VOID COEFFICIENT SENSITIVITY ANALYSIS FOR THE TRIGA MARK II REACTOR AT L.E.N.A. (UNIPV)

¹ Politecnico di Milano; Dept. of Energy, Nuclear Eng. Division, Via La Masa 34, 20156, Milan, Italy
² LPSC-IN2P3-CNRS; 53 Rue des Martyrs, 38026 Grenoble, France
³ Milano Multiphysics; Polihub, Politecnico di Milano, via Durando 39, 20158 Milano, Italy
⁴ Institut Laue Langevin; 71 Rue des Martyrs, 38042 Grenoble, France

Published online: 22 February 2021

Abstract

Sensitivity analysis studies the effect of a change in a given parameter to a response function of the system under investigation. In reactor physics, this usually translates into the study of how cross sections and fission spectrum modifications affect the value of the multiplication factor, the delayed neutron fraction or the void coefficient for example. Generalized Perturbation Theory provides a useful tool for the assessment of adjoint weighed functions such as k_eff and void coefficient sensitivities. In this work, the capability of SERPENT code to perform sensitivity calculation based on GPT is used to study the TRIGA Mark II research reactor installed at L.E.N.A. of University of Pavia. A general sensitivity analysis to the most important reactor’s cross sections has been performed in order to highlight the biggest reactivity contributions. Two numerically challenging tasks related to GPT calculation have been performed thanks to the relatively quick Monte Carlo approach allowed by this reactor: investigating the linearity of the reactivity injection caused by the flooding of the central channel, and calculating the fuel void coefficient sensitivity to the coolant density.