ML18312A217
| ML18312A217 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 11/20/2017 |
| From: | Joylynn Quinones-Navarro NRC/NRR/DIRS/IRAB |
| To: | |
| Quinones-Navarro J,NRR/DIRS,404-997-4469 | |
| References | |
| FAQ 18-05 | |
| Download: ML18312A217 (5) | |
Text
FAQ 18-05 Turkey Point Unit 3 Shutdown - Proposed NRC Response Plant: Turkey Point Unit 3 Date of Event: November 20, 2017 Submittal Date:
Licensee
Contact:
Bob Hess Tel/email: 305-246-4112 Robert.hess@fpl.com NRC
Contact:
Joylynn Quinones- Navarro Tel/email: 404-997-4469 joylynn.quinones-navarro@nrc.gov Performance Indicator: IE03 Unplanned Power Changes per 7,000 Critical Hours Site-Specific FAQ (see Appendix D)? (__)Yes or (XX) No FAQ to become effective (XX) when approved or (other date)
Question Section NEI 99-02 Guidance needing interpretation (include page and line citation):
Page 14 - Unplanned power change definition:
The number of unplanned changes in reactor power of greater than 20% of full-power, per 7,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of critical operation excluding manual and automatic scrams.
Unplanned changes in reactor power, for the purposes of this indicator, is a change in reactor power that:
(1) was initiated less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following the discovery of an off- normal condition that required or resulted in a power change, of greater than 20% of full power to resolve, and (2) has not been excluded from counting per the guidance below. Unplanned changes in reactor power also include uncontrolled excursions of greater than 20% of full power that occur in response to changes in reactor or plant conditions and are not an expected part of a planned evolution or test.
Page 15 - Examples of occurrences that would be counted against this indicator include:
- Power reductions that exceed 20% of full power and are not part of a planned and documented evolution or test. Such power changes may include those conducted in response to equipment failures or personnel errors or those conducted to perform maintenance.
- Power reductions due to equipment failures that are under the control of the nuclear unit are included in this indicator.
Event or circumstances requiring guidance interpretation:
On November 20, 2017, with Turkey Point Unit 3 operating at 100% power, control room operators noted a reduction in Reactor Coolant Pump (RCP)Seal Flow. The plant procedure, 3-ONOP-041.1 Reactor Coolant Pump Off-Normal, directs shutdown of the unit following General Operating Procedure 3-GOP-100 Fast Load Reduction fast power reduction section. The intent is to protect the equipment and shut down the reactor so that repairs can be made. It should be noted that the procedure directs immediate trip of the reactor if RCP
temperatures exceed acceptable limits. However, since RCP temperatures remained within those limits, plant operators commenced Unit 3 shutdown using a normal shutdown procedure.
Timeline:
0323 Control Room alarm on RCP Controlled Bleed Off (CBO) high temperature and entered procedure 3-ONOP-041.1 for RCP off-normal condition 0738 Control Room alarm for RCP Trouble, 3C RCP CBO flow changed from 2.4 gpm to 0. For that condition, 3-ONOP-041.1 directs operations to commence unit shutdown using (normal plant shutdown procedure) 3-GOP-100, Fast Load Reduction section.
0742 Operations briefed the plan to shutdown the reactor and entered the procedure 3-GOP-100.
0844 Control Room Operators completed a power reduction using 3-GOP-100 and then inserted a manual scram at 18% power.
Unit 3 was shutdown in accordance with plant procedure for equipment protection. Since the unit was initially at 100% power and the shutdown exceeded a 20% power change, the power change was appropriately counted against the Unplanned Power Changes per 7000 Hrs Critical Performance Indicator (IE02).
If licensee and NRC resident/region do not agree on the facts and circumstances, explain:
NRC Resident Inspector does not agree with the licensee. The Resident Inspector believes the licensee did not fully address the applicable item in NEI 99-02. Specifically, while the scram occurred at less than 35% power level and was inserted using normal operating procedures, the licensee did not address whether this was a planned shutdown. The plant was shut down following the rapid load reduction procedure, 3-GOP-100 and the procedure used for normal planned shutdowns is 3-GOP-103. Because the licensee did not use the normal method of implementing a planned shutdown, the occurrence should count in the unplanned scrams performance indicator.
