The Domestic Nuclear Detection Office of the U.S. Department of Homeland Security (DHS) requested that NCRP provide specific radiation protection advice relevant to the Cargo Advanced Automated Radiography System (CAARS) currently under development. CAARS is designed to detect high atomic number (Z > 72) material which might be special nuclear material or shielding designed to conceal radioactive material. In addition, it must have a conventional radiographic imaging capability to detect illicit drugs, high explosives, and other contraband (e.g., weapons, currency) in cargo conveyances. This Commentary:
- recommends a dose limit for individuals who might be inadvertently exposed to radiation
in a conveyance within the CAARS exclusion zone; and also:
- addresses the methods for estimating by calculation and verifying by measurement
such doses delivered by CAARS;
- discusses the estimated change in health risk to such an individual as a function of dose;
- recommends various methods for ensuring the dose limit to an inadvertentlyexposed individual is not exceeded;
- describes the physical properties of the interaction between high-energy radiation
and material that influence both the doses delivered and the methods for measuring
such doses; and
- recommends specific methods for measuring the maximum dose to an exposed individual
in a scanned conveyance.
- addresses the maximum cumulative effective dose in an hour to an individual working outside the exclusion zone of a CAARS facility; and also:
- recommends system features and operational procedures to ensure that worker doses remain as low as reasonably achievable (ALARA); and
- recommends specific methods for measuring dose to an individual working outside the exclusion zone.
- recommends an administrative control for annual effective dose to members of the public outside the perimeter of a CAARS facility.
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