Tom Spears
The Ottawa Citizen
October 16, 1997

Bruce A plant may be lost for peak winter season

The giant Bruce A generating station on Lake Huron, which can supply 15 per cent of Ontario’s electricity, has shut down because of rust and cracks and may never reopen.

Ontario Hydro insists it plans to get the plant working again in time for winter. But it needs permission from a federal regulator, which says this may be "difficult."

Meanwhile, one energy analyst warns Ontario may have winter power brownouts if the Bruce A isn’t fixed before the peak demand season of December through February.

The confusing picture of nuclear power in Ontario, in short, just got muddier.

The Bruce A’s three working nuclear reactors, each big enough to power the city of Ottawa on the coldest day of winter, are due to shut down in March. A fourth reactor in the station is already shut down indefinitely.

But late in the summer, the three working reactors had to shut down unexpectedly when Ontario Hydro, which owns the plant, found a new type of corrosion and cracking in it.

Now the Atomic Energy Control Board of Canada, which regulates nuclear safety, says the rust and cracking may be too poorly understood to justify letting the plant run any time soon.

If so, says the board, the plant may not be allowed to reopen before its official closing date next spring.

"The nature of the defects and the inspection technique may make it difficult for Ontario Hydro to make a timely case for short-term operation of any Bruce A units," the board’s safety experts wrote.

The neighbouring Bruce B station, which also has four reactors, is not affected. It is operating near full power.

Hydro says the plant should work again within a month or two. "We’re still planning to restart the units. We haven’t changed from our original position, which was to have them running over the peak period in the winter time," said spokesman Terry Young. "We’re looking at (starting) somewhere in the November-December period."

The loss of Bruce A would threaten Ontario’s energy security for the winter, said Tom Adams of Energy Probe, a frequent Hydro critic.

Two-thirds of Ontario’s energy comes from its string of nuclear stations. But the giant Darlington station has scaled down to just over half power because of computer glitches in its safety systems. Its four reactors are delivering two reactors’ worth of power.

"The remaining issue is: Is any juice coming out of Bruce A?" Mr. Adams said. "The reliability of Bruce A over the winter peak could undermine reliability and cause brownouts, or even blackouts."

The AECB says Ontario Hydro doesn’t even understand what went wrong yet.

"What they have here is a fairly significant corrosion problem," said AECB spokesman Bob Potvin. "The nature and type of this corrosion is somewhat different" from what Hydro has seen before.

"In order for Ontario Hydro to make a case to us that they can restart these things, they have to have a damn good understanding of the nature of the phenomenon, of the rate at which it works, and the progress of this particular defect," Mr. Potvin said.

"Our approval is definitely needed, and before we give our approval they have to give us an awful lot of information that is not there yet," he said.

"So all of that is a pretty significant quantity of work that has to be done by Ontario Hydro. What our people are saying is: Will they be able to do this work? Will it be worthwhile for them to do this work for what is a relatively short-term operation?" he said.

The problem isn’t the reactors themselves. It’s in the boilers, also known as steam generators, attached to them.

A nuclear power plant is just a big steam engine that uses radioactive uranium fuel for heat.

The reactor heats one body of water, and sends it through sealed tubes into a separate tank of water, the boiler. There the sealed tubes of hot water from the reactor act like the heating element in an electric kettle: They boil the big tank of water and make steam. That steam turns a turbine and a generator to make electricity.

The trouble at Bruce A is that some of the sealed tubes carrying water from the reactor are corroding and cracking. The danger is that the water sealed inside has become radioactive by passing through the reactor core, and it would release radioactivity if it leaked.