ML13045A290

Relief from the Requirements of the ASME OM Code

ML13045A290
Person / Time
Site:	Oconee
Issue date:	02/15/2013
From:	Robert Pascarelli Plant Licensing Branch II
To:	Gillespie P Duke Energy Carolinas
Boska, J P
References
TAC ME8849, TAC ME8850, TAC ME8851
Download: ML13045A290 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 February 15,2013 Mr. Preston Gillespie Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752 SUB.JECT: OCONEE NUCLEAR STATION, UNITS 1,2 AND 3, RELIEF FROM THE REQUIREMENTS OF THE ASME OM CODE (TAC NOS. ME8949, ME8950, AND ME8951)

Dear Mr. Gillespie:

By letter dated June 18, 2012, Duke Energy Carolinas, LLC, the licensee, submitted request ON-SRP-HPI-03 to the U.S. Nuclear Regulatory Commission (NRC). The licensee requested authorization to use an alternative vibration measurement method rather than the method required per the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) for nine pumps (three per unit) at the Oconee Nuclear Power Station (ONS), Units 1, 2, and 3. Relief Request ON-SRP-HPI-03 is applicable to the fifth 1O-year inservice testing (1ST) program interval at ONS, Units 1, 2, and 3. The licensee requested to use the proposed alternative on the basis that complying with the current ASME OM Code requirements is impractical and would create unnecessary burden.

As set forth in the enclosed safety evaluation, the NRC staff has determined that requiring the licensee to meet the requirements for the vibration measurement locations for these pumps as noted in the ASME OM Code results in a hardship without a compensating increase in the level of quality and safety. The NRC staff finds that allowing vibration measurements at the requested locations provides reasonable assurance of the operational readiness of these pumps. Therefore, pursuant to 10 CFR 50.55a(a)(3)(ii), the NRC staff authorizes the proposed alternative in request ON-SRP-HPI-03 for the remainder of the fifth 1ST interval for ONS Units 1, 2, and 3 which is scheduled to end on June 3D, 2022.

P. Gillespie -2 If you have any questions, please contact the Project Manager, John Boska, at 301-415-2901, or via email at John.Boska@nrc.gov.

Sincerely, Robert J. Pascarelli, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287

Enclosure:

As stated cc w/encl: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUEST ON-SRP-HPI-03 FOR THE FIFTH 10-YEAR INTERVAL INSERVICE TESTING PROGRAM DUKE ENERGY CAROLINAS, LLC OCONEE NUCLEAR STATION, UNITS 1,2, AND 3 DOCKET NOS. 50-269, 50-270, AND 50-287

1.0 INTRODUCTION

By letter dated June 18, 2012 (Agencywide Documents Access and Management System Accession No. ML12173A312), Duke Energy Carolinas, LLC, the licensee, submitted request ON-SRP-HPI-03 to the U.S. Nuclear Regulatory Commission (NRC). The licensee requested authorization to use an alternative vibration measurement method rather than the method required per the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) for nine pumps (three per unit) at the Oconee Nuclear Power Station (ONS), Units 1, 2, and 3. Relief Request ON-SRP-HPI-03 is applicable to the fifth 1O-year inservice testing (1ST) program interval at ONS, Units 1, 2, and 3. The licensee requested to use the proposed alternative on the basis that complying with the current ASME OM Code requirements is impractical and would create unnecessary burden.

2.0 REGULATORY REQUIREMENTS Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.55a(f), "Inservice Testing Requirements," requires, in part, that the 1ST of certain ASME Code Class 1,2, and 3 components must meet the requirements of the ASME OM Code and applicable addenda, except where alternatives have been authorized pursuant to 10 CFR 50.55a(a)(3)(i) or (a)(3)(ii).

In proposing alternatives, a licensee must demonstrate that the proposed alternatives provide either an acceptable level of quality and safety (10 CFR 50.55a(a)(3)(i)) or compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety (10 CFR 50.55a(a)(3)(ii)). Section 50.55a allows the NRC to authorize alternatives to ASME OM Code requirements upon making the necessary findings.

The ONS Units 1, 2, and 3 fifth ten-year 1ST program interval commenced on July 1, 2012 and ends on June 30, 2022. The applicable ASME OM Code edition and addenda for ONS Units 1, 2, and 3 is the 2004 Edition through the 2006 Addenda.

Enclosure

-2 The NRC staff's findings with respect to authorizing the alternative, ON-SRP-HPI-03, are given below:

3.0 TECHNICAL EVALUATION

3.1 Licensee's Alternative Request ON-SRP-HPI-03 ISTB-3540(b) , "Vibration", states, "On vertical line shaft pumps, measurements shall be taken on the upper motor-bearing housing in three approximately orthogonal directions, one of which is the axial direction."

Alternative vibration measurements were requested for the following Group A vertical line shaft pumps:

• 1HPIPU0001 -High Pressure Injection (HPI) Pump

• 1HPIPU0002 -HPI Pump

• 1HPIPU0003 -HPI Pump

• 2HPIPU0001 -HPI Pump

• 2HPIPU0002 -HPI Pump

• 2HPIPU0003 -HPI Pump

• 3HPIPU0001 -HPI Pump

• 3HPIPU0002 -HPI Pump

• 3HPIPU0003 -HPI Pump Licensee's Reason for the Request Performing the ASME OM Code-required vibration measurements on the upper motor bearing housing for the subject pumps is a hardship on the basis of inaccessibility due to the location and design features of the motors. The plant design does not provide access to the top of the motors for the subject pumps and the plant would need to be modified to provide a permanent ladder and platform for access to the bearing on each of the nine motors to allow obtaining the ASME OM Code vibration measurements. Also, the upper motor bearing housing is contained within a cone shaped fiberglass protective shroud which obstructs access to the bearing housing and prevents performance of the axial vibration measurement. In order to perform the required measurements, the component would need to be redesigned to eliminate the shroud or the shroud would have to be removed for each test. Any modifications to the plant and to the upper motor bearing housings represent a hardship and create unnecessary burden. In addition, removal of the shroud during pump operation to provide direct access to the bearing housing would create an additional equipment concern due to the potential for foreign material intrusion and component damage.

