ML20209D267
| ML20209D267 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, Limerick  |
| Issue date: | 07/02/1999 |
| From: | Geoffrey Edwards PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-96-05, GL-96-5, NUDOCS 9907130097 | |
| Download: ML20209D267 (10) | |
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,. -....y GL 96-05 PECO NUCLEAR eama. c-nem, Nuclear Group Headquarters A UNir or PECO furacy 965 Chesterbrook Baukvard Wayne, PA 19087-5691 July 2,1999 Docket Nos. 50-277 j
50-2P'}
50-352 50 353 License Nos. DPR-44 DPR-56 NPF-39 NPF-85 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
SUBJECT:
Limerick Generating Station, Units 1 and 2 Peach Bottom Atomic Power Station, Units 2 and 3 Response to Requests for Additional infomiation (RAl) Regarding Generic Letter (GL) 96-05, " Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves"
References:
- 1) Letter from G. D. Edwards (PECO Energy) to U.S. Nuclear Regulatory Commission (NRC) dated May 14,1998
- 2) Letter from B. C. Buckley (NRC) to G. D. Edwards (PECO Energy) dated March 22,1999
- 3) Letter from M. C. Thadani (NRC) to G. D. Edwards (PECO Energy) dated April 20,1999
Dear Sir / Madam:
in the Reference 1 letter, PECO Energy Company (PECO Energy) submitted an updated
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' response to GL 96-05 indicating its intent to implement the provisions of the Joint Owner's Group (JOG) Program for MOV Periodic Verification at Limerick Generating Station (LGS), Units 1 and 2, and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3. PECO Energy has transitioned its GL 96-05 MOV Program over to the JOG
" Interim" MOV Periodic Verification Program within the time frame spacified in the Reference 1 lettar. PECO Energy acknowledges the U. S. Nuclear Regulatory Commission's (NRC) staff position, as expressed in the Reference 2 and 3 letters,
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encouraging participation in the industry wide JOG program as having substantive o
benefits in the areas of program implementation, regu!atory oversight and reactor safety through improved component reliability.
In the Reference 2 and 3 letters, the NRC has requested additional information with respect to the MOV programs at LGS, Units 1 and 2, and PBAPS, Units 2 and 3 in order to complete its GL 96-05 review. Attached is our response for LGS, Units 1 and 2, and PBAPS, Units 2 and 3. This letter provides a comtr on PECO Energy response to both
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98 PDR ADOCK 77 9
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July 2,1999 Page 2 Requests for Additional Information (RAls). A consolidated PECO Energy response is appropriate because of the common MOV program in place at both stations and since several questions in the RAls are identical and apply equally to each station.
If you have any additional questions, please contact us.
Very truly yours,
/$ tic 8fh/efht tb Garrett D. Edwards Director-Licensing Attachment cc:
H. J. Miller, Administrator, Region I, NRC A. C. McMurtray, NRC Senior Resident inspector, PBAPS A. L. Burritt, NRC Senior Resident inspector, LGS l
July 2,1999 Page 3
. bec:
N. J. Sproul, Public Service Electric & Gas R.1. McClean, State of Maryland i
A. F. Kirby, Ill, Delmarva Power & Light Company / Atlantic Electric R. R. Janati, Commonwealth of Pennsylvania G. R. Rainev - 63C-3 C. P Lewis - 63C. J. J. Hagan - 62C-3 J. D. von Suskil-LGS, SMB1-1 J. Doering - PB, SMB4-9
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M. E. Wamer-PB, A4-1S M. P. Gallagher - LGS, GMLS-1 i
G. L Johnston - PB, SMB3-2A J. P. Grimes - LGS, SSB3-1 E. F. Sproat - 63B-1 C. Anders - 63C-3 R. A. Kankus - 63C-2 A. A. Winters - PB, A4-SS K. Bersticker - LGS, SSB2-4 J. G: Hufnagel/TRL - 62A-1 D. P. Helker/RWG - 62A-1 i
PBAPS ISEG - PB, SMB4-6 PA DEP BRP inspector-LGS, SSB2-4 Commitment Coordinator-62A-1 Correspondence Control Desk - 61B-5 DAC - 61B-5 i
T. S. Neckowicz - 638-3 J. F. Mittman - LGS, SSB3-1 S. F. Gallogly - PB, S3-6 3
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COMMONWEALTH OF PENNSYLVANIA :
ss.
