ML101930023

Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01: Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems

ML101930023
Person / Time
Site:	Browns Ferry
Issue date:	07/07/2010
From:	Krich R Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML101930023 (9)

Text

Tennessee Valley Authority 1101 Market Street, LP 3R IIVAI Chattanooga, Tennessee 37402-2801 R. M. Krich Vice President Nuclear Licensing July 7, 2010 10 CFR 50.4 10 CFR 50.54(f)

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Unit 3 Facility Operating License No. DPR-68 NRC Docket No. 50-296

Subject:

Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01: Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems

References:

1. NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated January 11, 2008

2. TVA Three-Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated May 9, 2008

3. TVA Three-Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated June 6, 2008

4. TVA Three-Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated July 11, 2008

5. TVA Nine-Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated October 11, 2008

6. Letter from NRC to Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Re:

Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" Proposed Alternative Course of Action (TAC Nos. MD7799, MD7800, and MD7801), dated September 25, 2008 printed on recycled paper

U.S. Nuclear Regulatory Commission Page 2 July 7, 2010

7. TVA Browns Ferry Nuclear Plant, Unit 1 - Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated March 2, 2009

8. Letter from NRC to the Nuclear Energy Institute (NEI), "Preliminary Assessment of Responses to Generic Letter 2008-01, 'Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,' and Future Nuclear Regulatory Commission Staff Review Plans," dated May 28, 2009

9. Letter from NRC to Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Re:

Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,"

Request for Additional Information, dated August 24, 2009

10. TVA Browns Ferry Nuclear Plant, Unit 2 - Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated September 21, 2009

11. TVA Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Response to Request for Additional Information Regarding Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (TAC Nos. MD7799, MD7800, and MD7801) dated September 21, 2009 The purpose of this letter is to provide the Tennessee Valley Authority (TVA) "Nine-Month (Post-Outage)" response to NRC issued Generic Letter (GL) 2008-01, Reference 1, for Browns Ferry Nuclear Plant (BFN), Unit 3. TVA's initial responses and the "Nine-Month" response were provided in References 2, 3, 4, and 5. NRC acceptance review of the Nine-Month response is provided in Reference 6.

The NRC issued GL 2008-01 to request that each licensee evaluate the licensing basis, design, testing, and corrective actions for the emergency core cooling, decay heat removal, and containment spray systems to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, and that appropriate action is taken when conditions adverse to quality are identified.

This supplemental response is being submitted within 90 days of startup from the outage in which the deferred actions were completed (Unit 3 Cycle 14 Refueling Outage).

GL 2008-01 response activities that remain to be accomplished, such as the long-term items identified in Reference 6, are considered to be confirmatory.

This Unit 3 response is similar to the Unit 1 and 2 responses (References 7 and 10) and addresses applicable NRC requests for additional information (References 9), the TVA response to NRC requests for additional information (Reference 11), and NRC guidance (Reference 8).

U.S. Nuclear Regulatory Commission Page 3 July 7, 2010 TVA concludes that the subject BFN, Unit 3, systems are operable and that BFN; Unit 3, is currently in compliance with the licensing basis documentation and applicable regulations, including 10 CFR 50 Appendix B, Criteria III, V, XI, XVI, and XVII, with respect to the concerns outlined in GL 2008-01 regarding managing gas accumulation in these systems.

There are no new regulatory commitments contained in the letter.

Please direct any questions concerning this matter to Terry Cribbe at (423) 751-3850.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on the 7 th day of July, 2010.

Respectfully, R. M. Kil

Enclosure:

Tennessee Valley Authority (TVA) Browns Ferry Nuclear Plant (BFN), Unit 3, -

Nine-Month Supplemental (Post-Outage) Response To NRC Generic Letter (GL) 2008-01 cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant

ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)

BROWNS FERRY NUCLEAR PLANT (BFN), UNIT 3, -

NINE-MONTH SUPPLEMENTAL (POST-OUTAGE) RESPONSE TO NRC GENERIC LETTER (GL) 2008-01 This Enclosure provides the TVA Browns Ferry Nuclear Plant (BFN) Unit 3 Nine-Month Supplemental (Post-Outage) Response to Generic Letter (GL) 2008-01 for actions that were deferred until the next refueling outage as requested by NRC letter dated September 25, 2008 (Reference 2).

