Overview and status of domestic and international standards for nuclear criticality safety

For many years, the domestic and international consensus standards for nuclear criticality safety (NCS) have provided guidance for those performing hands-on operations involving fissionable materials. These consensus standards have been crucial to reducing the number of criticality accidents in process facilities. The last known criticality accident inside the United States was in 1978 (39 years ago at this writing) at the Idaho Chemical Processing Plant, and outside the United States, an accident occurred at Tokai-mura, Japan, in 1999 (18 years ago at this writing). The domestic consensus standards for NCS include the American Nuclear Society (ANS) standards. The ANS Standards Board, the NCS Consensus Committee, and the ANS-8 Subcommittee oversee the development and maintenance of these standards. There are currently eighteen standards in revision (seven) or maintenance (eleven) cycles, and one standard is currently in development. The international consensus standards for NCS calculations, procedures, and practices are maintained and developed within the International Organization for Standardization, Technical Committee 85 on Nuclear Energy, Subcommittee 5 on Nuclear Fuel Technology, and Working Group 8, “Nuclear Criticality Safety.” Seven standards are currently available, one standard is in revision, and four standards are at various stages of development. This paper provides the NCS community with an overview and status report of domestic and international NCS consensus standards to stimulate interest and to support their continued development.