Characterization of mixed N/G beam of the VR-1 reactor

Abstract

VR-1 is light water zero-power reactor using IRT-4 M fuel with nominal enrichment of 19.7 wt%, equipped with the radial channel being directly attached to the fuel. Enrichment at the top level of the low enriched uranium limit guarantees that the larger part of non-scattered neutrons in the spectrum is coming from 235U than in case of experimental reactors using enrichments between 2 and 5 wt% (e.g., LR-0). Thus, the measurement of the VR-1 leakage spectrum can be a valuable contribution to the validation process of predicted 235U prompt fission neutron spectrum. Presented second set of measurements is confirming the beam stability at VR-1 and compares the agreement rate in neutron spectrum shape with two benchmarks; light- and heavy water filtered neutron spectrum obtained from spheres. Additionally, gamma spectrum was measured and compared with spherical iron benchmark and VVER-1000 core simulator. Presented measurements have the character of comprehensive characterization of beamline experiments developed at reactor cores with IRT-4 M fuel. Reported good agreement between the experiment and calculation confirm the methodology of using VR-1 as a Mock-Up experiment for benchmarking of high power reactors with IRTM fuel in the neutron transport experiments.