Ontario is about to decide whether to overhaul Canada’s oldest nuclear power plant. Does it deserve a second life?

All of these are Candu reactors – Canada’s homegrown reactor design. They deteriorate with age. Inside their cores, pressure tubes (which contain the uranium fuel) grow longer, thinner and weaker. They begin to sag and corrode, increasing the risk of ruptures. Feeder pipes, which supply water to the pressure tubes, also corrode and thin.

Globe and Mail, MATTHEW MCCLEARN, 21 Jan 24

The Pickering Nuclear Generating Station’s dull, mottled-grey concrete domes testify to its more than half a century of faithful service. Lately, its six operating reactors have produced enough electricity to supply 1.5 million people, about one-tenth of Ontario’s total population.

In the coming weeks, Ontario Energy Minister Todd Smith is expected to reveal whether the province will extend the plant’s life. A study last summer from Ontario Power Generation, the station’s owner, examined the feasibility of refurbishing Pickering’s four “B” reactors, commissioned between 1983 and 1986. OPG has said there’s no technical reason the work can’t proceed. If approved, it would begin in 2028, with the aim of returning the reactors to service in the mid-2030s.

The real question is whether it’s worth it.

A firm cost estimate for extending the reactors’ lifespan has not been finalized. Refurbishments under way at OPG’s Darlington nuclear plant in Clarington and Bruce Power’s station in Tiverton have cost between $2-billion and more than $3-billion per reactor. The reactors at Pickering, Canada’s oldest nuclear plant, could cost even more, though their output is relatively small by modern standards.

Ontario’s government has said little about how it is weighing this decision, and it’s unclear what other options, if any, the province is considering. OPG has said its feasibility study would compare the refurbishment’s economic viability to “potential alternatives,” but the finished report has not been released publicly.

The Globe and Mail made a freedom of information request for a copy of the study. But Sean Keelor, chief administrative officer at Ontario’s Ministry of Energy, withheld the document in its entirety. He cited exemptions within the province’s Freedom of Information Act for “advice to government” and for information that could damage the “economic or other interests of Ontario.”

The Canadian Nuclear Safety Commission, which regulates the industry, allows utilitiesto perform upgrades thateffectively double reactors’ lives, as long as “all practicable safety improvements to bring the facility up to modern standards” have been identified. Upgrading Pickering would be no small undertaking.

“They are very old reactors, and the equipment is out of date,” said Ibrahim Attieh, a reactor physicist who worked on Candu designs. “It’s going to be a lot more costly to retrofit new equipment in.”

The Pickering station, situated on the shore of Lake Ontario about 30 kilometres east of downtown Toronto, also includes the four 1970s-era Pickering “A” reactors, which are not under consideration for refurbishment.

Two have been dormant for decades after an aborted refurbishment, and the remaining two are scheduled to shut down permanently this year.

Candus were originally expected to operate for about 30 years. The industry has said decisions on whether to refurbish should be made after a quarter century – a milestone Pickering B has already passed.

All refurbishments involve sending workers into a reactor’s radioactive core, to replace major components such as pressure tubes and feeder pipes. But the scope of work varies considerably, depending on the age, design and condition of components, as well as other factors. A utility might also improve other infrastructure at a nuclear plant, such as turbines and control room equipment.

Subo Sinnathamby, OPG’s chief projects officer, said that among the components that would need to be replaced at Pickering B are the steam generators, which use heat produced inside the core to boil water, creating steam that drives turbine blades.

Ms. Sinnathamby said these components are too large to be removed through the reactor’s airlocks.

“We will have to cut a hole in the dome to remove it,” she said.

Pickering B’s control room is straight out of the Cold War and would also require modernization.

Then there’s the station’s intake for cooling water. Pickering’s was built close to Lake Ontario’s shoreline, a decision that has caused technical headaches ever since. Algae, for instance, can enterthe intake and hinder the station’s ability to condense steam from its turbines, forcing shutdowns.A refurbished station would need an intake that reaches farther out into the lake.

“We’re looking to have a deep water intake tunnel to bring water in from the lake, very similar to what we have at Darlington,” Ms. Sinnathamby said.

OPG decided against refurbishing Pickering in 2009, citing “challenging economics” as one reason.

Each Pickering B unit puts out slightly more than 500 megawatts – roughly half the output of modern large reactors. Ms. Sinnathamby said refurbishment might increase each reactor’s output by up to a few tens of megawatts, but the necessary engineering work to confirm that has not been completed.

By comparison, Bruce Power’s reactors put out more than 800 megawatts, while Darlington’s produce nearly 900 megawatts. Previous estimates suggested the cost of refurbishing units at the three stations would be roughly equivalent. If that’s true, then Pickering’s would be the least attractive to overhaul, per unit of output.

Deciding to go ahead now could make the economics more challenging still.

OPG began planning Darlington’s refurbishment a full decade before work began, and well before the station was at risk of forced retirement. That advance planning allowed the company to take one or two reactors out of service at a time, while the others continued generating electricity and revenue.

Pickering, though, would be idle for years on end. Idle reactors bring in no revenue, but continue to cost money.Two decades ago, a provincial panel found that OPG had spent $25-million a month on three of Pickering A’s idle reactors during an overhaul. More recently, in 2015, OPG estimated that keeping the station operating beyond 2020, when it was scheduled to shut down, would increase the company’s cash flow by as much as $1-billion annually. The station’s decommissioning has been pushed back several times.

Ms. Sinnathamby said some of the station’s workers would be needed for refurbishment. Others could be reassigned to work at Darlington, where OPG is in the early stages of building four new 300-megawatt reactors.

But even if the costs of refurbishing Pickering B seem daunting, some important factors have changed since Ontario last pondered its fate…………………………………………………….. https://www.theglobeandmail.com/business/article-pickering-nuclear-station-extension-deadline/—