ML16285A334
| ML16285A334 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 10/12/2016 |
| From: | Mary Anderson NRC/NRR/DIRS/IPAB |
| To: | |
| Anderson M,NRR/DIRS,301-415-8744 | |
| References | |
| Download: ML16285A334 (4) | |
Text
Prairie Island Power Change December 2014 Plant: Prairie Island Nuclear Generating Station (PINGP) Unit 1 Date of Event: 12/10/2014 Submittal Date: 06/16/2015 Licensee
Contact:
Bryan Willard Tel/email: 651-267-6829 / Bryan.Willard@xenuclear.com NRC
Contact:
Karla Stoedter Tel/email: 651-388-1121 x4219 Performance Indicator: IE03 - Unplanned Power Changes per 7,000 Critical Hours Site-Specific FAQ (see Appendix D)? No [This is generic.]
FAQ to become effective: When approved Question Section NEI 99-02 Guidance needing interpretation (including page and line citation):
Pg 14 Lines 4-9 The 72-hour period between discovery of an off-normal condition and the corresponding change in power level is based on the typical time to assess the plant condition, and prepare, review, and approve the necessary work orders, procedures, and safety reviews, to effect a repair. The key element to be used in determining whether a power change should be counted as part of this indicator is the 72-hour period and not the extent of the planning that is performed between the discovery of the condition and initiation of the power change.
Pg 15 Lines 36-43 If a condition is identified that is slowly degrading and the licensee prepares plans to reduce power when the condition reaches a predefined limit, and 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> have elapsed since the condition was first identified, the power change does not count. If however, the condition suddenly degrades beyond the predefined limits and requires rapid response, this situation would count. If the licensee has previously identified a slowly degraded off-normal condition but has not prepared plans recognizing the potential need to reduce power when the condition reaches predefined limits, then a sudden degradation of that condition requiring rapid response would constitute a new off-normal condition and therefore, a new time of discovery.
Event or circumstances requiring guidance interpretation:
On December 10, 2014, PINGP Unit 1 commenced a power reduction and initiated a forced outage in response to leakage through the 12 Reactor Coolant Pump (RCP) seal. See the timeline below for a description of the actions taken surrounding this event. Figure 1 shows the unidentified leakage rate during the time period of interest.
o This was found by an increasing trend in Unit 1 Reactor Coolant Drain Tank (RCDT) level rate of change, and a steady increase in pressure in the 12 RCP #3 seal cavity, which suggested that more flow was being diverted to the #3 seal.
Page 1 of 4 Revised 10/20/2015
Prairie Island Power Change December 2014 o An Operational Decision-Making Issue (ODMI) evaluation was requested under this AR on 12/02/2014. The purpose of this ODMI was to establish actions for operators once certain leakage thresholds were exceeded.
- 12/07/2014 0501 - AR 1458595 was initiated to identify that action levels were exceeded for the RCS Leakage Monitoring Program. This was closed to AR 1457811.
- 12/07/2014 0845 - NRC Resident was notified of issues with Unit 1 Reactor Coolant System (RCS) unidentified leakage and pending containment entry to investigate.
- 12/08/2014 1523 - AR 1458727 was initiated to document an increase in Unit 1 RCS unidentified leakage. This was closed to AR 1457811.
- 12/09/2014 - ODMI 1457811 was completed and signed by the Plant Manager.
- 12/10/2014 0901 - A second consecutive performance of the Unit 1 RCS Leakage Test resulted in unidentified leakage greater than 0.8 gallons per minute (GPM). This exceeded a threshold in ODMI 1457811, and it was decided to commence a shutdown of Unit 1 per 1C1.4, Unit 1 Power Operation. Procedure 1C1.4 is the normal operating procedure for Unit 1 above 15%
rated power. When a shutdown is commenced, it is used for load decreases prior to entering 1C1.3, Unit 1 Shutdown.
For clarification, the ODMI process at PINGP serves to assist operations in evaluating certain trends and conditions. ODMI 1457811 was developed during the window between off-normal condition discovery and the corresponding change in power level, in order to assess the plant condition and ensure the safe operation of Unit 1.
