ML18039A438

Forwards Summary of Plans & Schedule Re Completion of Quantitive Analysis of Adequacy of Stroke Times of Direct Current MOVs Under Design Basis Conditions.Summary Submitted in Response to RAI Re Insp Repts

ML18039A438
Person / Time
Site:	Browns Ferry
Issue date:	07/16/1998
From:	Crane C TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
50-259-98-03, 50-259-98-3, 50-296-98-03, 50-296-98-3, GL-89-10, NUDOCS 9807270403
Download: ML18039A438 (16)

Text

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ACCESSION NBR:9807270403 DOC.DATE: 98/07/16 NOTARIZED: NO DOCKET FACIL:50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH. NAME ' AUTHOR AFFILIATION CRANE,C.M. Tennessee, Valley Authority RECIP.NAME', RECIPIENT AFFZLIATION Records Management Branch (Document Control Desk)

SUBJECT:

Forwards summary of plans R schedule re completion of quantitive analysis of adequacy of stroke times of direct current MOVs under design basis conditions. Summary submitted in. res P onse to RAI re ins P re P ts.

DISTRIBUTION CODE: IE01D COPIES RECEIVED:LTR- ENCL SIZE:

TITLE: General (50 Dkt) -Insp Rept/Notice of Violation Response NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3-PD 1

• 1 DEAGAZZO,A 1 1 INTERNAL: ACRS 2 2 AEOD/SPD/RAB 1 1 AEOD TC 1 1, DEDRO 1 1 I CENTER 1 1 NRR/DRCH/HOHB 1 1 NRR PECB 1 1 NRR/DRPM/PERB 1 1 NUDOCS-ABSTRACT 1 1 OE DIR 1 1 OGC/HDS3 1 1 RGN2 FILE 1 1

'1 01'OAC EXTERNAL:'LITCO BRYCE,J H 1 1 1 NRC PDR 1 1 NUDOCS FULLTEXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTRO!

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Cl Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 Christopher M. (Chris) Crane Vice President, 8rowns Feny Nuclear Plant July 16, 1998 U.S. Nuclear Regulatory Commission ATTN:, Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of ) Docket Nos. 50-296 Tennessee Valley Authority )

BROWNS FERRY NUCLEAR PLANT (BFN) REPLY 'TO REQUESTED INFORMATION IN INSPECTION REPORT 50 259 I 2 60 I 2 96/98 03 During the subject inspection, the inspectors determined certain assumptions for implementing Generic Letter 89-10 for Unit 3 were not adequately justified. As a result, NRC requested TVA to submit its plans and schedule for obtaining and analyzing, applicable test data for certain motor operated valves (MOVs).

In addition, NRC requested TVA to submit its plans and schedule to complete a quantitative analysis of the adequacy of the stroke times of its Direct Current MOVs under design basis conditions.

The Enclosure to this letter complies with these requests.

There are no commitments contained in this letter.,

If you have any questions please call me at (256) 729-2636.

cerely C. M. rane closure See page 2

'7807270403 9807%6 PDR ADQCK 05000296 PDR p

4l U.S. Nuclear Regulatory Commission Page' July 16, 1998 Enclosure cc: (Enclosure)

Mr. H. O. Christensen, Branch Chief U ~ ST Nuclear Regulatory Commission 61 Forsyth Street, S.W.

Suite 23T85 Atlanta, Georgia 30303 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611 Mr. A. W. DeAgazio,-Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. E. H. Girard, Reactor Inspector U.S. Nuclear Regulatory Commission 61 Forsyth Street, S.W..

Suite 23T85 Atlanta, Georgia 30303 Mr. T. G. Scarbrough, Sr. Mechanical Engineer U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

~I ENCLOSURE TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNIT 3 REQUESTED INFORMATION ON BFN's STATUS FOR UNIT 3 GENERIC LETTER (GL) 89-10 ISSUES BACKGROUND:

BFN Calculation MD-Q0999-980001, "Design Input Parameters" formed the basis for valve factors selected for various valve groups in the BFN GL 89-10 program. During the development of the appropriate valve factors, it was determined that various types of information were available which could be used as the technical basis for valve factors. The objective was to obtain information which was directly applicable to BFN valves. Therefore, valve testing at BFN was considered the best available information.

