[en] Based on materials of the GTDC symposia and workshops, the paper discusses the situation with power supply of countries and world regions with small and medium power networks. A proposal is made on the use of low power NPP for such regions. Characteristics of modular gas-turbine high temperature gas cooled reactors are presented, which can be used as a basis for development of environmentally friendly and safe NPP for power production. (author)

[en] The selected set of risks associated with reactor shutdown in PWRs are outlined and discussed (e. g. outage planning, residual heat removal capability, rapid boron dilution, containment integrity, fire protection). The contribution of different outage strategies to overall core damage risk during shutdown is assessed for a particular basic outage plan. The factors which increase or minimize the probability of reactor coolant boiling or core damage are analysed. (author)

[en] At the end of the operational lifetime of a nuclear power plant (NPP) it is necessary to take measures for the decommissioning as stated in different international regulations and also in the national Slovenian law. Based on these requirements Slovenian authorities requested the development of a site specific decommissioning plan for the NPP KRSKO. In September 1995, the Nuklearna Elektrarna Krsko (NEK) developed a site specific scope and content for decommissioning plan including the assumptions for determination of the decommissioning costs. The NEK Decommissioning Plan contains sufficient information to fulfill decommissioning requirements identified by NRC, IAEA and OECD - NEA regulations. In this paper the activities and the results of development of NEK Decommissioning Plan consisting of the development of three decommissioning strategies for the NPP Krsko and selection of the most suitable strategy based on site specific, social, technical, radiological and economical aspects, cost estimates for the strategies including the costs for construction of final disposal facilities for fuel/high level waste (fuel/HLW) and low/intermediate level waste (LLW/ILW) and scheduling all activities necessary for the decommissioning of the NPP KRSKO are presented. (author)

[en] The analysis evaluate the consequences of the removal of the autoclosure interlock (ACI) on the Residual Heat Removal System (RHRS) suction/isolation valves at the nuclear power plant. The deletion of the RHRS ACI is in part based on a probabilistic safety analysis (PSA) which justifies the removal based on a criterion of increased availability and reliability. Three different areas are to be examined in PSA: the likelihood of an interfacing system LOCA, RHRS unavailability, and low temperature overpressurization control. The paper emphasises particularly the RHRS unavailability and the likelihood of an interfacing system LOCA evaluation utilising the current control circuitry configuration and then with the proposed modification to the control circuitry. (author)

[en] Instantons contributions to nonleptonic decays in chiral-bag model are the subject of this study. The instanton induced-term was introduced in chiral-bag model based analysis of K→π decays. Almost perfect fit of the experimental data was possible with the induced-term coefficient C₁≅1.4. However, this conclusion, which is appreciably larger than the rough theoretical estimate (which was C₁=0.15) depends on the approximation used in the theoretical approach. Also, the μ-dependence of the operator matrix elements were studied. Although the μ-dependence must in principle cancel as was illustrated by using a simple model, in practice the choice of μ markledy influences the theoretical predictions for K→2π decays, with and without instantons. Nonleptonic strangeness-changing hyperon decays were also considered together with instanton induced term. The same type of analysis has led previously to a reasonable qualitytive, and to some extent quantitative, description of the decay amplitudes. The instanton contributions do not improve old results. Data favor a very small instanton influence. (author)

[en] Harmful effects of UV light involves cell killing, mutagenesis and neoplastic transformation of exposed cells. The effect of UV light depends on the wavelength, dose irradiation, type of exposed cells, endogeny substance, experimental condition that can increase or decrease sensibility of the cells on the UV light. The loss of viability is the end point of cellular dysfunction, however, UV irradiation may affect cells function before it is perish. We examined the killing modes of cell death, necrosis or apoptosis, depending on the way of the cellular elements involved in process. Necrosis is a pothologic response involving a dramatic increase in cell volume that ultimately leads to cell lysis, usually caused by damaging of cell membrane. Apoptosis or genetically programmed cell death is result of complex cell mechanisms. Mouse spleen cells were diluted to 8.5·10⁶/mL in Hanks' solution. Cells spread in thin layers (2mm) in glass Petri dishes were exposed to the different doses of UVC light. After irradiation and staining with fluorescein diacetate (FDA) and propidium iodide (PI) solution, the viable cells, as well as apoptosis were observed under fluorescent microscope. Immediately after UV irradiation the number of viable cell rapidly decreased. Lower doses of UVC light caused apoptosis as well as necrosis of exposed cells. Around 10% of spleen cells commit suicide after UVC exposure. There was significantly higher percentage of apoptotic cell than in control non irradiated sample. The highest fluence (1280J/m²) of UVC light, lysed considerable number of lymphocytes, around 80%. Small fraction (15%) of cells survived used UVC light. Noticed resistance of spleen cells is not completely clear, but results suggest that it due to the present of mature lymphocytes, which could not proliferate, and are less sensitive to UV light. In spite of this our results confirm that UVC light is capable to cause DNA damage, apoptosis and necrosis of mouse spleen cells. (author)

[en] Most of the artificial ionizing radiation sources are located in medical institutions. The largest contribution to popular irradiation, apart from natural sources, also originates from their use. The application of ionizing radiation in medicine is continuously developing and spreading. Not only the individual absorbed dose is steadily growing, the whole population is more and more exposed. By lung radiogram analysis, important diagnostic data are obtained for tuberculosis treatment. So chest radiography remains the most important method at diagnosing and attending TB patients, children or adults equally. Unfortunately, radiological treatment is accompanied by the risk of radiation doses being received on organs which are unprotectable during examination. It should be remembered that TB patients are frequently x-rayed, whereby the accumulated dose, and the damage risk increase. To make the risk as small, and the benefit of ionizing radiation use as big as possible, certain principles have to be followed: a) Treat a patient with x-rays only if there is a positive and justified medical indication. b) If it is unavoidable, it has to be performed in an institution where technique and protection methods are well known to the staff. c) Monitor the received radiation doses by using suitable and precise dosimetry equipment. (author)

[en] In this paper is presented that accreditation in our days is a strict requirement for a lab for its results could be accepted on international level. Accreditation itself brings to new requirements, among them some are related to the calibration of the radiological measuring equipment

[en] Dose-effect curve for X-radiation was made based on the analysis of chromosome aberrations in lympocytes of goats. Blood samples from seven goats were irradiated using MOORHEAD method, slightly modified and adapted to our conditions. Linear-square model was used, and the dose-effect curves were fitted by the smallest squares method. Dose-effect curve (collective) for goats is displayed as the following expression: y(D)= 8,6639·10^-3 D + 2,9748·10^-2 D²+2,9475·10^-3. Comparison with some domestic animals such as sheep and pigs showed differences not only with respect to linear-square model, but to other mathematical presentations as well. (author)

[en] Safety assessments are usually performed to gain acceptance or approval for disposal of accumulated waste, demonstrating compliance with national regulations for a particular facility. However, the preliminary assessment for Croatian LILW repository should generally focus on providing reasonable assurance both to the public and to decision makers that the Croatian share of LILW from NPP Krsko - which is still in Slovenia - can be admitted and safely disposed of in Croatia. More specifically, the assessment should clearly present all realistic options and compare the associated long term repository performances, demonstrating that desirable safety goals can be achieved by an appropriate choice of (a) location, (b) facility design, (c) institutional control period and (d) waste acceptance criteria. As relevant national legislation does not require any safety analyses at this early phase of repository planning, generally recognized international safety standards, practices and recommendations (e.g. as presented in the recent IAEA publications) can provide guidance through the assessment process, while the results should be evaluated against national regulations. (author)