Believe it or not, Wal-Mart and Los Alamos National Laboratory have something in common.

They both have to get a firm handle on their inventory for the holiday season rush.

Of course, national security won't be threatened if Wal-Mart is off by a few pairs of socks this Christmas.

There would be significant alarm, on the other hand, if Los Alamos came up short on its big annual nuclear inventory in December, said Victoria Longmire, a nuclear materials safeguards specialist at the lab.

"When Wal-Mart does inventory, they need to know the label is correct and how many of each item they have," Longmire said. "When we do inventory, we need to know that what's inside our containers is actually what is supposed to be there, and we have to be very accurate."

Managing nuclear inventory in the past was an exercise in outdated technology. Lab personnel had to drag hundreds of containers - ranging in size from a coffee mug to a refrigerator - out of storage and into a separate facility where they were weighed, tested and scanned, Longmire said.

This year some parts of the lab are using a new system designed by Longmire. It's an inventory cart that can roll up to the casks of nuclear material, weigh them, check labels and see inside without opening them up, she said.

"It's not rocket science," Longmire said. "Basically what we tried to do is take off-the-shelf Wal-Mart technologies and our more sophisticated scanning and measurement equipment and put them together."

The cart can shave weeks - and costs - off an inventory compared with the older method. It also helps track when materials are removed for scientific tests, said Nancy Ambrosiano, a spokeswoman for the lab.

"A lot of the time people assume we have all these warehouses full of nuclear materials and they never move," Ambrosiano said. "The thing is, this is a scientific facility. People have to be able to check materials in and out without throwing the inventory off."

When an item is removed and returned, the cart can quickly scan and make sure the materials are still present in the correct amounts, Ambrosiano said.

It also prints out inventory reports and keeps a constant record of what's there, as opposed to handwritten reports used in the past, Longmire said.

Materials in storage are labeled with radio frequency tags and bar codes. If there is a question about something being lost, workers can do a very quick inventory by zipping through and just checking the tags, Longmire said.

"Of course the cart isn't our only security," Longmire said. "It's part of an integrated network of cameras, sensors and smart portals that someone has to go through if they want to remove any of the materials for research."

Los Alamos used the cart for the first time this October, when the lab transferred several items from its TA-18 nuclear storage facility - used since the 1940s - to a newer storage area at the Nevada Test Site, Ambrosiano said.

"We were able to move that material basically on schedule, despite the lab shutdown earlier this year, because of this inventory cart," Ambrosiano said.

Work on the cart cost about $800,000 for the prototype, but subsequent units will cost more in the range of $100,000 each, Longmire said.

The project was sponsored by the Department of Energy Office of Security and Safety Performance Assurance and the Office of Field Security for the National Nuclear Security Administration.

Longmire plans to continue tweaking and adding improvements to the scanning and sensing abilities of the cart in coming months. She hopes it will next be used at the lab's TA-55 facility, which is the other big nuclear repository at Los Alamos, she said