[en] For the reliable assay of extremely low activity, it is essential to reduce the system background count rates. Typical background reduction techniques, including the anticoincidence techniques with guard detectors to reject the cosmic-ray signal, were applied to set up an ultralow background system, KAERI-ULBS, for use in special purpose such as remote monitoring of undeclared nuclear activities. The effectiveness of each background reduction techniques was analysed. The KAERI-ULBS system showed the following performance : system background lower by a order of 2 in 50 keV to 2.5 MeV energy region than the partially shielded condition(sample door opened), nominal count rate of 6.8x10^-4 cps for at 662 keV, and the minimum detectable count rate of 5.078x10^-3 cps for ¹³⁷Cs(662 keV). Additional endeavors were made to reduce the remaining cosmic-ray contributions by introducing passive neutron shield to the system. Around 10% of further background reduction appears to be achieved when the system is surrounded by neutron shield consisting of polyethylene blocks of 100 mm and a boron sheet of 3.2 mm thick

[en] Ultralow background gamma-ray measurement system was installed to measure and analyze gamma-rays emitted from environmental and swipe samples. The background reduction techniques applied on this system are the passive shielding to surround the HPGe detector, an active external anticosmic shield to shield cosmic-rays and the nitrogen gas supply to minimize the introduction of ubiquitous radon decay nuclei. The performance test result showed that the system background at energies between 50 keV and 2 MeV is reduced about 10^-2 order and the MDA is so low as to be suitable for the environmental sample analysis. But it is appeared that the neutron produced by cosmic ray increases the background at low energy region

[en] Since IAEA Safeguards inspection started in Korea, IAEA and Korea have been looking for possible cooperation ways to perform more efficient and effective safeguards inspection. As a part of the efforts, during the 8th JRM in 1999, the IAEA and Korea agreed the LWRs enhanced cooperation between both sides. It is traditional safeguards approach based on the remote monitoring. In 2004, the additional Protocol was in force in Korea. Since then, both sides have been now considering new approaches according to all the facility types under the integrated safeguards. This study analyzes which options suggested by the IAEA is the best approaches to Korean LWRs

[en] The Korean nuclear fuel fabrication plant started to manufacture the nuclear fuels at the end of 1988 and has been supplying all the domestic needs of the LWR fuels since then. A new CANDU fuel fabrication plant was also built in 1997. These plants were classified as a bulk facility by the Agency's safeguards criteria, the Agency has been applying the inspection procedure designed to meet the purpose of safeguarding these. It requires that one physical inventory verification and two interim inspections should be carried out under the zone approach, which has been applied for LEU and NU fresh fuels. In order to evaluate the material balance during each material balance period, the Material Unaccounted For (MUF) must be accurately declared by the facility operators and properly evaluated by the Agency

[en] Since safeguards inspection in Korea started, the IAEA and Korea have been looking for possible cooperation for more efficient and effective safeguards implementation. As a part of the efforts, the IAEA and Korea agreed the enhanced cooperation on the LWR inspection at the 8th Joint Review Meeting in 1999. The enhanced cooperation on LWR inspection is a kind of traditional safeguards approach based on remote monitoring. From the current situations, it is expected that integrated safeguards would be applied in near future. In this aspect, this study analyzes the form of integrated safeguards appropriate to Korean LWRs

[en] Four Wolsong units are designated by the IAEA as an On-Load reactor. On-power fueling in a CANDU 600 MW reactor is normally performed by inserting eight fresh fuels on the end of a fuel channel while eight irradiated fuels are discharged at the other end. Since Wolsong unit 1 started its commercial operation in 1983, now four OLRs have been operating in ROK

[en] Based on the enhanced cooperation between Republic of Korea (ROK) and International Atomic Energy Agency (IAEA), IAEA installed new safeguards equipment (Unattended Monitoring System, UMS) at Wolsung unit 2 on January, 2005. The UMS was utilized in parallel with traditional human surveillance during the transfer campaign of Wolsung unit 2 (7 March - 22 July). Installation of UMS at all Wolsung units will be decided on the basis of the result of this test. The transfer campaign with UMS at Wolsung units 2 and 4 was started from September 1, 2006 at the same time. Implementation of UMS to the transfer campaign in Wolsung site will be considerably reduced the IAEA's inspection effort and burden of operator

[en] A remote operational system for the tomographical assay was designed to scan the sample and to assay the inside radioactive materials distribution three dimensionally, composed of 3 axes moving table, collimator, data acquisition system in a PC control. The system design was done by considering that how the accurate assay be affected by the modeling or by the other system components. In the system design, MCNP code simulation was done to find the optimum condition for the spatial assay of the radioactive materials

[en] Depleted uranium used in gamma ray irradiator as the shielding material was not completely investigated and properly reported by the Atomic Energy Act until now, The IAEA required to report the status of the companies using small amount of uranium and information for 42 NDT companies was declared in 1999. And IAEA inspector visited some company to confirm their declarations. The Additional protocol proposed as the strengthened safeguards system by the IAEA, which was ratified through the national assembly on February 9, 2004, and was entered into force on February 19, 2004. The government is investigating the amount, purpose and location of depleted uranium in the area of non-nuclear use.

[en] The Korean nuclear fuel fabrication plant (KNFC) established to manufacture the nuclear fuels at the end of 1988 and has been supplying all domestic needs of the LWR and CANDU fuels. In the Agency's safeguards criteria, KNFC is classified as a bulk facility and is defined to be verified with one physical inventory verification (PIV) and two interim inspections should be carried out under the zone approach, which has been applied for LEU and NU fresh fuels. After the PIV is performed, KNFC should calculate the material unaccounted for (MUF) and report it to the authority and the Agency. This is significant element influenced by the accuracy of equipment for nuclear material accounting