Testing data from other TVA plants was considered desirable, since the data acquisition and analysis methods used were the same as those used't BFN. Beyond these two sources, definitive analysis of test data, from Electric Power Research Institute (EPRI) and NRC/INEL valve testing was also considered. EPRI report test data were cons'idered to have been performed at conditions similar to BFN's design basis accidents. After these data sources, test information from other utilities was considered. Due to variations in MOV program technical approaches, some utility sources were not considered directly applicable. For example, some utilities use valve factor while others use valve friction .

factor. However, information was obtained from the utilities where valve specific and data analysis methodology information were applicable.

TVA also participates in the Boiling Water Reactor Owner's Group Valve Technical Resolution Group which- includes 22 utility members. TVA's participation in this group was used to identify utilities that would have comparable valves and associated test data. It is not the intent of the design input parameters calculation to document every case where information was sought and not used.

In addition, BFN used two industry consultant firms for developing the valve factors used to meet the requirements of GL 89-10. These firms had access to a significant amount

0 of other utility data and provided this data for BFN use, where it was applicable. r BFN has expended significant effort to obtain industry data which can be used to support valve factors for BFN valves.

In cases, where the data is technically applicable, used ~

it was NRC GL 89-10 issues/TVA re lies TVA's implementation of Generic Letter 89-10 remained partly incomplete since TVA did not appear to satisfactorily obtain and/or analyze Motor-Operated Valve (MOV) test data to support the following assumptions for its MOVs:

ASSUMPTION 1 Assumption of 0.55 valve factor in calculating the design basis thrust requirements for gate valve group 3b and 7.

TVA's REPLY In development of the technical basis for valve factors for Group 3b .(Crane 900 pound gate valves), BFN found no valve test data available on valves with Stellite 21 hardfacing material. TVA procured Stellite 21 material valves to comply with sound AL2GV principles for reducing the amount of cobalt at BFN. TVA considered the test data from the EPRI TR-103119 "Friction Separate Effects Test Report" to be the best available data in regards to the performance of these materials. The EPRI program which generated this report, undertook an extensive review 'of various valve designs and materials. Appendix A of the EPRI report found that the populat'ion of valves with Stellite 21 hardfacing materials was small. A comparison of the data shows that the performance properties under similar contact stress and fluid conditions for Stellite 6 and Stellite 21 materials are very similar. .Therefore, BFN concluded that valve factors for Stellite 21 valves would not be significantly different than a valve of similar design which had Stellite 6 material.

EPRI performed .testing on a Crane 900 pound class valve with Stellite 6 hardfacing which was shown to exhibit a valve friction 'factor of 0.44. It was not practical for BFN to perform a differential pressure test for this valve since its function as the HPCI injection valve would potentially cause reactivity excursions which were deemed adverse to E-2

4l II reactor safety. Therefore, BFN added a 25% margin of safety on the Satellite 6 valve friction factor and thereby established the 0.55 valve friction factor selected for 'the Stellite 21 hardfacing materials valve.

Similarly, for Group 7 valves, BFN was unable to locate any available test data for valves which use Deloro hardfacing.

The primary differences between Deloro and Stellite 6 are that the Deloro friction coefficient (from material testing) does not decrease with increasing temperature, and that in edge-on-edge contact mode, the Deloro shows a greater susceptibility to mechanical damage. The BFN valves which contain the Deloro material are parallel seat valves which will not experience edge-on-edge contact. Therefore, the valve friction factor of 0.55 for these valves was used.

BFN is also aware that some valve testing with these Deloro hardfacing materials will be performed under the Joint Owner's Group Periodic Verification (JOG PV) program. TVA is a participant in the JOG PV program. Therefore,, TVA will monitor test data from the JOG PV program and incorporate data applicable to Deloro and Stellite 21 materials into the design input parameters calculation, as it becomes available. The differential pressure test program for the JOG PV program is currently scheduled for completion in 2003. Within three months of receipt of test data from the JOG PV program, TVA plans to incorporate the applicable data.