The trending throughout this event was focused on unidentified leakage because the maximum allowable unidentified leakage to meet LCO 3.4.14 is 1.0 GPM. The maximum allowable identified leakage to meet LCO 3.4.14 is 10.0 GPM, and this limit was not challenged during this event.
The Unit 1 power reduction was reported as an unplanned power change per NEI 99-02 in the 4th quarter of 2014; however, PINGP is seeking to retract the unplanned power change.
If licensee and NRC resident/region do not agree on the facts and circumstances, explain:
The NRC Resident agrees with the description of the event. However, it is not clear from NEI 99-02 when the off-normal condition was first discovered and whether the licensee adequately prepared plans to reduce power.
Potentially relevant FAQs: None Response Section Proposed Resolution of FAQ:
The point of disagreement between the licensee and NRC inspector is on what constitutes discovery.
PINGP first identified the slowly degrading off-normal condition under AR 1457811 on 11/30/2014. This was ten days before the Unit 1 shutdown commenced. The ODMI was finalized the day before the Page 2 of 4 Revised 10/20/2015
Prairie Island Power Change December 2014 shutdown. While other ARs were written concerning the increased rate of Unit 1 unidentified leakage, AR 1457811 remained the primary CAP entry that tracked key actions in the event troubleshooting process.
This situation did not degrade beyond predefined limits or require rapid response. Throughout the event, the maximum allowable unidentified leakage of 1.0 GPM, as defined in PINGPs Technical Specifications, was not exceeded. The decision to reduce power, aided by guidance in ODMI 1457811, was conservative in nature and provided for a safe transition of the unit to Mode 5. Since normal operating procedures were used to reduce power in Unit 1, a rapid response designated by use of abnormal operating procedure 1C1.4 AOP1, Rapid Power Reduction Unit 1, did not take place.
NEI 99-02 states that the key element to be used in determining whether a power change should be counted as part of this indicator is the 72-hour period and not the extent of planning that is performed between the discovery of the condition and initiation of the power change. The initiation of AR 1457811 on 11/20/2015 identified the apparent degradation to the reactor coolant pump seal and constitutes discovery for the purposes of this indicator. The plant shutdown occurred on 12/10/2015, well in excess of the 72-hour period required prior to the power reduction. Therefore, the power reduction commenced on 12/10/2014 does not count as an Unplanned Power Change per NEI 99-02.
If appropriate, provide proposed rewording of guidance for inclusion in next revision:
Not applicable.
Figure 1 -- Unit 1 RCS Unidentified Leakage during from 12/03/14 through 12/10/14. Each data point was captured while performing SP 1001AA, Daily Reactor Coolant System Leakage Test. The off-normal condition was first discovered on 11/30/14 (AR 1457811) and the ODMI was signed on 12/9/14.
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Prairie Island Power Change December 2014 NRC Response:
The staff reviewed the licensees FAQ and the resident inspectors additional information provided.
While the licensee contends that the off-normal condition was first identified on 11/20, the residents position is that the licensee was unaware of the severity of the condition until it accelerated and a plant shutdown was required on 12/10. NEI 99-02 states [i]f a condition is identified that is slowly degrading and the licensee prepares plans to reduce power when the condition reaches a predefined limit, and 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> have elapsed since the condition was first identified, the power change does not count. In this case the licensee discovered a possible off-normal condition on 11/20, but failed to adequately identify it as a condition that may require a downpower. However, on 12/2, the licensee identified increased RCS unidentified leakage they determined was most likely related to the previously identified condition and requested an ODMI. While the ODMI was not completed until 12/9, the fact that it was requested on 12/2 is the pertinent requirement (ref. FAQ 99-06). The pertinent portion of NEI 99-02 in this case is the excerpt from page 16, lines 40-43:
If the licensee has previously identified a slowly degraded off-normal condition but has not prepared plans recognizing the potential need to reduce power when the condition reaches predefined limits, then a sudden degradation of that condition requiring rapid response would constitute a new off-normal condition and therefore, a new time of discovery.
In this case, that new time of discovery was on 12/2. As such, it is reasonable to conclude that the licensee determined an off-normal condition that would require a downpower existed on 12/2, well in excess of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from the subsequent downpower that occurred on 12/10. The staff concludes that this shutdown should not count towards the IE03 PI.
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