ML16285A175
| ML16285A175 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 10/11/2016 |
| From: | Mary Anderson NRC/NRR/DIRS/IPAB |
| To: | |
| Anderson M, NRR/DIRS, 301-415-8744 | |
| References | |
| Download: ML16285A175 (4) | |
Text
FAQ 13-01 Final Turkey Point Unplanned Scrams per 7000 Hours Critical Page 1 Revised 04/29/2013 Plant: Turkey Point Unit 3 Date of Event: March 12, 2013 Submittal Date: March 14, 2013 Licensee
Contact:
Bob Tomonto Tel/email: 305-246-7327 bob.tomonto@fpl.com NRC
Contact:
Tim Hoeg Tel/email: 305-246-6199 tim.hoeg@nrc.gov Performance Indicator: IE01, Unplanned Scrams per 7000 Critical hours Site-Specific FAQ (Appendix D)? YES FAQ requested to become effective when approved.
This FAQ concerns the March 12, 2013 Turkey Point Unit 3 manual reactor trip. This trip was the third in four quarters and because the plant had accrued a low number of critical hours in that time period (approximately 4500), the NRC Performance Indicator IE01 exceeded the Green-White threshold of 3.0. Florida Power & Light (FPL), as licensee for Turkey Point Units 3 and 4, proposes that Performance Indicator IE01 be shown as N/A until Unit 3 has accumulated four full quarters of power operation so that the indicator will be representative of operational performance. The reason for this request is that the site was in a planned extended shutdown during the first three quarters of 2012 (2/26/12 - 9/6/12) to perform upgrades and plant improvements associated with an Extended Power Uprate (EPU). The low number of critical hours was not in any way related to poor operational or regulatory performance.
This request is being submitted as a Plant-Specific FAQ, as discussed in NEI 99-02, Appendix D, which states that the guidance was written to accommodate situations anticipated to arise at a typical nuclear power plant. However, uncommon plant designs or unique conditions may exist that have not been anticipated. In these cases, licensees should first apply the guidance as written to determine the impact on the indicators.
Then, if the licensee believes that there are unique circumstances sufficient to warrant an exception to the guidance as written, the licensee should submit a Frequently Asked Question to NEI for consideration at a public meeting with the NRC.
Question Section NEI 99-02 Guidance needing interpretation (include page and line citation):
- NEI 99-02, Rev 6, Page 10 Lines 25-27.
- NEI 99-02, Rev 6, Page D-1 Lines 16-21.
FAQ 13-01 Final Turkey Point Unplanned Scrams per 7000 Hours Critical Page 2 Revised 04/29/2013 Event or circumstances requiring guidance interpretation:
Between February 26, 2012 and September 6, 2012, Turkey Point Unit 3 was shutdown for extensive plant modifications and improvements required to support operation at increased power levels. The extended EPU shutdown resulted in a very low number of critical hours during the first three quarters of 2012. As a result of scrams during the first quarter of 2013, Unit 3 will end this quarter with NRC PI IE01 value of approximately 4.5, which is indicative of the volatility of the PI when the number of hours of critical operation is significantly below the 7000 hour0.081 days <br />1.944 hours <br />0.0116 weeks <br />0.00266 months <br /> reference value.
NEI 99-02, Revision 6 allows for displaying the IE01 value as N/A when accumulated critical hours are less than 2400. That is intended to prevent a unit from crossing from Green to White, based solely on a single unplanned scram. NEI 99-02, also clearly indicates that the indicator is monitored over four quarters of operation. Further, the Data Example table on page 11, shows no PI values until after four quarters of data are accumulated. In fact, the example in that table shows that greater than 2400 hours0.0278 days <br />0.667 hours <br />0.00397 weeks <br />9.132e-4 months <br /> of critical operation had been accumulated in third quarter of 1997, with one scram, yet no PI value is displayed.
