129-571: The Kashiwazaki-Kariwa Nuclear Power Plant ( 柏崎刈羽原子力発電所 , Kashiwazaki-Kariwa genshiryoku-hatsudensho , Kashiwazaki-Kariwa NPP) is a large, modern (housing the world's first advanced boiling water reactor or ABWR) nuclear power plant on a 4.2-square-kilometer (1,000-acre) site. The campus spans the towns of Kashiwazaki and Kariwa in Niigata Prefecture , Japan , on the coast of the Sea of Japan , where it gets cooling water. The plant
258-515: A 2021 survey by Niigata Nippo , just over half of Niigata prefecture residents oppose a nuclear restart. In October 2022, Japanese Prime Minister Kishida Fumio unveiled a new strategy for Japans nuclear power plants regarding new construction projects and license extensions. Included in this strategy, is a plan to restart units at the Kashiwazaki-Kariwa Nuclear Power Plant by the summer months of 2023. Although,
387-503: A LOC incident. However, when a team was sent to investigate the status of the RCIC of unit 2 the following morning (02:55), they confirmed that the RCIC was operating with the PCV pressure well below design limits. Based on this information, efforts were focused on unit 1. However, the condensate storage tank from which the RCIC draws water was nearly depleted by the early morning, and so the RCIC
516-445: A causal relationship between radiation and the cancer. Six other persons have been reported as having developed cancer or leukemia . Two workers were hospitalized because of radiation burns , and several other people sustained physical injuries as a consequence of the accident. Criticisms have been made about the public perception of radiological hazards resulting from accidents and the implementation of evacuations (similar to
645-403: A closed coolant loop from the pressure vessel with a heat exchanger in a dedicated condenser tank. Steam would be forced into the heat exchanger by the reactor pressure, and the condensed coolant would be fed back into the vessel by gravity. Each reactor was initially designed to be equipped with two redundant ICs which were each capable of cooling the reactor for at least 8 hours (at which point,
774-405: A closed-loop system which draws coolant from the suppression chamber (SC) instead of the storage tank, should the storage tank be depleted. Although this system could function autonomously without an external energy source (besides the steam from the reactor), direct current (DC) was needed to remotely control it and receive parameters and indications and alternating current (AC) was required to power
903-409: A height of 15 m (49.2 ft) above sea level and spanning more than 800 m (2,624 ft) in length for units 1–4, and more than 500 m (1,640 ft) for units 5–7 by June 2013. The height of a potential tsunami was assumed to be 3.3 m. Also, plans were made to rebuild the radioactive overflow storage pool to be completed by September 2012. On 10 November 2011, TEPCO announced
1032-751: A heightened downtime and show a lifetime operating factor under 50%. A number of design variants have been considered, with power outputs varying from 600 to 1800 MWe. The most developed design variant is the ABWR-II, started in 1991, an enlarged 1718 MWe ABWR, intended to make nuclear power generation more competitive in the late 2010s. None of these designs have been deployed. The new designs hoped to achieve 20% reductions in operating costs, 30% reduction in capital costs, and tight planned construction schedule of 30 months. The design would allow for more flexibility in choices of nuclear fuels. Fukushima Daiichi nuclear disaster The Fukushima nuclear accident
1161-491: A host of other factors). TEPCO's president maintained that fears of a leak of radioactive material were unfounded (since the amount leaked into the ocean was a billionth of the legal limit), but many international reporters expressed distrust of the company that has a history of cover-up controversies. The IAEA's Mohamed ElBaradei encouraged full transparency throughout the investigation of the accident so that lessons learned could be applied to nuclear plants elsewhere. News of
1290-426: A nuclear power plant. This shook the plant beyond design basis and initiated an extended shutdown for inspection, which indicated that greater earthquake-proofing was needed before the operation could be resumed. The plant was completely shut down for 21 months following the earthquake. Unit 7 was restarted after seismic upgrades on 19 May 2009, followed later by units 1, 5, and 6. (Units 2, 3, and 4 were not restarted by
1419-601: A power shortage during the summer months. Trade minister Akira Amari requested that business users cut electricity use, and in August TEPCO was forced to reduce electricity supplies for industrial uses, the first time it had to resort to such measures in 17 years. Reports of the leak caused thousands of cancellations at resorts and hotels along the Sea of Japan coast, even as far as Murakami, Niigata (140 km northeast) and Sado Island . Inn owners have said that rumors have been more damaging than direct effects of
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#17327803077321548-537: A process which typically takes about two weeks. Operation of reactor 7 would still require completion of additional inspections and would require the approval of the Niigate Prefecture Governor. It's been reported that Reactor 7 is scheduled to restart operation in October of 2024 "under a base-case scenario". Advanced boiling water reactor The advanced boiling water reactor ( ABWR )
1677-508: A survey for signs of past tsunamis in this area. With drills, soil samples were to be taken of sediment layers dating from the year 1600 back to 7000 years ago, at nine locations around the plant at the coast of central Japan. This survey, the first that TEPCO ever conducted on this subject, did start on 15 November 2011, and was planned to be completed in April 2012, and was done to examine the possibility of higher tsunamis than had been expected at
1806-438: A widespread issue throughout the company's culture. TEPCO is planning on moving nearly 40% of their nuclear division employees to Niigata Prefecture in preparation of its plans to restart Reactor 7 and begin rebuilding trust in the citizens, but the future of Kashiwazaki-Kariwa is still uncertain. As of 26 May 2022, the local government has yet to move forward with approval for TEPCO to set forth their plans to restart. According to
1935-443: Is a Generation III boiling water reactor . The ABWR is currently offered by GE Hitachi Nuclear Energy (GEH) and Toshiba . The ABWR generates electrical power by using steam to power a turbine connected to a generator; the steam is boiled from water using heat generated by fission reactions within nuclear fuel. Kashiwazaki-Kariwa unit 6 is considered the first Generation III reactor in the world. Boiling water reactors (BWRs) are
2064-892: Is licensed to operate in Japan, the United States and Taiwan, although most of the construction projects have been halted or shelved. As of December 2006 , four ABWRs were in operation in Japan: Kashiwazaki-Kariwa units 6 and 7, which opened in 1996 and 1997, Hamaoka unit 5, opened 2004 having started construction in 2000, and Shika 2 commenced commercial operations on March 15, 2006. Another two partially constructed reactors are in Lungmen in Taiwan , and one more ( Shimane Nuclear Power Plant 3) in Japan. Work on Lungmen halted in 2014. Work on Shimane halted after
