ML101790114

License Amendment Request for Non-Conservative Technical Specification Associated with the Amount of Liquid Nitrogen Storage

ML101790114
Person / Time
Site:	Peach Bottom
Issue date:	06/25/2010
From:	Cowan P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML101790114 (25)

Text

Exelon Nudear Exelon Nuclear www.exeloncorp.com www.exeloncorp.com Exeln.

Exelon ExelonWay 200Exelon 200 Way Nuclear Nuclear KennettSquare, Kennett Square.PA PA19348 19348 OCFR5O.90 110CFR50.90 June 25, June 25, 2010 2010 U.S. Nuclear U.S. Nuclear Regulatory Regulatory Commission Commission ATIN:

ATTN: Document Document Control Control Desk Desk Washington, Washington, DC DC 20555-0001 20555-0001 Peach Bottom Peach Bottom Atomic Atomic PowerPower Station, Units 22 and Station, Units and 33 Facility Operating Renewed Facility Operating License Nos. DPR-44 License Nos. DPA-44 and and DPR-56 DPR-56 Docket Nos.

Docket Nos. 50-277 50-277 and and 50-278 50-278

Subject:

License Amendment Request for Non-Conservative Technical Technical Specification Specification Associated with the Amount of Liquid Nitrogen Storage Storage In In accordance accordance with 10 CFR 50.90, Application lIApplication for amendment of license or construction permit, Exelon Generation Company, LLC (Exelon) requests amendments to the Technical permit,"

Specifications (TS), Appendix A of Renewed Facility Operating License Nos. DPR-44 and DPR Specifications DPR-56 for Peach 56 for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed amendments would revise the TS and associated Bases for PBAPS, Units 2 and The proposed 3,

3, to address non-conservative TS Surveillance Requirements (SRs) associated with the to address '

amount amount of of nitrogen nitrogen available in the liquid nitrogen nitrogen storage tank to support operation of the Primary Primary Containment Containment IsolationIsolation Valves (PCIVs) and Reactor Building-to-Suppression Chamber Chamber Vacuum Vacuum Breakers Breakers by'the bythe Safety Safety Grade Instrument Gas ($GIG)

Grade Instrument (SGIG) system. The liquid nitrogen storage tank storage tank is is common common to to both both PBAPS PBAPS units.

units. Exelon Exelon determined that the amount of nitrogennitrogen needed in the liquid needed in the liquid nitrogennitrogen storage storage tank tank as as described described in in TS SR 3.6.1.3.1 and SR 3.6.1.5.1 3.6.1.5.1 was was non-conservative non-conservative based based on on newly derived system newly derived system design leakage.

design leakage.

Currently, Currently, TS TS SR SR 3.6.1.3.1 3.6.1.3.1 andand SR 3.6.1.5.1 specify SR 3.6.1.5.1 specify that the liquid that the nitrogen storage tank is to be liquid nitrogen be maintained maintained at level ~ 16 at aa level 16 inches inches water re-analysis of column. AA re-analysis water column. of th,e amount of the amount leakage design leakage of design associated associated with with the the SGIG SGIG system, system, which which is is based based on on empirical empirical data, data, indicates indicates the the liquid liquid nitrogen nitrogen storage tank should storage tank should be be maintained maintained at at ~ 22 22 inches inches water water column, column, or or equivalent equivalent volume volume of>

of ~

124,000 124,000 standard standard cubic cubic feet feet (set)

(scf) at at 250 psig, to satisfy TS SR 3.6.1.3.1 250 psig, to satisfy TS SA 3.6.1.3.1 and SR 3.6.1.5.1. and SR 3.6.1.5.1.

Therefore, Therefore, the the current current TS TS value value ofof ~ 16 inches water 16 inches non-conservative and column isis non-conservative water column requires and requires revision. InIn accordance revision. accordance with with NRC Administrative Letter NRC Administrative Dispositioning of 98-10, "Oispositioning Letter 98-10, Technical of Technical Specifications That Specifications That Are Are Insufficient Insufficient to to Assure Assure Plant Plant Safety, Safety, " Exelon Exelon has has implemented implemented administrative administrative controls controls to to ensure ensure the liquid nitrogen the liquid storage tank nitrogen storage volume isis ~> 22 tank volume water inches water 22 inches column column to to satisfy satisfy SR SR 3.6.1.3.1 3.6.1.3.1 andand SR 3.6.1.5.1.

SR 3.6.1.5.1.

Attachment Attachment 11 provides provides an evaluation of an evaluation proposed TS the proposed of the changes to TS changes to address address the non the non-conservative conservative TS TS SR SR values associated with values associated with the amount of the amount nitrogen available of nitrogen liquid the liquid available inin the nitrogen storage nitrogen storage tank. tank. Attachment Attachment 2 2 contains contains the the TS TS page page mark-ups mark-ups for for the the proposed proposed TS TS changes.

changes. Attachment Attachment33contains containsthe mark-ups for the associated the mark-ups for the associated TS Bases pages for TS Bases pages for information informationonly. only.

u.s.

U.S. Nuclear Nuclear Regulatory Commission License License Amendment Request SGIG System Non-Conservative TS Docket Docket Nos. 50-277 and 50-278 June 25, 2010 Page 2 Page proposed changes have been reviewed by the Plant Operations Review Committee and The proposed approved by the Nuclear Safety Review Board in accordance with the requirements of the Exelon Quality Assurance Program.

Exelon requests approval of the proposed amendments by June 25, 2011. Once approved, the amendments shall be implemented within 60 days.

There are no regulatory commitments contained in this submittal.

50.91(b)(1),

Pursuant to 10 CFR 50.91 (b)(1), a copy of this License Amendment Request is being provided to the designated official of the Commonwealth of Pennsylvania.

Should you have any questions concerning this submittal, please contact Mr. Richard Gropp at (610) 765-5557.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 25th day of June 2010.

