Implementation and validation of an aerosol collection model by a spray in a CFD code – Application to the scavenging of aerosols emitted during laser cutting operations of fuel debris for the dismantling of the damaged reactors of Fukushima Dai-ichi

Thomas Gelain (1) , Emmanuel Porcheron (2) , Yohan Leblois (2) , Christophe Chagnot (3) , Christophe Journeau (4) , Damien Roulet (5)

1 IRSN/PSN-RES/SCA/LEMAC - Laboratoire d'expérimentations et de modélisation en aérodispersion et confinement
2 IRSN/PSN-RES/SCA/LPMA - Laboratoire de physique et de métrologie des aérosols
3 LTA - Laboratoire Technologie d'Assemblage
4 DEN
5 ONET

The general context of this article is related to the dismantling of the damaged reactors of Fukushima Dai-ichi and more specifically to the use of the laser cutting technique for the fuel debris retrieval on the damaged reactors. IRSN is involved in a project led by ONET, in collaboration with CEA, to bring relevant elements to analyze the risk involved by the dispersion of aerosols emitted by the dismantling operations. During the laser cutting operations for retrieving the fuel debris in air condition, particles will be produced, inducing a potential risk of dispersion into the environment. Hence, their collection, to prevent their release into the environment, is one of the safety key issues in the dismantling actions of Fukushima Dai-ichi reactors. For that, IRSN performed CFD simulations of aerosol scavenging by a spray, to evaluate the capability of collection by this technique. These simulations, conducted with the ANSYS CFX code, use an eulerian method for the continuous phase and a lagrangian method for the spray for which a collection model detailed by Plumecocq [1] or Marchand [2] was implemented. Aerosols are modelled by the way of a DQMOM population balance implemented by Gelain et al [3] (already used for recent simulations in the same context) and enriched with a deposition model developed by Nerisson et al [4]. In a first time, CFD simulations are performed with the geometry of the TOSQAN vessel, comparatively to experimental results presented in a companion paper. This first step allows to validate the implementation of the collection model and to study the sensitivity to the aerosol size. In a second time, the CFD simulations are conducted with the geometry of the pedestal of Fukushima Dai-ichi reactors, to be more representative of a realistic case. In this configuration, sensitivity studies are described, highlighting the influence of a multispray and of thermal-hydraulic conditions (temperature) on aerosol scavenging.

Domaines: Sciences de l'ingénieur [physics]

Thomas Gelain, Emmanuel Porcheron, Yohan Leblois, Christophe Chagnot, Christophe Journeau, et al.. Implementation and validation of an aerosol collection model by a spray in a CFD code – Application to the scavenging of aerosols emitted during laser cutting operations of fuel debris for the dismantling of the damaged reactors of Fukushima Dai-ichi. 28th International Conference on Nuclear Engineering, ICONE28, Aug 2020, ANAHEIM, United States. ⟨hal-03106522⟩