Experimental Validation of RAPID Based on JSI TRIGA Reactor Dosimetry

The RAPID (Real-time Analysis Particle-transport and In-situ Detection) Code System, based on the Multi-stage Response-function Transport (MRT) methodology, utilizes the Fission Matrix (FM) and Detector Response Function (DRF) approaches for calculation of the fission neutron source and detector responses / doses respectively. The MRT methodology decouples the analysis of a nuclear system in several physics-based stages, for which response functions or coefficients are pre-calculated as a function of problem-relevant parameters (e.g., control rod positions for TRIGA reactors). These response functions are then coupled in real-time via linear systems of equations for any input configuration. As part of an ongoing collaboration between Virginia Tech and the Jožef Stefan Institute (JSI), the code is undergoing experimental validation and benchmarking using the JSI TRIGA Mark-II reactor. RAPID has already been validated at critical condition for different core configurations. In this work, RAPID is being validated for dosimetry calculations using in-core foils of Aluminum (99.9 wt.%) – Gold (0.1 wt.%) dosimeters. This paper compares RAPID results to both measurements and a standard 3-D Serpent Monte Carlo prediction. The aim of this work is to demonstrate the ability of RAPID for accurately calculating both detailed core fission density distribution and detector responses/doses in real-time (seconds), making the code a useful tool, e.g. for dosimetry calculations, pressure vessel fluence calculations, and design of experiments in a fraction of the time required using state-of-the-art codes.