The Pickering A nuclear power plant is to be reactivated at a cost of Can$1.3bn ($815m) after four years in mothballs, Ontario Power Generation announced Monday.

However, approval to restart the reactor’s four units comes with a long list of conditions set by the nuclear industry regulator, the Canadian Nuclear Safety Commission.

“The plan was always to bring it back into service,” said Ted Gruetzner, a spokesman for Ontario Power Generation (OPG).”There is a lot of work that needs to be done in terms of enhanced shut-down system and stuff like that and just kind of bring it up to current specs.”

The power plant, just east of Toronto on Lake Ontario, comprises four 540 MW Candu reactors. Activated in the 1970s, OPG shut the reactor down in 1997 after management decided against making costly upgrades, not because of any “safety issues in terms of the equipment,” Gruetzner said.

The company initially applied for the restart in November 1999. An environmental assessment was finally completed in February, and licensing hearings concluded early last month. The safety commission said it is satisfied that OPG complies with all current security regulations.

The aim is to restart the first reactor next March, with the three remaining units activated at intervals of about six months, the company said. Before it can do that, OPG has to complete improvements and upgrades specified by the safety commission. The dozens of conditions include modifications to deal with a large loss of coolant, seal checks and enhancement of the emergency shutdown system.

“After they have done a list of maintenance and upgrades, they must report back to the commission every six months or before restarting each unit, depending on which comes first,” said commission spokeswoman Sunni Locatelli. Those reports will be made public.

The company will also require approval of the agency’s safety staff before each increase in reactor power. In deciding to allow the restart, the commission said OPG can run the facility safely and “is not likely to cause significant adverse environmental effects.” The improvements and upgrades will ensure “protection of the environment, the health and safety of persons, and the maintenance of national security and measures required to implement Canada’s international obligations,” the commission said.

OPG currently operates four other reactors at its Pickering B facility. The amended licence for Pickering A is valid until June 30, 2003.