Burnup Rate Research Articles

Cross-jurisdictional analysis and forecasting of North American nuclear fuel inventory using a standardized unit

This study fills the noted gap in comparative analyses of spent nuclear fuel (SNF) by assessing inventories from two key nuclear power regions, the USA and Canada, using a comprehensive analytical framework and standardized data from 2009 to 2021. In the USA, SNF inventory increased by 14.7 % in fuel assembly weight and 47 % in residual heavy metal content compared to Canada, in line with their use of light water reactors. Canada's SNF production is directly correlated to its nuclear power output, influenced by the lower burnup of natural uranium fuel used in CANDU reactors (R2 = 0.57; p-value < 0.05) while the USA shows insignificant correlation, likely due to a variety of reactor types and higher burnup rates (R2 = 0.008; p-value > 0.05). Further, the study identifies a strong negative correlation between uranium mine production and SNF inventory in the USA, indicating a reliance on imports amidst negligible domestic mining. In contrast, Canada also exhibits moderate negative dependency due to its position as a major uranium exporting jurisdiction. The obtained negative correlations with coal rents in both countries indicate a shift towards more nuclear energy use, impacting economic growth and energy patterns. The developed predictive models indicate a higher future SNF increase in Canada than in the USA. These findings are essential for planning the transition from temporary to permanent SNF disposal, ensuring safe long term management of radioactive waste.

Experimental burn-up analysis of ITU Triga Mark II reactor fuel elements

In this study, burn-up values ​​of spent fuels were determined using Non-Destructive Analysis (NDA) with the help of 137Cs burn-up indicator. Four spent fuel elements (F30, D18, B5 and E14) that burned in the core of the Istanbul Technical University Triga Mark II research reactor over the years were investigated with two different methods. In addition, the individual activity of the fuel elements along the axial fuel length was determined by the High Purity Germanium (HPGe) detector. As expected, it was determined that the fuel element B5, located in the center of the reactor core, exhibited the highest burn-up value with both methods. The calculations conducted using method 1 revealed a burn-up rate of 5.40% for the B5 fuel element, while method 2 yielded a burn-up value of 205.59 MWd/tHM. Experimental results were compared with previous simulation burn-up studies.

Numerical simulation of the co-firing of pulverized coal and eucalyptus wood in a 1000MWth opposed wall-fired boiler

Currently, coal-fired coupled biomass power generation is widely regarded as a primary method for reducing carbon emissions in coal-fired power plants. This research investigates the co-firing of biomass in an opposed wall-fired boiler and the implementation of air-staged combustion technology using numerical simulation approaches. The study examines the impact of various air methods of distribution and blending ratios on combustion properties and NOx emissions. The findings demonstrate that the abrasive wear of fuel particles on the platen superheater is decreased by the addition of biomass to the fuel mix. Furthermore, a drop in the furnace chamber's overall temperature is the outcome of raising the blending ratio. Different blending ratios have their own adapted air distribution methods. At blending ratios of 10% and 30%, the W-type air distribution exhibits the lowest NOx outlet concentrations of 231.84 mg/Nm3 and 220.6 mg/Nm3, respectively. Moreover, the W-type air distribution shows the highest burnup rates of 98.74% and 98.43% at these blending ratios. This suggests that it is feasible to change the burner monolayer air distribution and combine it with co-firing of biomass technology to achieve low NOx and efficient operation of a hedge-fired boiler.

