Tokyo Electric Power Company | Largest electricity company in the world | History and definition of Electric Power Company | Symbol of TEPCO

The Tokyo Electric Power Company, Incorporated , also known as Toden or TEPCO, is an electric utility servicing Japan's Kantō region, Yamanashi Prefecture, and the eastern portion of Shizuoka Prefecture. This area includes Tokyo. Its headquarters are located in Uchisaiwaicho, Chiyoda, Tokyo, and international branch offices exist in Washington, D.C., and London.

Tepco is the fourth largest electric power company in the world (1st: E.ON, 2nd: Électricité de France, 3rd: RWE), and the largest to hail from Asia. The amount of electricity it sells annually is the same as the amount Italy uses in a year. Tepco has one-third of the Japanese electric market. Tepco is the largest of the 10 electric utilities in Japan.

In 2007 Tepco was forced to shut the Kashiwazaki-Kariwa Nuclear Power Plant after the Niigata-Chuetsu-Oki Earthquake. That year it posted its first loss in 28 years. Corporate losses continued until the plant reopened in 2009. Following the March 2011 Tōhoku earthquake and tsunami, its power plant at Fukushima Daiichi was the site of a continuing nuclear disaster, one of the world's most serious. TEPCO could face ¥2 trillion ($23.6 billion) in special losses in the current business year to March 2012, and Japan plans to put TEPCO under effective state control as a guarantee for compensation payments to people affected by radiation.

Japan's ten regional electric companies, including TEPCO, were established in 1951 with the end of the state-run electric industry regime for national wartime mobilization.

In the 1950s, the company's primary goal was to facilitate a rapid recovery from the infrastructure devastation of World War II. After the recovery period, the company had to expand its supply capacity to catch up with the country's rapid economic growth by developing fossil fuel power plants and a more efficient transmission network.

In the 1960s and 1970s, the company faced the challenges of increased environmental pollution and oil shocks. TEPCO began addressing environmental concerns through expansion of its LNG fueled power plant network as well as greater reliance on nuclear generation. The first nuclear unit at the Fukushima Dai-ichi (Fukushima I) nuclear power plant began operational generation on March 26, 1970.

During the 1980s and 1990s, the widespread use of air-conditioners and IT/OA appliances resulted a gap between day and night electricity demand. In order to reduce surplus generation capacity and increase capacity utilization, TEPCO developed pumped storage hydroelectric power plants and promoted thermal storage units.

Recently, TEPCO is expected to play a key role in achieving Japan's targets for reduced carbon dioxide emissions under the Kyoto Protocol. It also faces difficulties related to the trend towards deregulation in Japan's electric industry as well as low power demand growth. In light of these circumstances, TEPCO launched an extensive sales promotion campaign called 'Switch!', promoting all-electric housing in order to both achieve the more efficient use of its generation capacity as well as erode the market share of gas companies.

The company's power generation consists of two main networks. Fossil fuel power plants around Tokyo Bay are used for peak load supply and nuclear reactors in Fukushima and Niigata Prefecture provide base load supply. Additionally, hydroelectric plants in the mountainous areas outside the Kanto Plain, despite their relatively small capacity compared to fossil fuel and nuclear generation, remain important in providing peak load supply. The company also purchases electricity from other regional or wholesale electric power companies like Tohoku Electric Power Co., J-POWER, and Japan Atomic Power Company.

The company has built a radiated and circular grid between power plants and urban/industrial demand areas. Each transmission line is designed to transmit electricity at high-voltage (66-500kV) between power plants and substations. Normally transmission lines are strung between towers, but within the Tokyo metropolitan area high-voltage lines are located underground.

From substations, electricity is transmitted via the distribution grid at low-voltage (22-6kV). For high-voltage supply to large buildings and factories, distribution lines are directly connected to customers' electricity systems. In this case, customers must purchase and set up transformers and other equipment to run electric appliances. For low voltage supply to houses and small shops, distribution lines are first connected to the company's transformers (seen on utility poles and utility boxes), converted to 100/200V, and finally connected to end users.

Under normal conditions, TEPCO's transmission and distribution infrastructure is notable as one of the most reliable electricity networks in the world. Blackout frequency and average recovery time compares favorably with other electric companies in Japan as well as within other developed countries. The company instituted its first-ever rolling blackouts following the shutdown of the Fukushima I and II plants which were close to the epicenter of the March 2011 earthquake. For example on the morning of Tuesday, March 15, 2011, 700,000 households had no power for three hours. The company had to deal with a 10 million kW gap between demand and production on March 14, 2011.

