November 6, 2015
Follow-Up of Events and Notices of Enforcement Discretion (71153 - 1 sample) (Closed) LER 05000333/2015-003-00: Roof Maintenance Results in Secondary Containment Vacuum Below Technical Specification Limit
Inspection Scope
On July 20, 2015, while operating at 100 percent power, work commenced to replace the roofing materials (insulation, felt paper, and a mix of asphalt and gravel) above the metal deck of the reactor building roof. Shortly after work started, operators noted that reactor building differential pressure (d/p, measured relative to outside pressure) was degrading. TS 3.6.4.1, “Secondary Containment,” requires, in Mode 1, 2, or 3, that secondary containment be maintained at a vacuum of greater than or equal to 0.25 inch of vacuum water gauge, relative to the outside. Operators placed both trains of the standby gas treatment system in service and isolated normal reactor building ventilation, however, these actions were not successful in preventing d/p from decreasing to less than 0.25 inches of vacuum. This condition placed the plant in a four hour TS action statement to restore secondary containment or be in Mode 3 within 12 hours and Mode 4 in 36 hours. Work on the roof was stopped and efforts were commenced to reseal the roof. These actions were successful and d/p was restored to greater than 0.25 inches of vacuum after a period of 92 minutes. Secondary containment operability was not restored within four hours due to continuing roof restoration work and testing to verify operability, however, it was restored prior to a plant shutdown being required. This represents a self-revealing Green NCV, which is discussed below. This LER is closed.
b. Findings
Introduction. The inspectors identified a self-revealing violation of 10 CFR 50, Appendix B, Criterion V, “Instructions, Procedures, and Drawings,” because FitzPatrick staff failed to provide instructions appropriate to the reactor building roof replacement project. Specifically, inadequate instructions were provided to ensure that roofing material removal would be performed in a slow, deliberate manner, such that its effect on secondary containment could be assessed and operability maintained. As a result, this activity caused secondary containment to be inoperable for a period in excess of its TS allowed outage time.
Description. The reactor building roof replacement project originated due to the need to eliminate leaks, as well as to extend the functionality of the roof to the life of the plant. The EC package that was developed to support the roof replacement, EC 56686, “Reactor Building Roof Replacement - 2015,” concluded that the metal roof decking formed the secondary containment pressure boundary and that the portion of the roof that was to be replaced was not safety-related. Nonetheless, it was recognized that removal of the top materials could uncover degraded portions of the metal roof decking, as well as fastener holes, and thereby challenge secondary containment. As a result, the EC placed a limit of 740 square feet of decking that could be exposed at any one time.
When removal of the existing roofing material commenced on July 20, 2015, workers cleared the first 740 square foot area of roof. At that time, it was not recognized that the decking plates were not overlapped and welded together, but rather had gaps between them which allowed for significantly more air in-leakage than had been anticipated. As a result, workers sealed the anticipated fastener holes and proceeded to clear the next 740 square foot area. At the same time, plant operators were observing secondary containment vacuum degrade. Operators placed both trains of the standby gas treatment system in service and isolated normal reactor building ventilation in an effort to maintain secondary containment. These actions arrested the degradation, but only resulted in holding secondary containment vacuum at 0.15 inches of water gauge. Work on the reactor building roof was stopped and secondary containment was declared
inoperable.
As a corrective action, the new roofing materials were installed to reseal the affected area of the reactor building roof. This was successful in restoring secondary containment vacuum to greater than 0.25 inches water gauge after a period of 92 minutes. After completion of work and satisfactory PMT, operators declared secondary containment operable after a period of five hours and 26 minutes. The issue was entered into the CAP as CR-JAF-2015-03260.
Analysis. The inspectors determined that FitzPatrick staff’s failure to provide appropriate instructions for the reactor building roof replacement project, such that this work resulted in a loss of secondary containment for longer than the TS allowed action time, was a performance deficiency that was within Entergy’s ability to foresee and correct, and should have been prevented. The finding was more than minor because it is associated with the procedure quality attribute of the Barrier Integrity cornerstone and affected the cornerstone objective to provide reasonable assurance that physical design barriers (fuel cladding, RCS, and containment) protect the public from radionuclide releases caused by accidents or events. Specifically, the WO did not provide adequate instruction to ensure that roofing material removal would be performed in slow, deliberate manner, coordinated between operations and maintenance personnel, and allowing adequate time after actions that could impact secondary containment such that their effect on secondary containment could be assessed and operability maintained. As a result, secondary containment was rendered inoperable and remained so for longer than the TS-specified allowed outage time.
In accordance with IMC 0609.04, “Initial Characterization of Findings,” and Exhibit 3 of IMC 0609, Appendix A, “The Significance Determination Process (SDP) for Findings At- Power,” the inspectors determined that this finding was of very low safety significance (Green) because the performance deficiency was not a pressurized thermal shock issue, did not represent an actual open pathway in the physical integrity of the reactor containment, did not involve an actual reduction in function of hydrogen igniters in the reactor containment, and only represented a degradation of the radiological barrier function provided by the reactor building and standby gas treatment system.
The finding had a cross-cutting aspect in the area of Human Performance, Avoid Complacency, because FitzPatrick staff did not adequately plan for the possibility of latent issues and inherent risk associated with the reactor building roof replacement project, such that the commencement of work resulted in a loss of secondary containment [H.12].
Enforcement. 10 CFR 50, Appendix B, Criterion V, “Instructions, Procedures, and Drawings,” states, in part, “Activities affecting quality shall be prescribed by documented instructions, procedures, or drawings, of a type appropriate to the circumstances and shall be accomplished in accordance with these instructions, procedures, or drawings…” Contrary to the above, on July 20, 2015, instructions provided to FitzPatrick maintenance personnel for removal of reactor building roofing material were not of a type appropriate to the circumstances, in that they were inadequate to ensure that roofing material removal would be performed in a slow, deliberate manner, in coordination with Operations department personnel, such that its effect on secondary containment could be assessed and operability maintained. As a result, secondary containment vacuum could not be maintained at or above the TS Surveillance Requirement 3.6.4.1.1 limit of 0.25 inches of vacuum water gauge, and secondary containment remained inoperable for a period in excess of the TS 3.6.4.1.A allowed outage time of four hours. Because this violation was of very low safety significance (Green) and FitzPatrick staff entered this issue into the CAP as CR-JAF-2015-03260, this violation is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy. (NCV 05000333/2015-02, Inadequate Instructions for Reactor Building Roof Replacement Result in Inadvertent Loss of Secondary Containment)