Chernobyl Nuclear Power Plant - Ukraine
-First reactor built in 1977.
-Second reactor built in 1978.
-Third reactor built in 1981.
-Fourth reactor built in 1983.
April 25, 1986
Reactor four was scheduled to be shut down for maintenance. While it was shut down, an experiment was to be done to test a safety emergency core cooling feature. The power plant managers did not acquire proper approval for running approval for the test. The test was to be completed during the day time, but it didn't go as planned. The test required reactor four's power output to be lowered by 50%, but it wasn't allowed because the power was needed for the citizens. The test was postponed to later that night, when the night shift took over.
Alexander Akimov was chief of the night shift, and Leonid Toptunov was the operator responsible for controlling the movement of the control rods. How far the control rods were placed in the core determined how much power was to be created. Leonid was a young engineer who had little experience with controlling the rods. When they started to lower the power, for some unknown reason, Leonid placed the rods too far in, causing the reactor to nearly shut down. Leonid had to override the automatic system and use manual controls to pull the rods back far enough so the experiment could be done. The power was only around one third of what it should be for the test. Yet the engineers continued the experiment.
As part of the plan, extra water pumps were turned on. The water flow exceeded the safe limit which caused the reactor's core temperature to lower. This made the operator to remove the control rods so the test could continue. This led to an unstable reactor, since most of the rods were removed. The automatic control system should have shut the reactor down, but that was disabled by the operators. The operators were unaware that the power was dangerously increasing.
April 26, 1986
Around 1 a.m., reactor four exploded, causing the top of the reactor to be exposed. Large amounts of radioactive particles were dispersed throughout the air. When oxygen contacted the extremely hot core of the reactor, it increased the emission of the radioactive particles, and the wind carried them across international borders. Nuclear power plants in the western hemisphere were built with a "containment vessel" to stop the radioactive particles from going into the air. Chernobyl did not have them.
Soviet Cover Up
The Soviet Union's first priority was to make sure that no one could find out what actually happened. The Soviet government failed to inform the world, especially the effected European countries, about the severe health issues that would come from the radiation.
"...some Soviet politicians and scientists now claim that a cover-up is still going on. They charge that 1) the accident released at least 20 times more radiation than the government has admitted, 2) Communist officials failed to evacuate nearby towns and cities right away, although they knew of the danger...legislator, Yuri Shcherbak, notes that the decision to evacuate residents of the town of Chernobyl, which is just 14 km (9 miles) from the plant, was not made until May 2, six days after the accident. By April 30, he says, radiation in nearby Kiev (pop. 2.6 million) had risen to 100 times safe levels." November, 1989 Time Magazine.
This causes a large amount of distrust in the government. When this disaster occured, the Soviet government should of aknowledged the mistake that was made, and evacuate all of the necessary people. Not only was there a large distrust of the government, but also the integrity of the government was diminished.
Design of the Plant
A nuclear reactor becomes more and more dangerous as new radioactive isotopes form and accumulate in the !rbmk_design.jpg|align=left,width=333,height=214!fuel. Therefore the most important system in the design of nuclear reactors is its safety system. The only measure to ensure substantial level of safety is to provide multiple protective devices which can be turned on rapidly one after the other. However, it is impossible to provide absolute safety due to budget limitations.
The Chernobyl-type design would not be licensed to operate in any of the West and East industrial nation due to many serious flaws in it's the design of its safety features.
The RMBK design at Chernobyl did not possess a massive containment structure found in its Western counterparts. Nuclear plants in the United States of America for example employs a design principle known as "safety-in-depth". Whereby even if the safety system fail, the Western nuclear plants can relay upon many layers of physical barrier to minimize and prevent the release of radioactive materials to the environment. These layers of protection ensure radioactive material are unable to escaped to it's surrounding and polluting the environment.
Besides that, the RMBK design used in Chernobyl has "a positive void coefficient" In layman's term, this means that nuclear chain reaction and power output increases when coolant water is lost. This caused an uncontrollable power surge that led to the disaster. While in the western world, all U.S design reactors have "a negative void coefficient". This allows the nuclear chain reaction to be automatically shutdown when coolant water is lost.
The engineers who design the Chernobyl reactor have been unethical in their practice. They failed to design a reactor with sufficient safety features incase of any emergency or conduct sufficient tests to ensure the power plant was a safe working environment. The engineers have failed to uphold the first principle of the engineering code of ethics. "Engineers shall hold paramount the safety, health and welfare of the public in the performance of their professional duties."
Another serious violation of the engineering code of ethics by the engineers is to maintain and improve our technical competence and to undertake technological tasks for others only if qualified by training or experience, or after full disclosure of pertinent limitations. The Russian engineers should have obtained expertise on the design of nuclear reactors from their Western counterparts to continue improving their knowledge in the field of nuclear engineering. With the knowledge gained specifically on the principle of "safety-in-depth" and the "negative void coefficient" the disaster could have been eliminated or the scale of the incident could be significantly lowered.
