20110327 Fukushima Earth Quake Influence(Fepc)


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Possible Influence of Fukushima Daiichi
NPP Accident Caused by Tohoku Pacific
Offshore Earthquake, Public Relations Division of the Federation of Electric Power Companies (Japan)

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20110327 Fukushima Earth Quake Influence(Fepc)

  1. 1. 9:00 on March 27, 2011Possible Influence of Fukushima DaiichiNPP Accident Caused by Tohoku Pacific Offshore Earthquake Public Relations Division, FEPC The Federation of Electric Power Companies 1
  2. 2. We offer our sincerest condolences to the casualties of the Tohoku Earthquakeand subsequent tsunami on March 11. We are extremely aware of the serious concerns and difficulties caused by theaccident at TEPCO’s Fukushima Daiichi Nuclear Power Plant and consequentrelease of radioactive material, both for those living nearby and the widerpublic, and we most deeply apologize for this situation. Working with the support of the Japanese Government and related agencies,TEPCO is making utmost efforts to prevent the situation from deteriorating,and the electricity industry as a whole is committing all its resources, includingvehicles, equipment, and manpower, to assist in these efforts. The Federation of Electric Power Companies 2
  3. 3. Outline of Tohoku-Pacific Ocean EarthquakeDate of occurrence: 14:46 on Friday, March 11,2011Epicenter: Offshore Sanriku (38ºN, 142.9ºE),Depth of hypocenter: 24 km (tentative value),Magnitude: 9.0 Hypocenter and seismic intensitySeismic intensity 7: Kurihara city, Miyagiprefecture Press release at 14:53 on March 11, 2011Upper 6: Hitachi city, Ibaraki prefecture,Naraha-cho, Tomioka-cho, Okuma-machi, Nuclear reprocessingFutaba-cho, Fukushima prefecture, Natori city, facilitiesMiyagi prefecture, etc.Lower 6: Ofunato city, Ishimaki city, Onagawa-cho, Miyagi prefecture, Tokai village, Ibarakiprefecture, etc. HypocenterUpper 5: Miyako city, Iwate prefecture,Fukushima city, Fukushima prefecture, Taihaku Fukushima NPPward, Sendai city, Miyagi prefectureLower 5: Kuji city, Iwate prefecture, Kariiwa Epicenter Seismic Upper 6 Lower 6 Upper 5 Lower 5villate, Niigata prefecture Intensity 7 Legend 4 3 2 14: Rokkasho village and Higashidori village,Aomori prefecture, Kashiwazaki city, Niigataprefecture, Tadami-cho, Fukushima prefecture The Federation of Electric Power Companies 3
  4. 4. Current Status of NPPs Affected by the Earthquake Tohoku Electric Higashidori NPP Cold shutdown (with cooling water Unit 1 below 100ºC) Hot shutdown Reactor shutdown for outage JNFL reprocessing plant: no significant event Numbers in parentheses show the time of Tohoku Electric Onagawa NPP cold shutdown. Unit 1 Unit 2 Unit 3 *Cooling water temperature was 100ºC because the units ( 0:58 on Mar. 12) (*) (1:17 on Mar. 12) had just been started up. Tokyo Electric Fukushima Daiichi NPP (as of 09:00 on March 16) Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6Radius of 20-30 Units 1 Units 3 – Continuing injecting freshwater to cool down the reactor – Continuing injecting freshwater to cool down the reactorkm: Staying – Internal gas release (venting) to depressurize the pressure vessel – Internal gas release (venting) to depressurize the pressure vesselindoors – A hydrogen explosion blew off the roof of the reactor building – A hydrogen explosion blew off the roof of the reactor building. – External power was restored. (Checking integrity of machinery) – Seawater spray and injection into the spent fuel pool – External power was restored. (Checking integrity of machinery) Units 2 – Continuing injecting freshwater to cool down the reactor Units 4 – Internal gas release (venting) to depressurize the pressure vessel – fire broke out (the reactor building was damaged). – An explosion sound (the suppression chamber damage suspected). – Seawater spray and injection into the spent fuel pool.Within 20 km – Seawater was sprayed into the spent fuel pool. – External power was restored. (Checking integrity of machinery)radius: – External power was restored. (Checking integrity of machinery)evacuation Tokyo Electric Fukushima Daiichi NPP (as of 09:00 on March 16) Unit 1 Unit 2 Unit 3 Unit 4 17:00 on Mar. 14 18:00 on Mar. 14 12:15 on Mar. 12 7:15 on Mar. 15 JAPC Tokai II NPP 0:40 on Mar. 15 The Federation of Electric Power Companies 4
  5. 5. Current Status of Fukushima Daiichi NPPControl rods were inserted to shut the reactor down following signals received from seismometers.The operating plant automatically shutdown, which means the shutdown function worked.The loss of cooling function at units 1, 2 and 3 caused the temperature and pressure inside the reactorpressure vessel to rise, leading to a release of radioactive materials out of the reactor. Shutdown Containment Cool down Control rods Suppression pool The Federation of Electric Power Companies 5
