Evaluation of Effective Delayed Neutron Fraction Techniques in MC21

摘要

A set of benchmark evaluations has shown that the NFP estimator for β_(eff) outperforms two of the other methods frequently implemented by MC21 users. The comparisons also provided an opportunity to identify and understand why the k-ratio and AIFP methods perform poorly for specific classes of problems. The k-ratio and AIFP methods depend upon relative stationarity of the flux and reaction rates with perturbations to the fission spectrum. Because the MC21 implementation of NFP does not rely on such an assumption, it is more generally applicable.