France and Britain, the two EU countries with the largest nuclear industry, strongly opposed stringent stress tests on nuclear power plants following the Fukushima disaster in Japan. Energy Commissioner Günther Oettinger's proposal to introduce them was sponsored by Austria, a country without nuclear energy, and backed by Germany.
In a short statement, the European Commission announced that a meeting of the European Nuclear Safety Regulators Group (ENSREG) had ended without any results.
The Commission added that Oettinger had convened another ENSREG meeting for next week, on 19 and 20 May in Prague. Discussions will also continue at a lower level.
"Content is more important than timing. The public expects credible stress tests covering a wide range of risks and safety issues. This is what we are working on," Oettinger said in the statement.
National experts and regulators from several EU countries with nuclear reactors objected to including terrorist attacks as part of the security review of their nuclear installations.
This is despite an agreement reached at the highest political level following the Fukushima disaster to set the "highest standards" of nuclear safety in Europe (see 'Background').
The 143 nuclear power plants operating in Europe, plus the six under construction and the 15 planned, should be able to withstand any possible threat, including a malicious plane crash like the 9/11 terrorist attacks in the US, a cyber attack or acts by an operator who has lost his or her mind, EU leaders agreed in March.
France in particular pointed out that the threat of terrorism was not mentioned in the 25 March EU summit conclusions.
According to experts, if such draconian criteria are introduced, all existing nuclear power plants would need to close down.
Barroso not in sync with Oettinger?
In his public statements, Commission President José Manuel Barroso has revealed differences with Oettinger. He has refrained from mentioning 9/11-style terror threats, speaking instead of a "widest range of scenarios, natural and man-made".
But the German commissioner has thus far only repeated that he would not accept any watering down of the stringent tests proposed.
Under pressure from public opinion after Fukushima, Germany has reviewed its plans to extend the use of its older nuclear plants for another 10 to 15 years.
There is no deadline for adopting a decision on nuclear stress tests. What is certain is that planned nuclear power plants or installations under construction would be affected even in the absence of a decision.
In the event that the stress tests produce negative results for certain installations, decisions regarding their future will remain a national responsibility.
However, should upgrades not prove technically or economically feasible, reactors should be shut down and decommissioned, the Commission insists.