ML080280137
| ML080280137 | |
| Person / Time | |
|---|---|
| Issue date: | 02/26/2008 |
| From: | Cunningham M NRC/NRR/ADES/DRA |
| To: | Bradley B Nuclear Energy Institute |
| Dinsmore S | |
| Shared Package | |
| ML080280127 | List: |
| References | |
| Download: ML080280137 (10) | |
Text
February 26, 2008 Mr. Biff Bradley, Director Risk Assessment Nuclear Energy Institute Suite 400, 1776 I Street, NW Washington, D.C. 20006-3708
SUBJECT:
PROBABILISTIC RISK ASSESSMENT QUALITY REQUIREMENTS FOR RISK-INFORMED INSERVICE INSPECTION (ISI).
Dear Mr. Bradley:
By email dated December 3, 2007, Victoria Anderson of the Nuclear Energy Institute (NEI) provided Stephen Dinsmore in NRC/NRR/DRA/APLA an email with the subject Draft White Paper on Risk-Informed PRA Capability. The email included two attachments, draft NEI Position Paper Probabilistic Risk Assessment (PRA) Technical Adequacy for Risk-Informed Inservice Inspection (RI-ISI) and draft PRA Quality Requirements for Application of the EPRI RI-ISI Traditional Approach (TR-112657) and PWROG RI-ISI Methodology (WCAP-14572).
The email and the two attachments are provided as Enclosures 1, 2, and 3 of this letter.
The email and attachments address discussions from two public meetings between the NRC staff and industry to discuss two related issues: (1) how RI-ISI relief requests based on TR-112657 or WCAP-14572 methods can be shown to comply with the requirements of RG 1.200 (Minutes ADAMs Accession Number ML072150191) and (2) how RI-ISI relief requests based, in part, on ASME Code Case N-716 can be shown to comply with the requirements of RG 1.200 (Minutes ADAMs Accession Number ML072150343). RI-ISI relief requests based, in part, on Code Case N-716 rely on a flooding analysis done in accordance with the ASME standard while other RI-ISI methods rely, instead, on a RI-ISI specific pipe rupture analysis.
The staff has evaluated the email and attached documents and cocluded that the information in the attachments can be used to further define the PRA quality requirements for RI-ISI. As discussed in the staff comments in Enclosure 4 of this letter, the staff has concluded that the white paper discussion on Topic 1, including the information in Table 1 (general demonstration of compliance with RG 1.200) requires further development. Additional information that will be required is discussed in Enclosure 4. The white paper discussion on Topic 2 that is contained in Table 2 (Code Case N-716 compliance with RG 1.200) is sufficiently complete to be used as a basis for further discussions.
B. Bradley The Staff suggests that NEI provide a topical report instead of the white paper so that the NRCs review and approval process can be used. A single topical report could address both topic 1 and topic 2. Guidance on determining the capability of a PRA needed to support a particular risk-informed application can be found in Section 3 of RA-Sb-2005. The staff intends to issue a meeting notice for a March 2008 public meeting to discuss these topics.
Sincerely,
/RA/
Mark A. Cunningham, Director Division of Risk Assessment Office of Nuclear Reactor Regulation
Enclosures:
As Stated cc w/encl: See next page
B. Bradley The Staff suggests that NEI provide a topical report instead of the white paper so that the NRCs review and approval process can be used. A single topical report could address both topic 1 and topic 2. Guidance on determining the capability of a PRA needed to support a particular risk-informed application can be found in Section 3 of RA-Sb-2005. The staff intends to issue a meeting notice for a March 2008 public meeting to discuss these topics.
Sincerely,
/RA/
Mark A. Cunningham, Director Division of Risk Assessment Office of Nuclear Reactor Regulation
Enclosures:
As Stated cc w/encl: See next page DISTRIBUTION:
DRA r/f RidsNrrDpr RidsNrrDprPspb RidsNrrPMTMensah RidsNrrLADBaxley RidsOgcMailCenter RidsAcrsAcnwMailCenter RidsNrrDirsItsb RidsNrrDraApla CDoutt SRosenberg ADAMS ACCESSION NO Pkg. ML080280127.
Memo ML080280137 Encl 2: ML080280379 Enclosure 3: ML080280366 OFFICE NRR/APLA NRR/APLA NRR/DRA NAME SDinsmore MRubin MCunningham DATE 02/11/08 02/11/08 02/26/08 OFFICIAL RECORD COPY
References:
Regulatory Guide 1.200 An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities (RG 1.200)
(ADAMs Accession number ML07024001).
