The technical problems with the W76 were also partially disclosed in the report from the GAO, which said the Energy Department had failed to "effectively manage cost, schedule and technical risks" not only on the W76 program but on another refurbishment effort for a warhead known as the B61.
In the case of the B61, the Energy Department boasted that it had completed the job ahead of schedule and under cost, even though it sharply reduced the number of bombs that it rebuilt and curtailed the scope of the work on each bomb, the GAO said. The cost of refurbishing each bomb doubled, the office said.
LaVera said all issues with fogbank had been resolved. The only remaining W76 issue involves potential minor defects in its arming, fusing and firing system, the safety controls that prepare a nuclear weapon for detonation.
He said the existing design of the arming system had been certified, though the department was continuing to examine the issue.
"It is inaccurate to say that we are unable to ship the weapons because there is an issue or problem," LaVera said.
Not everybody agrees that the fogbank problem raises broad concerns about a loss of expertise.
Since the late 1990s, the nation has embarked on a program to invest billions of dollars in scientific research to keep the old weapons viable.
The issue is highly sensitive because many arms control advocates worry that such a loss could become a rationale for a resumption of nuclear testing.
The Energy Department's scientific program to support the stockpile "has done very well so far. Most people would say it has been a terrific success," said Sydney Drell, a nuclear weapons expert at Stanford University.
The department plans to deliver the first batch of W76s in late fall, LaVera said.
That would put it about two years behind schedule, a delay that has caused logistical problems for the Navy, the GAO said.
It is not yet clear how long it will take for the department to refurbish all 2,000 warheads in its current plan, but the process of gradually taking warheads out of service, refurbishing them and returning them to service could take an additional 10 years.
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ralph.vartabedian@ latimes.com
