Explosion at off-gas recombiner of a nuclear power plant

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 plant’s turbine building during work on an out-of-service recombiner (an equipment for the recombination of hydrogen and oxygen produced by radiolysis). The post-incident investigation 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.

The INITIATING cause was the leak in a valve of the recombiner, which allowed for hydrogen build-up in a pipe section where worked were grinding.

Nothing is reported on the root cause, but a tentative ROOT CAUSE can be attributed to lack of measures aiming at detecting presence of hydrogen before workers start grinding works.

off-gs system, recombiner

Part of the plant was under maintenance

Hydrogen explosion caused first- and second-degree burns contaminated with radioactive dust to a member of the plant's maintenance crew. A second member reported a light ears problem due to the sound of the explosion.