Reduced-scale study of the coupling between thermal and wind effects on the ventilation systems of nuclear facilities

Abstract

To study heat and mass transfers inside nuclear facilities equipped with ventilation systems, a methodology was developed to carry out reduced-scale experiments for studying flows induced by thermal and wind effects simultaneously. The methodology was numerically validated on simple configurations and applied to a reference configuration representative of nuclear facilities. The effects of wind and thermal phenomena on heat and mass transfers in various ventilation situations (normal ventilation or ventilation switched off) and scenarios of heat supply were studied in wind tunnel experiments. The thermal sources that could be generated by an industrial process were reproduced experimentally with a helium injection. The objectives of this article are to present the scaling-down methodology and the main experimental results concerning the influence of thermal effects on airflows in the reduced-scale model. The effects of heat with or without wind on loss of building containment were also highlighted and analysed. Finally, the reliability of SYLVIA simulation software, which was used to support safety assessments in nuclear facilities, was analysed using the experimental results.

Keywords:

• Ventilation networks
• similarity
• non-isothermal flows
• reduced-scale experiments
• SYLVIA simulation software
• nuclear facilities

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Thomas Le Dez is engineer in Inovertis group, society specialized in innovative process. His work focuses on the improvement and maintenance of ventilation systems, mainly in the nuclear facilities. The software SYLVIA is used in order to design the ventilation systems of several facilities.

Jérôme Richard is a Dr. engineer at the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN). He is the head of the Laboratory of Experiments and Modelling in Airborne dispersion and Containment. His work focuses on the modelling of thermal airflows and pollutants transfers inside the nuclear facilities, especially in ventilation networks.

Christian Inard is Professor at La Rochelle University, Department of Civil Engineering. His research activities are focused on design of low energy buildings, indoor thermal comfort and indoor air quality, HVAC systems modelling and control, and urban microclimate modelling and experiment.

Nicolas Le Roux is a Dr. engineer at the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN), in the Laboratory of Experiments and Modelling in Airborne dispersion and Containment. His work focuses on the numerical and experimental characterization of airflows inside the nuclear facilities, in particular in ventilation networks. He conducted a PhD thesis on the reduced-scale study of airflows inside mechanically ventilated buildings subjected to wind.

François Demouge is a Research Engineer at the CSTB (Scientific and Technical Center for Building). He is part of the Numerical Modelling Group of the Climatology, Aerodynamics, Pollution and Epuration Department. His work focuses on the performance assessment of Ventilation Systems with regards to Indoor Air Quality, Thermal comfort and Energy Savings.

Xavier Faure is a Research Engineer at the CSTB (Scientific and Technical Center for Building). His work mainly focuses on thermo-aeraulic fields and he is head of the ventilation laboratory for standard evaluation of ventilation devices.

Laurent Ricciardi is an engineer at the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN). He is the deputy head of the Airborne pollutants and Containment Department. His work focuses on modelling of airflows and gaseous/particulate pollutants transfers inside the nuclear facilities, in normal, degraded or accident situation.