1. Fast Rossi-alpha Measurements of Plutonium using Organic Scintillators
- Author
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Hua, M. Y., Bravo, C. A., MacDonald, A. T., Hutchinson, J. D., McKenzie, G. E., Grove, T. J., Goda, J. M., McSpaden, A. T., Clarke, S. D., and Pozzi, S. A.
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Physics - Instrumentation and Detectors - Abstract
In this work, Rossi-alpha measurements were simultaneously performed with a $^3$He-based detection system and an organic scintillator-based detection system. The assembly is 15 kg of plutonium (93 wt$\%$ $^{239}$Pu) reflected by copper and moderated by lead. The goal of Rossi-alpha measurements is to estimate the prompt neutron decay constant, alpha. Simulations estimate $k_\text{eff}$ = 0.624 and $\alpha$ = 52.3 $\pm$ 2.5 ns for the measured assembly. The organic scintillator system estimated $\alpha$ = 47.4 $\pm$ 2.0 ns, having a 9.37$\%$ error (though the 1.09 standard deviation confidence intervals overlapped). The $^3$He system estimated $\alpha$ = 37 $\mu$s. The known slowing down time of the $^3$He system is 35-40 $\mu$s, which means the slowing down time dominates and obscures the prompt neutron decay constant. Subsequently, the organic scintillator system should be used for assemblies with alpha much less than 35 $\mu$s., Comment: PHYSOR 2020: Transition to a Scalable Nuclear Future Cambridge, United Kingdom, March 29th-April 2nd, 2020
- Published
- 2020
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