ASME Code Case N-716 Alternative Piping Classification and Examination Requirements,Section XI Division 1. (N-716)
ASME RA-Sb-2005, Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications, Addendum B to ASME RA-S-2002, ASME.
(RA-Sb-2005)
Mr. Anthony Pietrangelo, Vice President Regulatory Affairs Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 arp@nei.org Mr. Jack Roe, Director Operations Support Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 jwr@nei.org Mr. Charles B. Brinkman Washington Operations ABB-Combustion Engineering, Inc.
12300 Twinbrook Parkway, Suite 330 Rockville, MD 20852 brinkmcb@westinghouse.com Mr. Gary L. Vine, Executive Director Federal and Industry Activities, Nuclear Sector EPRI 2000 L Street, NW, Suite 805 Washington, DC 20036 gvine@epri.com Mr. James Gresham, Manager Regulatory Compliance and Plant Licensing Westinghouse Electric Company P.O. Box 355 Pittsburgh, PA 15230-0355 greshaja@westinghouse.com Ms. Barbara Lewis Assistant Editor Platts, Principal Editorial Office 1200 G St., N.W., Suite 1100 Washington, DC 20005 Barbara_lewis@platts.com Mr. Alexander Marion, Executive Director Nuclear Operations & Engineering Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 am@nei.org
Mr. Jay Thayer, Vice President Nuclear Operations Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 jkt@nei.org Mr. John Butler, Director Safety-Focused Regulation Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 jcb@nei.org Mike Melton, Senior Project Manager 1776 I Street, NW, Suite 400 Washington, DC 20006-3708 man@nei.org Mr. James H. Riley, Director Engineering Nuclear Energy Institute 1776 I Street, NW Washington, DC 20006-3708 jhr@nei.org
ENCLOSURE 1 Email from:
Victoria Anderson of the Nuclear Energy Institute (NEI)
To:
Stephen Dinsmore in NRC/NRR/DRA/APLA From:
"ANDERSON, Victoria" <vka@nei.org>
To:
<scd1@nrc.gov>
Date:
12/03/2007 5:00:44 PM
Subject:
Draft White Paper on Risk Informed ISI PRA Capability
- Steve, Attached is the draft white paper on PRA Capability and Risk-Informed ISI that Biff discussed with you on Friday. Please take a look at this paper and get back to me regarding the next step.
-Victoria Victoria K. Anderson Project Manager, Risk Assessment Nuclear Energy Institute 1776 I St. N.W., Suite 400 Washington, DC 20006 www.nei.org <http://www.nei.org/>
P: 202-739-8101 F: 202-533-0173 E: vka@nei.org <mailto:vka@vka@nei.org>
nuclear. clean air energy.
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CC:
"BRADLEY, Biff" reb@nei.org
ENCLOSURE 4 NRC Staff Commments on NEIs draft white paper and attachments provided to the NRC by email on 12/03/07 By email dated December 3, 2007, Victoria Anderson of the Nuclear Energy Institute (NEI) provided Stephen Dinsmore in NRC/NRR/DRA/APLA an email with the subject Draft White Paper on Risk-Informed PRA Capability. The email included two attachments, NEI Position Paper Probabilistic Risk Assessment (PRA) Technical Adequacy for Risk-Informed Inservice Inspection (RI-ISI) and PRA Quality Requirements for Application of the EPRI RI-ISI Traditional Approach (TR-112657) and PWROG RI-ISI Methodology (WCAP-14572).
The staff and industry have had two public meetings to discuss two related issues, (1) how RI-ISI relief requests based on TR-112657 or WCAP-14572 methods can be shown to comply with the requirements of RG 1.200 (ML072150191) and (2) how RI-ISI relief requests based, in part, on ASME Code Case N-716 can be shown to comply with the requirements of RG 1.200 (ML072150343). RI-ISI relief request based, in part, on Code Case N-716 rely on a flooding analysis done in accordance with the ASME standard while other RI-ISI methods rely, instead, on a RI-ISI specific pipe rupture analysis.
The white paper discussion on Topic 1, including the information in Table 1 (general demonstration of compliance with RG 1.200) requires significant further development.
Additional information that will be required is discussed in the comments below. The white paper discussion on Topic 2, that is contained in Table 2 (compliance with RG 1.200 for Code Case N-716 method) is sufficiently complete to be used as a basis for further discussions.
