Nuclear plant’s tsunami plan was based on single page memo

JAPANESE nuclear regulators trusted that the reactors at Fukushima Dai-ichi were safe from the worst waves an earthquake could muster based on a single-page memo from the plant operator nearly a decade ago.

In the December 19, 2001 document — one double-sized page obtained by The Associated Press under Japan’s public records law — Tokyo Electric Power Co rules out the possibility of a tsunami large enough to knock the plant offline and gives scant details to justify this conclusion, which proved to be wildly optimistic.

Regulators at the Nuclear and Industrial Safety Agency, or NISA, had asked plant operators for assessments of their earthquake and tsunami preparedness. They didn’t mind the brevity of TEPCO’s response, and apparently made no moves to verify its calculations or ask for supporting documents.