An inquiry package arrives for a shell-and-tube exchanger. The data sheet is unremarkable: 316L, TEMA R, ASME Section VIII, Division 1 — a duty a shop has run a hundred times. Behind it sits a supplier quality requirements attachment running dozens of pages. It invokes a quality assurance standard, hold points, submittals for approval, and a records package due before the unit ships.
The exchanger is ordinary. The obligations attached to it are what separate bidders who can execute from bidders who find out during fabrication.
TL;DR
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ASME NQA-1 is a nuclear quality assurance standard. It sets requirements for quality assurance programs, not rules for designing or building equipment.
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NQA-1 and 10 CFR Part 50, Appendix B govern quality assurance. ASME construction codes govern how equipment is designed and built. Neither substitutes for the other.
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Heat number traceability is a requirement, not simply a good practice. Appendix B Criterion VIII requires identification "by heat number, part number, serial number, or other appropriate means."
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Classification determines which controls apply, not the fact that equipment sits at a nuclear facility. RG 1.26, Revision 6 assigns ASME Section VIII, Division 1 to Quality Group D pressure vessels.
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An ASME Code stamp and an NQA-1 program are different things. Neither implies the other.
On this page: what NQA-1 is · regulations and codes · which equipment is affected · what changes in the shop · material traceability · common mistakes · FAQs
What is ASME NQA-1?
ASME NQA-1, Quality Assurance Requirements for Nuclear Facility Applications, is a nuclear quality assurance standard. It defines what a quality assurance program must contain and control when an organization supplies items or services that perform a safety function at a nuclear facility.
It is not a design code. The standard says nothing about allowable stress, weld joint efficiency, minimum wall thickness, tube sheet thickness, or nozzle reinforcement. Those rules come from the construction code.
What NQA-1 governs is the program around the work: how requirements reach the shop, how conformance is demonstrated and documented, how deviations are captured, and how the evidence stays retrievable years later. ASME’s published scope for the 2024 edition covers "the establishment and execution of quality assurance programs during siting, design, construction, operation and decommissioning of nuclear facilities." Facilities in scope include "nuclear power plants (NPP), small modular reactors (SMR), and advanced reactors."
The 18 Requirements and 10 CFR 50 Appendix B
NQA-1 is organized into 18 numbered Requirements. They track the 18 criteria of Appendix B to 10 CFR Part 50 one for one.
The requirement statements are close enough that fabricators and buyers often treat the two documents as interchangeable in conversation. There are nuances between them that both parties need to understand to establish compliance. Criterion VII, for example, is titled "Control of Purchased Material, Equipment, and Services." The parallel NQA-1 Requirement 7 is "Control of Purchased Items and Services," and the broader term items reaches scope the Appendix B title does not obviously cover.
| Appendix B criteria I–IX | Appendix B criteria X–XVIII |
|---|---|
| I. Organization | X. Inspection |
| II. Quality Assurance Program | XI. Test Control |
| III. Design Control | XII. Control of Measuring and Test Equipment |
| IV. Procurement Document Control | XIII. Handling, Storage and Shipping |
| V. Instructions, Procedures, and Drawings | XIV. Inspection, Test, and Operating Status |
| VI. Document Control | XV. Nonconforming Materials, Parts, or Components |
| VII. Control of Purchased Material, Equipment, and Services | XVI. Corrective Action |
| VIII. Identification and Control of Materials, Parts, and Components | XVII. Quality Assurance Records |
| IX. Control of Special Processes | XVIII. Audits |
Criteria titles per 10 CFR Part 50, Appendix B. NQA-1 Part I organizes its 18 Requirements against these same subjects.
Two definitions explain why the program is built this way. Appendix B describes quality assurance as "all those planned and systematic actions necessary to provide adequate confidence that a structure, system, or component will perform satisfactorily in service." NQA-1 ties that confidence to an item’s safety function — the performance required of an item or service to achieve safe and reliable use of nuclear energy and processing of nuclear material.
