ML20203D884
| ML20203D884 | |
| Person / Time | |
|---|---|
| Issue date: | 01/23/1998 |
| From: | Bennett Brady NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | John Tappert NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20203D883 | List: |
| References | |
| NUDOCS 9802260186 | |
| Download: ML20203D884 (3) | |
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Attachment January 23,1998 hilihiO TO:
Events Assessment and Generic Communications !! ranch Division ofitcactor Program hianagement OfEc: of Nuclear Iteactor llegulation l
1 llON1:
llennett 11rady iteliability and Ilisk Assessment Branch Safety Programs Division OIDee for Analysis ar.d Evaluation of Operational Data SUllJECf:
llevisions to AEOD Dran Service Water System lleport At a meeting on Tuesday, December 16,1997, representatives of Nitit provided comments on AEOD's dran "Special Study: Operating Expciicnce Feedback From Service Water System Failures and Degradations (19861995)." n a meeting summary that Steve hiays provided you, I listed the comments that AEOD agreed to address in ?he fmal report. Your E mail of January 7 to Steve indicated that my meeting summary was acceptable and that we should proceed with revising and publishing the finM Service Water System (SWS) report. Below are the comments that AEOD agreed to address in the fmal report and how we have addressed them:
Ger.eral Comments on lleport:
I.
The study covers Sil'Sfailures and degradations information up to 1995. Future AEOD reports should be more timely in order to sup'> ort regulatory decision making.
AEOD agrees with the desire for the most timely information consistent with available resources and will try to produce more timely reports or updates in the future.
2.
It is not clear what the denominator was in some ofthe percentages in the report.
AEOD reviewed all percentages in the report and edited those that needed clarification to make the basis of the percentages clear.
Comments on Executive Summary:
3.
The Executive Summary states that the current study utill:ed datafrom 1992 through I995 to update tne AEOD Sil'S study. However, the methodology section says that LERs were reviewedfor the period 1986-1995. The timeframe ofthe study may need to be clarifled The second sentence on page iii was revised to clarify that this report used the previous 9802260186 980219 PDR ORG NEXD PDR
data (19861991) and the additional data from 1992 through 1995.
4.
Finding (2) on page iv. discusses several cause categories and may i.e confusing to the
- reader, ilullets and sub bullets were added in (2) on page iv to clarify this paragraph.
S.
Finding (3) on page iv. states that the conditional core damage probabilities associated with the ASP events is consistent with the Sil'S contributions to core damagefrequency.
11re rational behind comparing these two meast.res shmdd be explained The last sentence in (3) was revised to state that the range of CCDPs for the ASP events is consistent with the SWS related initiators for the population of plants.
6 Ilie percentage ofCDF attributable to Sil'Sfailure in Pil'R and Bil'R plants statedin the report is higher than the estimatesfrom a review of the IPE Database.
The paragraph on the bottom of page 9 was expanded to explain the transients included in i
this analysis and that the analysis was conservative in that it was not restricted to the essential service water system.
7 The last recommendation recomme~tds thatJiaure inspection activities be moreJbcused on the generie risk insights in this study with respect to safety sign!/lcant Sil'S perfbrmance with consideration ofplant specific PRil results and relevant operating experience. The recommendations in the conclusion section ofthe reportfor NRR action should be more specific ami better defined.
AEOD will expand the recommendation in the letter of transmittal of the Onal SWS report.
Comments on Report 8.
On page 33, Ihe study indicated that there was "no statistical trend in the relative contribution to CDF among BIl'Rs or Pll'Rs with respect to plant age, " The conclusion is based on thefact that plants old oryoung reported similar CDF contributionfrom loss ofservice water. The basisfor the conclusion is too weak and may needfurther elaboration.
AEOD revised (6) on page 33 to state that the data are insuf0cient to conclude that
" aging" is a signincant contributor to the IPE results.
9 On page 33, the study concludes that "the Sil'Sperformance was a measurable, not dominant, contributor to risk " The conclusion may be true or average; however, severalplants indicated that the risk contributionfrom loss ofESil' was relatively significant, i.e., greater than IE 3 in CDF contribution. The conclusion should be
e elaborated.
Al!OI) made editorial changes to say that this is true for the general population of plants but plant specific risk contributions can vary.
10.
Page 8 states "These inspections are performed at sites with perceivedSil'Sproblems. "
Sil'SOPIs were not always conducted at sites with perceivedSil'Sproblems.
AliOD deleted this scatence.
Distribution: Pilaranowsky, Meeting Attendees
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