ML20138C850

Safety Evaluation Authorizing Proposed Alternative to Vibration Measurement Requirements of OM-6,paragraph 4.6.4 (B),For Standby Svc Water Pumps & Diesel Fuel Oil Transfer Pumps,Per 10CFR50.55a(a)(3)(ii)

ML20138C850
Person / Time
Site:	River Bend
Issue date:	04/28/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20138C834	List: ML20138C827 ML20138C850
References
NUDOCS 9704300222
Download: ML20138C850 (4)

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• p 4 UNITED STATES E NUCLEAR REGULATORY COMMISSION E WASHINGTON, D.C. 20086 4001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE TESTING PROGRAM RELIEF RE0 VEST 33-VRR-1 REVISION 0 ENTERGY OPERATIONS INC.

RIVER BEND STATION UNIT 1 4 DOCKET NUMBER 50-458 l

1.0 INTRODUCTION

i The Code of Federal Regulations,10 CFR 50.55a, requires that inservice testing (IST) of certain ASME Code Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel  :

Code and applicable addenda, except where relief has been requested and granted or proposed alternatives have been authorized by the Commission <

pursuant to 10 CFR 50.55a (f)(6)(i), (a)(3)(i), or (a)(3)(ii). In order to obtain authorization or relief, the licensee must demonstrate that: .

l (1) conformance is impractical for its facility; (2) the proposed alternative l

i provides an acceptable level of quality and safety; or (3) compliance would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. Section 50.55a (f)(4)(iv) provides that inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in 10 CFR 50.55a(b), subject to the limitations and modifications listed, and subject to Commission approval. Nuclear Regulatory Commission (NRC) guidance contained in Generic Letter (GL) 89-04, " Guidance on Developing Acceptable Inservice Testing Programs," provided alternatives to the Code requirements determined to be acceptable to the staff and authorized the use of the l alternatives in Positions 1, 2, 6, 7, 9, and 10 provided the licensee follow i

i the guidance delineated in the applicable position. When an alternative is proposed which is in accordance with GL 89-04 guidance and is documented in the IST program, no further evaluation is required; however, implementation of the alternative is subject to NRC inspection.

Section 50.55a authorizes the Commission to grant relief from ASME Code requirements or to approve proposed alternatives upon making the necessary j

findings. The NRC staff's findings with respect to granting or not granting the relief requested or authorizing the proposed alternative as part of the licensee's IST program are contained in this Safety Evaluation (SE).

The first ten-year interval for the River Bend station began on June 16, 1986.

Because of an approved extension to their interval in a NRC letter dated l November 13, 1995, the first ten-year interval will'end on December 1, 1997.

The current IST program is-based on the requirements of the 1980 Edition through the winter 1981 addenda of the ASME Code and reliefs as may have been i

i ENCLOSURE 9704300222 970428 PDR ADOCK 05000458 P PDR

granted by the NRC. By letter dated January 2, 1991, the NRC issued the review of the licensee's first ten year interval inservice testing program and provided certain reliefs; all pumps in the program were granted the relief to  !

use OH-6 for measuring vibration velocity as the test requirement. l l

2.0 RELIEF RE0 VEST PRR-006 The licensee has requested relief from the vibration measurement requirements 1

of OMa-1988, Part 6 (OM-6), Paragraph 4.6.4(b), for the standby service water pumps and the diesel fuel oil transfer pumps listed below. Paragraph 4.6.4 i requires that vertical line shaft pump measurements shall be taken on the upper motor bearing housing in three orthogonal directions, one of which is l the axial direction. The licensee has proposed to take vibration measurements l in three orthogonal directions in a location that provides valid indication of motor vibratory motion in close proximity to the upper motor bearing housing.

SWP-P2A EDF-PIA SWP-P2B EDF-PIB SWP-P2C EDF-PIC SWP-P2D l 2.1 Licensee's Basis for Reauestina Relief The licensee states:

1 The standby service water pump motors are totally enclosed, l weatherproof induction motors that are equipped with housing covers i which completely enshroud the motor upper bearing housing. The l housing cover precludes vibration measurements from being taken  ;

directly on the upper bearing housing.

The diesel fuel oil transfer pumps are also equipped with housing ,

covers that preclude vibration measurements from being taken i directly on the upper motor bearing housing.

1 Removing the upper bearing motor housing covers for routine  ;

vibration readings would compromise the design configuration and the  ;

operation of the pump motors. Cooling, thermocouples and other j motor sensors would be disabled. Also, the test configuration would I differ greatly from normal configuration which would invalidate the test data obtained to prove operational readiness of the pump. This option is not practical.

Modifying the upper bearing housing cover to include an access port or installing vibration sensors is not preferred since these methods would change component configuration without a compensating increase in safety. The transmission path for the alternate vibration points will not attenuate the vibration response or amplitude, therefore providing equivalent data without disturbing the equipment operation or design.

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3.2 Alternate Testina The licensee proposes:

Vibration measurements will be taken in three orthogonal directions in a location that provides valid indication of motor vibratory motion in close proximity to the upper motor bearing housing.

On the standby service water pumps, the upper measurements will be taken on a lifting lug that is integral to the motor stator housing. The lifting lug is structurally rigid and provides transmissibility of the motor vibratory motion. The vibration measurements will be taken in three orthogonal directions on the lifting lug.

On the diesel fuel oil transfer pumps the upper measurements will be taken on the motor stator housing which is rigidly connected to the motor bearing housing. The vibration measurements will be taken in three directions on the motor stator in close proximity to the motor bearing housing.

3.3 - Evaluation The Code (OM-6) requires that quarterly vibration measurements be taken on vertical line shaft pumps during their regular inservice test. Since the actual pumps are submerged in water, the Code requires that vibration measurements be taken on the upper motor bearing housing in three orthogonal directions, one of which is the axial direction. The licensee states that access to the upper motor bearing housing for both the standby service water

! and diesel fuel oil transfer pumps is impeded by housing covers on all seven -

pumps. It would be a hardship without a compensating increase in safety for the licensee to modify the pump to perform the vibration measurements if there were comparable locations on the pumps to collect vibration data.

The licensee has proposed to take vibration measurements from alternate locations that would provide vibration data that are not attenuated from the upper motor bearing housing. For the standby service water pumps, the licensee will take vibration measurements from a lifting lug that is integral to the motor stator housing. The vibration measurements for the diesel fuel oil transfer pumps would be taken from the motor stator housing which is rigidly connected to the motor bearing housing. The licensee states that measurements will be taken in three orthogonal directions on all pumps as required by the Code.

The licensee's alternate locations for taking vibration measurement provide rigid _ structural contact to the motor bearing housing. The locations should i not be subject to dampening effects that could mask potential degradation. '

! Therefore, the licensee's proposed alternative locations for taking vibration measurements provide a reasonable assurance of operational readiness.

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_4-3.4 Conclusion j

The proposed alternative to the vibration measurement requirements of OH-6,  !

Paragraph 4.6.4(b), for the standby service water pumps and the diesel fuel j oil transfer pumps is authorized pursuant to 10 CFR 50.55a (a)(3)(ii) based on i the determination that the proposed alternative to the Code requirements provides reasonable assurance of operational readiness, and compliance with the specified requirements results in a hardship without a compensating increase in the level of quality and safety. i i

Principal Contributor: Joseph Colaccino j Odte: April 28, 1997 l

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