Accident Possibilities at #Gentilly2 and Other #CANDU Reactors

BACKGROUND INFORMATION ~ AUGUST 1995

by Gordon Edwards, Ph.D., President, Canadian Coalition for #Nuclear Responsibility

"When Gentilly-2 was built, nobody thought about the possibility that an accident could kill everybody in the control room of the nuclear reactor, possibly resulting in a catastrophic accident. (Even if the reactor is shut down, the heat still has to be removed from the core to prevent a catastrophe -- and that cannot be guaranteed if the operators are dead.) A few years ago, AECB discovered that a sudden break in one of the steam pipes passing over the roof of the control room could, in fact, kill everyone inside and make the control room unusable. Obviously, this improbable situation could be extremely hazardous for the population at large.

"At first, AECB wanted Hydro-Quebec to relocate the steam pipes, but Hydro-Quebec argued that this would be too expensive. Instead they offered to make some substantial alterations to the interior design of the building so as to minimize the effects of such a break in the steam pipes, and to carefully monitor the pipes so as to detect any weakening which might (or might not) occur before such a break would happen. Those corrective actions are still being carried out. Whether they are adequate to eliminate the possibility of a catastrophic accident caused by a steam pipe rupture is a matter of judgment.

"One of the most serious kinds of accidents in any nuclear reactor is a Loss of Coolant Accident, or LOCA. It is caused by a pipe break or an open valve, allowing the water normally used to remove the heat from the core of the reactor to escape. Without adequate cooling, the core of the reactor will overheat and fission products will be released from the damaged fuel, many of them in the form of radioactive gases and vapours. If these materials escape into the environment in large enough quantities, a nuclear catastrophe will result.

"Every CANDU reactor has an Emergency Core Cooling System (ECCS) which is supposed to flood the core of the reactor with ordinary water in case of a large LOCA to prevent it from overheating. Sometimes, however, the ECCS is not available. The AECB allows the ECCS to be unavailable for up to eight hours in any given year, and in some cases it is unavailable for a much longer period of time. If a large LOCA were to happen at such a time, serious core damage could occur and a nuclear catastrophe could result.

"The first LOCA in a Canadian nuclear generating station was at Pickering, just outside of Toronto, in 1983, when a pressure tube burst without warning in the core of the reactor. A few years earlier, nuclear experts had insisted that a pressure tube could not burst suddenly, because it would begin to leak long before it would break, giving the operators enough time to shut the reactor down and correct the situation. But the experts were wrong.

"Fortunately, it was not a very large LOCA, and the ECCS was not needed to keep the fuel from overheating. Most of the fuel remained undamaged and so not much radioactivity was released. However, repairs to the core of the Pickering reactor took four years and cost more than 500 million dollars. All of the pressure tubes had to be replaced, since many of them were showing signs of serious deterioration and some were developing blisters. If several pressure tubes had burst at the same time, a much more frightening situation would have to be dealt with.

"All CANDU reactors have pressure tubes, and all of them deteriorate with time. But the cost of replacing all the pressure tubes is so great that Ontario Hydro has decided to shut down some of its reactors permanently rather than spend the money needed to repair them. At Gentilly-2, until recently, Hydro-Quebec was also planning to replace all the pressure tubes; but now, to save money, they have decided to try something less expensive -- to re-adjust the "garter springs" which support the pressure tubes inside the core of the reactor, so they will not sag as much and, hopefully, will not develop the same kind of blisters that were seen in the pressure tubes at Pickering. This approach does not halt or reverse the deterioration of the pressure tubes, but it will perhaps slow it down.

"In December, 1994, a second LOCA occurred at a Canadian nuclear reactor. This time, it was not a pressure tube, but a relief valve that broke at Pickering.As the superheated mixture of water and steam escaped through the broken valve, a powerful vibration shook the pipe so hard that it broke, resulting in a large LOCA that required -- for the first time in Canadian history -- the use of the ECCS to prevent damage to the nuclear fuel. Similarly accidents involving broken relief valves in CANDU reactors have also occurred in #SouthKorea, and -- in May 1995 -- at one of the Bruce reactors in #Ontario. In these situations, however, the vibrations did not result in broken pipes.

