10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Experimental Single Effect Analysis of the Particle Retention Efficiency of a Gas Scrubber
MICHAEL KLAUCK, Kathrin Trollmann, Jeffrey Kobalz, Robin de Winter, Hans-Josef Allelein, Forschungszentrum Jülich GmbH
Abstract Number: 1238 Working Group: Control and Mitigation
Abstract Avoiding or at least minimizing effects of severe accidents in nuclear power plants on the environment is one of the most essential objectives of Severe Accident Management (SAM). A significant part of the fission products released in the process of a loss of coolant accident can reach the containment – the last dense barrier against the leakage of radioactive isotopes – in the form of airborne particles. Once leaked into the atmosphere, gaseous aerosols accumulate over time and might lead to long-term land contamination. Consequently, reliable prediction of aerosol behavior inside the containment during severe accidents is the key to optimizing SAM and thus to minimizing consequences for the environment. This is of particular relevance when it comes to understanding relevant processes regarding particle retention in a water seal (so-called ‘pool scrubbing’) which is considered to be one of the processes to efficiently filter the containment atmosphere before venting into the surrounding environment.
Several international reactor safety projects have been studying some partial aspects of pool scrubbing and Filtered Containment Venting Systems (FCVS), e.g. OECD/NEA-THAI 3 and the European Commission-funded PASSAM project. However, in order to develop numerical models based on a phenomenological approach, a broad experimental data base with detailed particle characterization is needed. In the framework of the German national ‘SAAB’ project (‘Severe Accident Aerosol Behavior’ 2013-2017, funded by the German Federal Ministry of Economic Affairs and Energy), a sophisticated new test facility has been designed and constructed that allows pool scrubbing-related phenomena to be addressed. Its modular set-up allows the investigation of particle retention efficiency at different pool heights up to 6 m and various options regarding injection geometry. Furthermore, two different concepts provide the opportunity to ensure reproducible and constant aerosol generation for both insoluble and soluble particles. Consequentially, the recently launched follow-up SAAB-II project (2017-2021) aims at providing a reliable data base for model development of water-induced particle retention. Pool scrubbing is investigated focusing on single effect tests and the influence of different boundary conditions, including variations of pool height, injection velocity, temperatures, steam supply, particle size distribution, aerosol composition, and injection geometry.
The paper introduces the SAAB-II project and includes a detailed description of the experimental facility, its measurement instrumentation and the aerosol generators, and gives an overview of the experimental results achieved so far.