More stunning revelations about the safety of Ontario’s nuclear reactors
Bruce Nuclear Station, Kincardine, ON – world’s largest nuclear station
By Angela Bischoff, Director of the Ontario Clean Air Alliance
There are more stunning revelations in the Globe and Mail this week about the precarious state of Ontario’s aging nuclear reactors.
The Globe reports that inspections of pressure tubes from two shutdown Bruce Nuclear reactors show damaging hydrogen equivalent levels (Heq) that are twice the allowed level under Canadian nuclear regulations. These levels are a flashing red light about the condition of these critical safety components. The measured numbers far exceed what experts at Bruce Nuclear predicted the levels would be based on their computer modelling.
The fuel in a nuclear reactor must be cooled at all times to prevent the release of radioactive gases and vapours. Inside the heart of a CANDU reactor, the pressure tubes are the main arteries needed to cool the hot fuel. Due to the absorption of more and more hydrogen over the years, these metallic tubes gradually weaken and the chance that they may one day burst is increased. “A burst tube would be devastatingly bad news, not only causing loss of coolant but also triggering a power surge that has to be arrested within two seconds to prevent an even more devastating nuclear accident” says Dr. Gordon Edwards.
Reactors operating with the hydrogen equivalent levels discovered at Bruce are violating their reactor operating licence. More importantly, these high levels send an urgent warning that Canadian nuclear operators are running reactors without a correct understanding of what is happening inside the aging reactor cores. Super heated water at a temperature of 300 degrees C is pumped through the core under great pressure to keep the water from flashing into steam. The pressure tubes have to be tough enough to meet that challenge. Hydrogen weakens them.
Weakening of the pressure tubes is particularly alarming when it comes to one of the world’s oldest nuclear stations – the Pickering Nuclear Station in the GTA. We already know that Ontario Power Generation (OPG) has been reporting erroneous hydrogen measurements of tube integrity for this plant. Now the Bruce station hydrogen measurements suggest that plans to “guesstimate” what the levels might be is a dangerous bet.
The recent bad news from Bruce makes it critically important that the Canadian Nuclear Safety Commission (CNSC) do much more to ensure the safety of all these stations, including Pickering. This has to go beyond sending polite letters to nuclear operators asking them to revisit their computer models. We believe that Pickering must be shut down immediately until there is ironclad proof that its tubing is still fit for service. The only way to get that proof is to take physical samples from the tubes while the plant is shut down. Guesstimates are not good enough.
Pickering already has a past history of tubes splitting and cracking, leading to dangerous loss of cooling situations. Determining exactly when tubes have become seriously compromised is a difficult guessing game – one mistake could put millions of people living around this station at risk.
What you can do
Please contact Deputy PM Chrystia Freeland – tell her we need a nuclear regulator that is not afraid to enforce its regulations in the interest of public safety. No more relying on guesstimates. We need real evidence of whether the Pickering reactors are safe to operate and we need it now.