Vibration measurements taken on the fiberglass shroud would not provide useful or meaningful information.

Licensee's Proposed Alternative The licensee proposed to take quarterly vibration readings at two locations on the motor and two locations on the pump. Locations on the motor are at the inboard bearing and approximately midway on the motor housing. Locations on the pump are at the pump inboard bearing and on the pump stand. At each location, vibration measurements are recorded in two approximately

- 3 orthogonal directions perpendicular to the rotating shaft. These locations have been chosen for monitoring, in an effort to identify specific failure modes, and have proven to provide early indication of abnormal pump/motor performance. Monitoring of the pump/motor vibrations at these locations will ensure the health of the pump is sufficiently examined.

The ASME OM Code imposes more stringent hydraulic acceptance criteria on these vertical line shaft pumps than for horizontal centrifugal or positive displacement pumps. This hydraulic acceptance criteria places more emphasis on detection of degradation through hydraulic test data than through mechanical test data. Application of the ASME OM Code hydraulic testing acceptance criteria along with radial vibration monitoring in the areas described above will provide adequate data for assessing the condition of the subject pumps and for monitoring degradation.

Therefore, reasonable assurance of operational readiness for these pumps will be maintained.

3.2 NRC Staff's Evaluation The ASME OM Code recognizes the value of implementing a vibration analysis strategy for monitoring vertical line shaft pumps by requiring measurements to be taken on the upper motor bearing housing in three orthogonal directions, one of which is the axial direction. The licensee proposes to obtain vibration measurements on the nine HPI vertical line shaft pumps 1HPIPU0001, 1HPIPU0002, 1HPIPU0003, 2HPIPU0001, 2HPIPU0002, 2HPIPU0003, 3HPIPU0001, 3HPIPU0002, and 3HPIPU0003 at two locations on the motor and two locations on the pump. The locations on the motor are at the motor inboard bearing housing area and approximately midway on the motor housing. The pump locations are at the pump inboard bearing and on the pump stand. Vibration measurements will be recorded in two orthogonal directions at the stated locations. The vibration measurements will be tracked and trended along with the hydraulic performance test data. Axial vibration data will not be obtained. The licensee stated that axial measurement at the upper motor bearing is difficult due to an obstruction from a fiberglass protective shield which protects the upper motor from the elements. Accessing the upper motor bearing housing would require fabrication of scaffolding and a redesign of the protective fiberglass shield so that it could be removed.

Obtaining vibration measurements in two orthogonal directions at the inboard motor bearing area and midway on the motor housing as well as two orthogonal directions at the pump inboard bearing and on the pump stand will provide performance data on the upper and lower bearings and overall pump and motor assembly. Parameters such as bearing health, pump/motor unbalance, pump/motor looseness, electrical faults, and resonance issues can be monitored using these measurement points. The licensee has obtained vibration measurements at these locations for these pumps and motors in the previous 1ST interval. Measuring vibration at these locations has proven to provide early indication of abnormal pump/motor performance. The collected data at two orthogonal locations on the motor and two orthogonal locations on the pump, coupled with the trending of pump hydraulic performance data, provides an acceptable alternative for monitoring component health.

Requiring the licensee to meet the requirements for the vibration measurement locations for these pumps as noted in the ASME OM Code results in a hardship without a compensating increase in the level of quality and safety. These pumps operated without notable degradation while measuring vibration at the requested alternate locations during the previous 1ST interval. Based on the good performance history of these pumps while using the alternate vibration measurement locations and the acceptance by the NRC staff of alternate vibration measurement locations for

-4 other pumps and motors for other licensees, the staff finds that measuring vibrations at the locations requested by the licensee for these pumps and motors is acceptable. Allowing vibration measurements at the requested locations provides reasonable assurance of the operational readiness of these pumps.

4.0 CONCLUSION

As set forth above, the NRC staff determines that the proposed alternative, in request ON-SRP-HPI-03, provides reasonable assurance that HPI pumps 1HPIPU0001, 1HPIPU0002, 1HPIPU0003. 2HPIPU0001, 2HPIPU0002. 2HPIPU0003, 3HPIPU0001. 3HPIPU0002. and 3HPIPU0003 are operationally ready. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR SO.SSa(a)(3)(ii). All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject request remain applicable.

Therefore. the NRC staff authorizes the proposed alternative in request ON-SRP-HPI-03 for the remainder of the fifth 1ST interval for ONS Units 1, 2, and 3 which is scheduled to end on June 30, 2022.

Principal Contributor: R. Wolfgang, NRR/DE Date: February 1S, 2013

P. Gillespie -2 If you have any questions, please contact the Project Manager, John Boska, at 301-415-2901, or via email at John.Boska@nrc.gov.

Sincerely, IRA!

Robert J. Pascarelli, Chief Plant licensing Branch 11-1 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287

Enclosure:

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