Makio Tashiro, seated behind the counter of his clock shop, quietly told how an accident at the nearby nuclear power plant had revived his worst nightmare.

In the dream, Tashiro's portable gamma-ray sensor - a boxlike device he carries with him - starts beeping wildly. The city goes dark and the plant grinds to a halt, spewing deadly radiation into the air as the reactor core overheats and melts.Officials say the accident Feb. 9 at the plant six miles from the shop was not a meltdown. An emergency shutdown was ordered because abnormal radiation levels were detected in a reactor when radioactive water leaked from one cooling system to another after a steam generator tube cracked.

Tashiro, 39, has been assured only a small amount of radiation leaked into the atmosphere and poses no health risk. Still, he considers moving away from the plant near the white sand beaches of central Japan's western shore.

What is being called Japan's worst nuclear accident has raised new questions about the government's ambitious program to expand its atomic energy program.

The nation has been startled by the first accident to set off a reactor core's emergency cooling system, and critics noted it followed a mandatory annual safety check by only a few months.

Activists have said the tubes suspected of causing the accident are prone to wear and are the weak point in the design of 17 of Japan's 40 nuclear power plants.