ML13078A253

03/21/2013 Licensee Meeting Slides Re Joseph M. Farley Nuclear Plant NFPA 805 Fire Modeling LAR Submittal - Session 8

ML13078A253
Person / Time
Site:	Farley
Issue date:	03/19/2013
From:	Southern Nuclear Operating Co, Southern Co
To:	Division of Operating Reactor Licensing
Brown E
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ML13078A284	List: ML13078A245 ML13078A246 ML13078A247 ML13078A248 ML13078A250 ML13078A251 ML13078A252 ML13078A253 ML13078A255
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Download: ML13078A253 (16)

Text

FNP NFPA 805 LAR Submittal Overview March 19-21, 2013 Nuclear Safety Capability Assessment

Summary

• NSCA Methodology & Development

• G Governingi C Criteria it i

• Fault Tree Implementation

• C Computer-Based Analysis Process

• Compliance Strategies & VFDR Identification

• Table B-3 Development

• Fire Risk Evaluations

- Recovery Actions

- Defense-in-Depth NSCA Slide 2 of 16

NSCA Methodology

• Performed IAW governing documents and project instructions

• Strict and formal analysis conventions

• Emphasis on consistency and standardization

• Analysis driven by Function States, not just equip ID

• Appendix R analysis used as basis

• Integration of graphical analysis tools (ARCPlus)

NSCA Slide 3 of 16

NSCA Development

• NSCA model based on NFPA 805 performance criteria implemented via CAFTA fault tree

• Detailed development and mapping of vital auxiliaries

- Clearly defined support system impacts

- Automatic generation of cascading power supply impacts

• Safe and Stable

- Encompasses p Modes 1-3

- Long-term Mode 3 capability addressed

• Incorporated Off-site Power NSCA Slide 4 of 16

Governing Criteria

• NEI 00-01, Rev.1

- Initial Work to Rev.1

- Gap analysis performed to Rev. 2 (per Generic RAI 10 and RG 1.205)

- MSO tto Rev.

R 2/3

• NFPA 805

• Applicable A li bl FAQ FAQs

- FAQ 07-0030 FAQ 07-0038 FAQ 09-0057

- FAQ 08-0054 08 0054 FAQ 07-0039 07 0039

• NEI 04-02, Rev. 2 NSCA Slide 5 of 16

NSCA Fault Trees

• Top-down development based on NFPA 805 Performance Criteria

• Strict mapping to circuit analysis via Basic Event-to-Function State Matrix

• All equipment dependencies built into model

- Eliminate manual assessment of support system failures - Avoid missing dependencies

- Significantly improved analysis fidelity

- More precise failure identification

• Highly intuitive understanding of losses NSCA Slide 6 of 16

NSCA Fault Trees NSCA Slide 7 of 16

NSCA Fault Trees NSCA Slide 8 of 16

NSCA Fault Trees NSCA Slide 9 of 16

NSCA Fault Trees NSCA Slide 10 of 16

Computer Analysis Process

• Equipment / Circuit Analysis / Fire Area data superimposed on CAFTA model

• Software produces area-by-area failures and graphically depicts on fault tree

• Analyst dispositions failures

- Identifies and documents deterministic compliance basis

- Identifies and documents VFDR based on intended method of accomplishment NSCA Slide 11 of 16

Computer Analysis Process RED shows failure propagation based on Function State l

losses in i fire fi area NSCA Slide 12 of 16

Deterministic Compliance & VFDRs

• Basis for deterministic compliance

- Cable protected

- Detailed circuit analysis

- Licensing action

- Approved exemption

- Etc.

• VFDRs

- Explicitly documented in software using defined binning method and conconventions entions

- Exported to Table B-3 NSCA Slide 13 of 16

VFDRs and Table B-3

• VFDRs Written at low Level instead of summary level

• Provides higher precision and better understanding of failures

• Precludes masking masking of compounded failures

• Potentially perception that extent of problems are greater than they actually are (i.e., more VFDRs documented than method which documents at system level)

• Table B-3

- Captures all VFDRs

- All pre-transition OMAs treated as VFDRs

- Documents methods of accomplishment NSCA Slide 14 of 16

Fire Risk Evaluations

• Extensive effort to assure alignment between PRA and NSCA

- Ensure accurate treatment of VFDRs

- More realistic delta CDF values

- Examples - MSO, cascading failure, HVAC, etc.

• Recovery Actions

- Feasibility assessments per FAQ 07-0030

- DID RAs for Alternate shutdown areas

• Units 1 and 2 analyzed separately, but cross unit impacts considered NSCA Slide 15 of 16

Q Questions ti  ?

NSCA Slide 16 of 16