ML23334A007

NRR E-mail Capture - Palo Verde 1, 2, and 3 - Official RAIs for LAR That Revises TSs 3.5.1, SITs - Operating; 3.5.2, SIT Shutdown; 3.6.5, Containment Air Temperature; and SRs for TS 3.5.1, SITs Operating

ML23334A007
Person / Time
Site:	Palo Verde
Issue date:	11/29/2023
From:	Siva Lingam NRC/NRR/DORL/LPL4
To:	Cox M Arizona Public Service Co
References
L-2023-LLA-0098
Download: ML23334A007 (5)

Text

From: Siva Lingam Sent: Wednesday, November 29, 2023 9:03 PM To: Matthew.Cox@aps.com Cc: Jennifer Dixon-Herrity; Jennie Rankin; Phillip Sahd; Ahsan Sallman; Jo Ambrosini (She/Her); Derek Scully; Matthew Hamm

Subject:

Palo Verde 1, 2, and 3 - Official RAIs for LAR that Revises TSs 3.5.1, SITs -

Operating; 3.5.2, SIT Shutdown; 3.6.5, Containment Air Temperature; and SRs for TS 3.5.1, SITs Operating (EPID L-2023-LLA-0098)

By letter dated June 29, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23180A222), Arizona Public Service Company (the licensee) submitted a license amendment request (LAR) for U.S Nuclear Regulatory Commission (NRC) approval for Palo Verde Nuclear Generating Station, Units 1, 2, and 3 (Palo Verde, PVNGS), by requesting the following changes:

• Surveillance Requirement (SR) 3.5.1.2 for Technical Specification (TS) 3.5.1, Safety Injection Tanks (SITs) - Operating,

• SR 3.5.2.2 for TS 3.5.2, Safety Injection Tanks (SITs) - Shutdown,

• Limiting Condition for Operation (LCO) for TS 3.5.2, and

• LCO for TS 3.6.5, Containment Air Temperature.

The LAR proposes to revise the Palo Verde current licensing basis to express the SIT volumes in cubic feet (ft3) instead of percent level and proposes adjustments to the containment air temperature values to eliminate incorporation of margin between the design values and the TS values. After reviewing the enclosure of the licensees letter dated June 29, 2023, the NRC staff requests the licensee to provide responses to the following official requests for additional information (RAIs). Note that we transmitted draft RAIs to you on October 5, 2023, scheduled the clarification call at your request on November 6, 2023, which was cancelled due to Unit 1 outage conflict, and eventually held a clarification call on November 28, 2023, to discuss the draft RAIs. As mutually agreed during this clarification call, please provide your responses to these official RAIs by January 19, 2024.

The principal design criteria for Palo Verde were developed in consideration of the seventy General Design Criteria (GDC) for nuclear power plant construction permits proposed by the Atomic Energy Commission in a proposed rulemaking published for Title 10 of the Code of Federal Regulations (10 CFR) Part 50 in the Federal Register of July 11, 1967. The principal design criteria from the Palo Verde Updated Final Safety Analysis Report (UFSAR) section 3.1 that is applicable is referred to in the regulatory basis for the RAIs given below.

SNSB RAI-1

Regulatory Basis:

The following 10 CFR Part 50, Appendix A, General Design Criteria (GDC) are applicable:

• GDC 16, Containment design, as it relates to providing a reactor containment and associated systems to establish an essentially leak-tight barrier against the uncontrolled release of radioactivity to the environment and to assure that the containment design conditions important to safety are not exceeded for as long as postulated accident conditions require.

• GDC 38, Containment heat removal, as it relates to providing a system to remove heat from the reactor containment whose safety function is to reduce rapidly, consistent with the functioning of other associated systems, the containment pressure and temperature following any loss-of-coolant accident (LOCA) and maintain them at acceptably low levels.

• GDC 50, Containment design basis, as it relates to designing the reactor containment structure, including access openings, penetrations, and the containment heat removal system so that the containment stru cture and its internal compartments can accommodate, without exceeding the design leakage rate and with sufficient margin, the calculated pressure and temperature conditions resulting from any LOCA.

