AECL provides update on NRU activities

Monday, Mar 15, 2010

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 NRU reactor vessel repair activities continue. The overall repair process began on December 12, 2009. To date, 46 per cent of the repair activities and associated post-repair examinations have been completed.

Preparations for the final repair sequence continue. This next series represents the greatest level of complexity and will incorporate the installation of plates welded to the vessel wall combined with the application of horizontal weld build-up. The project team continues to work with third-party experts to finalize detailed repair procedures.

Every effort is being made to return the NRU to service as soon as possible. The program is driven by safety, producing a quality repair, conservative decision-making and completion of all the necessary analyses.

The very complex nature of the remaining repairs requires that extra precautions be taken.  Each of these repairs presents unique and more difficult challenges that require first-of-a-kind technical solutions. To ensure that the repair process itself does not cause damage to the vessel an additional level of preparation is necessary to program the welding sequences and to qualify the welders. 

This additional preparation and repair work has added to the time required to return NRU to service.  As a result, the current return-to-service is projected to be during the second half of May 2010. Material risk does exist that this schedule will be adjusted. As a consequence, AECL and its expert advisors are evaluating the work schedule and conducting further analysis around the evolving repair techniques. All guidance continues to be founded on the best evidence available.

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.

A more comprehensive explanation of these repair challenges can be found on the NRUCanada.ca website. Recently posted videos provide an illustrated overview of the weld repair challenges along with the research and analysis underway to ensure that the weld repairs are completed successfully with minimal impact or stress on the NRU vessel.

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