• safety assessment of nuclear power plants;

• thermal-hydraulic analysis of accident and transient processes;

• assessment of change of thermal-hydraulic parameters in NPP containment and other compartments;

• simulation of radionuclides and aerosols transport in the compartments;

• assessment of nuclear reactor core modifications and analysis of postulated reactivity accidents;

• safety analysis of thermonuclear fusion reactors;

• analysis of new nuclear power plants;

• reliability estimation and control of energy systems;

• Level 1 and Level 2 probabilistic safety assessment of NPP;

• assessment and prognosis of the NPP graphite stack-fuel channel gap closure dynamics;

• strength analysis of constructions, piping and other elements of complex technical systems;

• single failure analysis and engineering assessment for complex technical systems;

• risk and hazard assessment of industrial objects;

• assessment of energy supply security;

• reliability assessment and modelling of processes in net systems;

• sensitivity and uncertainty analysis of modelling results;

• fundamental research of thermal physics.

 

In 2008 researchers of the Laboratory together with Lithuanian and international partners participated in implementation of 33 projects:

 

• 3 state funded scientific research works;

• 15 international projects (among them 6 projects of EU 6th Framework Programme and 7th Framework Programme, 4 international scientific research programmes financed

from own resources);

• 15 projects with Lithuanian partners. 

 

 

A three year state funded project Development of Methodologies of Security and Reliability Assessment of Energy Supply to Lithuania was completed in 2008. Main objective of the project was to create an estimation and assessment methodology of Lithuanian energy security. This methodology included assessment of various external and internal threats to energy system, analysis of their consequences and choice of solutions, which could eliminate and mitigate these threats. From probable threats there were analysed not only technical, but also economical (crisis) and geopolitical challenges of energy supply disturbances as well as terrorist acts. Threats impact was estimated from economical, social and political point of view.

UNDERSTAND project was completed in 2008. The objective of UNDERSTAND was to present a training package to system operators concerning crises management and intersystem cooperation. The aim of the project was to develop and justify a training concept, which could be expanded in further projects striving to retain undisrupted electricity supply in European electric systems. In this project, which is part of Leonardo da Vinci programme,besides LEI, 9 partners from 8 European countries participated: the leading partner – Swedish Energy Agency, SC SecLink (Sweden), Ostrav Technological University VSB (Czech Republic), ABC Dialog (Denmark), National Emergency Supply Agency (Finland), Link Consulting sas (Italy), KCEM (Sweden), Žilina University (Slovakia), University of Kranfold (UK), and Ostrav VSB (Czech Republic).

 

The objective of Seventh Framework Programme project SECURE (Security of Energy Considering its Uncertainty, Risk and Economic Implications), in which 15 partners from 11 EU countries take place, is to develop energy security assessment methodology, taking into account security of energy supply issues, estimating geopolitical changes, price formation, development of energy markets inside EU and outside, terrorist threats, etc. The project, which is under Observatoire Méditerranéen de l’Energie (France) coordination, is very important and opportune regarding EU energy security.

 

Cooperation agreement was signed with Joint Research Center Energy Institute (The Netherlands) to implement project Lithuanian Energy Security Assessment, where using experience of Dutch colleagues, security assessment model of energy supply to Lithuania will be developed and assessment of state’s energy security will be performed. 

 

 

On 20-31 October 2008 Basic Professional Training Courses in Nuclear Safety were organized in Lithuania. Lithuanian State Nuclear Power Safety Inspectorate (VATESI) and IAEA initiated the idea to organize such kind of training. The training courses were supervised by LEI, the director of which was assigned Dr. Habil. Algirdas Kaliatka from Laboratory of Nuclear Installation Safety. JSC Visagino atominė elektrinė and Ignalina Nuclear Power Plant also contributed in organizing the training courses. In these courses lectures were given by lecturers and specialists from LEI, INPP, Kaunas University of Technology, and Institute of Physics. There were 19 representatives from VATESI, JSC Visagino atominė elektrinė, LEI and 20 participants from 13 foreign countries – Armenia, Bulgaria, Czech Republic, Hungary, Kazakhstan, Latvia, Estonia, Poland, Romania, Russia, Slovakia, Slovenia, and Ukraine.

