Implementation of Depletion Architecture in the MAMMOTH Reactor Physics Application

摘要

Nuclear fuel experiments conducted at the Transient Reactor Test Facility (TREAT) willbe analyzed with the MAMMOTH reactor physics application, currently under developmentat Idaho National Laboratory. MAMMOTH natively couples with the BISON,RELAP-7, and Rattlesnake applications within the MOOSE framework. The methodscurrently implemented allow for simulating the irradiation of fuel from the beginning oflife in a nuclear reactor until it is placed in TREAT for fuel testing using the same finiteelement mesh throughout the analysis thereby retaining a very high level of resolutionand fidelity. The calculation of the isotopic distribution in fuel requires the solution to thedecay and transmutation equations coupled to the neutron transport equation. This workfocuses on two significant improvements to the MAMMOTH micro-depletion capability.First, the depletion architecture within MAMMOTH is modified to improve the flexibilityand speed of burnup calculations. The results of various benchmark tests demonstrate theaccuracy of the modified implementation. The second improvement involves the expansionof the data functionality. MAMMOTH can now read the decay data files used bythe Oak Ridge Isotope Generation (ORIGEN) code, thus enabling access to data of morethan 1,600 isotopes. Comparison of ORIGEN and MAMMOTH for a selected benchmarkproblem was performed. Both codes yield very similar results, with differences of 0.03%that can be attributed to differences in precision between the two codes. Future work willfocus on comparisons between MAMMOTH and ORIGEN for more complex problems.