ML15057A480

Prairie Island, Units 1 and 2 - Supplement to License Amendment Request (LAR) to Revise Technical Specification (TS) 3.5.3, ECCS [Emergency Core Cooling System]- Shutdown

ML15057A480
Person / Time
Site:	Prairie Island
Issue date:	02/26/2015
From:	Davison K Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-PI-15-004, TAC MF0727, TAC MF0728
Download: ML15057A480 (17)

Text

Xcel Energy@ FEB 2 6 2015 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant Units 1 and 2 Dockets 50-282 and 50-306 Renewed License Nos. DPR-42 and DPR-60 L-PI-15-004 10 CFR 50.90 Supplement to License Amendment Request (LAR) to Revise Technical Specification (TS) 3.5.3, "ECCS [Emergency Core Cooling System]-Shutdown" (TAC Nos. MF0727 and MF0728) By letter dated February 20, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 13053A199), Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), submitted a license amendment request for Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2, to remove Technical Specification (TS) 3.5.3 Limiting Condition for Operation (LCO) Note 1. By letters dated June 25,2013 (ML 13178A024) and September 15, 2014 (ML 14258A089), NSPM supplemented the February 20, 2013 LAR. By email dated November 24, 2014, NRC Staff requested additional information (RAI) on the February 20, 2013, LAR (ML 13053A 199). The enclosure to this letter provides the response to the NRC Staff RAI. NSPM submits this supplement in accordance with the provisions of 10 CFR 50.90. The response to the RAI proposes additional TS changes which revise the scope of the requested license amendment.

Accordingly, the enclosure to this letter revises the Determination of No Significant Hazards Consideration.

However, the revised Determination of No Significant Hazards Consideration does not change the conclusions of the Determination of No Significant Hazards Consideration or Environmental Assessment presented in the February 20, 2013 (ML 13053A 199) submittal as supplemented June 25, 2013 (ML 13178A024) and September 15, 2014 (ML 14258A089).

In accordance with 10 CFR 50.91, NSPM is notifying the State of Minnesota of this LAR supplement by transmitting a copy of this letter and enclosure to the designated State Official.

1717 Wakonade Drive East

• Welch, Minnesota 55089-9642 Telephone:

651.388.1121 Document Control Desk Page 2 If there are any questions or if additional information is needed, please contact Mr. Dale Vincent, P.E., at 651-267-1736.

Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.

I declare under penalty of perjury that the foregoing is true and correct. Executed on FEB 2 6 2015 Kevin Davison Site Vice President, Prairie Island Nuclear Generating Plant Northern States Power Company -Minnesota Enclosures (1) cc: Administrator, Region Ill, USNRC Project Manager, PINGP, USNRC Resident Inspector, PINGP, US NRC State of Minnesota ENCLOSURE Supplement to License Amendment Request (LAR) to Revise Technical Specification (TS) 3.5.3, "ECCS [Emergency Core Cooling System]-Shutdown" TAC Nos. MF0727 and MF0728 By letter dated February 20, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 13053A 199), Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), submitted a license amendment request for Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2, to remove Technical Specification (TS) 3.5.3 Limiting Condition for Operation (LCO) Note 1. By letters dated June 25, 2013 (ML 13178A024) and September 15, 2014 (ML 14258A089), NSPM supplemented the February 20, 2013 LAR. By email dated November 24, 2014, NRC Staff requested additional information (RAI) on the February 20, 2013, LAR (ML 13053A 199). NRC RAI: The applicability of TS 3.5.3 is Mode 4 above 218 oF in the cold leg. As such, below 218 oF in the cold leg there is no requirement for ECCS [emergency core cooling system]. However, ECCS is necessary because RCS [reactor coolant system] temperature is high enough to flash if there is a depressurization or loss of coolant (note: below 200 T ave ECCS is not necessary because RCS temperature is not high enough to flash if there is a depressurization or loss of coolant).

Please explain why no ECCS is acceptable when the RCS temperature is high enough to flash if there is a depressurization or loss of coolant. How will the plant mitigate a depressurization event or loss of coolant below 218 oF in the cold leg. NSPM Response:

Currently TS 3.5.3 is applicable in Mode 4 when both RCS cold legs are above the safety injection (SI) disable temperature specified in the Pressure and Temperature Limits Report (PTLR). The Limiting Condition for Operation (LCO) statement requires one train of the ECCS, which comprises an Sl pump and residual heat removal (RHR) pump, to be operable throughout the mode or other specified conditions of applicability.

