ML18276A071

From kanterella
Jump to navigation Jump to search

Exelon'S Presentation for October 4, 2018 Public Pre-Submittal Meeting on Planned Calvert Cliffs 10CFR50.69 LAR
ML18276A071
Person / Time
Site: Calvert Cliffs  Constellation icon.png
Issue date: 10/04/2018
From: Bryan Hanson
Exelon Generation Co
To: Marshall M
Plant Licensing Branch 1
Marshall M, NRR/DORL/LPLI, 415-2871
References
EPID L-2018-LRM-0059
Download: ML18276A071 (22)
v • d • e


Text

Calvert Cliffs 10CFR50.69 LAR Pre-Submittal Meeting October 4, 2018

Agenda

  • Introductions
  • Objectives for Meeting
  • Discuss NRC questions on Seismic approach
  • Get alignment on level of detailed need in the LAR

Calvert Cliffs and Industry Attendees

  • Shannon Rafferty-Czincila - Exelon Senior Manager, Risk Management
  • Barry Sloane - Exelon Risk Management
  • Phil Tarpinian - Exelon Risk Management
  • Enrique (Rick) Villar - Exelon Corporate Licensing
  • Rob Cavedo - Exelon Risk Management
  • James Landale - Exelon Risk Management
  • Greg Krueger - NEI
  • Via phone
  • John Koelbel - Exelon Risk Management
  • David Passehl - Exelon Risk Management
  • Jon Kapitz - NEI

Calvert Cliffs 10CFR50.69 - The Rule

  • 10 CFR 50.69 allows adjustment of the scope of equipment subject to special treatment controls (e.g., quality assurance, testing, inspection, condition monitoring, assessment, and evaluation).
  • Allows licensees to focus resources on SSCs that make a significant contribution to plant safety.
  • Allows licensees to categorize SSCs using a risk-informed process.
  • The risk-informed categorization process determines the safety significance of SSCs and place the SSCs into one of four Risk-Informed Safety Class (RISC) categories.

3 Calvert Cliffs 50.69 LAR Pre-submittal meeting

Calvert Cliffs 10CFR50.69

  • The NEI 00-04 provides 2 options for considering seismic risks:
  • An SPRA can be used with specified risk ranking and sensitivity studies to determine seismic related HSS SSCs
  • An IPEEE Seismic Margins Assessment (SMA) equipment list can be used where all of the SSCs on the equipment list are designated HSS.
  • Calvert Cliffs cannot submit 50.69 LAR without an alternative approach to characterize seismic risks
  • Industry developed EPRI TR 3002012988 Alternative Approaches for Addressing Seismic Risk in 10CFR50.69 Risk-Informed Categorization
  • Calvert Cliffs will submit using this approach 4 Calvert Cliffs 50.69 LAR Pre-submittal meeting

NRC Questions and Discussion Application of Seismic Risk Insights Using a Risk Informed Approach RIDM is a top regulatory priority

  • SECY-17-0112, Plans for Increasing Staff Capabilities to Use Risk Information in Decision-making Activities
  • SECY-18-0060, Achieving Modern Risk Informed Regulation Use of this approach is consistent with the a recommendation from SECY-18-0060 (Staff Response to EDO Transformation Letter)
  • expanding the use of qualitative and quantitative risk insights to scale the scope and depth of licensing reviews depending on the safety and security significance of the matter being reviewed The application of a seismic alternative approach to inform the 50.69 categorization process is an example of RIDM
  • The incorporation of insights from contemporary seismic PRAs provide a perspective on the seismic risk contribution to the 50.69 categorization decision making process 6 Calvert Cliffs 50.69 LAR Pre-submittal meeting

1 - Describe the integrated, systematic process being used to support the risk-informed categorization and treatment of SSCs

  • The requirements of 10CFR50.69(c) apply to the entire categorization process, not new approaches to screening a hazard. However EPRI Seismic Alternative approach:
  • Considers the results and insights from the plant-specific PRA.
  • Employs a systematic process to evaluated the seismic hazard which is integrated into the overall categorization process.
  • The EPRI systematic process:
  • Considers the likelihood and magnitude of the seismic hazard.
  • Considers margin to the site specific seismic design basis.
  • Uses insights from categorization trials performed using detailed seismic PRAs, at high seismic hazard sites, to determine the degree to which seismic importance measures contribute to the 50.69 categorization decisions.

