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The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
Utility Working Conference and Vendor Technology Expo
August 8–11, 2021
Marco Island, FL|JW Marriott Marco Island
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Nuclear Science and Engineering
Fusion Science and Technology
Bumpy roads lead to beautiful places
Per Nuclear News tradition, this month’s issue is dedicated to highlighting our nuclear technology supply chain. U.S. nuclear suppliers have certainly seen their share of challenges in the last decade or so. The widely anticipated “Nuclear Renaissance” of the early 2000s gave way to Fukushima, then a wavelet of plant closures that ANS President Steve Nesbit addresses in his column on page 15 of the August 2021 issue of Nuclear News.
However, the nuclear narrative has taken on a more positive tone of late. Significant federal investments in advanced nuclear energy systems, coupled with a broader recognition of the need to decarbonize, has stoked excitement for a new generation of U.S. technology on the verge of scaled commercial deployment by the end of the decade. Hopefully, in the words of Washington Nationals manager Davey Martinez, whose team went from a 19–32 record to World Series champs in 2019, “Bumpy roads lead to beautiful places.”
Alexander R. Clark, John Mattingly, Jeffrey A. Favorite
Nuclear Science and Engineering | Volume 194 | Number 4 | April 2020 | Pages 308-333
Technical Paper | dx.doi.org/10.1080/00295639.2019.1698267
Articles are hosted by Taylor and Francis Online.
This paper presents the first application of model calibration to neutron multiplicity counting (NMC) experiments for cross-section optimization that is informed by adjoint-based sensitivity analysis (SA) and first-order uncertainty quantification (UQ). We summarize previous work on SA applied to NMC and describe notable modifications and additions. We give the procedure for first-order UQ and Bayesian-inference-based parameter estimation (PE). We then discuss model calibration applied to NMC of a 4.5-kg sphere of weapons-grade, alpha-phase plutonium metal (the BeRP ball) with the nPod neutron multiplicity counter. For the BeRP ball in bare and polyethylene-reflected configurations, we discuss the sensitivity of the first- and second-moment detector responses (i.e., first and second moments of the NMC distribution, respectively) to the cross sections. We describe the sources of uncertainty in the measured and simulated responses. Specifically, uncertainty in the measured responses is due to both random and systematic sources. Uncertainty in the simulated responses is due to the cross-section covariances. We describe in detail the adjustment to the cross sections and cross-section covariances due to the optimization. Due to the contribution of systematic uncertainties to the measured response uncertainties, the adjustment to the cross sections is similar in trend but larger in magnitude compared to that recommended by previous work. We compare the measured responses to responses simulated with nominal and optimized cross sections, demonstrating that the best-estimate cross sections produce simulations of NMC experiments that are more accurate with reduced uncertainty.