Potentially relevant FAQs:
Perry FAQ 440 Date of Event: June 2007 Entered : 3/19/2008 Response Section Proposed Resolution of FAQ:
Turkey Point Unit 3 shutdown should count against the Unplanned Power Changes Performance Indicator. It was a planned shutdown to address an equipment issue which utilized a normal shutdown procedure. The equipment required a plant shutdown to repair and would not allow for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for planning. The operating procedure directed Operators to commence shutdown in order to be able to remove the RCP from service. The condition did not warrant insertion of an immediate (unplanned) plant scram and so should be counted as an
Unplanned Power Change, as operators were given the time necessary to conduct an orderly reactor shutdown. The scram was inserted at 18% power, well below the 35% threshold.
The Unplanned Power Changes and Unplanned Scrams Performance Indicators are included in the set of Initiating Events and are both intended to provide indication of off normal conditions that can present challenges to plant operators. However, the distinction is that Unplanned Power Changes monitors the number of unplanned power changes (excluding scrams) that could have, under other plant conditions, challenged safety functions. By contrast, Unplanned Scrams measures the rate of scrams per year of operation at power and provides an indication of initiating event frequency.
The definition of Unplanned Scram implies a plant transient or other condition necessitating immediate trip of the reactor (manual scram in anticipation of automatic scram). The exceptions make it clear that a condition that allows time for operators to take deliberate action to reduce power and then manually manual trip the reactor, should not be counted against the Indicator.
This conclusion is further confirmed in the examples of scrams to be included (page 10 of NEI 99-02, rev 7, lines 38-41) and the examples of scrams that are not included (page 11 of NEI 99-02, rev 7, lines 12-14).
NRC inspection Manual Chapter (IMC) 308, contains additional information that helps to inform the understanding of the Unplanned Scrams PI. Page 14 of Attachment 1 states Some industry representatives indicated that including manual scrams in the current scram PIs could result in non-conservative decision-making by operators during a plant event for which a manual scram is warranted. From this quote, it is clear that the PI was expanded to capture manual scrams that are initiated to preclude and automatic scram. Since the Turkey Point Unit 3 shutdown was neither automatic, nor to avoid an automatic trip, it should not be counted in the Unplanned Scrams PI.
Turkey Point reduced power in accordance with their general operating procedure and shutdown Unit 3 at 18% power and within less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from the initial indication of equipment issue. Thus the shutdown was counted in the Unplanned Power Changes per 7000 hours0.081 days <br />1.944 hours <br />0.0116 weeks <br />0.00266 months <br /> Critical PI.
If appropriate, provide proposed rewording of guidance for inclusion in next revision:
N/A PRA update required to implement this FAQ?
No MSPI Basis Document update required to implement this FAQ?
No Proposed NRC Response:
The NRC staff reviewed the information provided in this FAQ and the details of the November 20, 2017, event at Turkey Point. Turkey Point Unit 3 was operating at 100% power, when control room operators received an alarm for reactor coolant pump (RCP) control bleed-off (CBO) high temperature at 0323 and operators entered 3-ONOP-041.1, RCP Off Normal. At 0738 operators received an RCP trouble alarm when the 3C RCP CBO step changed from 2.4 gpm to 0.0 gpm. At this point, step 20 of 3-ONOP-041.1 directed operators to perform a unit
shutdown per General Operating Procedure (GOP) 3-GOP-100, Fast Load Reduction. In accordance with step 26 of the GOP, at 0742 operators commenced a rapid load reduction to roughly 18% power then manually tripped the reactor at 0844.
The licensee stated in FAQ 18-05 that Unit 3 was shutdown in accordance with plant procedure for equipment protection. Since the unit was initially at 100% power and the shutdown exceeded a 20% power change, the power change was appropriately counted against the Unplanned Power Changes per 7000 Hrs Critical Performance Indicator (IE02).
The licensee also provided the following points to support their conclusion:
- 1. This was a planned shutdown to address an equipment issue which utilized a normal shutdown procedure.
- 2. The equipment required a plant shutdown to repair and would not allow for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for planning and the operating procedure directed operators to commence shutdown in order to be able to remove the RCP from service.
- 3. The condition did not warrant insertion of an immediate (unplanned) plant scram and so should be counted as an Unplanned Power Changes, as operators were given the time necessary to conduct an orderly Rx shutdown.
- 4. The scram was inserted at 18% power, well below the 35% threshold.