Respectfully, Id,C'lt ~

Pamela B. Cowan Director - Licensing and Regulatory Affairs Exelon Generation Company, LLC Attachments: 11 - Evaluation of Proposed Changes 2 - Mark-ups of Technical Specification Pages 3 - Mark-ups of Technical Specification Bases Pages (For Information Only) cc: S. J. Collins, Administrator, Region I, USNRC F. L. Bower, USNRC Senior Resident Inspector, PBAPS J. Hughey, Project Manager, USNRC R. R. Janati, Commonwealth of Pennsylvania S. Gray, State of Maryland

ATTACHMENT 1 1 Evaluation of Proposed Changes PBAPS, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 Technical Specifications Changes to Address Non-Conservative "Technical Surveillance Requirement Value for Safety Grade Instrument Gas (SGIG) System Storage Nitrogen Storage" 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

5.0 REGULATORY EVALUATION

5.1 No Significant Hazards Consideration (NSHC) 5.2 Applicable Regulatory Requirements 5.3 Conclusion

7.0 REFERENCES

ATTACHMENT 1 1 Evaluation of Proposed Changes Page 1 1 of 8 1.0

SUMMARY

DESCRIPTION Exelon Generation Company, LLC, (Exelon) is requesting amendments to the Technical Specifications (TS), Appendix A, of Renewed Facility Operating License Nos. DPR-44 and DPR-56 for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

Exelon has determined that the current PBAPS, Units 2 and 3, TS value for nitrogen nitrogen available in the liquid nitrogen storage tank to support operation of the Primary Containment Isolation Valves (PCIVs) and Reactor Building-to-Suppression Chamber Vacuum Breakers by the Safety Grade Instrument Gas (SGIG) system is non non-conservative based on newly derived system leakage values. Therefore, the guidance "Dispositioning of of Nuclear Regulatory Commission (NRC) Administrative Letter 98-10, Dispositioning Safety," applies. Exelon Technical Specifications That Are Insufficient to Assure Plant Safety, has implemented administrative controls to maintain the amount of nitrogen in the liquid nitrogen storage tank at a level of ~ 22 inches water column in support of SGIG system operation, and is submitting this License Amendment Request (LAR) to address this non-conservative TS condition. This proposed change would revise TS Surveillance Requirement (SR) 3.6.1.3.1 and SR 3.6.1.5.1 to require the minimum amount of nitrogen inventory in the liquid nitrogen storage tank be maintained at ~ 22 inches water column, not the currently stated level of ~ 16 inches water column. The methodology for determining the minimum required inventory is discussed in Section 4.0 of this submittal.

2.0 DETAILED DESCRIPTION Currently, the TS SR 3.6.1.3.1 and SR 3.6.1.5.1 specify that the liquid nitrogen storage tank be maintained at a level of ~ 16 inches water column to support the operation of the PCI Vs and Reactor Building-to-Suppression Chamber Vacuum Breakers. Specifically, PCIVs the current TS SRs require the following:

SURVEILLANCE FREQUENCY SR 3.6.1.3.1 Verify Containment Atmospheric Dilution 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (CAD) System liquid nitrogen storage tank is 16 inches water column.

level is.2:

SURVEILLANCE FREQUENCY 3.6. 1.5.1 SR 3.6.1.5.1 Verify Containment Atmospheric Dilution 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (CAD) System nitrogen storage tank level is

> 16 inches water column.

.2:

These TS SRs verify that the level in the liquid nitrogen storage tank is sufficient to ensure at least seven days of post Loss of Coolant Accident (LOCA) operation for the PCI Vs and Reactor Building-to-Suppression Chamber Vacuum Breakers.

PCIVs The proposed TS change would revise TS SR 3.6.1.3.1 and TS SR 3.6.1.5.1 to increase the minimum level in the liquid nitrogen storage tank from ~ 16 inches water column to ~

22 inches water column or equivalent volume of ~ 124,000 scf at 250 psig. The SR will

ATTACHMENT 1 1 Evaluation of Proposed Changes Page 2 of 8 only have reference to the required level in the liquid nitrogen storage tank, and the calculated equivalent inventory will be maintained in the TS Bases. The proposed TS changes are as follows:

SURVEILLANCE FREQUENCY SR 3.6. 1.3. 1 3.6.1.3.1 Verify nitrogen inventory is equivalent to ,~ 22 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> inches water column in the liquid nitrogen storage tank.

SURVEILLANCE FREQUENCY SR 3.6. 1.5. 1 3.6.1.5.1 ~ 22 Verify nitrogen inventory is equivalent to ? 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> inches water column in the liquid nitrogen storage tank.

3.0 BACKGROUND

Following a Design Basis Accident (DBA) LOCA coincident with a loss of instrument air, the SGIG system supplies pressurized nitrogen gas as a backup pneumatic source to the Containment Atmospheric Control (CAC) purge and vent isolation valves, Reactor Building-to-Suppression Chamber Vacuum Breakers, and the Containment Atmospheric Dilution (CAD) system vent control valves. Nitrogen for the SGIG system is supplied from a 6000-gallon liquid storage tank which is common to both units. The SGIG system performs three distinct post-LOCA functions: (1) supports the containment vacuum relief function, (2) supports primary containment isolation for PCIVs, and (3) supports control of containment atmosphere via the CAD system. SGIG system requirements are addressed for each of the supported systems and components in Limiting Condition for (PCIVs)," and LCO Primary Containment Isolation Valves (PCIVs),

Operation (LCO) 3.6.1.3, "Primary 3.6.1.5, "Reactor Reactor Building-to-Suppression Chamber Vacuum Breakers.

Breakers."

To support SGIG system operation, the liquid nitrogen storage tank minimum required level is currently required to be maintained at ~ 16 inches water column in accordance with TS SR 3.6.1.3.1 and SR 3.6.1.5.1. Exelon has implemented administrative controls to maintain the amount of nitrogen in the liquid nitrogen storage tank at a level of ~ 22 inches water column in support of SGIG system operation based on a revised analysis of system losses.

4.0 TECHNICAL EVALUATION

A non-conservative TS condition was identified based on SGIG system leakage being found in excess of that previously assumed. As a result, the value of of>~ 16 inches water column currently specified in TS SR 3.6.1.3.1 for the PCI Vs PCIVs and TS SR 3.6.1.5.1 for Reactor Building-to-Suppression Chamber Vacuum Breakers is non-conservative.

Reactor 3.6.1.3.1 and TS SR 3.6.1.5.1 currently require a minimum of 1 TS SR 3.6.1.3.1 TS ~ 166 inches water column of nitrogen in the liquid nitrogen storage tank to ensure PCIV and Reactor Building-to-Suppression Chamber Vacuum Breaker operability. This value is based on the tank having a 7-day supply of nitrogen assuming that one unit is in post-LOCA and

ATIACHMENT ATTACHMENT 11 Evaluation of Proposed Changes Page 3 of 8 the other unit is in Safe Shutdown. SGIG system inoperability due to insufficient tank inventory would affect both units' units containment ventilation PCI PCIVs Vs (TS 3.6.1.3) and Reactor Building-to-Suppression Chamber Vacuum Breakers (TS 3.6.1.5).

