AUTHOR=He Donghao , Zhang Tengfei , Liu Xiaojing 

TITLE=The Application of the Combined Fission Matrix Theory in Fast Reactors

JOURNAL=Frontiers in Energy Research

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2021.766449

DOI=10.3389/fenrg.2021.766449

ISSN=2296-598X

ABSTRACT=<p>The combined fission matrix theory is a recently-developed hybrid neutron transport method. It features high efficiency, fidelity, and resolution whole-core transport calculation. The theory is based on the assumption that the fission matrix element <italic>a</italic><sub><italic>i</italic>,<italic>j</italic></sub> is dominated by the property of the destination cell <italic>i</italic>. This assumption can be well explained in thermal reactors, and the combined fission matrix method has been validated in a series of thermal neutron system benchmarks. This work examines the feasibility of the combined fission matrix theory in fast reactors. The European Sodium Fast Reactor is used as the numerical benchmark. Compared to the Monte Carlo method, the combined fission matrix theory reports a 64 pcm <italic>k</italic><sub><italic>eff</italic></sub> difference and 8.3<italic>%</italic> 2D RMS error. The error is much larger than that in thermal reactors, and the correction ratio cannot significantly reduce the material discontinuity error in fast reactors. Overall, the combined fission matrix theory is more suited for thermal reactor transport calculations. Its application in fast reactors needs further developments.</p>