UNE 73401 nuclear design change request: template and fields

In one sentence

The design change request describes the change, its technical justification, its effect on the design bases and on safety, the verification it needs and the documents to be updated, because the design control criterion of nuclear quality assurance requires changes to be subject to control measures equivalent to those applied to the original design and to be approved by the same organisations, as CSN guide GS-10.6 explains.

Content reviewed on 17 October 2026

Type of information: Mandatory record Design control criterion (changes); GS-10.6. Lifetime record for the licensee (IS-24)
Who fills it in: Engineering Approved by the same organisation that approved the original design; quality assurance checks the process is followed
When: Before the change is applied Including changes that arise during manufacture or erection
How long it is kept: Lifetime or at least 5 years IS-24 requires licensees to keep as lifetime records, for the whole life of the facility or component, those meeting any of its criteria, and to keep non-permanent records for at least five years. Suppliers apply whatever the licensee’s purchase order specifies.

What the standard requires

What UNE 73401 demands and what it leaves to your judgement

In nuclear quality assurance, design changes, including those arising on site, must be subject to control measures equivalent to those of the original design and be reviewed and approved by the organisations that carried out that review, unless another organisation with the necessary knowledge is expressly designated.

The request must justify the change technically, assess its effect on the design bases and on other items, and decide what verification it needs. For the licensee, some changes also require a safety evaluation and, depending on their scope, authorisation from the regulator.

Records supporting changes are lifetime records under Instruction IS-24.

Read it in context: Design and document control, in the UNE 73401 Academy

Structure

Fields the template should include

Number, date and requester
Item and design documents affected, with their revision
Description of the change
Technical justification
Effect on the design bases, the safety class and other items
Verification needed and its result
Approval by the design organisation
Documents updated: drawings, calculations, specifications, procedures
Notification to the licensee or customer, where applicable
Closure

Example

Example: change of section on a support

Company, people and figures are fictitious: the example only shows what a properly completed record looks like.

Field	Content
Number	MD-2026-006 · 3 March 2026 · workshop
Item	Support SP-114 · drawing PL-SP-114 revision 2 · calculation CA-SP-114 revision 2
Change	Replace the specified section with another of equivalent dimensions owing to a supply shortage
Justification	Lead time for the original section of 16 weeks
Effect	The resisting cross-section changes; same steel grade
Verification	Recalculation verified by the same independent engineer · margin 1.3
Approval	Head of engineering, 10 March · licensee acceptance through the order channel, 17 March
Documents	Drawing to revision 3 · calculation to revision 3 · bill of materials

At the audit

Mistakes auditors commonly flag

Site changes made first and documented later as “as built”.
The change is approved by someone other than whoever approved the design, with no designation.
Not all affected documents are identified and some drawings are left out of date.
Small changes processed without verification even though they affect the calculation.
The licensee is not told about a change that the order makes subject to its acceptance.

In Kimobox

How this record is kept in Kimobox

1Every design change is documented with its technical justification.
2Approval follows the same workflow as the original design, with independent verification where required.
3Affected documents are linked and versioned, so none is left at the previous revision.
4Tasks arising from the change are assigned an owner and a date, with an alert if they fall behind.

Frequently asked questions

What people ask us before getting started

Is a change of material a design change?

If it affects what is specified in the design documents of a safety-related item, yes. It must go through the same control as the original design.

Who approves the change?

The organisation that approved the original design, unless another one with sufficient access to information and competence is expressly designated.

How does it differ from a nonconformity?

A design change alters the design in a planned way. A nonconformity accepted “use as is” does not change the design, but it must be technically justified and often requires the documentation of the manufactured item to be updated.

Keep exploring

Related pages

Sources

Where each figure comes from

References to the official text in force. If a standard is revised, this page is updated and the review date says so.

Guía de Seguridad GS-10.6 (Rev. 1) — Garantía de calidad en el diseño de instalaciones nucleares (Quality assurance in the design of nuclear facilities) Consejo de Seguridad Nuclear (Spanish Nuclear Safety Council) · April 2002
Instrucción IS-24, de 19 de mayo de 2010, del Consejo de Seguridad Nuclear, sobre el archivo y los periodos de retención de los documentos y registros de las instalaciones nucleares (CSN Instruction IS-24 on archiving and retention periods for nuclear facility documents and records) BOE-A-2010-8779 · BOE no. 133, 1 June 2010
10 CFR Part 50, Appendix B — Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants (an alternative accepted by GS-10.1) U.S. Nuclear Regulatory Commission · Current text

UNE 73401 nuclear design change request