SELECTING OF MATRIX COMPOSITION FOR IMMOBILIZATION OF IRRADIATED FUEL OF THE IGR REACTOR

Impulse Graphite Reactor (IGR) is a unique nuclear installation namely research reactor with the core consisting of uranium-graphite fuel elements with 90% enrichment by U235. Possible immobilization of the first core taken from the reactor in 1967 is studied here as part of the IGR reactor conversion to low-enriched uranium fuel. Irradiated fuel is related to the category of mediumactive waste according to the content of beta-emitters. Expected value of highly-enriched uranium fuel (HEU) burnup rate was less than 1 % mass. The experts from the Institute of Atomic Energy (IAE) proposed the way how to immobilize irradiated IGR reactor fuel into the cement matrix. First, the fuel is suggested to dilute with depleted uranium in order to lower the enrichment up to the &lt;20 mass. % by U235. The properties of the matrix should meet the engineering criteria ruled by international and national standards. So, according to aforesaid, The IAE team is facing an actual problem of selection the matrix and understanding its characteristics.The work was aimed at selection of composition of cement mortar for making robust matrix to immobilize irradiated IGR reactor fuel.The paper describes techniques and results of the time identification (start) of solidification, gradual volume change, water separation, velocity and uniform cement mortar.

Measurement of 6Li burn-up reaction rate using a single crystal CVD diamond detector under fast neutron irradiation environment

The study aimed to develop a technique for measuring the 6Li burn-up rate using a single crystal diamond (SCD) detector (SDD) made by chemical vapor deposition (CVD) with a thin lithium fluoride foil. The method relied on pulse shape discrimination (PSD) to separate pulses by nuclear reaction products of 6Li from pulses due to fast neutrons and gamma-rays.By applying the PSD method, the rectangular shape pulses induced by events occurred at the specific depth positions of the SCD, i.e., the incident surface, the ballistic center region (BCR), and the rear surface, were extracted. Thereafter, pulses occurred each specific depth position of the SCD were discriminated according to the pulse width.Due to a short range of nuclear reaction products in the SCD, pulses at the incident surface should be induced by both fast neutrons and nuclear reaction products, although pulses at the BCR are caused by fast neutron only. The study demonstrated that quantitative measurements of nuclear reaction products in the 6Li burn-up reaction under fast neutron irradiation can be achieved using only one SDD by analyzing event rates at the incident surface and in the BCR region.

Particle size influence on the aluminum combustion dynamics in 1-m&lt;sup&gt;3&lt;/sup&gt; chamber

Introduction. The results of a standard study of the explosibility of aluminum air suspensions (AAS) can contribute to the development of AAS combustion physics. In particular, a complex of information about the polydispersity and of the AAS low explosion limit values in a 1-m3 chamber made it possible to determine the maximum particle size of the explosive fraction of a polydisperse sample d*m,t ≈ 40–50 µm (Poletaev, 2014). In the present work, a relationship is established between the AAS combustion dynamics in a 1-m3 chamber and persion. The dispersity of sample particles is described by the mass-average particle size of its explosive fraction (d*50), in contrast to the works of other researchers who use the mass-average size of all particles (d50).Initial data. Known information about the dispersity and explosion parameters of 15 aluminum samples studied in a 1-m3 chamber was used. The continuous particle size distribution functions necessary for calculating d*50 were represented by the Rosin – Rammler distributions filling the gaps between the discrete data of the sieve analysis of the samples.Combustion dynamics. The dynamics of AAS turbulent combustion in a 1-m3 chamber is represented by the maximum air suspension burn-up rate Ub. Ub was calculated using the formula (Kumar, 1992) intended for gas-air mixtures by substituting the AAS explosion parameters into this formula.Results and its discussion. A plot of the d*50 Ub complex versus d*50 is shown. The average value of the complex (≈ 33 µm·m/s) is constant in the range 10 ≤ d*50 ≤ 35 µm. The latter is typical for the product of the particle size and the normal velocity of the laminar flame in AAS (Ben Moussa, 2017) and indicates the similarity of the effect of particle dispersion on the dynamics of turbulent and laminar combustion of AAS.Conclusions. The dispersion of an explosive polydisperse aluminum sample is determined by the average particle size of the explosive fraction of the sample d*50. The similarity of the combustion patterns indicates a relationship between the mechanisms of laminar and turbulent flame propagation in AAS.

Contribution of simulation to study ionizing radiation in endovascular surgery

In the last decade, endovascular surgery became the first-line treatment of aneurysms and occlusive lesions. The complexity of certain procedures exposes the patient and the operators to a high burn-up rate. Preoperative digital simulation can help to decrease this exposure by planning the procedure and simulating the ionizing radiations. The Monte Carlo simulation techniques (MC), i.e. the simulation of particles in matter, allow a precise and personalized calculation of the radiation dose received by the patient.

