The Energy Department has asserted that Bechtel Corp. underplayed safety risks from equipment it is installing at the nation's largest nuclear waste cleanup project, according to government records.
A federal engineering review team found in late July that Bechtel's safety evaluation of key equipment at the plant at the Hanford site in Washington state was incomplete and that "the risks are more serious" than Bechtel acknowledged when it sought approval to continue with construction, the documents say.
Senior scientists at the site said in emails obtained by The Times that Bechtel's designs for tanks and mixing equipment are flawed, representing such a massive risk that work should be stopped on that part of the construction project.
But Energy Department officials in Washington said they believed the problems were fixable and that they had authorized Bechtel to keep going for the time being. Bechtel officials said Friday that the matter was not a safety issue and that sticking to the current construction schedule would save money.
The Hanford project is the most important environmental cleanup program in the nation. It seeks to prevent 56 million gallons of radioactive sludge in underground tanks, some of which are leaking, from contaminating the nearby Columbia River.
Bechtel is under contract to build a $12.3-billion treatment plant at the former nuclear weapons center to convert the radioactive sludge to solid glass that could be more safely buried at a future high-level waste dump.
But the plant has been repeatedly stung by problems and delays, including a 2006 work stoppage when engineers determined it could not withstand a severe earthquake and that major retrofitting was required.
The latest problem hit this year, when engineers and scientists began to raise serious doubts about the safety of key tanks and mixing systems that would process the radioactive waste.
A government engineering team and a separate safety team evaluated the Bechtel design and determined that it did not meet safety requirements set by the Energy Department, and that Bechtel had failed to justify a request to continue construction.
In an Aug. 2 letter, Dale Knutson, the Energy Department's senior on-site manager, told Bechtel officials that their requests to continue construction had "insufficient information for demonstrating that the … vessels will meet their credited safety functions."
But Knutson authorized Bechtel to continue construction anyway, including welding shut tanks that use a controversial new mixing technology. Bechtel officials said that welding the tanks shut now would not prevent modifications later if additional testing showed they were necessary.
That authorization has fueled a new round of turmoil among engineers and scientists who had found Bechtel's design deficient, according to Richard McNulty, president of Local 788 of the American Federation of Government Employees, the union that represents the scientists and engineers.
"Clearly, the management system or safety culture is broken," said Donald H. Alexander, a chemist in the division of nuclear safety, in an Aug. 2 email to top Energy Department officials. "I find the behavior of management to be appalling."
Alexander said he was pressured to concur on technical issues but refused, and that top managers at the project had attempted to discredit his technical work. He is the second top scientist at the project to allege that management is running roughshod over scientists.
Walter Tamosaitis, the research and technology chief for Bechtel subcontractor URS Corp., was removed from his job last year and put in a basement office with nothing to do after raising similar safety concerns about the plant's design.
A series of tests with nonradioactive materials in the last year showed that the mixing system, designed to last 30 years without service, wore out in only a few months, according to McNulty and Energy Department documents.
If the mixers wear out or fail once highly radioactive material is flowing through the tanks, it would be theoretically impossible to fix the problem and could paralyze the project, the scientists say.
The tanks use pulse jet mixers, which engineers describe as giant turkey basters, to keep the sludge stirred, preventing plutonium from concentrating at the bottom and starting a chain reaction or producing explosive hydrogen gas. The pulse jet mixers have never been used in the United States and failed in the recent tests to prevent material from building up at the bottom of tanks.
After consulting with his membership, McNulty sought a stop-work order from Knutson, asserting that the decision to proceed presented an imminent safety hazard. The order was blocked and McNulty filed a grievance. The documents were sent to the Defense Nuclear Facilities Safety Board last week.
"The design of the tanks is flawed," said Tom Carpenter, executive director of the nuclear watchdog group Hanford Challenge, which provided the Energy Department documents to The Times. "The tests showed it and the safety engineers showed it. The decision to let Bechtel continue transfers the economic risk to the taxpayers. It amounts to a decision to approve a defective design."
Energy Department spokesman Jen Stutsman defended the decision, saying the tanks will not be installed until additional testing demonstrates whether the mixing system will work.
"We will not allow the vessels to be installed until the results from large-scale testing have shown that the vessel designs will safely and effectively handle the waste at the site," she said. "The Department of Energy is continuing to closely oversee the design, construction and testing of the Waste Treatment Plant to ensure that it will operate safely and effectively."