential future IRIS design upgrades. 1 INTRODUCTION The International Reactor Innovative and Secure (IRIS), an integral, modular, medium size (335 MWe) PWR, has been under development since the turn of the century by an international consortium led by Westinghouse and including over 20 organizations from ten countries [1]. Maintenance of IRIS reactor has been optimized to enable extended operating cycles up to four years [2]. Different IRIS reactor fuel management options have been examined with the assumption of current enrichment licensing limitation (less than 5% enriched uranium oxide) [3], leading to a two-batch reloading scheme. To fully exploit the IRIS optimized maintenance, and at the same time to improve fuel utilization, a core design enabling a 4-year operating cycle together with a three-batch reloading scheme is desirable. However, this requires not only the increased allowed burnup but also use of fuel with uranium oxide enriched beyond 5%. This paper considers three-batch reloading scheme for 4-year operating cycle with the assumptions of increased discharge burnup and fuel enrichment beyond 5%. Studies have been performed resulting in development of a preliminary three-batch core design. It must be emphasized that this study is outside the current licensing efforts, but it is of long-term interest for potential future IRIS design upgrades. Development of a three-batch reloading scheme for IRIS reactor extended cycles is described in Section 2. Calculational model of the IRIS reactor core is given in Section 3. A preliminary three-batch core configuration for the first cycle of IRIS reactor is presented in Section 4. Conclusions are given in Section 5.