Japan Earthquake: nuclear plants

Here you go:

http://www.osti.gov/bridge/servlets/...Hq/5835351.pdf

The 7th mid long term meeting was held on 25 June: http://www.meti.go.jp/earthquake/nuc...120625_02.html

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuc...120625_02n.pdf Progress status of ground water bypass study

The 7th mid long term meeting was held on 25 June: http://www.meti.go.jp/earthquake/nuc...120625_02.html

3-2 Treatment of accumulated water
http://www.meti.go.jp/earthquake/nuc...120625_02k.pdf Subdrain purification test report

The English-language executive summary of The Fukushima Nuclear Accident Independent Investigation Commission was just released a few minutes ago. You can download it from here:

http://naiic.go.jp/en/

The government-run investigation committee’s interim report, NISA’s “Technical Findings,” and specifically TEPCO’s interim report, all concluded that the loss of emergency AC power—that definitely impacted the progression of the accident— “was caused by the flooding from the tsunami.” TEPCO’s report says the first wave of the tsunami reached the site at 15:27 and the second at 15:35. However, these are the times when the wave gauge set 1.5km offshore detected the waves, not the times of when the tsunami hit the plant. This suggests that at least the loss of emergency power supply A at Unit 1 might not have been caused by flooding. Based on this, some basic questions need to be logically explained before making a final determination that flooding was the cause of the station blackout.

4. Several TEPCO vendor workers who were working on the fourth floor of the nuclear reactor building at Unit 1 at the time of the earthquake witnessed a water leak on the same floor, which houses two large tanks for the isolation condenser (IC) and the pip- ing for IC. The Commission believes that this was not due to water sloshing out of the spent fuel pool on the fifth floor. However, since we cannot go inside the facility and perform an on-site inspection, the source of the water remains unconfirmed.

5. The isolation condensers (A and B2 systems) of Unit 1 were shut down automatically at 14:52, but the operator of Unit 1 manually stopped both IC systems 11 minutes lat- er. TEPCO has consistently maintained that the explanation for the manual suspen- sion was that “it was judged that the per-hour reactor coolant temperature excursion rate could not be kept within 55 degrees (Celsius), which is the benchmark provided by the operational manual.” The government-led investigation report, as well as the government’s report to IAEA, states the same reason. However, according to several workers involved in the manual suspension of IC who responded to our investiga- tion, they stopped IC to check whether coolant was leaking from IC and other pipes because the reactor pressure was falling rapidly. While the operator’s explanations are reasonable and appropriate, TEPCO’s explanation is irrational.

6. There is no evidence that the safety relief (SR) valve was opened at Unit 1, though this should have taken place in the case of an accident. (Such records are available for Units 2 and 3.) We found that the sound of the SR valve opening for Unit 2 was heard at the Central Control Room and at Unit 2, but no one working at Unit 1 heard the sound of the Unit 1 SR valve opening. It is therefore a possibility that the SR valve might not have worked in Unit 1. In this case, a minor LOCA caused by the seismic motion could have taken place in Unit 1.

25 June 2012 government-Tokyo Electric mid and long term response committee, steering committee (7th meeting)

3-1 Cooling by closed loop water injection
http://www.meti.go.jp/earthquake/nuc...120625_02g.pdf Unit 2 alternative thermometers installation progress status

28 March 2012 government-Tokyo Electric mid and long term response committee, steering committee (4th meeting)

http://www.meti.go.jp/earthquake/nuc...120328_02f.pdf page 7 is about the revision of priorities for installation of alternative thermometers. The high radiation routes are cancelled. What is left is Jet Pump system B X-40C/D in area B with priority 1, SLC differential pressure sensor X-51 in area C with priority 2, and TIP in area D as priority (1) with a note. The note says: "there is a possibility that the TIP guide tubes are surviving in the outer surroundings of the core (see page 8). →If undamaged TIP guide tubes are left, they can be promoted to priority 1." The figure in the left part of page 8 shows a yellow area where surviving TIP tubes are believed to exist.

Analyses of core melt and re-melt in the Fukushima Daiichi nuclear reactors
http://www.tandfonline.com/doi/full/...48.2011.636537

Analyses of core melt and re-melt in the Fukushima Daiichi nuclear reactors
http://www.tandfonline.com/doi/full/...48.2011.636537