Belgium's nuclear regulator FANC on Wednesday dismissed a request from German Environment Minister Barbara Hendricks to temporarily shut down two defect-prone nuclear reactors until questions can be answered about their safety.
"The FANC remains convinced that the [two reactors] comply with international safety standards and that there is no need to shut down these units from a nuclear safety point of view," the regulator said in a statement.
Technical problems with Belgium's ageing nuclear plants have created tensions with neighbouring Germany, which is moving towards clean and sustainable energy sources and has passed legislation that requires the closure of all its commercial nuclear reactors by 2022.
The Belgian reactors, Doel 3 and Tihange 2, were taken offline in 2012 after service checks indicated defects in the reactor pressure vessels. These were later found to be hydrogen flakes, formed when hydrogen bubbles became trapped during the manufacturing of the tank's steel rings.
FANC conducted analysis and consultations with international experts before announcing in November that the reactors could be relaunched.
But Hendricks said Wednesday that further tests should be carried out, noting that Germany's independent Reactor Safety Commission (RSK) had been unable to confirm that the reactors had sufficient security reserves in the case of a breakdown.
"Therefore I think it is right to take the sites off the grid, at least until the further investigations are concluded," Hendricks said in a statement issued during a visit to the eastern Chinese city of Nanjing, where she was attending a German-Chinese environment forum.
Doing so would "show that Belgium takes the concerns of its German neighbours seriously," Hendricks added.
The RSK study, seen by dpa, says that "questions have been left open" relating to some of the stress scenarios that the two plants were tested for.
It concludes that the reactors' load-bearing walls should withstand regular operations, but says there is not enough evidence that they would remain safe in the event of a fault.
Earlier this month, experts from Germany and Belgium discussed the findings at Tihange 2 and Doel 3 as part of a newly formed working group on nuclear security. Both sides were in favour of more analysis to back up indications that the sites are safe, Hendricks' office said.
"Our German colleagues asked lots of questions, but they did not raise any new issues that we had not taken into account during our review of the Doel 3 and Tihange 2 safety cases," said Director-General of the FANC Jan Bens. "Our conclusions remain unchanged, despite what Minister Hendricks says."
More than half of Belgium's electricity is generated by the four-reactor Doel plant in the north of the country, close to the Netherlands, and a three-reactor plant at Tihange in the east, near the German border.
Although all of Belgium's reactors were built at least 30 years ago, they are not among the oldest in operation in Europe.