Text

Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans
	ML081780683
Person / Time
Site:	Hatch
Issue date:	06/25/2008
From:	Stinson L; Southern Nuclear Operating Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	NL-08-0903
	Download: ML081780683 (46)
	v • d • e

L.M. Stinson (Mike) Southern Nuclear Vice President Operating Company, Inc.

Fleet Operations Support 40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.5181 Fax 205.992.0341 SOUTHERN COMPANY AIM June 25, 2008 Energy to Serve Your World*

Docket Nos.: 50-321 NL-08-0903 50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Request to Implement an Alternative Source Term Response to Request for Additional Information Regqarding the Turbine Building Ventilation Exhaust System Fans Ladies and Gentlemen:

On August 29, 2006 Southern Nuclear Operating Company (SNC) submitted a request to revise the Edwin I. Hatch Nuclear Plant (HNP) licensing/design basis with a full scope implementation of an alternative source term (AST). By letters dated November 6, 2006, November 27, 2006, January 30, 2007, June 22, 2007, July 16, 2007, August 13, 2007, October 18, 2007, December 11, 2007, January 24, 2008, February 4, 2008, February 25, 2008, February 27, 2008, March 13, 2008, April 1, 2008, and May 5, 2008 SNC has submitted further information to support the NRC review of the HNP AST submittal.

By letter dated May 30, 2008 the NRC requested additional information concerning the turbine building ventilation exhaust systems, which are credited in the AST analysis with purging the area around the main control room beginning 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months following the start of certain HNP design basis accidents. The enclosures to this letter contain the SNC response to the referenced NRC request for additional information (RAI).

Specifically, in response to the referenced RAI and pursuant to 10 CFR 50.90, SNC hereby requests a revision to the HNP Units 1 and 2 Technical Specifications (TS), Appendices A to Operating Licenses DPF-57 and NPF-5, respectively, as justified by implementation of AST per the previously referenced submitted information. The proposed revision would add a TS, with an applicable Limiting Condition for Operation, Required Actions, Completion Times, and Surveillance Requirements, for the turbine building ventilation exhaust system fans on Units 1 and 2, reflecting the crediting of the turbine building purge function as part of the AST assumptions for certain HNP design basis accidents.

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U. S. Nuclear Regulatory Commission NL-08-0903 Page 2 The 10 CFR 50.92 evaluation and the justification for the categorical exclusion from performing an environmental assessment that were included in the August 29, 2006 submittal continue to remain valid and are applicable to the proposed TS revision.

SNC requests approval of the proposed license amendments as part of NRC approval of AST implementation. The proposed changes would be implemented as part of HNP AST implementation by May 31, 2010.

Mr. L. M. Stinson states he is a Vice President of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and to the best of his knowledge and belief, the facts set forth in this letter are true.

This letter contains no NRC commitments. If you have any questions, please advise.

Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY L. M. Stinson Vice President Fleet Operations Support Sworn to and subscribed before me this day of U,A. 2008.

Notary Public My commission expires: _ ___ ,/0 LMS/CLT/daj

Enclosures:

1. Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans

2. Basis for Proposed Change

3. Technical Specifications and Bases Markup Pages

4. Technical Specifications and Bases Clean Typed Pages

U. S. Nuclear Regulatory Commission NL-08-0903 Page 3 cc: Southern Nuclear Operatinq Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, Vice President - Hatch Mr. D. H. Jones, Vice President - Engineering RType: CHA02.004 U. S. Nuclear Re-gulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. J. A. Hickey, Senior Resident Inspector - Hatch State of Georgia Mr. N. Holcomb, Commissioner - Department of Natural Resources

Edwin I. Hatch Nuclear Plant Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans Enclosure 1 Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans

Enclosure 1 Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans NRC QUESTION In a request for additional information dated April 26, 2007, concerning the implementation of an Alternative Source Term application; the U.S. Nuclear Regulatory Commission (NRC) staff asked whether Southern Nuclear Operating Company, Inc. (SNC) considered adding a Limiting Condition for Operation (LCO) to the Technical Specifications (TS) for the turbine building ventilation system (TBVS), including surveillance requirements (SR). SNC's reply dated February 27, 2008, stated that:

"SNC intends to add the TB HVAC exhaust systems to the scope of the HNP Maintenance Rule program, in accordance with 10 CFR 50.65 and to the scope of license renewal, in accordance with 10 CFR 54.37(b)." and "After due consideration, SNC has concluded that the addition to HNP TS of a LCO, including surveillance requirements, to assure "the lowest functional capability or performance levels," as stated in 10 CFR 50.36 titled "Technical Specifications," is not warranted for the new credited function of the TB HVAC exhaust systems. Contrary to the vast majority of safety functions in the TS, the capability to perform the Alternative Source Term credited function of purging the turbine building is demonstrated continuously during Edwin I. Hatch Nuclear Plant operation."

As discussed with SNC staff on May 29, 2008, the NRC staff requests that SNC provide a detailed evaluation of whether the TBVS is equipment required for safe operation of the facility as required by 10 CFR 50.36(d)(2)(ii)(C), Criterion 3, "A structure, system or component that is part of the primary success path and which functions or actuates to mitigate a design-basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier," or 10 CFR 50.36(d)(2)(ii)(D), Criterion 4, "A structure, system, or component which operating experience or probabilistic risk assessment has shown to be significant to public health and safety" and therefore requires a limiting condition for operation.

The NRC staff may pursue, in the future as needed, further details on the addition of the TB HVAC exhaust systems to the scope of the HNP Maintenance Rule program.

SNC RESPONSE In order to ensure compliance with 10 CFR 50.36(d)(2)(ii)(C), SNC proposes to add a turbine building exhaust system fans TS, since the turbine building purge function is credited to mitigate three of the four HNP design basis accidents.

Therefore, in Enclosures 2, 3, and 4 to this letter, SNC provides justification for the addition of a turbine building ventilation exhaust system fans TS on HNP Units 1 and 2 reflecting the crediting of the turbine building purge function as part of the AST assumptions for three of the four HNP design basis accidents.

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Enclosure 1 Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans The referenced Criterion 4 is not applicable since neither operating experience or probabilistic risk assessment to date has shown the turbine building ventilation exhaust system fans to be significant to public health and safety.

Finally, as noted in the referenced SNC letter to the NRC dated February 27, 2008, the inclusion of the turbine building ventilation exhaust systems in the HNP Maintenance Rule program will be complete in sufficient time to support final AST implementation, once NRC approval is obtained.

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Edwin I. Hatch Nuclear Plant Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans Enclosure 2 Basis for Proposed Change

Edwin I. Hatch Nuclear Plant Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans Enclosure 2 Basis for Proposed Change Table of Contents 1.0 Summary Description 2.0 Detailed Description 3.0 Technical Evaluation 4.0 Regulatory Evaluation 4.1 Significant Hazards Consideration 4.2 Applicable Regulatory Requirements/Criteria 4.3 Precedent 4.4 Conclusions 5.0 Environmental Consideration 6.0 References

Enclosure 2 Basis for Proposed Change 1.0 Summary Description This evaluation supports a request to amend Appendix A of Operating Licenses DPF-57 and NPF-5 for Edwin I. Hatch Nuclear Plant (HNP) Unit 1 and Unit 2, respectively.

The proposed change would revise the Technical Specifications (TS) to add a turbine building ventilation (TB HVAC) exhaust system fans TS on HNP Units 1 and 2, reflecting the crediting of the turbine building purge function as part of the Alternative Source Term (AST) assumptions for three of the four HNP design basis accidents (DBAs). This TS change is being proposed in response to an AST related NRC request for additional information (RAI) dated May 30, 2008 (reference Enclosure 1 for the SNC response to the RAI).

SNC requests approval of the proposed change as part of NRC approval of AST implementation. The proposed changes would be implemented as part of HNP AST implementation by May 31, 2010.

2.0 Detailed Description The proposed change will add a new TS Limiting Condition for Operation (LCO) 3.7.9 for the TB HVAC exhaust system fans. To account for potential single failures, LCO 3.7.9 will require one Unit 1 and one Unit 2 TB HVAC exhaust system fan to be operable in modes 1, 2 and 3. The new associated Conditions, Required Actions, Completion Times, and Surveillance Requirements are closely modeled after similar ventilation system TS in the Standard Technical Specifications.

This new TS is being proposed as a result of AST crediting a new function for the TB HVAC exhaust system fans; specifically the turbine building purge function. One of the four available TB HVAC fans is sufficient to purge the area around the control room to reduce the activity available for leakage into the control room following the three applicable DBAs, loss of coolant accident, main steam line break or control rod drop accident. Consequently, the turbine building purge function is credited to mitigate three of the four HNP DBAs and meets Criterion 3 for establishment of a TS LCO per 10 CFR 50.36(d)(2)(ii)(C) (reference Enclosure 1 for the SNC response to the RAI).

