"How'd you like to live next to that plant and every time you turn on the tap to take a drink you have to think about whether it's safe?" asked Joe Cosgrove, the head of parks in Godley, Illinois, a town adjacent to Braidwood.

Cosgrove and some scientists and anti-nuclear activists who monitor health issues related to nuclear power say the delay in reporting the spills is indicative of industry and regulatory obfuscation bordering on cover-up.

"We don't know what else has been leaked from that site. When they close ranks, you can't believe them," Cosgrove said, referring to the plant owner and the Nuclear Regulatory Commission, which oversees safety at the nation's 103 commercial reactors, including 11 in Illinois.

Cosgrove recalled a 2002 spill of diesel fuel that was initially mischaracterized by Braidwood's operators as run-off from a parking lot. When information about the tritium spills arose as part of the town's since-dropped lawsuit over the fuel, Exelon asked the court to bar any questions about it.

A local doctor and his wife, Joseph and Cynthia Sauer, whose daughter contracted brain cancer when they lived near the Dresden plant, have collected data about heightened rates of cancer and birth defects near the Illinois plants in the period after the spills began. They say they were brushed off by the NRC.

CONCLUSIVE INVESTIGATION

"I don't say that people don't have concerns, but any suggestion that we are in cahoots with the industry to suppress (information) is baseless," NRC spokesman Jan Strasma said.

The industry and the NRC say existing medical research shows people living near nuclear plants are safe and limits on discharges of radioactive liquids and gases are adequate.

But some scientists and at least one congressman want a conclusive investigation of the health risks. They say that while tritium is like water, if ingested some of it may remain in the body where it can damage cells, leading to cancers, birth defects and miscarriages.

US Rep. Edward Markey has been unable to secure government funding for a health study on people living near nuclear plants, and the Massachusetts Democrat says he opposes US President George W. Bush's prescription to build a new generation of nuclear reactors to lessen reliance on fossil fuels until more is known.

"The president's plan is misguided. It presents health risks, creates additional nuclear waste that we have no long-term solution for, creates additional terrorist targets that we do not adequately defend, and costs an enormous amount of money. (Bush's) phrase 'clean, safe nuclear power' is oxymoronic," he said.

IS IT SAFE?

Exelon and the NRC say a 1998 spill of 3 million gallons (11.3 million litres) of tritium -- a form of hydrogen that becomes radioactive water when it contacts air -- did contaminate ground water that breached the Braidwood plant boundary. But the radioactivity had not risen above federal limits where people live or have their drinking water wells.

At Dresden, the 276,000-gallon (1 million-litre) tritium leak is still on-site, and the spill at Byron was found inside concrete vaults along an effluent pipe.

The plants are all within 100 miles (160 km) of Chicago in northern Illinois, which has the largest nuclear capacity of any US state, about equal to Great Britain's.

The spilled tritium was destined to be discharged as effluent in rivers anyway, authorities said, and they were not explicitly required to notify the public about it -- a reporting loophole Illinois congressmen want closed.

"It's not like people are going to start dropping like flies from this level of radiation," said Arjun Makhijani of the Institute for Energy and Environmental Research.