The Class Name
The 26th of April this year will be marked as the twenty-eighth anniversary of a disaster of a worldwide scale. So much time has passed after it and we still remember that fear of a nightmare of such a nuclear disaster that has changed millions of lives during a couple of days and it changed the nature itself, as well. The topic of our research is the Chernobyl Catastrophe (or “Chernobylska Katastropha” in Ukrainian); we`re going to describe its causes and consequences, the governmental meanings about it and how it changed the territory of Ukraine and the countries it affected.
Let us also describe the purpose and the procedure of the experiment, which was the key of the system tests during 26 April. It was an experiment of improvement of emergency core cooling mechanisms as a nuclear reactor was still generating an amount of vestigial decay heat when it was inactive. The amount of 7% of decay heat is a significant one and hides potential danger when it`s not properly cooled. Chernobyl station used RBMK reactors that use water coolers. Chernobyl`s Reactor 4 composed of approximately 1,600 separate fuel channels and every one of them needed a flow of coolant of approximately 28,000 liters per hour. As the cooling pomps demanded enough electricity to cool a reactor after an emergency shutdown, the reactors had 3 reserve diesel generators that could start up in the next 15 seconds; however, it took more than a minute for the mechanism to reach the full speed and the 5,5 MW (megawatt) output in order to run the main pomp. In order to resolve this gap of one minute, there had appeared a theory that rotational energy generated by the steam turbine could possibly be applied for the creation of the additional electrical force, as the analysis confirmed that this pressure of steam would be enough to accelerate the coolant pomp for 45 seconds somehow closing the gap mentioned above.
Although, it had to be practically and experimentally verified and confirmed, the interesting fact here is that the previous attempt to do so have ended a failure. The year of 1982 was the date of the first test on that purpose. It resulted in the insufficiency of exhilaration amount of the turbine generator and it obviously didn`t support the expected magnetic field after the trip of the turbine. In 1984, the systems were upgraded and the experiment was launched again and reached the same unsatisfactory results. The third attempt to confirm the theorized data was in the 1985, but failed to achieve positive results for the third time. At last, the experiment of 26 April 1986 was the fourth attempt of the experiment, it was expected to take place on the 4th Reactor during its shutdown; the results of it didn`t only confirmed the theory of cooling improvement, but also caused the much worse consequences.
The experiment itself aimed at switching the consistencies of the electrical sources for the reactor and was scheduled to launch with an automatic emergency shutdown. As there were not detected any harmful effects on the reactor`s safety, the experiment itself wasn`t officially coordinated the main engineer and/or the reactor`s main designer. It was confirmed only by the plant`s director; however, it was also contradicting the norms and rules of running such experiments. The reactor`s thermal output expected to be no lower than 700 megawatts by the beginning of the experiment according to the test calculations. If the conditions of the experiment had been predicted, the whole test would have been operated with the maximum probability of a safe outcome, as the catastrophe itself was the result of the reactor`s boost at the beginning of the experiment, which was unacceptable according to the approved technology of the test.
The Chernobyl nuclear plant had been operating for approximately two years with no ability to overcome the first minute of a complete electricity loss and lacked such an inevitable improvement. The rulers of the plant wanted to fix that as fast as they can, as this may be the best explanation why everything was running so fast and why there were so much ignorance of rules and the technical procedures. "The mere fact that the operators were carrying out an experiment that had not been approved by higher officials indicates that something was wrong with the chain of command. The State Committee on Safety in the Atomic Power Industry is permanently represented at the Chernobyl station. Yet the engineers and experts in that office were not informed about the program. In part, the tragedy was the product of administrative anarchy or the attempt to keep everything secret." says Medvedev in his research. The next paragraphs will be on the exact time how the experiment was taking place and the results of it. The beginning of the test was at 01:23:04 AM. Only four of the eight Main Circulating Pumps (MCP) were running despite the fact that six of them are required to run such tests. After that started the diesel generators that picked up the power loads after the MCP`s and they finished this by 01:23:43 AM. As the MCP`s started to decrease their energy outputs, so did the turbines that served them and the water flow for the cooling decreased and caused it to start boiling. The time of 01:23:40 was registered by the plant`s computer SKALA as the time of the emergency shutdown (EPS-5 button) of the reactor that launched the explosion in a nearest time later.
After the launch of the SCRAM (emergency shutdown system), it caused an enormous power surge, after that came overheat of the core, which caused the fracture of the fuel rods and the jamming of the control rods and the output of the reactor reached the mark of 530 megawatt. This order of events wasn`t recorded by instruments, but only were known as the results of mathematical modelling. Obviously, the power surge caused the temperature to increase and the steam pressure increased, as well. It caused the fuel cover to fall exposing them into the coolant; moreover, it broke the channels of locations of these elements.
After that, the reactor reached approximately of 30,000-megawatt thermal, as the last registered figure of that was 33,000 megawatts. This was followed by a steam explosion that blew off the upper plate of the reactor of approximately 2,000-ton weight. The explosion itself broke the fuel channels and spilled the rests of the coolant into the steam masses; in addition, with still boiling water masses all of these were increasing the temperature of the reactor. After that came the second explosion and it separated the broken core and ended the nuclear chain reaction. This resulted in the outside ignition of the graphite rods that were sent outside the reactor with the explosion. Moreover, the roof of the reactor was partially made of bitumen that is a combustible material and the fire reached the Reactor 3 that was still working. On the night shift of the reactor, the main engineer wanted shut it down immediately. He was forbidden to do so by his management; nevertheless, he did this at 05:00 and left only the emergency cooling system operators with him.
