NRC-15-0027, Submittal of Inservice Testing Program Relief Request PRR-012 for Quarterly Test of Core Spray Pumps

Submittal of Inservice Testing Program Relief Request PRR-012 for Quarterly Test of Core Spray Pumps

ML15064A073
Person / Time
Site:	Fermi
Issue date:	03/05/2015
From:	Kaminskas V DTE Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-15-0027
Download: ML15064A073 (18)

Text

Vito A. Kaminskas Site Vice President DTE Energy Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.6515 Fax: 734.586.4172 Email: kaminskasv@dteenergy.com DTE Energy-10 CFR 50.55a(z)(1)

March 5, 2015 NRC-15-0027 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

References:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

2) DTE Electric Company letter to NRC, "Submittal of Inservice Testing Program Relief Requests for Pumps and Valves-Third Ten-Year Interval," NRC-09-0064, dated November 3, 2009 (ML093140302)

3) U.S. Nuclear Regulatory Commission, "Fermi 2 - Evaluation of Relief Request Nos: PRR-002, PRR-003, and PRR-006, for the Third 10-Year Interval Inservice Testing Program," dated July 6, 2010 (ML101670351)

4) DTE Electric Company letter to NRC, "Submittal of Revised Relief Request No. PRR-002 for the Inservice Testing Program Third 10-Year Interval," NRC-12-0015, dated February 20, 2012 (ML12052A043)

5) U.S. Nuclear Regulatory Commission, "Fermi 2 - Evaluation of Relief Request PRR-002, Revision 1, for the Third 10-Year Interval Inservice Testing Program for Fermi 2," dated January 31, 2013 (ML13022A456)

6) U.S. Nuclear Regulatory Commission, Regulatory Guide 1.192, Revision 1, "Operation and Maintenance Code Case Acceptability, ASME OM Code," dated August 2014 (ML13340A034)

USNRC NRC-15-0027 Page 2

7) U.S. Nuclear Regulatory Commission, Public Meeting Notice, "Forthcoming Pre-Application Teleconference with DTE Electric Company to Discuss Proposed Relief Request Regarding Core Spray System Pumps," dated February 12, 2015 (ML15043A245)

Subject:

Submittal of Inservice Testing Program Relief Request PRR-012 for Quarterly Test of Core Spray Pumps Pursuant to 10 CFR 50.55a(z)(1), DTE Electric Company (DTE) hereby requests U.S.

Nuclear Regulatory Commission (NRC) approval of the enclosed Relief Request PRR-012 to allow quarterly testing of core spray pumps to be conducted in parallel for the remainder of the third ten-year interval of the Inservice Testing (IST) program at Fermi 2, which started on February 17, 2010. The enclosure to this letter provides the details of this Relief Request.

Since the pre-operational testing phase of Fermi 2, testing of the Core Spray (CS)

System pumps has been conducted with two pumps running in parallel, which deviates from the IST requirement to test each pump individually. Relief from the requirement to test each pump individually was granted by the NRC throughout each of the first and second ten-year IST intervals.

On November 3, 2009, DTE submitted relief requests for the third ten-year IST interval, including PRR-002, Relief to Allow Parallel Testing of Core Spray Pumps (Reference 2). PRR-002 requested relief in three specific areas:

relief to continue running the quarterly test with dual pumps, relief to continue using a flow reference curve as acceptance criterion, and relief to delay the first comprehensive pump test (CPT) until a system modification has been completed.

In Reference 2, DTE indicated that system modifications were planned that would eliminate the need for relief from individually testing the CS pumps each quarter and the need to use flow reference curves as acceptance criteria. Therefore, relief for these two IST requirements was requested on a temporary basis. Additionally, relief was requested to delay the CPT, which requires individual pump testing, until the modification was complete. NRC approved PRR-002 on July 6, 2010 (Reference 3).

On February 20, 2012, DTE submitted a revision to Relief Request PRR-002 (Reference 4) requesting NRC approval to extend the relief for quarterly CS pump testing, extend the use of flow reference curves, and delay the first CPT to allow additional time to prepare for implementation of the modifications due to some scoping changes. PRR-002, Revision 1, was approved by the NRC in Reference 5.

USNRC NRC-15-0027 Page 3 During the subsequent evaluation and scoping work for this modification in preparation for refueling outage 17 (RF-17) scheduled for fall 2015, DTE determined that the complexity of the original modification to meet the requirement for individual quarterly pump testing would be cost prohibitive with no substantial increase in safety.