Current Analysis nitrogen is The current analysis specifies that a total of approximately 50,000 scf of nitrogen required for the operation of the SGIG system under design bases conditions. This amount of nitrogen (which includes a 25% 49,905 scf) is 25% margin and rounded up from 49,905 is required for seven days of post-accident SGIG system operation, which supports PCIV and Reactor Building-to-Suppression Chamber Vacuum Breaker functions. The 25% 25%

margin amounts to 9,981 scf over the 7-day period which may be considered available to compensate for leakage losses.

The table below shows the current TS values for nitrogen capacity needed in the liquid nitrogen storage tank.

Current Requirements - Liquid Nitrogen Storage Tank Capacity Nitroqen Storaqe TS Requirements Inches water column TS SR 3.6.1.3.1 ~16 16 TS SR 3.6.1.5.1 ~16 16 Upgraded Uraded Analysis An updated daily leakage estimate has been derived based on actual historical plant data. This leakage exceeds the assumed leakage that was the basis for the current allowed value.

Each fill cycle in the analyzed historical time period was identified and the difference in volume of nitrogen in the liquid nitrogen storage tank on a 24-hour interval was Operations rounds data points. Using this data, the amount of calculated based on Operations' nitrogen operationally evacuated from the liquid nitrogen storage tank per fill cycle was calculated. The amount of nitrogen evacuated from the tank was subtracted by the amount consumed to yield the estimated leakage.

Since the liquid nitrogen storage tank is required to provide seven days of post-LOCA operation, a 7-day rolling leakage total was calculated. Within each fill cycle, an average and maximum 7-day rolling leakage total was used to determine the updated assumed leakage.

This leakage value (total combined for both units) is assumed to exist for seven days.

The maximum operating 7-day leakage was 74,917 scf with an average operating 7-day leakage of 53,498 scf. An assumed maximum leakage of 80,422 scf was selected to bound the maximum 7-day leakage by approximately 5500 scf, or 7% 7% of the maximum operating 7-day leakage. When the assumed maximum leakage is combined with the required amount of nitrogen for seven days of post-LOCA SGIG operation, the total

ATIACHMENT 1 ATTACHMENT 1 Evaluation of Proposed Changes Page 4 of 8 SGIG inventory required is 120,000 120,000 scf. An operational required amount of 22 22 inches inches water column in the liquid nitrogen storage tank, or an equivalent volume of 124,000 124,000 scf at 250 psig was selected to provide a margin of 4000 scf above the total SGIG SGIG demand. demand.

The following table provides a summary of the different values utilized: utilized:

Total Demand for Dual Unit Operation Source Volume (scf) (scf) f-J..L~§~"I~ . _.~.~.c?g~_.f9 . r.Z~Q.C!Y~~9f . e9§)!:.hOQ.~~9 e_~!~.~g.O~ __._~_. __._~~." . ___.~_._~.~ __~_ . _ r ,

~§)l.§Z.~ __._ _ .

_..39,578

. . ?2)1~y~r~g.~ ge. 9p~r~!iQgg..7.:.Q~y.J~~.k~g~...

7-day eakage . . 5.3 A 98 .

§~'.4§J..~

. ~l

3) M~~i.~~.r.D.Qp.~r~~iQg Maxim urn Ope rating7-day ..?~.q.~y . I~~k~g~.kage . . .7.4.,9.17.

.4 917 .

.4t.~~.~~I'lJ~.q.M.~?5!.~

4) Assumed Maximum . ~~..7.:Q.~y b.~.~.k~.g.~...

-day ..Leakage . .

~.Q,.4?? .

. 80,422

5) Total SGIG Inventory Required for 7-day Post LOCA 120 000 12 00 r-.._..-~.._.." _~-_.._~._~ .._.._._._." __.__ _~ __._ --" _._._._-~_.~ .._..~ __.._--_ __ __.._ _ ..- .."._~ _._~ __._i11+/-t4}_=:_

_._-_..__..~~._ ~. _:. ._._._._ _.._~. _.

6) Operational Required Inventory for SGIG (22 (22" water 124 000 124 000

.. 99!~I'lJQ1~t?§.Qp~ig co urn n) a 25Op !g ,

7) Margin above Total SGIG Inventory Required 44,000 000

. . ~ .(~J:(§.t=

(6)-(5)= ~....... .

8) Margin above SGIG demand with maximum 7-day leakage 9 505 9 505

_~_.__.._ __.~~~_~~ __._~ _ .

. ~~" _.~ __~~~._. ~__..__."._._ __ ~ .~_ _._ _._._ _ ..._J):tU

_ (~1:il11+/-t~}1= )).) _ ___..~~.,.__ __ _

9) Margin above SGIG demand with average 7-day leakage 30924 4 v,

(6}-<<1 }+(2)}=

(6)-((1)+(2))= '

In order to support operation of the PCIVs PCI Vs and Reactor Building-to-Suppression Chamber Vacuum Breakers, a minimum amount of liquid nitrogen must be maintained in the liquid nitrogen storage tank. This level is currently established in TS at ~ 16 inches water column. This new analysis, which utilizes system leakage based on operational data, determined that the amount of nitrogen in the liquid nitrogen storage tank should be maintained at a level of ~ 22 inches water column, or equivalent volume of> of ~ 124,000 124,000 scf at 250 psig. The proposed TS changes would revise TS SR 3.6.1.3.1 and TS SR 3.6.1.5.1 to increase the minimum level in the liquid nitrogen storage tank from ~ 16 3.6.1.5.1 inches water column to ~ > 22 inches water column, for ensuring operability of the PCIVs PCI Vs and Reactor Building-to-Suppression Chamber Vacuum Breakers. As previously stated, a level of ~ 22 inches water column in the liquid nitrogen storage tank would be equivalent to a volume of ~ 124,000 scf at 250 psig.

ItIt is is desired desired that the TS allow for two equal measurements of nitrogen inventory (Le., (i.e.,

liquid nitrogen nitrogen storage tank level or the equivalent standard volume of nitrogen). This clearly states the level of liquid nitrogen required in the TS, while giving flexibility for temporary modifications that require use of an auxiliary source, provided technical equivalency equivalency of the vessel and the required minimum inventory is monitored and maintained.

maintained.

ATIACHMENT ATTACHMENT 11 Evaluation of Proposed Changes Page 5 of 8

5.0 REGULATORY EVALUATION

5.1 No Significant Hazards Consideration (NSHC)

In accordance with 10 CFR 50.90, It,4pplication Application for amendment of license or construction permit,"

permit, Exelon Generation Company, LLC (Exelon) requests the following amendments to Appendix A, Technical Specifications (TS), of Renewed Facility Operating License Nos. DPR-44 and DPR-56 for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3. The proposed amendments would revise the PBAPS, Units 2 and 3, TS Surveillance Requirements (SRs) to address a non-conservative value associated with the amount of nitrogen available in the liquid nitrogen storage tank to support operation of the Primary Containment Isolation Valves (PCIVs) and Reactor Building-to-Suppression Chamber Vacuum Breakers by the Safety Grade Instrument Gas (SGIG) system.

