Atomic Energy of Canada Limited (AECL) has reported that during the fuel reloading of the National Research Universal reactor at Chalk River, Ontario, a specific set of reactor instrumentation, important to safe operation, was not responding and replacement of the instrumentation is estimated to add 10 to 15 days beyond the planned return-to-service date of July 31.

“The restart schedule is challenging with initially more than 3,000 different restart activities that must be completed prior to returning the reactor to service,” said the organization.

To date approximately 90 percent of these activities are complete, said AECL. The return-to-service team had loaded more than half the reactor fuel and completed the first stage of fuel loading and has conducted the first of four assessments used to verify fuelling calculations.
 
Canadian Nuclear Safety Commission's safety inspectors continue to provide independent regulatory oversight of AECL activities at the Chalk River site, added  AECL.