WO 13-0038, Operating Corporation - Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specification (TS) 3.4.12, Low Temperature Overpressure Protection (LTOP) System

Operating Corporation - Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specification (TS) 3.4.12, Low Temperature Overpressure Protection (LTOP) System

ML13156A338
Person / Time
Site:	Wolf Creek
Issue date:	05/28/2013
From:	Rich Smith Wolf Creek
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
WO 13-0038
Download: ML13156A338 (6)

Text

W$LFCREEK NUCLEAR OPERATING CORPORATION Russell A. Smith Site Vice President and Chief Nuclear Operating Officer May 28, 2013 WO 13-0038 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Reference:

1) Letter WO 12-0066, dated November 21, 2012, from R. A. Smith, WCNOC, to USNRC

2) Letter dated February 1, 2013, from C. F. Lyon, USNRC, to M. W.

Sunseri, WCNOC, "Wolf Creek Generating Station - Request for Additional Information Re: Revision to Technical Specification 3.4.12, "Low Temperature Overpressure Protection (LTOP)

System" (TAC NO. MF0309)"

3) Letter WO 13-0010, dated February 25, 2013, from R. A. Smith, WCNOC, to USNRC

4) Letter dated April 30, 2013, from C. F. Lyon, USNRC, to M. W.

Sunseri, WCNOC, "Wolf Creek Generating Station - Request for Additional Information Re: Revision to Technical Specification 3.4.12, "Low Temperature Overpressure Protection (LTOP)

System" (TAC NO. MF0309)"

Subject:

Docket No. 50-482: Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specification (TS) 3.4.12, "Low Temperature Overpressure Protection (LTOP) System" Gentlemen:

Reference 1 provided Wolf Creek Nuclear Operating Corporation's (WCNOC) application to revise 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 during the TS 3.4.12 Applicability.

Reference 2 provided a Nuclear Regulatory Commission (NRC) request for additional information related to the application. Reference 3 provided WCNOC's response to the request for additional information. Reference 4 provided a second request for additional information.

The Attachment provides WCNOC's response to the request for additional information.

P.O. Box 411 / Burlington, KS 66839 / Phone: (620) 364-8831 (* , )

An Equal Opportunity Employer M/F/HCNET

WO 13-0038 Page 2 of 3 The additional information does not expand the scope of the application as originally noticed, and does not impact the no significant hazards consideration determination presented in Reference 1.

In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," a copy of this submittal is being provided to the designated Kansas State official.

This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-4156, or Mr. Michael J. Westman at (620) 364-8831 ext. 4009.

Sincerely, Russell A. Smith RAS/rlt Attachment cc: A. T. Howell (NRC), w/a T. A. Conley (NRC), w/a C. F. Lyon (NRC), w/a N. F. O'Keefe (NRC), w/a Senior Resident Inspector (NRC), w/a

WO 13-0038 Page 3 of 3 STATE OF KANSAS SS 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.

Rustell A. Smith Site Vice President and Chief Nuclear Operating Officer SUBSCRIBED and sworn to before me this o day of -Mal ,2013.

S RHONA L.TIEMEYR Notary Public EO.iCL MY COMMISSION EXPRES WEA944,i v 1/ 2/~ Expiration Date 4*/ZJA/ LZJI// I2//

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Attachment to WO 13-0038 Page 1 of 3 Response to Request for Additional Information Reference 1 provided Wolf Creek Nuclear Operating Corporation's (WCNOC) application to revise 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.

Reference 2 provided a Nuclear Regulatory Commission (NRC) request for additional information related to the application. Reference 3 provided WCNOC's response to the request for additional information. Reference 4 provided a second request for additional information.

The specific NRC question is provided in italics.

1. Page 1 of Attachment I to the licensee's February 25, 2013, response to question I explains that Note I is the exception to the safety analysis, but does not provide a safety basis for taking that exception. Please provide a safety basis for the exception. This basis may include procedural controls, operator training, and related considerations, which ensure that the likelihood of an initiating event, which could cause the actuation of the two emergency core cooling system centrifugal chargingpumps (CCPs) along with the normal CCP, remains minimal. The basis may also include similar considerations that show that the consequences of such a simultaneous actuation are reasonablymitigated.

Response: As discussed in Reference 3, the NCP is normally in-service to maintain the charging and letdown functions of the Chemical and Volume Control System. One ECCS CCP is OPERABLE/FUNCTIONAL and capable of injecting into the RCS but is not in operation.

During a typical refueling outage, maintenance activities are performed during train (train 'A' or train 'B' safety related equipment) related windows. When the maintenance activities are completed and the train 'A' equipment is restored to service, then train 'B' equipment is taken out of service. Performing ECCS CCP swap operations for maintenance activities requires both CCPs to be capable of injecting for a limited period of time. During the time allowed for pump swap operation, the inoperable/nonfunctional CCP must first be restored to OPERABLE status to meet Limiting Condition for Operation (LCO) 3.5.3, "ECCS-Shutdown," and Technical Requirement (TR) 3.1.10, "Boration Injection System - Shutdown." TR 3.1.10 requires one boration injection subsystem (one ECCS CCP) be FUNCTIONAL in MODES 4, 5, and 6. The pump swap operation must be completed within the one hour allowed by Note 1 to LCO 3.4.12.

