Events Resulting in the Fukushima Daiichi Nuclear Plant Disaster - Term Paper Example

? The liability of the Tokyo Electric Power Company (TEPCO) for the Fukushima Daiichi nuclear disaster The paper looks at the Fukushima Daiichi nuclear disaster. The impact of the incident to the environment was devastating and the effects from the release of radioactive substances will make the areas around the plant uninhabitable for centuries. The radiation is also harmful to people exposed. The failure of the nuclear plant reactors occurred after the emergency generators serving the facility failed. The emergency generators in the plant failed after the rooms housing the generators flooded and the generators were drowned. Sea water breached the tsunami walls protecting the facility after a tsunami that followed the earthquake. The tsunami wave was 13 meters while the tsunami walls protecting the facility were only 10 meters high. TEPCO had predicted a possibility of a tsunami wave breaching the wall in case of an earthquake of a high magnitude. The paper seeks to establish the liability of the company in regard to the Fukushima Daiichi nuclear disaster. Table of contents 1. Introduction……………………………………………………………………….…4 1.1 Fukushima I nuclear power plant…………………………………….….……..4 2. Causes of the Fukushima I nuclear plant disaster……………………………….…...5 3. Safety issues relating to the Fukushima nuclear plant prior to the disaster.……..…..6 3.1 Changed layout of the emergency cooling system……………………………. 6 3.2 Falsified safety records by TEPCO……………………………………….…..…6 3.3 Prior failure of the backup generator ………………………………….…………6 3.4 Ignored tsunami warning………………………………….……………….……..7 3.5 Location of the reactor…………………………………………………….……..7 4. Events resulting in the Fukushima Daiichi nuclear plant disaster………………….….…7 4.1 Issues in Unit 1……………………………………………………………….…8 4.2 Issues in Unit 2…………………………………………………………………..9 4.3 Issues in Unit 3……………………………………………….…………………..9 4.4 Issues in Unit 4……………………………………………………….……….….10 5 Release of radioactive substances into the environment………………….………………...10 6. Liability for the Fukushima nuclear disaster…………………………….…………………11 6.1 Assessing TEPCO’S liability…………………………………….……….…...12 Work cited ……………………………………………………………………………………14 1. Introduction The Great East Japan Earthquake with magnitude of 9.0 did a substantial damage to Japan and its environs. The gigantic tsunami that followed the quake resulted in more damage. The earthquake was complex and unusual double quake with a severe period of around 3 minutes. As a result of the earthquake Japan shifted a few meters east and the country's coastline sank half a meter. The death toll from the earthquake is recorded at 19,000, and much of the coastal area was destroyed. 1.1 Fukushima I nuclear power plant The Fukushima I Nuclear Power Plant comprised of six boiling water reactors. These reactors were designed by General Electric. During its activity, the plant produced a total power of 4.7 gigawatts. The plant was among the largest nuclear plants around the world. It was run by TEPCO (Tokyo Electric Power Company). At the time of the earthquake unit 1, 2 and 3 of the plant were operational while unit 4 had been de-fueled and both unit 5 and 6 had been shut down for maintenance. After the earthquake the functioning units in all nuclear plants, including unit 1, 2 and 3 in the Fukushima I plant were shut down following government regulations (Ohnishi, 12). A 13 meter tall tsunami hit the plant about an hour after the 9.0 magnitude earthquake. The tsunami wave overcame the plants sea wall which was a mere 10 meters high. The water from the tsunami flooded the plants low lying rooms, which housed the plant's emergency generators. The flooding resulted in the failure of the emergency diesel powered generators and this cut off power to critical pumps in the system. 2. Causes of the Fukushima I nuclear plant disaster Nuclear power reactors produce energy by splitting atoms, normally uranium. The splitting of these atoms produces fission products, which in turn cause other atoms to split resulting in a chain reaction. Even after the chain reaction is stopped the reactor will continue to produce heat because of the unstable isotopes created during the fission process. The decay of the unstable isotopes produces heat and cannot be stopped. In order to remove the heat, cooling water must continue to circulate the fuel rods, the spent fuel pond and the reactor’s core. Cooling pumps to circulate the water cooling in the system can be powered by other reactors, sources outside the plant, diesel generators or the emergency cooling systems driven by steam turbines. The use of steam turbines reduces the dependency on emergency generators, but the reactor must be producing steam for the system to work. The significance of cooling in a nuclear reactor stems from the necessity to keep the reactors internal components at