Estimate for uranium facility goes from $600 million to $11.6 billion The cost of a proposed uranium processing facility for nuclear weapons in Oakridge, Tenn., has soared as high as $11.6 billion - 19 times the original estimate - even as critics accuse the Energy Department of overstating the need for spare bomb parts. Under a proposal unveiled in 2005, the manufacturing plant at the Y-12 National Security Complex would produce new uranium cores for the nation's stockpile of aging hydrogen bombs. But not long after the plan was disclosed, with an estimated cost of $600 million, the price tag began to climb. Now, the processing facility would be among the largest investments in the U.S. nuclear weapons infrastructure since the Manhattan Project, which developed the atomic bomb during World War II. The facility has drawn sharp criticism by the Project on Government Oversight, a Washington watchdog group, which advocates that the plan be scrapped. In a report issued Wednesday, the group cites a little-noticed report by the Army Corps of Engineers that made the $11.6-billion cost estimate and argued that the work could be done more cheaply at existing facilities. The Energy Department has not disputed the corps' estimate, although its own official price tag is $4.2 billion to $6.5 billion. A spokeswoman at Y-12 said the corps' estimate was the highest of three outside agency reviews of the project. The escalating cost reflects questions that have troubled the Energy Department's nuclear weapons complex since the end of the Cold War: How long will the Pentagon need a stockpile of nuclear weapons, and how can the massive industrial network needed to maintain the bombs be kept going at an affordable level? The Y-12 plant is the only U.S. facility that melts, casts and machines bomb-grade uranium. About 7,000 people work there. The facilities, massive brick structures the size of football fields, were built 70 years ago during World War II. The Energy Department says they are "genuinely dilapidated." Similar problems with aged facilities exist at the Pantex nuclear weapons facility in Texas, Los Alamos National Laboratory in New Mexico and the Savannah River Site in South Carolina, among other places. But Peter Stockton, lead author of the new report and a former Energy Department special investigator, disputes the need to replace so many uranium cores, known as secondaries. The Energy Department delayed its plans for a new plutonium facility in New Mexico after acknowledging that it had overestimated the number of plutonium triggers it would need for weapons, he noted. The Energy Department has failed to account for reductions in the size of the U.S. weapons stockpile and has underestimated the resiliency of the weapons parts, Stockton said. "They can't say how many secondaries we will need," he said. President Obama signed an agreement with Russia to cut each side's weapons stockpile to 1,550 by 2018, down from about 6,000 weapons about a decade ago. Stockton said the uranium work could be done more cheaply at existing facilities at Y-12 or at Pantex, where nuclear weapons are disassembled and repaired. The nation's three types of nuclear bombs are slowly undergoing life-extension programs, in which some parts are replaced and updated. Many of the weapons are more than 30 years old; they can no longer be tested under international treaties to determine conclusively that they will work. Some of the parts are virtual museum pieces, such as the B61 gravity bomb's fusing system, which still uses vacuum tubes. It is generally accepted that the bombs need to be refurbished. But all of the three design types already would be refurbished by the time the new uranium facility is fully operational in 2038, the date cited by the Army Corps of Engineers. The corps did not release its cost estimates, but the Government Accountability Office cited them this summer in a briefing addendum. The GAO, an arm of Congress, found that the Energy Department had made a number of errors in its cost estimates, including pricing a building design with a roof 13 feet too low to accommodate manufacturing equipment. That resulted in a $540-million increase in the project. After that, the GAO said it was reducing its confidence in the Energy Department's cost estimates. The GAO also found that the department had anticipated that Congress would provide much higher annual funding than was realistic. In addition, the GAO said, a longer construction schedule would drive up the price. In another report released Tuesday, the libertarian Cato Institute said the cost of the nation's nuclear force could be reduced by eliminating the historic reliance on delivering bombs by three different systems: submarines, bombers and land-based missiles. Cato defense analysts Benjamin Friedman and Christopher Preble say that submarine-launched missiles are more accurate than land-based missiles and can provide deterrence by themselves at a much lower cost. Friedman and Preble suggest that the Air Force not modernize its fleet of intercontinental ballistic missiles - part of a plan that, they say, could save $20 billion without jeopardizing the nation's deterrence against an attack.