ScribbleLive

Research on the Mark-I calculated RPV melt-through in under 14 hours www.ornl.gov www.osti.gov www.osti.gov

And TEPCO reported on the 13th that upon reflooding, “the water level within the pressure vessel [reactor] did not rise for a long time.” www.tepco.co.jp The failure of the water level to rise despite inflowing water is consistent with the water flowing out of the reactor. That the level did eventually rise is consistent with the level in the exterior containment vessel eventually rising high enough to allow the water in the reactor to finally rise.

@Edano, not a big deal, but the time you cite "seawater injection: 3/13 16:34" does not match Tepco's press release of March 13, which states: "we began injecting water containing boric acid that absorbs neutron into the reactor by the fire pump from 09:25AM, Mar 13." www.tepco.co.jp As for NISA saying when core breech occurred, what is there basis? The NRC says the nutron emitters Arnie attributes to the SFPs came from a core or cores. The explosion of Unit 3 is the most obvious vehicle for such relocation. @Edano, not a big deal, but the time you cite "seawater injection: 3/13 16:34" does not match Tepco's press release of March 13, which states: "we began injecting water containing boric acid that absorbs neutron into the reactor by the fire pump from 09:25AM, Mar 13." www.tepco.co.jp

As for NISA's core-breach time, what is their basis? The NRC says the neutron emitters Arnie attributes to the SFPs came instread from a core. The explosion of Unit 3 is the most obvious vehicle for such relocation,and if so, core contents must have been available for relocation.

@Edano, I don't know. There does seem to be an innocuous error in that same Tepco press release of March 13. Right on top it says, "Miyagiken-Oki Earthquake that occurred yesterday at 2:46PM." But yesterday on the 13th was March 12, yet the quake was March 11.

From the NISA report to IAEA, p12-13:
"3) Fukushima Dai-ichi NPS Unit 3
∙ (Loss of Power supply) The reactor was scrammed by the earthquake at 14:47 on March 11,
and the external power supply was lost and two emergency diesel generators started up. The
two emergency diesel generators were stopped by the tsunami and all AC power was lost at
15:41 on the same day.
∙ (Cooling of the reactor) The Reactor Core Isolation Cooling System (RCIC) was manually
started at 15:05 on March 11. It stopped automatically at 15:25 on the same day due to the
rise of the reactor water level. It was started manually at 16:03 on the same day, and the RCIC
stopped at 11:36 on March 12. The High Pressure Core Injection System (HPCI)
automatically started due to the reactor low water level (L-2) at 12:35 on the same day, and
the HPCI stopped at 2:42 on March 13. The reason for that appears to be a drop of pressure in
the reactor. The other probable cause could be water-vapor outflow from the HPCI system.
∙ (Status of the reactor core) The operation for injection of water containing boric acid
commenced using a fire extinguishing line at around 9:25 on March 13. However, the water
could not be injected sufficiently due to the high pressure in the reactor, and the water level in
the reactor lowered. As a result, water injection was halted at least for 6 hours and 43 minutes
after the HPCI stopped at 02:42 on March 13 until water injection using the fire extinguishing
line started at 09:25 on the same day. According to the results of NISA’s analysis, the fuel
appears to have been exposed due to a drop of the reactor water-level at around 08:00 on
March 13, and the core started melting afterwards. A considerable part of melted fuel seems
to have moved to and accumulated at the bottom of the RPV. However, there is a possibility
that the bottom part of the RPV is damaged and a part of the fuel has dropped and 13
accumulated at the dry well floor (lower pedestal).
∙ (Hydrogen explosion) A wet well vent operation of the PCV was carried out at 05:20 on
March 14. A hydrogen explosion occurred at the reactor building at 11:01 on the same day. It
seems that zirconium and water reacted along with a rise in the temperature in the PCV, and
that gas containing hydrogen by such ways as leakage from the PCV accumulated in the
upper area of the reactor buildings triggered a hydrogen explosion. "

@Edano I wonder whether either or both of these significant quakes may have aggravated matters at Daiichi back in March?
18:56 19 March 2011 Northern Ibaraki Prefecture M6.1 depth 20 km
07:12 23 March 2011 Southeastern Fukushima Prefecture M6.0 depth 10 km
The one on the 23rd was very shallow, almost a direct hit on the NPP, came with no warning, and seemed to be followed by another approximately half an hour later. See here: www.youtube.com
Figure 1 on this page labels 7 inland quakes M>6 but lists and briefly describes only 5 of them: unit.aist.go.jp