NMP2L2652, License Amendment Request - Revise Surveillance Requirement 3.5.1.2 to Remove Note

License Amendment Request - Revise Surveillance Requirement 3.5.1.2 to Remove Note

ML17234A025
Person / Time
Site:	Nine Mile Point
Issue date:	08/22/2017
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP2L2652
Download: ML17234A025 (15)

Text

Exelon Generation ~

NMP2L2652 August 22, 2017 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 NRG Docket No. 50-41 O 200 Exelon Way Kennett Square. PA 19348 www exeloncorp.com 10 CFR 50.90

Subject:

License Amendment Request - Revise Surveillance Requirement 3.5.1.2 to Remove Note In accordance with 1 O CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Exelon Generation Company, LLC (Exelon) requests an amendment to the Technical Specifications, Appendix A, of Renewed Facility Operating License No. NPF-69 for Nine Mile Point Nuclear Station, Unit 2 (NMP2).

The proposed amendment would delete the Surveillance Requirements (SR) Note associated with Technical Specifications (TS) Section 3.5.1, "ECCS -

Operating," SR 3.5.1.2, to reflect the Residual Heat Removal (RHR) system design and ensure the RHR system operation consistent with the TS Section 3.5.1 LCO requirements. provides the Evaluation of Proposed Changes. Attachment 2 provides the Proposed TS Marked-Up Pages. Attachment 3 provides the proposed TS Bases Marked-Up Pages. The TS Bases pages are being provided for information only.

The proposed changes have been reviewed by the NMP Plant Operations Review Committee in accordance with the requirements of the Exelon Quality Assurance Program.

Exelon requests approval of the proposed amendment by August 31, 2018. Once approved, the amendment shall be implemented within 60 days.

There are no regulatory commitments contained in this request.

U.S. Nuclear Regulatory Commission License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O August22,2017 Page 2 In accordance with 1 O CFR 50.91, "Notice for public comment; State consultation," paragraph (b), Exelon is notifying the State of New York of this application of license amendment by transmitting a copy of this letter and its attachments to the designated State Official.

Should you have any questions concerning this submittal, please contact Ron Reynolds at (61 O) 765-5247.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 22nd day of August 2017.

Respectfully,

~~ w;:-

James Barstow Director, Licensing & Regulatory Affairs Exelon Generation Company, LLC Attachments:

1) Evaluation of Proposed Changes

2) Proposed Technical Specifications Marked-Up Page

3) Proposed Technical Specifications Bases Marked-Up Page cc:

USNRC Regional Administrator, Region I USNRC Project Manager, NMP USNRC Senior Resident Inspector, NMP A. L. Peterson, NYSERDA w/attachments w/attachments w/attachments w/attachments

ATTACHMENT 1 License Amendment Request Nine Mile Point Nuclear Station, Unit 2 Docket No. 50-41 O EVALUATION OF PROPOSED CHANGES

SUBJECT:

Revise Surveillance Requirement 3.5.1.2 to Remove Note 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration 4.4 Conclusions

6.0 REFERENCES

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O Evaluation of Proposed Changes 1.0

SUMMARY

DESCRIPTION Page 1 of 8 In accordance with 1 O CFR 50.90, "Application for amendment of license, construction permit or early site permit," Exelon Generation Company, LLC (Exelon) is requesting to amend Facility Operating License (FOL) No. NPF-69 for Nine Mile Point Nuclear Station, Unit 2.

Exelon proposes to delete a Surveillance Requirement (SR) Note associated with Technical Specification (TS) 3.5.1, "ECCS - Operating," SR 3.5.1.2, to more appropriately reflect the Residual Heat Removal (RHR) system design, and ensure the RHR system operation is consistent with the TS Limiting Condition for Operation (LCO) requirements.

Exelon requests approval of the proposed changes. Once approved, the amendment shall be implemented within 60 days.

2.0 DETAILED DESCRIPTION The proposed change will delete the following Note from SR 3.5.1.2:

Low pressure coolant injection (LPCI) subsystems may be considered OPERABLE during alignment and operation for decay heat removal with reactor steam dome pressure less than the residual heat removal cut-in permissive pressure in MODE 3, if capable of being manually realigned and not otherwise inoperable. provides the marked-up TS pages with the proposed changes indicated. provides marked-up TS Bases pages with the proposed change indicated and provided for information only.

