CFD Analysis of the Heavy Liquid Metal Flow Field in the MYRRHA Pool (original) (raw)

Measurement and analysis of turbulent liquid metal flow in a high-power spallation neutron source—EURISOL

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The European Isotope Separation On-Line (EURISOL) design study completed in 2009 examined means of producing exotic nuclei for fundamental research. One of the critical components identified in the study was a high-power neutron spallation source in which a target material is impacted by a proton beam producing neutrons by a process known as spallation. Due to the high heat power deposition, liquid metal, in this case mercury, is the only viable choice as target material.

Heavy liquid metal natural circulation in a one-dimensional loop

Nuclear Engineering and Design, 2011

The ENEA Brasimone Research Centre since 1999 is strongly involved in the national and European research programmes performed in the field of heavy liquid metal technology aiming at the development of critical (LFR) and subcritical (ADS) nuclear systems.

Preliminary CFD Assessment of an Experimental Test Facility Operating with Heavy Liquid Metals

The CFD analysis of a Venturi nozzle operating in LBE (key component of the CIRCE facility, owned by ENEA) is presented in this paper. CIRCE is a facility developed to investigate in detail the fluid-dynamic behavior of ADS and/or LFR reactor plants. The initial CFD simulations have been developed hand in hand with the comparison with experimental data: the test results were used to confirm the reliability of the CFD model, which, in turn, was used to improve the interpretation of the experimental data. The Venturi nozzle is modeled with a 3D CFD code (STAR-CCM+). Later on, the CFD model has been used to assess the performance of the component in conditions different from the ones tested in CIRCE: the performance of the Venturi is presented, in terms of pressure drops, for various operating conditions. Finally, the CFD analysis has been focused on the evaluation of the effects of the injection of an inert gas in the flow of the liquid coolant on the performance of the Venturi nozzle.

Journal of Nuclear Energy Science & Power Generation Technology Design of a Heavy Liquid Metal Neutron Spallation Target for Experimental Accelerator driven Sub-critical Reactor

In this paper detailed design of a liquid metal Lead-Bismuth-Eutectic (LBE) neutron spallation target for an experimental ADS reactor of ~30 MW with sub-criticality (k) of 0.975 is presented. The high energy beam consists of 650 MeV and 0.9 mA proton beam. The circulation of the liquid metal is based on gas lift method. Extensive numerical simulations have been carried out to optimise the target geometry, LBE/gas flow rate, beam parameters, neutron yield etc. This paper also includes time dependent two phase CFD analysis to study the effect of nitrogen gas flow rate on LBE flow rate, 3D thermal-hydraulic studies of liquid metal flow near the window and spallation region. The optimum asymmetric flow geometry at the bottom of the target to shift the stagnation zone to minimize the window temperature and estimation of thermo mechanical stress in the window has been carried out. In addition, spallation neutron generation and their energy spectrum, heat deposition distribution, spallation products and their activities have been estimated using high energy particle transport code FLUKA. (Energy: ~ 1 GeV and Current: few to tens of mA) interacts with the target, which is located in the core of a subcritical reactor and produces spallation neutrons (~ 10 19 n/s) that diffuse into and drive the reactor [6]. In this paper, detailed design of a heavy liquid metal neutron spallation target suitable for the proposed experimental MultiPurpose Research Reactor (MPRR) operating under ADS mode is presented. The experimental reactor is of ~30 MW (thermal) and will operate at k = 0.975. Various target configurations have been studied with different beam energies, top injection and bottom injection for different geometries. Based on this analysis, it is proposed to have LINAC with proton energy of 650 MeV and beam current of 0.9-1.0 mA for generating the required spallation neutrons [7]. The target will be located at the centre of the reactor in a vertical cylindrical diameter space of 240 mm. Heavy density liquid metal LBE (lead-bismuth-eutectic of 45% lead and 55% bismuth) will be used as spallation target. The schematic of the proposed Reactor is shown in Figure 1. Basic Spallation Target Loop The major components of the module are the window (the solid barrier through which the beam enters the target), spallation region above the window, riser pipe along with mixer for gas injection, annular down comer along with heat exchanger, cover gas region which also acts as a gravity based passive gas separator. The schematic of the target module and various subsystems are shown in Figure 2. Instead of mechanical pump or electromagnetic pump, the circulation of the liquid metal is achieved by the gas lift method [8]. This enhances the reliability of the system. In addition, an outer water cooled jacket will be provided around the target module to act as a safety jacket in case of LBE window failure [9]. The window is a very important component of the loop. Typically it is a hemispherical in shape, having a thickness of ~1.5 mm at the outlet and ~3 mm at the edges. One of the candidates for the proposed window material that will be tested in this facility is T91 steel [10]. The incident proton beam deposits 409 kW of heat (as estimated by FLUKA code presented later) in the target and 4.1 kW in the window for the above beam. An additional heat of 370 kW is deposited due to gamma radiation from the reactor. The liquid metal is circulated to extract the heat deposited by the beam in the window and in the liquid metal itself. The circulation of the liquid metal is achieved in the loop as follows. In the mixer, located below the riser pipe, nitrogen (or argon or helium) gas is injected. This gives rise to two-phase mixture in the riser pipe and consequently leads to a density difference between the riser and downcomer pipes. This causes circulation of liquid metal in the loop. The riser height is designed in such a way that required flow rate of liquid metal is achieved. Both the phases enter the separator located at the top of the loop. Gas is separated here and taken to a gas outlet pipeline. The liquid metal flows down through the downcomer (annular pipe). At the top of the downcomer and below the separator, a heat-exchanger is located which extracts the heat from the liquid metal. At the bottom of the downcomer, where the liquid metal enters spallation region, there is a cut at slanted angle to break the flow symmetry [11]. This is to shift the stagnation zone at the bottom and provide convective heat transfer, where proton beam deposits bulk of the heat. Through

