ML22096A006

Reactor Pressure Vessel Inservice Inspection Requirements in the U.S

ML22096A006
Person / Time
Issue date:	04/11/2022
From:	Michael Benson NRC/NRR/DNRL/NVIB
To:
Benson M, (301) 415-2425
References
Download: ML22096A006 (15)

Text

Reactor Pressure Vessel Inservice Inspection Requirements in the U.S.

Michael L. Benson U.S. Nuclear Regulatory Commission International ISI Workshop April 11-14, 2022 Virtual Workshop ML22096A006

Regulations vs. Consensus Standards

• Inservice inspection requirements for U.S. nuclear power plants are set forth in Title 10 of the Code of Federal Regulations 50.55a (10 CFR 50.55a)

• American Society of Mechanical Engineers (ASME) Boiler

& Pressure Vessel Code,Section XI, Division 1 (BPV XI) is incorporated by reference (IBR) in 10 CFR 50.55a

• The rules of BPV XI, therefore, become law subject to conditions in 10 CFR 50.55a(b)(2) upon IBR 4/12/2022 2

Rules of BPV XI, Subsection IWA (2021 Edition)

• General requirements applicable to all examination activities under BPV XI

• Programmatic in nature

• IWA-2400 requires an inservice inspection (ISI) program consisting of plans and schedules

• Interval dates and inspection periods

• Applicable Edition and Addenda of BPV XI

• An ISI interval is a time period during which all the examination requirements of BPV XI must be met (see IWA-2430(a))

• The current BPV XI ISI interval is 10 years 4/12/2022 3

Rules of BPV XI, Subsection IWB (2021 Edition)

• Examination requirements for ASME Class 1 components

• Table IWB-2500-1 provides a complete listing of components in scope of BPV XI and defines required method, extent, and frequency of the exam.

• Organized according to Examination Categories

• Each category is organized according to Item Numbers

• Figures in IWB illustrate applicable weld geometries and exam volumes 4/12/2022 4

Rules of BPV XI, Subsection IWB (2021 Edition)

• Examination Category B-A, Pressure Retaining Welds in Reactor Vessel

• Item Nos. B1.10-B1.12: vessel shell welds

• Item Nos. B1.20-B1.22: vessel head welds

• Item No. B1.30: shell-to-flange weld

• Item No. B1.40: head-to-flange weld

• Item No. B1.50-B1.51: repair welds 4/12/2022 5

Rules of BPV XI, Subsection IWB (2021 Edition)

• Examination Category B-D, Full Penetration Welded Nozzles in Vessels

• Item Nos. B3.90: nozzle-to-vessel welds

• Item Nos. B3.100: nozzle inner radius section 4/12/2022 6

BPV XI Rules for Items B1.10-B1.12 (2021 Edition)

• Circumferential and longitudinal reactor vessel shell welds

• Method: Volumetric exam

• Frequency: Once during the first ISI interval and each successive interval

• Extent: All welds, essentially 100% of defined volume

• Essentially 100%: IWA-2200(c) - greater than 90% of the defined volume 4/12/2022 7

BPV XI Rules for Items B1.20-B1.22 (2021 Edition)

• Circumferential and meridional reactor vessel head welds

• Method: Volumetric exam

• Frequency: Once during the first ISI interval and each successive interval

• Extent: Accessible length of all welds, essentially 100% of defined volume 4/12/2022 8

BPV XI Rules for Item B1.30 (2021 Edition)

• Reactor vessel shell-to-flange weld

• Method: Volumetric exam

• Frequency: Once during the first ISI interval and each successive interval

• Extent: Essentially 100% of the defined volume 4/12/2022 9

BPV XI Rules for Item B1.40 (2021 Edition)

• Reactor vessel head-to-flange weld

• Method: Volumetric and surface exam

• Surface exam only may be used if a pervious volumetric exam did not detect a flaw that exceeds acceptance criteria

• Frequency: Once during the first ISI interval and each successive interval

• Extent: Essentially 100% of the defined volume 4/12/2022 10

BPV XI Rules for Items B1.50-B1.51 (2021 Edition)

• Repair welds exceeding 10% of the nominal wall thickness

• Method: Volumetric and surface exam

• Surface exam only may be used if a previous volumetric exam did not detect a flaw that exceeds acceptance criteria

• Frequency: Once during the first ISI interval and each successive interval

• Extent: Essentially 100% of the defined volume 4/12/2022 11

BPV XI Rules for Item B3.90 (2021 Edition)

• Nozzle-to-vessel welds

• Method: Volumetric

• Frequency: Once during the first ISI interval and each successive interval

• Extent: All nozzles, essentially 100% of the defined volume

• IWB-2500(f) allows 25% sample, as opposed to all nozzles 4/12/2022 12

BPV XI Rules for Item B3.100 (2021 Edition)

• Reactor vessel nozzle inside radius

• Method: Volumetric

• Frequency: Once during the first ISI interval and each successive interval

• Extent: All nozzles, essentially 100% of the defined volume

• IWB-2500(f) allows 25% sample, as opposed to all nozzles

• IWB-2500(g) allows visual exam in lieu of the volumetric exam, under certain conditions 4/12/2022 13

Related Conditions in 10 CFR 50.55a(b)(2)

• (xvi), (xviii), (xix), (xxii), and (xxiv) are miscellaneous conditions related to nondestructive examination

• (xxi)(B) conditions on use of IWB-2500(f) and (g)

• Requires a plant-specific evaluation

• Not permitted for plants with a renewed license

• Not permitted for newer plants licensed under 10 CFR 52 4/12/2022 14

Summary

• ASME BPV XI, Subsection IWB, Categories B-A and B-D

• Conditions on ASME BPV XI in 10 CFR 50.55a(b)(2)

• Related items

• RPV-related Code Cases

• Alternatives under 10 CFR 50.55a(z) 4/12/2022 16