UPDATE: Workers return to damaged nuclear plant

Photo by Dennis Wilden

Photo by Dennis Wilden

FUKUSHIMA, Japan -- Japan ordered emergency workers to withdraw from its stricken nuclear complex Wednesday amid a surge in radiation, temporarily suspending efforts to cool the overheating reactors. Hours later, officials said they were preparing to send the team back in.

UPDATE: (11:00 A.M.) A white cloud of smoke or steam rising above Japan's Fukushima Daiichi nuclear plant on Wednesday may have been caused by a breach in the containment vessel in one of its reactors, government officials said.

Workers have been allowed to return to the plant.

Chief Cabinet Secretary Yukio Edano said a breach in the No. 3 reactor's containment vessel -- the steel and concrete shell that insulates radioactive material inside -- may have brought about the smoke..

It is unclear how much radioactive material may have been emitted, what kind of health threat that could pose or when the danger would end.

The nuclear crisis has triggered international alarm and partly overshadowed the human tragedy caused by Friday's 9.0-magnitude earthquake and the subsequent tsunami, a blast of black seawater that pulverized Japan's northeastern coastline. The quake was one of the strongest recorded in history.