Kashiwazaki-Kariwa Nuclear Power Plant
Encyclopedia
The is a large, modern (housing the world's first ABWR) nuclear power
plant on a 4.2-square-kilometer (1,038 acres) site including land in the towns of Kashiwazaki
and Kariwa
in Niigata Prefecture
, Japan
on the coast of the Sea of Japan
, from where it gets cooling water. The plant is owned and operated by The Tokyo Electric Power Company
(TEPCO).
It is the largest nuclear generating station in the world by net electrical power
rating. It was approximately 15 miles from the epicenter of the second strongest earthquake to ever occur at a nuclear plant, the Mw
6.6 July 2007 Chūetsu offshore earthquake
. This shook the plant beyond design basis and initiated an extended shutdown for inspection, which indicated that greater earthquake-proofing was needed before operation could be resumed.
The plant was completely shut down for 21 months following the earthquake. On May 9, 2009, one unit (Unit 7) was restarted, after seismic upgrades. Units 6, 1, and 5 have since been restarted as well.
The power installation costs for units at this site well reflect 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 Reactor
s (ABWRs) ever built.
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 the time, Nobuya Minami, announced that plans to use the MOX fuel at the KK plant would be suspended indefinitely.
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.
on November 4, 2004, devices around the base of the plant only measured 4 on the Japanese seismological intensity scale while other nearby places measured 6.
All of the reactors except for Unit 4 were operating normally at the time of the earthquake and continued to do so through the quake, Unit 4 was shut down due to routine maintenance. Unit 7 shut down during an aftershock because the turbine thrust bearing wear trip signal was activated.
The KK plant was 19 kilometers away from the epicenter of the magnitude
6.6 2007 Chūetsu offshore earthquake
, which took place 10:13 a.m., July 16, 2007. Shaking
of 6.8 m/s² (0.69 g) was recorded in Unit 1 in the east-west direction, above the design specification for safe shutdown of 4.5 m/s², and well above the rapid restart specification for key equipment in the plant of 2.73 m/s². Units 5 and 6 also recorded shaking over this limit. Shaking of 20.58 m/s² 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 nearly completely charred.
Reactor units 2, 3, 4, and 7 all automatically powered down safely in response to the quake, while 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, July 18, 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 the restart for over a year, without stating the source of the information. For comparison, in 2005, a reactor at the Onagawa NPP
was closed for five months following an earthquake.
offered to inspect the plant, which was initially declined. The governor of Niigata prefecture
then sent a petition to Shinzo Abe
. On Sunday, July 22, the 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 August 19, 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 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 July 15, 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 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 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.
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 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 aftershock
s, 40 losing their lids. Company officials reported on July 17 that traces of the radioactive materials cobalt-60
, iodine, and chromium-51 had been released into the atmosphere, presumably from 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, in fact, 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 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 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 a host of other factors).
Tepco's president maintained that fears of a radiation leak 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.
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 the earthquake.
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 a hard time meeting the Kyoto Protocol
.
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 the same week that fuel loading for unit 3 started.
, to a height of 15 m (49.2 ft) above sea level
, more than 800 m (2,624 ft) in length for units 1- 4, and more than 500 m (1,640 ft) for unit 5-7 by June 2013, which has been assumed 3.3 m height of tsunami
. Also, plans have been made to rebuild the storage pool for radioactive water overflow by September 2012.
and METI. Some of the events listed below didn't necessarily fit this category but TEPCO decided to officially report them anyway.
; however, objections from the local community due to concerns of electromagnetic waves stopped the plan. This would have been Japan's first electric line of that scale.
, started a law suit at the Otsu District Court, and asked a court order to prevent the restart of seven reactors operated by Kansai Electric Power Company
, in the prefecture Fukui
.
