One year ago this week, a nuclear fuel processing plant in Tokai-mura, Ibaraki Prefecture, experienced a "criticality." That accident shattered once and for all the crumbling myth of safety that has encased Japan's nuclear power industry, and changed the way Japanese view nuclear power.

The official version of events places the blame on human error. Since the accident, government and the nuclear power industry have eagerly promoted this version in an effort to put distance between the industry as a whole and the Tokai-mura accident at JCO Co. (not an acronym).

As Dr. Jinzaburo Takagi documents in his new book, the accident was caused by workers following procedures "deviating so drastically from approved procedures" as to be "incredibly absurd."

But, while Takagi, the industry and the government agree on how the criticality accident occurred, that is where their consensus ends.

Two of the workers involved in the accident have died of their injuries, a third has left hospital. As Takagi's book illustrates, however, perhaps the greatest failing of the industry and government has not been a failure to train and supervise workers, but rather an inability to conduct the nuclear power business with the critical and objective eye necessary to protect the lives and livelihoods of Japanese workers and residents.

Takagi is no stranger to the nuclear power industry. He received a doctorate in nuclear chemistry from Tokyo University, then spent five years working at Nippon Atomic Industry Group Ltd., now incorporated into Toshiba.

Later, after working at Tokyo University and Tokyo Metropolitan University, he founded the Citizens' Nuclear Information Center in 1975, where he was executive director from 1987 to 1998. In 1997, he received the Right Livelihood Award for his research on plutonium issues.

"Criticality Accident at Tokai-mura" is a readable and detailed account of the accident that led to almost 20 hours of criticality. It also exposes an entire industry riddled with technological and policy shortcomings.

Takagi begins with an explanation of criticality ("a condition in which a nuclear chain reaction becomes self-sustaining, as occurs in a nuclear reactor"), then guides the reader through the missteps that led to the accident.

Briefly stated, three workers making uranyl nitrate solution (used to fabricate nuclear fuel) overloaded a mixing tank with 16.6 kg of enriched uranium, although "anti-criticality regulations" required that no more than 2.4 kg be placed in the tank. The load went critical.

Though media have been content to place blame on the workers who cut corners to save time, Takagi argues that this misses the point. Workers at JCO Co. regularly used procedures that were "a deviation" from an unapproved, "modified version" of the official operation manual.

Workers went so far as to handle buckets of uranium solution with bare hands. The truth is, shortcuts were commonly accepted procedure. Takagi notes that with the nuclear power industry in decline, safety has become less affordable.

"The safety margin is greatly reduced by efforts to cut costs and to prolong the life span of Japan's aging reactors," he writes. As cutbacks become the norm, workers and supervisors inevitably resort to shortcuts.

At the time of the accident, however, workers used to handling low-enriched uranium were mixing high-enriched uranium. When mixing batches of low-enriched uranium, combining up to 16 kg of the uranium is allowable.

"It is probable that the workers thought they could do the same with the high-enriched uranium," writes Takagi.

"Their statement, 'We conducted the work after consulting with our boss,' shows that rather than being caused by a careless mistake, the accident was primarily the result of a lack of awareness about criticality throughout the whole company."

More to the point, explains Takagi, "Since there will always be a risk of criticality occurring at plants of this kind, facilities should be built according to a fail-safe, foolproof design, so that criticality can be avoided even in cases of equipment failure or human error."

Mixing tanks could have been constructed so that criticality would not occur under any circumstances. Takagi calls this "criticality-proof geometry." The true cause of the accident, he concludes, was that "the facility was not built to an appropriate design."

In other words, no fail-safe in a lethal process. "The ultimate mistake," writes Takagi, "was that this criticality-proof geometry was not applied to the precipitation tank." Lucky for JCO and the government that the laborers could be blamed. Especially guys no longer around to fight the rap.

With a flash of blue light, the reaction began at 10:35 a.m. Sept. 30. In a chilling chronology of events at the plant, in Tokai-mura and within the government, Takagi reveals that the accident caught everyone completely off guard. Monitoring of neutron radiation from the JCO plant did not begin until almost 4:30 in the afternoon. Government officials from the Nuclear Safety Commission did not arrive on the scene until 9:30 p.m.

With an informed and critical eye, Takagi analyzes the exposure of victims, the nuclear fuel cycle, the absence of safety measures in the industry, and the obvious fact that accidents do happen.

In the last chapter, "Critique of the Government's Final Report," he notes that a committee submitted an accident report to the Science and Technology Agency within less than three months. The report was completed in such an extreme rush, says Takagi, that it came out a month before the final estimates of radiation exposures were released.

Reports of this kind usually take a year or two to complete. Why the haste?

Takagi raises numerous questions about the conclusions found in the report, the proliferation of nuclear materials in Japan, shortcomings in industry security, and lessons not learned despite previous accidents.

"Aggressive promotion of nuclear energy is not backed up by real confidence in nuclear power on the part of promoters," Takagi concludes. "They lack both technical and political confidence. Thus when there is an accident, fears that harsh publicity will damage the image of nuclear energy are uppermost.

"The government, which is the biggest stakeholder in the nuclear power industry, becomes defensive, and is incapable of making a suitably rigorous response."

Takagi's book provides that rigor, in a most unsettling look behind the scenes of Japan's nuclear power industry.