November 4, 2009

AECL "on cusp” of repairs

by Terry Myers

Atomic Energy of Canada said last week it is "on the cusp” of beginning physical repairs to the NRU reactor at Chalk River.

In its 27th update on the NRU shutdown, AECL said cleaning of the six sites on the reactor vessel needing repair has now been completed, paving the way for the "weld buildup” repairs themselves.

As part of the weld preparation, several samples of vessel material were "scooped” from the vessel wall, the company said.

"These scoop samples are presently undergoing analysis. This will provide AECL with a better understanding on the nature of the corrosion in the vessel and will allow final weld tests on actual vessel material.”

In a new video, project manager David Cox said testing the "scoop” samples is the "last piece of the puzzle in convincing ourselves we have covered all the bases.”

"Although we've got a detailed plan, we are facing challenges almost every day,” he said.

Despite those challenges, the company has managed to stay on schedule and "we're on the cusp now of moving into the repair stage” of the work, Cox said.

"We have to be on top of all of the activities that are critical to the sequence of operations to return (the reactor) to service in the first quarter of 2010.”

NRU has  been shut down since May 15 after a small heavy water leak was detected.

The leak was later traced to an area of corrosion near the base of the reactor vessel.

The areas of corrosion can only be reached through small openings about four inches across on top of the reactor deck, about 30 feet above the level of the actual corrosion.

Cox has said doing the repairs will be like "trying to change the oil in your car from your living room.”

Special tools have had to be developed to do both the cleaning of the reactor vessel and welding of the affected areas.

Cox said the company has had a "great partnership” going with several outside suppliers that are developing the special tools.

"Working together with all the groups within AECL and the external vendors is really important to our success,” he said.

"It's all happening in some cases in six weeks, which is very fast in this kind of environment where we have to ensure safety and nuclear reliability in all components.”