Safety Demonstration Tests of Hypothetical Explosive Burning in the Cell and Air Ventilation System in a Nuclear Fuel Reprocessing Plant

A nuclear fuel reprocessing plant is equipped with an air ventilation system consisting of cells, ducts, dampers, high-efficiency particulate air filters, and blowers. This ventilation system is required to have multiple safeguards in order to confine airborne radioactive materials within the plant in the event of fire, explosion, and criticality. To evaluate these safeguards, three kinds of explosive burning tests are performed using a large-scale facility simulating the ventilation system of a reprocessing plant. In the boilover test, an organic solvent is burned on a layer of water in a burning pan to determine the magnitude of the burning caused by the sudden boiling of the water under the solvent. The optimum conditions for boilover burning are determined by the relationship between the pan size and the ventilation rate. In the deflagration tests, to investigate the mitigating effects of the cell and duct structures in the ventilation system, rocket fuel is burned in the test cell to generate a transient gas overload. A decrease is observed in the pressure, temperature, and flow rate peaks of the gas in the facility. To confirm the integrity of the blower and the durability of the ventilation system motor, a blower test is performed. Pressurized air accumulated in a tank is forced into the blower, and the response of the blower is measured.