The Agency needs to maintain a solid and reliable foundation for recruited inspectors by providing practical training at commercial nuclear power plants. The Comprehensive Inspection Exercise (CIE) is a basic training which consists of a simulation of a Design Information Verification (DIV) Visit, a Physical Inventory Verification (PIV) at a nuclear power plant, including Complementary Access. The basic curriculum includes a pre-course session, auditing exercises, fresh fuel (bundles and assemblies) measurements, spent fuel (bundles and assemblies) measurements, verification of design features, as well as nuclear material flow. ROK has been holding the lightwater reactor (LWR) / heavy-water reactor (CANDU) training course (CIE) from 2010 every year with about 2 weeks curriculum through MSSP (Member State Support Program). LWR and CANDU are operated by KHNP. To efficiently carry out the safeguards, IAEA receives the contribution through the ROK support program and implement R&D for the nuclear material inspection. ROK has been supporting and contributing total 22 tasks to IAEA in-cash and in-kind. Among them, this training provides for a course on safeguards verification activities at CANDU and LWR facilities. This course offers inspectors a unique opportunity to understand diversion scenarios and to familiarize themselves with instruments specifically used at CANDU and LWR facilities (OFPS and DCVD), as well as spent fuel dry storage transfer verification activities and dry storage dual sealing arrangements. KINAC performs PoC (Point of Contact) on behalf of NSSC and coordinates work between IAEA and KHNP. Additionally, KINAC first discusses with KHNP that can host light-water reactors and heavy-water reactors with KHNP at the beginning of each year. In order to hold a successful training, ROK plans and carries out a lot of process including agenda, accommodation, equipment movement, logistics and so on in consultation with the IAEA and facilities.

The measurement activities to evaluate material balance of nuclear material are usually performed by operator. It is because that the IAEA does not have enough manpower to carry out nuclear measurement accountancy of all nuclear materials in the world. Therefore, the IAEA should consider scenarios which facility operator tries to divert nuclear material for misuse by distorting measurement record. It is required to verify the operator’s measurement data whether it is normal or not. IAEA measures inventory items using their own equipment which is independent of facility operator equipment for verification. Since all inventory lists cannot be verified due to limited resources, the number of items to be verified is determined through statistical method which is called as sample size calculation. They measure for the selected items using their own equipment and compares with operator’s record. The IAEA determines sample size by comprehensively considering targeted diverted nuclear material amount and targeted non-detection probability and performance of measurement equipment. In general, the targeted diverted nuclear material amount is considered significant quantity (plutonium: 8 kg, uranium-235: 75 kg). If the targeted non-detection probability or the performance of the verification equipment is low, the sample size increases, and on the contrary, in the case of high non-detection probability or good performance of verification equipment, even a small sample size is satisfied. It cannot be determined from a single sample size calculation because there are so many sample size combinations for each verification equipment and there are many diversion scenarios to be considered. So, IAEA estimates initial sample size based on statistical method to reduce calculation load. And then they calculate non-detection probability for a combination of initial sample size. Through the iteration calculation, the sample size that satisfies the closest to the target value is derived. The sample size calculation code has been developed to review IAEA’s calculation method. The main difference is that IAEA calculates sample size based on approximate equation, while in this study, sample size is calculated by exact equation. The benchmarking study was performed on reference materials. The data obtained by the code show similar results to the reference materials within an acceptable range. The calculation method developed in this study will be applied to support IAEA and domestic inspection activities in uranium fuel fabrication facility.