1) Surry uses IFBA fuel. Core modeling is performed using the CASMO-4/SIMULATE-3 computer codes. In making comparisons between measured and predicted boron concentrations (corrected for B-10, power, xenon, rod position, and RCS temperature), we notice a tendency to for the core models to underpredict the measured critical boron between 2 and 4 GWD/MTU by 10-20 ppm (about 80-160 pcm) more than at other times in life (such as at BOC equilibrium xenon or between MOC and EOC). Have you observed this tendency at your plant?
2) For the monthly reactivity anomaly calculation, is a B-10 corrected value used to meet Tech Spec requirements, or is the non-corrected value used? (Surry uses the non-corrected value)
3) Does your anomaly procedure have a threshold (such as +/-500 pcm) at which the anomaly would be documented in the corrective action system?
Adina LaFrance
It's a healthy thing now and then to hang a question mark on the things you have long taken for granted. -Betrand Russell
Nuclear Analysis & Fuel Reactor Engineer Surry Power Station Email: Adina.K.LaFrance@Dom.com Phone: 757-365-2658 Pager #: 4290
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