The neutronics effect of TRISO duplex fuel packing fractions and their comparison with homogeneous thorium‐uranium fuel

To improve the performance of the thorium fuel, the duplex fuel potential for the micro-sized high-temperature reactor (HTR) using TRISO fuel has previously been investigated. The objective of this work is to expand on past research by delving deeper into several crucial components of the microheterogeneous thorium-uranium TRISO fuel compact. The MCNPX simulation was used to compare the neutronic performance of TRISO duplex fuel to that of homogeneous (Th,U)O2 fuel at various packing fractions and 235U enrichment. Variations in duplex fuel packing fraction and 235U enrichment were shown to have a significant effect on the neutronics of TRISO fuel. The fuel rod with 20% TRISO packing fraction has the highest kinf value at BOC, fastest burnup rate, fastest 235U depletion, and longest cycle length. As the packing fraction increases, these values however deteriorate in the opposite direction. Furthermore, the conversion ratio increases and the Doppler effect becomes stronger. The findings of evaluating duplex fuel rods at the fuel block level differed. The 40% packing fraction fuel block model achieves the lowest reactivity swing, the strongest Doppler effect, and the longest cycle length. As its packing fractions reduced to 30% and 20%, the values changed in the opposite direction. In comparison to the duplex fuel design, the homogenous TRISO fuel has a lower achievable discharged burnup and shorter cycle length. However, at the beginning of its cycle, it has a stronger doppler effect and lower pin power peaking. Despite the fact that the duplex's power peaking value drops with increasing burnup and becomes comparable to homogeneous fuel, these are some of the challenges and concerns that should be addressed in future research. Despite this, the overall result indicates that the duplex fuel design has promising potential for application in a micro-sized HTR.

Optimal Radial Build and Transmutation Properties of a Fusion-Based Transmutation Reactor with Molten Salt Coolants

The optimal shape of a fusion-based transmutation reactor with a molten salt coolant was determined by plasma physics, technology, and neutronic requirements. System parameters such as neutron multiplication, power density, shielding, and tritium breeding, were calculated in a self-consistent manner by coupling neutron transport analysis with conventional tokamak systems analysis. The plasma physics and engineering levels were similar to those used in the International Thermonuclear Experimental Reactor. The influence of aspect ratio of the tokamak and fusion power on the radial build, and the transmutation properties associated with two molten salt options, FLiBe and FliNaBe, were investigated. Being compared with a transmutation reactor with a small aspect ratio, a transmutation reactor with large aspect ratio was smaller in size and had a larger maximum fusion power. This type of reactor also revealed increased tritium-breeding capability and a smaller initial transuranic (TRU) inventory with a slightly lower burn-up rate. The burn-up rate for molten salt using either FLiBe or FLiNaBe was similar, but the initial TRU inventory and the tritium-breeding capability were smaller with FLiNaBe compared with FLiBe.

Определение удельной массовой скорости выгорания многокомпонентных нефтепродуктов

The specific mass burn-up rate of combustible substances (materials) in case of a fire, determines the heat release intensity, the temperature of burning, the intensity of fire development and other parameters. Like the rate of flame propagation, the mass burn-up rate depends on the physical and chemical properties of substances, their aggregate state, as well as other factors. The mass burn-up rate is used in modeling the process of fire development, assessment of the rate of heat release and the intensity of the supply of extinguishing agents to fire extinguishing installations. Currently, the values of the specific mass burn-up rate are given in various reference materials for a limited number of petroleum products. For single-component substances, the desired value can also be determined by calculation. The existing calculation formulas in theory are applicable for both simple and complex substances, and, in this case, there is a need to calculate the values of the specific heat of combustion and evaporation, the specific heat capacity of the substance. However, the process of complex hydrocarbon fuels burn-up differs significantly- it is due to the gradual burning out of individual fractions in their composition. Therefore, for complex substances the calculation should be made considering the changes in density and temperature during the process of burning. The methods for determining the specific mass rate of burnout of multicomponent petroleum products are considered, the universal nomogram and calculation formula are proposed that will allow determining the specific mass rate of burn-up, knowing the density of the petroleum product under normal conditions and its boiling point.

