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{{Adams
#REDIRECT [[WO 12-0066, License Amendment Request to Revise Technical Specification 3.4.12, Low Temperature Overpressure Protection (Ltop) System.]]
| number = ML12334A406
| issue date = 11/21/2012
| title = License Amendment Request to Revise Technical Specification 3.4.12, Low Temperature Overpressure Protection (Ltop) System.
| author name = Smith R
| author affiliation = Wolf Creek Nuclear Operating Corp
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000482
| license number = NPF-042
| contact person =
| case reference number = WO 12-0066
| document type = Letter
| page count = 34
| project =
| stage = Request
}}
 
=Text=
{{#Wiki_filter:WO*1 LF CREEK'NUCLEAR OPERATING CORPORATION Russell A. Smith Site Vice President and Chief Nuclear Operating Officer November 21, 2012 WO 12-0066 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
 
==Reference:==
: 1) Letter WO 12-0047, dated May 31, 2012, from S. E. Hedges, WCNOC, to USNRC 2) Letter dated December 7, 1999, from J. N. Donohew, USNRC, to 0. L. Maynard, WCNOC, "Wolf Creek Generating Station -Amendment No. 130 to Facility Operating License No. NPF-42 (TAC NO. MA4572)"
 
==Subject:==
Docket No. 50-482: License Amendment Request To Revise Technical Specification 3.4.12, "Low Temperature Overpressure Protection (LTOP) System" Gentlemen:
Pursuant to 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Wolf Creek Nuclear Operating Corporation (WCNOC) hereby requests an amendment to Renewed Facility Operating License No. NPF-42 for the Wolf Creek Generating Station (WCGS). Reference 1 submitted a request for interpretation of Technical Specification (TS) Limiting Condition for Operation (LCO) 3.4.12, "Low Temperature Overpressure Protection (LTOP) System," requesting Nuclear Regulatory Commission (NRC) concurrence with the position that the LCO is met when both safety injection pumps and one centrifugal charging pump are not capable of injecting into the Reactor Coolant System (RCS) with the second centrifugal charging pump and the normal charging pump capable of injecting into the RCS. In a teleconference on October 17, 2012, the NRC indicated that they did not concur with the proposed position.
The proposed amendment revises TS 3.4.12 to reflect the mass input transient analysis that assumes an Emergency Core Cooling System (ECCS) centrifugal charging pump and the normal charging pump capable of injecting into the RCS during the TS 3.4.12 Applicability.
P.O. Box 411 / Burlington, KS 66839 / Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HCNET WO 12-0066 Page 2 of 3 Attachment I provides a description of the proposed change and supporting technical evaluation.
Attachment II provides the existing TS pages marked up to show the proposed change. Attachment III provides revised (clean) TS page. Attachment IV provides the existing TS Bases pages marked up to show the proposed changes and is for information only. Final TS Bases changes will be implemented pursuant to TS 5.5.14, "Technical Specification (TS)Bases Control Program," at the time the amendment is implemented.
It has been determined that this amendment application does not involve a significant hazard consideration as determined per 10 CFR 50.92, "Issuance of amendment." Pursuant to 10 CFR 51.22, "Criterion for categorical exclusion; identification of licensing and regulatory actions eligible for categorical exclusion or otherwise not requiring environmental review," Section (b), no environmental impact statement or environmental assessment needs to be prepared in connection with the issuance of this amendment.
The Plant Safety Review Committee reviewed this amendment application.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," a copy of this amendment application, with attachments, is being provided to the designated Kansas State official.The proposed changes to TS 3.4.12 are considered to be administrative changes based on the safety evaluation for Amendment No. 130 (Reference 2). As such, WCNOC requests approval of the proposed amendment by June 27, 2013. It is anticipated that the license amendment, as approved, will be effective upon issuance and will be implemented within 90 days of NRC issuance.This letter contains no commitments.
If you have any questions concerning this matter, please contact me at (620) 364-4156, or Mr. Gautam Sen at (620) 364-4175.Sincerely, Russell A. Smith RAS/rIt Attachments:
I Evaluation II Proposed Technical Specification Change (Markup)III Revised Technical Specification Pages IV Proposed Technical Specification Bases Changes (For Information Only)cc: E. E. Collins (NRC), w/a T. A. Conley (KDHE), w/a C. F. Lyon (NRC), w/a N. F. O'Keefe (NRC), w/a Senior Resident Inspector (NRC), w/a WO 12-0066 Page 3 of 3 STATE OF KANSAS)) s COUNTY OF COFFEY )Russell A. Smith, of lawful age, being first duly sworn upon oath says that he is Site Vice President and Chief Nuclear Operating Officer of Wolf Creek Nuclear Operating Corporation; that he has read the foregoing document and knows the contents thereof; that he has executed the same for and on behalf of said Corporation with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.By & 7 Rus elI A. Smith Site Vice President and Chief Nuclear Operating Officer SUBSCRIBED and sworn to before me this 2I4 day of /\oIepye be"- ,2012.I GAYLE SHEPHEARD' Notary lvublic M& Notary Public -,tate of Kansas My Appt. Expires Expiration Date J-- /-,4 Attachment I to WO 12-0066 Page 1 of 8 EVALUATION
 
==Subject:==
License Amendment Request To Revise Technical Specification 3.4.12, "Low Temperature Overpressure Protection (LTOP) System" 1.0
 
==SUMMARY==
DESCRIPTION 2.0 DETAILED DESCRIPTION 3.0 TECHNICAL EVALUATION
 
==4.0 REGULATORY EVALUATION==
 
4.1 Applicable Regulatory Requirements/Criteria 4.2 No Significant Hazards Consideration Determination 4.3 Conclusion 5.0 ENVIRONMENTAL CONSIDERATION
 