2193-466: Is owned and operated by Tokyo Electric Power Company (TEPCO), and it is the largest nuclear generating station in the world by net electrical power rating. On 16 July 2007, the Chūetsu offshore earthquake took place, with its epicenter located only 19 km (12 mi) from the plant. The earthquake registered M w 6.6, ranking it among the strongest earthquakes to occur in the immediate range of
2322-543: Is that it greatly reduces the flow capacity required of the ECCS. The first reactors to use internal recirculation pumps were designed by ASEA-Atom (now Westinghouse Electric Company by way of mergers and buyouts, which was owned by Toshiba ) and built in Sweden . These plants have operated very successfully for many years. The internal pumps reduce the required pumping power for the same flow to about half that required with
2451-737: The Nuclear and Industrial Safety Agency (NISA) announced that it would allow inspectors from the United Nations to review the damage. A team from the IAEA carried out a four-day inspection, as investigations by Japan's Nuclear and Industrial Safety Agency (NISA), Nuclear Safety Commission (NSC) and the Tokyo Electric Power Company (TEPCO) continued. The team of the IAEA confirmed that the plant had "shut down safely" and that "damage appears less than expected." On 19 August,
2580-476: The disposal of treated wastewater once used to cool the reactor , resulting in numerous protests in neighboring countries. The Fukushima Daiichi Nuclear Power Plant consisted of six General Electric (GE) light water boiling water reactors (BWRs). Unit 1 was a GE type 3 BWR. Units 2–5 were type 4. Unit 6 was a type 5. At the time of the Tōhoku earthquake on 11 March 2011 , units 1–3 were operating. However,
2709-456: The reactor pressure vessel (RPV) and embedded itself into the concrete at the base of the PCV. Although at the time it was difficult to determine how far the fuel had eroded and diffused into the concrete, it was estimated that the fuel remained within the PCV. Computer simulations, from 2013, suggest "the melted fuel in Unit 1, whose core damage was the most extensive, has breached the bottom of
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#17327803077322838-500: The spent fuel pools of all units still required cooling. Many of the internal components and fuel assembly cladding are made from a zirconium alloy (Zircaloy) for its low neutron cross section . At normal operating temperatures (~300 °C (572 °F)), it is inert. However, above 1,200 °C (2,190 °F), Zircaloy can be oxidized by steam to form hydrogen gas or by uranium dioxide to form uranium metal . Both of these reactions are exothermic . In combination with
2967-488: The "unexpectedly large ground motions" were now well understood and could be protected against, and further confirming the safe performance of the plant during the quake. Initially, it was thought that some water (estimated to be about 1.5 L) from the spent fuel pool leaked into the Sea of Japan as a result of the quake. Later, more detailed reports confirmed a number of releases, though most of them were far less active than common natural radiation sources. According to
3096-492: The 13 EDGs, 10 were water-cooled and placed in the basements about 7–8 m below the ground level. The coolant water for the EDGs was carried by several seawater pumps placed on the shoreline which also provide water for the main condenser. These components were unhoused and only protected by the seawall. The other three EDGs were air-cooled and were connected to units 2, 4, and 6. The air-cooled EDGs for units 2 and 4 were placed on
3225-639: The 2011 earthquake On June 19, 2006 NRG Energy filed a Letter Of Intent with the Nuclear Regulatory Commission to build two 1358 MWe ABWRs at the South Texas Project site. On September 25, 2007, NRG Energy and CPS Energy submitted a Construction and Operations License (COL) request for these plants with the NRC. NRG Energy is a merchant generator and CPS Energy is the nation's largest municipally owned utility. The COL
3354-573: The 20th. Unit 6 was not operating, and its decay heat was low. All but one EDG was disabled by the tsunami, allowing unit 6 to retain AC-powered safety functions throughout the incident. However, because the RHR was damaged, workers activated the make-up water condensate system to maintain the reactor water level until the RHR was restored on the 20th. Cold shutdown was achieved on the 20th, less than an hour after unit 5. On 21 March, temperatures in
3483-554: The ABWR are offered by GE-Hitachi, Hitachi-GE, and Toshiba. In 1997 the GE-Hitachi U.S. ABWR design was certified as a final design in final form by the U.S. Nuclear Regulatory Commission , meaning that its performance, efficiency, output, and safety have already been verified, making it bureaucratically easier to build it rather than a non-certified design. In 2013, following its purchase of Horizon Nuclear Power , Hitachi began
3612-498: The BWRs of AEG (later Kraftwerk Union AG, now AREVA ). Older BWRs use a hydraulic locking piston system to move the control rods in six-inch increments. The electric fine motion control rod design greatly enhances positive actual control rod position and similarly reduces the risk of a control rod drive accident to the point that no velocity limiter is required at the base of the cruciform control rod blades. Slightly different versions of
3741-567: The Chernobyl nuclear accident), as they were accused of causing more harm than they prevented. Following the accident, at least 164,000 residents of the surrounding area were permanently or temporarily displaced (either voluntarily or by evacuation order). The displacements resulted in at least 51 deaths as well as stress and fear of radiological hazards. Investigations faulted lapses in safety and oversight, namely failures in risk assessment and evacuation planning. Controversy surrounds
3870-462: The FP injection port was hidden under debris. The next morning (12 March, 04:00), approximately 12 hours after the loss of power, freshwater injection into the reactor vessel began, later replaced by a water line at 09:15 leading directly from the water storage tank to the injection port to allow for continuous operation (the fire engine had to be periodically refilled). This continued into the afternoon until
3999-674: The Fukushima Daiichi Accident. By October 2020, the Japanese government had inspected the plant, and by January 2020, TEPCO had completed its improvements on Unit 7. The company outlined plans to restart the reactor as early as the end of the Japanese 2022 Fiscal year (31 March 2022). However, the Nuclear Regulation Authority released a report in April 2021 indicating that there were serious security infractions and enacted an order that postponed
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4128-487: The Fukushima coast. In response to the station blackout during the initial hours of the accident and the ongoing uncertainty regarding the cooling status of units 1 and 2, a 2 km radius evacuation of 1,900 residents was ordered at 20:50. However, due to difficulty coordinating with the national government, a 3 km evacuation order of ~6,000 residents and a 10 km shelter-in-place order for 45,000 residents