3.0 TECHNICAL EVALUATION

AHR System Design and Operation The NMP2 RHR system is designed to perform different and independent functions to support plant operation during normal and accident conditions:

Shutdown Cooling (SOC)

LPCI Suppression pool cooling RHR containment spray cooling The RHR system is composed of three independent loops, each containing a motor-driven pump, piping, valves, instrumentation, and controls. Each loop has a suction source from the suppression pool and is capable of discharging water to either the reactor vessel via a separate nozzle, or back to the suppression pool via a full-flow test line. The A and B loops have heat exchangers that are cooled by service water. Loops A and B can also take suction from the

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O Evaluation of Proposed Changes Page 2 of 8 reactor recirculation system suction and can discharge into the reactor recirculation discharge or to the suppression pool and drywell spray spargers. In addition, Loops A and B take suction from the fuel pool and discharge to the fuel pool cooling discharge.

The SDC mode is operated during normal unit cooldown and shutdown to remove decay heat.

This decay heat removal is required for performing refueling or maintenance operations, or for keeping the reactor in the MODE 3 (i.e., Hot Shutdown) condition. In the SOC mode of operation, either the A or B RHR pump takes suction from the A Reactor Recirculation (RR) loop; and directs the flow through the RHR heat exchanger prior to returning the water back to the Reactor Pressure Vessel (RPV) through the RR System.

The LPCI mode supports the Emergency Core Cooling System (ECCS) safety objective to limit the release of radioactive materials following a Loss of Coolant Accident (LOCA) by delivering a large flood of water into the core to refill the RPV and provide core cooling at low RPV pressures. The three RHR pumps automatically start in LPCI mode upon receipt of an ECCS initiation signal. In the LPCI mode of operation, each AHR pump takes suction from the suppression pool through an independent suction line and discharges to the reactor core through separate RPV piping penetrations.

The AHR suppression pool cooling mode ensures that the long term bulk temperature of the suppression pool is limited to 212°F following a LOCA. The two RHR suppression pool cooling subsystems perform the suppression pool cooling function by circulating water from the suppression pool through the RHR heat exchangers and returning it to the suppression pool.

Each AHR suppression pool cooling subsystem contains a pump and one heat exchanger and is manually initiated and independently controlled.

The RHR containment spray cooling mode provides two redundant means to spray into the containment and suppression pool vapor space to reduce internal pressure to below design limits with bypass leakage from all leakage paths from drywell to containment. There are two redundant, 100% capacity RHR containment spray subsystems. Each subsystem consists of a suction line from the suppression pool, an RHR pump, a heat exchanger, and two spray headers inside the primary containment. The AHR containment spray mode will be automatically initiated, if required, following a LOCA.

TS Requirements NMP2 TS 3.5.1, "ECCS - Operating," requires each ECCS injection system to be OPERABLE in Modes 1, 2, and 3. With regard to the LPCI mode, this means that all three LPCI subsystems are required for the LCO to be met. If one LPCI subsystem is inoperable, TS 3.5.1, Condition A, requires the inoperable subsystem to be returned to OPERABLE status within seven days.

The TS 3.5.1 LCO is modified by a note that allows a LPCI subsystem to be considered OPERABLE for the LPCI function when the subsystem is being aligned or is operating in the SOC mode, and the unit is in Mode 3 below the AHR cut-in permissive pressure. Utilization of this note requires that the RHR system be capable of manual realignment to the LPCI mode and not be otherwise inoperable.

NMP2 TS 3.4.9, "Residual Heat Removal (RHR) Shutdown Cooling System - Hot Shutdown,"

LCO requires that two AHR SOC subsystems be OPERABLE; and when no RR pump is in operation, one SDC subsystem must be in operation during Mode 3. An OPERABLE RHR SOC

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O Evaluation of Proposed Changes Page 3 of 8 subsystem consists of one AHR pump, one heat exchanger, and the associated piping and valves. Each SOC subsystem is considered OPERABLE if it can be manually aligned (remote or local) to the SOC mode for removal of decay heat. In Mode 3, one AHR SOC subsystem can provide the required cooling, but two subsystems are required to be OPERABLE to provide redundancy. If one or both SOC subsystems are inoperable, TS 3.4.9, Condition A, required immediate initiation of actions to restore one SOC subsystem to OPERABLE status.

