Simulation and Experimental Validation of Electromagnetic Signatures for Monitoring of Nuclear Material Storage Containers

Research at the Pacifi c Northwest National Laboratory (PNNL)demonstrated that the low frequency electromagnetic (EM) responseof a sealed metallic container interrogated with an encirclingcoil is a strong function of its contents and can be used toform a distinct signature confi rming the presence of specifi c componentswithout revealing hidden geometry or classifi ed designinformation. Finite element simulations further investigated thisresponse for a variety of confi gurations of an encircling coil anda typical nuclear material storage container. Excellent agreementwas obtained between simulated and measured impedance signaturesfor electrically conducting spheres placed inside an AT-400Rnuclear material container. Simulations determined the effects ofexcitation frequency and of the geometry of the encircling coil,nuclear material container, and internal contents. It is possibleto use electromagnetic models to evaluate the application of theEM signature technique to proposed versions of nuclear weaponscontainers which can accommodate restrictions imposed by internationalarms control and treaty verifi cation legislation.