The reactivity of a nuclear reactor is the most important safety and operating parameter. Due to short reactor period, the Light Water Reactor(LWR) designs require the compensations of rapid unfavorable reactivity inc...The reactivity of a nuclear reactor is the most important safety and operating parameter. Due to short reactor period, the Light Water Reactor(LWR) designs require the compensations of rapid unfavorable reactivity increases. The increase in fuel or moderator temperature leads to compensate the reactivity jumps as inherent safety characteristics. The safe and reliable reactor operation requires the accurate assessment of these reactivity changes. This paper highlights the improvements in the methodology to determine the feedback reactivity changes in IAEA MTR benchmark. This method incorporates the reactivity effects of fuel temperature in moderator regions and vice versa. For this purpose, a detailed 3D model of the IAEA 10 MW MTR benchmark reactor is developed employing OpenMC computer code. OpenMC is a probabilistic computer code for neutronic calculations. This work uses temperature-dependent JEFF 3.2 cross-sectional library. The model is validated against the reference results of eigenvalues for control rods(inserted and in fully withdrawn position), control rod reactivity worth, averaged thermal flux in the central flux trap, and power fraction for each fuel element at beginning of life. The validated model is applied to simulate the feedback reactivity coefficients against the conventional reference results. In order to improve the methodology, the effect of the moderator temperature and void on fuel is incorporated to obtain a more realistic value of the fuel temperature coefficient.Similarly, the moderator temperature coefficient and void coefficient are improved by incorporating the coupling effects of fuel temperature on moderator. This methodology can be applied to improve the LWR designs.展开更多
We report inelastic interactions of protons at the center of mass energy s1/2 = 900 Ge V, by using different event generators to study the forward-backward(FB) correlation in summed transverse momentum and multiplicit...We report inelastic interactions of protons at the center of mass energy s1/2 = 900 Ge V, by using different event generators to study the forward-backward(FB) correlation in summed transverse momentum and multiplicity of produced charged particles. The transverse momentum, p T ≥ 100 Me V, and pseudorapidity, | η |< 2.5, have been employed for both the correlations. The simulation results are compared with the ATLAS experimental data, obtained with the same values of | η | and p T at s1/2 = 900 Ge V. We also measure the jet and jet-like structure as a function of azimuthal distributions in the events relative to the highest transverse momentum particle. Three overlapping regions of pseudorapidity, | η |< 1.0, | η |< 2.0, and | η |< 2.5 are used with transverse momentum, p T > 500 Me V. For FB correlations, EPOS, and Sybill2.3 c results are in a good agreement with the data as compared to the other models.Similarly, for the azimuthal distribution, EPOS-LHC, DPMJETIII, and Sibyll2.3 c show good agreement with the data for full η region. In general, EPOS provides a better description of the data for both the quantities studied in this paper.展开更多
Non-Newtonian fluids have variable viscosity in response to shear rate,and the presence of polymers and nanoparticles further modifies their flow characteristics.In this paper,the effects of polymers and nanoparticles...Non-Newtonian fluids have variable viscosity in response to shear rate,and the presence of polymers and nanoparticles further modifies their flow characteristics.In this paper,the effects of polymers and nanoparticles on mass and heat transfer control,drag reduction,boundary layer flow development in a polymeric finitely extensible nonlinear elastic-Peterlin(FENE-P)fluid,and the significance of nanoscience in modern day life are discussed.We examine the behavior of polymer additives by utilizing a dispersion model in conjunction with the polymeric FENE-P model.Our work includes a comparison with Cortell's earlier work,which only looked at the behavior of polymer’s inclusion into the base fluid.This research investigates numerically how the inclusion of polymers and nanoparticles into the base fluid reduces drag while increasing heat and mass transfer.The observed variations in skin friction,reduced Nusselt,and Sherwood numbers indicate an intriguing correlation between the rates of heat and mass transport and surface drag.More precisely,as the heat and mass transfer efficiency improve,the surface encounters less resistance,which is commonly referred to as drag.In summary,the research highlights the capability of polymers and nanoparticles to effectively modify fluid dynamics,minimize drag,and enhance mass and heat transfer inside the flow region.展开更多
