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This paper focuses on what went wrong with the Chernobyl nuclear explosion and the consequences associated with it. First, it discusses issues related to human errors such as the operators not properly following regulations and performing a dangerous experiment, and it also discusses problems related to the RBMK core reactor which created the conditions for the explosions. Major environmental and health problems were consequences that resulted from the nuclear disaster. Another focus on the Chernobyl explosion is the nuclear fallout or pollution caused by the explosion in Northern Ukraine on the Pripyat River, where it resulted in atmospheric contamination by radionuclides, leading to soil and water resource contamination. The Chernobyl disaster has caused health problems for Ukrainians such as thyroid cases and weakened immunities.
Nuclear power is considered an alternative source of energy. Nuclear power is produced by the fission or splitting of atoms, which ultimately are used to produce power. As the nuclei of the atoms break apart, subatomic particles such as neutrons are released as well as electromagnetic radiation, referred to as radioactivity (Haycock, 2004). The purpose of a nuclear reactor is to produce nuclear energy by splitting the atoms slowly with a great degree of control. The heat produced from the splitting of the atoms is used to drive the generator, which will ultimately produce electricity needed for homes (Haycock, 2004).
Nuclear power has its benefits as well as its disadvantages. It can be very useful when proper technologies are used and when does not result in the release of carbon dioxide as carbon dioxide molecules contribute to pollution. Nuclear power plants can harvest a lot of electricity, in which the electricity can indeed be very useful to home owners (Baratta, 2009). There are also serious disadvantages associated with nuclear power such as the risk of meltdowns and explosions if too much power is produced in the reactors, thus resulting in a potentially lethal power surge. Another risk associated with nuclear power is radiation which is released by radioactive molecules such as uranium, strontium, and cesium (Pediatrics, 2003). Unstable atoms release energy and radiation. The radiation is dangerous to humans and can cause tissue damage because of injury to skin cells and eventually illnesses such as autoimmune diseases and thyroid cancer (Pediatrics, 2003). Neutrons are particular dangerous as the damage caused increases by tenfold compared to gamma rays (Pediatrics, 2003) Another feature of neutrons making them more dangerous is their higher mass and the greater degree of energy that travels along paths. Neutrons are a less common type of radiation, but are observed in explosive nuclear reactions, as in the case of Chernobyl (Pediatrics, 2003).
In order for the reactor to work effectively, there needs to have a balance with the number of neutrons. Neurons help to rotate the core, thus generating energy. If there are too few neutrons rotating around the core, the reactor will stop (Montgomery, 2008). However, if there are too many neutrons, the reactor will spin out of the control if the reaction is not contained immediately, and there will be the risk of a nuclear meltdown (Pediatrics, 2003).
The Chernobyl Accident was regarded as the most serious nuclear disaster that ever occurred in recorded history (Stapleton, 2004). Chernobyl was a catastrophic nuclear explosion that took place in the northern region of Ukraine along the Pripyat River on the early morning of April 26, 1986 (Imanaka & Kawana, 2009). The destruction of one of the nuclear reactors resulted in the release of radioactive material and ashes into the atmosphere, resulting in atmosphoric, soil, and water contamination (Muhr & Rehkopf, 2003). The largest volume of radionuclides emitted from Chernobyl included iodine, xenon, and tectnetium, in which they were short-lived (Onishi). As well, the area surrounding Chernobyl became contaminated with radionuclides such as plutonium, cesium, and iodine (Pediatrics, 2003). The disaster forced approximately 400,000 people to abandon their homes, and radioactive contamination affected at least 10,000 square kilometers of land in Europe (Imanaka & Kawana, 2009).
Category of Chernobyl Sufferers
Total Body Dose
A. Staff of NPP and firefighters who were at the scene.
B. Liquidators (military, construction workers etc)
C. Evacuees from the 30km zone
Average 30 mSv*
D. Inhabitants of highly contaminated areas and resettlers
Average 50 mSv
E. Inhabitants of contaminated areas (>37 kBq/m2)
Average 10 mSv
*; The present authors consider that this value is underestimated.
Millions of people suffered from the radiation originating from the Chernobyl site. As indicated from the chart above, the figures show that staff members of NPP and firefighters listed in Category A suffered from the most harmful effects of radiation, receiving a dose within the range of 1-20 Sv 17. Close to 200 workers were working in the first four reactors at the time of the accident while close to 300 workers were doing construction work in the fifth and sixth reactors (I & K, 2009). Firefighters instantly felt the effects of radiation from Sv 17, in which they instantly became sick and suffered from burns. The radiation dose, averaging 10 mSv in Category E, represents the inhabitants of contaminated areas was not nearly as high as figure, but still nonetheless dangerous with detrimental effects on their health (I & K, 2009) Soviet authorities reported that a total of 31 people died from the explosion, including two of the day of the explosion and one more person from an unknown cause (Imanaka & Kawana, 2009).