In both cases the confidence has to be demonstrable to someone who was not there. That is why documentation carries so much weight in nuclear work. A well-made weld with no record and a defective weld with no record look identical to an auditor a decade later, and only one of them can be defended.
How does NQA-1 relate to nuclear regulations and ASME construction codes?
NQA-1 and Appendix B establish quality assurance requirements. ASME construction codes establish requirements for designing and constructing the equipment. They answer different questions. Satisfying one does not satisfy the other, and neither can be substituted for the other.
This is the distinction that causes the most trouble in nuclear procurement. It surfaces because four separate layers of requirement arrive in the same procurement package.
The four requirement layers
| Requirement layer | Examples | What it governs |
|---|---|---|
| Regulatory | 10 CFR Part 50, Appendix A (General Design Criterion 1) and Appendix B; 10 CFR 50.55a; 10 CFR Part 830, Subpart A for DOE nuclear facilities | The quality assurance obligations the owner or contractor owes the regulator, flowed down to suppliers and sub-tier suppliers |
| Quality assurance program | ASME NQA-1, Parts I and II, in the edition the project invokes | How work is planned, controlled, verified, documented, and audited |
| Design and construction code | ASME BPVC Section III (Classes 1, 2, 3); Section VIII, Division 1 or 2; TEMA; API 620 and 650; ASME B31.1 and B31.3 | How the equipment is designed, fabricated, examined, and tested |
| Owner, EPC, and project-specific | Supplemental supplier quality requirements, inspection and test plan hold points, submittal and records requirements | Project additions that exceed the construction code, Appendix B, and NQA-1 |
The regulatory layer sets the terms for everything below it. Appendix A, General Design Criterion 1, requires that structures, systems, and components important to safety "be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed." That phrase — commensurate with — is why nuclear quality requirements are graded rather than uniform.
NRC requirements: Appendix B and Regulatory Guide 1.28
On NRC-regulated work, NQA-1 is the default quality assurance standard. Regulatory Guide 1.28, Revision 6, issued September 2023, endorses Parts I and II of NQA-1-2017, NQA-1-2019, and NQA-1-2022 as an acceptable way to meet Appendix B, subject to stated exceptions. That endorsement is what puts NQA-1 into most U.S. commercial nuclear specifications.
DOE requirements: 10 CFR Part 830
DOE nuclear facilities operate under a different regulation, and the difference matters when reading a specification. 10 CFR Part 830, Subpart A "establishes quality assurance requirements for contractors conducting activities, including providing items or services that affect, or may affect, nuclear safety of DOE nuclear facilities."
Its criteria at 10 CFR 830.122 are ten performance-based statements rather than Appendix B’s eighteen prescriptive ones. Subpart A does not name NQA-1. DOE contractors invoke it routinely anyway, flowing it down by contract — so on DOE work the applicable standard and edition come from the procurement documents rather than from the regulation.
Why an ASME Code stamp is not an NQA-1 program
An ASME Code Certificate of Authorization and the Certification Mark show that a fabricator’s quality control system was accredited for construction under a specific code section. They do not demonstrate an NQA-1 program.
RG 1.28 is explicit about the limit. NRC recognition of the ASME Accreditation Program "applies only to the programmatic aspects of the QA programs," and purchasers "should ensure that the suppliers are effectively implementing their approved QA programs." The reverse also holds: an NQA-1 program confers no Code stamping authority.
Which nuclear equipment requires these controls?
Classification determines the applicable controls, not the equipment’s location. A common and expensive assumption is that everything destined for a nuclear site carries nuclear quality requirements. It does not.
Appendix B is scoped to safety function. Its "pertinent requirements … apply to all activities affecting the safety-related functions of those structures, systems, and components," and the program must provide control "to an extent consistent with their importance to safety."
10 CFR 50.2 defines safety-related SSCs as those "relied upon to remain functional during and following design basis events" to assure reactor coolant pressure boundary integrity, safe shutdown, or the capability to prevent or mitigate accident consequences. Equipment outside that definition is not free of quality controls. The controls differ in kind, and are usually reduced in rigor.