The following information is provided in this response:

a) A description of the results of evaluations that were performed pursuant to GL 2008-01 on the previously incomplete activities, such as system piping walkdowns, at BFN, Unit 3, (see Section A of this Enclosure),

b) A description of any additional corrective actions determined necessary to assure system operability and compliance with the quality assurance criteria in Sections III, V, Xl, XVI, and XVII of Appendix B to 10 CFR Part 50 and the licensing basis and operating license with respect to the subject systems, including a schedule and a basis for that schedule (see Section B1 of this Enclosure), and c) A summary of any changes or updates to previous corrective actions, including any schedule change and the basis for the change (See Section B2 of this Enclosure).

This supplemental Unit 3 response is similar to the March 2, 2009, Unit 1 response (Reference 3) and the September 21, 2009, Unit 2 response (Reference 7) and, as applicable, addresses the August 24, 2009, NRC request for additional information (Reference 5) and implements the guidance provided in the NRC to Nuclear Energy Institute, dated May 28, 2009 (Reference 4).

The original conclusions documented in the Nine-Month response (Reference 1) with respect to the licensing basis evaluation, testing evaluations, and corrective action evaluations have not changed. This supplement will only discuss the results of design evaluation reviews conducted during the recent refueling outage associated with incomplete activities.

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A. EVALUATION RESULTS

1. Design Basis Documents There is no additional information or changes to report since the TVA BFN Nine-Month Response to NRC GL 2008-01, dated October 11, 2008 (Reference 1).

2. Confirmatory Walkdowns Portions of the Residual Heat Removal (RHR), Core Spray, and High Pressure Coolant Injection (HPCI) Systems not previously accessible were walked down during the Unit 3 Cycle 14 Refueling Outage (U3R14) using the same criteria as the previous walkdowns. The walkdown scope consisted of the RHR Loop I and II injection piping, which is downstream of the injection valves, the RHR Shutdown Cooling suction piping, the Core Spray Loop I and II injection piping, which is downstream of the injection valves, and the HPCI injection piping.

For the RHR Loop l and II injection piping, the RHR Shutdown Cooling suction piping, the Core Spray Loop I and II injection piping, the walkdowns showed an acceptable pipe slope for horizontal sections for the RHR piping and Core Spray piping. Due to the configuration of the HPCI piping (as confirmed by walkdowns), it cannot contain a void that exceeds acceptance criteria and no measurements were required. The acceptance criteria and the basis for acceptance of this condition are described in the NRC GL 2008-01 request for additional information (RAI) response to Question 9, dated September 21, 2009 (Reference 6).

For the RHR Loop I and II injection piping, it was identified that both are elevated above the vent locations used in loop venting procedures, 3-SR-3.5.1. 1(RHR I) and (RHR II), with Loop I containing an inverted U. The Core Spray Loop II injection piping also contained an inverted U. The Core Spray Loop II contains a horizontal run of pipe and then drops down before the Loop II Testable Check Valve, 2-CKV-075-0054, which creates an inverted U. Loop I of Core Spray contains a previously unvented high point in a similar geometric location as Loop II.

During the walkdown, it was found that each Loop of RHR and Core Spray injection piping has an existing vent line at the highpoints. These vent lines were added to the system fill and vent procedures as a result of other unit walkdowns. Both of the RHR lines are vented dynamically when placed in service for Shutdown Cooling.

Based on ALARA considerations, a procedure change request to vent the drywell Core Spray injection piping by flushing has been submitted. Technical Specification (TS) Surveillance Requirement 3.5.1.1 verifies, for each Emergency Core Cooling System (ECCS) injection/spray subsystem, the piping is filled with water from the pump discharge valve to the injection valve.

As stated in our October 11, 2008 response (Reference 1), an analysis of ECCS piping downstream of the injection valves was completed and a determination was made that the existence of air voids in this piping would have no adverse consequences related to accident conditions. Even if small voids did exist, the pressure transient would not be greater than the normal injection pressure. A discussion of this transient and the basis for acceptance of this condition are described in the NRC GL 2008-01 RAI response to Question 10, dated September 21, 2009 (Reference 6).

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No confirmatory ultrasonic test (UT) (nondestructive) examinations were performed on previously inaccessible piping.

3. Vent Valves For the RHR Loop I and II injection piping, the RHR Shutdown Cooling suction piping, the Core Spray Loop I and II injection piping, and the HPCI injection piping, no new vent valve locations were identified and no modifications to existing vent valves were required.