The Staff proposes that NEI provide a topical report instead of the white paper so that the NRCs review and approval process can be used. A single topical report could address both topic 1 and topic 2. Guidance on determining the capability of a PRA needed to support a particular risk-informed application can be found in Section 3 of RA-Sb-2005. The staff intends to issue meeting notice for a March 2008 public meeting to discuss these topics.
Topic 1: Quality of PRA satisfying RG 1.200.
The EPRI (ADAMs Accession number ML013470102) and WOG RI-ISI (ADAMs Accession number ML012630349) methods require a RI-ISI specific pipe rupture analysis and do not rely on a PRA flooding analyses. There is, however, reliance on the PRA in general to support the RI-ISI pipe rupture analysis. During the July 17, 2007, public meeting, we discussed how a gap analysis required by RG 1.200 on a PRA used to support the RI-ISI pipe rupture analysis might be limited to a well defined subset of supporting requirements in ASME Standard RA-Sa-2005.
The white paper proposes that satisfying the mitigating systems performance indicator (MSPI)
(ML043510095) supporting requirements (and IE-A2 and LE-A2) is equivalent to satisfying RG 1.200 requirements for RI-ISI. This may be appropriate, but the general justification that "MSPI addresses mitigating systems for loss of coolant initiating events" is not sufficient to support this conclusion. The following issues should be addressed.
- 1. The Scope of Application column in Table 1 should be made consistent with current endorsed guidance (e.g., N560 has never been endorsed but EPRI and WOG Topical methods have)
- 2. A more detailed evaluation of why a PRA of sufficient quality for MSPI applications would also have sufficient quality for RI-ISI applications is needed. The MSPI process relies on importance measure for a number of system functions. A sub-set of the ASME supporting requirements were identified for particular attention based on their crucial role for directly affecting these importance measures. RI-ISI applications relies on the conditional core damage and large early release probabilities for a number of system functions. NEI should provide an evaluation that demonstrates the consistency (or differences) between the system functions and PRA results important to MSPI and those important to RI-ISI.
- 3. The MSPI task force report recommended a gap analysis on the important supporting requirements but it is unclear if all licensees performed this gap analysis. Some licensees may have relied on an industry wide cross-comparison. NEI should explain how licensees have demonstrated that their PRAs satisfy the MSPI quality requirements and how this demonstration is sufficient to support RI-ISI.
- 4. During the July 17, 2007 meeting, NEI requested some ADAMs Accession numbers for RI-ISI relief requests where facts and observations (F&Os) regarding specific ASME supporting requirements were evaluated for their potential affect on RI-ISI pipe rupture analysis. The following Accession Numbers were provided to NEI by email but are not discussed in the White paper. NEI should provide some discussion comparing and contrasting these plant specific RI-ISI results with the supporting requirements determined to be important/unimportant for MSPI application.
The following ADAMs Accession numbers are for RI-ISI submittals that included information on plant specific F&O's and their resolution for RI-ISI.
ML042610214 ML012750204 ML052430399 ML031180030 ML032030059 ML051370346 ML052080045 ML053050446 Topic 2: Quality of the flooding PRA The RI-ISI method based, in part, on ASME Code Case N-716 relies on the PRA flooding analyses. Table 2 of the White paper proposes capability categories for each of the ASMEs flooding analysis supporting requirements. RI-ISI submittals that reference Code case N-716 will need to address the supporting requirements for the PRA flooding analysis. A PRA flooding analysis relies, in turn, on the PRA in general. Therefore, as illustrated in Table 1 of the white paper, all RI-ISI submittals must address Topic 1.
The NRC has not endorsed Code case N-716. Two individual RI-ISI applications that referenced ASME Code Case N-716 RI-ISI have been approved after some modifications to the method by each licensee (ADAMs Accession numbers ML072430005 and ML072620553).
Determination that the quality of the PRA analysis was sufficient in these applications was based on consistency between the licensees flooding PRA analysis and the requirements for the RI-ISI pipe rupture analyses approved in the Topical Reports. As illustrated in ML072620553, the staff has concluded that a flooding analysis that is consistent with the supporting requirements in RA-Sb-2005 can provide confidence that the quality of the PRA analysis is sufficient for a RI-ISI application.
Individual licensee flooding analysis supporting requirements are assigned a capability category.
The Assessment column in the Table 2 provides the industry proposal for capability categories that would be sufficient to achieve the quality required for a RI-ISI application based, in part, on Code Case N-716. The staff has concluded that Table 2 is sufficiently complete that it can support detailed discussions in a public meeting.