Entire plant related
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
plant on a 4.2-square-kilometer (1,038 acres) site including land in the towns of Kashiwazaki
Kashiwazaki, Niigata
is a city located in Niigata, Japan.As of May 1, 2008, the city has an estimated population of 92,947 and the density of 210 persons per km². The total area is 442.70 km²....
and Kariwa
Kariwa, Niigata
is a village located in Kariwa District, Niigata, Japan.As of March 31, 2007, the village has a population of 4,997 and a density of 190.14 persons per km²...
in Niigata Prefecture
Niigata Prefecture
is a prefecture of Japan located on the island of Honshū on the coast of the Sea of Japan. The capital is the city of Niigata. The name "Niigata" literally means "new lagoon".- History :...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
on the coast of the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
, from where it gets cooling water. The plant is owned and operated by The Tokyo Electric Power Company
The Tokyo Electric Power Company
, also known as or TEPCO, is an electric utility servicing Japan's Kantō region, Yamanashi Prefecture, and the eastern portion of Shizuoka Prefecture. This area includes Tokyo...
(TEPCO).
It is the largest nuclear generating station in the world by net electrical power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
rating. It was approximately 15 miles from the epicenter of the second strongest earthquake to ever occur at a nuclear plant, the Mw
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
6.6 July 2007 Chūetsu offshore earthquake
2007 Chuetsu offshore earthquake
The Chūetsu Offshore Earthquake was a powerful magnitude 6.6 earthquake that occurred 10:13 a.m. local time on July 16, 2007, in the northwest Niigata region of Japan. The earthquake shook Niigata and neighbouring prefectures...
. This shook the plant beyond design basis and initiated an extended shutdown for inspection, which indicated that greater earthquake-proofing was needed before operation could be resumed.
The plant was completely shut down for 21 months following the earthquake. On May 9, 2009, one unit (Unit 7) was restarted, after seismic upgrades. Units 6, 1, and 5 have since been restarted as well.
Reactors
There are seven units, which are all lined up along the 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 newest of the reactors.| KK - 1 | KK - 2 | KK - 3 | KK - 4 | KK - 5 | KK - 6 | KK - 7 | |
|---|---|---|---|---|---|---|---|
| Reactor Type | BWR | BWR | BWR | BWR | BWR | ABWR | ABWR |
| Net Power (MW) | 1,067 | 1,067 | 1,067 | 1,067 | 1,067 | 1,315 | 1,315 |
| Gross Power (MW) | 1,100 | 1,100 | 1,100 | 1,100 | 1,100 | 1,356 | 1,356 |
| Start of Construction | 6/5/1980 | 11/18/1985 | 3/7/1989 | 3/5/1990 | 6/20/1985 | 11/3/1992 | 7/1/1993 |
| First Criticality | 12/12/1984 | 11/30/1989 | 10/19/1992 | 11/01/1993 | 7/20/1989 | 12/18/1995 | 11/01/1996 |
| Commission date | 9/18/1985 | 9/28/1990 | 8/11/1993 | 8/11/1994 | 4/10/1990 | 11/7/1996 | 7/2/1997 |
| Installation Costs (1,000 yen/kW) | 330 | 360 | 310 | 310 | 420 | 310 | 280 |
| Reactor/NSSS Supplier | Toshiba Toshiba is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and... |
Toshiba Toshiba is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and... |
Toshiba Toshiba is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and... |
Hitachi Hitachi, Ltd. is a Japanese multinational conglomerate headquartered in Marunouchi 1-chome, Chiyoda, Tokyo, Japan. The company is the parent of the Hitachi Group as part of the larger DKB Group companies... |
Hitachi Hitachi, Ltd. is a Japanese multinational conglomerate headquartered in Marunouchi 1-chome, Chiyoda, Tokyo, Japan. The company is the parent of the Hitachi Group as part of the larger DKB Group companies... |
Hitachi/Toshiba/GE General Electric General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States... |
Hitachi/Toshiba/GE General Electric General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States... |
The power installation costs for units at this site well reflect 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 Reactor
Advanced Boiling Water Reactor
The Advanced Boiling Water Reactor is a Generation III boiling water reactor. The ABWR is currently offered by GE Hitachi Nuclear Energy and Toshiba...
s (ABWRs) ever built.