==6.0 REFERENCES==
 
Attachment I to WO 12-0066 Page 2 of 8 EVALUATION 1.0
 
==SUMMARY==
DESCRIPTION This evaluation supports a request to amend Renewed Facility Operating License No. NPF-42 for the Wolf Creek Generating Station (WCGS).The proposed change revises Technical Specification (TS) 3.4.12, "Low Temperature Overpressure Protection (LTOP) System," to reflect the mass input transient analysis that assumes an Emergency Core Cooling System (ECCS) centrifugal charging pump (CCP) and the normal charging pump (NCP) capable of injecting into the Reactor Coolant System (RCS)during the TS 3.4.12 Applicability.
2.0 DETAILED DESCRIPTION Proposed Changes Limiting Condition for Operation (LCO) 3.4.12 currently states, in part: An LTOP System shall be OPERABLE with a maximum of zero safety injection pumps and one centrifugal charging pump capable of injecting into the RCS and the accumulators isolated and one of the following pressure relief capabilities:
LCO 3.4.12 is revised to state, in part: An LTOP System shall be OPERABLE with a maximum of zero safety injection pumps, one Emergency Core Cooling System (ECCS) centrifugal charging pump, and the normal charging pump capable of injecting into the RCS and the accumulators isolated and one of the following pressure relief capabilities:
Notes 1 and 2 to LCO 3.4.12 and Condition B are revised to specify the centrifugal charging pumps as ECCS centrifugal charging pumps.Required Action B.1 is revised to state: Initiate action to verify a maximum of one ECCS centrifugal charging pump and the normal charging pump capable of injecting into the RCS.Surveillance Requirement (SR) 3.4.12.2 is revised to state: Verify a maximum of one ECCS centrifugal charging pump and the normal charging pump capable of injecting into the RCS.Revision 56 to the TS Bases were released on November 7, 2012 to reflect that the NCP shall not be capable of injecting into the RCS during the LTOP MODES. The changes to the affected TS Bases pages will be incorporated in accordance with TS 5.5.14, "Technical Specification (TS) Bases Control Program."
Attachment I to WO 12-0066 Page 3 of 8 Conditions that the Proposed Amendment is Intended to Resolve On May 9, 2012, a Nuclear Regulatory Commission (NRC) regional inspector identified that a potential violation of TS 3.4.12 occurred during a recent forced outage (January 2012) and in prior refueling outages. LCO 3.4.12 requires an LTOP System shall be OPERABLE with a maximum of zero safety injection pumps and one CCP capable of injecting into the RCS.During the recent forced outage and during refueling outages, one safety related CCP and the non-safety related NCP were capable of injecting into the RCS.A review of the WCGS licensing basis and the NRC safety evaluations related to License Amendment Nos. 123 (Reference
: 1) and 130 (Reference
: 2) establishes the following position: LCO 3.4.12 requires, in part, an LTOP System shall be OPERABLE with a maximum of zero safety injection pumps and one CCP capable of injecting into the RCS. The LCO is applicable in MODE 3 with any RCS cold leg temperature
< 368 OF, MODE 4, MODE 5, and MODE 6 when the reactor vessel head is on. The LCO is considered to be met when both safety injection pumps and one CCP are not capable of injecting into the RCS with the second CCP and the NCP capable of injecting into the RCS.The mass input transient analysis assumes simultaneous injection of both a CCP and the NCP into the water-solid RCS while the Residual Heat Removal (RHR) System and the letdown line are isolated.
This assumption is consistent with the TS LCO, which requires all safety injection pumps and one of the two ECCS CCPs be made incapable of injecting into the RCS and therefore, allows a CCP to be OPERABLE and the NCP to be functional under these modes of operation.
The safety evaluation in Amendment No. 123 for the conversion from current TSs to the improved TSs indicates that the requirements associated with LCO 3.4.12 is specific to ECCS pump capability to inject into the RCS.By letter dated December 29, 1998 (Reference 4), WCNOC submitted a license amendment request to revise the TSs to incorporate revised RCS heatup and cooldown limit curves, and a revised Cold Overpressure Mitigation System (COMS) power operated relief valve (PORV)setpoint limit curve, as required by 10 CFR 50 Appendix H and current TS (pre-improved Technical Specifications)
Surveillance Requirement 4.4.9.1.2.
In response to Reference 4, the NRC issued License Amendment No. 130 (Reference
: 5) on December 7, 1999. The amendment approved (1) the RCS heatup and cooldown limit curves in Figures 3.4-2 and 3.4-3, and COMS PORV setpoint limit curve in Figure 3.4-4 of the current TSs, and (2) the list of references in Section 5.6.6 on the RCS pressure and temperature limits report in the improved TSs. The safety evaluation for Amendment No. 130 states, in part: The operability of two PORVs or two RHR suction relief valves or an RCS vent opening of at least 2 square inches ensure adequate flow capacity to protect the RCS from overpressurization from either (1) the start of a centrifugal charging pump and/or the normal charging pump injecting into the RCS, or (2) the start of the idle RCP with the secondary water temperature of the steam generator less than or equal to 50 IF above the RCS cold leg temperature.
The full basis for this position was submitted to the NRC in Wolf Creek Nuclear Operating Corporation (WCNOC) letter WO 12-0047 (Reference 3).
Attachment I to WO 12-0066 Page 4 of 8 3.0 TECHNICAL EVALUATION
 
===System Description===
The LTOP System controls RCS pressure at low temperatures so the integrity of the reactor coolant pressure boundary (RCPB) is not compromised by violating the pressure and temperature (P/T) limits of 10 CFR 50, Appendix G. The reactor vessel is the limiting RCPB component for demonstrating such protection.
The PRESSURE TEMPERATURE LIMITS REPORT (PTLR) provides the maximum allowable actuation logic setpoints for the power operated relief valves (PORVs) and the maximum RCS pressure for the existing RCS cold leg temperature during cooldown, shutdown, and heatup to meet the Appendix G requirements during the LTOP MODES.The LTOP System for pressure relief consists of two PORVs with reduced lift settings, or two RHR suction relief valves, or one PORV and one RHR suction relief valve, or a depressurized RCS and an RCS vent of sufficient size. Two RCS relief valves are required for redundancy.
One RCS relief valve has adequate relieving capability to prevent overpressurization for the required coolant input capability.
The charging and letdown functions of the Chemical and Volume Control System are employed to maintain a programmed water level in the RCS pressurizer, thus maintaining a proper reactor coolant inventory during all phases of plant operation.
This is achieved by means of a continuous feed-and-bleed process during which the feed rate is automatically controlled, based on the pressurizer water level. The bleed rate can be chosen to suit various plant operational requirements by selecting the proper combination of letdown orifices in the letdown flow path. Three charging pumps (one "normal" pump and two CCPs) are provided to take suction from the volume control tank and return the purified reactor coolant to the RCS. Normal charging flow is handled by the NCP. The pumps are of the single speed, horizontal, centrifugal type. The 100-percent redundant ECCS CCPs are powered from separate Class 1E sources, while the NCP is powered from a non-Class 1 E source.Evaluation of Low Temperature Overpressure Transients The ASME Code (Section III, Appendix G) establishes guidelines and upper limits for RCS pressure primarily for low temperature conditions less than approximately 350 *F. The mitigation system discussed in Updated Safety Analysis Report (USAR) Section 5.2.2.10.1 addresses these conditions as discussed in the following paragraphs.
Two specific transients:
mass input and heat input, with the RCS in a water solid condition; have been considered as the design basis for the LTOP System. Each of these scenarios assumes as an initial condition that the RHR System is isolated from the RCS, and thus the relief capability of the RHR System relief valves is not available.
Transient analyses have been performed to determine the maximum pressure for the postulated mass input and heat input events.The LTOP PORV setpoint limit curve (PTLR Figure 2.2-1) is determined based on the updated heatup and cooldown limit curves, and the analysis results of limiting LTOP transients.
The methodology for this determination is given in WCAP-14040-A (Reference 6). The limiting LTOP mechanisms analyzed for WCGS under water solid conditions were:
Attachment I to WO 12-0066 Page 5 of 8 a. FOR LIMITING MASS ADDITION LTOP MECHANISM Operation of one ECCS CCP and the NCP with instrument air failure resulting in the flow control valve in the letdown line failing closed (letdown isolation) and the flow control valve in the charging line failing open (maximum charging flow), and b. FOR LIMITING HEAT ADDITION LTOP MECHANISM Inadvertent start-up of a reactor coolant pump with a maximum 50&deg;F temperature mismatch between the RCS and the hotter steam generators.
These analyses, using the LOFTRAN computer code, take into consideration pressure overshoot and undershoot beyond the PORV open and close setpoints, which can occur as a result of time delays in signal processing and valve stroke times. The maximum expected pressure overshoot and undershoot calculated from the limiting mass input and heat input transients, in conjunction with the 10 CFR 50, Appendix G, pressure limits and reactor coolant pump No. 1 seal pressure limit, are utilized in the selection of the pressure setpoints for the PORV. The mass injection rate assumed in the design basis mass input transient is based on 100% flow capacity of the NCP and one ECCS CCP. The maximum combined pump flow has been assumed in order to envelop the maximum flow possible by the operational configuration that uses the NCP for charging with one CCP remaining OPERABLE, or the use of one CCP for charging with the NCP remaining functional, during shutdown modes. The analyses demonstrated that one PORV or one RHR suction relief valve or an RCS vent of at least 2.0 square inches is capable of limiting the RCS pressure excursions below the 10 CFR 50 Appendix G limits for the design basis LTOP limits.Both the heat input and mass input analyses take into account the single failure criteria and therefore, only one PORV was assumed to be available for pressure relief. The above events have been evaluated considering the allowable pressure/temperature limits established by the Appendix G guidelines.
The evaluation of the transient results concluded that reactor vessel integrity is not impaired.
 
