Text

Limerick Generating Station, Units 1 and 2, License Amendment Request to Include Alternate Method of Verifying Drywell Unidentified Leakage
	ML111650563
Person / Time
Site:	Limerick
Issue date:	06/14/2011
From:	Jesse M D; Exelon Generation Co, Exelon Nuclear
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	Download: ML111650563 (36)
	v • d • e

10 June 1 2011 U.S.Nuclear ATTN: Washington, Limerick Generating Station, Units 1 and 2 Facility Operating Nos.NPF-85 License Amendment Request to Include an Alternate Method of Verifying Drywell Unidentified LealKa(le 1)from P.R.Simpson (Exelon Generation Company, LLC for Dresden Nuclear Power Station)to U.S.NRC, IIRequest for Emergency License Amendment Regarding Drywell Floor Drain Sump Monitoring System,lI dated August 18, 2008 2)Letter from C.Gratton (U.S.NRC)to C.G.Pardee (Exelon Generation Company, LLC), IIDresden Nuclear Power Station, Unit 3-Issuance of Emergency Amendment Regarding Drywell Floor Drain Sump Monitoring System (TAC No.MD9467)," August 2008 3)Letter from J.L.Hansen (Exelon Generation Company, LLC for Dresden Nuclear Power Station and Quad Cities Nuclear Power Station)to U.S.NRC,"Request for LicenseAmendmentto Revise Technical Specification 3.4.5,"RCS Leakage Detection Instrumentation," to Allow Alternate Method of Verifying Drywell Leakage" dated August 28,2009 4)Letter from C.Gratton (U.S.NRC)to M.J.Pacilio (Exelon Generation Company, LLC),"Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2-Issuance of Amendments RE: Authorizing Alternative Methods of Verifying Leakage within the Drywell (TAC NOS.ME2148 thru ME2151)," dated August 16, 2010 In accordance with10 CFR 50.90,"Application for amendment of license, construction permit, or early site permit," Exelon Generation Company, LLC (EGC)requests an amendment to the Technical Specifications (TS)for Limerick Generating Station (LGS), Units 1 and 2.The proposed amendment revises Technical Specification (TS)3.4.3.1,"LEAKAGE DETECTION SYSTEMS," to support addition of an alternative method of verifying that unidentified leakage in the drywell is within limits.In Reference 1, EGC requested a temporary emergency license amendment for Dresden Nuclear Power Station (DNPS), Unit 3 to allow the reconfiguration of the drywell floor drain sump (DWFDS)flow monitoring system such that the drywell equipment drain sump (DWEDS)could be used as an alternate method to verify that Reactor Coolant System (RCS)leakage in the drywell is within TS limits.The emergency license amendment request was reviewed and approved by the NRC in Reference 2.Following the emergency license amendment approval by the NRC, EGC submitted a request for a permanentlicensechange for both DNPS and Quad Cities Nuclear Power Station (QCNPS)in Reference 3.The NRC approved the license u.s.Nuclear Regulatory Commission June 14, 2011 Page 2 amendment for both DNPS and QCNPS in the Reference 4 Safety Evaluation Report.The changes proposed in this license amendment request seek to incorporate the alternate method approved for DNPS and QCNPS into the LGS TS for Units 1 and 2.The changes proposed in this license amendment request have wording and justification similar to the changes approved for DNPS and QCNPS.The DNPS and QCNPS submittal and Safety Evaluation Report were verified for applicabilityandutilized as the template for this submittal.

Attachment 1 provides a description of the proposed change.Attachment 2 provides the existing TS page markups showing the proposed changes.Attachment 3 provides the associated TS Bases markups for information only.There are two regulatory commitments contained in this letter, detailed in Attachment 4.Attachment 5 contains drywell sump level monitoring system configuration drawings for information only.The proposed changes have been reviewed by the LGS Plant Operations Review Committee and approved by the Nuclear Safety Review Board in accordance with the requirements of the EGC Quality Assurance Program.EGC requests approval of the proposed amendment by June 14, 2012.Once approved, the amendment shall be implemented within 60 days of issuance.In accordance with 10 CFR 50.91,"Notice for public comment;State consultation, II paragraph (b), EGC is notifying the Commonwealth of Pennsylvania of this application for license amendment by transmitting a copy of this letter and its attachments to the designated State Official.Should you have any questions concerning this letter, please contact Ms.Wendy E.Croft at (610)765-5726.I declare under penalty of perjury that the foregoing is true and correct.Executed on the 14 th day of June 2011.

Michael D.Je se Director, Licen On d Regulatory Affairs Exelon Generation Company, LLC Attachments:

1.2.3.4.5.Evaluation of Proposed Changes Markup of Technical Specification Pages Markup of Technical Specifications Bases Pages (For Information Only)List of Commitments Drywell Sump Level Monitoring System Configuration Drawings (For Information Only)cc: USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, LGS USNRC Project Manager, LGSR.R.Janati, Bureau of Radiation Protection u.s.Nuclear Regulatory Commission June 14, 2011 Page 2 amendment for both DNPS and QCNPS in the Reference 4 Safety Evaluation Report.The changes proposed in this license amendment request seek to incorporate the alternate method approved for DNPS and QCNPS into the LGS TS for Units 1 and 2.The changes proposed in this license amendment request have wording and justification similar to the changes approved for DNPS and QCNPS.The DNPS and QCNPS submittal and Safety Evaluation Report were verified for applicabilityandutilized as the template for this submittal.

