Chernobyl – 29 years after the disaster. How it happened. ... 28 PHOTOS

Chernobyl – 29 years after the disaster. How it happened.

28 PHOTOS







In the early morning hours of April 26, 1986, the Chernobyl nuclear power plant in Ukraine (formerly part of the Soviet Union) exploded. It was the worst nuclear disaster the world has ever seen.

Located about 81 miles (130 km) north of the city of Kiev, Ukraine, and about 12 miles (20 km) south of the border with Belarus, the four reactors at the Chernobyl Nuclear Power Plant were designed and built during the 1970s and 1980s.

The nearest town to the power plant was the newly built city of Pripyat, which housed almost 50,000 people in 1986. About 12,000 residents used to live in the second town - Chornobyl. The remainder of the region was primarily farms and woodland.

The day before the Chernobyl nuclear disaster, plant operators were preparing for a one-time shutdown to perform routine maintenance on reactor number 4. According to official version: in violation of safety regulations, operators disabled plant equipment including the automatic shutdown mechanisms.

At 1:23 a.m. on April 26, when extremely hot nuclear fuel rods were lowered into cooling water, an immense amount of steam was created, which — because of the RBMK reactors' design flaws — created more reactivity in the nuclear core of reactor number 4. The resultant power surge caused an immense explosion that detached the 1,000-ton plate covering the reactor core. It released the radiation into the atmosphere and cut down flow of coolant into the reactor.

A few seconds later, a second explosion of even greater power than the first blew the reactor building apart and spewed burning graphite and other parts of the reactor core around the plant. After that several big fires started around the damaged reactor and reactor number 3, which was still operating at the time of the explosions.

The explosions killed two plant workers, who were the first of several workers to die within hours of the accident. For the next several days the firemen and emergency crews tried desperately to distinguish the fires and stop radiation leaks. Many of them died from the radiation sickness. Twenty-eight of the workers at Chernobyl died in the four months following the accident, according to the U.S. Nuclear Regulatory Commission (NRC), including some heroic workers who knew they were exposing themselves to deadly levels of radiation in order to secure the facility from further radiation leaks.


Most of the radiation released from the failed nuclear reactor was from iodine-131, cesium-134 and cesium-137. Iodine-131 has a relatively short half-life of eight days, according to UNSCEAR, but is rapidly ingested through the air and tends to localize in the thyroid gland. Cesium isotopes have longer half-lives (cesium-137 has a half-life of 30 years) and are a concern for years after their release into the environment.

On April 27, the residents of Pripyat were evacuated — about 36 hours after the accident had occurred. By that time, many were already complaining about vomiting, headaches and other signs of radiation sickness. Officials eventually closed off an 18-mile (30 km) area around the plant; residents were told they would be able to return after a few days, so many left their personal belongings and valuables behind.

The prevailing winds at the time of the accident were from the south and east, so much of the radiation plume traveled northwest toward Belarus. Nonetheless, Soviet authorities were slow to release information about the severity of the disaster to the outside world. But when radiation alarms began to go off at a nuclear plant in Sweden, authorities were forced to reveal the full extent of the crisis.

Within three months of the Chernobyl accident, a total of 31 people died from radiation exposure or other direct effects of the disaster, according to the NRC, UNSCEAR and other sources. More than 6,000 cases of thyroid cancer may eventually be linked to radiation exposure in Ukraine, Belarus and Russia, though the precise number of cases that are directly caused by the Chernobyl accident is difficult (if not impossible) to ascertain.

Shortly after the radiation leaks from Chernobyl occurred, the trees in the woodlands surrounding the plant were killed by high levels of radiation. This region came to be known as the "Red Forest" because the dead trees turned a bright ginger color. The trees were eventually bulldozed and buried in trenches.

The damaged reactor was hastily sealed in a concrete sarcophagus intended to contain the remaining radiation: How effective this sarcophagus has been — and will continue to be into the future — is a subject of intense scientific debate. Plans to construct a safer and more permanent containment structure around the reactor have yet to be implemented.

