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OTTAWA — A planned 33-day shutdown of the NRU isotope reactor at Chalk River is underway to allow the first major inspection since emergency repairs ended last August.
The outage began Sunday, part a commitment by operator Atomic Energy of Canada Ltd. (AECL) to inspect the reactor’s repaired containment vessel within nine months of returning to service after a 15-month, $70-million breakdown.
That crisis forced hospitals and doctors worldwide to scramble for scarce alternate medical isotope supplies and threatened Canada’s international dominance in nuclear medicine.
It followed another emergency safety shutdown, in 2007, that ended when Parliament legislated the reactor to resume operation. The move overruled a refusal by the Canadian Nuclear Safety Commission (CNSC) to allow a restart until a backup safety system was installed to prevent the remote risk of a core meltdown during an earthquake or other disaster, a fear recently borne out in Japan.
In a statement Thursday, AECL said the isotope community was informed, “well in advance of this outage and have taken steps to adjust their activities.”
The key task will be to inspect repairs to the reactor’s 65,000-litre heavy-water containment vessel, which sprang a pinprick leak in May 2009. Several other corrosion spots also required complex repairs in the highly radioactive environment.
Since then, NRU has been operating on a 28-day cycle, including regularly scheduled five-day outages for maintenance and other supporting operations activities. The scope of the current planned inspect requires far more down time.
The reactor, two hours northwest of Ottawa, is scheduled to return to service June 17. It is the world’s oldest operating nuclear reactor and will mark 54 years of service Nov. 3.