3.0 Technical Evaluation The control room, as part of the control building, is housed within the Units 1 and 2 turbine building structure. As part of the revised DBA radiological dose analyses implementing AST, the Units 1 and 2 TB HVAC exhaust system fans are credited to mitigate radiological doses to control room personnel. One of the four TB HVAC exhaust system fans is credited with purging the area around the control room to reduce the activity available for leakage into the control room following a postulated loss of coolant accident, main steam line break, or control rod drop accident.

The TB HVAC system was originally designed to support power generation and was not considered an engineered safety feature (ESF) system. The primary power generation design function of the TB HVAC system, consisting of supply and exhaust systems, is to provide air movement for temperature and airborne radioactivity control. To accomplish E2 - 2

Enclosure 2 Basis for Proposed Change the power generation design function the TB HVAC system runs continuously during normal plant operation.

As part of the implementation of AST, the TB HVAC exhaust system fans (without reliance on the TB HVAC supply system) are credited with performing a ESF design function of mitigating the consequences of the referenced DBAs by purging the activity available for leakage into the control room post-accident. For each unit, air is exhausted from the turbine building by a duct system to the outside environment via the reactor building vent plenum by one of two exhaust fans. The exhaust from the turbine building passes through two 50% capacity filter trains, per unit, but the filtering function is not credited. One of the two 100% capacity exhaust fans per unit runs continuously during normal plant operation. If the operating exhaust fan fails, the standby exhaust fan starts automatically.

To accomplish the AST credited purge function post-accident, one of the four TB HVAC exhaust system fans is sufficient to deliver the credited purge flow. The single fan flow capacity necessary to support the original TB HVAC system power generation design functions bounds the AST credited purge flow. The AST dose analyses assume that the turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the start of the 3 applicable DBAs. This assumption allows time for restarting at least one exhaust fan post-accident following a concurrent loss of offsite power. AST does not take credit for filtration by the TB HVAC exhaust system filter trains.

In support of crediting a single TB HVAC exhaust system fan for purge flow post-accident, the TB HVAC exhaust systems have been enhanced as follows. To assure that no single failure exists that would preclude the operation of one fan, two fans are required (one fan from each unit). The TB HVAC exhaust systems and the motor control center panels utilized for the normal non-Class 1E power source for the TB HVAC exhaust systems have been seismically verified to be able to support the purge function following a Hatch design basis earthquake. Finally, in the unlikely event that the normal power supply for the TB HVAC exhaust fan systems cannot be restored prior to 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months post-accident with a concurrent loss of offsite power, each of the TB HVAC exhaust fans can be powered, one at a time per unit, via manual transfer switches from an essential motor control center (one essential motor control center per unit) that can receive power from an emergency diesel generator.

The technical details associated with the revised DBA radiological dose analyses implementing AST which credit the turbine building purge and the technical details associated with previously listed enhancements to the TB HVAC exhaust systems have been covered in detail as part of the information previously submitted to support NRC review of the HNP AST submittal (see References 1 - 5). The proposed TS change is consistent with the information provided in those references.

4.0 Regulatory Evaluation 4.1 Significant Hazards Consideration The proposed change would revise the TS to add a TB HVAC exhaust system fans TS on HNP Units 1 and 2 reflecting the crediting of the turbine building purge E2 - 3

Enclosure 2 Basis for Proposed Change function as part of the AST assumptions for three of the four HNP DBAs. The crediting of one of the four TB HVAC exhaust system fans to provide turbine building purge flow within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the start of the 3 applicable DBAs is an AST assumption documented in detail in the initial AST submittal dated August 29, 2006. This proposed TS change is consistent with the information provided in the initial submittal and associated further information provided to support the NRC review of the HNP AST submittal (see References 1 - 5). Therefore, the 10 CFR 50.92 evaluation included in the August 29, 2006 submittal Enclosure 3 continues to remain valid.

4.2 Applicable Regulatory Requirements/Criteria AST implementation is governed by 10 CFR 50.67, the guidelines of the Standard Review Plan (SRP) section 15.0.1 revision 0, "Radiological Consequence Analyses Using Alternative Source Terms," and Regulatory Guide 1.183, "Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors," dated July, 2000.

4.3 Precedent The HNP control room has a unique configuration for a boiling water reactor. As part of the control building it is housed within the HNP Units 1 and 2 turbine building structure. The need to credit the turbine building purge function as part of the AST assumptions for three of the four HNP DBAs is necessitated by this unique configuration. One TB HVAC fan purges the area around the control room to reduce the activity available for leakage into the control room following the three applicable DBAs. Consequently the proposed change to revise the TS to add a TB HVAC exhaust system fans TS on HNP Units 1 and 2 is somewhat unique. However, the proposed TS is closely modeled after similar ventilation system TS in the Standard Technical Specifications.

There are numerous precedents for NRC approval of AST implementation in accordance with 10 CFR 50.67. Amendments similar to the HNP AST submittal were approved for Browns Ferry on September 27, 2004 and Vermont Yankee on March 29, 2005. In addition, the HNP application of AST incorporates elements of the Columbia AST submittal approved on November 27, 2006 and the Oyster Creek AST submittal approved April 26, 2007.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

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Enclosure 2 Basis for Proposed Change 5.0 Environmental Consideration The proposed change would revise the TS to add a TB HVAC exhaust system fans TS on HNP Units 1 and 2 reflecting the crediting of the turbine building purge function as part of the AST assumptions for three of the four HNP DBAs. The crediting of one of the four TB HVAC exhaust system fans to provide turbine building purge flow within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the start of the 3 applicable DBAs is an AST assumption documented in detail in the initial AST submittal dated August 29, 2006. This proposed TS change is consistent with the information provided in the initial submittal and associated further information provided to support the NRC review of the HNP AST submittal (see References 1 - 5).

Therefore, pursuant to 10 CFR 51.22(b), the justification for the categorical exclusion from performing an environmental assessment included in the August 29, 2006 submittal continues to remain valid.

6.0 References

1. "Request to Implement an Alternative Source Term," NL-06-1637, August 29, 2006.

2. "Response to Request for Additional Information Regarding the Power Sources for the Turbine Building Ventilation System," NL-07-0894, October 18, 2007.

3. "Response to Request for Additional Information Regarding the Turbine Building Ventilation and Leakage Treatment Piping Seismic Evaluations," NL-07-1949, December 11, 2007.

4. "Response to Request for Additional Information Regarding the Turbine Building Ventilation and Standby Liquid Control Systems," NL-07-1532, February 27, 2008.

5. "Response to Request for Additional Information Regarding the Power Sources for the Turbine Building Ventilation System," NL-08-0351, March 13, 2008.

E2 - 5

Edwin I. Hatch Nuclear Plant Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans Enclosure 3 Technical Specifications and Bases Markup Pages

TABLE OF CONTENTS (continued) 3.6 CONTAINMENT SYSTEMS (continued) 3.6.1.6 Low-Low Set (LLS) Valves .......................................................................... 3.6-15 3.6.1.7 Reactor Building-to-Suppression Chamber Vacuum Breakers ..................... 3.6-17 3.6.1.8 Suppression Chamber-to-Drywell Vacuum Breakers ................................... 3.6-19 3.6.2.1 Suppression Pool Average Temperature ..................................................... 3.6-21 3.6.2.2 Suppression Pool Water Level ..................................................................... 3.6-24 3.6.2.3 Residual Heat Removal (RHR) Suppression Pool Cooling .......................... 3.6-25 3.6.2.4 Residual Heat Removal (RHR) Suppression Pool Spray ............................. 3.6-27 3.6.3.1 Containment Atmosphere Dilution (CAD) System ........................................ 3.6-29 3.6.3.2 Primary Containment Oxygen Concentration ............................................... 3.6-31 3.6.4.1 Secondary Containment .............................................................................. 3.6-32 3.6.4.2 Secondary Containment Isolation Valves (SCIVs) ....................................... 3.6-35 3.6.4.3 Standby Gas Treatment (SGT) System ....................................................... 3.6-38 3.7 PLANT SYSTEMS ...................................................................................... 3.7-1 3.7. 1 Residual Heat Removal Service Water (RHRSW) System .......................... 3.7-1 3.7..2 Plant Service Water (PSW) System and Ultimate Heat Sink (UHS) ............. 3.7-3 3.7..3 Diesel Generator (DG) 1 B Standby Service Water (SSW) System .............. 3.7-6 3.7..4 Main Control Room Environmental Control (MCREC) System ..................... 3.7-8 Add here 3.7..5 Control Room Air Conditioning (AC) System ............................................... 3.7-12 3.7..6 Main C ondenser O ffgas ............................................................................... 3.7-16

.78.7 Main Turbine Bypass System ...................................................................... 3.7-18

