ML24192A326
| ML24192A326 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/12/2024 |
| From: | Palo Verde, AZ |
| To: | William Orders Plant Licensing Branch IV |
| References | |
| Download: ML24192A326 (1) | |
Text
Pre-Submittal Meeting - Relief Request 71 - Resubmission of Relief Request 30 July 12, 2024
2 Agenda Introduction
Background
Code Requirements Alternative Requirements Alternative Justification Duration of Proposed Alternatives Schedule
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Background===
RR30 was approved November 2004 for Palo Verde Units 1, 2, & 3.
This RR was to allow a greater diametral clearance (cMAX) between replacement pressurizer heater sleeves and the heater sheaths as specified by Code Case 1361-2.
The RR was originally approved for the remainder of plant life: prior to seeking license extension.
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4 Code Requirements ASME Section III, Sub-Section NB-3356, Code Case 1361-2 specifies a diametral clearance (cMAX) of 0.045 in. between the pressurizer heater sleeves and heater sheaths.
Simplified diagram
5 Palo Verde replaced the original Alloy 600 pressurizer heater sleeves with Alloy 690 sleeves in the fall refueling outages of 2003 (Unit 2), 2004 (Unit 3), and 2005 (Unit 1).
It was determined that the diametral clearances between the replacement Alloy 690 pressurizer heater sleeves and the heater sheaths may be as great as 0.062 inch.
Therefore, pursuant to 10 CFR 50.55a(a)(z)(1) APS proposes an alternative of 0.062 inch in lieu of the 0.045 inch cMAX diametral clearance specified in Code Case 1361-2.
Alternative Requirements
6 Alternative Justification Original Evaluation Structural Integrity Associates evaluated the stresses on the fillet weld with a diametral clearance of 0.062 inches (0.055-inch nominal)
The results of the SI evaluation demonstrate compliance with the ASME Code NB-3220 allowables for Primary Membrane, Primary Membrane plus Bending, Primary plus Secondary and Fatigue stresses.
The SI evaluation considered a 60-year life in the original stress analysis.
7 Alternative Justification Updated Evaluation All original analysis from SI is still valid (previous slide)
An Environmentally Assisted Fatigue (EAF) screening is required for RCS pressure boundary components monitored for fatigue for license extension commitments.
Environmentally Assisted Fatigue (EAF) analysis by SI identified the bounding components that must be managed for EAF during the period of extended operation.
Analysis concluded that all components in the specified thermal zone -including the heater sheath to sleeve weld - remain within EAF limits through 60 years of operation.
8 Duration of Proposed Alternatives The proposed alternative is requested to continue through initial license extension for PVNGS Units 1, 2, and 3.
These dates are (midnight of)
Unit 1: June 1, 2045 Unit 2: April 24, 2046 Unit 3: November 25, 2047
9 Schedule APS is planning to submit in July 2024 NRC Approval is requested by May 2025.
Questions