Nuclear reactors and blackouts: an explosive mix that caused the Fukushima disaster

Bags of Contaminated Soil in Fukushima. Piles of bags containing contaminated soil, mud and grass at a site in Iitate village, three and a half years after the nuclear accident. 10/27/2014 © Noriko Hayashi / Greenpeace

Turkey has just suffered a massive failure of its electricity grid. A long-lasting blackout spread over more than half of the country, leaving the capital Ankara and many large cities in the dark.

It may take a while to investigate the initial cause of that failure, but there already is one clear lesson: it has been a wake up call against the construction of nuclear reactors in earthquake- and blackout-prone Turkey.

Every knowledgeable engineer will confirm that a fragile and unstable grid requires more flexible power plants that can quickly turn on and off or promptly change their output, in order to help the electricity network find a new balance and stability. On the other hand, large nuclear power plants are the most unflexible source of energy, because they take several days to start, and while they can stop within seconds, every sudden shut down creates a safety risk and large financial loss. Because of this, nuclear reactors make the grid even more vulnerable, and are definitely not a suitable solution to the black out problems. 

Even worse, an operating nuclear reactor represents a real ticking bomb in case of a loss of electricity supply. Do not forget that it was actually the loss of electricity – and not directly the damage from the earthquake – that caused the nuclear reactors in Fukushima to melt down and explode, releasing the massive radiation cloud that contaminated large areas of land and sea. More than 150,000 people had to abandon their houses, villages, farms, livelihoods and sacred places where their families were buried, never to be able to return. They have lost nearly everything, and a number of them may die prematurely – especially the children who are most vulnerable to the radiation.

In Fukushima, the earthquake was the cause of a major black out, but it was the black out itself that eventually resulted in the nuclear disaster. This is because there is a high concentration of radioactive material inside every nuclear reactor, and its radiation generates huge amounts of heat even after the reactor has been stopped. A typical 1,200 MW reactor, such as the one planned for Akkuyu in Turkey, contains about 100 tons of highly radioactive fuel. This nuclear fuel still produces about 40 MW of heat when the reactor is stopped – this is enough to boil and turn roughly 50,000 liters of water into vapor every hour. This intense heat generated from the radioactive decay inside the reactor continues for days and weeks, and there is nothing that can stop it. The only way to prevent even a closed nuclear reactor from melting down (and releasing its radiation into the environment) is non-stop cooling. This however requires large motors and pumps to circulate thousands of liters of water through the reactor every minute.

Whenever there is a blackout (or even a simple failure of a transformer between the nuclear power station and the electricity transmission grid), the nuclear reactor has to stop, because the grid cannot be take away the electricity it produces. But as the reactors stops, and with no power supply through the network, there is also no electricity to run the reactor cooling system. This is exactly what makes nuclear reactors extremely vulnerable to blackouts.

The only life-line in such situation are the backup diesel generators inside the nuclear power plant. They have to quickly start up to produce the electricity vitally needed for the reactor cooling systems. But if these diesel generators fail there is nothing that can stop the disaster. It only takes few hours after the loss of cooling before the reactor begins to melt. In Fukushima, the first nuclear building exploded and released a radioactive cloud less than 24 hours after its reactor’s cooling system failed.

There are numerous studies into the problem. For example research by US Sandia National Laboratories shows that in the case of total failure of reactor cooling, radiation starts escaping in about 17 hours. What happened in Fukushima was a problem well known, but the government and the nuclear industry kept denying the risk by saying it is unlikely or even impossible to happen. Unfortunately, the reality has proven the opposite, at the cost of hundreds of billions of in economic damages and human suffering. 

Before Fukushima, a very similar accident happened in Sweden in 2006. Following a blackout and shut down of reactors in Forsmark nuclear power plant, the backup diesel generators failed to start. The power plant went into darkness, computer screens in the control room went blank, and the indicators and control systems were down. It was only thanks to a big stroke of luck that twenty minutes later, at least some of the generators were eventually started up manually. It did not take even an earthquake or tsunami to cause a total black out and almost a major nuclear accident there.

There are many lessons that Fukushima has taught us. One of them is that no matter how technically advanced the nuclear reactor, there is always an unpredictable and deadly combination of human error, technological failure and natural disaster that can lead to catastrophic nuclear accident. The other is that not even a rich country like Japan, famous for its robots and skills to handle major disasters, can handle a large nuclear reactor accident.

Many countries started to take this problem seriously. Even a French nuclear Institute IRSN published a report in 2012 report showing that a major nuclear accident in France could result in damages exceeding 540 billion EUR. The leader of the study, Patrick Momal was quoted as suggesting that it would be an “unmanageable European catastrophe”.

I was a high school student in Czechoslovakia when the Chernobyl accident happened in 1986 and contaminated large parts of my country. In the past three years, I have travelled to Fukushima five times after the accident in 2011, working there as a radiation protection expert.

I will never forget the fear of mothers worried about their children, tears of teachers not able to protect their students, the despair of people left on their own and deceived by their government, and the hopelessness of those who had to flee away and even not have not received the compensation or means to find a home and start a new life.

This is why I also want to share my horrifying experience and tell the truth about nuclear hazards: because we can’t allow Chernobyl and Fukushima to happen again. Turkey still has a chance to avoid such a fate by changing its mind about Akkuyu and other nuclear power plants. The simple fact is that the country does not need them to keep its lights on. 

Jan Beranek currently works as Program Director for Greenpeace Mediterranean. He studied physics and has a university diploma for graduating a radiation protection course. He was also leading the response work of Greenpeace International in Japan after Fukushima accident in 2011.

[Image: Bags of Contaminated Soil in Fukushima. Piles of bags containing contaminated soil, mud and grass at a site in Iitate village, three and a half years after the nuclear accident. 10/27/2014 © Noriko Hayashi / Greenpeace]

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