Power Plants at Fukushima and Onagawa - Term Paper Example

FUKUSHIMA DAIICHI POWER PLANT DISASTER 2011 Introduction Japan experienced a devastating earthquake with a magnitude of 9.0 on 11th of March, 2011. The epicenter was at off-coast of Honshu. Due to this earthquake 55 nuclear power plants were shut. Power plants at Fukushima and Onagawa, in Japan’s Futaba district experienced highest risks, not only from the earthquake but from resultant tsunami also. While Onagawa power plants escaped, Daiichi nuclear power plant at Fukushima suffered from hydrogen explosions. During the disaster, huge amount of nuclear fuel were also damaged along with heavy discharge of radioactive elements into surrounding environment. (Holt, Campbell and Nikitin, 2012, p. 2) A lot of lives were lost due to the earthquake and tsunami. Numerous people lost their families and friends. The condition was made worse by leakage of radioactive materials from Fukushima- Daiichi power plant. The Daiichi disaster is often considered as a natural disaster for it caused by two natural disasters with high magnitudes. While the other nuclear stations survived, the Daiichi power station succumbed to combined force of the earthquake and tsunami (Lüsted, 2011, p. 6- 11). Disaster Tokyo Electric Power Company (TEPCO) is in charge of Fukushima- Daiichi power plant. This nuclear power station had six nuclear units in total. Another nuclear power station of Fukushima, Daini consist four nuclear units. The nuclear reactors situated in Daiichi were basically boiling water reactors (BWRs). The first five reactors bore General Electric Mark-I designs. Nuclear powers were generated for commercial operations. Uranium- 235 and plutonium- 239 are the nuclear fuels. These compositions are heavy isotopes and produced energy through fission of nuclei. Each such reaction results in generation of more fusion events, which in turn support a continuing nuclear chain reaction. Fusion products that are produced “s iodine- 129, iodine- 131, strontium- 90, and cesium- 137”. Whenever, shutting down is required, control rods are inserted. These rods function by absorbing the neutrons. During nuclear reactions, heat is produced by radioactive decay. Therefore, it is necessary to keep on pumping water and circulate it so as to reduce the decay heat. Normally, the reactors take a few days time to cool down fully and reach the “cold shutdown” state (Holt, Campbell and Nikitin, 2012, p. 4). Condition of reactors at Fukushima- Daiichi power plant: When the earthquake started on 11th, half of Daiichi nuclear reactors were automatically shut down and the other half were suspended from regular functions for routine inspections. However, all though the earthquake, Daini reactors were operating. They were shut after the quake. During the earthquake, nuclear units 2 and 3 of Daiichi were affected by horizontal acceleration of ground, exceeding maximum level. The tsunami caused by the earthquake proved to be most fatal. The Fukushima Daiichi power plant faced the wrath of six-meter-high seawall, barely forty minutes after the intense earthquake. This disconnected the whole plant from national electricity grid. Diesel generators at plant were used for AC power. But due to tsunami waves, most generators as well as electrical switchgear rooms were flooded away. This hampered the backup AC power to a large extent. Both nuclear unit 5 and 6 was saved by timely power generated by air-cooled diesel generator. Other than these two, all other units suffered from fuel damage (Holt, Campbell and Nikitin, 2012, p. 4). The Daiichi plant suffered a power crisis for the tsunami waves brought down the plant’s whole DC power distribution. Thus, immediately after the tsunami waves hit the plant, units 1 to 4 stated cooling problems. Neither the primary, nor the secondary cooling system functioned. When seawater was pumped in by TEPCO to cool the reactors, the water got contaminated with neutron- absorbing boron. However, this strategy failed to yield desired results and the reactors were overheated for next few days. Loss of nuclear fuel was reported on 2nd December, 2011 by TEPCO. In reactors 1 to 4 most of the nuclear fuels had melted and a portion of them had also leaked directly into atmosphere. As a result of chemical reaction between the volatile zirconium cladding with heated steam resulted in production of hydrogen. This is the hydrogen that was leaked through containments of 1 and 3. The hydrogen could have also leaked from venting systems, causing large- scale explosions in the reactor buildings as well as in the nuclear units of 1, 3, and 4. It has been calculated that each such explosion had released 800-1,000 kilograms hydrogen into Japan’s atmosphere (Holt, Campbell and Nikitin, 2012, p. 5- 6). Fuel pools of Fukushima- Daiichi reactors were also affected and in turn it removed the fuel rods. Large amount of radioactive materials left with the spent fuels were responsible for generating so much heat. Water was discharged from the power plant to prevent the water of spent fuel pools from boiling and leaking. This would have resulted in overheating of spent fuel rods and subsequent mixing of radioactive elements into outer atmosphere. However, release of radioactive materials could not be stopped as they were discharged through explosion in reactor buildings. Stored fuel in the pools was wasted due to debris. (Holt, Campbell and Nikitin, 2012, p. 6) Once the reactors were affected in Fukushima, Daiichi power plant, radioactive materials escaped from the reactors and got mixed with outer atmosphere. This contamination was further fuelled by venting along with hydrogen explosions. The water that was pumped into the reactors to control their heat also got contaminated. To the worst, the contaminated water mixed with Pacific Ocean, for it was either leaked or discharged. It was found out by INPO that, a total of 130,000 curies of water was leaked into ocean. Before it released, the water was inside the turbine building and before finally leaking into the cabin had also flown through the trench. (Holt, Campbell and Nikitin, 2012, p. 9- 11) As a precaution, the local authorities compelled evacuation with a radius of three kilometers all around the power plant due to tsunami forecasts. After the dose was found to be increased the following day of the disaster, evacuation was expanded to ten kilometers on the first step and then ultimately up to twenty kilometers. During this time, the dose rate was as high as 400 times