Attachment 1 provides a description of the proposed change.Attachment 2 provides the existing TS page markups showing the proposed changes.Attachment 3 provides the associated TS Bases markups for information only.There are two regulatory commitments contained in this letter, detailed in Attachment 4.Attachment 5 contains drywell sump level monitoring system configuration drawings for information only.The proposed changes have been reviewed by the LGS Plant Operations Review Committee and approved by the Nuclear Safety Review Board in accordance with the requirements of the EGC Quality Assurance Program.EGC requests approval of the proposed amendment by June 14, 2012.Once approved, the amendment shall be implemented within 60 days of issuance.In accordance with 10 CFR 50.91,"Notice for public comment;State consultation, II paragraph (b), EGC is notifying the Commonwealth of Pennsylvania of this application for license amendment by transmitting a copy of this letter and its attachments to the designated State Official.Should you have any questions concerning this letter, please contact Ms.Wendy E.Croft at (610)765-5726.I declare under penalty of perjury that the foregoing is true and correct.Executed on the 14 th day of June 2011.

Michael D.Je se Director, Licen On d Regulatory Affairs Exelon Generation Company, LLC Attachments:

1.2.3.4.5.Evaluation of Proposed Changes Markup of Technical Specification Pages Markup of Technical Specifications Bases Pages (For Information Only)List of Commitments Drywell Sump Level Monitoring System Configuration Drawings (For Information Only)cc: USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, LGS USNRC Project Manager, LGSR.R.Janati, Bureau of Radiation Protection ATTACHMENT 1 Evaluation of Proposed Changes Limerick Generating Station, Units 1 and 2 Facility Operating License Nos.NPF-39 and NPF-85 ATTACHMENT 1 Evaluation of Proposed Changes Limerick Generating Station, Units 1 and 2 Facility Operating License Nos.NPF-39 and NPF-85

Subject:

License Amendment Request to Include an Alternate Method of Verifying Drywell Unidentified Leakage 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

2.1 Background

3.0 TECHNICAL EVALUATION

3.1 Drywell Sump Level Monitoring System Description 3.2 RCS Leakage Limits 3.3 RCS Leakage Detection While Filling the DWFDS 3.4 Summary

4.0 REGULATORY EVALUATION

4.1 Applicable

Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration

4.4 Conclusions

5.0 ENVIRONMENTAL

CONSIDERATION

6.0 REFERENCES

Subject:

License Amendment Request to Include an Alternate Method of Verifying Drywell Unidentified Leakage 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

2.1 Background

3.0 TECHNICAL EVALUATION

3.1 Drywell Sump Level Monitoring System Description 3.2 RCS Leakage Limits 3.3 RCS Leakage Detection While Filling the DWFDS 3.4 Summary

4.0 REGULATORY EVALUATION

4.1 Applicable

Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration

4.4 Conclusions

5.0 ENVIRONMENTAL

CONSIDERATION

6.0 REFERENCES

Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 1 of 10 1.0

SUMMARY

DESCRIPTION This evaluation supports a request to amend Operating Licenses NPF-39 and NPF-85 for Limerick Generating Station (LGS)Units 1 and 2, respectively.

The proposed changes would amend the Operating Licenses by revising Technical Specification (TS)3.4.3.1,"LEAKAGE DETECTION SYSTEMS," to add an alternative method to verify Reactor Coolant System (RCS)unidentified leakage in the drywell is within limits.The proposed amendment revises TS 3.4.3.1,"LEAKAGE DETECTION SYSTEMS," to support implementation of an alternate method to quantify Reactor Coolant System (RCS)leakage in theprimarycontainment (Le., the drywell).The proposed alternate method uses the installed drywell equipment drain sump (DWEDS)monitoring system, with the drywell floor drain sump (DWFDS)overflowing to the DWEDS, to verify that RCS leakage in the drywell is within TS 3.4.3.2,"OPERATIONAL LEAKAGE," limits.This configuration would only be used when the DWFDS monitoring system is unavailable.

The purpose of the proposed license amendment is to increase operating flexibility and avoid unnecessary plant transients due to extended inoperability of the DWFDS monitoring system (e.g., inoperability caused by a component failure).Theproposedchange will enable each unit to reconfigure the DWFDS flowmonitoringsystem such that it is overflowing into the DWEDS.The reconfigured drywell sumpmonitoringsystem can then be used to verify that drywell leakage is within the limits specified in TS 3.4.3.2.This operating configuration is conservative to the normal configuration in that the TS 3.4.3.2.b unidentified leakage limit of less than or equal to 5 gallons per minute (gpm)will be applied to total leakage, as opposed to the TS 3.4.3.2.c limit of less than or equal to 30 gpm.2.0 DETAILED DESCRIPTION This proposed amendment is consistent with the License Amendment Request and subsequent NRC Safety Evaluation Report for Dresden Nuclear Power Station (DNPS)and Quad CitiesNuclearPower Station (QCNPS)pertaining to an alternate method of verifying drywell leakage, References 6.1 and 6.2, respectively.

The proposed TS and TS Bases changes are:*TS Limiting Condition for Operation (LCO)3.4.3.1.b is revised to state that,"the drywell sump monitoring system" is required to be operable.*TS 3.4.3.1 , Action B is revised to remove the specific references to the DWFDS monitoring system and replaces this with a reference to the drywell sump monitoring system.*TS BASES 3/4.4.3.1 is revised to define the drywell sump monitoring system as either the DWFDS monitoring system or the DWEDS monitoring system with the DWFDS overflowing to the DWEDS.A markup of the proposed TS and TS Bases page changes are provided in Attachments 2 and 3, respectively.

The TS Bases page changes are provided for information only.Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 1 of 10 1.0

SUMMARY

DESCRIPTION This evaluation supports a request to amend Operating Licenses NPF-39 and NPF-85 for Limerick Generating Station (LGS)Units 1 and 2, respectively.

