ML16285A318

ROP PI Frequently Asked Questions (Faqs): 13-02

ML16285A318
Person / Time
Site:	Susquehanna
Issue date:	06/14/2013
From:	Mary Anderson, Patrick Finney NRC/NRR/DIRS/IPAB, Division Reactor Projects I
To:
Anderson M,NRR/DIRS,301-415-8744
References
Download: ML16285A318 (8)

Text

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change Plant: Susquehanna Date of Event: June 11, 2012 Submittal Date: June 14, 2013 Licensee

Contact:

John Tripoli Tel/email: 570-542-3100/jltripoli@pplweb.com NRC

Contact:

Patrick Finney_______ Tel/email: (570)542-3189 patrick.finney@nrc.gov Performance Indicator: IE03 Site-Specific FAQ (Appendix D)? Yes FAQ requested to become effective when approved Question Section:

During a planned power reduction of greater than 20% to support a scheduled control rod pattern adjustment, Susquehanna Unit 1 operators encountered a potential equipment problem. To expedite investigation of the plant equipment issue, the operators chose to manually initiate a reactor recirculation system runback which reduced power to the target power level more rapidly than originally projected. Following the runback, and resolution of the potential equipment problem, the planned rod pattern adjustment activities were performed at the target power level within the planned time frame. Power ascension proceeded as planned. Should this rapid power reduction within the planned power reduction scope be counted as an unplanned power change per 7000 critical hours?

Event or circumstances requiring guidance interpretation:

Following the Susquehanna Unit 1 Refueling Outage completed on 6/7/12, during power ascension, on 06/11/12, a planned power reduction from approximately 90% (initial) to approximately 65% (final) was scheduled to perform a rod pattern adjustment evolution. The plan was established greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> prior to the actual power reduction.

After, the planned power reduction began at approximately 85% power, plant operators initiated a manual reactor recirculation runback at approximately 84% power to limiter #2 in order to reduce condenser area radiation levels. The runback was necessary to rapidly decrease radiation levels to allow entry into the condenser area to locate the source of water identified on an area camera in the condenser area.

The condenser area water issue was identified and remedied within 15 minutes of entry. The cause was a condenser area sump drain valve.

The planned rod pattern adjustment continued and was completed within the planned time frame of approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> from the initial power reduction to completion of the rod pattern adjustment. At that time the ramp up from 70% power began.

PPL did not classify this as an unplanned power change because the planned rod pattern adjustment continued and was completed within the planned time frame. The condenser water Page 1 of 8 Revised 10/21/2013 Page 2 of 23 in FAQ Package

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change issue was investigated and resolved within the planned time frame of the rod pattern adjustment and at the same power level as the planned evolution. The rod pattern adjustment (planned activity) was successfully performed at the planned power level with no delay.

The question is whether or not interrupting the rod pattern adjustment and initiating a reactor recirculation system runback should count as an Unplanned Power Change per 7000 critical Hours under NRC IMC 0305 Operating Reactor Assessment Program and the guidance in NEI 99-02 Regulatory Assessment Performance Indicator Guideline Revision 6.

NEI 99-02, Rev.6, page 13, lines 3 through 6, contain the following Purpose statement for this indicator:

This indicator monitors the number of unplanned power changes (excluding scrams) that could have, under other plant conditions, challenged safety functions. It may provide leading indication of risk-significant events but is not itself risk-significant. The indicator measures the number of plant power changes for a typical year of operation at power.

Further, NEI 99-02, Rev.6, page 14, lines 10 through 14 state:

Equipment problems encountered during a planned power reduction greater than 20% that alone may have required a power reduction of 20% or more to repair are not counted as part of this indicator if they are repaired during the planned power reduction. However, if during the implementation of a planned power reduction, power is reduced by more than 20% of full power beyond the planned reduction, then an unplanned power change has occurred.

Susquehanna Unit 1 was in the process of reducing power on 6/11/2013, at 21:35, for a planned rod pattern adjustment. See the load profile below for a comparison of the predicted power Page 2 of 8 Revised 10/21/2013 Page 3 of 23 in FAQ Package

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change changes in blue and the actual power changes in red.

