BENCHMARKING OF THE RAPID TOOL FOR A SUBCRITICAL FACILITY

The RAPID (Real-time Analysis for Particle transport and In-situ Detection) tool is benchmarked using the U.S. Naval Academy’s subcritical reactor (USNA-SCR) facility. RAPID is a tool capable of real-time calculation of the system eigenvalue, subcritical multiplication, axially-dependent, pin-wise, fission distribution, and determination of detector responses. RAPID utilizes a Multi-stage Response- function Transport (MRT) approach using the Fission Matrix method to perform fixed-source, eigenvalue, and subcritical multiplication calculations and the adjoint function methodology to calculate detector responses. RAPID is enabled to do real-time calculations by utilizing databases of pre-calculated response coefficients. RAPID’s real-time calculation capability is particularly important for nuclear materials monitoring and safeguards applications. The USNA-SCR contains 268 annular natural uranium fuel rods, arranged in a hexagonal lattice, placed in a tank of water. The USNA-SCR is driven by a PuBe source located at the center of the fuel bundle. The neutron measurements were performed with a 3He proportional counter within the annulus of the fuel pins. The set of measurements include cross-core radial slices at fixed axial positions. Measured detector responses are compared with calculated reaction rates of a fixed-source MCNP Monte Carlo calculation. RAPID calculations are performed for eigenvalue calculations and it’s results are compared with a reference MCNP Monte Carlo calculation.