ML23146A014

Discussion Topics for the May 31, 2023, Public Meeting on MRP-227, Rev. 2, Pressurized Water Reactor Internals Inspection and Evaluations Guideline, Review

ML23146A014
Person / Time
Site:	Electric Power Research Institute
Issue date:	05/31/2023
From:	Licensing Processes Branch
To:
References
MRP-227, Rev 2, EPID L-2022-TOP-0029
Download: ML23146A014 (2)

Text

Discussion Topics for MRP-227, Rev. 2, Pressurized Water Reactor Internals Inspection and Evaluations Guideline, Review May 31, 2023 Group 1: Recent Operating Experience Topic 1: New operating experience (OpE) - Westinghouse Electric Company (WEC)-

design core barrel upper girth weld (UGW) cracking (H.B. Robinson OpE)

There is recent OpE of UGW cracking which is not reflected in the topical report (TR) (occurred after the TR was submitted). UGWs were categorized as expansion in MRP-227, Rev. 1-A.

The basis for this categorization - that upper flange welds would develop cracking prior to the UGWs, is not supported by the OpE. Considering the recent OpE, describe industry plans for addressing the UGW OpE with regards to the TR Topic 2: New operating experience - WEC-design clevis insert cracking There is recent OpE of clevis insert base metal cracking which is not reflected in the TR (Item W14, Table 49) (occurred after the TR was submitted). ASME Section XI requires 10-Year VT-3 visual inspections of WEC-design clevis insert assemblies. Considering the recent OpE, describe industry plans for addressing the clevis insert cracking (including base metal) OpE with regards to the TR.

Group 2: For Discussion Topic 3: B&W Core Barrel (CB) Welds - RAIs MRP-227-B&W-2, MRP-227-B&W-3, and MRP-227-B&W-4 The response to RAI MRP-BAW-2 regarding Item B20 states, in part:

A cumulative usage factor (CUF) calculation, considering the entire CB cylinder (flanges, cylinders, vertical, and circumferential seam welds),

would be performed; for example, as was done for Oconee Nuclear Station (ONS) subsequent license renewal application (SLRA)

(Reference 8). Therefore, if the calculated CUF value meets the acceptance criteria, the entire CB does not need to be examined for fatigue, regardless of accessibility considerations.

This response is an adequate description of the analysis scope for the CB. Was it intended that the additional scope of this alternative CUF evaluation (e.g., cylinders, vertical, and circumferential seam welds) would be added to Table 4-1? Is there a basis for not having the vertical and circumferential seam welds as expansion components for Item B20?

Updated Expansion Table 4-4 has Notes 8, 9 and 10 associated with CB top and bottom flange circumferential welds, all vertical seam welds, and the center circumferential weld.

Notes 8, 9 and 10 in MRP-227, Rev. 2 are associated with bolts, not these welds. What

is the text for these notes that is applicable to the CB expansion components? Updated Table 4-1 has changed the Notes for Items B16 and B17 from Notes 17 and 18 to Notes 9 and 10 - was this intended?

Updated Table 4-1 and Table 4-4 Items B16 and B17, and their subparts, only impacting Davis-Besse (e.g., will result in inspections at Davis-Besse) based on the results of the Primary Component inspections for ONS-2 and ANO-1. What is the precedent and/or basis for inspections at one plant based solely on the inspection results from another site or sites? Generally, this approach could be acceptable to multi-unit sites where the plant characteristics related to operation and fabrication details are consistent and the owner controls the inspection of all units, but that is not the case in this instance. For example, inspections of the Primary Components at ONS-2 and ANO-1 may not occur for a variety of reasons, and thus there would be no validation confirming no need for inspections at Davis-Besse. What provisions in MRP-227, Rev. 2 are there for a plant (e.g., Davis-Besse) to perform inspections if other plants (e.g., ONS-2 or ANO-1) do not implement their inspections?

Topic 4: Table 4-2, Item C12 for lower support structure deep beams Staff noted that Item C12 (lower support structure deep beams) in Table 4-2 identified the degradation mechanisms as cracking (SCC [stress corrosion cracking], IASCC, fatigue) that results in detectable surface breaking indication in the welds or beams. The examination method/frequency column for C12 in Table 4-2 states, Enhanced visual (EVT-1) examination, no later than two refueling outages from the beginning of the license renewal period.

Subsequent examination at a 10-year interval if adequacy of remaining fatigue life cannot be demonstrated.

Staff interpret this to mean that the subsequent examination at a 10-year interval would occur unless the adequacy of remaining component life is demonstrated through a fatigue analysis that would also address the effects of SCC and IASCC.

Is the staff interpretation consistent with the intent of the text for C12 in the TR?

Topic 5: WEC CRDM thermal sleeve degradation experience - related to New Items W21a and W21b for thermal sleeves in Table 4-9 New line Item W21a in the TR for managing wear in the thermal sleeves cites use of an unreviewed examination method in PWROG-16003-P. Since this report has not been reviewed and approved by the staff, the staff expects that the examination method will not be implemented prior to review and approval by the staff.

Topic 6: Non-Qualified Visual Methods for CE-design tie rods and nuts Staff interpret the non-qualified procedures for CE-design tie rods and nuts (C18 in Table 4-2) to mean that non-certified plant personnel would be performing the inspection. Discuss whether this is correct with additional detail, if possible. Include topics such as whether there would be any preparation of the staff prior to the inspection.