  6. 6. Current Status of Fukushima Daiichi NPP Before the quake 4 3 2 1 Tsunami possibly flooded upAfter the quake to this line? Circulating water pump Seawater Seawater pump Intake Heavy oil tank The Federation of Electric Power Companies 6
  7. 7. What Happened Following Loss of Off-site Power Supply• The plant was designed so that: In case of loss of external power supply, the control rods that suppress nuclear fissions are automatically inserted into the reactor by water pressure to scram the reactor immediately (shutdown). At the same time, emergency diesel generators are automatically started up to supply the necessary electricity. Following this earthquake, the reactor shutdown function worked properly, but the emergency diesel generators failed after starting up, causing loss of function to cool the reactor. Shutdown Control rods are Reactor is scrammed inserted Loss of power supply Cooling down Emergency diesel Reactor cooling generator start-up The Federation of Electric Power Companies 7
  8. 8. •The action to gradually reduce pressure inside the containment vessel to preventdamage to the containment vessel is called ventilation (venting). The relief valves areopened to release gas from the containment vessel and then the gas is discharged fromthe vent stack after iodine and other radionuclides have been absorbed to some extentby the water in the pressure suppression pool. This action maintains the integrity andcontainment function of the containment vessel. Containment vessel Vent stack Reactor pressure vessel Safety-relief valve G Containment vessel vent line Rupture disk Relief valve Relief valve Suppression pool The Federation of Electric Power Companies 8
  9. 9. To submerge the fuel in water to maintain reactor safety: Water is being injected into the pressure vessel through the fire prevention system piping from the filtered water tank at the site. Water is being injected into the pressure vessel by connecting fire engines to the fire prevention system piping. To overcome the accident, Fukushima Daiichi is using filtered water, fire-fighting water and seawater as the water source. Boron is also being injected, which absorbs neutrons, to improve the safety. Containment vessel Reactor pressure vessel Turbine Generator Fire pump Boron storage pit Filtered water tank Reactor recirculation Fire engines pump Fire engines(Pumper trucks) (Pumper trucks) 5 vehicles Suppression 2-3 vehicles pool Sea Sea The Federation of Electric Power Companies 9
  10. 10. Differences between Exposure and Contamination According to the press release, the measured radioactive contamination of an evacuee was 40,000 cpm, which means a radiation exposure of approximately 0.18 mSv per hour in terms of the effect on the human body. *Calculated values may differ if different types of instruments are used.Radiation exposure: A person is exposed to radiation. External exposure External exposure occurs when the radiation source (radioactive material, etc.), such as roentgen, is outside the human body. Measured values are represented as radiation dose per hour (in sieverts/hour, millisieverts per hour, or microsieverts per hour). 1 sievert = 1,000 millisieverts (mSv) = 1,000,000 microsieverts ( Sv) External exposure Internal exposure Internal exposure occurs when radioactive material is taken into the human body by people swallowing radioactive materials or breathing contaminated air. It is measured in radiation counts per minute (cpm). Internal exposureContamination: Radioactive contamination occurs when radioactive material is deposited on the surface of skin or clothes. A contaminated person will be continuously exposed to radiation until the radiation source (radioactive material) is removed. It is measured in radiation counts per minute (cpm). Contamination The Federation of Electric Power Companies 10
  11. 11. Possible Health Effects of Radiation on Local Residents The exposure dose received by local residents following the accident is unclear so far (to be surveyed). The average person receives roughly 2.4 millisieverts (mSv) of radiation exposure, both internal and external, a year due to exposure to natural sources in daily life (as global average). No health effects have been observed from radiation exposure below 100 mSv. The amount of radiation 10,000 mSv or (mSv) higher Skin exposure Acute ulcers *Health effects of radiation released by the With clinical manifestation 5,000 mSv 7,000-10,000 mSv 100% mortality JCO criticality accident Skin exposure The exposure dose received by local residents Local exposure Erythematous macule Whole body exposure Lens exposure Cataract living on the west boundary of the JCO site 2,500-6,000 mSv was 16 millisieverts at the highest. Gonad exposure 3,000-5,000 mSv Permanent infertility 50% mortality The level of detected radioactive material 3,000 mSv 1,000 mSv within a 10-kilometer radius from the facility Nausea and vomiting (10% of Skin exposure population) was low enough not to affect the health of Acomia local residents or the environment. 