In thermal hydraulic design of nuclear reactor cores it is of interest to know the probability for 0, 1, 2, . . D hot channels and/or cladding and fuel hot spots [i.e., channels (spots) in the core at which temperature limits are exceeded]. Furthermore, it might even be advantageous to design a core for a maximum permissible number of such hot channels (spots) by comparing the safety considerations with the plant efficiency. Numerical procedures available in the open literature using statistical methods are currently restricted to the evaluation of hot channel or hot spot factors corresponding to the requirement that either the most exposed nominal channel (spot) or all channels (spots) in the entire core do not exceed imposed temperature or heat flux limits. This paper describes a method, hereafter referred to as “Method of Correlated Temperatures,” which enables an evaluation to be made of the entire probability distribution of the number of hot channels as a function of the corresponding hot channel factor. A quantitative comparison is performed between the proposed method and other procedures currently in use by applying the different methods to a hot channel factor analysis of a simplified hypothetical LMFBR-type core.