 

During training courses participants were acquainted with basic nuclear, radiation, environment safety principles, peculiarities of nuclear power plants safety and its assessment. Extra topics were included into the program (development of new nuclear power plant structure: external electricity supply network: dismantling of power plant after its final shutdown), particularly relevant and interesting for the representatives from the Baltic countries, who are prepared for constructing new nuclear power plant in Lithuania. While organizing the excursion to the Ignalina NPP, the participants had an opportunity to survey the full scope simulator of Ignalina NPP. The participants were divided into three groups and using the simulator, performed operator’s actions in case of emergency situations.

 

 

 

 

“It is important to formulate nuclear safety knowledge in accordance with IAEA safety standards for the countries, which are preparing for construction of new nuclear power plants, cooperation of Lithuanian organizations and IAEA are extremely beneficial aiming at continuous development of structures related with nuclear safety”,- stated Maria Moracho, inspector of IAEA Nuclear Installation Safety Department. According to her, it has been decided to organize these training courses in Lithuania since there are a number of specialists of this field, competent experience has been accumulated and relevant infrastructure necessary for such kind of training is available.

 

“Such kind of courses has been organized for the first time in Lithuania. Besides, these are the very first steps in establishing Basic nuclear safety training centre in Lithuania”, - stated Marius Ginevičius, director general of JSC Visagino atominė elektrinė. According to him, after establishing such training centre in the future in Lithuania, specialists from Lithuania as well as other countries could raise there their qualification.

 

In 2008 Lithuanian Energy Institute continuing activities for project IRIS (International Reactor Innovative and Secure) according to the general agreement between project participants and Westinghouse Electric Company LLC the new bilateral contracts were considered. Conceptual IRIS project is already finished and, at present, works of reactor technical systems testing and preparation of reactor project for licensing are carried out (till year 2010). In this stage researchers of LEI begin to prepare methodologies for new reactors comparisons and implement works, related to structural, economical, security and safety analysis of the reactor. Scientific research in this field is relevant for the study of new reactors construction in Lithuania. IRIS project and related research will be completed around 2010 – 2015, i.e. in the time when assessment and licensing issues for new nuclear reactor in Lithuania will be extremely important. In the recent years specialists of the Laboratory of Nuclear Installation Safety have participated in performing IRIS probabilistic safety and economical efficiency analysis and research, devoted to reduce the risk of different external hazards and the uncertainty of obtained results.

 

New generation reactor development and analysis works, related to IAEA coordinated research programs, are carried out in the Laboratory. One of such programmes is Review of Economical Benefit of Evacuation Zone and Safety Measures Around Nuclear Power Plants with Innovative Small and Medium Capacity Reactors in the Regions, where Reactors are Used for Electricity and Heat Generation. The objective of this project is the assessment of evacuation zone and safety measures of nuclear power plants as well as the analysis of perspectives of secure and efficient small and medium capacity reactors. Performing research there is an attempt to develop an economic efficiency study, where the possibilities of new nuclear power plant use for district heating are analysed. In the work it is analysed what the economic effect would be if reactor power plant were used for electricity production as well as district heating. Performed research reveal how the efficiency of new nuclear power plant increases in such case.

 

In 2008 activity was initiated in accordance with agreement with VATESI – to prepare updated version of nuclear safety regulating legal act General Regulations for Nuclear Power Plant Safety. Survey of international regulating documents (IAEA, WENRA, EUR, EPRI (URD) and worldwide experience (9 countries) was carried out. In accordance with it first version and, after VATESI comments, second version of General regulations for NPP safety were developed. Final document version is to be submitted to VATESI in 2009. This document will be one of the most important legal acts, regulating safety requirements of Visaginas NPP, planed to be constructed in Lithuania.