- Using those risk-informed insights, a graded implementation process was developed to consider the site-specific contributions of seismic risks in the full NEI 00-04 categorization process in concert with insights from other risk evaluations, Defense-in-Depth considerations, and Integrated Decision-making Panel considerations.

7 Calvert Cliffs 50.69 LAR Pre-submittal meeting

2 - Describe whether the case studies in the EPRI report are bounding for Calvert Cliffs

  • The Case Studies in the EPRI Report are representative and risk-informed for the industry, including Calvert Cliffs.
  • The trials in the EPRI report are performed at sites with high seismic hazards relative to their design basis and are therefore more likely to challenge the seismic capability of the plant and produce unique seismic insights.
  • At Calvert Cliffs, and other Tier 1 plants, the seismic hazard is less challenging compared to the seismic design basis and therefore, the expected unique seismic insights are much less likely.
  • The graded seismic process developed in the EPRI report focuses specifically on 50.69 categorization insights, and consistent with other risk-informed applications recommends focusing efforts where unique insights are more likely to occur and less efforts where they are unlikely.

8 Calvert Cliffs 50.69 LAR Pre-submittal meeting

3 - Describe how the proposed approach addresses the discussion in Section II.1.2 of the statements-of-consideration for 10 CFR 50.69

1. The industry commenters stated that additional PRA requirements were not necessary because the other categorization requirements in § 50.69(c) addressed other modes and events not addressed by the PRA and as a result, all sources of risk were addressed

- The EPRI report addresses this explicitly. The results of the 4 example sites demonstrate that all sources of risk are adequately address by either the results of the other elements of the categorization process (Tier 1 sites), or a combination of the other categorization methods combined with additional correlated failure investigations (Tier 2 sites).

2. and where non-PRA methods are used, the requirements and associated implementation guidance account for this situation by requiring a process that tends to conservatively categorize SSCs into RISC-1 and RISC-2

- NEI 00-04 was written prior to the development of many of the risk-informed processes in use today, and as such the non-PRA processes invoked do tend to produce conservative results.

- The method described in the EPRI report is a risk-informed process based on PRA results, and is demonstrated to produce results equivalent to seismic PRAs 9 Calvert Cliffs 50.69 LAR Pre-submittal meeting

4 - Identify any differences between the approved Limerick 50.69 LAR and the planned Calvert Cliffs 50.69 LAR

  • Calvert will apply the same methodology and implementation of NEI 00-04 as Limerick
  • The only deviation from the NEI 00-04 (and the Limerick 50.69 LAR) is the approach to the screening assessment for the seismic external hazard 10 Calvert Cliffs 50.69 LAR Pre-submittal meeting

5 - Identify which portions of the EPRI report (or information in the EPRI report) will be included in the submittal

  • The entire EPRI report will be submitted as part of the Calvert LAR
  • The LAR will indicate that only those portions of the report that support the Tier 1 approach are applicable to Calvert Cliffs
  • Note: the Tier 2 plant will have the same approach 11 Calvert Cliffs 50.69 LAR Pre-submittal meeting

6 - Identify which portions of the EPRI report that Exelon will be using as the technical justification for the planned amendment

  • The entire EPRI report will be submitted as part of the Calvert LAR
  • The LAR will indicate that only those portions of the report that support the Tier 1 approach are applicable to Calvert Cliffs
  • This includes the majority of the report (excludes Sections 2.3 and 2.4) 12 Calvert Cliffs 50.69 LAR Pre-submittal meeting

7 - Describe whether the alternative approach described in the EPRI report can be considered a bounding approach

  • Approach defined in EPRI Report is a risk-informed, graded process.