Low temperature overpressurization evaluations for PINGP demonstrate that a single Sl pump injection below the temperature specified as the Sl disable temperature in the PTLR (currently specified as 218 oF) could overpressurize the RCS. With both Sl pumps incapable of injecting below the Sl disable temperature, the LCO requirement for ECCS would not be met. To remedy this situation, the PINGP TS 3.5.3 Applicability was revised to exclude the portion of Mode 4 when the temperature of at least one RCS cold leg is below the Sl disable temperature.

NSPM proposes in this LAR supplement to revise the TS 3.5.3 Applicability statement to apply to all of Mode 4. Attachment 1 to this Enclosure provides TS 3.5.3 marked up with the changes proposed by this license amendment supplement including removal of Page 1 of 4 RHR LCO Note RAI the Applicability clause, "when both RCS cold leg temperatures are > Sl pump disable temperature specified in PTLR." Attachment 2 to this Enclosure provides the TS 3.5.3 Bases marked up with the changes associated with the proposed TS 3.5.3 changes.

• Attachment 3 to this Enclosure provides the retyped TS 3.5.3 page with all proposed changes incorporated.

The TS and Bases changes proposed in Attachments 1, 2 and 3 to this Enclosure supersede in their entirety the TS and Bases changes previously provided in the attachments to the February 20, 2013 LAR (ML 13053A 199) enclosure.

To preclude inadvertent operation of the Sl pump required to be operable to meet TS 3.5.3 and further protect the RCS from overpressurization, PINGP license amendments 183 and 173 (ML0801 00186), for Units 1 and 2 respectively, added LCO Note 2 to PINGP TS 3.5.3 which states, "An Sl train may be considered OPERABLE when the pump is capable of being manually started from the control room." This note allows the LCO operability requirements to be met with the Sl pump disabled from automatic initiation for the current TS 3.5.3 Applicability.

This same note will allow the LCO to be met with the proposed TS 3.5.3 Applicability to include the whole range of Mode 4. The response to this RAI proposes significant TS changes in addition to those previously proposed in this license amendment request which are beyond the scope of the Significant Hazards Consideration previously provided.

The following Significant Hazards Consideration supersedes the Section 4.3 "Significant Hazards Consideration", previously provided in the Enclosure to the February 20, 2013 (ML 13053A199) as modified by the supplement dated June 25, 2013 (ML 13178A024):

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

Response:

No This license amendment request proposes to revise the Technical Specification for ECCS operability requirements in Mode 4 by removing the LCO Note which allows the RHR subsystem to be considered operable for ECCS when aligned for shutdown cooling and revising the Applicability statement to include all of Mode 4. These changes will require one train of RHR to be aligned for ECCS operation throughout Mode 4. The proposed changes do not affect the ECCS and RHR subsystem design, the interfaces between the RHR subsystem and other plant systems' operating functions, or the reliability of the RHR subsystem.

The proposed changes do not change or impact the initiators and assumptions of the analyzed accidents.

Therefore, the ECCS and RHR subsystems will be capable of performing their accident mitigation functions, and the proposed TS changes do not involve an increase in the probability of an accident.

The proposed TS changes will require that one train of RHR is aligned for ECCS operation during Mode 4 which assures that one train of ECCS is operable to Page 2 of 4 RHR LCO Note RAI mitigate the consequences of a loss of coolant accident.

Thus the proposed TS changes do not involve a significant increase in the consequences of an accident.

Therefore, the proposed Technical Specification changes 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 This license amendment request proposes to revise the Technical Specification for ECCS operability requirements in Mode 4 by removing the LCO Note which allows the RHR subsystem to be considered operable for ECCS when aligned for shutdown cooling and revising the Applicability statement to include all of Mode 4. These changes will require one train of RHR to be aligned for ECCS operation throughout Mode 4. The proposed Technical Specification changes involve changes to when system trains are operated, but they do not change any system functions or maintenance activities.

The changes do not involve physical alteration of the plant, that is, no new or different type of equipment will be installed.

