Facility puts nuclear reactor safety systems to the test
S. Himmelstein | September 20, 2024The performance of passive safety systems designed to cool a nuclear reactor without any operator intervention or power is being tested at U.S. Argonne National Laboratory. The Natural Convection Shutdown Heat Removal Test Facility (NSTF) at the Illinois-based laboratory represents a half-scale model of an actual reactor system and is used for large-scale experimental evaluation of reactors and their components.
Nuclear reactors are typically equipped with heat removal systems designed to handle the decay heat generated after a system shutdown. These systems require operator action or electricity input to power
Source: U.S. Argonne National Laboratory pumps. Passive systems serve as backup to remove heat in the absence of worker action or power supply, removing the heat that can be deleterious to nuclear fuel by means of gravity or convection. The NSTF is currently testing a water-based reactor cavity cooling passive system to perform this function.
Reactor core heat at the facility is simulated by exposing a large steel plate to powerful electric heaters. During testing, pipes filled with filtered tap water in an insulated cavity are heated, and the thermal problem is addressed by removing this heat as the water circulates around a large, vertical closed loop of pipes and tanks. The loop-contained water does not interact with material in the nuclear reactor and contains no radioactive material or waste.
Experiments entail operating the system with blockages in different areas of the pipes, or with different water levels in the tanks. The NSTF researchers work with industry stakeholders to simulate real-world scenario where active cooling is suddenly lost. The data generated is qualified to the level of National Quality Assurance-1 (NQA-1), a national standard for quality assurance in the nuclear industry.
Prior to the focus on water-based cooling, the facility was used to explore air-based passive safety systems, leading to the development of a patented weather cap device that protects sensitive exhaust systems from wind-induced downdrafts.