About 1,350 Soviet military helicopters, buses, bulldozers, tankers, transporters, fire engines and ambulances were used while fighting against the April 26, 1986 nuclear accident at Chernobyl. All were irradiated during the clean-up operation

Despite the contamination of the site — and the inherent risks in operating a reactor with serious design flaws — the Chernobyl nuclear plant continued operation for many years, until its last reactor was shut down in December of 2000. The plant, the ghost towns of Pripyat and Chernobyl, and a large area surrounding the plant known as the "zone of alienation" are largely off-limits to humans.

Read the other our articles about the worst human made disaster in worlds history:

The Chernobyl Disaster: the 25th anniversary

The Chernobyl Disaster: the 25th anniversary. Part II

The Chernobyl Disaster: the 25th anniversary. Part II

Chernobyl Nuclear Power Plant during its construction (1970s)

Parade in Kiev on May 1st 1986 (only 130 km from Chernobyl). The information about the disaster didn’t release yet by the Soviet authorities.

Aerial photo – during fighting against nuclear accident at Chernobyl

Environmental activists tagged contaminated containers. Bremen, Northern Germany, February 6, 1987.

Chernobyl Nuclear Power Plant

Chernobyl Nuclear Power Plant during its construction (1970s)

The workers of the Chernobyl nuclear power plant pass control room of the destroyed 4th power unit. Photo taken on April 14, 1998.

Worker checked the radiation level of meat. Frankfurt, West Germany, May 12, 1986. According to the Minister for Social Affairs of the federal state of Hesse, after the explosion of the Chernobyl all the meat must be checked to the radiation level.

The control panel of the 4th unit of the Chernobyl nuclear power plant April 14, 1998.

Workers who constructed the concrete sarcophagus covering the Chernobyl reactor in the memorable 1986 photo near the unfinished construction site. Thousands of people who worked during the liquidation of the Chernobyl disaster died from the radiation poisoning.

Near Chernobyl Nuclear Power Plant

The nearest town to the power plant – Pripyat after the disaster

The duty operator of a nuclear reactor control. The last working reactor ?3 of Chernobyl Nuclear Power Plant. Tuesday, June 20, 2000.

Destroyed by fire and then collapsed roof of the Chernobyl nuclear power plant.

Classroom at a school in the ghost town of Pripyat, which is located near the Chernobyl nuclear power plant, May 26, 2003

The television frame in the room of one of the hotels in the city of Pripyat, May 26, 2003.

Girls, 17-year-old Oksana (right) and 15-year-old Alla affected by the Chernobyl disaster of 1986, are being treated with infrared rays at Children's Hospital "Tarara" in the Havana, Cuba.

Roof of reactor ?4 of Chernobyl Nuclear Power Plant.

Worker of the Chernobyl nuclear power plant worker measures radiation levels after the working day, April 12, 2006.

The main room of the 1st unit of the Chernobyl nuclear power plant April 29, 1986 in Chernobyl.

The construction crew in during work to strengthen the sarcophagus covering the destroyed 4th unit of Chernobyl Nuclear Power Plant .April, 2006

The Soviet health worker examines a child who had been evacuated from the area of the nuclear disaster near Kiev May 11, 1986.

Chairman of the Presidium of the Supreme Soviet of the USSR Mikhail Gorbachev (center) and his wife Raisa Gorbachev during a meeting with the leadership of the Chernobyl Nuclear Power Plant. February 23, 1989. It was the first Soviet leader to visit the station after the accident, which occurred in April 1986.

Kiev residents stand in line for forms to check for contamination by radiation after the Chernobyl disaster in Kiev, May 9, 1986.

The boy reads the notice at the gate of the playground in Wiesbaden, May 5, 1986. It says: "This area is temporarily closed." A week after the explosion of the nuclear reactor in Chernobyl April 26, 1986 the municipal council of Wiesbaden closed all playgrounds after the discovery of radioactivity levels from 124 to 280 becquerels.

Military helicopter, used during fighting against nuclear accident at Chernobyl.

About 1,350 Soviet military helicopters, buses, bulldozers, tankers, transporters, fire engines and ambulances were used while fighting against the April 26, 1986 nuclear accident at Chernobyl. All were irradiated during the clean-up operation.

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