Nuclear Power Plant In Lithuania Research Articles

Gamma Radiation Shielding Assessment Using Stochastic, Deterministic, and Experimental Methods for RBMK-1500 SNF Storage Cask

This paper presents an evaluation of the gamma-radiation shielding capabilities of the CONSTOR® RBMK-1500/M2 cask dedicated for the storage of spent nuclear fuel at the Ignalina Nuclear Power Plant in Lithuania. This cask is of a new design with increased capacity compared to the older CONSTOR RBMK-1500 and CASTOR RBMK-1500 casks and new facility for their interim storage has been installed. “Hot tests” conducted at this new interim storage facility included dose rate measurements of the CONSTOR RBMK-1500/M2 casks that were loaded with particular sets of spent nuclear fuel half-assemblies and transferred to the facility for subsequent interim storage. Having actual data on the spent nuclear fuel half-assemblies that were loaded into a particular cask, gamma dose rate modeling of that CONSTOR RBMK-1500/M2 cask (namely, cask ID 153) was performed. Modeling was performed using the MCNP (based on the stochastic mathematical method) and the VISIPLAN and MicroShield (both based on the deterministic mathematical method) computer codes. The obtained modeling results were compared between the different codes and with the measurement results. The performed analysis revealed that modeled gamma dose rates are in good agreement for all analyzed codes, although agreement with the measurements is to some extent less.

Neutron dose rate analysis of the new CONSTOR® storage cask for the RBMK-1500 spent nuclear fuel

This paper presents the neutron dose rate analysis of the new CONSTOR® RBMK-1500/M2 storage cask intended for the spent nuclear fuel storage at Ignalina Nuclear Power Plant in Lithuania. These casks are designed to be stored in a new “closed” type interim storage facility, with the capacity to store up to 202 CONSTOR® RBMK-1500/M2 casks. In 2016 y, the “hot trials” of this new facility were conducted and 10 CONSTOR® RBMK-1500/M2 casks loaded with the spent nuclear fuel were transported to the dedicated storage places in this facility. During “hot trials”, the dose rate measurements of the CONSTOR® RBMK-1500/M2 casks were performed as the dose rate is one of the critical parameter to control and it must be below design (and safety) criteria. Therefore, having the actual data of the spent nuclear fuel characteristics, the neutron dose rate modeling of the CONSTOR® RBMK-1500/M2 cask loaded with this particular fuel was also performed. Neutron dose rate modeling was performed using MCNP 5 computer code with very detailed geometrical representation of the cask and the fuel. The obtained modeling results were compared with the measurement results and it was revealed, that modeling results are generally in good agreement with the measurements.

Distribution of radiocarbon in sediments of the cooling pond of RBMK type Ignalina Nuclear Power Plant in Lithuania.

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for”Channelized Large Power Reactor”). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947–2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947–1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4–13.6 pMC during the first 15 years of plant operation. However, during the 2000–2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000–2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.

Uncertainty and Sensitivity Analysis at Low Value of Determination Coefficient of Regression Analysis: Case of I-129 Release from RBMK-1500 SNF under Disposal Conditions

As in other nuclear countries, the operation of the Ignalina nuclear power plant in Lithuania has led to the accumulation of around 22 thousand assemblies of spent nuclear fuel (SNF). The development of geological disposal program involves an iterative assessment of the system safety supported by scientific research on radionuclides migration and related processes. This study focused on the application of Contribution to the Sample Mean (CSM) and Contribution to Sample Variance (CSV) methods to complement the uncertainty and sensitivity analyses of the time-dependent flux of I-129 from the engineered barriers of a conceptual disposal facility for RBMK-1500 SNF (RBMK is abbreviation of “High Power Channel-type Reactor” (in Russian)). The analysis was performed using a MATLAB platform (8.0.0.783 (R2012b), MathWorks, MA, USA). The mean and variance ratios derived from CSM and CSV plots were applied to estimate the effect of reduced uncertainty range on mean flux and its variance, and the uncertainty analysis was also complimented. Increasing the lower bounding value of defect size enlargement time range to 4.6 × 104 years would lead to a lower mean flux until 5 × 104 years after repository closure. Later on (up to 1 million years after repository closure), the only reduction of the upper bounding value of the SNF dissolution rate range would affect a decreased mean flux.