.7,.8 Soent Fuel Storaae Pool Water Level ............. ...... . ................... 3.7-19 13.7 .9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans ................... 3.7-201 3.8 ELECTRICAL POWER SYSTEMS .............................................................. 3.8-1 3.8.1 AC Sources - Operating ............................................................................... 3.8-1 3.8.2 AC Sources - Shutdown .............................................................................. 3.8-20 3.8.3 Diesel Fuel Oil and Transfer, Lube Oil, and Starting Air ............................... 3.8-23 3.8.4 DC Sources - Operating .............................................................................. 3.8-26 3.8.5 DC Sources - Shutdown .............................................................................. 3.8-31 3.8.6 Battery Cell Param eters ............................................................................... 3.8-33 3.8.7 Distribution Systems - Operating ................................................................. 3.8-36 3.8.8 Distribution Systems - Shutdown ................................................................. 3.8-39 3.9 REFUELING OPERATIONS ....................................................................... 3.9-1 3.9.1 Refueling Equipm ent Interlocks ................................................................... 3.9-1 3.9.2 Refuel Position One-Rod-Out Interlock ........................................................ 3.9-3 3.9.3 Control Rod Position .................................................................................... 3.9-4 3.9.4 Control Rod Position Indication .................................................................... 3.9-5 3.9.5 Control Rod O PERABILITY - Refueling ....................................................... 3.9-7 (continued)

HATCH UNIT 1 iii Amendment No. M

Turbine Building Ventilation Exhaust System Fans 3.7.9 3.7 PLANT SYSTEMS 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans LCO 3.7.9 One Unit 1 and one Unit 2 TB HVAC exhaust system fan shall be OPERABLE.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One required TB HVAC A.1 Restore required TB 7 days exhaust system fan HVAC exhaust system inoperable, fan to OPERABLE status.

B. Two required TB HVAC B.1 Restore one required 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months exhaust system fans TB HVAC exhaust inoperable, system fan to OPERABLE status.

C. Required Action and C.1 Be in MODE 3. 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months associated Completion Time not met. AND C.2 Be in MODE 4. 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months HATCH UNIT 1 3.7-20 Amendment No.

Turbine Building Ventilation Exhaust System Fans 3.7.9 SURVEILLANCE REQUIREMENTS

NOTE---------------------------------

When a TB HVAC exhaust system fan, with associated filter trains, ductwork and dampers, is placed in an inoperable status for the performance of required Surveillances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

SURVEILLANCE FREQUENCY SR 3.7.9.1 Operate each TB HVAC exhaust system fan 92 days for > 15 minutes.

SR 3.7.9.2 Verify manual transfer capability to alternate 24 months power supply for each TB HVAC exhaust system fan.

HATCH UNIT 1 3.7-21 Amendment No.

Turbine Building Ventilation Exhaust System Fans B 3.7.9 B 3.7 PLANT SYSTEMS B 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans BASES BACKGROUND The control room, as part of the control building, is housed within the Units 1 and 2 turbine building structure. As part of the revised design basis accident (DBA) radiological dose analyses implementing Alternative Source Term (AST), the Units 1 and 2 TB HVAC exhaust system fans are credited to mitigate radiological doses to control room personnel. One of the four TB HVAC exhaust system fans is credited with purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident.

The TB HVAC system was originally designed to support power generation and was not considered an engineered safety feature (ESF) system. The primary power generation design function of the TB HVAC system, consisting of supply and exhaust systems, is to provide air movement for temperature and airborne radioactivity control. To accomplish the power generation design function the TB HVAC system runs continuously during normal plant operation.

As part of the implementation of AST, the TB HVAC exhaust system fans (without reliance on the TB HVAC supply system) are credited with performing an ESF design function of mitigating the consequences of the referenced DBAs by purging the activity available for leakage into the control room post-accident. For each unit, air is exhausted from the turbine building by a duct system to the outside environment via the reactor building vent plenum by one of two exhaust fans. The exhaust from the turbine building passes through two 50% capacity filter trains, per unit, but the filtering function is not credited. One of the two 100%

capacity exhaust fans per unit runs continuously during normal plant operation. If the operating exhaust fan fails, the standby exhaust fan starts automatically.

To accomplish the AST credited purge function post-accident, one of the four TB HVAC exhaust system fans is sufficient to deliver the credited purge flow. The single fan flow capacity necessary to support the original TB HVAC system power generation design functions bounds the AST credited purge flow. The AST dose analyses assume that the turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the start of the 3 applicable DBAs. This assumption allows time for restarting at least one exhaust fan post-accident following a concurrent loss of offsite power.

AST does not take credit for filtration by the TB HVAC exhaust system filter trains.

(continued)

HATCH UNIT 1 B 3.7-41

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES BACKGROUND In support of crediting a single TB HVAC exhaust system fan for purge (continued) flow post-accident, the TB HVAC exhaust systems have been enhanced as follows. To assure that no single failure exists that would preclude the operation of one fan, two fans are required (one fan from each unit).

The TB HVAC exhaust systems and the motor control center panels utilized for the normal non-Class 1 E power source for the TB HVAC exhaust systems have been seismically verified to be able to support the purge function following a Hatch design basis earthquake. Finally, in the unlikely event that the normal power supply for the TB HVAC exhaust fan systems cannot be restored prior to 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months post-accident with a concurrent loss of offsite power, each of the TB HVAC exhaust fans can be powered, one at a time per unit, via manual transfer switches from an essential motor control center (one essential motor control center per unit) that can receive power from an emergency diesel generator.

APPLICABLE The TB HVAC exhaust system fans support maintaining the SAFETY ANALYSES habitability of the control room by purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident. The TB HVAC exhaust systems are described in Unit 1 FSAR section 10.9.3.4 (Ref. 1) and Unit 2 FSAR section 9.4.4 (Ref. 2). The dose mitigation function of the TB HVAC exhaust systems, specifically crediting purge flow starting 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months after the applicable DBAs, is documented in the Unit 1 and 2 safety analysis in Unit 2 FSAR chapter 15 (Ref. 3). The radiological doses to control room personnel as a result of the various DBAs are also documented in Unit 2 FSAR chapter 15 (Ref. 3). No single failure will cause the loss of the credited turbine building purge function.

The TB HVAC exhaust system fans satisfy Criterion 3 of the NRC Policy Statement.

LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan must be OPERABLE to ensure that at least one is available, assuming a single failure disables the other system. Inability to implement the turbine building purge function could result in exceeding a dose of 5 rem to the control room operators in the event of a loss of coolant accident, main steam line break, or control rod drop accident.

(continued)

HATCH UNIT 1 B 3.7-42

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC (continued) exhaust system fan are considered OPERABLE when the individual components necessary to control operator exposure are OPERABLE in both systems. Each unit's required TB HVAC exhaust system fan is considered OPERABLE when its associated:

a. One of the two available exhaust fans is OPERABLE,

b. Prefilters, carbon adsorbers, and high efficiency particulate air (HEPA) filters are not excessively restricting flow,

c. Associated ductwork and dampers are OPERABLE, and exhaust flow can be maintained, and

d. Alternate power supply (from essential motor control centers) and associated manual transfer switches are OPERABLE.

OPERABILITY of one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan entails satisfying the requirements listed above for each unit's TB HVAC exhaust system fan. For both units' TB HVAC exhaust system fans to be OPERABLE, the two required exhaust fans must be independently powered.

APPLICABILITY In MODES 1, 2, and 3, one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan must be OPERABLE to control operator exposure during and following a DBA which could lead to a fission product release in the turbine building.

In MODES 4 and 5, the probability and consequences of a DBA with a fission product release in the turbine building are reduced because of the pressure and temperature limitations in these MODES. Therefore, maintaining one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan OPERABLE is not required in MODE 4 or 5.

ACTIONS A.1 With one unit's required TB HVAC exhaust system fan inoperable, an inoperable TB HVAC exhaust system fan must be restored to OPERABLE status within 7 days. With the unit in this condition, the remaining OPERABLE TB HVAC exhaust system fan is adequate to perform the turbine building purge function. However, the overall reliability is reduced because a single failure related to the OPERABLE (continued)

HATCH UNIT 1 B 3.7-43

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES ACTIONS A.1 (continued)

TB HVAC exhaust system fan could result in reduced turbine building purge capability. The 7 day Completion Time is based on the low probability of a DBA occurring during this time period, and that the remaining OPERABLE TB HVAC exhaust system fan can provide the required capabilities.

B.1 If two required TB HVAC exhaust system fans are inoperable in MODE 1,2, or 3, the TB HVAC exhaust systems fans cannot perform their turbine building purge function. Actions must be taken to restore one required TB HVAC exhaust system fan to OPERABLE status within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is reasonable based on the low probability of a DBA occurring during this time period, the purge function is maintained via natural wind-driven ventilation in the turbine building, and the low probability that sufficient activity would be released into the turbine building following a DBA to significantly impact control room habitability via inleakage.

C.1 and C.2 In MODE 1, 2, or 3, ifthe inoperable required TB HVAC exhaust system fans cannot be restored to OPERABLE status within the associated Completion Time, the unit must be placed in a MODE that minimizes risk. To achieve this status, the unit must be placed in at least MODE 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in MODE 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

SURVEILLANCE The Surveillances are modified by a Note to indicate that when a REQUIREMENTS required TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, is placed in an inoperable status for performance of required Surveilances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months provided one of the other TB HVAC exhaust system fans, with associated filter trains, ductwork, and dampers, can perform the turbine building purge function post-accident. Upon completion of the Surveillance, or expiration of the 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months allowance, the TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, must be returned to OPERABLE status or the applicable Condition entered and Required Actions taken.

