ML20210S847
| ML20210S847 | |
| Person / Time | |
|---|---|
| Issue date: | 08/11/1999 |
| From: | Joshua Wilson NRC (Affiliation Not Assigned) |
| To: | Carpenter C NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20210S852 | List: |
| References | |
| PROJECT-669 NUDOCS 9908180214 | |
| Download: ML20210S847 (10) | |
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UNITED STATES i
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j NUCLEAR REGULATORY COMMISSION i h t
WASHINGTON, D.C. 20555-0001 h
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Lim August 11,1999 h
- j MEMORANDUM TO
Cynthia A. Cepenter, Chief j
Generic Issaes, Environmental, Financial, A
f and Rulemaking Branch Division of Regulatory improvement Programs, NRR FROM:
James H. Wilson, Senior Project Manager g
Generic issues, Environmental, Financial, 4
and Rulemaking Branch l{
j Division of Regulatory Improvement Programs, NRR
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SUBJECT:
SUMMARY
OF MEETING HELD ON JULY 15, WITH EPRI CONCERNING RISK-INFORMED IN-SERVICE INSPECTION On July 15,1999, representatives of Electric Power Research Institute (EPRI) and its contractors met with the representatives of the Nuclear Regulatory Commission (NRC) at the NRC's offices in Rockville, Maryland. The purpose of the meeting was to discuss open items remaining in the staff's review of EPRI topical report, TR-112657, Revised Risk-Informed Inservice Inspection Evaluation Procedure. Attachment 1 provides a list of meeting attendees and their affiliations. Attachment 2 provides the presentation materials used by EPRI at the meeting. Attachment 3 contains the handouts used by the staff to summarize the remaining open issues of the topical report.
The staff and EPRI discussed the open issues in Attachment 3, as discussed below.
1.
Piping Scope Definition 1
The TR does not clearly define the scope of the risk-informed inservice inspection J
e (RI-ISI) program, nor does it provide guidance with respect to integration of the RI-ISI q
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program and various other augmented inspection programs. The TR discussion in
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Table 6-2 (Page 6-12) conflicts with Section 3.1 (Page 3-2), where it is implied that it is j
up to the licensee to make the decision regarding whether to incorporate piping I
systems and degradation mechanisms such as flow-accelerated corrosion (FAC),
intergranular stress corrosion cracking (IGSCC), and microbiologically-induced corrosion (MIC), into the RI-ISI program or leave them unchanged.
Resolution: The text on Page 3-2 has been clarified to state that IGSCC Category B-G welds and FAC programs may not be subsumed into RI-ISI programs.
The TR should be revised to provide clear and consistent guidance for integration of e
the augmented and RI-ISI programs. Also, the TR should clarify that the inspections under the augmented programs that are not being impacted by RI-ISI program (e.g,
IGSCC B-G and FAC) will not be credited towards the samples being selected for the RI-ISI program.
9908190214 990811 PDR TOPRP EXIEPRI l
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A C, Carpenter August 11, 1999 Resolution: EPRI will resolve the issue and inform the staff of its position.
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Section 3.2 (Page 3-5) should include a reference to the altamate methodology in Sechon 3.6.7, for evaluation of systems subject to localized corrosion such as service water. Section 3.6.7 (Page 3-65), "Altemate Element Selection Criteria-Localized Corrosion," should be clarified to specify that if a licensee performs an evaluation that departs from an approved process such as that presented in this section of the topical report, a more detailed evaluation by the NRC staff to determine the adequacy of the approach will be required.
Resolution: Section 3.6.7.3 will be deleted, i
2.
Multi-Discipline Plant Review The EPRI methodology does not advocate using an " Expert Panel" for final element n
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selection. Instead, final element selection is subject to a detailed multi-discipline plant review, in accordance with the criteria noted in topical report Section 3.6.5.1 (Page 3-60) and 3.6.5.2 (Page 3-62) of EPRI TR-112657. However, the role of the multi-discipline plant review team in performing this assessment is not adequately described in the topical report. The TR should be revised to include this information, as well as further guidance to describe the role of the multi-discipline plant team for each area where plant-specific knowledge is required to validate and ensure the adequacy of the RI-ISI evaluations.
Resolution: EPRI TR has been revised to include more details of the multi-discipline plant review team. The EPRI TR will be further revised to indicate that: (1) multi-discipline team will include personnel that performed degradation and consequence analysis and (2) results of the multi-discipline team meetings will be documented.
