[en] Trends of development and the state of Lithuanian power economy during the past few decades are analysed. Legacy of the past is assessed. A comprehensive analysis of forecasts and development scenarios of economy and its energy sector under free marked conditions is given. The problems of energy saving, main fuel supply and usage of demand resources are touched upon. Legal structures and reforms of energy sector are reviewed. The importance of nuclear power and the Ignalina NPP for Lithuania is emphasized. (author)

[en] Lithuania has more than one million of transport means, the thermal capacity of which is about 50 mill. kW, i.e. 10 times more than the capacity of all thermal power stations. In the 21st century electrical energy will be used for transport means instead of petrol, and new capacities of electric stations in Lithuania will be necessary. All perspective transport means are described and conclusions for Lithuanian energetics are presented. (author)

[en] The thermal analysis was performed on two types German made CASTOR RBMK-1500 and CONSTOR RBMK-1500 casks for interim storage of spent fuel at Ignalina NPP. Numerical calculation code ALGOR (USA) was used. The calculations were performed for different cases of single cask or cask in storage when it is just loaded with spent fuel and after 50 years of storage, for summer and winter conditions. It was established that in all cases the maximum temperature of fuel cladding never exceed the maximum allowable temperature. It was obtained that from the thermal point of view the casks can be used for the interim storage of spent fuel pre-stored for at least 5 years in water pools. (author)

[en] The paper offers a prognosis of the formation of air pollutants from Lithuanian power plants operating in the common Baltic electricity market according to two electricity production scenarios related with closure of the Ignalina NPP. According to Scenario 1, the closure date of Unit 1 of the Ignalina NPP is 2004 and of Unit 2 2009. According to Scenario 2, the closure date of Unit 1 is 2004, however, Unit 2 will be replaced by a new modern nuclear unit since 2010. In accordance with the both scenarios, formation of air pollutants will increase every year because of the growth of electricity demand. The influence of the largest air pollution source such as the Lithuanian TPP will be most significant to the situation in Lithuania, although the contribution of other power plants will remain more or less constant since 2005. The necessity of investments to the flue gas cleaning technologies (mainly from SO₂ and solid particles) remains in both scenarios, because the expected emissions exceed the engagements of Lithuania for admission to EC. (author)

[en] An experimental investigation of heat transfer in an inclined (φ = 20 degrees from horizontal position) flat channel with one-side heating (the upper wall is heated) for turbulent mixed convection opposing airflow conditions has been performed in the region of Re = 4 * 10³ - 4 * 10⁴, Gr_q = 1.7 * 10⁸ - 1.4 * 10¹⁰. The regularities of heat transfer in an inclined (φ = 20 degrees) flat channel have been found to be the same as at larger inclination angles. Using these and earlier published data for other inclination angles, the correlation has been suggested for the calculation of heat transfer rate for φ = 90 degrees - 20 degrees. (author)

[en] Radioactive waste management philosophies and technologies are still emerging, and there is therefore a need to reorganize and improve the national system for radioactive waste management in Lithuania. Lithuania's Law on Radioactive Waste Management and the new regulations will be harmonized with the European Union legislation in this field, with the IAEA general principles and with the obligations of the Republic of Lithuania under the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. Different organizational and financial schemes available in the EU countries for radioactive waste management are described and analyzed. The most important aspects needed to establish the Lithuania's Radioactive Waste Management Agency and Fund are defined and developed. (author)

[en] The international consensus has it that spent nuclear fuel (SNF) and long-lived high level radioactive wastes are best disposed of in geological repositories, using a system of engineered and natural barriers. Due to the danger of exposure arising from long-lived radionuclides to humans and the environment, SNF is not allowed to be disposed of in near-surface repositories. Performing the assessment of radionuclide migration (an integrated part of repository safety assessment) a description of the disposal system is required. The generic repository concept for RBMK-1500 SNF disposal in crystalline rocks in Lithuania is presented in this paper. The proposed repository concept is based on the KBS-3 concept developed by SKB for the disposal of PWR and BWR spent nuclear fuel in Sweden. The generic repository concept for SNF disposal in crystalline rocks in Lithuania foresees the SNF disposal in the parallel horizontal emplacement tunnels with a diameter of 1.85 m and length of 250 m at a depth of 300-500 m. Based on thermal calculations, in case of the distance of 1.2 m between the canisters and the distance of 40 m between the tunnels, the repository would cover an area of appr. 0.4 km². The preliminary data on the copper canister for RBMK-1500 SNF are 1050 mm in diameter and 4070 mm in length, and it could hold 32 RBMK- 1500 SNF half-assemblies. For the disposal of spent nuclear fuel from the Ignalina Nuclear Power Plant, 1400 canisters would be required. For the isolation of the canisters, bentonite with a thickness of 0.35 m is proposed. For the backfilling of the main tunnels, shafts and ramp, a mixture of crushed rock and bentonite is selected. (author)

[en] The Accident Localisation System (ALS) of the Ignalina NPP is a 'pressure suppression' type confinement which protects the population, employees and environment from the radiation hazards. According to the Safety Analysis Report for the Ignalina NPP, about 110 m³ of hydrogen is released to ALS compartments during the Maximum Design Basis Accident. If the volume concentration of hydrogen in the compartment reaches 4%, there is a possibility for a combustible mixture to appear. However, the flammability of hydrogen depends on the air and steam concentrations. In the NPP hydrogen appears due to water radiolysis during normal operation and steam interaction with zirconium (this mechanism is related to severe accidents). In this paper, the calculation results of hydrogen distribution in the Ignalina NPP ALS during Maximum Design Basis Accident are presented. (author)

[en] The processes that might occur during beyond-design-basis accidents (BDBA) in vessel-type light water reactors are rather well known, but many questions and uncertainties still remain. Experimental and analytical research is performed around the world to decrease the remaining uncertainties and develop reliable computer codes for simulation of the processes that could occur in the reactor core and containment in case of beyond-design-basis accidents. Understanding these phenomena would help developing strategies for the management of related accidents. This paper discusses the differences of RBMK-1500 from vessel-type reactors (BWR and PWR), identifies the possible BDBA scenarios and presents an approach to accident management that could be further developed at the Ignalina NPP to prevent accident developing into a severe accident. (author)

[en] The paper deals with the application of the MESSAGE model for analysis of the energy sector development in three Baltic countries - Estonia, Latvia and Lithuania. The main issue for the Baltic countries is an efficient, secure and environmentally benign manner of power system development after the predetermined closure of the Ignalina NPP, the biggest power plant in the region. The paper focuses on the methodology of analysis, describes in detail the structure of the multi-regional model, presents options analysed for the future power system development, gives characteristics of the scenarios analyzed. The paper focuses on highlighting the circumstances under which a new nuclear power plant can be economically justified in the region. (author)