Sunday, October 25, 2009

Major Nuclear Power Plant Accidents

December 12, 1952

A partial meltdown of a reactor's uranium core at the Chalk River plant near Ottawa, Canada, resulted after the accidental removal of four control rods. Although millions of gallons of radioactive water poured into the reactor, there were no injuries.

October 1957

Fire destroyed the core of a plutonium-producing reactor at Britain's Windscale nuclear complex - since renamed Sellafield - sending clouds of radioactivity into the atmosphere. An official report said the leaked radiation could have caused dozens of cancer deaths in the vicinity of Liverpool.

Winter 1957-'58

A serious accident occurred during the winter of 1957-58 near the town of Kyshtym in the Urals. A Russian scientist who first reported the disaster estimated that hundreds died from radiation sickness.

January 3, 1961

Three technicians died at a U.S. plant in Idaho Falls in an accident at an experimental reactor.

July 4, 1961

The captain and seven crew members died when radiation spread through the Soviet Union's first nuclear-powered submarine. A pipe in the control system of one of the two reactors had ruptured.

October 5, 1966

The core of an experimental reactor near Detroit, Mich., melted partially when a sodium cooling system failed.

January 21, 1969

A coolant malfunction from an experimental underground reactor at Lucens Vad, Switzerland, releases a large amount of radiation into a cave, which was then sealed.

December 7, 1975

At the Lubmin nuclear power complex on the Baltic coast in the former East Germany, a short-circuit caused by an electrician's mistake started a fire. Some news reports said there was almost a meltdown of the reactor core.

March 28, 1979

Near Harrisburg, Pennsylvania, America's worst nuclear accident occurred. A partial meltdown of one of the reactors forced the evacuation of the residents after radioactive gas escaped into the atmosphere.

February 11, 1981

Eight workers are contaminated when more than 100,000 gallons of radioactive coolant fluid leaks into the contaminant building of the Tennessee Valley Authority's Sequoyah 1 plant in Tennessee.

April 25, 1981

Officials said around 45 workers were exposed to radioactivity during repairs to a plant at Tsuruga, Japan.

April 26, 1986

The world's worst nuclear accident occurred after an explosion and fire at the Chernobyl nuclear power plant. It released radiation over much of Europe. Thirty-one people died iin the immediate aftermath of the explosion. Hundreds of thousands of residents were moved from the area and a similar number are belived to have suffered from the effects of radiation exposure.

March 24, 1992

At the Sosnovy Bor station near St. Petersburg, Russia, radioactive iodine escaped into the atmosphere. A loss of pressure in a reactor channel was the source of the accident.

November 1992

In France's most serious nuclear accident, three workers were contaminated after entering a nuclear particle accelerator in Forbach without protective clothing. Executives were jailed in 1993 for failing to take proper safety measures.

November 1995

Japan's Monju prototype fast-breeder nuclear reactor leaked two to three tons of sodium from the reactor's secondary cooling system.

March 1997

The state-run Power Reactor and Nuclear Fuel Development Corporation reprocessing plant at Tokaimura, Japan, contaminated at least 35 workers with minor radiation after a fire and explosion occurred.

September 30, 1999

Another accident at the uranium processing plant at Tokaimura, Japan, plant exposed fifty-five workers to radiation. More than 300,000 people living near the plant were ordered to stay indoors. Workers had been mixing uranium with nitric acid to make nuclear fuel, but had used too much uranium and set off the accidental uncontrolled reaction.


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THE ATOMIC BOMBING OF HIROSHIMA

Hiroshima (August 6, 1945)

In the early morning hours of August 6, 1945, a B-29 bomber named Enola Gay took off from the island of Tinian and headed north by northwest toward Japan. The bomber's primary target was the city of Hiroshima, located on the deltas of southwestern Honshu Island facing the Inland Sea. Hiroshima had a civilian population of almost 300,000 and was an important military center, containing about 43,000 soldiers.

Little Boy at Tinian Island, August 1945The bomber, piloted by the commander of the 509th Composite Group, Colonel Paul Tibbets, flew at low altitude on automatic pilot before climbing to 31,000 feet as it neared the target area. At approximately 8:15 a.m. Hiroshima time the Enola Gayreleased "Little Boy," its 9,700-pound uranium bomb, over the city. Tibbets immediately dove away to avoid the anticipated shock wave. Forty-three seconds later, a huge explosion lit the morning sky as Little Boy detonated 1,900 feet above the city, directly over a parade field where soldiers of the Japanese Second Army were doing calisthenics. Though already eleven and a half miles away, the Enola Gay was rocked by the blast. At first, Tibbets thought he was taking flak. After a secondEnola Gay returning from Hiroshima mission, Tinian Field, August 6, 1945 shock wave (reflected from the ground) hit the plane, the crew looked back at Hiroshima. "The city was hidden by that awful cloud . . . boiling up,mushrooming, terrible and incredibly tall," Tibbets recalled. The yield of the explosion was later estimated at 15 kilotons (the equivalent of 15,000 tons of TNT).

