Ivan Kovalets

Institute of Mathematical Machines and Systems Problems, National Academy of Sciences of Ukraine · Department of Environmental Informatics

The mesoscale meteorological/distributed hydrological model chain WRF/DHSVM was calibrated for simulation of extreme flood events in Uzh River basin in Ukrainian Carpathians. The flood event which happened in July, 2008 was successfully reproduced by using final analysis meteorological input data of the US National Centers for Environmental Predict...

Simulations of atmospheric dispersion of radon around the uranium mill tailings of the former Pridneprovsky Chemical Plant (PChP) in Ukraine were carried out with the aid of two atmospheric dispersion models: the Airviro Grid Model and the CALMET/CALPUFF model chain. The available measurement data of radon emission rates taken in the territories an...

A model of CO2 atmospheric transport in vegetated canopies is tested against measurements of the flow, as well as CO2 concentrations at the Norunda research station located inside a mixed pine–spruce forest. We present the results of simulations of wind-speed profiles and CO2 concentrations inside and above the forest canopy with a one-dimensional...

In this work, we present an inverse computational method for the identification of the location, start time, duration and quantity of emitted substance of an unknown air pollution source of finite time duration in an urban environment. We considered a problem of transient pollutant dispersion under stationary meteorological fields, which is a reaso...

In this work, we present a method to use the European nuclear emergency response system RODOS for analysis of potential sources of airborne radioactivity of an unknown origin. The method is based on a solution of adjoint equations, without modification of the code of long-range atmospheric dispersion model MATCH used in RODOS. The method has been s...

A computationally efficient source inversion algorithm was developed and applied with the Lagrangian atmospheric dispersion model DIPCOT. In the process of source location estimation by minimizing a correlation-based cost function, the algorithm uses only the values of the time-integrated concentrations at the monitoring stations instead of all of...

The evaluation of the previously developed one-dimensional model of radiocarbon atmospheric transport in vegetated canopies against C-14 concentration data collected at the site of SMEAR-II research station was pre-sented. In most cases, the simulated vertical profiles of C-14 concentrations within the canopy layer agreed reasonably with measuremen...

Introduction. Air pollution modeling is a powerful tool that allows developing scientifically justified solutions to reduce the risks posed by atmospheric emissions of pollutants. Problem Statement. Cloud computing infrastructures provide new opportunities for web-based air pollution forecasting systems. However the implementation of these capabili...

This paper presents model results for the dispersion of radionuclides released into the atmosphere by intense forest fires in the Chernobyl Exclusion Zone in April 2020. The ¹³⁷Cs activity concentration in the surface air is calculated on a regional scale (in Ukraine) and a local scale (within the Chernobyl Exclusion Zone). The ¹³⁷Cs activity in th...

The possibility of using grid and spectral relaxation methods (nudging) and other options in the mesoscale model WRF for long-term continuous and forecast calculations on fine-resolution grid in the vicinity of Kyiv has been investigated. Results of comparison of selected meteorological parameters with surface measurements are presented. The basic...

The JRODOS nuclear emergency response system was applied for estimation of risks caused by transboundary transport of possible accidental release from the newly designed units 3&4 of Khmelnitsky NPP. The total effective potential dose for 1-year children, received during 1 year after release from all pathways was calculated and used as measure of i...

The paper presents the results of the simulation of secondary air pollution scenario in Ukraine due to the wind lift of anthropogenic radionuclides during a dust storm in April 2020. A variant of the Bagnold formula was used to parameterize the intensity of radionuclide resuspension. To set the initial pollution of the territory of Ukraine, the rec...

Earlier this year international media reported on the large forest fires taking place near the abandoned Chernobyl nuclear plant. Although the disastrous accident with Chernobyl’s reactor #4 took place over thirty years ago, it still remains part of our collective memory. Adequate protection of the public against the radioactive debris and abandone...

The highly contaminated Chernobyl exclusion zone (ChEZ) still remains a potential source of the additional atmosphere radioactive contamination due to forest fires there. The possible radionuclide transport outside the ChEZ in the direction of populated regions (including Kyiv, 115 km from the ChEZ borders) and its consequences for people health is...

