Company officials were quick to report that there was no apparent release of radiation in the incident; however, there was a substantial loss of reactor coolant levels, forcing the plant to immediately shut down. Not the first such scram at Mihama in recent years, the fatal steam pipe rupture was, nonetheless, the worst accident at a Japanese nuclear facility since the 1999 explosion at the Tokaimura uranium reprocessing plant killed two workers and resulted in radiation leaks to surrounding environs.

In short order, it became known that the carbon-steel pipe at Mihama had corroded from the inside, losing integrity as the thickness of its walls diminished from about 10 millimeters to between 0.6 mm and 1.4 mm at the place of rupture. Also revealed was the fact that Kansai Electric had never performed safety inspections on that section of pipe in the 28 years of Mihama's operations.

The utility almost immediately announced that it would shut down all 11 of its nuclear stations for inspection. One sad fact emerging from the situation was that Kansai Electric had previously scheduled a detailed inspection for Mihama to start the week after the accident occurred. Internal documents from the company showed that officials were planning an extended outage related to the tests, perhaps in anticipation that there would need to be pipe replacements or repairs.

Six other nuclear utilities were ordered by the Nuclear and Industrial Safety Agency to review their inspection records and conduct tests for pipe corrosion. Most vulnerable to similar problems are Japan's 23 pressurized-water reactors, and the Kyodo News service uncovered government and industry reports that pipes from at least 17 of these facilities had been replaced in recent years or were scheduled for replacement because of suspected internal corrosion.

The initial flurry of news reports about Mihama has slowed considerably, but several significant developments have occurred in the past few weeks:

• On August 25, a fifth Mihama worker died. The 30-year-old utility subcontractor had undergone extensive skin grafting at a nearby university medical center, but his injuries proved fatal;
• Citing possible criminal negligence by utility officials, local police have conducted a search of Kansai Electric offices in the Fukui Prefecture, seizing inspection records and the section of pipe that was the cause of the accident;
• While rejecting calls for his resignation, Kansai Electric Power president Yosaku Fuji issued a statement of contrition and took responsibility for lax inspections at Mihama. Fuji also accepted the sanction of having his salary reduced by half for three months "as a symbol of moral responsibility" for the accident;
• Not directly related to Mihama, but troubling from an overall utility industry perspective, the operators of the Shinchi coal-fired power facility in Sohma City disclosed a very similar steam pipe rupture at their plant on August 15. No injuries were reported, but initial tests indicated that the thickness of wall of the carbon-steel pipe had diminished from 10.3 mm to just 1.4 mm. As at Mihama, engineers pointed to cavitation and flow-accelerated corrosion, but they expressed concern that the Shinchi power plant had been in operation for only nine years.

The Mihama accident occurs within a context of diminishing public confidence in nuclear power and electric utilities among Japanese citizens. The 1999 explosion at the Tokaimura was a crystallizing event for anti-nuclear activists, leading to formation of a number of new non-governmental organizations (NGOs) that question the nation’s reliance on nuclear power generation.

Possibly more influential for the general public was last year's scandal in which Tokyo Electric Power -- the nation’s preeminent electric utility -- admitted that it had falsified records at its nuclear facilities to cover up some fairly substantial safety problems. As a result, nearly all nuclear stations in the country were taken out of service last summer, including 17 operated by TEPCO. Even more of a black eye for the utility, its chief executive officer and the head of its nuclear operations were forced to resign in disgrace.

"Japanese people's confidence in nuclear energy policy has been lowering because of nuclear accidents and scandals since the 1990s," said Hiromi Kikuchi, an independent journalist, who is currently writing a book about Japan’s nuclear policies.

Kikuchi, a former energy reporter for the Asahi Shimbun newspaper, is also a personal friend of mine; we first met in 2001 when she was a public policy fellow at the University of Maryland. The Mihama accident, she told me, "spurs the distrust in the country's nuclear power industry and influences the country’s energy plans."

Her assessment of public opinion was backed up by Tokyo Electric Power, which responded to my e-mail queries following the Mihama accident with this statement: "TEPCO lost public trust completely by the recent series of incidents. The entire company is pulling together in an effort to restore public trust and is taking preventative steps, such as disclosing whatever incident occurred at the power plants."

