Study of Moisture Carryover in Boiling Water Reactors
Open Access
- Author:
- Stumbris, Emily
- Area of Honors:
- Nuclear Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Kostadin Nikolov Ivanov, Thesis Supervisor
Kostadin Nikolov Ivanov, Thesis Supervisor
Arthur Thompson Motta, Thesis Honors Advisor - Keywords:
- moisture carryover
boiling water reactor
bwr
nuclear reactor
core design
core simulation - Abstract:
- One unique characteristic of boiling water reactors (BWRs) is that they utilize one continuous loop of water to cool and moderate the reactor and power the turbine in the form of steam. Nearly all of the water exiting the top of the reactor is supposed to be converted to steam by the heat of fission reactions in the fuel. However, in some BWRs the moisture content of the water exiting the reactor is elevated, a problem known as moisture carryover (MCO). MCO can potentially damage the steam turbine at very high levels, but the more immediate threat posed by MCO is increased dose rates in areas around the steam components due to the carryover of radioactive cobalt-60 from Stellite in-core structures. Since MCO has negative effects to worker health and plant operating costs, effectively mitigating the problem is a current priority of BWR-owning utilities and reactor vendors around the world. This thesis investigates several MCO mitigation strategies using Limerick 2 as the basis for modeling via General Electric’s proprietary 3-D BWR core simulator package PANAC11. The strategies are reducing the core inlet orifice size for the peripheral bundles, changing the loading pattern, reducing the channel thickness for the peripheral bundles, and limiting core flow. The thesis goal is to recommend a MCO reduction strategy to the industry based on the magnitude of mitigation and economic feasibility. The results of this thesis work show that reducing the channel thickness for Ring 8 bundles is the recommended solution to MCO. Core simulation studies for Limerick 2 showed that implementing this change caused a 40-60% increase in Ring 8 exit quality for most of the cycle. This method is also economically feasible, as the cost incurred by the utility if the change is made to fresh reload batches is minimal.