 

In 2008 activities were continued in accordance with LEI signed contract with Inspecta Nuclear AB (Sweden) LEI Assistance in Performing Expertise of PULS 03 and GREAT Documentation. In 1980 in Sweden, in accordance with referendum results, a decision was made concerning non-construction of new nuclear power plants and shutdown of operated nuclear power plants. It was forecasted to shutdown the operation of all Sweden nuclear power plants till 2010, however, at present time, the opinion of Sweden society and politicians has changed concerning the perspectives of nuclear power development, and thus capacity increase programme of operated power plants is carried out.

 

Researchers of the Laboratory of Nuclear Installation Safety participate in documentation expertise works of PULS O3 and GREAT projects, which are designed for the capacity increase of Oskarshamn (BWR type reactor) and Ringhals 3 (PWR type reactor), operated in Sweden. Main task of LEI researchers in implementing contract with Inspecta Nuclear AB is to perform an expertise of thermohydraulic and strength calculations, given in PULS O3 and GREAT projects. Participation in these works is an excellent possibility to get to know the specifics of different type reactors, with national Sweden and international requirements intended for projection documentation of different type reactors and safety justification. The experience of laboratory scientists will be applied for constructing new power plant in Lithuania.

Network of Excellence of Severe Accident Research of Nuclear Power Plants SARNET Contract on Network of Excellence for Severe Accident Research and Management (SARNET) was continued in 2008. 49 European R&D organizations, including LEI, participated in this project. In 2008 the Laboratory researchers participated in the activities of three working groups:

 

• ASTEC – adaptation and verification of integral code ASTEC designed for modelling of severe accidents in nuclear power plants;

• CONTAINMENT – analysis of processes occurring in protective shields of nuclear power plants;

• PSA-2 – application of level-2 probabilistic safety analysis for various nuclear power plants, risk assessment and method development of its reduction.

 

Another part of SARNET project is probabilistic safety assessment considering potential severe accident scenarios. The model for severe accident (hydrogen explosion and reactor containment damage) research was analysed and developed together with other participants of the project (close cooperation with scientists from Consejo de Seguridad Nuclear and Universite Libre de Bruxelles). Further improvement of developed software and model was carried out for intended works. Sensitivity analysis software SUSA and SIMLAB were applied for the analysis and comparison of results.

 

In 2008 SARNET project was completed. Activities, designed for the integration of nuclear power plants’ severe accident phenomena and control research in Europe, will be continued in network of excellence SARNET II.

 

 

 

In 2008 LEI together with partners continued activities of NULIFE network of excellence. One of the main tasks is to establish an integral organizational structure – virtual institute capable of performing scientific research of durability assessment in European nuclear facilities industry. NULIFE network of excellence will enable to coordinate scientific research, carried out in Europe, in the fields which require an interaction among different ageing processes, environmental impacts and loadings, taking into account safety level of different nuclear facilities. The executers of the project are gathered into a consortium, which is comprised of Contractors from ten organizations and Associated Contributors from 27 organisations, whereas the project coordinator is VTT Technical Research Centre of Finland.

 

In 2008 researchers of the Laboratory participated in the following working groups: A-1 – assessment of experience and competence of partners (analysing power issues of nuclear plant); IA-2-2 – assessment of structural integrity (final report on RBMK-1500 reactor fuel channel ageing was prepared); IA-2-4 – safety, risk and reliability (researchers presented their experience in the activities on safety, risk and reliability assessment of nuclear power plants. The project will be implemented till 2011.

 

In accordance with agreement between EC JRC IE and LEI in 2008 the research on Reliability and Data Analysis of Passive Components was initiated. Activities of the project are related with EC JRC IE coordinated APSA research network Use of Probabilistic Safety Assessment for Evaluation of Ageing Effects to the Safety of Energy Facilities. APSA research network comprises 14 organizations from different countries and is related to EU NULIFE network of excellence. Taking into account impact of equipment ageing on change of their reliability characteristics APSA research network is devoted to improvement of classical probabilistic safety analysis (PSA). In the classical PSA, applying an assumption of constant reliability parameters, sometimes inadequate safety assessment is carried out. In order to perform ageing PSA it is need to have larger amount of data and more detailed models and to carry out inspection assessment. In this research network LEI most of attention devoted to activities, related to component reliability analysis methods and time dependent reliability characteristic assessment as well as application of such methods and estimates in PSA models. The issues of development and application of reliability database and relevant software (e.g. WinBUGS) were considered too. Since 2008 LEI has been coordinating APSA research network activity – Ageing data and reliability analysis for passive components.

