Fire at the storage of a power plant

At a nuclear power plant, a fire occurred in the station's hydrogen storage facility. The storage facility consisted in one or more tube trailers which had to be connected to the plant hydrogen supply line.
An operator had just aligned valves at the hydrogen storage facility in preparation for putting the hydrogen injection system into service, when the valves started leaking causing a large fire.

The operator escaped injury because he was wearing fire retardant protective clothing and was able to quickly scale a 7 foot high fence enclosing the hydrogen area.

INITIATING cause was the failure of three valves, leaking and starting the fire. The technical reasons for the valves failure is not provided.

According to the root cause analysis performed by the plant operator, all failures were due to an inadequate preventive maintenance program by company supplying the hydrogen system, which was also responsible for its maintenance.

hydrogen storage area

Plant was operating at 100% power.

The incident did not require the plant to be shut down at any point and there was only one small injury to an employee.

The U.S. Nuclear Regulatory Commission (NRC) issued the information notice 2001-12 to alert addressees to potential hazards associated with hydrogen storage facilities.
It is expected that recipients will review the information for applicability to their facilities and consider appropriate actions to avoid similar problems.
However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.

The occurrence was immediately reported to the NRC, and staff sought firefighting assistance from local volunteer fire departments.
Some 12 local organizations came to staff’s aid, and the fire was under control within an hour, although the formal emergency status did not end until 8 p.m.
Work crews were kept on over the weekend to enable the prompt initiation of an investigation as to the fire’s cause, which was still ongoing.

The results of the NRC special inspection (Report No. 50-333/99-02, Accession No. 9904010078, dated March 26, 1999) determined that the licensee's overall response to the event was acceptable.
The licensee and offsite support took appropriate actions to control the fire until the hydrogen burned out.
The special investigation also determined that the licensee's subsequent event investigation was systematic and comprehensive

The NRC report concluded that this event demonstrated that "lack of adequate maintenance, system monitoring and oversight of maintenance can contribute to the ignition of a fire which is difficult to extinguish and poses an extreme danger to fire fighting personnel. Properly maintaining, monitoring and overseeing of hydrogen storage facility equipment can minimize the risk of fire or explosion".

Since hydrogen storage facilities can play acritical role in the overall safety of a plant, it remains a background question: which is the technical responsibility of a plant operator, in controlling and/or ensuring that contractors perform activities as agreed? Which means could be used, to perform an independent check on the soundness of the maintenance performed by 3rd parties?