4257-523: The HPCI and RCIC systems, but both failed to restart. Following this loss of cooling, workers established a water line from the valve pit to inject seawater into the reactor alongside unit 2. However, water could not be injected due to RPV pressures exceeding the pump capability. Similarly, preparations were also made to vent the unit 3 PCV, but PCV pressure was not sufficient to burst the rupture disk. Later that morning (9:08), workers were able to depressurize
4386-539: The HPCI system showed signs of malfunction. The HPCI isolation valve failed to activate automatically upon achieving a certain pressure. In response, the workers switched off HPCI and began injection of water via the lower-pressure firefighting equipment. However, the workers found that the SRVs did not operate to relieve pressure from the reactor vessel to allow water injection by the DDFP. In response, workers attempted to restart
4515-409: The IAEA reported that, for safety-related and nuclear components, "no visible significant damage has been found" although "nonsafety related structures, systems and components were affected by significant damage". The official report issued by the IAEA stated that the plant "behaved in a safe manner" after a 4-day inspection. Other observations were: Recommendations included: External inspections of
4644-707: The International Nuclear Event Scale. According to the United Nations Scientific Committee on the Effects of Atomic Radiation , "no adverse health effects among Fukushima residents have been documented that are directly attributable to radiation exposure from the Fukushima Daiichi nuclear plant accident". Insurance compensation was paid for one death from lung cancer , but this does not prove
4773-465: The NISA, this was the first time a release of radioactive material happened as a result of an earthquake. About 400 drums containing low-level nuclear waste stored at the plant were knocked over by the aftershocks , 40 losing their lids. Company officials reported on 17 July that traces of the radioactive materials cobalt-60 , iodine, and chromium-51 had been released into the atmosphere, presumably from
4902-435: The PCV was completed later that afternoon at 14:00. At the same time, pressure in the reactor vessel had been decreasing to equalize with the PCV, and the workers prepared to inject water into the reactor vessel using the DDFP once the pressure had decreased below the 0.8 MPa limit. Unfortunately, the DDFP was found to be inoperable and a fire truck had to be connected to the FP system. This process took about 4 hours, as
5031-473: The RCIC system failed. In response, the high-pressure coolant injection (HPCI) system was activated to alleviate the lack of cooling while workers continued to attempt to restart the RCIC. Additionally, the FP system was used to spray the PCV (mainly the SC) with water in order to slow the climbing temperatures and pressures of the PCV. On the morning of the 13th (02:42), after DC power was restored by new batteries,
5160-422: The RCIC system was continuing to cool the reactor. However, knowing that their DC supply was limited, the workers managed to extend the backup DC supply to about 2 days by disconnecting nonessential equipment, until replacement batteries were brought from a neighboring power station on the morning of the 13th (with 7 hours between loss and restoration of DC power). At 11:36 the next day, after 20.5 hours of operation,
5289-590: The United States, including two reactors at the South Texas Project site. The projects in both Taiwan and US are reported to be over-budget. The standard ABWR plant design has a net electrical output of about 1.35 GW , generated from about 3926 MW of thermal power. The ABWR represents an evolutionary route for the BWR family, with numerous changes and improvements to previous BWR designs. Major areas of improvement include: The RPV and Nuclear Steam Supply System (NSSS) have significant improvements, such as
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5418-436: The atmosphere, those which remain in a gaseous phase will simply be diluted by the atmosphere, but some which precipitate will eventually settle on land or in the ocean. Approximately 40–80% of the atmospheric caesium-137 was deposited in the ocean. Thus, the majority (90~99%) of the radionuclides which are deposited are isotopes of iodine and caesium, with a small portion of tellurium , which are almost fully vaporized out of
5547-410: The blackout, the RCIC was functioning as designed without the need for operator intervention. The safety relief valves (SRVs) would intermittently release steam directly into the PCV suppression torus at its design pressure and the RCIC properly replenished lost coolant. However, following the total blackout of Unit 2, the plant operators (similar to Unit 1) assumed the worst-case scenario and prepared for
5676-459: The condenser tank would have to be refilled). However, it was possible for the IC system to cool the reactor too rapidly shortly after shutdown which could result in undesirable thermal stress on the containment structures. To avoid this, the protocol called for reactor operators to manually open and close the condenser loop using electrically operated control valves. After the construction of Unit 1,
5805-400: The containers losing their lids. Criticisms of the company's response to the event included the time it took the company to report events and the certainty with which they were able to locate the source of various problems. TEPCO's president made a comment the site was a "mess" after visiting post-quake. While the reported amount of leaked radioactivity remained far below what poses a danger to
5934-708: The contaminated waters far into the Pacific Ocean, dispersing the radioactivity. As of late 2011, measurements of both the seawater and the coastal sediments suggested that the consequences for marine life would be minor. Significant pollution along the coast near the plant might persist, because of the continuing arrival of radioactive material transported to the sea by surface water crossing contaminated soil. The possible presence of other radioactive substances, such as strontium-90 or plutonium , had not been sufficiently studied. Recent measurements show persistent contamination of some marine species (mostly fish) caught along
6063-431: The core due to their high vapor pressure. The remaining fraction of deposited radionuclides are of less volatile elements such as barium , antimony , and niobium , of which less than a percent is evaporated from the fuel. In addition to atmospheric deposition, there was also a significant quantity of direct releases into groundwater (and eventually the ocean) through leaks of coolant which had been in direct contact with
6192-399: The critical parts of the reactor was found. In 2006, the design of the reactors was reevaluated with new standards requiring the reactors to withstand accelerations ranging up to 450 Gal. In the event of an emergency, operators planned to pump water into the reactors to keep them cool. This would inevitably create steam which should not be very radioactive because the fuel would still be in