COUNTY OF CHESTER i
J. J. Hagan, being first duly sworn, deposes and says:
That he is Senior Vice Prosident, Nuclear Operations of PECO Energy Company; the Applicant herein; that he has read the attached response to the RAI regarding Generic Letter 96-05 for Peach Bottom Facility Operating Licenses DPR-44 and DPR-56, and Limerick Facility Operating Licenses NPF-39 and NPF-85, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.
Notanal Seal MrfnM.fdhes 7 eni Vick President My commission Expires Dec.18 I
. Member, Pennsylvania Association of Natanes j
Subscribed and Sworn to before me this' JAD day of 14
.1999
)
Notary Public i
1 GL 96-05 RAI Page 1 Attachment i
PECO Energy Response NRC Requests For Additional Information Concerning Generic Letter 96-05," Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves" Limerick Generating Station (LGS), Units 1 and 2 Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3
References:
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- 1) Letter frorn G. D. Edwards (PECO Energy) to U.S. Nuclear Regulatory Commission (NRC) dated May 14,1998
- 2) Letter from B. C. Buckley (NRC) to G. D. Edwards (PECO Energy) dated March 22,1999
- 3) Letter from M. C. Thadani (NRC) to G. D. Edwards (PECO Energy) dated April 20,1999 Common NRC Questions & Responses NRC Question (Reference 2I31. Question 3)
In a letter dated May 14,1998, the licensee updated its commitment to implement the Joint Owner's Group (JOG) Program on MOV Periodic Verification in response to GL 96-05. The JOG program specifies that the methodology and discrimination criteria for ranking MOVs according to their safety significance are the responsibility of each participating licensee. In a previous letter dated March 14,1997, the licensee had generally described the risk ranking of MOVs at Limerick (and Peach Bottom) for applintion of the interim MOV static diagnostic test program. As Limerick (and Peach Bottom) is a boiling water reactor (BWR) nuclear plant, is the licensee applying the Boiling Water Reactor Owners' Group (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 27,19967 If not, the licensee should describe the methodology used for risk ranking MOVs at Limerick (and Peach Bottom)in more detail.
PECO Enerov Resci nse in 1998, PECO Energy re-evaluated the safety significance (risk) ranking of its GL 96-05 scope in conjunction with MOV Program transition activities. This revised MOV risk ranking process followed the general guidance provided by the BWROG Report NEDC-32264A, Rev. 2 as endorsed by NRC SER dated February 27,1996, and the Westinghcu::e Owner's Group Report V-EC-1658, Rev.1 as endorsed by NRC SER dated April 14,1998. In ado; tion, applicable guidance and lessons learned, cs provided in the ASME OMN-3 Code Case were incorporated into the process. This MOV risk ranking process systematically integrates the plant Probabilistic Safety Assessment (PSA) with an expert panel review.
GL 96-05 RAI Page 2 MOV risk n:.nking involved the following multi-step process:
- 2) Calculate MOV (component level) PSA risk importance measures related to core damage frequency (CDF) and large early release frequency (LERF)
Risk Achievement Worth (RAW)
Fussell-Vesely importance (F-V)
- 3) Perform risk ranking categorization (High, Medium, Low)
- 4) Perform Expert Panel Review and Finalize Risk Ranking The MOV Risk Ranking Categorization Criteria for consideration by the Plant Expert Panel were as follows:
RISK RANKING CATEGORIZATION CRITERIA
[NekCategory9 NN [N d W CrRerla 9
High F-V > 0.01 or RAW >10 0.01 > F-V > 0.001 and RAW < 10 Medium OR 10 > RAW >2 and F-V < 0.01 Low F-V < 0.001 and RAW < 2 An expert panel review provided the final element of the MOV Risk Ranking Process. The purpose of the expert panel is to compensate for the limitations and assumptions inherent in the plant PSA. Once the PSA based rankings were developed, the expert panel reviewed them j
and made relative adjustments based on the following (typical) considerations:
i Consideration of safety related MOVs not explicitly modeled in the PSA Consideration of plant unique MOV failure data and component history Extemal Event Consideration interchangeability of MOV functions e
Technical Specification LCO implications Shutdown Requirements Maintenance Rule System Availability Considerations Design Basis Analysis NRC Question (Reference 2I31. Question 4)
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 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 actuator and its potential degradation.