How quality group classification works
For light-water reactors, classification is expressed through quality groups. RG 1.26, Revision 6 sets out the system and ties each group to a standard.
| Quality group | Scope | Pressure vessel standard |
|---|---|---|
| A | Reactor coolant pressure boundary per 10 CFR 50.55a(c)(1) | ASME Section III, Class 1 |
| B | Excluded from Group A, or in systems important to safety for emergency core cooling, postaccident containment heat removal, or postaccident fission product removal | ASME Section III, Class 2 |
| C | Remaining safety-related water-, steam-, and radioactive-waste-containing components | ASME Section III, Class 3 |
| D | Not in the reactor coolant pressure boundary and not in Groups B or C, but in systems that contain or may contain radioactive material | ASME Section VIII, Division 1 |
Per RG 1.26, Revision 6, Table 1. Group D piping and valves are assigned to ASME B31.1; Group D atmospheric tanks to API 650, AWWA D-100, or ASME B96.1; and Group D tanks from 0 to 15 psi to API 620.
Where fabricated process equipment fits
RG 1.26 names the equipment types directly. Its Group B and Group C positions both apply to "pressure vessels, heat exchangers (other than turbines and condensers), storage tanks, piping, pumps, and valves" meeting the respective criteria.
Shell-and-tube exchangers, tanks, columns, condensers, evaporators, and separators all sit inside this framework somewhere. Where each one lands depends on its function, not its equipment category.
The Group D row is the practical opening for a great deal of fabricated process equipment, because a Section VIII, Division 1 vessel is an NRC-acceptable standard there. Owners may also impose selected NQA-1 requirements on non-safety-related scope by contract, including document control, material traceability, and records. That is why the inquiry documents, rather than the equipment type, determine what a fabricator actually has to do.
What changes in the shop under an applicable NQA-1 program?
Conventional ASME Code fabrication is already tightly controlled. Section VIII, Division 1 construction runs on a written quality control system reviewed by an Authorized Inspector. It requires procedures and welders qualified under Section IX, material certified to Section II specifications, examination by qualified NDE personnel, and a witnessed hydrostatic test before stamping.
An NQA-1 program adds a further layer of planning, verification, and documented evidence on top of that foundation.
| Element | Section VIII, Division 1 quality control system | Added or extended under an applicable NQA-1 program |
|---|---|---|
| Program basis | Written QC system for Code construction, reviewed by the Authorized Inspection Agency | Documented QA program addressing the 18 Part I Requirements, subject to owner or third-party audit |
| Material acceptance | Material certified to the applicable Section II specification | CMTRs with heat traceability, receiving inspection to a written procedure, controlled release before use |
| Traceability | Material identification maintained per Code rules | Documented traceability from mill heat through cutting, forming, welding, and final assembly, recorded on the traveler |
| Procurement | Purchase orders invoking material specifications | Approved supplier list, supplier qualification and periodic evaluation, flow-down of QA requirements to sub-tier suppliers |
| Commercial items | Commercial procurement acceptable within Code rules | Commercial grade dedication where a commercial item performs a safety function, verifying identified critical characteristics |
| Document control | Current drawings and procedures at the work station | Formal revision control with distribution records, superseded document removal, and owner review or approval of designated submittals |
| Inspection planning | Authorized Inspector hold points per the QC system | Written inspection and test plan with owner and third-party witness and hold points, notification lead times, and release signatures |
| Nonconformances | Repairs and rejections handled per the QC system | Documented nonconformance reports with engineering disposition, owner concurrence where required, and trending |
| Corrective action | Addressed within the QC system | Formal corrective action process addressing cause and preventing recurrence |
| Measuring and test equipment | Gauges and instruments calibrated as required | Calibration traceable to national standards, with recall, out-of-tolerance evaluation, and records of use |
| Records | Manufacturer’s Data Report and supporting Code records retained | Defined lifetime and nonpermanent records, controlled storage, and a turnover documentation package delivered to the owner |
| Verification | Authorized Inspector oversight | Independent internal audits, supplier audits, and owner or joint-utility surveillance |
The pattern is consistent across every row. Nuclear fabrication is distinguished less by better welding than by the requirement to demonstrate and document each step: performed to an approved requirement, by qualified people, using calibrated equipment, with every deviation captured and dispositioned.
