IN A MAJOR accomplishment for the Department of Energy's (DOE) Stockpile Stewardship Program, scientists at the nation's nuclear weapons laboratories announced in July that they had succeeded for the first time in modeling the explosion of a thermonuclear weapon in three dimensions. Soon after, the General Accounting Office (GAO) issued a report in mid-August strongly criticizing both the department and Lawrence Livermore National Laboratory for oversight and management failures of the controversial National Ignition Facility (NIF).
Stockpile Stewardship is a $4.5 billion per year program intended to safeguard the nation's nuclear weapons arsenal in the absence of nuclear tests. The program includes many elements, among them an advanced effort at the computer modeling of nuclear explosions, termed the Accelerated Strategic Computing Initiative. Also included is the over-budget and behind-schedule National Ignition Facility, intended to use lasers to recreate the pressures and temperatures present in a nuclear explosion. DOE has termed the NIF an "essential component" of the stewardship effort, but critics have strongly questioned its relevance to the central goals of the program.
Los Alamos National Laboratory reported in late July that nuclear scientists working under the Accelerated Strategic Computing Initiative had successfully modeled a thermonuclear secondary detonation in three dimensions during a 42-day simulation. The simulation, completed April 30, ran on Los Alamos' Blue Mountain supercomputer, the third-fastest in the world, with assistance from Sandia National Laboratory's Red supercomputer, currently the fastest in the world.
Last December, Livermore scientists utilized their lab's Blue Pacific supercomputer to model the behavior of a thermonuclear primary, the boosted plutonium fission bomb that provides the energy necessary to trigger a combined fission-fusion reaction in the secondary, which is responsible for most of the destructive yield of a thermonuclear weapon.
Three-dimensional modeling allows scientists to perform more realistic simulations than they could with the two-dimensional simulations previously feasible. Laboratory scientists expect to receive a new generation of more powerful supercomputers within the next five years, significantly shortening the required processing time and making successive analyses possible within a shorter time frame. Scientists require repeated analyses to effectively model the consequences of changes in the various components of a stockpiled weapon, such as ageing of the fissile material or chemical high explosive. More computing power will also facilitate higher resolution modeling.
Despite rather optimistic media coverage in the wake of the successful simulation, "virtual nuclear tests" remain a distant prospect. According to Los Alamos spokesman Jim Danneskiold, scientists "hope within a few years to be able to accurately simulate some of the physics involved in nuclear explosions."
GAO Criticizes NIFThe General Accounting Office issued a report August 17 that sharply criticizes DOE for "inadequate oversight" and Lawrence Livermore National Laboratory for "poor management" of the National Ignition Facility. Perhaps most damaging, officials associated with the program apparently told GAO that they knowingly submitted unrealistically low budget estimates to Congress in order to secure approval for the project, believing that "the value of NIF to the future of the Laboratory overshadowed potential cost concerns."
The National Ignition Facility has been plagued with a slew of problems since its inception. The most significant technical challenge has been an inability to construct optics that can withstand the lasers' anticipated intensity. Financially, the program, initially proposed at $400 million and funded by Congress at $1.1 billion in 1995, is now estimated by the Energy Department to cost about $3.3 billion, although GAO argues in its report that total costs could exceed $3.9 billion. (The latter figure includes NIF-related research that DOE chooses not to tally in the program's budget.) The GAO report also notes that the department expects completion of the necessary facilities, originally scheduled for 2002, to be delayed until 2008. And the report warns that project costs could grow even higher and completion could be delayed further, given unresolved technical issues.
DOE's fiscal year 2001 budget request includes more than $300 million for National Ignition Facility-related work, but Secretary of Energy Bill Richardson has indicated that the department will not seek additional appropriations to cover the NIF cost overruns; instead it will shift funds within the existing stockpile stewardship budget.
Given the potential for further dramatic cost overruns, Richardson's plan has fueled fears that the NIF could drain funding from other more central projects, hampering the stewardship effort. The GAO report recommends that funds not be reallocated to the NIF from the nuclear weapons program until DOE certifies that the selected cost and schedule plan "will not negatively affect the balance of the Stockpile Stewardship Program." The report also calls on Richardson to arrange for an independent review of remaining technical challenges that could "affect the project's cost and schedule risks."
In her July 28 response to the report, Deputy Administrator for Defense Programs Madelyn Creedon largely agreed with GAO's findings, but stated concern that the report "gives the impression" that DOE has "not taken appropriate action." According to the letter, the department is already meeting the review requirement with various independent analyses, most notably one from a task force chaired by John McTague, former science adviser to President Ronald Reagan.