Analysis of flow induced density wave oscillations in the CANDU supercritical water reactor

Abstract

In this paper, a 1-D thermal-hydraulic model, THRUST, is developed to simulate and analyze the CANDU supercritical water reactor (SCWR) from the thermodynamic point of view without considering the effect of neutronic coupling. THRUST, where a characteristic-based finite difference scheme is used, is validated against the available numerical results. The model is, then, used for the analysis of the CANDU SCWR with a primary focus to determine the conditions for potential density wave oscillations. Extensive numerical studies are performed to obtain the marginal stability boundary in the operating regime of the reactor. The effect of various parameters, such as, mass flow rate, operating pressure, axial heat flux profile, local pressure drop coefficient, and friction factor, on the stability thresholds of the reactor have been investigated.

Analysis of parallel channel instabilities in the CANDU supercritical water reactor

“…THRUST was validated for the in-phase model of DWOs in the previous work (Dutta et al, 2015). In order to evaluate the capability of THRUST in analyzing the out-of-phase mode of DWOs and MSB for parallel channels, the results obtained by THRUST are validated against the experimental data conducted by Xiong et al (2012) where the stability thresholds and marginal stability points (MSPs) were obtained for a two-parallel-channel system as shown in Fig.…”

“…Except for the works done by Xiong et al (2012), Xiong et al (2013), the rest of the works mentioned above (Chatoorgoon, 2001;Gómez et al, 2008;Jain and Rizwan-uddin, 2008;Ambrosini and Sharabi, 2008;Sharabi et al, 2008;Ambrosini, 2009;Zhao et al, 2011;T'Joen et al, 2011;Ambrosini, 2011;Ampomah-Amoako and Ambrosini, 2013) were mainly confined to analyze the inphase mode of DWOs under supercritical conditions for flows in single channels. Dutta et al (2015) carried out a numerical investigation on DWOs in the CANDU SCWR using a 1-D nonlinear TH model, Thermal-Hydraulic solveR Undertaking Supercritical waTer (THRUST), which is also based on a single channel model. They also studied the effect of various parameters on the marginal stability boundary (MSB) including the effect of different axial power profiles, but neglected the effect of the radial power variation on the MSB.…”

Numerical analysis of parallel-channel density wave instabilities in a supercritical water reactor

“…Because of the several related research works on the supercritical fluids (SCFs) conducted in the recent past [1][2][3][4][5][6][7][8][9][10][11][12][13][14] in addition to the decades together related research experience [15][16][17][18][19][20] and based on those findings, it is reasonable to believe that the development of a SCWR is one of the viable options to implement the generation IV nuclear reactor in practice and make it operational in the near future, provided the remaining uncertainties associated with a new possible technology are addressed adequately. The TH stability and the related safety of the SCWR are one of the important identified areas which have received a considerable importance among the concerned scientific community.…”

“…The related research works, in spite of the varied nature of those, more or less agree that a SCWR, in its relevant operating conditions, might undergo DWOs, a dynamic instability, which gets originated purely due to the nonlinear interactions of the TH parameters and might get influenced with the neutronic parameters as well. The TH models, which have been used for the prediction of DWOs, can be based on linear perturbation and frequency-domain approaches [1-3, 5, 8, 21, 22], or based on nonlinear time-domain solution methodologies [5,[9][10][11][12][13][14]. Although the fact that the MSBs predicted from these two categories of models occasionally differed in quantitative agreements, the related studies with these models did predict the possibility of DWOs in an SCW system considering a single channel, subjected to the highest reactor power, as a representative of the complete reactor core.…”

Nuclear coupled thermal hydraulic analysis of fast transient depressurization in supercritical channels

“…The TH model, THRUST, which was earlier used to analyze the TH behavior of various supercritical pressure water systems (Dutta et al, 2015a(Dutta et al, , 2015b(Dutta et al, , 2015c is at present integrated with the neutron point kinetic (NPK) solver (Sanchez, 1989) using temperature and density reactivity feedback coefficients to account for the time-dependent reactor power. The model THRUST solves the nonlinearly coupled mass, momentum in axial direction and energy conservation equations along with the thermodynamic equation of state in the time domain using a characteristic-based, fully implicit finite difference method.…”