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This written assignment purpose is to examine and analyze of a situation happened in an nuclear power plant disaster. The objective of this assignment is to ensure students use a proper approach in examining each question. There are several scopes covered in the Industrial Studies (EAT 221) during the class lecture. Lecturer had been deliver a message of what students need in order to complete this report. During lecture, many topics were covered especially on how does an organization operates and competes in market. There was also an explanation of how an organization improves their quality management in controlling their nuclear plant during a natural disaster. Suggestion has been made through this report based on what students learnt in class. This case study is to measure how effective the topics covered in class affected to the students thinking. In addition, the case study encourage student to analyze problems occurred in proper ways.
The Great East Japan Earthquake of magnitude 9.0 hit Japan on March 11, 2011 which did a big damage to the region including creating a large tsunami that caused very much more. The earthquake was centered 130 kilometers offshore the city of Sendai (ä»™å°) in Miyagi Prefecture (å®®åŸŽçœŒ) on the eastern coast of Honshu Island¼ˆæœ¬å·ž¼‰. The 15-meter tsunami hit the coastal ports and town resulting millions of buildings lost, over 19,000 of human life died and hundreds of thousands of people needed to be evacuated from their homes.
Fukushima Daiichi Nuclear Power Plant (ç¦å³¶ç¬¬ä¸€åŽŸååŠ›ç™ºé›»æ‰€) which are owned and operated by Tokyo Electrical Power Company (TEPCO) was severely damaged by the earthquake. The resulting tsunami disabled the power supply and cooling of three Fukushima Daiichi reactors causing a nuclear incident. The incident was declared a Level 7 (Severe Accident) by the International Nuclear Event Scale (INES) due to high radioactive releases in the first few days. When the earthquake occurred, it appears that no serious damage was done to the nuclear reactors and the operating units; Unit 1, 2 and 3 were shut down accordingly, as the emergency shut-down feature (SCRAM) designed. At the same time, all six external power sources were lost due to the earthquake damage resulting emergency diesel generators to start up. The seawater pumps for both the main condenser circuits and the auxiliary cooling circuits notably the Residual Heat Removal (RHR) were damaged when the first wave hit, following by the second wave 8 minutes later.
The tsunami also drowned the diesel generators and inundated the electrical switchgear and batteries which lead to station blackout and the reactors were isolated from their ultimate heat sink. Outside access was difficult due to obstructed roads that were damaged by the tsunamis.
This makes those Unit 1, 2 and 3 reactors in a very critical situation which led the authorities to extend the evacuation while engineers were instructed to restore power and cooling the reactors.
The 125-vold DC batteries for Unit 1 and 2 had failed while Unit 3 had battery power for about 30 hours, leaving the engineers without instrument, control and lighting which make the restoration process more difficult to do.
Nuclear Emergency was declared on Friday, 11 March 2011 and at approximately 8.50 pm the Fukushima authorities issued an evacuation order for people within 2 km of the plant. On Saturday 12th March 2011, Japan's Prime Minister extended the evacuation order to 20km within the plant.
3. Fukushima Nuclear Disaster was "man-made"
The independent Investigation Committee on the Accident (ICANPS) was appointed by the Japanese cabinet in early June 2011 to set up investigations on causes of the nuclear accident, The panel consists ten experts, mostly academics and technological advisers. The national Diet later set up Nuclear Accident Independent Investigation Commission (NAIIC) in December 2011. NAIIC reported in July 2012, criticizing the government, the plant operator and the country's national culture. The commission's report concluded that the accident was a "man-made disaster", the result of "collusion between the government, the regulators, and Tokyo Electrical Power Corporation (TEPCO)". It said the "root causes were the organizational and regulatory systems that supported faulty rationales for decisions and actions".
The NAIIC criticized the regulator for the insufficiently maintaining independence from the industry in developing and enforcing safety regulations, the government for inadequate emergency preparedness and management, and TEPCO for its poor governance and lack of safety culture, Fundamental changes across the industry, including the government and regulators, to increase openness, trustworthiness and focus on protecting public health and safety were also called in the report.