This Note is based on the AST dose analyses assumption that the (continued)

HATCH UNIT 1 B 3.7-44

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES SURVEILLANCE turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the REQUIREMENTS start of the 3 applicable DBAs. Consequently this testing allowance (continued) does not significantly impact the ability to manually initiate turbine building purge flow within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months .

SR 3.7.9.1 This SR verifies that each of the two available TB HVAC exhaust system fans on both Unit 1 and Unit 2, total of four TB HVAC exhaust system fans, starts on demand and continues to operate. One of the two 100% capacity exhaust fans per unit runs continuously during normal plant operation. One of the exhaust fans per unit is in standby.

Standby systems should be checked periodically to ensure that they start and function properly. Operating the standby TB HVAC exhaust system fans on both Unit 1 and Unit 2 for Ž: 15 minutes demonstrates that each exhaust fan can perform the turbine building purge function by exhausting turbine building air to the reactor building vent plenum and that any blockage, fan or motor failure can be detected for corrective action.

As the environmental and normal operating conditions of this system are not severe, testing each subsystem once every 92 days provides an adequate check on this system. Furthermore, the 92 day Frequency is based on the known reliability of the equipment (one fan per unit running continuously during normal operation) and the exhaust fan redundancy available.

SR 3.7.9.2 This SR verifies manual transfer capability to t he alternate power supply for each TB HVAC exhaust system fan. Since during normal plant operation each continuously running exhaust fan per unit is using its normal power supply, the standby or alternate power supply from an essential motor control center (one essential motor control center per unit) should be checked periodically to ensure the essential motor control center can provide power to each TB HVAC exhaust system fan via a manual transfer switch. Each of the four TB HVAC exhaust system fans, two per unit, should be connected to the alternate power supply one at a time via a manual transfer switch. This Surveillance can be performed with the reactor at power. The 24 month Frequency is consistent with other similar ventilation system SRs.

REFERENCES 1. Unit 1 FSAR, Section 10.9.3.4.

2. Unit 2 FSAR section 9.4.4

3. Unit 2 FSAR, Chapter 15.

HATCH UNIT 1 B374 B 3.7-45

TABLE OF CONTENTS (continued) 3.6 CONTAINMENT SYSTEMS ........................................................................ 3.6-1 3.6.1.1 Primary Containment ................................................................................... 3.6-1 3.6.1.2 Primary Containment Air Lock ..................................................................... 3.6-3 3.6.1.3 Primary Containment Isolation Valves (PCIVs) ............................................ 3.6-7 3.6.1.4 Drywell Pressure ......................................................................................... 3.6-13 3.6.1.5 Drywell Air Temperature .............................................................................. 3.6-14 3.6.1.6 Low-Low Set (LLS) Valves .......................................................................... 3.6-15 3.6.1.7 Reactor Building-to-Suppression Chamber Vacuum Breakers ..................... 3.6-17 3.6.1.8 Suppression Chamber-to-Drywell Vacuum Breakers ................................... 3.6-19 3.6.2.1 Suppression Pool Average Temperature ..................................................... 3.6-21 3.6.2.2 Suppression Pool W ater Level ..................................................................... 3.6-24 3.6.2.3 Residual Heat Removal (RHR) Suppression Pool Cooling .......................... 3.6-25 3.6.2.4 Residual Heat Removal (RHR) Suppression Pool Spray ............................. 3.6-27 3.6.3.1 (D e lete d ) ..................................................................................................... 3 .6 -2 9 3.6.3.2 Primary Containment Oxygen Concentration ............................................... 3.6-31 3.6.3.3 Drywell Cooling System Fans ...................................................................... 3.6-32 3.6.4.1 Secondary Containment .............................................................................. 3.6-33 3.6.4.2 Secondary Containment Isolation Valves (SCIVs) ....................................... 3.6-36 3.6.4.3 Standby Gas Treatment (SGT) System ....................................................... 3.6-39 3.7 PLANT SYSTEMS ...................................................................................... 3.7-1 3.7.1 Residual Heat Removal Service Water (RHRSW) System .......................... 3.7-1 3.7.2 Plant Service Water (PSW) System and Ultimate Heat Sink (UHS) ...................................................................... 3.7-3 3.7.3 Diesel Generator (DG) 1 B Standby Service Water (SSW)

S yste m .................................................................................................. 3 .7 -6 3.7.4 Main Control Room Environmental Control (MCREC) System ..................... 3.7-8

.7.5 Control Room Air Conditioning (AC) System ............................................... 3.7-12 I Add here

.7.6 Main Condenser Offgas ............................................................................... 3.7-16

.7.7 Main Turbine Bypass System ...................................................................... 3.7-18

.7.8 Spent Fuel Storage Pool Water Level .......................................................... 3.7-19 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans .................. 3.7-20 3.8 ELECTRICAL POW ER SYSTEMS .............................................................. 3.8-1 3.8.1 AC Sources - Operating ............................................................................... 3.8-1 3.8.2 AC Sources - Shutdown .............................................................................. 3.8-20 3.8.3 Diesel Fuel Oil and Transfer, Lube Oil, and Starting Air ...................................................................................... 3.8-23 3.8.4 DC Sources - Operating .............................................................................. 3.8-26 3.8.5 DC Sources - Shutdown .............................................................................. 3.8-31 (continued)

HATCH UNIT 2 iii Amendment No. f]

Turbine Building Ventilation Exhaust System Fans 3.7.9 3.7 PLANT SYSTEMS 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans LCO 3.7.9 One Unit 1 and one Unit 2 TB HVAC exhaust system fan shall be OPERABLE.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One required TB HVAC A.1 Restore required TB 7 days exhaust system fan HVAC exhaust system inoperable, fan to OPERABLE status.

B. Two required TB HVAC B.1 Restore one required 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months exhaust system fans TB HVAC exhaust inoperable, system fan to OPERABLE status.

C. Required Action and C.1 Be in MODE 3. 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months associated Completion Time not met. AND C.2 Be in MODE 4. 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months HATCH UNIT 2 3.7-20 Amendment No.

Turbine Building Ventilation Exhaust System Fans 3.7.9 SURVEILLANCE REQUIREMENTS

NOTE --------------------------------------------------------------

When a TB HVAC exhaust system fan, with associated filter trains, ductwork and dampers, is placed in an inoperable status for the performance of required Surveillances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

SURVEILLANCE FREQUENCY SR 3.7.9.1 Operate each TB HVAC exhaust system fan 92 days for > 15 minutes.

SR 3.7.9.2 Verify manual transfer capability to alternate 24 months power supply for each TB HVAC exhaust system fan.

HATCH UNIT 2 3.7-21 Amendment No.

Turbine Building Ventilation Exhaust System Fans B 3.7.9 B 3.7 PLANT SYSTEMS B 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans BASES BACKGROUND The control room, as part of the control building, is housed within the Units 1 and 2 turbine building structure. As part of the revised design basis accident (DBA) radiological dose analyses implementing Alternative Source Term (AST), the Units 1 and 2 TB HVAC exhaust system fans are credited to mitigate radiological doses to control room personnel. One of the four TB HVAC exhaust system fans is credited with purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident.

The TB HVAC system was originally designed to support power generation and was not considered an engineered safety feature (ESF) system. The primary power generation design function of the TB HVAC system, consisting of supply and exhaust systems, is to provide air movement for temperature and airborne radioactivity control. To accomplish the power generation design function the TB HVAC system runs continuously during normal plant operation.

As part of the implementation of AST, the TB HVAC exhaust system fans (without reliance on the TB HVAC supply system) are credited with performing an ESF design function of mitigating the consequences of the referenced DBAs by purging the activity available for leakage into the control room post-accident. For each unit, air is exhausted from the turbine building by a duct system to the outside environment via the reactor building vent plenum by one of two exhaust fans. The exhaust from the turbine building passes through two 50% capacity filter trains, per unit, but the filtering function is not credited. One of the two 100%

capacity exhaust fans per unit runs continuously during normal plant operation. If the operating exhaust fan fails, the standby exhaust fan starts automatically.

To accomplish the AST credited purge function post-accident, one of the four TB HVAC exhaust system fans is sufficient to deliver the credited purge flow. The single fan flow capacity necessary to support the original TB HVAC system power generation design functions bounds the AST credited purge flow. The AST dose analyses assume that the turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the start of the 3 applicable DBAs. This assumption allows time for restarting at least one exhaust fan post-accident following a concurrent loss of offsite power.

AST does not take credit for filtration by the TB HVAC exhaust system filter trains.

