What Happened During 1986 Chernobyl Nuclear Accident That Still Resonates As Ultimate Horror

Everyone is talking about mini-series ¡®Chernobyl¡¯ these days. The HBO programme is based on the nuclear accident in Ukraine that was nothing short of a disaster. The follow up exercise was even worse as the world witnessed one of the biggest man made tragedies of that time.

HBO

Here is all you should know about the catastrophe which left long term health impact on the people living in vicinity of the disaster site.

Where is Chernobyl?

Chernobyl is located 81 miles in north of the Ukrainian capital Kiev and it¡¯s just 12 kms from the border with Belarus.

At the time of disaster in 1986, it was the part of the erstwhile USSR. In 1970s and 1980s, the USSR built four reactors at the Chernobyl Nuclear Power Plant and a reservoir which was roughly 22 sq km in size was also built to provide the cooling water to the reactor.

The river Pripyat was the source of water in the reservoir.

A devastated kindergarten on 25th anniversary of Chernobyl disaster in 2011 in the ghost city of Pripyat, AFP

The then newly built city of Pripyat was the nearest town to the power plant and if the estimates of the World Nuclear Association are to be believes, it had a population of almost 50,000 people and the smaller town Chernobyl had about 12,000 people living in it.

What actually happened?

The disaster took place on April 26, 1986, but the immediate cause of the accident is attributed to April 25, when one-time shutdown was planned by plant operators in perform the routine maintenance of reactor number 4.

According to the UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), the safety regulations were violated when the plant equipment which also included the automatic shutdown mechanism were disabled for the operators.

As a result, on April 26, at 1.23 am, an immense amount of steam was created post the extremely hot nuclear rods were put into the cooling water which propagated more reactivity in the core of the reactor number 4. This is said to have happened because of the design flaws in RBMK reactors.

A gas mask and children toy in the kindergarten, AFP

Since the automatic shutdown mechanism was already disabled, the massive power surge in the reactor cause an explosion and the 1000 ton plate which covered the reactor core was detached realising radiation into the atmosphere. The explosion and detachment of the plate also cut off the flow of coolant into the reactor.

Seconds later, another explosion which had a greater intensity than the first one took place and the reactor building was blown apart leaving burning graphite and other parts of the reactor core spewed in and around the plant.

The explosion started fires around the explosion which damaged the functioning reactor number 3.

The flaw in the Reactors

The main cause of the disaster was said to be the flawed design of the reactors. The plant used RBMK-1000 nuclear reactors designed in Soviet Union. In RBMK reactors, the enriched U-235 uranium was used as a fuel to heat water creating steam that drove the reactor turbine resulting in the electricity generation.

In most reactors used globally, the water is used as a coolant which moderates the reaction in the core of the plant. As the core heats and more steam is created, the steam bubbles also called voids in the water help in reducing the reaction in the core. But RBMK-100 didn¡¯t work on this concept and instead it used graphite to moderate the reactivity inside the core apart from keeping a continuous nuclear reaction on inside the core.

With nuclear core heating and producing more steam bubbles, the core gets more reactive instead of cooling down creating what engineers refer it as a "positive-void coefficient¡±.

Explosion and the leak

The crippled Chernobyl plant after three days of the explosion in April 1986, AP

The explosion killed several workers and the two workers died within hours of the accident. Attempts were made to contain fires and radiation leaks as the death toll kept climbing. According to the U.S. Nuclear Regulatory Commission (NRC), a total of 28 workers died in four months after the accident. Some of them kept attempting to secure the facility from further radiation leak despite knowing that they were exposing themselves to the radiation in process of containing the leak.

Evacuations and impact of people¡¯s health

The resident of Pripyat were evacuated on April 27 after 36 hours of the accident and by then many had complained of vomiting, headache and other symptoms of the radiation sickness. The 30 km area around the plant closed off. Since the winds flow pattern took the radiation towards Belarus and the authorities of the Soviet Union were reportedly slow in releasing information about the magnitude of the radiation leak to the world and it took the radiation arms in a nuclear plant in Sweden to go off to compel the authorities to disclose the extent of the crisis.

The helicopter sprays in order to decontaminate the area near the Chernobyl plant in June 1986, Reuters.

It was, however, unclear that how many cases of cancer surfaced where the Chernobyl accident was directly responsible, but more than 6,000 cases of thyroid cancer were linked to radiation in Ukraine and neighbouring Russia and Belarus.

Surprisingly, the number of deaths and other ailment feared due to the leak were lower than feared and per the NRC report, "The majority of the five million residents living in contaminated areas ¡­ received very small radiation doses comparable to natural background levels (0.1 rem per year)," according to an NRC report. "Today the available evidence does not strongly connect the accident to radiation-induced increases of leukemia or solid cancer, other than thyroid cancer." The NRC report was quoted by www.livescience.com report.

Chernobyl, not safe, neither today, nor tomorrow

Soon after the accident, the radiation killed the tree surrounding the plant and the region got name ¡°Red Forest¡± as the trees that died due to the radiation turned a bright ginger colour, which was later bulldozed and buried later.

A man found the house he had abandoned due to radiation leak in 1986 in ruins when he returned to his village Lomysh in Belarus in 2011, Reuters

Today, Chernobyl has home to most unique wildlife sanctuaries housing a variety of animals and birds such as boar, elk, bears, beaver, deer, lynx, eagles, wolves and others in the thick forest that now surrounds the plant.

The area, however, sees the stunted trees growing in the zone and animals in the area have high levels of cesium-137 in their bodies and what's more depressing is that despite having variety of animals in the region, for 20,000 years, this area will remain unsafe for human habitation.