6321-415: The earthquake, combined with the fact that replacement power sources (such as oil and gas) are at record highs, caused TEPCOs stock to plummet 7.5%, the largest drop in seven years, which amounted to around US$ 4.4 billion lost in stock capitalization. This made the event even more costly to the company than the 2002 data falsification scandal . Additionally, TEPCO warned that the plant closure could cause
6450-494: The earthquake. The shutdown forced TEPCO to run natural gas plants in place of this plant, not only increasing Japan's demand for the fuel and increasing the price internationally, but also increasing carbon dioxide output such that Japan will have difficulty meeting the Kyoto Protocol . After 16 months of comprehensive component-based assessment and upgrades on all seven reactors, this phase of post-earthquake response
6579-466: The epicenter of the magnitude 6.6 2007 Chūetsu offshore earthquake , which took place 10:13 a.m., 16 July 2007. Peak ground acceleration of 6.8 m/s (0.69 g ) was recorded in Unit 1 in the east–west direction, above the design specification for safe shutdown of 4.5 m/s, and well above the rapid restart specification for key equipment in the plant of 2.73 m/s. Units 5 and 6 also recorded shaking over this limit. Shaking of 20.58 m/s
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#17327803077326708-473: The exothermic reaction of boron carbide with stainless steel , these reactions can contribute to the overheating of a reactor. In the event of an emergency, reactor pressure vessels (RPV) are automatically isolated from the turbines and main condenser and are instead switched to a secondary condenser system which is designed to cool the reactor without the need for pumps powered by external power or generators. The isolation condenser (IC) system involved
6837-443: The explosion. The debris produced by the explosion damaged the mobile emergency power generator and the seawater injection lines. The seawater injection lines were repaired and put back into operation at 19:04 until the valve pit was nearly depleted of seawater at 01:10 on the 14th. The seawater injection was temporarily stopped in order to refill the valve pit with seawater using a variety of emergency service and JSDF vehicles. However,
6966-480: The facility. The power company intends to invest ¥20 Billion (US$ 165.4 Million) on these security measures from 31 March 2023 to 31 March 2028. According to a report from TEPCO, the NRA began Additional Inspection (Phase II) to monitor the new security measures at the plant. In April 2022, it was confirmed that the security flaws revealed in the NRA's April 2022 report were limited to Kashiwazaki-Kariwa and not indicative of
7095-428: The feasibility of this timelime have been questioned by journalists given the number of safety issues that have come to light at the plant in the last few years. Most of these issues relate to security discrepancies such as a worker who forgot his ID, borrowed his colleagues card to enter crucial areas. A government inspection of Unit 7 in October 2020 concluded that the majority of construction had been finished by January
7224-409: The final 20 km evacuation zone. 20% of residents who were within the initial 2 km radius had to evacuate more than six times. Additionally, a 30 km shelter in place order was communicated on the 15th, although some municipalities within this zone had already decided to evacuate their residents. This order was followed by a voluntary evacuation recommendation on the 25th, although
7353-400: The following numbers of fuel assemblies: The original design basis was a zero-point ground acceleration of 250 Gal and a static acceleration of 470 Gal, based on the 1952 Kern County earthquake (0.18 g , 1.4 m/s , 4.6 ft/s ). After the 1978 Miyagi earthquake , when the ground acceleration reached 0.125 g (1.22 m/s , 4.0 ft/s ) for 30 seconds, no damage to
7482-475: The following units were designed with new open-cycle reactor core isolation cooling (RCIC) systems. This new system used the steam from the reactor vessel to drive a turbine which would power a pump to inject water into the pressure vessel from an external storage tank to maintain the water level in the reactor vessel and was designed to operate for at least 4 hours (until the depletion of coolant or mechanical failure). Additionally, this system could be converted into
7611-454: The following year. TEPCO felt that it is doing everything in its power to meet NRA guidelines. In late 2023, the national regulator lifted the operational ban on the plant, allowing it to begin applying for permits from local governments to reopen. On Monday, 8 April 2024, Japans Nuclear Regulation Authority approved plans submitted by TEPCO to fuel reactor No. 7. TEPCO announced it would begin fueling reactor 7 starting around 4pm on 14 April,
7740-693: The four ABWRs in operation are often shut down due to technical problems. The International Atomic Energy Agency documents this with the 'operating factor' (the time with electricity feed-in relative to the total time since commercial operation start). The first two plants in Kashiwazaki-Kariwa (block 6 & 7) reach total life operating factors of 70%, meaning that about 30% of the time, since commissioning, they were not producing electricity. For example, in 2010 Kashiwazaki-Kariwa 6 had an operating capacity of 80.9%, and an operating capacity of 93% in 2011. However, in 2008 it did not produce any power as
7869-455: The freshwater tank was nearly depleted. In response, injection stopped at 14:53 and the injection of seawater, which had collected in a nearby valve pit (the only other source of water), began. Power was restored to units 1 (and 2) using a mobile generator at 15:30 on 12 March. At 15:36, a hydrogen explosion damaged the secondary confinement structure (the RB). The workers evacuated shortly after
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#17327803077327998-542: The fuel pond had risen slightly, to 61 °C (142 °F), and water was sprayed over the pool. Power was restored to cooling systems on 24 March and by 28 March, temperatures were reported down to 35 °C (95 °F). Quantities of the released material are expressed in terms of the three predominant products released: caesium-137 , iodine-131 , and xenon-133 . Estimates for atmospheric releases range from 7–20 PBq for Cs-137, 100–400 PBq for I-131, and 6,000–12,000 PBq for Xe-133. Once released into
8127-496: The fuel. Estimates for this release vary from 1 to 5.5 PBq caesium-137 and 10-20 PBq iodine-131 . According to the French Institute for Radiological Protection and Nuclear Safety , the release from the accident represents the most important individual oceanic emissions of artificial radioactivity ever observed. The Fukushima coast has one of the world's strongest currents ( Kuroshio Current ). It transported
