ML20205M131
| ML20205M131 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 04/02/1999 |
| From: | Hughey W ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20137H933 | List: |
| References | |
| 50-416-96-03, 50-416-96-3, GL-89-10, GL-96-05, GL-96-5, GNRO-99-00030, GNRO-99-30, NUDOCS 9904150122 | |
| Download: ML20205M131 (18) | |
Text
= Entergy y3"~ 1
, W.K.Hughey April 2, 1999 -
U.S. Nuclear Regulatory Commission Mail Station P1-37 Washington, D.C. 20555 Attention: Document Control Desk
Subject:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 l
l Response to Generic Letter (GL) 96-05 j Request for AdditionalInformation
]
GNRO-99/00030 6 Gentlemen:
By letter dated February 1,1999 (GNRI-99/00002), the NRC requested additional l information from Grand Gulf Nuclear Station (GGNS) regarding GL 96-05, " Periodic j Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves" This l information was discussed during a conference call with the NRC on January 26,1999, and ;
the responses for these questions are documented and attached to aid the NRC as it i completes its GL 96-05 review for GGNS.
l Please contact Ms. Rita Jackson at (601) 437-2149 if you have questions regarding this submittal. !
Yours truly, \ lI i
hh WKH/RRJ attachment: Response to NRC RAI for GL 96-05 7
cc: (See Next Page)i g4150122990402 p ADOCK 05000416 PDR -f i l l v ,) , ' ' p, : i *. { ); t it .( j ri k / f . _, ) l, .i
l GNRO-99/00030 Page 2 of 3 cc: Ms. J. L. Dixon-Herrity, GGNS Senior Resident (w/a) Mr. L. J. Smith (Wise Carter) (w/a) Mr. N. S. Reynolds (w/a) Mr. H. L. Thomas (w/o) Mr. E. W. Merschoff (w/a) Regional Administrator
'J.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 Mr. S. P. Sekerak, Project Manager (w/2)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 13H3 Washington, D.C. 20555
GNRO 99/00030 Page 3 of 3 bec: File (LCTS/RPTS) (w/a) File (Hard Copy) (w/a) File (Central) (w/a) (22 ) ccmail: Mr. S. J. Bethay (w/a) Mr. C. A. Bottemiller (w/a) Mr. S A. Burris (w/a) Mr. R. W. Byrd (w/a) Mr. L. F. Daughtery (w/a) l Mr. W. A. Eaton (w/a) Mr. E. C. Ewing (w/a) l Mr. W. K. Hughey (w/a) Mr. D. E. James (w/a) Mr. R. J. King (w/a) Mr. C. W. Lambert (w/a) , Mr.C. M. Renfroe (wla) Mr. J. C. Roberts (w/a) Mr. J. J. Turner (w/a) Mr. J. D. Vandergrift (w/a) Mr. J. E. Venable (w/a) Mr. M. D. Withrow (w/a) Mr. W. T. White (w/a) 1 I l l
i l Attachment to GNRO 99/00030 Response to NRC Request for AdditionalInformation Generic Letter 96-05
- 1. In NRC inspection Report No. 50-416/96-03 (IR96-03) issued March 19,1996, the NRC staff closed its review of the motor-operated valve (MOV) program implemented at GGNS in response to GL 89-10. In the inspection report, the NRC staff discussed certain aspects of the licensee's MOV program to be i addressed over the long term, with some of these aspects addressed in IR 96- l 20 dated January 8,1997. GGNS is requested to address the following:
A. The adequacy for blowdown of the thrust prediction model that remains open in IR 96-20 as IFl 50-416/96003-01. ' Response: GGNS feels that this issue was adequately addressed in the letter written to Mr. Tom Scarbrough from Dr. Nabil Shauki on the subject of GGNS's GL 89-10 program. The letter discusses Siemen's grouping methodology and how it would identify major damage that would lead to unpredictable valve i behavior. The unpredictability question also appears to have been addressed in the position paper from Wyle Labs addressing NRC concerns regarding the GGNS grouping program. The position paper was issued February 22,1996 (Reference Number 45258R96), with NRC concern #3 being the question on valve damage. Appropriate portions of these referenced documents are attached as appendices. B. The justification of the Powell gate valve factors remains open in IR 96-20 and also in IFl 50-416/96003-01. Response: Additional dp testing per NRC request was conducted on 2 MOVs in Powell GA1600/900 pound class, as well as on 2 other MOVs in the Powell GA1150 pound class. Engineering Reports GGNS-98-0048 (600/900 GA1 class) and GGNS-99-0006 (150 GA1 class) document the test results. The results indicate that the valve factors of 0.5 (600/900 class) and .62 (150 class) supplied by Siemen for GGNS's grouping methodology are bounding. Valve Class Calculated Valve Grouping Valve Factor Factor E12F027A 600 GA1 0.48 0.50 E12F042C 600 GA1 0.50* 0.50 P41F015A 150 GA1 0.49 0.62 P41F0158 150 GA1 0.46* 0.62