normal operating temperatures. These structures are made from zircaloy which is inert at operating temperatures of about 300 degrees Celsius. When these elements are exposed to temperatures beyond 500 degrees Celsius in the presence of steam, an exothermic reaction, which produces hydrogen gas, occurs. This reaction can also lower the melting point of the fuel in the reactor. The emergency generators in the Fukushima I plant were located in the basement of the reactor building. The plans drawn by General Electric positioned the generators at the basement, and despite reservations by the sites engineers TEPCO elected to follow General Electric’s plan. The flooding of the basement and subsequent drowning of the emergency generators initiated the failure of the cooling system in the plant. This failure escalated and caused the failure of the reactors and the release of radioactive substances into the environment. 3. Safety issues relating to the Fukushima nuclear plant prior to the disaster 3.1 Changed layout of the emergency cooling system The initial plans in setting up the reactor included a plan to set up a reactor and the piping systems of two reactors, which were separate from each other. However, these plans were altered by TEPCO and the two piping structures were linked together outside the reactor. These changes to the plans were not reported as required. Following the damage of the other cooling systems the isolation condenser ought to have functioned by condensing the steam to be used for cooling the reactor. The condenser failed to function properly, and it is not clear if the valve in the condenser was open (Ohnishi, 12). 3.2 Falsification of safety records by TEPCO The construction of the Fukushima nuclear plant was subject to falsified records. The scandal led to the departure of the top executives of TEPCO. It also resulted in the disclosure of problems in the plant which had not been revealed. TEPCO admitted to falsifying documents in the plant. Moreover, inspections in the plant did not cover the devices associated with cooling systems such as the diesel generators and water pump motors (Cohen et al. 39). 3.3 Prior failure of the backup generator Prior to the incident, the backup generator for unit 1 had experienced a failure. This failure was as a result of flooding in the basement of the reactor building. The sea water used to cool the reactor was leaking into the building through a corroded pipe. Despite this technicality, TEPCO did not move the generator to higher ground but instead installed doors to prevent water from leaking into the generator room. Consequently, TEPCO admitted that the generator rooms were flooded after the tsunami and its power sources were submerged (Bunn, and Olli 1580). 3.4 Ignored tsunami warning A study by a department set up by TEPCO pointed out an immediate need to safeguard of the station from flooding. The study also indicated the possibility of a tsunami wave breaching the facility. The report was dismissed as being unrealistic, and the predictions were not taken seriously. Other bodies were also concerned about the risk of flooding, but no measures were taken to mitigate the problem. 3.5 Location of the reactor The Fukushima plant is located in Japan which is a high seismic area. This area is more prone to natural disasters including earthquakes and tsunamis. The International Atomic Energy Agency had voiced its concerns regarding the ability of nuclear reactors in Japan to survive seismic activity. The agency warned that a strong earthquake was likely to cause problems for the nuclear reactors in the country. 4. Events resulting in the Fukushima Daiichi nuclear plant disaster No serious damage occurred to the reactors after the earthquake and units 1, 2 and 3 at the plant were shut down as designed, as a response to the earthquake. However, the external power sources were damaged by the earthquake and, as a result; the diesel generators located under the turbines building were used. By default, the cooling of the reactor would have been sustained by bypassing the steam and passing it through the condensers (Kan 12). A while after the earthquake, a tsunami wave, hit the plant followed by other wave moments later. The waves submerged the sea water pumps that pumped water to the main condenser and auxiliary cooling units. The waves also drowned the diesel generators located at the basement of the reactor chamber. This caused a station blackout (Cohen et al. 37). The reactors affected were isolated from their ultimate heat sink. Roads leading to the plant were also obstructed by the tsunami, and this made outside access to the plant impossible. These events put reactors 1, 2 and 3 in an unstable position, and the authorities ordered and subsequently extended an evacuation. There were attempts to restore power and the cooling system to these retractors (Kingston 16). When there was a power