Development of a multiphysics model for the study of fuel compressibility effects in the Molten Salt Fast Reactor

Cervi, Eric; Lorenzi, Stefano; Cammi, Antonio; Luzzi, L.

doi:10.1016/j.ces.2018.09.025

Cited by 44 publications

(10 citation statements)

References 15 publications

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“…23 In this regard, the present work may pave the way to future implementations of the adjoint method in 3D simulation tools for nuclear reactor analysis, such as the multiphysics toolkit OpenFOAM. 34 An interesting research direction can be the extension and the assessment of the proposed method with application to the 3D geometry of the MSFR, keeping into account the helium bubbling system, [35][36][37] fuel compressibility effects, 38,39 and solid wall deformation feedbacks on reactivity. [40][41][42] through the project "Nuclear Innovation Center for Haeorum Alliance".…”

Section: Discussionmentioning

confidence: 99%

Adjoint‐based sensitivity analysis of circulating liquid fuel system for the multiphysics model of molten salt reactor

et al. 2020

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Summary The strongly coupled behaviors between neutronics and thermal‐hydraulics of liquid‐fueled molten salt reactors make it difficult to evaluate system behaviors, due to the transport of precursors along moving fuel. Extending an adjoint‐based method on the multiphysics approach, different assumptions on temperature dependencies of nuclear and thermophysical properties of salt are included in the local sensitivity analysis of a circulating liquid fuel system. Local sensitivity of various types of system response in steady‐state is analyzed for 39 parameters including coupling models, reactor design values, and kinetic constants of delayed neutron and decay heat precursors for a simplified 1D model of molten salt fast reactor. Extended adjoint‐based sensitivity analysis method for MSR is successfully validated achieving 1.38% deviation on average between a recalculation and adjoint method, comparing local sensitivities to all parameters. Also, it takes 66.3 times less in computational time compared with the recalculation method for evaluating the sensitivity of the same type of system response. The importance of all the parameters to the system response is analyzed according to the assumptions on temperature dependencies to nuclear data and salt properties. The most influencing ones are fission energy‐related terms, and their importance increases when temperature dependencies are taken into account, compared with constant properties. Changes of influences on the sensitivity are investigated from the relative changes of the parameter values in various system response types, and it implies the importance to consider the multiphysics modeling on the local sensitivity analysis.

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Section: Discussionmentioning

confidence: 99%

Adjoint‐based sensitivity analysis of circulating liquid fuel system for the multiphysics model of molten salt reactor

et al. 2020

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“…According to Ref. 23, the equilibrium void fraction is about 1%. This value is chosen as the boundary condition for the periodic simulation (i.e., the total void fraction α is around 0.01), and three initial bubble distributions (i.e., in Fig.…”

Section: Iiib Determination Of the Flow Regimementioning

confidence: 98%

Interface Tracking Investigation of the Sliding Bubbles Effects on Heat Transfer in the Laminar Regime

2021

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Helium gases are utilized to remove fission products from the molten salt fast reactor (MSFR) core during operation. Helium gases and other volatile fission products may be introduced into the intermediate heat exchanger channels. The effect of these gases on heat transfer is essential for the MSFR to operate properly, especially in laminar flow regimes. The computational fluid dynamics code PSI-BOIL was selected to examine this problem because of its interface tracking capability. A periodic square duct simulation created the flow regime, resulting in a sliding bubble regime. Following that, we examined the impact of heat transfer using an extended nonperiodic channel simulation with a succession of corner bubble arrays. Due to the combined effects of low thermal diffusivity and laminar flow characteristics, it is shown that the length of heat transfer augmentation may extend to at least five bubble diameters downstream of the bubble placement. Finally, we examined the impact of interphasic heat transfer between an inert gas and a liquid. The bulk of the heat transfer amplification effect was due to the motion of the bubbles rather than interphasic heat transfer.

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“…The OpenFOAM library, based on standard finite-volume methods for CFD calculations, is used to develop the numerical solver used in the present work. Originally developed for the transient analysis of the MSFR (Aufiero et al, 2014), the adopted multiphysics solver was recently extended to allow for the study of compressibility effects during super-prompt-critical transients (Cervi et al, 2019b) and of the bubbling system (Cervi et al, 2019a). The version employed in this work features single-phase incompressible thermal-hydraulics, multi-group neutron diffusion and transport equations for delayed neutron and decay heat precursors.…”

Section: The Multiphysics Modelmentioning

confidence: 99%

An Eulerian Single-Phase Transport Model for Solid Fission Products in the Molten Salt Fast Reactor: Development of an Analytical Solution for Verification Purposes

et al. 2021

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Nuclear reactor modeling has been shifting, over the last decades, towards full-core multiphysics analysis due to the ever-increasing safety requirements and complexity of the designs of innovative systems. This is particularly true for liquid-fuel reactor concepts such as the Molten Salt Fast Reactor (MSFR), given their strong intrinsic coupling between thermal-hydraulics, neutronics and fuel chemistry. In the MSFR, fission products (FPs) are originated within the liquid fuel and are carried by the fuel flow all over the reactor core and through pumping and heat exchange systems. Some of FP species, in the form of solid precipitates, can represent a major design and safety challenge, e.g., due to deposition on solid boundaries, and their distribution in the core is relevant to the design and safety analysis of the reactor. In this regard it is essential, both for the design and the safety assessment of the reactor, the capability to model the transport of solid FPs and their deposition to the boundary (e.g., wall or heat exchanger structures). To this aim, in this study, models of transport of solid FPs in the MSFR are developed and verified. An Eulerian single-phase transport model is developed and integrated in a consolidated multiphysics model of the MSFR based on the open-source CFD library OpenFOAM. In particular, general mixed-type deposition boundary conditions are considered, to possibly describe different kinds of particle-wall interaction mechanisms. For verification purposes, analytical solutions for simple case studies are derived ad hoc based on the extension of the classic Graetz problem to linear decay, distributed source terms and mixed-type boundary conditions. The results show excellent agreement between the two models, and highlight the effects of decay and deposition phenomena of various intensity. The resulting approach constitutes a computationally efficient tool to extend the capabilities of CFD-based multiphysics MSFR calculations towards the simulation of solid fission products transport.

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Development of a multiphysics model for the study of fuel compressibility effects in the Molten Salt Fast Reactor

Cited by 44 publications

References 15 publications

Adjoint‐based sensitivity analysis of circulating liquid fuel system for the multiphysics model of molten salt reactor

Adjoint‐based sensitivity analysis of circulating liquid fuel system for the multiphysics model of molten salt reactor

Interface Tracking Investigation of the Sliding Bubbles Effects on Heat Transfer in the Laminar Regime

An Eulerian Single-Phase Transport Model for Solid Fission Products in the Molten Salt Fast Reactor: Development of an Analytical Solution for Verification Purposes

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