On the ground moments before the blast it was a calm and sunny Monday morning. An air raid alert from earlier that morning had been called off after only a solitary aircraft was seen (the weather plane), and by 8:15 the city was alive with activity -- soldiers doing their morning calisthenics, commuters on foot or on bicycles, groups of women and children working outside to clear firebreaks. Those closest to the explosion died instantly,Victim of atomic attack with the pattern of her clothing burned into her back. their bodies turned to black char. Nearby birds burst into flames in mid-air, and dry, combustible materials such as paper instantly ignited as far away as 6,400 feet from ground zero. The white light acted as a giant flashbulb, burning the dark patterns of clothing onto skin (right) and the shadows of bodies onto walls. Survivors outdoors close to the blast generally describe a literally blinding light combined with a sudden and overwhelming wave of heat. (The effects of radiation are usually not immediately apparent.) The blast wave followed almost instantly for those close-in, often knocking them from their feet. Those that were indoors were usually spared the flash burns, but flying glass from broken windows filled most rooms, and all but the very strongest structures collapsed. One boy was blown through the windows of his house and across the street as the house collapsed behind him. Within minutes 9 out of 10 people half a mile or less from ground zero were dead.

Before and After aerial photographs of HiroshimaPeople farther from the point of detonation experienced first the flash and heat, followed seconds later by a deafening boom and the blast wave. Nearly every structure within one mile of ground zero was destroyed, and almost every building within three miles was damaged. Less than 10 percent of the buildings in the city survived without any damage, and the blast wave shattered glass in suburbs twelve miles away. The most common first reaction of those that were indoors even miles from ground zero was that their building had just suffered a direct hit by a bomb. Small ad hoc rescue parties soon began to operate, but roughly half of the city's population was dead or injured. In those areas most seriously affected virtuallyHiroshima mushroom cloud (picture taken from the ground) no one escaped serious injury. The numerous small fires that erupted simultaneously all around the city soon merged into one large firestorm, creating extremely strong winds that blew towards the center of the fire. The firestorm eventually engulfed 4.4 square miles of the city, killing anyone who had not escaped in the first minutes after the attack. One postwar study of the victims of Hiroshima found that less than 4.5 percent of survivors suffered leg fractures. Such injuries were not uncommon; it was just that most who could not walk were engulfed by the firestorm.

Even after the flames had subsided, relief from the outside was slow in coming. For hours after the attack the Japanese government did not even know for sure what had happened. Radio and telegraph communications with Hiroshima had"A-bomb Dome" amidst ruins of Hiroshima (the dome is now a World Heritage Site).suddenly ended at 8:16 a.m., and vague reports of some sort of large explosion had begun to filter in, but the Japanese high command knew that no large-scale air raid had taken place over the city and that there were no large stores of explosives there. Eventually a Japanese staff officer was dispatched by plane to survey the city from overhead, and while he was still nearly 100 miles away from the city he began to report on a huge cloud of smoke that hung over it. The first confirmation of exactly what had happened came only sixteen hours later with the announcement of the bombing by theCasualties in a makeshift hospital, Hiroshima United States. Relief workers from outside the city eventually began to arrive and the situation stabilized somewhat. Power in undamaged areas of the city was even restored on August 7th, with limited rail service resuming the following day. Several days after the blast, however, medical staff began to recognize the first symptoms of radiation sickness among the survivors. Soon the death rate actually began to climb again as patients who had appeared to be recovering began suffering from this strange new illness. Deaths from radiation sickness did not peak until three to four weeks after the attacks and did not taper off until seven to eight weeks after the attack. Long-range health dangers associated with radiation exposure, such as an increased danger of cancer, would linger for the rest of the victims' lives, as would the psychological effectsof the attack.

A soldier walks through a leveled portion of Hiroshima.No one will ever know for certain how many died as a result of the attack on Hiroshima. Some 70,000 people probably died as a result of initial blast, heat, andradiation effects. This included about twenty American airmen being held as prisoners in the city. By the end of 1945, because of the lingering effects of radioactive fallout and other after effects, the Hiroshima death toll was probably over 100,000. The five-year death total may have reached or even exceeded 200,000, as cancer and other long-term effects took hold.

At 11:00 a.m., August 6 (Washington D.C. time), radio stations began playing a prepared statement from President Truman (right) informing thePresident Harry S. Truman, November 1945 American public that the United States had dropped an entirely new type of bomb on the Japanese city of Hiroshima -- an "atomic bomb." Truman warned that if Japan still refused to surrender unconditionally, as demanded by the Potsdam Declaration of July 26, the United States would attack additional targets with equally devastating results. Two days later, on August 8, the Soviet Union declared war on Japan and attacked Japanese forces in Manchuria, ending American hopes that the war would end before Russian entry into the Pacific theater. By August 9th, American aircraft were showering leaflets all over Japan informing its people that "We are in possession of the most destructive explosive ever devised by man. A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2,000 of our giant B-29s can carry on a single mission. This awful fact is one for you to ponder and we solemnly assureFat Man at Tinian Island, August 1945 you it is grimly accurate. We have just begun to to use this weapon against your homeland. If you still have any doubt, make inquiry as to what happened to Hiroshima when just one atomic bomb fell on that city." Meanwhile, Tibbets's bomber group was simply waiting for the weather to clear in order to drop its next bomb, the plutonium weapon nicknamed "Fat Man" (right) that was destined for the city of Nagasaki.


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