TEPCO's acts of contrition were mirrored in language found in its annual company environmental reports. As recently as 2002, the utility stressed its reliance on nuclear as the most sensible policy for combating global warming and maintaining reliable service. The growing anti-nuclear public sentiment was acknowledged, but the company said it planned to pursue education efforts to convince the population that its fears and concerns were unwarranted. In the most recent environment report, TECO has changed its tune. The latest report includes a special section titled, "We will consider nuclear with you," reported Kikuchi.

"I think TEPCO's attitude has considerably changed since two years ago," she added. "However, other power companies' stances look unchanged, judging from their environmental reports."

Indeed, the Federation of Electric Power Companies of Japan (FEPC) continues to promote the Basic Energy Plan, adopted by the Japanese Parliamentary Cabinet last year, which endorses continued reliance on nuclear energy and expansion of fuel reprocessing and recycling. "Nuclear power generation, including the nuclear fuel cycle, will be promoted as a key power source, based on the premise that safety will be guaranteed," states the Plan.

The official position increasingly runs counter to public opinion research, noted Kikuchi. As early as February 1999 (six months before the Tokaimura explosion), a survey conducted by the Office of the Prime Minister revealed a deep split in public opinion. More people opposed nuclear expansion than supported it, "with 27.2 percent choosing a moratorium on nuclear expansion, and 21.5 percent opposed to any use of nuclear power. Only 4.2 percent said they wanted aggressive increase in nuclear power, but 38.5 percent said they favored a careful increase."

A more recent polling indicates further erosion in support, she added; "10.6 percent approved the increase of nuclear power plants, 45.6 percent hoped they would not increase, and 34.9 percent said they hoped for fewer plants." Also, "83.1 percent said they had concerns about nuclear power safety."

Japanese utilities currently plan construction of 17 new reactors by 2016, but Kikuchi doubts those plans -- which have been revised downward repeatedly -- will come to fruition, in part because the rules of a liberalized power market will discourage new capital investment in nuclear energy. Another front will be industry efforts to extend the lifespan of existing reactors, from their licensed 30-40 year spans to as long as 60 years.

The biggest battles could come over fuel reprocessing and radioactive waste disposal, predicted Tetsunari Iida, executive director of the Institute for Sustainable Policies in Tokyo. The nuclear utilities have invested heavily in a reprocessing station at Rokkasho, officially for recycling but largely because the have no other viable solutions for waste disposal. The FEPC utilities estimate the project cost will be $18.8 trillion yen (about $170 billion USD).

"In order to avoid its huge economic risk for the utilities, they had been strongly negotiating through their political influence that its cost could be recovered through a new tax on electricity,” Iida told me. "There has been rising political opposition against it. The Mihama accident would affect this discussion."

The Bottom Line: The closure of Kansai Electric's nuclear facilities, and possible curtailments at others, comes at a difficult time for Japanese power utilities. This has been a record-breaking summer of heat and power use for Japan. In July, aggregate peak demand for the 10 largest utilities was 174 million KWh, up 16.2 percent from 2003, but slightly less than a peak of 178 million KWh still anticipated for this summer, according to FEPC. Lighting, air-conditioning and industrial demand are all up substantially.

At the same time that hydroelectric generation had fallen by 22.7 percent compared to last year, nuclear utilities were pumping up their output. In July, nuclear capacity utilization was 77.7 percent, up half-again from last year's 53.1 percent utilization rate. This was prior to the Mihama accident, though, and the loss of nuclear capacity has eaten into the nation’s projected 14 percent reserve margin.

Replacement of the lost generation will be costly for Kansai Electric, which relies on nuclear for 65 percent of energy generation, but no figures are yet available. The company begged its neighboring utilities for supplies and has restarted several old and inefficient fossil-fuel stations -- at a time when oil and natural gas prices have skyrocketed.

Last year, Tokyo Electric spent about $2.8 billion for repairs and replacement fuel when its 17 reactors were off line. Summer 2003 presented a "severe supply-demand situation," admitted TEPCO officials. "We put our customers to considerable inconvenience by asking them to conserve electricity."

In Japan's wavering support for nuclear power, the future of policy may be determined by how the public balances such additional costs and the inconvenience of supply curtailments against growing concerns over safety.

Arthur O'Donnell is Energy Central's Editorial Director -- Newsletters.
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