The proposed changes would amend the Operating Licenses by revising Technical Specification (TS)3.4.3.1,"LEAKAGE DETECTION SYSTEMS," to add an alternative method to verify Reactor Coolant System (RCS)unidentified leakage in the drywell is within limits.The proposed amendment revises TS 3.4.3.1,"LEAKAGE DETECTION SYSTEMS," to support implementation of an alternate method to quantify Reactor Coolant System (RCS)leakage in theprimarycontainment (Le., the drywell).The proposed alternate method uses the installed drywell equipment drain sump (DWEDS)monitoring system, with the drywell floor drain sump (DWFDS)overflowing to the DWEDS, to verify that RCS leakage in the drywell is within TS 3.4.3.2,"OPERATIONAL LEAKAGE," limits.This configuration would only be used when the DWFDS monitoring system is unavailable.

The purpose of the proposed license amendment is to increase operating flexibility and avoid unnecessary plant transients due to extended inoperability of the DWFDS monitoring system (e.g., inoperability caused by a component failure).Theproposedchange will enable each unit to reconfigure the DWFDS flowmonitoringsystem such that it is overflowing into the DWEDS.The reconfigured drywell sumpmonitoringsystem can then be used to verify that drywell leakage is within the limits specified in TS 3.4.3.2.This operating configuration is conservative to the normal configuration in that the TS 3.4.3.2.b unidentified leakage limit of less than or equal to 5 gallons per minute (gpm)will be applied to total leakage, as opposed to the TS 3.4.3.2.c limit of less than or equal to 30 gpm.2.0 DETAILED DESCRIPTION This proposed amendment is consistent with the License Amendment Request and subsequent NRC Safety Evaluation Report for Dresden Nuclear Power Station (DNPS)and Quad CitiesNuclearPower Station (QCNPS)pertaining to an alternate method of verifying drywell leakage, References 6.1 and 6.2, respectively.

The proposed TS and TS Bases changes are:*TS Limiting Condition for Operation (LCO)3.4.3.1.b is revised to state that,"the drywell sump monitoring system" is required to be operable.*TS 3.4.3.1 , Action B is revised to remove the specific references to the DWFDS monitoring system and replaces this with a reference to the drywell sump monitoring system.*TS BASES 3/4.4.3.1 is revised to define the drywell sump monitoring system as either the DWFDS monitoring system or the DWEDS monitoring system with the DWFDS overflowing to the DWEDS.A markup of the proposed TS and TS Bases page changes are provided in Attachments 2 and 3, respectively.

The TS Bases page changes are provided for information only.

Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 2 of 10 2.1 Background On August 16, 2008, at approximately 2000 hours0.0231 days 0.556 hours 0.00331 weeks 7.61e-4 months , operations personnel at DNPS attempted to pump the DNPS Unit 3 DWFDS utilizing Dresden Operating Procedure (DOP)2000-24,"Drywell Sump Operation.

II Successful completion of DOP 2000-24 is used, in part, to satisfy DNPS Surveillance Requirement (SR)3.4.4.1,"Verify RCS unidentified and total LEAKAGE and unidentified LEAKAGE increase are within limits." The pumps started as expected;however, the integrator indicated no flow.During a second attempt to operate the pumps, DNPS operations personnel observed the position indicators for the two containment isolation valves, which indicated that the valves were in their proper position.DNPS maintenance personnel also inspected the pump breakers and measured pump motor current, with no abnormalities identified.

The drywell floor drain sump pumps had been successfully pumped previously at 1600 hours0.0185 days 0.444 hours 0.00265 weeks 6.088e-4 months , and every four hours prior.DNPS conducted troubleshooting actions to identify possible malfunctions.

These troubleshooting actions indicated that the containment isolation valve (Le., one of two drywell floor drain sump pump discharge valves)may have failed closed.Since the drywell floor drain sump could not be pumped, DNPS was not able to satisfy the acceptance criteria of SR 3.4.4.1 for DNPS Unit 3.Therefore, TS LCO 3.4.4 for unidentified leakage could not be verified to be within limits.The applicable TS action requires that the unit be placed in Mode 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and Mode 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months .In that the containment isolation valve is part of primary containment, the valve could not be repaired during unit operation.

As such, DNPS requested, and the U.S.Nuclear Regulatory Commission (USNRC)granted, a Notice of Enforcement Discretion (NO ED)for TS 3.4.4, Condition C and TS 3.4.5, Condition C (Le., References 6.3 and 6.4, respectively).

Specifically, the NOED provided a seven-day extension to the TS Completion Times to place the unit in Mode 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and Mode 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months .The extension provided sufficient time to reconfigure the DWFDS monitoring system such that the DWEDS monitoring system could be physically utilized to quantify unidentified drywell leakage.In addition, the seven-day extension provided sufficient time for DNPS to request, and the USNRC to review and approve, an emergency license amendment to revise TS 3.4.5, on a temporary basis, to approve the use of the DWEDS monitoring system as an alternate method to quantify unidentified leakage (Le., References 6.5 and 6.6, respectively).

Subsequently, DNPS and Quad Cities Nuclear Power Station (QCNPS)submitted an additional license amendment request, Reference 6.1, requesting the emergency license amendment changes be made permanent for both stations.The USNRC requested additional information to support the license amendment request review in the Reference 6.7 letter.The DNPS and QCNPS responses were provided in the Reference 6.8 and 6.9 submittals.

The license amendment request was approved by the USNRC in August 2010 (Reference 6.2).To prevent the need for a similar emergency license amendment, the changes proposed in this request seek to incorporate the alternate method of verifying drywell leakage into the LGS TS for Unit 1 and Unit 2.Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 2 of 10 2.1 Background On August 16, 2008, at approximately 2000 hours0.0231 days 0.556 hours 0.00331 weeks 7.61e-4 months , operations personnel at DNPS attempted to pump the DNPS Unit 3 DWFDS utilizing Dresden Operating Procedure (DOP)2000-24,"Drywell Sump Operation.

