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62-707: All of the electric utilities in the Eastern Interconnection are electrically tied together during normal system conditions and operate at a synchronized frequency at an average of 60 Hz. The Eastern Interconnection reaches from Central Canada eastward to the Atlantic coast (excluding Quebec ), south to Florida , and back to the western Great Plains (excluding most of Texas ). Interconnections can be tied to each other via high-voltage direct current power transmission lines ( DC ties ), or with variable-frequency transformers (VFTs), which permit

124-450: A Mark II type (over/under) containment structure. Unit 1 is a 460 MWe boiling water reactor ( BWR-3 ) constructed in July 1967. It commenced commercial electrical production on March 26, 1971, and was initially scheduled for shutdown in early 2011. In February 2011, Japanese regulators granted an extension of ten years for the continued operation of the reactor. It was damaged during

186-568: A controlled flow of energy while also functionally isolating the independent AC frequencies of each side. Each of the interconnects in North America is synchronized at a nominal 60 Hz, while those of Europe run at 50 Hz. The benefits of synchronous zones include pooling of generation, resulting in lower generation costs; pooling of load, resulting in significant equalizing effects; common provisioning of reserves, resulting in cheaper primary and secondary reserve power costs; opening of

248-683: A controlled flow of energy while also functionally isolating the independent AC frequencies of each side. The Eastern Interconnection is tied to the Western Interconnection with six DC ties, to the Texas Interconnection with two DC ties, and to the Quebec Interconnection with four DC ties and a VFT. In 2016, National Renewable Energy Laboratory simulated a year with 30% renewable energy ( wind and solar power ) in 5-minute intervals. Results show

310-411: A grid to be able to provide sufficient current to keep the voltage and frequency reasonably stable until circuit breakers can resolve the fault. Many traditional generator systems had wires which could be overloaded for very short periods without damage, but inverters are not as able to deliver multiple times their rated load. The short circuit ratio can be calculated for each point on the grid, and if it

372-599: A possible uncovering of the Spent fuel pools in Units 1, 3 and 4. Units 5 & 6 were reported on March 19, by the station-wide alert log updates of the IAEA , to have gradually rising spent fuel pool temperatures as they had likewise lost offsite power, but onsite power provided by Unit 6's two diesel generators that had not been flooded, were configured to do double-duty and cool both Unit 5 and 6's spent fuel pools "and cores". As

434-440: A precautionary measure, vents in the roofs of these two units were also made to prevent the possibility of hydrogen gas pressurization and then ignition. Radiation releases from Units 1–4 forced the evacuation of 83,000 residents from towns around the plant. The triple meltdown also caused concerns about contamination of food and water supplies, including the 2011 rice harvest, and also the health effects of radiation on workers at

496-422: A row with Serbia , leading to the phase in the whole synchronous grid of Continental Europe lagging behind what it should have been. The frequency dropped to 49.996 Hz. Over time, this caused synchronous electric clocks to become six minutes slow until the disagreement was resolved. (2007) (2018) (2020) (2016) (2022) A partial table of some of the larger interconnections. Historically, on

558-567: A small sample of melted radioactive fuel from a damaged reactor. The sample will help improve future decommissioning strategies, though doubts persist about the long-term cleanup timeline. A glitch halted Telesco, the robot attempting to retrieve the sample, further delaying the mission. Concerns also remain over the impact on marine life as radioactive water is being released into the Pacific Ocean, despite government assurances that it meets safety standards. In November 2024,TEPCO has moved

620-528: A stable grid with some changes in operation. The North American Electric Reliability Corporation (NERC) reported in 2008 the following actual and projected consumption for the regions of the Eastern Interconnection (all figures in gigawatts): Wide area synchronous grid A wide area synchronous grid (also called an " interconnection " in North America ) is a three-phase electric power grid that has regional scale or greater that operates at