Firemen - Putting Out the Fire
When reactor 4 exploded, the firemen stationed nearby the plant reacted quickly. They were never informed of what started the fire. The firemen did not know the fire was from the reactor, they thought it would just be an electrical fire. Their main objective was to put out the fire on the roof, so it could not spread to the other reactors. One of the firemen stated, "We arrived there at 10 or 15 minutes to two in the morning ... We saw graphite scattered about. Misha asked: What is graphite? I kicked it away. But one of the fighters on the other truck picked it up. It's hot, he said. The pieces of graphite were of different sizes, some big, some small enough to pick up ...We didn't know much about radiation. Even those who worked there had no idea."
It was the firemen's obligation to put out the fire, but they should have been tought about the effects of radation, and how to handle it. When they tried to put out the fire with water, it made it worse. More radioactive particles were spread into the atmosphere. The water alone would not put out the fire in the reactor. Helicopters came and dropped over 5,000 metric tons of materials like clay, sand, and lead on top of the burning reactor. The fire was not put out until two weeks after the explosion. One of the firemen that was involved on the initial fire exstinguishing effort described the radiation, "tasting like metal...and feeling a sensation similar to that of pins and needles all over his face,"as reported by the CBC television series Witness. All of the firemen that were involved with the initial fire exstinguishing effort later died of radiation sickness, due to the lack of knowledge and information of the situation.
High exposure to radiation in the short term or 'acute' exposure is life threatening. Acute deterministic health effects occurred among the personnel of the plant, or in those persons brought in for fire fighting and immediate clean-up operations. They were subjected to the combined effect of radiation from several sources: (1) external gamma/beta radiation from the radioactive cloud, the fragments of the damaged reactor core scattered over the site and the radioactive particles deposited on the skin, and (2) inhalation of radioactive particles (UN88).
All of the dosimeters worn by the workers were over-exposed and did not allow an estimate of the doses received. However, information received from the persons hospitalized and diagnosed as suffering from acute radiation syndrome. Using biological dosimeter, it was estimated that 41 patients received whole-body doses from external irradiation in the range 1-2 Sv, 50 received doses between 2 and 4 Sv, that 22 received between 4 and 6 Sv, and that the remaining 21 received doses between 6 and 16 Sv. Normal background radiation levels are typically around 3 milliSv per year.
In the highest exposure group of those who were acutely exposed (6-16 Gy), the first reaction was usually vomiting, occurring within 15-30 minutes of exposure. These patients were desperately ill; fever and intoxication as well as diarrhea and vomiting, were prominent features. Mucous membranes were severely affected, becoming swollen, dry and ulcerated, making breathing and swallowing extremely painful and difficult. 20 of 21 with such high doses died, in spite of the intensive specialized medical treatment provided.
At lower exposures, the symptoms, signs and laboratory findings improved. Vomiting began later, platelet and white cell counts did not drop so precipitously and the fever and toxaemia were less pronounced. Beta radiation burns to the skin were a major complicating factor and mucous membrane damage was difficult to treat, but survival improved markedly at lower doses, so that no early deaths were noted in the less than 1-2 Gy exposure group
There have been many reports of an increase in the incidence of some diseases as a result of the Chernobyl
accident. In fact, the accident has, according to present knowledge, given rise to an increase in the incidence of thyroid cancers. Exposure to high levels of radiation may increase the risk of papillary and follicular thyroid cancers. In 1978 (8 years before Chernobyl) only 5 cases of childhood thyroid cancer was found in Minsk. In 1993 there were 87 cases of thyroid cancer among children. Nearly 50% of the early (1992) thyroid cancers appeared in children who were aged between one and four years at the time of the accident. At the same time 382 were diagnosed in the Ukraine.
# Dose is reported in gray (Gy) for the matter or sieverts (Sv) for biological tissue, where 1 Gy or 1 Sv is equal to 1 joule per kilogram
Radioactive clouds emitted from the Chernobyl incident polluted many parts of Europe. About 200 000 square kilometers of Europe were contaminated above the level of 37 kBq m2. Ukraine. The deposition varied to the rain when the contaminated air masses passed. The surface deposit of radionuclide, especially radioiodine, caused contamination of agricultural plants and plant-consuming animals. The radioiodine was absorbed into milk leading to a significant thyroid doses to people consuming milk especially children. Dairy animal became contaminated after feeding on the contaminated grass.
In addition irradiation from radionuclide released from the incident had an acute effect upon the flora and fauna living in the high exposure areas. There was a reported of increased mortality of plants, soil invertebrates and mammals. Also, there have been reproductive losses in plants and animals.Genetic effects on somatic cells have been seen in the exclusion zone. Although whether the observed cytogenetic anomalies in somatic cells have any detrimental significance is not known.