8256-463: The general trend in costs of nuclear plants. Capital costs increased through the 1980s but have become cheaper in modern times. The last two units were the first Advanced Boiling Water Reactors (ABWRs) ever built. Operating a single large plant comprising this many reactors has several economic advantages. One such benefit is the limited impact of single-reactor refueling outages during the replacement cycle; one dormant reactor makes minimal impact on
8385-412: The ground floor of the spent fuel building, but the switches and various other components were located below, in the basement. The third air-cooled EDG was in a separate building placed inland and at higher elevations. Although these EDGs are intended to be used with their respective reactors, switchable interconnections between unit pairs (1 and 2, 3 and 4, and 5 and 6) allowed reactors to share EDGs should
8514-440: The ground or basement levels at approximately 15:41. The switching stations that provided power from the three EDGs located higher on the hillside also failed when the building that housed them flooded. One air-cooled EDG, that of unit 6, was unaffected by the flooding and continued to operate. The DC batteries for units 1, 2, and 4 were also inoperable shortly after flooding. As a result, units 1–5 lost AC power and DC power
8643-548: The housings connected to the bottom of the RPV and eliminating large diameter external recirculation pipes that are possible leakage paths. The 10 internal recirculation pumps are located at the bottom of the annulus downcomer region (i.e., between the core shroud and the inside surface of the RPV). Consequently, internal recirculation pumps eliminate all of the jet pumps in the RPV, all of the large external recirculation loop pumps and piping,
8772-652: The installation was offline for maintenance, and therefore had an operating capacity of 0% for that year. In contrast other modern nuclear power plants like the Korean OPR-1000 or the German Konvoi show operating factors of about 90%. The output power of the two new ABWRs at the Hamaoka and Shika power plant had to be lowered because of technical problems in the power plants steam turbine section. After throttling both power plants down, they still have
8901-404: The isolation valves and the large diameter nozzles that penetrated the RPV and needed to suction water from and return it to the RPV. This design therefore reduces the worst leak below the core region to effectively equivalent to a 2-inch-diameter (51 mm) leak. The conventional BWR3-BWR6 product line has an analogous potential leak of 24 or more inches in diameter. A major benefit of this design
9030-415: The isolation valves. In an emergency where backup on-site power was partially damaged or insufficient to last until a grid connection to off-site power could be restored, these cooling systems could no longer be relied upon to reliably cool the reactor. In such a case, the expected procedure was to vent both the reactor vessel and primary containment using electrically or pneumatically operated valves using
9159-418: The jet pump system with external recirculation loops. Thus, in addition to the safety and cost improvements due to eliminating the piping, the overall plant thermal efficiency is increased. Eliminating the external recirculation piping also reduces occupational radiation exposure to personnel during maintenance. An operational feature in the ABWR design is electric fine motion control rod drives, first used in
9288-437: The majority of residents had evacuated from the 30 km zone by then. The shelter in place order was lifted on April 22, but the evacuation recommendation remained. Of an estimated 2,220 patients and elderly who resided within hospitals and nursing homes within the 20 km evacuation zone, 51 fatalities are attributed to the evacuation. There was one suspected death due to radiation, as one person died 4 years later of
9417-455: The need arise. The power station was also equipped with backup DC batteries kept charged by AC power at all times, designed to be able to power the station for approximately 8 hours without EDGs. In units 1, 2, and 4, the batteries were located in the basements alongside the EDGs. In units 3, 5, and 6, the batteries were located in the turbine building where they were raised above ground level. The units and central storage facility contained
9546-550: The new owner. The 'Development Consent Order' for Wylfa was accepted in June 2018 and in August Bechtel were appointed as project managers. The first reactor was expected online in the mid-2020s with construction at Oldbury expected to start a few years after this. However, on January 17, 2019, Horizon Nuclear Power announced the suspension of both these projects for financial reasons. In comparison with comparable designs,
9675-400: The newly installed Japanese regulator NRA. In January 2013, studies were conducted or planned on geological faults around six Japanese reactor sites. The Kashiwazaki-Kariwa plant would be number seven. In 2017, TEPCO contempleted a restart of the plant from 2019 to 2021. Kashiwazaki-Kariwa is one of the 44 nuclear power plants in Japan that have been rendered inactive in the years following
9804-406: The ocean began two hours later, and cooling of unit 3 resumed in the afternoon (approximately 16:00) and continued until cooling was lost once more as a result of site evacuation on the 15th. Unit 4 was not fueled at the time, but the unit 4 spent fuel pool (SFP) contained a number of fuel rods. On 15 March, an explosion was observed at unit 4 RB during site evacuation. A team later returned to
9933-554: The plant remains idle. All reactors continue to use low-enriched uranium as the nuclear fuel; however, there have been plans drafted by TEPCO to use MOX fuel in some of the reactors by the permission of the Japanese Atomic Energy Commission (JAEC). A public referendum in the Kariwa village in 2001 voted 53% against use of the new fuel. After the 2002 TEPCO data fabrication scandals, the president at
10062-639: The plant safe. However, TEPCO determined that significant upgrades were required to cope with the improved understanding of the seismic environment and possible shaking effects at the plant site. The IAEA sent a team for a follow-up visit in January 2008. They concluded that much high-quality inspection work had been undertaken and noted the likely improvements to nuclear seismic design worldwide that may result from this process. An additional visit from an IAEA team of 10 experts occurred in December 2008, noting that
10191-472: The plant were built according to earthquake-resistance standards, which are regulated by law and the JAEC. In 2006 safety standards for earthquake resistance in Japan's nuclear plants were modified and tightened. After the 2007 earthquake suspicions arose that another fault line may be closer to the plant than originally thought, possibly running straight through the site. The KK plant was 19 kilometers away from
10320-410: The plant were planned to be completed by the end of July 2008. The schedule was confirmed on 10 July 2008 by the site superintendent, Akio Takahashi. On 15 July, Akira Amari said his ministry was also continuing their own tests. An IAEA workshop in June 2008 recognized that the earthquake exceeded the "seismic input" used in the design in that plant, and that regulations played a critical role in keeping
