22 Jan (NucNet): Belgium’s nuclear regulator has said tests to confirm the structural integrity of the country's Doel-3 and Tihange-2 nuclear reactors show nothing that would require a permanent shutdown of the units, but they have asked for some supplementary tests.
Checks were carried out after indications of flaws were found in the units’ reactor pressure vessels (RPVs) last year.
Electrabel, the operator of both plants, presented its findings in a report to Belgium’s Federal Agency for Nuclear Control (FANC) on 5 December 2012, including a proposed action plan for restarting both units.
FANC has now asked Electrabel, a subsidiary of France’s GDF Suez, to carry out “certain tests” again and to provide additional information.
FANC said it had particularly asked for testing of the RPVs at a pressure higher than their usual pressure. Operational pressures for the RPVs are about 150 to 160 bars, or about 150 times atmospheric pressure.
FANC said it had also asked other experts to assess the report’s findings. These include FANC’s technical subsidiary Bel V, Belgian inspection and monitoring specialists AIB-Vinçotte, and regulatory authority experts in other countries.
Electrabel said it had taken note of FANC's advice and would take the necessary action. FANC told NucNet it could not say exactly how long the tests would take, but it expected results would probably be available next month.
The flaws in the Doel-3 RPV were originally suspected in August 2012 and at that point the unit was shut down for inspection. As a precaution, Belgium’s six other commercially operational reactors were also checked for RPV flaws. Later in September, FANC said there were indications of similar flaws in the Tihange-2 RPV, but not in any other reactors.
In December 2012, Electrabel said results of tests carried out to confirm the structural integrity of Doel-3 and Tihange-2 showed that both units were safe for immediate restart and operation.
The company said the tests demonstrated that the RPVs’ structural integrity meets “within significant margins” all safety criteria. The investigations and calculations carried out were subjected to “a stringent control procedure” that was validated by outside experts, Electrabel said.
Doel-3 is scheduled to be decommissioned in 2022 and Belgium plans to close all its nuclear power stations by 2025.
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