Recent experience measuring breeder fresh fuel assemblies

The International Atomic Energy Agency (IAEA) is required to conduct independent on-site verification of nuclear material held under safeguards agreements with member states. The nuclear material contained in liquid-metal fast breeder reactor (LMFBR) fresh fuel assemblies presents unique safeguards and measurement problems. Since LMFBR fresh fuel may contain uranium of various enrichments, plutonium, or mixtures of uranium and plutonium, a combination of nondestructive assay (NDA) methods and equipment must be used to achieve independent verification of the nuclear material contained in LMFBR fresh fuel assemblies. During 1985 and 1986, a number of measurements were carried out at the BOR-60 LMFBR facility near Dimitrovgrad, USSR to train IAEA inspectors in the use of standard NDA equipment and measurement procedures that can be employed to verify the nuclear material content of LMFBR fresh fuel. Since these measurements were conducted at an operation LMFBR facility, agency inspectors had an opportunity to receive training under actual field conditions. These activities also presented the first opportunity for the agency to test NDA measurement methods on LMFBR fresh fuel of the BOR-60 design. The measurements conducted at the BOR-60 site established that standard agency NDA equipment and procedures can be employed to independently verify the nuclear material content of LMFBR fresh fuel assemblies