Technical Specification 3.9.2, Refuel Position One-Rod-Out Interlock requires immediately, with the refuel position one rod-out-interlock
inoperable, that 1)
control rod withdrawal be suspended, and 2) actions be initiated to fully insert all insert-able
control rods in core cells containing one or more fuel assemblies. Contrary to this requirement, during
control rod exercise testing on April 20, 2007, the reed switch which fed the one rod-out-interlock was
inoperable for
Control Rod 26-35 and immediate actions were not taken to suspend
control rod withdrawal. Although unrecognized at the time by the operators - because the full core display position indication for
Control Rod 26-35 did not change from green to amber in color, the one-rod-out interlock was not met and thus was
inoperable. After completing testing for
Control Rod 26-35 and while withdrawing the next
control rod (26-31) in the test one notch (Position 02), the operators realized that the color change had not occurred for
Control Rod 26-35. The operators immediately re-inserted
Control Rod 26-31, stopped the test and notified management, and entered the issue into the corrective action program as
CAP 01088836. This finding is of very low safety significance because at no time was more than one
control rod withdrawn.
