05000416/LER-2002-001
| Grand Gulf Nuclear Station, Unit 1 | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown |
| 4162002001R00 - NRC Website | |
A. REPORTABLE OCCURRENCE
None. This LER is voluntary to provide the NRC follow-up information to the NOED granted to extend the LCO time for the Division 2 Diesel Generator (DG) [EK].
B. INITIAL CONDITIONS
At the time of the event, the reactor was in OPERATIONAL CONDITION 1 with reactor power at approximately 100 percent. Reactor temperature, reactor pressure vessel (RPV) pressure and RPV water level were at approximately 540 degrees F, 1012 PSIG and 36 inches, respectively. Planned maintenance was being performed on the Division 2 DG.
C. DESCRIPTION OF OCCURRENCE
The Division 2 DG was declared inoperable on March 26, 2002 at 0402 for planned maintenance. During the planned maintenance, various problems occurred such as infant mortality failures of some process sensors that caused the DG to remain inoperable. The total sum of the infant mortality switch failure, equipment tagging and re-tagging issues, and limited contingency planning resulted in a planned outage time of 46 hours5.324074e-4 days <br />0.0128 hours <br />7.60582e-5 weeks <br />1.7503e-5 months <br /> extending into excess of the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed outage limiting condition for operation (LCO).
Several conversations took place between the licensee and the NRC on March 28th and preparations were made for Grand Gulf to request a Notice of Enforcement Discretion (NOED) to extend the LCO time by 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to allow for repair and testing of the diesel generator as a result of the jacket water temperature switch failures. The NOED was granted by the NRC at 0030 on March 29th and was invoked at 0402 on March 29th. The NOED was utilized to prevent commencement of a TS-required shutdown. The Division 2 DG was declared operable at 1336 on March 29th.
While this event is not reportable, a voluntary LER is being written to provide the NRC additional followup information. According to NRC Regulatory Issue Summary 2001-20, even if a NOED is issued to a licensee, if an LER is required by 10CFR50.73 as a result of a non-conformance, then the LER must be submitted. In GGNS' situation, the NOED was granted, but the DIV 2 DG was restored to operable status in time to prevent a reportable condition under 10CFR50.73.
According to 10CFR50.73(a)(2)(i)(A), "The completion of any nuclear plant shutdown required by the plant's Technical Specifications;" requires an LER if the shutdown is completed. While the NOED granted a 72- hour extension to the LCO, we considered reportability under 10CFR50.73(a)(2)(i)(A) as if we had not received the NOED. NUREG 1022 states, "For 50.73 reporting purposes, the phrase 'completion of any nuclear plant shutdown' is defined as the point in time during a TS required shutdown when the plant enters the first shutdown condition required by an LCO. An LER is not required if a failure was or could have been corrected before a plant has completed shutdown and no other criteria in 50.73 apply.
In this situation the DIV 2 DG was functional at 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br /> and was declared operable at 1336 (about 2 1/2 hours before having to reach plant shutdown). Therefore, we believe the plant, even without the NOED, would not have been required to complete shutdown before the problem was corrected and the DG returned to operable status.
D. APPARENT CAUSE
A Root Cause Determination was performed to determine the contributing factors for exceeding the 72-hour TS Limit. The root cause was determined to be inadequately defined job performance standards. Some examples of this were:
- No guidelines exist to define the content and major points to be considered during pre-system outage meetings. Limited contingency planning was involved in the pre-outage meetings for the DG outage.
Guidelines would ensure key areas were addressed instead of relying on 'Tribal Knowledge'.
- Tagging and re-tagging of equipment consumed hours that were critical to meeting the 72-hour LCO time limit. The emergent tagging activities were performed in conjunction with on-going daily plant activities.
(No one was dedicated to the diesel tagging activities.)
- The information concerning the reliability issue with the pneumatic temperature switch was known to a few key individuals, but not known by other key personnel involved in the outage. This affected the degree of contingency planning that was done.
E. CORRECTIVE ACTIONS
Immediate Action: The Division 2 Diesel Generator was repaired and returned to operable status.
Long Term Actions: A Condition Report, CR-GGN-2002-00555, was written to address exceeding the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> TS Limit. A root cause determination was performed as one of the corrective actions of the CR.
This root cause identified additional corrective actions that will address the enhancement of planning and scheduling of system outages.
F. SAFETY ASSESSMENT
This is a voluntary LER to provide follow-up information related to the NOED granted to Grand Gulf on March 29, 2002. The DG inoperable status did not exist for longer than allowed by TS (72-hour LCO allowed outage time and the shutdown action statement of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />); therefore, there was no safety significance to this event. In fact the granting of the NOED by the NRC avoided any additional risk associated with the forced reactor power reduction and power ascension that would have been required without the NOED.
G. ADDITIONAL INFORMATION
None