ML20203D880
| ML20203D880 | |
| Person / Time | |
|---|---|
| Issue date: | 02/19/1998 |
| From: | Rossi C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Gillespie F, Holahan G, Lainas G NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20203D883 | List: |
| References | |
| NUDOCS 9802260183 | |
| Download: ML20203D880 (6) | |
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Fetruary 19, 1996 MEMORANDUM TO:
Frank P. Gillespie, Director, DISP:NRR Gary M. Hofahan, Director, DSSA:NRR Gus C. Lainas, Acting Director, DE:NRR Jack W. Roe, Acting Director, DRPM:NRR R. Lee Spessard, Director, DRCH:NRR Lawrence C. Shao, Director, DET:RES M. Wayne Hodges Director, DST:RES Joseph A. Murphy, Acting Director, DRA:RES James T. Wiggins, Director, DRG:RGN 1 Johns P. Jaudon, Director, DRS:RGN-ll John A. Grobe, Acting Director, DRS:RGN Ill Arthur T. Howell, Director, DRS:RGN-IV FROM:
Charles E. Rossi, Direct [d,'. M Safety Programs Division Office for Analysis and Evaluation of Operational Data
SUBJECT:
SPECIAL STUDY: OPERATING EXPERIENCE -E3DBACK FROM SERVICE WATER SYSTEM FAILURES AND DEGRADATIONS (1986 -
1995) FINAL REPORT Attached for your information and use is the special study on service water system (SWS) failures and degradations covering operating experience from 1986 through 1995. This special study was performed to evaluate the safety implications of service water systems evenM and the impact of licensee and NRC initiatives on SWS performance.
The report characterizes Licensee Event Reports (LERs) into Safety Significant categories by their nature and effect on the system. Analyses of the trends in and contributions to the Safety Significant LERs form the basis for the assessment of the overall safety performance and the effectiveness of NRC and licensee activities. Additional evaluations include analysis and trending of SWS LER cause mechanisms, SWS performance w"hin NRC regions, and review of Individual Plant Evaluation (IPE) and Accident Sequence Precursor (ASP) information relating to SWS events. Comments from NRR, RES, and the Regions were solicited and a meeting was j
held on December 16,1997 to discuss them. This report reflects the choges agreed upon as a result of the review comments. (See attachment with resolution of comments).
j This report identified the following major findings and conclusions:
[3 There were no failures of SWS that resulted in an actualloss of core cooling capability.
e The few short term losses of SWS (less than 2% of the 579 reported SWS events) tha' had a potential impact on core cooling capability were identified and recovered promptly.
No trend was detected in the annual rate of all SWS LERs (579) over the period 1986-e 1995. However, ttyT number of Safety Significant SWS LERs increased over the 1986 9902260183 98021E '
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2 through 1995 period. Licensee programs in response to Generic Letter (GL) 8913 efforts played a significant role in identifying these safety significant SWS LERs. Of the 147 Safety Significant SWS LERs,46 appear to have been identified as a result of efforts related to GL 8913. This study found no trend (increase or decrease) in the number of Safety Significant LERs when events related to GL 8913 are removed from the database.
Licensee activities in response to GL 89-13 appear to have been successfulin identifying safety significant programmatic and design related issues affecting SWS performance.
Licensee GL 89-13 efforts primarily identified problems of the " Potential Failure / Degradation" type rather than problems of the " Actual Failure" type. This is consistent with the intent of one of the GL 89-13 requirements to verify design adequacies and maintenance programs. This is indicative of successful efforts to identify and correct design and maintenance issues which might become operational problems if left unattended.
A Service Water System Operational Performance Inspection (SWSOPI) review was performed to see if new safety significant items were found in the SWSOPIs that were not in operating experience, and to see if inspection findings were consistent with safety s)gnificant findings relating to SWS operating experience. Six LERs were generated as a result of SWSOPI findings including one Safety Significance Category 6 LER (specific support system heat exchanger). Five LERs were not classified in the Safety Significance categories. The SWSOPIs were primarily reviews of the design bases and licensee compliance with regulatory requirements for processes to monitor and veilfy continued applicability of the design bases. Program and process reviews formed the bulk of the inspection instructions and the findings reflect issues predominantly related to program and process deficiencies rather than operational failures or degradations.