10449-431: The plant's net power production. A smooth transition was seen in the power production history of the plant up through the time the last two units were built. Currently, however, there are no active reactors at the Kashiwazaki-Kariwa plant. TEPCO has outlined plans to restart Reactor 6 and Reactor 7 and is awaiting approval from the government and citizens before the reactors are permitted to restart. In February 1991, Unit 2
10578-463: The power station to inspect unit 4, but were unable to do so due to the present radiological hazard. The explosion damaged the fourth-floor rooftop area of Unit 4, creating two large holes in a wall of the RB. The explosion was likely caused by hydrogen passing to unit 4 from unit 3 through shared pipes. The following day, on the 16th, an aerial inspection was performed by helicopter which confirmed there
10707-410: The primary containment vessel and even partially eaten into its concrete foundation, coming within about 30 cm (1 ft) of leaking into the ground". A Kyoto University nuclear engineer said with regard to these estimates: "We just can't be sure until we actually see the inside of the reactors." Unit 2 was the only other operating reactor which experienced a total loss of AC and DC power. Before
10836-496: The primary containment vessel. Therefore, the steam would manually be released by venting valves to prevent a high pressure explosion. The 9.0 M W earthquake occurred at 14:46 on Friday, 11 March 2011, with the epicenter off of the east coast of the Tōhoku region . It produced maximum ground g-force of 560 Gal , 520 Gal, 560 Gal at units 2, 3, and 5 respectively. This exceeded the seismic reactor design tolerances of 450 Gal, 450 Gal, and 460 Gal for continued operation, but
10965-581: The process of generic design assessment of the Hitachi-GE ABWR with the UK Office for Nuclear Regulation . This was completed in December 2017. In July 2016 Toshiba withdrew the U.S. design certification renewal for the ABWR because "it has become increasingly clear that energy price declines in the US prevent Toshiba from expecting additional opportunities for ABWR construction projects". The ABWR
11094-496: The process of restarting seawater injection was interrupted by another explosion in unit 3 RB at 11:01 which damaged water lines and prompted another evacuation. Injection of seawater into unit 1 would not resume until that evening, after 18 hours without cooling. Subsequent analysis in November 2011 suggested that this extended period without cooling resulted in the melting of the fuel in unit 1, most of which would have escaped
11223-405: The public a direct measure of ambient radioactivity around the site, but due to damage sustained during the earthquake, stopped reporting on the website. The company published an apology on that page, and data from the devices covering the off-line period was released later, showing no artificial abnormalities (note that the readings naturally fluctuate depending on whether it's raining or snowing and
11352-407: The public, details changed multiple times in the few days after the quake and attracted significant media attention. After the quake, TEPCO was supposedly investigating 50 separate cases of "malfunctioning and trouble," a number that was changed to 63 cases later. Even the radioactivity sensors around the site encountered trouble, the reading from these devices are normally available online, giving
11481-495: The quickest and suffered the smallest effect. Units 1, 2, and 3, on the other hand, generated no electricity during the fiscal year of 2003. Units 1-4 were completely shut down in 2008. Only Unit 1 was temporarily restarted in 2010–2011. Unit 5 was temporarily restarted between 2010 and 2012 after a shut down in 2007. Following the Fukushima disaster in 2011, Unit 1 was shut down again in 2012 along with units 5–7. As of May 2022,
11610-468: The reactor by operating the safety relief valves using batteries collected from nearby automobiles. This was shortly followed by the bursting of the venting line rupture disk and the depressurization of the PCV. Unfortunately, venting was quickly stopped by a pneumatic isolation valve which closed on the vent path due to a lack of compressed air, and venting was not resumed until over 6 hours later once an external air compressor could be installed. Despite this,
11739-414: The reactor operators began planning to lower the PCV pressure by venting. The PCV reached its maximum pressure of 0.84 MPa at 02:30 on 12 March, after which it stabilized around 0.8 MPa. The decrease in pressure was due to an uncontrolled vent via an unknown pathway. The plant was notified Okuma town completed evacuation at 9:02 on 12 March. The staff subsequently began controlled venting. Venting of
11868-399: The reactor pressure was immediately low enough to allow for water injection (borated freshwater, as ordered by TEPCO) using the FP system until the freshwater FP tanks were depleted, at which point the injected coolant was switched to seawater from the valve pit. Cooling was lost once the valve pit was depleted but was resumed two hours later (unit 1 cooling was postponed until the valve pit
11997-426: The reactor vessel. However, the reactor pressure had already increased to many times greater than the limit of the DDFP. Additionally, the team detected high levels of radiation within the secondary confinement structure, indicating damage to the reactor core, and found that the primary containment vessel (PCV) pressure (0.6 MPa ) exceeded design specifications (0.528 MPa). In response to this new information,
12126-603: The release of radioactive contaminants into the surrounding environment. The accident was rated seven (the maximum severity) on the International Nuclear Event Scale by Nuclear and Industrial Safety Agency, following a report by the JNES (Japan Nuclear Energy Safety Organization). It is regarded as the worst nuclear incident since the Chernobyl disaster in 1986, which was also rated a seven on
12255-480: The reloading of fuel at the plant, citing improvements in the safety management system. As of 2024, TEPCO is seeking permission from local authorities to restart the plant again. There are seven reactor units spread across the campus coast line. Numbering starts at Unit 1 with the south-most unit through Unit 4, then there is a large green space in between Unit 4 and 7, then it continues with Units 6 and 5. The power installation costs for units at this site well reflect
12384-506: The remaining electricity on site. This would lower the reactor pressure sufficiently to allow for low-pressure injection of water into the reactor using the fire protection system to replenish water lost to evaporation. Station operators switched the reactor control to off-site power for shutdown, but the system was damaged by the earthquake. Emergency diesel generators (EDG) then automatically started to provide AC power. Two EDGs were available for each of units 1–5 and three for unit 6. Of
12513-489: The restart for over a year, without stating the source of the information. For comparison, in 2005, a reactor at the Onagawa Nuclear Power Plant was closed for five months following an earthquake. The International Atomic Energy Agency (IAEA) offered to inspect the plant, which was initially declined. The governor of Niigata prefecture then sent a petition to Shinzo Abe . On Sunday, 22 July 2007,
