Preparation for Early Termination of Ignalina NPP Operation

Seimas (Parliament of Lithuania) approved updated National Energy strategy where it is indicated that first Unit will be shutdown before the year 2005 and second Unit in 2009 if funding for decommissioning is available from EU and other donors. In accordance to Ignalina NPP Unit 1 Closure Law the Government of Lithuania approved the Ignalina NPP Unit 1 Decommissioning Program until year 2005. For enforcement of this program, the plan of measures for implementation of the program was prepared and approved by the Minister of Economy. The plan consists of two parts, namely technical- environmental and social-economic. Technical-environmental measures are mostly oriented to the safe management of spent nuclear fuel and operational radioactive waste stored at the plant and preparation of licensing documents for Unit 1 decommissioning. Social-economic measures are oriented to mitigate negative social and economic impact on Lithuania, inhabitants of the region, and, particularly, o n the staff of Ignalina NPP by means of creating favorable conditions for a balanced social and economic development of the region. In this paper analysis of planned activities, licensing requirements for decommissioning, progress in preparation of the Final Decommissioning Plan is discussed

Modelling of the aiding mixed convection in a vertical rectangular channel

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Many researchers have analyzed laminar and turbulent mixed convection in channel flows, however, despite their wide investigations, there are still many cases which are not well understood and difficult to predict. Investigations of heat transfer in the laminar-turbulent (transition) region under the effect of buoyancy (mixed convection) are rather limited. In this paper the results on numerical investigation of the local aiding mixed convection heat transfer in the laminar-turbulent (transition) region in a vertical rectangular channel are presented. Numerical 3D steady state simulations have been performed using Ansys Fluent code in air flow. Modelling has been performed using laminar and transitional (kkl-ω, SST and Re Stress ω) models. Modelling results demonstrate that vortexes exist in the central part of the channel. This makes velocity profiles asymmetrical. The results of numerical modeling have been compared with the results of experiments performed at the same conditions and previous results of 2D numerical modelling using laminar modeldc201

Comparative analysis of numerical methods used for thermal modeling of spent nuclear fuel dry storage systems

Management of spent nuclear fuel is a very important part in the whole cycle of nuclear energy generation. Usually “dry” storage technology in casks is selected for the interim storage of spent nuclear fuel for up to 50 years after pre-storage time in water pools. In this paper, two case studies were carried out to highlight the differences and similarities between Ukraine and Lithuania in spent nuclear fuel storage.Управління відпрацьованим ядерним паливом є дуже важливою частиною всього циклу виробництва ядерної енергії. Зазвичай технологія «сухого» зберігання в контейнерах вибирається для тимчасового зберігання відпрацьованого ядерного палива протягом до 50 років після часу попереднього зберігання у водних басейнах. У цій статті були проведені два тематичних дослідження, щоб підкреслити відмінності і подібності між Україною та Литвою в області зберігання відпрацьованого ядерного палива.Управление отработанным ядерным топливом является очень важной частью всего цикла производства ядерной энергии. Обычно технология «сухого» хранения в контейнерах выбирается для временного хранения отработанного ядерного топлива в течение до 50 лет после времени предварительного хранения в водных бассейнах. В этой статье были проведены два тематических исследования, чтобы подчеркнуть различия и сходства между Украиной и Литвой в области хранения отработавшего ядерного топлива

PREPARATION FOR EARLY TERMINATION OF IGNALINA NPP OPERATION

ABSTRACT Seimas (Parliament of Lithuania) approved updated National Energy strategy where it is indicated that first Unit will be shutdown before the year 2005 and second Unit in 2009 if funding for decommissioning is available from EU and other donors. In accordance to Ignalina NPP Unit 1 Closure Law the Government of Lithuania approved the Ignalina NPP Unit 1 Decommissioning Program until year 2005. For enforcement of this program, the plan of measures for implementation of the program was prepared and approved by the Minister of Economy. The plan consists of two parts, namely technicalenvironmental and social-economic. Technical-environmental measures are mostly oriented to the safe management of spent nuclear fuel and operational radioactive waste stored at the plant and preparation of licensing documents for Unit 1 decommissioning. Social-economic measures are oriented to mitigate negative social and economic impact on Lithuania, inhabitants of the region, and, particularly, on the staff of Ignalina NPP by means of creating favorable conditions for a balanced social and economic development of the region. In this paper analysis of planned activities, licensing requirements for decommissioning, progress in preparation of the Final Decommissioning Plan is discussed

Investigation of characteristics of solid particles from a mixture of sewage sludge and wood pellets synthetic gas and their clean-up

The most reasonable way to utilise sewage sludge in Europe is in energy production. In the process of thermochemical conversion of sewage sludge, combustible gas is produced. Studies of synthetic gas composition show that this gas contains various impurities, which must be cleaned before gas supply to the final user. Although there are many ways to clean toxic materials existing in the synthetic gas, the application of plasma treatment seems the most promising. Exposure to the high temperature of plasma changes the structure and the chemical composition of solid particulates existing in the gas. In this study on the synthetic gas, ESP cleaning efficiency, size and elemental analysis of solid particles collected from different parts of the experimental setup with a gasifier operating on a mixture of sludge and wood pellets were analysed. The results showed the difference in particle sizes and changes in elemental composition of particles collected from different parts of the experimental setup. It was determined that the synthetic gas obtained by gasification of a mixture of sludge and wood pellets contains a great concentration of solid particles, which leads to the total collection efficiency of an electrostatic precipitator being only about 60 %

Modelling of the Radiological Contamination of the RBMK-1500 Reactor Water Purification and Cooling System

This paper presents modelling results on the RBMK-1500 reactor water purification and cooling system (PCS) components contamination at Ignalina NPP Unit 1. The modelling was performed using a computer code LLWAA-DECOM (Tractebel Energy Engineering, Belgium), taking into consideration PCS components characteristics, parameters of the water flowing in circuits, system work regimes, and so forth. During the modelling, results on activity of PCS subsystems and components’ deposits and nuclide composition of deposits at the moment of the final shutdown of the reactor, as well as activity decay of the most contaminated PCS components’ deposits and dose rates after the final shutdown of the reactor, were obtained. Significant difference of contamination levels was revealed among PCS subsystems and subsystems components. The subsystem of nonpurified water is the most contaminated in PCS, and the activity of the least contaminated component in this subsystem is only 1.42% compared to the activity of the most contaminated component. The most contaminated and the least contaminated components of the purified water subsystem comprise 28.33% and 0.86% of activity, respectively, compared to the activity of the most contaminated PCS component

Analysis of radionuclide release through EBS of conceptual repository for Lithuanian RBMK spent nuclear fuel disposal : case of canister with initial defect

This paper presents research on radionuclide transport from generic geological repository for the RBMK-1500 SNF of 2.8 235U initial enrichment (with Er absorber) and average burn-up of ~ 29 MWd/kgU. Radionuclide transport analysis was focused on the engineered barrier system (EBS) and performed taking into account possible differences in the data on the initial size of a canister defect, defect enlargement time and radionuclide release start time. For the numerical simulations, computer code AMBER (UK) was used. The analysis of radionuclide transport regularities demonstrates that the release from the EBS is the most intensive after the defect enlargement. Most relevant radionuclides were identified based on the mass transfer analysis complemented by the analysis of radiotoxicity flux. The results showed that, depending on the differences of the initial defect size, defect enlargement time and release start time, the peak flux from the EBS may vary by a factor of 2 (for 129I) and 1.5 (for 226Ra) for RBMK-1500 SNF