nonnuclear

Nonnuclear is an adjective describing something that does not involve the nucleus or nuclear processes, or that arises outside of the cell nucleus. The term is used across disciplines, and its exact meaning depends on context.

In biology, nonnuclear refers to structures or processes located outside the cell nucleus. Many cellular activities occur in the cytoplasm or in organelles such as mitochondria and chloroplasts, which contain their own DNA and protein synthesis machinery yet are not part of the genomic nucleus. The term is also used when contrasting nuclear and extranuclear genomes; for example, mitochondrial and chloroplast genomes are nonnuclear.

In energy and policy contexts, nonnuclear refers to energy sources, technologies, or strategies that do not involve nuclear fission, fusion, or weapons-grade materials. Nonnuclear energy sources include solar, wind, hydro, geothermal, and biomass, while nonnuclear weapons imply conventional weapons that do not rely on nuclear reactions.

In medicine and imaging, nonnuclear imaging modalities use non-nuclear processes. This includes magnetic resonance imaging (MRI), ultrasound, optical imaging, and X-ray–based techniques that do not depend on nuclear reactions; nuclear imaging specifically relies on radioactive tracers and is discussed separately.

Nonnuclear can be written with or without a hyphen as nonnuclear or non-nuclear; style guides vary. In general, the term is used to emphasize absence of nuclear involvement rather than to imply a comprehensive negation of all nuclear-related aspects.