TS 3.4.9 applies only in Mode 3, with RPV pressure less than the AHR cut-in permissive pressure. Mode 3 means that the reactor mode switch is in the 'Shutdown' position and the average reactor coolant temperature is greater than 200°F. In this mode, all the RPV head closure bolts are fully tensioned and therefore, RPV pressure is typically above atmospheric pressure.

Need for Proposed Changes During the Clinton NRC Component Design Basis Inspection (CDBI) in 2016 (Reference 1 ),

NRC inspectors identified a Non-cited Violation in that the design and operation of the AHR system was not consistent with TS requirements. This was documented in Reference 1. The AHR system could not support the TS operability of LPCI, AHR suppression pool cooling, and AHR containment spray, in MODE 3 while an AHR subsystem was operating in SOC mode, as required by the associated TS LCOs and SR Notes described above. Under the stated operating conditions, these LCOs are not met because the suppression pool suction valves are closed, and would not be able to be manually realigned from the SOC mode to support the other LCO functions (i.e., as required by the associated SR Notes). Specifically, these valves would not be capable of opening at water temperatures greater than 150°F due to pressure locking/thermal binding concerns.

During a LaSalle NRC inspection conducted in 2012 (Reference 2) in accordance with Temporary Instruction (Tl) 2515/177, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems (NRC Generic Letter 2008-01 )," NRC inspectors identified a concern because the operability of LPCI was not ensured in Mode 3 while an AHR subsystem was operating in SOC mode as required by TS. The inspection report (Reference 2) states that TS LCO 3.5.1 required, in part, each ECCS subsystem to be operable during Mode 3 and that this LCO included the note discussed above. Contrary to the requirements of this LCO 3.5.1 note, LaSalle had declared the LPCI subsystem inoperable when it was configured for the SOC mode of operation.

NMP has implemented procedure changes/restrictions preventing the realignment of an AHR subsystem from SOC to LPCI mode as a result of NRC Information Notice 2010-11 (Reference 3) and operating experience at Prairie Island (Reference 4) which determined that during operation in Mode 3, the potential exists for the water in the AHR pump suction piping aligned for SOC to flash/boil when realigned to the LPCI mode. This phenomenon is due to the physical arrangement (i.e. common interface) of the SOC and LPCI suction lines for the AHR pumps. The realignment from SOC mode to LPCI mode transfers the suction source for the AHR pump; thereby exposing the high temperature SOC water to the low pressure LPCI suction piping from the Suppression Pool. The resultant flashing/boiling of the high pressure, high temperature water when introduced to the low pressure piping could result in voiding of the suction piping, AHR pump cavitation, water hammer and associated AHR system damage.

This vulnerability is greatest during the early stages of Mode 3 operation when the SOC water temperature is the highest.

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O Evaluation of Proposed Changes Page 4 of 8 Review of the potential for valve thermal binding (Reference 5) found that the LPCI injection valves (2RHS*MOV24A/B) and the RHR pump min flow valves (2RHS*MOV4A/B) could be susceptible to thermal binding. This condition exists when the differential temperature across the valve exceeds 60°F, as it may be when the valve is closed to support SOC mode of operation. This temperature differential results from the high temperature SOC water on one side of the valve and cool suppression pool water on the other side. The flashing/boiling in the RHR suction piping and the RHR valve thermal binding are the result of the RHR system design that support several different operating modes using common equipment. This design feature, and the associated temperature phenomenon, prevents timely realignment of the RHR subsystem from SOC mode to LPCI mode. Therefore, the TS 3.5.1 note that allows an RHR subsystem to remain OPERABLE for LPCI mode when being aligned or operated in SOC mode is inappropriate and should be removed from the NMP2 TS. NMP2 will declare the respective LPCI subsystem of ECCS inoperable for the subsystem operating in SOC mode and enter the appropriate Condition(s) of TS 3.5.1 in Mode 3.