The proposed TS changes would revise TS SR 3.6.1.3.1 and TS SR 3.6.1.5.1 to increase the minimum level in the liquid nitrogen storage tank from ~ 16 16 inches water column to a level of ~ 22 inches water column. A level of ~ > 22 inches water column in the liquid nitrogen storage tank would be an equivalent volume of ~ 124,000 124,000 scf at 250 psig.

According to 10 CFR 50.92, IIlssuance Issuance of amendment,"

amendment, paragraph (c), a proposed amendment to an operating license involves no significant hazards consideration if operation of the facility in accordance with the proposed amendments would not:

(1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involve a significant reduction in a margin of safety.

In support of this determination, Exelon has evaluated whether or not a significant hazards consideration is involved with the proposed amendments by focusing on the Issuance of amendment, three standards set forth in 10 CFR 50.92, IIlssuance amendment,"as as discussed below:

1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed TS changes to increase the level in the liquid nitrogen storage tank from ~ 16 inches water column to a level of ~ > 22 inches water column, or equivalent volume ofof>

~ 124,000 scf at 250 psig, is necessary in order to correct a non non-conservative TS value. Increasing the level is intended to ensure continued operability of the PCIVs (SR 3.6.1.3.1) and Reactor Building-to-Suppression Chamber Vacuum Breakers (SR 3.6.1.5.1) via the SGIG system. The non-

ATIACHMENT 1 ATTACHMENT 1 Evaluation of Proposed Changes Page 6 of 8 conservative TS condition was identified based on aa re-analysis of of the liquid liquid nitrogen nitrogen storage tank operation. The leakage allowance that was previously assumed assumed was was not based on a rigorous empirical value. The re-analysis of the leakage leakage allowance allowance assumes more reasonable system leakage based on operational data. Exelon has data. Exelon has determined that the current PBAPS, Units 2 and 3, TS SR value for the minimum minimum level in the liquid nitrogen storage tank of ~ 1616 inches water column is is non non-Commission (NRC) conservative and that the guidance of Nuclear Regulatory Commission (NRC)

Administrative Letter 98-10, Dispositioning IIDispositioning of Technical Specifications that are Insufficient to Assure Plant Safety," applies. Exelon has Safety,applies. has implemented implemented administrative administrative controls to maintain the amount of nitrogen in the liquid nitrogen storage tank at at a level of ~

> 22 inches water column in support of SGIG system operation.

Exelon is submitting this License Amendment Request to address this non non-conservative condition. The proposed TS changes do not introduce new equipment or new equipment operating modes, nor do the proposed changes alter existing system relationships. The proposed changes do not affect plant operation, design function or any analysis that verifies the capability of a system, structure or component (SSC) to perform a design function. Further, the proposed changes do not increase the likelihood of the malfunction of any SSC or impact any analyzed accident. Consequently, the probability or consequences of an accident previously evaluated are not affected.

Therefore, the proposed amendments do not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed TS change to increase the level in the liquid nitrogen storage tank from ~ 16 inches water column to a level of ~ > 22 inches water column, or equivalent volume of of>~ 124,000 scf at 250 psig, for the PCI Vs (SR 3.6.1.3.1) and Reactor PCIVs Building-to-Suppression Chamber Vacuum Breakers (SR 3.6.1.5.1) is needed to correct a non-conservative value based on a revised analysis. The proposed TS changes do not alter the design function or operation of any SSC. There is no new system component being installed, no construction of a new facility, and no performance of a new test or maintenance function. The proposed TS changes do not create the possibility of a new credible failure mechanism or malfunction. The proposed changes do not modify the design function or operation of any SSC.

proposed Further, the proposed changes do not introduce new accident initiators.

Further, Consequently, the proposed changes cannot create the possibility of a new or Consequently, different kind different kind of accident from any accident previously evaluated.

Therefore, the Therefore, the proposed amendments do not create the possibility of a new or kind of accident from any accident previously analyzed.

different kind different

ATIACHMENT ATTACHMENT 11 Evaluation of Proposed Changes Page 7 of 8

3. Does the proposed amendment involve a significant reduction in aa margin of of safety?

Response: No.

The proposed TS changes to increase the level in the liquid nitrogen storage tank from ~ 16 inches water column to a level of ~ > 22 inches water column, or equivalent volume of ~ 124,000 scf at 250 psig, for the PCI PCIVs Vs (SR 3.6.1.3.1) and Reactor Building-to-Suppression Chamber Vacuum Breakers (SR 3.6.1.5.1) are necessary to correct an existing non-conservative TS value. The proposed TS changes are needed based on a revised analysis that utilizes empirical data for nitrogen system uses and losses. The proposed changes do not exceed or alter a design basis or a safety limit for a parameter established in the PBAPS, Units 2 and 3, Updated Final Safety Analysis Report (UFSAR) or the PBAPS, Units 2 and 3, Renewed Facility Operating License (FOL). Consequently, the proposed changes do not result in a reduction in the margin of safety.

Therefore, the proposed amendments do not involve a significant reduction in a margin of safety.

5.2 Applicable Regulatory Requlatorv Requirements Exelon reviewed the proposed TS changes against the regulatory requirements listed below to ensure that there is reasonable assurance that the SGIG system will continue to function as designed.

50.36(c)(1)(ii)(A) 10 CFR 50.36(c)(1 Limiting safety system settings for nuclear reactors are

)(ii)(A) states: "Limiting settings for automatic protective devices related to those variables having significant safety functions. Where a limiting safety system setting [LSSS] is specified for a variable on which a safety limit has been placed, the setting must be so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded.

exceeded."

10 CFR 50.36(c)(3), "Surveillance Suiveillance requirements, are requirements relating to test, requirements,"are calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.

As discussed above, the proposed TS changes would revise TS SR 3.6.1.3.1 and TS SR 3.6.1.5.1 to establish a minimum level in the liquid nitrogen storage tank of ~ 22 inches water column, rather than a level of inches of>~ 16 inches water column which is currently stipulated. A level of ~ 22 inches water column in the liquid nitrogen storage tank would be an equivalent volume of ~ 124,000 scf at 250 psig. The proposed TS changes are necessary to correct a non-conservative TS value that was determined based on revised leakage analysis for the SGIG system. The proposed TS changes will ensure that a sufficient volume of nitrogen is available to support SGIG system operation. The proposed TS changes do not involve a change to an LSSS as specified in 10 CFR 50.36(c)(1 )(ii)(A).