==4.0 REGULATORY EVALUATION==
 
4.1 Applicable Regulatory Requirements/Criteria Section 182a of the Atomic Energy Act requires applicants for nuclear power plant operating licenses to include TS as part of the license. The Commission's regulatory requirements related to the content of the TS are contained in 10 CFR 50.36, "Technical specifications." The TS requirements in 10 CFR 50.36 include the following categories:
(1) safety limits, limiting safety systems settings and control settings, (2) limiting conditions for operation (LCO), (3)surveillance requirements, (4) design features, and (5) administrative controls.The LTOP System controls RCS pressure at low temperatures so the integrity of the Reactor Coolant Pressure Boundary is not compromised by violating the pressure and temperature limits of 10 CFR Part 50, Appendix G, "Fracture Toughness Requirements."
Attachment I to WO 12-0066 Page 6 of 8 4.2 No Significant Hazards Consideration Determination The proposed amendment revises Technical Specification (TS) 3.4.12, "Low Temperature Overpressure Protection (LTOP) System" to reflect the mass input transient analysis that assumes an Emergency Core Cooling System (ECCS) centrifugal charging pump (CCP) and the normal charging pump (NCP) capable of injecting into the Reactor Coolant System (RCS)during the TS 3.4.12 Applicability.
WCNOC has evaluated whether or not a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92,"Issuance of amendment," Part 50.92(c), 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 change revises TS 3.4.12 to allow an ECCS CCP and the NCP to be capable of injecting into the RCS during low RCS pressures and temperatures.
The Limiting Condition for Operation provides RCS overpressure protection by having a minimum coolant input capability and have adequate pressure relief capability.
Analyses have demonstrated that one power operated relief valve (PORV) or one residual heat removal (RHR) suction relief valve or an RCS vent of at least 2.0 square inches is capable of limiting the RCS pressure excursions below the 10 CFR 50 Appendix G limits for the design basis LTOP limits.The NRC has previously evaluated the allowance for an ECCS CCP and the NCP being capable of injecting into the RCS during the TS 3.4.12 Mode of Applicability.
In the safety evaluation dated December 7, 1999 related to Wolf Creek Generation Station, Unit 1, Amendment No. 130, the NRC concluded:
The operability of two PORVs or two RHR suction relief valves or an RCS vent opening of at least 2 square inches ensure adequate flow capacity to protect the RCS from overpressurization from either (1) the start of a centrifugal charging pump and/or the normal charging pump injecting into the RCS, or (2) the start of the idle RCP with the secondary water temperature of the steam generator less than or equal to 50 IF above the RCS cold leg temperature.
The proposed change does not adversely affect accident initiators or precursors nor alter the design assumptions, conditions, and configuration of the facility or the manner in which the plant is operated and maintained.
The proposed change does not adversely affect the ability of structures, systems, and components (SSC) to perform their intended safety function to mitigate the consequences of an initiating event within the assumed acceptance limits. The proposed change does not affect the source term, containment isolation, or radiological release assumptions used in evaluating the radiological consequences of any accident previously evaluated.
Further, the proposed change does not increase the types and amounts of radioactive effluent that may be released offsite, nor significantly increase individual or cumulative occupational/public radiation exposure.
Attachment I to WO 12-0066 Page 7 of 8 Therefore, the proposed change does not represent a significant increase in the probability or consequences of an accident previously evaluated.
: 2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?
Response:
No The proposed change revises TS 3.4.12 to allow an ECCS CCP and the NCP to be capable of injecting into the RCS during low RCS pressures and temperatures.
The Limiting Condition for Operation provides RCS overpressure protection by having a minimum coolant input capability and have adequate pressure relief capability.
Analyses have demonstrated that one power operated relief valve (PORV) or one residual heat removal (RHR) suction relief valve or an RCS vent of at least 2.0 square inches is capable of limiting the RCS pressure excursions below the 10 CFR 50 Appendix G limits for the design basis LTOP limits.The proposed change will not physically alter the plant (no new or different type of equipment will be installed) or change the methods governing normal plant operation.
The proposed change does not introduce new accident initiators or impact assumptions made in the safety analysis.
Testing requirements continue to demonstrate that the Limiting Conditions for Operation are met and the system components are functional.
Therefore, it is concluded that the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
: 3. Does the proposed change involve a significant reduction in a margin of safety?Response:
No The proposed change does not alter the manner in which safety limits, limiting safety system settings or limiting conditions for operation are determined.
The safety analysis acceptance criteria are not impacted by this change. The proposed change will not result in plant operation in a configuration outside the design basis.Therefore, it is concluded that the proposed change does not involve a significant reduction in a margin of safety.Based on the above, WCNOC 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.
4.3 Conclusion 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 the health and safety of the public.
Attachment I to WO 12-0066 Page 8 of 8 5.0 ENVIRONMENTAL CONSIDERATION WCNOC has evaluated the proposed amendment for environmental considerations.
The review has determined that the proposed amendment would change requirements with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, and 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 10 CFR 51.22(c)(9).
Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.
 
