Nuclear forensicsNuclear forensics to the aid of nuclear detectives
Fans of the popular TV series “CSI” know that the forensics experts who investigate crime scenes are looking for answers to three key questions: “Who did it; how did they do it; and can we stop them from doing it again?” The field of nuclear forensics has similar goals and uses similar techniques — but with even higher stakes. “In nuclear forensics, we want to know first, is someone able to put together the parts to make a nuclear weapon and set it off?” says one researcher. “And second, if one is set off, can we find out who did it, how they did it and are they going to do it again? Like traditional forensics, we’re looking for nuclear signatures, just like fingerprints; we’re looking for the technological and material clues and evidence to tell us what somebody had done to make this unfortunate thing happen.”
Fans of the popular TV series “CSI” know that the forensics experts who investigate crime scenes are looking for answers to three key questions: “Who did it; how did they do it; and can we stop them from doing it again?”
The field of nuclear forensics, an important element of Lawrence Livermore National Laboratory’s (LLNL) national security mission, has similar goals and uses similar techniques — but with even higher stakes.
“In nuclear forensics, we want to know first, is someone able to put together the parts to make a nuclear weapon and set it off?” said LLNL nuclear chemist Dawn Shaughnessy, who leads the experimental and nuclear radiochemistry group in the Physical and Life Sciences Directorate. “And second, if one is set off, can we find out who did it, how they did it and are they going to do it again?
“Like traditional forensics, we’re looking for nuclear signatures, just like fingerprints; we’re looking for the technological and material clues and evidence to tell us what somebody had done to make this unfortunate thing happen.”
If a nuclear explosive was detonated on U.S. soil, nuclear forensics specialists would be dispatched to examine the rubble from the explosion for traces of fissile material, fission products and activation products — nearby debris or structural components of the bomb made radioactive by neutron activation. The more information the experts could glean by characterizing these materials, the better able they would be to determine the weapon’s design and origin.
An LLNL release reports that the National Ignition Facility (NIF) is playing a growing role in LLNL’s nuclear forensics work by providing radioactive samples from nuclear fusion experiments for analysis. “We’re looking for information about the nuclear decay of certain elements - and not just the actinides,” Shaughnessy said. “We also need to know about the materials used to build a device by looking for isotopes and nuclear decay signatures to piece together what was physically there when an event occurred.
“For some isotopes that would be very useful signatures for us; we don’t have any data on their nuclear reaction pathways,” she said. “For example, if a nuclear device was set off in a garage, the garage would have steel in it that would become radioactive, and that might help us figure out something related to the resultant neutron spectrum.