ATTACHMENT 1 1 Evaluation of Proposed Changes Page 8 of 8 5.3 Conclusion assurance that Based on the considerations discussed above: (1) there is reasonable assurance that the health and safety of the public will not be endangered endangered by operation inin the proposed proposed Commission's manner, (2) such activities will be conducted in compliance with the Commissions inimical to the common regulations, and (3) the issuance of the amendment will not be inimical common defense and security or to the health and safety of the public.

6.0 ENVIRONMENTAL CONSIDERATION

A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 1010 CFR 51 .22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement 51.22(c)(9).

or environmental assessment need be prepared in connection with the proposed amendment.

7.0 REFERENCES

Dispositioning of Technical Specifications That

1. NRC Administrative Letter 98-10, "Dispositioning Safety Are Insufficient to Assure Plant Safety"

ATTACHMENT 2 Markups of Technical Specifications Pages PBAPS, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 REVISED TECHNICAL SPECIFICATIONS PAGES Unit2 Unit 2 Unit3 Unit 3 3.6-12 3.6-12 3.6-19 3.6-19

PCIVs PCIVs 3.6.1.3 3.6.1.3 ACTIONS (continued)

(conti nued)

CONDITION REQUIRED ACTION COMPLETION TIME E. Purge/Vent flowpath E.1 Isolate the 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> open for an penetration.

accumulated time greater than 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> OR Q

for the calendar year while in MODE 11 or 2 E.2.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> with Reactor Pressure greater than 100 psig. AND E.2.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> F. Required Action and F.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time of Condition A, AND B, C, or DD not met in MODE 1, 2, or 3. F.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> G. Required Action and G.1 Initiate action to Immediately associated Completion suspend operations Time of Condition A, with a potential for B, C, or DD not met draining the reactor for PCIV(s) required vessel.

to be OPERABLE during MODE 4 or 5.

MODE40r5. OR G.2 Initiate action to Immediately restore valve(s) to OPERABLE status.

SURVEILLANCE REQUIREMENTS SURVEILLANCE_REQUIREMENTS SURVEILLANCE SURVEI LLANCE FREQUENCY SR 3.6.1.3.1 Verify Containment Atmospheric Dilution 24 hhours ours (CAD) System liquid nitrogen inventory storage tanl(

tank 1evel level is equi val ent to ~ 46 equivalent 4 22 inches water column in the liquid nitrogen storage tank.

SR 3.6.1.3.2 Verify Safety Grade Instrument Gas (SGIG) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> System header pressure is ~ 80 psig.

(continued)

(conti nued)

PBAPS UNIT 2 3.6-12 269XXX Amendment No. -9XXX

Reactor Building-to-Suppression Chamber Vacuum Breakers 3.6.1.5 3.6.1.5 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME D. Required Action and D.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time of Condition C C not met.

E. Two lines with one or E.1 Restore all vacuum 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> more reactor building- breakers in one line to-suppression chamber to OPERABLE status.

vacuum breakers inoperable for opening.

F. Required Action and F.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Associated Completion Compl eti on Time of Conditions A, AND At!P B, or EE not met.

F.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> SURVEILLANCE REQUIREMENTS SURVEILLANCE_REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.1.5.1 Verify Containment Atmospheric Dilution 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (CAD) System nitrogen storage inventory is equivalent to tank level is > 4622 4-6-22 inches water column in the liquid nitrogen storage tank.

SR 3.6.1.5.2 Verify Safety Grade Instrument Gas (SGIG) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> System header pressure ~ 80 psig.

(continued)

(conti nued)

PBAPS UNIT 2 3.6-19 Amendment No. 2-4-XXX

~XXX

PCIVs 3.6.1.3 3.6.1.3 ACTIONS (continued)

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME E. Purge/Vent flowpath E.1 Isolate the 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> open for an penetration.

accumulated time greater than 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> OR Q

for the calendar year while in MODE 11 or 22 E.2.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> with Reactor Pressure greater than 100 psig. AND ANP E.2.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> F. Required Action and F.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time of Condition A, AND B, C, or DD not met in MODE 1, 2, or 3. F.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> G. Required Action and G.1 Initiate action to Immediately associated Completion suspend operations Time of Condition A, with a potential for B, C, or DD not met draining the reactor for PCIV(s) required vessel.

to be OPERABLE during MODE 4 or 5.

MODE4or5. OR G.2 Initiate action to Immediately restore valve(s) to OPERABLE status.

SURVEILLANCE REQUIREMENTS SURVEILLANCE SURVEI LLANCE FREQUENCY SR 3.6.1.3.1 Verify Containment Atmospheric Dilution 24 hhours ours (CAD) System liquid nitrogen inventory storage storogo tanl(

tank 1evel level is equi val ent to ;::: 4 equivalent 4 22 inches water column in the liquid nitrogen storage tank.

SR 3.6.1.3.2 Verify Safety Grade Instrument Gas (SGIG) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> System header pressure is ;::: 80 psig.

(continued)

(conti nued)

PBAPS UNIT 3 3.6-12 Amendment No. XXX ~xxx

Reactor Building-to-Suppression Reactor Building-to-Suppression ChamberChamber Vacuum Vacuum Breakers Breakers 3.6.1.5 3.6.1.5 ACTIONS ACTIONS (continued)

Lcpnti nued)

CONDITION CONDITION REQUIRED ACTION REQUIRED ACTION COMPLETION TIME COMPLETION TIME D.

D. Required Action Required Action and and 0.1 D.1 Be in Be MODE 3.

in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 12 hours associated Completion associated Completion Time of Time of Condition CC not not met.

E.

E. Two lines Two lines with with one one or E.1 Restore all Restore all vacuum vacuum 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> hour more reactor more reactor building-building- breakers in breakers in one one line line to-suppression chamber to-suppression OPERABLE status.

to OPERABLE status.

vacuum breakers breakers inoperable for inoperable opening.

F. Required Action and F.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 12 Associated Completion Time of Conditions A, AND N

B, or E E not met.

F.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> SURVEILLANCE REQUIREMENTS SURVEI LLANCE_REQUIREMENTS SURVEILLANCE SURVEI LLANCE FREQUENCY SR SR 3.6.1.5.1 Verify Containment Atmospheric Dilution 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (CAD) System nitrogen storage inventory is equi val ent to tanl<

equivalent tank 1evel level is>

is 4-6-22 4-622 inches water column in the liquid nitrogen storage tank.

