ML053490153

Slides - December 8, 2005, Meeting with Energy Northwest on the Risk-Informed Diesel Generator Allowed Completion Time Extension

ML053490153
Person / Time
Site:	Columbia
Issue date:	12/08/2005
From:	Energy Northwest
To:	Office of Nuclear Reactor Regulation
References
TAC MC3203
Download: ML053490153 (15)

Text

Pesoplie,*Vision, S~ollutionxs Columbia Generating Station Diesel Generator CT Extension NRC Public Meeting December 8, 2005

7 AGENDA

• Introductions -

W.S. Oxenford, Energy Northwest M.E. Mayfield, U.S. Nuclear Regulatory Commission

• License Amendment Request for Extension of Diesel Generator Completion Time - G.V. Cullen

• Risk-informed Submittal

• Station Safety Enhancements

• Offsite Power Configuration

• Previously Approved Submittals

• CGS Response to NRC Concerns

• Summary

• NRC Feedback

• Review of Action Items g 2E ERG Y X ONORT HWEI ST Page 2 People *Vision *Solutions

Risk-Informed Submittal

• Regulatory Guide 1.200 Pilot Submittal

• Peer Review Team

- Assessed quality of PRA prior to use for the DG CT extension risk-informed application

- Determined modeling assumptions well defined and capture c within base model documentation

- Amendment affecting Facts & Observations (F&Os) resolved

• NRC on-site review of Columbia's PRA

• NRC Review Team comments resolved g3oENERGY I Page 3 v NORTHWVEST People-Vision-Solutions

Risk-Informed Submittal

• Regulatory Guide 1.177/1.174

• Risk metrics meet criteria for "very small risk region" (RG 1.174)

• Risk metrics for ICCDP met (RG 1.177)

• Key principles met E- Compliance with existing regulations

- Consistent with defense-in-depth philosophy

- Maintain sufficient safety margin

- No significant increase in core damage frequency

- Use of performance measurement strategies

- maintenance rule

_iPage Pe 4 4

PpleiOTHnWS EST People *Vision *Solutions

Station Safety Enhancements Plant Modifications Additional 480v AC Source to Battery Chargers (DG-4)

• DG purchased and staged

• Hard wiring installed to simplify and shorten deployment

• Greatly extends power availability to preferred coping equipment (RC , ADS and Siwitchgear Control Power)

• Battery capacity no longer limits SBO coping duration Pg P ENERGY l

N PageS5 X NORTHWVEST People *Vision *Solutions

Station Safety Enhancements 2 Plant Modifications (continued)

Additional 4.16kv AC Source for Selected Safe Shutdown Loads (Div 3 DG Cross Connect to Div 1 or 2)

• CGS modified to add capability in response to RAI

• Providing procedures and training to facilitate implementation

• Significantly enhances flexibility and safety for LOOP and SBO responses Pag 6ENpERGY

..NORTHWVEST Page 6 People *Vision*Solutions

Station Safety Enhancements Risk Management

• Risk Management Action Commitments for Extended DG CT Include:

• Extended DG CT will not be entered for scheduled maintenance purposes if severe weather or high stress grid conditions are expected

• Verify current grid stability and forecasted grid conditions g7 P e NERGY lPage l 7 w NORTHWVEST People-Vision-Solutions

Station Safety Enhancements Risk Management (continued)

Greatly restrict maintenance activities on station

• No testing or maintenance on the protected DGs

• No testing or maintenance on plant distribution system connections to off-site power sources

• No testing or maintenance on HPCS and RCIC

• Restricted testing and maintenance on risk-significant equipment

• System load dispatcher contact on daily basis

• Other commitments g8 NORTHWpEST l Page 8 People *Vision *Solutions

Offsite Power Configuration Federal Columbia River Power System (FCRPS)

-l

• Infrastructure includes 500kV, 230kV and 115kV AC Transmission systems Columbia Generating Station interconnections to grid:

- Main Generator output is to the 500kV system at Ashe substation (two bus, breaker-and-a-half scheme, 500kv lines to other substations)

- Preferred offsite source to CGS is from the 230kV system at Ashe (not connected to 500 kV yard at Ashe)

- Backup offsite source to CGS is from the 115kV system at Benton substation (on separate right of way from the 230kV system) l* Regional grid on east side of the state includes significant hydroelectric generating resources to continuously support station service to Columbia

• Diverse Black Start capability in the FCRPS enhances recovery of station service to Columbia during LOOP/SBO events g ENERGYioSo

- Page 9 X ~NORTWS People *Vision *Solutions

Industry Precedent

• Columbia Originally Modeled after Clinton Submittal - Approved without Cross Connect

• Columbia Similar to River Bend and Grand Gulf Submittals - Approved with Addition of Cross Connect

• Time frame commitment for implementation of cross connection same as committed by RB and GG

• Defense-in depth and Safety at CGS are Equal or Greater g ENERGY Page 10 X NORTHWVEST People *Vision *Solutions

In dustry Precedent

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Grand Gulf/River Bend SBO Comparison

• GG and RB Credit RCIC With HPCS as Backup

• Columbia credits HPCS with RCIC as preferred system (in essence HPCS is backup)

- Columbia credits HPCS for 10CFR 50.63 coping

- Columbia committed on docket to have RCIC as preferred SBO response equipment

- FSAR states RCIC is preferred SBO source

- SBO procedures direct operators to RCIC first

- From safety and risk standpoint this makes Columbia similar to RB and GG PENERGY Page 12 X NORTHWVEST People *Vision *Solutions

CGS Response to NRC Concerns

• Using DG-3 for SBO and Cross Connect Does Not Cause Licensing Basis Conflict

- Unlike PWRs, Division 1 & Division 2 have only LP AC ECCS systems for injection and decay heat removal

- When cross connection would be used:

- Plant will be at low pressure and high pressure injection is not required or

- HPCS has successfully mitigated the SBO

- Determination that offsite power will not be restored within 4-hour coping time

- Failure of HPCS

- RCIC functioning fully to mitigate SBO (and well beyond coping requirement o f4 hours)

Pg 1ENERGY S X NORTHWVEST Page 13 People *Vision *Solutions

CGS Response to NRC Concerns

• Implementation procedures will provide for swap-over to be accomplished in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> from decision to implement 9 Bus alignment - less than 90 minutes

• Bus energization - less than 30 minutes

• Ability to maintain core cooling and safe shutdown assured by HPCS plus DG-3 cross connect g ENERGY Page 14 NORTHWVEST People *Vision *Solutions

Summnary Conclusion

• Risk-Informed Process Guidance Followed and Satisfied

• Station Safety Significantly Enhanced to Satisfy Requirements and RAI

• Similar to Precedent Approved Submittals P ENERGY X NORTHWVEST Page 15 People *Vision-*Solutions

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