U1C18 BOC Startup Load Profile NOTE: Minor Rod Pattern Adjustments are planned DURING NOTE: At Reduced Power, Power Core Flow Cal and Hi-Speed Stops will be the Recirc Flow RAMP with a negligible impact to the Power levels are +/ - 2% RTP scheduled after Unit 2 reaches rated power Ascension Schedule 100 90 Perform RPA Unit 1 SHUTDOWN due to LPRM Cal and Rod Pattern unidentified leak inside Adjustment at 75% RTP Minor RPA 80 PSS Testing Perform RPA LOWERing Reactor TP -164 -037 #2 Limiter Power to ~65% RTP Checks at ~62% RTP 70 Perform RPA LOWERing Reactor Power to ~65% RTP 60 FDWTR/ICS Testing and Reactor Engineering: J. Mirilovich / I., Francis multiple Rod Pattern 50 Adjustments at 65% RTP Work Request # : ______________________

- Activities Planned & Scheduled 40 - Resources Reviewed

- Marketing Notified

- Risk Evaluated 30 Rated Therm al Po wer (% RTP)

Manager - Work Mgmt: _______________________

LPRM Cal, FDWTR/ICS Testing, Scram Time Testing and multiple Rod Pattern Adjustments at ~38% RTP Reactivity Manipulations Reviewed:

20 Manager - Nuclear Ops: _______________________

Approval to Perform:

10 Plant Manager: _______________________

Breaker Closure 0

Time PPL Susquehanna concluded that this was not an unplanned power change because:

The power reduction was greater than 20% and was planned greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in advance of the rod pattern adjustment. The planned reduction was from approximately 90% power to approximately 65% power.

Shortly after commencing the planned power reduction, in response to a Condenser Area Transfer Sump High Level alarm, plant operators initiated a manual reactor recirculation pump runback to limiter 2. The runback started at approximately 84% power and ended at approximately 62% power.

The emergent condenser area issue was resolved quickly and operators completed the planned rod pattern adjustment. Although the planned evolution was briefly delayed it was completed. If the planned evolution had been canceled (not just briefly delayed) because of the emergent condition, this would be considered an unplanned power change.

The guidance from NEI 99-02, Rev. 6 page 14 discussed above provides the reasoning for this to not be an unplanned power change. Although the power change was greater than 20%, it was resolved during the planned power reduction window and the emergent issue did not require power to be reduced by more than 20% beyond the planned power reduction.

Therefore, an unplanned power change did not occur.

Page 3 of 8 Revised 10/21/2013 Page 4 of 23 in FAQ Package

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change Additional considerations:

The power reduction to perform the rod pattern adjustment was a planned evolution with additional personnel supporting the normal shift compliment. Consistent with the purpose of this indicator, no challenge to safety systems occurred. Shift personnel were ready for a power reduction, a potentially significant problem arose, shift personnel took conservative action to place the plant in a status where nuclear and radiological safety was maximized, and the potentially significant problem was addressed in a matter of minutes rather than a potentially longer period of time with higher radiation exposure.

If licensee and NRC resident/ region do not agree on the facts and circumstances explain:

The following NRC Resident Inspector Position (with concurrence from RI/DRP/PB4) position was provided:

A) The inspectors considered the following NEI 99-02, Regulatory Assessment Performance Indicator Guideline, Revision 6, guidance deemed pertinent to this discussion:

1) Page 13, Lines 9-10: The purpose of IE03 is to monitor the number of unplanned power changes (excluding scrams) that could have, under other plant conditions, challenged safety functions.

2) Page 13, Lines 25-29: The term Unplanned changes in reactor power is defined as changes in reactor power that are 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, and that result in, or require a change in power level of greater than 20% of full power to resolve. 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.

3) Page 14, Lines 10-14: Equipment problems encountered during a planned power reduction greater than 20% that alone may have required a power reduction of 20% or more to repair are not counted as part of this indicator if they are repaired during the planned power reduction. However, if during the implementation of a planned power reduction, power is reduced by more than 20% of full power beyond the planned reduction, then an unplanned power change has occurred.

4) Page 14, Lines 16-18: Unplanned power changes and shutdowns include those conducted in response to equipment failures or personnel errors and those conducted to perform maintenance. They do not include automatic or manual scrams or load-follow power changes.

5) Page 14, Lines 23-24: Unplanned power changes include runbacks and power oscillations greater than 20% of full power.

Page 4 of 8 Revised 10/21/2013 Page 5 of 23 in FAQ Package

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change

6) Page 16, Line 14: Downpowers of greater than 20% of full power for ALARA reasons are counted in the indicator.