The licensse should describe the plan at Limerick (Peach Bottom) for assuring adequate ac and de MOV motor actuator output capability, including consideration of recent guidance in Limitorque Technical Update 98-01 and its Supplement 1.
GL 96-05 RAI Page 3 PECO Enerav Response Potential degradation of thrust and torque delivered by the MOV actuator can be readily identified through (static) diagnostic periodic verification testing (PVT). PECO Energy conducts MOV PVT at frequencies within the risk based limits prescribed by the JOG Program taking into consideration the trending of as-found diagnostic test data. MOV performance trending is periodically assessed in accordance with Common Administrative Procedure A-C-81 (PECO Nuclear Motor Operated Valves). Each station's MOV lubrication, preventative maintenance and MOV periodic verification test frequencies are reassessed during the MOV performance trending process to ensure adequate margin for expected degradation.
In 1998, PECO Energy performed a comprehensive assessment of revised industry guidance on AC MOV motor actuator output capability guidance contained in Limitorque Technical Update (LTU) 98-01 (& Supplement 1). Significant generic program methodology changes included: 1) the adoption of Commonwealth Edison's (CECO) White Paper (WP)-125 methodology to replace LTU 98-01 methodology, as applicabie, and 2) the performance of more rigorous motor heat-up calculations in lieu of using bounding maximum equipment qualification temperature limits. CECO WP-125 was developed following an extensive industry sponsored Limitorque actuator AC motor testing program (which PECO Energy contributed) and is widely considered as representing the best available industry data for the tested motor types. The PECO Energy actions performed for Peach Bottom were reviewed by NRC Region I inspectors during a MOV inspection conducted at Peach Bottom during the week of January 4,1999 and were found to be appropriate. These findings are documented in the PBAPS NRC Inspection Report dated March 25,1999. The corresponding LTU 98-01 evaluation for Lime-ick applied the same approach and generic methodology changes as Peach Bottom.
PECO Energy is aware of the results of the DC MOV motor / actuator testing performed at INEL as presented at the Dec '98 Motor Operated Valve User's Group and is participating in the BWROG VTRG project to develop a standard DC MOV motor torque / speed / stroke time methodology. Currently, this revised DC MOV methodology is expected to be finalized in the fourth quarter of 1999.
Station Specific NRC Questions & Responses NRC Ouestion (Reference 2. Question 1)
In NRC Inspection Report No. 50-352 & 353/95-19, the NRC staff closed its review of the motor operated valve (MOV) program implemented at the Limerick Generating Station, Units 1 and 2 (Limerick), in response to Generic Letter (GL) 89-10, " Safety-Related Motor-Operated Valve Testing and Surveillance." In the inspection report, the NRC staff discussed certain aspects o,'
j the licensee's MOV program to be addressed over the long term. For example, Fe inspectors I
noted that (1) the licensee had used test data from the Electric Power Research Institute (EPRI)
MOV Performance Prediction Program in determining valve factors although the EPRI testing program was not intended to establish a statistical database for assigning bounding valve factors; (2) the licensee committed to dynamically test the low pressure coolant injection valves; l
(3) the licensee intended to revise its MOV program to prevent applying data from a single i
valve to other non-testable MOVs; and (4) additional valve factor justification was needed for Group 35 (8" Crane gate valves). The licensee should describe the actions taken to address I
the specific long-term aspects of the MOV program at Limerick that were noted in the NRC
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Page 4 inspection report, including consideration of the NRC staff conclusions on the EPRI program that were subsequently provided in the NRC safety evaluation dated March 15,1996, and its supplement dated February 20,1997.
