A five-pound CO2 cylinder being stored in a compressed gas storage cage at a power plant failed catastrophically and became a missile. The cylinder destroyed the storage cage, then struck one of six stationary hydrogen storage cylinders used as emergency make-up for the hydrogen supply system. One of the hydrogen cylinders was broken away from its mounts and moved 10 feet from its original location. The loss of this cylinder severed the manifold tubing, creating a leak path to the atmosphere for the remaining five hydrogen cylinders. The leaking hydrogen gas apparently self-ignited, engulfing the immediate area. The site fire brigade responded and used hose lines from a distance to provide cooling until the hydrogen supply was consumed. The fire was out within seven minutes, and no off-site fire assistance was needed. All normal supplies of hydrogen were isolated and a re-flash watch was established until all damaged hydrogen cylinders were removed to an isolated "safe zone." Damage was restricted to the CO2 cylinder, the six hydrogen cylinders, associated piping (which showed flame impingement), and the compressed gas storage cage.

Preliminary results indicated that the CO2 cylinder rupture was caused by tensile strength overload caused by overpressurization. The safety disc assembly was dissembled and it was found to contain three safety discs where there should have only been one. Installation of multiple safety discs probably resulted in failure to relieve the overpressure condition prior to cylinder rupture.