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With Thin Lead ShieldsThis story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.Before the Fukushima 50, there were the Chernobyl liquidators.

After the nuclear reactor explosion 25 years ago today that rained down radioactive material over Ukraine, Belarus, and western Russia, a corps of plant employees, firefighters, soldiers, miners, construction workers, and volunteers were called in to clean up the mess.

The government of the former Soviet Union called them "liquidators," meaning those who eliminate the consequence of an accident. But from early on, it became clear that they could not eliminate, but only contain, the damage from what still stands as the largest nonmilitary release of radioactivity in history.

At the peak of the cleanup, an estimated 600,000 workers were involved in tasks such as building waste repositories, water filtration systems, and the "sarcophagus" that entombs the rubble of Chernobyl reactor number four. They also built settlements and towns for plant workers and evacuees.

The International Atomic Energy Agency (IAEA) says some 350,000 of the liquidators in the initial plant cleanup received average total body radiation doses of 100 millisieverts. That’s a dose equal to about 1,000 chest x-rays and about five times the maximum dose permitted for workers in nuclear facilities.

The Soviets did not have adequate protective uniforms, so those enlisted to enter highly radioactive areas cobbled together their own shields. Some workers, like the ones shown here, attached aprons made of lead sheets just 2 to 4 millimeters thick over their cotton work clothing. Authorities agree that 28 workers lost their lives to acute radiation sickness, while another 106 of the liquidators were treated and survived. But the health toll for the survivors continues to be a matter of debate. One advocacy group, the Chernobyl Union, says 90,000 of the 200,000 surviving liquidators have major long-term health problems.

Some liquidator advocates see renewed awareness in the wake of the earthquake-and-tsunami-triggered disaster at the Fukushima Daiichi nuclear power plant in Japan, and the attention to the perils faced by the cleanup workers there (sometimes called the "Fukushima 50," although their numbers are likely far greater.)

"Thanks to Fukushima they paid attention to us," Vyacheslav Grishin, head of the Chernobyl Union, told the news agency AFP, as a ceremony was held in Moscow to honor the liquidators on the eve of the Chernobyl accident’s 25th anniversary.

(Related: "Pictures—A Rare Look Inside Fukushima Daiichi Nuclear Plant")—Marianne Lavelle

Photograph by Igor Kostin, Sygma/Corbis

Pictures: "Liquidators" Endured Chernobyl 25 Years Ago

Robots couldn't handle the intense radiation at Chernobyl, so the dangerous nuclear cleanup job fell to the "liquidators" — a corps of soldiers, firefighters, miners, and volunteers.

April 28, 2011