Variability of hydrogeological parameters in the environment of new nuclear power plant in Lithuania

The groundwater flow and radionuclide (3H, 14C and 137Cs) transport model was performed for the model domain of the experiment site near Ignalina nuclear power plant (INPP) in Lithuania assuming that the radionuclides will reach groundwater straight after the new NPP operation begins. The task of the study is to predict the transportation of radionuclide from the hypothetical reactor of the new NPP and perform a sensitivity analysis in order to predict the effects of radiation on the environment. The main focus of attention was the evaluation of ranges of the parameters, such as effective porosity, hydraulic conductivity and dispersivity, mostly influencing the assessment results.The obtained results show that the activity concentration of the modelled radionuclides strongly depends on the hydrogeological properties of the aquifer. The largest variability of activity concentration is established for the radiocarbon determined by the dispersivity and hydraulic conductivity.

Modeling of irradiated graphite 14C transfer through engineered barriers of a generic geological repository in crystalline rocks

There are two RBMK-1500 type graphite moderated reactors at the Ignalina nuclear power plant in Lithuania, and they are under decommissioning now. The graphite cannot be disposed of in a near surface repository, because of large amounts of 14C. Therefore, disposal of the graphite in a geological repository is a reasonable solution. This study presents evaluation of the 14C transfer by the groundwater pathway into the geosphere from the irradiated graphite in a generic geological repository in crystalline rocks and demonstration of the role of the different components of the engineered barrier system by performing local sensitivity analysis. The speciation of the released 14C into organic and inorganic compounds as well as the most recent information on 14C source term was taken into account. Two alternatives were considered in the analysis: disposal of graphite in containers with encapsulant and without it. It was evaluated that the maximal fractional flux of inorganic 14C into the geosphere can vary from 10−11y−1 (for non-encapsulated graphite) to 10−12y−1 (for encapsulated graphite) while of organic 14C it was about 10−3y−1 of its inventory. Such difference demonstrates that investigations on the 14C inventory and chemical form in which it is released are especially important. The parameter with the highest influence on the maximal flux into the geosphere for inorganic 14C transfer was the sorption coefficient in the backfill and for organic 14C transfer – the backfill hydraulic conductivity.

Modelling of RBMK-1500 SNF storage casks activation during very long term storage

Existing interim spent nuclear fuel storage facility (SNFSF) at Ignalina nuclear power plant in Lithuania is fully loaded with CASTOR®RBMK-1500 and CONSTOR®RBMK-1500 storage casks. The planned lifetime of these casks is 50 years and the first loaded cask was moved to the SNFSF in 1999. The start of operation of disposal facility in Lithuania is foreseen later than the planned interim storage ends. So, the possibilities to extend the storage period over 50 years should be considered. Therefore, the casks decommissioning issues should be taken into account, as due to prolonged neutron irradiation casks materials could became activated.This paper presents modelling results of storage casks neutron activation during 300 year storage period. Modelling results show, that after 50 years of storage, side-wall and bottom of CASTOR®RBMK-1500 cask are activated above clearance criteria. However, for 100–300 year storage period all of the casks components could be free released.

The environmental impact assessment process for nuclear facilities: A review of the Lithuanian practice and experience

The only one nuclear power plant (NPP) in the Republic of Lithuania – Ignalina NPP has been shutdown and entered the phase of decommissioning. Decommissioning activities, along with dismantling works, include construction and operation of a new spent nuclear fuel and radioactive waste management, storage and disposal facilities. The new NPP in Lithuania, if such would be constructed, are to be located adjacently to the existing plant. Current and future planned nuclear activities in Lithuania are concentrated in a single location, in the northeast of the country near the state borders with the Republic of Latvia and the Republic of Belarus. Number of different projects and participants involved, necessity to control and limit overall impact on the environment require for planning and coordination of activities and impacts, including consideration and updating of outcomes from the previous environmental impact assessment (EIA) studies. Regulatory review and coordination of EIA documents also demands substantial time resources, impacts schedule of activities and therefore must be properly planned and managed. The paper describes approach and progress in EIA for nuclear activities in Lithuania and examines experience gained in preparation, review and coordination of EIA studies. Emphasis is placed on approach that has been used to deal with cumulative radiological impact because acceptability of this impact is one of primary goal in demonstration of acceptability of the newly planned nuclear activities.