(continued)

HATCH UNIT 2 B 3.7-41

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES BACKGROUND In support of crediting a single TB HVAC exhaust system fan for purge (continued) flow post-accident, the TB HVAC exhaust systems have been enhanced as follows. To assure that no single failure exists that would preclude the operation of one fan, two fans are required (one fan from each unit).

The TB HVAC exhaust systems and the motor control center panels utilized for the normal non-Class 1 E power source for the TB HVAC exhaust systems have been seismically verified to be able to support the purge function following a Hatch design basis earthquake. Finally, in the unlikely event that the normal power supply for the TB HVAC exhaust fan systems cannot be restored prior to 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months post-accident with a concurrent loss of offsite power, each of the TB HVAC exhaust fans can be powered, one at a time per unit, via manual transfer switches from an essential motor control center (one essential motor control center per unit) that can receive power from an emergency diesel generator.

APPLICABLE The TB HVAC exhaust system fans support maintaining the SAFETY ANALYSES habitability of the control room by purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident. The TB HVAC exhaust systems are described in Unit 1 FSAR section 10.9.3.4 (Ref. 1) and Unit 2 FSAR section 9.4.4 (Ref. 2). The dose mitigation function of the TB HVAC exhaust systems, specifically crediting purge flow starting 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months after the applicable DBAs, is documented in the Unit 1 and 2 safety analysis in Unit 2 FSAR chapter 15 (Ref. 3). The radiological doses to control room personnel as a result of the various DBAs are also documented in Unit 2 FSAR chapter 15 (Ref. 3). No single failure will cause the loss of the credited turbine building purge function.

The TB HVAC exhaust system fans satisfy Criterion 3 of the NRC Policy Statement.

LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan must be OPERABLE to ensure that at least one is available, assuming a single failure disables the other system. Inability to implement the turbine building purge function could result in exceeding a dose of 5 rem to the control room operators in the event of a loss of coolant accident, main steam line break, or control rod drop accident.

(continued)

HATCH UNIT 2 B 3.7-42

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC (continued) exhaust system fan are considered OPERABLE when the individual components necessary to control operator exposure are OPERABLE in both systems. Each unit's required TB HVAC exhaust system fan is considered OPERABLE when its associated:

a. One of the two available exhaust fans is OPERABLE,

b. Prefilters, carbon adsorbers, and high efficiency particulate air (HEPA) filters are not excessively restricting flow,

c. Associated ductwork and dampers are OPERABLE, and exhaust flow can be maintained, and

d. Alternate power supply (from essential motor control centers) and associated manual transfer switches are OPERABLE.

OPERABILITY of one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan entails satisfying the requirements listed above for each unit's TB HVAC exhaust system fan. For both units' TB HVAC exhaust system fans to be OPERABLE, the two required exhaust fans must be independently powered.

APPLICABILITY In MODES 1, 2, and 3, one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan must be OPERABLE to control operator exposure during and following a DBA which could lead to a fission product release in the turbine building.

In MODES 4 and 5, the probability and consequences of a DBA with a fission product release in the turbine building are reduced because of the pressure and temperature limitations in these MODES. Therefore, maintaining one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan OPERABLE is not required in MODE 4 or 5.

ACTIONS A.1 With one unit's required TB HVAC exhaust system fan inoperable, an inoperable TB HVAC exhaust system fan must be restored to OPERABLE status within 7 days. With the unit in this condition, the remaining OPERABLE TB HVAC exhaust system fan is adequate to perform the turbine building purge function. However, the overall reliability is reduced because a single failure related to the OPERABLE (continued)

HATCH UNIT 2 B 3.7-43

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES ACTIONS A.1 (continued)

TB HVAC exhaust system fan could result in reduced turbine building purge capability. The 7 day Completion Time is based on the low probability of a DBA occurring during this time period, and that the remaining OPERABLE TB HVAC exhaust system fan can provide the required capabilities.

B.1 If two required TB HVAC exhaust system fans are inoperable in MODE 1, 2, or 3, the TB HVAC exhaust systems fans cannot perform their turbine building purge function. Actions must be taken to restore one required TB HVAC exhaust system fan to OPERABLE status within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is reasonable based on the low probability of a DBA occurring during this time period, the purge function is maintained via natural wind-driven ventilation in the turbine building, and the low probability that sufficient activity would be released into the turbine building following a DBA to significantly impact control room habitability via inleakage.

C.1 and C.2 In MODE 1, 2, or 3, if the inoperable required TB HVAC exhaust system fans cannot be restored to OPERABLE status within the associated Completion Time, the unit must be placed in a MODE that minimizes risk. To achieve this status, the unit must be placed in at least MODE 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in MODE 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

SURVEILLANCE The Surveillances are modified by a Note to indicate that when a REQUIREMENTS required TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, is placed in an inoperable status for performance of required Surveilances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months provided one of the other TB HVAC exhaust system fans, with associated filter trains, ductwork, and dampers, can perform the turbine building purge function post-accident. Upon completion of the Surveillance, or expiration of the 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months allowance, the TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, must be returned to OPERABLE status or the applicable Condition entered and Required Actions taken.

This Note is based on the AST dose analyses assumption that the (continued)

HATCH UNIT 2 B 3.7-44

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES SURVEILLANCE turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the REQUIREMENTS start of the 3 applicable DBAs. Consequently this testing allowance (continued) does not significantly impact the ability to manually initiate turbine building purge flow within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months .

SR 3.7.9.1 This SR verifies that each of the two available TB HVAC exhaust system fans on both Unit 1 and Unit 2, total of four TB HVAC exhaust system fans, starts on demand and continues to operate. One of the two 100% capacity exhaust fans per unit runs continuously during normal plant operation. One of the exhaust fans per unit is in standby.

Standby systems should be checked periodically to ensure that they start and function properly. Operating the standby TB HVAC exhaust system fans on both Unit 1 and Unit 2 for > 15 minutes demonstrates that each exhaust fan can perform the turbine building purge function by exhausting turbine building air to the reactor building vent plenum and that any blockage, fan or motor failure can be detected for corrective action.

As the environmental and normal operating conditions of this system are not severe, testing each subsystem once every 92 days provides an adequate check on this system. Furthermore, the 92 day Frequency is based on the known reliability of the equipment (one fan per unit running continuously during normal operation) and the exhaust fan redundancy available.

SR 3.7.9.2 This SR verifies manual transfer capability to the alternate power supply for each TB HVAC exhaust system fan. Since during normal plant operation each continuously running exhaust fan per unit is using its normal power supply, the standby or alternate power supply from an essential motor control center (one essential motor control center per unit) should be checked periodically to ensure the essential motor control center can provide power to each TB HVAC exhaust system fan via a manual transfer switch. Each of the four TB HVAC exhaust system fans, two per unit, should be connected to the alternate power supply one at a time via a manual transfer switch. This Surveillance can be performed with the reactor at power. The 24 month Frequency is consistent with other similar ventilation system SRs.

REFERENCES 1. Unit 1 FSAR, Section 10.9.3.4.

2. Unit 2 FSAR section 9.4.4

3. Unit 2 FSAR, Chapter 15.

HATCH UNIT 2 B 3.7-45

Edwin I. Hatch Nuclear Plant Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans Enclosure 4 Technical Specifications and Bases Clean Typed Pages

TABLE OF CONTENTS (continued) 3.6 CONTAINMENT SYSTEMS (continued) 3.6.1.6 Low-Low Set (LLS) Valves .......................................................................... 3.6-15 3.6.1.7 Reactor Building-to-Suppression Chamber Vacuum Breakers .......... 3.6-17 3.6.1.8 Suppression Chamber-to-Drywell Vacuum Breakers .................................. 3.6-19 3.6.2.1 Suppression Pool Average Temperature ............................................ 3.6-21 3.6.2.2 Suppression Pool W ater Level .................................................................. 3.6-24 3.6.2.3 Residual Heat Removal (RHR) Suppression Pool Cooling ......................... 3.6-25 3.6.2.4 Residual Heat Removal (RHR) Suppression Pool Spray .............. 3.6-27 3.6.3.1 Containment Atmosphere Dilution (CAD) System ....................................... 3.6-29 3.6.3.2 Primary Containment Oxygen Concentration .............................................. 3.6-31 3.6.4.1 Secondary Containm ent ....................................... ............................... 3.6-32 3.6.4.2 Secondary Containment Isolation Valves (SCIVs) ...................................... 3.6-35 3.6.4.3 Standby Gas Treatment (SGT) System ...................................................... 3.6-38 3.7 PLA NT SY ST EM S ......... ;........................................................................... 3.7-1 3.7.1 Residual Heat Removal Service Water (RHRSW) System .......................... 3.7-1 3.7.2 Plant Service Water (PSW) System and Ultimate Heat Sink (UHS) ........... 3.7-3 3.7.3 Diesel Generator (DG) 1 B Standby Service Water (SSW) System ............. 3.7-6 3.7.4 Main Control Room Environmental Control (MCREC) System .......... 3.7-8 3.7.5 Control Room Air Conditioning (AC) System ............................................... 3.7-12 3.7.6 Main Condenser O ffgas .............................................................................. 3.7-16 3.7.7 Main Turbine Bypass System .......... ..................... 3.7-18 3.7.8 Spent Fuel Storage Pool Water Level ........................... 3.7-19 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans ......... 3.7-20 3.8 ELECTRICAL POW ER SYSTEMS ............................................................. 3.8-1 3.8.1 AC Sources - Operating .................................................. 3.8-1 3.8.2 AC Sources - Shutdow n ........................................................ .................... 3.8-20 3.8.3 Diesel Fuel Oil and Transfer, Lube Oil, and Starting Air.............. 3.8-23 3.8.4 DC Sources - O perating .............................................................................. 3.8-26 3.8.5 DC Sources - Shutdow n ............................................................................. 3.8-31 3.8.6 Battery Cell Parameters .................................................. 3.8-33 3.8.7 Distribution Systems - Operating ....................................... 3.8-36 3.8.8 Distribution Systems - Shutdown .............................. 3.8-39 3.9 REFUELING OPERATIONS ................................. 3.9-1 3.9.1 Refueling Equipment Interlocks ............................... 3.9-1 3.9.2 Refuel Position One-Rod-Out Interlock .......................... 3.9-3 3.9.3 Control Rod Position ....................................... 3.9-4 3.9.4 Control Rod Position Indication ............................... 3.9-5 3.9.5 Control Rod OPERABILITY - Refueling .......................... 3.9-7 (continued)