Appendix B Criterion IX puts it in its own terms. Special processes, "including welding, heat treating, and nondestructive testing, are controlled and accomplished by qualified personnel using qualified procedures." Every verb in that clause concerns control rather than skill.
Material traceability in nuclear fabrication
Traceability is a requirement, not a matter of good housekeeping, and it is where these controls become concrete on the shop floor.
Appendix B Criterion VIII requires measures for "the identification and control of materials, parts, and components, including partially fabricated assemblies." Those measures must "prevent the use of incorrect or defective material, parts, and components." Identification is maintained "by heat number, part number, serial number, or other appropriate means, either on the item or on records traceable to the item."
Criterion VII adds the delivery-side obligation. Documentary evidence of conformance "shall be available at the nuclear power plant or fuel reprocessing plant site prior to installation or use of such material and equipment." A records package is therefore a contractual deliverable, not paperwork assembled at the end.
How traceability survives fabrication
Traceability is a chain, and it has to hold at every transfer. Follow a single plate heat entering the shop for a vessel shell:
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Certification. The mill issues a Certified Material Test Report (CMTR) identifying the specification and grade, heat number, chemical analysis, and mechanical test results.
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Receiving inspection. A written procedure verifies the CMTR against the purchase order, and the marking on the plate against the CMTR. Material is released to production only after acceptance.
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Identification transfer. When the plate is cut, the heat number carries to every piece — by stamping where the specification permits it, by a marking method suited to thin or corrosion-sensitive material where it does not, and by a documented transfer record wherever forming or machining will remove the mark.
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Traceability through fabrication. As the piece is formed, fitted, and welded, the traveler ties that heat to the weld records, the filler metal heat or lot, the examination reports, and any heat treatment.
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Final documentation. The completed package maps each heat to its location in the finished equipment. A reviewer can start from any weld or component and trace back to the mill certification.
Step 3 is a critical point in the traceability chain. Cutting, forming, and machining can remove markings, so the documented transfer matters as much as the original identification.
What positive material identification does and does not do
PMI verifies that the metal in the shop matches what the paperwork says. It is the practical defense against mixed alloys in a shop running many grades. It does not replace a CMTR; it confirms the CMTR belongs to the material on the floor.
One documented case shows why verification is needed alongside certification. NRC Information Notice 2008-04 reported counterfeit stop check valves carrying a recognized manufacturer’s name supplied to a nuclear plant. One was installed on a stator cooling water pump discharge in a non-safety-related system, where it ran eight months before discovery. A second sat in warehouse inventory.
Documentation accompanied those parts the entire time. Paperwork alone could not have caught them.
Common mistakes in nuclear equipment procurement
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Assuming a nuclear site imposes nuclear quality requirements on everything. Appendix B is scoped to activities affecting safety-related functions, and RG 1.26 assigns Section VIII, Division 1 to Quality Group D vessels. Classification comes first.
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Treating an ASME Code stamp as evidence of an NQA-1 program. NRC recognition of ASME accreditation reaches only the programmatic aspects of Code work, and leaves implementation verification with the purchaser.
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Describing equipment as "NQA-1 certified." NQA-1 applies to programs. Equipment is built to a construction code, under a quality assurance program.
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Leaving classification and quality assurance scope out of the inquiry. A bidder who is not told which Requirements apply, which hold points exist, and what records are due will price a different job than the one being bought.
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Discovering documentation requirements after fabrication starts. Traceability that was not recorded at cutting cannot be reconstructed at final inspection. The affected material usually has to be scrapped or re-certified.
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Applying NQA-1 uniformly to avoid making a classification decision. Blanket application raises cost without adding safety margin, and it buries the requirements that actually matter.
Define the scope before the inquiry goes out
Successful nuclear equipment procurement depends less on specification length than on five decisions being stated clearly:
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The equipment’s safety classification, and the basis for it.
