A Linear Stability Analysis for Natural-Circulation Loops Under Supercritical Conditions

Jain, Rachna; Corradini, Michael L.

doi:10.13182/nt06-a3764

Cited by 40 publications

(6 citation statements)

References 6 publications

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“…Note how the slope of the second half of the power flow curve becomes steeper at increased subcooling. These trends are all consistent with the published numerical work on supercritical loops [30]- [32]. As the temperature approaches the pseudo-critical point (33.1°C), there is a strong drop in the driving force, resulting in a lower flow rate.…”

Section: Resultssupporting

confidence: 89%

“…As such the DR shows a maximum. Jain and Uddin [30] and Jain and Corradini [32] did not report this behavior, which could be because they only searched for the first transition by incrementing the power from a low value. This maximum behaviour was also found by Sharma et al [31] who studied a rectangular supercritical loop with water at 25 MPa.…”

Section: Linear Stabilitymentioning

confidence: 98%

“…[30]- [32]). These results were obtained using different codes which apply various techniques to study the stability (such as an eigenvalue analysis or transient simulations).…”

Section: Introductionmentioning

confidence: 99%

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Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

T’Joen

Rohde

2012

Nuclear Engineering and Design

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The HPLWR (High Performance Light Water Reactor) is the European concept design for a SCWR (SuperCritical Water Reactor). This unique reactor design consists of a three pass core with intermediate mixing plena. As the supercritical water passes through the core, it experiences a significant density reduction. This large change in density could be used as the driving force for natural circulation of the coolant, adding an inherent safety feature to this concept design. The idea of natural circulation has been explored in the past for boiling water reactors (BWR). From those studies, it is known that the different feedback mechanisms can trigger flow instabilities. These can be purely thermo-hydraulic (driven by the friction -mass flow rate or gravity -mass flow rate feedback of the system), or they can be coupled thermo-hydraulic -neutronic (driven by the coupling between friction, mass flow rate and power production). The goal of this study is to explore the stability of a natural circulation HPLWR considering the thermo-hydraulic -neutronic feedback. This was done through a unique experimental facility, DeLight, which is a scaled model of the HPLWR using Freon R23 as a scaling fluid. An artificial neutronic feedback was incorporated into the system based on the average measured density. To model the heat transfer dynamics in the rods, a simple first order model was used with a fixed time constant of 6 seconds. The results include the measurements of the varying decay ratio (DR) and frequency over a wide range of operating conditions. A clear instability zone was found within the stability plane, which seems to be similar to that of a BWR. Experimental data on the stability of a supercritical loop is rare in open literature, and these data could serve as an important benchmark tool for existing codes and models.

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Section: Resultssupporting

confidence: 89%

Section: Linear Stabilitymentioning

confidence: 98%

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Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

T’Joen

Rohde

2012

Nuclear Engineering and Design

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“…The heated section contains 120 axial nodes after verification of grid independency. Care has been taken to describe the fluid properties as accurately as possible because the location of the stability boundary is known to be very sensitive to any deviation from reality [20]. We therefore used cubic splines consisting of 30 nodes within the relevant enthalpy range.…”

Section: Numerical Validationmentioning

confidence: 99%

Downscaling a supercritical water loop for experimental studies on system stability

Rohde

Marcel

T’Joen

et al. 2011

International Journal of Heat and Mass Transfer

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“…In 2004, Lomperski et al (2004) reported an early experimental study of supercritical CO 2 in a natural circulation loop but no flow instability was found during tests. Jain et al (2006) performed a linear stability analysis for a natural circulation loop with supercritical CO 2 . Results revealed that the stability threshold of natural circulation loops was a complex function of fluid properties and loop geometries, and was not strictly confined to the near-peak region of the steady state flow-power curve.…”

Section: Instability Studies Of Circulation Loop 23mentioning

confidence: 99%

Numerical Instability Study of Supercritical Water Flowing Upward in Two Heated Parallel Channels

Chatoorgoon

Ormiston

2017

Proceedings of the 20th Pacific Basin Nuclear Conference

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A three dimensional numerical investigation of supercritical water flowing upward in two heated parallel channels was developed using a RANS model in the Computational Fluid Dynamics (CFD) code ANSYS CFX. The standard k- turbulence model with scalable wall functions was adopted throughout this numerical study.The effects of spatial and temporal grid sizes on flow instability were studied first. Then oscillatory instabilities of nine experimental cases were predicted using the CFX code.For comparison purposes, Chatoorgoon"s 1-D non-linear SPORTS code was also used to determine the instability boundary. These new numerical results were compared with the experimental data and previous numerical results by other investigators.Additionally, the effects of changing the outlet plenum volume, the turbulent Prandtl number, the turbulence inlet conditions, the outlet K factor, the maximum iterations per time step in the transient analysis and the order of the transient scheme on the instability thresholds were examined.ii ACKNOWLEDGEMENTS

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A Linear Stability Analysis for Natural-Circulation Loops Under Supercritical Conditions

Cited by 40 publications

References 6 publications

Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

Experimental study of the coupled thermo-hydraulic–neutronic stability of a natural circulation HPLWR

Downscaling a supercritical water loop for experimental studies on system stability

Numerical Instability Study of Supercritical Water Flowing Upward in Two Heated Parallel Channels

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