Unit 1
Technical Specifications Section 3.3.1.1 requires two channels of intermediate range nuclear instrumentation in Mode 2 to provide the input to the P-6 interlock. This interlock allows the operator to block the source range channels during a reactor startup. This is done to prevent damage to the detectors as power is elevated to levels that could damage the detector. Contrary to the above, between March 11 and March 27, the P6 interlock was
inoperable due to a non-conservative bias, concurrent with Unit 1 being in Mode 2 on March 14 from 0558 to 1010. This problem was entered into the licensees corrective action program as CR 1005422. The finding was screened using
Inspection Manual Chapter 0609, Appendix A, The
Significance Determination Process for Findings At-Power, and was determined to be of very low safety significance (Green).
