Boiling channels and systems in a BWR (Boiling Water Reactor) may oscillate owing to the dynamic behavior of the liquid-steam mixture used for removing the thermai power. A thermal-hydraulic system may be unstable under particular operating conditions. Two kinds of power oscillation have been observed in BWR cores. One is an in-phase (core-wide) and the other is an out-of-phase (regional) oscillation. Since the first one can make detection more difficult, the latter oscillation is potentially more severe. The problem Is weIl known since the design of the first BWR system. However, to improve the safety systems of these reactors, it is necessary to be able to detect in a reliable way these oscillations from the neutronic signals. The purpose of this work is to characterize these unstable behaviors in a BWR NPP. Within this study, it has been performed a number of perturbation analysis. The coupled codes technique through the use of RELAP5/3.3IPARCS has been used for the simulation of the transients. Validation has been performed against Peach Bottom-2 Low-Flow Stability Test PT3. Three dimensional time domain BWR stability analysis were performed on test point 3 for the core wide oscillation mode. In this transient dynamically complex events take place, i.e., neutron kinetics is coupled with thermal-hydraulics and an in-phase oscillation has been developed. The calculated coupled code results are herein compared against the available experimental data.
Peach Bottom Cycle 2 Stability Analysis using Relap5/Parcs
D'AURIA, FRANCESCO SAVERIO
2004-01-01
Abstract
Boiling channels and systems in a BWR (Boiling Water Reactor) may oscillate owing to the dynamic behavior of the liquid-steam mixture used for removing the thermai power. A thermal-hydraulic system may be unstable under particular operating conditions. Two kinds of power oscillation have been observed in BWR cores. One is an in-phase (core-wide) and the other is an out-of-phase (regional) oscillation. Since the first one can make detection more difficult, the latter oscillation is potentially more severe. The problem Is weIl known since the design of the first BWR system. However, to improve the safety systems of these reactors, it is necessary to be able to detect in a reliable way these oscillations from the neutronic signals. The purpose of this work is to characterize these unstable behaviors in a BWR NPP. Within this study, it has been performed a number of perturbation analysis. The coupled codes technique through the use of RELAP5/3.3IPARCS has been used for the simulation of the transients. Validation has been performed against Peach Bottom-2 Low-Flow Stability Test PT3. Three dimensional time domain BWR stability analysis were performed on test point 3 for the core wide oscillation mode. In this transient dynamically complex events take place, i.e., neutron kinetics is coupled with thermal-hydraulics and an in-phase oscillation has been developed. The calculated coupled code results are herein compared against the available experimental data.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