*Value is extrapolated
I Attachment to GNRO 99/00030 C. The as-found testing for stem lubrication degradation that was not addressed in IR 96-20. Response: The inspectors were looking for long term justification for not having a value dedicated to stem lube degradation. GGNS has been performing "as found" coefficient of friction (COF) testing on MOVs that have not been modified, have not been worked on, and those that have been previously VOTES tested. To date data is hmited due to a large population of MOVs being previously MOVATS (displacement measuring device (DMT) and loadcell) tested. Many other MOVs have had actuator modifications or valve modifications for margin improvements and were not "as found" tested. The limited test data shows that the "as found" COF was less than the previous "as left" COF. This was seen in all tests except one. On this particular MOV, the "as found" COF increased by 8.9% over the previous "as left" COF. It should be noted that this MOV has always had a high COF and is at the maximum on its torque output. Currently, the plan is to modify this MOV in RFO 10. Based on these results, GGNS still believes that 25% of packing load is sufficient to bound stem lube degradation. Collecting "as found" data for the effects for stem degradation is part of GGNS's trending program and will continue to be collected. The amount of "as found" COF data should increase since most of the previous MOVATS test with DMT/loadcell methodology have been replaced with VOTES test, and, most of the margin improvement modifications are complete. If the COF data starts to show that values are increasing, adjustments to the GGNS setup methodology procedures will be made. D. The revision of open valve factor determinations to account for stem rejection forces that were not addressed in IR 96-20. Response: The impact of adding stem ejection load to the measured open thrust used to calculate the open valve factors was assessed. It was concluded that overall this had a minimalimpact on the calculated open valve factors. The open valve factors calculated using the MS-49 data sheets were not used by Siemens when the group valve factors were established. E. The MOV trending program update that was not covered in IR 96-20. Response: Per the request of the inspectors during the GGNS closecut audit, several trending parameters were added to the MOV trending program. Parameters that are trended and plotted per MOV trending procedure are as follows: Torque Switch Trip (TST) Thrust, TST Displacement Unseat Thrust, Closed Running Thrust, COF, Seating Current, Inrush Current, Running Current, Contractor Drop Out Time and Stroke time. GGNS has purchased a VOTES Motor Power Monitor (MPM) unit and plans to start testing in 1999. MPM data will be added to the trend database in the future.
l Attachment to GNRO 99/00030 l l l
- 2. Is the licensee applying the BWROG methodology for ranking MOVs based on their safety significance as described in BWROG Topical Report NEDC-32264 and the NRC safety evaluation dated February 27,1996, for NEDC 32264? If not, the licensee should describe the methodology used for risk ranking MOVs at GGNS.
1
Response
GGNS used the November 1993 version of NEDC 32264 as the basis for the GGNS MOV safety significance ranking. This revision of the document is very similar to l Revision 2. The primary difference is that Revision 2 includes discussion addressing j such issues as: inter-system common cause and multi-component issues; scope of GL 89-10 versus the scope of PSA analysis; integration of probabilistic and deterministic methods of ranking MOVs; design basis capability and verification; testing intervals; ! changes in plant design or state of knowledge of valve categorization; and other considerations. It is our conclusion that none of this discussion would have resulted in i changes to the basic risk significance ranking of MOVs for GGNS. The importance l ranking and resultant categorization of valves was one of the factors utilized for establishing the frequency of periodic retesting.
