This document provides requirements and guidance regarding the use of CAAS for operations of a nuclear facility. Requirements and guidance on CAAS design are provided in the IEC 60860. This document is applicable to operations with fissile materials outside nuclear reactors but within the boundaries of nuclear establishments. This document applies when a need for CAAS has been established. Information about the need for CAAS is given in Annex C. This document does not include details of administrative steps, which are considered to be activities of a robust management system (ISO 14943 provides details of administrative steps). Details of nuclear accident dosimetry and personnel exposure evaluations are not within the scope of this document. This document is concerned with gamma and neutron radiation rate-sensing systems. Specific detection criteria can also be met with integrating systems; systems detecting either neutron or gamma radiation can also be used. Equivalent considerations then apply.