Comparison ?of ?fast ?and ?thermal ?neutron ?multiplicity ?counters ?for? assaying ?special ?nuclear ?materials??

Year
2010
Author(s)
Martyn T. Swinhoe - Los Alamos National Laboratory
J. B. Marlow - Los Alamos National Laboratory
Les Nakae - Lawrence Livermore National Laboratory
H.O. Menlove - Los Alamos National Laboratory
P.L. Kerr - Los Alamos National Laboratory
R. Wurtz - Lawrence Livermore National Laboratory
D. Henzlova - Los Alamos National Laboratory
S. A. Sheets - Lawrence Livermore National Laboratory
Abstract
Neutron coincidence counting is a widely adopted nondestructive assay (NDA) technique used in nuclear safeguards to measure the mass of plutonium present in impure plutonium samples and spent fuel. We are performing a comparison of two different techniques for coincidence counting: one that measures thermal neutrons using the He-3 based Epithermal Neutron Multiplicity Counter (ENMC) and a second that employs a LLNL- designed array of liquid scintillators to measure fast neutrons (LSMC). In light of current limitations on the availability of 3He this Next Generation Safeguards Initiative (NGSI) funded project is intended to evaluate the capabilities and limitations of the LSMC through a comprehensive comparison with the proven but He-3 intensive ENMC, using materials that are representative of a real safeguards environment. In the past, liquid scintillators have been explored in the safeguards context with little demonstrable and deployable success. The goal of the study is to determine whether this type of liquid scintillator-based system may be practical for broader use in safeguards applications.