Analysis of the Zone Approach for Plutonium Facilities

In order to examine the effect of different inspection strategies on inspection effort, an analysis was carried out of the zone approach for the international safeguards verifications of a model nuclear fuel cycle. The fuel cycle includes thefabricationof'mixed- oxidefreshfuelfor nine light-water reactors and one experimental breeder reactor and the subsequent reprocessing of the spent fuel. There are thus two zones to be considered, aplutonium zone and an irradiated fuel zone. The zone approach entails many fewer verifications of nuclear material flows between different material balance areas (facilities) than the facility-oriented approach, and it requires an annual simultaneous physical inventory verification (PIV) and monthly simultaneous interim inventory verifications for timeliness at all the facilities. Therefore, the zone approach yields "snapshots " of the disposition of the nuclear materials at the time of the simultaneous inventory verifications, but less verified information than a facility-oriented approach encompassing frequent flow verification.