Approximately 12% (17 of 147) of the Safety Significant SWS events were also identified e
as precursor events in the ASP program. The conditional core damage prcbabilities (CCDPs) associated with these ASP events ranged from 1.3E-6 to 4.8E-4. These CCDP ranges are consistent with the SWS related contributions to Core Damage Frequency (CDF)in IPEs for the population of plants.
The IPEs indicate the percentage of CDF attributable to SWS failure is about 13% for e
PWR plants and 7% for BWR plants. There was no statistically significant trend (increase or decrease)in the relative contribution to CDF among BWRs or PWRs with respect to plant age.
Based on these findings and conclusions, the report made the following recommendations:.
AEOD should continue to monitor the overallindustry experience as indicated by LERs end the additional reliability data that will become available via the industry's Equipment Performance Information and Exchange (EPIX) system. The purpose of this work will be to determine if the operating experience indicates safety significant improvement in performance as SWS actions in response to GL 89-13 are completed.
NRR should evaluate the effectiveness of future SWS inspections (SWSOPIs or other e
inspections of SWS performance)in light of the risk Mgnificance of the operating
3 experience discussed in this report. Future inspection activitics should be more focused on the generic risk insights in this study with respect to safety significant SWS performance in consideratior' of plant specific PRA results and relevant operating experience.
As part of the review process, NRR requested amplification of the recommendations to make future inspections more focused on " generic risk insights in this study with respect to safety significant SWS pe,trmance in consideration of plant specific PRA results and relevant cporating experience," The following suggestions follow a generic approach which consists of 1)ldentifying plants for increased inspection based on the risk contribution of the issue at hand arid 2) tailoring the specific activities to those actual or potential conditions that reflect the dominant contributors to that risk that apply to tnat plant.
When planning future SWS inspection activities, plants should be selected for inspection where the operating experience indicates that the SWS performance is risk significant.
This cou'd include:
1)
Plants for which the percentage of CDF attrit,utable to SWS failures is a significant contributor to risk, 2)
Plants that had experienced SWS related ASP events whose CCDP was high, for example, a cater than 1.0 E -4, 3)
Plants experiencing SWS related events in the Safety SigMcance categories of this report, or 4)
Plants wNse design and operating characteristics are similar to those identified above, and thus a higher risk of safety significant SWS events in the future.
Plants that have none of these characteristics normally would not be candidates for additional SWS inspection beyond the numal routine monitoring currently administered through the core inspection program, in planning a specific insp6 ' ion of a selected plant, inspectors should focus on those equipment or conditions that have been dominant contributors to the SWS operational risk at the plant or at similar plants. The inspection should be conducted to determine that the licensee has taken corrective actions to resolve the existing problems of intoiest, to verify that the equ pment is capable of performing its risk significant function, to determine the effectiveness of inservice and surveillance testing with respect to significant operational requirements and past operating history as documented in this report, and to investigate conditions or operations that operating experience has indicated would adversely affect the reliability of the equipment to perform its risk-significant function.
For example, during the period of this study, Shearon Harris reported three Safety g
Significant SWS LER events - one of Safety Significance Category 2 due to failure to close of the seal water booster pump suction and discharge valves, one of Safety Significance Category 3 when the seal water supply piping configuration was determined
4 to be vulnerable to passive failures which could disable both Essential Service Water (ESW) trains, and one of Safety Significance Category 6 when planned maintenance on the 1 A SA ESW pump led to the Essentia! Services Chilled Water system being declared inoperable. The second of these events was also an ASP event with a conditional core damage probability of 4.8 E 4. A potentialinspection at Harris might focus on the adequacy of testing of saal v.ater booster pump suction and discharge valves and other small valves required to isolate safety related lines where poor water quality is expected and could adversely impact the risk significant function of the SWS.
Thie report is being provided to you as an AEOD report at this time for your information and use.
AEOD plans to publish this report later as a NUREG. If you have any technical questions on this material, please contact Bennett M. Brady of my staff at 415-6363.
