[Robert A Cook PE]

blah blah don’t have answers, space affected cavernous, structural integrity strong BUT lots of sheet metal covering gone

Sounds vaguely like it could be a explosion inside the large exhaust gas “duct” area on the outlet of the gas turbine, before it turns and goes up the stack (single stage) or to the waste heat recovery steam generator (dual stage plant).

[Gondring]

It was being built as dual-stage.