February 9, 2015

Feb 9, 2015 | Fukushima Accident Updates

  • Actual Fukushima child exposures are one-third of Tokyo estimates. A team at Minamisoma General Hospital, led by Dr. Masaharu Tsubokura, monitored 520 school children of all ages with dosimeters. The monitoring periods ranged between 18 and 30 months. The actual readings showed an average of 0.8 millisieverts per year, which is a third of the 2.4 mSv/yr estimated by the government. The estimates were derived from “mid-air” readings taken near the homes of the children, assuming they would spend 8 hours per day outdoors. As it turned out, 97% of the children were outside less than 4 hr/day on weekdays, and 85% less than 4 hr/day on weekends and holidays. Dr. Tsubokura believes this is the first detailed child survey comparing actual to estimated exposures. The findings have been published in London’s Imperial College School of Public Health journal. http://www.fukushimaminponews.com/news.html?id=462
  • A Tritium removal system has been adopted for use with Fukushima wastewaters. Kurion, Inc., has developed the new technology. A demonstration project for verification tests of the Tritium separation technology will be run by the Industry Ministry (METI). Most Tritium removal technologies were found to be prohibitively expensive, but Kurion’s Modular Detritiation System is less costly. The test project should be ready in April. http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1422841701P.pdf
  • Muon tomography technology has been delivered to F. Daiichi unit #1. The portable system is ready for testing. The process is similar to X-ray imaging. Muons are a type of cosmic radiation that passes through most substances, but extremely dense materials deflect and block their passage. Uranium is one of the densest substances known, so Muon detection can be used to produce an image depicting where the main mass of melted uranium is located. About 10,000 muons per square meter reach the Earth’s surface every minute. The process was originally developed to map magma inside volcanos. It has been modified to be used at F. Daiichi. Before units #1, 2 & 3 can be fully decommissioned, all damaged fuel must be removed. Muon tomography should show where the melted fuel has accumulated inside the three reactor buildings and greatly assist in planning. Decommissioning Officer Naohiro Masuda said, “This is a great example of how the innovation and cooperation from external experts is helping us overcome challenges and make progress toward decommissioning. I hope that this will give us an opportunity to contribute to technological advancement and to share such progress with the rest of the world.” Delivery of a second system for unit #1 usage will be later this week. http://www.tepco.co.jp/en/press/corp-com/release/2015/1248057_6844.html  For images of the delivery and external installation of the equipment, see… http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150209_01-e.pdf
  • A “crawler” robot has been developed to examine inside the Primary Containments at F. Daiichi. The robot was built by Hitachi-GE and can change shapes from rectangular to cylindrical in order to fit through tight spaces and inside piping. In rectangular form, the robot is 20x30x10 centimeters, but can fold into a rod-like form less than 10 centimeters in diameter. It is self-propelled and carries a camera, radiation monitor and thermometer. Radiation levels inside the PCVs are too high for human inspection, so it is hoped this robot will provide inspections sufficient to find out whether or not melted fuel (corium) flowed outside the reactor pressure vessel (RPV). Hitachi-GE engineer Yoshitomo Takahashi said, “Depending on how much data we can collect from this area, I believe (the probe) will give us a clearer vision for future decommissioning.” The robot was unveiled Friday at Hitachi-GE, Tokyo, and is planned for on-site use with unit #1 in April or May. http://www3.nhk.or.jp/nhkworld/english/news/20150206_16.html — http://blogs.wsj.com/japanrealtime/2015/02/06/fukushima-watch-robot-to-provide-first-glimpse-of-reactor-fuel-debris/ — http://www.japantoday.com/category/technology/view/robot-to-probe-melted-fukushima-reactor
  • The IAEA begins its latest inspection of Fukushima Daiichi. The International Atomic Energy Agency has sent a 15-member team to Japan as a follow-up to the agency’s 2013 examination. The general focus will be the status of the station’s decommissioning process, with special emphasis on wastewater buildup and treatment. Team leader Juan Carlos Lentijo said dealing with contaminated water at F. Daiichi remains “one of the most challenging short-term issues”. http://english.kyodonews.jp/news/2015/02/335600.html
  • It seems the restart assessment for Takahama units 3&4 will be formally approved. The draft of the approval was released in December, but a 30-day period for public comment had to be granted and the submittals reviewed before a final announcement could be rendered. The NRA has pored over some 3,600 public comments since mid-January. The final approval document could be ready by Thursday. Station owner Kansai Electric says they do not believe actually start up one of the units before November. The utility must submit additional design paperwork to the NRA for approval, and local consent must be garnered. The NRA added that if units 1&2 at Takahama are ever considered for restart, Kansai Electric will have to undergo a unit 3&4 reassessment because the new emergency command center is too close to units 1&2. http://fukushimaupdate.com/nra-to-approve-takahama-safety-measures/
  • The anticipated restart of the two Sendai units has caused political reaction. When asked about restarts, Fukushima Gov. Masao Uchibori said, “We urge the government to take into full consideration the tremendous suffering from the nuclear power plant accident and make sure that future policy ensures the safety and peace of mind of all citizens.” Sources say that the June restarts will be formally announced by Prime Minister Abe, who wants the nation’s massive trade deficit caused by the nuke moratorium to be eased. http://www.japantimes.co.jp/news/2015/02/06/national/sendai-reactor-faces-june-restart-if-inspection-election-hurdles-cleared/#.VNTdnqMcQdV
  • Japan has lifted all restrictions on fish caught off northern Ibaraki Prefecture. The prefecture was placed under a ban for all seafood in April, 2011. The restrictions have been peeled back slowly over the past two years. The final ban specific to flounder, has been lifted. No other restrictions remain. Ibaraki is immediately south of Fukushima Prefecture. 57 flounder tests were performed since last year; 38 showed no detectible Cesium and the other 20 were less than one-seventh of the national limit. The local fisheries will continue radiation monitoring in the hope of dispelling rumors in the marketplace. http://www3.nhk.or.jp/nhkworld/english/news/nuclear.html