Attachtnent: As stated cc w/att.:
V. K. Chexal, EPRI W. J. Hastie, INPO Distribution w/att.:
Public DHickman BSheron, NRR JHoughton, NRR File Center J Rosenthal RZimmerman, NRR MShuaibi, NRR RAB RF SRichards, NRR AThadani, DEDE JTatum, NRR SPD RF RWessman, NRR JMitchell, OEDO RRAB RF MMayfield, RES TOMartin, OEDO TTMartin REmrit, RES PKadambi, RES FCongel RSavio, ACRS MCunningham, RES KRaglin JTappert, NRR DOCUMENT NAME: H:\\BMB\\SWSTRANS.TWO P
- See previous concurrence ry.e..... corr onm. oco... io ic.i. i is. so. c copy.4c.et.ew.aei e copy.,.ei.ce.aci u no copy OFFICE RRAS/RRAB E
RRAS/RRAB E
RRAB E
SPD E
NAME BBrady*
SMays*
PBaranowsky*
CERossitA DATE 2/6/98 2/9/98 2/10/03 1/ /-f /98
9 4
Safety Significance Category 6 when planned maintenance on the 1 A SA ESW pump led to the Essential Services Chilled Water system being declared inoperable. The second of these events was also an ASP event with a conditional core damage probability of 4.8 E-4. A potentialinspection at Harris might focus on the adequacy of testing of seal water booster pump suction and discharge valves and other small valves required to isolate safety-related lines where roor water quality is expected and could adversely impact the risk-significant fur sf the SWS, This report is being provided to you as an AEOD ieport at this time for your information and use.
AEOD plans to publish this report later as a NUREG. If you have any technical questions on this material, please contact Bennett M. Brady of my staff at 415-6363.
Attachment:
As stated cc w/att.:
V. K. Chexal, EPRI W. J. Hastie, INPO Qistribution w/atL:
Public DHickman BSheron, NRR JHoughton, NRR File Center J Rosenthal RZimmerman, NRR MShuaibi, NRR RAB RF SRichards, NRR AThadani, DEDE JTatem, NRR SPD RF RWessman, NRR JMitchell, OEDO RRAB RF MMayfield, RES TOMartin, OEDO TTMartin REmrit, RES PKadambi, RES FCongol RSavio, ACRS VCun lingham, RES KRaglin JTappert, NRR CSerpan, RES DOCUMENT NAME: H:\\BMB\\SWSTRANS.TWO
- See previous concurrence v.
e.
.. n ons. noe
.nunme.i. in ts. i.e. c cop.,..nuw.nci r eon w,.n.ew. net r no con OFFICE RRAS/RRAB E
RRAS/RRAB E
RRAB d
SPD h
NAME BBrady*
SMays*
PBaran CERossi
// /N98 DATE 2/6/98 2/3/98
/
/98
4 Safety Significance Category 6 when planned maintenance on the 1A SA ESW pump led to the Essential Services Chilled Water system being declared inoperable. The second of these events was also an ASP event with a conditional core damage piobability of 4.8 E-4, A potentialinspection at Harris might focus on the adequacy of testing of seal water booster pump suction and discharge valves end other small valves ruquired to isolate safety related lines where poor water quality is expected and could adversely impact the risk significant function of the SWS.
This report is being provided to you as an AEOD report at this time for your information and use.
AEOD plans to publish this report later as a NUREG. If you have any technical questions on this material, please contact Bennett M. Brady of my staff at 415-6363.
Attachment:
As stated cc w/att.:
V. K. Chexa!, EPRI W. J. Hastie, INPO Dlakibution w/att.:
/
Public DHickqban,
BSheron, NRR JHoughton, NRR File Center J RosdothaA RZimmerman, NRR MShualbl, NRR RAB RF SRichards, NRR AThadanirDEQE JTatem, NRR SPD RF RWessman', NRR JMitchell[OEDd RRA8 RF MMayfield, RES TOMartin, OEDO TTMartin RErnrit, RES PKadamb ' RES FCormel RSavio, ACRS MCunnin h
,13GS KRagiin JTappert, NRR Csorpan, R
/
DOCUMENT NAME: H:\\BMB\\SWSTRANS.TWO t.
w. em.e w. soewn.ni. inme.= in in. i,occ em w..n.e wr em w.n w.aei v em OFFICE RRAS/RRAB d RRAS/RRAB b
RRAB SPD NAME BBrady //8d SMays b'^
_PBaranowsky CERossi lDATE 8/ h /98 4/ 9 /98 J2//d/98
/
/98 1
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