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The applicable design and construction code and edition.
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The applicable quality assurance requirements, including the standard, edition, and which Requirements apply.
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The inspection requirements, including witness and hold points and notification lead times.
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The documentation and records requirements, including retention and format.
Those five answers turn an ambiguous inquiry into a biddable scope. They also distinguish the fabricators who understand the obligations from those who have read only the data sheet.
Harris Thermal has an NQA-1 Quality Assurance Program in place to support applicable nuclear and DOE fabrication requirements. The company fabricates ASME Section VIII, Division 1 pressure vessels and tanks, shell-and-tube heat exchangers, columns, evaporators, condensers, and other custom process equipment for nuclear, DOE, and advanced-energy projects.
Which controls apply to a given order still depends on the equipment’s classification, the governing construction code, and the quality assurance and inspection requirements the owner or EPC invokes. The scope is deliberately specific: balance-of-plant and nuclear-adjacent equipment, fabricated without requiring an ASME Section III Certificate of Authorization. The nuclear and DOE fabrication capability page states that boundary directly, including what falls outside it.
In-house mechanical and thermal design sits alongside radiography, ultrasonic, penetrant, and visual examination with positive material identification and the ASME U, R, and PP certifications under one roof. That reduces the number of interfaces on documentation-intensive work.
Two related articles cover adjacent ground. When ASME Code compliance is actually required addresses jurisdictional adoption. Exotic alloy heat exchangers for chemical service covers the high-alloy controls that often accompany nuclear and DOE process duty.
FAQs about NQA-1 and nuclear equipment fabrication
Is NQA-1 the same as the ASME Boiler and Pressure Vessel Code?
No. They govern different things. The BPVC is a design and construction code, setting allowable stresses, thickness rules, welding and examination requirements, and testing for the equipment itself. ASME NQA-1 is a nuclear quality assurance standard, setting requirements for the program under which the work is planned, controlled, verified, and documented. Equipment is designed and built to Section III or Section VIII; the program governing that work may be an NQA-1 program. NQA-1 contains no design rules, and no construction code contains a complete quality assurance program.
Does an ASME U-stamp mean a fabricator meets NQA-1?
No. A Certificate of Authorization and the Certification Mark show that a quality control system was accredited for construction under a specific Code section. RG 1.28, Revision 6 states that NRC recognition of the ASME Accreditation Program "applies only to the programmatic aspects of the QA programs," and that purchasers should confirm suppliers are effectively implementing their approved programs. An NQA-1 program is a separate and broader set of controls, evaluated on its own.
What equipment can be subject to NQA-1 requirements?
Any item or service affecting a safety function. That is determined by classification, not by equipment type. In practice it has included pressure vessels, shell-and-tube heat exchangers, condensers, evaporators, columns and towers, separators, tanks, piping and spools, and process skids and modular assemblies. It also covers supporting services such as nondestructive examination, heat treatment, and calibration. Non-safety-related equipment at the same facility may carry a reduced control set, selected NQA-1 requirements imposed by contract, or neither. The procurement documents govern.
Which edition of NQA-1 applies to a project?
Whichever edition the procurement documents invoke. For NRC-regulated work, RG 1.28, Revision 6 endorses Parts I and II of NQA-1-2017, NQA-1-2019, and NQA-1-2022, subject to stated exceptions. ASME has since published NQA-1-2024. On DOE work, 10 CFR Part 830 does not name the standard, so the edition arrives through contract. Confirm the edition and the applicable Requirements in writing before bidding.
Why is material traceability important in nuclear fabrication?
Because it is required, and because the alternative cannot be verified. Appendix B Criterion VIII requires identification maintained "by heat number, part number, serial number, or other appropriate means, either on the item or on records traceable to the item." Criterion VII requires documentary evidence of conformance to be available at the site before installation or use. Traceability is also the practical defense against counterfeit, fraudulent, and suspect items. NRC Information Notice 2008-04 documented counterfeit valves that reached a nuclear plant with documentation in hand, one of which ran eight months in a non-safety-related system before discovery.
