Calculation and analysis of thermal–hydraulics fluctuations in pressurized water reactors. (February 2015)

• Record Type: Journal Article
• Authors: Malmir, Hessam; Vosoughi, Naser
• Is Part Of: Annals of nuclear energy. Volume 76(2015:Feb.)
• Page Start: 75
• Page End: 84
• Publication Date: 2015-02
• Subjects: Thermal–hydraulics -- Noise analysis -- PWR -- Single heated channel -- Feedback transfer function; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2014.09.041
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Single-phase thermal–hydraulics noise equations are originally derived in the frequency domain. The fluctuations of all the coolant parameters are calculated, without any simplifying assumptions. The radial distribution of the temperature fluctuations in the fuel, gap and cladding are taken into account. The closed-loop calculations are performed by means of the point kinetics noise theory. Both the space- and frequency-dependence of the thermal–hydraulics fluctuations are analyzed. Abstract: Analysis of thermal–hydraulics fluctuations in pressurized water reactors (e.g., local and global temperature or density fluctuations, as well as primary and charging pumps fluctuations) has various applications in calculation or measurement of the core dynamical parameters (temperature or density reactivity coefficients) in addition to thermal–hydraulics surveillance and diagnostics. In this paper, the thermal–hydraulics fluctuations in PWRs are investigated. At first, the single-phase thermal–hydraulics noise equations (in the frequency domain) are originally derived, without any simplifying assumptions. The fluctuations of all the coolant parameters, as well as the radial distribution of the temperature fluctuations in the fuel, gap and cladding are taken into account. Then, the derived governing equations are discretized using the finite volume method (FVM). Based on the discretized equations and the proposed algorithm of solving, a single heated channel noise calculation code (SHC-Noise) is developed, by which the steady-state and fluctuating parameters of PWR fuel assemblies can be calculated. The noise sources include the inlet coolant temperature and velocity fluctuations, in addition to the power density noises. The developed SHC-Noise code is benchmarked in different cases and scenarios. Furthermore, to show the effects of the power feedbacks, the closed-loop calculations are performed by means of the point kinetics noise theory. Both the space- and frequency-dependence of the temperature fluctuations are analyzed in this work.