failure, which is approximately an hour after three fission reactors were shut down, the reactor cores would continues to produce around 1.5% of its actual thermal power. This is because of the fission product decay. With the lack of heat removal by distribution to a heat exchanger, there was a build up in the reactor pressure vessel. The interaction of the fuel, extremely hot zirconium and steam produced hydrogen. The pressure started to rise in the vessel, and it was directed to the suppression chamber below the chamber. The temperature and pressure in the suppression chamber rose very quickly, and water injection was commenced. The cooling systems gradually failed and required the internal pressure to be relieved by venting into the suppression chamber (Cohen et al. 40). 4.1 Issues in Unit 1 The level of the water inside unit 1 dropped to the top of the fuel after a few hours and gradually reduced to the bottom of the fuel very quickly. The temperature of the bare fuel rose to over 2800°C, and the central part of the unit started to melt and fell into the water at the bottom of the reactor pressure vessel. The containment was eventually vented, and the vented steam was accompanied by aerosols noble gasses and hydrogen. The hydrogen mixed with air and caused a hydrogen explosion which blew off the roof of the unit and ripped off the top part of the building. The core in unit 1 which consisted of the molten fuel and control rods went through the bottom of the reactor pressure vessel and eroded into the concrete below the vessel before solidifying. The earthquake itself did not cause any damage to unit 1 of the plant (Tsubokuraet al. 670). 4.2 Issues in Unit 2 The backup water injector in unit 2 failed, and it took a while before an alternative pump was employed to inject seawater into the reactor pressure vessel. Pressure had to be relieved from the vessel before the generator became functional and this required nitrogen and power. Meanwhile, the water level in the reactor had dropped considerably, and the core was damaged. Much of the fuel in the unit melted and fell into the water at the bottom of the vessel. Pressure was vented from the unit and to avoid a hydrogen explosion experienced in unit 1 a blowout panel was constructed at the top of the unit. A leak of the primary containment occurred, and much of the radiation recorded within the facility appeared to originate from unit 2 (Tsubokuraet al. 670). 4.3 Issues in Unit 3 The, main backup, water injector in unit 3 also failed, and this was followed by the failure of the high pressure system. The water level in the vessel dropped drastically and required venting due to increased pressure. Venting the suppression chamber and containment was successful but the fuel had melted and fallen into the bottom of the reactor pressure vessel. Venting of the suppression chamber was attempted thereafter, but it back flowed, and a large hydrogen explosion blew off the top of the unit as well as the walls and destroyed the top part of the building. The debris from the explosion in unit three was very radioactive (Cohen et al. 43). 4.4 Issues in Unit 4 There was also an explosion at Unit 4 which was defueled at the time of the disaster. The explosion destroyed the top of the unit 4 building and caused further damage to the structure of unit 3. The explosion was actually a hydrogen explosion from unit 3 and had reached unit 4 from a backflow in shared ducts between the two units. The volatile and airborne fission products were carried in the steam and hydrogen, and the hydrogen explosion caused a discharge of these products into the atmosphere (Kingston 16). 5. Release of radioactive substances into the environment The main fission products used as a fuel in the reactors include iodine-131and caesium-137. Caesium-137 has a half life of 30 years and is easily dispersed in cloud while Iodine-131has a half life of 8 days. It produces strong gamma radiation while it decays, is soluble in water and can be taken into the body. The element has a biological half life of around 70 days. These radioactive materials were released from the containment vessels through deliberate venting to reduce pressure, deliberate discharge of water used to cool the reactors into the sea and unintentional or uncontrolled events in the plant. There were concerns about a likely release of radioactive materials, and a 20 km zone around the plant was evacuated. The evacuation later expanded to 30 km around the plant. It was difficult tracking the radiation since all except one radiation monitoring centers on the plant were damaged by the tsunami (Norio et al. 34). Some radioactivity was detected after the explosion in unit 1, and after the explosion in unit three more radiation was detected. The accident at Fukushima led to detectable traces of radioactivity around the globe, but the concentrations were significantly high in Japan. The radioactive materials could not be controlled, and these materials passed to food products and water sources in the country (Norio et al. 34). 