Justification for Proposed Changes Removal of Existing SR Note A review of all RHR valves for the potential of thermal binding found four valves that were susceptible: LPCI Injection Valves (2RHS*MOV24A/B) and RHR Pump Minimum Flow Valves (2RHS*MOV4A/B). When realigning from SOC to LPCI, the potential exists to have greater than 150°F differential temperature which could cause thermal binding. This temperature differential results from the high temperature SOC water on one side of the valve and the cool suppression pool water on the other. Review of NMP2 system operation parameters (Reference 5) identified that during reactor operation in Mode 3, the potential exists for the water in the RHR pump suction piping, when aligned for SOC, to flash/boil when realigned to the ECCS modes. The resultant flashing/boiling of the high pressure, high temperature water when introduced to the low pressure piping could result in voiding in the suction piping, RHR pump cavitation, water hammer and associated RHR system damage. The flashing/boiling in the RHR suction piping and the suppression pool suction valve thermal binding are the result of the RHR system design that supports several different operating modes using common equipment.

Due to these operational constraints, the Note in NMP2 SR 3.5.1.2 that allows LPCI, RHR suppression pool cooling, and RHR containment spray subsystems to be considered OPERABLE when being aligned or operated in SOC mode are inconsistent with system design and operation, should be removed from the NMP2 TS. At the low pressures and decay heat levels in MODE 3 with RPV pressure less than the RHR cut-in permissive, a reduced complement of ECCS subsystems will provide the required core cooling; thereby, allowing operation of RHR shutdown cooling when necessary.

The NRC approved Standard Technical Specifications (STS-NUREG-1434, Revision 4) also recognized this boiling water reactor design configuration and the mutual exclusivity of the LPCI and SOC functions. The STS bases explained the allowance provided by the TS 3.5.1 note as "necessary since the RHR System may be required to operate in the shutdown cooling mode to remove decay heat and sensible heat from the reactor. At these low pressures and decay heat levels, a reduced complement of ECCS subsystems should provide the required core cooling, thereby allowing operation of RHR shutdown cooling when necessary." However, industry and site specific operating experience makes the application of the TS 3.5.1 note inappropriate at NMP2.

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O Evaluation of Proposed Changes Page 5 of 8 Therefore, the removal of the TS 3.5.1 note, and operation with one RHR subsystem inoperable for LPCI mode while being aligned or operated in SDC in accordance with TS 3.4.9, is justified.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The following NRC requirements and guidance documents are applicable to the review of the proposed changes.

10 CFR 50, Appendix A, General Design Criterion (GDC) 34, "Residual heat removal," requires that a system to remove residual heat be provided with a safety function to transfer fission product decay heat and other residual heat from the reactor core at a rate such that specified acceptable fuel design limits and the design conditions of the reactor coolant pressure boundary are not exceeded.

10 CFR 50, Appendix A, GDC 35, "Emergency core cooling," requires that a system to provide abundant emergency core cooling be provided with a safety function to transfer heat from the reactor core following any loss of reactor coolant at a rate such that (1) fuel and clad damage that could interfere with continued effective core cooling is prevented and (2) clad metal-water reaction is limited to negligible amounts.

1 O CFR 10, Appendix A, GDC 37, "Testing of emergency core cooling system," requires that the emergency core cooling system design provide the capability for periodic pressure and functional testing. This testing shall assure (1) structural and leaktight integrity of components, (2) operability and performance of active components, (3) operability of the whole system under conditions as close to design as possible.

1 O CFR 50.36, "Technical specifications," details the content and information that must be included in a station's Technical Specifications (TS). In accordance with 10 CFR 50.36, TS are required to include (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation; (3) surveillance requirements; (4) design features; and (5) administrative controls. As described in 10 CFR 50.36(c)(2), "Limiting conditions for operation,"

are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When an LCO is not met, the licensee shall shut down the reactor or follow any other actions permitted by TS.

1 O CFR 50.46(a)(1 )(i) requires that each boiling or pressurized light-water nuclear power reactor be provided with an ECCS designed with a calculated cooling performance in accordance with an acceptable evaluation model following a postulated LOCA.

