Aerosol Retention in the Vicinity of a Breach in a Tube Bundle: An Experimental Investigation

Abstract

This article summarizes the main results of a bench-scale program focused on experimentally assessing the aerosol retention near the tube breach in a tube bundle. The major variables investigated were particle nature (polydispersed TiO 2 agglomerates vs. solid, monodisperse SiO 2 spheres) and Re D (0.8−2.7·10 5 ). In addition, comparisons to other data sets provided insights into the particle aerodynamic size effect on retention efficiency. Results showed that particle nature substantially affects aerosol retention in the tube bundle: mass retention efficiency was low for TiO 2 agglomerates (less than 30%) whereas it was much higher for SiO 2 particles (around 85%). Retention efficiency is also affected by Re D : its sensitivity was found to follow a log-normal behavior with a maximum retention attained at Re D near 1·105 . This evolution with Re D was similar for both types of compounds. Particle size also influences retention efficiency: the bigger the TiO 2 agglomerates the lower retention efficiency (no data were available for SiO 2 ). Among all these variables, particle nature was noted to have a prime importance for in-bundle retention, whereas Re D and particle aerodynamic size, although also affect retention efficiency, did not play such a key role. In light of the results, the presence of retention-inhibiting mechanisms such as fragmentation, resuspension or bouncing has been discussed. The data recorded will enhance the overall understanding of the governing mechanisms involved and will serve as a database against which compare model predictions. Nevertheless, further experimental data would be desirable to set up a sound database.

Experimental investigations on nuclear aerosols in a severe accident

“…The deposition patterns observed in previous CAAT2 campaign (Tardáguila and Herranz, 2013) and the modelling results (López del Prá et al, 2010) have helped to understand the gas flow interaction with the tubes (Herranz and Velasco, 2013;Khushnood et al, 2004;Sánchez-Velasco et al, 2010). The flow-induced vibration manifests the possible interaction of the tubes vibration mechanisms with the particles deposition ones.…”

“…To quantify the total mass retained in the bundle, the mass deposited on 30 tubes out of 121 was collected. Extrapolation to the whole bundle might be considered reliable based on symmetry conditions (Herranz et al, 2006;Sánchez-Velasco et al, 2010), CFD simulations (López del Prá et al, 2010) and previous experience. The estimated net retention might be independent from any variable besides the symmetry.…”

A Theoretical Investigation of Aerosol Retention Within the Secondary Side of a Steam Generator Under a SGTR Severe Accident Sequence in a PWR Nuclear Power Plant

“…The third section shows the implementation of the model in a Fortran code describing input and output decks. The fourth one compares predictions with the experimental data available obtained in the laboratory LASS of CIEMAT within the international EU-SGTR and ARTIST projects López del Prá et al, 2010c;Sanchez-Velasco et al, 2010). The fifth section describes the procedure and results of the uncertainty analysis performed to the model and the input parameters.…”

“…Validation of the ARI3SG model was performed by comparing its predictions with the experimental SGTR and CAAT databases Sanchez-Velasco et al, 2010) obtained in the PECA facility of CIEMAT. They were devoted to investigate the aerosol retention in the break stage of a steam generator under dry conditions.…”