10 CFR Part 50 Appendix B, Criterion XII, Control of Measuring and Test Equipment, requires that instruments used in activities affecting quality are properly calibrated to maintain accuracy within necessary limits. Contrary to this, on January 10, 2007, the licensee used a degraded traversing in-core (
TIP), Probe A, to calibrate associated
LPRM detectors resulting in 16 local power range monitors being improperly calibrated. As a result, there was a reduction in the calculated margin to the core operating limits of one percent. An analysis of the condition concluded that at least five percent margin was maintained to the core operating limits during this period.
TIP A was repaired and recalibrated on January 18, 2007, and the affected
LPRM detectors were recalibrated on January 20, 2007. This finding is of very low safety significance because it only affected the fuel barrier. This condition was entered into the licensees
CAP as
CR-RBS-2007-0208 