500-2,000 mSv 500 mSv Lens exposure Decrease in peripheral blood Opacity of the lens lymphocytes 10 mSv 6.9 mSv Chest computed tomography scan Natural background in (CT scan) Guarapari, Brazil 1.0 mSvFrom space 2.4 mSv Annual dose limit for Without clinical manifestation 0.39 mSv (World average) members of the public From radon Natural background (excluding radiotherapy) in the air received per capita 0.38 mSv 1.26 mSv (per year) Difference in natural 0.6 background radiation between Gifu and Kanagawa (per year) X-ray of the stomach (the largest difference between (once) prefectures) From food 0.19 0.05 mSv 0.29 From ground Air flight between Chest X-ray (once) 0.48 Tokyo and New York (round-trip) 0.05 mSv Notes (Cosmic rays increase Annual target dose in the 1. The numerical values in this drawing are shown: with altitude.) area surrounding a nuclear power (I) in terms of effective dose or equivalent dose, and (II) in line with a report by the United Nations Scientific Committee on the Effects of plant (LWR) Atomic Radiation. (Actual records are significantly 2. Natural background radiation includes the effect of breathing radon (according to a report by the National Institute of Radiological Sciences). lower than this target value.) The Federation of Electric Power Companies 11
  12. 12. Possible Health Effects of Radiation on Workers? Personal dosimeter with alarm functionA personal dosimeter is always worn byworkers during work to measureradiation exposure. The digital displayshows the exposed dose directly. Analarm and sound are issued if theexposed dose exceeds the preset value. The Federation of Electric Power Companies 12
  13. 13. Notification according to Act on Special Measures concerning Nuclear Emergency Preparedness Articles 10 &15Following the release of radioactive material from Fukushima Daiichi NPP, local residents living in a 20-km radiuswere ordered to evacuate and those living in a 20- to 30-km radius to stay indoors according to the Act on SpecialMeasures concerning Nuclear Emergency Preparedness, Articles 10 and 15 respectively.This Act was enacted in June 2000 to improve disaster prevention measures, including the initial response in case of anaccident, as well as cooperation between the national government and prefectures/municipalities based on the lessonslearned from the JCO criticality accident in September 1999. Occurrence of an event requiring notification Nuclear emergency (according to Article 10 of (according to Article 15 of the Act on Special the Act on Special Measures concerning Measures concerning Usual trouble Nuclear Emergency Nuclear Emergency Preparedness) Preparedness) Level of 5 sV/h around the plant 500 sV/h around the radiation and site boundary (continued plant site boundary accident for 10 minutes) (continued for 10 minutes) severity Occurrence of an event A nuclear emergency which may lead to an event (e.g., complete lack emergency (e.g., of water injection from unavailability of a part of the emergency core Emergency Core Cooling cooling system) System) Mihama-2 SG tube rupture TMI accident (March 1979) accident (February 1991) (Approximately 600 Sv/h (ECCS was actuated.) was measured around the plant site.) JCO accident (September 1999) (The highest radiation level of Article 10 Article 15 840 Sv/h was measured.) The Federation of Electric Power Companies 13
  14. 14. Appropriateness of a 20-km Radius Evacuation AreaRadioactive material released into the air is carried downwind and dispersed depending on the windvelocity and atmospheric stability.The radiation dose rate on the ground surface, which is relatively high at the point of release, decreasesfurther downwind as radioactivity is weakened by diffusion.Therefore, the central government of Japan designates an evacuation area to minimize the health effectsof radiation. Atmospheric stability Distribution of ground spatial radiation dose rate on the Strong instability (Class A) downwind axis depending on atmospheric stability 2 1 10 Neutral (Class D) 3 1 10 Medium instability (Class B) Radiation dose rate 4 1 10 Stable (Class E-F) 5 1 10 Weak instability (Class C)( / ) 6 1 10 Atmospheric stability: An indicator of the degree of air movement and diffusion 7 1 10 in the vertical direction. It depends on the intensity of solar radiation and wind, 1 100 0 1 10 and is used to predict the diffusion of atmospheric material. Downwind distance ( ) As instability increases, atmospheric material is more easily diffused; as stability increases, atmospheric material becomes harder to diffuse. It ranges from A (very unstable) to F (stable), with intermediate stability from B to E. The Federation of Electric Power Companies 14
