This paper will provide an update on results from the feasibility study and discuss the attributes of the coated Mo cladding design to meet the challenging requirements for improving fuel tolerance to severe loss of coolant accidents. | Evaluations of Mo-alloy for light water reactor fuel cladding to enhance accident tolerance EPJ Nuclear Sci. Technol. 2 5 2016 Nuclear Sciences B. Cheng et al. published by EDP Sciences 2016 amp Technologies DOI epjn e2015-50060-7 Available online at http REGULAR ARTICLE Evaluations of Mo-alloy for light water reactor fuel cladding to enhance accident tolerance Bo Cheng1 Peter Chou1 and Young-Jin Kim2 1 Electric Power Research Institute EPRI Palo Alto CA 94304 USA 2 GE Global Research Center Schenectady NY 12309 USA Received 21 September 2015 Received in final form 26 November 2015 Accepted 3 December 2015 Published online 1 February 2016 Abstract. Molybdenum based alloy is selected as a candidate to enhance tolerance of fuel to severe loss of coolant accidents due to its high melting temperature of 2600 C and ability to maintain sufficient mechanical strength at temperatures exceeding 1200 C. An outer layer of either a Zr-alloy or Al-containing stainless steel is designed to provide corrosion resistance under normal operation and oxidation resistance in steam exceeding 1000 C for 24 hours under severe loss of coolant accidents. Due to its higher neutron absorption cross-sections the Mo-alloy cladding is designed to be less than half the thickness of the current Zr-alloy cladding. A feasibility study has been undertaken to demonstrate 1 fabricability of long thin wall Mo-alloy tubes 2 formability of a protective outer coating 3 weldability of Mo tube to endcaps 4 corrosion resistance in autoclaves with simulated LWR coolant 5 oxidation resistance to steam at 1000 1500 C and 6 sufficient axial and diametral strength and ductility. High purity Mo as well as Mo La2O3 ODS alloy have been successfully fabricated into 2-meter long tubes for the feasibility study. Preliminary results are encouraging and hence rodlets with Mo-alloy cladding containing fuel pellets have been under preparation for irradiation at the Advanced Test Reactor ATR in Idaho .
