The citizens of Pripyat and the members of the emergency services who were the first to arrive to the central to try to avoid more tragic consequences were the most affected. The most part of them died or suffered (and suffer) the sequels of this terrible accident.
The Grandma wants to talk about this incident, and she wants to think about the real necessity of having nuclear plants when we are a planet rich in natural sources and green energies.
The Chernobyl disaster was a nuclear accident that occurred on Saturday 26 April 1986, at the No. 4 reactor in the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR in the Soviet Union.
It is considered the worst nuclear disaster in history both in terms of cost and casualties, and is one of only two nuclear energy accidents rated at seven -the maximum severity- on the International Nuclear Event Scale, the other being the 2011 Fukushima Daiichi nuclear disaster in Japan.
The initial emergency response, together with later decontamination of the environment, ultimately involved more than 500,000 personnel and cost an estimated 18 billion Soviet rubles -roughly US$68 billion in 2019, adjusted for inflation.
The accident started during a safety
test on an RBMK-type nuclear reactor. The test was a simulation of an
electrical power outage to help create a safety procedure for
maintaining reactor cooling water circulation until the back-up
electrical generators could provide power. Three such tests had been
conducted since 1982, but they had failed to provide a solution. On this
fourth attempt, an unexpected 10-hour delay meant that an unprepared
operating shift was on duty.
More information: Chornobyl NPP
During the planned decrease of reactor power in preparation for the electrical test, the power unexpectedly dropped to a near-zero level.
The operators were able to only partially restore the specified test power, which put the reactor in an unstable condition. This risk was not made evident in the operating instructions, so the operators proceeded with the electrical test. Upon test completion, the operators triggered a reactor shutdown, but a combination of unstable conditions and reactor design flaws caused an uncontrolled nuclear chain reaction instead.
A large amount of energy was suddenly released, and two explosions ruptured the reactor core and destroyed the reactor building.
One was a highly destructive steam explosion from the vaporizing superheated cooling water; the other explosion could have been another steam explosion or a small nuclear explosion, akin to a nuclear fizzle. This was immediately followed by an open-air reactor core fire that released considerable airborne radioactive contamination for about nine days that precipitated onto parts of the USSR and Western Europe, especially Belarus, 16 km away, where around 70% landed, before being finally contained on 4 May 1986.
The fire gradually released about the same amount of contamination as the initial explosion. As a result of rising ambient radiation levels off-site, a 10-kilometre radius exclusion zone was created 36 hours after the accident. About 49,000 people were evacuated from the area, primarily from Pripyat. The exclusion zone was later increased to 30 kilometres when a further 68,000 people were evacuated from the wider area.
More information: World Nuclear Association
The reactor explosion killed two of the reactor operating staff. A massive emergency operation to put out the fire, stabilize the reactor, and clean-up the ejected nuclear core began. In the disaster and immediate response, 134 station staff and firemen were hospitalized with acute radiation syndrome due to absorbing high doses of ionizing radiation. Of these 134 people, 28 died in the days of months afterward and approximately 14 suspected radiation-induced cancer deaths followed within the next 10 years. Significant clean-up operations were taken in the exclusion zone to deal with local fallout, and the exclusion zone was made permanent.
Among the wider population, an excess of 15 childhood thyroid cancer deaths were documented as of 2011. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has, at multiple times, reviewed all the published research on the incident and found that at present, fewer than 100 documented deaths are likely to be attributable to increased exposure to radiation.
Determining the total eventual number of exposure related deaths is uncertain based on the linear no-threshold model, a contested statistical model, which has also been used in estimates of low level radon and air pollution exposure. Model predictions with the greatest confidence values of the eventual total death toll in the decades ahead from Chernobyl releases vary, from 4,000 fatalities when solely assessing the three most contaminated former Soviet states, to about 9,000 to 16,000 fatalities when assessing the total continent of Europe.
To reduce the spread of radioactive contamination from the wreckage and protect it from weathering, the protective Chernobyl Nuclear Power Plant sarcophagus was built by December 1986.
It also provided radiological protection for the crews of the undamaged reactors at the site, which continued operating.
Due to the continued deterioration of the sarcophagus, it was further enclosed in 2017 by the Chernobyl New Safe Confinement, a larger enclosure that allows the removal of both the sarcophagus and the reactor debris, while containing the radioactive hazard. Nuclear clean-up is scheduled for completion in 2065.
The ionizing radiation levels in the worst-hit areas of the reactor building have been estimated to be 5.6 roentgens per second (R/s), equivalent to more than 20,000 roentgens per hour. A lethal dose is around 500 roentgens (~5 Gray (Gy) in modern radiation units) over five hours, so in some areas, unprotected workers received fatal doses in less than a minute. However, a dosimeter capable of measuring up to 1,000 R/s was buried in the rubble of a collapsed part of the building, and another one failed when turned on. All remaining dosimeters had limits of 0.001 R/s and therefore read off scale. Thus, the reactor crew could ascertain only that the radiation levels were somewhere above 0.001 R/s, while the true levels were much higher in some areas.
Because of the inaccurate low
readings, the reactor crew chief Aleksandr Akimov assumed that the
reactor was intact. The evidence of pieces of graphite and reactor fuel
lying around the building was ignored, and the readings of another
dosimeter brought in by 04:30 were dismissed under the assumption that
the new dosimeter must have been defective. Akimov stayed with his crew
in the reactor building until morning, sending members of his crew to
try to pump water into the reactor. None of them wore any protective
gear. Most, including Akimov, died from radiation exposure within three
weeks.
More information: BBC
The nearby city of Pripyat was not immediately evacuated. The townspeople, in the early hours of the morning, at 01:23 local time, went about their usual business, completely oblivious to what had just happened. However, within a few hours of the explosion, dozens of people fell ill. Later, they reported severe headaches and metallic tastes in their mouths, along with uncontrollable fits of coughing and vomiting. As the plant was run by authorities in Moscow, the government of Ukraine did not receive prompt information on the accident.
To expedite the evacuation, residents were told to bring only what was necessary, and that they would remain evacuated for approximately three days. As a result, most personal belongings were left behind, and remain there today.
By 15:00, 53,000 people were evacuated to various villages of the Kiev region. The next day, talks began for evacuating people from the 10-kilometre zone. Ten days after the accident, the evacuation area was expanded to 30 kilometres.
The Chernobyl Nuclear Power Plant Exclusion Zone has remained ever since, although its shape has changed and its size has been expanded.
More information: United States Nuclear Regulatory Commission
The surveying and detection of isolated fallout hotspots outside this zone over the following year eventually resulted in 135,000 long-term evacuees in total agreeing to be moved.
The years between 1986 and 2000 saw the near tripling in the total number of permanently resettled persons from the most severely contaminated areas to approximately 350,000.
Contamination from the Chernobyl accident was scattered irregularly depending on weather conditions, much of it deposited on mountainous regions such as the Alps, the Welsh mountains and the Scottish Highlands, where adiabatic cooling caused radioactive rainfall.
The resulting patches of contamination were often highly localized, and localized water-flows contributed to large variations in radioactivity over small areas.
Sweden and Norway also received heavy fallout when the contaminated air collided with a cold front, bringing rain. There was also groundwater contamination.
More information: National Geographic
where nature revives after a world-wide man-made disaster,
where there is a real 'ghost town.'
Volodymyr Zelensky
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