ML15154A877

Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating

ML15154A877
Person / Time
Site:	Palo Verde
Issue date:	06/02/2015
From:	Mims D APS, Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07056-DCM/DCE
Download: ML15154A877 (13)

Text

IMC 0410 DWIGHT C. MIMS aps Senior Vice President, Nuclear Regulatory & Oversight Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 Mail Station 7605 102-07056-DCM/DCE Tel 623 393 5403 June 2, 2015 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station (PVNGS) Unit 3 Docket No. STN 50-530 Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating This letter documents the background and technical information supporting the Arizona Public Service (APS) Company request for a Notice of Enforcement Discretion (NOED) for Palo Verde Nuclear Generating Station (PVNGS) Unit 3. The NOED request was discussed with the Nuclear Regulatory Commission (NRC) during a teleconference held on May 29, 2015. APS received verbal approval from the NRC staff for the NOED at 17:53 Mountain Standard Time (MST). This submittal fulfills the requirement that a written NOED request be submitted to the NRC within two working days following NRC verbal approval of the NOED. The enclosure to this letter provides the written request.

During the NOED teleconference with the NRC, APS discussed that no permanent change to the Operating License or Technical Specification (TS) appeared necessary because of the planned APS submittal of a license amendment request (LAR) for risk informed completion times pursuant to Technical Specifications Task Force (TSTF) traveler TSTF-505-A, Revision 1, Provide Risk-Informed Extended Completion Times

- RITSTF Initiative 4b. The NRC staff agreed that an LAR separate from the TSTF-505 submittal would not be necessary.

The events leading to the APS request began at 06:28 MST on May 27, 2015, when the Unit 3 High Pressure Safety Injection (HPSI) pump A was removed from service for routine preventative maintenance and declared inoperable. A routine oil sample taken from the HPSI motor outboard bearing appeared dark in color. Sample analysis revealed the presence of metal particles indicative of bearing babbitt material.

Troubleshooting determined the cause was associated with the motor shaft being axially misaligned resulting in damage to the motor outboard bearing.

APS requested NRC enforcement discretion for non-compliance with the Emergency Core Cooling System (ECCS) TS 3.5.3, ECCS - Operating, Limiting Condition for Operation (LCO) Required Action B.1, to restore the inoperable HPSI pump within 72 A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

102-07056-DCM/DCE June 2, 2015 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS

- Operating Page 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The requested 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> extended Completion Time provided sufficient time to complete repairs and post-maintenance testing to avoid a plant shutdown, required by TS LCO 3.5.3, Condition C, when the original 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time expired.

Corrective maintenance and testing of the Unit 3 HPSI pump A continued into the extended Completion Time, which started at 6:28 MST on Saturday, May 30, 2015.

APS restored the Unit 3 HPSI pump A to an OPERABLE status and exited Condition B of TS LCO 3.5.3 at 17:10 MST on May 30, 2015, within the extended Completion Time. Unit 3 remained in Mode 1 at 100 percent power and normal operating pressure and temperature throughout the period HPSI pump A was inoperable.

No commitments are being made to the NRC by this letter.

Should you need further information regarding this NOED request, please contact Thomas Weber, Regulatory Affairs Department Leader at (623) 393-5764.

Sincerely, DCM/DCE/hsc

Enclosure:

Request for Notice of Enforcement Discretion for Technical Specification LCO 3.5.3, ECCS - Operating cc:

M. L. Dapas NRC Region IV Regional Administrator T. W. Pruett NRC Region IV Director DRP C. A. Peabody NRC Senior Resident Inspector PVNGS M. T. Markley NRC DORL Branch Chief M. M. Watford NRC NRR Project Manager

ENCLOSURE Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating

Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating Introduction This letter documents the background and technical information supporting the Arizona Public Service (APS) Company request for a Notice of Enforcement Discretion (NOED) for Palo Verde Nuclear Generating Station (PVNGS) Unit 3. The NOED request was discussed with the Nuclear Regulatory Commission (NRC) during a teleconference held on May 29, 2015. APS received verbal approval from the NRC staff for the NOED at 17:53 Mountain Standard Time (MST). This enclosure fulfills the requirement that a written NOED request be submitted to the NRC within two working days following NRC verbal approval of the NOED.