II Successful completion of DOP 2000-24 is used, in part, to satisfy DNPS Surveillance Requirement (SR)3.4.4.1,"Verify RCS unidentified and total LEAKAGE and unidentified LEAKAGE increase are within limits." The pumps started as expected;however, the integrator indicated no flow.During a second attempt to operate the pumps, DNPS operations personnel observed the position indicators for the two containment isolation valves, which indicated that the valves were in their proper position.DNPS maintenance personnel also inspected the pump breakers and measured pump motor current, with no abnormalities identified.

The drywell floor drain sump pumps had been successfully pumped previously at 1600 hours0.0185 days 0.444 hours 0.00265 weeks 6.088e-4 months , and every four hours prior.DNPS conducted troubleshooting actions to identify possible malfunctions.

These troubleshooting actions indicated that the containment isolation valve (Le., one of two drywell floor drain sump pump discharge valves)may have failed closed.Since the drywell floor drain sump could not be pumped, DNPS was not able to satisfy the acceptance criteria of SR 3.4.4.1 for DNPS Unit 3.Therefore, TS LCO 3.4.4 for unidentified leakage could not be verified to be within limits.The applicable TS action requires that the unit be placed in Mode 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and Mode 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months .In that the containment isolation valve is part of primary containment, the valve could not be repaired during unit operation.

As such, DNPS requested, and the U.S.Nuclear Regulatory Commission (USNRC)granted, a Notice of Enforcement Discretion (NO ED)for TS 3.4.4, Condition C and TS 3.4.5, Condition C (Le., References 6.3 and 6.4, respectively).

Specifically, the NOED provided a seven-day extension to the TS Completion Times to place the unit in Mode 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and Mode 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months .The extension provided sufficient time to reconfigure the DWFDS monitoring system such that the DWEDS monitoring system could be physically utilized to quantify unidentified drywell leakage.In addition, the seven-day extension provided sufficient time for DNPS to request, and the USNRC to review and approve, an emergency license amendment to revise TS 3.4.5, on a temporary basis, to approve the use of the DWEDS monitoring system as an alternate method to quantify unidentified leakage (Le., References 6.5 and 6.6, respectively).

Subsequently, DNPS and Quad Cities Nuclear Power Station (QCNPS)submitted an additional license amendment request, Reference 6.1, requesting the emergency license amendment changes be made permanent for both stations.The USNRC requested additional information to support the license amendment request review in the Reference 6.7 letter.The DNPS and QCNPS responses were provided in the Reference 6.8 and 6.9 submittals.

The license amendment request was approved by the USNRC in August 2010 (Reference 6.2).To prevent the need for a similar emergency license amendment, the changes proposed in this request seek to incorporate the alternate method of verifying drywell leakage into the LGS TS for Unit 1 and Unit 2.

Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 3 of 10

3.0 TECHNICAL EVALUATION

3.1 Drywell Sump Level Monitoring System Description The DWEDS at LGS is located immediately adjacent to the DWFDS, withthetop of both sumps (tanks)at the same elevation, approximately seven feet apart.There are no obstructions between the two sumps to prevent or divert drywell floor drain sump overflow from reaching the drywell equipment drain sump.Based on the sump configurations, an engineering computation determined that approximately 550 gallons are required in the DWFDS for overflow into the DWEDS.Attachment 5 contains drawings detailing the physical configuration of the sumps.LGS has verified that the sump configuration and sump volumes for LGS Units 1 and 2 (i.e., both DWEDS and DWFDS)are equivalent to the DNPS Unit 3 DWFDS and DWEDS sump configuration and volume (Le., approximately 1000 gallons full capacity each).All leakage from Reactor Coolant Pressure Boundary (RCPB)components inside the drywell, with the exception of leakage from the Main Steam Relief Valves (MSRVs)(Updated Final Safety Analysis Report (UFSAR)Section 5.2.5.2.1.8), flows directly to either the drywell equipment drain sump orthedrywell floor drain sump.There are no other reservoirs in the drywell of sufficient capacity to prevent leakage from draining directly to either of these sumps.Both drain sumps are identically sized, horizontal cylindrical tanks located inside the reactor vessel pedestal below the diaphragm slab and vented to the drywell atmosphere.

Leakage from RCPS components inside the primary containment which are not normally subject to leakage is collected by the DWFDS.This leakage, which may originate from any number of sources within the drywell, is transported to the sump via the floor drain network within the drywell.Thus, separation of unidentified leakage from the identifiable leakage routed to the equipment drain sump ensures that a small unidentified leakage that is of concern will not be masked by a larger, acceptable, identified leakage.The DWEDS monitoring system is similar to the DWFDS monitoring system.Certain RCPB components within the drywell are, by the nature of their design, normally subject to a limited amount of leakage.These components include pump seals, valve stem packings, and other equipment that cannot practicably be made to be completely leak-tight.

These leakages are piped directly tothedrywell equipment drain sump.All of the various drains are open only to the equipment they serve, thereby receiving leakage only from identified sources.Background leakage to this sump is determined during initial plant operation.

Rates of leakage collection in excess of background indicates abnormal RCPB leakage.The control circuits for the two monitoring systems perform the same functions, and sump instrumentation consists of the same components and performs a similar function.Instruments for both monitoring systems are calibrated using similar plant procedures to satisfy TS Surveillance Requirements (SRs)for functional testing and calibration.

