Experimental ECCS Sump Strainer Head Loss Testing and the Incorporation of CFD Computed Source Terms for Pressurized Water Reactors

High Energy Line Breaks (HELBs) inside nuclear reactor containment are recognized as challenges to Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) nuclear power plants arising from the collateral damage due to insulation, fireproofing, coatings, and other miscellaneous materials which are shredded and transported during the event. These materials, as well as latent debris (dirt and dust) will be transported towards the containment floor and the recirculation sump screens by flow from both the HELB and the containment spray headers. This debris, if washed towards the recirculation pumps, could potentially impede the performance of the Emergency Core Cooling System (ECCS). To evaluate transport of material towards the sump and the potential for degradation in performance of the ECCS, Computational Fluid Dynamics (CFD) has been used to predict the volume of material transported to the sump screens [1]. This predicted volume is then used in full scale laboratory tests to determine head loss across the screen under design flow rates. The laboratory sump strainer tests employed a flume facility measuring 14 m by 3 m by 1.5 m tall with a 2.5 m by 3 m by 2 m deep pit at one end, which can accommodate multiple full scale strainer modules. Head loss performance of the modules under different insulation debris loading conditions was evaluated. The internal walls of the flume were adjusted to reproduce prototypical average approach flow velocity and velocity gradients such that the transport of insulation debris to the strainer modules was accurately represented. A three-port isokinetic sampling system was integrated into the downstream piping for measuring debris bypass. This paper will cover the sump screen head loss testing methodology, and the associated integration of the computational results for the source terms.© 2009 ASME