TOKYO, Oct. 1 —   An uncontrolled nuclear reaction was contained at a Japanese uranium processing plant on Friday, authorities said, one day after leaking radioactive gas seriously injured three workers and possibly contaminated 34 others. Officials allowed people living near the plant to venture outside and resume their daily routines.
 
MASARU HASHIMOTO, governor of Ibaraki Prefecture, said he had received confirmation that the reaction had been brought under control at 6:15 a.m. local time. The company that runs the plant acknowledged fault. The accident was the result of a “clear violation” of in-house safety rules, Makoto Morita, a spokesman for the company JCO, told The Associated Press Friday.
 
Radiation levels outside the plant had returned to normal by Friday morning and experts said that they did not believe there was a serious threat to local residents. Still, officials described the accident as the most serious ever at a nuclear facility in Japan.
 
An order for more than 310,000 residents within a six-mile radius of the plant to stay indoors was lifted in the afternoon. A380-yard radius around the plant was still declared off-limits.
 
THOUSANDS AFFECTED
Those affected by escaping radiation included local residents, plant workers and firefighters. Officials told nearby residents that any clothes worn during evening rain showers in the area should be washed and that locally grown vegetables should not be harvested.

The incident occurred Thursday morning at a privately owned plant at Tokaimura in Ibaraki Prefecture, about 90 miles northeast of Tokyo. The facility, which refines uranium so it can be used to fuel nuclear reactors, is located in Tokaimura, a town of 33,000 people, which is home to 15 nuclear-related facilities.
 
The sick included 14 workers, five local residents and two people working on a nearby golf course.  Government officials said the accident spewed a gas containing alpha, beta and gamma radiation into the atmosphere, forcing the evacuation of 150 neighbors of the plant.