ML18017B141

NRC Slides for Jan 18, 2018, Public Meeting to Discuss Licensee Methods of Accounting for Seismic Risk in 10 CFR 50.69 Applications Without Using a Seismic Probabilistic Risk Assessment

ML18017B141
Person / Time
Issue date:	01/17/2018
From:	Ed Miller Special Projects and Process Branch
To:	Ed Miller Special Projects and Process Branch
References
Download: ML18017B141 (16)

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1 NRR-DMPSPEm Resource From: Miller, Ed Sent: Wednesday, January 17, 2018 12:27 PM To: Miller, Ed

Subject:

NRC Slides for Jan 18, 2018, Public Meeting on 10 CFR 50.69 Attachments:

Jan18_2018_public meeting 10 CFR 50_69 NRC Slides.pdfSlides for the subject meeting are attached.

Hearing Identifier: NRR_DMPS Email Number: 98 Mail Envelope Properties (DM5PR0901MB23928383CA83D58F33AA3C61E9E90)

Subject:

NRC Slides for Jan 18, 2018, Public Meeting on 10 CFR 50.69 Sent Date: 1/17/2018 12:26:31 PM Received Date: 1/17/2018 12:26:33 PM From: Miller, Ed Created By: Ed.Miller@nrc.gov Recipients: "Miller, Ed" <Ed.Miller@nrc.gov>

Tracking Status: None

Post Office: DM5PR0901MB2392.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 48 1/17/2018 12:26:33 PM Jan18_2018_public meeting 10 CFR 50_69 NRC Slides.pdf 430025 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: Recipients Received:

50.69 LARs NRC Observations January 18, 2018 public meetingSteve Dinsmore/ Mihaela BiroDivision of Risk AssessmentOffice of Nuclear Reactor RegulationU.S. Nuclear Regulatory Commission 2 Topics*Status*Categorization Process Description

• PRA Quality Issues

• F&O Dispositions

• PRA Model Uncertainties

• External Hazards

• Passive Categorization

• Conclusions 3 Status*Pilot submitted August 2012, issued December 2014*Draft NEI template provided for NRC comment August 2016-Template differed from pilot LAR-Formal NRC review not requested, not performed*Public meetings August 2016, January 2017, June 2017, October 2017.*As of January 18, 2017, 9 LARs based on template in house, many more LARs

expected 4 Categorization Process Description -Pilot*The Pilot LAR included a detailed description of the process for categorization -Procedures governing process -Observation of trial IDP deliberations

-Observation of results of two systems categorizations*The Pilot LAR included explanation of how the process was consistent with process endorsed

in NEI 00-04*The pilot review revealed the categorization process is fairly complex and flexible 5 Categorization Process Description -Template*10 CFR 50.69 (b)(2)(i) requires a description of the categorization process in LARs*Template LAR provides no description of process-states that the categorization process will be "in accordance with NEI 00-04" -followed by deviations and clarifications*Previous staff comments on LAR template-Text in template descriptive of required information, not boilerplate-LAR should address plant specific implementation and procedures*Template should be revised to provide the required plant specific process description 6 Categorization Process Description -Current LARs*NEI 00-04 contains a number of steps performed in certain order-Changing the steps or the order could impact the results presented to the IDP and thus the categorization*Staff has developed an RAI requesting a summary description of the process, e.g.,-sequence of steps-when IDP can re-assign preliminary HSS components

-component vs. function categorization

-how the passive categorization integrates in the overall process*Expectation is that future LARs will include a plant specific summary description of process that will be implemented at the pant 7 Categorization Process Description -Plant Specific 8 PRA Quality Issues *Adequate PRA quality needed*Need the peer and F&O review history up to the date of the LAR*PRA models need to reflect the current as-built, as operated plant*All unclosed F&Os need to be reported in the LAR and dispositioned for this application*General statement that "only methods acceptable to NRC are used" could help minimize RAIs about fire and seismic methods-Summary about how this conclusion was reached should be added to the LARs-F&Os should be consistent with this observation 9 F&O Dispositions*F&O Disposition should either:-justify why the F&O has no impact on the categorization, either with a reasonable technical discussion or a sensitivity study, or-summarize an acceptable change to the PRA and commit to implementing it, followed by a focused scope peer review if it was an

upgrade*Insufficient to state that the impact of resolving F&O will be evaluated and fixed if it could affect categorization 10 PRA Model Uncertainties*NEI 00-04 discusses "[A]pplicablesensitivity studies identified in the characterization of PRA

adequacy"*RG 1.201, interprets this as dealing with uncertainties "associated with the licensee's choice of specific models and assumptions"*NUREG-1855 discusses identifying key sources of uncertainty and assumptions *Includes any not commonly accepted methods and assumptions *Like F&O resolution, disposition for each important model uncertainty is PRA model specific and

should be reported in the LAR 11 External Hazards*Fire -PRA, updated FIVE (screening) in NEI 00-04; Safe Shutdown list proposal under review*Seismic -PRA, updated SMA (screening) in NEI 00-04; generic alternative proposal part of this

meeting*Other screening (e.g., meets the SRP or low CDF) which assigns nothing to HSS based on "low risk"

does not meet the guidance in NEI 00-04*hazards of less magnitude but higher frequency not automatically low risk*SSCs that cause low CDF/LERF might be HSS*Step in Fig. 5-6 asks if removal of SSC could result in screened scenario becoming unscreened 12 External Hazards (cont'd)*Figure 5-6 in Section 5.4 of NEI 00-04summarizes the process that begins with the SSC selected for categorization and then proceeds through the flow chart for each external hazard 13 Passive Categorization*ANO-2 passive categorization methodology excludes all Class 1 pressure boundary components*Code Case N-660 allows including the following Class 1 components, but includes additional stepsi.breaks small enough for makeup provided by the reactor coolant makeup system; orii.The component is or can be automatically isolated from the reactor coolant system by two valves in series*RG 1.147, referenced in RG 1.201, accepted Code Class N-660 with limitation that it must be applied to only Code Class 2 and 3, and non-code*Deviation from ANO-2 or accepted N-660 is not a short term solution 14 Conclusions *LARs need to include categorization process summary description*RG 1.200 PRA quality guidelines apply

• Any deviations should be minimized

• Methods not accepted by NRC should be avoided *Consistency with Figure 5-6 should be demonstrated in LAR*Passive categorization should not deviate from accepted methods in LARs