RICHLAND - A radiation leak just days after the discovery that an employee had falsified records halted some cleanup efforts at Hanford nuclear reservation so workers could take a "safety break."
The safety review Wednesday affected about 1,000 employees and subcontractors of Washington Closure Hanford, which is cleaning up contaminated areas near former reactor sites along the Columbia River.
Workers returned to their jobs Thursday, Washington Closure spokesman Todd Nelson said.
On Tuesday, radioactive tritium contamination was found to have spread outside a tent where radiological work was being performed near the closed B and C reactors on the nuclear reservation's north side.
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The levels of contamination were too low to require reporting and were not believed to have affected worker health, Nelson said.
It is too early to say whether the U.S. Department of Energy will fine the company, Nelson said Thursday.
"They're going to have to say," he said. "We're taking aggressive action to get work going and make sure it doesn't happen again."
DOE spokeswoman Colleen French did not immediately return a call for comment Thursday.
Washington Closure and Energy Department officials were working on a decontamination plan for the tritium, an isotope of hydrogen that spreads easily because it binds with oxygen.
The spread of tritium and the problem with landfill compacting records discovered last week "make us concerned about the conduct of operations," said Nick Ceto, Hanford project manager for the Environmental Protection Agency, which regulates the cleanup project.
EPA will discuss its concerns with DOE and Washington Closure officials, he said.
Tritium, which is used in hydrogen bombs, was produced at Hanford reactors from 1949 to 1952 until its production was moved elsewhere.
The leak occurred after workers tapped a small canister Friday that was among debris retrieved from a burial ground that held waste from Hanford's B Reactor and nearby buildings. They discovered tritium gas inside.
Work inside the radiological tent was halted Monday after tritium contamination was found. Additional tests found the contamination had been tracked outside the tent.
Washington Closure has about 700 workers, and its subcontractors have about 300. The company is in charge of cleaning 761 waste sites and burial grounds contaminated by radioactive and chemical wastes.
The radiation contamination comes on the heels of the discovery last Friday that a subcontractor employee had falsified records at a low-level radioactive waste landfill.
S.M. Stoller, which operates the landfill, said that one employee had been recording compaction test data even though he had not performed the test at times over the past year.
The test ensures that compacting of waste is adequate so that contents won't settle and possibly affect the integrity of an engineered cap that will cover the landfill.
The Energy Department's primary concern has been working with Washington Closure to ensure employees are safe and the environment is protected, French told the Tri-City Herald on Wednesday.
The agency is looking at the circumstances surrounding the tritium contamination, she said.
"While this is tough work, worker safety is the department's priority and any action or process breakdown that calls that into question is simply unacceptable," she said. "That's what we'll be looking at as we continue to gather facts and examine the causes."