  15. 15. What Does the Detection of Cesium and Iodine Mean? Cesium and iodine, which are radioactive materials, do not exist in nature, but are fission productsgenerated from the fission of uranium and plutonium.* Cesium and iodine produced by nuclear tests in the past and the Chernobyl accident exist in Japan. It is suspected that fission products, which should be contained in fuel pellets and fuel cladding, havebeen released with gases due to continued abnormal conditions. Cesium 135/137 Iodine 129/131 Uranium 235 Fuel for nuclear power Fission generation Strontium 90 92 protons 143 neutrons Krypton 85 * Cesium and iodine are similar to other radioactive materials in terms of health effects of external exposure. The Federation of Electric Power Companies 15
  16. 16. Are Milk and Spinach Safe when Excess Radioactive Materials Are Detected? The provisional limits settled in line with the Food Sanitation Act are strict (with a wide safetymargin) taking into consideration long term ingestion, and so ingesting milk and spinach at thislevel would not immediately affect human health. Transfer in the environmentAccording to the government;The cumulative radiation dose in one year if a person wereto keep drinking milk with the detected level would beequivalent to 6.9 millisieverts (same as a CT scan).According to the government;The cumulative radiation dose in one year if a person were tokeep eating spinach with the detected level would beequivalent to 1.4 millisieverts (one-fifth of a CT scan). The Federation of Electric Power Companies 16
  17. 17. The Federation of Electric Power Companies 17
  18. 18. Has Dangerous Plutonium been Released from the MOX in Fukushima Daiichi Unit 3? There is no difference in released radioactive material between a uranium fuelreactor and MOX fuel reactor because plutonium is produced during power generationin a uranium fuel reactor. In-core years * At Fukushima Daiichi Unit 3, there are 32 One year Two years Three years MOX fuel assemblies among 548 fuel Electricity generated by uranium 238: 7% assemblies in total. Ratio of power generation In uranium fuel, uranium 238 absorbs neutrons Electricity generated by uranium 235: 63% and plutonium is produced by fission inside the reactor. Uranium fuel remains in the reactor for 3 to 4 years to continuously generate power. After 3 to 4 years of use, about 60% of the electricity comes from plutonium. Electricity generated by plutonium: 30% Burnup ratio (megawatt day/ton) The Federation of Electric Power Companies 18
  19. 19. Outline of Chernobyl Accident•Outline of the accident at Chernobyl (former Soviet Union, 1986): A rapid increase in power output occurred during low-power operation for an extended period of time,which was prohibited, damaging the core. As the type of the reactor was unique to former Soviet Unionand the reactor wasn’t made of steel, moreover, there was no containment vessel, it was impossible toseal radioactive material. Both the reactor and building cracked, causing the release of a large amount ofradioactive material. Structure of Chernobyl power plant Control room: There is a switch to turn off the When the Chernobyl accident occurred: safety system. Absence of containment vessel About 135,000 people living within a 30-km radius were evacuated. Fuel Mixture of water A person received a dose of 120 millisieverts Steam-water and steam on average. separator Control rod Steam About 50 people were exposed to radiation during fighting a fire. Turbine Generator Water Condenser Pressure Main circulation Cooling water tube pump Cooling water Moderator: graphite Coolant: water Pump Japanese reactor Chernobyl reactor Self-control ability Yes Possibility of loss Coolant Water Water Neutron moderator Water Graphite Safety system Preventing risky operation by interlock function Easy to be removed Rigid containment vessel enclosing the reactor Yes No The Federation of Electric Power Companies 19
  20. 20. Outline of Three Mile Island AccidentOutline of TMI accident (U.S.A., 1979) When the main feedwater pumps and valves malfunctioned, operators made multiple mistakes, including accidentally shutting down the emergency core cooling system, which caused a loss of inventory of reactor coolant and fuel damage. However, the containment of radioactive material remained intact, and thus only a small amount of radioactive material was released, causing no health effect. Containment vessel Structure of TMI NPP Blow-off did not close Turbine building Pressurizer Steam relief valve Refueling water tank Mal-indication of water gage Pressurizer Steam Manual shutdown generator Generator Reactor vessel G Turbine (ECCS) Main feedwater pump Relief to atmosphere Condenser Reactor coolant Purification Auxiliary building pump system Condensate tank Manual shut down Water transport Valve was closed Pressure relief Water holding tank Transfer pump system Quench tank Auxiliary feedwater pump“China Syndrome” is a term coined in the U.S. for an exaggerated core meltdown accident, in which the core at a nuclear power plant in theU.S. melts down, penetrates the earths crust, and reaches the opposite side of the earth (China). The phrase was used as the title of anAmerican film about a nuclear power plant accident. The Federation of Electric Power Companies 20
