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J. Nucl. Eng., Volume 3, Issue 3 (September 2022) – 4 articles

Cover Story (view full-size image): Journal of Nuclear Engineering (ISSN 2673-4362), an international open access journal, publishes peer-reviewed papers containing original research, ideas, and developments related to the science and application of nuclear and radiation processes.
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10 pages, 2037 KiB  
Opinion
Nature, Energy and Society—A Scientific Study of the Options Facing Civilisation Today
by Wade Allison
J. Nucl. Eng. 2022, 3(3), 233-242; https://doi.org/10.3390/jne3030013 - 19 Aug 2022
Cited by 1 | Viewed by 3203
Abstract
The nations of the world plan to stop burning carbon fuels but have not fixed on any replacement. For social and economic confidence, they need to share a proper picture of the options. The science is simply explained and not in doubt, though [...] Read more.
The nations of the world plan to stop burning carbon fuels but have not fixed on any replacement. For social and economic confidence, they need to share a proper picture of the options. The science is simply explained and not in doubt, though widely misunderstood. Energy sources belong to three distinct groups: renewable, chemical and nuclear. Since human life began, it has adopted each of these in turn. In the past, initial disruptions have been more than off-set by the rise in human values that followed. Now, to complete the final step, we confront those who would look backward to the age of renewables. Instead, the world should look forward to a heavy dependence on nuclear energy with a confidence informed by natural science and openly shared in society. Full article
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11 pages, 5921 KiB  
Article
Neutronics Analyses of the Radiation Field at the Accelerator-Based Neutron Source of Nagoya University for the BNCT Study
by Takeo Nishitani, Sachiko Yoshihashi, Yuuki Tanagami, Kazuki Tsuchida, Shogo Honda, Atsushi Yamazaki, Kenichi Watanabe, Yoshiaki Kiyanagi and Akira Uritani
J. Nucl. Eng. 2022, 3(3), 222-232; https://doi.org/10.3390/jne3030012 - 13 Jul 2022
Cited by 1 | Viewed by 2134
Abstract
The Nagoya University Accelerator-driven Neutron Source (NUANS) is an accelerator-based neutron source by 7Li(p,n)7Be reaction with a 2.8 MeV proton beam up to 15 mA. The fast neutrons are moderated and shaped to beam with a Beam Shaping Assembly (BSA). [...] Read more.
The Nagoya University Accelerator-driven Neutron Source (NUANS) is an accelerator-based neutron source by 7Li(p,n)7Be reaction with a 2.8 MeV proton beam up to 15 mA. The fast neutrons are moderated and shaped to beam with a Beam Shaping Assembly (BSA). NUANS is aiming at the basic study of the Boron Neutron Capture Therapy (BNCT) such as an in vitro cell-based irradiation experiment using a water phantom. Moreover, the BSA is developed as a prototype of one for human treatment. We have evaluated the radiation field of NUANS by a Monte Carlo code PHITS. It is confirmed that the radiation characteristics at the BNCT outlet meet the requirement of IAEA TECDOC-1223. Additionally, the radiation field in the water phantom located just in front of the BSA outlet is calculated. In the in vitro irradiation experiment, the boron dose of 30 Gy-eq, which is the dose to kill tumor cells, is expected for 20 min of irradiation at the beam current of 15 mA. Full article
(This article belongs to the Special Issue Recent Advances in Applied Nuclear and Radiation Physics)
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31 pages, 403 KiB  
Article
Illustrative Application of the nth-Order Comprehensive Adjoint Sensitivity Analysis Methodology for Nonlinear Systems to the Nordheim–Fuchs Reactor Dynamics/Safety Model
by Dan Gabriel Cacuci
J. Nucl. Eng. 2022, 3(3), 191-221; https://doi.org/10.3390/jne3030011 - 30 Jun 2022
Viewed by 1332
Abstract
The application of the recently developed “nth-order comprehensive sensitivity analysis methodology for nonlinear systems” (abbreviated as “nth-CASAM-N”) has been previously illustrated on paradigm nonlinear space-dependent problems. To complement these illustrative applications, this work illustrates the application of the nth-CASAM-N to a paradigm nonlinear [...] Read more.
The application of the recently developed “nth-order comprehensive sensitivity analysis methodology for nonlinear systems” (abbreviated as “nth-CASAM-N”) has been previously illustrated on paradigm nonlinear space-dependent problems. To complement these illustrative applications, this work illustrates the application of the nth-CASAM-N to a paradigm nonlinear time-dependent model chosen from the field of reactor dynamics/safety, namely the well-known Nordheim–Fuchs model. This phenomenological model describes a short-time self-limiting power transient in a nuclear reactor system having a negative temperature coefficient in which a large amount of reactivity is suddenly inserted, either intentionally or by accident. This model is sufficiently complex to demonstrate all the important features of applying the nth-CASAM-N methodology yet admits exact closed-form solutions for the energy released in the transient, which is the most important system response. All of the expressions of the first- and second-level adjoint functions and, subsequently, the first- and second-order sensitivities of the released energy to the model’s parameters are obtained analytically in closed form. The principles underlying the application of the 3rd-CASAM-N methodology for the computation of the third-order sensitivities are demonstrated for both mixed and unmixed second-order sensitivities. For the Nordheim–Fuchs model, a single adjoint computation suffices to obtain the six 1st-order sensitivities, while two adjoint computations suffice to obtain all of the 36 second-order sensitivities (of which 21 are distinct). This illustrative example demonstrates that the number of (large-scale) adjoint computations increases at most linearly within the nth-CASAM-N methodology, as opposed to the exponential increase in the parameter-dimensional space which occurs when applying conventional statistical and/or finite difference schemes to compute higher-order sensitivities. For very large and complex models, the nth-CASAM-N is the only practical methodology for computing response sensitivities comprehensively and accurately, overcoming the curse of dimensionality in sensitivity analysis of nonlinear systems. Full article
28 pages, 452 KiB  
Article
The nth-Order Comprehensive Adjoint Sensitivity Analysis Methodology for Nonlinear Systems (nth-CASAM-N): Mathematical Framework
by Dan Gabriel Cacuci
J. Nucl. Eng. 2022, 3(3), 163-190; https://doi.org/10.3390/jne3030010 - 21 Jun 2022
Cited by 7 | Viewed by 1464
Abstract
This work presents the nth-Order Comprehensive Adjoint Sensitivity Analysis Methodology for Nonlinear Systems (nth-CASAM-N), which enables the most efficient computation of exactly determined expressions of arbitrarily high-order sensitivities of generic nonlinear system responses with respect to model parameters, uncertain [...] Read more.
This work presents the nth-Order Comprehensive Adjoint Sensitivity Analysis Methodology for Nonlinear Systems (nth-CASAM-N), which enables the most efficient computation of exactly determined expressions of arbitrarily high-order sensitivities of generic nonlinear system responses with respect to model parameters, uncertain boundaries, and internal interfaces in the model’s phase space. The mathematical framework underlying the nth-CASAM-N is proven to be correct by using mathematical induction. The nth-CASAM-N is formulated in linearly increasing higher-dimensional Hilbert spaces—as opposed to exponentially increasing parameter-dimensional spaces—thus overcoming the curse of dimensionality in sensitivity analysis of nonlinear systems. Full article
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