Computational Fluid Dynamics Throughout the Design Process in Nuclear Applications

2008

Though Computational Fluid Dynamics (CFD) is recognized as an emerging engineering tool, it is not infrequent that engineering projects make little or no use of it during the early design stages. CFD codes, if used at all, are left for the final stages in which an already finished design is tested to confirm its performance before construction. Scaled mock-ups are also used at these stages, but in many cases they are economically unaffordable. In a nuclear reactor the operational radiation dose results from coupled processes of coolant flow and species radioactive decay. Thermal-hydraulic phenomena such as stratification, stagnation and inappropriate flow pattern should thus be considered from the early design stages. In this article we want to report on an innovative experience in this direction, namely the application of CFD since the first stages of the design of some components of the reactor to be built by INVAP S. E. in Lucas Height, Australia, for the Australian National Science and Technology Organization (ANSTO). The analysis of the aforementioned components leads, sooner or later, to the need for massive threedimensional simulations which can only be performed with high performance computing techniques. This motivates a brief description of the software (PAR-GPFEP, presented in MECOM'2000) and of the hardware (Linux PC-cluster) used to successfully produce the simulations. The two case studies addressed in this presentation elaborate on the scientific, software-related and strategic aspects of CFD consulting work throughout the design process. Though the application is specific to the nuclear industry, the methodologies are applicable to many other areas of engineering design.

Status and future challenges of CFD for liquid metal cooled reactors

Liquid metal cooled reactors are envisaged to play an important role in the future of nuclear energy production because of their possibility to use natural resources efficiently and to reduce the volume and lifetime of nuclear waste. Typically, sodium and lead(-alloys) are envisaged as coolants for such reactors. Obviously, in the development of these reactors, thermal-hydraulics is recognized as a key (safety) challenge. A relatively new technique to deal with thermal-hydraulics issues is Computational Fluid Dynamics (CFD). This technique is used increasingly nowadays for design and safety evaluation purposes. This paper will discuss the development status of CFD application to liquid metal cooled reactors. In addition, the main challenges for future developments will be indicated. Firstly, the technological challenges will be discussed which ask for CFD application. Afterwards, the needs for CFD development and/or validation will be discussed. The discussion will also include the need for accompanying experiments.

Leading CFD Models for Innovative Nuclear Applications at CRS4

2014

In the last 15 years, CRS4 has developed a consolidated experience in CFD simulations in the field of innovative nuclear system. The complexity of the applications has progressively increased during these years and we present three of the most recent ones. The first application regards the construction of a CFD model of the entire primary coolant loop of MYRRHA, the future Belgian multi-purpose Lead-Bismuth Eutectic (LBE) cooled nuclear reactor, built in the framework of the FP7 SEARCH project. The second application regards the control rod insertion dynamics in the MYRRHA framework, for use in the FP7 MAXSIMA project. The third application concerns the conception of liquid Lead spallation target for the European Spallation Source (ESS), developed during the FP7 THINS project. The model of the MYRRHA primary coolant loop combines a free-surface flow and a thermal flow, driven by hydraulic pumps. Heat is provided by the reacting nuclear core and removed by heat exchangers and thermal...

A fusion reactor design with a liquid first wall and divertor

Fusion Engineering and Design, 2004

Within the magnetic fusion energy program in the US, a program called APEX is investigating the use of free flowing liquid surfaces to form the inner surface of the chamber around the plasma. As part of this work, the APEX Team has investigated several possible design implementations and developed a specific engineering concept for a fusion reactor with liquid walls. Our approach has been to utilize an already established design for a future fusion reactor, the ARIES-RS, for the basic chamber geometry and magnetic configuration, and to replace the chamber technology in this design with liquid wall technology for a first wall and divertor and a blanket with adequate tritium breeding. This paper gives an overview of one design with a molten salt (a mixture of lithium, beryllium and sodium fluorides) forming the liquid surfaces and a ferritic steel for the structural material of the blanket. The design point is a reactor with 3840 MW of fusion power of which 767 MW is in the form of energetic particles (alpha power) and 3073 MW is in the form of neutrons. The alpha plus auxiliary power total 909 MW of which 430 MW is radiated from the core mostly onto the first wall and the balance flows into the edge plasma and is distributed between the first wall and the divertor. In pursuing the application of liquid surfaces in APEX, the team has developed analytical tools that are significant achievements themselves and also pursued experiments on flowing liquids. This work is covered elsewhere, but the paper will also note several such areas to indicate the supporting science behind the design presented. Significant new work in modeling the plasma edge to understand the interaction of the plasma with the liquid walls is one example. Another is the incorporation of magneto-hydrodynamic (MHD) effects in fluid modeling and heat transfer.