  21. 21. Level of Fukushima Daiichi NPP Accident General description of INES levels Examples INES Level Radiological Barriers and People and Environment Defence-in-Depth of Events Control Major release of radioactive material with Chernobyl, Major widespread health and environmental Accident effects requiring implementation of 1986 Level 7 planned and extended countermeasures. Serious Significant release of radioactive material Accident likely to require implementation of Level 6 planned countermeasures. Severe damage to reactor core.Accident Accident with Limited release of radioactive material Release of large quantities of radioactive Wider likely to require implementation of some material within an installation with a high Three Mile Consequences planned countermeasures. probability of significant public exposure. Island, USA, Level 5 Several deaths from radiation. This could arise from a major criticality 1979 accident or fire. Fuel melt or damage to fuel resulting in Accident with Minor release of radioactive material more than 0.1% release of core inventory. Local unlikely to result in implementation of Release of significant quantities of Tokaimura Consequences planned countermeasures other than radioactive material within an installation (JCO), Level 4 local food controls. with a high probability of significant Japan, 1999 At least one death from radiation public exposure. Exposure rates of more than 1 Sv/h in an Near accident at a nuclear power plant with no Serious Exposure in excess of ten times the operating area. safety provisions remaining. Incident statutory annual limit for workers. Non-lethal deterministic health effect Severe contamination in an area not Lost or stolen highly radioactive sealed source. Level 3 (e.g., burns) from radiation. expected by design, with a low Misdelivered highly radioactive sealed source probability of significant public exposure. without adequate procedures in place to handle it. Significant failures in safety provisions but with no Radiation levels in an operating area of actual consequences. Exposure of a member of the public in more than 50 mSv/h. Found highly radioactive sealed orphan source, Incident excess of 10 mSv. Significant contamination within the device or transport package with safety provisionsIncident Level 2 Exposure of a worker in excess of the facility into an area not expected by intact. statutory annual limits. design. Inadequate packaging of a highly radioactive sealed source. Overexposure of a member of the public in excess of statutory annual limits. Anomaly Minor problems with safety components with Mihama, Level 1 significant defence-in-depth remaining. Japan, 2004 Low activity lost or stolen radioactive source, device or transport package.Below Deviation 0+Scale (Below Scale/ Level 0) 0- Out of Scale Events of no safety relevance The Federation of Electric Power Companies 21
  22. 22. Seismic Safety of Nuclear Power PlantsCountermeasures against earthquake: Nuclear power plants are designed to withstand possible earthquakes or severer. Countermeasures against earthquakes Plant design Automatic Countermea Thorough Install plants on with Demonstratio shutdown sures against survey strong supporting sufficient n test function tsunami bedrock safety margin The validity of the seismic safety of a nuclear power plant is judged according to the “Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities” (revised in 2006) established by the Nuclear Safety Committee. Each nuclear power plant assumes an earthquake and tsunami, which are expected to pose the highest risks. Countermeasures against tsunami: A nuclear power plant is designed allowing a sufficient margin of elevation of the plant site above sea level based on the largest tsunami predicted from past records according to the concept of the Review Guide for Safety Design and Tsunami Assessment Method (Japan Society of Civil Engineers). According to this concept, at Fukushima Daiichi, seawater pumps required for cooling in case of an emergency were installed at +5.6m above the reference sea level. The Federation of Electric Power Companies 22