For the first time, a pilot simulation of atmospheric pollution in Kyiv from all known sources of nitrogen dioxide, sulfur dioxide and ammonia was carried out. For simulation, we used both the reports of on annual emissions of stationary sources in Kyiv from the State Statistics Service of Ukraine (SSSE) and the data of the international geo-distri...

The possibility of using grid and spectral relaxation methods and other options in the WRF mesoscale model for long-term continuous calculations has been investigated. Results of comparison of selected me-teorological parameters with surface measurements are presented. The basic recommendations for select-ing the optimal combination of long-term ca...

The Black sea is a deep semi-enclosed dilution basin connected with the Mediterranean Sea by shallow and narrow Turkish Straits. The simulation of sea level, temperature and salinity change in the Black Sea in 2000-2100 was carried out using a chain of models, which includes models of the Black and Azov Seas, as well as the Kerch Strait, the Turkis...

This paper examines the issue of radionuclide resuspension from wildland fires in areas contaminated by the Chernobyl Nuclear Power Plant explosion in 1986. This work originated from a scientific exchange among scientists from the USDA Forest Service, Ukraine and Belarus that was organized to assess science and technology gaps related to wildfire r...

The development of the source inversion algorithm is described which allows for estimation of the release rates of multiple nuclides and source height with the use of gamma dose rate (GDR) measurements. The method is applicable for the dispersion problems of different spatial scales: from ~1 to ~1000 km. The variational formulation of source invers...

Results of testing of Advanced Source Inversion Algorithm (SIA) integrated in JRODOS system against synthetic measurements are described. L-curve approach was found to be useful for setting regularization parameter (alfa_sigmab) of the algorithm. Even with heavily wrong first guess time dependent source term (S.T.) error of estimated S.T. was decre...

An improved inverse modelling method to estimate the location and the emission rate of an unknown point stationary source of passive atmospheric pollutant in a complex urban geometry was incorporated in the Computational Fluid Dynamics code ADREA-HF in Efthimiou et al., (2017). The key improvement lies in a two-step segregated approach. At first on...

The evaluation of the previously developed one-dimensional model of radiocarbon atmospheric transport in vegetated canopies against micrometeorological and C-14 concentration data collected at SMEAR-II research station is presented for the first. In most cases, the simulated vertical profiles of C-14 inside canopy layer reasonably agree with measur...

The estimation of a hazardous contaminant unknown source characteristics (i.e., rate and location) in a complex urban environment using efficient inverse modelling techniques is a challenging problem that involves advanced computational fluid dynamics combined with appropriate mathematical algorithms. In this paper we further assess our recently pr...

The intentional or accidental release of airborne toxics poses great risk to the public health. During these incidents, the greatest factor of uncertainty is related to the location and rate of released substance, therefore, an information of high importance for emergency preparedness and response plans. A novel computational algorithm is proposed...

In this report we consider the problem of estimating the unknown parameters of a hazardous pollutants release in the atmosphere. The problem known as 'source term estimation' or 'source inversion' is ill-posed and hence extremely difficult to solve. Recently we developed a method [1] in which instead of a commonly used quadratic cost function we as...

It is developed information web technology that allows upon users’ request to forecast meteoro-logical conditions at arbitrary territory with high resolution, on the basis of adaptation of modern mete-orological model and web-technologies for providing model with input data, obtaining and visualization of results.

An improved inverse method was presented recently for the estimation of the location and the rate of an unknown point stationary source of passive atmospheric pollutant in a complex urban geometry. The inverse method was incorporated in the well-established and updated version of the ADREA-HF Computational Fluid Dynamics code. The key improvement o...

An improved inverse method was presented recently for the estimation of the location and the rate of an unknown point stationary source of passive atmospheric pollutant in a complex urban geometry. The inverse method was incorporated in the well-established and updated version of the ADREA-HF Computational Fluid Dynamics code. The key improvement o...

Within the framework of this research, information technology for forecasting atmospheric pollutant transport following manmade accidents with emissions of hazardous matters has been developed. It is based on the integration of emission scenarios, atmospheric transport models of different complexity (from simplified local screening models to CALPUF...