文摘The reactivity of a nuclear reactor is the most important safety and operating parameter. Due to short reactor period, the Light Water Reactor(LWR) designs require the compensations of rapid unfavorable reactivity increases. The increase in fuel or moderator temperature leads to compensate the reactivity jumps as inherent safety characteristics. The safe and reliable reactor operation requires the accurate assessment of these reactivity changes. This paper highlights the improvements in the methodology to determine the feedback reactivity changes in IAEA MTR benchmark. This method incorporates the reactivity effects of fuel temperature in moderator regions and vice versa. For this purpose, a detailed 3D model of the IAEA 10 MW MTR benchmark reactor is developed employing OpenMC computer code. OpenMC is a probabilistic computer code for neutronic calculations. This work uses temperature-dependent JEFF 3.2 cross-sectional library. The model is validated against the reference results of eigenvalues for control rods(inserted and in fully withdrawn position), control rod reactivity worth, averaged thermal flux in the central flux trap, and power fraction for each fuel element at beginning of life. The validated model is applied to simulate the feedback reactivity coefficients against the conventional reference results. In order to improve the methodology, the effect of the moderator temperature and void on fuel is incorporated to obtain a more realistic value of the fuel temperature coefficient.Similarly, the moderator temperature coefficient and void coefficient are improved by incorporating the coupling effects of fuel temperature on moderator. This methodology can be applied to improve the LWR designs.
基金Supported by the Higher Education Commission(HEC) of Pakistan by the Grant No.20-3379/NRPU/R&D/HEC/2014
文摘We report inelastic interactions of protons at the center of mass energy s1/2 = 900 Ge V, by using different event generators to study the forward-backward(FB) correlation in summed transverse momentum and multiplicity of produced charged particles. The transverse momentum, p T ≥ 100 Me V, and pseudorapidity, | η |< 2.5, have been employed for both the correlations. The simulation results are compared with the ATLAS experimental data, obtained with the same values of | η | and p T at s1/2 = 900 Ge V. We also measure the jet and jet-like structure as a function of azimuthal distributions in the events relative to the highest transverse momentum particle. Three overlapping regions of pseudorapidity, | η |< 1.0, | η |< 2.0, and | η |< 2.5 are used with transverse momentum, p T > 500 Me V. For FB correlations, EPOS, and Sybill2.3 c results are in a good agreement with the data as compared to the other models.Similarly, for the azimuthal distribution, EPOS-LHC, DPMJETIII, and Sibyll2.3 c show good agreement with the data for full η region. In general, EPOS provides a better description of the data for both the quantities studied in this paper.
文摘Non-Newtonian fluids have variable viscosity in response to shear rate,and the presence of polymers and nanoparticles further modifies their flow characteristics.In this paper,the effects of polymers and nanoparticles on mass and heat transfer control,drag reduction,boundary layer flow development in a polymeric finitely extensible nonlinear elastic-Peterlin(FENE-P)fluid,and the significance of nanoscience in modern day life are discussed.We examine the behavior of polymer additives by utilizing a dispersion model in conjunction with the polymeric FENE-P model.Our work includes a comparison with Cortell's earlier work,which only looked at the behavior of polymer’s inclusion into the base fluid.This research investigates numerically how the inclusion of polymers and nanoparticles into the base fluid reduces drag while increasing heat and mass transfer.The observed variations in skin friction,reduced Nusselt,and Sherwood numbers indicate an intriguing correlation between the rates of heat and mass transport and surface drag.More precisely,as the heat and mass transfer efficiency improve,the surface encounters less resistance,which is commonly referred to as drag.In summary,the research highlights the capability of polymers and nanoparticles to effectively modify fluid dynamics,minimize drag,and enhance mass and heat transfer inside the flow region.
