Themes: Engineering sciences: fluid mechanics, energetics
Thesis location: Aerosol Physics and Metrology Laboratory (LPMA) - Gyf-sur-Yvette (91)
Start: October 2021
Master 2 research with mention of university or engineering school. Aerosol physics and metrology, fluid mechanics, combustion, energetics, aerosol physico-chemistry, optical diagnostics.
Age limit: 26 years old unless otherwise stated.
Among the accidents likely to occur in a basic nuclear installation (BNI), fire represents a major risk. It can damage elements essential to safety and lead to the dispersion of radioactive materials in the installation and even in the environment. IRSN is carrying out research in order to develop models to predict the quantities as well as the physicochemical properties of aerosols emitted during a fire. The progress of this knowledge on the specific properties of these particles (morphology, composition, size, thermal and electrical properties) are thus gradually taken into consideration in order to describe the consequences induced by their deposition on the equipment participating in the safety of BNI ( clogging of filtration devices, malfunction of electrical equipment, etc.). The main objective of this thesis is to provide experimental knowledge of a phenomenological nature on the effects of scale and ventilation on the physico-chemical properties of aerosols emitted during fires. In the current state of our knowledge, the data and models available in the scientific community remain limited. This thesis work is necessary before considering the development of a robust methodology for the real-scale transposition of the work carried out by IRSN relating to the consequences, from the point of view of the safety of installations and containment of radioactive substances within them, the production, transport and deposition of soot produced during a fire. This thesis is based on the complementarity of the developments envisaged at CORIA and IRSN. In a first phase, we will seek to describe the influence of ventilation conditions on the formation and properties of soot in an academic flame developed by CORIA for a liquid fuel. State-of-the-art metrological means will be used by this laboratory in order to determine, in-situ, the optical properties of the soot produced under these conditions. At the end of this development, part of this optical metrology will be transposed to an intermediate scale (<0.1 m) by using the IRSN Saclay facilities which allow the study of liquid and solid fuels. This transposition will then be extended to larger fireplaces (0.1-1 m) within the facilities to carry out fires in the confined and under-ventilated test rooms of IRSN Cadarache. The advances in knowledge of this thesis work consist of: • the proposal of innovative diagnostics to determine the optical properties of soot produced by fire outbreaks, paving the way for the establishment of their radiative properties, • improving knowledge on the production of soot from fire sources