Performance
Such a large plant size has several economic advantages, one of these being the limited impact of refueling outages of individual units on the plant's total 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. Unfortunately, since completion the plant has seen two events that caused the entire plant to be shut down. The last of these two events is ongoing and data is not available yet, data for the rest of the plant's history is shown below:| Unit 1 | Unit 2 | Unit 3 | Unit 4 | Unit 5 | Unit 6 | Unit 7 | Total | |
|---|---|---|---|---|---|---|---|---|
| 1985 | 4.960 | 4.960 | ||||||
| 1986 | 6.704 | 6.704 | ||||||
| 1987 | 9.195 | 9.195 | ||||||
| 1988 | 6.960 | 6.960 | ||||||
| 1989 | 6.442 | 1.041 | 7.484 | |||||
| 1990 | 5.987 | 5.386 | 7.911 | 19.284 | ||||
| 1991 | 9.032 | 6.642 | 7.093 | 22.767 | ||||
| 1992 | 6.958 | 9.047 | 0.053 | 6.977 | 23.035 | |||
| 1993 | 6.874 | 7.213 | 6.488 | 0.012 | 9.238 | 29.825 | ||
| 1994 | 7.020 | 7.291 | 7.264 | 6.040 | 7.155 | 34.771 | ||
| 1995 | 9.235 | 7.697 | 9.254 | 6.182 | 7.508 | 39.877 | ||
| 1996 | 6.814 | 8.811 | 7.922 | 8.068 | 7.906 | 5.663 | 0.058 | 45.242 |
| 1997 | 7.900 | 7.284 | 8.016 | 7.517 | 8.919 | 10.161 | 8.128 | 57.926 |
| 1998 | 6.176 | 8.142 | 6.748 | 9.259 | 7.353 | 10.702 | 9.716 | 58.095 |
| 1999 | 9.199 | 8.209 | 9.028 | 8.142 | 7.772 | 9.710 | 8.445 | 60.505 |
| 2000 | 7.715 | 8.140 | 7.945 | 6.919 | 7.043 | 9.412 | 11.240 | 58.413 |
| 2001 | 7.071 | 7.595 | 6.986 | 5.591 | 9.199 | 9.270 | 10.078 | 55.790 |
| 2002 | 5.906 | 5.866 | 5.576 | 9.240 | 8.191 | 11.504 | 7.990 | 54.273 |
| 2003 | 0.000 | 0.000 | 0.000 | 4.186 | 1.503 | 8.401 | 5.778 | 19.869 |
| 2004 | 6.497 | 4.660 | 6.550 | 5.624 | 6.135 | 8.635 | 10.805 | 48.906 |
| 2005 | 3.126 | 6.388 | 6.062 | 7.192 | 6.853 | 11.126 | 7.977 | 48.725 |
| 2006 | 6.299 | 9.331 | 7.331 | 2.817 | 8.400 | 8.447 | 8.166 | 50.792 |
| 2007 | 3.165 | 1.830 | 5.054 | 5.061 | 0.0 | 3.758 | 6.358 | 25.226 |
| 2008 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| 2009 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 3.654 | 5.366 | 9.02 |
| 2010 | 5.291 | 0.0 | 0.0 | 0.0 | 0.780 | 9.522 | 9.034 | 24.627 |
2002 Scandal shut downs
The reactors at the KK plant were shut down one by one after the discovery of deliberate falsification of data. The first one was taken offline September 9, 2002, and the last one was taken offline January 27, 2003. The newest units, the more inherently safe ABWRs, were taken back online the quickest and suffered the smallest effect. Units 1, 2, and 3 on the other hand, generated no electricity whatsoever during the entire fiscal year of 2003.Fuel
All reactors continue to use low-enriched uraniumUranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
as the nuclear fuel; however, there have been plans drafted by Tepco to use MOX fuel
MOX fuel
Mixed oxide fuel, commonly referred to as MOX fuel, is nuclear fuel that contains more than one oxide of fissile material. MOX fuel contains plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enriched uranium fuel used in the...
