I grew up in Bowmanville.
Nothing too big or exciting there that might be part of an RPG, except maybe the St Mary's cement company with it's huge vertical furnace (looking all the like a rocket launch gantry) along with its equally huge (though in depth) blasting pit for limestone, as well as the former internment camp for German POWs during WW2.
Darlington generation station and Pickering generation station (on the other side of Oshawa) are the two nearby nuclear plants, with four and five (originally eight, with one still in standby) reactors respectively.