Effect of Core Size on Rod Worth During a Control Rod Drop Accident
Open Access
- Author:
- Mcclure, Kelly Ralston
- Area of Honors:
- Nuclear Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Kostadin Nikolov Ivanov, Thesis Supervisor
Seungjin Kim, Thesis Honors Advisor - Keywords:
- nuclear
control rod
BWR - Abstract:
- A control rod drop accident (CRDA) is a reactivity-initiated transient event analyzed by engineers for boiling water reactors (BWRs). During a CRDA, a control rod drops from the core at a high speed, causing a reactivity spike and risking damage to the fuel and cladding. Engineers must prove that a reactor’s core design will remain safe in the event of such an accident. Thus, to gain a full understanding of the effect and severity of a CRDA, it is beneficial to explore the effect of reactor core size on the transient results. Beginning with the largest available BWR reactor core, five common BWR core sizes were created and a CRDA was simulated at each size. The initial core re-sizing methodology was developed at GE Hitachi Nuclear Energy, then the process was repeated and the CRDA simulation was performed at Penn State. The goal of the core reduction process was to create core that could be considered “similar” for the CRDA analysis, as defined by adherence to a ±0.005 eigenvalue limit between the calculated and expected leakage-adjusted values. A CRDA was simulated in the five core sizes to compare the severity of the transient event – as defined by the rod worth of a particular rod of interest. The accident simulation indicated that the rod worth, and thus fuel enthalpy increase, decreases as the core size increases. The same trend was found when comparing power peaking factor (FQ) in the various core sizes. These results suggest that smaller cores yield a more limiting control rod drop accident.