682-586: A synchronized utility frequency and is electrically tied together during normal system conditions. Also known as synchronous zones , the most powerful is the Northern Chinese State Grid with 1,700 gigawatts (GW) of generation capacity, while the widest region served is that of the IPS/UPS system serving most countries of the former Soviet Union. Synchronous grids with ample capacity facilitate electricity trading across wide areas. In

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744-562: A synchronous grid is stored energy that a grid has available which can provide extra power for up to a few seconds to maintain the grid frequency. Historically, this was provided only by the angular momentum of the generators, and gave the control circuits time to adjust their output to variations in loads, and sudden generator or distribution failures. Inverters connected to HVDC usually have no inertia, but wind power can provide inertia, and solar and battery systems can provide synthetic inertia . In short circuit situations, it's important for

806-464: A synchronous grid, all the generators naturally lock together electrically and run at the same frequency , and stay very nearly in phase with each other. For rotating generators, a local governor regulates the driving torque and helps maintain a more or less constant speed as loading changes. Droop speed control ensures that multiple parallel generators share load changes in proportion to their rating. Generation and consumption must be balanced across

868-475: A synchronous grid, or between them. The Tres Amigas SuperStation aims to enable energy transfers and trading between the Eastern Interconnection and Western Interconnection using 30GW HVDC Interconnectors . Fukushima Daiichi The Fukushima Daiichi Nuclear Power Plant ( 福島第一原子力発電所 , Fukushima Daiichi Genshiryoku Hatsudensho , Fukushima number 1 nuclear power plant)

930-670: A time for safety checks due to the TEPCO data falsification scandal . On February 28, 2011, TEPCO submitted a report to the Japanese Nuclear and Industrial Safety Agency admitting that the company had previously submitted fake inspection and repair reports. The report revealed that TEPCO failed to inspect more than 30 technical components of the six reactors, including power boards for the reactor's temperature control valves, as well as components of cooling systems such as water pump motors and emergency power diesel generators. In 2008,

992-517: Is a disabled nuclear power plant located on a 3.5-square-kilometre (860-acre) site in the towns of Ōkuma and Futaba in Fukushima Prefecture , Japan. The plant suffered major damage from the magnitude 9.1 earthquake and tsunami that hit Japan on March 11, 2011. The chain of events caused radiation leaks and permanently damaged several of its reactors, making them impossible to restart. The working reactors were not restarted after

1054-686: Is estimated at $ 71 billion. TEPCO will shoulder $ 143 billion of decommissioning and decontamination, while the Ministry of Finance of Japan will provide $ 17 billion. Other power companies will also contribute to the cost. On September 26, 2020, Prime Minister Yoshihide Suga visited the Daiichi Nuclear Power Plant to show that his cabinet prioritized the reconstruction of areas that were affected by natural and nuclear disasters. The three reactors host 880 tonnes of highly radioactive melted nuclear fuel. As of 2024–13 years after

1116-506: Is found to be too low, for steps to be taken to increase it to be above 1, which is considered stable. For timekeeping purposes, over the course of a day the operating frequency will be varied so as to balance out deviations and to prevent line-operated clocks from gaining or losing significant time by ensuring there are 4.32 million on 50 Hz, and 5.184 million cycles on 60 Hz systems each day. This can, rarely, lead to problems. In 2018 Kosovo used more power than it generated due to

1178-461: Is output ( droop speed control ). When the grid is lightly loaded the grid frequency runs above the nominal frequency, and this is taken as an indication by Automatic Generation Control systems across the network that generators should reduce their output. In addition, there's often central control, which can change the parameters of the AGC systems over timescales of a minute or longer to further adjust

1240-423: The 2011 Tōhoku earthquake and tsunami . Unit 1 was designed for a peak ground acceleration of 0.18  g (1.74 m/s ) and a response spectrum based on the 1952 Kern County earthquake , but rated for 0.498 g. The design basis for Units 3 and 6 were 0.45 g (4.41 m/s ) and 0.46 g (4.48 m/s ) respectively. All units were inspected after the 1978 Miyagi earthquake when the ground acceleration

