The rumour is that when Ontario's minister of Energy and Infrastructure was confronted with the cost estimates for the new nuclear build, he suffered a severe case of sticker shock. For the nuclear reactors themselves, it may very well be terminal:
The Government of Ontario today announced that it has suspended the competitive RFP to procure two replacement nuclear reactors planned for the Darlington site....This makes Ontario the latest in a long line of jurisdicions that have abandoned nuclear when they get a look at the bill.
Only the submission from AECL was compliant with the terms of the RFP and the objectives of the Government. However, concern about pricing and uncertainty regarding the company's future prevented Ontario from continuing with the procurement at this time.