The changes do not alter assumptions made in the safety analyses but ensure that one train of ECCS is operable to mitigate the consequences of a loss of coolant accident.

These changes do not create new failure modes or mechanisms which are not identifiable during testing and no new accident precursors are generated.

Therefore, the proposed Technical Specification changes do 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 This license amendment request proposes to revise the Technical Specification for ECCS operability requirements in Mode 4 by removing the LCO Note which allows the RHR subsystem to be considered operable for ECCS when aligned for shutdown cooling and revising the Applicability statement to include all of Mode 4. These changes will require one train of RHR to be aligned for ECCS operation throughout Mode 4. This license amendment proposes Technical Specification changes which assure that the ECCS -Shutdown TS LCO requirements are met if a Mode 4 LOCA Page 3 of 4 RHR LCO Note RAI were to occur. With these changes, other TS requirements for shutdown cooling in Mode 4 will continue to be met. Based on review of plant operating experience, there is no discernable change in cooldown rates when utilizing a single train of RHR for shutdown cooling. Thus, no margin of safety is reduced as part of this change. Therefore, the proposed Technical Specification changes do not involve a significant reduction in a margin of safety. Although the response to the 10 CFR 50.92(c) questions have been is revised, the conclusion has not changed: Northern States Power Company, a Minnesota corporation (NSPM) concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c) and, accordingly, a finding of "no significant hazards consideration" is justified.

Page 4 of 4 ENCLOSURE,ATTACHMENT1 Technical Specification Pages (Markup) 3.5.3-1 1 page follows ECCS -Shutdown 3.5.3 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) 3.5.3 ECCS-Shutdown LCO 3.5.3 One ECCS train shall be OPERABLE.

1. An RHR train may be considered OPERABLE during alignment and operation for decay heat removal, if capable of being manually realigned to the EGGS mode of operation. An SI train may be considered OPERABLE when the pump is capable of being manually started from the control room. APPLICABILITY:

MODE 4 'Nhen both RDS cold leg temperatures are > SI pump disable temperature specified in PTLR. ACTIONS -------------------------------------------------NOTE------------------------------------------------------

LCO 3.0.4.b is not applicable to ECCS safety injection (SI) subsystem.

CONDITION A. Required ECCS residual heat removal (RHR) subsystem inoperable.

B. Required ECCS safety injection (SI) subsystem inoperable.

Prairie Island Units 1 and 2 A.l B.l REQUIRED ACTION COMPLETION TIME Initiate action to restore Immediately required ECCS RHR subsystem to OPERABLE status. Restore required ECCS SI 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> subsystem to OPERABLE status. Unit 1-Amendment No. 158 167 -+/--8J 3.5.3-1 Unit2-AmendmentNo.

149157-+/--7J-ENCLOSURE,ATTACHMENT2 Bases Pages (Markup) 8 3.5.3-1 8 3.5.3-2 8 3.5.3-3 8 3.5.3-4 8 3.5.3-5 8 3.5.3-6 6 pages follow ECCS -Shutdown B 3.5.3 B 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) B 3.5.3 ECCS-Shutdown BASES BACKGROUND Prairie. Island Units 1 and 2 The Background section for Bases 3.5.2, "ECCS-Operating," is applicable to these Bases, with the following modifications.

In MODE 4, the required ECCS train consists of two separate subsystems:

safety injection (SI) and residual heat removal (RHR). ' The ECCS flow paths consist of piping, valves, heat exchangers, and pumps such that water from the refueling water storage tank (R WST) or containment Sump B can be injected into the Reactor Coolant System (RCS) following the accidents described in Bases 3.5.2. In the event of a loss of coolant accident (LOCA) while in the Applicability of Technical Specification (TS) 3.5.3. fluid in the RHR suction piping could flash to steam. resulting in the RHR system not remaining capable of responding to the LOCA. Also. if a LOCA occurs in MODE 4 that is of sufficient size to depressurize and drain the RCS. any operating RHR pump could lose its suction source at some point. As a result, any operating RHR pump is assumed to fail if it is not shut down prior to steam and/or air voiding. See References 1 and 2. These issues are similar in that they both relate to the RHR system's ability to mitigate a LOCA while in MODE 4. and similar corrective actions are required to address both concerns.

However, the immediate precursor of each failure is distinctly different.