Radiocarbon and Other Environmental Isotopes in the Groundwater of the Sites for a Planned New Nuclear Power Plant in Lithuania

The assessment of construction sites for the new Visaginas Nuclear Power Plant (Visaginas NPP), including groundwater characterization, took place over the last few years. For a better understanding of the groundwater system, studies on radiocarbon; tritium; stable isotopes of hydrogen, oxygen, and carbon; and helium content were carried out at the location of the new NPP, at the Western and Eastern sites, as well as in the near-surface repository (NSR) site. Two critical depth zones in the Quaternary aquifer system were characterized by different groundwater residence times and having slightly different stable isotope features and helium content. The first shallow interval of the Quaternary multi-aquifer system consists of an unconfined aquifer and semiconfined aquifer. The second depth interval of the system is related to the lower Quaternary confined aquifer. Groundwater residence time in the first flow system was mainly based on tritium data and ranges from 6 to 60 yr. These aquifers are the most important in terms of safety assessment and are considered as a potential radionuclide transfer pathway in safety assessment. Groundwater residence time in the lower Quaternary aquifers based on 14C data varies from modern to several thousand years and in some intervals up to 10,500 yr.

Prospects for the Development of Nuclear Energy in the Baltic Region

The article aims to evaluate the prospects of construction of a nuclear power plant in Lithuania and the possible benefits, as well as to analyse the decisive factors of development of nuclear energy in Europe and worldwide. Attention is paid to the increasingly stringent regulation of the development of nuclear energy, which may play a role in the growing competition among the nuclear power plants built in Lithuania, Russia and Belarus. The article ends with the conclusion that despite the high costs of construction of nuclear power plants, pending problems of disposal of spent nuclear fuel, rapid development of renewable resources and other factors, nuclear energy will retain its role in the energy balances of the countries in the region. The article also gives a positive assessment of the possibilities of construction of a nuclear power plant in Lithuania.

Integrated probabilistic analysis of nuclear power plant building damage due to an aircraft crash

In order to ensure that nuclear power plant buildings are reliable and safe in case of external loading, it is very important to evaluate uncertainties associated with loads, material properties, geometrical parameters, boundaries and other parameters. Therefore, a probability-based analysis was developed as the integration of deterministic and probabilistic methods using existing state-of-the-art software. The subject of this paper is the integrated analysis of building failure due to impact by a commercial aircraft. The Monte Carlo Simulation, First-Order Reliability and the combined Monte Carlo Simulation and Response Surface methods were used for the probabilistic analyses. During an aircraft crash, the dynamic impact loading is uncertain. Therefore a relation expressed by the probability of failure of impacted wall and loading function was determined. With failure defined as concrete cracking and rebar rupture, the failure probabilities of the impacted wall were calculated as a function of the peak impact load. The integrated deterministic and probabilistic analysis approach was applied to the Ignalina Nuclear Power Plant in Lithuania. The conclusions from this analysis was that a through-the-wall crack in the concrete element of a plant wall may occur with a probability of 0.0266, but the failure probability of the reinforcement bars is very small, that is, near zero. Thus, no perforation of the impacted wall by structures of the aircraft should occur. The importance of performing a probabilistic analysis of crash events is shown by comparing results to those obtained by a mean value deterministic approach.

Analysis of the processes in spent fuel pools of Ignalina NPP in case of loss of heat removal

Ignalina NPP is the only nuclear power plant in Lithuania consisting of two units, commissioned in 1983 and 1987. Unit 1 of Ignalina NPP was shutdown for decommissioning at the end of 2004 and Unit 2 is to be operated until the end of 2009. Both units are equipped with channel-type graphite-moderated boiling water reactors RBMK-1500. According to the design, the spent fuel should be returned for reprocessing to Russia. However actually any fuel assembly has not been taken out from territory of the Ignalina NPP and all assemblies of spent fuel are stored in the spent fuel pools and dry on-site storage facility. Thus, the safety justification of facilities for intermediate spent fuel assemblies’ storage in Ignalina NPP is very important. This paper presents the results of loss of heat removal accidents (the most probable beyond design basis accident) in spent fuel pools of Ignalina NPP. The analysis was performed by employing best-estimate system thermal hydraulic code RELAP5 and codes for severe accidents ATHLET-CD and ASTEC. The best-estimate analysis, performed using RELAP5, allowed to investigate in the details the water evaporation, uncovering and fuel assemblies heat-up processes, when heat removal from the structures of buildings and pools are evaluated. The processes of spent fuel assemblies’ degradation due to loss of long-term heat removal were analyzed using ATHLET-CD and ASTEC codes. The results of calculations showed that the increase in water temperature in the pools from 50 °C up to 100 °C takes approximately 80–110 h, the evaporation of water volume down to uncovering of fuel assemblies takes approximately 220–260 additional hours. Later, after 200–300 h, the temperature of fuel claddings exceeds 800–1000 °C and the failures of fuel claddings occur due to cladding ballooning. The total amount of hydrogen generated up to time of complete water evaporation from spent fuel pools is about 7500–16,000 kg. These results of performed analysis were used for development of accident management guidelines for spent fuel pools of RBMK-1500.