An update of this work was recently published in Kovalets I.V., Romanenko O., Synkevich R. (2020) Adaptation of the RODOS system for analysis of possible sources of Ru-106 detected in 2017. Journal of Environmental Radioactivity, 220-221C (2020) 106302 https://dx.doi.org/10.1016/j.jenvrad.2020.106302

We recently developed the method for identification of location, start time, duration and release rate of an unknown short-duration source of airborne pollution in urban environment. The method has been integrated in the ADREA-HF CFD code and the testing has been carried out by performing series of source inversion runs using the data of 200 indivi...

We recently developed the method for identification of location, start time, duration and release rate of an unknown short-duration source of airborne pollution in urban environment. The method has been integrated in the ADREA-HF CFD code and the testing has been carried out by performing series of source inversion runs using the data of 200 indivi...

Please refer to published version of this article Kovalets et al. (2018) Atmos. Env. 181:82-9 https://www.researchgate.net/publication/323726600_Inverse_identification_of_unknown_finite-duration_air_pollutant_release_from_a_point_source_in_urban_environment

Published in Atmospheric Environment (2018) , DOI: 10.1016/j.atmosenv.2018.03.028. Full text freely available here: https://www.researchgate.net/publication/323726600_Inverse_identification_of_unknown_finite-duration_air_pollutant_release_from_a_point_source_in_urban_environment

A methodology has been developed that makes it possible to use the long-range atmospheric transport model MATCH of the JRODOS nuclear emergency response system to solve the problem of identifying the location of an unknown source after detection of radioactivity. The developed method was applied for the case of detection of I-131 in Europe in Octob...

An improved inverse modelling method to estimate the location and the emission rate of an unknown point stationary source of passive atmospheric pollutant in a complex urban geometry is incorporated in the Computational Fluid Dynamics code ADREA-HF and presented in this paper. The key improvement in relation to the previous version of the method li...

In this work we present an automated source inversion algorithm suitable for usage in the real-time online 10 emergency response system JRODOS in which measurements of gamma dose rates and other quantities taken at a wide 11 range of distances from the Nuclear Power Plant are used to provide estimates of the time-dependent emission rates of 12 diff...

Web system is available online http://env.com.ua:88/airsystem/airsystem_connect.html In the work the calculations of affected areas following the discharges of dangerous substances in air using screening models were automated in a pilot version of the software and simulation system of operational air pollution forecasting in Ukraine. Software imple...

The work presented in this report is part of the biosphere modeling studies that were carried out within the SR-PSU project, dedicated to the safety assessment of the Forsmark repository for LILW. The report presents a new assessment model of the C-14 transport in the surface atmosphere above vegetated land that receives releases of this radionucli...

An improved inverse method was presented recently for the estimation of the location and the rate of an unknown point stationary source of passive at-mospheric pollutant in a complex urban geometry. The inverse method was incorporated in the well-established and updated version of the ADREA-HF Computational Fluid Dynamics code. The key improvement...

In this paper a description is given of software tools that have been developed during the NERIS-TP project which provide the capability to users of Decision Support Systems (DSSs), such as JRODOS, to calculate their own prognostic meteorological data with the desired spatial and temporal resolution. These tools increase the flexibility of applying...

The task of accurate estimation of consequences of radioactive carbon (14C) releases from nuclear facilities requires modeling of CO2 transport in plant canopies, since a large fraction of 14C is released and transported in the form of 14CO2 and can be taken up by plants via photosynthesis. One-dimensional models of radiocarbon transport in the env...

The atmospheric release of hazardous materials in urban or industrial environments can be the result of an accident, with potential consequences in local or regional scale, or can be an intentional act of violence. In such cases the highest uncertainty is associated with the location of the release and the quantity of the released substance. So far...

In Kovalets et al. (2011), a method was developed to estimate the location and rate of an unknown point stationary source of passive atmospheric pollutant in a complex urban geometry. The algorithm was implemented in the ADREA-HF Computational Fluid Dynamics code and was applied in a complex urban geometry (the MUST wind tunnel experiment). This ap...

