Proposal for the Use of Thorium as Fuel And Zirconium Alloy Cladding for Triga®-Type Nuclear Research Reactors

Objective: This article presents a proposal to justify the technical feasibility of using thorium as nuclear fuel with a zirconium alloy cladding in Triga-type nuclear research reactors. Theoretical Framework: The benefits of using thorium as fuel and zirconium alloy cladding in nuclear reactors are presented. Thorium has superior physical and nuclear properties and reduced production of radioactive waste. Method: The use of codes based on the Monte Carlo method for simulating neutron parameters is proposed. The reference is the core configuration of the IPR-R1 Triga reactor in Brazil, which has a fuel element with aluminum and stainless-steel cladding and fuel with a uranium-zirconium hydride alloy. The proposal is to simulate with a cladding in an alloy with zirconium and fuel with a thorium-uranium mixture. Results and Discussion: The aim is to conclude through numerical simulations that it is possible to use Th-232 as a mixed fuel, together with Zircaloy alloy as a coating, in reactors in Triga research reactors. A simulation with Monte Carlo code is presented, comparing the Zircaloy fuel coating with the current fuel claddings used in the IPR-R1 Triga reactor. Research Implications: From the analysis of the results to be obtained in the simulations, it will be possible to know whether the use of Th-232 as fuel will be advantageous in Triga reactors. The simulation already carried out demonstrated the increase in the Effective Multiplication Factor (keff) with Zircaloy-4 being used as a cladding. This increases the efficiency of Triga research reactors. Originality/Value: In Triga Mark I reactors, the maximum power reaches 250 kW in continuous operation, due to the cladding physical limitations. Temperatures above this value can lead to a phase change in the cladding, which can cause it to rupture. By using zirconium alloy claddings, it is possible to operate at powers above 250 kW without damaging the thorium-uranium mixed fuel. An increase in neutron flux means greater possibilities for scientific and technological applications.