| dc.description.abstract | The Reactor Core Isolation Cooling (RCIC) system is found in certain boiling water reactor power plants. The RCIC system is meant to provide coolant to the reactor pressure vessel (RPV) in certain cases when the vessel is isolated from the main steam turbines and condensers. In 2011, the Great East Tohoku earthquake in Japan caused the operation of three reactors at the Fukushima Daiichi nuclear site to be interrupted. The seismic activity initiated the shutdown of the three reactors and the RCIC system came online in the two reactors equipped with a RCIC system.
The RPV must have decay heat removal after shutdown. In the Fukushima Daiichi nuclear accident the RCIC system, it is believed, removed this decay heat from units 2 and 3 for 70 and 20 hours respectively. This greatly exceeds the expected RCIC run time of 4-8 hours, which is why the RCIC system has drawn great amounts of attention since the accidents. Experimental demonstration of this extended operation of the RCIC system shows that the system could be more capable of providing cooling than previously thought. As this performance in practice is far greater than the anticipated operation duration, the RCIC system merits increased study into its performance, specifically, in beyond design accidents and station blackout conditions.
A Computational Multiphase Fluid Dynamics (CMFD) simulation was developed herein for implementation in STAR-CCM+. This simulation studied the RCIC pump performance and degradation due to changes in turbine performance and heat up of the Suppression Pool. As the RCIC pump and turbine are physically on the same shaft, the turbine’s performance has direct implications on the performance of the pump. One of the pump suction sources is the Suppression Pool, so a heat up of the Suppression pool could introduce two-phase flow at the pump inlet. A centrifugal pump similar to those used in RCIC Systems was created in the CMFD model to explore the pump performance as it is affected by Gas Void Fraction, and impeller rotational speed.
The goal of this thesis is to develop, implement, and apply detailed mathematical models of the RCIC system pump so its performance in beyond design accident and station blackout conditions can be better understood | en |
