Cladding Surface Temperature Limit for Fuel Element Aluminum-Alloy Cladding of Research and Test Reactors

Higher power density and thermal flux are needed for the research and test reactors both under construction and in research to improve the level of neutron flux. This makes the temperature of aluminum-alloy cladding increase continuously and approach its limit. The cladding surface temperature limit for aluminum-alloy cladding used in the research reactor was studied under normal operation condition（condition I） and anticipated operation occurrences（condition II）. It was indicated that for fuel elements with aluminum-alloy cladding used in research reactors, the mechanical property and the condition to prevent the coolant boiling are the main limited factors for cladding surface temperature under condition I. According to the design guidelines for condition II, the cladding integrity should be guaranteed and the highest temperature and cladding stress should be put under restriction, instead of the cladding surface temperature. However, the cladding surface temperature is relative to the highest temperature and cladding stress still, and it is should be focused.