Reactor physics analysis of a Source-driven TRIGA configuration in subcritical domain

Abstract

Subcritical reactors (SCR) are systems that are driven by an external source to achieve stationary state. Domain-wide parametric study was performed elucidating the behavior of these systems on account of subcriticality level and source properties. Various configurations of the Philippine Research Reactor-1 Subcritical Assembly for Training, Education, and Research were modelled in MCNP6.2 as a representative SCR. Here we report the behavior of integral and distributed physics parameters. Results indicate that βeff is constant, while prompt decay constant (α), subcritical multiplication factor (ks), and neutron source efficiency (Seff) increases, and Λeff decreases as keff increases. Seff shows non-uniform behavior when keff>0.95 suggesting that system response vary widely within this range. Furthermore, softer source spectrum resulted to higher performance metrics when located within the core, however at periphery, harder spectrum is advantageous. The findings clarify the physics of SCRs making possible system optimization and design of experiments targeting specific validation metrics.