No. 40: 18:00, April 2
NHK news regarding status of Fukushima Daiichi nuclear power station yesterday and today.
●High-level radioactive iodine detected offshore
Radioactive iodine twice the country's legal standard has been detected in seawater at a location 40 kilometers south of the disabled Fukushima Daiichi nuclear power plant. The Japanese Science Ministry on Saturday released the results of a survey based on samples taken 3 days ago. The sample was collected at a spot 10 kilometers off Iwaki City and 40 kilometers from the disabled plant, both in Fukushima Prefecture. The detected level of iodine-131 was 79.4 becquerels per liter, twice the legal standard for water discharged from nuclear plants. This is the first time that a radioactive reading that exceeds the legal limit has been detected off the shore of Fukushima Prefecture. It's believed that the radioactive substances were carried offshore from the plant by a north-south current. On Saturday, a crack was found in the compound of the nuclear plant through which radioactive water has been leaking into the ocean.
The Nuclear Safety and Industrial Agency says radioactive iodine will be diluted in seawater and does not ose a threat to human health. But it said it will continue to closely monitor the condition.
Saturday, April 02, 2011 17:49 +0900 (JST)
●Radioactive water leak confirmed
Tokyo Electric Power Company says it has identified for the first time a place where high-level radioactive water is leaking into the ocean from the No. 2 reactor at the Fukushima Daiichi nuclear plant. The power company said on Saturday that water has been seeping from a crack in the wall of a 2-meter deep pit that contains power cables near the reactor's water intake. Water measuring between 10 and 20 centimeters deep was found in the pit. The radiation level has been measured at over 1,000 milisieverts per hour. The company says it is preparing to pour concrete into the cracked pit to stop the radioactive water leak.
A senior Nuclear Safety Agency official says the crack could be one of the sources of radioactivity found in the seawater near the water outlet.
He says the agency has ordered TEPCO to test samples of seawater at more locations near the plant and analyze them for different radioactive materials. In the past week, the radiation detected in water in the basement of the turbine building at the No. 2 reactor was about 100,000 times higher than the normal level. High-levels of radiation were also found in puddles in a utility tunnel outside the turbine building.
Saturday, April 02, 2011 17:33 +0900 (JST)
●IAEA reports lower radiation levels in Iitate
The International Atomic Energy Agency says radiation levels in a village 40 kilometers from the Fukushima Daiichi nuclear power plant have dropped below its criterion for evacuation. The IAEA announced the result of its analysis on Friday. The village of Iitate, to the northwest of the plant, is outside the 20-kilometer exclusion zone and the 20-to-30-kilometer alert zone where the Japanese government advises voluntary evacuation. The IAEA said the average level of radioactive iodine-131 in Iitate's soil was 7 million becquerels per square meter between March 19th and 29th, based on 15 readings by Japanese authorities. It said this was below its evacuation criterion. On Wednesday, the UN nuclear agency said 20 million becquerels of iodine-131 per square meter were detected in Iitate during a similar period, using data obtained by Japanese authorities. It said this was twice its evacuation level. The IAEA says levels of radioactive substances could change depending on the situation at the Daiichi plant, as well as wind, rain, and other weather conditions. The agency is advising the Japanese government to carefully assess soil data.
Saturday, April 02, 2011 11:03 +0900 (JST)
●Higher radiation levels on SDF helicopters
Higher than normal levels of radiation have been detected on Ground Self-Defense Force helicopters that flew over the troubled Fukushima Daiichi nuclear power plant even after decontamination. GSDF sources say hundreds of microsieverts of radiation per hour were detected at engine inlets and other parts of the helicopters, which monitored radiation levels and took aerial pictures of the plant. The US military has informed the Japanese force that radioactive cesium in particular easily adheres to paint used on helicopters and other vehicles. The GSDF is trying to ensure that all mechanics will wear protective gear during their work. It is also considering the purchase of new equipment to vacuum up radioactive substances.
