Safety Of Canada's Nuclear Reactors In Question Because Of Design Feature

June 29, 2009 9:56 a.m. EST

Ottawa, Ontario (AHN) - Canada's seven nuclear stations which use Candu technology have a positive reactivity feedback design feature which may lead to dangerous power pulses in the event of a major accident.

According to internal documents of the Canadian Nuclear Safety Commission obtained by Greenpeace Canada under an Access to Information Act request, nuclear stations are designed to speed up atomic chain reactions when water that is used to cool reactors leak. During such accidents, reactors must be immediately shut down to prevent overheating.

Overheating and the loss of coolant could damage a nuclear station's containment system, leading to radioactive material to spread outside.

These findings led the commission to warn nuclear power plants in Canada to run at a lesser power because of the apparently weak safe features of the stations, according to the Globe and Mail. Even if the commission and utilities that run the nuclear reactors had to spend so much to address these safety issues, there is no guarantee it will be fully resolved.

The design feature caused the Atomic Energy of Canada to discontinue plans to operate the two Maple reactors in Chalk River despite spending $500 million. The Chalk River facility has been closed for more than one month due to a water leak and is at the center of an ongoing medical crisis in Canada and other parts of the world. The facility produces medical isotopes used for certain screening procedures manufactured.

Canadian Nuclear Safety Commission director-general Greg Rzentkowski has told the Globe and Mail the Chalk River reactors' shutdown features were designed to counteract positive reactivity by preventing chain reactions before they lead to overheating even if there is a drastic loss of coolant.

Greenpeace has also said the Candu-6 design had contributed to the Chernobyl explosion, and is vulnerable to a terror attack.

Concerns about the positive reactivity design come after a 21-member peer review team from the International Atomic Energy Agency inspected Canada's nuclear stations. According to CNSC president Michael Binder, the review team which issued it findings two weeks ago, found out that Canada "has a mature and well-established nuclear regulatory framework and the CNSC has done its job effectively in protecting the safety, health and security of Canadians and its environment."

The final report of the IRRS peer review team will be made public in fall.