ML18283B952

NRR E-mail Capture - Final RAI - South Texas Standby DG TS Change (L-2018-LLA-0078)

ML18283B952
Person / Time
Site:	South Texas
Issue date:	10/10/2018
From:	Lisa Regner Plant Licensing Branch IV
To:	Richards D, Sterling L South Texas
References
L-2018-LLA-0078
Download: ML18283B952 (6)

Text

NRR-DMPSPEm Resource From: Regner, Lisa Sent: Wednesday, October 10, 2018 4:35 PM To: Drew Richards (amrichards@STPEGS.COM); Lance Sterling (lsterling@stpegs.com)

Cc: Regner, Lisa

Subject:

Final RAI - South Texas Standby DG TS change (L-2018-LLA-0078)

Attachments: RAI STP SBDG - final to licensee.docx Final Request for Additional Information (L-2018-LLA-0078)

The U.S. Nuclear Regulatory Commission (NRC) staff sent STP Nuclear Operating Company (the licensee) draft Requests for Additional Information (RAIs) by email on August 17 (mechanical), September 5 (electrical), September 11 (protective systems), and October 2, 2018 (technical specifications). These RAI questions relate to a license amendment request (LAR) that proposes to revise certain surveillance requirements (SRs) for Technical Specification (TS) 3.8.1.1, Alternating Current Sources for minimum voltage and frequency acceptance criteria for standby diesel generator testing at South Texas Project Units 1 and 2 (STP).

STPNOC informed the NRC staff that a clarification call was needed for the draft RAIs for mechanical, electrical and protective systems and this call was held on September 19, 2018. Subsequently, the NRC staff modified the draft RAI for mechanical based on the licensee need for clarifications. The revised draft was sent on September 20, and the licensee stated that the revisions provided the needed clarifications.

The final request for additional information for all subjects is attached. Mr. Drew Richards agreed to provide a response to this final RAI on or before 30 days from the date of this email. If STPNOC does not respond by this date, the requested completion date for the LAR decision may not be met by the NRC.

The NRC staff also informed the licensee that a publicly available version of this final RAI would be placed in the NRCs Agencywide Documents Access and Management System (ADAMS).

By letter dated March 27, 2018 (ADAMS package Accession No. ML18086B761), the licensee requested an amendment to the Operating License for South Texas Project Units 1 and 2. The proposed amendment requests a TS changes for the Standby Diesel Generator. The NRC staff requires additional information to complete its review of this request as detailed in the attached document.

Lisa M. Regner Senior Project Manager Branch 4, Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission OWFN 9E01

' 301-415-1906 Lisa.Regner@nrc.gov 1

Hearing Identifier: NRR_DMPS Email Number: 616 Mail Envelope Properties (BN6PR09MB1491DF7044EDF07D62C8F1C8E5E00)

Subject:

Final RAI - South Texas Standby DG TS change (L-2018-LLA-0078)

Sent Date: 10/10/2018 4:34:58 PM Received Date: 10/10/2018 4:35:00 PM From: Regner, Lisa Created By: Lisa.Regner@nrc.gov Recipients:

"Regner, Lisa" <Lisa.Regner@nrc.gov>

Tracking Status: None "Drew Richards (amrichards@STPEGS.COM)" <amrichards@STPEGS.COM>

Tracking Status: None "Lance Sterling (lsterling@stpegs.com)" <lsterling@stpegs.com>

Tracking Status: None Post Office: BN6PR09MB1491.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 2290 10/10/2018 4:35:00 PM RAI STP SBDG - final to licensee.docx 29316 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

STP NUCLEAR OPERATING COMPANY SOUTH TEXAS PROJECT ELECTRIC GENERATING STATION UNITS 1 AND 2 DOCKET NUMBERS 50-498 AND 50-499 REQUESTS FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATION 3.8.1.1 (A.C. SOURCES, OPERATING)

By application dated March 27, 2018 (ADAMS Accession Number ML18086B761), STP Nuclear Operating Company, the licensee, requested changes to the South Texas Project (STP) Unit 1 and Unit 2 Technical Specifications. The changes would restrict the steady-state voltage and frequency limits for standby diesel generator (SBDG) operation to ensure that accident mitigation equipment can perform as designed. The U.S. Nuclear Regulatory Commission (NRC) staff has determined the following requests for additional information (RAI) are needed in order to complete its review.