Each sump tank has its own level transmitter which is monitored by a dedicated processing unit.Normally closed drain valves are provided, enabling the level in each tank to increase as leakage drains into them.The processing unit calculates an average leak rate for a given measurement period by establishing the amount of increase in level that occurred during the period, and converting that value into volumetric terms (gpm).The processing units provide an alarm in the main control room each time the average leak rate changes by a predetermined value since the last time that alarm was reset.The setpoint isa1 gpm change in unidentified Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 3 of 10

3.0 TECHNICAL EVALUATION

3.1 Drywell Sump Level Monitoring System Description The DWEDS at LGS is located immediately adjacent to the DWFDS, withthetop of both sumps (tanks)at the same elevation, approximately seven feet apart.There are no obstructions between the two sumps to prevent or divert drywell floor drain sump overflow from reaching the drywell equipment drain sump.Based on the sump configurations, an engineering computation determined that approximately 550 gallons are required in the DWFDS for overflow into the DWEDS.Attachment 5 contains drawings detailing the physical configuration of the sumps.LGS has verified that the sump configuration and sump volumes for LGS Units 1 and 2 (i.e., both DWEDS and DWFDS)are equivalent to the DNPS Unit 3 DWFDS and DWEDS sump configuration and volume (Le., approximately 1000 gallons full capacity each).All leakage from Reactor Coolant Pressure Boundary (RCPB)components inside the drywell, with the exception of leakage from the Main Steam Relief Valves (MSRVs)(Updated Final Safety Analysis Report (UFSAR)Section 5.2.5.2.1.8), flows directly to either the drywell equipment drain sump orthedrywell floor drain sump.There are no other reservoirs in the drywell of sufficient capacity to prevent leakage from draining directly to either of these sumps.Both drain sumps are identically sized, horizontal cylindrical tanks located inside the reactor vessel pedestal below the diaphragm slab and vented to the drywell atmosphere.

Leakage from RCPS components inside the primary containment which are not normally subject to leakage is collected by the DWFDS.This leakage, which may originate from any number of sources within the drywell, is transported to the sump via the floor drain network within the drywell.Thus, separation of unidentified leakage from the identifiable leakage routed to the equipment drain sump ensures that a small unidentified leakage that is of concern will not be masked by a larger, acceptable, identified leakage.The DWEDS monitoring system is similar to the DWFDS monitoring system.Certain RCPB components within the drywell are, by the nature of their design, normally subject to a limited amount of leakage.These components include pump seals, valve stem packings, and other equipment that cannot practicably be made to be completely leak-tight.

These leakages are piped directly tothedrywell equipment drain sump.All of the various drains are open only to the equipment they serve, thereby receiving leakage only from identified sources.Background leakage to this sump is determined during initial plant operation.

Rates of leakage collection in excess of background indicates abnormal RCPB leakage.The control circuits for the two monitoring systems perform the same functions, and sump instrumentation consists of the same components and performs a similar function.Instruments for both monitoring systems are calibrated using similar plant procedures to satisfy TS Surveillance Requirements (SRs)for functional testing and calibration.

Each sump tank has its own level transmitter which is monitored by a dedicated processing unit.Normally closed drain valves are provided, enabling the level in each tank to increase as leakage drains into them.The processing unit calculates an average leak rate for a given measurement period by establishing the amount of increase in level that occurred during the period, and converting that value into volumetric terms (gpm).The processing units provide an alarm in the main control room each time the average leak rate changes by a predetermined value since the last time that alarm was reset.The setpoint isa1 gpm change in unidentified Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 4 of 10 leakage collected in the drywell floor drain sump tank, anda2 gpm change in identified leakage collected in the drywell equipment drain tank.Alarms are also generated in the main control room for high total average leak rate.The high total average leak rate alarm setpoints can be adjusted at the processing unit, which is located in the main control room, as the amount of acceptable identified leakage changes during operation.

Indication of the leakage rates is provided in the main control room onmounted indicators.

Sump tank levels (in gallons)are provided on monitors from the Plant Monitoring System.Level switches, which are independent of the level transmitters, open the sump tank drain valves when the level increases to an upper setpoint value and keep them open until the level decreases to the lower setpoint value.The level switches then close the drain valves and reset the processing units to start a new measurement period.The measurement period must be long enough to ensure that the level transmitter loop can adequately detect the increase in level that would correspond to the 1 gpm and 2 gpm changes in leak rates described above, and yet short enough to ensure that such a leak rate will be detected within an hour.The measurement period will be less than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months .The transmitters which are located in the reactor enclosure and the processing units which are located in the main control room are accessible during normal plant operation for calibration.

The transmitters can be isolated from the sump tanks by existing bypass manifolds.

Zero and span adjustments can be made using portable test equipment.

The processing unit functions can be calibrated by applying known input levels at the unit and observing the response.The Drywell Sump Level Monitoring System (DSLMS)is comprised of the processing units, level transmitters, control room leakage flow indicators and interconnecting raceway and cables.The DSLMS has been demonstrated to remain operational after a Safe Shutdown Earthquake.

The DSLMS is energized by Class1E power.The Class1E power to the panel is provided with a Class1E fuse and circuit breaker in series to meet separation requirements.

The DSLMS is automatically shed from the Class1E power in the event of a Loss of Coolant Accident (the load shedding relay, however, is not qualified for Class1E service).In addition, to the sump level monitoring system described above, the discharge from each sump is monitored by a flow element.The measured flow rate is integrated and recorded in the control room.A control room alarm is also provided to indicate excessive discharge rates.These indications and alarms are provided in accordance with Regulatory Guide 1.45.3.2 RCS Leakage Limits TS 3.4.3.2,"OPERATIONAL LEAKAGE,II specifies the leakage limits for the RCS.The leakage limits require, in part, unidentified leakage to be less than or equal to 5 gpm, total leakage averaged over the previous 24-hour period to be less than or equal to 25 gpm, and the increase in unidentified leakage within the previous 24-hour period to be less than 2 gpm.Section 5.2.5 of the LGS UFSAR describes the methods used for detection of leakage through the RCPS, and specifies use of the drywell sumps (Le., DWFDS and DWEDS)as the primary methods that can be used.The leakage collected in the DWEDS is identified leakage, and the leakage collected in the DWFDS is unidentified leakage.TS 3.4.3.1 currently requires the DWFDS be operable as a RCS leakage detection system.Theproposedchange revises TS 3.4.3.1 to support the addition of an alternative method to use the Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 4 of 10 leakage collected in the drywell floor drain sump tank, anda2 gpm change in identified leakage collected in the drywell equipment drain tank.Alarms are also generated in the main control room for high total average leak rate.The high total average leak rate alarm setpoints can be adjusted at the processing unit, which is located in the main control room, as the amount of acceptable identified leakage changes during operation.

