Analysis of Destructive and Nondestructive Assays of Irradiated LEU Fuel Material for the Validation of MCNP and Nuclear Forensic Methodologies.

Sean Martinson - Texas A&M University
Jenna Garcia - Texas A&M University
Isaac Haynes - Texas A&M University
Sunil Chirayath - Texas A&M University
Simrun Saini - Texas A&M University
Elisan Wagner - Texas A&M University

Researchers rely on the functionality and accuracy of Monte Carlo N-Particle (MCNP) to model complex problems such as nuclear reactors. Model accuracy can be validated by comparing simulated results against real world experiments or historical records. MNCP can provide support for radiological safety, criticality measurements, and even nuclear forensics. Nuclear forensics is a multi-disciplinary field that provides data and information concerning nuclear material which may have been used for illicit or unsanctioned activities. In 2021, Texas A&M University sent low enriched uranium (LEU) UO2 material to the University of Missouri Research Reactor (MURR) to be irradiated. An MCNP simulation was conducted according to the detailed irradiation history of the fuel material. Once the irradiation and necessary cooling were completed, the irradiated fuel material was transferred back to Texas A&M University and isotopically analyzed through destructive and nondestructive methods, specifically, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and High-Purity Germanium (HPGe), respectively. Comparisons of simulated and experimental concentrations included the following nuclides: 95Zr, 95Nb, 103Ru, 140Ba, 140La, 141Ce, 144Ce, 133Cs, 134Cs, 135Cs, 137Cs, 136Ba, 138Ba, 149Sm, 150Sm, 152Sm, 153Eu, 154Eu, and plutonium (239Pu, 240Pu, and 241Pu). The simulation and experimental results together support nuclear forensic methodologies of interdicted or inspected materials. These methodologies seek to determine key parameters of source nuclear material, such as: the type of reactor which irradiated the material, the burnup of the material, and the time since the material was discharged from the reactor.