State of the Art of the Ignalina RBMK-1500 Safety

Ignalina NPP is the only nuclear power plant in Lithuania consisting of two units, commissioned in 1983 and 1987. Unit 1 of Ignalina NPP was shut down for decommissioning at the end of 2004 and Unit 2 is to be operated until the end of 2009. Both units are equipped with channel-type graphite-moderated boiling water reactors RBMK-1500. The paper summarizing the results of deterministic and probabilistic analyses is developed within 1991–2007 by specialists from Lithuanian Energy Institute. The main operational safety aspects, including analyses performed according the Ignalina Safety Improvement Programs, development and installation of the Second Shutdown System and Guidelines on Severe Accidents Management are discussed. Also the phenomena related to the closure of the gap between fuel channel and graphite bricks, multiple fuel channel tube rupture, and containment issues as well as implication of the external events to the Ignalina NPP safety are discussed separately.

Neutron Activation in the Metal Structures of an RBMK-1500 Reactor

One of the two RBMK-1500 reactor units of the Ignalina nuclear power plant in Lithuania was shut down at the end of 2004 and is currently under decommissioning. The knowledge of radioactive inventory of irradiated materials is very important in the planning of the decommissioning activities and is essential for predicting the radiological impact to personnel during dismantling and management of these materials. The generated radionuclides and their radioactivities in the shield and support plates of the Ignalina Unit 1 RBMK-1500 reactor were modeled in this paper. The reactor shield and support plates, which are made of steel, become radioactive because of intensive neutron irradiation, as they are located close to the bottom and the top of the reactor active core.The assessment of radioactivity levels in shield and support plates was performed using the computer code ORIGEN-S. The list of radionuclides, their radioactivity levels, and the radioactivity dependence on the initial impurity content and cooling time were assessed in this paper. It was found that 3H, 14C, 36Cl, 55Fe, 60Co, 59Ni, and 63Ni are the main contributors to the radioactivity of the shield and support plates.

The Turndown of Soviet Modernity: from Chernobyl and Ignalina to the Green Movement and Sąjūdis

The modern governments are conceived as to draw their legitimacy based on universal rational knowledge and the concept of controllable and calculable risks as a tool for ensuring progress and welfare of society. The multiple risks and uncertainties of modernisation that the governments were incapable to deal with caused a deficit of legitimacy and institutional ambiguity (or the institutional void as Hajer suggested calling it). Consequently, new actors and new political arenas or spaces have emerged and are expected to lead to institutional innovation. The Soviet system represents the version of the modern state which based its legitimacy on the principle of rationalism applicable towards external nature and was challenged by multiple risks and side effects of its industrial development that led to the deficit or even absence of legitimacy. The crisis of legitimacy of the Soviet state and institutional void, this paper argues, was a key premise for the former Soviet republics such as Lithuania to restore its’ statehood and indepe­ndence in search of new democratic participatory modes of governance. The theoretical perspective based on governance transformations induced by the crisis of legitimacy, uncertainties of modernisation and institutional void in the former Soviet system of governance is illuminated by two empirical cases rooted in the nuclear energy sector, namely the accident at Chernobyl Nuclear Power Plant in Ukraine in 1986, and public controversy around the Ignalina Nuclear Power Plant in Lithuania.

