The Independent Electricity System Operator(IESO) balances the supply of and demand for electricity in Ontario and then directs its flow across the province's transmission lines. http://www.ieso.ca/
According to IESO, Ontario is a net exporter of energy: http://www.ieso.ca/imoweb/siteShared/imports_exports.asp?sid=icSourcesof energy In 2010 we exported 15.2 TWh and imported 6.4 TWh
The former Ontario Power Authority was merged with IESO. It plans and procures electricity supply from diverse resources and facilitate the measures needed to achieve conservation targets.
Ontario Clean Air Alliance (OCE) and the IESO have calculated the cost of importing power from Quebec. It’s all in their report: http://www.cleanairalliance.org/wp-content/uploads/2016/04/pikoptions.pdf
Basically, Ontario does not need to upgrade the lines to import enough water power to replace Pickering, but would need to spend $1.6 billion to upgrade the lines to also import enough power to replace Darlington.
But $1.6 billion is a steal compared to OPG’s request for $12.8 Billion to rebuild Darlington. And then the power will cost us 16.5 cents (on top of the $12.8 billion) per kWh, compared to Quebec's power at 5 cents (on top of the $1.6 billion) per kWh.
In summary for Pickering, it’s straight up 5 cents vs. 9.2 cents. And no additional radiation waste or fear of catastrophic release.
The North American Reliability Corporation (NERC) http://www.nerc.com
The Ontario Energy Boardregulates the province's electricity and natural gas sectors in the public interest
Ontario Power Generation - manages the generation and sale of electricity in Ontario.
OPG generating assets include:
OPG also owns two other nuclear generating stations which are leased on a long-term basis to Bruce Power L.P.
In 2010, OPG generated 88.6 terawatthours (TWh) of electricity.
Hydro One delivers electricity across Ontario. It is mainly owned by the Ontario Government although a portion was recently sold to private investors.