Image of Sarcophagus
Chernobyl Sarcophagus. Photo in November 2002 by Imanaka T.
The graphite rock burned for another ten days, releasing more radiation into the atmosphere. The Soviet Army was called to come destroy the fire. One month following the explosion, a sarcophagus was constructed around the fourth reactor to prevent the further spread of radionuclides (Imanaka, 2009).
There is evidence that human error led to the explosion. The engineers of the Chernobyl Nuclear Power Plant wanted to try a new but risky experiment that would involve lowering the power of one of the operating units to near shutdown level and determining the generator if could produce enough power to make the reactor work efficiently in case of a shutdown (Hepworth, 2003). The Chernobyl engineers proceeded with the experiment in the early hours of April 25, 1986. The operators turned the power to a level too low (Stapleton, 2004). At approximately 11 PM on April 25, 1986, the systems started showing signs of instability (Hepworth, 2003). At 12:30 AM on April 26, 1986, the operator could not control the power level effectively because the power nearly reached 0 MWt, whereas the initial plan in the experiment was to reduce the power to only 700 MWt (Imanaka & Kawana, 2009). If all of the operators would have stopped the experiment at this point since the systems were already showing numerous signs of stability, the Chernobyl explosion would have never occurred (Imanaka & Kawana, 2009). Human error was one of the main factors with regard to what went terribly wrong with Chernobyl.
At 1 AM on the morning of April 26, 1986, the engineers increased the power of the reactor to attempt to stabilize it (Hepworth, 2003). Approximately twenty minutes later, the water approached its boiling points, and the reactors were becoming even more unstable (Stapleton, 2004). The engineers attempted to put rods in the reactor, but could not fully push them into the reactor since the heat and pressure were already destroying the structure of the graphite core needed to control the reaction. The engineers made another error by not using enough rods to control the reactions and therefore were conducting the test improperly. Orders stated that they needed to use at least thirty rods (Stapleton, 2004). At 1:24 AM, the explosion occurred as the power increased two-thousandth fold (Hepworth, 2004).
There were issues and dysfunctions with the structure of the power plant. That had happened was that there was a meltdown in unit number four, and it began malfunctioning, which eventually led to an explosion.
It appears that there were internal flaws within the nuclear system. The type of the reactor in unit four was called a RBMK reactor, which stands for "Reaktor Bolshoi Moschnoshi Kanalynyi" (Onishi). The RBMK was a graphite tube reactor, which boiled water, and the fuel moved through 1690 channels throughout the reactor. The reactor was classified as unsafe as it did not meet international safety standards because there were issues with the core cooling system and control system (Onishi). In contrast to Western nuclear reactors, the Chernobyl reactor did not have a containment building, and it is crucial that the containment building is in place to retain radiation. Graphite was not an effective material for a reactor in Chernobyl as high temperatures caused it to burn.
Before the reaction, the reactor core reached very high temperatures, which overheated, resulting in a meltdown with the core materials turning into a hot molten mass (I & K, 2009). With regard to the Chernobyl incident, the reactor core also caused a steam explosion, which resulted in the release of radiation (Onishi et al). Steam was the fuel instead of water. Steam reaches higher temperatures more quickly while water does not, and water serves as a moderator. The reactor core had a positive void co-efficient because the excess steam created voids or packets, thus promoting excess fission reactions and ultimately leading to a power surge, which resulted in the explosion (I & K, 2009). It was a possibility that leaks resulted in the production of hydrogen gas, thus completely disrupting the cooling systems and resulting in the explosion. The moderator was made of graphite, which increased the risk of the explosion since it did not absorb the neutrons as well (Montgomery, 2008). The uranium particles and graphite core created an intensely hot molten structure.
2 - CONTAMINATION - ATMOSPHERIC CONTAMINATION, SOIL CONTAMINATION, AND WATER CONTAMINATION
2.1 - ATMOSPHERIC CONTAMINATION
The surrounding area became contaminated with radioactive elements such as cesium, iodine, and plutonium, and the contamination affected over 21,000 square kilometers of land, also hitting other neighbouring countries such as Belarus and Russia particularly hard, and spreading to other sections of Europe (Pediatrics, 2003). The notorious radioactive cloud broke into two main lobes in the beginning of May 1986: one heading north and the other heading west. The north lobe affected countries such as Poland, Germany, the Netherlands, and eventually Scandinavia (Epidemiologic Reviews, 2005). As the wind switched directions to the south, the radioactive clouds brought radioactive elements to Italy and the Balkans (Hepworth, 2003). Nuclear fallout rose into the atmosphere and travelled thousands of kilometers facilitated by wind and atmospheric conditions. It did not help that the wind frequently blew in different directions days following the event, which evidently led to greater nuclear fallout and devastation experienced in other European countries (Epidemiologic Reviews, 2005). Nuclear fallout refers to radioactive particles microscopic in size but evidently severe enough to cause adverse effects.