==6.0 REFERENCES==
: 1. Letter from J. N. Donohew, USNRC, to 0. L. Maynard, WCNOC, "Conversion to Improved Technical Specification for Wolf Creek Generating Station -Amendment No. 123 to Facility Operating License No. NPF-42 (TAC NO. M98738)," March 31, 1999.2. Letter from J. N. Donohew, USNRC, to 0. L. Maynard, WCNOC, "Wolf Creek Generating Station -Amendment No. 130 to Facility Operating License No. NPF-42 (TAC NO.MA4572," December 7, 1999.3. WCNOC letter WO 12-0047, "Request for Interpretation of Technical Specification 3.4.12,"Low Temperature Overpressure Protection (LTOP) System"," May 31, 2012.4. WCNOC Letter WO 98-0104, "Docket Number 50-482: Application for Amendment To The Technical Specifications To Incorporate Revised Heatup and Cooldown Limit Curves, And A Revised Cold Overpressure Mitigation System (COMS) Power-Operated Relief Valve (PORV) Setpoint Limit Curve," December 29, 1998.5. Letter from J. N. Donohew, USNRC, to 0. L. Maynard, WCNOC, "Wolf Creek Generating Station -Amendment No. 130 to Facility Operating License No. NPF-42 (TAC NO.MA4572," December 7, 1999.6. WCAP-14040-A, "Methodology Used to Develop Cold Overpressure Mitigation System Setpoints and RCS Heatup and Cooldown Limit Curves," Revision 4, May 2004.
Attachment II to WO 12-0066 Page 1 of 6 PROPOSED TECHNICAL SPECIFICATION CHANGES (MARK-UP)
Attachment II to WO 12-0066 Page 2 of 6 LTOP System 3.4.12 3.4 REACTOR COOLANT SYSTEM (RCS)3.4.12 Low Temperature Overpressure Protection (LTOP) System -an Y& 4ie- rurtym c1rw~i LCO 3.4.12 An LTOP System shall be OPERABLE with a maximum of zero safety-&#xfd;iinjection pumpp l1one centrifugal charging pump capable of injec ingg into the RCS and the accumulators isolated and one of the following pressure relief capabilities:
: a. Two power operated relief valves (PORVs) with lift settings within the limits specified in the PTLR, or b. Two residual heat removal (RHR) suction relief valves with setpoints> 436.5 psig and < 463.5 psig, or c. One PORV with a lift setting within the limits specified in the PTLR and one RHR suction relief valve with a setpoint > 436.5 psig and< 463.5 psig, or d. The RCS depressurized and an RCS vent of > 2.0 square inches.C-- ----------
NOTES --------------------------
1.~~Two centrifugal charging pumps may be made capable of injecting for < 1 hour for pump swap operation.
: 2. Two safety injection pumps and two centrifugal charging pumps may be made capable of injecting into the RCS: (a) in MODE 3 with any RCS cold leg temperature
< 368&deg;F and ECCS pumps OPERABLE pursuant to LCO 3.5.2, "ECCS -Operating," and (b) for up to 4 hours after entering MODE 4 from MODE 3 or until the temperature of one or more RCS cold leg decreases below 325 0 F, whichever comes first.3. One or more safety injection pumps may be made capable of injecting into the RCS in MODES 5 and 6 when the RCS water level is below the top of the reactor vessel flange for the purpose of protecting the decay heat removal function.4. Accumulator may be unisolated when accumulator pressure is less than the maximum RCS pressure for the existing RCS cold leg temperature allowed by the P/T limit curves provided in the PTLR.Wolf Creek -Unit 1 3.4-26 Amendment No. 123 Attachment II to WO 12-0066 Page 3 of 6 LTOP System 3.4.12 APPLICABILITY:
MODE 3, with any RCS cold leg temperature
_< 368&deg;F, MODE 4, MODE 5, MODE 6 when the reactor vessel head is on.ACTIONS LCO 3.0.4b. is not applicable when entering MODE 4 or MODE 3.CONDITION REQUIRED ACTION COMPLET1ON TIME A. One or more safety A.1 Initiate action to verify a Immediately injection pumps capable of maximum of zero safety injecting into the RCS. injection pumps are capable of injecting into the RCS.B. Two centrifugal charging pumps capable of injecting into the RCS.B. 1 Initiate action to verify maximum of one , centrifugal charging pump/@)capable of injecting into the RCS.Immediately
=colt5er,&#xfd;4 vAA C. An accumulator not isolated C.1 Isolate affected 1 hour when the accumulator accumulator.
pressure is greater than or equal to the maximum RCS pressure for existing cold leg temperature allowed in the PTLR.(continued)
Wolf Creek -Unit 1 3.4-27 Amendment No. 4-24, 155 Attachment II to WO -Page 4 of 6 "40 P F~~~o~- WfrkC~v-%
kv~LTOP System 3.4.12 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME D. Required Action and D.1 Increase all RCS cold leg 12 hours associated Completion temperatures to > 368 0 F.Time of Condition C not met. OR D.2 Depressurize affected 12 hours accumulator to less than the maximum RCS pressure for existing cold leg temperature allowed in the PTLR.E. One required RCS relief E.1 Restore required RCS 7 days valve inoperable in MODE relief valve to OPERABLE 3 or MODE 4. status.F. One required RCS relief F.1 Restore required RCS 24 hours valve inoperable in relief valve to OPERABLE MODE 5 or 6. status.G. Two required RCS relief G.1 Depressurize RCS and 8 hours valves inoperable, establish RCS vent of> 2.0 square inches.OR Required Action and associated Completion Time of Condition A, B, D, E, or F not met.OR LTOP System inoperable for any reason other than Condition A, B, C, D, E, or F.Wolf Creek -Unit 1 3.4-28 Amendment No. 123 Attachment I1 to WO 12-0066 Page 5 of 6 LTOP System 3.4.12 SURVEILLANCE REQUIREMENTS and-SURVEILLANCE FREQUENCY SR 3.4.12.1 Verify a maximum of zero safety injection pumps are 12 hours capable of injecting into the RCS.SR 3.4.12.2 Verify a maximum of one centrifugal charging pump 12 hours capable of injecting into the RCS.&he. normAl ~SR 3.4.12.3 Verify each accumulator is isolated when 12 hours accumulator pressure is greater than or equal to the maximum RCS pressure for the existing RCS cold leg temperature allowed by the P/T limit curves provided in the PTLR.SR 3.4.12.4 Verify RHR suction isolation valves are open for each 72 hours required RHR suction relief valve.SR 3.4.12.5 Verify required RCS vent >_ 2.0 square inches open. 12 hours for vent pathway(s) not locked, sealed or otherwise secured in the open position AND 31 days for vent valve(s) locked, sealed or otherwise secured in the open position (continued)
Wolf Creek -Unit 1 3.4-29 Amendment No. 123 Attachment II to WO 12-01 Page 6 of 6 ( Z LTOP System 3.4.12 SURVEILLANCE REQUIREMENTS (continued)
SR 3.4.12.6 Verify PORV block valve is open for each required 72 hours PORV.SR 3.4.12.7 Not Used.SR 3.4.12.8 -----------------
NOTE -------------------
Not required to be performed until 12 hours after decreasing any RCS cold leg temperature to < 368)F.Perform a COT on each required PORV, excluding 31 days actuation.
SR 3.4.12.9 Perform CHANNEL CALIBRATION for each required 18 months PORV actuation channel.Wolf Creek -Unit 1 3.4-30 Amendment No. 123 Attachment III to WO 12-0066 Page 1 of 4 REVISED TECHNICAL SPECIFICATION PAGES LTOP System 3.4.12 3.4 REACTOR COOLANT SYSTEM (RCS)3.4.12 Low Temperature Overpressure Protection (LTOP) System LCO 3.4.12 An LTOP System shall be OPERABLE with a maximum of zero safety injection pumps, one Emergency Core Cooling System (ECCS) centrifugal charging pump, and the normal charging pump capable of injecting into the RCS and the accumulators isolated and one of the following pressure relief capabilities:
: a. Two power operated relief valves (PORVs) with lift settings within the limits specified in the PTLR, or b. Two residual heat removal (RHR) suction relief valves with setpoints> 436.5 psig and < 463.5 psig, or c. One PORV with a lift setting within the limits specified in the PTLR and one RHR suction relief valve with a setpoint > 436.5 psig and_< 463.5 psig, or d. The RCS depressurized and an RCS vent of > 2.0 square inches.----------------------------
