A methodology to enhance thermal neutron flux in Tehran Research Reactor core for domestic fuel test purposes

Highlights: • Increasing TRR thermal neutron flux for fuel test purposes was the main objective of this study. • A compact core configuration was developed considering all design criteria and limitations. • Neutronic and thermal-hydraulic safety aspects of the proposed configuration were investigated. Performance of newly fabricated nuclear fuels must be tested under desired neutronic and thermal-hydraulic operating conditions prior to utilization in the reactor core. Tehran research reactor (TRR) as an MTR-type reactor is the only operating research reactor in the country that can potentially be used for irradiation tests on domestic fuels. In this study, compacting TRR core configuration, as a method to increase thermal neutron flux in the central in-core irradiation position to provide desired neutronic environment for fuel irradiation tests, is of concern. Several design criteria and limitations, including preservation of enough and suitable irradiation positions in the core for routine radioisotopes production activities of the reactor, have been considered to develop a new compact core configuration for TRR in which, desired linear heat generation rate is achieved in the test fuels and all the neutronic and thermal-hydraulic safety parameters of the proposed configuration are in accordance with the acceptance criteria stated in the reactor FSAR.