3.
Element Selection in Existing Augmented Programs
' For segments that are included in the existing plant FAC and/or IGSCC inspection programs, the topical report Section 3.6.4.2 (Page 3-59) provides the following guidance: for segments in Risk Category 1, 3, or 5 that are included in a plant's existing FAC inspection program, the number of inspection locations is to be the same as in the existing plant FAC inspection program; for those segments that are in Risk Category 1, 2, 3, or 5, and are included in the existing plant IGSCC inspection program, the number
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of inspection locations is to be the same as in the existing plant IGSCC inspection program, except as discussed in Section 3.2 of this evaluation. However, this guidance could be misconstrued to mean that different locations could be selected as long as the
" number" of FAC/lGSCC locations are the same. The guidance in the topical report j
should be changed to make it clear that the same FAC/lGSCC inspection locations
..should be examined as those of the existing plant FAC/lGSCC inspection locations.
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I C. Carpenter
-3 August 11, 1999 4
I Resolution: EPRI TR is being revised to clarify issues related to augmented j
inspections.
l 4.
Risk-Related issues Figure 3-6 in the topical report provides a decision flowchart and associated criteria for evaluating RI-ISI impacts on core damage frequency (CDF) and large early release frequency (LERF). The flowchart provides a branch for adjusting elements to be examined if the cumulative change in CDF or LERF is >1E-7/yr and >1E-8/yr, respectively. However, the guidance is insufficient to describe how the licensee should adjust the element selection to meet the above risk criteria. The TR should be revised to provide more guidance in Section 3.7.2, paragraph " Adjustment to Element Selection," to more fully describe how the licensee would perform this evaluation, and to ensure that any adjustments made to the elements to be examined are also reviewed and approved by the plant multi-discipline team.
Resolution: EPRI TR-112657 will be revised to clarify Figure 3-6.
The TR states that system level decision guidelines should be applied to each system regardless of the scope of the application. (OPEN ISSUE: The topical report only implies that the system level guidelines should always be used.) The topical report includes a flow chart in Figure 3-6 which outlines the decision criteria for evaluating RI-ISI impacts on CDF and LERF (OPEN ISSUE the figure is still confusing).
Resolution: EPRI stated that it intended that the system level guidelines to always be used (aside from Class 1560 applications discussed below). EPRI will clarify the text.
The TR states that risk change evaluation (qualitative and quantitative) are not needed l
for the Class 1-only applications. The staff does not agree that the change in risk for l
Class 1 applications is not necessary. Nor has the staff been provided a generic i
evaluation showing that the change in risk for Class 1 application is less then some risk guideline, as well as a methodology for each licensee to determine whether the generic application is applicable to their plant. Current staff position is that applications including all reactor coolant pressure boundary (RCPB) piping, may treat this Class 1 piping as one system because the RCPB is defined in 10CFR50.2 and is equivalent to a " system" insofar as it performs a well defined function and is comprised of a fixed set of equipment.
Resolution: EPRI indicated it would try to develop a bounding analysis showing that the change in risk would be generically acceptable for Class 1560 applications. It agreed to use the system-level change in risk as the acceptable change criteria. If a robust bounding analysis can not be developed quickly, EPRI will consider the inclusion of Class 1 risk calculations in its methodology.
C. Carpenter 4
August 11, 1999 l
l EPRI estimates that the total frequency of a pipe break at a plant is on the order of e
1E-2/yr. Although (as discussed in Section 3.3.2) the guidelines for consequence were developed together with the bounding pipe failure frequencies, EPRI has not provided a justification for the guidelines.
Resolution: EPRI will clarify the text in the TR.
Table 3-6 in EPRI TR-112657 provides the upper bound estimates for each table element. The staff recognizes that elements with conditional core damage probabilities (CCDPs) up to 2E-4 are categorized medium (not high) and others as high as 2E-7 are categorized as low (not medium). Current thinking is that for this particular table, a factor of two increase in the guidelines is offset by the simultaneous use of three upper bound values. (OPEN ISSUE - The current table has entries with more than 2E-4.)
Resolution: EPRI expanded the discussion and tables showing that the table entries are consistent using point estimates (instead of upper bounds) of the initiating event frequency ranges, and maintaining the upper bounding values for the other two inputs.