4. Procedures Core Spray System Operating Instruction, 3-01-75, has been revised to address venting of piping downstream of the injection valves. Based on ALARA considerations, a procedure change request to vent the drywell Core Spray piping by flushing (Problem Evaluation Report (PER) 171750) has been submitted. RHR System Operating Instruction, 3-01-74, has been revised to address venting of piping downstream of the injection valves.

B. DESCRIPTION OF NECESSARY ADDITIONAL CORRECTIVE ACTIONS

1. Additional Corrective Actions None.

2. Corrective Action Updates The following corrective actions, described in TVA's October 11, 2008 response, are repeated in Table 1 for clarity and include a status of all actions as of the completion of the U3R14 Outage.

a. Changed Corrective Actions For Table 1, corrective action item 3, Unit 2 procedures have been revised to allow UT in lieu of bonnet venting due to back leakage causing excessive pipe temperature.

b. Additional Completed Corrective Actions Table 1, corrective action item 7, was completed.

c. Additional Planned Corrective Actions No additional corrective actions are required as a result of the outage activities and evaluations.

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C. CONCLUSION TVA has evaluated the previously unevaluated portions of the applicable systems at BFN, Unit 3, that perform the functions described in the GL and has concluded that gas accumulation is maintained less than the amount that challenges operability as defined in the BFN TS and as related to commitments to the applicable General Design Criteria, as stated in the Final Safety Analysis Report.

REFERENCES

1. WVA Nine-Month Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated October 11, 2008

2. Letter from NRC to Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Re: Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," Proposed Alternative Course of Action (TAC Nos. MD7799, MD7800, and MD7801), dated September 25, 2008

3. TVA Browns Ferry Nuclear Plant, Unit 1 - Nine-Month Supplemental (Post-Outage)

Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,"

dated March 2, 2009

4. Letter from NRC to the Nuclear Energy Institute (NEI), "Preliminary Assessment of Responses to Generic Letter 2008-01, 'Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,' and Future Nuclear Regulatory Commission Staff Review Plans," dated May 28, 2009

5. Letter from NRC to Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Re: Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," Request for Additional Information, dated August 24, 2009

6. TVA Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Response to Request for Additional Information Regarding Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (TAC Nos. MD7799, MD7800, and MD7801), dated September 21, 2009

7. TVA Browns Ferry Nuclear Plant, Unit 2 - Nine-Month Supplemental (Post-Outage)

Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,"

dated September 21, 2009 E-4

TABLE 1 Item Description Status as of Status as of Status as of Status as of 10/11/08 03/02/09 (U1R7) 06/22/09 (U2R15) 07/07/10 (U3R14)

1. TVA will evaluate adopting the revised 44teg~ated Improved Within 6 months of Unchanged Unchanged Unchanged Standard Technical Specification (ISTS) NRC approval of the Traveler

2. The design change review checklist is revised to include an Complete Unchanged Unchanged Unchanged explicit item to determine if the design change introduces or increases the potential gas accumulation beyond established acceptance criteria.

3. The procedure for venting the LPCI injection lines is revised Complete For Unit 1, procedures Unchanged For Unit 2, to use the vent valve on the bonnet of the LPCI injection have been revised to procedures have isolation valve. require that UT been revised to examinations be used in allow UT in lieu lieu of bonnet venting, of bonnet venting due to back leakage causing excessive pipe temperature.

4. The ECCS and Decay Heat Removal (DHR) System 11/26/2008 Complete Unchanged Unchanged operating procedures are being revised to require UT inspection or dynamic venting of locations that could contain a significant void should this pipe be drained.

5. The venting procedures for LPCI discharge pipe are revised Complete Unchanged Unchanged Unchanged to include a time requirement on water flow from the vent.

6. The Core Spray Pump flow test procedures are revised to Complete Unchanged Unchanged Unchanged require the monthly vent procedures to be used for verifying the system is full of water prior to testing the pump.

7. Periodic venting T-he-procedures that are used fef to 01MV2099 Prior to this review, it The completion Complete meet~ng SR 3.5.1.1 are being revised to require that-gas 0 was determined that date for this rele.. e .. bo timed-

.an.d.

. results PRc. The

.... r V .vi.ed 09/30/2009 this item (action) was item has pr,,edr**e will a,,, require tha , in the event of an not as intended. changed.

exte~ded-gas release, a report is entered into the Corrections are as Corrective Action Program. shown. The new date supports this change.

8. The ECCS and DHR System operating procedures are 09/25/2009 Complete New Item Complete being revised to address venting of piping downstream of the injection valves.

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