Analytical Challenges in Detecting Undeclared Nuclear Activities

Fingerprints and forensic analysis have played critical roles in criminal law enforcement

for more than 100 years. In the relatively new field of "nuclear forensics" – which

focuses on determining the nature and origin of illicit nuclear materials – methods are

required to characterize material properties with high sensitivity and accuracy. Just as

with human fingerprinting, measurements of radio- and stable isotope abundances, trace

element impurities, molecular form, “age” and physical parameters such as density and

shape or grain size can be assembled to create a nuclear fingerprint or signature of a

specific nuclear facility. In environmental samples these nuclear signatures provide a

powerful approach to identify and categorize materials indicative of undeclared nuclear

activities. Ensuring the accuracy of nuclear fingerprinting requires the development and

application of sophisticated mass spectrometers, electron microscopes and radiation

detectors capable of characterizing materials across samples of great diversity and size;

environmental samples range over 13 orders of magnitude in mass, with U and Pucontents and Pu/U ratios varying by more than a factor of 108. The analytical challenges

posed by environmental sampling for nuclear safeguards are substantial and are best

addressed through expanded international cooperation in instrumentation and

standardization.