Some segment ruptures may lead to core damage sequences that create conditions in containment which increase the conditional containment failure probability (CCFP) f given a core damage above 0.1. EPRI TR-112657 requires that the impact on containment associated with sequences that have CCDPs greater than 1E-5/10E-7 (or medium / low sequences if using the tables) be evaluated to determine if a CCFP of greater than 0.1 is expected for each sequence. (OPEN ISSUE: Page 3-26 includes High/ Medium for BWR but only High for PWRs.)
Resolution: EPRI will revise the text.
The methodology includes an evaluation of the plant specific isolstion valve e
unavailabilities to confirm that the categories in Table 3-12 are appropriate. (OPEN ISSUE, if the unavailabilities alone do not support the suggested categories, the applicant should evaluate the CCDP given a LOCA outside of containment and determine what consequence categories correspond to the CLERP guidelines.)
Resolution: EPRI will add guidance for what a licensee should do if the categories are not appropriate.
Human Actions to isolate Breaks (OPEN ISSUE: the explanation on Page 3-20 in the e
submittal is insufficient to explain how to do the analysis.)
Resolution: EPRI will add an explanation.
l This methodology implies, but does not seem to require, that the recovered train can be used to mitigate the sequence (recovery of one train of emergency feedwater following l
a large LOCA in a PWR would not provide useful mitigating capacity) and that the recovered train is " worth" about one train (recovery of a reactor core isolation cooling
[RCIC] train with an unavailability of 0.1 should not be credited as 0.01, e.g., a full mitigating train) (OPEN ISSUE: The requirement that no more credit than the recovered train be taken is not in the TR.)
Resolution: EPRI will clarify the requirement.
C. Carpenter August 11, 1999 The TR does not caution that some operator recovery actions in a PRA credit the e
recovery of the failed component; for example, starting a pump upon failure of the automatic signal. During all CCOP, conditional large early release probability (CLERP),
and confirmatory calculations, it would be incorrect to retain those equipment recovery 4
actions which would not be possible when the equipment failure is due to environmental conditions.
Resolution: EPRI will add the caution.
The staff does not normally review and approve specific calculation input parameters for generic use by all licensees in all applications. The staff does review and approve the methods, guidelines, and individual bounding values that can be shown to be generic. In the Markov method the staff has not reviewed the numerous input parameters. Individual applicants are responsible for assuring that all operation experience used is applicable to their plant, that it was used in an appropriate manner, and that any calculations performed on the data are done according to the approved methodology. The staff may review these calculation or the results of licensee's review to determine the acceptability of the data analysis and the data used on a case by case basis. (OPEN ISSUE: The necessity for this review is not discussed in the topical report.)
Resolution: EPRI did not anticipate that the staff would approve all the input values.
The staff will clarify in the SER (if necessary) that the licensees remain responsible for the appropriateness of the input values they use in the method.
5.
Appendices The text should indicate that the contents of specific applications must fulfill the following minimum staff information requirements. The following text was taken from the WCAP-145721-NPA SER:
Submittal Contents (1) justification for statement that PRA is of sufficient quality (2) summary of riskimpact (3) current inspection Code (4) impact on previous relief requests (5) revised FSAR pages impacted by the change, it any (6) process followed (WCAP, Code Case, and exceptions to methodology, if any)
(7) summary of results of each step (e.g., number of segments, number of HSS and LSS segments, number oflocations to be inspected, etc.)
(8) a statement that RG pn'nciples are met (or any exceptions)
(9) summary of changes from current ISI program (10) summary of any augmented inspections that would be impacted
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4 C. Carpenter
-6.
August 11, 1999 i
Retrievable Onsite Documentation for'PotentialNRC Audit (1) scope deMnition (2)
. segment deRnition (3) failure probability assessment i
(4) consequence evaluation J(5)
PRA modelruns forthe RI-ISIprogram -
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(6) risk evaluation
. (7) structuralelement/NDE selection (8) change in risk calculation
)
(9).
PRA qualityreview 1
(10) continual assessment forms as program changes in response to inspection results
~ (11) documentation required by ASME Code (including inspection personnel quali6 cation, inspection results, and Raw evaluations)
' Resolution: EPRI did not intend that the sample submittals in the appendices would be l
. a rigid, essentially word-for-word format, but only as general guidance. The staff will intestigate how the topical report and the SER should be worded to recognize the gerieral guidance without rigidly specifying the contents of a submittal. The staff and
. EPRI briefly reviewed the EPRI onsite documentation chapter, and EPRI will make j
some clarifications and additions to address the 11 items discussed above.