The events leading to the APS request began at 06:28 MST on May 27, 2015, when the Unit 3 High Pressure Safety Injection (HPSI) pump A was removed from service for routine preventative maintenance and declared inoperable. A routine oil sample taken from the pump motor outboard bearing appeared dark in color. Oil viscosity and chemistry were otherwise normal. Sample analysis revealed the presence of metal particles indicative of bearing babbitt material (Sn, Cu, Pb). Microscopic examination concluded that most particles were generated at elevated temperatures. No previous oil sample of this bearing contained wear metal. Engineering concluded damage had occurred to the babbitt bearing surface resulting in deposition of the material in the oil.

Three attempts were made to flush the babbitt material from the bearing, but subsequent sampling reconfirmed the presence of babbitt material each time. Based upon this information the pump motor bearing was disassembled for corrective maintenance.

Inspections and measurements revealed improper axial adjustment of the motor coupling which caused the motor rotor shaft to be displaced toward the motor outboard bearing. The rotating thrust collar on the shaft wore (intermittently during motor starting) against the babbitted axial limit surface of the outboard journal bearing. The bearing journal surfaces were not significantly damaged. A decision was made to replace the bearing. The misalignment occurred during maintenance on HPSI pump A during the recent Unit 3 1 8 th refueling outage which was completed on May 3, 2015. The thrust collar, normally approximately 0.250 inches away from the outboard motor bearing, if aligned properly, is not relied upon during normal operation.

APS requested NRC enforcement discretion for non-compliance with the Emergency Core Cooling System (ECCS) TS 3.5.3, ECCS - Operating, Limiting Condition for Operation (LCO) Required Action B.1, to restore the inoperable HPSI pump within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The requested 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> extended Completion Time provided sufficient time to complete repairs and post-maintenance testing to avoid a plant shutdown, required by TS LCO 3.5.3, Condition C, when the original 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time expired. The additional 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time of the NOED started at 6:28 MST on Saturday, May 30, 2015. The required actions for Condition C specify entry into Mode 3, Hot Standby, within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> (C.1) and reactor coolant system (RCS) pressurizer pressure to be reduced to less than (<)1837 pounds per square inch absolute (psia) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> (C.2), and RCS cold leg temperature (To) to be reduced to <485 degrees Fahrenheit within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> (C.3).

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Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating The Unit 3 HPSI train A was declared inoperable on May 27, 2015, at 06:28 MST when it was removed from service in support of preventative maintenance. Operability was restored at 17:10 MST on May 30, 2015, following bearing replacement, axial alignment, and post-maintenance testing of the pump and motor. APS maintenance was able to perform the motor bearing oil flush in parallel with the coupling alignment which enabled the work to be done in a shorter duration than estimated. Also, multiple iterations of motor bearing flushes were not needed which shortened the duration of the maintenance.

The following provides the information, described in Nuclear Regulatory Commission (NRC) Inspection Manual Chapter (IMC) 0410, Notices of Enforcement Discretion, dated March 13, 2013, required to be included in requests for enforcement discretion.

07a. Did the licensee address what type of Notice of Enforcement Discretion (NOED) is being requested, which of the NOED criteria is satisfied, and how it satisfied those criteria?

IMC 0410, Section 06.02, "Types of NOEDs," Criterion a.1(a), "regular' NOED is satisfied. This criterion allows a plant in power operation to avoid unnecessary transients. Granting this NOED results in no net increase in radiological risk and avoids unnecessary plant transients in order to comply with TS LCO 3.5.3, thus minimizing potential safety consequences and operational risks. A transition from Mode 1 to Mode 3 at reduced pressure and temperature would result in unnecessary shutdown of the reactor and system realignments without a corresponding health and safety benefit.

07b. Did the licensee detail the TS or license condition that will be violated?

TS LCO 3.5.3 is applicable in Modes 1, 2, and in Mode 3 with pressurizer pressure greater than or equal to 1837 psia or with RCS Tc greater than or equal to 485 degrees Fahrenheit.

In order to initiate routine preventative maintenance on Unit 3 HPSI pump A, the necessary clearances were established and HPSI train A was declared inoperable and TS LCO 3.5.3, Required Action B.1 was entered, which specifies the inoperable train be restored to an operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If the inoperable train could not be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the plant would be placed in MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and RCS pressure and temperature must be reduced to <1837 psia and 485 degrees Fahrenheit within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> per the required actions of TS LCO 3.5.3, Condition C.