1302-636: The North American power transmission grid the Eastern and Western Interconnections were directly connected, and was at the time largest synchronous grid in the world, but this was found to be unstable, and they are now only DC interconnected. Interconnectors such as High-voltage direct current lines, solid-state transformers or variable-frequency transformers can be used to connect two alternating current interconnection networks which are not necessarily synchronized with each other. This provides

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1364-523: The moment magnitude scale occurred at 14:46 Japan Standard Time (JST) off the northeast coast of Japan, one of the most powerful earthquakes in history. Units 4, 5 and 6 had been "shut down" prior to the earthquake for planned maintenance. The remaining reactors were shut down/ SCRAMed automatically after the earthquake, and the remaining decay heat of the fuel was being cooled with power from emergency generators. The subsequent destructive tsunami with waves of up to 14 metres (46 ft) that over-topped

1426-596: The ENTSO-E in 2008, over 350,000 megawatt hours were sold per day on the European Energy Exchange (EEX). Neighbouring interconnections with the same frequency and standards can be synchronized and directly connected to form a larger interconnection, or they may share power without synchronization via high-voltage direct current power transmission lines (DC ties), solid-state transformers or variable-frequency transformers (VFTs), which permit

1488-535: The Fukushima Daiichi nuclear power plant and to cancel plans to build units 7 and 8. It refused however to make a decision regarding units 5 and 6 of the station or units 1 to 4 of the Fukushima Daini nuclear power station until a detailed investigation is made. In December 2013 TEPCO decided to decommission the undamaged units 5 and 6; they may be used to test remote clean-up methods before use on

1550-596: The Fukushima Daini plant by the Tomioka Line (富岡線). Its major connection to the north is the Iwaki Line (いわき幹線), which is owned by Tohoku Electric Power . It has two connections to the south-west that connect it to the Shin-Iwaki substation (新いわき). The plant reactors came online one at a time beginning in 1970 and the last in 1979. From the end of 2002 through 2005, the reactors were among those shut down for

1612-609: The Fukushima disaster and the Chernobyl disaster worldwide the only Level 7 events up to date. Japanese wheelchair basketball player Akira Toyoshima revealed that he was working as an accountant at the Fukushima Daiichi Nuclear Power Plant when the 2011 Tōhoku earthquake and tsunami struck Japan and the tsunami eventually claimed the lives of thousands of people. Toyoshima insisted that he

1674-562: The IAEA warned Japan that the Fukushima plant was built using outdated safety guidelines, and could be a "serious problem" during a large earthquake. The warning led to the building of an emergency response center in 2010, used during the response to the 2011 nuclear accident. On April 5, 2011, TEPCO vice president Takashi Fujimoto announced that the company was canceling plans to build Reactors No. 7 and 8. On May 20 TEPCO's board of directors' officially voted to decommission Units 1 through 4 of

1736-491: The Japanese government approved the discharge of radioactive water , which has been treated to remove radionuclides other than tritium , into the Pacific Ocean over the course of 30 years. The reactors for Units 1, 2, and 6 were supplied by General Electric , those for Units 3 and 5 by Toshiba , and Unit 4 by Hitachi . All six reactors were designed by General Electric. Architectural design for General Electric's units

1798-454: The accident—attempts to remove highly radioactive material from the damaged reactor were halted. Tesco attempted to remove 3 grams (0.1 ounce) from an estimated 880 tons of lethally radioactive molten fuel. This sample will provide critical data for the development of future decommissioning methods, as well as the necessary technology and robots, according to experts. On 11 September 2024, a robotic mission at Fukushima Daiichi restarted to collect

1860-414: The benefit of interconnection without the need to synchronize an even wider area. For example, compare the wide area synchronous grid map of Europe (in the introduction) with the map of HVDC lines (here to the right). Solid state transformers have larger losses than conventional transformers, but DC lines lack reactive impedance and overall HVDC lines have lower losses sending power over long distances within