RAI:

Palo Verde UFSAR, Table 6.2.1 -7, Engineered Safe ty Systems Operating Assumptions for Containment Peak Pressure Analysis - at 102% of 3990 (ML23181A166), states that for containment peak pressure analysis inputs at 102% of 3990 megawatts thermal (MWt), the SIT volume is 1914 ft3/tank.

(a) As noted in UFSAR, Table 6.2.1-7, the containment response in the current licensing basis (CLB) is based on SIT volume, which is different from either the minimum or the maximum volumes specified in the proposed LCOs 3.5.1 and 3.5.2. Provide impact on the peak pressure, peak vapor temperature, and peak sump temperature containment analysis of record based on the most conservative value of the SIT volumes proposed in LCOs 3.5.1 and 3.5.2.

(b) From the containment peak pressure and peak temperature response standpoint, what is the most conservative SIT volume and explain why it is conservative for both operating and shutdown conditions.

(c) In case it is determined there is no impact on the containment pressure and temperature response, provide a technical justification that the currently used SIT volume 1914 ft3/tank is most conservative.

SNSB RAI-2

Regulatory Basis:

Same as in SNSB RAI -1

RAI:

The current TS values in volumetric units for LCO 3.5.2 are a minimum of 1029.2 ft3 and a maximum of 1914 ft 3 for four operable SITs and a minimum of 1451.5 ft3 and a maximum of 1914 ft3 for three operable SITs. In the proposed TS change, these values are a minimum of 908 ft3 and a maximum of 2000 ft3 for four operable SITs and a minimum of 1361 ft3 and a maximum of 2000 ft3 for three operable SITs.

(a) What is the technical basis for 908 ft3 and 2000 ft3?

(b) Provide the key features of the safety analysis (such as inputs, assumptions, methodology, and results) which includes the 908 ft3 and 2000 ft3.

SNSB RAI-3

Regulatory Basis:

Same as in SNSB RAI-1

RAI:

The LAR, section 3.2 states:

NUREG-1432, Standard Technical Specifications [STS], Combustion Engineering Plants, Revision 5.0, Volume 1, Specifications (ML21258A421), lists the LCO 3.6.5, Containment Air Temperature (Atmospheric and Dual), containment average air temperature limit as a bracketed value of 120° F. The intent of the STS is that the initial containment air temperature in the LCO be the design-basis accident analytical limit for containment average air temperature.

The initial pre-accident containment air temperature of 120° F is used in the Palo Verde design-basis accident analyses for both LOCAs and main steam line breaks (MSLBs). However, the current Palo Verde TS LCO 3.6.5 indicated limit is stated as less than or equal to 117° F instead of 120° F. The TS LCO 3.6.5 limit of 117° F has been derived to account for instrument uncertainties, which ensures the analytical limit of 120° F will not be exceeded. This LAR proposes to restore the Palo Verde LCO 3.6.5 value to of less than or equal to 120° F to be consistent with the intent of the STS and Palo Verde design-basis accident analytical limits for containment average air temperature.

The STS 3.6.5 bracketed containment temperature [120° F] is a generic value. For using it as plant specific in Palo Verde TSs, demonstrate that by applying 120° F (plus uncertainties) as an initial containment temperature along with the same other CLB inputs and assumptions, the containment response analysis results remain bounded by the co ntainment design pressure, temperature, and the equipment qualification profile.

SNSB RAI-4

Regulatory Basis:

Same as in SNSB RAI-1

RAI:

The LAR Section 2.1.2 states:

This change will more accurately describe the design/analysis limit in the TS and will also allow for future revision to the surveillance procedures to specify the TS SRs 3.5.1.2 and 3.5.2.2 SIT level requirements in terms of either narrow range instrumentation percent or wide range instrumentation percent. This will provide operational flexibility, while still maintaining the current safety analyses requirements and associated SIT level limits and controls. This control would be within the licensee-controlled surveillance procedures, pursuant to 10 CFR 50.59, Changes, tests and experiments, without requiring a formal license amendment. This, in turn, will allow potential PVNGS flexibility while continuing to ensure TS LCO compliance and conformance with the safety analysis.