in some of the reactors by the permission of the Japanese Atomic Energy Commission
Japanese Atomic Energy Commission
The was established in 1956 and serves as the regulatory body for nuclear power in Japan. The Atomic Energy Basic Law contained a provision for its creation, and shortly after the law was enacted, the organization started activities, which are stated to be: assure that research and use of nuclear...
(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 the time, Nobuya Minami, announced that plans to use the MOX fuel at the KK plant would be suspended indefinitely.
Earthquakes
- See also: Nuclear power in Japan - Seismicity
Earthquake resistant design features
The foundation of the plant is very deep and goes through an unstable layer of sand down onto a sturdy layer of bedrock. Basements of the reactor buildings extend four levels down. These massive 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 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.
2004 Chūetsu Earthquake
In the 2004 Chūetsu earthquake2004 Chuetsu earthquake
The occurred at 5:56 p.m. on Saturday, October 23, 2004 . The Japan Meteorological Agency has named it the Heisei 16 Niigata Prefecture Chuetsu Earthquake or The Mid Niigata Prefecture Earthquake of 2004...
on November 4, 2004, devices around the base of the plant only measured 4 on the Japanese seismological intensity scale while other nearby places measured 6.
All of the reactors except for Unit 4 were operating normally at the time of the earthquake and continued to do so through the quake, Unit 4 was shut down due to routine maintenance. Unit 7 shut down during an aftershock because the turbine thrust bearing wear trip signal was activated.
2007 Chūetsu offshore earthquake
Richter magnitude scale
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....
6.6 2007 Chūetsu offshore earthquake
2007 Chuetsu offshore earthquake
The Chūetsu Offshore Earthquake was a powerful magnitude 6.6 earthquake that occurred 10:13 a.m. local time on July 16, 2007, in the northwest Niigata region of Japan. The earthquake shook Niigata and neighbouring prefectures...
, which took place 10:13 a.m., July 16, 2007. Shaking
Peak ground acceleration
Peak ground acceleration is a measure of earthquake acceleration on the ground and an important input parameter for earthquake engineering, also known as the design basis earthquake ground motion...
of 6.8 m/s² (0.69 g) was recorded in Unit 1 in the east-west direction, above the design specification for safe shutdown of 4.5 m/s², and well above the rapid restart specification for key equipment in the plant of 2.73 m/s². Units 5 and 6 also recorded shaking over this limit. Shaking of 20.58 m/s² 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 nearly completely charred.
Reactor units 2, 3, 4, and 7 all automatically powered down safely in response to the quake, while 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, July 18, the mayor of Kashiwazaki ordered operations at the plant to be halted until its safety could be confirmed. The Nikkei
Nihon Keizai Shimbun
is one of the largest media corporations in Japan. Nikkei specializes in publishing financial, business and industry news. Its main news publications include:* Nihon Keizai Shimbun , a leading economic newspaper....
reported that government safety checks could delay the restart for over a year, without stating the source of the information. For comparison, in 2005, a reactor at the Onagawa NPP
Onagawa Nuclear Power Plant
The is a nuclear power plant located on a 1,730,000 m2 site in Onagawa in the Oshika District and Ishinomaki city, Miyagi Prefecture, Japan. It is managed by the Tohoku Electric Power Company...
was closed for five months following an earthquake.
