SAFEGUARDS CORRESPONDENCE IN POST OPERATION
PHASE AT URANIUM ENRICHMENT PLANT

The uranium enrichment facility using gas centrifuge at Ningyo-toge environmental engineering center was constructed in 1979 and safeguards measure for enrichment facility was applied at the time of operation start. It was clear that it was extremely difficult to balance protection of sensitive information and effective safeguards measure. HSP (Hexapartite Safeguards Project; 1980-1983) discussed safeguards approach for gas centrifuge enrichment facility. Conclusion of HSP includes LFUA (Limited Frequency Unannounced Access) to detect misuse of facility to produce high-enrichment uranium. Based on HSP, various safeguards measures were developed and tested at NEP through the Pilot Plant operation. The effective and efficient safeguards measures were demonstrated and developed through long-term operation in the Demonstration Plant. Currently, our facility has been shifted to decommissioning phase. We need new safeguards challenge in accordance with current situation. Regarding safeguards for post-operation, ELFUA (Expanded Limited Frequency Unannounced Access) is tentatively installed. ELFUA is the inspection of the decontamination process of dismantled centrifuges in addition to LFUA for maintaining transparency and, attaching the seals for main piping of centrifuge is tentatively implemented for enhancing the proliferation resistance as operation shut down. We have also developed technologies for evaluation, recovery and measurement the hold-up uranium in the centrifuges after operation shutdown as preparation of decommissioning. In order to complete safeguards termination for enrichment plants in the final stage of decommissioning facility, we are now discussing with IAEA about removal of nuclear material, waste disposal and removal or rendering of essential equipment for its use as main theme. Regarding dismantlement of centrifuge, currently, a part of centrifuge and attached equipment are dismantled in progress. We understand that the requirement of change the status is “Permanent decommissioning of cascade”. To reach this requirement, it is important to maintain transparency for centrifuge, make essential equipment rendered inoperable and manage the hold-up uranium and waste material. Safeguards challenges for post-operation phase need to be solved step by step towards termination. The paper will describe the safeguards challenge and perspective in enrichment facility.