HL-5758, Forwards Response to NRC 990129 RAI Re GL 96-05 Program at Ei Hatch Nuclear Plant

Forwards Response to NRC 990129 RAI Re GL 96-05 Program at Ei Hatch Nuclear Plant

ML20205P566
Person / Time
Site:	Hatch
Issue date:	04/09/1999
From:	Sumner H SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-05, GL-96-5, HL-5758, NUDOCS 9904200218
Download: ML20205P566 (7)

Text

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lawis Sumner Southern Nuclear Vice President Operating Company. Inc.

Hatch Project Support 40 invemess Parkway

Post Offico Box 1295 Birmingham. Alabama 35201 Tel 205.992.7279 Fax 205.992.0341 l

SOUTHERN h COMPANY Encry to Serve hurWorld" April 9, 1999 Docket Nos. 50-321 HL,-5758 50 366 U.S. Nuclear Regulatory Conunission l ATTN: Document Control Desk l Washington, D.C. 20555

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Edwin I. Hatch Nuclear Plant Response to Request for Additional Information:

Generic Letter 96-05 Ladies and Gentlemen:

By letter dated January 28,1999, the Nuclear Regulatory Commission (NRC) requested additional

information regarding the Generic Letter (GL) 96-05 program at Edwin I. Hatch Nuclear Plant.

The Enclosure provides the specific NRC questions and the Southern Nuclear Operating Company responses.

Mr. H. L. Sumner, Jr. states he is Vice President of Southern Nuclear Operating Company and is j

authorized to execute this oath on behalf of Southern Nuclear Operating Company, and to the best of his knowledge and belief, the facts set forth in this letter are true. f

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Respectfuliy submitted, 9 gg /h j l

H. L. Sumner, Jr. j h

• l l Sworn to and subscribed before me this day of 1999.  ;

fliw ch. b8J Notary Public My Commission Expires: wcoinccionEXPir:S AUCILT3.1909 l l

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Enclosure:

Response to Request for Additional Information: Generic Letter 96-05

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cc: (See next page.) , ([

• 9904200218 990409 " '

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U.S Nuclear Regulatory Commission Page 2 l April 9, 1999 cc: Southern Nuclear Oocratina Company Mr. P. H. Wells, Nuclear Plant General Manager SNC Document Management (R-Type A02.001)

U.S. Nuclear Regulatory Commissign. Washinntonm D C l Mr. L. N. Olshan, Project Manager - Hatch

.QS. Nuclear Reculatory Commission. Region II Mr. L. A. Reyes, Regional Administrator Mr. J. T. Munday, Senior Resident Inspector - Hatch l,

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1 Enclosure l

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Edwin 1. Hatch Nuclear Plant Response to Request for Additional Information:

Generic Letter 96-05 NRC Ouestion No. I Based on the NRC staff's review of Southern Nuclear Operating Company's (SNC's) submittal and the results of NRC Inspection Report No. 50-321 & 366/95-25, the staff, in its February 29, 1996, letter, closed its review of the motor-operated valve (MOV) program implemented at the Edwin 1. Hatch Nuclear Plant, Units I and 2 (Hatch). This program has been implemented in ,

response to Generic Letter (GL) 89-10, " Safety-Related Motor- Operated Valve Testing and Surveillance." In the February 29,1996, letter, the staff discussed certain aspects of SNC's MOV program to be addressed over the long-term. For example, the staff noted that SNC's plan to (1) monitor industry data to provide further confidence in the design-basis thrust requirements for valves 2B31F031 A/B, IB21F016, and iB21F019; and (2) eliminate sharp internal valve edges and verify proper internal clearances of valves that must function under blowdown flow conditions. Further, the NRC inspection report noted in the close-out of inspector follow-up item (IFI) 50-321 and 366/95-02-02, that SNC had committed to increase the margin for valve IG31F004 during the spring 1996 outage. SNC should describe briefly the actions taken to address the specific long-term aspects of the MOV program at Hatch noted in the NRC's letter and inspection report.

SNC Response (1) Valves IB21-F016 and IB21-F019 were replaced with Anchor Darling valves having larger actuators per DCR 96-005, which was completed in November 1997. The replacement valves have radiused edges.

A larger motor was installed on valve 2B31-F031 A/ B per DCR 96-006, which was completed in March 1997.

The monitoring of industry data is accomplished through SNC's participation in the JOG program.

(2) To address the issue of sharp edges in gate valves (affecting thrust requirements), the following steps have been included in plant maintenance Procedure 52CM-MME-011-OS:

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. l i Enclosure Response to Request for Additional Information:

. Generic Letter 96-05 NOTE Thefollowing steps are required ONLY on 1REll-F008, inEl1 F009, IDE41-F002, IDE41-F003, laE51-F007,1RE51 F008, IMG31-F001, lag 31 F004, IB21-F016 and 1B21-F019; however, they are recommendedfor ALL gate valves and will nonnally be perfonned at any time the valves are openfoi repair AND the work scope will allow implementation. Any disc usedfor replacement of a disc with existing radinsed corners must have the radiused corners cut on the new disc before installation.

7.7.5 Removal ofSharp Edges on Gate Wdve Discs, Seats and Guides

'7.7.5.1 Inspect male andfemale guiding surfaces of the valve disc, seat and the in-body disc guides to ensure that all applicable mating edges are rounded off per Attachment 6.

7.7.5.2 IF edges are NOT within the specifications ofAttachment 6, machine OR hand-grind the applicable corners to obtain an acceptable radius.

Also, during the Spring 1999 outage, the new wedges and guides going inta IG31-F001 and IG31-F004, per DCR 97-039, will have radiused edges.

