The incident occurred at a power generator during the shutdown of one reactor unit. Hydrogen leaked from the cooling circuit of the generator due to damaged sealing. The hydrogen ignited. The fire was extinguished after 1 hour 40 minutes.

A catastrophic failure of the low pressure turbine followed by fire and flooding severely damaged the generator. The main turbine automatically tripped due to an erroneous mechanical over speed signal caused by high vibrations. The reactor, which was operating at 93 percent power, received an automatic scram signal triggered by the turbine trip. The high vibration was caused by catastrophic failure of the turbine blades. Ejected blade parts ripped through the turbine casing and severed condenser tubes and other piping.

A hydrogen fire occurred in a nuclear power plant outside the controlled area. The leaking point was on a pipe system of the distribution circuit of the gas network (6 bar nominal working pressure). The specific location was a joint on the fire-protection cupboard containing the hydrogen cylinders. The fire started during a repairing intervention on a cupboard nearby, performed by a sub-contractor using a hot surface welding equipment. Internal emergency services isolated and depressurized the pipes, and extinguished the flame.

A hydrogen leak occurs at a gas cylinder storage tank park in a nuclear power plant. Employees locate the origin of the leak on a defective pressure regulator. They isolate the hydrogen release and secure the park. 10 m of gas, the equivalent of one and a half cylinders, escaped.

The accident took place when replacing a pallet of empty hydrogen cylinders with a new full one. The pallet in service (almost empty) was not disconnected from the gas supply line. When the operator in charge of handling (fork lift) begun to remove the pallet in service from its position, he teared off the hose connecting it to the pressure relief system. The pressurised hydrogen in the pipes and in the pallet escaped and ignited. The intervention of the teams from the plant and external emergency services extinguished the fire in 1h45.

A hydrogen skid was placed into service in a nuclear power plant, outside the controlled area. This skid, like seven others, was located in a gas cylinder storage facility. It was supplied by several hydrogen cylinders at a pressure of 200 bar. As its pressure was rising, a trap on the skid was blown off, causing the hydrogen to leak and ignite. The flaming jet measured 40 cm and continued as the system was open. Surprised by the incident, an employee fell and slightly injured his arm.

The nuclear plant was a boiling-water reactor with an output of 0.54 million kW. The component affected was a steam piping (inside diameter: 15 cm; thickness: 1.1 cm) of a heat exchanger used for removing residual heat from the reactor. The piping was broken during a test of a high pressure core injection system for cooling water provided for an emergency core cooling system. The incident resulted in a leakage of radioactive gases. The part of the piping broken was located on the 2nd floor of the building, but there were no workers there.

A hydrogen explosion caused burns contaminated with radioactive dust to a member of the plant's maintenance crew. Three other workers escaped injury.The accident occurred in the basement of the plants turbine building during work on an out-of-service recombiner (an equipment that combines hydrogen and oxygen to make water. A review team has found that a leak in a valve on the system allowed the hydrogen gas to build up in the pipe where the employee was working with a grinding wheel.

A potentially explosive situation was reported by safety inspectors at a nuclear waste tank. The waste slurry had formed a thick crust which was trapping hydrogen being continuously generated underneath. The tank has uncertain chemistry and contents.According to the New Scientist article (see references) four million litres of waste "have been behaving mysteriously inside the underground storage tank. Every few months the tank burps releasing a burst of hydrogen and nitrous oxide."Calculation estimated a potential for an explosion equivalent to 230 kilos of TNT.

The accident occurred in a disposal storage for contaminated waste, consisting in a 65-metre shaft flooded with seawater. At the origin of the explosion was the reaction with water of at least two kilograms of sodium and potassium. They reacted violently with the water, producing hydrogen. The explosion opened the ceiling of the storage. A plume of white smoke blowing out to sea was reported by witness. Probably also an emission of radioactive particles occurred.