| Idaho State University’s Aerojet-General Nucleonics 201 (AGN-201) is a low-power
thermal reactor used for instruction and research. This thesis presents the results of a sensitivity
analysis investigating changes in the reactor’s effective multiplication factor (k-effective) under
various material perturbations and geometric configurations applied to the reactor core. The
analysis includes weight-percent perturbations to the isotopic compositions of the uranium fuel
and changes in the boron impurity concentration within the graphite reflector. Cadmium
impurities within the uranium fuel are also examined due to cadmium’s high neutron absorption
cross section and its potential influence on system criticality.
Computational studies are performed using two independent Monte Carlo particle
transport codes: MCNP (Monte Carlo N-Particle) and SERPENT. Both MCNP and SERPENT
reactor models include an additional quarter fuel plate embedded within a polyethylene disk
above the core, consistent with a post-construction modification made to increase reactivity.
Various core geometries are simulated, and the resulting changes in 𝑘-effective are analyzed. A
key component of this thesis is the comparison of results between MCNP and SERPENT, which
serves as part of the overall code validation effort. This cross-code comparison evaluates the
consistency and sensitivity responses of both models, providing confidence in the predictive
accuracy of Monte Carlo methods applied to the AGN-201 reactor system.
Keywords: AGN-201 Reactor, Neutron Transport Modeling, MCNP Simulation, SERPENT Simulation, Sensitivity Analysis, Uncertainty Quantification, Criticality |