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PECO Enerav Response (1) For the GL 96-05 valve population not testable under D-P conditions, Limerick continues to apply the statistically derived bounding valve factors which were established to support NRC closure of the GL 89-10 MOV Program at Limerick in 1996. PECO Energy considers that the utilization of EPRI data for this purpose remains technically valid. All MOV D-P testing conducted at Limerick since the 1996 supports the bounding valve factors selected.
As participating members in the JOG Dynamic Test Program, PECO Energy evaluates JOG MOV test data for applicability to Limerick. The JOG Program has specifically created a formal feedback notice mechanism to communicate the results of MOV DP testing having negative valve factor performance trends.
(2) All eight RHR Low Pressure Coolant Injection (LPCI) valves were dynamically tested.
J (3) All valve factors which are selected based on in-situ test data, and are not set to the statistically bounding value, are based on representative test data which meet GL 89-10 Supplement 6 grouping criteria.
(4) Three of eight Group 35 (8" Crane) valves have been dynamically tested and have shown significant margin using the default valve factor of 0.62. Measured apparent valve f actors are typically below a value of 0.3.
NRC Ouestion (Reference 3. Question il in NRC Inspection Report No. 50-277 & 278/97-07, the Nuclear Regulatory Commission (NRC) staff closed its review of the motor-operated valve (MOV) program implemented at the Peach Bottom Atomic Power Station (Peach Bottom)in response to Generic Letter (GL) 89-10,
" Safety-Related Motor-Operated Valve Testing and Surveillance." In the inspection report, the NRC staff discussed aspects of the licensee's MOV program to be addressed over the long term, including the licensee's plans to implement a margin improvement program to increase the thrust capability of more than 30 MOVs. The licensee should describe the actions taken to address this long-term aspect of the MOV program at Peach Bottom that was noted in the NRC inspection report.
PECO Enerov Response The PECO Energy MOV margin improvement initiative is considered an on-going project at both the Limerick and Peach Bottom stations which attempts to balance the benefits of frequent MOV Periodic Verification Testing (PVT) against those derived from MOV design changes which serve to improve MOV set-up margin and reduce MOV PVT frequencies. As new industry issues arise which may degrade MOV performance, they are evaluated in timely manner for impact on MOV margin such that required changes are planned before the associated issue becomes a required MOV design standard. Through torque switch adjustments and other design changes, Peach Bottom has reduced the number of MOVs with
" Low" (i.e., less than 5%) thrust margin to six (G) and anticipates additional MOV margin l
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GL 96-05 RAI Page5 improvements by the end of 3R12 (Fall 1999). These improvements have incorporated motor actuator methodology changes resulting from Limitorque Technical Update 98-01 (discussed separately in response to NRC Question 4).
NRC Question (Reference 3. Question 2)
In GL 96-05, the NRC staff discussed the scope of the program with respect to safety-related MOVs that are assumed to be capable of returning to their safety position when plac3d in a position that prever:ts their safety system (or train) from performing its safety function; and the system (or train) is not declared inoperable when the MOVs are in their non-safety position. In a letter dated March 14,1997, the licensee indicated that such MOVs are not included in the GL 96-05 program at Peach Bottom, but that operability is demonstrated through routine plant operation. However, NRC Inspection Report No. 50-277 & 278/97-07, dated December 16, 1997, noted that (1) the licensee had revised Peach Bottom's GL 89-10 program scope to include 12 of the 16 MOVs that were originally considered to have a passive safety function; and (2) the systems / trains associated with the remaining four MOVs Te declared inoperable when they are out of their safety positions in accordance with the plant Technical Specifications. Therefore, the licensee should clarify its position by identifying if the referenced 12 MOVs are included in tM Peach Bottom GL 96-05 program scope, if not, the licensee should address its plans fur maintaining torque switch settings and the feedback of industry operating experience and data. Further, the Peach Bottom licensee should discuss the manner in which its approach will provide confidence that these MOVs will be capable of retuming to their safety position, including (1) plans for performing required switch setting adjustments promptly, (2) any specified MOV operation under dynamic conditions, or (3) any future diagnostic testing. The Peach Bottom licensee should describe the bases for its confidence that (1) these MOVs will continue to be capable of retuming to their safety position, (2) any degradation in MOV performance will be identified prior to causing the MOVs to be incapable of retuming to their safety position, and (3) any action necessary to ensure MOV capability will be taken in a timely manner.
