Chernobyl Disaster : research
The Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR, it situated in the Ivankiv Raion of northern Kiev Oblast, Ukraine. Chernobyl is about 90 km north of Kiev, and 160 km southwest of the Belarusian city of Gomel.
From many articles about Chernobyl disaster that I have read, I can summarise that it began with the safety test in the reactor unit 4. The Chernobyl power plant need to use electricity for the coolant pump to use for the emergency core cooling system which the Chernobyl had been in operation for two years without this capability to ride through the first 60–75 seconds of a total loss of electric power, identify as potential safety problem. So, this test is basically about trying to use power from the turbine, the power that the reactor create itself, during that 1 minute gap, could the turbine spin and supply enough power to maintain reactor’s cooling water. This test have done before for 3 times and this is the 4th attempt The test was planned to do in the day shift but there was an unexpected 10 hour delay so that unprepared operating shift have to do this test, could be said as inadequately trained person. This fourth attempts only have an authority from the owner of reactor since it was considered to concern on the non-nuclear part of the power plant so it was carried without a proper exchange information with the team in charge of the test and the person in charge of the operation and safety of the nuclear reactor
Operators ran the plant at very low power, due to the improper communication with safety personnel in which the design of this reactor (RMBK) was highly unstable at low power. The reactor had a dangerously large positive void coefficient, the increase in steam void lead to the increase in power output.
Due to the 10 hrs delayed, the reactor have been hold at the half power for 10 hours before resume the test. This produce the xenon that poisoning the core. it makes the core didn’t have enough power so, they increase the power of the core. The operator didn’t notice the problem, after they increase the power to the point where they want, they shut down the cooling water to start the test but At that point the only thing that keep the reactor stable is cooling water. Which there is nothing to control the power of the core, there is the swing reaction, the core was over heat, it create a massive steam voids from the cooling water that left.
Together with that the operator shut off the steam to the turbine in order to test only the turbine, it increase the formation of steam void in the core and it reduce ability of the liquid water coolant to absorb neutrons, which in turn increased the reactor’s power output, giving yet a further power increase, and increase in fuel temperature. The increase in temperature was affected by the design of the reactor, massive steam build up and it lead to a rapid increase in steam pressure. The operator might see that the core power dangerously increase to the very high number so, they press rapid emergency shut down button, which its process in turn accelerate the reaction instead. The steam pressure in side the core was no longer be held back so it exploded (the 1st explosion) and it blow out the 1,000T cover plate. It allows oxygen to come into the reactor which cause the fire and threw out a lot of fragments from the fuel channel and hot graphite (the2nd explosion) 2–3 seconds after the first explosion, it exposing the reactor core to the environment. This Chernobyl disaster was the product of unstable condition, inadequately trained person, and flawed Soviet reactor design, it cause an uncontrolled power surge.
On the other hand, the reactor unit3 which is close the unit4 and still operating was getting at least 5 fires on the roof which they have to put those fires out and protect the cooling systems of reactor unit3. The chief of the night shift, Yuri Bagdasarov, wanted to shut down the reactor immediately, but chief engineer Nikolai Fomin not allow. The operators were given respirators and potassium iodide tablets and told to continue working. Until 5 Am that Yuri made his own decision to shut down the reactor, leaving only those operators there who had to work the emergency cooling systems.
The nearby city of Pripyat was not immediately evacuated. The townspeople, in the early hours of the morning, 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. Ukraine’s acting Minister of Internal Affairs Vasyl Durdynets phoned to the Chairwoman of the Presidium of Verkhovna Rada Supreme Soviet of the Ukrainian SSR to report current affairs; only at the end of the conversation that he add that there had been a fire at the Chernobyl nuclear power plant, but it was extinguished and everything was fine and there was nothing to be concerned about the people. But after they fly to the power plant in evening 26 Apr, they saw that the reactor was destroyed and extremely high levels of radiation had caused a number of cases of radiation exposure and In the early daylight hours of 27 April, approximately 36 hours after the initial blast, they ordered the evacuation the population for three days which later made it permanent
The initial evidence that a major release of radioactive material was affecting other countries came not from Soviet sources, but from Sweden. Sweden reported unusually high levels of radioactivity. In the morning of 28 April, radiation levels set off alarms at the Forsmark Nuclear Power Plant in Sweden, workers at the Forsmark Nuclear Power Plant (approximately 1,100 km from the Chernobyl site) were found to have radioactive particles on their clothes so they search for the source of radioactivity, after they had determined there was no leak at the Swedish plant. the Swedish government contacted the Soviet government to inquire about whether there had been a nuclear accident in the Soviet Union. The Soviets initially denied it but after the Swedish government suggested they were about to file an official alert, the Soviet government admitted an accident took place at Chernobyl. At first, the Soviets only conceded that a minor accident had occurred, but once they began evacuating more than 100,000 people, the full scale of the situation was realized by the global community. At the evening of 28 April, a 20-second announcement was read in the TV news programme