B) The inspectors considered the following information from PPL sources pertinent to this discussion:

Upon receipt of the sump alarm, the Operators used the Alarm Response Procedure, AR-125-001, Reactor and Turbine Bldg Miscellaneous Sumps Panel 1C692, Revision 8, according to operator logs. The procedure directs operators to determine source of excessive inleakage and isolate as necessary and if excessive leakage is evident, perform ON-169-001. The following Off Normal Procedures were entered: ON-169-001, Flooding in the Turbine Building, ON-164-002, Loss of Reactor Recirculation Flow, and ON-178-002, Core Flux Oscillations. Operator logs on 6/11/12 at 2148 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.17314e-4 months <br /> stated Initiated Recirc Pump Runback to Limiter #2 in order to lower power to reduce Condenser Area Radiation Levels in support of a pending Condenser Area investigatory entry. The runback was reset at 2316 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.81238e-4 months <br />. Reactor power at that time was approximately 62 percent. PPLs investigation into the event determined this was a mispositioning event based on a valve found in the closed position.

Reactor Engineering staff were present for the control rod pattern adjustment evolution. Their Reactivity Manipulation Request was annotated with the comments condenser area transfer sump Hi alarm. Downpower to ~60% by unplanned power reduction (emphasis added) form OP-AA-338-5. OP-AD-338-5 is the Controlled Shutdown/Unplanned Power Reduction form and has two means of entry: a controlled shutdown is required or an unplanned power reduction to below the reactor power maneuvering envelope. The copy used was annotated that a Transient was in progress and that a core flow reduction was required to mitigate the transient.

C) The inspectors questioned PPLs basis for not counting the downpower as unplanned. This is based on A(3) above in that the power reduction was not implemented as planned. Specifically, PPLs planned power reduction had not included a recirculation runback as part of the downpower sequence, was an interruption of the rod pattern adjustment, and was completed more rapidly than originally projected. The resident inspectors also considered the runback a deviation from the planned power reduction based on the off-normal procedures entered as well as the procedure entered to implement the runback as described in B) above.

Based on the runback being a deviation from the downpower plan, the inspectors further considered the other NEI 99-02 entries described in A) above.

1) The annunciator alarm was due to a configuration control error where an operator mispositioned a condenser bay valve. The inspectors considered this information in light of reference A(4) above. Therefore, this was a personnel error that resulted in an operator response by reducing power >20%.

2) The operators inserted a recirculation runback in response to the alarm. The inspectors considered this information in light of reference A(5) above. Therefore, this was a runback >20% and unplanned power change.

Page 5 of 8 Revised 10/21/2013 Page 6 of 23 in FAQ Package

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change

3) Based on PPL operator logs, the runback was initiated to lower radiation levels in the condenser bay. Using reference A(6) above, the downpower occurred for ALARA reasons.

4) PPLs description of the event in the FAQ states, in part, that the runback was necessary to rapidly decrease radiation levels. Based on reference A(1), the inspectors considered that the rapid reduction in power under other plant conditions could have challenged safety functions.

5) PPL discovered an off-normal condition that required a >20% power reduction to resolve and it was not an expected part of the planned rod pattern adjustment. Based on this and reference A(2) above, the runback was for an off-normal condition and was not an expected part of the planned evolution.

In summary, the power change that occurred was not planned as implemented. The downpower for a control rod pattern adjustment is normally executed through PPLs General Operating (GO) procedure and supporting Operations and Reactor Engineering procedures. In this case, PPL responded to an annunciator alarm resulting from a human performance mispositioning event by using Off Normal and Unplanned Power Reduction procedures and implemented a Recirculation Runback that resulted in a power change > 20%.

Potentially relevant existing FAQ numbers:

Archived FAQs related to the Unplanned Power Changes per 7000 Critical Hours PI (IE03) were reviewed for applicability and consideration of the manner in which power was reduced. A direct correlation to this FAQ was not found. However, archived FAQs are not to be used as a reference for current situations. NEI 99-02, Rev. 6, Appendix E, page E-4 states:

At the time of a revision of NEI 99-02, active FAQs will be reviewed for inclusion in the text.

These FAQs will then be placed in an archived file. Archived FAQs are for historical purposes and are not considered to be part of NEI 99-02.

The currently approved IE03 FAQs (469 and 483) were reviewed and the changes proposed by these FAQs are not applicable to the question posed by this FAQ.

Proposed Resolution of FAQ:

The resolution to this event should be to conclude that it should not be reported as an unplanned power change per 7000 critical hours.