 

In 2008 LEI being the member of EC JRC IE coordinated ENIQ (European Network for Inspection and Qualification) continued its participation in activities of Task Group on Risk, implemented the risk-informed inspection programme development and optimisation activities in Lithuania. ENIQ research network is comprised of 20 different organizations. Activity of this network is related to EU NULIFE network of excellence and other 7FP projects.

Preparation of the Ignalina NPP 117/1 Building Equipment Decontamination and Dismantling Project (B9-0) was continued in 2008. The project is implemented by VT Nuclear Services (United Kingdom), Nukem Technologies GmbH (Germany) and LEI consortium. In the frame of this project, personnel of Nuclear Installation Safety Laboratory was involved in development of the strategy, basic design, detail design and safety justification report. LEI is responsible for supporting of Ignalina NPP during project licensing and implementation stages. The Ignalina NPP 117/1 building equipment decontamination and dismantling strategy was developed and approved by the Ignalina NPP in 2008. As well in 2008 the basic design and safety justification report was developed. The development of detail design for equipment decontamination and dismantling was started in the end of 2008.

 

In 2008 the activities were continued in accordance with Association Agreement Concerning the Cooperation in the Field of Scientific Research of Thermonuclear Fusion signed between LEI and European Commission. Cooperating with Max-Plank-Institut für Plasmaphysik (Germany), the analysis of stellarator type thermonuclear fusion experimental equipment W7-X, constructed in the institute, was carried out. The accident assuming rupture of 40 mm diameter pipe of W7-X cooling circuit leading to steam release to the vacuum vessel was simulated. Calculations were carried out using RELAP5, COCOSYS and ASTEC codes.  

 

 

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In 2008 LEI researchers visited to Max-Plank-Institut to discuss the results of analyses and discussed the future programme of activities. W7-X safety analysis activities are to be continued in 2009.

 

 

 

State funded project Research of Condensation Impact on Interface Surface Stability was completed in 2008. Numerical and experimental research results of two-phase flow in the inclined channel were presented during the project: pressure losses, channel inclination angle, and gas velocity profiles. The analysis of obtained results revealed the drawbacks of experimental facility, helped to decide on the constructions of experimental facility, further improvements of measurement equipment and methodology. In the second stage, new improved experimental facility was developed, numerical and experimental research was initiated in the condensing media. Interface surface shear stress was estimated in accordance with the results and it was determined that at two-phase flow vertically stratified horizontal flow condensation enhances tangent stress on the interface surface.

 

Two year cooperation project Numerical and Experimental Research of Nuclear Reactors in the Field of Heat Transfer was completed in 2008. The project was implemented with Ukrainian National Academy of Sciences Institute of Technical Thermal Physics. Results of condensation impact on interface surface stability and sensitivity analysis of RBMK- 1500 reactor one group distribution collector blockade postulated accident carried out using FAST method are presented in the work. Results may be used for developing thermal-hydraulic facility, designed to ensure passive (opposite to natural) circulation in two-phase thermal circuits.

 

 

In 2008 a three year state funded project Best Estimate Methodology Application Simulating Processes in Technical, Natural and Social System was continued. Researchers from the Laboratory of Hydrology and from the Laboratory of Energy Systems Research also take part in this study. The aim of the work is application of uncertainty analysis methodology in the field of social sciences and performing modelling of hydrological processes.

 

In 2008 forecast of electric power demands was revised out. Applying sensitivity and uncertainty analysis methods in social systems (for energy economy tasks), mathematical model of energy system development, applied in developing National Energy Strategy, was reviewed. The changes in energy markets were evaluated in the model. Also, the verification of improved FEMAXI-6 code was demonstrated using sensitivity and uncertainty analysis. This code (designed to model processes in fuel rods), was adjusted to RBMK-1500 reactor needs.