The regulator, NISA, gave no instruction to TEPCO to prepare for severe flooding and even told the nuclear operators at Fukushima nuclear power plant that it is not necessary to plan for station blackout even though TEPCO had been aware since 2006 that Fukushima Daiichi could face a station blackout if flooded, as well as the potential loss of ultimate heat sink in the event of a major tsunami. This lack of readiness for station blackout by the regulator, NISA and TEPCO was compounded by a lack of planning and training for severe accident mitigation during the tsunami hit. Plans and procedures for venting and manual operation of emergency cooling were incomplete and their implementation in emergency circumstances proved very difficult as a result. NISA was also was criticized for its "negligence and failure over the years" to prepare for a nuclear accident in terms of public information and evacuation, with previous governments equally culpable. Then TEPCO's difficulty in mitigation was compounded by government interference which undermined NISA.
4. Industrial Process and Operation
Fukushima Daiichi Nuclear Power Plant (ç¦å³¶ç¬¬ä¸€åŽŸååŠ›ç™ºé›»æ‰€) began their operation in 1971. They have six nuclear reactors, which carries the capacity of 4,696 MW. Fukushima Daiichi nuclear power station is located approximately 250 km north of Tokyo in the towns of Futaba and Ohkuma.
The site of the station is approximately 3.5 million square meters and the plants are built on solid bedrock after all soil has been removed. The power plant station was built using reinforced concrete walls that are far thicker than those used in normal buildings. Therefore, if an earthquake of level 5 or greater occurs, the reactor buildings would shake far less than an ordinary building. Seismic detecting devices that were stored in the reactor building are designed to automatically shut the reactor down in an earthquake hit situation.
5. Impact of the Fukushima nuclear disaster
Radiation from Fukushima Daiichi nuclear plant disaster may cause from 15 to 13,000 deaths of humans life and from 24 to 2,500 cases of people getting cancer with mostly in Japan according to Stanford researchers. The estimates have large uncertainty ranges, but are far from previous claims that the radioactive that was released from Fukushima Daiichi nuclear plant would not cause any severe health effects.
The nuclear disaster has highlighted and compounded such pre-existing issues such as falling birth rates, fragmenting of the family unit, and the shrinking of local communities. Now, the daily concerns about the radiation levels, safe food and clean water source have left many young Japanese couples unwilling to take on risky tasks of raising children in a dangerous environment.
During the pre-quake years, there was lack of economic development in local communities where young Japanese move to larger towns and cities to seek higher paid jobs. The consequences of this would be erosion of regional identity where communities which were affected by the earthquake, tsunami and Fukushima Daiichi nuclear disaster more than ever, need their younger generation.
Fukushima Daiichi nuclear disaster forced families to move to further towns and cities where they could secure day to day services which are easier than in their earthquake-stricken communities. The victims would also have to meet financial commitments; this includes repaying mortgages on homes that have been destroyed during the disaster. Survivors have spent on average five months in temporary shelters. Temporary accommodation was allocated in a lottery deemed the fairest way of distributing accommodation. Many have found themselves unable to face this additional upheaval compounding the fragmenting of communities, brought about by the failure of governmental officials to consider keeping people from the same area together. For others, tracing and finding other survivors from their locales has been crucial to ensuring togetherness and stability. To this end, a group of people have joined in putting down a fifty per cent deposit on their temporary accommodation to ensure they have more say in how the buildings were built.
6. Actions taken by TEPCO, government and regulators
At 3.42 pm, when the nuclear plant started to fail, about one hour after shutdown, the reactor cores produced about 1.5% of nominal thermal power. This produced a lot of steam in the reactor pressure vessels housing the cores, and this was released into the dry primary containment (PCV) through safety valves. After the water level dropped, interaction of the fuel's hot zirconium cladding with steam was produced later accompanied with hydrogen.
As pressure started to rise, the suppression chamber under the reactor was filled with directed steam, within the containment, but the internal temperature and pressure rose greatly. Water injection was set, various systems was used for this to provide this and the Emergency Core Cooling System (ECCS). Over 3 days, these systems increasingly failed, so from early Saturday fire pumps were used to inject water in to the reactor pressure vessel (RVP, but for this to work the internal pressures were required to be relieved initially by ventilating into the suppression chamber.