The proposed change does not involve any physical changes to the structures, systems, or components at NMP2. The proposed change will reflect current plant configuration of the RHR system design and assure safe operation by continuing to meet applicable regulations and requirements.

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 o Evaluation of Proposed Changes 4.2 Precedent Page 6 of 8 The NRC has approved similar license amendment requests to remove the applicable TS SR Note from SR 3.5.1.2, as follows:

1. Letter from R. B. Ennis (U.S. NRC) to M. J. Pacilio (EGC), "Peach Bottom Atomic Power Station, Units 2 and 3 - Issuance of Amendments RE: Delete Non-Conservative Note from Limiting Condition for Operation for Operation 3.5.1 (TAC Nos. MF3184 and MF3185)," dated July 28, 2014 (ADAMS Accession No. ML14163A589)

2. Letter from B. K. Vaidya (U.S. NRC) to B. C. Hanson (EGC), "LaSalle County Station Units 1 and 2, Issuance of Amendments RE: Revision of Technical Specifications Section 3.5.1, 'Emergency Core Cooling Systems Operating' (TAC Nos. MF5570 and MF 5571 )," dated October 14, 2015 (ADAMS Accession No. ML152448410) 4.3 No Significant Hazards Consideration Exelon has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 1 O CFR 50.92(c),

"Issuance of amendment," as discussed below:

1.

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

Response: No.

No physical changes to the facility will occur as a result of this proposed amendment.

The proposed change will not alter the physical design. The current Note in Technical Specification (TS) Surveillance Requirement (SR) 3.5.1.2 could make Low Pressure Coolant Injection (LPCI) susceptible to potential water hammer in the Residual Heat Removal (RHR) system if in the Shutdown Cooling (SOC) Mode of RHR in Mode 3 when swapping from the SOC to LPCI mode of AHR.

The proposed change will remove the TS Note and eliminate the risk for pump cavitation, water hammer through voiding in the suction piping, and potential damage to the RHR system.

Therefore, the proposed change does 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 change does not alter the physical design, safety limits, or safety analysis assumptions associated with the operation of the plant. Accordingly, the change does not introduce any new accident initiators, nor does it reduce or adversely affect the

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O Evaluation of Proposed Changes Page 7 of 8 capabilities of any plant structure, system, or component to perform their safety function.

Deletion of the TS Note is appropriate because current TSs could put the plant at risk for potential pump cavitation and voiding in the suction piping, resulting in water hammer and potential damage to the RHR system.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3.

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

Response: No.

The proposed change conforms to NRC regulatory guidance regarding the content of plant Technical Specifications. The proposed change does not alter the physical design, safety limits, or safety analysis assumptions associated with the operation of the plant.

Therefore, the proposed amendment does not involve a significant reduction in a margin of safety.

Based on the above, Exelon concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 1 O CFR 50.92(c) and, accordingly, a finding of no significant hazards consideration is justified.

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

5.0 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 1 O 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 1 O CFR 51.22(c)(9). Therefore, pursuant to 1 O CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

License Amendment Request Revise Surveillance Requirement 3.5.1.2 Docket No. 50-41 O Evaluation of Proposed Changes

6.0 REFERENCES

Page 8 of 8

1. Letter from M. Jeffers (U. S. Nuclear Regulatory Commission) to Bryan C. Hanson (Exelon Generation Company, LLC), "Clinton Power Station - NRG Component Design Bases Inspection, Inspection Report 05000461/2016009," dated January 12, 2017.

2. Letter from M. Kunowski (U. S. Nuclear Regulatory Commission) to M. J. Pacilio (Exelon Generation Company, LLC), "LaSalle County Station, Units 1 and 2 NRG Integrated Inspection Report 05000373/2012004; 05000374/2012004," dated October 30, 2012.

3. NRG Information Notice 2010-11, "Potential for Steam Voiding Causing Residual Heat Removal System lnoperability," dated June 16, 2010.

4. Prairie Island Nuclear Generating Plant LER 1-09-04, "Residual Heat Removal System lnoperability While in Mode 4 Due to Potential Steam Voiding," dated June 5, 2009.

5. Exelon Corrective Action Program, Action Request 01626060, "OE 307641 BWR RHR Suction Flashing and Water Hammer," dated February 25, 2014.