Institutional Domains, Fields of Tensions and Institutional Innovation: a Sociological Approach

This article explores the structural roots of institutional fields of tensions. It singles out four societal domains – bureaucratic, economic, academic, and civic – and elaborates on different doctrines, steering mechanisms and ethos prevailing in such domains. It draws on Max Weber’s concepts of “ideal types’ of politically and economically-oriented action as a theoretical predecessor of the concept of domains and institutional tensions. It also draws on Giddens’ interpretation of social structuring processes, and develops a notion of institutional learning by proposing a concept of inter-institutional learning. The recent case of developing a new nuclear power plant in Lithuania is deployed in this article inter alia as an illustration of the tensions arising between different institutional domains, as an illustration of dominance of certain principles, steering
 mechanisms and ethos pertaining to particular institutional domains, e.g. bureaucratic and economic, whereas other domains such as civic are neglected or marginalized. It is also conceived as an example illuminating the opening of possible ways in the search for institutional innovations.

Updating of risk-informed ISI programme for Ignalina RBMK-1500 nuclear power plant in Lithuania: Results and challenges

The paper presents a risk-informed in-service inspection (RI-ISI) pilot study project of 300 mm piping at Ignalina nuclear power plant (INPP) RBMK-1500 reactor, located in Lithuania. The RI-ISI study investigates optimal 300 mm piping ISI strategies with respect to risk and required resources. In total 1240 stainless steel welds were analyzed, assuming inter-granual stress corrosion cracking (IGSCC) to be the main damage mechanism. Pipe break frequency was estimated by probabilistic fracture mechanics methods and combined with safety barriers, provided by probabilistic safety assessment (PSA) study. After 3 years of operation, updating of RI-ISI was performed by taking into account new statistical data on pipe defects. Comparison with previous RI-ISI program was performed. The paper includes discussion on uncertainties in the study and robustness of RI-ISI programs.

Modelling of the shielding capabilities of the existing solid radioactive waste storages at ignalina NPP

There is only one nuclear power plant in Lithuania--Ignalina NPP (INPP). The INPP operates two similar units with design electrical power of 1500 MW. The units were commissioned in 1983 and 1987 respectively. From the beginning of the INPP operation all generated solid radioactive waste was collected and stored at the Soviet type solid radwaste facility located at INPP site. The INPP solid radwaste storage facility consists of four buildings, namely building No. 155, No. 155/1, No. 157 and No. 157/1. The buildings of the INPP solid radwaste storage facility are reinforced concrete structures above ground. State Nuclear Safety Inspectorate (VATESI) has specified that particular safety analysis must be performed for existing radioactive waste storage facilities of the INPP. As part of the safety analysis, shielding capabilities of the walls and roofs of these buildings were analysed. This paper presents radiation shielding analysis of the buildings No. 157 and No. 157/1 that are still in operation. The buildings No. 155 and No. 155/1 are already filled up with the waste and no additional waste loading is expected.

IRS-1C LISS III land cover maps at different spatial resolutions used in real-time accidental air pollution deposition modelling

Remote-sensing scenes can provide information highly useful for real-time modelling of the atmospheric deposition in the case of an accidental nuclear release. Accurate prediction of spatial patterns in the deposition is vital to establish countermeasures to avoid unnecessary exposure of the public. This is demonstrated by a hypothesised case for a nuclear power plant in Lithuania. From classification analysis a number of land cover classes are mapped in an IRS-1C LISS III scene. The roughness of each land cover class is assigned and used as input to a real-time dispersion model. Calculation results with input of a high-resolution roughness map provide the most realistic deposition pattern. A scale analysis of degrading the land cover map into lower resolutions is performed. The atmospheric deposition model results based on lower resolution roughness maps are compared and evaluated by the so-called Dose Isopleth Correlation Area (DICA) method. The recommendation is that a 1-km resolution is adequate for real-time deposition modelling. Furthermore, the land cover mapping should be performed with care. Temporal variations in roughness at a seasonal time scale should be considered.

Public Risk Perceptions in a 'Double-Risk' Society: The Case of the Ignalina Nuclear Power Plant in Lithuania

This article explores how public risk perceptions and attitudes to nuclear power in Lithuania are shaped by a complex blend of what Beck (1992) [ Risk Society. Towards a New Modernity, London, Sage ] in risk-society theory calls the social distribution of 'goods' and 'bads'. It argues that the Lithuanian society and several other transitional and developing societies are facing a 'double-risk': first, the complex uncertainty related to the transition to the market economy and democratic governance; second, the increasing social anxiety about high-consequence risks, such as those associated with nuclear power, and the inability of modern institutions to cope with such risks. Empirical evidence is provided by case-study material of the Ignalina nuclear power plant and public opinion survey results.