APS requested enforcement discretion to extend the TS LCO 3.5.3, Required Action B.1 Completion Time 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (from 72 to 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) to avoid the plant shutdown (Mode 3 entry) while HPSI pump A remained inoperable to complete the corrective maintenance and testing.

Unit 3 was in Mode 1 at 100% power and normal operating pressure and temperature at the time of the request.

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Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating 07c. Did the licensee provide a description of the circumstances, including: likely causes; the need for prompt action; the action taken to avoid the need for a NOED; and any relevant historical events?

The events leading to the APS request began at 06:28 MST on May 27, 2015, when the Unit 3 High Pressure Safety Injection (HPSI) pump A was removed from service for routine preventative maintenance and declared inoperable. A routine oil sample taken from the pump outboard motor bearing appeared dark in color. Oil viscosity and chemistry were otherwise normal. Sample analysis revealed the presence of metal particles indicative of bearing babbitt material (Sn, Cu, Pb). Microscopic examination concluded that most particles were generated at elevated temperatures. No previous oil sample of this bearing contained wear metal. Engineering concluded damage had occurred to the babbitt bearing surface resulting in deposition of the material in the oil.

Three attempts were made to flush the babbitt material from the bearing, but subsequent sampling reconfirmed the presence of babbitt material each time. Based upon this information the pump motor bearing was disassembled for corrective maintenance.

Inspections and measurements revealed improper axial adjustment of the motor coupling which caused the motor rotor shaft to be displaced toward the outboard motor bearing. The rotating thrust collar on the shaft wore (intermittently during motor starting) against the babbitted axial limit surface of the outboard journal bearing. The bearing journal surfaces were not significantly damaged. A decision was made to replace the bearing. The misalignment occurred during maintenance on HPSI pump A during the recent Unit 3 18th refueling outage which was completed on May 3, 2015. The thrust collar, normally approximately 0.250 inches away from the outboard motor bearing, if aligned properly, is not relied upon during normal operation.

The need for prompt action is based upon the TS LCO requirements of the ECCS and safety significance of the equipment.

APS took actions in an attempt to avoid the need for this NOED request, including establishment of a dedicated response team, comprised of maintenance, engineering, and work management to troubleshoot the cause of the bearing oil contamination and to make repairs under a maintenance plan using 24-hour coverage. A management oversight team was also provided. The schedule reflected that the maintenance would require more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to complete the bearing replacement, axial alignment, and post-maintenance testing.

The HPSI motor outboard bearing is a large motor split sleeve type bearing and is not prone to frequent failure. The PVNGS corrective action program records the following information that appeared to be relevant to this issue:

CRDR 3774620: In June of 2011, the Unit 1 HPSI B motor outboard bearing oil was identified as being dark. Engineering evaluation determined that the darker color was the result of a stained sight glass and lack of a white discriminator 3

Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating backdrop behind the sight glass. The pump passed all tests and was placed back into service.

APS performed a review of past operating history of the HPSI motor bearings at PVNGS. There have been no occurrences of a HPSI motor bearing failure.

07d. Did the licensee provide information that shows the licensee fully understands the cause of the situation that has led to the NOED request?

Inspections and measurements revealed improper axial adjustment of the motor coupling which caused the motor rotor shaft to be displaced toward the outboard motor bearing. The rotating thrust collar on the shaft wore (intermittently during motor starting) against the babbitted axial limit surface of the outboard journal bearing. The bearing journal surfaces were not significantly damaged. A decision was made to replace the bearing. The misalignment occurred during maintenance on HPSI pump A during the recent Unit 3 1 8 th refueling outage which was completed on May 3, 2015. The thrust collar, normally approximately 0.250 inches away from the outboard motor bearing, if aligned properly, is not relied upon during normal operation.

07e. Did the licensee detail the proposed course of action to resolve the situation until the situation no longer warrants an NOED?

The planned maintenance involved motor outboard bearing replacement, axial alignment, and post-maintenance testing. These actions resolved the condition and restored the Unit 3 A HPSI pump to an OPERABLE status.

07f. Did the licensee address that the resolution itself does not result in a different, unnecessary transient?

