ML24170A996

Response to Second Request for Additional Information to Revise Technical Specifications (TS) 3.5.1, Safety Injection Tanks (Sits) – Operating, TS 3.5.2, Safety Injection Tanks (Sits) – Shutdown a

ML24170A996
Person / Time
Site:	Palo Verde
Issue date:	06/18/2024
From:	Harbor C Arizona Public Service Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
02-08818-CDH/MDD
Download: ML24170A996 (1)

Text

10 CFR 50.90 A member of the STARS Alliance, LLC Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek Cary D. Harbor Senior Vice President Site Operations Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 Mail Station 7605 Tel: 602.397.7036 102-08818-CDH/MDD June  2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 Renewed Operating License Nos. NPF-41, NPF-51, and NPF-74 Response to Second Request for Additional Information to Revise Technical Specifications (TS) 3.5.1, Safety Injection Tanks (SITs)

- Operating, TS 3.5.2, Safety Injection Tanks (SITs) - Shutdown, and TS 3.6.5, Containment Air Temperature By letter number 102-08610, dated June 29, 2023 [Agencywide Documents Access and Management System (ADAMS) Accession No. ML23180A222], Arizona Public Service Company (APS) submitted a license amendment request (LAR) for Nuclear Regulatory Commission (NRC) approval for Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2, and 3. By letter number 102-08734, dated March 6, 2024 (ADAMS Accession No. ML24066A047), APS responded to the Request for Additional Information (RAI) to Revise Technical Specifications (TS) 3.5.1, Safety Injection Tanks (SITs) - Operating, TS 3.5.2, Safety Injection Tanks (SITs) - Shutdown, and TS 3.6.5, Containment Air Temperature.

The NRC staff issued a second RAI to support their review regarding the proposed LAR. A clarifying phone call was held between the NRC staff and APS on 0D\\,

to discuss the additional information needed. The APS response to the second NRC staff RAI, dated May 20, 2024 (ADAMS Accession No. ML24143A111) is provided in the enclosure to this letter.

No new commitments are being made to the NRC by this letter. Should you need further information regarding this letter, please contact Michael D DiLorenzo, Licensing Department Leader, at (623) 393-3495.

I declare under penalty of perjury that the foregoing is true and correct to the best of my knowledge.

Executed on ___June 1, 2024___

(Date)

Sincerely, CDH/MDD/cr Harbor, Cary (Z16762)

Digitally signed by Harbor, Cary (Z16762)

Date: 2024.06.18 11:40:43 -07'00'

102-08818-CDH/MDD ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Second RAI Response - Revise Technical Specifications 3.5.1, 3.5.2 and 3.6.5 Page 2

Enclosure:

Response to Second Request for Additional Information to Revise Technical Specifications (TS) 3.5.1, Safety Injection Tanks (SITs) - Operating, TS 3.5.2, Safety Injection Tanks (SITs) - Shutdown, and TS 3.6.5, Containment Air Temperature cc:

J. D. Monninger NRC Region IV Regional Administrator W. T. Orders NRC NRR Project Manager for PVNGS N. Cuevas NRC Acting Senior Resident Inspector for PVNGS B. D. Goretzki Arizona Department of Health Services - Bureau of Radiation Control

Enclosure Response to Second Request for Additional Information to Revise Technical Specifications (TS) 3.5.1, Safety Injection Tanks (SITs) - Operating, TS 3.5.2, Safety Injection Tanks (SITs) - Shutdown, and TS 3.6.5, Containment Air Temperature

Enclosure Response to Second Request for Additional Information - Revise Technical Specifications 3.5.1, 3.5.2 and 3.6.5 1 of 4 Introduction By letter number 102-08610 dated June 29, 2023, as supplemented by letter number 102-08734 dated March 6, 2024, Agencywide Documents Access and Management System (ADAMS) Accession No. ML23180A222 and ML24066A047, respectively, Arizona Public Service Company (APS) requested Nuclear Regulatory Commission (NRC) approval to modify Palo Verde Nuclear Generating Station (PVNGS) Technical Specifications (TS) 3.5.1, TS 3.5.2, and TS 3.6.5.

After reviewing the enclosures of the APS letters, and in consideration of the information exchanged during a clarification call between the NRC staff and APS, held on May 15, 2024, the NRC staff requested response to the following request for additional information (RAI) via email dated May 20, 2024 (ADAMS Accession No. ML24143A111). This enclosure provides the APS response to the NRC RAI. The NRC request is provided first, followed by the APS response.

