August 24, 2015

Aug 24, 2015 | Fukushima Accident Updates

  • 13,000 more Fukushima evacuees can prepare to go back home. Tokyo’s nuclear emergency response headquarters says residents of Minamisoma City and Katsurao Village can stay in their homes for a three month preparatory period starting on August 31. In the affected zones of both communities, residents have been allowed to visit their abodes only during the day. The zones are the entire Odaka district and part of the Haramachi district in Minamisoma, and nearly all of the small part of Katsurao under the mandated evacuation restriction. In Minamisoma as many as 11,702 will be able to repopulate, and in Katsurao up to 1,360 are subject to the eased restriction. Deputy Chief Osamu Goto said the reason for the decision is “conditions for (residents’) return home are almost in place, including progress in the preparation of infrastructure systems and decontamination work.” However, he noted that “it does not follow that the restrictions will be automatically lifted three months later” because discussion with the local and prefectural governments must ensue. Regardless, Minamisoma plans on lifting the evacuation order inn April, and Katsuao sometime in the spring. The response task force also intends to extend the eased ruling to Kawamata Town’s Yamakiya district, but details have yet to be worked out. http://www.fukushimaminponews.com/news.html?id=551
  • The slow increase of electrical output at Sendai #1 was curtailed Friday. A seawater leak into one of the three main condensers under the main turbines caused the problem. It seems power was at about 75% when a conductivity alarm sounded on the fresh water (condensate) being pumped out of the condenser. A chemical analysis quickly identified seawater in the liquid. The condenser was isolated in order to begin investigation and repair the leak. Sendai #1 is a Pressurized Water Reactor with “primary” and “secondary” systems. The water in the primary system is heated to a high temperature by the heat of fission as it passes through the nuclear fuel core. The primary water is kept at a very high pressure so that it cannot boil. The hot primary water is pumped to a steam generator where it runs through a myriad of pipes (tube sheet) and heats water on the outside (secondary side) of the tubes. The secondary water is allowed to boil, producing the steam to drive the turbine generators. The primary and secondary waters do not mix, thus the steam is not radioactive. When the used-up steam emerges from the bottom of the turbines, it is cooled by another myriad of metal tubes with seawater flowing inside them and condenses back into liquid form. The large tank containing the cooling tubes is called the condenser. The pressure on the steam/condensate side of the condenser tubes is well-below atmospheric, and the seawater running through the tubes has a pressure slightly above atmospheric, so the seawater flows into the condensate if a leak develops. It seems this has not been adequately explained by Japan’s Press, as shown in the below links. http://www3.nhk.or.jp/nhkworld/english/news/nuclear.html — http://the-japan-news.com/news/article/0002371636 — http://mainichi.jp/english/english/newsselect/news/20150821p2g00m0dm075000c.html
  • Tepco has posted a detailed Press handout on their upgraded information disclosure program. As a result of the uproar over previously unreported instances of rainwater runoff radioactivity over the past year, the company has committed to a policy of intensified disclosure. The release states, “In the wake of the drainage K problem that came to light in March of this year efforts are being made to improve the awareness of the FDEC and its sensitivity to issues of social concern.” The rationale is that “The sensitivity of disclosing information from the perspective of society had not fully permeated throughout the organization.” Tepco also says the problem was worsened by organizational issues. The Fukushima Daiichi Decontamination & Decommissioning Engineering Company (FDEC) has been tasked to improve awareness, cultivate social sensitivity, and create a formal mechanism to ensure promise fulfillment. In order to implement better public communication, the Risk Communicator staff will be doubled and populated with “…primarily nuclear engineers in management positions that have a variety of expert skills.” Training for the staff will be held every six months with instructors from “outside the company”. http://www.tepco.co.jp/en/press/corp-com/release/betu15_e/images/150824e0101.pdf
  • Correction of an earlier update. Last week, it was announced that Japan has formally protested the South Korean embargo on marine food products. We posted that the ban was expanded to all of Japan in 2013. Actually, the restriction was specific to but eight prefectures on the eastern coastline of Honshu Island; Aomori, Iwate, Miyagi, Fukushima, Ibaraki, Tochigi, Gunma and Chiba. South Korea says the embargo is due to the “leakage of contaminated water”. http://www.jaif.or.jp/en/japan-seeks-formal-adjudication-by-wto-on-south-koreas-import-restrictions-on-japanese-marine-products/