scholarly journals Analysis of Unsteady Behaviour of Natural Circulation Helium Loop

2020 ◽  
Vol 328 ◽  
pp. 03009
Author(s):  
Matej Vach ◽  
Branislav Knížat ◽  
Marek Mlkvik ◽  
Róbert Olšiak ◽  
František Urban ◽  
...  
Keyword(s):  
Experimental Data ◽  
Nuclear Reactor ◽  
Natural Circulation ◽  
Computational Grids ◽  
Time Interval ◽  
Natural Circulation Loop ◽  
Unsteady Fluid Flow ◽  
Unsteady Fluid ◽  
The One ◽  
Coolant System

This paper deals with the one-dimensional unsteady fluid flow model of the natural circulation loop. The presented model represents the experimental facility Helium Loop STU which is the physical model of an emergency coolant system of a nuclear reactor. The governing equations are solved according both Euler and Lagrange approaches on two parallel computational grids. Linearization of equations and semi-implicit discretization scheme are used to enhance the algorithm effectiveness. The simulation results were compared to experimental data. The model can be considered as high-accurate in comparison with experimental data (relative error 1.14÷1.15 % at specified time interval).

scholarly journals Mathematical modeling and numerical investigation of density wave instability of supercritical natural circulation loop

2021 ◽  
Vol 321 ◽  
pp. 04004
Author(s):  
Santosh Kumar Rai ◽  
Neha Ahlawat ◽  
Pardeep Kumar ◽  
Vinay Panwar
Keyword(s):  
Energy Conservation ◽  
Natural Circulation ◽  
Density Wave ◽  
Circulation Loop ◽  
Wave Instability ◽  
Conservation Equations ◽  
One Dimensional ◽  
Natural Circulation Loop ◽  
The One ◽  
Riser Height

In present paper, a mathematical model based on the one dimensional nonlinear mass, momentum and energy conservation equations has been developed to study the density wave instability (DWI) in horizontal heater and horizontal cooler supercritical water natural circulation loop (HHHC-SCWNCL). The one dimensional nonlinear mass, momentum and energy conservation equations are discretized by using finite difference method (FDM). The numerical model is validated with the benchmark results (NOLSTA model). Numerical simulations are performed to find the threshold stability zone (TSZ) and draw the stability map for natural circulation loop. Further, effect of change in diameter and riser height on the density wave instability of SCWNCL has been investigated.

Stability Behavior of Single-Phase Natural Circulation Loop

2003 ◽  
Author(s):  
Seyed Khalil Moussavian ◽  
Mario Misale ◽  
Francesco D’Auria ◽  
Mahmoud Salehi
Keyword(s):  
Natural Circulation ◽  
The Body ◽  
Linear Stability Theory ◽  
Circulation Loop ◽  
Conservation Equations ◽  
Cold Zone ◽  
Natural Circulation Loop ◽  
The Stability ◽  
The One ◽  
The University

The circulating fluid in natural circulation loops would absorb heat from the hot zone (source) and will transport it to the cold zone (sink) without using of any mechanical pumps or other devices. The fluid density differences in hot and cold zones would lead buoyancy force which is introduced as the body force for the loop. By introducing the one-dimensional conservation equations; mass, momentum and energy in the loop and applying the perturbation method, or linear stability theory, would help us to study the stability of the rectangular natural circulation loop. The conservation equations in transient form were solved using the finite difference method. The results obtained from the linear and nonlinear stability studies would be compared with the experimental data of DITEC loop (LOOP#1) obtained at the University of Genova and with other suitable data in the literature.

An Experimental and Numerical Study to Support Development of Molten Salt Breeder Reactor

2017 ◽  
Vol 3 (3) ◽  
Author(s):  
A. K. Srivastava ◽  
R. Chouhan ◽  
A. Borgohain ◽  
S. S. Jana ◽  
N. K. Maheshwari ◽  
...  
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Molten Salt ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Natural Circulation ◽  
Research Centre ◽  
Numerical Studies ◽  
Natural Circulation Loop ◽  
Transient Experiments

Conceptual molten salt breeder reactor (MSBR) is under development in Bhabha Atomic Research Centre (BARC) with long-term objective of utilizing abundant thorium available in India. It is based on molten salts, which acts as fuel, blanket, and coolant for the reactor. LiF–ThF4 (77.6–22.4 mol %) is proposed as a blanket salt for Indian MSBR. A laboratory scale molten salt natural circulation loop (MSNCL) named molten active fluoride salt loop (MAFL) has been setup for thermal-hydraulic, material compatibility, and chemistry control studies. Steady-states and transient experiments have been performed in the operating temperature range of 600–750 °C. The loop operates in the power range of 250–550 W. Steady-state correlation given for natural circulation flow in a loop is compared with the steady-state experimental data. The Reynolds number was found to be in the range of 57–114. Computation fluid dynamics (CFD) simulation has also been performed for MAFL using openfoam code, and the results are compared with the experimental data generated in the loop. It has been found that predictions of openfoam are in good agreement with the experimental data. In this paper, features of the loop, its construction, and the experimental and numerical studies performed are discussed in detail.

Experimental and Analytical Study on the Heat Transfer Characteristics in a Natural Circulation Loop for an Integral Type Reactor

2010 ◽  
Author(s):  
Hyun-Sik Park ◽  
Ki-Yong Choi ◽  
Seok Cho ◽  
Sung-Jae Yi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Natural Circulation ◽  
Circulation Loop ◽  
Circulation Flow ◽  
Integral Type ◽  
Heat Transfer Characteristics ◽  
Flow Rates ◽  
Type Reactor ◽  
Natural Circulation Loop

The heat transfer characteristics in a natural circulation loop for an integral type reactor were experimentally investigated by using the VISTA facility and steady-state natural circulation flow rates were acquired for various core powers and feed water flow rates. The experimental data were compared with the predictions from existing correlations of Duffey et al. (1987) and Vijayan et al. (2002). It was shown that Duffey et al. (1987)’s correlation for a two-phase natural flow predicted the experimental data well. Also the experimental data on the natural circulation in the primary loop of the VISTA facility were analyzed by using a best-estimate system analysis code, MARS. The MARS code predicted the overall natural circulation flow characteristics reasonably.

Comparative analysis and verification of engineering methods of shallow cracks effect for fracture toughness prediction for reactor pressure vessels

2020 ◽  
pp. 140-165
Author(s):  
V. I. Kostylev ◽  
B. Z. Margolin
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Comparative Analysis ◽  
Nuclear Reactor ◽  
Probabilistic Approach ◽  
Pressure Vessels ◽  
Local Methods ◽  
European Method ◽  
Shallow Crack ◽  
Reactor Pressure

The main features of shallow cracks fracture are considered, and a brief analysis of methods allowing to predict the temperature dependence of the fracture toughness KJC (T) for specimens with shallow cracks is given. These methods include DA-method, (JQ)-method, (J-T)-method, “local methods” with its multiparameter probabilistic approach, GP method uses power approach, and also two engineering methods – RMSC (Russian Method for Shallow Crack) and EMSC (European Method for Shallow Crack). On the basis of 13 sets of experimental data for national and foreign steels, a detailed verification and comparative analysis of these two engineering methods were carried out on the materials of the VVER and PWR nuclear reactor vessels considering the effect of shallow cracks.

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