Candu reactors seen as risk

Peter Calamai
Toronto Star
October 14, 2001

OTTAWA — The unusual design of Candu nuclear power stations like Pickering makes them peculiarly vulnerable to a terrorist attack, says the author of an accident risk study prepared for a Senate committee.

Consultant Gordon Thompson said in an interview Friday that Ontario’s nuclear stations were “susceptible” because the multiple reactors at each station rely on common systems for emergency core cooling and for vacuum containment.

Most of the world’s 400 nuclear generating stations have individual safety systems for each reactor unit, even at stations with two or more reactors.

But the shared Candu safety systems mean that a severe earthquake or an act of malice such as a terrorist attack could cause breaches at all eight nuclear reactors that make up the 2,300-megawatt station, Thompson said.

“The scenario of an eight-reactor accident has never been examined by anyone in Canada, basically because it is too uncomfortable, I imagine,” he said.

A self-described nuclear skeptic, Thompson heads the Institute for Resource and Security Studies, a small think-tank in Cambridge, Mass. He studied Ontario reactor safety in 1988 for a provincial government inquiry and also for an environmental coalition in 1993.

Thompson said risk assessment studies are necessary to estimate the consequences of a multi-reactor accident at an Ontario nuclear plant.

Depending on the robustness of fire and electrical systems, radioactive debris could be released, he said. He agrees with an American assessment that existing reactors — either U.S. or Canadian — were not designed to withstand the explosive force of a commercial aircraft laden with jet fuel.

The aircraft could knock out the shared safety systems or overload them by causing ruptures, he said.

In June, the Senate committee recommended that Ontario Power Generation be ordered by the Canadian Nuclear Safety Commission to conduct a full-scale analysis of probable risks at Pickering. Both the federal agency and the utility said a study was unnecessary.

The nuclear safety commission is just now finishing an analysis of the enhanced security measures that it ordered on Sept. 11 for about 30 Class One nuclear installations across Canada, including Candu power reactors in Ontario, Quebec and New Brunswick.

 

 

`The scenario of an eight-reactor accident has never been examined by anyone in Canada, basically because it is too uncomfortable, I imagine.’ – Gordon Thompson

 

 

Commission president Linda Keen plans to meet operators of the power reactors and other major nuclear installations in Ottawa within the next few weeks to discuss even more stringent security measures, according to officials at the federal regulatory agency.

These new measures will be based in part on two security reports that the agency commissioned in late 1999 and early 2000. The reports deal with possible sabotage at nuclear power plants and identifying vital areas within Candu reactors.

The commission is initially focusing on short-term safety improvements, said Jim Blyth, manager of the agency’s terrorism response. “We’re certainly not ruling out design changes, but they need to be carefully considered,” Blyth said.

Thompson stressed that an eight-reactor accident wouldn’t necessarily be eight times worse than the rupture of a single reactor elsewhere, because of differences in the production of radioactive materials.

He estimated that a hypothetical Pickering catastrophe could release twice as much cesium-137 as the 1,000-megawatt reactor that exploded at Chernobyl in 1986. This isotope is the longest-lived of the radioactive contamination released at Chernobyl, with a half-life of 30 years.

Ontario also has another eight-reactor station at Bruce on Lake Huron and a four-reactor station at Darlington, 75 kilometres east of Toronto.

In Ottawa yesterday, the RCMP weren’t saying much about a report of a Kuwaiti man found with documents detailing an Atomic Energy Canada building and a federal disease- and virus-control site, Canadian Press reports.

U.S. agents were briefed in Canada, according to the Los Angeles Times.

“It’s part of an ongoing investigation and we’re not in a position to provide any details right now,” said Serge Lalonde, an RCMP spokesperson in Ottawa.

It is unclear which buildings the documents may have detailed.

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