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Neutron Multiplicity Counting: Credible Regions for Reconstruction Parameters

Jérôme M. Verbeke

Nuclear Science and Engineering / Volume 182 / Number 4 / April 2016 / Pages 481-501

Technical Paper /

First Online Publication:March 9, 2016
Updated:April 1, 2016

From nuclear materials accountability to homeland security, the need for improved nuclear material detection, assay, and authentication has grown over the past decades. Starting in the 1940s, neutron multiplicity counting techniques have enabled quantitative evaluation of masses and multiplications of fissile materials. In this paper, we propose a new method to compute uncertainties on these parameters using a model-based sequential Bayesian processor, resulting in credible regions in the fissile material mass and multiplication space. These uncertainties will enable us to evaluate quantitatively proposed improvements to the theoretical fission chain model. In addition, because the processor can calculate uncertainties in real time, it is a useful tool in applications such as portal monitoring: monitoring can stop as soon as a preset confidence of nonthreat is reached.