SR SR 3.6.1.5.2 3.6.1.5.2 Verify Safety Safety Grade Instrument Gas (SGIG) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> System header pressure ~ 80 psig.

(conti nued)

(continued)

PBAPS PBAPS UNIT UNIT 33 3.6-19 3.6-19 6&XXX Amendment No. 265XXX

ATTACHMENT 33 ATTACHMENT Markups of Technical Specifications Bases Pages Pages PBAPS, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 CPR-44 and DPR-56 CPR-56 REVISED TECHNICAL SPECIFICATIONS BASES 8ASES PAGES (For Information Only)

Unit22 Unit3 Unit 3 83.6-16 B 3.6-16 B 3.6-16 83.6-16 8.3.6-24 B.3.6-24 B 3.6-24 83.6-24 8B 3.6-35 B 8 3.6-35 ..

83.6-39 B 3.6-39 B 3.6-39 83.6-39 .....................

PCIVs PCIVs B 3.6.1.3 B 3.6.1.3 BASES BACKGROUND each of the supported system and components in LCO 3.6.1.3, 3.6.1.3, (continued) "Primary (PCIVs) ," and LCO Primary Containment Isolation Valves (PCIVs),

3.6.1.5, 3.6.1 .5, "Reactor Building-to-Suppression Chamber Reactor Building-to-Suppression Chamber Vacuum Breakers."

Breakers. For the SGIG System, liquid nitrogen from the CAD System liquid nitrogen storage tank passes through through the the CAD System liquid nitrogen vaporizer where it is converted converted to a gas. The gas then flows into a Unit 22 header and a Unit 3 header separated by two manual globe valves.

valves. From From each header, the gas then branches to each valve operator or or valve seal supplied by the SGIG System. Each branch is separated from the header by a manual globe valve and aa check valve.

To support SGIG System functions, the CAD System liquid liquid nitrogen storage tank tanl( minimuminventory rcquircd required lcvcl level is equivalent to a storage tank minimum required level of >~ 4-6 46-22 inches water column, or a technically justified source of equivalent inventory ~> 124,000 scf at 250 psig, and a minimum required SGIG System header pressure of 80 psig.

APPLICABLE The PCIVs LCO was derived from the assumptions related to SAFETY ANALYSES minimizing the loss of reactor coolant inventory, and establishing the primary containment boundary during major accidents. As part of the primary containment boundary, PCIV OPERABILITY supports leak tightness of primary containment. Therefore, the safety analysis of any event requiring isolation of primary containment is applicable to this LCO.

The DBAs that result in a release of radioactive material and are mitigated by PCIVs are a LOCA and a main steam line break (MSLB). In the analysis for each of these accidents, it is assumed that PCIVs are either closed or close within the required isolation times following event initiation.

This ensures that potential paths to the environment through PCIVs (including primary containment purge valves) are minimized. Of the events analyzed in Reference 1, the LOCA is a limiting event due to radiological consequences. The closure time of the main steam isolation valves (MSIVs) is the most significant variable from a radiological standpoint. The MSIVs are required to close within 33 to 5 seconds after signal generation. Likewise, it is assumed that the primary containment is isolated such that release of fission products to the environment is controlled.

(continued)

(conti nued)

PBAPS UNIT 2 B 3.6-16 B Revision No. GXX8GXX

PCIVs BB 3.6.1.3 3.6.1.3 BASES (continued)

SURVEILLANCE SR 3.6.1.3.1 REQUIREMENTS REQU I REM ENTS Verifying that the nitrogen inventory ;s is equivalent to a level in the GA9-liquid ~of ~ ~22 CAD liquid nitrogen tank i-s--of 44-22 inches water column (~ (> 124,000 sef scf at 250 psig) will ensure at least 7 days of post-LOCA SGIG System operation. This minimum volume of liquid nitrogen allows sufficient time after an accident to replenish the nitrogen supply in order to maintain the containment isolation function. The level inventory is verified every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to ensure that the system is capable of performing its intended isolation function when required. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is based on operating experience, which has shown to be an acceptable period to verify liquid nitrogen supply. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency also signifies the importance of the SGIG System for maintaining the containment isolation function of the primary containment purge and exhaust valves.

SR 3.6.1.3.2 This SR ensures that the pressure in the SGIG System header is ~ 80 psig. This ensures that the post-LOCA nitrogen pressure provided to the valve operators and valve seals is adequate for the SGIG System to perform its design function.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency was developed considering the importance of the SGIG System for maintaining the containment isolation function. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is also considered to be adequate to ensure timely detection of any breach in the SGIG System which would render the system incapable of performing its isolation function.

SR 3.6.1.3.3 3.6.1 .3.3 This SR ensures that the primary containment purge and exhaust valves are closed as required or, if open, open for an allowable reason. If a purge valve is open in violation of this SR, the valve is considered inoperable (Condition AA applies). The SR is modified by a Note stating that the SR is not required to be met when the purge and exhaust valves are open for the stated reasons. The Note states that these valves may be opened for inerting, de-inerting, pressure control, ALARA or air quality considerations for personnel entry, or Surveillances that require the valves to be open.

The 6 inch and 18 inch purge valves and 18 inch exhaust (continued)

(conti nued)

PBAPS UNIT 2 B B 3.6-24 Revision No. GXX GXX

Reactor Building-to-Suppression Building-to-Suppression Chamber Vacuum Vacuum Breakers Breakers BB 3.6.1.5 3.6.1.5 BASES BACKGROUND suppression chamber atmosphere. Low spray spray temperatures temperatures andand (continued) atmospheric conditions that yield the minimum amount of of contained noncondensible gases are assumed for conservatism.

conservatism.

The Safety Grade Instrument Gas (SGIG) System System supplies supplies pressurized nitrogen gas (from the Containment Containment Atmospheric Atmospheric Dilution (CAD) System liquid nitrogen storage tank) as aa safety grade pneumatic source to the CAC System purge and exhaust isolation valve inflatable seals, the reactor building-to-suppression chamber vacuum breaker air operated operated isolation butterfly valves and inflatable seal seal, and the CAC

, CAC and CAD Systems vent control air operated valves. The The SGIG System thus performs two distinct post-LOCA post-LOCA functions: (1) (1) supports containment isolation and (2) supports CAD SystemSystem vent operation. SGIG System requirements are addressed for each of the supported system and components in LCO 3.6.1.3, 3.6.1.3, "Primary Primary Containment Isolation Valves (PCIV5),

(PCIVs)," LCO 3.6.1.5, 3.6.1.5, and "Reactor Reactor Building-to-Suppression Chamber Vacuum Breakers."

