Almost all of Europe's nuclear reactors are in need of an urgent overhaul that could cost as much as $32bn, according to a leaked draft-report by the European Commission.
The Commission is expected on Thursday to finalise its stress test report, which was designed to ensure that a disaster similar to the one at Japan's Fukushima could not happen again.
The report will be debated by EU ministers later this month..
After that, the Commission intends in 2013 to propose new laws, including on insurance and liability to "improve the situation of potential victims in the event of a nuclear accident", the draft obtained by Reuters news agency said.
Of the 134 EU nuclear reactors grouped across 68 sites, 111 have more than 100,000 inhabitants living within 30 km.
Safety regimes vary greatly and the amount that needs to be spent to improve them is estimated at $13-32bn across all the reactors, the draft says.
France's nuclear watchdog has already said the country, which relies on nuclear power for about 75 per cent of its electricity, needs to invest billions of euros.
The lesson of Fukushima was that two natural disasters could strike at the same time and knock out the electrical supply system of a plant completely, so it could not be cooled down.
The stress tests found that four reactors, in two different countries, had less than one hour available to restore safety functions if electrical power was lost.
By contrast, four countries operate additional safety systems fully independent from the normal safety measures and
located in areas well-protected against external events. A fifth country is considering that option.
The main finding, the draft says, is that there are "continuing differences" between member states' safety regimes.
It also says provisions to ensure the independence of national regulators are "minimal".
Imad Khadduri, a nuclear analyst, told Al Jazeera that this report reflects "what is now an issue in Japan, which is the complacency of the nuclear industry, and the following up with modifications and updates on safety issues."
"European power reactors should take much more strident efforts in fixing and implementing the safety issues.
Khadduri went on to say that if the public "is going to be alarmed by the $30bn cost of it all, they should be more worried about how much it could cost to decommission reactors, which is incredibly costly."
The stress tests are a voluntary exercise to establish whether nuclear plants can withstand natural disasters, aircraft crashes and management failures, as well as whether adequate systems are in place to deal with power disruptions.
All 14 member states that operate nuclear plants took part, however, as did Lithuania, which is decommissioning its nuclear units.
From outside the 27-member bloc, Switzerland and Ukraine joined in the exercise.
The tests were meant to have been completed around the middle of the year, but countries were given extra time to assess more reactors.
Non-governmental organisations are among those who have criticised the process as not going far enough and having no powers to force the shut-down of a nuclear plant.
"The stress tests only give a limited view," said Roger Spautz, energy campaigner at Greenpeace, which believes nuclear power should be phased out.
He cited independent research earlier this year which said some European reactors needed to be shut down immediately, as well as the example of Belgium, where the Doel 3 and Tihange 2 reactors have been halted because of suspected cracks.
The draft report says the stress tests are not a one-off exercise and will be followed up. Existing legislation also needs to be enforced, it said.
The deadline for passing the existing nuclear safety directive into national law was July 2011. The Commission started infringement proceedings against 12 member states that missed it.
To date, two have still not complied but the report did not specified which ones.
The Commission does not comment on leaked drafts.
But on Monday, the EU energy spokeswoman said the recommendations were being finalised and would not be "very,
In France, the nuclear watchdog and operator EDF said they would not comment before seeing the official report.