Ignalina NPP Research Articles

RADIOLOGICAL INVESTIGATION OF ROACH AND PERCH FROM SOME LAKES IN LITHUANIA

From the point of view of biological toxicity the most toxic radionuclides are man‐made 90Sr and 137Cs because the behavoir of both of them is similar to stable calcium and potassium in the body. Fish is the last part of the hydrosystem chain which accumulates pollutants. The aim of this study was to analyse the distribution of these two radionuclides in the muscle and other organs of perch and roach that differ by age and living conditions. Measurements were performed for 137Cs and 90Sr activity concentrations in fishes from the lakes of Drūkšiai, Lūkstas and Dusia. Radioecological investigation was carried out for different age groups of roach and perch analysing samples of muscle and spine bones (including the head of fish). Radioecological investigation of fishes from the lakes of Drūkšiai, Lūkstas and Dusia show that the activity concentrations of 137Cs and 90Sr are low. Anyway, the accumulated radioactivity by food chain reaches the human body. Nowadays a lot of investigations are related to the lakes in the vicinity of Ignalina NPP. The investigation shows that the activity concentrations of 137Cs and 90Sr in fishes from the Drūkšiai lake are the same as in fishes from other lakes in other locations of Lithuania.

Radionuclides in deposition in the Ignalina NPP region in 2005

Abstract Results of radionuclide activity concentration measurements in deposition and ground-level air conducted at the station of the Institute of Physics situated 3.5 km from the Ignalina Nuclear Power Plant (Ignalina NPP) in 2005 are analyzed. Atmospheric depositional fluxes of 7Be, 60Co and 137Cs are estimated. Radionuclide particle deposition rates are calculated. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model of the global dispersion and deposition is used to explain variations in the 137Cs activity concentration in the ground-level air in the Ignalina NPP region in 2005. An increase in the 137Cs activity concentration of up to 17.4 µBq m−3 on 30 October-5 November is studied. Modelling results show that the Chernobyl NPP Unit 4 Sarcophagus and the radiocaesium resuspension from the Chernobyl NPP accident polluted regions are sources of 137Cs to the environment of the Ignalina NPP. Results on solubility in water of aerosols — carriers of 137Cs — are discussed.

Modelling of coupled groundwater flow and radionuclide transport in crystalline basement using FEFLOW 5.0

Abstract The strategy of radioactive waste management of Lithuania provides for evaluating the possibilities of disposal of spent nuclear fuel and long‐lived radioactive waste originated from Ignalina NPP in deep geological formations. The initial studies performed in Lithuania during 2001–2004 focused on screening of all potentially prospective geological formations as host formations. Since most information is available on crystalline basement, this formation was selected for the model case studies. Taking into account the assumptions (canister defect scenario proposed by Swedish experts and evaluated by LEI experts), groundwater flow and radionuclide (iodine‐129 as mobile and long‐lived one) transport modelling using computer code FEFLOW was performed according to geosphere conditions and parameters characteristic of the southern part of Lithuania (0,8×0,6×0,52 km far‐field block). The upward groundwater flow through defected canister located in tectonically damaged zone was simulated. The main results...

MODELLING OF COUPLED GROUNDWATER FLOW AND RADIONUCLIDE TRANSPORT IN CRYSTALLINE BASEMENT USING FEFLOW 5.0

The strategy of radioactive waste management of Lithuania provides for evaluating the possibilities of disposal of spent nuclear fuel and long‐lived radioactive waste originated from Ignalina NPP in deep geological formations. The initial studies performed in Lithuania during 2001–2004 focused on screening of all potentially prospective geological formations as host formations. Since most information is available on crystalline basement, this formation was selected for the model case studies. Taking into account the assumptions (canister defect scenario proposed by Swedish experts and evaluated by LEI experts), groundwater flow and radionuclide (iodine‐129 as mobile and long‐lived one) transport modelling using computer code FEFLOW was performed according to geosphere conditions and parameters characteristic of the southern part of Lithuania (0,8×0,6×0,52 km far‐field block). The upward groundwater flow through defected canister located in tectonically damaged zone was simulated. The main results of calculations are the following: in the case of upward groundwater flow, the maximum I‐129 volumetric activity in single tectonic fracture above defected canister will not exceed 1 Bq/1, and in the active water exchange zone, it is close to 10−2 Bq/l. These figures show that doses obtained by human recipient via aquatic pathway should be below the dose constraint (0,2 mSv/y). More complicated scenarios and assumptions should be investigated in future studies.