Saturday, April 02, 2011 09:27 +0900 (JST)
●TEPCO to get a massive floating platform
\Tokyo Electric Power Company is going to get a massive hollow floating platform from Shizuoka City. TEPCO plans to use it to store radioactive water at its crippled Fukushima Daiichi nuclear plant. The steel mega float is 136 meters long and 46 meters wide. Shizuoka City obtained it after it was used in an on-sea airport experiment off Yokosuka City near Tokyo. In 2003, the city turned the float into a deep-sea fishing park at a cost of about 7.3 million dollars. TEPCO asked the city for the float so it can use it to store radioactive water at the nuclear plant. The float can store up to 18,000 tons of water. Shizuoka City says TEPCO plans to keep the float in a safe place after using half its capacity. Sources say the float will be taken to the Fukushima Daiichi nuclear plant after inside dividing walls are removed at a Yokohama shipyard.
Saturday, April 02, 2011 09:05 +0900 (JST)
●TEPCO speeds up work to remove radioactive water
The operator of the Fukushima Daiichi nuclear plant is stepping up work to remove radioactive water that hinders the functioning of the cooling systems. Tokyo Electric Power Company is trying to remove contaminated water from the basements of the turbine buildings of the No.1, 2, and 3 reactors. At all 3 reactors, TEPCO wants to move radioactive water into storage tanks. But first, uncontaminated water in the storage tanks must be transferred. Work at the No. 2 and 3 reactors is expected to begin on Saturday. As for the No. 1 reactor, the uncontaminated water in the storage tank will be completely transferred to another one by Saturday afternoon.
On Friday, workers began a test spraying of synthetic resin in areas around the reactors to contain radioactive materials released by hydrogen blasts. Synthetic resin is expected to harden mud and dust. The same day, 8 monitoring posts to measure radiation levels in the compounds started functioning again for the first time since the quake struck 3 weeks ago. TEPCO says it will restore the automatic data transmission system so that the information can be made public on its website. Also on Friday, docked US military barges began providing freshwater to cool the reactors. But work was suspended temporarily after water leaked from a hose.
Saturday, April 02, 2011 09:05 +0900 (JST)
●Restoring stable cooling systems may take time
The operator of the crippled Fukushima Daiichi nuclear plant is working hard to restore systems that cool reactors in a stable manner by circulating massive volumes of water. Currently, freshwater is being poured directly into the reactors and the pools containing spent nuclear fuel rods, to cool them down. But the plant operator wants to restore the functions of the cooling systems that circulate water inside the reactors and the pools for spent fuel. The freshwater is cooled down by seawater. On Friday, Tokyo Electric Power Company installed temporary pumps at 4 reactors, from No. 1 to No. 4. The pumps will be used to capture seawater to cool down the circulating freshwater. But pipes and pumps used to cool the reactors may have been damaged by the quake, and radiation levels in the reactor buildings remain too high to check their condition.
TEPCO says it may take time to restore the cooling systems, as it has to take emergency measures and wait for radiation levels to go down. It says it will consider developing other cooling methods.
Saturday, April 02, 2011 09:05 +0900 (JST)
●Radioactive water may be kept in mega float
Japan's government is deciding if highly radioactive water at the Fukushima Daiichi nuclear plant can be temporarily kept in a steel mega float or in US military vessels.
Highly radioactive materials have been detected in water at the crippled nuclear plant in northeast Japan. Plant operator Tokyo Electric Power Company plans to use water tanks to store the radioactive water, but the capacity of these tanks is limited. Shizuoka City has offered TEPCO a hollow floating platform made of steel to store the water. The mega float is 136 meters long and 46 meters wide, and is currently used as a deep-sea fishing park. The government is also negotiating with the US military, to see if 2 US barges can be used to temporarily store the radioactive water. The barges were used to transport freshwater that will be used to cool reactors at the nuclear plant. The government also plans to use 2 ships leased from a private firm. It says storage of up to 15,000 tons of contaminated water is possible if these ships are used alongside the mega float. TEPCO and the government are trying to iron out concrete methods of safely transporting and storing radioactive water.