NOTES --------------------------
: 1. Two ECCS centrifugal charging pumps may be made capable of injecting for _ 1 hour for pump swap operation.
: 2. Two safety injection pumps and two ECCS centrifugal charging pumps may be made capable of injecting into the RCS: (a) in MODE 3 with any RCS cold leg temperature
< 368&deg;F and ECCS pumps OPERABLE pursuant to LCO 3.5.2, "ECCS -Operating," and (b) for up to 4 hours after entering MODE 4 from MODE 3 or until the temperature of one or more RCS cold leg decreases below 325 0 F, whichever comes first.3. One or more safety injection pumps may be made capable of injecting into the RCS in MODES 5 and 6 when the RCS water level is below the top of the reactor vessel flange for the purpose of protecting the decay heat removal function.4. Accumulator may be unisolated when accumulator pressure is less than the maximum RCS pressure for the existing RCS cold leg temperature allowed by the P/T limit curves provided in the PTLR.Wolf Creek -Unit 1 3.4-26 Amendment No. 1-2-,
LTOP System 3.4.12 APPLICABILITY:
MODE 3, with any RCS cold leg temperature
_< 368&deg;F, MODE 4, MODE 5, MODE 6 when the reactor vessel head is on.ACTIONS-------------------
NOTE -----------------------------------------------------------
LCO 3.0.4b. is not applicable when entering MODE 4 or MODE 3...................................................................................................................................
CONDITION REQUIRED ACTION COMPLETION TIME A. One or more safety A.1 Initiate action to verify a Immediately injection pumps capable of maximum of zero safety injecting into the RCS. injection pumps are capable of injecting into the RCS.B. Two ECCS centrifugal B.1 Initiate action to verify a Immediately charging pumps capable of maximum of one ECCS injecting into the RCS. centrifugal charging pump and the normal charging pump capable of injecting into the RCS.C. An accumulator not C.1 Isolate affected 1 hour isolated when the accumulator.
accumulator pressure is greater than or equal to the maximum RCS pressure for existing cold leg temperature allowed in the PTLR.(continued)
Wolf Creek -Unit 1 3.4-27 Amendment No. 12'3,155&,
LTOP System 3.4.12 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.4.12.1 Verify a maximum of zero safety injection pumps are 12 hours capable of injecting into the RCS.SR 3.4.12.2 Verify a maximum of one ECCS centrifugal charging 12 hours pump and the normal charging pump capable of injecting into the RCS.SR 3.4.12.3 Verify each accumulator is isolated when 12 hours accumulator pressure is greater than or equal to the maximum RCS pressure for the existing RCS cold leg temperature allowed by the PIT limit curves provided in the PTLR.SR 3.4.12.4 Verify RHR suction isolation valves are open for each 72 hours required RHR suction relief valve.SR 3.4.12.5 Verify required RCS vent _ 2.0 square inches open. 12 hours for vent pathway(s) not locked, sealed or otherwise secured in the open position AND 31 days for vent valve(s) locked, sealed or otherwise secured in the open position (continued)
Wolf Creek -Unit 1 3.4-29 Amendment No. 1-23, Attachment IV to WO 12-0066 Page 1 of 13 PROPOSED TS BASES CHANGES (FOR INFORMATION ONLY)
Attachment IV to WO 12-0066 Page 2 of 13 LTOP System B 3.4.12 B 3.4 REACTOR COOLANT SYSTEM (RCS)B 3.4.12 Low Temperature Overpressure Protection (LTOP) System BASES BACKGROUND The LTOP System controls RCS pressure at low temperatures so the integrity of the reactor coolant pressure boundary (RCPB) is not compromised by violating the pressure and temperature (P/T) limits of 10 CFR 50, Appendix G (Ref. 1). The reactor vessel is the limiting RCPB component for demonstrating such protection.
The PTLR provides the maximum allowable actuation logic setpoints for the power operated relief valves (PORVs) and the maximum RCS pressure for the existing RCS cold leg temperature during cooldown, shutdown, and heatup to meet the Reference 1 requirements during the LTOP MODES.The reactor vessel material is less tough at low temperatures than at normal operating temperature.
As the vessel neutron exposure accumulates, the material toughness decreases and becomes less resistant to pressure stress at low temperatures (Ref. 2). RCS pressure, therefore, is maintained low at low temperatures and is increased only as temperature is increased.
The potential for vessel overpressurization is most acute when the RCS is water solid, occurring only while shutdown; a pressure fluctuation can occur more quickly than an operator can react to relieve the condition.
Exceeding the RCS P/T limits by a significant amount could cause brittle cracking of the reactor vessel. LCO 3.4.3, "RCS Pressure and Temperature (P/T) Limits," requires administrative control of RCS pressure and temperature during heatup and cooldown to prevent exceeding the PTLR limits.This LCO provides RCS overpressure protection by having a minimum coolant input capability and having adequate pressure relief capacity.Limiting coolant input capability requires both safety injection pumps and one Emergency Core Cooling System (ECCS) centrifugal charging pump to be incapable of injection into the RCS and isolating the accumulators.
The normal charging pump (NCP), in addition to one ECCS centrifugal charging pump flow, has been included in the analysis of design basis masupta-epesr ransient.T I-N-q n tot I iniefigAo RCwheyi spification i app" a b. The pressure relief capacity requires ei er o redun ant CS relief valves or a depressurized RCS and an RCS vent of sufficient size. One RCS relief valve or the open RCS vent is the overpressure protection device that acts to terminate an increasing pressure event.Wolf Creek -Unit 1 B 3.4.12-1 Revision 56 Attachment IV to WO 12-0066 Page 3 of 13 LTOP System B 3.4.12 BASES BACKGROUND With minimum coolant input capability, the ability to provide core coolant (continued) addition is restricted.
The LCO does not require the makeup control system deactivated or the safety injection (SI) actuation circuits blocked.Due to the lower pressures in the LTOP MODES and the expected core decay heat levels, the makeup system can provide adequate flow via the makeup control valve. If conditions require the use of more than one ECCS centrifugal charging pump for makeup in the event of loss of inventory, other ECCS pumps can be made available through manual (_actions.?
The LTOP System for pressure relief consists of two PORVs with reduced lift settings, or two residual heat removal (RHR) suction relief valves, or one PORV and one RHR suction relief valve, or a depressurized RCS and an RCS vent of sufficient size. Two RCS relief valves are required for redundancy.
One RCS relief valve has adequate relieving capability to prevent overpressurization for the required coolant input capability.
PORV Requirements As designed for the LTOP System, each PORV is signaled to open if the RCS pressure approaches a limit determined by the LTOP actuation logic.The LTOP actuation logic monitors both RCS temperature and RCS pressure and determines when a condition not acceptable with respect to the PTLR limits is approached.
The wide range RCS temperature indications are auctioneered to select the lowest temperature signal.The lowest temperature signal is processed through a function generator that calculates a pressure limit for that temperature.
