The Nuclear and Industrial Safety Agency and Tokyo Electric Power Co. were aware at least by 2006 that the Fukushima No. 1 nuclear plant was at risk of having its power knocked out by massive tsunami, NISA officials said Tuesday.

According to the officials, the awareness was shared at a study session attended by several utilities that was held in response to the 2004 Sumatra quake and tsunami in Indonesia.

A paper compiled in August 2006 indicated the participants recognized that "there is a possibility that power equipment could lose their functions if 14-meter tsunami hit the Fukushima plant, with seawater flowing inside the (reactor) turbine buildings."

The agency, however, did not confirm whether the utilities disseminated this information internally, the officials said.

Countermeasures against huge tsunami were not taken and the plant on the coast of Fukushima Prefecture lost most of its power sources and hence the ability to keep its reactors and spent fuel pools cooled after massive tsunami overwhelmed the complex minutes after the March 11, 2011, Great East Japan Earthquake.

Tepco Chairman Tsunehisa Katsumata, who was the utility's president in 2006, testified Monday before a Diet-appointed panel investigating the crisis that he had not been provided the tsunami-threat information.

He said Tepco management might have been able to take countermeasures had it received the warning.

Katsumata also told the panel Monday that the visit by then Prime Minister Naoto Kan to the plant to assess the crisis hampered the response.

Noting that plant chief Masao Yoshida had to accompany Kan for about an hour when he visited the plant on March 12, 2011, Katsumata told the panel that Yoshida's main task was to manage the crisis, which in the following days resulted in three reactor meltdowns.

Katsumata also said Kan made "various inquiries directly" to Yoshida over the phone amid the extreme confusion. "To be honest, such (actions) were not good," he said.

Katsumata will step down in June, with Tepco expected to receive an injection of ¥1 trillion in public funds to avoid insolvency.

A new tsunami evacuation advisory system that uses mobile phone networks was tested Monday in the coastal city of Natori, Miyagi Prefecture.

Developed by Fumihiko Imamura, a professor of tsunami engineering at Tohoku University, and others, the system warns individuals via email messages on their mobile phones to move to the safest place near their current locations.

"The system will help reduce evacuation times. I hope it will be used by groups such as communities and those working to restore tsunami-hit areas," Imamura said.

A subscriber to the system first receives a notice that an earthquake has occurred, followed by another message recommending evacuation to a suggested place, which appears on a map.

(The Japan Times, 16/05/2012)