The operator of the crippled Fukushima nuclear plant on Friday admitted it had played down the risks of a tsunami to the facility for fear of the financial and regulatory costs.
The admission is one of the starkest yet by Tokyo Electric Power Company (TEPCO), which has been criticised for trying to shirk responsibility for the worst nuclear disaster in a generation.
The report says before the huge waves of March 2011 smashed into the plant the company was aware defences against natural disasters were not sufficient, but did not act because of the possible consequences.
"There was a latent fear that plant shutdown would be required until severe accident measures were put in place," Tokyo Electric Power Company (TEPCO) said in a report.
The company document, entitled "Fundamental Policy for the Reform of TEPCO Nuclear Power Organization" says insufficient planning was done to prepare for a natural disaster at the plant.
"There was concern that if new severe accident measures were implemented, it could spread concern in the siting community that there is a problem with the safety of current plants."
Explore further: Record high radiation at crippled Japan nuke plant