"In June 1995, the AECB made public its analysis of these accidents. They have concluded that a similar accident could occur at any time at Gentilly-2, and that the resulting vibrations would very likely result in either broken pipes or damage to other valves, thus resulting in a serious LOCA. Hydro-Quebec has made no statement about the situation, and may not agree with the AECB as to the possibility of such an accident or the necessity of undertaking the necessary repair work which would involve redesigning that portion of the pressure relief system."

http://www.ccnr.org/Gentilly_Safety.html

#NuclearPlants #Canada #WaterIsLife #RenewablesNow

#HydroQuébec considers reopening #Gentilly2 #nuclear power station

by Philip Authier, August 10, 2023

QUEBEC – "Hydro-Québec is currently studying the possibility of reopening the mothballed Gentilly-2 nuclear plant in #Bécancour to boost #Quebec’s available power resources in the face of soaring demand.

"On Thursday, Hydro officials confirmed the news, first reported by the Journal de Montréal .

"'Concerning the Gentilly-2 station, an evaluation on the current state of the station is underway, to evaluate our options and to feed our reflection on Quebec’s future energy offering,' the utility said in a statement to the Montreal Gazette.

"The new CEO of Hydro-Québec, #MichaelSabia, is already on the record saying he has 'an open mind (on future options) given the context of a strong increase in demand,' the statement added.

"'We are evaluating different possible options to increase the production of clean electricity. It would be irresponsible at this time to exclude certain energy sectors.'

"In 2012, the #PartiQuébécois government endorsed a recommendation from Hydro-Québec to close Gentilly-2, a #CANDU reactor, mainly owing to the high costs of upgrading the installation. It cost Hydro-Québec $80 million to shut down the plant.

"With a capacity of 675 megawatts, the Gentilly-2 reactor started producing power in 1981."

Source:
https://www.msn.com/en-ca/news/canada/hydro-qu%C3%A9bec-considers-reopening-gentilly-2-nuclear-power-station/ar-AA1f6m1M

#NuclearPlants #Environment #WaterIsLife #NuclearWaste

God I love CANDU. It’s a sci-fi reactor.
---
RT @Bruce_Power
We thank you @viraniarif for raising @Dr_Keefer's petition to prioritize #CANDU nuclear power. Your support for #cleanenergy gets us one step closer to reaching Canada's #netzero emissions targets.

Read more: https://openparliament.ca/debates/2023/4/26/arif-virani-1/#:~:text=Mr.%20Speaker%2C%20I%20have%20two,Chris%20Keefer%20for%20raising%20it #cdnpoli
https://twitter.com/Bruce_Power/status/1651995988687564802

Fukushima was no accident
March 10, 2023

"The 12th anniversary of the Fukushima Nuclear disaster is an excellent moment for the Canadian Nuclear Safety Commission (CNSC) to take a long, hard look in the mirror. What it will see is an agency that excels at spinning out talking points about Canada’s 'world class' nuclear industry along with hype about new unproven nuclear technologies. What it won’t see is an agency that rigorously demands answers to difficult questions like just what is happening with long-in-the-tooth pressure tube systems inside decades-old reactors.

"Unfortunately, too many of our political leaders listen to the CNSC’s spin instead of examining the agency’s actions. They are oblivious to the fact that the CNSC has allowed its own requirements for assuring pressure tube integrity to be violated, and that its staff see their job as perpetuating the #nuclear industry in #Canada first and foremost rather than truly demanding the 'world class' safety standards the agency pays lip service to in its communications.