The PVNGS safety analysis considers the HPSI system as a mitigating system and also considers a single failure of a HPSI train. A HPSI pump failure is not considered an initiating event. TS LCO 3.5.3, Condition B, accommodates the temporary unavailability of a single train of HPSI for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The maintenance planned in the extended Completion Time requested by APS in this NOED request was limited to restoring HPSI pump A to an OPERABLE status. Therefore, the resolution would not introduce a different, unnecessary transient.

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Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating 07g. Did the licensee explain why they did not have time to process an emergency TS or license amendment or that a license amendment is not needed?

The misalignment of the HPSI pump motor could not have been anticipated. The preparation of an emergency TS or license amendment prior to the time required for restoration of the HPSI pump was not practical.

07h. Did the licensee describe the condition and operational status of the plant, including safety-related equipment out of service or otherwise inoperable, and nonsafety-related equipment that is degraded or out of service that may have risk significance and that may increase the probability of a plant transient or may complicate the recovery from a transient or may be used to mitigate the condition?

PVNGS Unit 3 is currently operating at 100 percent power and at normal operating pressure and temperature. The degraded condition of the HPSI pump A motor outboard bearing, discovered during performance of routine preventative maintenance, resulted in a single train of the HPSI ECCS subsystem being inoperable beyond the planned time and the inability to exit TS LCO 3.5.3, Required Action B.1, within the Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

For Unit 3, aside from TS LCO 3.5.3, Required Action B.1, no other safety-related equipment was out-of-service or otherwise inoperable. The potential risk impacts of out-of-service nonsafety-related switchyard breaker PL925 and nonsafety-related normal pressurizer spray valve RCEPV100E were considered and discussed in response to question 71 below. No other non-safety related equipment was degraded or out-of-service that had risk significance, increased the probability of a plant transient, complicated the recovery from a transient, or could be used to mitigate the condition.

Units 1 and 2 remained at 100 percent power for the duration of the extended Completion Time authorized by the NOED.

07i. Did the licensee request a specific period for the NOED, including a justification for the duration of the noncompliance?

APS requested a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> extension for the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> completion time of TS LCO 3.5.3, Required Action B.1, to 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. The completion time expiration changed from 06:28 MST on May 30, 2015, to 06:28 MST on May 31, 2015. The justification for the duration is provided in the following risk assessment sections of this NOED request.

The verbal request noted that if during the course of repairs unexpected conditions were identified such that work could not have been completed within the extended Completion Time, a plant shutdown would have been completed as required by TS LCO 3.5.3, Required Actions C.1, C.2, and C.3.

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Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating 07j. Did the licensee detail and explain compensatory measures the plant has both taken and will take to reduce the risk associated with the specified configuration?

Consistent with APS response in section 71, the major risk impact that results from the maintenance configuration during the period where HPSI pump A is unavailable is reduced redundancy for RCS inventory make-up following a small or medium break loss-of-coolant event, steam generator tube rupture event, or a rapid RCS cool down.

Given this insight, the following compensatory measures shall be implemented (although not credited in the risk evaluation) for the duration that HPSI pump A is unavailable:

1. Suspend work in the switchyard

2. Restrict any work on the Unit 3 RCS pressure boundary

3. Protect Unit 3 Train B safety injection pumps

4. Protect the Unit 3 Train B engineered safety feature (ESF) Switchgear

5. Protect both Unit 3 emergency diesel generators

6. Protect both station blackout generators

7. Protect the Unit 3 charging pumps 07k. Did the licensee discuss the status and potential challenges to offsite and onsite power sources, including any current or planned maintenance in the distribution system and any current or planned maintenance to the emergency diesel generators?

There are currently no challenges to offsite power sources. The required and alternate offsite power sources are functional and available. One switchyard breaker is currently out-of-service for maintenance and that work will be suspended during the period of the NOED. The one breaker (Breaker PL925 - West Wing Number #2 East/West bus cross-connect breaker) does not impair the ability to provide offsite power from the seven off-site sources available to the PVNGS site.

071. Did the licensee include the safety basis for the request and an evaluation of the safety significance and potential consequences of the proposed course of action?

The Palo Verde internal events, internal flooding, and fire probabilistic risk assessment (PRA) model (PRADATA Version 20) was used to evaluate the risk associated with the extended Completion Time of Unit 3 HPSI Pump A.