HATCH UNIT 1 iii Amendment No.

Turbine Building Ventilation Exhaust System Fans 3.7.9 3.7 PLANT SYSTEMS 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans LCO 3.7.9 One Unit 1 and one Unit 2 TB HVAC exhaust system fan shall be OPERABLE.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One required TB HVAC A.1 Restore required TB 7 days exhaust system fan HVAC exhaust system inoperable, fan to OPERABLE status.

B. Two required TB HVAC B.1 Restore one required 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months exhaust system fans TB HVAC exhaust inoperable. system fan to OPERABLE status.

C. Required Action and C.1 Be in MODE 3. 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months associated Completion Time not met. AND C.2 Be in MODE 4. 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months 3.7-20 HATCH UNIT 1 Amendment No.

Turbine Building Ventilation Exhaust System Fans 3.7.9 SURVEILLANCE REQUIREMENTS

NOTE----.......--------- ---------------------

When a TB HVAC exhaust system fan, with associated filter trains, ductwork and dampers, is placed in an inoperable status for the performance of required Surveillances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

SURVEILLANCE FREQUENCY SR 3.7.9.1 Operate each TB HVAC exhaust system fan 92 days for > 15 minutes.

SR 3.7.9.2 Verify manual transfer capability to alternate 24 months power supply for each TB HVAC exhaust system fan.

HATCH UNIT 1 3.7-21 Amendment No.

Turbine Building Ventilation Exhaust System Fans B 3.7.9 B 3.7 PLANT SYSTEMS B 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans BASES BACKGROUND The control room, as part of the control building, is housed within the Units 1 and 2 turbine building structure. As part of the revised design basis accident (DBA) radiological dose analyses implementing Alternative Source Term (AST), the Units 1 and 2 TB HVAC exhaust system fans are credited to mitigate radiological doses to control room personnel. One of the four TB HVAC exhaust system fans is credited with purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident.

The TB HVAC system was originally designed to support power generation and was not considered an engineered safety feature (ESF) system. The primary power generation design function of the TB HVAC system, consisting of supply and exhaust systems, is to provide air movement for temperature and airborne radioactivity control. To accomplish the power generation design function the TB HVAC system runs continuously during normal plant operation.

As part of the implementation of AST, the TB HVAC exhaust system fans (without reliance on the TB HVAC supply system) are credited with performing an ESF design function of mitigating the consequences of the referenced DBAs by purging the activity available for leakage into the control room post-accident. For each unit, air is exhausted from the turbine building by a duct system to the outside environment via the reactor building vent plenum by one of two exhaust fans. The exhaust from the turbine building passes through two 50% capacity filter trains, per unit, but the filtering function is not credited. One of the two 100%

capacity exhaust fans per unit runs continuously during normal plant operation. If the operating exhaust fan fails, the standby exhaust fan starts automatically.

To accomplish the AST credited purge function post-accident, one of the four TB HVAC exhaust system fans is sufficient to deliver the credited purge flow. The single fan flow capacity necessary to support the original TB HVAC system power generation design functions bounds the AST credited purge flow. The AST dose analyses assume that the turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the start of the 3 applicable DBAs. This assumption allows time for restarting at least one exhaust fan post-accident following a concurrent loss of offsite power.

AST does not take credit for filtration by the TB HVAC exhaust system filter trains.

(continued)

HATCH UNIT 1 B 3.7-41

Turbine Building Ventilation -Exhaust System Fans B 3.7.9 BASES BACKGROUND In support of crediting a single TB HVAC exhaust system fan for purge (continued) flow post-accident, the TB HVAC exhaust systems have been enhanced as follows. To assure that no single failure exists that would preclude the operation of one fan, two fans are required (one fan from each unit).

The TB HVAC exhaust systems and the motor control center panels utilized for the normal non-Class 1E power source for the TB HVAC exhaust systems have been seismically verified to be able to support the purge function following a Hatch design basis earthquake. Finally, in the unlikely event that the normal power supply for the TB HVAC exhaust fan systems cannot be restored prior to 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months post-accident with a concurrent loss of offsite power, each of the TB HVAC exhaust fans can be powered, one at a time per unit, via manual transfer switches from an essential motor control center (one essential motor control center per unit) that can receive power from an emergency diesel generator.

APPLICABLE The TB HVAC exhaust system fans support maintaining the SAFETY ANALYSES habitability of the control room by purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident. The.TB HVAC exhaust systems are described in Unit 1 FSAR section 10.9.3.4 (Ref. 1) and Unit 2 FSAR section 9.4.4

.(Ref. 2). The'dose mitigation function of the TB HVAC exhaust systems, specifically crediting purge flow starting 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months after the applicable DBAs, is documented in the Unit 1 and 2 safety analysis in Unit 2 FSAR chapter 15 (Ref. 3). The radiological doses to control room personnel as a result of the various DBAs are also documented in Unit 2 FSAR chapter 15 (Ref. 3). No single failure will cause the loss of the credited turbine building purge function.

The TB HVAC exhaust system fans satisfy Criterion 3 of the NRC Policy Statement.

LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan-must-be OPERABLE to ensure that at least one is available, assuming a single failure disables the other system. Inability to implement the turbine building purge function could result in exceeding a dose of 5 rem to the control room operators in the event of a loss of coolant accident, main steam line break, or control rod drop accident.

(continued)

HATCH UNIT 1 B 3.7-4P

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC (continued) exhaust system fan are considered OPERABLE when the individual components necessary to control operator exposure are OPERABLE in both systems. Each unit's required TB HVAC exhaust system fan is considered OPERABLE when its associated:

a. One of the two available exhaust fans is OPERABLE,

b. Prefilters, carbon adsorbers, and high efficiency particulate air (HEPA) filters are not excessively restricting flow,

c. Associated ductwork and dampers are OPERABLE, and exhaust flow can be maintained, and

d. Alternate power supply (from essential motor control centers) and associated manual transfer switches are OPERABLE.

OPERABILITY of one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan entails satisfying the requirements listed above for each unit's TB HVAC exhaust system fan. For both-units' TB HVAC exhaust system fans to be OPERABLE, the two required exhaust fans must be independently powered.

APPLICABILITY In MODES 1, 2, and 3, one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan must be OPERABLE to control operator exposure during and following a DBA which could lead to a fission product release in the turbine building.

In MODES 4 and 5, the probability and consequences of a DBA with a fission product release in the turbine building are reduced because of the pressure and temperature limitations in these MODES. Therefore, maintaining one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan OPERABLE is not required in MODE 4 or 5.

ACTIONS A.1 With one unit's required TB HVAC exhaust system fan inoperable, an inoperable. TB HVAC exhaust system fan must be restored to OPERABLE status within 7 days. With the unit in this condition, the remaining OPERABLE TB HVAC exhaust system fan is adequate to perform the turbine building purge function. However, the overall reliability is reduced because a single failure related to the OPERABLE (continued)

HATCH UNIT 1 B 3.7-43

Turbine Building Ventilation Exhaust System Fans, B 3.7.9 BASES ACTIONS A.1 (continued)

TB HVAC exhaust system fan could result in reduced turbine building purge capability. The 7 day Completion Time is based on the low probability of a DBA occurring during this time period, and that the remaining OPERABLE TB HVAC exhaust system fan can provide the required capabilities.

B. 1 If two required TB HVAC exhaust system fans are inoperable in MODE 1, 2, or 3, the TB HVAC exhaust systems fans cannot perform their turbine building purge function. Actions must be taken to restore one required TB HVAC exhaust system fan to OPERABLE status within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is reasonable based on the low probability of a DBA occurring during this time period, the purge function is maintained via natural wind-driven ventilation in the turbine building, and the low probability that sufficient activity would be released into the turbine building following a DBA to significantly impact control room habitability via inleakage.