After the explosions, the firemen arrived to put out the fire around the reactor. Despite the fact that they were not informed about the real state of things about the plant, they expected to be radiated and were coming there not to follow the regulations and instructions, but for their duty as the firefighters. Still, the witnesses among the firefighters regarding the awareness on where they are coming are divided into two separate meanings, some of them didn`t know everything about the radiation and came here to extinguish some electric fire; however, there was the part of the firefighters that knew that their duty was suicidal that day.
The first priority was to put out the fires on the station`s roof and the area around the 4th Reactor in order to protect and keep the cooling systems of Reactor 3 functional. The fires across the territory were put out by the 6:00, but the price of this was the high amounts of radiation received by the firefighters. We should also mention that the fire inside the 4th reactor was burning till the 10 May 1986. The fire was also put out with the help of the helicopters using approximately 5,000 tons of lead, sand and boron to drop them on the burning reactor; the liquid nitrogen injection was also used. The fire and the explosion itself have thrown many particles of radionuclides, including strontium-90, iodine-131 and caesium-137; moreover, the participants of the disasters could view this radioactive cloud during the time of the explosion. The facilities including the remote robot-cars and bulldozers were also involved in the clean-up as they were supposed to detect the radioactive waste and utilize it; however, on the high radiation the electronic machines refused to work.
The Pripyat city wasn`t evacuated immediately after a disaster and the citizens were doing their casual stuff and they didn`t know anything about the incident. Although, an amount of people during the day fell sick, they reported the coughing and vomiting, a metallic taste in their mouths and severe headaches.The majority of the Soviet population was informed about the disaster a few days after the explosion and with a brief announcement on national TV. All the radio broadcasting were changed into the classical music, which has become a traditional method of announcing the horrifying news to the society. All the scientists were awaiting for the future instructions and updates regarding the situation. An investigating commission was sent on the place of the tragedy on 26 April: they had found two people already dead and 52 hospitalized. By the night between the 26 and 27 of April, the committee had registered evidences of deaths and high radiation diseases among the affected people and they have launched the evacuation of people from Pripyat. At the morning of 27 April, there were buses to pick up the people from the city and transfer them to the nearby cities and villages of the Kiev region. There was an announcement from Moscow that the officials had found no reason not to celebrate the 1 May and scientists were reporting the radiological background of Kiev as a normal. The Soviet officials tried their best to hide the consequences of the incident; however, the registered increase of the radiological front detected by Swedish nuclear power plant located over one thousand km from Pripyat, made the Soviet governors accept the fact of the disaster and started to take measures about its consequences.
INSAG reports that both staff and operating regulations disabled the protection of the reactor and they think that it was the crew of operators` fault in neglecting the test regulations and approved procedures. Moreover, the organization in its report paid enough attention to unacceptable safety measures at all levels of the plant. The engineering, design, manufacture, construction and many other processes confirmed the inadequate behavior to the safety measures and the exact details are mentioned above. The whole Soviet manner of running the nuclear plants was put to the severe critics from the organization.
We should also describe the state of the cities involved in the disaster. The city of Chernobyl is a city in Kiev region of Ukraine and it was formed, developed and took part in the general history of the whole country. There were some particular events in the city through the whole history of the country; however, there was no such event for the city to be as important for the city as it was important for the country and horrifying for the rest of the world. In the year of 2003, the United Nations Development Programme started a project under the name of “Chernobyl recovery and Development Programme (CRDP)” for the restoration of the injured areas from the disaster. The project started his activity taking the Human Consequences of the Chernobyl Nuclear Accident report regulations. The main mission of the project is to support the Ukrainian Government to maintain the long-term consequences of economic, ecological and social origin of the disaster. The program works in the most injured regions of Ukraine: Kiev and its region, Chernihiv, Zhytomir and Rivne regions.
As the majority of the Chernobyl city`s population was evacuated after the incident, the only people left here are the representatives of the State Agency of Ukraine on the Exclusion Zone Management and their visitors. Although, they are limited to visit the city only for the work-related purposes and only for limited amount days per week.
Nevertheless, short tours are available here from Kiev, though they are of an extreme manner and cost a lot. Several former citizens of Pripyat and Chernobyl are also returning here every year to see how their homes have changed; moreover, this procedure became a tradition among the evacuated citizens.
The last thing to say is the measures taken by the officials to protect the country and the rest of the world from any potential hazardous consequences of the plant. The current shelter, the so-called “sarcophagus” that was constructed between May and November of 1986 to hide the radioactive waste within the 4th reactor and limit the access of it to the outside space. It should be mentioned here that the shelter itself was built under the hazardous conditions of high radiation and the strict time limits. The project was partially completed as it could hide the radioactive materials and gave the possibility to monitor the remnants of the former reactor.
The shelter was never considered as the permanent measure against the incident`s consequences; however, the Ukrainian Government had no sources and funds to improve the security of the shelter. However, on 12 February 2013, a section of the roof of the sarcophagus with an area of approximately 600 m2 broke down and the reason of it considered being the enormous amounts of snow lying here. The truth was that it was the result of, inadequate construction work, and the ageing of the construction. The increase of the radiation level appeared right after the roof collapse. This and the similar issues forced the Ukrainian Government to establish a contract with French association Novarka and the last promised to establish a new and improved shelter by 2015. Their progress and the photos of the future shelter are also available online.
The Catastrophe of Chernobyl is the one of the greatest scientific mistakes and misunderstandings, the results of managerial and official irresponsibility and the blind rush for the theoretical results. The price of such mistake is the highest – the enormous amount of dead, injured and radiated, the spoiled environment and the economic situation of the countries surrounding the radiated zone. The consequences of the disaster are still unravelling in due time and nobody can predict what is going to happen next with the remnants of the greatest nuclear catastrophe of the whole world.
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