ScribbleLive

uh, I hit the return button accidentally. What are some of the significant technical things we have learned?
.....that no technology is safe, certainly not nuclear power reactors.

Are there some individual incidents or moments that stick out in your head?
...the worried face of a young mother.

More cryptic pronouncements ( www.tepco.co.jp , p 28) on Unit 1 after the quake: "According to the alarm data record, right around the time of the MSIV closure signal, the main steam pipe rupture-related isolation signals were transmitted. However, the steam flow rate was recorded as 0 (zero), and no increase in steam flow rate was observed. [Attachment 6-1 (7)]
Judging from the above, it is considered that the isolation signal was transmitted
due to the loss of instrumentation power following the loss of off-site power. "
At that time, that is before the tsunami hit, there was diesel and battery power for sure.

Hi all – just logged on & catching up on the discussion we initiated last night about the location of the melted fuel in #2. I posted this last night, don’t know if it helps: ‘about unit 2, we presumed that the fuel (heat source) is likely to exist near the reactor-side pipe.'
And re the temperature sensors:
‘the thermometer three are nearly equally spaced. One had …. begun to rise, exceeding the 70 degrees on the night of 5. Two thermometers rest is left pointing to the front and rear both 44 degrees.' blog.goo.ne.jp’

Here is tepco's evaluation of the walk-through of Unit 1 we saw on video a couple of months ago in this report www.tepco.co.jp .
“3) Results of Unit 1 IC walk-down [Attachment 6-8 (3)]
・ The main unit of the IC installed in the Unit 1 reactor building, main pipes, and valves were visually investigated to confirm whether or not there was any damage that could cause the reactor to lose its cooling water. Since the inside of the PCV could not be entered, main body, pipes and valves outside of the PCV were investigated.
・ On the 4th floor of the reactor building where the main unit of the IC is installed, a hole was made on the north-side ceiling due to the hydrogen explosion on the 5th floor. Some of the insulating material at the top part of the IC's north side was scattered among the rubble and considered to have been blown off by the explosion. Furthermore, the insulating material on the south side of the main unit of the IC was also severely torn off and it had fallen down, which was on the reactor building equipment hatch (opening on the floor) side. It is considered that the hydrogen explosion on the 5th floor blasted through the opening and damaged the insulating material on the IC. None of insulating materials on the 3rd or 2nd floor was found to have been torn off or scattered.
・ No damage was found on the main unit of the IC. No ruptured pipes, leakage from flange sections, and broken valves were found. Also, no trace by a blast of the high pressure steam from the reactor was found.
・ Judging from the above, it was confirmed that there was no damage to the IC equipment located outside of the PCV that could have caused loss of reactor cooling water.
・ In addition to this field walk-down, the positioning status of IC valves and IC water level were also checked. It was confirmed that Valve 2A and Valve 3A of the Subsystem-A were open, and Valve 2B and Valve 3B of the Subsystem-B were closed. Not only that, both Subsystem-A and Subsystem-B that make up feed valves to the IC were also confirmed to be closed. The IC field water level gauges (cooling water) indicated 65% for
the Subsystem-A and 85% for the Subsystem-B. This was confirmed to match the
instrumentation in the MCR (main control room).”

@lillymunster , it contradicts the notion tepco reported to NISA last June that the IC had boiled dry in the early evening of Mar. 11. Of course, this inspection does not rule out internal damage. Because of the statements in this current report, we might keep a lookout for where the backup batteries precisely were installed. Not all were wiped out by the tsunami.

Here is a bit we saw as well www.tepco.co.jp , p. 41: "Heavy fuel oil tanks for boilers were washed away. Therefore, it is not possible to investigate the extent of damage caused by the earthquake. For EDG fuel tanks and condensate storage tanks (CSTs), which were one of the cooling water sources, ground subsidence around the basement was observed. It is considered to be as a result of the earthquake. However, no leakage or other damage was found on the tanks themselves.
《photo (7) and photos (8), (9)."

@Peter note where they found batteries 'As the operators surveyed the damage, they quickly realized that the diesel generators couldn't be salvaged and that external power wouldn't be restored anytime soon. In the plant's parking lots, workers raised car hoods, grabbed the batteries, and lugged them back to the control rooms. They found cables in storage rooms and studied diagrams. If they could connect the batteries to the instrument panels, they could at least determine the water levels in the pressure vessels'. spectrum.ieee.org

Here is tepco's damage summary from this report www.tepco.co.jp p 49:
"1) The tsunami after the earthquake caused emergency seawater system pump equipment
to lose its function at all units. This prevented residual heat (decay heat) from being removed
from the reactor by seawater.
2) Loss of power supply function at Units 1 to 5 caused all motor-operated facilities
(safety systems, water injection and cooling equipment, etc.) to be rendered unusable.
Motor-operated valves were no longer operable from the MCR.
3) At Units 1, 2, and 4, where DC power was also lost, all monitoring instruments in the
MCR became unavailable, preventing the monitoring of the plant status. At Units 3 and 5,
where DC power was available, measurements and monitoring of the plant condition were
influenced by the battery levels. - 50 -
4) SRVs for reactor depressurization and solenoid valves for controlling air-operated vent
valves for the PCV also became inoperable.
5) In addition, lack of communication tools and power outages that affected lighting in
the MCRs, buildings, and outside field made emergency response even more difficult.
6) Debris and residual water due to the tsunami and the risk of further tsunami made the
working environment much harder in the field outside."

@lillymunster this is news to me: according to Wikipedia there was MOX in the 'Central Storage Facility' - assume means the Common SFP