This Week in History: Chernobyl Nuclear Power Plant Explosion


The disaster at Chernobyl (Ukrainian spelling: Chornobyl) on April 26, 1986 occurred as a result of an experiment on how long safety equipment would function during shutdown at the fourth reactor unit at Ukraine’s first and largest nuclear power station. The operators had dismantled safety mechanisms at the reactor to prevent its automatic shutdown, but this reactor type (a graphitemoderated Soviet RBMK) became unstable if operated at low power. An operator error caused a power surge that blew the roof off the reactor unit, releasing the contents of the reactor into the atmosphere for a period of about twelve days.

The accident contaminated an area of about 100,000 square miles. This area encompassed about 20 percent of the territory of Belarus; about 8 percent of Ukraine; and about 0.5-1.0 percent of the Russian Federation. Altogether the area is approximately the size of the state of Kentucky or of Scotland and Northern Ireland combined. The most serious radioactive elements to be disseminated by the accident were Iodine-131, Cesium-137, and Strontium-90. The authorities contained the graphite fire with sand and boron, and coal miners constructed a shelf underneath it to prevent it from falling into the water table.

After the accident, about 135,000 people were evacuated from settlements around the reactor, including the town of Pripyat (population 45,000), the home of the plant workers and their families, and the town of Chernobyl (population 10,000), though the latter remained the center of the cleanup operations for several years. The initial evacuation zone was a 30-kilometer (about 18.6 miles) radius around the destroyed reactor unit. After the spring of 1989 the authorities published maps to show that radioactive fallout had been much more extensive, and approximately 250,000 people subsequently moved to new homes.

Though the Soviet authorities did not release accurate information about the accident, and classified the health data, under international pressure they sent a team of experts to a meeting of the IAEA (The International Atomic Energy Agency) in August 1986, which revealed some of the causes of the accident. The IAEA in turn was allowed to play a key role in improving the safety of Soviet RBMK reactors, though it did not demand the closure of the plant until 1994. A trial of Chernobyl managers took place in 1987, and the plant director and chief engineer received sentences of hard labor, ten and five years respectively.

Chernobyl remains shrouded in controversy as to its immediate and long-term effects. The initial explosion and graphite fire killed thirty-one operators, firemen, and first-aid workers and saw several thousand hospitalized. Over the summer of 1986 up until 1990, it also caused high casualties among cleanup workers. According to statistics from the Ukrainian government, more than 12,000 “liquidators” died, the majority of which were young men between the ages of twenty and forty. A figure of 125,000 deaths issued by the Ukrainian ministry of health in 1996 appears to include all subsequent deaths, natural or otherwise, of those living in the contaminated zone of Ukraine.

According to specialists from the WHO (World Health Organization) the most discernible health impact of the high levels of radiation in the affected territories has been the dramatic rise in thyroid gland cancer among children. In Belarus, for example, a 1994 study noted that congenital defects in the areas with a cesium content of the soil of one–five curies per square kilometer have doubled since 1986, while in areas with more than fifteen curies, the rise has been more than eight times the norm.

Among liquidators and especially among evacuees, studies have demonstrated a discernible and alarming rise in morbidity since Chernobyl when compared to the general population. This applies particularly to circulatory and digestive diseases, and to respiratory problems. Less certain is the concept referred to as “Chernobyl AIDS,” the rise of which may reflect more attention to medical problems, better access to health care, or psychological fears and tension among the population living in contaminated zones. Rises in children’s diabetes and anemia are evident, and again appear much higher in irradiated zones. The connection between these problems and the rise in radiation content of the soil have yet to be determined.

To date, the rates of leukemia and lymphoma— though they have risen since the accident—remain within the European average, though in the upper seventy-fifth percentile. One difficulty here is the unreliability or sheer lack of reporting in the 1970s. The induction period for leukemia is four to fifteen years, thus it appears premature to state, as some authorities have, that Chernobyl will not result in higher rates of leukemia.

As for thyroid cancer, its development has been sudden and rapid. As of 2003 about 2,000 children in Belarus and Ukraine have contracted the disease and it is expected to reach its peak in 2005. One WHO specialist has estimated that the illness may affect one child in ten living in the irradiated zones in the summer of 1986; hence ultimate totals could reach as high as 10,000. Though the mortality rate from this form of cancer among children is only about 10 percent, this still indicates an additional 1,000 deaths in the future. Moreover, this form of cancer is highly aggressive and can spread rapidly if not operated on. The correlation between thyroid gland cancer and radioactive fallout appears clear and is not negated by any medical authorities.

After pressure from the countries of the G7, Ukraine first imposed a moratorium on any new nuclear reactors (lifted in 1995) and then closed down the Chernobyl station at the end of the year 2000. The key issue at Chernobyl remains the construction and funding of a new roof over the destroyed reactor, the so-called sarcophagus. The current structure, which contains some twenty tons of radioactive fuel and dust, is cracking and is not expected to last more than ten years. There are fears of the release of radioactive dust within the confines of the station and beyond should the structure collapse.

It is fair to say that the dangers presented by former Soviet nuclear power stations in 2003 exceed those of a decade earlier. In the meantime, some 3.5 million people continue to live in contaminated zones. From a necessary panacea, evacuation of those living in zones with high soil contamination today has become an unpopular and slow-moving process. Elderly people in particular have returned to their homes in some areas.

Source citation:  MARPLES, DAVID R. “Chernobyl.” Encyclopedia of Russian History. Ed. James R. Millar. Vol. 1. New York: Macmillan Reference USA, 2004. 238-240. World History in Context. Web. 22 Apr. 2016.

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