Tokyo Electric Power Company (TEPCO)
Fukushima Daiichi Nuclear Disaster
Estimated impact: $200B+ cleanup costs; 154,000 evacuees; region contaminated for decades
A magnitude 9.0 earthquake and tsunami caused three reactor meltdowns at Fukushima Daiichi. TEPCO had been warned that its tsunami defenses were inadequate but resisted upgrades to avoid regulatory scrutiny and shutdown costs. The backup diesel generators were placed in basements vulnerable to flooding.
Decision context
Whether to upgrade tsunami barriers and relocate backup generators based on updated seismic and tsunami risk assessments that showed the plant's defenses were inadequate.
Decision anatomy
Red = risk factor present · Green = protective factor present
Biases present in the decision
★ Primary driver · Severity estimated from bias type and decision outcome
Toxic combinations
Reference class base rates
Across all 143 curated case studies in our library:
Lessons learned
- Status quo bias: TEPCO treated existing tsunami barriers as adequate despite updated geological evidence showing larger historical tsunamis
- Loss aversion around shutdown costs prevented investment in safety upgrades that were trivial relative to the eventual catastrophe
- Optimism bias in nuclear safety assumes the worst case is bounded by historical experience, ignoring geological evidence of rarer, larger events
Source: National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission (NAIIC) Report (2012) (Post Mortem)
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Workflows that fire on decisions like Tokyo Electric Power Company (TEPCO)’s
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