IAEA Inspections
The International Atomic Energy AgencyInternational Atomic Energy Agency
The International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons. The IAEA was established as an autonomous organization on 29 July 1957...
offered to inspect the plant, which was initially declined. The governor of Niigata prefecture
Niigata Prefecture
is a prefecture of Japan located on the island of Honshū on the coast of the Sea of Japan. The capital is the city of Niigata. The name "Niigata" literally means "new lagoon".- History :...
then sent a petition to Shinzo Abe
Shinzo Abe
was the 90th Prime Minister of Japan, elected by a special session of the National Diet on 26 September 2006. He was Japan's youngest post–World War II prime minister and the first born after the war. Abe served as prime minister for nearly twelve months, before resigning on 12 September 2007...
. On Sunday, July 22, the NISA
Nuclear and Industrial Safety Agency
The is a Japanese nuclear regulatory and oversight branch of the Agency for Natural Resources and Energy under the Ministry of Economy, Trade and Industry. It was created in 2001 during the 2001 Central Government Reform. It has a main office in Kasumigaseki, Chiyoda, Tokyo that works with the...
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 August 19, 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:
- "Safety related structures, systems and components of the plant seem to be in a general condition, much better than might be expected for such a strong earthquake, and there is no visible significant damage"
- Conservatisms introduced in the construction of the plant compensated for the magnitude of the earthquake being so much greater than planned for.
Recommendations included:
- A re-evaluation of the seismic safety.
- Detailed geophysical investigations
External inspections of 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 July 15, Akira Amari
Akira Amari
is a Japanese politician of the Liberal Democratic Party and a member of the lower house. He was the Minister of Economy, Trade and Industry from 2006 to 2008 and is currently Minister of State in charge of Administrative Reform....
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 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 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.
Radiation Releases
Initially, it was thought that some water (estimated to be about 1.5 L) from the spent fuel poolSpent fuel pool
Spent fuel pools are storage pools for spent fuel from nuclear reactors. They are typically 40 or more feet deep, with the bottom 14 feet equipped with storage racks designed to hold fuel assemblies removed from the reactor. A reactor's pool is specially designed for the reactor in which the...
leaked into the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
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 the NISA
Nuclear and Industrial Safety Agency
The is a Japanese nuclear regulatory and oversight branch of the Agency for Natural Resources and Energy under the Ministry of Economy, Trade and Industry. It was created in 2001 during the 2001 Central Government Reform. It has a main office in Kasumigaseki, Chiyoda, Tokyo that works with the...
, this was the first time a release of radioactive material happened as a result of an earthquake.
- 0.6 litres of slightly radioactive water leaked from the third floor of the Unit 6 reactor building, which contained 280 becquerelBecquerelThe becquerel is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The Bq unit is therefore equivalent to an inverse second, s−1...
s of radioactivity. (For reference, a household smoke detector typically contains 37,000 Bq (1.0 microcuries) of radioactivity, and a living adult human typically has around 8000 Bq of naturally occurring radioactivity inside his or her body.) - 0.9 litres of slightly radioactive water leaked from the inner third floor of the Unit 6 reactor building, containing 16,000 Bq of radioactivity.
- From unit 6, 1.3 cubic meters of water from the spent fuel pool leaked from the pool, and flowed into through a drainage pipe, ultimately into the Sea of Japan. The water contained 80 Bq/LLitrepic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...
, totaling 90,000 Bq in the release. For comparison, an OnsenOnsenAn is a term for hot springs in the Japanese language, though the term is often used to describe the bathing facilities and inns around the hot springs. As a volcanically active country, Japan has thousands of onsen scattered along its length and breadth...
located in Misasa, TottoriMisasa, Tottoriis a town located in Tōhaku District, Tottori, Japan. It is also home to the official treasure of Sanbutsuji and the Okayama Hospital.The name "Misasa" originates from the belief that one who stays to enjoy three mornings in the town's famous hot springs will find all of his ailments cured.As of...
, JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
uses water with a large concentration of radonRadonRadon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium or thorium. Its most stable isotope, 222Rn, has a half-life of 3.8 days...
