Commentary 20

NCRP Commentary No. 20, Radiation Protection and Measurement Issues Related to Cargo Scanning with Accelerator-Produced
High-Energy X Rays

Purchase

The Domestic Nuclear Detection Office of the U.S. Department of Homeland Security requested that the National Council on Radiation Protection and Measurements (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.

NCRP Commentary No. 20, Radiation Protection and Measurement Issues Related to Cargo Scanning with Accelerator-Produced High-Energy X Rays:

• 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 inadvertently- exposed 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; 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.