No abstract available

[en] To perform Total System Performance Assessment(TSPA) of a potential HLW repository, it is necessary to develop the TSPA code. KAERI has developed the one-dimensional PSA code MASCOT-K since 1997 and verified special modules dedicated for the dissolution of spent nuclear fuel. In the second R and D phase, MASCOT-K is once again verified as a part of the confidence building for TSPA. The AMBER code based on the totally different mathematical approach, compartment theory is used together with MASCOT-K to assess the annual individual doses for given K- and Q- scenarios. Results indicate that both AMBER and MASCOT-K simulate the annual individual doses to a potential biosphere. And the MASCOT-K is more flexible to describe the natural barrier such as a fracture for sensitivity studies. In the third R and D phase, MASCOT-K will be actively used to check whether the proposed KAERI reference disposal concept is solid or not

[en] The Periodic Safety Review(PSR) of the existing nuclear power plants is required every ten years according to the recently revised atomic energy acts. The PSR of Kori unit 1 and Wolsong unit 1 that have been operating more than ten years is ongoing to comply the regulations. This research project started to develop the techniques necessary for the PSR. The project developed the following four techniques at the first stage for the environmental assessment of the existing plants. 1) Establishment of the assessment technology for contamination and accumulation trends of radionuclides, 2) alarm point setting of environmental radiation monitoring system, 3) Development of Radiation Safety Evaluation Factor for Korean NPP, and 4) the evaluation of radiation monitoring system performance and set-up of alarm/warn set point. A dynamic compartment model to derive a relationship between the release rates of gas phase radionuclides and the concentrations in the environmental samples. The model was validated by comparing the result with the samples. The results of the research will be used in the Periodic Safety Review of the nuclear power plants in operation

[en] The evaluation technology of decommissioning process must be developed and will be used for the ALARA planning tool of decommissioning process and demonstrated for tools of decommissioning equipment. Also, this technology can be used for tools workplaces with high work difficulty such as large-scale chemical plant, under water and space. The monitoring system for high alpha radioactive contamination measurement will be use in the high radioactivity decommissioning sites such as hot-cell or glove box. Also, it will be use in the general nuclear facilities as the radiation monitoring unit. The preparation technology of the radiation sensor for high radioactive contamination measurement will be transferred to the company for the industrialization. The remote monitoring system can prevent the workers exposure using the optical fiber to separate the sensor and electronics

[en] Oxidation of SiC produces SiO₂ while CO is released. A ''reoxidation'' step at lower temperatures is, however, necessary to produce high-quality SiO₂ . This step is believed to cleanse the oxide of residual C without further oxidation of the SiC substrate. We report first-principles calculations that describe the nucleation and growth of O-deficient C clusters in SiO₂ under oxidation conditions, fed by the production of CO at the advancing interface, and their gradual dissolution by the supply of O under reoxidation conditions. We predict that both CO and CO₂ are released during both steps

[en] Technology development on lithium induced matallization process is the key to safely manage spent fuel. To understand its importance on the nuclear fuel cycle, its impact on the radwaste disposal has been studied. Firstly, the inventories of major nuclides have been assessed for both metal forms and solid waste forms from molten salt processes. Then specific decay heat per mass was calculated and summation of exponential functions was created to fit the change of decay heat as a function of time. The decay heat information was used to determine the optimum layout of a repository whose pitch distance is determined by the temperature constraint of a buffer layer. Also post closure radioactive safety was assessed. Results showed that the Li induced metallization process can save the area for disposal by half and enhance the safety of the repository system. However, the pilot scale design concept is needed to understand cost of the process in the future

[en] In TSPA of long-term post closure radiological safety on permanent disposal of HLW in Korea, appropriate management of input and output data through QA is necessary. The robust QA system is developed using the T2R3 principles applicable for five major steps in R and D's. The proposed system is implemented in the web-based system so that all participants in TSRA are able to access the system. In addition, the internet based input database for TSPA is developed. Currently data from literature surveys, domestic laboratory and field experiments as well as expert elicitation are applied for TSPA

[en] The design load considered in the evaluation is the dead weight and the thermal load for transients. The purpose of this study is to evaluate the structural integrity for the design configurations and dimensions of the UIS in the PGSFR, which is performed for the loading condition including the thermal transients according to the ASME Div.5-HB. The maximum stress is 2.39 MPa, which occurs in the geometrical discontinuity of the upper part of the UIS slot

[en] For better cooperation in the field of radioactive waste management between Korea and Finland, the nuclear industry in Finalnd focusing its strategy and capabilities is studied. The strength of the Finnish program is in the site securing, disposal concept development with cost analysis, site investigation, and safety analysis. KAERI and Finnish delegates visited each other and held a joint seminar on the field of radioactive waste management. The future cooperation areas will be cost analysis and potential participation in the Onkalo project. Finnish DiP is effective to get consensus among many different stakeholders. Further independent study is recommended in this area

[en] In general, the economic payoffs exceed costs of building and operating the new center, since most incumbent firms have firm technological capabilities and are expected to grow in a constant trend for the future. The main functions for the proposed business center for start-up businesses would be as followings : providing incubating facilities, consulting on management and supplying technical know-how