In Japan, a public debate is raging over the safety of nuclear power. A series of cover-ups at several plants has sparked widespread outrage and threatens to derail expansion plans. Over the last three months, Tokyo Electric, the country's largest power company, and a few smaller rivals, have revealed breaches in safety standards that have shocked the nation. The violations date back as far as 1986, but have been hidden from the public until now.

Chihiro Kamisawa is an activist and researcher at the Citizen's Nuclear Information Center, which supports the use of alternative fuels. He says news of the scandal has triggered deep fear in a country that relies on nuclear energy for one third of its electricity needs. "I think that the public has lost confidenc," he says. "Even those who promote the use of nuclear power such as local governments are now shocked. Until now, the government has said that the nuclear plants are safe. But the latest incident reveals that the information [given by the power firms to the government] was not reliable."

The problems at many of the plants are defects, cracks in huge pipes that conduct water into the reactors. The power companies admit they hid or repaired the problems without the proper authorization from regulators, for fear that they would be shutdown if the defects were exposed.

There have been no reported radiation leaks and plants in other countries with similar cracks are allowed to continue operating while repairs are made. But experts fear strong earthquakes, to which Japan is vulnerable, could trigger a nuclear meltdown at one or more of the nation's 51 nuclear reactors.

Japanese people are highly sensitive to nuclear power catastrophes following the deadly accident three years ago in Tokaimura, a town 125 kilometers northeast of Tokyo. Employees improperly mixing nuclear fuel caused an explosion and a radiation leak. They exposed hundreds of residents, plant workers and emergency personnel to radiation and two plant workers died.

A newspaper poll taken last month shows that almost 90 percent of Japanese surveyed fear another nuclear power plant accident could occur. However, government officials insist that Japan's nuclear plants operate to the world's highest safety standards.

But Mr. Kamisawa and other critics worry that the regulatory system is lax because it allows companies a lot of leeway in monitoring themselves. They accuse government officials and nuclear plant operators of maintaining what they call "a culture of secrecy." "I think more information disclosure is needed to regain public trust as well as a better system for verifying the accuracy of plants' reports [to regulators]," he says.

Since the recent string of scandals, the government has begun making changes to win back public confidence. Regulators have ordered Tokyo Electric to shutdown operations at one of its nuclear reactors for one year as a punishment for falsifying safety records. That will cost the company an estimated $160 million and is likely to force it to buy energy from rivals. The president and chairman of the company have resigned.

Japan's Nuclear and Industrial Safety Agency plans to raise the maximum fine for misdeeds at power plants to about $250,000 dollars, a 100-fold increase over the present penalty. But whether these moves will be enough to stop serious accidents is unclear.

Hideki Nariai is the president of the Atomic Energy Society of Japan and a former professor of engineering who supports the use of nuclear energy. He is hopeful that the recent string of scandals will push Japan's nuclear power industry to become more accountable. He says nuclear energy is a cost efficient source of power for Japan, which is eager to wean itself from its heavy dependency on oil imports. "This is a wake-up call for the government to discuss setting up more detailed regulations. Over time, people may come to see the cracks as relatively minor problems," says Mr. Nariai. "However, the industry needs to be seriously aware that if there are damaged reactors, they can be harmful. The risk is not zero."

Still, the recent scandals could stall the world's most ambitious nuclear power program. Japan hopes to build 12 new reactors, more than any other nation. But some communities, which once welcomed nuclear plants because they meant more jobs and tax revenue, have set up stations in their town halls to monitor local radiation levels around the clock.

The cover-ups also appear to have thwarted Tokyo Electric's plan to use plutonium-enriched fuel at its reactors to make them more efficient. The initiative was seen as a critical step for Japan's nuclear industry because it would have recycled spent nuclear fuel, but public resistance has forced the project to a standstill.