The Independent Electricity System Operator (IESO) has been advised by Ontario Power Generation that two 500-MW units at the Pickering Nuclear Generating Station A are not expected to be available until at least late August. As a result, the IESO is incorporating the impact of the change in status in its plans to reliably manage the power supply in Ontario over the next few months.

"Ontario imports power from neighboring jurisdictions almost every day," said Derek Cowbourne, chief operating officer for the IESO. "The unavailability of the two Pickering units will increase the need for imports at times over the summer, particularly when hot, humid weather conditions occur or if additional equipment problems occur," said Cowbourne.

The situation that affected supply in the Greater Toronto Area (GTA) last week is expected to improve. One of the Pickering units that was unavailable has returned to service and work is nearing completion on the GTA transmission equipment that has been out of service.

Cowbourne said the IESO has a number of measures it can take to address periods when the system is strained, including appealing to customers to temporarily reduce or shift their use of electricity to off-peak hours.

"We appreciate the response of customers to our appeals," said Cowbourne. "Those efforts can make a difference when the system is strained."