EEOB 1-1 Regulatory Requirements:

10 CFR, Appendix A of Part 50, General Design Criterion (GDC) 17, Electric Power Systems, requires, in part, that an onsite electric power system and an offsite electric power system be provided to permit functioning of structures, systems, and components (SSCs) important to safety. The safety function for each system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents. The onsite electric power supplies shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure.

The licensee adopted WCAP-17308-NP-A, Revision 0, which states that the allowable range of frequency and voltage when incorporated directly into plant-specific TS SRs, imply that SSCs can function satisfactorily with a frequency variation of plus or minus (+/-) 0.25 percent of the 60 Hz nominal and +/-5 percent variation in the 4160 V nominal voltage. Steady-state DG operation at the extremes of the allowable frequency and voltage limits will have an impact on system design bases, including:

• Performance of safety related systems

• DG loading calculations

• DG fuel oil consumption calculations

• MOV performance Issue:

The LAR states: To maintain desired standby diesel generator (SBDG) operating parameters, the steady-state voltage range was also revised to 4160 +/- 208 volts (+/- 5%). As a final corrective action, STPNOC is pursuing this license amendment request to ensure that the design basis is protected. However, the licensee does not describe what methodology was used for evaluating the SBDG voltage tolerance. Further, the LAR does not include how the voltage tolerance was determined to ensure the functioning of SSCs.

Request:

Based on the above, provide a discussion of the methodology including the assumptions used for evaluating the SBDG voltage tolerance including how it demonstrates that the steady-state voltage values of +/-5 percent of the nominal voltage (4160 +/- 208 volts) provide sufficient capacity and capability to assure functioning of SSCs.

EMIB 1-1

Background:

Insufficient net positive suction head (NPSH) margin can result in pump cavitation and pump performance degradation. Changes in pump frequency affect the available and required NPSH. Therefore, the proposed frequency tolerance might affect the available and required NPSH of the affected pumps. The licensee provided a list of the analyzed pumps in License Amendment Request (LAR) Section 3.0, subsection IST pump curves.

Issue: The licensee did not provide information to describe how the proposed frequency tolerance affects available and required NPSH for the analyzed pumps.

Request: In order to demonstrate that all pumps will continue to perform their design functions with the proposed SBDG frequency tolerance of 60 +/- 0.3 Hertz (Hz) state whether or not there is sufficient margin between the required net positive suction head and available net positive suction head at 59.7 Hz and 60.3 Hz for all pumps evaluated for the LAR.

EMIB 1-2

Background:

The lube oil pump, jacket water pump, and fuel oil primary booster pump are mounted on the SBDG skid and are driven by the SBDG, therefore, these pumps are affected by the proposed frequency tolerance.

Issue: The licensee did not provide information that addresses how the proposed SBDG frequency tolerance affects the performance of the SBDG lube oil pump, jacket water pump, and fuel oil primary booster pump.

Request: In order to demonstrate that the SBDG lube oil pump, jacket water pump, and fuel oil primary booster pump will continue to perform their design functions with the proposed SBDG frequency tolerance of 60 +/- 0.3 Hertz (Hz) state whether or not there is sufficient margin for SBDG operation: (1) for the flow rate at 59.7 Hz and 60.3 Hz; (2) for the discharge pressure at 59.7 Hz and 60.3 Hz; and (3) between the required net positive suction head and available net positive suction head at 59.7 Hz and 60.3 Hz.

EMIB 1-3

Background:

The lower discharge pressures resulting from the proposed lower-end frequency tolerance (59.7 Hz) could cause low pressure switches to trip. Similarly, the higher discharge pressure resulting from the proposed higher-end frequency tolerance (60.3 Hz) could cause relief valves to lift on affected discharge piping.

Issue: The licensee did not provide information that addresses whether the proposed SBDG frequency tolerance will cause low pressure switches associated with skid mounted pumps for the SBDG to trip or relief valves located on the discharge piping of the ECCS pumps and SBDG skid mounted pumps to lift.

Request: Discuss whether or not any low pressure switches associated with skid mounted pumps for the SBDG will trip or whether any relief valves located on the discharge piping of the ECCS pumps and SBDG skid mounted pumps will lift due to the pressures at the low-end (59.7 Hz) and high-end (60.3 Hz) proposed SBDG frequency tolerance. If a low pressure switch will trip or a relief valve will lift, explain how the affected pumps will continue to perform their design functions.