Uncertainty and sensitivity analysis of the CPS-CC voiding in the RBMK reactor Ignalina-2

Abstract The best-estimate accident analysis approach is widely used for studying safety issues. The introduction of nominal values implies the evaluation of solution uncertainty, therefore an uncertainty analysis is required. New results of an uncertainty and sensitivity analysis of the Control and Protection System Cooling Circuit (CPS-CC) voiding accident in an RBMK-1500 reactor core are presented here. A typical reactor core state of Ignalina NPP Unit2 before the implementation of the independent diverse shut-down system was chosen for the study. The analyzed reactivity initiated accident is one of the most severe ones in RBMK-1500 reactors causing a positive reactivity insertion of about 2 in the case of a full CPS-CC voiding. The simulation of the CPS-CC dynamic voiding process was conducted without taking into account an additional failure of the reactor equipment. The analysis was performed by employing the GRS uncertainty and sensitivity method based on the SUSA software package in combination with the 3D core model QUABOX/CUBBOX-HYCA, adjusted for reactors of RBMK type. The results of the analysis give indications for which parameters the uncertainty of knowledge should be reduced in order to reduce the uncertainty of results most effectively.

Radionuclides in the ground-level air and deposition in the Ignalina NPP region during 2002 - 2005

Radionuclides in the ground-level air and deposition in the Ignalina NPP region during 2002 - 2005

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.

Modelling of activation processes for GR-280 graphite at ignalina NPP

Ignalina Nuclear Power Plant (INPP) operates two RBMK-1500 water-cooled graphite-moderated channel-type power reactors. The total mass of graphite in the cores of both units at INPP is about 3600 tons. Modelling of activation processes in the reactor's structural materials is necessary for decommissioning planning, because large amounts of activated structural materials (graphite, stainless steel, concrete, etc.) should be managed as radioactive waste. Knowledge of radiological characteristics and a radioactive inventory of irradiated materials are essential in planning of the decommissioning processes. The purpose of this work was to perform conservative neutron activation analysis for decommissioning purposes of INPP. ORIGEN computer code was used for the calculations. Activity levels were calculated for different nuclides present in the graphite and estimates were made how these activity levels depend on irradiation time, neutron flux value and other parameters. Obtained results were compared with the data available from other investigations for GR-280 graphite.

Sustainable energy in Baltic States

Integration of New Member States to the European Union has created a new situation in the frame of implementation of the Lisbon strategy and EU Sustainable Development. The closure of Ignalina NPP is the biggest challenge to the energy sector development of the Baltic States. The Baltic States have quite limited own energy resources and in the Accession agreement with the EU Lithuania, Latvia and Estonia have verified their targets to increase the share of electricity produced from renewable energy sources (RES-E) by the year 2010. A wider use of renewable energy and increase of energy efficiency can make a valuable contribution to meeting the targets of sustainable development. The article presents a detailed overview of the present policies and measures implemented in the Baltic States, aiming to support the use of RES and the increase of energy efficiency. The review of possibilities to use the EU Structural Funds (SF) for the implementation of sustainable energy projects in the Baltic States was performed.The use of regional social–economic–environmental indicators is the main key to integrate sustainable energy development at the program deployment level. The indicators to be used should describe the contribution of energy programs to the sustainable development, medium- and long-term trends and inter-relationship between them and the typical energy indicators (saved toe, improved energy efficiency, percentage of RES). Municipalities may play a considerable role by promoting sustainable energy since local authorities are fulfilling their functions in the energy sector via a number of roles. The Netherlands’ example shows that municipalities may act as facilitators by implementing national environmental policy and increasing energy efficiency in an integral part of these activities. The guidelines for Lithuanian local sustainable energy development using the SF co-financing have been presented.

Best estimate analysis of group distribution header blockage events in RBMK-1500 reactors

Abstract The analysis of Group Distribution Header (GDH) blockage events shows that the integrity of several fuel channels could be violated. A best estimate analysis of GDH blockage events in the RBMK-1500 reactor (Large Channel Type Water-cooled Graphite-moderated Reactor) of the Ignalina Nuclear Power Plant is performed. Uncertainties of the initial and boundary conditions as well as ATHLET code models were taken into account during the simulation. The analysis is performed employing the code ATHLET Mod. 1.2 Cycle D and the package SUSA 3.5. In this paper the ATHLET code model of Ignalina NPP, event scenarios and results of the analysis are presented. Analysis results show that GDH blockage events do not lead to severe consequences.