Therefore, DTE is currently pursuing an alternative modification to be implemented during RF-17 and is requesting an extension of the previously granted relief from single pump testing during the quarterly test of the core spray pumps for the remainder of the third ten-year IST period.

DTE believes that continuing to perform the quarterly pump tests in parallel for the duration of the third ten-year IST interval reflects the most conservative approach to minimize potential test line piping and valve degradation, limit challenging the test valve motor operator, and ensure continuation of accurate trend monitoring of the core spray system's performance. This approach reflects normal system operation and Technical Specification requirement that pumps be operable in parallel. The CPT for each individual pump is planned to be performed during RF-17 after completion of the current planned modification and will be performed every two years thereafter.

The use of flow reference curves is now approved in 10 CFR 50.55a(b)(6), which incorporates American Society of Mechanical Engineers Operation and Maintenance of Nuclear Power Plants Code Case OMN-16 (2006 Addenda), Use of a Pump Curve for Testing, as described in Regulatory Guide 1.192, Revision 1, Operation and Maintenance Code Case Acceptability, ASME OM Code (Reference 6); therefore, no further relief is needed for the use of the flow reference curves.

The planned modification will be implemented during RF-17 scheduled in the fall of 2015, at which time the current relief from quarterly single pump testing will expire.

Therefore, DTE requests NRC approval of this Relief Request by November 30, 2015, in order to use this relief for the next quarterly test following RF-17.

A pre-application teleconference was held with NRC staff on February 25, 2015 (Reference 7). Should you have any questions or require additional information, please contact Mr. Christopher Robinson, Licensing Manager at (734) 586-5076.

Sincerely,

Enclosure:

10 CFR 50.55a Relief Request PRR-012

USNRC NRC-15-0027 Page 4 cc:

Director, Office of Nuclear Reactor Regulation NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Michigan Public Service Commission, Regulated Energy Division (kindschl@michigan.gov)

Enclosure to NRC-15-0027 10 CFR 50.55a Relief Request PRR-012

Enclosure to NRC-15-0027 Page 1 10 CFR 50.55a Relief Request PRR-012 Quarterly Test of Core Spray Pumps Proposed Alternative In Accordance with 10 CFR 50.55a(z)(1)

Alternative that provides acceptable level of quality and safety

1. ASME Code Component(s) Affected Pump ID Pump Description Code OM Type Speed Class Group E2101C001A Division 1 Core Spray Pump A 2

B Centrifugal 3560 RPM E21010001B Division 2 Core Spray Pump B 2

B Centrifugal 3560 RPM E2101C001C Division 1 Core Spray Pump C 2

B Centrifugal 3560 RPM E2101C001D Division 2 Core Spray Pump D 2

B Centrifugal 3560 RPM

2. Applicable Code Edition and Addenda

ASME OM Code 2004 Edition

3. Applicable Code Requirement

ISTB-3300 (Reference Values)

ISTB-5122 (Group B Test Procedure)

4. Reason for Request

Pursuant to 10 CFR 50.55a(z), "Alternatives to codes and standards requirements," relief is requested to deviate from the Group B (stand-by) pump testing requirements in American Society of Mechanical Engineers (ASME) Operation and Maintenance (OM) Code sections ISTB-3300 and ISTB-5122. The basis of this Relief Request is that "the proposed alternative would provide an acceptable level of quality and safety."

Enclosure to NRC-15-0027 Page 2 The ASME OM Code is considered applicable to component testing rather than system level testing. Therefore, the general ASME OM Code requirements for Group B pumps are interpreted to be performed on individual pumps. Historically, the Group B test for the Core Spray (CS) System at Fermi 2 has been performed on two pumps running in parallel due to test system design limitations. For example, division 1 Core Spray (CS) Pumps A and C are operated in parallel during the quarterly pump surveillance. DTE Electric Company (DTE) is requesting permission to continue performing the Group B CS test with the pumps operated in parallel for the remainder of the third ten-year Inservice Test (IST) interval following refueling outage 17 (RF-17) when the current relief request PRR-002 expires. The two year frequency comprehensive pump test will be performed by individual pump testing during RF-17, planned for fall 2015, after implementing a system modification.

Background

The CS System protects the reactor core in the event of a large break loss of coolant accident (LOCA) if the Feedwater, Control Rod Drive (CRD), Reactor Core Isolation Cooling (RCIC), High Pressure Cooling Injection (HPCI), or Residual Heat Removal (RHR) Systems are unable to maintain Reactor Pressure Vessel (RPV) water level. At DTE's Fermi 2 Nuclear Power Plant, the CS System is divided into two divisions, 1 and 2, with two pumps in each division since each pump is capable of providing only 50% of the desired system flow. If one pump is determined to be inoperable, then the division is declared inoperable.