- 3. The licensee is requested to describe the GGNS plan 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. The licensee should address the setup of RCIC E51-F045 using 110% of dc motor torque in its response. '
Response: GGNS has the same setup criteria described in previously approved NRC inspections with respect to error calculations and setup methodology. All AC powered gate and globe MOVs in the Grand Gulf GL 89-10/96-05 programs were evaluated using Limitorque Technical Update 98-01 for guidance to determine potential operability and margin concerns. The evaluation was performed and addressed in Engineering Report GGNS-98-0038 and CR 1998-0819-00. As a result of the evaluations, GGNS implemented modifications in RFO9 and currently has plans for more modifications during RFO10 to increase MOV output capabilities to improve margin. RCIC E51-F045 was identified in MNCR 95/0302 as exceeding MO-25 motor torque values. The condition was evaluated and showed that the motor was capable of delivering 110% of its rated torque. The NRC accepted this at the time. Their concern I was how this valve would be effected by information expected to be issued by i Limitorque regarding torque capabilities of DC motors. l i
)
Attachrnent to GNRO 99/00030 Limitorque, to date, has not issued a formal document on DC motors as they did on AC motors. GGNS is a member of the VTRG and is aware of the testing that has been performed to date and testing that will be performed in the future. DC motor torques are calculated at GGNS as allowed by Limitorque Technical Update 92-02. For all DC l MOVs except 1E51F045, motor torque does not have to account for elevated ambient temperature effects because maximum expected temperatures under design basis conditions are less than Qualified Tenperatures (i.e. 340* F) given in Table A-3 of l Limitorque Technical Update 92-02. 1E51F045 had a motor gear changeout in RFO8 as a result of the available torque margin indicated in MNCR 95/0302. Close torque for 1E51F045 was increased by about 45%. Before gear change torque available was 861 ftibs, and after the gear change it was 1254 ftIbs. As a result of the gear changeout, the torque is now set below the 100% rating of the DC motor torque.
Attachment to GNRO 99/00030 Appendix A Fax from Wyle Laboratories (Dr. Nabil Schauki) to Mr. Tom Scarbrough, NRC
Subject:
GL 89-10 Closure Meeting at GGNS and Inspection Report No. 50-415/96-03 , This appendix is referred to in response to Question 1 of RAI i I l
TFQ M C-12-9.6 TlW 4:17 PM tR.703 P.2/9 ,
' t 2.DEZ.1996 18:07' SIKLI) CFF' Nret.8 ' l ;
I l 1 FAX Wyle Laboratories Huntsville, Alabama 35807 (205) 837 44II Fax: (205) 721 0144 TO: Tom Scarbrough ' NRC . FAX (301) 415 2444
Subject:
OL 89.10 Closure Meeting at Grand Gulf and Impection Report No. 50 415/96 03 l Dear Tom; Referring to the Generic Letter 8910 Closure Inspection Report No. 50-415/96 03 of Grund Gulf's Program, the inspectors stated an open question about identifying major damage which would lead to unpredictable behavior by the Siemens Methodology, We l believed that by sending the fax about the comparative analysis on two of the GI-87 test valve on Feb.15, to have solved the issue. (See Attachment) Furthermore on our telephone conversation during the closure meeting on Feb.14th,1996, we infonned your inspectors about other considered items to assure coverage of known conditions / derign features which would lead to vahe failures. An exarnple was given on disc deflection on Os the seat at high energy loads which would lead to major plasti 5 cation of the body seat thus leading to functional failure. Such behavior has been identi5ed by separate effects tests, large scale gate valve testing as well as by Finite Element Model Analysis at Siemeos in Germany. Anotheritem was the tilted disk seat contact at high loads. The ca!culation of disk stability and disc seat contact are one of the important analysis models in the grouping methodology to cover this behavior. Please allow me sorce statements about "Siemens Grouping Methodology" to assure clarifying this issue because the veri 6 cation of the operability and predictabihty is done by performing dynamic tests on selected covering prototypes. The method does not verify functionalbility and predictability solely by analysis.
- The major goal of the Grouping Methodology is to idcotify a family of MOVs with similar dynamic and stress behavior as well as to define the test candidates which require test results from dynamic tests at " Design Basis Conditions."
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yyr:Tl=MITMF'f:Tr~rf, iru na7m. ... ...
- >- a tz.tcz.1995 18:07 SIKNU C(T NDN4 NR.703 P.3/9
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I (, . Tests preformed on worst case candidates will show any unpredictable l hehavior. I l The test conditions and pressure build up are compared to the analysis models to verify coverage. e The test signatures and inspection results are the basis to show that the valves are performing predictable thus a!!owing application of test results to the MOV family.
