(For today’s commentary – No “Melt-throughs” at Fukushima Daiichi? – click here)
- Using endoscopic technology, Tepco has measured the water depth in the bottom of the annulus between the RPV pedestal and outer PCV wall, as well as radiation levels above and below the water. The water is about 2.8 meters deep, which is 80 centimeters more than they expected based on the water level found in unit #2. The radiation level at the surface of the water itself is about 0.5 sieverts per hour, which was another surprise to Tepco because they estimated that it would be at least double that level. The radiation field just above the water’s surface is 4.7 sieverts per hour. However, the radiation measurement at an elevation of 8.6 meters above the floor of the annulus is 11 sieverts per hour, producing yet another surprise. , Tepco had speculated the radiation field should have been increasingly lower as the radiation detector was raised higher and higher above the water. The opposite is now known to be the case. The Tepco spokesman, Masayuki Ono, says it is difficult to identify where the source of this higher radiation is coming from. However, holding true to the company position of a full RPV melt-through, Ono said the high water level is surely enough to keep the melted fuel lying at the bottom of the PCV from over-heating. Tepco also says the relatively good condition of the PCV’s inner steel lining and the concrete pedestal wall is yet another surprise. What little debris that has been viewed on the metal grating (walkway) suggests the hydrogen explosion of March 12, 2012 had fairly little impact on the physical integrity of the containment. (NHK World; Mainichi Shimbun; Asahi Shimbun; Kyodo News; Japan Times)
- Tepco has intentionally stopped the de-chlorination system on F. Daiichi unit #4 spent fuel pool (SFP). Why? Because the entire pool’s water has been effectively de-chlorinated, and system operation is no longer necessary. The SFP Chloride level before the system went into operation more than a year ago was 1,944 parts per million. It has been reduced to about 9ppm, which meets Japan’s stringent fresh water standards. (Tepco Press Release)
- Tepco has finally admitted they had insufficient tsunami protective measures prior to 3/11/11, and they could have upgraded them well before that catastrophic date…but chose otherwise. This admission was made at the first meeting of Tepco’s independent nuclear advisory panel. The five-member panel is headed by former American NRC Chairman Dale Klein, and supported by four equally-independent experts. The panel has been convened to draw up a company-wide reform plan. The preliminary opinion of the group is that Tepco was able to have taken steps to prevent the Fukushima accident well in advance of the crippling tsunami, and a more effective company organization would have done it. In addition, the panel says that all nuclear employees should develop a “questioning attitude” toward nuclear safety. Chair Klein stated, “The challenge that TEPCO will have is establishing a culture so that every individual understands they are responsible for safety,” and that this is one of the critical differences between the American and Japanese nuclear programs. (NHK World; Kyodo News)
- Prime Minister Noda’s inspection of the F. Daiichi unit #4 Spent Fuel Pool has reignited fears of pool failure and potentially huge radiation releases. It seems Noda’s inspection was hoped to ease rumors that the building is dangerously tilting and frighteningly fragile. However, some people see it as a ploy to deflect reasonable concerns. Voices from around the world remain alarmed about the possibility of the reactor 4 building collapsing in the event of another major temblor, regardless. “There won’t be any more serious trouble unless something extraordinary happens,” said Hajimu Yamana, a Kyoto University professor who sits on the Tepco reform panel. He added, “[Still] you can’t totally deny the possibility of (another) gigantic earthquake…so we need to speed up work as far as unit 4 is concerned.” Lower House lawmaker Sumio Mabuchi, who headed a project to reinforce the reactor 4 building, says he feels the only way to insure no future catastrophe from unit #4 SFP is by filling every available space with concrete, “The reinforcement steps (adopted) were a first-aid measure, and I kept saying we should buttress the building with permanent measures. We believed (flooding the reactor 4 building) with concrete was necessary as a permanent measure, and held discussions about the subject. But right now, I don’t have any knowledge of current conditions.” On the other hand, Tepco says their detailed analyses of the unit #4 PCV, of which the SFP is an integral part, shows that it would take a quake many times worse than 3/11/11 to potentially weaken the existing SFP support structure. (Japan Times)
- The lack of temporary storage sites for decontamination residues continues to plague Fukushima Prefecture. Hundreds of thousands of bags containing Cesium-contaminated soil remain on the premises of the locations where they were generated. Decontamination has been undertaken in most of the 41 affected municipalities surrounding F. Daiichi, totaling about 4,500 properties. This is but 1.1% of those that have been identified for decontamination. In other words, the existing volume of undisposed material is but the tip of the eventual iceberg. Tokyo continues to plan for construction of a temporary storage facility in Futaba Town, but local opposition has kept the work from beginning. (NHK World)
- Shizuoka Prefecture’s assembly has rejected a petitioned request for a local nuclear referendum. The petition concerning the operation of the nukes at Hamaoka NPS was voted down on Thursday. A hastily-crafted amended version of the proposal was also rejected. Most assembly members say it would be inappropriate for the Prefecture to hold a referendum that would potentially impact Tokyo’s new national energy policy. Referendum supporters say the prefecture should back their citizen’s desire to have a say in the matter. Governor Heita Kawakatsu is one who supported the proposal. (NHK World)