Effect of gap design pressure on the LWR fuel rods lifetime

Abstract The fuel burn-up rate has been raised in recent years to improve the efficiency of nuclear LWRs (light water reactors). Therefore, surveying and estimating changes in fuel properties and structural materials during radiation exposure is of paramount importance. In the present study, the researchers focused on analyzing the role of LWR fuel rod initial gap pressure (initial gas pressure when a fuel rod is fabricated) on the rod’s thermal and mechanical performance. FRAPCON-4.0 steady-state fuel performance code was used to simulate the effect of initial gap pressure on the behavior of a specific BWR-type fuel rod that was irradiated under the HALDEN research program. This fuel rod is similar to commercial BWR fuel rods in all respects, except that the research reactors have a height limit. The important fuel design criteria, such as the centerline temperature, effective stresses, total released fission gas to the fuel rod’s void volumes, and the cladding strains, were included in the analysis. According to the present study, a potential initial gap pressure range could be suggested to increase fuel rods’ lifetime by improving the safety criteria margins, especially fuel centerline temperature and the released amount of gaseous fission products. As we know, lower fuel temperature leads to having a reactor with a higher power density and, consequently, a maximum fuel burn-up rate, which can affect the economy and safety of nuclear power plants.

Оценка относительного приращения (перепада) температуры газовой среды в интегральной математической модели пожара в зданиях в начальной стадии

Within the framework of the integral mathematical model for the building fire’s initial stage, the increments of the gas medium temperature in the initial stage of a fire development in buildings have been determined, and estimates for these increments have been presented. The dependence between the gas medium temperature’s relative increment and the burn-up rate’s average value has been established, and an estimated formula for the relative temperature difference over a given time period has been obtained.

Delayed fast neutron as an indicator of burn-up for nuclear fuel elements

Feasibility study of burn-up analysis and monitoring using delayed fast neutrons was investigated at Missouri University of Science and Technology Reactor (MSTR). Burnt and fresh fuel elements were used to collect delayed fast neutron data for different power levels. Total reactivity varied depending on the burn-up rate of fuel elements for each core configuration. The regulating rod worth was 2.07E-04 Δk/k/in and 1.95E-04 Δk/k/in for T121 and T122 core configurations at 11 inch, respectively. Delayed fast neutron spectrum of F1 (burnt) and F16 (fresh) fuel elements were analyzed further, and a strong correlation was observed between delayed fast neutron emission and burn-up. According to the analyzed peaks in burnt and fresh fuels, reactor power dependency was observed and it was determined that delayed neutron provided more reliable results at reactor powers of 50 kW and above.

THE EFFICIENCY OF RADIATION SHIELDING MADE FROM MATERIALS WITH HIGH ATOMIC NUMBER AND LOW MASS DENSITY

The radiation shielding from γ-quanta of the existing transport containers (TC) for transportation of spent nuclear fuel (SNF) is made of steel or steel plus Pb 25…30 cm thick and weighting ~ 60…80 t. The application of materials with high atomic number, dispersed (solids grinded to a powdery state) to the densities in the range 4 &lt; ρ &lt; 8 g/cm3, is investigated. Simulations based on the Monte Carlo method show that at the densities of dispersed depleted U larger than 5 g/cm3 and shielding thicknesses of more than 30 cm, the absorption of γ-quanta of SNF is greater than that of the shielding made of steel of the same thickness. The application of such materials, while the weight characteristics of the shields are not exceeded, provides radiation shielding for SNF with the high burnup rate and the smaller cooling time or larger amount of the transported SNF.