12642-521: The restart indefinitely. Following the April 2021 NRA report, TEPCO admitted that its intruder detection system was left broken in order to reduce costs and confirmed that an unauthorized personnel member used a colleague's ID card to access the plant's central control room in September 2020. In response, TEPCO plans to implement anti-terrorism measures, install an intrusion detection system, and hire an additional 30 guards to protect nuclear material at
12771-464: The safety assessments for the plant. These were based on a magnitude 7.85 quake caused by a 131 kilometer long fault near Sado Island in Niigata and a 3.3 meter-high tsunami. To endure this, an embankment was under construction to resist tsunami waves up to 15 meters high. The recalculation could have consequences for the stress tests and safety assessments for the plant. After the planned revision of
12900-461: The safety standards in July 2013, some faults under the reactors were considered as geologically active. This was found by Japanese news agency Kyodo News on 23 January 2013 in papers and other material published by TEPCO. Under the new regulations, geologic faults would be considered to be active if they had moved within the last 400,000 years, instead of the less stringent standard of 120 000 years, as
13029-479: The same week that fuel loading for Unit 3 started. Units 2, 3, and 4 were not restarted. The reactors were shut down indefinitely following the 2011 Tōhoku earthquake and tsunami . Plans to restart units 6 and 7 were delayed after problems developed with the intruder detection system. On 21 April 2011, after the Fukushima Daiichi nuclear disaster , TEPCO announced a plan to build up the seawall to
13158-587: The second most common form of light water reactor with a direct cycle design that uses fewer large steam supply components than the pressurized water reactor (PWR), which employs an indirect cycle. The ABWR is the present state of the art in boiling water reactors , and is the first Generation III reactor design to be fully built , with several reactors complete and operating. The first reactors were built on time and under budget in Japan , with others under construction there and in Taiwan . ABWRs were on order in
13287-455: The seismic values were within the design tolerances of unit 6. Upon detecting the earthquake, all three operating reactors (units 1, 2, and 3) automatically shut down. Due to expected grid failure and damage to the switch station as a result of the earthquake, the power station automatically started up the EDGs, isolated the reactor from the primary coolant loops, and activated the emergency shutdown cooling systems. The largest tsunami wave
13416-452: The steam driving the turbine triggered alarms. The levels were reportedly 270 times the expected operating level. Reactors at the plant were shut down one by one following the 2002 discovery that TEPCO had deliberately falsified data surrounding safety inspections. The first reactor was taken offline 9 September 2002, and the final reactor was taken offline 27 January 2003. The newest units, the more inherently safe ABWRs, were taken back online
13545-437: The substitution of RIPs, eliminating conventional external recirculation piping loops and pumps in the containment that in turn drive jet pumps producing forced flow in the RPV. RIPs provide significant improvements related to reliability, performance and maintenance, including a reduction in occupational radiation exposure related to containment activities during maintenance outages. These pumps are powered by wet-rotor motors with
13674-625: The televised news media. Citizens were informed by radio, trucks with megaphones, and door to door visits. Many municipalities independently ordered evacuations ahead of orders from the national government due to loss of communication with authorities; at the time of the 3 km evacuation order, the majority of residents within the zone had already evacuated. Due to the multiple overlapping evacuation orders, many residents had evacuated to areas which would shortly be designated as evacuation areas. This resulted in many residents having to move multiple times until they reached an area outside of
13803-466: The time of the March 2011 earthquake.) The four restarted and operating units at the plant were not affected by the 11 March 2011 earthquake , but thereupon all units were shut down to carry out safety improvements. TEPCO regained permission to restart units 6 and 7 from the Nuclear Regulation Authority (NRA) in 2017, but throughout 2023, all units remained idle. In December 2023, the NRA finally approved
13932-410: The time the plant was designed and built. On 26 April 2012, TEPCO said that it would recalculate the risks of earthquakes and tsunamis. This was done after reports, as published by four prefectures around the nuclear Plant, re-estimated the risks of potential earthquakes in the region: The calculated earthquake magnitudes are almost three times stronger than all the calculations done by TEPCO regarding
14061-630: The time, Nobuya Minami [ jp ] , announced that plans to use the MOX fuel at the KK plant would be suspended indefinitely. Sand at the sites was removed and the reactor was built on firm ground. Adjacent soil was backfilled. Basements of the reactor buildings extend several levels down (maximum of 42 m below grade). These underground elements stabilize the reactor buildings, making them less likely to suffer sway due to resonance vibrations during an earthquake. As with other Japanese power plants, reactors at
14190-412: The tsunami, operators attempted to manually open the IC control valve, but the IC failed to function, suggesting that the isolation valves were closed. Although they were kept open during IC operation, the loss of DC power in unit 1 (which occurred shortly before the loss of AC power) automatically closed the AC-powered isolation valves to prevent uncontrolled cooling or a potential LOC. Although this status
14319-462: The tsunami. The isolation condenser (IC) was functioning prior to the tsunami, but the DC-operated control valve outside of the primary containment had been in the closed position at the time to prevent thermal stresses on the reactor components. Some indications in the control room stopped functioning and operators correctly assumed loss of coolant (LOC). At 18:18 on 11 March, a few hours after
14448-489: Was 13–14 m (43–46 feet) high and hit approximately 50 minutes after the initial earthquake, overtopping the seawall and exceeding the plant's ground level, which was 10 m (33 ft) above sea level. The waves first damaged the seawater pumps along the shoreline, 10 of the plant's 13 cooling systems for the emergency diesel generators (EDG). The waves then flooded all turbine and reactor buildings, damaging EDGs and other electrical components and connections located on
14577-447: Was a major nuclear accident at the Fukushima Daiichi nuclear power plant in Ōkuma, Fukushima , Japan which began on 11 March 2011. The proximate cause of the accident was the 2011 Tōhoku earthquake and tsunami , which resulted in electrical grid failure and damaged nearly all of the power plant's backup energy sources . The subsequent inability to sufficiently cool reactors after shutdown compromised containment and resulted in