Strength evaluation of a steam distribution device in the Ignalina NPP accident localisation system

The Ignalina NPP has a pressure suppression type of confinement, which is referred to as the accident localization system (ALS). The ALS prevents the release of the radioactive material from the NPP to the environment during a loss-of-coolant accident (LOCA). Ten water pools are located in the two ALS towers (five pools in each tower), which separate the dry well from the wet well. These water pools condense the accident-generated steam and prevent high overpressures in the compartments. The steam distribution device (SDD), with the vertical vent pipes (nozzles) that are inserted under the water of the condensing pools, connects the dry well and the wet well. In case of an accident, these components must be capable of withstanding the dynamic loads generated by a LOCA for successful pressure suppression function. This paper presents the transient analysis of the SDD and their connections to the vertical steam corridors following a LOCA. A thermo-hydraulic analysis of the SDD was performed using the state-of-the-art COCOSYS code to determine pressure and temperature histories resulting from a LOCA. The finite element code NEPTUNE was used to evaluate the structural integrity of the SDD and its supporting reinforced concrete wall. Results show that, although portions of the SDD undergo plastic response and the outside surface of the vertical steam corridor reinforced concrete wall cracks, the structural integrity of the SDD and wall are maintained during a LOCA.

05/02058 COCOSYS code validation against measured data during unintended single main safety valve opening at Ignalina NPP

05/02058 COCOSYS code validation against measured data during unintended single main safety valve opening at Ignalina NPP

Development of accident management measures for RBMK-1500 in the case of loss of long-term core cooling

Results of the Level 1 Probabilistic Safety Assessment of the Ignalina Nuclear Power Plant have shown that in the risk topography transients are dominating. Analysis has shown that failure of the long-term core cooling is the main contributor to the core damage frequency. However, the reactor core damage in the long-term indicates the potential opportunities for the accident management. The main goal of accident management is to avoid a multiple fuel channel rupture because considering the design of RBMK reactors the consequences of rupture of more than 11–16 FC at full pressure would be close to the consequences of Chernobyl accident. This paper presents a detailed thermal–hydraulic analysis of the accidents with the loss of long-term core cooling, performed using the RELAP5 model of Ignalina NPP reactor cooling circuit and safety systems. Different ways of potential accident management are discussed. On the basis of this analysis the accident management strategy was developed.

Fire hazard analysis at Ignalina Nuclear Power Plant

Abstract The fire hazard analysis methodology and main results of Ignalina Nuclear Power Plant RBMK-1500 type reactor's systems and rooms with safety elements and also rooms adjacent to main rooms and other fire hazardous rooms are presented. In total this concerns about 2100 rooms in the control area of one Unit, where the fire could influence nuclear safety of the power plant. For this purpose the decision-making computerized system FIRE-INPP was developed. It includes modules for recording necessary information, data processing, analysis and assessment on compliance of rooms at Ignalina NPP with national fire safety requirements and international recommendations regarding fire hazard. Screening algorithms and decision-making module are the basis for the decision-making computerized system, that allows to perform unambiguous, reliable and fast fire hazard analysis and give recommendations to ensure fire safety adequacy.

05/01032 Dynamic reliability and risk assessment of the accident localization system of the Ignalina NPP RBMK-1500 reactor

05/01032 Dynamic reliability and risk assessment of the accident localization system of the Ignalina NPP RBMK-1500 reactor

05/01038 Investigation on gasoline deep desulfurization for fuel cell applications

The paper presents modelling and analysis results of contamination of the RBMK-1500 reactor Low Salted Water System (LSWS) components and comparison of the results with other RBMK-1500 water systems at Ignalina NPP Unit 1. These results provide information for radiological characterization, which is an important task of the nuclear installation to be decommissioned. The modelling was performed using a computer code LLWAA-DECOM (Tractebel Energy Engineering, Belgium), taking into consideration LSWS components' characteristics, parameters of the water flowing in circuits, system work regimes, etc. During the modelling, results on activity of LSWS subsystems and components' deposits and nuclide composition of the 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.Analysis showed that there is significant difference of contamination levels among LSWS components. LSWS activity is lower than Main Circulation Circuit (MCC) and Purification and Cooling System (PCS) subsystems activity. Activity variation for LSWS components is smaller compared to MCC and PCS. Nuclides that mostly contribute to contamination in deposits of LSWS are corrosion nuclides as in MCC and PCS.

