Pickering B Safety Margin Slips Again

Jeffbrackett - May 17, 2008

A recent Canadian Nuclear Safety Commission staff report says that the safety margins for Pickering B are not what they used to be. Problems arose during a recent reassessment of the seriousness of the positive void coefficient accident scenario.

The CNSC staff pointed out that with the passage of time they have discovered unanticipated phenomena and problems with design predictions leading to an erosion of safety margins. Much of the safety analysis for the aging reactors is based on hazard assessments conducted by Ontario Hydro (OPG) in the 1970's and early 1980's.

CNSC staff reported that in their view OPG has not assessed that these assessments remain valid according to current plant design, configuration or condition.

Now more than ever, as nuclear reactors age and their performance and safety margins become even more uncertain, we need to take a closer look and extend the primary nuclear emergency planning zone to 30 kilometers.

Visit to find out where you stand.

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