AECL provides update on NRU activities
Thursday, Jan 14, 2020
The following information bulletin is in accordance with Atomic Energy of Canada Limited’s (AECL) ongoing commitment to voluntary public disclosure of events related to the Chalk River Laboratories (CRL).

AECL reports that the NRU reactor vessel repair activities are currently focused on preparation work in advance of the next series of weld repairs that will use horizontal welding machines. The overall repair process, which began December 12, is proving effective but is progressing at a slower pace than originally anticipated.  Welding equipment is currently undergoing modifications and testing for use in applying the horizontal repairs.  Engineering analysis and the qualification of welders for each specific repair site continues. To date, 27 per cent of the repair activities have been completed.

Plans are being modified to optimize the schedule recognizing safety and a high quality repair must be maintained. The current schedule targets return to service by the end of March 2010. However, if there are continuing challenges with the repair process, the NRU return-to-service schedule could extend into April. 

Further guidance on a return-to-service date will be provided when repairs to all sites have been undertaken. The repairs are scheduled to be completed in February.

Guidance on the duration of the shutdown continues to be founded on the best evidence available, including the most up-to-date analysis of inspection data, progress on repair strategies and critical path requirements for restart after an extended shutdown.

Activities related to the start-up phase of the NRU return-to-service project are on-going. The multi-stage start-up process is being conducted by a dedicated team working in parallel with the repair team. There are 19 start-up procedures involving more than 1,000 subset activities required to safely return the reactor to high power.

The first medical isotopes will begin to be removed from the NRU for processing and distribution within 10 days of the reactor being returned to service.

More information on the return to service of the NRU is available at, including two new video updates explaining the sequence of events required to bring the NRU back to high power once the repair welds are complete.  Both videos highlight the 1,000+ start-up activities, and multiple maintenance upgrades that are being performed in addition to the repairs in order to ensure the NRU reactor is restarted safely and continues to operate well into the future.

The Canadian Nuclear Safety Commission safety inspectors continue to provide independent regulatory oversight of AECL activities at the Chalk River site.

There is no threat to workers, the public, the environment or nuclear safety related to this event.


Source: AECL

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