Has Unit #2 had a “phantom melt-through”?

TEPCO has made a brief endoscopic (visual) inspection inside the primary containment structure surrounding the unit two Reactor Pressure Vessel (RPV). What seems surprising to TEPCO and the Japanese Press, is no indication of melted fuel outside the RPV. TEPCO spokesperson Junichi Matsumoto told Japan Times, “We could not spot any signs of fuel, unfortunately.” He added that the endoscopic device used for the inspection only looked at a small portion of the interior, so a better inspection technology and longer visual examinations should find evidence of melted fuel having leaked from the RPV. Or will they?

I suspect the problem is neither technological nor temporal. I have maintained since the Fukushima Daiichi control room records were released in July that unit #2 probably did not experience a full, core-relocating meltdown. Severe fuel damage inside the fuel cell is a given. From the operator records, it seems the fuel cell was completely uncovered and had no cooling water flow whatsoever for up to 5 hours. With unit #2 generating the lowest decay heat rate and after four days of continual decay heat reduction, that isn’t enough time for a total catastrophic meltdown! Some melting is probable in the upper, central portions of the core. Perhaps even the severe degree of melting found at TMI in 1984. But not the core-relocating event postulated by TEPCO. In other words, TEPCO can look all they want, and express as much disappointment as they wish for not finding evidence of RPV melt-through, but I believe they are chasing a phantom. A few corium drips solidified on the vessel-penetrating control rod mechanisms? Maybe. But a melt-through just doesn’t seem likely to me, and the preliminary endoscopic images taken yesterday only add fuel to my fire.

This blog is probably the singular place on the internet you will find this speculation….I’ve been looking diligently for months and have found this assumption nowhere else. If I’m wrong, I’ll be the first to admit it and ask that my crow be served medium rare with fries and plenty of ketchup. But, that’s one meal I don’t think I’ll have to eat.

  • TEPCO is using a high-tech endoscope for inspection inside the unit #2 containment structure. The containment penetration is located 2.5 meters (~8 feet) above the floor of the outer reactor building. The endoscope is 8 millimeters in diameter, tipped with a 360o camera and temperature detector. (Mainichi Shimbun) Photos taken with the camera show the interior walls and piping within the massive structure. The photos were slightly blurred, probably due to the high humidity and severe radiation level in the drywell area. The pictures were not clear enough to show how high the water is above the floor. However, the high-tech thermometer showed internal temperature to be about 43oC, which conforms very well to the 45oC reading generated from the bottom head of the RPV. (NHK World) The images released by TEPCO show rusted metal surfaced caused by nearly 10 months of being subjected to an atmosphere saturated with moisture. The high-tech thermometer confirmed what TEPCO and the government have said since December; the temperature of unit #2 RPV has stabilized. Further, there is no apparent structural damage or other evidence of earthquake damage on March 11. (Japan Today) TEPCO expected to find water inside the containment to a depth of about 4.5 meters, but found no water level they could see. A metal “foothold” located at 4 meters above the floor is clearly not under water, so the actual surface of the water must be lower than that. Where the water level might be is not possible to guess, at this point. However, the extremely high humidity and a constant light rain of condensation inside the structure indicate there must be a lot of hot water inside the containment. (Japan Today)
  • TEPCO has found yet another volume of contaminated water which was previously unknown, this time in a pit near unit #2 reactor building. The pit houses a seawater pump. It is estimated that there is 500 tons of water in the pit. Analysis of the water shows a radioactive level of over 16,000 Becquerels per cubic centimeter. This is the highest radioactive Cesium concentration discovered in the last two months. It is unlikely any of the water in the pit has found its way into the ocean because contamination levels that high would have shown up in daily sea-side samples. (JAIF)
  • NISA has announced their preliminary opinion on the Oi power plant’s stress test results. The Agency says they find the results to be acceptable for possible restart. The meeting to announce the initial findings was delayed due to the number of protestors who demanded attendance. In order to avoid needless and rude protestor disruptions, as has been the case with NISA meetings in the past, the meeting was held in one room with the audience watched closed circuit TV in another. (Japan Times)
  • NISA’s Oi stress test announcement has meet with an avalanche of protestor criticisms. In fact, when NISA officials left the meeting, protestors surged from their seats and literally accosted the men with shouts and threats. One protestor shouted, “How can you assess the safety of a nuclear plant?” Another asserted, “You should allow us to listen to discussions in the meeting room instead of setting up seats for the audience in a separate room.” In a more dignified manner, University of Tokyo professor emeritus Hiromitsu Ino showed his anger by saying, “It’s wrong to draw a conclusion on the safety assessment of nuclear reactors even without setting clear standards for safety. Priority should be placed on reassessing all reactors’ safety while taking into consideration lessons learned from the Fukushima crisis. From the beginning, NISA had intended to give the green light to reactivation.” (Mainichi Shimbun)
  • The Oi stress test announcement in no way means the two power plants will be restarted. First, the International Atomic Energy Agency must critique the results of the test, which is scheduled to begin January 23. Second, there will be no restarts as long as local officials from the region near the Oi facility agree to power resumption. That will probably be the most difficult barrier to surmount. Governor Issei Nishikawa of Fukui Prefecture, home to the Oi Nuclear Power Station, said that stress tests are insufficient to determine whether the reactors can be restarted, “It’s nothing but a simulation. No clear standards have been set for how the results of such tests can be used to determine whether operations at the reactors can be resumed.” (Mainichi Shimbun)
  • The level of detectable Cesium in the foods consumed by most people in Fukushima Prefecture is 11 times higher than the typical person in Tokyo. This applies only to individuals who eat higher-than-normal volumes of fruits and mushrooms grown inside the prefecture. Those who eat lower volumes of the foodstuffs consume up to ten times less Cesium. (Asahi Shimbun) Regardless, no-one is exceeding Japan’s ridiculously restrictive national standards. The Asahi article merely demonstrates that no newspaper in Japan cares a bit about the mental anguish they are fomenting through their reports concerning any radiation level that is detectable.