The NRC staff reviewed in detail the applicable guidance in NEI 99-02, Revision 7, and potentially applicable previous FAQ decisions. Because this event involved a downpower that led to a plant shutdown, the inspectors reviewed the NEI guidance for both the unplanned scrams and unplanned downpowers performance indicators. The staff noted that this event meets the definition of an unplanned power change, which is defined in NEI 99-02, Revision 7 as:
a change in reactor power that (1) was initiated less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following the discovery of an off-normal condition that required or resulted in a power change of greater than 20% of full power to resolve, and (2) has not been excluded from counting per the guidance below. Unplanned changes in reactor power also include uncontrolled excursions of greater than 20% of full power that occur in response to changes in reactor or plant conditions and are not an expected part of a planned evolution or test.
The inspectors reviewed the Clarifying Notes for the unplanned downpower performance indicator. The guidance states on page 17, lines 1-2, that off-normal conditions that begin with one or more power reductions and end with an unplanned reactor trip are counted in the unplanned reactor scram indicator only. However, if the cause of the downpower(s) and the scram are different, an unplanned power change and an unplanned scram must both be counted. In this case, both the downpower and reactor trip were a result of the RCP CBO equipment issue, thus it is clear that the event would count as an unplanned downpower or an unplanned scram, but not both.
The staff reviewed FAQ 17-02, Palo Verde Unit 3 Scram, which dealt with this same question.
The event in question was described in FAQ 17-02 as:
On September 19, 2016, the Palo Verde Nuclear Generating Station (PVNGS) Unit 3 main turbine tripped from 100% power resulting in an automatic reactor power cutback, which reduced power greater than 20%. The reactor power cutback system automatically reduced unit power to approximately 50%, and operators subsequently initiated a power
reduction to 12% power in accordance with the load rejection abnormal operating procedure. During the power reduction to 12%, PVNGS management elected to complete a reactor shutdown to troubleshoot and repair the cause of the turbine trip, which was not known. PVNGS counted this event as an unplanned scram because the staff was using an abnormal operating procedure to direct plant actions.
The NRC response for that FAQ stated that the initial downpower was caused by an unknown fault on the turbine control system and the decision to trip the reactor was predicated by that initial event. The FAQ response concluded that, This event should count as one unplanned scram and no unplanned power changes. The inspectors determined that FAQ 17-02 is applicable to this FAQ. The guidance in NEI 99-02, Revision 7, and the NRC response to FAQ 17-02 lead to the conclusion that this event should count in the unplanned scrams performance indicator only.
The staff also reviewed FAQ 440 since the licensee identified that FAQ as potentially applicable.
FAQ 440 stated that if the licensee does not follow its normal method of shutting down the plant due to problems that challenge plant operations, the scram should be included in the unplanned scram performance indicator. In the Turkey Point event that is the source of this FAQ, the operators entered the applicable ONOP, which directed a unit shutdown via fast power reduction per 3-GOP-100. Based on reviewing operations logs from a recent refueling outage, the staff believes the procedure the licensee uses for normal planned shutdowns is 3-GOP-103, Power Operation to Hot Standby. The staffs review of FAQ 440 also leads to the conclusion that the event in question should count as an unplanned scram.
The staff elected to also review NEI 99-02 guidance on the definition of an unplanned scram.
An unplanned scram means that the scram was not an intentional part of a planned evolution or test as directed by a normal operating or test procedure. This includes scrams that occurred during the execution of procedures or evolutions in which there was a high chance of a scram occurring but the scram was neither planned nor intended. Also, one of the examples in NEI 99-02, Revision 7 (page 11, lines 38-39) for scrams that are included in the unplanned scrams indicator are the scrams that resulted from unplanned transients, equipment failures, spurious signals, human error, or those directed by an abnormal, emergency, or annunciator procedures. In this case, the execution of a rapid plant shutdown and scram was directed by an off-normal procedure in response to an unexpected equipment condition with RCP CBO.
Actual execution of the shutdown and scram was performed in a manner different than that used for ordinary planned shutdowns.
Based on the staffs review of information provided in this FAQ, NEI 99-02 guidance, and applicable prior FAQs, the NRC staff concludes that the unplanned rapid plant shutdown due to the off-normal 3C RCP condition counts in the Unplanned Scrams per 7,000 Critical Hours performance indicator since (1) the off-normal condition began with one or more power reductions and ended with a reactor trip and (2) the plant shutdown was directed by an off-normal procedure, and (3) the shutdown was not conducted in the same manner using the same procedure in which the licensee conducts planned shutdowns. This event does not count in the unplanned power changes performance indicator. No change to NEI 99-02 is required as a result of this FAQ.