ASTM C 992a:2020

1.1 This specification defines criteria for boron-based neutron absorbing material systems used in racks in a pool environment for storage of nuclear light water reactor (LWR) spent-fuel assemblies or disassembled components to maintain sub-criticality in the storage rack system. 1.2 Boron-based neutron absorbing material systems normally consist of metallic boron or a chemical compound containing boron (for example, boron carbide, B 4 C) supported by a matrix of aluminum, steel, or other materials. 1.3 In a boron-based absorber, neutron absorption occurs primarily by the boron-10 isotope that is present in natural boron to the extent of 18.3 ± 0.2% by weight (depending upon the geological origin of the boron). Boron enriched in boron-10 could also be used. 1.4 The materials systems described herein shall be functional (that is, always be capable to maintain a boron-10 areal density such that subcriticality is maintained depending on the design specification for the service life in the operating environment of a nuclear spent fuel pool). 1.5 Observance of this specification does not relieve the user of the obligation to conform to all applicable international, national, and local regulations. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

27.120.01