95 research outputs found
On integrating Monte Carlo calculations in and around near-critical configurations I. Methodology
No full textMonte Carlo with variance reduction (VR) is employed to calculate radiation-induced responses in a variety of fixed source problems. In eigenvalue problems, Monte Carlo is used without VR (apart from implicit capture) for in-core integral responses (keff, reactivity coefficients, burn-up effects, etc.). More differential in- or ex-core responses are either treated in the same way thus limiting the range of solvable problems, or by decoupling. We evaluate an all-Monte Carlo approach developed to calculate differential in- or ex-core responses without decoupling. The ex-core problems involve responses in a GEN III PWR. The in-core problems study the neutron flux and 96Zr(n,γ) rate at the surface of a control rod in the VERA Benchmark. Comparison is made with an empirical approach involving analog Monte Carlo in-core with VR ex-core. The paper consists of two parts: part I tests the methodology; part II compares with PWR GEN II and III ex-core decoupled results
On integrating Monte Carlo calculations in and around near-critical configurations – II. Pressurized water reactors
No full textInternational audienceThis article is the second part of a paper that evaluates a recent approach that has been developed to calculate differential in- and ex-fissile configuration responses employing Monte Carlo with variance reduction. The first part focused more on the methodological aspects and established the circumstances under which a single eigenvalue calculation could be made as efficient as possible, in particular as compared with an empirical approach (involving again a single eigenvalue calculation). Both ex- and in-core test problems were considered. Instead this second part looks at two ex-core PWR sample problems and compares the single eigenvalue approach with an all Monte Carlo decoupled approach with different approximations at the point of decoupling, thus highlighting the sensitivity of the decoupled result to the decoupling approximation
Writing intelligentsia against the project of turning the Siberian rivers in the 60-80s of the twentieth century
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Thermal stability of the hydrogen-bonded water network in the hydration shell of islet amyloid polypeptide
No full textCalculating the effective delayed neutron fraction in the Molten Salt Fast Reactor: analytical, deterministic and Monte Carlo approaches
No full textThis paper deals with the calculation of the effective delayed neutron fraction (betaeff) in circulating-fuel nuclear reactors. The Molten Salt Fast Reactor is adopted as test case for the comparison of the analytical, deterministic and Monte Carlo methods presented. The Monte Carlo code SERPENT-2 has been extended to allow for delayed neutron precursors drift, according to the fuel velocity field. The forward and adjoint eigenvalue multi-group diffusion problems are implemented and solved adopting the multi-physics toolkit OpenFOAM, by taking into account the convective and turbulent diffusive terms in the precursors balance. These two approaches show good agreement in the whole range of the MSFR operating conditions. An analytical formula for the circulating-to-static conditions betaeff correction factor is also derived under simple hypotheses, which explicitly takes into account the spatial dependence of the neutron importance. Its accuracy is assessed against Monte Carlo and deterministic results. The effects of in-core recirculation vortex and turbulent diffusion are finally analysed and discussed
Effect of Temperature on the Structural and Hydrational Properties of Human Islet Amyloid Polypeptide in Water
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