The seismic risk impact was quantitatively evaluated using the recently completed and Peer Reviewed model developed in compliance with NRC RG 1.200, Revision 2 (SDOC NN345-A00008 Revision 0, Palo Verde Seismic PRA - Quantification). The Unit 3 HPSI pump A was determined to be seismically rugged by the fragility team and screened out from modeling. The seismic risk impact of the HPSI system was quantified to result in a 6

Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating Risk Achievement Worth (RAW) of 1.0 for both core damage frequency (CDF) and large early release frequency (LERF).

The equipment unavailability windows and risk-impacting activities assumed to be scheduled concurrent with the unavailability of Unit 3 HPSI pump A during the extended Completion Time being requested are as follows:

Out of Service Component PRA Model Basic Event Impacted Unit 3 High Pressure Safety Injection Pump A OOS-SIAP02 Switchyard Breaker PL925 OOS-SWYD-PL948 (Note 1)

Unit 3 Pressurizer Normal Spray Valve RICEPV100E OOS-NRMSPRAY (Note 2)

Note 1: Event OOS-SWYD-PL948 bounds the Switchyard breaker PL925 work. Per Operations direction, maintenance on switchyard breaker PL925 will be suspended and remain out of service during the period of enforcement discretion. Since the Palo Verde revision 20 model is based on Unit 1, the associated switchyard breaker (PL945 or conservatively PL948) has to be modeled in order to replicate the equivalent impact on Unit 3 risk.

Note 2: Event OOS-NRMSPRAY bounds the maintenance on normal pressurizer spray valve RCEPV100E by rendering all pressurizer normal spray unavailable.

The specified basic events were selected to represent a bounding case for the maintenance that is anticipated to potentially occur during the period of enforcement discretion. PRA model basic event OOS-SIAP02 renders the HPSI pump A unavailable.

In addition to the above events, the frequency of initiating event loss of off-site power including subsequent losses (IELOSP) was increased from its nominal value of 2.42E-2/yr to 3.12E-2/yr to reflect the increased likelihood of a loss of offsite power due to a switchyard breaker being unavailable. This increase is in accordance with the methodology applied to assess 1 OCFR50.65 (a)(4).

Consequence(s)

Baseline OOS Delta Frequency Frequency Combined Internal Events, Internal 2.30E-5/yr 2.45E-5/yr 1.50E-6/yr Flooding, and Fire CDF Combined Internal Events, Internal 1.04E-6/yr 1.05E-6/yr 1.OOE-8/yr Flooding, and Fire LERF Seismic CDF Note 3 Note 3 Note 3 Seismic LERF Note 3 Note 3 Note 3 Note 3: Screened out quantitatively.

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Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating Consequence Total Total OOS Total Delta Incremental Baseline Frequency Conditional Frequency Probability Core Damage 2.30E-5/yr 2.45E-5/yr 1.50E-6/yr 4.1 E-9 Large Early 1.04E-6/yr 1.05E-6/yr 1.OOE-8/yr 2.6E-1 1 Release The incremental conditional core damage probability (ICCDP) and incremental conditional large early release probability (ICLERP) over the requested period of enforcement discretion are much less than the 5E-7 and 5E-8 guidance thresholds in NRC Inspection Manual Chapter 0410, respectively.

Dominant contributors to risk include medium and small loss of coolant accidents (MLOCA and SLOCA) and steam generator tube rupture events. Internal Flooding mitigation is not measurably impacted by the equipment out of service. Fire transients that initiate interfacing system LOCAs or multiple spurious operation failure of reactor coolant pump seals increase small break LOCAs, and these transients have a larger contribution with one of the two HPSI pumps unavailable. Transients that potentially challenge the Primary Safety Valves (Loss of Condenser Vacuum, Spurious Main Steam Isolation Valve Closure, and Turbine Trip) see a slight increase in importance, but are masked by the contribution redistributed to the MLOCA and SLOCA initiators.

No compensatory measures are required based on risk.

