Explicit Modeling of B4C in Neutron Absorber Plates with SCALE

Integral Experiment Request 554 (IER-554), a critical experiment that will use Boralcan absorber plates, will be performed using the Sandia Pulsed Reactor Facility/Critical Experiments apparatus at Sandia National Laboratories to obtain critical benchmark data for neutron absorbers and investigate how they interact with neutrons. The present work focuses on the explicit modeling of B4C in neutron absorber plates that will be used in the IER-554 experiment-specifically, the non-homogeneity of B4C powder particles within the aluminum matrix. This neutron absorber is normally modeled as a homogeneous mixture, but metallographic reports show that B4C powder particles are not necessarily uniformly distributed. Therefore, the purpose of the present work is to determine whether the conventional homogenous model of B4C and aluminum provides an accurate approximation or if a more realistic representation of B4C powder particle distribution is necessary, while maintaining a constant mass of B4C. Modeling was accomplished via the SCALE KENO-VI criticality calculation module. To account for the randomness of the B4C powder particle distribution, Sampler, a module within SCALE, was used. Additionally, Python was used to generate random sizes and locations of the geometries that Sampler could not generate, further enhancing randomness in the model. The results indicate that the various representations of B4C do not significantly influence keff, supporting the validity of the current homogeneous modeling method. Future work should explore more randomized geometries (including stochastic geometries) and incorporate a variety of different shapes to develop a more realistic model of the B4C powder particles.