Review Overview of experimental programs on core melt progression and fission product release behaviour B.J. Lewis a, * , R. Dickson b , F.C. Iglesias c , G. Ducros d , T. Kudo e a Royal Military College of Canada, P.O. Box 17000, Kingston, Ontario, Canada K7K 7B4 b Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, Canada K0J 1J0 c Candesco Corporation, 230 Richmond Street, 10th Floor, Toronto, Ontario, Canada M5V 1V6 d Commissariat à l’Energie Atomique, CEA Cadarache, Building 315, BP 01, 13108 Saint Paul lez Durance, France e Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai-mura, Ibaraki-ken 319-1195, Japan article info Article history: Received 23 May 2008 Accepted 14 July 2008 abstract An overview of experimental programs that have been conducted to better understand core melt progres- sion phenomena and fission product behaviour during severe reactor accidents in light water reactors is presented. This discussion principally focuses on the melting and liquefaction of core materials at differ- ent temperatures, materials oxidation and relocation, hydrogen generation behaviour, and the release and transport of fission products and aerosols. A comparison of fission product release results from annealing and in-reactor experiments is also presented. Ó 2008 Elsevier B.V. All rights reserved. Contents 1. Introduction ......................................................................................................... 126 2. Review of melt progression and fission product release experiments ........................................................... 127 2.1. Single-effects (out-of-pile) fission product release experiments .......................................................... 129 2.1.1. ORNL experiments ....................................................................................... 129 2.1.2. CEA-Grenoble experiments ................................................................................ 129 2.1.3. JAEA experiments ........................................................................................ 134 2.1.4. AECL-CRL experiments .................................................................................... 134 3. Degraded core accident phenomena ...................................................................................... 134 3.1. Comparison of integral experiments ................................................................................ 137 4. Fission product release behaviour ........................................................................................ 139 5. Conclusions .......................................................................................................... 141 Acknowledgments .................................................................................................... 142 References .......................................................................................................... 142 1. Introduction Numerous in-pile [1–27] and out-of-pile experiments [28–39] have been conducted to better understand light water reactor (LWR) severe accident progression following the accident at the Three Mile Island Unit 2 (TMI-2) nuclear power plant. These exper- iments have principally focused on high temperature core melt progression and fission product release behaviour. Specifically, the experiments were designed to investigate: (i) how the core loses its original geometry as a result of interactions between core materials and fuel liquefaction; (ii) the relocation behaviour of the core with melt formation leading to partial core blockage, fuel deb- ris beds and molten pools; (iii) how much hydrogen is produced by the steam oxidation of core materials with relocation; (iv) the influence of core degradation on the release, transport and deposi- tion of fission products and aerosols; and (v) the fragmentation of the degraded core with cool down and/or quenching [40–49]. This paper reviews previous separate-effects and integral-ef- fects experiments conducted to better understand core melt pro- gression phenomena (see Section 2). The understanding and experience gained in these various experiments for core melt phe- nomena (Section 3) and fission product release behaviour (Section 4) are discussed and compared. This discussion is also presented in light of the phenomena inferred from examination of the damaged TMI-2 reactor core [16]. 0022-3115/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jnucmat.2008.07.005 * Corresponding author. Tel.: +1 613 541 6611; fax: +1 613 542 9489. E-mail address: lewis_b@rmc.ca (B.J. Lewis). Journal of Nuclear Materials 380 (2008) 126–143 Contents lists available at ScienceDirect Journal of Nuclear Materials journal homepage: www.elsevier.com/locate/jnucmat