Coupled Monte Carlo-CFD analysis of heat transfer phenomena in a supercritical water reactor fuel assembly

2020 ◽  
Vol 141 ◽  
pp. 107312 ◽  
Author(s):  
Landy Castro ◽  
Juan-Luis François ◽  
Carlos García
Author(s):  
Mariana Ruzickova ◽  
Ales Vojacek ◽  
Thomas Schulenberg ◽  
Dirk C. Visser ◽  
Radek Novotny ◽  
...  

The supercritical water reactor (SCWR) is one of the six reactor concepts being investigated under the framework of the Generation IV International Forum (GIF). One of the major challenges in the development of a SCWR is to develop materials for the fuel and core structures that will be sufficiently corrosion resistant to withstand supercritical water conditions and to gain thermal-hydraulic experimental data that could be used for further improvement of heat transfer predictions in the supercritical region by numerical codes. Previously, core, reactor, and plant design concepts of the European high-performance light water reactor (HPLWR) have been worked out in great detail. As the next step, it has been proposed to carry out a fuel qualification test (FQT) of a small-scale fuel assembly in a research reactor under typical prototype conditions. Design and licensing of an experimental facility for the FQT, including the small-scale fuel assembly, the required coolant loop with supercritical water, and safety and auxiliary systems, was the scope of the recently concluded project “Supercritical Water Reactor–Fuel Qualification Test” (SCWR-FQT) described here. This project was a collaborative project cofunded by the European Commission, which took advantage of a Chinese–European collaboration, in which China offered an electrically heated out-of-pile loop for testing of fuel bundles. The design of the facility, especially of the test section with the fuel assembly, and the most important results of steady-state and safety analyses are presented. Material test results of the stainless steels considered for the fuel cladding are briefly summarized. Finally, important outcomes and lessons learned in the “Education and Training” and “Management” work packages are presented.


Author(s):  
Ajoy Debbarma ◽  
K. M. Pandey

Research activities are ongoing for High performance light water reactor (HPLWR) with square double rows fuel assembly to develop nuclear power plants with the purpose to achieve a high thermal efficiency and to improve their economical competitiveness. However, there is still a big deficiency in understanding and prediction of heat transfer in supercritical fluids. This paper evaluates three-dimensional turbulent flow and convective heat transfer in a single-phase and steady-state sub-channel of HPLWR by using general computational fluid dynamics code, Ansys 14 Fluent. The major concern using supercritical water as work fluid is the heat transfer characteristics due to large variations of thermal properties of supercritical water near pseudo-critical line. In order to ensure the safety of operation in High performance light water reactor (HPLWR), heat transfer deterioration (HTD) must be avoided. Numerical results prove that the RNG k-e model with the enhanced near-wall treatment obtained the most satisfactory prediction and lead to satisfactory simulation results. The HPLWR Square fuel assembly has many square-shaped water rods, Out of four types of sub-channels; three sub-channels SC-1, SC-2 and SC-3 are investigated (adjacent to the side of the moderator flow channels (SC-1) (moderator tube and assembly gap), central sub-channels formed by four fuel rods (SC-2), adjacent to the corner of the moderator tube (SC-3). Since coolant flow distribution in the fuel assembly strongly depends on the gap width between the fuel rod and water rod, fuel rod pitch to diameter ratio 1.1–1.4 with 8mm diameter are considered for simulation. Sub-channel analysis clarifies that coolant flow distribution becomes uniform when the gap width is set to 1.0 mm. was less than 620°C. Effects of various parameters, such as boundary conditions and pitch-to-diameter ratios, on the mixing phenomenon in sub-channels and heat transfer are investigated. The effect of pitch-to-diameter ratio (P/D) on the distributions of surface temperature and heat transfer coefficient (HTC) in a sub-channel, it was found that HTC increases with P/D 1.1 first and then decreases with increasing P/D ratio. Apart from the basic geometry sub-channel, a square sub-channel with a wire-wrapped rod inside has been chosen to investigate the “wire effect”.


2013 ◽  
Vol 59 ◽  
pp. 211-223 ◽  
Author(s):  
Emmanuel Ampomah-Amoako ◽  
Edward H.K. Akaho ◽  
Benjamin J.B. Nyarko ◽  
Walter Ambrosini

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