1922-461: The creation of a structure to develop the technologies and processes necessary to dismantle the four reactors damaged in the Fukushima accident. To reduce the flow of contaminated water into the Pacific Ocean, TEPCO spent ¥34.5 billion (approx. $ 324 million) to build a 1.5 kilometer-long underground wall of frozen soil around the plant, constructed by Kajima Corporation. 1,500 one-hundred-foot long (thirty-metre), supercooled pipes were inserted into

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1984-510: The damaged reactors. In 1990, the U.S. Nuclear Regulatory Commission (NRC) ranked the failure of the emergency electricity generators and subsequent failure of the cooling systems of plants in seismically very active regions one of the most likely risks. The Japanese Nuclear and Industrial Safety Agency (NISA) cited this report in 2004. According to Jun Tateno, a former NISA scientist, TEPCO did not react to these warnings and did not respond with any measures. Filmmaker Adam Curtis mentioned

2046-431: The entire grid because energy is consumed as it is produced. Energy is stored in the immediate short term by the rotational kinetic energy of the generators. Small deviations from the nominal system frequency are very important in regulating individual generators and assessing the equilibrium of the grid as a whole. When the grid is heavily loaded, the frequency slows, and governors adjust their generators so that more power

2108-529: The events. First commissioned in 1971, the plant consists of six boiling water reactors . These light water reactors drove electrical generators with a combined power of 4.7 GWe, making Fukushima Daiichi one of the 15 largest nuclear power stations in the world . Fukushima was the first nuclear plant to be designed, constructed, and run in conjunction with General Electric and Tokyo Electric Power Company (TEPCO). The sister nuclear plant Fukushima Daini ( "number two" ), 12 km (7.5 mi) to

2170-590: The fact that they were still included in the supply plan for 2011, released in March 2011, after the accidents. The company stated that the plan had been drafted before the earthquake. The Fukushima Daiichi plant is connected to the power grid by four lines, the 500 kV Futaba Line (双葉線), the two 275 kV Ōkuma Lines (大熊線) and the 66 kV Yonomori Line (夜の森線) to the Shin-Fukushima (New Fukushima) substation. The Shin-Fukushima substation also connects to

2232-405: The generators and batteries in that location, but mid-level engineers working on the construction of the plant were concerned that this made the backup power systems vulnerable to flooding. TEPCO elected to strictly follow General Electric's design in the construction of the reactors. The plant is on a bluff which was originally 35 meters above sea level. During construction, however, TEPCO lowered

2294-434: The ground in order to freeze the surrounding groundwater and soil. The wall ultimately failed to significantly decrease the groundwater flowing into the site. The cost of decommissioning and decontamination of the Fukushima Daiichi nuclear power plant has been estimated at $ 195 billion, which includes compensation payouts to victims of the disaster. The amount also includes decommissioning of Fukushima Daiichi reactors, which

2356-403: The height of the bluff by 25 meters. One reason for lowering the bluff was to allow the base of the reactors to be constructed on solid bedrock in order to mitigate the threat posed by earthquakes. Another reason was the lowered height would keep the running costs of the seawater pumps low. TEPCO's analysis of the tsunami risk when planning the site's construction determined that the lower elevation

2418-450: The incident, as TEPCO had covered it up; interviews of two former workers in 2007 led to its discovery by TEPCO management. A manual shutdown was initiated during the middle of a start-up operation. The cause was a high pressure alarm that was caused by the shutting of a turbine bypass valve. The reactor was at 12% of full power when the alarm occurred at 4:03 am (local time) due to a pressure increase to 1,030 psi (7,100 kPa), exceeding

2480-409: The market, resulting in possibility of long term contracts and short term power exchanges; and mutual assistance in the event of disturbances. One disadvantage of a wide-area synchronous grid is that problems in one part can have repercussions across the whole grid. Wide area synchronous networks improve reliability and permit the pooling of resources. Also, they can level out the load, which reduces