PECO Enerav Response During the 1998 GL 96-05 Program Update, the subject 12 MOVs were added to the scope of the GL 96-05 MOV Program. As valves within the scope of GL 96-05, these MOVs will all be subject to periodic verifcation testing based on margin and safety significance consistent with PECO Energy's commitnent to GL 96-05 in Reference 1. All of the subject 12 valves are classified as " Low" safety signifk. ant. The prescribed periodic system and valve diagnostic testir.g requirements provide adequate confidence commensurate with their safety significance
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that the valves will continue to: 1) maintain their " system recovery from test" function, and 2) detect potential degradation mechanisms (e.g., stem tube degradation) before valve functional opert.bility is challenged. All other aspects of the PECO Energy GL 96-05 MOV program (e.g.,
J including MOV performance trending, feedback of industry data, etc.) remain applicable.
NRC Ouestion (Reference 2. Question 2_)
In GL 96-05, the NRC staff discussed the scope of the program with respect to safety-related MOVs that are assumed to be capable of retuming to their safety position when placed in a position that prevents their safety system (or train) from performing its safe,ty function; and the system (or train)is not declared inoperable when the MOVs are in their non-safety position. In
GL 96-05 RAI 1,,7 Page 6 a letter dated March 14,' 1997, the licensee indicated that such MOVs are not included in the GL 96-05 program at Limerick, but that operability is demonstrated through routine plant operation. With respect to such MOVs placed in their non-safety position at Limerick, the licensee should address its plans for maintaining torque switch settings, and the feedback of industry operating experience and data. Further, the Limerick licensee should discuss the
. manner in which its approach will provide confidence that these MOVs will be capable of returning to their safety position, including (1) plans for performing required switch setting adjustments promptly, (2) any specified specific MOV operation under dynamic conditions, or (3) any future diagnostic testing. The Limerick licensee should describe the bases for its confidence that (1) thess MOVs will continue to be capable of returning to their safety position, (2) any degradation in MOV performance will be identified prior to causing the MOVs to be incapable of retuming to their safety position, and (3) any action necessary to ensure MOV capability will be taken in a timely manner.
PECO Enerav Response
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In 1998, PECO Energy formally revised the Limerick GL 96-05 MOV program scope to include the following addidonal motor operated valve applications:
RCIC Test Retum Valve RHR Pump Full Flow Test Valve i
Core Spray Test Loop Isolation Valve
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HPCI Test Retum Valve
. HPCI Test Retum to Condensate Storage Tank Valve
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- HPCI Test Retum/ Flush to Suppression Pool Valve Core Spray Pump Discharge Valve HPCI Pump Discharge Valve RCIC Pump Discharge Valve The above program scope changes were made during the required 1998 program transition period described in Reference 1. As valves within the scope of GL 96-05, they will all be subject to periodic verification testing based on margin and safety significance consistent with PECO Energy's commitment to GL 96-05. All of the above valves are classified as " Low" safety significant. The prescribed periodic system and valve diagnostic testing requirements provide adequate confidence commensurate with their safety significance that the valves will continue to: 1) maintain their " system recovery from test" function, and 2) detect potential degradation mechanisms (e.g., stem lube degradation) before valve functional operability is challenged. All other aspects of the PECO Energy GL 96-05 MOV program (e.g., including MOV performance trending, feedback of industry data, etc.) remain applicable.
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