to normal dose level within the plant, reaching its highest at 1,085 millirem/ hour on 16th March, 2011. Due to evacuation program, as many as 84,000 residents who dwelled within twenty kilometers of Fukushima- Daiichi power plant had to settle elsewhere by April. Later on during middle of May, another 15,000 residents were made to evacuate the northern area of Fukushima plant. In the northwest region, radius spanned up to forty kilometers. Certain initiatives were taken by Japanese Government to fight this natural disaster. Among them one program was about decontaminating the whole region. Reduction of doses of annual radiation was aimed to be reduced to 100 millirem, which is the international standard. However, it has to be remembered that the whole process of decontamination is a long term one (Holt, Campbell and Nikitin, 2012, p. 11). With further deterioration of reactor condition and subsequent increase in emission of radioactive elements, large stretches of land around the power plant became uninhabitable due to high contamination of land. The atmospheric contamination was further spread by winds. Radioactive materials even spread across the Pacific Ocean and made a northward shift. Things were more worsened by mid- March winds and heavy rains. The rains washed down the contaminating elements from air and thus, contaminated the land also by depositing radioactive cesium. It is worth noticing that the contamination caused by Fukushima- Daiichi plant was long lasting in nature. When compared with Chernobyl power plant disaster, it is found that the intensity of damage is almost similar in both cases. It was claimed by French Institute de Radioprotection et de Surete Nucleaire (IRSN) that surrounding environment with an radius of twenty kilometers was severely contaminated. But often the impact is considered to be less severe than that of Chernobyl for Fukushima land experienced only 16.2 microcuries per sq. meter of cesium deposits (Holt, Campbell and Nikitin, 2012, p. 11). Fukushima: Daini power plant Besides Daiichi, Fukushima had another nuclear power station at Daini. This site is located towards the south of Daiichi power plant, at a distance of twelve kilometers. In Daini power station, nuclear reactors were damages both by earthquake and tsunami. While the workers successfully closed reactor 3, reactors 1, 2, and 4 as well as their cooling systems were damaged. However, Daini escaped the disaster by retaining offsite power on time. It could maintain supply of water to cool the reactors. To manage the crisis, condensate systems along with makeup water were used. This kept the water level intact during the cooling system. Thus, reactors 1, 2, and 4 were saved. Afterwards necessary repairs and improvising were made by TEPCO. (Holt, Campbell and Nikitin, 2012, p. 9) There has been much controversy about role of Japanese Government in the Fukushima- Daiichi disaster. Japan’s government had permitted TEPCO to release 10,000 cubic meter water into ocean. This water was comparatively less contamination. The decision was taken during early April 2011 as a measure to store large volumes of water which was more contaminated with radioactivity. However treatment facility was used for this highly contaminated water only. The facilities were set up at site and through it contaminating elements were removed from water. The stored water was later on recycled for cooling and other purpose within the plant. (Holt, Campbell and Nikitin, 2012, p. 11) Assistance International Atomic Energy Agency, in collaboration with United States provided aid for Fukushima- Daiichi disaster. US intervention was due to request on part of Japanese Government to help fight dual calamities of earthquake and tsunami. Support was provided by US in the form of advice s well as in the form of equipments like “pumps, boron, fresh water, remote cameras, use of Global Hawk surveillance drones, evacuation support, medical support, and decontamination and radiation monitoring equipment.” Moreover, agencies like Nuclear Regulatory Commission (NRC), The National Nuclear Security Administration (NNSA) and Department of Energy (DOE) extended their support in the form of equipments. Equipments provided for measuring level of radiation and Aerial Measuring System along with analysis from US- based laboratories contributed greatly to disaster management programs. Water pumps of high- pressure and fire trucks were supplied by U.S. Department of Defense to control the heat of the reactors and cool them. These had reduced contain damage level. After providing immediate aid to the Japanese Government, U.S has been working in collaboration to decontaminate the effects of radioactive elements. Alongside providing the remedial measures, U.S was involved in decommissioning process of Fukushima Daiichi nuclear power plant. On Japan’s behalf it was declared that further precautionary measures were taken for nuclear sites like Hanford and Savannah River. Moreover, Japanese officials are provided trainings through workshops for managing such disaster. It is hoped that through these, Japan would be able to deal with radioactive waste in a better way as far as storage and disposal is concerned. The decontamination processes, with US collaboration is expected to continue for some more years (Holt, Campbell and Nikitin, 2012, p. 12) Conclusion The disaster at Fukushima- Daiichi nuclear power plant once again pointed to the fact that nuclear reactors possess a potential for severe damage. Emission of radioactive materials not only results in long term damage to the environment, but also has direct and indirect effect on general public health. The disaster had huge impact on Japan’s national economy and amounted to heavy financial loss. The evacuation process also added up to this as the Japanese Government had to shell out millions. Soon after the disaster, radiation level around the reactor plants was recorded as very high. The radioactive elements released resulting in high contamination of ocean water, land and air. It caused permanent damage to heath of thousands of inhabitants and the effects are likely to continue in their future generations also. Thus, the disaster was not totally a man made one; natural calamities were equally responsible for the mishap. References Holt, M., Campbell, R. J. and Nikitin, M. B., (2012), CRS Report for Congress, retrieved on June 30, 2013 from: http://www.fas.org/sgp/crs/nuke/R41694.pdf Lüsted, M. A., (2011).The 2011 Japan Disasters, US: ABDO Read More