The calculated pressure limit is then compared with the indicated RCS pressure from a wide range pressure channel. If the indicated pressure meets or exceeds the calculated value, a PORV is signaled to open.The PTLR presents the PORV setpoints for LTOP. The setpoints are normally staggered so only one valve opens during a low temperature overpressure transient.
Having the setpoints of both valves within the limits in the PTLR ensures that the Reference 1 limits will not be exceeded in any analyzed event.When a PORV is opened in an increasing pressure transient, the release of coolant will cause the pressure increase to slow and reverse. As the PORV releases coolant, the RCS pressure decreases until a reset pressure is reached and the valve is signaled to close. The pressure continues to decrease below the reset pressure as the valve closes.Wolf Creek -Unit 1 B 3.4.12-2 Revision 56 Attachment IV to WO 12-0066 Page 4 of 13 LTOP System B 3.4.12 trrfbv~m~.A~w~
&#xa3;~BASES BACKGROUND (continued)
RHR Suction Relief Valve Requirements During LTOP MODES, the RHR System is operated for decay heat removal and low pressure letdown control. Therefore, the RHR suction isolation valves are open in the piping from the RCS hot legs to the inlets of the RHR pumps. While these valves are open the RHR suction relief valves are exposed to the RCS and are able to relieve pressure transients in the RCS.The RHR suction isolation valves must be open to make the RHR suction relief valves OPERABLE for RCS overpressure mitigation.
The RHR suction relief valves are spring loaded, bellows type water relief valves with pressure tolerances and accumulation limits established by Section III of the American Society of Mechanical Engineers (ASME)Code (Ref. 3) for Class 2 relief valves.RCS Vent Requirements Once the RCS is depressurized, a vent exposed to the containment atmosphere will maintain the RCS at containment ambient pressure in an RCS overpressure transient, if the relieving requirements of the transient do not exceed the capabilities of the vent. Thus, the vent path must be capable of relieving the flow resulting from the limiting LTOP mass or heat input transient, and maintaining pressure below the P/T limits. The required vent capacity may be provided by one or more vent paths.APPLICABLE SAFETY ANALYSES Safety analyses (Ref. 4) demonstrate that the reactor vessel is adequately protected against exceeding the Reference 1 P/T limits. In MODES 1, 2, and 3, the pressurizer safety valves will prevent RCS pressure from exceeding the Reference 1 limits. In MODE 3 (with any RCS cold leg temperature
< 368 0 F) and below, overpressure prevention falls to two OPERABLE RCS relief valves or to a depressurized RCS and a sufficient sized RCS vent. Each of these means has a limited overpressure relief capability.
The actual temperature at which the pressure in the P/T limit curve falls below the pressurizer safety valve setpoint increases as the reactor vessel material toughness decreases due to neutron embrittlement.
Each time the PTLR curves are revised, the LTOP System must be re-evaluated to ensure its functional requirements can still be met using the RCS relief valve method or the depressurized and vented RCS condition.
Wolf Creek -Unit 1 B 3.4.12-3 Revision 0 Attachment IV to WO 12-0066 Page 5 of 13 LTOP System B 3.4.12 BASES APPLICABLE The PTLR contains the acceptance limits that define the LTOP SAFETY ANALYSES requirements.
Any change to the RCS must be evaluated against the (continued)
Reference 9 analyses to determine the impact of the change on the LTOP acceptance limits.Transients that are capable of overpressurizing the RCS are categorized as either mass or heat input transients, examples of which follow: Mass Input Type Transients
: a. Inadvertent safety injection; or b. Charging/letdown flow mismatch.Heat Input Type Transients
: a. Inadvertent actuation of pressurizer heaters;b. Loss of RHR cooling; or c. Reactor coolant pump (RCP) startup with temperature asymmetry within the RCS or between the RCS and steam generators.
The following are required with exception described below during the LTOP MODES to ensure that mass and heat input transients do not occur, which either of the LTOP overpressure protection means cannot handle: fC4e o. n1 6r% a. Rendering both safety injection pumps and one ECOS centrifugal, ih,. I " charging pump incapable of injection (t&#xfd;eCPPW'ha t.obcapable
\-tirt LTO? MODES) fici~ nehRS b. Deactivating the accumulator discharge isolation valves in their closed positions or by venting the affected accumulator; and c. Precluding start of an RCP if secondary temperature is more than 50&deg;F above primary temperature in any one loop. LCO 3.4.5, "RCS Loops -MODE 3," LCO 3.4.6, "RCS Loops -MODE 4," and LCO 3.4.7, "RCS Loops -MODE 5, Loops Filled," provide this protection.
Operation below 350&deg;F but greater than 3251F with all ECCS centrifugal charging and safety injection pumps OPERABLE is allowed for up to 4 hours. During low pressure, low temperature operation all automatic safety injection actuation signals except Containment Pressure -High are Wolf Creek -Unit 1 B 3.4.12-4 Revision 56 Attachment IV to WO 12-0066 Page 6 of 13 LTOP System B 3.4.12 BASES APPLICABLE blocked. In normal conditions a single failure of the ESF actuation SAFETY ANALYSES circuitry will result in the starting of at most one train of safety injection (continued) (one centrifugal charging pump, and one safety injection pump). For temperatures above 325 0 F, an overpressure event occurring as a result of starting two pumps can be successfully mitigated by operation of both PORV's without exceeding Appendix G limit. Given the short time duration that this condition is allowed and the low probability of a single failure causing an overpressure event during this time, the single failure of a PORV is not assumed. Initiation of both trains of safety injection during this 4-hour time frame due to operator error or a single failure occurring during testing of a redundant channel are not considered to be credible accidents.
Although LTOP is required to be OPERABLE when RCS temperature is less than 368 0 F, operation with all ECCS centrifugal charging pumps and both safety injection pumps OPERABLE is acceptable when RCS temperature is greater than 350 0 F. Should an inadvertent safety injection occur above 350 0 F, a single PORV has sufficient capacity to relieve the combined flow rate of all ECCS pumps and the NCP. Above 350 0 F, two RCPs and all pressurizer safety valves are required to be OPERABLE.Operation of an RCP eliminates the possibility of a 50&deg;F difference existing between indicated and actual RCS temperature as a result of heat transport effects. Considering instrument uncertainties only, an indicated RCS temperature of 350&deg;F is sufficiently high to allow full RCS pressurization in accordance with Appendix G limitations.
Should an overpressure event occur in these conditions, the pressurizer safety valves provide acceptable and redundant overpressure protection.
The Reference 9 analyses demonstrate that either one RCS relief valve or the depressurized RCS and RCS vent can maintain RCS pressure below limits when only one ECCS centrifugal charging pump (in addition to the fW&#xfd;Y&#xfd;L NCP) is actuated.