In this work we present model setup and results of calculated concentrations of radioactive aerosols and radon at the territories of the former Pridneprovsky Chemical Plant in Ukraine. For the numerical description of a resuspension from the bare soil the approximate empirical formula (Loosmore and Hunt, 2000) was used. Satisfactory comparison of t...

This report was published as a book chapter. Please use a full text of this book chapter from here: https://www.researchgate.net/publication/328700343_Advanced_Source_Inversion_Module_of_the_JRODOS_System In this report we describe the development of the source inversion algorithm in which measurements of gamma dose rate and other quantities taken...

A fast and simple method using Nuclear Power Plant fence measurements for source term estimation is presented in this work. The method is suitable for usage in a decision support system for off-site emergency management such as JRODOS. The article provides short introduction to basic principles and model application, input data, methodology, uncert...

The report documents a preliminary radiological safety assessment of the Zapadnoe uranium mill Tailings Facility (Zapadnoe Tailings Facility). Zapadnoe Tailings Facility is situated in the south western part of the industrial site of the former Pridneprovsky Chemical Plant site (PChP site), Dneprodzerginsk, Ukraine. Pridneprovsky Chemical Plant is...

In this work we presented model setup and results of calculations of yearly average concentrations of radioactive aerosols and radon at the PChP industrial site and Suhachivske site. Simulations had been carried out with the aid of US EPA CALMET/CALPUFF model chain. Satisfactory comparison of the simulated yearly averaged radon concentrations with...

This work presents the results of adaptation of the operational numerical weather forecasting system WRF-Ukraine for calculation of the detailed precipitation fields to be used in flood warning systems in the Ukrainian parts of the Prut and Siret basins. This allows for taking into account the influence of the orography (Carpathians) on precipitati...

The daily-average concentrations of Cs-137 increased by several times outside the Chernobyl Exclusion Zone following forest fires in April-May, 2015; - The radiological consequences of such increase are negligible (maximum effective dose ~0.01 nSv) and by a few orders of magnitude less than doses created by background radiation; - The radioactive...

Far range atmospheric dispersion model MATCH of the nuclear decision support system JRODOS was successfully used for forecasting of atmospheric dispersion of radionuclides following fire which happened in April-May, 2015 in Chenobyl Exclusion Zone. The forecast reported in this work was produced on April,29-th 2015 for the next 4 days and during th...

Verification of OpenFoam (Open Source Field Operation And Manipulation CFD ToolBox) is carried out. Numerical modeling MUST experiment (atmospheric transfer of pollution in urban area) is executed. The acceptable values for a meteorological field and a field of pollution are received. The results of modeling are commensurable with results of other...

'This is English translation of the article Kovalets IV.., Romanenko A.N., Anulich S.N., Ievdin I.A. (2015) Forecasting of the radioactive contamination by Cs-137 following fires in Chernobyl Exclusion Zone in April-May, 2015 // Proc. of 'Decision Support Systems. Theory and Practice' (DSS 2015), Kiev, 8 June 2015 [in Russian] doi: 10.13140/RG.2.1....

We are concerned with source term retrieval in the case of an accident in a nuclear power with off-site consequences. The goal is to optimize atmospheric dispersion model inputs using inverse modeling of gamma dose rate measurements (instantaneous or time-integrated). These are the most abundant type of measurements provided by various radiation mo...

Intense precipitation event happened in Ukraine on 21-27 July 2008 leading to extreme flash floods in the Ukrainian Carpathians which are characterized by the return period of approximately 50 years. Besides favourable synoptic conditions leading to quasi-stationary low situated over Balkans and South-West part of Ukraine precipitation during this...

Mesoscale WRF meteorological model, adapted to provide a system of nuclear emergency response RODOS with operational meteorological information for the conditions of Rivne NPP was successfully verified on the basis of the measurement data of RNPP meteostation and sodar. Miscalculations of wind direction near RNPP are local in nature and reduce with...

The method of statistical downscaling of climate change scenarios according to the data of global circulation models for the conditions of the Ukrainian Carpathians is proposed. According to results of calculations for the Ukrainian part of the Uzh River watershed, during the next 30 years the amount of daily precipitation occurring 1 per 100 years...

