TS 5.4.1.a requires that written procedures shall be established, implemented, and maintained as recommended in
Regulatory Guide (RG) 1.33, Rev. 2, Appendix A, February 1978. Section 3.d of
RG 1.33 recommends that appropriate procedures be prepared for energizing, filling, venting, draining, startup, shutdown, and changing modes of operation for the
ECCS. Contrary to the above, the licensee failed to develop an adequate procedure to fill and vent the Unit 2 NV system following system draining and
argon gas introduction associated with NV 2A mixed bed demineralizer valve modification work conducted December 1-12, 2013. On December 14, 2013, following this modification work, a large gas void was identified in the
ECCS piping at high point vent valve
2NV-1056, located in the suction of the
ECCS pumps during design basis accident conditions involving cold-leg recirculation. The licensee determined that the use of an inadequate fill and vent procedure during the system restoration from the modification work resulted in the accumulation of a significant amount of the gas at this location. This violation was determined to be of very low safety significance (Green) because the licensee provided reasonable evidence that the
ECCS pumps would have been capable of performing their intended safety function had the gas void been ingested into the suction of the pumps. This violation was documented in the licensees
CAP as
PIP M-13-11181.
