Ranking the importance of nuclear reactions for activation and transmutation events

TL;DR

This paper compares three techniques for ranking nuclear reactions' importance in activation and transmutation, highlighting the advantages of the pathways based metric (PBM) for sensitivity analysis.

Contribution

It evaluates and compares three reaction ranking methods, advocating for the pathways based metric (PBM) as the most effective approach.

Findings

PBM is preferred over other methods for reaction importance ranking.

Different techniques can yield varying importance rankings.

The study enhances understanding of nuclear reaction sensitivity analysis.

Abstract

Pathways-reduced analysis is one of the techniques used by the Fispact-II nuclear activation and transmutation software to study the sensitivity of the computed inventories to uncertainties in reaction cross-sections. Although deciding which pathways are most important is very helpful in for example determining which nuclear data would benefit from further refinement, pathways-reduced analysis need not necessarily define the most critical reaction, since one reaction may contribute to several different pathways. This work examines three different techniques for ranking reactions in their order of importance in determining the final inventory, comparing the pathways based metric (PBM), the direct method and one based on the Pearson correlation coefficient. Reasons why the PBM is to be preferred are presented.