In this report we review the methodologies that can be used to address the following issues in the frame of an inverse-modelling methodology for calculating the unknown accidental emissions of radionuclides: 1. Estimation of uncertainties in the dispersion model’s calculations 2. Estimation of uncertainties in the 1st-guess estimate of the source t...

The paper addresses following subjects: - Site location, operation history and contaminated legacies - Remediation history, National Remediation Programs and International Technical Assistance Projects - Current monitoring program, radiation hazards and remediation challenges/difficulties - Results of ENSURE-II (Ukraine-Sweden bilateral technical a...

In the present report an innovative computational data assimilation algorithm for estimating the location and rate of an unknown stationary point source of passive atmospheric pollutant in a complex urban geometry recently developed in NCSR “Demokritos” is evaluated. The evaluation was performed by using the measurements of the turbulent flow, 1:22...

Integration into JRODOS the models of radionuclide transport in rivers, reservoirs and coastal waters to support the emergency response in early accidental stages 0 20 40 60 80 100 120 140 160 180 1 Decision Support System RODOS The decision support system for offsite nuclear emergency management RODOS (Real-time on-line decision support), develope...

A general Safety Assessment Methodology has been developed within the framework of the Sweden SSM – Ukrainian Ministry of Energy and Coal Industry Cooperation Project ENSURE-2 in preparation for remediation activities at the Pridneprovsky Chemical Plant (PChP), a uranium production legacy site, located in Dneprodzerzhinsk, Ukraine. The objective of...

The paper presents results of the application of the OpenFoam CFD code for the assessment of the annually-average pollution (non-dimensional concentrations) in the vicinities of the buildings of the former uranium facilities ‘Pridneprovsky Chemical Plant’ (PChP). The simplified model based on stationary fluid dynamics equations had been used which...

This document describes the convertor developed to prepare input numerical weather prediction data for the far-range model of atmospheric transport MATCH of the RODOS system using the numerical weather prediction data calculated with WRF mesoscale meteorological model. Since WRF is freely available and it is widely used among the atmospheric modell...

This extended abstract of the Report 'Testing atmospheric-vegetation carbon model using the Norunda dataset'

This extended abstract of the Report 'Testing atmospheric-vegetation carbon model using the Norunda dataset'

Data Assimilation (DA) algorithms, allowing the simultaneous use of Numerical Weather Prediction (NWP) with measurement data in the stand-alone version of the Meteorological Pre-Processor (MPP) of the RODOS system, have been developed, successfully evaluated and further optimised in the frames of past EURATOM Grants by the authors. This report desc...

The paper presents estimates of the far-range atmospheric dispersion of radionuclides after the accident at Fukushima Daiichi Nuclear Power Plant (NPP), obtained using the long-range atmospheric dispersion model MATCH. Software tools were developed to run MATCH in the EU nuclear emergency response system JRODOS using freely available numerical weat...

Report of the EU FP7 PREPARE Project, PREPARE(WP4)-(14)-01 The object of this report is the “top-down” algorithms applicable for the estimation of the radionuclide emission characteristics during the emergency phase of a nuclear accident, i.e., released reactor inventory, time distribution of release rate and height of the release. In “top-down” (o...

An automated system is presented for forecasting weather conditions to be used in the European decision support system in case of nuclear emergency accidents JRODOS

This paper presents model estimates on the hemispheric scale of Cs137 from the sever nuclear power accident at NPP Fukushima. Modelling is made by the MATCH model (Robertson et al., 1997) and release estimates taken from Stohl, 2012. Comparisons with nuclide filter measurements at six stations in Sweden exhibit remarkably good results, given that t...

This document describes software which is developed to provide the RODOS system with numerical weather prediction data for the arbitrarily located computational domain where RODOS is installed in case if NWP data are not delivered to the emergency center by an external supplier (such as National Weather Services). This program works with freely ava...

The non-stationary character of climate changes in the Ukrainian Carpathian Region – i.e. decrease of return period of extreme floods, was shown for the first time by downscaling selected global climate change scenarios and by using improved methods developed for distributed watershed hydrological modeling. The research outputs were used to demonst...