14706-403: Was almost complete, with Reactor 7 fully upgraded to cope with the seismic environment. On 8 November 2008, fuel loading in reactor Unit 7 started, preparatory to a period of system safety tests on that reactor. On 19 February 2009 TEPCO applied to the local governance to restart Unit 7 after having obtained approval from the national government and regulators. Local government agreement for restart
14835-522: Was approved by the NRC on February 9, 2016. Due to market conditions, these two planned units may never be built and do not have a planned construction date. Horizon Nuclear Power had plans to build Hitachi-GE ABWRs at Wylfa in Wales and Oldbury in England. Both projects were paused in March 2012 by the shareholders at the time ( RWE and E-ON ) to put Horizon up for sale, with Hitachi becoming
14964-402: Was automatically shut down following a sudden drop in oil pressure inside the steam turbine. On 18 July 1997, radioactive steam leaked from a gauge within Unit 7 of the Kashiwazaki-Kariwa plant. In May, a burst tube had delayed trial runs at the plant, and earlier in July smoke had been found coming from plant machinery. In January 1998, Unit 1 was shut down after increasing radiation levels in
15093-457: Was damaged and the isolation valve for the PCV vent was found to be closed and inoperable. At 13:00 on the 14th, the RCIC pump for unit 2 failed after 68 hours of continuous operation. With no way to vent the PCV, in response, a plan was devised to delay containment failure by venting the reactor vessel into the PCV using the SRVs to allow for seawater injection into the reactor vessel. The following morning (March 15, 06:15), another explosion
15222-416: Was established nearly simultaneously at 21:23. The evacuation radius was expanded to 10 km at 5:44, and was then revised to 20 km at 18:25. The size of these evacuation zones was set for arbitrary reasons at the discretion of bureaucrats rather than nuclear experts. Communication between different authorities was scattered and at several times the local governments learned the status of evacuation via
15351-590: Was filled). However, despite being cooled, PCV pressure continued to rise and the RPV water level continued to drop until the fuel became uncovered on the morning of the 14th (6:20), as indicated by a water level gauge, which was followed by workers evacuating the area out of concerns about a possible second hydrogen explosion similar to unit 1. Shortly after work resumed to reestablish coolant lines, an explosion occurred in unit 3 RB at 11:01 on March 14, which further delayed unit 1 cooling and damaged unit 3's coolant lines. Work to reestablish seawater cooling directly from
15480-415: Was formerly accepted. Two faults, named "Alpha" and "Beta," are present under Reactors 1 and 2. Other faults are situated under Reactor 3 and Reactor 5, as well as underneath the building of Reactor 4. Under the new regulations, the beta-fault could be classified as active because it moved a ground layer including volcanic ash around 240,000 years ago. The outcome of the study might trigger a second survey by
15609-517: Was granted in May and electrical grid power was supplied from Unit 7 at 20% power on 19 May. The reactor was raised to 100% power on 5 June 2009 as part of a series of restart tests. Unit 6 restarted on 26 August 2009 and reconnected to the grid on 31 August. Unit 1 restarted on 31 May 2010 after loading with fuel (along with Unit 5) earlier in the year, and was generating grid power by 6 June 2010. Unit 5 recommenced grid generation on 26 November 2010, in
15738-533: Was heard on site coinciding with a rapid drop of suppression chamber pressure to atmospheric pressure, interpreted as a malfunction of suppression chamber pressure measurement. Due to concerns about the growing radiological hazard on site, almost all workers evacuated to the Fukushima Daini Nuclear Power Plant . Although AC power was lost, some DC power was still available in unit 3 and the workers were able to remotely confirm that
15867-474: Was in startup mode and not online. Units 1, 5, and 6 were already shut down for inspection at the time. TEPCO was ready to restart some of the units as of the next day, but the trade ministry ordered the plant to remain idle until additional safety checks could be completed. On Wednesday, 18 July, the mayor of Kashiwazaki ordered operations at the plant to be halted until its safety could be confirmed. The Nikkei reported that government safety checks could delay
15996-412: Was lost in units 1, 2, and 4. In response, the operators assumed a loss of coolant in units 1 and 2 and developed a plan in which they would vent the primary containment and inject water into the reactor vessels with firefighting equipment. Tokyo Electric Power Company ( TEPCO ), the utility operator and owner, notified authorities of a "first-level emergency". Two workers were killed by the impact of
16125-424: Was manually reconfigured at 05:00 to recirculate water from the suppression chamber instead. On the 13th, unit 2 was configured to vent the PCV automatically (manually opening all valves, leaving only the rupture disk) and preparations were made to inject seawater from the valve pit via the FP system should the need arise. However, as a result of the explosion in unit 3 the following day, the seawater injection setup
16254-404: Was not possible, as the reactor was not producing sufficient steam. However, the water within the RPV proved sufficient to cool the fuel, with the SRVs venting into the PCV, until AC power was restored on March 13 using the unit 6 interconnection, allowing the use of the low-pressure pumps of the residual heat removal (RHR) system. Unit 5 was the first to achieve a cold shutdown in the afternoon on
16383-414: Was recorded in the turbine building of Unit 3. Those nearby saw black smoke which was later confirmed to be an electric transformer that had caught fire at Unit 3. The fire was put out by noon on the day of the quake, about 2 hours after it started. The 3-story transformer building was extensively charred. Reactor units 3, 4, and 7 all automatically powered down safely in response to the quake. Unit 2
16512-448: Was sufficient water remaining in the SFP. On the 20th, water was sprayed into the uncovered SFP, later replaced by a concrete pump truck with a boom on the 22nd. Unit 5 was fueled and was undergoing an RPV pressure test at the time of the accident, but the pressure was maintained by an external air compressor and the reactor was not otherwise operating. Removal of decay heat using the RCIC
16641-435: Was unknown to the plant operators, they correctly interpreted the loss of function in the IC system and manually closed the control valves. The plant operators would continue to periodically attempt to restart the IC in the following hours and days, but it did not function. The plant operators then attempted to use the building's fire protection (FP) equipment, operated by a diesel-driven fire pump (DDFP), to inject water into
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