August 6, 2015

Aug 6, 2015 | Fukushima Accident Updates

  • Four bent fuel bundle handles were found in the unit #3 spent fuel pool (SFP). Tepco used an underwater camera to determine the degree of the rubble removal that will be needed before transferring the stored used fuel bundles. There is a considerable amount of rubble to be extracted from the tops of the stored fuel bundles. They noticed four bent bundle handles protruding out of the rubble bed. Whether or not the bent handles will make the removal of the four bundle’s a problem, remains to be seen. Tepco says there is no indication that the bundles beneath the bent handles have any damage. http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150804_01-e.pdf — http://www3.nhk.or.jp/nhkworld/english/news/nuclear.html
  • Tepco has been given approval to complete the “ice wall” surrounding units #1 through #4. The Nuclear Regulation Authority says the revised construction plan submitted by Tepco is permissible. The wall of frozen earth has been in construction on the inland side of the buildings since last June, but could not be started on the sea-side until all water had been removed from the equipment tunnels of units 1, 2, & 3. Once completed the wall will completely surround the four damaged unit’s buildings and severely limit the influx of groundwater into the basements. Ideally, the wall will stop the in-flow completely. Once it is completed, the NRA says Tepco must maintain the groundwater level inside the wall by pumping in uncontaminated water, if needed. http://www3.nhk.or.jp/nhkworld/english/news/20150804_01.html
  • Muon detection for unit #2 hits a snag. Muon detection has been used successfully inside unit #1 to establish the severity of fuel core damage. However, Tepco wanted a higher-resolution system developed before using the process on unit #2. The company and the NRA hoped to begin operation in the fall. However, the new device covers a 64m2 area, which is too big for the rooms where it would have to be installed inside the undamaged unit #2 reactor building. Station staff would have to remove and decontaminate other equipment to make enough room, which could hinder the decommissioning process. It would also cost twice as much money as that already spent developing the devices. Tepco says they will shift the smaller device being used at unit #1 after it completes its imaging run near the end of the year. http://www3.nhk.or.jp/nhkworld/english/news/nuclear.html
  • The opening of unit #1 enclosure allows for radiological measurements just above the destroyed refueling deck. Analysis showed no detectible Iodine, and barely detectible Cesium above one of the three sampling locations. The other two sampling points showed no Cesium. http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2015/images/airupper01_150805-e.pdf
  • The NRA approved the long-term management plan for the two soon-to-be-restarted Sendai nukes. Steps in the long-term plan to assure extended-life safety for all emergency equipment must be addressed in one year. The plans cover the next 30 years. Under the Reactor Regulation Law, plants that have 30 years or more of licensure must submit plans for the long-term safety of installed equipment beyond that point. Sendai unit #1 began operation 31 years ago, and could begin ramping up for restart on Tuesday. Of course, antinuclear critics complain that the NRA has made a hasty decision and allege that restart before the extended-life checks are completed is illegal. Safety reviews required for the resumption of operation are conducted separately from those required for long-term operations. The safety review for Sendai unit #1 was completed last May. http://www.jaif.or.jp/en/nra-approves-operation-of-sendai-1-beyond-30-years/ — http://www.japantimes.co.jp/news/2015/08/05/national/nra-approves-long-term-operating-plan-sendai-nuclear-plant/#.VcH3LZAw8dU — http://english.kyodonews.jp/news/2015/08/367531.html
  • The NRA says the restart of two Tepco units will be prioritized. Kashiwazaki-Kariwa units #6 & #7 are located on the Sea of Japan in Niigata Prefecture. Both are Boiling Water Reactor systems. Tepco needs them to be reactivated to alleviate its financial stress. It is expected that nuclear critics will decry the NRA decision because they constantly question Tepco’s ability to safely operate BWRs. http://english.kyodonews.jp/news/2015/08/367824.html
  • The NRA has approved a bill raising the exposure limit for nuclear emergencies to 250 millisieverts. The previous limit was 100 mSv. The bill says that the 100 mSv limit is to be maintained unless there’s a possibility that radioactive materials could disperse beyond the property boundary of a nuke station. If an off-site release is possible, then the 250 mSv limit kicks in. The ruling stipulates a need for prior written consent from potentially affected individuals after they have been educated on the possible health impacts of exposure and measures taken to minimize risk. The new limit is supposed to come into effect in April of 2016. http://www3.nhk.or.jp/nhkworld/english/news/nuclear.html