In response to IFl 95-02-02, the margin for valve IG31-F004 was primarily increased with MWO l-95-1383, which repacked the valve. Having a iower packing load increased margin. In addition, when the Valve Operation Test and Evaluation System (VOTES) test was performed under MWO l-95-2819 (April. I 1,1996), the torque switch was raised from 3.0 to 3.5, thereby increasing margin. The current margin, based upon the Joint Owners Group PV progam method, is over 10%, which is considered a high margin.

The new wedge and guide design for valve IG31-F004 should have a lower valve factor, as shown by Wyle/ Crane /Com Ed blowdown test data. In addition, valve IG31-F004 is being changed to " limit close," which will allow use of full motor capability.

' NRC Ouestion No.2

.The JOG program focuses on the potential age-related increase in the thrust or torque required to

' operate valves under their design-basis conditions. In'the NRC's safety evaluation dated October 30,1997, on the JOG program, the NRC staff specified that licensees are responsible for addressing the thrust or torque delivered by the MOV motor actuator and its potential degradation. . SNC should describe the plan at Hatch for ensuring adequate ac and de MOV motor actuator output capability, including consideration of recent guidance in Limitorque Technical Update 98-01 and its Supplement 1.

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Enclosure

. Response to Request for Additional Information:

Generic Letter 96-05 SNC Resoonse Lim torque Technical Update 98-01'and its Supplement i Plant Hatch has revised the methodology used in the Motor Operated Valve Torque Switch Setting Guide, A-43830, Rev. 5, to incorporate the guidance of Limitorque Technical Update 98-01 and its Supplement 1, for calculating the torque capability of ac-powered Limitorque actuators. All active safety function MOVs were verified capable of performing their safety functions. In addition, modifications and/or switch setting changes to improve margins reduced by the revised methodology have been completed.

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DC Motor Gearing Capability

' Plant Hatch currently uses the Limitorque methodology to ensure d4 motor actuators provide sufficient capability to cycle MOVs under design basis conditions. Plant Hatch is participating in the BWROG. Valve Technical Resolution Group (VTRG) effort to assess output capability and

- stroke time for MOVs with de motors. This effort will develop a comprehensive methodology that addresses industry concerns surrounding' actuators with de motors. Available motor and actuator test data will be considered in validating the methodology. Limitorque has agreed to work with the BWROG VTRG in completing this task.

Potential Degradation of MOV Actuator Delivered Thrust or Toraue l Plant Hatch will continue to:

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1. Perform 2ppropriate preventative maintenance activities.

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l. 2. Perform actuator refurbishment.as needed.

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3. Perform periodic static diagnostic testing of MOVs to confirm MOV capability and -

proper control switch settings consistent with design calculations.

'4. Apply appropriate design considerations or margins to account for actuator degradations such as stem lubrication degradation, spring pack relaxation, and rate of

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5. Perform biennial reviews to ensure design assumptions and maintenance practices remain appropriate.

During MOV testing, plant Procedure 53IT-TET-002-0S requires measuring thrust and torque  ;

during all tests, unless impractical. The combination of thrust and torque data taken on a regular basis provides pertinent information useful in detecting. changes in MOV performance. Any change in performance can be detected during either test review or biennial review.

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• - Enclosure '

. Response to Request for Additional Information:

Generic Letter 96-05 I

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Preventative Maintenance

To minimize the impact of aging on MOV actuator performance, Plant Hatch performs periodic maintenance on safety-related MOV actuators that includes:

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Stem lubrication.

l Actuator grease inspections.

Environmental qualification inspections.

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Motor control center inspections.

l These activities are performed to ensure the actuator either is in or is returned to a known

. condition.

Actuator Refurbishment

' Actuator refurbishment is performed on an "as needed basis" as identified by periodic inspections. This activity is assumed to return the actuator to an "as new" condition, j

! Stem Factor Degradation l

l Plant Hatch Procedure 53IT-TET-002-0S currently includes margin in MOV switch settings to account for 18 months of degradation in stem friction factor. Stems for GL 89-10 valves are lubricated every 18 months, thus returning them to a nondegraded state. As-found test data for MOVs are collected on an ongoing basis to confirm adequacy of the established design assumptions. Each MOV's individual assumption is verified each time it is tested, and the data are entered into the MOV database. Each design assumption is reviewed on a biennial basis per  ;

procedure 50AC-MNT-008-0S to ensure the design input remains valid based upon current data. 1 I

Rate ofImading (ROL)

For non-DP tested MOVs, Plant Hatch calculations include a load sensitive behavior (LSB) design assumption sufficient to account for ROL. This design assumption is reviewed on a biennial basis per procedure 50AC-MNT-008-0S to ensure the design input remains valid based

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upon current data. j i

For all valves DP tested, calculations are performed to determine the ROL. The calculated value j

.is compared to the current assumption for ROL of that valve. If the current calculan:d value is l

higher than the assumption, the design assumption is revised to the higher value. The calculated i value is t'so input to the MOV database. This design assumption is reviewed on a biennial basis HL-5758 E-4 )

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. Enclosure Response to Request for Additional Information: -l Generic Letter 96-05 i

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per Procedure 50AC-MNT-008-0S to ensure the design input remains valid based on current j data, i

i Springnack Relaxation l

l Plant Hatch Procedure 531T-TET-002-0S includes consideration for springpack relaxation in l MOV calculations and switch settings consistent with guidance in Limitorque Technical Update 93-02.

Motor Degradation At Plant Hatch, motor power traces from the motor power monitor on motors with the potential ,

for magnesium rotor corrosion are periodically collected and reviewed to trend for degradation.

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Plant Hatch is involvul in various industry organizations to keep apprised of the latest available information concerning MOV performance. Plant Hatch will continue to incorporate necessary enhancements into the MOV program based upon evaluation of the most current information. j i

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