Sandia LabNews

Blast mitgation foam contains chem-bio dispersal cloud

Labs-developed blast-suppression foam would be put to use in future chem, bio, or dirty bomb scare

If US authorities ever found in our midst a ticking terrorist bomb laced with chemical, biological, or radiological materials, the on-scene response team likely would reach for a foam developed at Sandia years ago.

The foam, studied and tested extensively at Sandia and the Nevada Test Site in the 1980s to support federal emergency response operations, is similar to common firefighting foams but is specially designed to trap radioactive particles thrown into it by the detonation of a so-called "dirty bomb."

The foam also suppresses an explosive blast by absorbing the force of the shock wave within its chemically engineered bubble structure.

A bonus feature of the Sandia foam — one that might come in handy in today’s terror-conscious world — is its ability to envelop chemical or biological aerosols in its aqueous bubble structure, thereby thwarting a terrorist’s plan to sicken or kill many people or render an area unusable by dispersing contaminants over a wide area, says Bill Rhodes (5817), manager of the Sandia team evaluating the foam for such applications.

Typically a tent or bag would be placed over a suspect bomb and then filled with the foam. Then, if the device detonated, observers would hear a thump and see the tent collapse into a wet mass, rather than hearing a loud bang and seeing the flash, smoke, and pressure wave that would accompany an unmitigated bomb.

The foam is available to first-responders from ChemGuard, Inc. (Mansfield, Texas) under the brand name Aqueous Foam Concentrate-380 (AFC-380).

Few agencies at the local and state level are aware of it, however, says Paul Johnson (5817).

That means it might not be within the reach of the on-scene teams that would need to deal with a suspect device in a timely manner, before it goes off.

It might be days, certainly hours, before federal responders could get to the scene. And if they don’t have the foam concentrate, tents, and spraying equipment with them, the chances of foaming the device in a timely fashion are diminishingly small, he says.

But much can be done at Sandia to put the foam into the hands of first-responders all over the country, says Bill.

The foam-generation equipment needs to be optimized to the needs of first-responders — local firefighters, mostly, on limited budgets and with little time for training. Thus, the gear needs to be inexpensive and easy to use.

And lightweight, adds Bill. Firefighters might need to pump the foam up to a high elevation to fill a large tent, climb a ladder with a tank strapped on, or fill a third-story room from outside. Extremely lightweight pumps, hoses, and containers are needed.

"It doesn’t sound like tough science, but you need lightweight materials and reliable designs," he says.

Also, while the foam’s blast-suppression and rad-trapping effects are well characterized, Sandia has yet to study adequately its ability to capture chemical and biological particles dispersed in a blast. Variations in foam structure, densities, and neutralizing additives might be considered for response to a broader range of suppression needs.

"Although we know it’s effective, its ability to trap these aerosols is not fully tested," he says. "We’d like to quantify these capabilities."

Moreover, a wider variety of terrorist bomb-scare scenarios needs to be studied, and a suite of tents, cones, bags, and other coverings created and evaluated for each situation.

Currently, a limited number of configurations are available — essentially a few sizes of tents and cones for different-sized explosive charges, and a fillable bag for hanging over the sides of buildings to keep particles from escaping through windows.

DOE and the FBI have sponsored evaluation of the foam in recent years, although the project currently is idle.

Sandia team members include Fred Harper (5817), Marvin Larsen (5854), Paul, and Bill. Others who have made major contributions to the foam’s development include primary developer Pete Rand (ret.), Ed Graeber (ret.), Kermit Goettsche (ret.), and Billy Marshall (2552)