Cask
Cation
Certificate of Compliance (COC)
Chain reaction
Charged particle
Chemical recombination
Cladding
Collective dose
Code of Federal Regulations (CFR)
Committed dose equivalent
Committed effective dose equivalent
Compact
Compound
Consent Order and Compliance Agreement (COCA)
Contamination
Containment
Control rod
Cosmic radiation
Counter
Critical mass
Critical organ
Criticality
Crud
Cumulative dose
Curie (Ci)