Chalk River Information Bulletin

(2009 December 23) 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).

Repairs to the NRU reactor vessel continue at the Chalk River Laboratories, with approximately 11 per cent of the planned repairs completed to date. 

The process, which spans multiple days for each repair, requires many steps, including site preparation, weld build-up application and numerous inspections. Each repair site is unique in its structure and accessibility and is therefore subjected to a lengthy qualification and examination process.  Prior to initiating each individual repair, AECL welders must demonstrate through a series of test welds that they are qualified to conduct each specific weld. 

Following each repair, non-destructive examinations, including two types of ultrasonic inspection and an eddy-current inspection inside the vessel, are required in order to confirm the quality of the repair.  The inspection process is then followed-up with laser profiling of the vessel surface that has been welded.  The purpose of this profiling is to quantify the thickness of the weld and confirm if there has been any shape change in the vessel due to the welding process.

Repair efforts will continue over the holiday period, with crews continuing to work around the clock, seven days a week to carry on repairs to the NRU vessel. 

More information on the return to service of NRU is available at NRUCanada.ca, including a new video update from NRU Return-to-Service Project Director, David Cox. In his update, Mr. Cox provides an in-depth description of the many steps involved in performing the weld build-up repairs in the NRU reactor vessel. This includes the high degree of complexity in training for and performing each individual weld repair remotely. 

Guidance on the duration of the shutdown continues to be founded on the best evidence available, including the most up-to-date analysis of the inspection data, progress on repair strategies, and critical path requirements for restart after an extended shutdown. At this time, the application of the band weld build-up technique, and the number of identified repair sites indicates the NRU will return to service by the end of March (first calendar quarter) of 2010. Further guidance on a return-to-service date will be provided when more information becomes available.

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.

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Contact:

Dale Coffin
Director, Corporate Communications
AECL, 1-866-886-2325