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6.
Miscellaneous L
l-There is an error in the equation for "V" on Page 2-22.
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Reso!ytion: The equation has been corrected.
e item 5 on Page 3-36 needs clarification.
Resolution: Item 5 has been revised for clarification, j
'e Definition of RI-ISI Classes on Page 3-60 needs clarification.
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Resolution: Definition has been clarified.
is the criteria for flaw evaluation and sample expansion Section 3.6.2.2 same as the e
ASME criteria. If so, why notjust give reference to the ASME Code.
Resolution: The guidance provided is similar to ASME requirements and is acceptable to the staff, Pages 3-85 and 3-87 of Section 3.7.1 state that bounding values for large, small and e
none rupture potential are 1E-3,1E-4, and 1E-5. EPRI should provide the basis for these values.
i C.:- Carpenter
-7 August 11, 1999 I
Resolution: Pages 2-16 and 3-85 provide the bases. Figure 2-2 has been deleted.
e The logic in the flow chart (Figure 34) needs to be clarified.
j Resolution: EPRI will clarify the flow chart.
o
_The requirements for relief request submittals Section 6.4 need to be clarified.
Resolution: Clarification has been provided on Page 6-9. EPRI will provide further clarification in the final TR.
EPRI intends to make these changes to the next revision of the topical report in July 1999.
i The staff intends to issue a draft SER in August to support the September ACRS meeting.
~ This should allow issuance of a final SER in October 1999.
i Project No. 669
~ Attachments: As stated l
cc w/attachs: See next page l
l 1
i i
4 C.' Carpenter" 7..
August 11,'1999 Resolution: Pages 2-16 and 3-85 provide the bases. Figure 2-2 has been deleted.
e-The logic in the flow chart (Figure 3-6) needs to be clarified.
. Resolution: EPRI will clarify the flow chart.
i
. The requirements for relief request submittals Section 6.4 need to be clarified.
e Resolution! Clarification has been provided on Page 6-9. EPRI will provide further i
clarification in the final TR.
EPRI intends to make these changes to the netsvision of the topical report in July 1999.
i
-The staff intends to issue a draft SER in August to support the October ACRS meeting. This should allow issuance of a final SER in November 1999.
Project No. 669 Attachments: 'As stated cc w/attachs: See next page Distribution: (w/all attachs)
/ Central Files Public.
RGEB R/F-i JWilson E-Mail: (w/ attach 1) -
'l SDinsmore. MRubin
- RBarrett SAli BZaleman j
DMatthewc - SNewberry RHermann WBateman SDembeck-l DOCUMENT NAME: a:Nhwi\\mtsm.715
- see previous concurrence i
OFFICE RGE N 3 SC:RGEB*
C:SPSB*
C:EMCB*
C:RGEB NAME JHWilsd:'bf BZalcman RBarrett WBateman CCarpenb DATE 8/// /99 8/11/99 7/12/99 8/6/99 8/l;/99 OFFICIAL RECORD COPY I
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LIST O,F ATTENDEES AT MEETING WITH EPRI HELD IN ROCKVILLE, MARYLAND ON JULY 15,1999 NAME AFFILIATION E. Sullivan NRC S. Ali NRC S. Dinsmore NRC R. Hermann NRC S. Malic NRC J. Mittman EPRI P. O'Regan EPRI K. Fleming ERIN V. Dimitrijevic Duke Engineering & Services D. Lamond Duke Engineering & Services P. Riccardella StructuralIntegrity Associates
i.
- Project No. 669 Electnc Power Research Institute Mr. Kurt Yeager.
President and CEO Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303 Robin Jones Vice President and Chief Nuclear Officer -
- Electric Power Research Institute
- 3412 Hillview Avenue -
Palo Alto, CA 94303 Mr. Raymond C. Torok Project Manager, Nuclear Power Group Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303 Mr. Gary L. Vine Senior Washington Representative Electric Power Research Institute 2000 L Street, N.W., Suite 805 Washington, DC 20036-Mr. Bindi Chexal Electric Power Research institute
- Post Office Box 10412 Palo Alto, CA 94303 i
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