2542-516: The network to permit greater control during off-nominal events. As was discovered in the California electricity crisis , there can be strong incentives among some market traders to create deliberate congestion and poor management of generation capacity on an interconnection network to inflate prices. Increasing transmission capacity and expanding the market by uniting with neighbouring synchronous networks make such manipulations more difficult. In

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2604-555: The ocean – contains the newer units 5 and 6, respectively, the positions from left to right. A set of seawalls protrude into the ocean, with the water intake in the middle and water discharge outlets on either side. Units 7 and 8 were planned to start construction in April 2012 and 2013 and to come into operation in October 2016 and 2017 respectively. The project was formally canceled by TEPCO in April 2011 after local authorities questioned

2666-506: The plant, and TEPCO announced plans to filter radioactive particles and discharge purified water. In August, Japanese officials said highly radioactive water was leaking from Fukushima Daiichi into the Pacific Ocean at a rate of 300 tons (about 272 metric tons) per day. Japanese Prime Minister Shinzo Abe ordered government officials to step in. By September 2019, one million tons of contaminated cooling water had been collected in tall steel tanks. Large filtration systems were used to clean

2728-650: The plant. Scientists estimate that the accident released 18 quadrillion becquerels of caesium-137 into the Pacific Ocean, contaminating 150 square miles (390 km ) of the ocean floor. The events at units 1, 2 and 3 have been rated at Level 5 each on the International Nuclear Event Scale , and those at unit 4 as Level 3 (Serious Incident) events, with the overall plant rating at Level 7 (major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures), making

2790-470: The plant; the releases continue to this day. On April 20, 2011, the Japanese authorities declared the 20 km (12 mi) evacuation zone a no-go area which may only be entered under government supervision. In November 2011, the first journalists were allowed to visit the plant. They described a scene of devastation in which three of the reactor buildings were destroyed; the grounds were covered with mangled trucks, crumpled water tanks and other debris left by

2852-403: The regional network flows and the operating frequency of the grid. Where neighbouring grids, operating at different frequencies, need to be interconnected, a frequency converter is required. HVDC Interconnectors , solid-state transformers or variable-frequency transformers links can connect two grids that operate at different frequencies or that are not maintaining synchronism. Inertia in

2914-405: The regulatory limit of 1,002 psi (6,910 kPa). The reactor was reduced to 0% power, which exceeded the 5% threshold that requires event reporting, and pressure dropped back under the regulatory limit at 4:25 am. Later, at 8:49 am the control blades were completely inserted, constituting a manual reactor shutdown. An inspection then confirmed that one of the 8 bypass valves had closed and that

2976-490: The required generating capacity, allow more environmentally-friendly power to be employed; allow more diverse power generation schemes and permit economies of scale. Wide area synchronous networks cannot be formed if the two networks to be linked are running at different frequencies or have significantly different standards. For example, in Japan, for historical reasons, the northern part of the country operates on 50 Hz, but

3038-460: The risks of the type of boiling water reactors cooling systems such as those in Fukushima I, and claimed the risks were known since 1971 in a series of documentaries in the BBC in 1992 and advised that PWR type reactors should have been used. Tokyo Electric Power Company (TEPCO) operated the station and was warned their seawall was insufficient to withstand a powerful tsunami, but did not increase

3100-402: The seawall height in response. The Onagawa Nuclear Power Plant , operated by Tohoku Electric Power , ran closer to the epicenter of the earthquake, but had much more robust seawalls of greater height and avoided severe accident. Fuel rods fell in reactor No. 3, causing a nuclear reaction. It took about seven and a half hours to place the rods back into proper positions. There was no record of

3162-477: The south, is also run by TEPCO. It also suffered serious damage during the tsunami, at the seawater intakes of all four units, but was successfully shut down and brought to a safe state. See the timeline of the Fukushima II nuclear accidents . The March 2011 disaster disabled the reactor cooling systems, leading to releases of radioactivity and triggering a 30 km (19 mi) evacuation zone surrounding