NRC RAI The licensee proposes to change TS LCO 3.6.5 from its existing value of 117°F to the design analytical value of 120°F. To justify, in the letter dated March 6, 2024, the licensee stated:

PVNGS Technical Specifications contain both the LCO limit and Surveillance Requirement (SR) which is implemented by the Control Room Operators in accordance with surveillance testing (ST). The ST procedures reflect the total loop uncertainty calculations which specifies the indicated value to provide reasonable assurance that the analytical limit is not exceeded. Therefore, the TS value of 120°F does not account for instrument uncertainty and instead it is controlled within the licensee-controlled TS Bases and surveillance procedures, pursuant to 10 CFR 50.59.

Describe any effects on the safety analyses from the TS value change from 117°F to 120°F and the operator actions taken if the surveillance test containment temperature limit is exceeded.

APS Response Safety Analysis Information The Technical Specification containment average air temperature limitation is an initial condition used in the design basis accident (DBA) analyses that establishes the containment operating envelope for temperature. NUREG-1432, Vol. 1, Standard Technical Specifications for Combustion Engineering Plants [Ref. 1], lists the Limiting Condition for Operation (LCO) 3.6.5, containment average air temperature limit as being a station specific value.

Initially (prior to 1998), the PVNGS Technical Specification utilized the analytical limit for containment average air temperature of d120qF as the station specific value and LCO limit.

However, it was changed to an instrument indicated value of d117qF (subtracting the 3qF instrument loop uncertainty from the analytical limit) under license amendment (LA) 117 (ADAMS Accession Number ML021720060). The LA 117 change was considered administrative in nature as it did not change the initial conditions for containment average air temperature used in the PVNGS safety analyses.

The proposed LAR (ADAMS Accession No. ML23180A222) restores the containment average

Enclosure Response to Second Request for Additional Information - Revise Technical Specifications 3.5.1, 3.5.2 and 3.6.5 2 of 4 air temperature of d 120qF as the LCO limit, reverting to the analytical value instead of an indicated value. As a result, there is no effect on the safety analyses. The assumed initial condition for the design basis events [References 7 through 16] remains unchanged.

There have been several relevant modifications implemented at PVNGS including power uprates and steam generator replacements, however, these modifications and license amendments did not modify the design basis accident analysis analytical containment average air temperature initial condition limit of 120qF. NRC License Amendment Nos. 149 and 157 documented NRC approval of the power uprates and steam generator replacements.

PVNGS Surveillance Test for Containment Average Air Temperature and Operator Actions PVNGS current Technical Specifications [Ref. 2] contains the containment average air temperature LCO limit (d117qF) and Surveillance Requirement (SR) SR 3.6.5.1 which directs Control Room (CR) operators to verify containment average air temperature is within the d117qF limit. The PVNGS surveillance frequency control program (01DP-0RS03) specifies that SR 3.6.5.1 is completed every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The Surveillance Test Frequency Basis states, in part:

The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> frequency of this SR is considered acceptable based on the observed slow rates of temperature increase within containment as a result of environmental heat sources (due to the large volume of containment).

The CR operator uses Surveillance Test (ST) procedures [Refs. 3 - 6] to accomplish the surveillance requirement. The ST procedures acceptance criteria include instrument loop uncertainty which specifies the instrument indicated value to ensure that the analytical limit of 120°F is not exceeded. The ST acceptance criteria is d 117qF, which incorporates instrument loop uncertainty of r 2.7qF, with margin [Ref. 7]. Due to the 3qF instrument loop uncertainty, with margin, included in the ST acceptance criteria, verifying the containment temperature d117qF ensures that the analytical initial condition limit of 120qF will not be exceeded.

There are a total of nine temperature monitors located in the containment. If any single temperature monitor indicates greater than 117qF, the surveillance test procedure directs the operator to take the arithmetical average of at least five temperature monitor indications taken at locations within the containment selected to provide a representative sample of the overall containment atmosphere [Refs. 3-6 and 8]. This average temperature value must be less than or equal to 117qF. The surveillance limit of 117°F, plus 3qF for instrument uncertainty, ensures that the design analytical limit for containment average air temperature of 120°F will not be exceeded.