C.1 and C.2 In MODE 1, 2, or 3, if the inoperable required TB HVAC exhaust system fans cannot be restored to OPERABLE status within the associated Completion Time, the unit must be placed in a MODE that minimizes risk. To achieve this status, the unit must be placed in at least MODE 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in MODE 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

SURVEILLANCE The Surveillances are modified by a Note to indicate that when a REQUIREMENTS required TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, is placed in an inoperable status for performance of required Surveilances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months provided one of the other TB HVAC exhaust system fans, with associated filter trains, ductwork, and dampers, can perform the turbine building purge function post-accident. Upon completion of the Surveillance, or expiration of the 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months allowance, the TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, must be returned to OPERABLE status or the applicable Condition entered and Required Actions taken.

This Note is based on the AST dose analyses assumption that the (continued)

HATCH UNIT 1 B 3.7-44

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES SURVEILLANCE turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the REQUIREMENTS start of the 3 applicable DBAs. Consequently this testing allowance (continued) does not significantly impact the ability to manually initiate turbine building purge flow within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months .

SR 3.7.9.1 This SR verifies that each of the two available TB HVAC exhaust system fans on both Unit 1 and Unit 2, total of four TB HVAC exhaust system fans, starts on demand and continues to operate. Oneof the two 100% capacity exhaust fans per unit runs continuously during normal plant operation. One of the exhaust fans per unit is in standby.

Standby systems should be checked periodically to ensure that they start and function properly. Operating the standby TB HVAC exhaust system fans on both Unit 1 and Unit 2 for > 15 minutes demonstrates that each exhaust fan can perform the turbine building purge function by exhausting turbine building air to the reactor building vent plenum and that any blockage, fan or motor failure can be detected for corrective, action.

As the environmental and normal operating conditions of this system are not severe, testing each subsystem once every 92 days provides an adequate check on this system. Furthermore, the 92 day Frequency is based on the known reliability of the equipment (one fan per unit running continuously during normal operation) and the exhaust fan redundancy available.

SR 3.7.9.2 This SR verifies manual transfer capability to the alternate power supply for each TB HVAC exhaust system fan. Since during normal plant operation each continuously running exhaust fan per unit is using its normal power supply, the standby or alternate power supply from an essential motor control center (one essential motor control center per unit) should be checked periodically to ensure the essential motor control center can provide power to each TB HVAC exhaust system fan via a manual transfer switch. Each of the four TB HVAC exhaust system fans, two per unit, should be connected to the alternate power supply one at a time via a manual transfer switch. This Surveillance can be performed with the reactor at power. The 24 month Frequency is consistent with other similar ventilation system SRs.

REFERENCES 1. Unit 1 FSAR, Section 10.9.3.4.

2. Unit 2 FSAR section 9.4.4

3. Unit 2 FSAR, Chapter 15.

HATCH UNIT 1 B 3.7-45

TABLE OF CONTENTS (continued) 3.6 CO NTAINM ENT SYSTEM S ....................................................................... 3.6-1 3.6.1.1 Prim ary C ontainm ent ............. ............ ...................................... 3.6-1 3.6.1.2 Prim ary Containm ent Air Lock ............................................ ....................... 3.6-3 3.6.1.3 Primary Containment Isolation Valves (PCIVs) ........................................... 3.6-7 3.6.1.4 Drywell Pressure ......................................... 3.6-13 3.6.1.5 Dryw ell A ir Tem perature ............................................................................ 3.6-14 3.6.1.6 Low-Low Set (LLS) Valves .......................................................................... 3.6-15 3.6.1.7 Reactor Building-to-Suppression Chamber Vacuum Breakers .................... 3.6-17 3.6.1.8 Suppression Chamber-to-Drywell Vacuum Breakers .................................. 3.6-19 3.6.2.1 Suppression Pool Average Temperature .................................................... 3.6-21 3.6.2.2 Suppression Pool Water Level ............... ................... 3.6-24 3.6.2.3 Residual Heat Removal (RHR) Suppression Pool Cooling .......................... 3.6-25 3.6.2.4 Residual Heat Removal (RHR) Suppression Pool Spray .............. 3.6-27 3 .6 .3 .1 (D eleted) ..................................................................................................... 3 .6-2 9 3.6.3.2 Primary Containment Oxygen Concentration ...................... 3.6-31 3.6.3.3 Drywell Cooling System Fans .................................................................. 3.6-32 3.6.4.1 Secondary Containment .................................... 3.6-33 3.6.4.2 Secondary Containment Isolation Valves (SCIVs) .................. 3.6-36 3.6.4.3 Standby Gas Treatment (SGT) System ...................................................... 3.6-39 3.7 P LA NT SY ST EM S ...................................................................................... 3.7-1 3.7.1 Residual Heat Removal Service Water (RHRSW) System.......................... 3.7-1 3.7.2 Plant Service Water (PSW) System and Ultimate Heat Sink (UHS) ................................. 3.7-3 3.7.3 Diesel Generator (DG) 1B Standby Service Water (SSW)

S yste m .................................................................................................. 3 .7 -6 3.7.4 Main Control Room Environmental Control (MCREC) System .................... 3.7-8 3.7.5 Control Room Air Conditioning (AC) System ................... ............................ 3.7-12 3.7.6 Main Condenser Offgas .............................................................................. 3.7-16 3.7.7 Main Turbine Bypass System ..................................................................... 3.7-18 3.7.8 Spent Fuel Storage Pool Water Level ......................................................... 3.7-19 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans .................. 3.7-20 3.8. ELECTRICAL POWER SYSTEMS ............ ................. 3.8-1 3.8.1 A C Sources - O perating .............................................................................. 3.8-1 3.8.2 AC Sources - Shutdow n ............................................................................... 3.8-20 3.8.3 Diesel Fuel Oil and Transfer, Lube Oil, a nd S tarting A ir .....................................................................................

3 .8-23 3.8.4 DC Sources - O perating .............................................................................. 3.8-26 3.8.5 DC Sources - Shutdow n ............................................................................. 3.8-31 (continued)

HATCH UNIT 2 iii Amendment No.

Turbine Building Ventilation Exhaust System Fans 3.7.9 3.7 PLANT SYSTEMS 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans LCO 3.7.9 One Unit 1 and one Unit 2 TB HVAC exhaust system fan shall be OPERABLE.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One required TB HVAC A.1 Restore required TB 7 days exhaust system fan HVAC exhaust system inoperable, fan to OPERABLE status.

B. Two required TB HVAC B.1 Restore one required 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months exhaust system fans TB HVAC exhaust inoperable, system fan to OPERABLE status.

C. Required Action and C.1 Be in MODE 3. 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months associated Completion Time not met. AND C.2 Be in MODE 4. 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months HATCH UNIT 2 3.7-20 Amendment No.

Turbine Building Ventilation Exhaust System Fans 3.7.9 SURVEILLANCE REQUIREMENTS

NOTE --------------------------------------------------------------

When a TB HVAC exhaust system fan, with associated filter trains, ductwork and dampers, is placed in an inoperable status for the performance of required Surveillances, entry into.

associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

SURVEILLANCE FREQUENCY SR 3.7.9.1 Operate each TB HVAC exhaust system fan 92 days for > 15 minutes.

SR 3.7.9.2 Verify manual transfer capability to alternate 24 months power supply for each TB HVAC exhaust system fan.

HATCH UNIT 2 3.7-21 Amendment No.

Turbine Building Ventilation Exhaust System Fans B 3.7.9 B 3.7 PLANT SYSTEMS B 3.7.9 Turbine Building Ventilation (TB HVAC) Exhaust System Fans BASES BACKGROUND The control room, as part of the control building, is housed within the Units 1 and 2 turbine building structure. As part of the revised design basis accident (DBA) radiological dose analyses implementing Alternative Source Term (AST), the Units 1 and 2 TB HVAC exhaust system fans are credited to mitigate radiological doses to control room personnel. One of the four TB HVAC exhaust system fans is credited with purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident.

The TB HVAC system was originally designed to support power generation and was not considered an engineered safety feature (ESF) system. The primary power generation design function of the TB HVAC system, consisting of supply and exhaust systems, is to provide air movement for temperature and airborne radioactivity control. To accomplish the power generation design function the TB HVAC system runs continuously during normal plant operation.

As part of the implementation of AST, the TB HVAC exhaust system fans (without reliance on the TB HVAC supply system) are credited with performing an ESF design function of mitigating the consequences of the referenced DBAs by purging the activity available for leakage into the control room post-accident. For each unit, air is exhausted from the turbine building by a duct system to the outside environment via the reactor building vent plenum by one of two exhaust fans. The exhaust from the turbine building passes through two 50% capacity filter trains, per unit, but the filtering function is not credited. One of the two 100%

capacity exhaust fans per unit runs continuously during normal plant operation. If the operating exhaust fan fails, the standby exhaust fan' starts automatically.

