Switzerland is taking a long hard look at its nuclear power industry in the wake of the catastrophe in Japan. Switzerland currently gets about 40 percent of its electricity from nuclear energy, but its plants are ageing: the Beznau 1 pressurized water reactor, which began operation in 1969, is the oldest in the world still in operation. In 1990 the Swiss approved a moratorium on building new nuclear plants, but more recently voters, concerned to reduce fossil fuel consumption, changed their minds and backed replacements for the oldest nuclear plants.

All that changed early on Monday morning, when Switzerland's minister for energy and the environment, Doris Leuthard, made her announcement: all plans for building new nuclear plants would be suspended.

"Safety is the highest priority for us, so I have decided to suspend these plans, until we know for certain if our own safety regulations are enough in light of these new developments," said Leuthard.

"I can't tell you how long this suspension will last, because I want to know first the exact causes of the events in Japan, whether risks were underestimated, and how much this will affect our own nuclear safety regulations."

Her decision made the Swiss government the first in Europe to officially change its nuclear power policy in response to the disaster in Japan. Germany and then the European Union as a whole swiftly followed, announcing stress tests across the EU, and, in Germany, even taking older plants out of commission.

Couldn't withstand an earthquake

Many Swiss would like their own government to go further and mothball Switzerland's oldest plants too. The reason: a study known as the Pegasos Project, carried out between 2001 and 2004, revealed that, when it came to earthquake protection, Swiss plants were not up to scratch.

"In the past, it's a fact: we underestimated the risk of earthquakes," admitted Georg Schwarz, deputy director of the Swiss Federal Nuclear Safety Inspectorate.

"The new study we carried out shows that the earthquake risk in Switzerland is actually twice as big as we originally thought - that means our nuclear power stations will have to re-examine their earthquake protection measures."

And indeed, earthquakes are not unknown in Switzerland. Although most recent ones have been relatively minor, the city of Basel experienced a huge quake in 1353. Regarded by modern seismologists as the most significant earthquake to hit central Europe in recorded history, it flattened the entire centre of the city, in which hundreds died. Every church and castle within a 30 kilometer radius was destroyed.

It is estimated that earthquake measured 6.5, possibly even 7, on the Richter scale, and safety experts are uncertain as to whether Switzerland's nuclear power stations could withstand such an event.

Calls for new safety regulations

As a result, new safety measures are already underway: the Beznau 1 plant, which came on stream in 1969, has had to build supplementary diesel generators, which would, in the event of an earthquake, cool down the fuel rods in an attempt to prevent a meltdown.

"We have been investing a lot," said Beat Römer, spokesman for Axpo, the company which runs Beznau 1, "one and half billion francs. One of the most important investments has been to build our own emergency system, but we are not finished, we are planning more safety measures costing around 300 million francs."

But that is the problem, according to Swiss nuclear skeptics: improving the ageing plants will take years, and during that time they may not satisfy safety requirements. Leo Scherer of Greenpeace believes the government must do more than just suspend plans for new plants.

"It's clear that in Switzerland we could have an earthquake that could be much stronger than the ones our current nuclear plants have planned for" he said.

"Something must be done to rectify this immediately, and, if we do find big safety gaps, we are going to have to decommission our plants - it's the only solution."

Huge task

For the Swiss government, it's a dilemma. With 40 percent of Switzerland's energy coming from nuclear sources, it would be a huge task to find a quick replacement. And so for now the government has ordered immediate safety inspections of all the Swiss nuclear plants, including extensive checks on earthquake protection.

Some changes are inevitable; new safety measures will have to be installed, but while that happens - and that will take an estimated five years or more - Switzerland's nuclear plants, if they continue in use, will, experts fear, be operating below ideal safety standards.

Author: Imogen Foulkes, Berne / ccp

Editor: Michael Lawton