The object of this paper is to study the specificity of the dynamics of carbon monoxide in mining to determine the location of the source of coal self-heating or spontaneous combustion. The Fire ...Dynamics Simulator software package was used to model the gas hazard of coal mine workings. Given the typical details for the western coal basin of Donbas geo metric dimensions of workings, properties of coal, etc., a model of a fragment of emergency mining of a coal mine was created, which allows for the display of geometric and physical similarity to processes in actual mine workings. The results of the simulation for the studied scenarios with different air supply systems related to the detection and location of sources of self-heating or spontaneous combustion in the coal mine workings were obtained and analysed. It was established that low-density fire gases are concentrated in the vault of the workings, where they slowly dissolve in the air, with the dissolution process being linear. It was revealed that air velocity up to 0.67 to 0.7 m/s contributes to the formation of fire gas flows, which move towards the ventilation flow, almost without mixing, which is referred to as bifurcation. Numerical parameters of fire gas dynamics in near-real conditions were established, which can become a basis for the detection and location of sources of endogenous thermodynamic processes in mine workings.
U radu se analizira posebnost dinamike ugljikova monoksida u rudarstvu kako bi se odredio smještaj izvorišta samozagrijavanja i samozapaljenja ugljena. Uporabljen je programski paket Fire Dynamics ...Simulator, kojim je modeliran rizik od plina na radilištu rudnika. Ogledno istraživanje načinjeno je na zapadu ugljenih bazena Donbasa uzimajući u obzir geometrijske dimenzije radilišta, svojstva ugljena itd. Stvoren je model za izvanredno rudarenje ugljena u izvanrednim okolnostima koji se može primijeniti na stvarne uvjete (geometriju, fizička svojstva) ugljenokopa. Simulacija je izvedena s nekoliko scenarija opskrbe zrakom s obzirom na smještaj detektora i izvora samozagrijavanja ili samozapaljenja. Utvrđeno je kako su zapaljivi plinovi male gustoće nakupljeni uz svod radilišta, gdje se sporo miješaju sa zrakom tijekom procesa koji je linearan. Prikazano je kako brzina strujenja zraka od 0,67 do 0,7 m/s pridonosi stvaranju toka zapaljivih plinova koji se tada gibaju prema ventilacijskome sustavu gotovo bez miješanja, ali s pojavama bifurkacije. Brojčane vrijednosti dobivene simulacijom za dinamiku zapaljivih plinova odgovaraju gotovo potpuno stvarnim uvjetima, te model može biti temelj za opažanje i smještanje endogenih (unutarnjih) termodinamičkih procesa na rudarskim radilištima.
During the accident in April 1986, the Cooling Pond (CP) of the Chornobyl Nuclear Power Plant (ChNPP) was heavily contaminated by fuel particles and radionuclides of cesium-137 (137Cs) and ...strontium-90 (90Sr). Starting from the end of 2014, a gradual decrease of the CP water level began leading to the transformation of the whole reservoir into eight separate sectors and raising the concern of the fate of 137Cs and 90Sr in the future. In this study, two mathematical models were applied to reproduce radioactive contamination of the CP from 1986 to 2021 and to provide a forecast of 137Cs and 90Sr concentrations in the CP water from 2022 to 2030. The hydrodynamic model THREETOX provided three-dimensional (3D) currents in the CP corresponding to hydrological conditions before and after water level drawdown, and these currents were used in the box model POSEIDON-F for the long-term simulations of the changes in 137Cs and 90Sr concentrations in water, bottom sediments, and biota. Seasonal changes in the distribution coefficient (Kd) describing the partition of 137Cs between water and sediments were considered in the box model, which allowed us to reproduce the observed variations of concentration. Calculated concentrations of 137Cs and 90Sr in water and freshwater fish occupying different trophic levels agreed well with measurements for the entire post-accident period. After the water level drawdown, concentrations of 137Cs in the CP water slightly increased in all eight sectors, while 90Sr concentrations significantly increased in sectors close to ChNPP, which was explained by an additional 90Sr source when comparing the simulation results and measurement data. Using the model forecast from 2022 to 2030, we predict that the concentration of both radionuclides will gradually decrease in new water bodies of the Cooling Pond except in the northern sectors, where the suggested additional source of 90Sr will lead to a stabilization of 90Sr concentrations.
During the accident in April 1986, the Cooling Pond (CP) of the Chornobyl Nuclear Power Plant (ChNPP) was heavily contaminated by fuel particles and radionuclides of cesium-137 (sup.137Cs) and ...strontium-90 (sup.90Sr). Starting from the end of 2014, a gradual decrease of the CP water level began leading to the transformation of the whole reservoir into eight separate sectors and raising the concern of the fate of sup.137Cs and sup.90Sr in the future. In this study, two mathematical models were applied to reproduce radioactive contamination of the CP from 1986 to 2021 and to provide a forecast of sup.137Cs and sup.90Sr concentrations in the CP water from 2022 to 2030. The hydrodynamic model THREETOX provided three-dimensional (3D) currents in the CP corresponding to hydrological conditions before and after water level drawdown, and these currents were used in the box model POSEIDON-F for the long-term simulations of the changes in sup.137Cs and sup.90Sr concentrations in water, bottom sediments, and biota. Seasonal changes in the distribution coefficient (Kd) describing the partition of sup.137Cs between water and sediments were considered in the box model, which allowed us to reproduce the observed variations of concentration. Calculated concentrations of sup.137Cs and sup.90Sr in water and freshwater fish occupying different trophic levels agreed well with measurements for the entire post-accident period. After the water level drawdown, concentrations of sup.137Cs in the CP water slightly increased in all eight sectors, while sup.90Sr concentrations significantly increased in sectors close to ChNPP, which was explained by an additional sup.90Sr source when comparing the simulation results and measurement data. Using the model forecast from 2022 to 2030, we predict that the concentration of both radionuclides will gradually decrease in new water bodies of the Cooling Pond except in the northern sectors, where the suggested additional source of sup.90Sr will lead to a stabilization of sup.90Sr concentrations.
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