The Chernobyl nuclear disaster of 1986 is by far the worst nuclear accident in the history of mankind. It was classified as level 7 (severe nuclear accident) of the INES scale, the highest value. Although it is the same level at which the Fukushima nuclear accident was classified, the consequences of the Chernobyl accident were still much worse. (What’s even worse is getting an F on your dissertation. Get amazing dissertation writing service.)
The Chernobyl nuclear power plant is located next to the town of Prypyat, 18km from the city of Chernobyl. At the time of the accident the Chernobyl nuclear power station had 4 reactors in operation and two more were under construction. On September 9, 1982, a partial melting of the base occurred in reactor No. 1 of the plant. Although due to the secrecy of the Soviet Union, the international community was not informed until 1985. It was repaired and continued to function.
The serious accident occurred in 1986, when the number 4 reactor exploded. Subsequently, despite the severity of the accident and due to the energy needs, reactors 1, 2 and 3 continued. The nuclear reactor 2 of Chernobyl was closed in 1991, the reactor 1 in 1996 and finally the number 3 reactor in 2000.
The Incident.
The Chernobyl nuclear accident (Ukraine) occurred during the night of 25 to 26 April 1986 in the fourth reactor of the nuclear plant. It was a nuclear reactor that belonged to the type that the Soviets call RMBK-1000, cooled by water and moderated by graphite. At one o'clock in the morning of April 25, engineers started the entry of control rods into the core of the nuclear reactor in order to reduce their power. By 23 hours the monitors had been set to the lowest power levels. But the operator forgot to reprogram the computer to maintain power between 700 MW and 1,000 thermal MW. For this reason, the power dropped to the level of 30 MW.
At such a low level, the automatic systems could stop the reactor due to its dangerousness, and for this reason, the operators disconnected the system of regulation of the power, the emergency system of cooling of the nucleus and other systems of protection when the system already was at the point of turning off the nuclear reactor.
Realizing that the control rods were removed in order to avoid increasing the power of the nuclear
reactor, operators manually removed too many control rods. The reactor core had 170 control rods. The safety rules demanded that there was always a minimum of 30 bars down and this time they left only 8.
Since the plant's safety systems were rendered inoperable and almost all control rods had been
removed, the plant reactor was in unstable and extremely unsafe operating condition. At that time, a
sudden increase of power took place that the operators did not detect in time. When they wanted to
lower the control rods again using the emergency SCRAM button, they did not respond because they
were possibly already deformed by the heat and disconnected to allow them to fall by gravity.
Finally, the nuclear fuel disintegrated and left the pods, coming into contact with the water used to cool the reactor core. At one and 23 minutes, a big explosion occurred, and a few seconds later, a second
explosion blew up the reactor slab and the concrete walls of the reactor room, throwing fragments of
graphite and nuclear fuel outside of the plant, with high radiation entering the atmosphere.
It is estimated that the amount of radioactive material released was 200 times higher than the atomic
bombs dropped on Hiroshima and Nagasaki at the end of World War II. The nuclear accident was
classified as Level 7 ("serious nuclear accident") on the International Nuclear Event Scale (INES scale) of the International Atomic Energy Agency (IAEA). This is, by far, the worst environmental disaster.
