A Study on Establishment of Unacceptable Radiological Consequence (URC) for Physical Protection against Sabotage

The international community has recommended that a graded approach should be applied to the establishment of the domestic regime for physical protection in accordance with fundamental principle H of the amended Convention on Physical Protection of Nuclear Material (CPPNM) and INFCIRC/225/rev.5. In Korea, Currently, the graded approach to unauthorized removal of nuclear material is divided into three categories (Category Ι, Category ΙΙ, Category ΙΙΙ) based on the IAEA INFCIRC/225/rev.5. Moreover, depending on the categorization of nuclear material, physical protection measures against unauthorized removal are also clearly categorized. But in the case of physical protection against sabotage, the graded approach to the physical protection measures is not applied since Unacceptable Radiological Consequence (URC) for identifying sabotage target and level is not determined. URC can be established based on either dose limit or design limit. The report by Sandia National Lab. in USA specifies that core damage is used for URC. Calculation of an exact dose is based on various assumptions and processes and subsequently increases uncertainty. Therefore, using design limit for decreasing uncertainty is more effective than using dose limit. In order to apply the graded approach to physical protection against sabotage, we have taken into Fundamental principle H : Physical protection requirements should be based on a graded approach, taking into account the current evaluation of the threat, the relative attractiveness, the nature of the material and potential consequences associated with the unauthorized removal of nuclear material and with the sabotage against nuclear material of nuclear facilities consideration legal and institutional standards on domestic and international radiological consequences and intended to provide a reference for the URC establishment by the State. The study on various standards led to the conclusion that each value has advantages and disadvantages respectively in setting URC. In case of Korea, there are a lot of regulation objectives including use facilities of radioisotope. We consider three things in determining URC. First, we can apply URC to all nuclear facilities and regulation objectives. Secondly, there is no conflict with safety standards