NRC Inspection Manual Chapter (IMC) 0351, Implementation of the Reactor Oversight Process at Reactor Facilities in an Extended Shutdown Condition for Reasons Other Than Significant Performance Problems, acknowledges that even two quarters of operating data following a plant shutdown of longer than six months makes this PI more volatile. NRC IMC 308, Reactor Oversight Process (ROP) Basis Document, Attachment 1, Figure 1 provides the basis for using 7000 hours0.081 days <br />1.944 hours <br />0.0116 weeks <br />0.00266 months <br /> in the denominator is one years worth of critical hours assuming an 80% capacity factor. In addition, Figure 1 also states that the Green to White threshold for PI IE01 was selected to identify outliers from industry norms.
For Turkey Point Unit 3, the White threshold will be crossed because the denominator is below industry norm (7000 hours0.081 days <br />1.944 hours <br />0.0116 weeks <br />0.00266 months <br />) due to the extended EPU outage, not because of the scrams. The unit did not operate for a full four quarters with a normal refueling outage and therefore should not be penalized with a significantly high PI because it is not representative of a reduction in safety margin and Turkey Point Unit 3 is not an outlier from industry norms.
A previously submitted White Paper from the NEI ROP Task Force proposed a similar approach for MSPI data. The basis is that the indicator value is heavily influenced by the number of hours of critical operation. When a plant is shutdown for extended outage (i.e., greater than six months), the indicator may not give results that are representative of the intent of ROP.
Consequently, it has been proposed that MSPI be grayed out for those plants that are shutdown for greater than six months and not be restored until after four quarters of operation have been accumulated.
FAQ 13-01 Final Turkey Point Unplanned Scrams per 7000 Hours Critical Page 3 Revised 04/29/2013 With a greater than six month refuel outage and only a portion of third quarter 2012, fourth quarter 2012 and the first quarter 2013 with potential critical operating hours, the PI will not display representative values for Turkey Point Unit 3 and should be displayed as N/A. The PI will not accurately represent plant operation until the full four quarters of plant operation have been accrued.
Potentially relevant existing FAQ numbers:
There are no potentially relevant FAQs. However, it should be noted that recent discussions with NRC staff regarding applicability of MSPI data that is skewed by extended plant shutdowns indicates that indicators that are tied to reactor critical hours may not be valid for shutdowns exceeding approximately 6 months and should not be actively monitored until four quarters after reactor restart.
Response Section Propose that Turkey Point Unit 3 be granted exemption from the threshold of 3.0 unplanned scrams per 7000 hours0.081 days <br />1.944 hours <br />0.0116 weeks <br />0.00266 months <br /> critical because of the circumstances for the extended plant shutdown resulting in less than four full quarters of operation. The PI should be displayed as N/A on the NRC website until four full quarters of power operation following the extended EPU outage in 2012.
NRC Final Response The Unplanned Scrams indicator is defined as the number of unplanned scrams during the previous four quarters, both manual and automatic, while critical per 7,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />. Current guidance in NEI 99-02 requires this PI to be reported when more than 2,400 critical hours are accumulated in the previous four quarters. The 2,400 critical hours limit is intended to prevent a unit from crossing the Green-White threshold on a single unplanned scram. Turkey Point Unit 3 accumulated 4,745 critical hours and three scrams in the previous four quarters.
The PI is normalized to 7,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> to account for approximately 73 days (80% availability factor) of shutdown time in four quarters. Since the PI is based on critical hours and number of scrams in the previous four quarters, low critical hours (<7,000) will cause a PI threshold to be exceeded with a lower number of scrams. The Green-White threshold was crossed based on a combination of both critical hours and the number of scrams at Turkey Point Unit 3.
The licensee is requesting an exemption for Turkey Point Unit 3 from the threshold of 3.0 unplanned scrams per 7,000 critical hours because of the circumstances for the extended plant shutdown resulting in less than four quarters of operation. The NEI 99-02 guidance was written to accommodate anticipated situations like this at a typical nuclear power plant. Appendix D of NEI 99-02 allows exemptions to be granted if unique conditions exist that have not been anticipated by the licensee. The NRC does not consider less than four quarters of critical
FAQ 13-01 Final Turkey Point Unplanned Scrams per 7000 Hours Critical Page 4 Revised 04/29/2013 operation a unique condition. The NRC staff does not support granting Turkey Point Unit 3 an exemption to the Unplanned Scrams per 7,000 Critical Hours indicators Green-White threshold.
This FAQ is effective immediately (06/28/2013).