According to World Nuclear Association, the tsunami countermeasures taken when Fukushima Daiichi was designed and sited in the 1960s were considered acceptable concerning the scientific knowledge then, with low recorded run-up heights for that particular coastline. But some 18 years before the 2011 disaster, new scientific knowledge had emerged about the likelihood of a large earthquake and resulting major tsunami of some 15.7 meters at the Daiichi site. However, despite this new information, this had not yet led to any major action by the plant operator, Tepco, or government regulators, notably the Nuclear & Industrial Safety Agency (NISA). The discussion around this new information was ongoing, but the action was minimal. The tsunami countermeasures should also be reviewed following International Atomic Energy Agency (IAEA) guidelines which required taking into account high tsunami levels, but NISA continued to allow the Fukushima plant to operate without sufficient countermeasures such as moving the backup generators up the hill, sealing the lower part of the buildings, and having some backup for seawater pumps, despite clear warnings.

A report from the Japanese government's Earthquake Research Committee on earthquakes and tsunamis off the Pacific coastline of northeastern Japan in February 2011 was due for release in April and might, after 18 years of inaction, have brought about changes. The document includes an analysis of a magnitude 8.3 earthquake known to have struck the region more than 1140 years ago, triggering enormous tsunamis that flooded vast areas of Miyagi and Fukushima prefectures. The report concludes that the region should be alerted of the risk of a similar disaster striking again. The 11 March earthquake measured magnitude 9.0 and involved the substantial shifting of multiple sections of the seabed over a source area of 200 x 400 km. Tsunami waves devastated wide areas of Miyagi, Iwate, and Fukushima prefectures.

Summing up, the Fukushima nuclear accident occurred due to the lack of actions of the Japanese nuclear authorities moving the backup generators up the hill, sealing the lower part of the buildings, and having some backup for seawater pumps, despite clear warnings and new scientific knowledge about the likelihood of a large earthquake and resulting major tsunami of some 15.7 meters at the Daiichi site. The tsunami countermeasures should also be reviewed following International Atomic Energy Agency (IAEA) guidelines which require considering high tsunami levels.

Thank you.

I based it on the NETFLYX THE DAYS (

https://movieweb.com/netflix-the-days-true-story-nuclear-disaster/ ) to quote ISHIKAWA. Despite the preliminary care, the film shows that there were design flaws in the construction of the plant and some professionals, who were not from the area, being responsible for important decisions. Access to the plant's plants was in printed manuals and not with online access. From what I've seen, I think the reaction of the technical authorities was more political than technical.

Other nuclear accidents and incidents in Japan:

1- March 1981. INES Level 2. Overexposure of workers: More than 100 workers were exposed to doses of up to 155 millirems per day of radiation during repairs of a nuclear power plant.

2- June 1999. INES Level 2. Shika plant, Ishikawa Prefecture. Control rod malfunction: Operators attempting to insert one control rod accidentally withdrew three, causing a 15-minute uncontrolled sustained reaction at the number 1 reactor of Shika Nuclear Power Plant.

3- 30 September 1999. INES Level 4. Ibaraki Prefecture. Accidental criticality: During the preparation of a uranyl nitrate solution, uranium in the solution exceeded the critical mass at a uranium reprocessing facility in Tokai-mura northeast of Tokyo, Japan. Three workers were exposed to (neutron) radiation doses in excess of allowable limits. Two of these workers died. 116 other workers received lesser doses of 1 mSv or greater though not in excess of the allowable limit.

The Japanese are not stupid, they just need energy at any cost, even if a nuclear power plant is built on a volcano