 

Solving natural system tasks (hydrological regime assessment of the Nemunas River), hydrological model for the Nemunas River, which may simulate Kaunas HPP inflow under various natural conditions and in accordance with forecasted climate change scenarios, was developed. Using GLUE (Generalized Likelihood Uncertainty Estimation) method, calibration parameter analysis of the Merkys River (belonging to Nemunas River basin) hydrological model was carried out. Best estimate values of six calibration parameters were determined and value intervals were defined, from which it is suggested to choose parameters to calibrate hydrological model under Lithuanian conditions.

 

 

 

 

 

 

 

In 2008 cooperation with Ignalina NPP was successfully continued. Implementing “turn-key” project Control System of Leaktightness of Fuel Cladding During Dismantling of Spent Fuel Assemblies in the “Hot Chamber”, the Control system of leaktightness of fuel cladding was developed and implemented at the Ignalina NPP. Ignalina NPP spent nuclear fuel assemblies from reactor are loaded to fuel maintenance pools, where they are stored no less than 12 months. Afterwards fuel assemblies are directed towards the hot chamber, where they are divided into two parts (two bundles of fuel elements) and are loaded to transportation trays, where only leak tight bundles of fuel elements may be loaded. Leaktightness of nuclear fuel assemblies must be controlled during the whole process in the hot chamber. Ignalina NPP initiated this project, the objective of which was to develop a Control Method of Leaktightness of Nuclear Fuel Assemblies Cladding, to justify it and implement control system of cladding leaktightness operating under this method. The project was coordinated by Lithuanian Energy Institute and implemented in LEI cooperation with JSC Specialus montažas – NTP. The control method of fuel assemblies leaktightness developed and justified during the project was applied in creating and implementing the system, which enables detection fuel assemblies with leaky fuel cladding in Ignalina NPP hot chamber both at fuel assemblies reload from the tray and during dismantling of assemblies into two bundles of fuel elements. Air samples, taken from the hot chamber, access the measuring unit NGM 204L, where activity of inert radioactive gas is measured.

 

Scheme of measuring unit NGM 204L

 

 

Fuel leaktightness control system was granted the gold medal at Lithuanian Industrialist Confederation organized competition Lithuanian Product of the Year, whereas its work efficiency was approved during operation of the system, which started at the end of 2008.

 

Cooperation project Analysis of Accident Localisation System (further ALS) of Ignalina NPP with GRS Company was completed in 2008. The scheme is designed for the analysis of results, obtained applying COCOSYS code. Beyond design basis event (Reactor cooling system pipe rupture with failure to activate emergency core cooling system) analysis was performed and impact of modelling parameters on calculation results was estimated. The following modelling parameters were chosen to perform calculations: control volume centre altitude, compressed air system activation criteria, and initial air and water temperature in Accident Localisation System. While performing the analysis, change of thermodynamic parameters (pressure, temperature, water level in condensed pools, other), hydrogen distribution and radionuclides deposition in compartments and their outflow from Accident Localisation Systems were estimated.

 

 

Distribution of deposited radioactive aerosols in compartments

 

In 2008 agreement was signed with Ignalina NPP regarding Implementation of Activities of Analysis of NPP A2 Unit 101/2 Buildings Reaction to Seismic Impact. Implementing this project, the Institute of Geology and Geography and Vilnius Gediminas Technical University participated as subcontractors. Soil and building data was collected for seismic analysis; the seismic hazard assessment was carried out taking into account analysis results of seismic events and seismictectonic conditions in Ignalina NPP region; the soil, the soil – structure interaction and the Ignalina NPP reactor building models have been prepared for seismic analysis of NPP A2 Unit 101/2 buildings.

