Overview
ISO 12749-5:2018 - "Nuclear energy, nuclear technologies, and radiological protection - Vocabulary - Part 5: Nuclear reactors" is an international vocabulary that defines core terms and concepts used across the field of nuclear reactors. The standard collects terms, definitions, notes and examples for reactor-related concepts at a broad, non‑quantitative level. It is intended to promote clear communication and a common understanding among engineers, regulators, researchers and other stakeholders working with nuclear reactors.
Key characteristics:
- Provides minimum essential information for each nuclear reactor concept.
- Excludes quantitative data (no numerical specifications or performance limits).
- Organizes entries in a conceptual (preferred-term) order and includes systematic and alphabetical indexes.
- Includes an informative Annex A (methodology) and a bibliography.
Key topics
ISO 12749-5:2018 covers foundational nuclear reactor vocabulary, including but not limited to:
- Nuclear fission (spontaneous and induced) and fission energy
- Prompt and delayed fission neutrons and fission radiation
- Fission products, fast and thermal neutrons
- Fissile and fertile nuclides
- Nuclear chain reaction, controlled chain reaction, and nuclear criticality
- Effective neutron multiplication factor (keff) and reactivity (ρ)
- Poison (neutron absorbers), neutron multiplicative configuration, and reactor kinetics
- Notes and examples to clarify ambiguous or widely misunderstood terms
The standard draws on established sources (ISO/TC 85 materials, IAEA, IEC) and documents terminological consensus from subject‑matter experts.
Applications
ISO 12749-5:2018 is practical for any activity that requires precise, unambiguous terminology related to nuclear reactors:
- Technical documentation, procedures and operating manuals
- Regulatory guidance, licensing documents and safety cases
- Standards development and cross‑organization coordination
- Training materials, textbooks and translator/reference glossaries
- Communication between multidisciplinary teams (design, operations, safety, procurement)
Because the vocabulary excludes quantitative specifications, it is complementary to technical standards that set numerical requirements.
Who should use it
- Nuclear engineers and reactor physicists
- Regulatory bodies and safety analysts
- Standards writers and technical editors
- Educators, trainers and translators working in nuclear technology
- Project managers and procurement specialists who need consistent terminology
Related standards
- Part of the ISO 12749 series (vocabulary for nuclear energy and radiological protection)
- Cross-references to ISO/TC 85 publications and IAEA terminology resources are included in the bibliography
Using ISO 12749-5:2018 helps reduce ambiguity, improve documentation quality, and ensure consistent use of core nuclear reactor terms across international projects and regulatory frameworks.