ATTACHMENT 2 License Amendment Request Nine Mile Point Nuclear Station, Unit 2 Docket No. 50-41 O PROPOSED TECHNICAL SPECIFICATION MARKED-UP PAGE TS Page 3.5.1-4

SURVEILLANCE REQUIREMENTS SR 3.5.1.1 SR 3.5.1.2 SURVEILLANCE Verify, for each ECCS injection/spray subsystem, locations susceptible to gas accumulation are sufficiently filled with water.

---

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

Low pressure eoolaflt ifljeetiofl (LPCI)

Sl:Jl~systeFflS A'IBY BO eeAsiaereel OPERABLE during aligAmeAt ana operation for deeay heat reFflO'tal with reseter steam aeA'!e pressure less thaA tl=le resielual heat reFflevel eut iA perFflissi*te pressure iA MODE a, if eapaelo of eeiAg fflaAually reeligAee afld Flot etl=lerwise iAeperaele.

ECCS - Operating 3.5.1 FREQUENCY In accordance with tho Surveillance Frequency Control Program Delete

---

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

SR 3.5.1.3 NMP2 Not required to be mot for system vent paths opened under administrative control.

Verify each ECCS injection/spray subsystem manual, power operated, and automatic valve in the flow path, that is not locked, sealed, or otherwise secured in position, is in tho correct position.

Verify:

a.

For each ADS nitrogen receiver discharge header, tho pressure is~ 160 psig; and

b.

For each ADS nitrogen receiver tank, tho pressure is~ 334 psig.

3.5.1-4 In accordance with tho Surveillance Frequency Control Program In accordance with tho Surveillance Frequency Control Program (continued)

Amendment 91, 16Q,162

ATTACHMENT 3 License Amendment Request Nine Mile Point Nuclear Station, Unit 2 Docket No. 50-410 PROPOSED TECHNICAL SPECIFICATION BASES MARKED-UP PAGE Bases Page:

B 3.5.1-5

BASES APPLICABLE SAFETY ANALYSES (continued)

LCO since transferring from the shutdown cooling mode to the LPCI mode could result in pump cavitation and voiding in the suction piping, resulting in the potential to damage the RHR System, including water hammer.

NMP2 ECCS - Operating B 3.5.1 inoperable at the time of the accident. The remaining OPERABLE ECCS subsystems provide the capability to adequately cool the core and prevent excessive fuel damage.

The ECCS satisfy Criterion 3 of Reference 12.

Each ECCS injection/spray subsystem and six ADS valves are required to be OPERABLE. The ECCS injection/spray subsystems are defined as the three LPCI subsystems, the LPCS System, and the HPCS System. The low pressure ECCS injection/spray subsystems are defined as the LPCS System and the three LPCI subsystems.

Management of gas voids is important to ECCS injection/spray subsystem operability.

With less than the required number of ECCS subsystems OPERABLE during a limiting design basis LOCA concurrent with the worst case single failure, the limits specified in 10 CFR 50.46 (Ref. 10) could potentially be exceeded. All ECCS subsystems must therefore be OPERABLE to satisfy the single failure criterion required by 10 CFR 50.46 (Ref. 10).

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LPCI subsystems FAay ea sonsieleFe OPERABLE during alignment and operation for decay heat remoValUM*~BSt<ew-ffff:t-a<Stt:ta+

~~**l!EQE~l-6'3~~~e&.- At these low pressures and decay heat levels, a reduced complement of ECCS subsystems should provide the required core cooling, thereby allowing operation of RHR shutdown cooling when necessary.

All ECCS subsystems are required to be OPERABLE during MODES 1, 2, and 3 when there is considerable energy in the reactor core and core cooling would be required to prevent fuel damage in the event of a break in the primary system piping. In MODES 2 and 3, the ADS function is not required when pressure is :::;: 150 psig because the low pressure ECCS subsystems (LPCS and LPCI) are capable of providing flow into the RPV below this pressure. ECCS requirements for MODES 4 and 5 are specified in LCO 3.5.2, "ECCS - Shutdown."

(continued)

B 3.5.1-5 Revision Q, 43 (A 150)