SRXB 1-1 Identify the large- and small-break loss-of-coolant accidents (LOCA), and non-LOCA events in Chapter 15 of the Updated Final Safety Analysis Report (UFSAR) that have analyses crediting the equipment, systems or components that are powered by the SBDG for operation.

SRXB 1-2 For each of the events identified in above item 1, identify the equipment, systems, or components (such as the safety isolation valves, pumps and fans for safety injection (SI),

auxiliary feedwater (AFW), containment fan coolers (CFC), and containment spray (CS), etc.)

that are powered by the SBDG and credited in the UFSAR Analysis of Record (AOR). The information should include the values (such as flow rates of emergency core cooling system (ECCS) pumps, AFW pumps, CFC pumps, and CS pumps; as well as the safety isolation valve closure time, and power-operated-relief valve (PORV) lifting and closure times, etc.) assumed in the AOR, representing the performance characteristics of the identified equipment, systems or components.

SRXB 1-3 For the input values assumed in the AOR identified in above item 2, provide information to show how those values are impacted by the proposed SBDG voltage and frequency limits conditions.

The information should include: (a) the limiting input values representing the performance characteristics of the equipment, systems, or components that are powered by the SBDG based on the revised TS voltage and frequency limits; a discussion of the methodology used to determine the input values, including the flow rates of the ECCS pumps, AFW pumps, CFC pumps, and CS pumps; as well as the safety isolation valve closure time, PORV lifting and closure times, etc., and (c)the impact of any changes on the AOR.

STSB 1-1 Requirements:

The NRCs regulatory requirements related to the content of the TS are contained in Title 10 of the Code of Federal Regulations (10 CFR) at 10 CFR 50.36. Surveillance requirements (SRs) are located at 10 CFR 50.36(c)(3). Per 10 CFR 50.36(c)(3), SRs are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.

Applicable regulatory guidance is contained in Standard Technical Specifications (STS) for Westinghouse Plants, NUREG-1431, Revision 4 (ADAMS Accession No. ML12100A222).

Additionally as stated on Page 4 of 18 of the enclosure to the LAR STPNOC used WCAP-17308 in conjunction with the NRC Safety Evaluation (ADAMS Accession No. ML17074A112). In STPNOC UFSAR Table 3.12-1 it states that STP complies with Regulatory Guides 1.9, Rev. 2 (ADAMS Accession No. ML12305A253), with an exception identified in UFSAR paragraph 8.3.1.2.3.

Background

In the STPNOC proposed markups of LAR Enclosure Attachment (1) both existing SR 4.8.1.1.2.a.2 and proposed SR 4.8.1.1.2.a.5 retain the former voltage and frequency tolerance bands of 4160 +/- 416 volts and 60 +/- 1.2 Hz. Neither SR requires DG loading therefore the larger bands sometimes assumed for loading do not apply. SR 4.8.1.1.2.a.2 only contains the old criteria. In WCAP-17308 the voltage and frequency tolerance bands were proposed to be deleted from STS SR 3.8.1.2. While the NRC stated that STS SR 3.8.1.2 was outside the scope of WCAP-17308 it also stated that the existing STS criteria would apply meaning that a voltage and frequency band in agreement with the licensees accident analysis should still be used.

Request:

Explain for each SR in which the previous voltage and frequency band is retained, how testing to the former criteria (i.e., determined to be non-conservative) demonstrates assurance that the necessary quality of systems and components [the SBDGs] is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.

STSB 1-2

[Requirements and Background are the same as STSB 1-1]

Request:

STPNOC proposed a new SR 4.8.1.1.2.a.5 be added. In the LAR STPNOC states (via Table 1) that the current surveillance requirement SR 4.8.1.1.2.a.2 is meant to be equivalent to STS SR 3.8.1.2 (i.e. more frequent or monthly SR, with a modified start allowed by note 3) and that SR 4.8.1.1.2.a.5 is meant to be equivalent to STS 3.8.1.7. However the proposed changes to TS 3.8.1.1, Actions b and c (each comparable to STS 3.8.1, Required Action B.3.2) would appear to indicate that the opposite is true (i.e. SR 4.8.1.1.2.a.5 is meant to be equivalent to STS SR 3.8.1.2). Please explain the apparent discrepancy.