Inside Unit 1, about three hours after the scram, the water level started to drop to the top of the fuel (6 pm) and at the bottom of the fuel an hour and half later (7.30 pm). The exposed fuel rose's temperature rose rapidly to 2800°C so that after a few hours the central part started to melt and by 16 hours after the scram (7 am Saturday) most of it had fallen into the water at the bottom of the RPV. Since then the temperatures of the RVP have decreased steadily.
When the pressure started to rise, venting the containment were attempted, and this was successfully done by 2.30 pm on Saturday when external power and compressed air sources were harnessed. In the absence of power much of the air was back flowed to the service floor at the top of the reactor building even though the venting was designed to be through an external stack, representing a serious failure of this system. The hydrogen accompanied the vented steam, aerosols and noble gases. On Saturday 12th 3.36 pm, after the hydrogen were mixed with air and ignited, hydrogen explosion occurred on the service floor of the building above unit 1 reactor containment, damaging the roof and top part of the building.
In Unit 2, on Monday 14th, steam-driven back-up water injection to inject water system had failed and that occurred before a fire pump started to inject into the RPV with seawater 6 hours before. RPV pressure had to be relieved via the wet well which required power and nitrogen before the fire pump could be started to used. This resulted a delay. Meanwhile the back-up cooling system started to fail later on so the reactor water level dropped rapidly. About 8 pm the core damage started, and much of the fuel then started to melt and probably fell into the water at the bottom of the RPV. On 13th and 15th, pressure was vented; meanwhile to avoid a repetition of unit 1 hydrogen explosion, the blowout near the top of the building was opened. The pressure suppression chamber under the actual reactor seemed to rupture early on 15th; this is possibly due to hydrogen explosion. Then the drywell containment pressure started to dropped. Analysis that was conducted later suggested that the PCV developed a leak on Tuesday 15th.
In Unit 3, on Saturday 12th 11 am, main back-up water injection system started to fail and early on Sunday 13th, water levels dropped immediately after water injection system failed. Venting steam into the wet well was used so the RPV's pressure was reduced successfully, allowing fire pump to be used to inject seawater. Venting the suppression chamber and containment was successful later on. About 9 am, the core damage started and on Sunday 13th, all of the fuel melted was retained on the core support plate or and fell into the water at the bottom of the RPV.
The venting of the PCV was repeated on 14th, and this allowed it to back flow to the service floor of the building, so that a huge hydrogen explosion above Unit 3 nuclear reactor containment blew off the roof and walls, while demolished the top part of the building on 11 am. A lot of debris was created during the explosion, making the ground near Unit 3 very radioactive.
7. Proposed actions needed at TEPCO nuclear plant
Safety measurements at nuclear power plant should be a priority so that the community would be protected from any preventable disaster and hazardous substances. There are a few actions that could be taken by Tokyo Electrical Power Co (TEPCO) to make sure their nuclear plants are kept safe every time.
Defense in Depth
Measures to prevent unexpected events
All of their nuclear plants should be designed to provide margins of safety capable of withstanding natural disasters.
TEPCO should have a very strict quality control at entire stage, from design to construction to operation.
In addition to regular strict inspections every year, interlock and fail-safe systems are incorporated at every turn to prevent wrong operations or actions.\
Measures to prevent escalation of unexpected events
TEPCO should install detection devices in nuclear plant to detect abnormalities immediately.
TEPCO should install special equipment that automatically and safely shuts the reactor down during erroneous events.
In extreme events or an accident
TEPCO should install Emergency Core Cooling System (ECCS).
TEPCO should use airtight structure of the primary containment vessel and the nuclear reactor building.
Reform from top man management
TEPCO should set up problem-oriented mindset so that they could learn from other divisions, industries, and successful oversea organizations.
TEPCO should develop their technical capability to see the overall system.
TEPCO should develop their capabilities on hoe to work and propose improvements on their own without depending on external organizations.