Liquidators clean the roof of the No. 3 reactor. At first, workers tried clearing the radioactive debris from the roof using West German, Japanese, and Russian robots, but the machines could not cope with the extreme radiation levels so authorities decided to use humans. In some areas, workers could not stay any longer than 40 seconds before the radiation they received reached the maximum authorized dose a human being should receive in his entire life. #

The majority of the liquidators were reservists ages 35 to 40 who were called up to assist with the cleanup operations or those currently in military service in chemical-protection units. The army did not have adequate uniforms adapted for use in radioactive conditions, so those enlisted to carry out work on the roof and in other highly toxic zones were obliged to cobble together their own clothing, made from lead sheets and measuring two to four millimeters thick. The sheets were cut to size to make aprons to be worn under cotton work wear, and were designed to cover the body in front and behind, especially to protect the spine and bone marrow. #

A military helicopter spreads sticky decontamination fluid supposed to reduce the spread of radioactive particles around the Chernobyl nuclear plant a few days after the disaster. #

Liquidators clear radioactive debris from the roof of the No. 4 reactor, throwing it to the ground where it will later be covered by the sarcophagus. These "biological robots" have only seconds to work—time to place themselves by a pile of debris, lift a shovel load, and throw it among the ruins of reactor No. 4. #

A Soviet technician checks water taken from a stream near Kiev for radiation on May 9, 1986. Checks were being performed hourly to be certain that water supplies were safe to use in the wake of the Chernobyl nuclear-plant accident. #

A bulldozer digs a large trench in front of a house before burying the building and covering it with earth. This method was applied to entire villages that were contaminated after the Chernobyl disaster. #

A Chernobyl nuclear-power-plant worker holds a dosimeter to measure radiation levels, with the under-construction sarcophagus, meant to contain the destroyed reactor, visible in the background, in this photo taken in 1986. #

Following orders issued by Soviet authorities to mark the end of cleanup operations on the roof of the No. 3 reactor, three men were requested to post a red flag atop the chimney overlooking the destroyed reactor, reached by climbing 78 meters up a spiral staircase. The flag bearers were sent despite the dangers posed by heavy radiation, and after a group of liquidators had already made two failed attempts by helicopter. The radiation expert Alexander Yourtchenko carried the pole, followed by Valéri Starodoumov with the flag, and Lieutenant Colonel Alexander Sotnikov with the radio. The whole operation was timed to last only 9 minutes, given the high radiation levels. At the end, the trio were rewarded with a bottle of Pepsi (a luxury in 1986) and a day off. #

At Moscow's No. 6 clinic, which specializes in radiation treatment, a patient recovers after a bone-marrow operation. A doctor examines the patient in a sterile room. The examination is carried out in an individual, air-conditioned chamber via specially created openings to avoid direct contact and contamination. #