However, the animals and plant population have been recovering from the radiation effects. This due to the reduction of exposure levels due to radioactive nuclide decay. The population of flora and fauna recovered through the effects of reproduction and immigration. The termination of human activities- agricultural, industrial and settlements- have even expanded the population of many animal and plant species.
When reactor number four at Chernobyl released radioactive particles in quantity 100 times more then the atomic bomb upon Hiroshima's, plans for new nuclear plants were halted worldwide. Plans to phase out nuclear power were carried out by politicians, particularly those in Europe. The health impact of Chernobyl is at an estimated 4,000 deaths from radiation-related illnesses. However this does not include the other side effect of the disaster including mental illnesses stemming from displacement, high divorce rates, and depression of the people involved. This still remains a serious concern even till today.
The Chernobyl incident served as a catalyst for the formation of The World Association of Nuclear Operators. The mission of this organization is "to maximize the safety and reliability of the operation of nuclear power plants by exchanging information and encouraging communication, comparison and emulation amongst its members." ("The Wano Mission", 2008)The organization also serves as the industry watchdog and writes private & confidential safety reviews for all nuclear power plant. In addition the United States and other Western countries have also spent hundreds of millions of dollars to improve the safety of the dozens of other Chernobyl-era reactors in the former Soviet Union and in their homeland.
The government adopted many policies to cope with the consequences of the Chernobyl nuclear accident. The cost of the accident both direct and indirect spanning 2 decades is estimated at hundreds of billion of dollars. Direct cost of the accident includes cost to seal off the reactor, resettlement of people, radiation monitoring of the environment. Indirect losses relates to the opportunity cot of closure of agricultural and industrial facilities. Government spending on Chernobyl placed a huge burden on the countries budget. In Ukraine, 5 to 7% of government spending is devoted to Chernobyl related benefits even till today.
Majority of the contaminated areas were in the rural region. The main source of income was the agricultural sector. A total of 784320 hectares of land were removed from service; timber production came to a halt for 694200 hectares. Stringent radiological control by the Europe Union and the Soviet Union limited the market for food product from affected regions. Even after remedial methods have made farming save. The fear of Chernobyl caused consumers to reject products from the region. This caused the revenue from agricultural activities t fall.
Three Mile Island
The Three Mile Island accident of 1979 was a partial core meltdown in Unit 2 of the nuclear power plant of the Three Mile Island Nuclear Generating Station in near Harrisburg. It was the most significant accident in the history of the American commercial nuclear power generating industry. This accident resulted in the complete cessation of nuclear power plant construction in the US.
Unlike Chernobyl, there is no deaths or injuries to plant workers or members of the nearby community that can be attributed to the accident. The average radiation dose to people living within ten miles of the plant was 8 millirem ( equivalent to a chest X-ray) and the maximum was 100millirem to a single individual ( a third of the average background radiation received by US resident yearly). In addition, a government report (the "Kemeny Commission Report") concluded that "there will either be no case of cancer or the number of cases will be so small that it will never be possible to detect them." This was due to the effective safety system implemented.
In comparison, the 1986 accident at Chernobyl was the worst nuclear disaster that has befallen the nuclear industry. It was caused by a series of mistake by the operators and aided by a positive void coefficient, the lack of a containment building. The Soviet too refuse to evacuate its citizens quickly while in the US plans to evacuate citizen within 20 miles of Three Mile were prepared within 24 hours of the incident.
The Chernobyl incident is widely regarded as the worst nuclear accident of the century. There been many incidents where unethical acts have taken place. For instance, the Soviets attempting to cover the incident up, the safety features of the plant and the lack of preparation by the Russian's engineers in case of a disaster. There also been aspect of globalization like the formation of The World Association of Nuclear Operators and the effect of this disaster upon the people perception of nuclear energy and other countries nuclear power plant plans
Medvedev, Z. The legacy of Chernobyl. New York/London: Norton. 1990.Time Magazine. May, 1986
"Institute of Electrical and Electronics Engineers' Code of Ethics " http://www.ieee.org/web/aboutus/ethics/code.html*
"American Society of Civil Engineers' Code of Ethics" http://www.asce.org/inside/codeofethics.cfm.html*
- Figure 2, *http://www.globalsecurity.org/wmd/world/russia/images/rbmk_chornobyl_017.jpg*
- Figure 3, *http://www.theijs.com/uploads/thyroid-cancer-retrosternal.jpg*
- "Chernobyl, Nuclear Power, and Foreign Policy." *http://www.cfr.org/publication/1053/chernobyl_nuclear_power_and_foreign_policy.html#2*
- "WANO Mission." *http://www.wano.org.uk/WANO_Documents/WANO_Mission.asp*
- "Chernobyl's legacy: health, environmental and socio-economic impacts and recommendations to the governments of Belarus, the Russian Federation and Ukraine.", Chernobyl Forum, published in 2002