  23. 23. Tsunami Countermeasures at Nuclear Power PlantsCase for Fukushima Daiichi NPP Ground level of the site 10 m Predicted maximum amplitude of tsunami Sea water pump Sea level criteria: +5.7 m Emergency diesel generator (Basement of the turbine building) Sea level criteria: -3.6 m Predicted minimum amplitude of tsunamiComparison among NPPs Level for authorized Predicted tsunami level (Japan Tsunami level of current reactor installation Society of Civil Engineers) Tohoku earthquake Onagawa 9.1m 13.6m Unknown Fukushima Daiichi 3.122m 5.4 5.7m >14 m Fukushima Daini 3.122 3.705m 5.1 5.2m >10 m The Federation of Electric Power Companies 23
  24. 24. Past Experience with Rolling BlackoutsIn Japan, power consumption was restricted due to insufficient electricity following the chaos after WorldWar II (1946 to 1947) and at the beginning of establishment of 9 electric power utilities. * Kansai Electric Power Co.,Ink implemented rolling blackouts in 1952 due to an imbalance in demand and supplycaused by a drought.In California, excessive electricity deregulation caused an imbalance in demand and supply, resulting inrolling blackouts in 2001.* Due to electricity deregulation implemented since 1998, utilities were unwilling to build new plants and theelectricity supply did not sufficiently increase in California. Meanwhile, the concentration of IT firms in SiliconValley led to a surge in electricity demand, exacerbating the electricity shortage, resulting in six rolling blackoutsin January, March and May 2001. The blackouts caused factories to shut down, put automatic teller machines outof service, and stopped traffic lights, which caused traffic accidents.During the oil crisis in Japan, electricity consumption was restricted due to the possible shortage of fuel forpower generation according to the Electricity Business Act, Article 27. Large customers (highest contractelectricity: 500 kW or more) were ordered to reduce their power consumption by 15%. The use of non-urgent electricity, such as for neon and advertising lights, was prohibited in principle.* Electricity Utilities Industry Law, Article 27 (outline)The Minister of Economy, Trade and Industry has the authority to restrict power consumption and set an upper limitwithin a required range when a power shortage will adversely affect the economy, peoples lives, and publicinterest.* The order to restrict electricity consumption was approved at a Cabinet meeting on January 11, 1974; it continuedto the end of May 1974. The Federation of Electric Power Companies 24
  25. 25. Possibility of Electric Power Exchange The exchange of electric power between western Japan (60 Hz) andeastern Japan (50 Hz) must go through frequency converters with atotal installed capacity of 1,000 MW There are three frequency converters between Tokyo Electric PowerCo.,Ink(50 Hz) and Chubu Electric Power Co.,Inc(60 Hz):• Shin-shinano frequency converter (a 600-MW facility in Nagano prefecture owned byTokyo Electric Power Co.,Ink)• Sakuma frequency converter (a 300-MW capacity facility in Shizuoka prefecture • Frequency converter (Shin-owned by Electric Power Development Co., Ltd.) shinano)• Higashi-shimizu frequency converter (a 100-MW capacity facility in Shizuokaprefecture owned by Chubu Electric Power Co.,Ink) Major interconnected Kitahon interconnected line The electric power exchange from Hokkaido power systems nationwide Hokkaido and Honshu are interconnected via an overhead• Electric Power Co.,Ink(50 Hz) is transmitted through the 600-MW Kitahon transmission line and an undersea cable, which connectinterconnected line with a capacity of 600-MW. AC/DC converters in Hakodate to those in Kamikita. 500,000 V transmission line 154,000-275,000 V transmission line DC interconnected system Main substation, switchgear Frequency converter AC converter Shin-shinano F.C.•Reference: What was the origin of the different frequencies between eastern Kanmon interconnected line Honshu and Kyushu areand western Japan? interconnected via a 500,000 V transmission line.• In the Meiji and Taisho eras, the eastern region introduced 50 Hzgenerators from Europe, while the western region introduced 60 Hz generatorsfrom the U.S. The approximate boundary is the Fuji river (Shizuoka Sakuma F.C. Higashi-shimizu F.C.prefecture) and Itoi river (Niigata prefecture). Frequency converter (F.C.) Honshu-Shikoku interconnected line The 50 Hz system in eastern Japan and 60• Efforts to unify the frequency failed due to the huge cost and time required. Anan-Kihoku DC main line of Honshi interconnected power system Hz system in western Japan are interconnected at the three frequency Honshu and Shikoku are interconnected via converters: Sakuma in Shizuoka prefecture a 500,000 V transmission line laid along the (300 MW), Shin-shinano in Nagano Seto-Ohashi bridge and the AC/DC prefecture (600 MW) and Higashi-shimizu converters located in Anan and Kihoku. in Shizuoka prefecture (100 MW). The Federation of Electric Power Companies 25