Методика определения массовой скорости выгорания горючих жидкостей

Introduction. In accordance with the provisions GOST 12.1.044-89 (ISO 4589-84) (Fire and Explosion hazard substances and materials. Nomenclature of indicators and metods of their determination) one of the important parameters of liquid combustion are the mass rate of liquid burnout and the influence of various conditions of the combustion process on the mass burnup rate. A laboratory method for determining the mass burnout rate of a combustible liquid has been developed. Goals and objectives. The aim of the study is to develop a laboratory method for determining the mass rate of liquid burn-up, which can be used in the educational process during laboratory work and to simulate the effect of combustion conditions on the mass rate of liquid burn-up. Methods. To implement this task, we used video recording of changes in the mass of the liquid during its combustion in vessels of different diameters, followed by graphical processing of the results of experiments for calculate the burn-up rate under different combustion conditions. Results and discussion. The method was tested on the example of the combustion of acetone. An example of computer-graphical result for calculating the mass rate of acetone burn-up is given. The empirical dependents of the acetone burn-up rate on the diameter of the liquid surface area is obtained. Conclusions. A laboratory method for determining the mass rate of burnout of a flammable liquid, which can be used in the educational process during laboratory work, has been developed. In contrast to GOST 12.1.044-89 (ISO 4589-84), the developed method can use vessels with a liquid diameter of more than 60 mm. Keywords: burnout rate, acetone, laboratory technique

Моделирование тушения пожаров нефтепродуктов в резервуарах с применением водопенных огнетушащих веществ

The decisive parameter in the design of automatic fire extinguishing systems in the depots for storing oil and oil products, the organization of fire extinguishing in the tanks with mobile equipment is the standard (critical) foaming agent supply rate. The purpose of this work is to evaluate the influence of the scale of model fire centers and their design on the values of critical intensity of the foam solution supply. The article presents the results of the analysis of the scientific studies of the process of oil products combustion and approaches to determining the standards for supplying a foaming agent solution to extinguish fires in the tanks. It is shown that the existing fire extinguishing modeling methods in the tanks do not fully take into account the effect on the extinguishing process of the following factors: the &nbsp;change in the rate of oil products burn-up depending on the tanks sizes, the transformation of the aerodynamic characteristics of the medium in the vicinity of the combustion zone, the scale and design of model combustion centers, means and methods of foam supply. The analysis of the work on estimating the burn-up rate of flammable liquids in the tanks of various diameters does not allow to conclude what the minimum size of the experimental tank should be, so that the results obtained for determining the critical intensity of the foam solution supply would not cause anyone doubts. The paper presents the results of mathematical modeling of changes in the heat flux density on the surface of burning gasoline in the tanks with a diameter of 3 m, 5 m and 21 m. It is shown that combustion in small-diameter tanks does not simulate the thermal regime of a fire implemented on the large-diameter tanks. Consequently, the foaming agent solutions critical on intensity supply for small and large tanks differ from each other. &nbsp;The combustion source used in a number of documents do not simulate the conditions for heating the side of a real tank, which explains the failure to extinguish fires in the large tanks. It is proposed to determine the intensity of the foaming solution supply, evaluate the efficiency of means and methods for producing foam in full-scale tanks or their mock-ups, which is economically justified and ensures the results reliability.

Burnup computation for HTR-10 using MCNPX as the function of radius and fuel enrichment

The HTR-10 is a gas-cooled high-temperature reactor with spherical fuel and moderator called pebble bed and operated on 10 MW thermal power. Until now, a lot of research and development on the HTR-10 in terms of neutronic computational modeling has been carried out, one of which is burnup analysis. Fuel depletion or burnup analysis is an analysis related to fuel control and reactor output power. This analysis is needed because changes in fuel composition will affect the neutronic parameter values of a reactor. The 10 MW HTR fuel depletion study has been conducted by modeling the reactor using MCNPX (Monte Carlo N-Particle e-Xtended) to analyze the effect of radius and enrichment of reactor fuel to the left value and the burnup rate. The study is conducted by modeling a 10 MW HTR with three sorts of fuel kernel radiuses using MCNPX. First, 250 μm radius, second, 275 μm radius, third, 300 μm radius and all radiuses are variated with 10-15% fuel enrichment. TRISO particles are dispersed using simple cubic (SC) lattice in the fuel zone. The fuel balls are allocated in the reactor core along with moderator balls using a body-centered cubic. To perform all the calculations, MCNPX utilizes continuous energy data library ENDF/B-VI. From the calculation result using MCNPX can be concluded that the kernels with the radius of 275 μm and 300 μm at 14% and 13% fuel enrichment respectively were more able to maintain a critical condition within a year of operation than the kernels a 250 μm radius and the fuel with 250 μm radius has the highest burnup rate that is 52,07 GWd/MTU.