2.2 - SOIL AND PLANT CONTAMINATION
Nuclear fallout hit other European countries, resulting in contamination to soil, animals, and plants. Evidence shows that the soil was contaminated to a certain degree in each of the Northern Hemisphere countries (Haycock, 2003). The Chernobyl nuclear disaster forced European farmers to destroy their farming lands because of radioactivity, and forests also had to be cleared because of radiation (Hepworth, 2004). Hunting restrictions have been placed in forests (Zink, 2009). Since livestock such as cows were feeding off of contaminated soil and grass, evidence indicated that the milk from the cows contained radionuclides. The radioactive isotope, 131I, was found in milk (Bratilova, 2009). Some countries banned the selling of milk and vegetable products. There was the fear of radioactive contamination, which would be harmful to people ingesting potentially contaminated products (Muhr & Rehkopf, 2003).
Map of the Narodichesky region's territory soil pollution by 137Cs
Another radionuclide that contaminated the soil was 137C (Stepanova et al, 2008). An area adversely affected by cesium contamination is the Narodichesky region of Ukraine where it is located less than 100 km away from the former Chernobyl Nuclear Plant (Stepanova et al, 2008). The diagram above illustrates the pollution levels in the different regions as shown by the different colours with red being the most severe, and the average pollution is 236 kBk/m2 in villages located throughout the Narodichesky region (Stepanova et al, 2008). The values of cesium contamination in soils range from 29 to 879 kBq/ m2 (Svendson, 2009). Radioactive contamination was more severe in this area not only because of its fairly close proximity to the former nuclear site, but also because 75% of the population lives in regions where they grow crops (Stepanova et al, 2008). Cesium is a radioactive element, which was a rather long half life of thirty years. The highest depositions of radioactive cesium (137Cs) were located near the top layers of the soil, in which plants and mushrooms grow (Stepanova et al, 2008). As plants grow, the delicate root systems absorb the cesium into the rest of the plant (Nillson, 2009). Berries were also contaminated from radioactive cesium (Zink, 2009). And consequently, the radioactive nuclides enter rest of the food chain when other animals feed off of these plants (Stepanova et al, 2008).
2.3 - WATER CONTAMINATION
The Chernobyl explosion has also contaminated bodies of water and water resources. of the location of the Chernobyl plant near the Pripyat River, the radionuclides travelled down the river, also entering the Dnieper River (Onishi). Both rivers are the main water pathways in Ukraine, which unfortunately have resulted in the further spread of water contamination from radionuclides (Onishi). From run-off originating from surface waters and larger bodies, the contamination entered sewage and sludge systems (Zink, 2006). Radionuclides have been found in other bodies of water such as streams, lakes, and rivers and in aquatic life forms (Smith & Voitsekhovitch, 2009). The levels of radioisotopes such as cesium will remain high for years in closed lakes for years, as there are no streams that exit from the lakes, and residents will be restricted from fishing as contamination has also affected fish (Zink, 2006). As well, the residents of Ukraine and Belarus are more prone to contamination because they rely on the shallow wells for drinking water (Yablokov & al, 2009). Due to soil run-off and leaching into bodies of water, Sr-90 has been also discovered in rivers. Sr-90 is highly soluble and stays in the water for much longer because of this reason (Amano, 1999). The Dnieper River is at least 1000 km in length and empties into the Black Sea, which has carried radionuclides with it and affecting other areas (Onishi, 10). Thirty percent of radionuclides affecting water resources were deposited in the Dnieper River, which included cesium, strontium, and plutonium. (Onishi). Forty percentage of radioisotopes were also located in Sozh and Iput river basins in Russia.
Since the nuclear explosion led to air contamination and winds blowing radionuclides thousands of kilometers away, radionuclides were also found in rain waters and in rivers in places as far away as Japan and North America (Karmaus & et, 2008). The nuclear disaster did not only affect the bodies of water locally in Chernobyl but also in other continents on a global scale.