Breakers. For the SGIG System, liquid nitrogen from the CAD System liquid nitrogen storage tank passes through the CAD System liquid nitrogen vaporizer where it is converted converted to a gas. The gas then flows into a Unit 22 header and a Unit 3 header separated by two manual globe valves. From each header, the gas then branches to each valve operator or valve seal supplied by the SGIG System. Each branch is separated from the header by a manual globe valve and a check valve.

To support SGIG System functions, the CAD System liquid nitrogen inventory ;s is equivalent to a storage tank minimum required level of ~ a 46-22 is ~ 4422 inches water column, or a technically justified source of equivalent inventory ~ >

124,000 sef scf at 250 ps;g, psig, and a minimum required SGIG System header pressure of 80 psig.

APPLICABLE Analytical methods and assumptions involving the reactor SAFETY ANALYSES building-to-suppression chamber vacuum breakers are used as part of the accident response of the containment systems.

Internal (suppression-chamber-to-drywell) and external (reactor building-to-suppression chamber) vacuum breakers (continued)

(conti nued)

PBAPS PBAPS UNIT 22 B B 3.6-35 Revision No. exxGXX

Reactor Building-to-Suppression Building-to-Suppression Chamber Chamber Vacuum Vacuum Breakers Breakers BB 3.6.1.5 3.6.1.5 BASES BASES ACTIONS ACTIONS ~

Li..

(continued)

(conti nued)

With two lines with one one or or more more vacuum vacuum breakers breakers inoperable inoperable opening, the primary for opening, primary containment containment boundary boundary is is intact.

intact.

However, in the event of of aa containment containment depressurization, depressurization, the the breakers is function of the vacuum breakers is lost.

lost. Therefore, Therefore, all all vacuum breakers in in one one line must bebe restored restored to to OPERABLE OPERABLE status within 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />. ThisThis Completion Completion Time Time is is consistent consistent with the ACTIONS of LCO 3.6.1.1, 3.6.1.1, which which requires that that primary primary OPERABLE status containment be restored to OPERABLE status within within 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />.

hour.

F.1 and F.2 Completion Time If any Required Action and associated Completion Time for Conditions A, B, or EE cannot be be met, the plant plant must must be be brought to a MODE in which the LCO does not apply. apply. To To achieve this status, the plant must be broughtbrought to to at at least least MODE 33 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to MODE 44 within 36 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

hours. The The allowed Completion Times are reasonable, based based on operating operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging challenging plant systems.

SURVEILLANCE SR 3.6.1.5.1 REQUIREMENTS REQU I REM ENTS Verifying that the nitrogen inventory is equivalent to a level in the GA9-liquid CAD liquid nitrogen tank ÷sof

~of ~ 4622

~22 inches water column (~ (? 124,000 sef scf at 250 psig) will ensure at least 7 days of post-LOCA SGIG System operation. This minimum volume of liquid nitrogen allows sufficient time after an accident to replenish the nitrogen supply in order to maintain the design function of the reactor building-to-suppression vacuum breakers. The lcvcl level inventory is verified every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to ensure that the system is capable of performing its intended isolation function when required.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is based on operating experience, which has shown to be an acceptable period to verify liquid nitrogen supply. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency also signifies the importance of the SGIG System for maintaining the design function of the reactor building-to-suppression chamber vacuum breakers.

SR 3.6.1.5.2 3.6.1 .5.2 This SR ensures that the pressure in the SGIG System header is ~ 80 psig. This ensures that the post-LOCA nitrogen pressure provided to the valve operators and valve seals that is adequate for the SGIG to perform its design function. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency was developed considering the importance of the SGIG System for maintaining the design function of the reactor building-to-suppression chamber function vacuum breakers. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is also considered to be adequate to ensure timely detection of any breach in the SGIG System which would render the system incapable of SGIG System performing its performing its function.

function.

(conti nued)

(continued)

PBAPS PBAPS UNIT UNIT 22 B 3.6-39 B 3.6-39 6XX Revision No. &SXX

PCIVs PCIVs 3.6.1.3 BB 3.6.1.3 BASES BACKGROUND each of the supported system and components in LCO LCD 3.6.1.3, 3.6.1.3, (continued) "Primary Primary Containment Isolation Valves (PCIVs), (PCIVs)," and LCO LCD 3.6.1.5, "Reactor Reactor Building-to-Suppression Chamber Chamber Vacuum Breakers."

Breakers. For the SGIG System, liquid nitrogen from the the CAD Systeffi Systcm liquid nitrogen storage tank passes through through thethe CAD Systeffi Sy3tcm liquid nitrogen vaporizer where it is converted converted to a gas. The gas then flows into a Unit 22 header and a Unit 3 header separated by two manual globe valves. From From each header, the gas then branches to each valve operator operator or or valve seal supplied by the SGIG System. Each branch is separated from the header by a manual globe valve and aa check valve.

To support SGIG System functions, the CAD Systcm Systeffi liquid nitrogen storage taAI( minimuminventory storagc tank ffiiAiffiuffiinventory rcquircd required lcvcl level is equivalent to a storage tank minimum required level of >~ 4 46-22 inches water column, or a technically justified source of equivalent inventory ~> 124,000 scf sef at 250 psig, and a minimum required SGIG System header pressure of 80 psig.

APPLICABLE The PCIVs LCDLCO was derived from the assumptions related to SAFETY ANALYSES minimizing the loss of reactor coolant inventory, and establishing the primary containment boundary during major accidents. As part of the primary containment boundary, PCIV OPERABILITY supports leak tightness of primary containment. Therefore, the safety analysis of any event requiring isolation of primary containment is applicable to this LCD.

LCO.

The DBAs DBA5 that result in a release of radioactive material and are mitigated by PCIVs are a LOCA and a main steam line break (MSLB). In the analysis for each of these accidents, it is assumed that PCIVs PCIV5 are either closed or close within the required isolation times following event initiation.

This ensures that potential paths to the environment through PCIVs (including primary containment purge valves) are minimized. Of the events analyzed in Reference 1, the LOCA is a limiting event due to radiological consequences. The closure time of the main steam isolation valves (MSIVs) is the most significant variable from a radiological standpoint. The MSIVs are required to close within 33 to 5 seconds after signal generation. Likewise, it is assumed that the primary containment is isolated such that release of fission products to the environment is controlled.

