ML18017B141
| 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) | |
Text
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.pdf Slides for the subject meeting are attached.
1
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 meeting Steve Dinsmore/ Mihaela Biro Division of Risk Assessment Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission
Topics
- Status
- Categorization Process Description
- PRA Quality Issues
- F&O Dispositions
- PRA Model Uncertainties
- External Hazards
- Passive Categorization
- Conclusions 2
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.
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 4
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 5
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 6
Categorization Process Description - Plant Specific 7
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 8
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 9
PRA Model Uncertainties
- NEI 00-04 discusses [A]pplicable sensitivity studies identified in the characterization of PRA adequacy
- RG 1.201, interprets this as dealing with uncertainties associated with the licensees 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 10
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
- Step in Fig. 5-6 asks if removal of SSC could result in screened scenario becoming unscreened 11
External Hazards (contd)
- Figure 5-6 in Section 5.4 of NEI 00-04 summarizes the process that begins with the SSC selected for categorization and then proceeds through the flow chart for each external hazard 12
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 steps
- i. breaks small enough for makeup provided by the reactor coolant makeup system; or ii. 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 13
Conclusions
- LARs need to include categorization process summary description
- 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 14