, which gives it a radioactivity of 9300 Bq/L. The leaked water from the plant did not pose a health risk even before being diluted. Towels were used to mop up the water. - On Wednesday, 18 July 2007, at Unit 7, radioactive iodineIodineIodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
was found leaking from an exhaust pipe by a government inspector, the leak began between Tuesday and Wednesday and was confirmed to have stopped by Thursday night. The amount of iodine released was estimated at 12 million Bq. and the total amount of particulate radioactivity released into the air was about 402,000,000 Bq. This was said to have been one 10 millionth of the legal limit. It is estimated that this caused an unintentional dose of 0.0002 nanosieverts (nSv)SievertThe sievert is the International System of Units SI derived unit of dose equivalent radiation. It attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to just the absorbed dose of radiation energy, which is measured in gray...
, per person distributed among around 10 million people. The limit for dose to the public from the operations of a nuclear plant in Japan in one year is 1100 nSv, and, for comparison, natural background radiation worldwide for humans is on average around 2 400 000 nSv/year (2.4 mSv/year). In regards to the cause, Yasuhisa ShiozakiYasuhisa Shiozakiis a Japanese politician who served as Chief Cabinet Secretary to Prime Minister Shinzō Abe until August 2007.Born in Matsuyama, Ehime Prefecture, he was an AFS exchange student in high school, graduated with a liberal arts degree from the University of Tokyo and attended the John F. Kennedy School...
said "This is an error of not implementing the manual," because the vent should have been closed.
Other Problems
Aftershock
An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...
s, 40 losing their lids. Company officials reported on July 17 that traces of the radioactive materials cobalt-60
Cobalt-60
Cobalt-60, , is a synthetic radioactive isotope of cobalt. Due to its half-life of 5.27 years, is not found in nature. It is produced artificially by neutron activation of . decays by beta decay to the stable isotope nickel-60...
, iodine, and chromium-51 had been released into the atmosphere, presumably from 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, in fact, 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 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 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 a host of other factors).
Tepco's president maintained that fears of a radiation leak 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
International Atomic Energy Agency
The International Atomic Energy Agency is an international organization that seeks to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons. The IAEA was established as an autonomous organization on 29 July 1957...
's Mohamed ElBaradei encouraged full transparency throughout the investigation of the accident so that lessons learned could be applied to nuclear plants elsewhere.
Impact
News of 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 4.4 billion USD 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 a power shortage during the summer months. Trade minister Akira AmariAkira Amari
is a Japanese politician of the Liberal Democratic Party and a member of the lower house. He was the Minister of Economy, Trade and Industry from 2006 to 2008 and is currently Minister of State in charge of Administrative Reform....
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
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
coast, even as far as Murakami, Niigata
Murakami, Niigata
is a city located in northern Niigata, Japan.On April 1, 2008, the city merged with the towns of Sanpoku and Arakawa, and the villages of Asahi and Kamihayashi, all from Iwafune District....
(140 km northeast) and Sado Island. Inn owners have said that rumors have been more damaging than direct effects of the earthquake.
Shutdown Alternatives
The shutdown forced TEPCO to run natural gasNatural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
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 a hard time meeting the Kyoto Protocol
Kyoto Protocol
The Kyoto Protocol is a protocol to the United Nations Framework Convention on Climate Change , aimed at fighting global warming...
.
Restart
After 16 months of comprehensive component-based assessment and upgrades on all seven reactors, this phase of post-earthquake response 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 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 the same week that fuel loading for unit 3 started.
2011-2012: Survey on Tsunami's in the past
On 10 November 2011 TEPCO announced a survey for signs of past tsunami's 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 tsunami's than were expected, when the plant was designed and built.Facility improvements after Fukushima I nuclear accidents
After Fukushima I nuclear accidents, TEPCO announced on 21 April 2011, the plan to build up the seawallSeawall
A seawall is a form of coastal defence constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a seawall is to protect areas of human habitation, conservation and leisure activities from the action of tides and waves...