(continued)

(conti nued)

PBAPS UNIT 3 B 3.6-16 B Revision No. &1-XX&fXX

PCIVs PCIVs BB 3.6.1.3 3.6.1.3 BASES (continued)

SURVEILLANCE SR 3.6.1.3.1 REQUIREMENTS REQU I REMENTS Verifying that the nitrogen inventory is equivalent to aa level in the GA9-liquid inches f6-22 inches

~of ~ 4622 CAD liquid nitrogen tank msof water column (? (~ 124,000 scf at 250 psig) will ensure at least 7 days of post-LOCA SGIG System operation. This minimum volume of liquid nitrogen allows sufficient sufficient time after an accident to replenish the nitrogen supply in order to maintain the containment isolation function. The level level inventory is verified every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to ensure that the the system is capable of performing its intended isolation function when required. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is basedbased on operating experience, which has shown to be an acceptable period to verify liquid nitrogen supply. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency also signifies the importance of the SGIG System System for maintaining the containment isolation function of the primary containment purge and exhaust valves.

SR 3.6.1.3.2 3.6.1 .3.2 This SR ensures that the pressure in the SGIG System header is ~ 80 psig. This ensures that the post-LOCA nitrogen pressure provided to the valve operators and valve seals is adequate for the SGIG System to perform its design function.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency was developed considering the importance of the SGIG System for maintaining the containment isolation function. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is also considered to be adequate to ensure timely detection of any breach in the SGIG System which would render the system incapable of performing its isolation function.

SR 3.6.1.3.3 3.6.1 .3.3 This SR ensures that the primary containment purge and exhaust valves are closed as required or, if open, open for an allowable reason. If a purge valve is open in violation of this SR, the valve is considered inoperable (Condition AA applies). The SR is modified by a Note stating that the SR is not required to be met when the purge and exhaust valves are open for the stated reasons. The Note states that these valves may be opened for inerting, de-inerting, pressure control, ALARA or air quality considerations for personnel entry, or Surveillances that require the valves to be open.

The 6 inch and 18 inch purge valves and 18 inch exhaust (continued)

(conti nued)

PBAPS UNIT 3 B 3.6-24 B Revision No. GXX

Reactor Building-to-Suppression Reactor BUilding-to-Suppression Chamber Vacuum Vacuum Breakers Breakers 3.6.1.5 BB 3.6.1.5 BASES BASES BACKGROUND suppression chamber atmosphere. Low spray temperatures temperatures and and (continued) atmospheric conditions that yield the minimum amount amount ofof contained noncondensible gases are assumed for conservatism.

conservatism.

The Safety Grade Instrument Gas (SGIG)

(SGIG) System System supplies supplies pressurized nitrogen gas (from the Containment Containment Atmospheric Atmospheric Dilution (CAD) System liquid nitrogen storage tank) as as aa safety grade pneumatic source to the CAC System System purge and exhaust isolation valve inflatable seals, the reactor reactor building-to-suppression chamber vacuum breaker breaker air operated isolation butterfly valves and inflatable seal, and the the CAC CAC and CAD Systems vent control air operated valves.

valves. The The SGIG SGIG System thus performs two distinct post-LOCA post-LOCA functions: (1) (1) supports containment isolation and (2) supports supports CAD CAD System System vent operation. SGIG System requirements are addressed for each of the supported system and components in LCO 3.6.1.3, 3.6.1.3, "Primary Primary Containment Isolation Valves (PCIV5),

(PCIVs) ," LCO 3.6.1.5, 3.6.1.5, and "Reactor Reactor BUilding-to-Suppression Building-to-Suppression Chamber Vacuum Breakers."

Breakers. For the SGIG System, liquid nitrogen from the CAD System liquid nitrogen storage tank passes through the CAD System liquid nitrogen vaporizer where it is converted to a gas. The gas then flows into a Unit 22 header and a Unit 3 header separated by two manual globe valves. From each header, the gas then branches to each valve operator or valve seal supplied by the SGIG System. Each branch is separated from the header by a manual globe valve and a check valve.

To support SGIG System functions, the CAD System liquid nitrogen inventory is equivalent to a storage tank minimum required level of f5-a~

is ? 46-22 4-622 inches water column, or a technically justified source or equivalent inventory ?~

124,000 scf at 250 psig, and a minimum required SGIG System header pressure of 80 psig.

APPLICABLE Analytical methods and assumptions involving the reactor SAFETY SAFETY ANALYSES building-to-suppression chamber vacuum breakers are used as part of the accident response of the containment systems.

Internal (suppression-chamber-to-drywell) and external (reactor building-to-suppression chamber) vacuum breakers (continued)

(conti nued)

PBAPS PBAPS UNIT 3 B B 3.6-35 Revision No. GXX

Reactor Building-to-Suppression Chamber Vacuum Breakers Breakers BB 3.6.1.5 3.6.1.5 BASES ACTIONS ~

L..i (continued)

(conti nued)

With two lines with one or more vacuum breakers inoperable for opening, the primary containment boundary is intact.

However, in the event of a containment depressurization, the function of the vacuum breakers is lost. Therefore, all vacuum breakers in one line must be restored to OPERABLE status within 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />. This Completion Time is consistent consistent with the ACTIONS of LCO 3.6.1.1, which requires that primary containment be restored to OPERABLE status within 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />.

F.1 and F.2 If any Required Action and associated Completion Time for Conditions A, B, or E E cannot be met, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to MODE 44 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging challenging plant systems.

SURVEILLANCE SR 3.6.1.5.1 REQUIREMENTS REQU I REM ENTS Verifying that the nitrogen inventory is equivalent to a level in the GA9-liquid 46-22 inches

~of ~ 4-622 CAD liquid nitrogen tank 4-sof water column (~(> 124,000 sef scf at 250 psig) will ensure at least 7 days of post-LOCA SGIG System operation. This minimum volume of liquid nitrogen allows sufficient time after an accident to replenish the nitrogen supply in order to maintain the design function of the reactor building-to-suppression vacuum breakers. The lcvcl level inventory is verified every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to ensure that the system is capable of performing its intended isolation function when required.

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is based on operating experience, which has shown to be an acceptable period to verify liquid nitrogen supply. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency also signifies the importance of the SGIG System for maintaining the design function of the reactor building-to-suppression chamber vacuum breakers.

SR 3.6.1.5.2 This SR ensures that the pressure in the SGIG System header is ~ 80 psig. This ensures that the post-LOCA nitrogen pressure provided to the valve operators and valve seals that is adequate for the SGIG to perform its design function. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency was developed considering the importance of the SGIG System for maintaining the design function of the reactor building-to-suppression chamber vacuum breakers. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Frequency is also considered to be adequate to ensure timely detection of any breach in the SGIG System which would render the system incapable of performing its function.

(continued)

(conti nued)

PBAPS UNIT 3 B 3.6-39 B Revision No. &XX

&7XX