3. HUMAN IMPACT
The Chernobyl nuclear explosion not only caused environmental problems but also health problems in humans. Radiation is indeed quite harmful to people. Iodine and cesium are particularly harmful radionuclides (Onishi). Once iodine and cesium are inside the human body, they release beta particles in the form of carcinogens, where carcinogens are cancer-causing agents (Bortman & al, 2003). European countries posted warnings to people, particularly children, to stay indoors to minimize exposure to radiation (Mur & Rehkopf, 2003). Large quantities of radiation cause burns to the skin and internal damage to the digestive and nervous system. Smaller doses have caused mutations and cancer (Haycock, 2004). A particular health problem associated with Chernobyl has been thyroid cancer as there has been a dramatic increase in the number of thyroid cancer cases. The Belarusian Ministry of Health officials reported that thyroid cancer incidents skyrocketed in areas afflicted by contamination in 1990 (Stapleton, 2004). The radionuclide, 131I, entered the body through the consumption of food and milk and accumulated in the thyroid (Bratilova, 2009). What happens is that radiation interferes with thyroid function and results in thyroid problems such as hypothyroidism and thyroid cancer. It has been observed in children affected by the Chernobyl incident is that they have had enlarged thyroids (Thyroid, 2003). Other countries located hundreds of kilometers away from the former Chernobyl Nuclear Plant site have reported an increase in the number of cancer cases. Turkish health officials have reported than the rate of patients with leukemia is twelve times higher after the Chernobyl compared to before it happened (Stapleton, 2004).Â
Victims of the Chernobyl Nuclear Disaster
"Victims of the Chernobyl Nuclear Disaster." UPI Photo Collection. Academic OneFile.
As show in the above photograph, children are more prone to suffering from the consequences of radiation, usually from thyroid cancer. A couple reasons are their smaller body masses and metabolic differences in comparison to adults. (Yablokov & al, 2009). If they drink milk from cows who have fed off the ground contaminated by radiation, they are more susceptible to radiation. Childrens' diets also include vegetables, which have been grown in soils contaminated by the nuclear fallout. Iodine, a dangerous radionuclide, tends to target the thyroid gland, causing damage to it and thus health problems (Bennett). Cancer rates have increased in children since the Chernobyl accident. Four thousand thyroid cancer cases in children who were zero to fourteen years of age at the time of the disaster have been recorded by medical officials up to the 2002 records (I & K, 2009). While the morality rates are not high in children with thyroid cancer, these children of Chernobyl will be required to take medication for the rest of their lives to regulate their thyroids (I & K, 2009)
LOWER BLOOD COUNTS
The radioactive contamination has caused other health issues for Ukrainians and Eastern Europeans such as lower blood counts. Medical studies conducted by the Chernobyl Sasakawa Health and Medical Cooperation project show that red and white blood cell levels as well as platelet counts are lower than average for people living in contaminated areas in comparison to healthy individuals . (Stepanova & al, 2008). The levels were even lower in children where soil contamination was higher from 137Cs. (Stepanova & al, 2008). Overtime, improvements in red and white blood cells counts as well as platelet levels have been recorded. (Stepanova & al, 2008). Health tests show that respiratory function is lower than healthy individuals. There is evidence that 137Cs affects the way lungs function. (Yablokov, 2009) Plus, children are more prone to infections if their blood tests are low, thus weakening their immune systems. (Svendsen, 2009)
One of the main causes of the catastrophe was that the operators violated safety regulations (I & K, 2009). It was also the tradition of Soviet Authorities to blame others for the accident and not accept responsibility (I & K, 2009). In 1991, the USSR government disappeared because of the fall of the USSR, and now the responsibility lay in the hands of Ukraine, Russia, and Belarus (I & K, 2009). Intervention from Western countries would be useful in increasing safety and operational standards in the former Soviet countries (Hepworth, 2004). There is evidence that many other reactors are unsafe, and government intervention is needed. Engineers redesigned the core reactors to improve the safety. The nuclear accident has prompted governments to take action by phasing out nuclear power plants and in nations such as Italy and Finland, shutting them down completely. (Norsdacht, 2008).
The explanations show that many things went wrong in the Chernobyl Nuclear Power Plant, leading to the explosion. As discussed by Hepworth, Stapleton, and Imanaka & Kawana, human error was a factor, in which the engineers tried a risky and unsafe experiment, did not properly follow procedures, reduced the power too low, and used too few rods to control the fission reaction. The graphite structure of the reactor was problematic as it was inaffective at high temperatures in absorbing neutrons and eventually turned into a molten radioactive mass. After the explosion, the results show that there was extensive contamination in Ukraine, Belarus, and Russia and other parts of Europe. The results show that contamination had an impact on air quality and the quality of soil and water resources. Cesium and iodine have been detected in the air, soil, and in bodies of water throughout Ukraine and Eastern Europe. The explosion also led to health problems. As discussed in Stepanova 2008, there was a direct correlation between radiation and illneses, in which the findings showed that patients affected by higher doses of cesium had lower ethrocyte and leukocyte levels as platelet counts. There were also a higher incidence of cancer cases in children because of differences in weight and metabolism.
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Light Water Graphite Reactor (RBMK) - Encyclopedia of the Earth
137 Cesium Exposure and Spirometry Measures in Ukrainian Children Affected by Chernobyl
Chernobyl Accident: Impacts on Water Resources
Uptake of 137Cs by fungi and plants due to potassium fertilization in Heby municipality
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