The LAR Section 2.2.2 states:

The original PVNGS TS LCO limit for containment average air temperature was 120° F but it was changed to 117° F by license amendment (LA) 117 (ADAMS Accession No. ML021720060) The NRC staff safety evaluation documented the basis for this more restrictive change, to include instrument uncertainty in the LCO, as follows from page 51 of the safety evaluation for LA 117:

ITS 3.6.5 CTS LCO 3.6.1.5, containment air temperature, reduced to incorporate instrument uncertainties.

The proposed TS change would revise the maximum containment air temperature from 120° F to 117° F, and would change the related Bases. The licensee's reanalysis noted that as much as 3° F of uncertainty may exist for the instruments that monitor containment air temperature.

The 120° F is the analytical value utilized as an upper bound initial condition in the containment safety analyses and that 3° F has been determined to be an appropriate plant specific value to account for instrument uncertainty. The change to the CTS is needed to ensure that the 120° F upper limit is not exceeded. This change is a result of the licensee's revised analysis which incorporated instrument uncertainties in the analysis.

Provide justification that not including instrument uncertainty in the TS values will have no impact on analytical limits used as inputs in the design basis for both the LOCA analysis and the containment pressure and temperature response analysis and the analysis results as well.

In addition, the NRC staff has an editorial comment for your consideration and corrections as noted below:

In the clean pages, for SR 3.5.1.2, the needs to be on the 2nd line. Sections 3.3.4.b and 3.3.4.d of the TSTF-GG-05-01, Writers Guide for Plant-Specific Improved Technical Specifications, dated June 2005 (attached for your convenience), addresses to need to keep symbols and units on the same line of text as the numbers they address. This is how the TS is formatted in NUREG-1432, the STS consistently cited by the licensee.

Provide the relevant corrected pages per NUREG-1432 along with your RAI responses.

Siva P. Lingam U.S. Nuclear Regulatory Commission Project Manager Palo Verde Nuclear Generating Station, Units 1, 2, and 3 Grand Gulf Nuclear Station Entergy Fleet Location: O-9E22; Mail Stop: O-9E03 Telephone: 301-415-1564 E-mail address: Siva.Lingam@nrc.gov

Hearing Identifier: NRR_DRMA Email Number: 2319

Mail Envelope Properties (SJ0PR09MB61095175AF5351E4B804E631F682A)

Subject:

Palo Verde 1, 2, and 3 - Official RAIs for LAR that Revises TSs 3.5.1, SITs -

Operating; 3.5.2, SIT Shutdown; 3.6.5, Containment Air Temperature; and SRs for TS 3.5.1, SITs Operating (EPID L-2023-LLA-0098)

Sent Date: 11/29/2023 9:02:52 PM Received Date: 11/29/2023 9:02:00 PM From: Siva Lingam

Created By: Siva.Lingam@nrc.gov

Recipients:

"Jennifer Dixon-Herrity" <Jennifer.Dixon-Herrity@nrc.gov>

Tracking Status: None "Jennie Rankin" <Jennivine.Rankin@nrc.gov>

Tracking Status: None "Phillip Sahd" <Phillip.Sahd@nrc.gov>

Tracking Status: None "Ahsan Sallman" <Ahsan.Sallman@nrc.gov>

Tracking Status: None "Jo Ambrosini (She/Her)" <Josephine.Ambrosini@nrc.gov>

Tracking Status: None "Derek Scully" <Derek.Scully@nrc.gov>

Tracking Status: None "Matthew Hamm" <Matthew.Hamm@nrc.gov>

Tracking Status: None "Matthew.Cox@aps.com" <Matthew.Cox@aps.com>

Tracking Status: None

Post Office: SJ0PR09MB6109.namprd09.prod.outlook.com

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