Before today’s updates, I would like to recommend an excellent report on the robots of Fukushima posted by America’s Nuclear Energy Institute (NEI). There have been numerous reports out of Japan over the past year concerning the use of robots for debris removal, measuring radiation levels in hazardous areas, and providing video plus other information back to operators who remain safe from excessive radiation exposure. Perhaps the most important robot use has been the internal inspection of the Primary Containment (PCV) for unit #2. For the complete story, go to…

Now, for today’s updates…

  • Kyoto Prefecture believes the Tokyo government’s explanations of the safety of Oi units #3 & 4 are insufficient for restarts. A Kyoto official (un-named) spoke to Tetsuya Yamamoto, NISA senior representative, on Tuesday at the Prefectural hall. The official said it is unclear to what extent the Nuclear Safety Commission has been involved in devising the new safety standards drafted last month. Further, he said Tokyo’s belief in Oi’s safety is inconsistent with those of the local residents. Yamamoto responded that the government is dedicated to putting the new nuclear safety standards in place as soon as possible. He added that without the two Oi units, the region faces the real possibility of power shortages this summer that could hurt everyone in Kyoto Prefecture. (NHK World)
  • Tepco reports that extensive testing proves that unit #4 Spent Fuel Pool will not collapse, even if an earthquake as powerful as March 11, 2011 happens again. Although post-quake/tsunami simulations revealed the SPF would probably not collapse, the margin of safety was less than before March 11. Because of this, Tepco decided to reinforce the bottom of the pool with steel girders, which brought the seismic safety margin to 1.43 (43% margin of safety). Concrete was subsequently added to the reinforcement bringing the safety margin to 1.79. In addition, precise measurements of the 5th floor show that the building has not tilted, which strongly suggests the reactor building has remained firmly attached to the underlying bedrock. Comment – While the Tepco report ought to quell rumors about unit #4 SPF collapsing with apocalyptic consequences for the world, it is unlikely that these outlandish rumors will stop. Prophets of nuclear energy doom around the world have literally “hung their hats” on these rumors. Based on their past actions, these prophets will probably accuse Tepco of falsifying data.
  • Japan and Kazakhstan have agreed to collaborate on the clean-up of Fukushima contamination. Japanese industry minister Yukio Edano met his Kazakh counterpart Asset Issekeshev in Kazakhstan on Tuesday. Representatives of Japanese electronics maker Toshiba and Kazakhstan’s national nuclear center also signed a memorandum on sharing decontamination expertise. The center began decontaminating the Soviet Semipalatinsk nuclear site in 1991. Toshiba intends to use Kazakhstan’s experience to develop new decontamination methods. (NHK World)
  • 2.4% of food items in nine prefectures exceeded the new limits on radioactive Cesium in April. The new limit of 100 Becquerels per kilogram went into effect on April 1. Out of 13,867 food samples tested, 337 exceed the limit. The 337 excessive samples came from 51 specific food items. 97.6% of all samples were below the new standard. (News on Japan)
  • There are four major investigative committees, each giving their opinion on what caused the Fukushima accident. Three published reports have some interesting agreements and a few areas of disagreement. One report (by the Diet’s expert panel) will not be available until June. The Asahi Shimbun, however, says none of the reports “paint a clear and definitive account of what actually transpired in the critical hours and days after the Great East Japan Earthquake and tsunami”, which is misleading. All three are quite clear versions on what happened. Apparently, The Asahi doesn’t want to believe the cause of the accident was the tsunami itself, which swamped the power complex and made emergency power inoperable. However, the three published reports all agree that the tsunami was the cause, but leave the door open for the earthquake contributing to the accident. This seems to be what The Asahi is focusing on…The Asahi seems to believe the earthquake was the culprit and the tsunami merely made matters worse in order to perpetuate fear, uncertainty and doubt.
  1. The existent reports seem to agree on three points – (a) the Tokyo government and Tepco not protecting against the rare-but-not-impossible tsunami, and allowing economic considerations to compromise safety, which made the accident possible. (b) The Prime Minister’s failure to use SPEEDI projections for the spread of radioactive contamination and his decision to evacuate based on distance rather than scientific data, causing confusion which resulted in many evacuees being exposed to higher radiation levels than ought to have occurred. (c) The tsunami itself, greatly exceeding the design-basis protective measures, was the cause of the accident.
  2. However, they disagree on three other key points – (a) did Tepco actually plan on abandoning Fukushima Daiichi on March 15? Tepco’s in-house report says, “The gist of what we asked the prime minister’s office is ‘Because the situation at the plant is difficult, we want consideration to be given to temporarily evacuating workers who are not directly involved in the work when that need arises.’ We never thought about (total withdrawal) nor asked that all workers be allowed to leave.” The government panel says Tepco’s statement was confusing and led the Prime Minister to take action. On the other hand, the private-sector panel took the position that that Tepco actually made the request to pull out all workers, based on testimony made by Yukio Edano, the then-chief Cabinet secretary. (b) Did Tepco operators err in stopping critical cooling flows on units #1 & 3? Tepco’s report says there is no evidence of human error. The government panel says possible delays in restoring cooling flows as soon as possible might have made the situation worse than it should have been. The panel said that such delays during an extreme emergency are “extremely inappropriate for an operator of a nuclear power plant.” The private sector panel believes that Tepco’s use of the High Pressure Coolant Injection system for cooling of unit #1 was little more than a stopgap measure, and that Tepco should have had alternative cooling measures in place when HPCI was lost. (c) The level of disagreement on what happened in unit #2 is enormous. Was there a hydrogen explosion inside the pressure suppression chamber on March 15th? Tepco says it never happened and the “sound” inside the unit #2 PCV was caused by the unit #4 hydrogen blast being transmitted through the underlying bedrock. The government report says the Plant manager assumed there was an explosion on March 15, so there’s no reason to think it did not happen. The government and private-sector panels say since there was fuel in unit #4 when it exploded on March 15, the large radiation release had to come from unit #2. Tepco says the March 15 releases came from unit #4, the atmosphere of which was contaminated by leakage from severely damaged unit #3. (Asahi Shimbun)