"#Japan has important lessons to teach us about what happens when a regulatory system becomes co-opted into propping up an industry instead of examining its fundamental safety. Far from being the result of 'once in a millennium' event, the conditions for the #Fukushima disaster were sown by lax oversight and a far too cozy relationship between the nuclear industry and its supposed regulators, according to the country’s own legislative assessment. The post-accident examination carried out by the Diet (legislature) of Japan found that there was no separation between nuclear regulation and promotion in the country, with the result that the nuclear industry became 'an unstoppable force, immune to scrutiny by civil society.'"

It also found that: “Despite having a number of opportunities to take measures, regulatory agencies and #TEPCO management deliberately postponed decisions, did not take action, or took decisions that were convenient for themselves.” There are some very worrying parallels between that statement and the refusal of the #CNSC to demand real proof from #Ontario Power Generation and Bruce Power that pressure tube systems are operating within safe limits."

#Fukushima #WaterIsLife #StopTEPCO #NoNukes #CANDU #FukushimaAnniversary

Read more:
https://www.cleanairalliance.org/fukushima-was-no-accident/

It's always good to learn your opinion on nuclear matters, @publius .

Tell me, the #CANDU type reactors with heavy water as a moderator, is there still a future for that sort of technology? As far as I can see, none of the SMRs work that way.

#SMR #NuclearEnergy

RT @Pickering2075@twitter.com

Even in their current extended operation state, Pickering B unit performance has consistently improved.

With a refurbishment, updates & uprates, capacity factors can increase even further.

Another 45+ years of #cleanenergy? Yes, please!

#Pickering2075 #CANDU 🇨🇦 #NuclearEnergy

🐦🔗: https://twitter.com/Pickering2075/status/1616815374669946880

Everyone saying things like:

- We need a better way to deal with nuclear waste.

- Cancer treatments are amazing.

- Nuclear fusion is going to solve energy needs.

You all need to watch this video!

The USA should build no fewer than 36 CANDU reactors! Place at least one in every state with spent nuclear fuel just sitting there waiting to be used.

https://youtu.be/CIgsXsPoEZM

#CANDU
#NuclearEnergy
#BuildMoreReactors

"Nuclear reactor pressure tubes are deteriorating faster than expected. Critics warn regulators are ‘breaking their own rules.’

The Canadian Nuclear Safety Commission has allowed utilities to operate tubes beyond licensing limits, a crucial concession for the nation’s aging reactors"

Globe & Mail: https://www.theglobeandmail.com/canada/article-canada-nuclear-power-plants-candu-tubes/

@nuclearhumanities @sts #nuclearpower #nuclear #CANDU

RT @NuclearObserver
Ultime Notizie del 5 Dicembre 2022
#nucleare #energia #canada #candu

I'm a huge fan of nuclear energy. Not a huge fan of huge fans.
#nuclearenergy
#zeroemissions
#cleanenergy
#candu

RT @Dr_Keefer@twitter.com

PLEASE SIGN OUR PETITION!

The entire existing nuclear supply chain and #CANDU fleet are being left out of a vital clean energy incentive called the Clean Technology Investment Tax Credit.

https://petitions.ourcommons.ca/en/Petition/Details?Petition=e-4201 https://twitter.com/i/web/status/1593710104548892672

🐦🔗: https://twitter.com/Dr_Keefer/status/1593710104548892672

PLEASE SIGN THIS PETITION!

https://petitions.ourcommons.ca/en/Petition/Details?Petition=e-4201

The entire existing Canadian #nuclear supply chain and our current fleet of #CANDU reactors are being left out of the Clean Technology Investment Tax Credit, a vital clean energy incentive recently launched by federal government.

Silly and short-sighted. Considering how crucial it is in lowering emissions and reducing dependency on fossil fuels.

SNC-Lavalin joint venture awarded $400 million Bruce Power Candu refurbishment deal https://bit.ly/33H9Hhq #SNCLavalin #BrucePower #Candu #onpoli

@publius @gemlog What should we think about #CANDU technology, using the heavy water moderator? Seems like it had many technical advantages, but it never caught on. Is it outmoded by newer reactor designs?

#nuclear