NRC Tentative Response Unplanned Power Changes per 7,000 Critical Hours performance indicator is defined as 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. This indicator monitors power changes that could have, under other plant conditions, challenged safety functions. The cornerstone key attributes measured by the unplanned power changes PI are human error, procedure quality, design, and equipment performance as referenced in Inspection Manual Chapter 0308, Attachment 1, Technical Basis for Performance Indicators.

Page 6 of 8 Revised 10/21/2013 Page 7 of 23 in FAQ Package

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change The definition of an unplanned change in reactor power is currently defined in FAQ 469 as follows:

Unplanned change 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.

The question posed by the licensee is whether the rapid power reduction (runback) event count in the Unplanned Power Changes per 7,000 Critical Hours performance indicator. The licensee concludes that the event does not count towards the PI because of the following guidance in NEI 99-02, Revision 6, page 14, lines 10-14:

Equipment problems encountered during a planned power reduction greater than 20%

that alone may have required a power reduction of 20% or more to repair are not counted as part of this indicator if they are repaired during the planned power reduction.

However, if during the implementation of a planned power reduction, power is reduced by more than 20% of full power beyond the planned reduction, then an unplanned power change has occurred.

In addition, approved guidance in FAQ 469 provides examples of occurrences that are not counted toward the PI that include the following:

Unanticipated equipment problems that are encountered and repaired during a planned power reduction greater than 20% that alone could have required a power reduction of 20% or more to repair.

The staff reviewed FAQ 231 to gain an understanding of the intent of the above guidance, which was first included in Revision 1 of NEI 99-02. The staffs interpretation of the Susquehanna event is that the off-normal condition (sump alarm) was not caused by an equipment problem (degraded condition) but by human error (measured cornerstone key attribute of the PI) since the condenser area sump valve (manual valve) was mispositioned by an operator. Also, the staff does not consider the manual repositioning of a valve an equipment repair. In addition, the staff considers the rapid power change following the condenser area sump alarm as an urgent and reactive operator response (using an off-normal procedure to initiate a runback) to an off-normal condition, and therefore, a deviation (method and rate of power reduction) from the already planned power change (rod pattern adjustment) that resulted in an actual change in reactor power level of greater than 20%. This event alone meets the definition of unplanned changes in reactor power. The staffs interpretation of the guidance in NEI 99-02, Revision 6, page 14, lines 10-14 was to exclude events related to equipment degradation that alone may have (indicates possibility) required reduction greater than 20% to resolve; the staff does not interpret the guidance to exclude all events that meet the PI definition occurring during a planned power reduction.

NEI 99-02 guidance (FAQ 469) provides examples of occurrences that would count toward this PI. This event meets the following examples:

Examples of occurrences that would be counted against this indicator include:

Page 7 of 8 Revised 10/21/2013 Page 8 of 23 in FAQ Package

FAQ 13-02 (Tentative NRC Response)

Susquehanna Power Change 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.

Runbacks and power oscillations greater than 20 % of full power. A power oscillation that results in an unplanned power decrease of greater than 20%

followed by an unplanned power increase of 20% should be counted as two separate PI events, unless the power restoration is implemented using approved procedures. For example, an operator mistakenly opens a breaker causing a recirculation flow decrease and a decrease in power of greater than 20%. The operator, hearing an alarm, suspects it was caused by his action and closes the breaker resulting in a power increase of greater than 20%. Both transients would count since they were the result of two separate errors (or unplanned/non-proceduralized action).

Unplanned downpowers of greater than 20% of full power for ALARA reasons.

The staff concludes that this event counts as an occurrence toward the Unplanned Power Changes per 7,000 Critical Hours indicator for the following reasons:

The off-normal condition was a result of human error and not equipment problems (degraded condition); therefore, the guidance in NEI 99-02, Revision 6, page 14, lines 10-14 does not apply to this event.

A deviation (planned method and rate) from the planned power reduction (rod pattern adjustment) occurred because of an unrelated off-normal condition.

An actual power reduction greater than 20% occurred.

The event represents 3 examples that would otherwise count against the indicator.

The staff considers the guidance (NEI 99-02, Revision 6, page 14, lines 10-14) difficult to apply because of the ambiguity of the intent (i.e., why is credit being granted when otherwise the occurrence by itself would count against the PI). The staff recommends modifying the guidance to provide a clear understanding of the basis for applying the guidance. If the intent cannot be agreed upon, the staff recommends removing the problematic guidance completely.

Page 8 of 8 Revised 10/21/2013 Page 9 of 23 in FAQ Package