NQA-1 (ASME Nuclear Quality Assurance-1) is the primary quality assurance standard for nuclear facility applications published by ASME. It defines 18 requirements covering design control, procurement, fabrication, inspection, testing, nonconformance control, corrective action, documentation, and audits.

Is NQA-1 a legal requirement?

NQA-1 is a consensus standard, not a law, but it is the accepted means of demonstrating compliance with 10 CFR 50 Appendix B (the NRC regulation for US nuclear plants) and is referenced in Canadian standards including CSA N286 and CSA N299. Most NRC-licensed plants and Canadian CNSC-licensed facilities are required to operate under a QA program that meets NQA-1 or an equivalent.

What is the difference between NQA-1 and 10 CFR 50 Appendix B?

10 CFR 50 Appendix B is the NRC regulation, it sets the mandatory criteria. NQA-1 is the industry consensus standard that explains how to implement a quality assurance program that satisfies those criteria. Appendix B tells you what you must achieve; NQA-1 tells you how.

What is NQA-1? ASME Nuclear Quality Assurance Standard Explained

NQA-1, formally titled Quality Assurance Requirements for Nuclear Facility Applications, is published by ASME (American Society of Mechanical Engineers) and is the foundational QA standard for nuclear facilities across North America. It defines not just what a quality program must accomplish, but how it must be structured, documented, and verified.

What NQA-1 covers

NQA-1 is organized into four parts. Part I contains the 18 basic QA program requirements. Part II contains supplementary requirements for specific applications. Part III provides guidance for implementing Parts I and II, and Part IV provides guidance on applying and using NQA-1. ASME’s published contents identify these four parts. The applicable edition and requirements follow the organization’s QA commitments and procurement documents.

The 18 Basic Requirements in Part I cover every phase of quality-related activity in a nuclear program:

Req. 1 Organization
Req. 2 Quality Assurance Program
Req. 3 Design Control
Req. 4 Procurement Document Control
Req. 5 Instructions, Procedures & Drawings
Req. 6 Document Control
Req. 7 Control of Purchased Items & Services
Req. 8 Identification & Control of Items
Req. 9 Control of Special Processes
Req. 10 Inspection
Req. 11 Test Control
Req. 12 Control of Measuring & Test Equipment
Req. 13 Handling, Storage & Shipping
Req. 14 Inspection, Test & Operating Status
Req. 15 Control of Nonconforming Items
Req. 16 Corrective Action
Req. 17 Quality Assurance Records
Req. 18 Audits

The graded approach: NQA-1 permits organisations to apply its requirements commensurate with the relative importance of an item or activity to safety, more rigour for safety-critical components, less for items with no safety function. This is known as the graded approach.

NQA-1 vs. 10 CFR 50 Appendix B

The relationship between NQA-1 and 10 CFR 50 Appendix B is often misunderstood. Appendix B is a regulation, it is the NRC’s legally binding list of 18 quality assurance criteria that every US nuclear power plant must satisfy. NQA-1 is an industry consensus standard that tells programs how to implement those criteria in practice.

Put simply: Appendix B says what you must achieve. NQA-1 says how to achieve it. The NRC has long treated NQA-1 as the accepted means of demonstrating compliance with Appendix B, and the two standards are closely aligned, their 18 requirements and 18 criteria map to one another almost exactly.

Applicability in Canada

NQA-1 is not a Canadian regulation, but it is widely used by Canadian nuclear facilities and suppliers, particularly those in the supply chain for US programs or those procuring from American suppliers. Canadian nuclear facilities use CSA N286 (management systems) and CSA N299 (quality assurance for procurement), both of which are aligned with the same principles as NQA-1.

CSA N299 qualification does not establish NQA-1 compliance automatically. Suppliers serving both markets should compare the applicable editions and customer requirements, document gaps, and agree the required qualification scope with each purchaser.

Where to look first

Four requirements are worth checking first, because each depends on records that go stale between audits: Requirement 15 (Control of Nonconforming Items), where NCRs sit without dispositions; Requirement 16 (Corrective Action), where cause analyses are thin or actions stay open past their due dates; Requirement 7 (Control of Purchased Items and Services), where supplier evaluations lapse; and Requirement 6 (Document Control), where people work from superseded revisions.

When qualification records, NCR status and corrective action due dates live in separate spreadsheets, these gaps stay hidden until an auditor finds them. The NQA-1 audit checklist lists the questions and records to check for all 18 requirements.

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References

American Society of Mechanical Engineers. ASME NQA-1-2022: Quality Assurance Requirements for Nuclear Facility Applications. New York: ASME, 2022.
U.S. Nuclear Regulatory Commission. "Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants." Code of Federal Regulations, 10 CFR 50 Appendix B. Washington, D.C.: NRC.
U.S. Nuclear Regulatory Commission. Regulatory Guide 1.28: Quality Assurance Program Criteria (Design and Construction), Revision 4. Washington, D.C.: NRC, June 2010.
U.S. Nuclear Regulatory Commission. Regulatory Issue Summary 2012-08: Clarification of Applicability of ASME NQA-1-2008 with Addenda NQA-1a-2009 to 10 CFR Part 50 Appendix B and 10 CFR Part 21 Programs. Washington, D.C.: NRC, 2012.