Ageing nuclear reactors are endangering safety in Europe

In many countries of the European Union, nuclear reactors will be operated for longer in future than originally planned. Furthermore, the nuclear power plants have to generate more electricity. The components of the nuclear reactors are burdened by both their increasing age (and the associated ageing effects) and the increase in output; in this way, they constitute a potential threat to the safety of the nuclear reactors. These are the main findings of a new report which Oeko-Institut has conducted on behalf of Greenpeace that is presented today across Europe.

Ageing and increases in output decrease safety margins

The 152 nuclear reactors in Europe (the EU along with Switzerland and the Ukraine) were technically designed for a lifetime of 30 to 40 years. Currently the reactors have an average age of 29 years; now, however, their lifetimes are to be extended to 50 to 60 years. If the originally planned lifetime is systematically exceeded, ageing effects increasingly arise which impair, for example, the properties of the materials concerned. Even now components that are eroding are forming cracks or becoming brittle, have to be continually being monitored and replaced in due time. Additional stress is put on the systems when the output is increased at the same time, i.e. the reactor has to produce more thermal energy during the lifetime extension.

“Paradoxically the oldest nuclear reactors in Europe have to increase their output,” says Simone Mohr, expert on nuclear technology at Oeko-Institut. “In some cases the oldest power plants are currently producing 20 per cent more output than was planned during construction.”

Problem case: Incidents at the nuclear reactors

The problems of old power plants arise, on the one hand, from the physical ageing of components, systems and building structures; and on the other hand, from the outdated technical and conceptual design. In the past the requirements for the design of nuclear power plants were lower than they are today. For example, old nuclear reactors are frequently less well protected against impacts from the outside such as floods, earthquakes or airplane crashes, than would be necessary under today’s rules.

“All these aspects are leading to a progressive decrease in the safety level of the older reactors in Europe,” says Simone Mohr. That can particularly become a problem in the case of incidents when the reactor is subject to greater stress than during normal operation.

Serious consequences cannot be ruled out in the densely populated regions of Europe in which nuclear reactors are found today. “To give one example: Switzerland currently has the oldest nuclear reactors in operation in Europe. Beznau-1 is, at 45 years of age, the oldest reactor operating in the world; Beznau-2 and Mühleberg are over 40 years old,” says Mohr. “If we also consider Fessenheim-1 and -2 in France, it becomes clear that a large number of old nuclear reactors are located in one of the earthquake-prone regions of Europe. If there was a core melt accident involving the release of radioactive material as in Fukushima, millions of people in and around Bern, Basel or Zurich could be affected.”

"Lifetime extension of ageing nuclear power plants: Entering a new era of risk." Report commissioned by Greenpeace with a contribution by Oeko-Institut

Contact at Oeko-Institut:

Simone Mohr
Researcher in Nuclear Engineering & Facility Safety Division
Oeko-Institut, Darmstadt office
Phone: +49 6151 8191-146

Stephan Kurth
Researcher in Nuclear Engineering & Facility Safety Division
Oeko-Institut, Darmstadt office
Phone: +49 6151 8191-108

Oeko-Institut is a leading independent European research and consultancy institute working for a sustainable future. Founded in 1977, the institute develops principles and strategies for ways in which the vision of sustainable development can be realised globally, nationally and locally. It has offices in three cities in Germany: Freiburg, Darmstadt and Berlin.

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