Review process for Belgian reactor restarts

Belgium's nuclear regulator has outlined a two-step review process for Electrabel's safety case report for the restart of the Doel 3 and Tihange 2 reactors. The reactors have been offline since 2012 because of concerns about defects in their reactor pressure vessels.

GDF Suez - Electrabel's parent - has said that "it hopes to submit a dossier to the Federal Agency for Nuclear Control (FANC) in late autumn in order to obtain permission for a restart of Doel 3 and Tihange 2."

FANC said that, together with its technical subsidiary Bel V, it intends to carry out a two-step review of Electrabel's safety case report. In the first step, a review will be made of the relevance of the methodology proposed by Electrabel. Depending on the conclusions of that review, FANC and Bel V will then inform Electrabel whether its safety case report for the restart of the reactors is eligible for review.

Doel 3 and Tihange 2 were taken offline in 2012 when ultrasound testing suggested the possible presence of cracks in their reactor vessels. Further investigations indicated that the defects are so-called hydrogen 'flakes' and were introduced during the manufacturing process. FANC allowed Electrabel to restart the units last May, requesting that further tests be conducted to evaluate the effect over time of these flakes.

In March, Electrabel brought forward planned outages for the two units after additional tests on hydrogen flakes suggested these may affect the mechanical properties of their reactor vessels. These outages were originally expected to last about six weeks, but the reactors remain offline awaiting the results of further tests.

FANC and Bel V have now put together an international review board to examine the results of these mechanical resistance tests. The expert panel is expected to review the relevance of Electrabel's translation of these test results to the pressure vessels of Doel 3 and Tihange 2.

While the expert panel studies the test results, FANC, Bel V and testing and inspection services company AIB-Vinçotte will review the methodology proposed by Electrabel for its safety case report.

"This means that the licensee will have to draw up its safety case report in correspondence with the methodology approved by the regulatory body," FANC said.

FANC will then analyse the safety case in depth, it said.

Researched and written
by World Nuclear News