INVESTIGATION ON CORROSION PROPERTIES OF CARBON-CARBON COMPOSITES

The corrosion resistance of carbon-carbon composite materials (C–C composites) was studied in a corrosive media of coolant NaF+ZrF4 salt (a model heat-transfer) at 700 °С in the air flow. It has been shown that C–C composite material is resistant to the model heat-transfer even under conditions of critical temperature accident. The main mechanism that leads to the C–C composite corrosion is a mechanism of composite material oxidation due to the contact with the air. The study has evidenced that the C–C composite burn-up rate well correlates with the pyrocarbon matrix content in the composite, the matrix content increase by 2530% results in the composite corrosion resistance increase by a factor of 2–4. So, by developing corrosion-resistant carbon-carbon composites one has a problem of finding an optimum fiber-matrix ratio in the composite. It has been confirmed experimentally that by silication of C–C composites with the use of the methods which were developed in NSC KIPT it is possible to increase the service life of products under simulated accident conditions by a factor of 7–7.5.

Compton (prompt-response) neutron detectors: Comparison of emitter materials through the nuclear transmutation model

Reactors’ safety and efficiency are the determining factors in the modern nuclear power industry, and their required level can be achieved only by using the appropriate control and protection systems. The problem of the accurate and prompt control of energy release is especially important when the reactor is operated near its critical parameters.Currently, β-emission self-powered neutron detectors (SPNDs) are used to control the energy release field in the WWER-1000 core. For such SPNDs, the signal delay and the life-time are inconsistent with the tendency to optimize the reactor operating conditions (for example, with the desire to increase the burnup rate of nuclear fuel). That is why, in order to ensure the necessary safety and economy indicators, it is proposed to use inertialess (prompt-response; Compton) SPNDs in the In-core Instrumentation System. Cd, Co, Er, Hf and Pt are usually used as the neutron-sensitive elements of such detectors. Therefore, it is necessary to determine, based on certain criteria, which metal is the best suited for WWER-1000 conditions. Such studies are usually carried out in real conditions and are quite complex, expensive and require a lot of time. However, the same can be realized by a qualitative comparison, which is a simpler way. In this paper, it is proposed to compare the popular materials of Compton SPNDs through the Rutherford model of nuclear transformations and the ‘Bateman solution’. By considering the calculation results of the elemental composition, the ability to absorb neutrons, the activity, the signal level, and metal cost, the number of possible candidates for the role of the most suitable Compton SPND emitter material can be significantly narrowed down.

Design and Uniformity Analysis of Fully Premixed Natural Gas Burner Venturi Mixer

The venturi mixer is one of the key structures of the fully premixed surface natural gas burner. It has the function of uniformly mixing gas and air in a specific fluid space. In order to improve the burn-up rate of the combustion, and make the combustion temperature lowered to reduce the emission of NOx pollutants, a two-channel venturi mixer was designed, according to the venturi mixer performance of pressure loss and uniform. The mixer structure was analyzed by numerical simulation with the evaluation of the uniform performance parameters from the downstream following isometric characteristic cross-sectional. The results show that the venturi shrinkage angle and diffusion angle have little effect on the uniformity of mixer. The number or area of the gas injection holes is related to the uniform performance of the mixer and the pressure loss of the gas. The gas injection holes on the venturi mixer can be adjusted to balance two key parameters and it is an important factor in the design of venturi mixer structure of the fully premixed surface natural gas burner.