DTE requested relief from the U.S. Nuclear Regulatory Commission (NRC) to allow the Core Spray pump tests to be conducted with two pumps running in parallel during the first and second ten-year intervals of the IST program. This relief was necessary because the existing flow control valves are not capable of throttling low enough to accommodate single pump operation without experiencing unstable operation, cavitation, and severe vibration.

Additionally, the test system configuration and use of dual pumps required relief to allow DTE to use a pump curve methodology for the acceptance criteria.

Prior to the third ten-year interval, DTE requested relief in Relief Request PRR-002, Revision 0 (Reference 7.1). This relief was similar to the previous relief granted during the first and second ten-year intervals to allow dual pump operation during the quarterly Group B test and use of a pump curve as acceptance criteria. In this request, DTE also described a planned modification to the CS test line to facilitate single pump operation for the quarterly Group B test and the new comprehensive pump test (CPT) (ISTB-5123) by changing test line isolation valve design (E2150F015A&B) on both divisions including the installation of flow restriction orifices. A subsequent request, PRR-002, Revision 1 (Reference 7.2) was granted to extend this relief through RF-17 to allow additional time for planning and scoping the proposed modification.

As DTE continued to plan the modification as described in Reference 7.1, the modification became cost prohibitive due to cost of new valves, reanalysis of the piping system, and the necessary implementation maintenance. The increased cost and risk associated with implementing this modification would not substantially increase the safety benefit to the station; therefore, DTE decided to pursue a different strategy. An alternate modification is planned for RF-17, which will consist of changing the valve internals and actuator gearing on the existing test line isolation valves (E2150F015A&B). This Relief Request (PRR-012) is

Enclosure to NRC-15-0027 Page 3 written to request relief from testing the Core Spray pumps individually for the quarterly Group B test following the expiration of PRR-002, Revision 1, after RF-17 through the end of the third ten-year interval.

Proposed Alternative The proposed alternative is to perform the quarterly Group B pump test in the manner that it has historically been performed (dual pump testing method).

During the quarterly Group B test, both pumps in each division will be tested as a single unit.

This implies that differential pressure and developed head reference values represent a combined pump flow characteristic. Since both pumps are run in parallel, acceptance criteria for differential pressure have been established (Attachments 1 and 2), which are more restrictive than the criteria given in Table ISTB-5121-1 for centrifugal pumps'. The following additional limitations on acceptance criteria are currently imposed and will be maintained for the duration of the Relief Request, to assure that any degradation in performance is detected and corrected in a timely manner:

1. In order to enhance the ability to detect the equivalent of one pump's degradation the following acceptance criteria will be utilized, which are more stringent than ISTB limits:

Acceptable DP Range -

0.94 to 1.06 Alert Range -

0.92 to <0.94 Required Action Range -

Low <0.92 and High >1.06

2. If the hydraulic performance of a CS division enters the Alert Range for any reason other than instruments out of calibration, both pumps in that division will be individually evaluated (e.g., perform motor diagnostics, evaluate vibration data, etc.)

in order to determine which pump(s) in the division has degraded. The testing frequency will be doubled until the cause of the deviation is determined and the condition is corrected.

3. If the hydraulic performance of a CS division exceeds the Required Action ranges for any reason the CS division will be declared inoperable. Appropriate inspections, tests, and repairs will be completed prior to returning the division to service.

4. New reference curves will be established or the current curves verified after either pump in the division has been repaired, replaced, or serviced.

5. As noted above, the modification performed during RF-17 will change the valve internals and gearing for the CS test line isolation valves (E2150F015A/B). This will allow single pump testing during the Comprehensive Pump Test every 2 years. This test, which will be performed during RF-17, will also help detect small levels of degradation that may not be as easily noticed during the Quarterly Group B test.

1 ISTB-5122 Group B Test Procedure uses the acceptance criteria from the ISTB-5121 Group A Test Procedure.

Therefore, Table ISTB-5121-1 is referenced here.

Enclosure to NRC-15-0027 Page 4

6.

Measuring and Test Equipment (M&TE) for pressure will meet the ASME OM Code requirements for a Comprehensive Pump Test (+/- 0.5%).

7. Vibration data will continue to be performed on each individual pump using the acceptance criteria established in ASME OM Code 2004 Edition (Table ISTB-5121-1). A single Alert criterion and a single Required Action criterion will be used over the range of the pump curve.