To accomplish the AST credited purge function post-accident, one of the four TB HVAC exhaust system fans is sufficient to deliver the credited purge flow. The single fan flow capacity necessary to support the original TB HVAC system power generation design functions bounds the AST credited purge flow. The AST dose analyses assume that the turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the start of the 3 applicable DBAs. This assumption allows time for restarting at least one exhaust fan post-accident following a concurrent loss of offsite power.

AST does not take credit for filtration by the TB HVAC exhaust system filter trains.

(continued)

HATCH UNIT 2 B 3.7-41

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES BACKGROUND In support of crediting a single TB HVAC exhaust system fan for purge (continued) flow post-accident, the TB HVAC exhaust systems have been enhanced as follows. To assure that no single failure exists that would preclude the operation of one fan, two fans are required (one fan from each unit).

The TB HVAC exhaust systems and the motor control center panels utilized for the normal non-Class 1 E power source for the TB HVAC exhaust systems have been seismically verified to be able to support the purge function following a Hatch design basis earthquake. Finally, in the unlikely event that the normal power supply for the TB HVAC exhaust fan systems cannot be restored prior to 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months post-accident with a concurrent loss of offsite power, each of the TB HVAC exhaust fans can be powered, one at a time per unit, via manual transfer switches from an essential motor control center (one essential motor control center per unit) that can receive power from an emergency diesel generator.

APPLICABLE The TB HVAC exhaust system fans support maintaining the SAFETY ANALYSES habitability of the control room by purging the area around the control room to reduce the activity available for leakage into the control room following a loss of coolant accident, main steam line break, or control rod drop accident. The TB HVAC exhaust systems are described in Unit 1 FSAR section 10.9.3.4 (Ref. 1) and Unit 2 FSAR section 9.4.4 (Ref. 2). The dose mitigation function of the TB HVAC exhaust systems, specifically crediting purge flow starting 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months after the applicable DBAs, is documented in the Unit 1 and 2 safety analysis in Unit 2 FSAR chapter 15 (Ref. 3). The radiological doses to control room personnel as a result of the various DBAs are also documented in Unit 2 FSAR chapter 15 (Ref. 3). No single failure will cause the loss of the credited turbine building purge function.

The TB HVAC exhaust system fans satisfy Criterion 3 of the NRC Policy Statement.

LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan must be OPERABLE to ensure that at least one is available, assuming a single failure disables the other system. Inability to implement the turbine building purge function could result in exceeding a dose of 5 rem to the control room operators in the event of a loss of coolant accident, main steam line break, or control rod drop accident.

(continued)

HATCH UNIT 2 B 3.7-42

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES LCO One Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC (continued) exhaust system fan are considered OPERABLE when the individual components necessary to control operator exposure are OPERABLE in both systems. Each unit's required TB HVAC exhaust system fan is considered OPERABLE when its associated:

a. One of the two available exhaust fans is OPERABLE,

b. Prefilters, carbon adsorbers, and high efficiency particulate air (HEPA) filters are not excessively restricting flow,

c. Associated ductwork and dampers are OPERABLE, and exhaust flow can be maintained, and

d. Alternate power supply (from essential motor control centers) and associated manual transfer switches are OPERABLE.

OPERABILITY of one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan entails satisfying the requirements listed above for each unit's TB HVAC exhaust system fan. For both Units' TB HVAC exhaust system fans to be OPERABLE, the two required exhaust fans must be independently powered.

APPLICABILITY In MODES 1, 2, and 3, one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan must be OPERABLE to control operator exposure during and following a DBA which could lead to a fission product release in the turbine building.

In MODES 4 and 5, the probability and consequences of a DBA with a fission product release in the turbine building are reduced because of the pressure and temperature limitations in these MODES. Therefore, maintaining one Unit 1 TB HVAC exhaust system fan and one Unit 2 TB HVAC exhaust system fan OPERABLE is not required in MODE 4 or 5.

ACTIONS A.1 With one unit's required TB HVAC exhaust system fan inoperable, an inoperable TB HVAC exhaust system fan must be restored to OPERABLE status within 7 days. With the unit in this condition, the remaining OPERABLE TB HVAC exhaust system fan is adequate to perform the turbine building purge function. However, the overall reliability is reduced because a single failure related to the OPERABLE (continued)

HATCH UNIT 2 B 3.7-43

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES ACTIONS A.1 (continued)

TB HVAC exhaust system fan could result in reduced turbine building purge capability. The 7 day CompletionTime is based on the low probability of a DBA occurring during this time period, and that the remaining OPERABLE TB HVAC exhaust system fan can provide the required capabilities.

B.1 If two required TB HVAC exhaust system fans are inoperable in MODE 1, 2, or 3, the TB HVAC exhaust systems fans cannot perform their turbine building purge function. Actions must be taken to restore one required TB HVAC exhaust system fan to OPERABLE status within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is reasonable based on the low probability of a DBA occurring during this time period, the purge function is maintained via natural wind-driven ventilation in the turbine building, and the low probability that sufficient activity would be released into the turbine building following a DBA to significantly impact control room habitability via inleakage.

C.1 and C.2 In MODE 1, 2, or 3, if the inoperable required TB HVAC exhaust system fans cannot be restored to OPERABLE status within the associated Completion Time, the unit must be placed in a MODE that minimizes risk. To achieve this status, the unit must be placed in at least MODE 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in MODE 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

SURVEILLANCE The Surveillances are modified by a Note to indicate that when a REQUIREMENTS required TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, is placed in an inoperable status for performance of required Surveilances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months provided one of the other TB HVAC exhaust system fans, with associated filter trains, ductwork, and dampers, can perform the turbine building purge function post-accident. Upon completion of the Surveillance, or expiration of the 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months allowance, the TB HVAC exhaust system fan, with associated filter trains, ductwork, and dampers, must be returned to OPERABLE status or the applicable Condition entered and Required Actions taken.

This Note is based on the AST dose analyses assumption that the (continued)

HATCH UNIT 2 [] 3.7-44

Turbine Building Ventilation Exhaust System Fans B 3.7.9 BASES SURVEILLANCE turbine building purge flow is manually initiated within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months of the REQUIREMENTS start of the 3 applicable DBAs. Consequently this testing allowance (continued) does not significantly impact the ability to manually initiate turbine building purge flow within 9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months .

SR 3.7.9.1 This SR verifies that each of the two available TB HVAC exhaust system fans on both Unit 1 and Unit 2, total of four TB HVAC exhaust system fans, starts on demand and continues to operate. One of the two 100% capacity exhaust fans per unit runs continuously during normal plant operation. One of the exhaust fans per unit is in standby.

Standby systems should be checked periodically to ensure that they start and function properly. Operating the standby TB HVAC exhaust system fans on both Unit 1 and Unit 2 for > 15 minutes demonstrates-that each exhaust fan can perform the turbine building purge function by exhausting turbine building air to the reactor building vent plenum and that any blockage, fan or motor failure can be detected for corrective action.

As the environmental and normal operating conditions of this system are not severe, testing each subsystem once every 92 days provides an adequate check on this system. Furthermore, the 92 day Frequency is based on the known reliability of the equipment (one fan per unit running continuously during normal operation) and the exhaust fan redundancy available.

SR 3.7.9.2 This SR verifies manual transfer capability to the alternate power supply for each TB HVAC exhaust system fan. Since during normal plant operation each continuously running exhaust fan per unit is using its normal power supply, the standby or alternate power supply from an essential motor control center (one essential motor control center per unit) should be checked periodically to ensure the essential motor control center can provide power to each TB HVAC exhaust system fan via a manual transfer switch. Each of the four TB HVAC exhaust system fans, two per unit, should be connected to the alternate power supply one at a time via a manual transfer switch. This Surveillance can be performed with the reactor at power. The 24 month Frequency is consistent with other similar ventilation system SRs.

REFERENCES 1. Unit 1 FSAR, Section 10.9.3.4.

2. Unit 2 FSAR section 9.4.4

3. Unit 2 FSAR, Chapter 15.

HATCH UNIT 2 B 3.7-45

v t e Letter Sequence Response to RAI
TAC:MD2934, (Approved, Closed)
Initiation Request, Request Acceptance... Administration Meeting, Meeting Questions 14 November 2006 22 February 2007 15 March 2007 10 April 2007 26 April 2007 8 May 2007 30 May 2007 16 August 2007 3 October 2007 9 January 2008 13 February 2008 30 May 2008 9 July 2008 Answers 25 February 2008 27 February 2008 11 December 2007 4 February 2008 13 March 2008 1 April 2008 5 May 2008 25 June 2008 14 August 2008 Results Approval Other: ML080110051, ML081900331, ML081900338
MONTHYEAR2008-02-13 [Table View]

NL-08-0903, Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans

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NL-08-0903, Request to Implement an Alternative Source Term Response to Request for Additional Information Regarding the Turbine Building Ventilation Exhaust System Fans

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