MONTREAL

Ontario Hydro, the largest power utility company in North America, is to close seven of its 19 Candu heavy-water nuclear reactors following an internal report that has heavily criticized the management of its nuclear division.

The company's president and chief executive officer, Allan Kupcis, has resigned, and its board has approved a major overhaul of its production facilities estimated to cost between C$5 billion and C$8 billion (US$3.6 billion to US$5.75 billion) over the next four years.

William Farlinger, Ontario Hydro's chairman, admitted last week that management practices appeared to have been deteriorating for the past 10 years. He said that the nuclear unit operated in the early years as “some sort of special nuclear cult”. Farlinger said: “I don't think anybody understood the level to which our nuclear management had sunk.”

Nuclear officials are keen to point out that the report emphasizes that the problems lay with management, rather than with the technology. But Gary Kugler, vice-president for commercial operations at Atomic Energy of Canada (AECL), the company that designed and built the Candu reactors, said: “This is not welcome news.”

AECL is planning to submit a proposal next month to sell two or more of its reactors to Turkey, and the company is trying to increase its sales to China, South Korea and Romania, which already have Candus. Indonesia, Vietnam, Thailand and the Philippines are also potential customers.

AECL officials are having to reassure such countries that the problems that led to the Canadian shutdown are not typical of the Candus.

Last year, nuclear power provided about 54 per cent of Ontario's electricity, down from 60 per cent or more several years earlier. In 1987, Ontario had six of the ten top-ranked nuclear reactors in the world, but their problems have been growing in recent years. In 1983, a ruptured pressure tube at the Pickering plant cost about C$1 billion to repair – more than the station's original cost.

Last December, the Atomic Energy Control Board, the nuclear regulator, produced a highly critical report on Ontario Hydro and gave the Pickering station an operating licence for only six months. In January, Kupcis brought in US nuclear experts to take over the utility's nuclear operations and report on its problems (see Nature 385, 287; 287 1997). It was their report that led to his resignation.

It is not clear whether all the reactors that are being shut down will eventually reopen. Those that do reopen will require upgrades, and any reactors that are closed permanently will have to be replaced by more expensive fossil-fuel plants.