 

In 2008 agreement was signed with Lithuanian State Science and Studies Foundation to finance science research project Modelling and Analysis of Soil and Its Interaction with Ignalina A2 Unit 101/ 2 Building, which was implemented by experts from the Institute of Geology and Geography and Vilnius Gediminas Technical University. The study discusses the seismotectonic conditions of Lithuania. The overview of the corresponding regulations and methods used in the seismic hazard assessment is provided. The experience of other countries and previous studies is discussed. In particular, the application of the probabilistic and deterministic approaches is compared and possibility of application of those methods for the geological conditions of Lithuania is analysed. The case studies of Ignalina NPP show similar estimates of the seismic hazard for both approaches that advocates consistency and applicability of those methods and urges employment of both methods in seismic risk analysis. It should be noted that obtained seismic hazard results are well compatible to seismic hazard estimates in Leningrad NPP that is located in a similar geological environment.

 

 

 

This study provides a methodological base for seismic risk analysis of Ignalina NPP and will be implemented for analysis of 101/2 building of unit A2 next year. The methodology incorporates ground shaking, building and Soil-Structure Interaction modelling of the seismic impact on the NPP. The finite element approach will be applied. The near-field earthquake peak acceleration for safety level SL-2 with exceeding of 10^-4 was evaluated as high as 168 cm/s² in Ignalina NPP. It is based on the fact of the presence of the large fault below the Ignalina NPP that is considered as a potential zone for generating an earthquake. This acceleration corresponds to intensity 7.5 (scale MSK-64).

 

 

 

Integrated decision making process

 

 

Implementing activities of Ignalina NPP Probabilistic Safety Analysis the methodology, designed for the probabilistic analysis of personnel errors, was carried out. Analysis of initiating events as well as probabilistic safety assessment (PSA) model was updated and uncertainty analysis of modelling results was carried out. Practical application of probabilistic safety assessment and decision making methodology was developed.

 

The justification of Hot Shutdown Procedure in Case of Station Blackout at Ignalina NPP was carried out. The analysis of processes, occurring in reactor cooling circuit, in case of Ignalina NPP station blackout was carried out employing system thermal hydraulic code RELAP5. The optimal operator actions, allowing to cooldown reactor reliably in such extreme conditions, were proposed, based on various calculations. It is necessary to point out, that the processes in RBMK reactors during beyond design basis accidents were not investigated in comprehensive manner. Project results enabled to improve Ignalina NPP “hot rupture” procedure in such way that operators of power plant could successfully control such beyond design basis accident as station blackout (complete energy loss for its own needs).

 

  

Other activities related with probabilistic safety assessment were carried out last year: Probabilistic Safety Analysis of External Events and Events in Shutdown Reactor; Optimisation of Testing Intervals for Safety Important Systems. Implementing these activities the research methodology was updated, probabilistic analysis models were developed and statistical data research was carried out as well as event scenario analysis and research of testing intervals.

 

Activities of projects Justification of Changes, Included into Ignalina NPP Symptomatically Oriented Accident Instruction and Justification of Changes, Included into Ignalina NPP Accident Classification Instruction were carried out in 2008. Deterministic analysis of beyond design basis accidents, which do not leads to reactor core violations, was carried out using RELAP5 and COCOSYS codes. Processes, occurring during accidents in reactor core, reactor cooling circuit and in compartments which surround the circuit, are simulated. Knowing the specific emergency situation outcomes, these accidents are attributed to a certain class of accidents. It is determined what kind of personnel reaction is needed aiming at controlling a specific energy situation or mitigating its consequences.

 

Ignalina NPP project Replacement of Flowmeters Due to the Diagnostic Results in Unit 2 in 2008 was completed. In each technological channel of RBMK- 1500 reactor coolant flowmeters are installed. When the flowmeter fails, the operation of appropriate technological channel is interrupted until the next shutdown of the reactor, when the broken flowmeter is replaced with a new one. Flowmeter diagnostics is being carried out before annual maintenance in order to avoid failures. In 2008 in the continued work analysis of diagnostic measures results was carried out and it was determined that 470 flowmeters had to be replaced in Ignalina NPP Unit 2 in order to guarantee a reliable operation of Unit 2 until the next planned maintenance. During the analysis the most degraded flow meters were selected. In case of changing them the reliability of all flow measuring system was improving.