The first concern is a result of trapped fluid in the RHR system remaining at a temperature that is sufficiently high such that flashing will occur when the system is depressurized.

The second concern is due to the fact that during a LOCA of sufficient size to depressurize and drain the RCS any operating RHR pump would lose its suction source. Due to these issues, ohe RHR train must be aligned for ECCS Unit 1-RevisionA

.. mendment No. 158 B 3.5.3-1 Unit 2-RevisionAmendment No. 149 BASES BACKGROUND (continued)

APPLICABLE SAFETY ANALYSES Prairie Island Units 1 and2 ECCS -Shutdown B 3.5.3 mode of operation to satisfy LCO 3.5.3 when in MODE 4. Due to the lower heat generation rate associated with operation in MODE 4 it has been judged that the full power licensing analyses described in the Applicable Safety Analyses section of Bases 3.5.2 would bound the consequences of a Design Basis Accident (DBA) in MODE 4. It is also recognized that due to the lower pressure and temperatures in the RCS, the probability of occurrence of a DBA is reduced. Therefore, the ECCS operational requirements are reduced. It is understood in these reductions that certain automatic SI actuations are not available.

Since the RHR System may be aligned to provide normal shutdovm cooling, time may be required for manual alignment ofECCS equipment.

In this MODE, the heat generation rate is lower and sufficient time exists for manual actuation of the required ECCS to mitigate the consequences of a DBA. Therefore, only one train ofECCS is required for MODE 4. This requirement dictates that single failures are not considered for this LCO due to the time available for operators to respond to an accident.

The ECCS trains satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

Unit 1-RevisionAmendment No. 158 B 3. 5 .3-2 Unit 2 -Revisionl

.. mendment No. 14 9 ECCS -Shutdown B 3.5.3 BASES (continued)

LCO In MODE 4, one of the two independent (and redundant)

ECCS trains is required to be OPERABLE to ensure that sufficient ECCS flow is available to the core following a DBA. ** **In MODE 4, an ECCS train consists of an SI subsystem and an RHR subsystem.

Each train includes the piping, instruments, and controls to ensure an OPERABLE flow path capable of taking suction from the RWST and transferring suction to the containment sump. During an event requiring ECCS actuation, a flow path is required to provide an abundant supply of water from the RWST to the RCS via the SI subsystem capable (through manual actions) of injecting into each of the cold leg injection nozzles and reactor vessel upper plenum nozzles. In the long term, a flow path is required to provide recirculation flow via the RHR subsystem from the containment sump into each of the reactor vessel upper plenum nozzles. This LCO is modified by onetwe Notes which. Note 1 allows an RHR train to be considered OPERABLE during alignment and operation fur decay heat removal, if capable of being manually realigned (remote or local) to the EGGS mode of operation and not othenvise inoperable.

This allows operation in the RHR mode during l\10DE 4. Note 2 allows an SI train to be considered OPERABLE when the *pump is capable of being manually started for ECCS injection from the control room. APPLICABILITY In MODES 1, 2, and 3, the OPERABILITY requirements for ECCS are covered by LCO 3.5.2. Prairie Island Units 1 and 2 In MODE 4 with RCS temperature below 350°F and both RGS cold leg temperatures above the SI pump disable temperature specified in . the PTLR, one OPERABLE ECCS train is acceptable without single failure consideration, on the basis of the stable reactivity of the reactor and the limited core cooling requirements.

B 3.5.3-3 Unit 1 Unit 2 BASES ECCS -Shutdown B 3.5.3 APPLICABILITY In MODE 4*\vhen any RCS cold leg temperature is< the SI pump (continued)

.*. disable temperature, and MODES 5 and 6, plant conditions are such that the probability of an event requiring ECCS injection is extremely low. Core cooling requirements in .MODE 4 vmen any RCS cold leg temperature is < the SI pump disable temperature are addressed by LCO 3.4.6, "RCS Loops MODE 4." Core cooling requirements in MODE 5 are addressed by LCO 3.4.7, "RCS MODE 5, Loops Filled," and LCO 3.4.8, "RCS Loops-MODE 5, Loops Not Filled." MODE 6 core cooling requirements are addressed by LCO 3.9.5, "Residual Heat Removal (RHR) and Coolant Circulation-High Water Level, and LCO 3.9.6, "Residual Heat Removal (RHR) and Coolant Circulation-Low Water Level." ACTIONS A Note prohibits the application ofLCO 3.0.4.b to an inoperable Prairie Island Units 1 and 2

