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Information Sheet Regarding the Tohoku Earthquake
The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office
As of 4:30PM (EST), March 13, 2011
At 2:46PM (JST) on March 11, 2011, a 9.0-magnitude earthquake occurred near the Tohoku region of Northeast Japan. The epicenter of the earthquake lies 17 miles below the earth’s surface in the Pacific Ocean, 81 miles off the coast from Sendai City. Intense shaking could be felt from Tokyo to Kamaishi, an arc of roughly 360 miles.
The earthquake generated a tsunami with waves of more than 30 feet that caused widespread damage to a swath of the northeast Japan coastline. In addition to the significant destruction of buildings, infrastructure, and human property, two of Japan’s 17 nuclear power stations (sites)—Fukushima Daiichi and Fukushima Daini—suffered damage due to the tsunami. All three of the six operating reactors at Fukushima Daiichi Nuclear Power Station and all four reactors at Fukushima Daini Nuclear Power Station, both operated by Tokyo Electric Power Company (TEPCO), shut down automatically in response to the earthquake. TEPCO is one of ten member companies of The Federation of Electric Power Companies of Japan (FEPC).
A state of emergency was declared at Fukushima Daiichi at 7:03PM March 11. Unit 1 and 3 reactors at Fukushima Daiichi lost primary reactor cooling because of a loss of all electrical power. Emergency cooling systems were engaged to lower the core reactor temperature. In order to alleviate the buildup of pressure, slightly radioactive vapor, that posed no health threat, was passed through a filtration system and emitted outside via a ventilation stack from Unit 1 reactor vessel at 9:07AM on March 12 and Unit 3 reactor vessel at 9:20PM on March 13. At 3:36PM on March 12, an explosion occurred at Fukushima Daiichi Unit 1 reactor damaging the roof of the secondary containment building. The explosion—caused by the interaction of hydrogen and oxygen vapor between the primary containment vessel and secondary containment building—did not damage the primary containment vessel or the reactor core. Four workers who were injured by the explosion were transported to a nearby hospital.
In order to control the pressure of the reactor core, TEPCO began to inject seawater and boric acid into the primary containment vessels of Unit 1 (8:20PM, March 12) and Unit 3 (1:12PM, March 13). There is likely some damage to the fuel rods contained the reactor core of Unit 1 and 3 reactors. The water level in the reactor vessel of Unit 2 reactor is steady. Personnel from TEPCO are closely monitoring the status of Unit 1, 2, and 3 reactors. The highest recorded radiation level at the Fukushima Daiichi site was 1557 micro sievert (1:52PM, March 13). The most recent reported level at Fukushima Daiichi is 44 micro sievert (7:33PM, March 13).
While representatives of the Japanese government have acknowledged the potential for partial meltdowns at Fukushima Daiichi Unit 1 and 3 reactors, there is no danger for core explosion, as occurred at the nuclear power station at Chernobyl in 1986. Control rods have been successfully inserted at all of the reactors, thereby ending the chain reaction. The reactor cores at Fukushima Daiichi and Daini power stations are surrounded by steel and concrete containment vessels of 40 to 80 inches thick that are designed to contain radioactive materials.
At 7:45AM on March 12, a state of emergency was declared for Fukushima Daini. There is electricity available at all four of the reactors at Fukushima Daini, including Unit 3 reactor. Although there is limited availability of the cooling water pumps at Unit 1, 2, and 4 reactors, TEPCO is working effectively to maintain constant cooling in the primary containment vessels. TEPCO confirms that no radioactivity has been recorded outside of the secondary containment buildings at Fukushima Daini.
Two other plants in the Tohoku region, Onagawa Nuclear Power Station and Tokai Nuclear Power Station, were automatically shut down in response to the earthquake. The four reactors at these plants have functioning cooling systems and are being monitored by plant operators. The Rokkasho Reprocessing Plant and accompanying facilities, located far north of the tsunami zone in Rokkasho Town, is operating safely on backup power generation systems. Japan Nuclear Fuel Limited (JNFL), which operates the Rokkasho facilities, drained a 600-liter spill from the containment pool for spent fuel through a specialized wastewater treatment system. Two casks of low-level nuclear waste (LLW), which were being prepared for transport from Mutsu Ogawara Port when the earthquake occurred, have been successfully received at the Rokkasho facility.
Japanese nuclear facilities are built to exacting safety standards. They are designed to withstand powerful seismic events, such as earthquakes. In this earthquake—the strongest recorded over the past 100 years in Japan—the containment structures of Fukushima Daiichi maintained their structural integrity. These facilities were designed to withstand tsunamis within a range of assumed strength. In this event, however, the force of the tsunami exceeded the assumed range and flooded diesel generators at Fukushima Daiichi power station, thus precipitating the loss of power for the reactor cooling systems.
In order to minimize adverse health effects of any potential radioactive release, the Japanese government issued an evacuation order at 9:23PM on March 11 for a radius of 1.86 miles around Fukushima Daiichi. By 6:25PM on March 12, the evacuation area has been enlarged to cover the approximately 70,000 residents within 12.5 miles of Fukushima Daiichi and 6.2 miles of Fukushima Daini.
In addition to supporting the evacuations near Fukushima Daiichi and Daini nuclear power stations, TEPCO is collaborating with the Japanese government to ensure the safety of the all people in the affected region. Iodine tablets, to counteract the effects of radioactivity on the thyroid gland, have been distributed to people at the boundary of the evacuation zone. Sophisticated radiation screening equipment has been mobilized to measure radiation exposure for people close to the evacuation area. The Japanese Nuclear and Industrial Safety Agency said that as many as 160 people may have been exposed to radiation around the Fukushima Daiichi station. TEPCO and the Japanese government will continue to use their full professional and technological resources, as well as those offered by international organizations, to ensure the safety of those displaced by the earthquake and tsunami.
The automatic shutdown of the 11 operating reactors at the Onagawa Nuclear Power Station, Tokai Nuclear Power Station, Fukushima Daiichi and Daini, represents a loss of 3.5% of electric generation capacity for Japan. In addition, several thermal power stations were damaged in the earthquake and are currently under repairs. In order to compensate for this loss of electricity production, TEPCO has instituted rolling blackouts, information about which can be found on the TEPCO website. The Japanese government is also urging all residents in Japan to minimize their electricity use in order to support the relief and recovery effort in Tohoku.
FEPC, in cooperation with TEPCO and related organizations, will continue to work tirelessly to provide the public with the most accurate and timely information on the situation at the Fukushima Daiichi and Daini nuclear power stations.
End of quoted information sheet.