However, the LCO allows only one ECCS centrifual charging pump OPERABLdurin the LTOP MODES. -IJ-qqt.P-/-, .WoMh't info Since neither one RCS relief valve nor the RCS vent can handle the pressure transient caused by accumulator injection, when RCS temperature is low, the LCO also requires accumulator isolation when accumulator pressure is greater than or equal to the maximum RCS pressure for the existing RCS cold leg temperature allowed in the PTLR.The isolated accumulators must have their discharge valves closed and the valve power supply breakers fixed in their open positions.
Fracture mechanics analyses established the temperature of LTOP Applicability at 368 0 F.Wolf Creek -Unit 1 B 3.4.12-5 Revision 56 Attachment IV to WO 12-0066 Page 7 of 13 LTOP System B 3.4.12 t#~~~i4p~BASES APPLICABLE SAFETY ANALYSES (continued)
PORV Performance The fracture mechanics analyses show that the vessel is protected when the PORVs are set to open at or below the limit shown in the PTLR. The setpoints are derived by analyses that model the performance of the LTOP System, assuming the mass injection transient of one ECCS centrifugal charging pump and the NCP injecting into the RCS and the heat injection transient of starting an RCP with the RCS 50&deg;F colder than the secondary coolant. These analyses consider pressure overshoot and undershoot beyond the PORV opening and closing, resulting from signal processing and valve stroke times. The PORV setpoints at or below the derived limit ensures the Reference 1 P/T limits will be met.The PORV setpoints in the PTLR will be updated when the revised P/T limits conflict with the LTOP analysis limits. The P/T limits are periodically modified as the reactor vessel material toughness decreases due to neutron embrittlement caused by neutron irradiation.
Revised limits are determined using neutron fluence projections and the results of examinations of the reactor vessel material irradiation surveillance specimens.
The Bases for LCO 3.4.3, "RCS Pressure and Temperature (P/T) Limits," discuss these examinations.
The PORVs are considered active components.
Thus, the failure of one PORV is assumed to represent the worst case, single active failure.RHR Suction Relief Valve Performance The RHR suction relief valves do not have variable pressure and temperature lift setpoints like the PORVs. Analyses show that one RHR suction relief valve with a setpoint at or between 436.5 psig and 463.5 psig will pass flow greater than that required for the limiting LTOP transient while maintaining RCS pressure less than the P/T limit curve.As the RCS P/T limits are decreased to reflect the loss of toughness in the reactor vessel materials due to neutron embrittlement, the RHR suction relief valves must be analyzed to still accommodate the design basis transients for LTOP.The RHR suction relief valves are considered active components.
Thus, the failure of one valve is assumed to represent the worst case single active failure.Wolf Creek -Unit 1 B 3.4.12-6 Revision 56 Attachment IV to WO 12-0066 Page 8 of 13 LTOP System B 3.4.12 BASES APPLICABLE RCS Vent Performance SAFETY ANALYSIS (continued)
With the RCS depressurized, analyses show a vent size of 2.0 square inches is capable of mitigating the limiting LTOP transient.
The capacity of a vent this size is greater than the flow of the limiting transient for the LTOP configuration, one ECCS centrifugal charging pump maintaining RCS pressure less than the maximum pressure on the P/T limit curve. "__ _ _The RCS vent size will be re-evaluated for compliance each time the P/T limit curves are revised based on the results of the vessel material surveillance.
The RCS vent is passive and is not subject to active failure.The LTOP System satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).
LCO This LCO requires that the LTOP System is OPERABLE.
The LTOP System is OPERABLE when the maximum coolant input or heat input bounded by that assumed in the analyses and required pressure relief capabilities are OPERABLE.
Violation of this LCO could lead to the loss of low temperature overpressure mitigation and violation of the Reference 1 limits as a result of an operational transient. *- Nt.To limit the coolant input capability, the LCO requires that a maximum of zero safety injection pump&#xfd;s one ECCS centrifugal charging pump-e capable of injecting into the RCS, and all accumulator discharge isolation valves be closed and immobilized (when accumulator pressure is greater than or equal to the maximum RCS pressure for the existing RCS cold leg temperature allowed in the PTLR). The NCP shall not be capable of injecting into the RCS when this specification is applicable.
The LCO is modified by four Notes. Note 1 allows two ECCS centrifugal charging pumps to be made capable of injecting into the RCS for < 1 hour for pump swap operations.
One hour provides sufficient time to safely complete the actual transfer and to complete the administrative controls and surveillance requirements associated with the swap. The intent is to minimize the actual time that more than one ECCS centrifugal charging pump is physically capable of injection.
This is accomplished by racking out the breaker for one pump or employing two independent means to prevent a pump start in accordance with SR 3.4.12.2.Note 2 recognizes the Applicability overlap between LCO's 3.4.12 and 3.5.2 and states that two safety injection pumps and two ECCS centrifugal charging pumps may be made capable of injecting into the RCS: Wolf Creek -Unit 1 B 3.4.12-7 Revision 56 Attachment IV to WO 12-0066 Page 9 of 13 LTOP System B 3.4.12 BASES LCO (a) In MODE 3 with any RCS cold leg temperature
< 368 0 F and ECCS (continued) pumps OPERABLE pursuant to LCO 3.5.2, "ECCS-Operating", and (b) For up to 4 hours after entering MODE 4 from MODE 3 or the temperature of one or more RCS cold legs decreases below 325&deg;F, whichever comes first.Note 3 states that one or more safety injection pumps may be made capable of injecting into the RCS in MODES 5 and 6 when the RCS water level is below the top of the reactor vessel flange for the purpose of protecting the decay heat removal function.Note 4 states that the accumulator may be unisolated when the accumulator pressure is less than the maximum RCS pressure for the existing RCS cold leg temperature as allowed by the P/T limit curves provided in the PTLR. The accumulator discharge isolation valve Surveillance is not required under these pressure and temperature conditions.
The elements of the LCO that provide low temperature overpressure mitigation through pressure relief are: a. Two OPERABLE PORVs; or A PORV is OPERABLE for LTOP when its block valve is open, its lift setpoint is set to the limit required by the PTLR and testing proves its ability to open at this setpoint, and motive power is available to the two valves and their control circuits.b. Two OPERABLE RHR suction relief valves; or An RHR suction relief valve is OPERABLE for LTOP when its RHR suction isolation valves are open, its setpoint is at or between 436.5 psig and 463.5 psig, and testing has proven its ability to open at this setpoint.c. One OPERABLE PORV and one OPERABLE RHR suction relief valve; or d. A depressurized RCS and an RCS vent.An RCS vent is OPERABLE when open with an area of >2.0 square inches.Wolf Creek -Unit 1 B 3.4.12-8 Revision 1 Attachment IV to WO 12-006(Page 10 of 13 BASES LTOP System B 3.4.12 (t LCO (continued)
Each of these methods of overpressure prevention is capable of mitigating the limiting LTOP transient.