The Residual Graphite-fuel Channel Gas Gap Probabilistic Analysis and Forecast at Ignalina NPP Unit 2 was carried out in 2008. The methodology, developed in previous works, was applied in the project to forecast the gas gap of Ignalina NPP Unit 2 and assess the probability of residual gap. Statistical analysis of measurements of fuel channels of Unit 2 was carried out using measuring data till year 2008, the probability of gas gap disappearance was evaluated and forecast of its change was carried out till year 2010. Calculations revealed that the forecasted probability of disappearance of the gas gap in Unit 2 till year 2010 comply with the requirements of VATESI.

 

Implementing project Application of Ignalina NPP Probabilistic Safety Analysis Model in VATESI Activity the probabilistic safety assessment (PSA) and analysis model was verified and relevant documents feasibility assessment was performed. Software RiskSpectrum RiskWatcher was chosen in order to apply Ignalina NPP PSA model for the analysis of unexpected events.

 

 

 

This software helps to work with PSA model and makes possible to adapt it for the development of system for unexpected events analysis. RiskWatcher typically is used as risk monitor for observation of risk dynamic, simulation of possible events scenarios and planning of outages depending on risk estimates. The essence of this software is level 1 PSA model, comprised of set of failure trees and event trees, which define scenarios of investigated events and their consequences. Taking into account the structure and data used in Ignalina NPP PSA model as well as VATESI information, the research on feasibility of data, which is necessary for PSA model adaptation, was carried out.

The Safety Assessment Expertise of Ignalina NPP Austenitic Du-300 Pipelines Welded Joints with Cracks Left for Further Operation, Volume of in Service Inspection and Period of Inspections was done in 2008. The expertise of Ignalina NPP document “Preparation of Reports for Safety Justification of Main Circulation Circuit Du-300 Pipelines of Unit 2, According “Requirements for Assessment of Intergranular Stress Corrosion Cracking Damages in RBMK-1500 Reactors’, P-2004-01”” was done. Comments and independent verification calculations of intergranular stress corrosion cracking acceptable and critical crack sizes and crack growth in 1.5 year of operation were presented in this expertise. The results of independent calculations where compared with results presented in report. According to analysis results it was recommended to VATESI to adjust the reviewed document according to Ignalina NPP answers to expertise comments.

 

Implementing agreement Review of INPP Documents, Submitted to VATESI, Related with Changes of Reactor Core Configuration, Physical Characteristics and Control, and Other Issues of Reactor Physics and Nuclear Fuel Storage and Management, Ignalina NPP documents were analysed in order to justify the updated method for operative reactivity margin estimation, the new determined limits for reactor passport characteristics, and safety of regular loading of 2.8% uranium-erbium fuel together with spent fuel rods, transferred from Ignalina NPP Unit 1 to Unit 2. Independent calculations were carried out, on the basis of which conclusion were drawn on the reliability and expedience of presented safety justifications.

 

 

 

Gold medal of Lithuanian Industrialists Confederation competition Lithuanian Product of Year 2008 awarded for development and implementation of project Control System of Leaktightness of Fuel Cladding During Dismantling of Spent Fuel Assemblies in the “Hot Chamber” 

 

According to agreement Review of Documents of Ignalina NPP SIP-3/2007 41 Implementation, the Ignalina NPP documents, submitted to VATESI aiming at justifying methodology and equipment, designed to measure hydrogen concentration in top steam reception chamber of Ignalina NPP Accident Localisation System, were analysed. After estimating acceptability of chosen hydrogen concentration measuring methodology, calculations of measuring error of hydrogen concentration were carried out.

 

In 2008 two Doctoral theses were defended Analysis of Hydrogen Distribution in Containments of Nuclear Power Plants (E. Babilas), Probabilistic Ageing Assessment and Management of Energy Installations (V. Matuzas).

 

Research results were presented in science research reports and 63 scientific articles (among them, 15 publications, included in the list of Institute of Scientific information), 49 papers were presented at scientific conferences. Researchers of the Laboratory participated in the events related to thermonuclear field and presented papers in all main international conferences, where safe operation of nuclear power plants and physical phenomena occurring in them were analysed. Researchers actively participated in different international and national training courses, IAEA seminars, coordinating meetings, activity of FUSION committees and other organizations.