If the containment average air temperature exceeds the limit of 117qF, in accordance with the surveillance procedures [Refs. 3 - 6], the following actions are performed:

x Notify Shift Manager / Control Room Supervisor immediately.

x Declare the affected component(s) inoperable / nonfunctional.

x Comply with the action requirement of the applicable LCO (LCO 3.6.5 required actions are shown below) o Restore containment average air temperature to within limit (8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />).

Enclosure Response to Second Request for Additional Information - Revise Technical Specifications 3.5.1, 3.5.2 and 3.6.5 3 of 4 o

Required action and associated completion time not met then be in Mode 3 (6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />) and be in Mode 5 (36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />).

After changing the TS LCO 3.6.5 limit back to 120qF, PVNGS surveillance procedures [Ref. 3

- 6] will remain unchanged and continue to verify an indicated temperature limit of 117qF to ensure that TS LCO limit of 120qF will not be exceeded as shown in Figure 1.

Figure 1: Containment Air Temperature Control with Proposed TS LCO Limit of d120qF In addition to the surveillance testing that is performed on a 24-hour frequency, alarms (i.e., alarm response procedure 40AL-9RK7B, Panel B07B Alarm Responses) [Ref. 17] are provided in the control room if any individual containment temperature instrument reading were to exceed 117qF. The alarm response procedure refers the operator to TS LCO 3.6.5.

Certain PVNGS Technical Specifications include a TS limit that is equal to the design analytical limit where the ST verifies the indicated value, accounting for the instrument loop uncertainty. For example, containment pressure LCO 3.6.4 lists the pressure upper limit of d 2.5 psig and the ST procedure [Ref. 3] verifies the pressure of d 1.8 psig, accounting for instrument loop uncertainty. In addition, the TS SR 3.5.5.1 requires the refueling water tank (RWT) temperature shall be maintained t 60qF and d 120qF but the ST procedure [Ref. 3]

verifies the temperature of t 65qF and d 115qF.

Potential future changes in containment temperature instrument uncertainty would require use of the design change process (in accordance with 10 CFR 50, Appendix A, Criterion III, Design Control and the PVNGS Quality Assurance Program Description) which includes revision of loop uncertainty calculations, a 10 CFR 50.59 review and updates to the implementing ST procedures. The revised surveillance value must protect the analytical and proposed TS limit of 120qF.

References

1. NUREG-1432, Revision 5, Volume 1, Standard Technical Specifications-Combustion Engineering Plants

2. PVNGS Technical Specification for Units 1, 2, and 3 through Amendment No. 221

3. PVNGS Procedure 40ST-9ZZM1, Revision 75, Operations Mode 1 Surveillance Logs

Enclosure Response to Second Request for Additional Information - Revise Technical Specifications 3.5.1, 3.5.2 and 3.6.5 4 of 4

4. PVNGS Procedure 40ST-9ZZM2, Revision 54, Operations Mode 2 Surveillance Logs

5. PVNGS Procedure 40ST-9ZZM3, Revision 43, Operations Mode 3 Surveillance Logs

6. PVNGS Procedure 40ST-9ZZM4, Revision 37, Operations Mode 4 Surveillance Logs

7. PVNGS Calculation 13-JC-HC-0203, Revision 2, Containment Temperature Instrument (HCN-T-0037, 0038, 0039, 0040, & 0041) Setpoint and Uncertainty Calculation

8. PVNGS Technical Specification Bases, Revision 78

9. PVNGS Calculation 13-NC-ZC-0206, Revision 9, Loss of Coolant Accident Containment Pressure and Temperature Transient Analysis

10. PVNGS Calculation 13-NC-ZC-0232, Revision 12, Loss of Coolant Accident Pressure and Temperature Containment Analysis for Limiting Case

11. PVNGS Calculation 13-NC-ZC-0238, Revision 7, System Design LOCA Analysis

12. PVNGS Calculation 13-NC-ZC-0233, Revision 6, Main Steam Line Break Inside Containment Pressure and Temperature Analysis for Structure Integrity and Equipment Qualification

13. PVNGS Calculation 13-NC-HJ-0001, Revision 7, Control Room Dose from a LOCA in an Adjacent Unit

14. PVNGS Calculation 13-MC-HC-0001, Revision 4, Containment Building Normal Heat Load Calculation

15. PVNGS Calculation 13-MC-HC-0003, Revision 2, Containment Building CEDM Cooling System Heat Loads

16. PVNGS Updated Final Safety Analysis Report, Revision 22A

17. PVNGS Procedure 40AL-9RK7B, Panel B07B Alarm Responses, Revision 24