Saturday, April 02, 2011 05:33 +0900 (JST)
●TEPCO releases new footage of Number 4 reactor
Tokyo Electric Power Company has released new video footage of the Number 4 reactor building at its damaged Fukushima complex. The utility firm shot the video using a camera installed on the tip of the long arm of a special construction vehicle. Osaka University Professor Akira Yamaguchi, an expert on nuclear reactors, analyzed the video. He says that a green device used to replace nuclear fuel rods stayed in place without falling into a spent-fuel storage pool, in spite of an apparent hydrogen explosion inside the reactor building. He also says that vapor from the storage pool reduces as the special vehicle pours water onto it, which contributes to cooling the water in the pool. Yamaguchi says the top of the reactor building suffered substantial damage, but the structure below the storage pool was hardly affected, as it was more strongly constructed. He stresses the need to restore the power supply as early as possible to restore the pool's cooling function. He says at least 90 tons of water a day need to be pumped in to cool the stored fuel rods. The pool in Number 4 reactor building holds over 1,300 spent rods, more than those kept in other units.
He warns that the fuel held there generates just as much heat as is produced by Numbers 2 and 3 reactors.
Yamaguchi says it is essential to keep the temperature low at the storage pool to prevent the fuel rods from being exposed and destroyed
Friday, April 01, 2011 22:04 +0900 (JST)
●Tremors exceeded design limits for 3 reactors
The operator of the Fukushima Daiichi nuclear power station says 3 of the plant's 6 reactors were shaken on March 11th by tremors exceeding forces they were designed to withstand. The Tokyo Electric Power Company, known as TEPCO, says reactor No.2 suffered the largest horizontal ground acceleration of 550 gals, which is 26 percent stronger than the reactor's design limit. TEPCO says the readings were 548 gals at the No.5 reactor, about 21 percent higher than its design limit; and 507 gals at the No.3 reactor, topping the capacity by about 15 percent. The power company says the strength of ground motions were close to or within the design parameters at the remaining 3 reactors, and at all 4 reactors of the nearby Fukushima Daini nuclear plant. The utility says it was planning to reinforce the reactors so they could withstand horizontal shaking of 600 gals, after the government reviewed their quake-resistance standards 5 years ago. But the work was not finished. TEPCO says it will continue analyzing the seismic activity in detail.
Friday, April 01, 2011 19:40 +0900 (JST)
●Battle continues for Fukushima
Urgent work is continuing on several fronts to contain the crisis at the Fukushima Daiichi nuclear power plant. Efforts to cool down the reactors continued on Friday. A barge provided by the US Navy is preparing to pump large volumes of fresh water by hose to a water tank near the No.1 reactor. Workers at the plant are replacing seawater with fresh water to cool the reactors and spent-fuel storage pools. The move follows concerns that salt in the seawater could clog up reactor equipment and hamper the flow of coolant water. Near the No.4 reactor, 400 liters of a synthetic resin solution were sprayed in an experiment intended to solidify contaminated dust and prevent radioactive materials from getting airborne. Plant operator Tokyo Electric Power Company is due to test the solution for about 2 weeks to see if it works. Workers also face the challenge of removing and safely storing highly radioactive water found in and around the reactors. On Friday, they emptied the No.2 reactor's condensate storage tank, with the same task at the No.1 reactor due to finish soon after. The emptied tanks will make room for water from the turbine condenser, which in turn will provide storage space for radioactive water flooding the turbine units. Contaminated water has also been found in deep tunnels extending from the turbine units of 3 reactors. To prevent the water from spilling into the ocean, water-level monitors are being installed. The work is due to be completed by Saturday.
Friday, April 01, 2011 19:25 +0900 (JST)
●Program errors force TEPCO to review all data
Tokyo Electric Power Company says it will review all data on radiation leaked from the damaged Fukushima Daiichi nuclear plant, citing errors in a computer program. The utility says it found errors in the program used to analyze radioactive elements and their levels, after some experts noted that radiation levels of leaked water inside the plant were too high. The company and the government's Nuclear and Industrial Safety Agency say previously released data may have shown the levels of tellurium-129 and molybdenum-99 to be higher than they really were. But they say that levels of iodine-131, which has a significant impact on humans and the environment, remain unchanged. Tokyo Electric releases data on radioactivity inside the plant compound and in nearby seawater and soil. The radioactive substances are believed to be coming from damaged nuclear fuel rods. The data is crucial for identifying the source of radioactive leaks and assessing their impact on the environment. The Nuclear and Industrial Safety Agency has told the company to find out why the errors occurred and to take steps to prevent a recurrence.
Friday, April 01, 2011 15:39 +0900 (JST)