Phased Array Ultrasonics (PAUT) Requirements Under ASME Section XI

Procedure qualification usually requires a demonstration on a representative flawed sample, and the scan plan forms part of the approved procedure rather than a field decision. ASME Section XI, enforced by ASME writes and maintains the Code; the U.S.: Two layers, and only the first is employer-based.

An auditor examining PAUT asks for the phased array unit, wedges, encoders, and the calibration blocks used for wedge delay, sensitivity and TCG. Section XI sets the mandatory examination, inspection and testing programme for nuclear reactor facility components in service: which welds and components get examined, by which NDE methods, on what schedule, against which flaw acceptance standards, and how repair and replacement activities are controlled. 10 CFR 50.55a(g)(4) requires inservice examination during successive 120-month inspection intervals to comply with the latest edition and addenda incorporated by reference eighteen months before the interval starts. IWA-2300 governs qualification of NDE personnel including VT-1, VT-2 and VT-3. Mandatory Appendix VII sets training and experience; Mandatory Appendix VIII sets performance demonstration for ultrasonic examination systems, integrating personnel, equipment and procedure into a single qualified entity. The Authorized Nuclear Inservice Inspector verifies completion before the plant returns to service.

Source: 10 CFR 50.55a, full text from the GPO govinfo CFR annual edition, Title 10 Volume 1, revised as of 1 January 2024 — paragraph (a)(1)(ii)(C) listing Section XI Division 1 editions incorporated by reference through the 2019 Edition; (b)(2)(xii) permitting NQA-1 editions specified in Table IWA-1600-1 alongside the licensee's Appendix B programme; (b)(2)(xiv) requiring 8 hours of annual hands-on training on cracked specimens or the Appendix VII VII-4240 annual practice, completed no earlier than 6 months before performing UT; (b)(2)(xv) Appendix VIII specimen set and Supplement conditions; (b)(2)(xviii)(A) requiring Level I and II NDE recertification on a 3-year interval in lieu of the 5-year interval in IWA-2314(a) and (b); (g)(4) successive 120-month inspection intervals updated to the edition incorporated 18 months before the interval starts; and the IWA-6230 Owner's Activity Report submission within 120 calendar days of each refuelling outage. ASME's own standard page for BPVC Section XI Division 1, 2025 Edition, 'Rules for Inservice Inspection of Nuclear Reactor Facility Components,' confirming the Authorized Nuclear Inservice Inspector role. IWA-2300 personnel provisions, employer sole responsibility for certification and permitted use of outside agencies, and the CP-189 reference in IWA-1600, corroborated against the World Nuclear Association CORDEL report 'Certification of NDE Personnel — Harmonization of International Code Requirements.' PDI ownership by utilities and operation by EPRI corroborated against NRC and PNNL assessment material. Accessed 21 Aug 2026.

Phased Array Ultrasonics under ASME Section XI — procedure, personnel and evidence
Item	What applies	Why it matters
Regime	ASME Boiler and Pressure Vessel Code, Section XI — Rules for Inservice Inspection of Nuclear Reactor Facility Components, made mandatory by 10 CFR 50.55a	Enforced by ASME writes and maintains the Code; the U.S. Nuclear Regulatory Commission makes it mandatory and conditions it through 10 CFR 50.55a. Compliance is verified in the field by the Authorized Nuclear Inservice Inspector
Method	Phased Array Ultrasonics (PAUT)	Needs its own procedure and its own qualified personnel
Procedure approval	The employer's Level III, qualified in this method	The signature an auditor traces
Other methods in scope	UT, Automated and encoded UT, ET including steam generator tube inspection, MT, PT, VT-1, VT-2 and VT-3 visual examination	Each needs separate qualification
Renewal	Two clocks. The programme clock: successive 120-month inspection intervals, each updated to the latest edition and addenda incorporated by reference eighteen months before the interval starts, per 10 CFR 50.55a(g)(4). The personnel clock: 10 CFR 50.55a(b)(2)(xviii)(A) overrides the Code — Level I and II NDE personnel must be recertified on a 3-year interval in lieu of the 5-year interval specified in IWA-2314(a) and IWA-2314(b), for the 2001 Edition through the latest edition incorporated by reference. Appendix VIII qualification carries its own currency requirement, with eight hours of hands-on training on cracked specimens annually, completed no earlier than six months before performing examinations at a licensee's facility.	Applies to the personnel certification behind this method

Does ASME Section XI require a separate procedure for PAUT?

Yes. Every method in scope needs its own written procedure, approved by someone qualified in that method, describing technique, equipment, calibration, scanning or coverage, acceptance criteria and reporting. A single combined "NDT procedure" covering several methods is a finding under every regime that names procedures individually.

Who can approve a PAUT procedure under ASME Section XI?

A Level III qualified in PAUT. Because ASME Section XI accepts employer-based certification, that Level III may be contracted rather than employed — but their own qualification must cover PAUT, and an auditor will check that before accepting the signature.

What PAUT records does a ASME Section XI audit sample?

The approved procedure, the technician's PAUT certification on the date of work, and the equipment evidence — the phased array unit, wedges, encoders, and the calibration blocks used for wedge delay, sensitivity and TCG. The auditor works backwards from a finished job, so every item has to reconcile with the report and its stated acceptance criteria.

What is the most common PAUT finding at audit?

Data acquired outside the scan plan the procedure qualified, or encoder position not recorded. It is a records failure rather than a technique failure — the examination was performed correctly and the evidence supporting it cannot be produced, which under ASME Section XI is recorded the same way as not having done the work.

Can a technician certified elsewhere perform PAUT under ASME Section XI?

Not automatically. Employer-based certification ends when the holder leaves, so the new employer must certify them under its own written practice. Prior training and documented experience transfer as evidence; the certificate itself does not.

What equipment evidence does PAUT need under ASME Section XI?

Calibration status traceable to the day of use, covering the instrument and its accessories — probes, cables, blocks and reference standards for ultrasonics; sources and densitometers for radiography. An in-calibration instrument with an out-of-calibration reference block fails the same way as an uncalibrated one.

How do PAUT requirements differ from the other methods in ASME Section XI?

Scope, qualification and evidence are method-specific, so the differences are real rather than administrative. ASME Section XI also covers UT, Automated and encoded UT, ET including steam generator tube inspection, MT, PT, and each carries its own procedure, its own personnel qualification and its own equipment evidence.

Personnel certification for PAUT

Two layers, and only the first is employer-based. For basic qualification, Section XI is employer-certified: IWA-2300 requires certification under a written practice to ASNT SNT-TC-1A or ANSI/ASNT CP-189 as referenced in IWA-1600, the employer is solely responsible for certifying Levels I, II and III, and outside agencies may be used to qualify NDE personnel — so an outsourced Level III can own the written practice and sign as the technical authority. The second layer is not employer-based: ultrasonic examinations covered by Mandatory Appendix VIII require a performance demonstration, in practice through the utility-owned, EPRI-operated Performance Demonstration Initiative. No written practice substitutes for a failed PDI demonstration.