On August 29, 2002, the government of Japan revealed that TEPCO was guilty of false reporting in routine governmental inspection of its nuclear plants and systematic concealment of plant safety incidents. All seventeen of its boiling-water reactors were shut down for inspection as a result. TEPCO's chairman Hiroshi Araki, President Nobuya Minami, Vice-President Toshiaki Enomoto, as well as the advisers Shō Nasu and Gaishi Hiraiwa stepped-down by September 30, 2002. The utility "eventually admitted to two hundred occasions over more than two decades between 1977 and 2002, involving the submission of false technical data to authorities". Upon taking over leadership responsibilities, TEPCO's new president issued a public commitment that the company would take all the countermeasures necessary to prevent fraud and restore the nation's confidence. By the end of 2005, generation at suspended plants had been restarted, with government approval.

In 2007, however, the company announced to the public that an internal investigation had revealed a large number of unreported incidents. These included an unexpected unit criticality in 1978 and additional systematic false reporting, which had not been uncovered during the 2002 inquiry. Along with scandals at other Japanese electric companies, this failure to ensure corporate compliance resulted in strong public criticism of Japan's electric power industry and the nation's nuclear energy policy. Again, the company made no effort to identify those responsible.

On 11 March 2011 several nuclear reactors in Japan were badly damaged by the 2011 Tōhoku earthquake and tsunami.

The Tōkai Nuclear Power Plant lost external electric power, experienced the failure of one of its two cooling pumps, and two of its three emergency power generators. External electric power could only be restored two days after the earthquake.

The Japanese government declared an “atomic power emergency” and evacuated thousands of residents living close to TEPCO's Fukushima I plant. Reactors 4, 5 and 6 had been shut down prior to the earthquake for planned maintenance. The remaining reactors were shut down automatically after the earthquake, but the subsequent tsunami flooded the plant, knocking out emergency generators needed to run pumps which cool and control the reactors. The flooding and earthquake damage prevented assistance being brought from elsewhere. Over the following days there was evidence of partial nuclear meltdowns in reactors 1, 2 and 3; hydrogen explosions destroyed the upper cladding of the building housing reactors 1 and 3; an explosion damaged reactor 2's containment; and severe fires broke out at reactor 4.

The Japanese authorities rated the events at reactors 1, 2 and 3 as a level 5 (Accident With Wider Consequences) on the International Nuclear Event Scale, while the events at reactor 4 were placed at level 3 (Serious Incident). The situation as a whole was rated as level 7 (Major Accident). On 20 March, Japan's chief cabinet secretary Yukio Edano "confirmed for the first time that the nuclear complex — with heavy damage to reactors and buildings and with radioactive contamination throughout — would be closed once the crisis was over." At the same time, questions are being asked, looking back, about whether company management waited too long before pumping seawater into the plant, a measure that would ruin and has now ruined the reactors; and, looking forward, "whether time is working for or against the workers and soldiers struggling to re-establish cooling at the crippled plant." One report noted that defense minister, Toshimi Kitazawa, on 21 March had committed "military firefighters to spray water around the clock on an overheated storage pool at Reactor No. 3." The report concluded with "a senior nuclear executive who insisted on anonymity but has many contacts in Japan sa[ying that] ... caution ... [as] plant operators have been struggling to reduce workers’ risk ... had increased the risk of a serious accident. He suggested that Japan’s military assume primary responsibility. 'It’s the same trade-off you have to make in war, and that is the sacrifice of a few for the safety of many,' he said. 'But a corporation just cannot do that.'"

There has been considerable criticism to the way TEPCO handled the crisis. It was reported that seawater was used only after Prime Minister Naoto Kan ordered it following an explosion at one reactor the evening of 12 March, though executives had started considering it that morning. Tepco didn't begin using seawater at other reactors until 13 March. Referring to that same early decision-making sequence, "Michael Friedlander, a former senior operator at a Pennsylvania power plant with General Electric reactors similar to the troubled ones in Japan, said the crucial question is whether Japanese officials followed G.E.’s emergency operating procedures." Kuni Yogo, a former atomic energy policy planner in Japan’s Science and Technology Agency and Akira Omoto, a former Tepco executive and a member of the Japanese Atomic Energy Commission both questioned Tepco's management's decisions in the crisis. Kazuma Yokota, a safety inspector with Japan's Nuclear and Industrial Safety Agency, or NISA, was at Fukushima I at the time of the earthquake and tsunami and provided details of the early progression of the crisis.