- I We did not feel dur'os development of the Model that the analysis alone ;
should cover the functionability verification. This is due to the fact that a considerable number of valves have stress exceedag the yield strength and thus an elastaplastic calculation would be required, Due to the largo variety of designs and interaction of the parts, the analy:Is was not considered to be an efficient too! for answering the functionability question. Iffou have any finther questions, please call me (205) 837 4411 c=t. 552. Best Regards, 4
/r -
Dr.N uki /J t)[ yle Laboratories 780010ghway 20 W. Huntm!!e Alabama 335806 O . . . . . . . . . . - . - - . . . . ......-.-. - ...-.... . .. -..... . . . . . . - - - - - - - . ~ - - - - - . - + . -
1ru 6T W.
'12.tCZ.1995 18'07 SIKMJ OFF f914 NR.703 P.4/9 l Entergy, Grand Gulf Atteistion: JeffWright (601) 437 2146 cxt. 6229 i
Subject:
Analysis Methodology /fdentification of msr damage. Please 6nd attached as agreed upon during our meeting on Feb,14th,1996, regarding bench ! marking of the analysis methodology on the INEL tested MOV No.1 (AD/900#,6"). As a i comparison we analyzed MOV No. 4, (AD/900#,10') and MOV No.5 (PoweU/900#,10"). the results of the analysis and conclusions are as fol!cws: Attachment 1: Comparison between Powen 900# and AD 900# flexgate valves. At first glance the two designs seem to be close and comparable. Attachrnent 2: Shows the dynanuc behavior of the Powell gate valve with a stable transfer of the disk from the guides to the seat ring. 'Ihis indicates an acceptable behavior. Attachment 3: Shows the dynamic behavior of the AD gate valve with an early tilted contact between the disc and seat. This early tilted contact at high energy loads with a large tilting angle indicates souging and hardfacing galling to be expected. The
.. inspection of the intemals revealed that parts of the hardfacing were shcared off and galling of the g!!dirig surfaces identified.
Attachment 4: Shows a comparison of the stresses between AD and Powcu gate valves. Mest l O .' . ,, rrmarkable are the average body / disc guide stress of AD (Design No. 2) whica exceed the 40 respectively 50 KSL This indicates a major damaga of the guides to be expected. Again the inspection of the guides verified the damage. PoweU,
, Design No.1, had low average stress and therefore only local plastifcation of edges are indicated. This was also verified by the inspection.
Attachment 5: Shows a relative comparison between the 6' /10" AD site valves to the 10 Powe!! gate valves. The dats she,v that the 6' AD is the weakest desigrt The 10" AD is marginally better in the disc seat bearing stress. The average body / disc guide are by factors higher than the Powou gate valve. As a conclusion, of the analysis a failure of the 6" AD , a poor performance of 10"AD and a fait performance of the Powell are gate valve during b!cwdown conditiorts is to be expected. These conclusions conform with the blowdown tests
. prfbrmed byINEL.
Ifyou have any questions, please call rne at (205) 837-4411, ext. 552. Best Regards.
. o l
Dr. Nabil O . . . . . . . . _ _ _ - . . . . . . . . _ . . . _ . . . . _ . . . . . . . . . . . . . . . - h
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1 r ADAPT A DETERMINISTIC APPROACII TO PERIODIC TESTING (FOR VALVES) Problem: Generic Letter 96-05 requires that utilities en:ure that MOV operability is maintained throughout the life of the plant. In this age of deregulation and competition, utilities have more limited resources to spend on maintaining plant safety and operability. Full flow dynamic testing of all GL 8910 program MOVs unduly burdens these resources and may, in some cases, reduce plant safety l by degrading critical MOVs. I 1 Solution: Wyle has performed an evaluation of the long term effects of flow media and stress on nuclear power plant gate valve performance. The results of this study show which valves are highly stressed and/or likely to have corrosion problems. From this, a logical action plan can be developed that considers the subject valves
- margins, testability, etc.
Benefits: Plant resources can be better utilized through an improved understanding of strengths and weaknesses in the performance of GL 89-10 program valves. This approach also reduces the j chance of degrading valve pans during testing. Finally, Wyle's approach results in a more cost-effective means of meeting GL 96-05 requirements over the life cycle of the plant. l l l l L A
r l' 1 l ?- l l l Attachment to GNRO 99/00030 l l l l l
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Appendix B Excerpt from Position paper to address NRC concerns regarding GGNS grouping program l Prepared for Entergy Operations by Wyle Laboratories February 22,1996 I t This appendix is referred to in response to Question 1 of RAI Note: This position paper refers to Siemens report 5221/94/025. This document is not attached because it contains proprietary information, but is available on site. l l l i}}