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Pickering Nuclear plant at risk of ‘Fukushima-type accident,

Nuclear plant at risk of ‘Fukushima-type accident,’ Ontario group says, National Observer, 
By Charles Mandel | NewsEnergy | April 8th 2021
   Citing the potential for a repeat of the 2011 Fukushima nuclear meltdown, the Ontario Clean Air Alliance wants an interim moratorium on the Pickering Nuclear Generating Station’s (PNGS) operation.

The aging plant is slated for closure in 2024, and the alliance says a moratorium should be imposed until the operators can prove to the public that it poses no risk to public safety. Ontario Power Generation (OPG) operates the plant, which consists of eight CANDU reactors— a type of reactor that uses deuterium oxide, or heavy water, as a moderator and coolant and natural (not enriched) uranium as a fuel. Two of the plant’s reactors have already been permanently shuttered because of their age.

OPG has been lobbying Ontario’s provincial government to keep the plant open until 2025. Currently, it is slated to remain operating until 2024, at which point decommissioning would begin. The OPG gained its last licence renewal for the plant in 2018.

The clean air alliance made its demand March 30 in a letter addressed to Rumina Velshi, president of the Canadian Nuclear Safety Commission (CNSC).

However, Marc Leblanc, CNSC commission secretary, said in a release in early April that an interim moratorium is not under consideration. “The commission sees no basis on which it might reconsider its licensing decision to authorize the operation of the PNGS.”

The CNSC did not return National Observer’s phone calls.

Fears of ‘Fukushima-type accident’

OPG says the plant’s exemplary safety record is proof there is no cause for concern.

However, a number of experts told National Observer the Pickering plant is well past its prime and shouldn’t be allowed to continue operations.

Jack Gibbons, president of the Ontario Clean Air Alliance, cited the plant’s aging pressure tubes as one reason the plant should be shuttered.

“It turns out that OPG does not have the data to show that Pickering’s pressure tubes are still safe for service. If the pressure tubes aren’t fit for service they could potentially rupture or break, and in the worst case scenario there could be a Fukushima-type accident,” Gibbons said.

The clean air alliance notes PNGS has at least twice as many people living within 30 kilometres as any other nuclear station on the continent. A 2018 study the alliance commissioned from Ian Fairlie, an independent consultant on radioactivity in the environment, cites dire consequences should a meltdown occur at PNGS.

It says a Fukushima-level accident at PNGS could cause approximately 26,000 cancers, require the evacuation of more than 150,000 homes and more than 650,000 people, and trigger a $125-billion loss in the value of single-family homes in the Greater Toronto Area.

Aging pressure tubes ‘a prime concern’

The pressure tubes in question are about 10 centimetres in diameter and some six metres long. Each pressure tube in a reactor holds 12 uranium bundles, which are the basis for the nuclear reaction that produces heat and provides the energy. The tubes — there are approximately 400 of them in a reactor — also carry the coolant. But like any aging part, the tubes could fail.

Gordon Edwards, president of the non-profit Canadian Coalition for Nuclear Responsibility, says OPG is “running these plants like no other CANDU reactor in the world.”

He explains that every other CANDU reactor that reaches a certain age is scheduled for refurbishment or re-tubing, which is a replacement of the pressure tubes and feeder pipes that go into the reactor’s core and cool the fuel.

Over their lifespan, the tubes are subjected to great heat, pressure and radiation from the fissioning uranium atoms. Over time, the stress to the tubes can cause them to become brittle and develop blisters that potentially become the site for an elongated crack or a serious rupture.

“Cooling the fuel is essential in nuclear power. If you don’t cool the fuel even after shutdown, you can have a meltdown. That’s what happened at Fukushima. I’m not saying every loss of coolant will lead to a meltdown, but that’s the precipitating cause that could lead to a meltdown. So therefore the integrity of the piping is a prime concern,” Edwards said.

While the Pickering plant must inspect the tubes as a condition of its operating licence, Edwards notes it only tests a fraction of the tubes, fewer than 10 per cent. Nor are the tubes uniform. One might have signs of degradation while the one next to it might be fine. According to Edwards, that makes the sampling less than reassuring.

Frank Greening is a research scientist who worked for OPG for 23 years. During that period, he estimates he spent half the time researching pressure tubes.

Greening says the benchmark for operating performance for CANDU reactors is roughly 30 years at 80 per cent capacity. Pickering reached that benchmark around 2015, but since then the OPG has “kept pushing the envelope, and the limiting factor is the pressure tubes’ fitness for service.”

According to Greening, “every time you turn around, they try and squeeze a little bit more juice out of the lemon. This is a way to keep the nuclear industry gainfully employed, and stretching the lifetime of these reactors as far as they can. I think they’ve gone too far.”………

April 10, 2021 - Posted by | Canada, safety

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