6. Liability for the Fukushima nuclear disaster A nuclear compensation system is aimed at protecting victims of nuclear incidents and provides sound development off the operators. Japans damage compensation system is based on the Act on Compensation for Nuclear Damage. In respect to liability the section 3 of the Act provides: “Where nuclear damage is caused as a result of reactor operation etc. during such operation, the nuclear operator who is engaged in the reactor operation etc. On this occasion shall be liable for the damage, except in the case where the damage is caused by a grave natural disaster of an exceptional character or by an insurrection.” The responsible operator shall have unlimited no-fault liability for nuclear damage resulting from its activities or its facilities. The nuclear operator in such case has an obligation to take steps to ensure compensation for damages resulting from nuclear damage. The Act provides for unlimited liability, strict liability, and channeling liability for operators. The Act under the channeling liability provides that where the nuclear damage is as a result of reactor operations full liability rests on the nuclear operator (Onishi 72). 6.1 Assessing TEPCO’S liability Under the Compensation Act, the operator is only exempted from liability if damage occurred as a result of “a grave natural disaster of an exceptional character or by an insurrection.” The main issue in the assessment of TEPCOS liability, therefore, is determining whether the Great East Japan Earthquake and ensuing tsunami can be considered “a grave natural disaster of an exceptional character,” as provided for by section 3 of the Compensation Act (Eri 452). The interpretation of the proviso in clause 3 follows that a grave natural disaster is one of an extraordinary character on a scale that has never occurred in history. The event must be of an extraordinary degree that it is substantially greater than the greatest occurrence recorded. Moreover, the Atomic Energy Commission argues that the natural disaster must have been unforeseeable and must have exceeded the design basis of the affected reactor. Following the Great East Japan Earthquake the functional units, 1, 2 and 3 were shut down automatically as a countermeasure. The earthquake damaged the external power grids, and the plant was left without an external power supply source. The emergency generators located in the basement of the reactor started up. However the generator rooms were flooded by water from the tsunami and the generators broke down. The entire plant was left without power. Although the design basis for tsunami waves was lower than the wave of the disastrous tsunami, TEPCO had made predictions that given an earthquake with magnitude of 8.3 the wave caused would be higher than 15 meters (Kushida 62). Despite these findings, the company did not develop any countermeasures. In this regard, it is imperative that the Great East Japan Earthquake and the tsunami that followed do qualify as ‘’a grave natural disaster of an exceptional character,” since neither was unforeseeable nor exceeding the design basis intended for reactors. Therefore, the exemption clause in section 3 of the Act on Compensation for Nuclear Damage does not apply, and TEPCO is fully liable under the channeling liability (Eri 452). Work cited Bunn, Matthew, and Olli Heinonen. "Preventing the next Fukushima." Science 333.6049 (2011): 1580-1. Cohen, Bernard, et al. "Risk Of Nuclear Power." Health Physics Society, The University of. Eri Osaka. “Corporate liability, government liability, and the Fukushima nuclear disaster.” Pacific Rim law & Policy Journal 21.3 (2012): 433-459. Gusiakov, Viacheslav K. "Fukushima: the myth of safety, the reality of geoscience." Bulletin of the Atomic Scientists 67.5 (2011): 37-46. Kan, Naoto. "Former Japanese PM Naoto Kan on the Fukushima Disaster." Foreign Affairs (2012). Kingston, Jeff, ed. Natural disaster and nuclear crisis in Japan: response and recovery after Japan's 3/11. Abingdon and New York: Routledge, 2012. Kushida, Kenji. "Japan's Fukushima Nuclear Disaster: Narrative, Analysis, Recommendations." (2012). Norio, Okada, et al. "The 2011 eastern Japan great earthquake disaster: Overview and comments." International Journal of Disaster Risk Science 2.1 (2011): 34-42. Ohnishi, Takeo. "The Disaster at Japan's Fukushima-Daiichi Nuclear Power Plant after the March 11, 2011 Earthquake and Tsunami, and the Resulting Spread of Radioisotope Contamination 1." Radiation research 177.1 (2011): 1-14. Onishi, Norimitsu. "‘Safety Myth’Left Japan Ripe for Nuclear Crisis." New York Times (2011). Tsubokura, Masaharu, et al. "Internal radiation exposure after the Fukushima nuclear power plant disaster." JAMA 308.7 (2012): 669-670. Read More