Fuel burnup analysis of the TRIGA Mark II Reactor at the University of Pavia

TL;DR

This paper presents a comprehensive fuel burnup analysis of the TRIGA Mark II reactor at the University of Pavia, using Monte Carlo simulations and a custom time evolution model to predict core reconfiguration effects after 48 years of operation.

Contribution

Developed a novel in-house time evolution software combined with MCNP5 to accurately model fuel burnup considering reactor-specific features and predicted a new core configuration for improved reactivity.

Findings

Predicted a significant increase in core excess reactivity after reconfiguration.

Validated the burnup model against experimental data.

Provided insights into long-term fuel management for research reactors.

Abstract

A time evolution model was developed to study fuel burnup for the TRIGA Mark II reactor at the University of Pavia. The results were used to predict the effects of a complete core reconfiguration and the accuracy of this prediction was tested experimentally. We used the Monte Carlo code MCNP5 to reproduce system neutronics in different operating conditions and to analyse neutron fluxes in the reactor core. The software that took care of time evolution, completely designed in-house, used the neutron fluxes obtained by MCNP5 to evaluate fuel consumption. This software was developed specifically to keep into account some features that differentiate experimental reactors from power ones, such as the daily ON/OFF cycle and the long fuel lifetime. These effects can not be neglected to properly account for neutron poison accumulation. We evaluated the effect of 48 years of reactor operation and predicted a possible new configuration for the reactor core: the objective was to remove some of the fuel elements from the core and to obtain a substantial increase in the Core Excess reactivity value. The evaluation of fuel burnup and the reconfiguration results are presented in this paper.