[en] Fourth Regional Meeting for Nuclear Energy in Central Europe is an annual meeting of the Nuclear Society of Slovenia. The proceedings contain 89 articles from Slovenia, surrounding countries and countries of the Central and Eastern European Region. Topics are: Research Reactors, Reactor Physics, Probabilistic Safety Assessment, Severe Accidents, Ageing and Integrity, Thermal Hydraulics, NPP Operation Experiance, Radioactive Waste Management, Environment and Other Aspects, Public and Nuclear Energy, SG Replacement and Plant Uprating.

[en] The licensing of the power uprating and steam generator replacement (PUSGR) of a nuclear power plant is a long multiple-step process. This paper describes the numerous aspects investigated during the PUSGR of Tihange 1, as seen by AVN, the technical support of the Belgian authorities. The main aspects covered are: 1) the regulatory context and the licensing procedure, 2) the safety studies: choice of the operating domain, data base for the accident analysis, methodologies for these analysis, reference core loading pattern and nuclear design, thermohydraulic studies and safety limits, justification for not reanalysing accidents not affected by the PUSGR, accident analysis (design basis accidents), transient analysis, verification of the capacity of safety systems and auxiliary systems, radiological consequences of accidents, regulations and protections, transition cycles, mechanical studies, 3) the follow-up of construction and installation activities, 4) the requalification and commissioning tests on site, 5) the upgrading of documents (procedures, Safety Analysis Report, Technical Specifications...). (author)

[en] Special developed tools for research reactor maintenance are described and their application at a 32 years old TRIGA type reactor is discussed. (author)

[en] Presented is the so-called PLUSS Sleeve. The basic idea was to take the adventage of different material characteristics between sleeve and SG tube. To this day was installed 1235 tubes in 3 plants which are operating successfully, two of them for more than two years. From our point of view the presented development and qualification of the new SG tube repair technique will replace most of the plugging processes of SG tubes in the future.

[en] This paper describes the Fire Protection Action Plan which prioritized proposed fire protection modifications from recommendations reported in the NPP Krsko Fire Hazards Analysis - Safe-Shutdown Separation Analysis (SSSA), the ICISA Analysis of Core Damage Frequency Due to Fire at the Krsko Nuclear Power Plant, and the Operational Safety Review Team (OSART) reports using a risk-based cost/benefit methodology. (author)

[en] The development of eddy current ''+Point'' probing technique makes possible to meet demands of finding small cracks in difficult parts of steam generator tubing, such as top of tube sheet and sleeved part of tube. Another application of ''+Point'' probe is surface examination of weld or other rough surfaces. This article present way of detecting direction of cracks as well as on site inspection experience. (author)

[en] The radiological impact of all operations is monitored as part of the license obligations, imposed by the South African Nuclear Energy Act. The occupational exposure at the Koeberg NPP showed an average value of about 0,90 mSv for the years 1994 and 1995. Liquid and gaseous effluents discharged from this plant in 1995 resulted in a calculated radiation dose to the public of about 0,45 μSv per year. Compared with the nuclear industry, the occupational and public exposure imposed by the mining and mineral processing industries is more difficult to assess due to the numerous potential transport mechanisms and pathways of the natural radioactivity. Yearly doses could be as high as 20 to 40 mSv per year in certain areas of copper and heavy mineral processing industries. The public exposure could accumulate up to a few mSv per year.

[en] NPP Krsko has experienced in last 5 years (1991-1996) a major safety analysis review and assessment. All this activities can be divided in five different categories: First category is international missions. Five different missions visited Krsko since 1991 (ICISA, OSART, WANO AND ASSET). Second category is one of the most systematic and comprehensive PSA analysis conducted at nuclear power plants which included Level 1, Level 2, External events and PSA assessment of shutdown modes. Third category represents the systematic compliance review and creation a list of the NRC regulatory requirements issued since 1975 to 1995 and applicable to NPP Krsko. Fourth category is review of all modifications, which were performed at NPP Krsko. Fifth category represent detailed analysis of important safety issues. All five categories included at different level of details, safety review of all areas in design, operation and maintenance. All this activities in last 5 years resulted in different lists of issues, which are now under implementation, and many of them are already resolved and completed. If all this activities are integrated into one single systematic and comprehensive effort they can be by it content and form compared to the periodic safety review and assessment conducted at many countries in Europe. (author)

[en] The Nuclear Regulatory Authority of the Slovak Republic as the state authority provides information related to its competance, namely information on safety operation of nuclear institutions, independently from nuclear operators and it enables the public and media to examine information on nuclear facilities. Described are the means of communication and work programs, and the public concerning the emergency planning and exercises. Presented are the activities of Nuclear Regulatory Authority of Slovakia in 1996.

[en] The paper describes NPP Krsko (NEK) PSA data collection and analysis process which is needed to support the NEK PSA Program. NEK plant specific data are collected and analysed by PSA Data Analyst. The PSA Data Analyst uses NEK plant specific data along with generic data as necessary to estimate probabilities and other statistical information required for the quantification of the NEK PSA Model. The data are also valuable in the other programs in the process of the execution or planned at the NEK, like ''Station Blackout Rule'', ''MOV Program'', ''Maintenance Rule'' and the future ''Data Rule'' that is under consideration by the U.S. NRC. Updated ''NEK PSA Plant Specific Data Base'' document at the moment include the period of the 13 years of NEK operating experience, and was developed in order to support the NEK Living PSA Program. According to that, the document ensure the valid and acceptable data base for the intended purpose of the future update of the NEK PSA Model, and other PSA related programs. The primary purpose of this paper is to define the basis and the scope, and then to specify the steps of NEK plant specific data collection and analysis process. According to established procedure, the process collect and analyse different types of NEK plant specific data sources (operating records, various types of documents, procedures, etc.) which contribute to one or more types of ''raw data'' that are used to derive the parameter estimates needed for the quantification of the NEK PSA Model. Consistent data collection and processing are necessary. The eleven basic types of tables plus data calculations parts and final ''NEK Data Processing Table'' provides a systematic and organized means for development of the ''NEK PSA Plant Specific Data Base''. The processed data which appeared in the ''NEK Data Processing Table'' came from the four different processes (or sources): generic data, plant specific data, bayesian data update process, calculated data. The final products of data collection and analysis effort are demand based failure probabilities, operating time based failure rate and Tand M unavailabilities as applicable to NEK plant specific components or systems of concern. (author)