[en] AI-Qaeda and other terrorist groups have tried to obtain the radioactive material which could be used to make a dirty bomb, and their documents relating to dirty bombs were found in the January 2003. International communities especially, the United States has made efforts to improve infrastructure of radiation regulation and security of radioactive material for protecting its people from radiological attacks. This study examines the likelihood of radiological terrorism and the radiological dispersal devices which could be used by determined terrorists, and the trend of international communities to respond it through improvement on radiation regulation and security

[en] This test procedure details the test loop, test method, and test procedure for pressure drop, vibration and endurance test of Non-instrumented Capsule of Advanced PWR Fuel Pellet. From the pressure drop test, the hydraulic design requirements of the capsule are verified. HANARO limit condition is checked and the compatibility with HANARO core is verified. From flow induced vibration test vibration frequency, vibration displacement are investigated. The wear of Non-instrumented Capsule of Advanced PWR Fuel Pellet is investigated through endurance test, and these data are used to evaluate the expected wear of during maximum resident time of Non-instrumented Capsule

[en] Radiation technologies are being utilized in a wide range of daily modern life and provide the public with valuable benefits through applications in fields of medical, industrial, agricultural, and science and engineering research. On the other hand, there is a high possibility that radioactive materials could be used for potentially malevolent purposes such as dirty bombs. International community, therefore, has made efforts to improve security of radioactive sources for protecting the public from radiological terrorism. This study investigated current status of radiation technologies and radioactive sources which could be used by radiological dispersal devices. This paper also reviewed the possibility of radiological weapon attacks, international trends and our methods to enhance security of radioactive sources

[en] As the digital technology is being developed drastically, it is being applied to various industrial instrumentation and control (I and C) fields. In the nuclear power plants, I and C systems are also being installed by digital systems replacing their corresponding analog systems installed previously. There had been I and C systems constructed by analog technology especially for the reactor protection system in the research reactor HANARO. Parallel to the pace of the current trend for digital technology, it is desirable that all I and C systems including the safety critical and non-safety systems in an advanced research reactor is to be installed based on the computer based system. There are many attractable features in using digital systems against existing analog systems in that the digital system has a superior performance for a function and it is more flexible than the analog system. And any fruit gained from the newly developed digital technology can be easily incorporated into the existing digital system and hence, the performance improvement of a computer based system can be implemented conveniently and promptly. Moreover, the capability of high integrity in electronic circuits reduces the electronic components needed to construct the processing device and makes the electronic board simple, and this fact reveals that the hardware failure itself are unlikely to occur in the electronic device other than some electric problems. Balanced the fact mentioned above are the roles and related issues of the software loaded on the digital integrated hardware. Some defects in the course of software development might induce a severe damage on the computer system and plant systems and therefore it is obvious that comprehensive and deep considerations are to be placed on the development of the software in the design of I and C system for use in an advanced research reactor. The work investigates the domestic and international standards on the classifications of digital software for use in I and C systems in nuclear power plants and describes the requirements for software development recommended by international standard

[en] This paper analyzes the trend of international nuclear export control system which has been strengthened since 9.11 terrorism and the problems of the amended guidelines which are being applied to the national regulation of each participating governments

[en] In an advanced HANARO reactor (AHR), the instrumentation and control (I and C) systems are designed based on the digital system rather than the analog system installed in an existing HANARO instrumentation and control systems. While the safety and functionality of analog-based instrumentation and control system are experienced over a long period of operating time and also well-validated, the obsolescence and the lack of flexibility of this system have to move from the analog technology to the digital technology in the instrumentation and control systems to be used in nuclear power plants as well as nuclear research reactors. For establishing the adequate structure of instrumentation and control systems for an AHR, various instrumentation and control architectures are analyzed for their merits and demerits for use in I and C systems of an AHR and the most promising instrumentation and control architecture for an AHR are drawn from this analysis. The conceptual configuration of a digital-based safety shutdown system is proposed in this report

[en] The analog seismic monitoring system for HANARO has been improved into a new digital Seismic Monitoring Analysis System(SMAS). For this purpose, the digital type hardware for the SMAS was newly developed. And the seismic monitoring and analysis programs that can provide a rapid and precise information for an earthquake were developed. In order to confirm the functional capability of the developed SMAS, the Site Acceptance Test(SAT) was performed. The results of the SAT satisfy the requirements of the fabrication technical specifications. In addition, the structural integrity and seismic characteristics of the newly developed SMAS were evaluated. The evaluated results demonstrate that the SMAS has adequate structural integrity and it can withstand the seismic loads and remain functional. The developed SMAS is successfully operating in the HANARO instrument room for monitoring and analyzing the signal of an earthquake at the HANARO site. The Seismic Evaluation System(SES) that can perform rapid evaluations of the seismic safety of the reactor building has been developed. After an earthquake, using the seismic signal obtained from the field sensors, the developed SES can perform a detail 3-D seismic analysis of the reactor building and some local analyses of the safety related system required for the assessment of the seismic safety of the HANARO building. In addition, the developed seismic evaluation system equipped with the post processing capability to display analysis results graphically or in report form. It is expected that the SES can be utilized for the evaluation of the seismic safety of the HANARO reactor building and the safety related seismic category structures after an earthquake

