Dr. Jonathan Mueller, the RADIANS postdoctoral research fellow, gave an invited seminar to the Purdue School of Nuclear Engineering on February 10, 2016. His seminar focused on his analysis of the measurements of subcritical assemblies of highly multiplying special nuclear material (SNM) he conducted during the measurement campaign at the Nevada Test Site (NTS) Device Assembly Facility (DAF) in Summer 2015. Dr. Mueller described how his measurements and analyses enable novel approaches to verification of nuclear disarmament. Purdue is a partner institution in the Consortium for Nonproliferation Enabling Capabilities (CNEC).
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Dr. Jonathan Mueller, the RADIANS postdoctoral research fellow, gave an invited seminar to the North Carolina A&T State University Department of Physics on January 20, 2016. He discussed his work on novel techniques to measure the neutron multiplication of special nuclear material (SNM) using fast organic scintillators, and he focused on his recent measurements of SNM at the Nevada Test Site (NTS) Device Assembly Facility (DAF) in Summer 2015. NCA&T is a partner institution in the Consortium for Nonproliferation Enabling Capabilities (CNEC), and they will collaborate with NC State University (NCSU) to conduct experiments at DAF in Summer 2016.
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CNEC students and faculty conducted neutron and gamma measurements of Category I weapons-grade plutonium and highly enriched uranium. The data collected will be used by the Consortium to advance research in detection, identification, and characterization of special nuclear material
(SNM). It will also be used to develop new Consortium courses on the analysis of SNM.
The CNEC university participants included:
The experiments were made possible by Los Alamos National Laboratory
staff: Jesson Hutchinson, Donnette Lewis, Kenny Valdez, Leonard Trujillo, Mark Smith-Nelson, Mark Mitchell, Clemente Garcia, and Jeff Favorite.
RADIANS team lead Prof. John Mattingly received a best paper award from the American Nuclear Society (ANS) Nuclear Criticality Safety Division (NCSD) at the summer 2012 ANS meeting.
Mattingly’s paper “An Evaluation of Monte Carlo Simulations of Neutron Multiplicity Measurements of Plutonium Metal,” co-authored by University of Michigan Nuclear Engineering Ph.D. student Eric Miller, demonstrated that the published value of the mean neutron multiplicity (nu-bar) of induced fission in 239Pu is significantly lower than it’s actual value. Mattingly and Miller made this discovery by comparing Monte Carlo simulations of subcritical neutron multiplicity counting experiments to measurements Mattingly performed at the Nevada Test Site in 2009. Their findings are of potentially substantial impact – they imply that current models of fission chain-reactions in plutonium significantly underpredict neutron multiplication.
Eric Miller graduated with his Ph.D. later in 2012; he now works for the Johns Hopkins University Applied Physics Laboratory.
Mattingly and Miller’s original work has formed the basis for continuing RADIANS research on sensitivity analysis, uncertainty quantification, and parameter estimation conducted by Ph.D. students Sean O’Brien and Alex Clark and postdoctoral scholar Todd Evans. We have developed new methods for nuclear data evaluation using subcritical neutron multiplicity counting experiments, and we are very close to demonstrating, quantitatively and irrefutably, that the published value of nu-bar for 239Pu needs to be reevaluated.
Prof. John Mattingly, the RADIANS team lead, received an Early Career Award from the Department of Homeland Security (DHS) Domestic Nuclear Detection Office (DNDO) to develop new methods to analyze interdicted, pre-detonation nuclear materials and post-detonation nuclear explosion debris (fallout). DNDO awarded Prof. Mattingly $300,000 to conduct this research, and NCSU contributed $75,000 in matching funds.
Prof. Mattingly’s research is supported by NCSU graduate students Garrett Dean and Gabe Lucero and postdoctoral scholar Dr. Tony Nettleton. Their work will enable the forensic analysis of interdicted, irradiated nuclear material and nuclear fallout.