Even when confronted with a 2006 internal study that called for immediate steps to protect the Fukushima No. 1 nuclear power plant from towering 20-meter tsunami, Tokyo Electric Power Co. did nothing.
Even when confronted with a 2006 internal study that called for immediate steps to protect the Fukushima No. 1 nuclear power plant from towering 20-meter tsunami, Tokyo Electric Power Co. did nothing.
The rest, as they say, is history.
Five years after the report was issued, the plant was in ruins due to explosions caused by the 2011 natural disaster.
The Great East Japan Earthquake of March 11 spawned 15-meter tsunami that inundated the plant.
The latest revelation shows that TEPCO missed opportunity after opportunity to comply with forecasts about possible tsunami damage.
Internal documents obtained by The Asahi Shimbun detail assumptions about the size of tsunami that could strike the Fukushima plant as well as countermeasures and their costs.
For example, it was determined that 8 billion yen ($100.6 million) would be needed to construct a tide barrier to protect the plant against a 20-meter tsunami.
For TEPCO, the writing was on the wall.
The central government, alarmed by a massive tsunami in the Indian Ocean in 2004 that claimed an estimated 230,000 lives, approached TEPCO in 2006 to ascertain what steps it could take to withstand such an assault from the sea.
In 2008, TEPCO came up with a calculation that tsunami as high as 15.7 meters could strike the Fukushima plant.
On both occasions, the utility opted to do nothing.
The tsunami that struck the plant last year flooded the emergency generators installed at the No. 1 to No. 3 reactors. This knocked out the cooling systems for the reactor cores, which led to meltdowns in the three reactors and the release of huge volumes of radioactive materials.
That crisis might have been avoided or mitigated if TEPCO had bothered to take tsunami scenarios in earnest.
The internal documents obtained by The Asahi Shimbun concern a TEPCO training program at what was then the nuclear energy technology and quality safety department's facility design group. The training program was held between December 2005 and the following March.
According to the documents, the team looked at what equipment and facilities would be damaged based on tsunami heights. At that time, TEPCO assumed the maximum height of tsunami striking the Fukushima plant would be 5.7 meters, which proved to be a gross miscalculation.
A damage simulation for tsunami higher than 5.7 meters centered on steps that could be taken and associated costs.
The study found that if a 13.5-meter tsunami hit, the emergency generator and direct-current recharger would be flooded.
That, in essence, meant a loss of all electricity sources, which is what precisely occurred at the plant after last year's tsunami.
The study also estimated that it would cost 2 billion yen just to prevent flooding in the No. 5 reactor.
To make some of the facility capable of withstanding a 20-meter tsunami would have required constructing a 1.5 kilometer-long tide barrier around only the No. 5 and No. 6 reactors. The cost of that construction project alone was estimated at 8 billion yen.
According to TEPCO sources, the results of the training program were announced at an internal meeting that would normally be attended by department heads involved in the nuclear energy sector.
That suggests that high-ranking officials were aware of the study before last year's nuclear accident.
After the 2004 Indian Ocean tsunami, triggered by a massive earthquake off Sumatra, the Nuclear and Industrial Safety Agency held study sessions from January 2006 with electric power companies to discuss the threat of giant tidal waves striking facilities.
In October 2006, NISA officials asked the companies to begin considering what measures to implement.
However, TEPCO apparently didn't do anything on grounds there was only a low probability that a similar tsunami would strike.
A TEPCO official, referring to the 2006 internal study, said: "It is not a document that the company formally approved in order to implement measures. The study came up with a number of conclusions, but no consideration was given to whether a devastating tsunami would actually hit."