Puma Punku in bolivia and Peru amazing stone cutting make me suspect aliens had done that , cuts are so precise and so impossible to realize today with our ''modern technology incline to think of a desintegrator cutting tool ( energy field that break atoms bonding )
it is Pickering in Ontario much less dangerous ( no big earthquake fault near )
even if they loss all exterior power Candu can still produce up to 40 % of power generation for internal use and dump the rest of steam in condensing unit