Neutron absorbers have been used for criticality control in spent nuclear fuel pools and in spent fuel transportation casks for decades. However, since the late 1980s, as spent fuel storage pools have been filled, utilities have transferred spent fuel into dry dual-purpose (storage/transportation) canisters. The neutron absorbers used in dual-purpose canisters are subjected to different operating conditions than materials used in spent fuel pools. Because of these differences, ASTM International Committee C26 on Nuclear Fuel Cycle has developed a new standard, C 1671, Practice for Qualification and Acceptance of Boron Based Metallic Neutron Absorbers for Nuclear Criticality Control for Dry Cask Storage Systems and Transportation Packaging. C 1671 is under the jurisdiction of Subcommittee C26.03 on Neutron Absorber Materials Specifications.
James Hobbs, Nuclear Fuel Services and C26 member, says that the new standard was developed because there were several existing material suppliers, new suppliers in the process of qualifying new products, canister designers/suppliers and testing organizations, each using one or more of the several approved but different approaches to qualification and acceptance testing. “The NRC wanted to codify industry practices and develop a consensus industry standard to guide canister designers, neutron absorber manufacturers and the end users toward a consistent approach for qualification and acceptance testing, as well as to provide the NRC with a consistent basis for evaluating new materials for regulatory approval,” says Hobbs. “The standard provides a consistent basis for qualification and acceptance for a variety of different material and different canister designs,” says Hobbs.
Subcommittee C26.03 welcomes participation in its standards developing activities. The task group responsible for C 1671 will soon be working on a proposed new standard for neutron absorber material to be used by the U.S. Department of Energy repository package, the transportation, aging and disposal, or TAD, canisters. The Department of Energy has qualified one material, grade A borated stainless steel for use in TAD canisters.
ASTM International standards are available for purchase from Customer Service (phone: 610/832-9585; service@astm.org) or at www.astm.org. For further technical information, contact James Hobbs, Nuclear Fuel Services, Erwin, Tenn. (phone: 404/229-1180; jshobbs@nuclearfuelservices.com). Committee C26 meets Jan. 27-Feb. 1, 2008, at the January committee week in Tampa, Fla. For membership or meeting information, contact Joe Koury, Technical Committee Operations, ASTM International (phone: 610/832-9804; jkoury@astm.org).
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