Nuclear Weapons Surveillance Program is vital ‘foundation for managing the aging stockpile’

Editor’s note: This is the first in a series of Lab News articles covering Sandia’s Nuclear Weapons Surveillance Program.

In testimony before the US Senate Committee on Armed Services Strategic Subcommittee last year, Sandia President Paul Robinson said the nuclear weapons surveillance program is the "foundation for managing the aging stockpile."

Those words clearly show the high level of responsibility carried by the 80 people in Sandia’s surveillance-related departments 2950, 2951, 2952, 2953, 2954, and 2955. They test and evaluate the safety and reliability of the nuclear stockpile and are the front line for finding potential problems and making recommendations for repairs and upgrades.

Weapons surveillance began in the US in the mid-1960s when weapons testing was done through underground explosions of nuclear devices. Such testing continued until the early 1990s.

"Since the cessation of ‘live’ nuclear weapons testing, our non-nuclear testing is one of the few ways we have to determine if the weapons will work when they are supposed to and not work when they are not supposed to," says Bill Norris, Level II Manager of Surveillance Group 2950. "We are vital to stockpile stewardship."

Weapons testing

Weapons in the stockpile range from anywhere between 15 to 40 years old, and the likelihood grows every year that parts might start to fail as the systems age. The faulty parts must be found and replaced or repaired.

Of course, says Bill, it is impossible to test all weapons in the stockpile, so the testing is done at random. Every year 11 weapons are randomly pulled for testing from each of the nine enduring stockpile systems in the country: B61-3/4/10, B61-7/11, W62, W76, W78, W80-0/1, B83, W87, and W88 — making for about 100 weapons tested annually. Bill says that this level of random testing will uncover most defects that might exist in weapons in the stockpile.

"If there is a defect in 10 percent of the weapons, there is a 90 percent probability that a weapon with that defect will be in the sample every two years," he says.

Eight of the 11 weapons systems are typically sent to Sandia’s Weapons Evaluation Test Laboratory (WETL) at the Pantex Plant near Amarillo where they receive more than 400 tests. This includes 80 principal tests where the weapons are first examined as a whole, followed by 320 supplemental tests where both other fuzing options are tested and some independent components are examined. Some of these tests are conducted at the coldest and hottest temperatures for which the system is designed to verify proper operation in those conditions.

Engineers in Albuquerque write procedures for Pantex and WETL technicians about how to dismantle the weapons, what measurements to take, and what observations to make. The technicians are also instructed in what to do with each part. In some cases, they totally destroy parts such as batteries and explosive components to see how they would have really operated.

WETL replacement

In addition, at least three weapons from each weapons system, roughly 40 a year, are flight-tested with the military. The weapons — minus their nuclear payloads — are deployed as bombs to be released from aircraft or in warheads loaded on cruise or ballistic missile systems. Because the missile systems are destroyed on landing, Sandia engineers have little or no actual parts to study to see what, if anything went wrong. At this point, a team does a "forensic investigation," using whatever evidence they have gained from telemetry or visual test observations.

The 40-year-old WETL facility where weapons are tested now houses about $90 million in equipment and is the only US facility that conducts systems-level, non-nuclear tests on atomic weapons and parts. It was constructed when some of the early weapons were first built, and the building has become inadequate. Thanks to congressional project approval three years ago and follow-on appropriations, that is about to be altered. By late 2004 the 18 Sandians at the Pantex site will be working in a new $22 million state-of-the-art facility that will replace the old building. The construction contract should be awarded in early February and the groundbreaking ceremony will occur shortly thereafter.

Gone too will be the old test equipment that was built when the weapons were constructed, replaced by $24 million in new "testers" being designed and built by engineers in Test Equipment Design Dept. 2955 in Albuquerque. This work should be complete by 2009.

Anomalies

If tests on a weapon system show an anomaly — a possible problem with a part that could jeopardize the system operation — with a Sandia-designed part, a Sandia system evaluation engineer (SEE) is notified. It is the SEE’s job to determine if the anomaly could affect the surety (safe use) or reliability of the weapon. If the SEE makes that determination, he/she opens a "significant finding investigation (SFI)." As chair of the investigation the SEE brings in technical people who understand the weapon to figure out the source of the failure.

The responsibility of the investigation team is to determine the cause and impact of the defect and to make recommendations for corrective actions. This information is eventually turned over to the design groups in Centers 2100 or 8200, which make the decision on whether repairs are needed and how to go about making those repairs.

Bill notes that making those repairs is becoming more and more difficult as the systems age. "Spare parts" for the older systems dating back to the 1960s simply don’t exist. Some old radars, for example, still use vacuum tubes. Replacement parts are less of a problem for the circa 1980 weapons because many extra parts were built and stored.

Better databases

One of the other problems surveillance teams run into is poor documentation of some of the older weapons systems.

"In the old days you could generally turn to the actual engineer who designed the part or someone with personal knowledge about the weapon design," Bill says. "Many of these people kept the designs and their basis in personal notebooks. And as long as the engineer was around, you could talk to him and look at the original notebook. Now many of the designers of the early weapons are retired and the team has to go back to scratch and recreate."

He adds that many designs and test information have been stored in boxes in the Manzano Mountains for many years.

One whole surveillance department, Dept. 2954, is devoted to building up a database of testing results of the weapons. Department members are digitizing the old information and developing ways to retrieve data — even down to a single component.

"All these advancements are moving the surveillance program toward a predictive capability that will allow us to replace components in our aging stockpile before they affect reliability," Bill says.