March 15th, 2011 – Fukushima Daiichi Timelines from TEPCO and NISA press releases

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From:Sigmon, Rebecca
Sent:Tuesday, March 15, 2011 2:08 PM
To:Hasselberg, Rick
Cc:King, Mark; Thomas, Eric
Subject:Timelines for Daiichi Units 1 and 4
Attachments:2011 fukushima daiichi unit 1 timeline.doc; 2011 Fukushim-DaiichiUnit 4 Timeline.docx


Attached are timelines for Units 1 and 4. Most of the information for Unit 1 came from the press releases put out by TEPCO and NISA (noted after each comment). One observation – neither TEPCO nor NISA refers to the explosion at Unit 1 as a hydrogen explosion at any point; they initially refer to it as a loud noise and white smoke following an earthquake centered near the plant. Following the explosion at Unit 3 though, the comments about the Unit 3 explosion reference the similar explosion at Unit 1, they just never update any of the previous information about Unit 1.

There wasn’t much out there about Unit 4 yet. TEPCO and NISA don’t have any press releases out yet about any of this morning’s events there, so what I do have is from news sites and Hope this meets your needs, let me know if you want me to focus on any area in particular and see what else is out there.

(all times are local (Tokyo) time)

Rebecca Sigmon
Reactor Systems Engineer
Operating Experience Branch
(301) 415-4018
[email protected]

Fukushima-Daiichi Unit I (all times Tokyo) (source of information)

1446 Automatic shutdown due to earthquake, loss of offsite power (TEPCO)
1541 Loss of emergency AC power, declaration of “1st Level Emergency” – Article 10(TEPCO)
1636 Declaration of Article 15 due to inability to verify coolant injection. Water level verification temporarily restored, Article 15 re-declared at 1707 (TEPCO)
2200 Evacuation ordered within 3 km (TEPCO)
2400 Status Update (TEPCO): Unit 1 shutdown and cooled by isolation condenser

Possible radiation release due to decreasing water level

3/12/2011 0300 Decision made to reduce containment pressure for units that cannot confirm water injection by RCIC (TEPCO)
0520 Radiation levels near the main gate have risen from .07 uSv/hr (7 mRem) to (NISA):
MP6 .59 uSv/hr (59 mRem)
MP8 .38 uSv/hr (38 mRem)
0600 Increasing levels of radiation measured by monitoring car, and one radiation monitoring
post shows radiation levels greater than normal (TEPCO)
0700 Evacuation ordered out to 10 km (TEPCO)
0700 Status Update (NISA):
Unit 1 is in Article 15 “Nuclear Emergency Situation”
Work in progress to connect electric generating cars to power pumps for water injection Containment vessel pressure could be as high as 840 kPa (design pressure 400 kPa)
0755 Radiation levels (NISA):
MP6 5.1 uSv/hr
MP8 2.5 uSv/hr
0940 Radiation levels (NISA)
MP6 5.1 uSv/hr
MP8 2.9 uSv/hr
1000 Containment pressure reduction ordered by government (TEPCO)
1100 Steam release in progress to relieve containment pressure (NISA)
1100 Status Update (TEPCO):
Reactor was cooled by isolation condenser, but that has since stopped.
Containment pressure increasing
Containment pressure reduction in progress
Reactor water level decreasing
1430 Successful reduction of containment pressure completed (TEPCO)
1500 One employee reported to have received 100 mSv exposure (10 Rem) (TEPCO)
1529 Large earth motion due to earthquake with close epicenter caused loud noise and white
smoke from unit 1, reading of 500 uSv/hr at site boundary (NISA)***
1536 Explosion noted at Unit 1, mentioned as due to an earthquake very close to the site, 4
personnel injured (TEPCO)***
***Neither TEPCO nor NISA refers to this as a hydrogen explosion from Unit I in any of their
communications at any point. Following the explosion from Unit 3 around 1100 on 3/14 though,
both TEPCO and NISA comment that what happened at Unit 3 is similar to what happened at
Unit I
1536 Hydrogen explosion in the space between the concrete containment and the reactor’s
primary system, but the explosion did not damage the containment function or the reactor
system (News Conference with Japanese Cabinet Secretary Edano)
1617 Article 15 “Radiation Disaster Measure” declared due to radiation levels at site boundary
exceeding limits (TEPCO)
1911 Evacuation order extended out to 20 km (TEPCO)
2005 Radiation levels (NISA):
MP4 (monitoring car at site boundary NW of units) 1015 uSv/hr
MP6 (main gate) 3.25 uSv/hr
MP8 (observation platform) 2.06 uSv/hr
2020 Injection of seawater into core followed by boric acid (TEPCO)
2215 Suspension of seawater injection following aftershock and tsunami alert (TEPCO)
2300 Continuation of containment pressure reduction efforts (TEPCO)
0200 Seawater/boric acid injection recommenced at some point before 0300 update (TEPCO)
0400 Radiation levels (NISA):
MP4 40 uSv/hr
MP6 3.1 uSv/hr
MP8 4.5 uSv/hr
0550 Radiation level (NISA):
MP6 3.2 uSv/hr
0856 Radiation levels at the site boundary, which had been decreasing, increased again
above the limit, causing a renewed declaration of Article 15 “Radiation Disaster Measure”
0930 Radiation level (NISA):
MP6 26 uSv/hr
1155 Seawater is being injected into containment via fire extinguishing system line (NISA)
1220 Radiation level (NISA):
MP4 47.1 uSv/hr
1500 Coordinating with authorities to determine how to cool spent fuel pool (TEPCO)
1930 Radiation levels (NISA)
MP4 44 uSv/hr
MP6 5.2 uSv/hr
0110 Interruption of seawater injection to Unit 1 due to lack of seawater in pit (NISA)
0250 Radiation level (NISA):
MP6 66.3 uSv/hr
0408 Radiation level (NISA):
MP4 56.4 uSv/hr
1234 Radiation level (NISA)
MP6 4.2 uSv/hr
1930 Plant Parameters (NISA)

Reactor Pressure .047/.270 MPa
Primary Containment Pressure Not Available
Reactor Water Level Low off scale
Suppression Pool Water Temp Not Available
Suppression Pool Water Pressure Not Available

Fukushima-Daiichi Unit 4
Unit was shutdown at the time 6f the earthquake and tsunami for regular inspection.
All TEPCO updates through 1500 on 3/13/2011 indicate that reactor level is stable, and there is
no known reactor coolant leakage into the containment vessel.
All NISA updates through 1930 on 3/14/2011 state that Unit 4 is in periodic inspection outage
with no other information on Unit 4. This is the most recent NISA press release available as of
1300 on 3/15/2011.

2100 General comment for Daiichi site about coordination to ensure cooling of the spent fuel

0600 Loud explosion heard on the site. The 4 th floor rooftop of the Unit 4 reactor building was
found to be damaged (TEPCO)
0600 Fire burning in the Unit 4 spent fuel pool (press conference with Cabinet Secretary
0938 Fire reported in Unit 4 reactor building believed to be from a lube oil leak from the recirc
pump drive system. Fire fighting efforts were successful, though the roof of the building was
damaged (
1100 Radiation level near Unit 4 -10 Rem/hr, 821 mrem/hr at the site boundary (

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