ASSUMPTION 2 Assumption of a 0.60 valve gate factor in calculating the design basis thrust requirements for gate valve group 11a and 11b.

TVA' REPLY The group 11a consists of 600 pound Walworth,valves of 6" and 20" sizes. TVA used test data from valves of similar

'esign (internal design and material type) as the basis for the valve friction factor. Information from EPRI Report TR-103237 R2 "EPRI MOV Performance Prediction. Program Topical Report," indicated that valve friction factors tend to decrease with increasing pressure class due to the. higher

,contact stresses, and with increasing valve size. A comparison of valve friction factors for this model of valve were made across a range of pressure classes and valve sizes. This data showed that valve friction factors ranged from 0.56 for 300 pound class valves to 0.45 for 900 pound E-3

0 ~I class valves. BFN established that the 0.6 valve friction factor was more conservative than the test data obtained for various pressure classes and valve sizes. In addition, BFN had reviewed valve, test data from NRC/INEL on a 6" 600 pound class valve which showed a valve friction factor of 0.27.

Therefore, the NRC/INEL valve friction factor enveloped BFN's valve friction factor of 0.6 for similar contact stress levels and fluid conditions.

The group 11b consists of 600 pound Walworth valves of 12" and 24" sizes. These valves are the same model as the valves in group 1la. The only difference between these two groups is the body and disc materials. The group 11b valves are stainless, and group 1la valves are carbon steel. Based on the valve application (i.e., low contact stresses and fluid temperatures) the stainless steel valves were not susceptible to any mechanisms which would induce "unpredictable" valve behavior. Therefore, BFN uses the same valve friction factor as for group 1la.

An additional attempt at obtaining test data for 600 pound class Walworth valves was made. Using the EPRI GIDATA database, various utilities with these types of valves were contacted. None of the utilities contacted had differential pressure test data on 600 pound Walworth valves. Most of the facilities contacted used a valve friction factor for the 600 pound Walworth valves based on test data from 300 pound and 900 pound class valves. Test data from another TVA facility was located for 600 pound'alworth valves of 16" size which showed a maximum valve. friction factor of 0.5. Therefore, the additional review confirmed that a 0.6 valve friction factor is reasonable for the group 1la and lib valves.

ASSUMPTION 3 Assumption of a 1.2 valve factor in calculating the design basis 'thrust requirements for globe valve group 2 and 3.

TVA~s REPLY

, TVA used the guidance provided by the EPRI Report TR-103237 for globe valve performance data. This report addresses balanced and unbalanced disc globe valve designs. The BFN globe valves in groups 2 (guide based) and 3 (seat based) are unbalanced disc design valves. EPRI test data for unbalanced disc globe valves show that the internal disc design is a major .contributor to differential pressure thrust requirements. The internal disc designs for the BFN

Ol.

valves were evaluated in accordance with the guidance provided in this EPRI report. Table 6-1, of the EPRI report, shows that the differential pressure force uses a valve safety factor of 1.0 for seat and guide based valves.

BFN added a 20% margin of safety to derive the 1.2 valve safety factor used for globe valve thrust requirements.

Therefore, TVA considers the 1.2 valve safety factor reasonable for the group '2 and 3 globe valves.

ASSUMPTXON 4 Assumption of a 10 percent rate of loading in calculating design basis thrust requirements for HOVs with roller screw stem nuts.

TVA' REPLY TVA is aware of the testing being performed at another nuclear facility. TVA contacted the utility and was informed that the testing will be complete by September 1998-. Therefore, within three months of receipt of the test data, TVA plans to review the test data, and make adjustments to the rate of loading value for .roller screw stem nuts.

DC MOVs In addition, NRC requested TVA to submit its plans and schedule to complete a quantitative analysis of the adequacy of the stroke times of its Direct Current (DC) HOVs under design basis conditions.

TVA's REPLY TVA has perfor'med a quantitative analysis of the BFN DC MOVs. This analysis used the design basis conditions for valve operation and has determined that, the valves with specific stroke time requirements are capable of performing their safety function within the stroke times required.

This analysis is available for NRC review onsite.

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