8.

DTE will use normalization to a reference flow to improve the effectiveness of trending.

The use of flow reference curves is now approved in 10 CFR 50.55a(b)(6), which incorporates ASME Operation and Maintenance of Nuclear Power Plants Code Case OMN-16 (2006 Addenda), Use of a Pump Curve for Testing, as described in Regulatory Guide 1.192, Revision 1, Operation and Maintenance Code Case Acceptability, ASME OM Code (Reference 7.3); therefore, no further relief is needed for the use of the flow reference curves.

Basis DTE requests relief to continue Group B quarterly testing of the CS pumps in parallel instead of individually. This is due to the additional time that will be required to perform the surveillance and resultant Limiting Condition for Operation (LCO) time, motor-operated valve (MOV) motor start limitations, loss of historical trend data, and potential valve cavitation.

The current quarterly surveillance requires throttling E2150F015A&B while operating both pumps in parallel to achieve a flow of > 6600 gallons per minute (GPM). This flow rate is used to meet both Technical Specifications (TS) surveillance and IST testing using a pump curve based acceptance criteria. The TS surveillance requires both pumps in a division to be operated in parallel. If individual pump testing is required, one pump would be started and tested for IST, then the second pump would be started to conduct the TS surveillance in parallel, then the first pump would be shut off to test the second pump under IST. This would represent a significant time increase from conducting both tests in parallel simultaneously and challenge the surveillance LCO time. This would also increase the time each division is temporarily inoperable while the testing is performed, which represents unnecessary reduction in defense in depth and introduces challenges to the operators. In addition, there is a limitation on how often a motor-operated valve can be cycled for throttling. The motor manufacturer, Limitorque (now owned by Flowserve), recommends a cooling period after 5 consecutive motor starts. Also, there would be a loss of trend data since DTE has obtained pump differential pressure and vibration for IST Group B testing with two pumps on a quarterly basis for years. Finally, a recent modeling study for the system after the current planned modification found that the valve cavitation index would be worse when testing with a single pump as compared to dual pumps. Therefore, it is preferable to limit how often the pumps are operated individually.

The CS pumps are standby system pumps and accumulate very few hours of run time per year. Degradation is unlikely for such pumps constructed to high quality standards, with periodic maintenance and lubrication activities. The fact that they do not operate frequently also increases the chance of detecting degradation before it reaches the IST Required

Enclosure to NRC-15-0027 Page 5 Action and TS requirements. Charts showing the normalized historic performance trends for each division (pair of pumps) are attached to this Relief Request (Attachments 3 and 4).

Historic performance data demonstrates the long-term stability of the CS pumps and the ability to trend the hydraulic performance by testing a pair of pumps for each division. In addition to the pump differential pressure (Dp), each pump is currently analyzed for vibration, and no adverse vibration trends have been detected.

In summary, continuing to perform the Group B pump test using two CS pumps in parallel combined with a single pump CPT performed every two years is adequate to detect degradation. The quarterly Group B test will continue to use tighter Dp acceptance criteria compared to the ASME OM Code, individual pump vibration testing, pressure gauge accuracy requirements equivalent to CPT standards, and normalized pump trending. The CPT performed every two years will increase the likelihood of detecting any potential degradation occurring on an individual pump that may be masked during the dual pump test.

Finally, the attached Dp trend charts show a stable trend and a lack of apparent degradation over many years of service.

5. Duration of Proposed Alternative

This proposed alternative will be used for the remaining duration of the Fermi 2, third ten-year interval.

6. Attachments, Division 1 Core Spray Pumps Performance Curve and Acceptance Criteria Table for Procedure 24.203.02, Division 2 Core Spray Pumps Performance Curve and Acceptance Criteria Table for Procedure 24.203.03, Division 1 Core Spray Pump Differential Pressure Trend Chart, Division 2 Core Spray Pump Differential Pressure Trend Chart

7.