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3224-468: The southern part uses 60 Hz. That makes it impossible to form a single synchronous network, which was problematic when the Fukushima Daiichi plant melted down. Also, even when the networks have compatible standards, failure modes can be problematic. Phase and current limitations can be reached, which can cause widespread outages. The issues are sometimes solved by adding HVDC links within

3286-400: The station, which had seawalls, disabled emergency generators required to cool the reactors and spent fuel pools in Units 1–5. Over the following three weeks there was evidence of partial nuclear meltdowns in units 1, 2 and 3: visible explosions, suspected to be caused by hydrogen gas, in units 1 and 3; a suspected explosion in unit 2, that may have damaged the primary containment vessel; and

3348-471: The tsunami; and radioactive levels were so high that visitors were only allowed to stay for a few hours. In April 2012, Units 1–4 were shut down. Units 2–4 were shut down on April 19, while Unit 1 was the last of these four units to be shut down on April 20 at midnight. In December 2013 TEPCO decided none of the undamaged units will reopen. Units 5 and 6 were shut down later in January 2014. In April 2021,

3410-436: The valve had a bad driving fluid connection. The reactor had been starting up following its 25th regular inspection, which had begun on October 18, 2008. Unit 3 had problems with over-insertion of control blades during outage. Repair work was being done on equipment that regulates the driving pressure for the control blades, and when a valve was opened at 2:23 pm a control blade drift alarm went off. On later inspection, it

3472-461: The water of its radioactive contaminants, but could not remove the estimated 14 grams of tritium , a radioactive isotope of hydrogen (Hydrogen-3) bonded into water molecules. TEPCO estimated the immediate site would run out of space by 2022, and planned to solve this problem by releasing the radioactive water into the Pacific Ocean . This proposed measure was criticised by environmental groups and several Asian governments, who claimed that storage area

3534-468: Was 0.125 g (1.22 m/s ) for 30 seconds, but no damage to the critical parts of the reactor was discovered. The design basis for tsunamis was 5.7 metres (18 ft 8 in). The reactor's emergency diesel generators and DC batteries, crucial components in helping keep the reactors cool in the event of a power loss, were located in the basements of the reactor turbine buildings. The reactor design plans provided by General Electric specified placing

3596-532: Was available in the exclusion zone around the reactor. Japan's government approved the release, beginning in 2023, over the course of an estimated 40 years. A note in the 2020 Tokyo Olympic Games opening speech referenced the disaster and how Japan has recovered from the disaster. The reactors will take 30–40 years to be decommissioned. On August 1, 2013, the Japanese Industry Minister Toshimitsu Motegi approved

3658-447: Was done by Ebasco . All construction was done by Kajima . Since September 2010, Unit 3 has been fueled by a small fraction (6%) of plutonium containing mixed-oxide (MOX) fuel , rather than the low enriched uranium (LEU) used in the other reactors. Units 1–5 were built with Mark I type (light bulb torus) containment structures . The Mark I containment structure was slightly increased in volume by Japanese engineers. Unit 6 has

3720-447: Was focused on organizing a set of important and urgent documents in the main office building of the Fukushima Daiichi Nuclear Power Plant as a member of the accounting team. In April 2013, TEPCO publicly admitted radionuclide contaminated water may have leaked from the storage units, possibly contaminating the soil and water nearby. The leak was controlled and stored in containment tanks. Contaminated water continued to accumulate at

3782-408: Was found that several of the rods had been unintentionally inserted. Unit 5 had an automatic SCRAM while an operator was conducting an adjustment to the control blade insertion pattern. The SCRAM was caused by a reactor low water level alarm. The turbine tripped along with the reactor and there was no radiation injury to workers. On March 11, 2011, an earthquake categorized as 9.1 M W on

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3844-442: Was safe because the sea wall would provide adequate protection for the maximum tsunami assumed by the design basis. However, the lower site elevation did increase the vulnerability for a tsunami larger than anticipated in design. The Fukushima Daiichi site is divided into two reactor groups, the leftmost group – when viewing from the ocean – contains units 4, 3, 2 and 1 going from left to right. The rightmost group – when viewing from

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