Indication of the leakage rates is provided in the main control room onmounted indicators.

Sump tank levels (in gallons)are provided on monitors from the Plant Monitoring System.Level switches, which are independent of the level transmitters, open the sump tank drain valves when the level increases to an upper setpoint value and keep them open until the level decreases to the lower setpoint value.The level switches then close the drain valves and reset the processing units to start a new measurement period.The measurement period must be long enough to ensure that the level transmitter loop can adequately detect the increase in level that would correspond to the 1 gpm and 2 gpm changes in leak rates described above, and yet short enough to ensure that such a leak rate will be detected within an hour.The measurement period will be less than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months .The transmitters which are located in the reactor enclosure and the processing units which are located in the main control room are accessible during normal plant operation for calibration.

The transmitters can be isolated from the sump tanks by existing bypass manifolds.

Zero and span adjustments can be made using portable test equipment.

The processing unit functions can be calibrated by applying known input levels at the unit and observing the response.The Drywell Sump Level Monitoring System (DSLMS)is comprised of the processing units, level transmitters, control room leakage flow indicators and interconnecting raceway and cables.The DSLMS has been demonstrated to remain operational after a Safe Shutdown Earthquake.

The DSLMS is energized by Class1E power.The Class1E power to the panel is provided with a Class1E fuse and circuit breaker in series to meet separation requirements.

The DSLMS is automatically shed from the Class1E power in the event of a Loss of Coolant Accident (the load shedding relay, however, is not qualified for Class1E service).In addition, to the sump level monitoring system described above, the discharge from each sump is monitored by a flow element.The measured flow rate is integrated and recorded in the control room.A control room alarm is also provided to indicate excessive discharge rates.These indications and alarms are provided in accordance with Regulatory Guide 1.45.3.2 RCS Leakage Limits TS 3.4.3.2,"OPERATIONAL LEAKAGE," specifies the leakage limits for the RCS.The leakage limits require, in part, unidentified leakage to be less than or equal to 5 gpm, total leakage averaged over the previous 24-hour period to be less than or equal to 25 gpm, and the increase in unidentified leakage within the previous 24-hour period to be less than 2 gpm.Section 5.2.5 of the LGS UFSAR describes the methods used for detection of leakage through the RCPS, and specifies use of the drywell sumps (Le., DWFDS and DWEDS)as the primary methods that can be used.The leakage collected in the DWEDS is identified leakage, and the leakage collected in the DWFDS is unidentified leakage.TS 3.4.3.1 currently requires the DWFDS be operable as a RCS leakage detection system.Theproposedchange revises TS 3.4.3.1 to support the addition of an alternative method to use the Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 5 of 10 installed DWEDS in the situation that the DWFDS is inoperable and the DWEDS is operable.In this situation the inoperable DWFDS would overflow into the DWEDS which would be capable of quantifying total RCS leakage (Le., unidentified plus identified leakage).The resultant value of total RCS leakage would be conservatively verified to be less than the TS 3.4.3.2.b unidentified leakage limit of 5 gpm and TS 3.4.3.2.1 unidentified leakage increase limit of 2 gpm within the previous 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .3.3 RCS Leakage Detection While Filling the DWFDS LGS TS SR 4.4.3.2.1.b requires the verification every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that RCS leakage measured by the DWFDS and DWEDS is within the specified limits of TS 3.4.3.2 (unidentified leakage to be less than or equal to 5 gpm and the increase in unidentified leakage within the previous 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to be less than 2 gpm).As described above, after the DWFDS begins overflowing into the DWEDS, the DWEDS can be used to measure total leakage (Le., unidentified plus identified leakage).Overflow into the DWEDS was determined by an engineering evaluation tooccurafter accumulation of approximately 550 gallons in the DWFDS.In order for the DWFDS to overflow into the DWEDS, LGS personnel would either have to manually fill the DWFDS with an external water source or allow unidentified RCS leakage to fill the DWFDS.The use of unidentified RCS leakage to fill the DWFDS at or above 550 gallons in an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months time period would require: 1.A minimum unidentified leakage rate of approximately 1.14gpm,and 2.The regulatory commitments delineated in this submittal for LGS, Units 1 and 2 (Le., verification of flow from the DWFDS to the DWEDS, prior to the initial use of the alternate monitoring method for a specific unit)have been satisfied.