References 7.1 DTE Electric Company letter to NRC, "Submittal of Inservice Testing Program Relief Requests for Pumps and Valves-Third Ten-Year Interval," NRC-09-0064, dated November 3, 2009 (ML093140302) 7.2 DTE Electric Company letter to NRC, "Submittal of Revised Relief Request No. PRR-002 for the Inservice Testing Program Third 10-Year Interval," NRC-12-0015, dated February 20, 2012 (ML12052A043) 7.3 U.S. Nuclear Regulatory Commission, Regulatory Guide 1.192, Revision 1, "Operation and Maintenance Code Case Acceptability, ASME OM Code," dated August 2014 (ML13340A034)

8. Precedent Fermi 2 Nuclear Power Plant - Relief Request PRR-002, Revision 1, was approved by NRC on January 31, 2013 (ML13022A456).

to Enclosure to NRC-15-0027 Division 1 Core Spray Pumps Performance Curve and Acceptance Criteria Table for Procedure 24.203.02

DIVISION 1 CORE SPRAY PUMPS PERFORMANCE CURVE AND ACCEPTANCE CRITERIA TABLE FOR PROCEDURE 24.203.02 APr = 456.8592530 -

0.027306Qr where:

APr = Reference Differential Pressure, psi Qr = Reference Flow, gpm Acceptable Range:

0.94APr AP 1.06AP, Alert Range Low:

0.92APr AP < 0.94APr Required Action Range:Low AP < 0.92APr High AP > 1.06APr Table 1 Core Spray Loop A E2101C001A&C Flow Required Alert Range Low Acceptable Range Required Action Action AP Range High Range Low gpm psi psi psi psi 6600

<254.6 254.6 to <260.1 260.1 to 290.4

>290.4 6650

<253.3 253.3 to <258.8 258.8 to 289.0

>289.0 6700

<252.0 252.0 to <257.5 257.5 to 287.6

>287.6 6750

<250.8 250.8 to <256.2 256.2 to 286.1

>286.1 6800

<249.5 249.5 to <255.0 255.0 to 284.7

>284.7 6850

<248.3 248.3 to <253.7 253.7 to 283.3

>283.3 6900

<247.0 247.0 to <252.4 252.4 to 281.8

>281.8 6950

<245.8 245.8 to <251.1 251.1 to 280.4

>280.4 7000

<244.5 244.5 to <249.8 249.8 to 279.0

>279.0 7050

<243.3 243.3 to <248.5 248.5 to 277.5

>277.5 7100

<242.0 242.0 to <247.3 247.3 to 276.1

>276.1 7150

<240.7 240.7 to <246.0 246.0 to 274.7

>274.7 7200

<239.5 239.5 to <244.7 244.7 to 273.2

>273.2 to Enclosure to NRC-15-0027 Division 2 Core Spray Pumps Performance Curve and Acceptance Criteria Table for Procedure 24.203.03

DIVISION 2 CORE SPRAY PUMPS PERFORMANCE CURVE AND ACCEPTANCE CRITERIA TABLE FOR PROCEDURE 24.203.03 AP, = 444.50000 -

0.02500Qr where:

APr = Reference Differential Pressure, psi Qr = Reference Flow, gpm Acceptable Range:

0.94APr AP < 1.06APr Alert Range Low:

0.92APr AP < 0.94APr Required Action Range:Low AP < 0.92APr High AP > 1.06APr Table 1 Core Spray Loop B E2101COO1B&D Flow Required Alert Range Low Acceptable Range Required Action Range AP Action Range Low High gpm psi psi psi psi 6600

<257.1 257.1 to <262.8 262.8 to 296.1

>296.1 6650

<256.0 256.0 to <261.6 261.6 to 294.8

>294.8 6700

<254.8 254.8 to <260.4 260.4 to 293.5

>293.5 6750

<253.7 253.7 to <259.3 259.3 to 292.2

>292.2 6800

<252.6 252.6 to <258.1 258.1 to 290.9

>290.9 6850

<251.4 251.4 to <256.9 256.9 to 289.6

>289.6 6900

<250.3 250.3 to <255.7 255.7 to 288.3

>288.3 6950

<249.1 249.1 to <254.6 254.6 to 286.9

>286.9 7000

<247.9 247.9 to <253.4 253.4 to 285.5

>285.5 7050

<246.8 246.8 to <252.2 252.2 to 284.2

>284.2 7100

<245.6 245.6 to <251.0 251.0 to 282.9

>282.9 7150

<244.5 244.5 to <249.9 249.9 to 281.6

>281.6 7200

<243.4 243.4 to <248.7 248.7 to 280.3

>280.3 to Enclosure to NRC-15-0027 Division 1 Core Spray Pump Differential Pressure Trend Chart

PRR-012, Attachment 3, Div 1 Core Spray - Normalized DP Trend 290 285 280 275 -

270 265 260

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N to Enclosure to NRC-15-0027 Division 2 Core Spray Pump Differential Pressure Trend Chart

PRR-012, Attachment 4, Div 2 Core Spray - Normalized DP Trend 290 285 280 275 270 265 260 04 o

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