Model safeguards approach for gas centrifuge enrichment plants

Full text: An improved model safeguards approach for gas centrifuge enrichment plants (GCEPs) has been developed by the IAEA. This model builds on the basic safeguards approach for commercial gas centrifuge enrichment plants that was established by the Hexapartite Safeguards Project (HSP) in the early 1980s. There were a number of reasons to update the HSP approach: since HSP concluded its work the plants covered by it have advanced in technology and grown in separative work capacity, operational procedures have changed and more plants are scheduled to be introduced; a number of States that did not participate in HSP have acquired the technology and built GCEPs now subject to safeguards, or are planning to build GCEPs; and safeguards technologies have evolved during this period. This document describes the revised model approach under traditional safeguards. There are three main paths to be considered for the acquisition of HEU by a State having a GCEP with a declared maximum enrichment level of ca. 5% 235U: (a) Diversion of nuclear material from the declared feed, product or tails by the false reporting of material unaccounted for (MUF), shipper-receiver difference (SRD), or of operator declarations reflected in operator-inspector difference statistics (D). The diverted material is shipped to an undeclared enrichment plant for further enrichment to HEU. (b) The introduction of undeclared feed into the plant for enrichment to a level less than or equal to the declared maximum. The product from this activity is not declared and is shipped to an undeclared enrichment plant for further enrichment to HEU. This path is known as 'excess production'. (c) Undeclared production of HEU at the declared GCEP by reconfiguration of the cascades or operation in recycle mode. The HEU product is not declared and is shipped to an undeclared location. If declared feed is used, the missing material is 'diverted' into MUF, SRD or D as in (a). Alternatively, undeclared feed could be used as in (b). A fourth acquisition path, misuse of the facility to produce enrichments higher than the declared maximum, but less than 20%, with enrichment to HEU at an undeclared enrichment plant, is not considered likely. It would have the disadvantages of both being open to detection by environmental sampling and requiring further enrichment at an undeclared plant to produce HEU. In any case, this acquisition path would be covered by measures covering the three main paths. The objective of safeguards (paragraph 28 of INFCIRC/153) is 'the timely detection of diversion of significant quantities of nuclear material from peaceful nuclear activities to the manufacture of nuclear weapons or of other nuclear explosive devices or for purposes unknown, and deterrence of such diversion by the risk of early detection'. From this overall objective, three specific safeguards objectives can be derived to cover the acquisition paths referred to above. These three objectives are: 1. The timely detection of the diversion of significant quantities of natural, depleted or low enriched UF6 from the declared flow through the plant, and the deterrence of such diversion by the risk of early detection. 2. The timely detection of the misuse of the facility in order to produce undeclared product (at the normal product enrichment levels) from undeclared feed and the deterrence of such misuse by the risk of early detection. 3. The timely detection of the misuse of the facility to produce UF6 at enrichments higher than the declared maximum, in particular HEU, and the deterrence of such misuse by the risk of early detection. The safeguards approach for any GCEP must be designed to meet all three of the objectives listed above. The main features of the approach are: Annual Physical Inventory Verification; Design Information Verification; Nuclear material accountancy verification of declared flows, i.e., natural uranium fed to the cascades and the low enriched and depleted uranium taken off them. The operator makes available 100% of the flow for verification by the Agency. This ma y be achieved by announced, unannounced or short-notice random inspections; Measures to confirm that there is no undeclared production of LEU enriched to levels not greater than the declared maximum level; Measures to detect the production of uranium at enrichments higher than the declared maximum, in particular HEU. These measures should include limited frequency unannounced access (LFUAs) inside the cascade areas to carry out visual observation, environmental sampling, NDA measurements and DA sampling, where possible. The paper will describe, in detail, a range of mechanisms for possible use in achieving the above objectives taking into account facility specific conditions. (author)