ARIGS is one of the programs on the aerosol retention on the tubes surrounding the breach within the secondary side of the steam generator in the absence of water. Its development has been internationally framed within the EU-SGTR and the ARTIST programs. Experimental activities were focused on setting up a reliable database in which the influence of gas mass flow rate, breach configuration and particle nature in the aerosol retention are properly considered. Theoretical activities are aimed at developing a predictive tool (ARISG) capable of assessing source term attenuation in the scenario with reasonable accuracy. Given the major importance of jet aerodynamics, 3D CFD analyses are being conducted to assist both test interpretation and model development.
ARISG-I was a step forward in the modeling of the aerosol retention of the steam generator. According to this analysis the main areas where research is needed are: gas jet behavior across the tube bank; particle resuspension, erosion, and/or bouncing; and particle inertial impaction and turbulent deposition under foreseen conditions.
No description available.
Steam generator reliability and performance are serious concerns in the operation of pressurized water reactors. The aim of the SGTR project was to provide a database of fission product retention in steam generator tube rupture sequences and models, which could be applied to estimate the effectiveness of different accident management strategies in these kind of accidents.
The SGTR project made an important step forward to resolve uncertainties of physical models, especially in the aerosol deposition and mechanical resuspension in turbulent flows. There was one sampling at the injection line for the Optical Particle Counter (OPC) aimed at determining the aerosol size distribution and quantifying the mass concentration at the inlet. Within the vessel atmosphere eight samplings were taken to six filters and two cascade impactors, from which the mass concentration exiting the tube mini-bundle was estimated.
The test mini-bundle is a scaled mock-up of the first stage of the steam generator tube bundle. It consists of a squared arrangement housing inside a total of 117 tubes plus four supporting rods placed in the corners. The mini-bundle allows two possible locations of the broken tube. One place is just at the centre of the structure and the other place is three tubes away from the centre.
In severe accidents with primary-to-secondary leakages, the retention of fission products in horizontal steam generators is poorly understood. The understanding of fission product deposition in realistic steam generator conditions is needed in realistic release estimates in PSA studies, and to design efficient accident management procedures. This is considered very important because steam generator tube rupture sequences are included in the risk dominant sequences.
Tube dimensions of the HORIZON model steam generator and Loviisa VVER-440 steam generators are approximately same. Thus it can be assumed that experiments give realistic results.
In addition to the steam generator section itself, the HORIZON facility includes a lot of equipment needed for steam and aerosol generation, and for measuring the thermal-hydraulic parameters as well as the aerosols concentrations.
The inlet and outlet chamber aerosol mass concentration is monitored with Tapered Element Oscillating Microbalance (TEOM) on-line mass monitor and the particle size distribution is measured on-line with the Electrical Low Pressure Impactor (ELPI). Aerosol sampling system includes heated sampling lines, two diluters (first diluter in system pressure is computer controlled and uses heated dilution air), pressure reducer and sampling valves. It is possible to change sampling point between inlet and outlet chambers.
Facility is dismanteled.