Nuclear knowledge management and preservation in Lithuania

Problems of nuclear knowledge management and preservation in Lithuania are presented in the paper. The support provided through bilateral cooperation projects was very important for Lithuania. The main projects implemented in the last 14 years are described in this paper. Lithuania joined INIS (International Nuclear Information System) in 1994 and established its own INIS national centre in the premises of the Ministry of Economy. To educate the public about the processes going on in Ignalina NPP, the information centre of Ignalina NPP was founded. Nuclear and nuclear related education in Lithuania is provided in the Kaunas Technological University.

Migration Peculiarities of Technogenic Radionuclides in the Ecosystem of Lake Drūkšiai Under Anthropogenic Conditions in 1988–1998

Activity concentrations of 137Cs, 60Co and 54Mn were determined in bottom sediments as well as in different species of hydrophytes and fish sampled at observation stations in Lake Drūkšiai and the Ignalina Nuclear Power Plant (INPP) wastewater canals. The radiogeochemical cartography of the distribution of radionuclide activity concentrations in hydrophytes growing in the littoral zone of the lake was produced. Sources of radionuclide inputs to the lake were identified. The impact of the Ignalina NPP wastewaters on bioaccumulation processes and migration of technogenic radionuclides in lake ecosystems was evaluated. It was established that in 1988–1998 the radioecological situation of Lake Drūkšiai was not stable. In hydrophytes, fish and bottom sediments of Lake Drūkšiai the lowest activity concentration values of radionuclides were observed in 1996–1998. Hydrophytes act as a primary barrier to radionuclide movement and reflect the one-season radioecological situation in a hydroecosystem most efficiently. However, bottom sediments, as a more conservative system, better reflect the long-lasting pollution with radionuclides.

Evaluation of the radiological consequences of14C due to contaminated Ignalina NPP graphite incineration

After decommissioning of Unit 1 of the Ignalina Nuclear Power Plant, the problem of the radioactive waste management emerged. Among radioactive waste there is an inventory of about 1700 tons of the graphite containing 14 C radioisotope as an activation product. The estimates show that the maximal total inventory of 14 C in graphite from Unit 1 is around 7 � 10 14 Bq. One of the possible ways for utilization of the graphite is its incineration in the radioactive waste processing plant. Unfortunately, in this case a significant amount of the radionuclide would be released into the atmosphere in the form of CO2 and the released radiocarbon would cause additional exposure of the population. Possible radiological consequences for the Lithuanian inhabitants are evaluated using the model of radiocarbon dispersion in the environment and considering several scenarios of the graphite incineration. Dispersion of the incineration gas is modelled using the Gaussian dispersion model. Assimilation of CO2 by the vegetation due to photosynthesis as well as washout of CO2 from the atmosphere by rain, uptake of the deposited 14 C by the plants from soil, and the eventual contamination of food products are considered. An estimated additional exposure effective dose to the critical group of the local population due to continuous releases of the total inventory of 14 C from the incinerator is of the order of 2.7 mSv. The consumption of the contaminated locally produced food products is the main contribution to the dose. Such continuous incineration of graphite would be acceptable if it were extended

Branduolinio reaktoriaus valdymo ir apsaugos sistemos modeliavimas

Ignalina NPP RBMK-1500 reactor control and protection system (RCPS) logic, which was implemented in code QUABOX/CUBBOX-HYCA, is described in the paper. Analysis of numerical simulation results shows, that logic of RBMK-1500 RPSS is adequate to logic as described in technical literature. Simulation results obtained by code QUABOX/CUBBOX-HYCA were compared with simulation results obtained us­ing STEPAN code. The conclusion was made that RCPS operation sequences and response are analogical. The complement the code QUABOX/CUBBOX-HYCA with full realistic RCPS logic allows to simulate the transient processes and accidents, which have place in the reactor core of Ignalina nuclear power plant.