Procedure STS CR-002, "Shift Log for MODES 4, 5, and 6," verifies that one of the ECCS CCPs is incapable of injecting into the RCS once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. Additionally, the operators are required to log the status change of the CCPs following a pump swap. This provides positive control of the CCPs and ensures that only one CCP is capable of injecting at any given time except during pump swap operations.

In normal conditions a single failure of the engineered safety feature (ESF) actuation circuitry will result in the starting of at most one train of safety injection (one ECCS CCP, 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 the Appendix G limit. As discussed in Reference 3, the mass input transient analysis assumes only one PORV to be available to mitigate the transients to meet the single failure criteria. TS 3.4.12 requires pressure relief capabilities of two PORVs, or two residual heat removal (RHR) suction relief valves, or one PORV and one RHR suction relief valve, or a vent path.

Attachment to WO 13-0038 Page 2 of 3 The analog signals that would provide an ECCS actuation signal except Containment Pressure

- High are blocked below 1920 psig (and P-1 1 is actuated) per Procedure GEN 00-006, "Hot Standby to Cold Shutdown." Procedure GEN 00-006 requires arming both PORVs for low temperature overpressure protection when the lowest RCS cold leg temperature is 375 0 F. This procedure specifies the steps necessary for ensuring that the safety injection pumps and an ECCS CCP are made incapable of injecting into the RCS for the TS 3.4.12 mode of applicability. Specifically, a clearance order is placed for racking the breaker out and the pump control switch is placed in pull-to-lock to prevent the pumps from injecting. Once the unit enters MODE 5, procedure GEN 00-006 requires that the Solid State Protection System (SSPS) be disabled. This further eliminates the possibility of an inadvertent ECCS actuation. Procedure SYS BG-201, "Shifting Charging Pumps," provides instructions for shifting from one ECCS CCP to the other CCP. This procedure includes a caution that when any RCS cold leg temperature is less than or equal to 368 0 F and the reactor vessel head is installed, two ECCS CCPs may be OPERABLE for less than or equal to one hour for pump swap operations.

As discussed in the Updated Safety Analysis Report (USAR) Section 5.2.2.10.4.1, plant procedures maximize the use of a pressurizer cushion (steam bubble) during periods of low pressure, low temperature operation. This cushion dampens the plant's response to potential transient generating inputs, providing easier pressure control with slower response rates. An adequate cushion substantially reduces the severity of potential pressure transients, such as reactor coolant pump induced heat input, and slows the rate of pressure rise for others. During operation with the pressurizer water solid, procedures further highlight precautions that minimize the severity of, or the potential for, developing an overpressurization transient.

Procedure GEN 00-006 provides the steps necessary for filling the pressurizer for water solid operation which is typically performed between an RCS temperature of 200OF to 1801F. This is performed with at least one RHR train in-service, which ensures that at least one RHR suction relief is also available for RCS pressure relief.

Typically, the operating crews scheduled to perform the shutdown and collapse or form the pressurizer bubble are provided with Just-In-Time training that is done in real time to enable practicing the evolutions on the simulator prior to performing them in the plant.

The LCO 3.4.12 Note 1 time window (one hour) of exposure is minimal. The likelihood of an operator error leading to an ECCS actuation or an inadvertent start of ECCS CCP during this one-hour window is remote. Procedural requirements exist in GEN 00-006 and SYS BG-201 that provide instructions for pump swap operations. During this time window, there are at least two pressure relief devices (normally the PORVs) available for overpressure protection. The one-hour allowed by Note 1 provides sufficient time to safely complete the transfer and to complete the administrative controls associated with pump swap operations.

References:

1. WCNOC Letter WO 12-0066, "License Amendment Request To Revise Technical Specification 3.4.12, "Low Temperature Overpressure Protection (LTOP) System","

November 21, 2012. ADAMS Accession No. ML12334A406.

2. Letter from C. F. Lyon, USNRC, to M. W. Sunseri, WCNOC, "Wolf Creek Generating Station - Request for Additional Information Re: Revision to Technical Specification 3.4.12, "Low Temperature Overpressure Protection (LTOP) System" (TAC NO. MF0309),"

February 1, 2013. ADAMS Accession No. ML13030A062.

Attachment to WO 13-0038 Page 3 of 3

3. WCNOC Letter WO 13-0010, "Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specification (TS) 3.4.12, "Low Temperature Overpressure Protection (LTOP) System" dated February 25, 2013.

ADAMS Accession No. ML13072A297)

4. Letter C. F. Lyon, USNRC, to M. W. Sunseri, WCNOC, "Wolf Creek Generating Station -

Request for Additional Information Re: Revision to Technical Specification 3.4.12, "Low Temperature Overpressure Protection (LTOP) System" (TAC NO. MF0309)," April 30, 2013.