The minimum unidentified leakage rate of approximately 1.14 gpm is based on the leakage rate required to fill approximately 550 gallons in the DWFDS in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months .The 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months period represents the TS-required surveillance interval as specified in SR 4.4.3.2.1.b but does not included the additional 25%grace, or 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , allowed by SR 4.0.2.This minimum leakage rate 1.14 gpm would cause the DWFDS to overflow into the DWEDS within the required SR 4.4.3.2.1.b interval.TS 3.4.3.2.1 requires that a'2 gpm increase in unidentified leakage over a 24-hour period is able to be detected.Conservatively assuming an empty DWFDS and a minimum, immediate increase in unidentified leak rate of 2 gpm the DWFDS would fill up to approximately 550 gallons and begin to overflow to the DWEDS in 4.6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .As stated above in Section 3.1 of this Attachment, the level switches will detecta2 gpm change in leak rates in the DWEDS and provide an alarm in the main control room.This meets the TS 3.4.3.2.1 requirement to detect a 2 gpm increase in unidentified leakage over a 24-hour period.TS 3.4.3.2.b imposes a leakage limit of 5 gpm of unidentified leakage.Conservatively assuming an empty DWFDS and a minimum, immediate increase in unidentified leak rate of 5 gpm the DWFDS would fill up to approximately 550 gallons and begin to overflow to the DWEDS in 1.83 hours9.606481e-4 days 0.0231 hours 1.372354e-4 weeks 3.15815e-5 months .As stated above in Section 3.1 of this Attachment, the level switches will detecta2 gpm change in leak rates in the DWEDS and provide an alarm in the main control room.This amount of time is less than the TS Completion Time for TS 3.4.3.2, Action B which reduces unidentified leakage rate to within limits in 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months and the completion time for TS 3.4.3.1 , Action B which restores the drywell sump monitoring system to Operable status within 30 days.Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 5 of 10 installed DWEDS in the situation that the DWFDS is inoperable and the DWEDS is operable.In this situation the inoperable DWFDS would overflow into the DWEDS which would be capable of quantifying total RCS leakage (Le., unidentified plus identified leakage).The resultant value of total RCS leakage would be conservatively verified to be less than the TS 3.4.3.2.b unidentified leakage limit of 5 gpm and TS 3.4.3.2.1 unidentified leakage increase limit of 2 gpm within the previous 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .3.3 RCS Leakage Detection While Filling the DWFDS LGS TS SR 4.4.3.2.1.b requires the verification every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that RCS leakage measured by the DWFDS and DWEDS is within the specified limits of TS 3.4.3.2 (unidentified leakage to be less than or equal to 5 gpm and the increase in unidentified leakage within the previous 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to be less than 2 gpm).As described above, after the DWFDS begins overflowing into the DWEDS, the DWEDS can be used to measure total leakage (Le., unidentified plus identified leakage).Overflow into the DWEDS was determined by an engineering evaluation tooccurafter accumulation of approximately 550 gallons in the DWFDS.In order for the DWFDS to overflow into the DWEDS, LGS personnel would either have to manually fill the DWFDS with an external water source or allow unidentified RCS leakage to fill the DWFDS.The use of unidentified RCS leakage to fill the DWFDS at or above 550 gallons in an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months time period would require: 1.A minimum unidentified leakage rate of approximately 1.14gpm,and 2.The regulatory commitments delineated in this submittal for LGS, Units 1 and 2 (Le., verification of flow from the DWFDS to the DWEDS, prior to the initial use of the alternate monitoring method for a specific unit)have been satisfied.

The minimum unidentified leakage rate of approximately 1.14 gpm is based on the leakage rate required to fill approximately 550 gallons in the DWFDS in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months .The 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months period represents the TS-required surveillance interval as specified in SR 4.4.3.2.1.b but does not included the additional 25%grace, or 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , allowed by SR 4.0.2.This minimum leakage rate 1.14 gpm would cause the DWFDS to overflow into the DWEDS within the required SR 4.4.3.2.1.b interval.TS 3.4.3.2.1 requires that a'2 gpm increase in unidentified leakage over a 24-hour period is able to be detected.Conservatively assuming an empty DWFDS and a minimum, immediate increase in unidentified leak rate of 2 gpm the DWFDS would fill up to approximately 550 gallons and begin to overflow to the DWEDS in 4.6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .As stated above in Section 3.1 of this Attachment, the level switches will detecta2 gpm change in leak rates in the DWEDS and provide an alarm in the main control room.This meets the TS 3.4.3.2.1 requirement to detect a 2 gpm increase in unidentified leakage over a 24-hour period.TS 3.4.3.2.b imposes a leakage limit of 5 gpm of unidentified leakage.Conservatively assuming an empty DWFDS and a minimum, immediate increase in unidentified leak rate of 5 gpm the DWFDS would fill up to approximately 550 gallons and begin to overflow to the DWEDS in 1.83 hours9.606481e-4 days 0.0231 hours 1.372354e-4 weeks 3.15815e-5 months .As stated above in Section 3.1 of this Attachment, the level switches will detecta2 gpm change in leak rates in the DWEDS and provide an alarm in the main control room.This amount of time is less than the TS Completion Time for TS 3.4.3.2, Action B which reduces unidentified leakage rate to within limits in 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months and the completion time for TS 3.4.3.1 , Action B which restores the drywell sump monitoring system to Operable status within 30 days.

Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 6 of 10 Therefore, depending upon the specific operational circumstances, filling of the DWFDS and ensuring flow from the DWFDS to the DWEDS would be established either manually with an external water source, or remotely, using the existing unidentified RCS leakage.In both circumstances the TS SR and TS Requirements in TS SR 3.4.3.2.1 and TS 3.4.3.2 will be met within the allotted completion times.3.4 Summary By allowing the drywell floor drain sump to overflow into the drywell equipment drain sump, Operations personnel are not able to differentiate between the identified and unidentified leakage inputs.As such, all leakage in the drywell sumps will be conservatively treated asunidentifiedleakage in accordance with the TS 3.4.3.2 limits.Ensuring flow from the DWFDS to the DWEDS would be established either manually with an external water source, or remotely, using the existing unidentified RCS leakage.In both circumstances the TS SR and TS Requirements in TS SR 3.4.3.2.1 and TS 3.4.3.2 will be met within the allotted completion times.Therefore, the addition of an alternative method to quantify unidentified leakage in the drywell is conservative with respect to the current TS limits.

4.0 REGULATORY EVALUATION

4.1 Applicable

Regulatory Requirements

/Criteria LGS Units 1 and 2 were originally designed and constructed following the issuance of the General Design Criteria (GDC).The GDC proposed criteria were adopted as regulatory requirements at both LGS Units.Details regarding the reactor coolant system leakage detection systems are provided in UFSAR Section 5.2.5,11 Reactor Coolant Pressure Boundary Leak Detection System.1I One of the leakage detection systems discussed is the drywell sumps (Le., DWFDS and DWEDS).The UFSAR states that various leak detection systems and capabilities collectively detect reactor coolant pressure boundary leakage, both identified and unidentified.

