On December 4, 2008, during a walkdown of the Unit 1 and Unit 2
emergency diesel generator (
EDG) system, the inspector identified that the vent lines associated with the
EDG fuel oil storage tanks appeared to lack
tornado missile protection. The inspector noted that the
updated final safety analysis report (
UFSAR) documented that the day tank vent and fuel oil storage tank vents and fill connections are protected from
tornado missiles due to the construction of the vents using heavy
gauge pipe. The inspector requested the documented technical basis showing that the installed fuel oil storage tank piping could meet the requirements stated in the
UFSAR. The licensee was unable to provide this documentation. The licensee initiated
PIP C-08-7140 and subsequently declared the diesel fuel oil system
operable but degraded, nonconforming and instituted compensatory measures to inspect the system for damage following a severe weather event and establish alternate vent paths as needed. Long term corrective actions have been established by the licensee to install
tornado missile protection, in the form of concrete on the vent lines. Evaluations completed by the licensee also identified that similar vulnerabilities existed on the
EDG fuel oil fill lines, crankcase vent lines, and
lube oil vent lines. Operating experience that had been received from McGuire Nuclear Station in July 2008 that identified similar vulnerabilities, however, this operating experience was evaluated as not applicable due to heavier
gauge piping being in place at Catawba but that no independent verification of the design basis of the installed piping was performed. This issue is unresolved pending further NRC inspection and review. This
URI is designated as
URI 05000413,414/2008006-02, Underground Fuel Oil Storage Tank Vent Missile Protection
