Photo/IllutrationKiyoshi Kurokawa, chairman of the Fukushima Nuclear Accident Independent Investigation Commission, presents the final report to Lower House Speaker Takahiro Yokomichi, right, in July 2012. (Asahi Shimbun file photo)

Five years after the accident at the Fukushima No. 1 nuclear power plant, the Diet is still sitting on a trove of raw documents and testimonies of more than 1,100 individuals who were on the front lines during the crisis.

The cache was compiled by the Fukushima Nuclear Accident Independent Investigation Commission, which released a report of its findings that totaled about 600 pages in July 2012.

The documents collected by that commission, including the testimonies of 1,167 individuals, have still not been released to the public more than four years after its disbandment.

Yasunori Sone, a political science professor at Tokyo's Keio University, said the documents should, in principle, be released to the public because the investigation was conducted by the Diet on behalf of the people.

"The Fukushima Nuclear Accident Independent Investigation Commission was the first established in the Diet with the authority to carry out a thorough investigation," Sone said. "Disclosure rules should be decided on quickly because it will serve as a precedent for future commissions."

However, the documents submitted to the commission by the central government as well as Tokyo Electric Power Co., operator of the Fukushima plant, remain in storage at the National Diet Library, along with more than 900 hours of questioning of the 1,167 individuals, many of whom worked to bring the accident under control.

Some of the testimony was given on condition that it would not be released.

For that reason, after the commission disbanded, the rules and administration committees of the two chambers of the Diet were to have established rules for disclosing the commission records.

The commission had left behind a record of its investigation as well as the source of the documents it had accumulated because it felt that it would be helpful when the documents were eventually released.

"It will be possible to learn about the background to the nuclear accident from new reports or books that are written based on the documents," said Kiyoshi Kurokawa, a professor emeritus at the University of Tokyo, who chaired the commission. "A fundamental point to not repeating mistakes is to learn from one's past errors."

Discussions within the rules and administration committees were disrupted when then Prime Minister Yoshihiko Noda dissolved the Lower House in November 2012 and called a snap election.

The December election brought the Liberal Democratic Party and its junior coalition partner, Komeito, back in control of government.

A multiparty group of lawmakers who were seeking to end dependence on nuclear energy asked that the rules and administration committees resume work on establishing disclosure rules. However, a subcommittee held one session that focused on presenting the opinions of members.

"Both the ruling and opposition parties are hesitant about releasing the documents because there is the possibility that they contain contents that are disadvantageous to the LDP, which had pushed nuclear energy, and the then Democratic Party of Japan, which had to deal with the nuclear accident," said a member of that multiparty group.

The disclosure of the documents is not the only area in which the Diet has been less than aggressive.

In its report, the commission included seven recommendations, including the establishment of a new independent investigation committee, made up mainly of experts from the private sector, to conduct further studies into unanswered questions about the accident.

However, the rules and administration committees have yet to discuss the possibility of establishing such an investigative committee.

The commission also recommended the establishment of special committees in both chambers of the Diet to oversee the nuclear regulatory structure.

In 2013, a Special Committee for Investigation of Nuclear Power Issues was established separately in the two chambers.

However, those special committees have been turned into venues to promote nuclear energy. For example, committee members who were originally from labor unions of the electric power companies or who represented districts where nuclear plants were based criticized the Nuclear Regulation Authority for its strict standards regarding the resumption of operations at nuclear plants.

In a similar manner, the special committees also asked for a review of the rule that limited nuclear plants to a maximum 40-year operating life.

Tomoko Abe, a Democratic Party member who serves as secretary-general of the multiparty group seeking zero nuclear power generation, said, "Although there are some issues regarding the nuclear accident that have become clearer with the passage of time, the arena for looking into those issues has been closed off. It is the responsibility of the legislative branch to set up a structure that will continue to examine the nuclear accident."