They are still saying five were killed this morning.

Evidently the accident happened when they were purging gas from the lines after the initial testing.

Tragic as this accident was to the workers immediately involved, there was negligible impact on the surrounding region other than a few broken windows and the noise of the explosion itself. However, even a partial meltdown of a nuclear reactor, such as happened at Three Mile Island in 1979, can rupture the reactor vessel itself (documented weeks after the accident) and release radioactive gas dispersed for thousands of miles.

Charley Noble