- Graded seismic process focuses specifically on 50.69 categorization insights

- Consistent with other risk-informed applications, focuses on where unique insights are more likely to occur rather than where they are unlikely

- Examined sites with high seismic hazards relative to their design basis that are more likely to challenge the plant seismic capability and produce unique seismic insights.

- At Tier 1 and Tier 2 plants, seismic hazard is less challenging compared to design basis, so expectation of unique seismic insights is even less likely.

  • Seismic hazard at Tier 1 plants is sufficiently low that it is unlikely the 50.69 Integral Importances would be driven by seismic risk.

- Integral Importance assessment weighs component importance from each contributor (hazard) by the fraction of the total CDF for that contributor.

- Therefore unlikely that the 50.69 Integral Importance of any component would have a required HSS outcome due to seismic risk for Tier 1.

- Other, non-PRA elements of the 50.69 categorization process provide reasonable confidence that SSC design requirements, including earthquake response, are adequately considered in HSS determination 13 Calvert Cliffs 50.69 LAR Pre-submittal meeting

8 - For the PRAs used in the case studies, state whether the PRAs have been used to support NRC approval of licensing actions comparable to the planned 50.69 LAR PLANT NSSS Containment RG 1.174 Risk-Informed LARs, Comparable to 50.69 LARs, Using RG 1.200 PRAs FPIE FPRA SPRA (INTERNAL)

Mark I (Steel (NS) 50.69 (NS) 50.69 A GE / BWR 4 Drywel and -

Wetwell) (App X) (App X)

(NS) ILRT Westinghouse / Large Dry, B N/A -

3-loop Subatmospheric (no App X)

(NS) 50.69, RICT (NS) 50.69, RICT (NS) 50.69, Westinghouse /

C Large Dry (NR) TMRE,ILRT, # (NR) TMRE,ILRT, # (NR) TMRE,ILRT, #

4-loop (no App X) (no App X) (no App X)

SFCP *, 50.69

Westinghouse / Wet, Ice D N/A 4-loop Condenser (App X) (App X)

Legend:

  • October 2018 # GSI-191 (NS) NRC SER Issue (NR) NRC review in progress 14 Calvert Cliffs 50.69 LAR Pre-submittal meeting

9 - For the SPRAs used in the case studies in the EPRI report, describe whether peer-review findings have been appropriately addressed for risk-informed licensing actions and whether SPRA peer-review findings have been closed out using an NRC-approved process PLANT NSSS Containment RG 1.200 SPRAs Peer NTTF Rec. 2.1 SPRA App. X Review Closure Status Findings ^ Review Mark I (Steel Submitted A GE / BWR 4 Drywel and YES (NR)

ALL NO Wetwell)

Large Dry, Westinghouse Submitted B

/ 3-loop Subatmo- YES (NR)

ALL NO spheric Westinghouse Submitted C

/ 4-loop Large Dry YES (NS)

ALL NO Westinghouse Wet, Ice Submitted D

/ 4-loop Condenser YES (NS)

OPEN YES Legend: ^ Finding Resolutions Reported (NS) NRC SER Issue (NR) NRC review in progress 15 Calvert Cliffs 50.69 LAR Pre-submittal meeting

10 - Discuss the relevance of the Near Term Task Force 2.1 evaluations in determining the appropriate tier for the proposed alternative approaches considering the differences in scope and purpose

  • The 50.69 Seismic Alternate approach uses the best estimate seismic hazard for the site along with the seismic design basis.
  • The site seismic hazard was developed in response to the NRCs NTTF 50.54(f) letter and was reviewed and accepted by the NRC.
  • The site seismic hazards reflect the site, for any purpose.

- The site hazard is the same for all risk informed applications.

  • Threshold for Tier 1 sites has no association with NTTF 2.1 evaluations.

- At Tier 1 sites, GMRS is either very low or within the range of the SSE such that unique seismic categorization insights not expected.

