Mid 2008
Study commissioned
TEPCO's internal safety division commissions a tsunami risk assessment using updated geological data, including evidence of the 869 Jogan tsunami reaching further inland than 20th-century models had predicted.
Late 2008
15.7 metres predicted
Engineers complete the study. A credible tsunami of 15.7 metres is possible. The seawall stands at 5.7 metres. A wave of this height would overtop it by ten metres and flood the emergency diesel generators located in the basement.
Late 2008
Presented to management
The study reaches TEPCO's executive leadership. The engineers have done precisely what they were asked to do. The signal is clear, specific, and formally documented. The decision now belongs to the organization.
2009
"Further study warranted"
No substantive measures are taken. The study is sent to committees. The language shifts, "engineers recommend" becomes "engineers suggest we consider." Cost sensitivity and regulatory relationships slow the signal toward a stop.
2010
Decision delayed again
Additional modeling is proposed. The estimated cost to protect the plant stands at approximately one billion dollars. No single person in TEPCO's diffuse committee structure holds clear accountability to force a resolution.
Early 2011
Three years. Still no decision.
The 2008 study sits unresolved. The seawall has not been raised. The generators have not been relocated. No waterproof barriers have been installed. The signal has not been suppressed by a single decision, it has been buried by accumulated organizational inertia.
March 11, 2011, 3:27 PM
The wave arrives
A 14-metre tsunami strikes Fukushima Daiichi. The engineers had been within 1.7 metres. The wave overtops the seawall by more than eight metres. Twelve of thirteen emergency diesel generators are submerged within minutes. Three reactors melt down. 154,000 people are evacuated.
"Did not take any substantive measures in response to this assessment.", National Diet of Japan Investigation, 2012
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Companion resource
Signal architecture determines whether the right information reaches decision authority. The Decision Rights Resources cover what happens when it does, from the Deepwater Horizon episode.
All Signal Integrity resources
Timeline
2008 to 2011: Three years of delay
Meltdown sequence
41 minutes to three meltdowns
Decision pathway
How the signal died at each gate
Evacuation map
154,000 people, three expanding zones
Framework
Signal Line Protection, the three elements
Take the diagnostic
Signal Integrity Diagnostic tool