• ECCS safety injection (SI) subsystem when entering MODE 4-with both R{;S cold legs temperatures greater than the SI pamp disable temperature specified in the PTLR. There is an increased risk associated with entering MODE 4 'Nith both RCS cold legs temperat'..wes greater than the SI pump disable temperature specified in the PTLR from MODE 5 with an inoperable ECCS SI subsystem

• and the provisions ofLCO 3.0.4.b, which allow entry into a MODE or other specified condition in the Applicability with the LCO not met after performance of a risk assessment addressing inoperable systems and components, should not be applied in this circumstance.

With no ECCS RHR subsystem OPERABLE, the plant is not prepared to respond to a loss of coolant accident or to continue a cooldown using the RHR pumps and heat exchangers.

The Completion Time of immediately to initiate actions that would restore at least one ECCS RHR subsystem to OPERABLE status ensures that prompt action is taken to restore the required cooling capacity.

Normally, in MODE 4, reactor decay heat is removed B 3.5.3-4 Unit 1 Unit 2 -Revision BASES ACTIONS Prairie Island Units 1 and 2 A.1 (continued}

ECCS -Shutdown B 3.5.3 from the RCS by an RHR loop. If no RHR loop is OPERABLE for this function, reactor decay heat must be removed by some alternate method, such as use of the steam generators.

The alternate means of heat removal must continue until the inoperable RHR loop

• components can be restored to operation so that decay heat removal is continuous.

With both RHR pumps and heat exchangers inoperable, it would be unwise to require the plant to go to MODE 5, where the only available heat removal system is the RHR. Therefore, the

• appropriate action is to initiate measures to restore one ECCS RHR . subsystem and to continue the actions until the subsystem is restored to OPERABLE status. With no ECCS SI subsystem OPERABLE (neither train), due to the inoperability of the SI pump or flow path from the RWST, the plant is not prepared to provide high pressure response to Design Basis Events requiring SI. The 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Completion Time to restore at least one SI subsystem to OPERABLE status ensures that prompt action is taken to provide the required cooling capacity or to initiate actions

• to place the plant in MODE 5, where an ECCS train is not required.

When the Required Actions of Conditions B cannot be completed within the required Completion Time, a controlled shutdown should be initiated.

Twenty-four hours is a reasonable time, based on operating experience, to reach MODE 5 in an orderly manner and without challenging plant systems or operators.

B 3.5.3-5 Unit 1 -Revision

+9; Unit 2 -Revision +9; BASES (continued)

ECCS -Shutdown B 3.5.3 SURVEILLANCE SR 3.5.3.1 REQUIREMENTS REFERENCES Prairie Island Units 1 and 2 The applicable Surveillance descriptions from Bases 3.5.2 apply. The applicable references from Bases 3.5.2 apply. 1. NRC Information Notice 2010-11. 2. Westinghouse NSAL-09-8.

B 3.5.3-6 Unit 1 -Revision J. Unit 2 -Revision J.

ENCLOSURE,ATTACHMENT3 Technical Specification Pages (Retyped) 3.5.3-1 1 page follows ECCS -Shutdown 3.5.3 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) 3.5.3 ECCS-Shutdown LCO 3.5.3 One ECCS train shall be OPERABLE.

---

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

An SI train may be considered OPERABLE when the pump is capable of being manually started from the control room. APPLICABILITY:

MODE 4. ACTIONS -------------------------------------------------NOTE------------------------------------------------------

LCO 3.0.4.b is not applicable to ECCS safety injection (SI) subsystem.

CONDITION A. Required ECCS residual heat removal (RHR) subsystem inoperable.

B. Required ECCS safety injection (SI) subsystem inoperable.

Prairie Island Units 1 and 2 A.l B.1 REQUIRED ACTION COMPLETION TIME Initiate action to restore Immediately required ECCS RHR subsystem to OPERABLE status. Restore required ECCS SI 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> subsystem to OPERABLE status. 3.5.3-1 Unit 1-Amendment No. -l-6+ +8J. Unit 2-Amendment ill-