16 Calvert Cliffs 50.69 LAR Pre-submittal meeting

11 - Discuss why correlated failures that are evaluated for Tier 2 plants are not considered for Tier 1 plants (i.e., why Tier 2 evaluations are not performed for Tier 1).

  • At the low seismic hazard sites in Tier 1, the likelihood of identifying a unique seismic condition that would cause an SSC to be designated HSS is very low.

- Based on the trial cases for plants with high seismic ground motions compared to their design basis and detailed SPRAs, few if any SSCs would be designated HSS for seismic unique reasons.

  • This same philosophy would apply to seismic correlated fragilities similarly as seismically independent fragilities.

17 Calvert Cliffs 50.69 LAR Pre-submittal meeting

12 - Describe how risk significant SSCs identified by fire PRA will be addressed considering the incorporation of a new approach that relies on fire PRA models to identify SSCs that are important to safety

  • The approach is not completely reliant on fire PRA models to identify SSCs important to safety
  • EPRI report shows the large majority of seismic risk HSS SSCs are overlaid by FPIE HSS determination; Impacts of fire risk evaluations are limited.
  • It is possible that even these few SSCs would be captured by other portions of the NEI 00-04 categorization process including:

- Defense-in-Depth, Shutdown, IDP qualitative considerations that do not permit downgrading an HSS SSC categorization

- Inclusion of a non-overlapping component in a function that is otherwise HSS and not able to be performed without the individual SSC.

Number of HSS HSS Seismic Fragility HSS Seismic Fragility Trial Plant Seismic Fragility Groups Overlaid ONLY by Groups Overlaid by FPIE Groups Fire Risk Plant A 23 22 1 Plant B 38 38 0 Plant C 28 17 6 Plant D 59 28 3 18 Calvert Cliffs 50.69 LAR Pre-submittal meeting

13 - Describe - how Exelon will address the potential hazard changes that may change the current proposed Tier 1 classification in the future and therefore, the categorization approach with respect to seismic risk

  • NRC Process for Ongoing Assessment of Natural Hazards Information (POANHI)
  • Enhances Safety, Integrated w/ existing process, provides stability & predictability (Ref. NRC SECY-15-0137, SECY-16-0144 )
  • NRC staff proactively and routinely aggregates and assesses new natural hazard info
  • NRC will use existing processes (e.g. GIP, identification of future research)
  • 10CFR50.69(e) (1) - Licensee shall review changes to the plant, operational practices, applicable plant & industry operational experience and update the SSC categorization &

treatment process every 2 refueling outages.

  • Industry processes
1. INPO post-Fukushima actions (IER 13-10) o Sites have implemented a process to formally evaluate challenges to design basis assumptions for external events, i.e. credible new hazard information
2. EPRI o Compiles and analyzes new information annually related to specific External Events, including seismic (Ref. NEI 12-06)
  • Exelon specific OPEX processes
  • Several procedures incorporate the INPO/EPRI Processes

LAR Wording Section 3.2.3

  • CCNPP proposes to apply an alternative seismic approach to those listed in NEI 00-04 sections 1.5 and 5.3. This alternative approach is specified in EPRI 3002012988.
  • CCNPP meets the Tier 1 criteria for Low Seismic Hazard/High Seismic Margin.
  • Tier 1: Plants where the GMRS [Ground Motion Response Spectrum]

peak acceleration is at or below approximately 0.2g or where the GMRS is below or approximately equal to the SSE [Safe Shutdown Earthquake]

between 1.0 Hz and 10 Hz. Examples are shown in Figures 2-1 and 2-2.

At these sites, the GMRS is either very low or within the range of the SSE such that unique seismic categorization insights are not expected.

  • For CCNPP, the 1st criterion is met

Review

  • Objectives for Meeting
  • Discuss NRC questions on Seismic approach
  • Get alignment on level of detailed need in the LAR
Retrieved from "https://kanterella.com/w/index.php?title=ML18276A071&oldid=1921723"