The licensee of nuclear facilities in the Republic of Korea should ensure the functionality of Critical Digital Assets (CDAs) is maintained and minimize the negative impact of cyber-attacks by establishing a cyber security contingency plan. The contingency plan should include detailed response guidelines for each stage of detection, analysis, isolation, eradication, and recovery and comply with the requirements specified in KINAC’s “Regulatory Standard 015 - Security for Computer and Information System of Nuclear Facilities”. However, since the cyber security contingency plan describes the overall response guidelines for CDA, it may be difficult to respond practically to cyberattacks. This paper suggests a method to address this issue by performing exercises based on the classification of CDA types. CDAs in nuclear facilities can be classified according to their characteristics. The criteria for classifying CDA types include whether the asset is a PC, whether communication ports (RS-232, 422, 485) exist, whether storage devices can be connected through USB/memory card ports and whether internal settings can be changed through HMI devices such as built-in buttons. By classifying CDA types based on the proposed criteria, the attack vectors of CDAs can be defined. By defining the attack vectors, a list of cyber-attacks that CDAs may face can be created, and abnormal symptoms of CDAs resulting from the listed cyber-attacks can be defined. By using the defined abnormal symptoms of CDAs, the response measures of detection, analysis, isolation, eradication, and recovery can be concretized and reflected in the contingency plan. This may enable a more practical emergency response. This paper presents an improvement to the cyber security emergency response plan through the definition of cyber-attacks based on the classification of CDA types. By improving the contingency plan for CDAs as a whole using the proposed method, it is expected that more effective response measures can be taken in the event of a cyber-attack.

Nuclear power plants (NPPs) are designed in consideration of redundancy, diversity, and independence to prevent leakage of radioactive materials from safety of view, and a contingency plan is established in case of DBA (Design Basis Accident) occurrence. In addition, NPPs have established contingency plans for physical attacks, including terrorist intrusions and bomb attacks. However, the level of contingency plan caused by cyberattacks is quite insufficient compared to the contingency plan in terms of safety and physical protection. The purpose of this paper is to present the problems of cyberattack contingency plan and methods to supplement it. The first problem with cyberattack contingency plan is that the initiating event for implementing the contingency plan is undecided. In terms of safety, the DBA is identified as an initial event, and each contingency plan is based on the initial events specified in the DBA such as Loss of Coolant Accident and Loss of Offsite Power. In terms of physical protection, each has a contingency plan by identifying bomb attacks and terrorist intrusions in Protected Area and Vital Area as initial events. On the other hand, in the contingency plan related to a cyberattack, an initial event caused by a cyberattack is not identified. For this, it is necessary to classify the attack results that may occur when the CDA is compromised based on the attack technique described in Design Basis Threat. Based on this, an initiating event should be selected and a contingency plan according to each initiating event should be established. The second problem is that there is no responsibility matrix according to the occurrence of the initiating event. From a safety point of view, when a DBA occurs, the organization’s mission according to each initial event is described in the contingency plan, and related countermeasures are defined in case of an accident through Emergency Operation Procedure. In the case of physical protection, referring to IAEA’s Regulatory Guide 5.54, the organization’s responsibility is defined in matrix form when an initial event such as a bomb attack occurs. In this way, the responsibility matrix to be carried out in case of initiating events based on the defined initial event should be described in the contingency plan. In this paper, the problems of the cyberattack contingency plan are presented, and for this purpose, the definition of the initial event and the need for a responsibility matrix when the initial event occurs are presented.

This paper analyzed economic feasibility of aquacultural construction which of large-scale. The results of the economic analysis, cage cultural and water recycling cultural by post-water treatment were analyzed that NPV is 2,083,685 thousand won and －14,105,896 thousand won and B/C ratio is 0.590 and 0.855, respectively. These were shown economic infeasibility. But, running water culture by pre-water treatment(small scale) and running water culture by pre-water treatment(large scale) were analyzed that the one is 5,555,747 thousand won and 15,048,589 thousand won and the other is 1,154 and 1,1221, respectively. these were shown economic feasibility. In addition, measurement of B/C ratio through a sensitivity analysis on running water cultural by prewater treatment(small scale) and running water cultural by pre-water treatment(large scale) is economic feasibility in all cases. However, these were analyzed when the selling price was falling to 20 percent, it has shown economic infeasibility and when the selling price rises to 20 percent, water recycling culture by post-water treatment has economic feasibility. The significance of the study analyzed a sensibility as well as economic feasibility by methods and scales. It is expected that used as basic materials when constructing and operating of land aquaculture in order to minimize the damage from natural disasters.