, to a height of 15 m (49.2 ft) above sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
, more than 800 m (2,624 ft) in length for units 1- 4, and more than 500 m (1,640 ft) for unit 5-7 by June 2013, which has been assumed 3.3 m height of tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
. Also, plans have been made to rebuild the storage pool for radioactive water overflow by September 2012.
Events
By Japanese law (and other countries have similar reporting), utilities operating nuclear plants must report certain kinds of events (power excursions, high dose to a worker, or accidents) to the NISANuclear and Industrial Safety Agency
The is a Japanese nuclear regulatory and oversight branch of the Agency for Natural Resources and Energy under the Ministry of Economy, Trade and Industry. It was created in 2001 during the 2001 Central Government Reform. It has a main office in Kasumigaseki, Chiyoda, Tokyo that works with the...
and METI. Some of the events listed below didn't necessarily fit this category but TEPCO decided to officially report them anyway.
- In May 2000, Unit 6 had to be shut down as a precautionary measure when increased concentrations of IodineIodineIodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
were detected in the coolant loop. - On June 12, 2004, the vacuum in the condenser in Unit 1 began to decrease. The operators reduced power, and the condenser pressure stabilized so the unit was run at the lower power of 800 MW for some time.
- On February 4, 2005, Unit 1 was manually shut down due to leakage of steam in the lower floor of the turbine room.
- On July 3, 2005, the Unit 5 reactor tripped by a turbine trip caused by a decreased vacuum in the condenser (turbine trip occurs to protect the turbine).
- On May 26, 2006, TEPCO and the Chūbu Electric Power CompanyChubu Electric Power Company, abbreviated as Chuden in Japanese, is the electric provider for the middle Chūbu region of the Honshū island of Japan. It provides electricity at 60 Hz, though an area of Nagano Prefecture uses 50 Hz. Chubu Electric Power ranks third among Japan’s largest electric utilities in terms of power...
submitted a report about cracking in the hafniumHafniumHafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable...
control blades. - On July 12, 2006, it was discovered that a worker was exposed to radiation above the 0.8 millisievertSievertThe sievert is the International System of Units SI derived unit of dose equivalent radiation. It attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to just the absorbed dose of radiation energy, which is measured in gray...
legal limit in one day, receiving 1.03 millisieverts. - On July 16, 2007, the 2007 Chūetsu offshore earthquake2007 Chuetsu offshore earthquakeThe Chūetsu Offshore Earthquake was a powerful magnitude 6.6 earthquake that occurred 10:13 a.m. local time on July 16, 2007, in the northwest Niigata region of Japan. The earthquake shook Niigata and neighbouring prefectures...
caused severe damage to parts of the plant, resulting in small radioactive releases, complete shutdown and seismic upgrades. - On September 20, 2007, a temporary air conditioner on the roof of the plant caught fire, but there was no danger of a radioactive leakLeakA leak is a hole or other opening, usually unintended and therefore undesired, in a container or fluid-containing system, such as a tank or a ship's hull, through which the contents of the container can escape or outside matter can enter the container...
. - On May 22, 2008, TEPCO announced that earthquake resistance standards needed to be increased by a factor of five and work to reinforce the reactors would begin in June.
- On August 5, 2011, in the afternoon the output of reactor 1 was reduced, and the next day the reactor would stop completely. This was done for a 2-month inspection. It was the first reactor run by TEPCO, to undergo an inspection since the nuclear accident at the Fukushima. Another reactor at the Kashiwazaki-Kariwa plant was scheduled for a regular inspection late August 2011. Niigata Governor Hirohiko Izumida said, that he won't give permission for any restart of a reactor, before the cause of the accident at the Fukushima plant would be revealed.
- On 22 August 2011 reactor nr.7 was taken offline for regular inspections. The normal time for this checkup was about 3 months.