[en] In the course of the visual inspection of the fuel assemblies un-loaded from the reactor core in December 1996, it was observed that many of fuel assemblies had mechanical damages on some components. The major damage was the freting-wear on spacer plates and endplates due to the flow induced vibration of the fuel assembly in the flow tube. Since the reactor is activated and the system modification for complete removal of the driving factors of the vibration of fuel assemblies is practically very difficult, the focus has been on the design change of the fuel assemblies. Consequently, various design changes were proposed to strengthen the wear resistance of the components based on the evaluation of the visual inspection results. The validity of the proposals was verified through the performance tests for the modified components, and the vibration test and endurance test for the fuel assemblies using the single-channel test rig(SCTR) in AECL.The subsequent design changes were additionally proposed based on the visual inspections for the fuel assemblies that had been fabricated according to the first design change and loaded in the core. As the effects of the first design change, the fretting-wear of spacer plates was remarkably reduced and the period until fretting-wear damage was extended by 60% for the first modified 36-rod fuel assembly. It is too early to say the endurance life time for the first modified 18-rod fuel assembly because of insufficient statistical data of only two bundles damaged, but the fretting-wear at the bottom endplate slot was reduced to about 50%. The second modified fuel assemblies, that were not loaded into the core yet, are expected to meet the design requirements for the core residence time due to strengthening the weak parts from the fretting-wear point of view. This report describes design changes and tests for fuel assemblies of HANARO to reduce the fretting-wear, and estimates the effects of design improvement quantitatively compared with the original fuel assemblies through the visual inspections of the fuel assemblies loaded in the reactor

[en] In the MMIS (Man-Machine Interface System) conceptual design requirements as a part of the instrumentation and control (I and C) for the advanced research reactor, the basic conceptual framework is decided that all the alarm system and information for the reactor operation are displayed on the display device on the work space of an operator, discarding the conventional operation mechanisms by moving through alarms and records spread over various boards of a control room. For the conceptual framework, the MMIS should be configured based on the digital system rather than the analog system whose dependability has been accumulated from the past operating experiences, because the existing analog system lacks of the capability of proving a human-centered information display environment that requires highly flexible and multi-functional capabilities. From a thorough review of the human-machine requirements for nuclear power plants and of the existing materials for research reactors, the conceptual design requirements for the MMIS of an advanced research reactor are established and they are as follows: Compact operator workstation, Large scale information display, Functionally organized alarm system, Information navigation in station, Staff organization in the control room, Intelligent operator aids, Level of automation, and Information redundancy

[en] Instrumentation and control system is to regulate reactor power automatically and to perform protective functions to shut down the reactor safely in case of an accident threatening the reactor safety. If the protective action would not be properly activated, an abnormal situation might be connected to a significant radiation hazard, even though a research reactor is maintained at low pressure and low temperature condition. For this reason, the reactor protection system for the advanced research reactor will be designed as per the safety design requirements for nuclear power generating stations. System classification are suggested based on the HANARO concept. Considering an international growing tendency toward nuclear safety enhancement and supplement of the existing one, a revised classification system will be applied to the components, structures and systems for the advanced research reactor. The reactor protection system is classified to the safety class and the others are non-safety grade. Based on the HANARO experience, the design guide aims at the improvement of reliability of safety and achievement of automatic control and signal processing by digitalization. To satisfy functional diversity requirement, the first shutdown system adopts a concept of control rod with a stepping motor while the second shutdown system uses D₂O dump system. The first shutdown system will use a PLC-type digital logic processor but the second shutdown system will use a conventional relay logic for the concept of equipment diversity. The reactor protective function for the advanced research reactor has a higher reliability by using two different shutdown mechanism. Although most of the instrumentation systems, except the reactor protection system are classified to non-safety grade, some systems like reactor regulation system or engineered safety feature actuation system selectively adopts the safety design requirements in order to ensure the safety-related function. All of the system control will be accomplished by a digital computer techniques and they are networked all together for comprehensive data display and management