The analysis and understanding of air ingress events are an important aspect of the design of high-temperature gas-cooled reactor (HTGR). During accident conditions (depressurized loss of forced cooling, D-LOFC) air may enter into the reactor pressure vessel as a result of a break in the helium pressure boundary, which can ultimately result in oxidation of the nuclear-grade graphite components.
We have designed, constructed, and operated an experimental apparatus which represents a 1/28 scaled simplified reactor building model in order to study and characterize the air ingress into the vented low-pressure containment of the next generation nuclear plant HTGR during hypothetical moderate-sized D-LOFC break accidents.
The design was based on non-dimensional similarity scaling approach. Experiments were conducted to investigate the behavior of He and Air in the containment during the depressurization and air-refill phases of the accident.
The facility is instrumented with O2 sensors, pressure transducers, and thermocouples to monitor and record gas concentrations, pressure, and temperatures at different locations, and it has been also equipped with venting paths, leak paths, 1-way and two-way louvers, vessels and heat sources.