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Investigating the Propagation Noise in PWRs via Coupled Neutronic and Thermal-Hydraulic Noise Calculations
, Ph.D. Dissertation Sharif University of Technology ; Vosoughi, Naser (Supervisor)
Abstract
In operating nuclear reactor core, fluctuations (deviations from normal operating conditions) are usually produced and propagated. These fluctuations can be due to control rod vibrations, inlet coolant temperature fluctuations, inlet coolant velocity fluctuations and so on. The induced neutron noise can be detected by in-core neutron detectors. Noise source identifications (such as the type, location and propagating velocity) as well as the calculation of the dynamical parameters (such as moderator temperature coefficient in PWRs and Decay Ratio in BWRs) are of the main applications of the neutron noise analysis in power reactors.
Investigating the propagation noise in PWRs (specifically...
Investigating the propagation noise in PWRs (specifically...
Propagation noise calculations in VVER-type reactor core
, Article Progress in Nuclear Energy ; Volume 78 , January , 2015 , Pages 10-18 ; 01491970 (ISSN) ; Vosoughi, N ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Neutron noise induced by propagating disturbances in VVER-type reactor core is addressed in this paper. The spatial discretization of the governing equations is based on the box-scheme finite difference method for triangular-z geometry. Using the derived equations, a 3-D 2-group neutron noise simulator (called TRIDYN-3) is developed for hexagonal-structured reactor core, by which the discrete form of both the forward and adjoint reactor dynamic transfer functions (in the frequency domain) can be calculated. In addition, both types of noise sources, namely point-like and traveling perturbations, can be modeled by TRIDYN-3. The results are then benchmarked in different cases. Considering the...
Investigating the propagation noise in PWRs via closed-loop neutron-kinetic/thermal-hydraulic noise calculations
, Article Annals of Nuclear Energy ; Volume 80 , 2015 , Pages 101-113 ; 03064549 (ISSN) ; Vosoughi, N ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Neutron noise induced by propagating thermal-hydraulic disturbances (propagation noise for short) in pressurized water reactors is investigated in this paper. A closed-loop neutron-kinetic/thermal-hydraulic noise simulator (named NOISIM) has been developed, with the capability of modeling the propagation noise in both Western-type and VVER-type pressurized water reactors. The neutron-kinetic/thermal-hydraulic noise equations are on the basis of the first-order perturbation theory. The spatial discretization among the neutron-kinetic noise equations is based on the box-scheme finite difference method (BSFDM) for rectangular-z, triangular-z and hexagonal-z geometries. Furthermore, the finite...
Investigating the Propagation of Thermal-hydraulic Noise in PWRs in Two phases
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor)
Abstract
The core behaviour of a nuclear reactor might be fluctuated (deviations from the normal operating conditions) in operating conditions due to various reasons. Control rod vibrations and the alterations of coolant temperature and velocity could be the main reasons for the fluctuations. These fluctuations lead to neutronic flux noise and subsequently power noise. The main objective of the current thesis was to study the thermal-hydraulic noise of the PWRs in two-phase with the emphasis on VVER-1000, which is similar to the Bushehr-1 nuclear reactor. By considering the possibility of existing two-phase flow (maximum allowable quality is about 14%) in hot channel of the PWRs, thermal-hydraulic...
Density peaks clustering based on density backbone and fuzzy neighborhood
, Article Pattern Recognition ; Volume 107 , November , 2020 ; Moradi, P ; Beigy, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Density peaks clustering (DPC) is as an efficient clustering algorithm due for using a non-iterative process. However, DPC and most of its improvements suffer from the following shortcomings: (1) highly sensitive to its cutoff distance parameter, (2) ignoring the local structure of data in computing local densities, (3) using a crisp kernel to calculate local densities, and (4) suffering from the cause of chain reaction. To address these issues, in this paper a new method called DPC-DBFN is proposed. The proposed method uses a fuzzy kernel for improving separability of clusters and reducing the impact of outliers. DPC-DBFN uses a density-based kNN graph for labeling backbones. This strategy...