Pulsed Research Reactors and the Development of a Large-Scale Uranium–Graphite Pulsed Reactor Concept Based on Experience Gained with IGR

For the safety assessment of existing reactor systems and the development of advanced nuclear technologies, it is essential to have experimental data on how nuclear fuel and structural materials respond under rapid transient conditions . Pulsed research reactors provide unique capabilities for reproducing short-duration power excursions with high neutron fluxes and rapid energy deposition. Many existing pulsed facilities were commissioned several decades ago and are approaching the limits of their experimental capabilities, highlighting the need for next-generation pulsed reactors. This paper reviews the principal concepts of pulsed research reactors and the physical mechanisms employed to generate intense neutron pulses. The characteristics of IBR-2M, self-quenching solution reactors, TRIGA, TREAT, the BIGR, and the IGR are analyzed to identify their advantages, limitations, and fields of application. The focus is on U-Gr reactors and the historical MIGR concept, which represented an early approach to increasing the performance of graphite pulsed reactors. The proposed large-scale uranium–graphite pulsed reactor is then assessed using preliminary neutronic and thermal results, with an emphasis on experimental channel dimensions, thermal neutron flux, and fluence in the self-quenching pulse and regulated transient modes.