Photo/IllutrationA collapsed crane and other debris at the crippled Fukushima No. 1 nuclear power plant after tsunami devastated the area on March 11, 2011 (Provided by Tokyo Electric Power Co.)

The Tokyo District Court on Sept. 5 accepted the written statement of a former Tokyo Electric Power Co. executive who claimed that his boss abruptly postponed tsunami prevention measures at the Fukushima No. 1 nuclear power plant in 2008.

The postponement reportedly occurred almost three years before the plant was engulfed by a tsunami on March 11, 2011, resulting in the most serious nuclear accident since the 1986 Chernobyl disaster.

The statement was made by Kazuhiko Yamashita, former head of TEPCO's center tasked with compiling steps against tsunami at the earthquake countermeasures, to prosecutors from 2012 to 2014. It was read out during the 24th hearing at the court on Sept. 5.

Tsunehisa Katsumata, 78, former TEPCO chairman, former TEPCO Vice President Sakae Muto, 68, and Ichiro Takekuro, 72, former TEPCO vice president, are on trial on charges of professional negligence resulting in death and injury from the 2011 nuclear disaster.

Yamashita's statement, recorded by investigators, supported arguments by lawyers serving as prosecutors that “defendants postponed measures to protect the plant despite having recognized the necessity for such measures.”

To prove negligence, prosecutors are trying to show that the top executives could have predicted the height of the tsunami that swamped the plant.

Defense lawyers have argued that “the nation’s earthquake forecast was not reliable and measures against tsunami had not been decided yet.”

According to Yamashita's statement, the three executives approved the implementation of anti-tsunami prevention measures based on earthquake forecast issued by the government professional body but later put off the enforcement of the measures at the plant.

Yamashita was originally scheduled to provide sworn testimony. Instead, Presiding Judge Kenichi Nagabuchi accepted Yamashita’s statement, saying, “(Yamashita) is not in a condition able to testify at the court.”

The statement said TEPCO initially considered options based on a long-term assessment of the probability of major earthquakes released by the science ministry’s Headquarters for Earthquake Research Promotion in 2002.

The utility estimated that a tsunami more than 7.7 meters high could hit its Fukushima No. 1 nuclear power plant based on its trial calculation.

In February 2008, when Yamashita proposed the tsunami measures in light of a long-term tsunami risk assessment during a meeting in which Katsumata and two other executives attended, the policy was accepted without opposition and was also adopted at a managing directors' meeting the following month.

Based on Muto's instructions, the team had mulled procedures on obtaining a permit to build a seawall to protect the Fukushima No. 1 plant, according to a TEPCO employee who testified at an April hearing.

However, when a TEPCO subsidiary conducted a detailed study on the maximum height of a tsunami on the basis of the assessment, it found in March the same year that a tsunami of “a maximum 15.7 meters” could engulf the Fukushima plant, surpassing the 10-meter height of the site of the plant where major facilities were located.

The findings were reported to TEPCO executives in June 2008 and then to Muto.

Muto in July 2008 decided to put off measures based on the 15.7-meter estimate, according to the statement.

TEPCO’s policy shift was the result of its “executives’ recognition that such measures require massive construction and would make it difficult for TEPCO to explain to the central government and locals that the plant was still safe, which could lead their demands for halting operations of the plant,” the statement said.

“I was surprised that a TEPCO executive had already revealed the inside details of the entity to such an extent,” said lawyer Yuichi Kaido, who is acting on behalf of the independent judicial panel of citizens who recommended the indictment of the three former TEPCO executives. “(TEPCO’s) extraordinariness that it did nothing because it couldn’t take measures was clearly exposed.”