Development of Research Program for Aging Management for Thai Research Reactor TRR-1/M1

Thai research reactor reached its first criticality in 1962. The reactor has been renamed TRR-1/M1 after modification into a TRIGA-MARK III type with low-enriched uranium fuels was completed in 1977. Since then, TRR-1/M1 has been in operation for over 40 years and gradually shown signs of ageing. In order to ensure safe operation and public safety, an aging management program needs to be developed to maintain its stability in safe operation. In adopting the IAEA systematic approach for ageing management, detailed information and evidence of aging from the structure, system and components of the reactor are required. However, because of limited information of aging issues for the research reactor worldwide, Office of Atoms for Peace developed research programs for aging assessment and inspection in research reactors. The programs were developed following requirements and elements for aging management provided in safety standard of the IAEA. The first element is to create inventories and classifications of structures, systems and components (SSC). For the second element, aging mechanisms, prevention, monitor and inspection measures were determined for selected SSCs, namely, reactor core and structure, concrete pool, core cooling system, and emergency core cooling system. The reactor core conditions, i.e., neutron fluence and temperatures, were calculated using MCNPX in order to determine in-core structural materials degradation mechanisms. The research program has been conducted since 2016 under Office of Atoms for Peace as the regulator and Thailand Institute of Nuclear Technology as the operator. The work that has been completed under the program is in full compliance with the IAEA SSG-10 Safety Standard where the future plan shall be summarized in the paper. (author)