hit Bruce reactor during heatwave
Province forced to buy electricity in peak periods
By John Spears
DICK LOEK/TORONTO STAR
An accident at Bruce Power helped to keep one of Ontario's major generating
units out of action all summer — a shutdown that was never made public as
record heat sent electricity prices soaring.
Unit 6 of the Bruce B generating station near Kincardine (on Lake Huron)
only returned to full service early this month, according to Canada's
The unit had been taken out of operation in March for planned maintenance.
But an accident in June helped keep the reactor out of service for the
entire summer, when the province set new records for power consumption and
had to buy large amounts of expensive imported power.
Ontario's supply of electricity is so tight that "any time the temperature
hits 30 degrees, we're going to be kept alive by our neighbours," said Dave
Goulding, who heads the agency that maintains Ontario's electric grid.
The province imported up to 4,000 megawatts of power at peak periods this
summer, when demand hit a record 25,414 megawatts. Bruce Unit 6 produces
about 800 megawatts.
One of nuclear power's selling points is that it produces no air pollution.
When nuclear plants go down, the gap is usually made up by power from
coal-burning plants, the dirtiest kind of power.
According to Bruce Power, the four units of the Bruce B plant produce
enough electricity to supply a city the size of Toronto. Losing Unit 6
reduced Bruce B's output by 25 per cent.
The accident occurred June 11 during maintenance in the reactor core. A
piece of equipment malfunctioned and produced an electrical arc that burned
a hole through a pressure tube — which contains uranium fuel — and through
the calandria tube that encases it. The calandria tube contains heavy water
and is itself enclosed by a large vessel called the calandria, containing
dozens of calandria tubes.
Both the calandria tube and the pressure tube had to be replaced, which was
not in the planned maintenance program. No radioactive material escaped the
Steve Cannon, of Bruce Power, would only say the accident kept the unit out
of service a " little bit" longer than planned. He wouldn't specify how
much generating time the accident cost, citing commercial confidentiality.
The Independent Electricity Market Operator (IMO) , which runs Ontario's
electricity grid, also refused to say how much extra down time the accident
created. So did the Canadian Nuclear Safety Commission (CNSC).
Cannon noted that it wasn't in Bruce Power's interest to have the unit shut
down for the summer because power prices were very high. He said Bruce
Power decided that replacing the tubes was the safest course to take.
And he said other generators had also been shut down for certain periods
during the summer, worsening the supply shortage.
"To pin it all on one unit (being out of service) is not going to be
contextually accurate," Cannon said.
But under Ontario's electricity system, the identity of generators that are
shut down is kept secret. That's in contrast to Alberta, where anyone with
Internet access can look up the Power Pool of Alberta Web site and see
exactly which generators are and are not in service at any time of day.
The only news release made by Bruce Power, on June 12, minimized the
accident. It said only that a pressure tube had been "slightly damaged" and
"the operational impact is not expected to be significant."
It made no mention at all of the calandria tube being damaged. That only
came to light in a report from the Canadian Nuclear Safety Commission
The commission said both tubes — the pressure tube and the calandria tube —
had to be replaced.
The problem reactor came back to power in September, according to the
commission, too late to help during the record-breaking summer.
Power prices get extremely volatile when demand is high and domestic
generators can't supply the full market. On occasions when the province had
to import emergency power, the IMO had to pay as much as $2 a kilowatt-hour
to out-of-province generators. Ontario's normal domestic price is about 5
cents a kilowatt-hour.