These indications and alarms are provided in accordance with Regulatory Guide 1.45.The proposed change does not involve physical changes to the RCS leakage detection systems.Rather, the proposed change allows use of the drywell equipment drain monitoring system to perform the function of the drywell floor drain monitoring system in quantifying unidentified leakage within the LGS Units 1 and 2 drywells.The design function of the RCS leakage detection systems is not affected by the proposed change.In addition, the alternative method conservatively assumes that all leakage in the drywell is unidentified leakage.Therefore, there is no impact to EGC's ability to meet the applicable regulatory requirements discussed above.4.2 Precedent The proposed alternate method has been incorporated into the TSs for the Monticello Nuclear Generating Plant (References 6.10 and 6.11), the Peach Bottom Atomic Power Station, Unit 2 and Unit 3 (References 6.12 and 6.13).In addition, the NRC has previously approved similar Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 6 of 10 Therefore, depending upon the specific operational circumstances, filling of the DWFDS and ensuring flow from the DWFDS to the DWEDS would be established either manually with an external water source, or remotely, using the existing unidentified RCS leakage.In both circumstances the TS SR and TS Requirements in TS SR 3.4.3.2.1 and TS 3.4.3.2 will be met within the allotted completion times.3.4 Summary By allowing the drywell floor drain sump to overflow into the drywell equipment drain sump, Operations personnel are not able to differentiate between the identified and unidentified leakage inputs.As such, all leakage in the drywell sumps will be conservatively treated asunidentifiedleakage in accordance with the TS 3.4.3.2 limits.Ensuring flow from the DWFDS to the DWEDS would be established either manually with an external water source, or remotely, using the existing unidentified RCS leakage.In both circumstances the TS SR and TS Requirements in TS SR 3.4.3.2.1 and TS 3.4.3.2 will be met within the allotted completion times.Therefore, the addition of an alternative method to quantify unidentified leakage in the drywell is conservative with respect to the current TS limits.

4.0 REGULATORY EVALUATION

4.1 Applicable

Regulatory Requirements

/Criteria LGS Units 1 and 2 were originally designed and constructed following the issuance of the General Design Criteria (GDC).The GDC proposed criteria were adopted as regulatory requirements at both LGS Units.Details regarding the reactor coolant system leakage detection systems are provided in UFSAR Section 5.2.5,11 Reactor Coolant Pressure Boundary Leak Detection System.1I One of the leakage detection systems discussed is the drywell sumps (Le., DWFDS and DWEDS).The UFSAR states that various leak detection systems and capabilities collectively detect reactor coolant pressure boundary leakage, both identified and unidentified.

These indications and alarms are provided in accordance with Regulatory Guide 1.45.The proposed change does not involve physical changes to the RCS leakage detection systems.Rather, the proposed change allows use of the drywell equipment drain monitoring system to perform the function of the drywell floor drain monitoring system in quantifying unidentified leakage within the LGS Units 1 and 2 drywells.The design function of the RCS leakage detection systems is not affected by the proposed change.In addition, the alternative method conservatively assumes that all leakage in the drywell is unidentified leakage.Therefore, there is no impact to EGC's ability to meet the applicable regulatory requirements discussed above.4.2 Precedent The proposed alternate method has been incorporated into the TSs for the Monticello Nuclear Generating Plant (References 6.10 and 6.11), the Peach Bottom Atomic Power Station, Unit 2 and Unit 3 (References 6.12 and 6.13).In addition, the NRC has previously approved similar Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 7 of 10 amendment requests to the TS for Dresden Nuclear Power Station, Units 2 and 3 and Quad Cities Nuclear Power Station, Units 1 and 2 (References 6.1 and 6.3).The subject license amendment request proposes to adopt revisions consistent with those proposed in the previously approved amendments.

4.3 No Significant Hazards Consideration In accordance with 10 CFR 50.90,"Application for amendment of license, construction permit, or early site permit, II Exelon Generation Company, LLC (EGC)requests an amendment to Facility Operating License Nos.NPF-39 and NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, respectively.

Specifically, the proposed change revises the Technical Specifications (TS)to support implementation of an alternative method of verifying that leakage intothedrywell floor drain sump is within limits.The alternative method involves use of the installed drywell equipment drain sump monitoring system to quantify unidentified leakage in the drywell.EGC has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92,"lssuance of amendment, II as discussed below: (1)Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.The proposed change does not involve physical changes to any plant structure, system, or component.

As a result, no new failure modes of the Reactor Coolant System (RCS)leakage detection systems are being introduced.

Additionally, the RCS leakage detection systems have no impact on any initiating event frequency.

The consequences of a previously analyzed accident are dependent on the initial conditions assumed for the analysis, the behavior of the fuel during the analyzed accident, the availability andsuccessfulfunctioning of the equipment assumed to operate in response to the analyzed event, and the setpoints at which these actions are initiated.

The ReS leakage detection systems do not perform an accident mitigating function.Emergency Core Cooling System, Reactor Protection System, and primary and secondary containment isolation actuations are not affected by the proposed change.The proposed change has no impact on any setpoints or functions related to these actuations.

There are no changes inthetypes or significant increase in the amounts of any effluents released offsite.Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

(2)Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.The proposed change allows use of the drywell equipment drain system as an alternative method of quantifying unidentified leakage in the drywell.The drywell Alternate Method of Verifying Drywell Unidentified Leakage Attachment 1: Evaluation of Proposed Changes Page 7 of 10 amendment requests to the TS for Dresden Nuclear Power Station, Units 2 and 3 and Quad Cities Nuclear Power Station, Units 1 and 2 (References 6.1 and 6.3).The subject license amendment request proposes to adopt revisions consistent with those proposed in the previously approved amendments.