A preliminary research to develop the DNBR limit using a sampled statistics method

The departure from nucleate boiling (DNB) design basis is one of the important reactor core thermal-hydraulic design bases. To avoid the DNB phenomenon, the departure from nucleate boiling ratio (DNBR) design limit corresponding to a certain confidence level should be developed. Thus, a research using a sampled statistics method was conducted to develop the DNBR limit. A reasonable design flow was proposed in this paper, the parameters to be sampled included almost all parameters influencing the DNBR, for example, the power distribution, model uncertainties, state parameters. A coupled code was developed to execute the sampled job and to carry out the DNBR calculation. Meanwhile, the typical LOFA was selected to evaluate the DNBR margin. The results showed that the sampled statistics methodology described in this paper has practical applications. (author)