Although not credited in the risk evaluation, the following compensatory measures shall be implemented for the duration that HPSI pump A is unavailable:

1. Suspend work in the switchyard

2. Restrict any work on the Unit 3 RCS pressure boundary

3. Protect Unit 3 Train B safety injection pumps

4. Protect the Unit 3 Train B engineered safety feature (ESF) Switchgear

5. Protect both Unit 3 emergency diesel generators

6. Protect both station blackout generators

7. Protect the Unit 3 charging pumps No indication exists based on oil sampling surveillances and maintenance history to suggest degraded performance of the other HPSI and similar pumps. Therefore, common-cause is not of concern, and no adjustment to the common-cause failure potential is considered.

Internal flooding, internal fire and seismic event sequences are considered in the response. Other external hazards have been evaluated and screened from further analysis in the Palo Verde PRA (1 3-NS-C1 11, Other External Hazards PRA, Rev. 0). In addition, this screening has been performed and Peer Reviewed per NRC RG 1.200, Revision 2. Therefore, the unavailability of HPSI pump A does not impact other external hazards.

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Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating 07m. Did the licensee demonstrate that the NOED condition, along with any compensatory measures, will not result in more than a minimal increase in radiological risk, either in a quantitative assessment that risk will be within the normal work control levels (ICCDP less than or equal to 5E-7 and/or ICLERP less than or equal to 5E-8) or in a defensible qualitative manner?

The resulting increases in core damage frequency and large early release frequency are very small, resulting in incremental conditional probabilities much less than the guideline values, as shown below:

Core Damage Large Early Release NOED Plant Configuration Frequency 2.45E-5/yr 1.05E-6/yr Baseline Frequency 2.30E-5/yr 1.04E-6/yr Risk Increase Frequency 1.50E-6/yr 1.OOE-8/yr Incremental Conditional Probability 4.1 E-9 2.6E-1 1 The ICCDP and ICLERP over the requested period of enforcement discretion are much less than the 5E-7 and 5E-8 guidance thresholds in NRC Inspection Manual Chapter 0410, respectively.

07n. Did the licensee discuss forecasted weather and pandemic conditions for the NOED period and any plant vulnerabilities related to weather or pandemic conditions?

There were no active alerts for any adverse weather conditions in the Phoenix area.

The five-day national weather forecast indicated clear weather with highs near 100 degrees for the Phoenix area.

There were no pandemic conditions present in Arizona.

070. Did the licensee describe the basis for the conclusion that the noncompliance will not create undue risk to public health and safety?

The proposed period of noncompliance was not detrimental to public health and safety.

APS evaluated the risk and determined that it was sufficiently low. A summary of the evaluation is provided as part of items 071 and 07m of this document. To further protect the health and safety of the public, risk management actions as described in items 07j and 071 were implemented.

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Enclosure Request for Notice of Enforcement Discretion for Technical Specification 3.5.3, ECCS - Operating 07p. Did the licensee describe the basis for the licensee's conclusion that the noncompliance will not involve adverse consequences to the environment?

This request for enforcement discretion did not result in any significant changes in the types, or significant increase in the amounts of any effluents that were released offsite.

In addition, no significant increase in individual or cumulative occupational radiation exposures was involved as a result of the request. Therefore, it can be concluded that the NRC's granting of this request for enforcement discretion does not involve any adverse consequences to the environment.

07q. Did the licensee's facility organization that normally reviews safety issues approve the request?

The PVNGS Plant Review Board met on May 29, 2015, and conducted a review of the NOED request as required by the station's NOED procedure. The board performed a detailed review of the APS responses to each of the questions related to the NOED request. The board approved the NOED request and did not identify any nuclear safety issues related to the proposed schedule of activities and compensatory measures that were implemented as defense-in-depth measures.

07r. Did the licensee commit that it will submit a written NOED request within two working days and a follow-up license amendment request following the staff's verbal granting of the NOED?

This letter fulfills the APS commitment to submit a written NOED request not later than 16:30 Central Daylight Time on June 2, 2015. A follow-up license amendment request will not be submitted because it is not expected that this condition will recur in the foreseeable future. In addition, APS plans to submit a license amendment request in mid-2015 pursuant to Technical Specifications Task Force (TSTF) traveler TSTF-505-A, Revision 1, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b, which will allow APS to calculate a risk-informed TS Completion Time in the event a HPSI train becomes inoperable in the future. No permanent change to the Operating License or TSs is necessary because of the application for risk informed completion times that is currently planned for mid-2015.

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