Active Detection of Shielded SNM With 60-keV Neutrons

• Published in: IEEE transactions on nuclear science Vol. 56; no. 3; pp. 1215 - 1217
• Main Authors: Hagmann, C.A., Dietrich, D.D., Hall, J.M., Kerr, P.L., Nakae, L.F., Newby, R.J., Rowland, M.S., Snyderman, N.J., Stoeffl, W.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arrays; Beams (radiation); Costs; Degradation; Design optimization; Detectors; Emission; Fissile materials; Inspection; Interrogation; neutron beams; neutron sources; Neutrons; Nuclear fuels; Particle beams; Plywood; Protons; Radiofrequency identification; Steel; Steels; Time measurement
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2009.2012859

Fissile materials, e.g., 235 U and 239 Pu, can be detected non-invasively by active neutron interrogation. A unique characteristic of fissile material exposed to neutrons is the prompt emission of high-energy (E > 1 MeV) fission neutrons. One promising mode of operation subjects the object to a beam of low-energy (E < 1 MeV) neutrons, generated by a proton beam impinging on a Li target. The emergence of high-energy secondary neutrons then clearly indicates the presence of fissile material. Our interrogation system comprises a low-dose 60-keV neutron generator (5 times 10 6 /s ), and a 1 m 2 array of scintillators for high-energy neutron detection. Preliminary experimental results demonstrate the detectability of small quantities (376 g) of 235 U shielded by steel (200 g/cm 2 ) or plywood (30 g/cm 2 ), with a typical measurement time of 1 min.