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8/3/2019 Chernobyl Disaster (2)

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CHERNOBYL DISASTER

Lika arobelidzeAni gogitidzeMari cqitishviliAchiko jincharadzeNika tabaguairakli bejanidzeGiorgi gogelia


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About the disaster

the Chernobyl disaster occurred on 26 April 1986 at the

Chernobyl nuclear power plant in Pripyat, Ukraine. At that

time, TUkraine was part of the Soviet Union.

The event was the worst accident in the history of nuclearpower. Because there was no containment building to trap the

radiation, radioactive fallout drifted over parts of the western

Soviet Union, Eastern Europe, Scandinavia, the UK, and the

eastern United States. Large areas of Ukraine, Belarus, and

Russia were badly contaminated. About 60% of the radioactivefallout landed in Belarus. About 350,000 people needed to be

evacuated and moved to other places where they could live

after the accident.


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The accident raised concerns about the safety of the Soviet nuclear power industry. Itslowed its expansion for some time. It also forced the Soviet government to becomeless secretive. Since then, Russia, Ukraine and Belarus became separate countries.Those countries have been burdened with continuing costs for decontamination andhealth care because of the accident. Exposure to radiation leads to a higher risk ofgetting cancer. It is difficult to accurately tell the number of deaths caused by the

events at Chernobyl.The Chernobyl accident happened when some workers wheretesting the safety of the reactor. Some of the devices that stopped the reactor fromblowing up were switched off.Then, there was a power surge; they lost control andthe reactor blew up.

Most of the people affected have not died yet. When and if the people involved die ofcancer, or related diseases, it will be hard to tell if this was because of the accident. A2005 IAEA report tells of 56 direct deaths, 47 of those were accident workers and 9were children who died of thyroid cancer.The report estimates that up to 4,000people may die from long term diseases related to the accident. Greenpeace, alongwith others, thinks that the study's conclusions may be false.


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causes

There were two official explanations of theaccident: the first, later acknowledged to beerroneous, was published in August 1986 and

effectively placed the blame on the power plantoperators.To investigate the causes of theaccident the IAEA created a group known as theInternational Nuclear Safety Advisory Group ,which in its report of 1986, INSAG-1, on the

whole also supported this view, based on thedata provided by the Soviets and the oralstatements of specialists.In this view, thecatastrophic accident was caused by grossviolations of operating rules and regulations


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"During preparation and testing of the turbine generator under run-down conditions using the auxiliary load, personnel disconnected aseries of technical protection systems and breached the mostimportant operational safety provisions for conducting a technicalexercise.":311The operator error was probably due to their lack ofknowledge of nuclear reactor physics and engineering, as well aslack of experience and training. According to these allegations, atthe time of the accident the reactor was being operated with manykey safety systems turned off, most notably the Emergency Core

Cooling System LAR and AZ Personnel had an insufficiently detailedunderstanding of technical procedures involved with the nuclearreactor, and knowingly ignored regulations to speed testcompletion.


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Chernobyl after disaster

Following the accident, questions arose about the future of the plant and itseventual fate. All work on the unfinished reactors 5 and 6 was halted threeyears later. However, the trouble at the Chernobyl plant did not end with thedisaster in reactor 4.The damaged reactor was sealed off and 200 cubicmeters of concrete was placed between the disaster site and the

operational buildings.T

he Ukrainian government continued to let the threeremaining reactors operate because of an energy shortage in the country.

In 1991, a fire broke out in the turbine building of reactor 2; the authoritiessubsequently declared the reactor damaged beyond repair and had it takenoffline. Reactor 1 was decommissioned in November 1996 as part of a dealbetween the Ukrainian government and international organizations such as

the IAEA to end operations at the plant. On 15 December 2000, then-President Leonid Kuchma personally turned off Reactor 3 in an officialceremony, shutting down the entire site.

In 2011, Ukraine plans to open up the sealed zone around the Chernobylreactor to tourists who wish to learn more about the tragedy that occurredin 1986.


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Japan disaster

Radioactive cesium above government safetylimits has been detected in rice outside theexclusion zone around the Fukushima nuclearplant, in a district about 60 kilometres west ofFukushima City, Japan, reports say. Japanesebroadcaster NHK reported on Nov. 17 thatFukushima prefecture has asked all 154farmers in the district to suspend riceshipments.


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Radioactive particles associated with nuclear fission have beendetected at Japan's tsunami-damaged atomic power plant, officialssaid Nov. 2, suggesting one of the reactors could have a newproblem. Gas from inside the Fukushima plant's No. 2 reactorindicated the presence of radioactive xenon, which could be the

byproduct of unexpected nuclear fission. Boric acid was injectedthrough a cooling pipe as a precaution because it can counteractnuclear reactions.

Tokyo Electric Power Co. said there was no rise in the reactor'stemperature or pressure.The company said the radioactive

materials had not reached the point when nuclear reactions are self-sustaining and the detection of the xenon would have no majorimpact on workers' efforts to keep the reactor cool and stable.


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On May 26, people from the region around

the nuclear plant who have been kept from

their homes since March 11 were given twohours to return to their dwellings and collect

some of their belongings.They are still not

allowed to return home permanently due to

fears of radioactive contamination.


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A senior nuclear adviser to Japanese Prime Minister Naoto Kan resignedApril 30, criticizing the government for ignoring his advice on radiation limitsand not doing enough to deal with the crisis at the plant.Toshiso Kosakosaid the government's 20-millisievert limit for radiation exposure is too high,especially for children. In a statement, Kan's administration called the

resignation"

unfortunate"

and said the government has always followed theadvice of the country's nuclear safety commission.

TheTokyo Electric Power Company, the utility that runs the nuclear plant,has offered 20 million yen (about $228 million) in "apology money" to everytown and city in the 20 kilometre mandatory evacuation zone around theplant. Japan's nuclear safety agency has said it could take months to bringthe situation at Fukushima under control.

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