APPLICABILITY This LCO is applicable in MODE 3 when any RCS cold leg temperature is_< 368 0 F, in MODE 4, in MODE 5 and in MODE 6 when the reactor vessel head is on. The pressurizer safety valves provide overpressure protection that meets the Reference 1 P/T limits in MODES 1, 2, and 3.When the reactor vessel head is off, overpressurization cannot occur.LCO 3.4.3 provides the operational P/T limits for all MODES. LCO 3.4.10,"Pressurizer Safety Valves," requires the OPERABILITY of the pressurizer safety valves that provide overpressure protection during MODES 1, 2, and 3.Low temperature overpressure prevention is most critical during shutdown when the RCS is water solid, and a mass or heat input transient can cause a very rapid increase in RCS pressure when little or no time allows operator action to mitigate the event.ACTIONS A Note prohibits the application of LCO 3.0.4b. to an inoperable LTOP System. There is an increased risk associated with entering MODE 3 from MODE 4 and MODE 4 from MODE 5 with LTOP inoperable and the provisions of LCO 3.0.4b., 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.
A.1 and B.1 With one or more safety injection pumps or two ECCS centrifugal charging pumps capable of injecting into the RCS, RCS overpressurization is possible.To immediately initiate action to restore restricted coolant input capability to the RCS reflects the urgency of removing the RCS from this condition.
C.1, D.1, and D.2 An unisolated accumulator requires isolation within 1 hour. This is only required when the accumulator pressure is at or more than the maximum RCS pressure for the existing temperature allowed by the P/T limit curves.Wolf Creek -Unit 1 B 3.4.12-9 Revision 56 Attachment IV to WO 12-0066 Page 11 of 13 LTOP System B 3.4.12 BASES -" c ACTIONS C.1. D.1, and D.2 (continued)
If isolation is needed and cannot be accomplished in 1 hour, Required Action D.1 and Required Action D.2 provide two options, either of which must be performed in the next 12 hours. By increasing the RCS temperature to > 368 0 F, an accumulator pressure of 648 psig cannot exceed the LTOP limits if the accumulators are fully injected.Depressurizing the accumulators below the LTOP limit from the PTLR also gives this protection.
The Completion Times are based on operating experience that these activities can be accomplished in these time periods and on engineering evaluations indicating that an event requiring LTOP is not likely in the allowed times.E. 1 In MODE 3 with any RCS cold leg temperature
< 368 0 F or MODE 4, with one required RCS relief valve inoperable, the RCS relief valve must be restored to OPERABLE status within a Completion Time of 7 days. Two RCS relief valves in any combination of the PORVS and the RHR suction relief valves are required to provide low temperature overpressure mitigation while withstanding a single failure of an active component.
The Completion Time considers the facts that only one of the RCS relief valves is required to mitigate an overpressure transient and that the likelihood of an active failure of the remaining valve path during this time period is very low.F. 1 The consequences of operational events that will overpressurize the RCS are more severe at lower temperature (Ref. 7). Thus, with one of the two RCS relief valves inoperable in MODE 5 or in MODE 6 with the head on, the Completion Time to restore two valves to OPERABLE status is 24 hours.The Completion Time represents a reasonable time to investigate and repair several types of relief valve failures without exposure to a lengthy period with only one OPERABLE RCS relief valve to protect against overpressure events.Wolf Creek -Unit 1 B 3.4.12-10 Revision 0 Attachment IV to WO 12-0066 Page 12 of 13 LTOP System B 3.4.12 BASES ACTIONS (continued)
G._1 The RCS must be depressurized and a vent must be established within 8 hours when: a. Both required RCS relief valves are inoperable; or b. A Required Action and associated Completion Time of Condition A, B, D, E, or F is not met; or c. The LTOP System is inoperable for any reason other than Condition A, B, C, D, E, or F.The vent must be sized > 2.0 square inches to ensure that the flow capacity is greater than that required for the worst case mass input transient reasonable during the applicable MODES. This action is needed to protect the RCPB from a low temperature overpressure event and a possible brittle failure of the reactor vessel.The Completion Time considers the time required to place the plant in this Condition and the relatively low probability of an overpressure event during this time period due to increased operator awareness of administrative control requirements.
SURVEILLANCE SR 3.4.12.1, SR 3.4.12.2.
and SR 3.4.12.3 AAV_.vlcp REQUIREMENTS To minimize the potential for a low temperature overpressure event by limiting the mass in utcaability, a maximum of zero safety injection pump one ECCS centrifugal charging pump are verified to be capable of injecting into the RCS and the accumulator discharge isolation valves are verified closed and with power removed from the valve operator.Verification that each accumulator is isolated is only required when accumulator pressure is greater than or equal to the maximum RCS pressure for the existing RCS cold leg temperature allowed by the P/T limit curves provided in the PTLR.The safety injection pumps and one ECCS centrifugal charging pump are rendered incapable of injecting into the RCS through removing the power from the pumps by racking the breakers out under administrative control.An alternate method of cold overpressure protection may be employed using at least two independent means to render a pump incapable of injecting into the RCS such that a single failure or single action will not Wolf Creek -Unit 1 B 3.4.12-11 Revision 56 Attachment IV to WO 12-0066 Page 13 of 13 LTOP System B 3.4.12 BASES SURVEILLANCE SR 3.4.12.1.
SR 3.4.12.2, and SR 3.4.12.3 (continued)
REQUIREMENTS result in an injection into the RCS. This may be accomplished by placing the pump control switch in pull to lock and closing at least one valve in the discharge flow path, or by closing at least one valve in the discharge flow path and removing power from the valve operator, or by closing at least one manual valve in the discharge flow path under administrative control.Providing pumps are rendered incapable of injecting into the RCS, they may be energized for purposes such as testing or for filling accumulators.
The Frequency of 12 hours is sufficient, considering other indications and alarms available to the operator in the control room, to verify the required status of the equipment.
SR 3.4.12.4 Each required RHR suction relief valve shall be demonstrated OPERABLE by verifying its RHR suction isolation valves are open and by testing it in accordance with the Inservice Testing Program. This Surveillance is only required to be performed if the RHR suction relief valve is being used to meet this LCO.The RHR suction isolation valves are verified to be opened every 72 hours. The Frequency is considered adequate in view of other administrative controls such as valve status indications available to the operator in the control room that verify the RHR suction isolation valves remain open.The ASME Code (Ref. 8), test per Inservice Testing Program verifies OPERABILITY by proving proper relief valve mechanical motion and by measuring and, if required, adjusting the lift setpoint.SR 3.4.12.5 The RCS vent of _> 2.0 square inches is proven OPERABLE by verifying its open condition either: a. Once every 12 hours for a valve that is not locked, sealed, or otherwise secured in the open position.Wolf Creek -Unit 1 B 3.4.12-12 Revision 32}}

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