CLEVELAND (AP) — Nuclear plant workers in Ohio violated several safety regulations and had to avoid a 6-foot-deep hole in the floor when increased radiation levels forced them to flee their work area in April, federal regulatory officials said in a preliminary report.

Four workers at the Perry Nuclear Power plant on the shores of Lake Erie were exposed to higher radiation levels than normal on April 22 while they were attempting to remove a monitor that measures nuclear reactions. Plant officials failed to appropriately evaluate the radiological hazards associated with the removal process, which is a violation of regulations, the U.S. Nuclear Regulatory Commission said in an inspection report released Thursday.

In light of the violations, the NRC is considering monitoring the plant more closely, which could include costly inspections.

The highest radiation exposure to any of the workers was 98 millirems, which is equivalent to two or three chest X-rays, the plant has said. The NRC's limit for radiation exposure in a year is 5,000 millirems.

The NRC said the plant failed to provide sufficient instructions to the workers, who were contractors brought in to help the plant shut down to refuel. The workers also failed to follow procedure, according to the report.

The commission also cited industrial safety hazards in the room where the incident occurred, including an unbarricaded 6-foot-deep hole in the grating on the floor. Inspectors also found a rope, a wire and a cord on the grating that workers could have tripped over.

The contractors were working in a containment building underneath the reactor at the time, the plant said. The plant refueling continued on schedule after the incident. There was no radiation threat to the public.

The nuclear plant, owned by Akron-based FirstEnergy Corp., is about 35 miles northeast of Cleveland and began operating in 1987.

The monitor, which had been sitting in the reactor core for about 10 months, was highly radioactive, said NRC spokeswoman Viktoria Mitlyng.

"Our top priority is the safe operation of our nuclear units," said FirstEnergy spokesman Todd Schneider. "We are taking this event seriously and have conducted a thorough investigation to ensure this type of situation is not repeated."

Schneider said new safety procedures are being put in place and the plant in increasing oversight of contract workers. He also said the hole in the floor was in a restricted area and has been fixed.

The plant has 10 days to respond to the report.

The plant had numerous safety problems several years ago, which led the NRC to monitor its safety operations every three months in 2005, when the plant was forced to shut down briefly because of problems with pumps that circulate coolant through the reactor's core.

In March 2010, a small fire broke out in a water pump's lubrication system at the plant. The fire burned for several hours, and two members of the plant's fire brigade were taken to a hospital for heat stress.


Information from: The Plain Dealer,