Steady-State Performance Analysis of a Dual-Cladding Design for Accident Tolerance Fuel

Abstract The 2011 Fukushima Daiichi accident has highlighted the fatal weaknesses of the currently using fuel system, global interest has expanded in exploring an alternative accident-tolerance fuel (ATF) with enhanced performance during not only accident conditions but also normal operation. Therefore, this paper proposed a novel Dual-Cladding design concept to decrease the probability of cladding failure and increase the accident-tolerance ability of fuel rods in 200MW Nuclear Heating Reactor II (NHR200-II). Compared to the single cladding of conventional PWR fuel, the Dual-Cladding rod has bilayer zirconium-based alloy cladding, which means that an extra zircalloy cladding is added outside the inner zircalloy cladding and the total diameter of the rod is unchanged. This concept can directly decrease the probability of cladding failure to 10% of typical value under normal operation according to relevant probabilistic risk assessment theory and increase fuel coping time during accident conditions in NHR200-II. On the other hand, enrichment of the pellet will be adjusted in this design. And there are also some challenges needed to be addressed, such as heat transfer between the two layers of cladding and fabrication of the rod. This paper showed the basic design of the Dual-Cladding fuel rod and analyzed thermal behavior under normal operation. This concept provides a fresh and economical way to improve the accident-tolerance ability of currently using fuel in NHR200-II.