- On 9 September 2011 TEPCO started with stress-tests to confirm the safety of two of its idle nuclear reactors. A computer-simulation was to used to confirm the reactors' earthquake and tsunami resistance. This test was introduced after the triple meltdown at the Fukushima-accident. All reactors in Japan needed to pass this test after their normal regular inspections before they were allowed to resume operation. The Governor of NiigataNiigatais a name of a place of Japan and the Chubu region.Niigata may refer to:* Niigata - a city in Japan and the capital of Niigata Prefecture* Niigata Prefecture - prefecture in Japan* Albirex Niigata - the city's professional football club...
Hirohiko IzumidaHirohiko Izumidais the governor of Niigata Prefecture since October 25, 2004.- Personal history :* September 15, 1962: Born in Kamo in Niigata Prefecture.* 1981: Graduated from Sanjo High School.* 1987: Graduated from Kyoto University Law Department....
said that he would not take any decision about a restart before the Fukushima accident would be properly assessed.
1,000,000 Volt Electric Line
There had been plans to supply some areas by means of a 1,000,000 V power lineKita–Iwaki powerline
The Kita–Iwaki Powerline is the largest double-circuit powerline for three-phase electric power in the world, which was built in 1999. It runs from Minami-Iwaki to Higashi-Yamanashi and has 2 circuits, which are operated at present with 500 kV, but can be switched over to 1100 kV if necessary...
; however, objections from the local community due to concerns of electromagnetic waves stopped the plan. This would have been Japan's first electric line of that scale.
Juridical actions against restarting nuclear powerplants
In August 2011 citizens of the prefecture Shiga, at the banks of Lake BiwaBiwa
The is a Japanese short-necked fretted lute, often used in narrative storytelling. The biwa is the chosen instrument of Benten, goddess of music, eloquence, poetry, and education in Japanese Shinto....
, started a law suit at the Otsu District Court, and asked a court order to prevent the restart of seven reactors operated by Kansai Electric Power Company
Kansai Electric Power Company
, also known as , is an electric utility with its operational area of Kansai region, Japan . The company is regarded as one of the leading companies in Kansai, as well as a leader of the Japanese electric power industry....
, in the prefecture Fukui
Fukui
Fukui is a Japanese name meaning "fortunate" or it can mean "one who is from the Fukui prefecture". It may refer to:- Places :* Fukui Prefecture** Fukui, Fukui - the city of the same name in the prefecture...
.
External links
Niigata Chuetsu Offshore Earthquake related- Niigata Chuetsu Offshore Earthquake impacts — Japan Atomic Industrial Forum
- Earthquake impacts — Japan Nuclear Technology Institute
- View on earthquake events — Japan's Nuclear Safety CommissionNuclear Safety CommissionNuclear Safety Commissions are governmental nuclear power and materials watchdogs and may refer to:* Canadian Nuclear Safety Commission* Japanese Nuclear Safety Commission...
- Kashiwazaki-Kariwa Earthquake — Japan's Citizens' Nuclear Information Center Report
- Kashiwazaki nuclear plant — report from the scene — GreenpeaceGreenpeaceGreenpeace is a non-governmental environmental organization with offices in over forty countries and with an international coordinating body in Amsterdam, The Netherlands...
- Insight: Where not to build nuclear power stations — New ScientistNew ScientistNew Scientist is a weekly non-peer-reviewed English-language international science magazine, which since 1996 has also run a website, covering recent developments in science and technology for a general audience. Founded in 1956, it is published by Reed Business Information Ltd, a subsidiary of...
- Japan’s Quake-Prone Atomic Plant Prompts Wider Worry — The New York TimesThe New York TimesThe New York Times is an American daily newspaper founded and continuously published in New York City since 1851. The New York Times has won 106 Pulitzer Prizes, the most of any news organization...
Entire plant related
- Tokyo Electric Company Official Site for Kashiwazaki-Kariwa 東京電力・柏崎刈羽原子力発電所 (Japanese)
- Power plant on-line monitor This shows output power, click on icons at top left to see three different radiation monitors. (Japanese)
- Nuclear TEPCO-Power Plants (English)
- List of events at the plant (English)