The commission itself was the first of its kind in Japan. Independent, third party accident investigation commissions have been established in a number of foreign countries in response to serious accidents, but never in Japan. In a surprise move, the Diet even granted them the power of subpoena. In the U.S., the Kemeny Commission that investigated the nuclear accident at Three Mile Island is well known.

The final report spans over 600 pages but there are some findings that were of particular interest:

The earthquake may have played a role in the meltdown

NAIIC said there was credible evidence that initial damage from the 9.0 magnitude earthquake that preceded the tsunami's arrival had caused damage to the plant, and played a role in the accident.

"We cannot rule out the possibility that a small-scale LOCA (loss-of-coolant accident) occurred at the reactor No. 1 in particular."

The relation of the earthquake to the meltdown is still not clear but as The Atlantic Wire noted last year, there were reports of piping breaking and coolant loss in the 40 minutes before the tsunami came and knocked out most of the power to the plant.

The government and TEPCO had previously been reluctant to admit the earthquake may have contributed to the disaster, sticking to the belief that rising waters from the tsunami knocked out cooling systems at the plant and triggered reactor meltdowns. TEPCO in their own "self-serving" internal report released last month, still stuck to the defense that the chief cause of the accidents was the enormity of the tsunami that hit the plant, "which was beyond all expectations."

The commission not only cast doubts on the role of the tsunami, it also found that TEPCO was well aware of the tsunami risk.

"It is impossible to limit the direct cause of the accident to the tsunami without substantive evidence. The Commission believes that this is an attempt to avoid responsibility by putting all the blame on the unexpected (the tsunami), as they (TEPCO) wrote in their midterm report, and not on the more foreseeable earthquake. Through our investigation, we have verified that the people involved were aware of the risk from both earthquakes and tsunami. Further, the damage to Unit 1 was caused not only by the tsunami but also by the earthquake."

Who is at fault? Why did the accident happen?

The report placed blame on the Japanese government, the regulatory agencies that were too cozy with the Tokyo Electric Power Company, but mostly TEPCO.

The report catalogs failure after failure to respond to safety risks, even after they were known. They failed to follow advice from the United States as well.

One passage in particular, is a microcosm of the many screw-ups that led to what may be the worst meltdown in atomic history. The final sentence, in italics, makes TEPCO and NISA (The Nuclear and Industrial Safety Agency) out to be the grand villains in this atomic tragedy:

Since 2006, the regulators and TEPCO were aware of the risk that a total outage of electricity at the Fukushima Daiichi plant might occur if a tsunami were to reach the level of the site. They were also aware of the risk of reactor core damage from the loss of seawater pumps in the case of a tsunami larger than assumed in the Japan Society of Civil Engineers estimation. The Nuclear and Industrial Safety Agency (NISA) knew that TEPCO had not prepared any measures to lessen or eliminate the risk, but failed to provide specific instructions to remedy the situation. We found evidence that the regulatory agencies would explicitly ask about the operators’ intentions whenever a new regulation was to be implemented. For example, NISA informed the operators that they did not need to consider a possible station blackout (SBO) because the probability was small and other measures were in place. It then asked the operators to write a report that would give the appropriate rationale for why this consideration was unnecessary. The regulators also had a negative attitude toward the importation of new advances in knowledge and technology from overseas. If NISA had passed on to TEPCO measures that were included in the B.5.b subsection of the U.S. security order that followed the 9/11 terrorist action, and if TEPCO had put the measures in place, the accident may have been preventable. There were many opportunities for taking preventive measures prior to March 11. The accident occurred because TEPCO did not take these measures, and NISA and the Nuclear Safety Commission (NSC) went along. They either intentionally postponed putting safety measures in place, or made decisions based on their organization’s self interest, and not in the interest of public safety.

Sources close to the investigation stated that TEPCO and NISA were extremely uncooperative in providing materials, and the commission had to use their legislative mandate to order NISA and TEPCO to turn over documents and others data on more than ten occasions. TEPCO, which has a dark history of cover-ups and collusion with anti-social forces, surprised no one by their lack of cooperation. (Note: The usually cool-headed Chairman Kurokawa, during the hearings, did at one point loose his cool with the evasive answers of TEPCO executives, and looked like he wished to chant, “Liar, Liar, Pants on Fire/Hang Yourself On a TEPCO wire”. It certainly seemed that way.)