Rate Coefficient Data Research Articles

A novel state-resolved actinometry method to determine the nitrogen atom number density in the ground state and intra-shell excited states in low-pressure electron cyclotron resonance plasmas

The active-particle number density is a key parameter for plasma material processing, space propulsion, and plasma-assisted combustion. The traditional actinometry method focuses on measuring the density of the atoms in the ground state, but there is a lack of an effective optical emission spectroscopy method to measure intra-shell excited-state densities. The latter atoms have chemical selectivity and higher energy, and they can easily change the material morphology as well as the ionization and combustion paths. In this work, we present a novel state-resolved actinometry (SRA) method, supported by a krypton line-ratio method for the electron temperature and density, to measure the number densities of nitrogen atoms in the ground and intra-shell excited states. The SRA method is based on a collisional-radiative model, considering the kinetics of atomic nitrogen and krypton including their excited states. The densities measured by our method are compared with those obtained from a dissociative model in a miniature electron cyclotron resonance (ECR) plasma source. Furthermore, the saturation effect, in which the electron density remains constant due to the microwave propagation in an ECR plasma once the power reaches a certain value, is used to verify the electron density measured by the line-ratio method. An ionization balance model is also presented to examine the measured electron temperature. All the values obtained with the different methods are in good agreement with each other, and hence a set of verified rate coefficient data used in our method can be provided. A novel concept, the ‘excited-state system’, is presented to quickly build an optical diagnostic method based on the analysis of quantum number propensity and selection rules.

Improved Quantum-Classical Treatment of N2-N2 Inelastic Collisions: Effect of the Potentials and Complete Rate Coefficient Data Sets.

In this study, complete (i.e., including all vibrational quantum numbers in an N2 vibrational ladder) data sets of vibration-to-vibration and vibration-to-translation rate coefficients for N2-N2 collisions are explicitly computed along with transport properties (shear and bulk viscosity, thermal conductivity, and self-diffusion) in the temperature range 100-9000 K. To reach this goal, we improved a mixed quantum-classical (MQC) dynamics approach by lifting the constraint of a Morse treatment of the vibrational wave function and intramolecular potential and permitting the use of more realistic and flexible representations. The new formulation has also allowed us to separately analyze the role of intra- and intermolecular potentials on the calculated rates and properties. Ab initio intramolecular potentials are indispensable for highly excited vibrational states, though the Morse potential still gives reasonable values up to v = 20. An accurate description of the long-range interaction and the van der Waals well is a requisite for the correct reproduction of qualitative and quantitative rate coefficients, particularly at low temperatures, making physically meaningful analytical representations still the best choice compared to currently available ab initio potential energy surfaces. These settings were used to directly compute the MQC rates corresponding to a large number of initial vibrational quantum numbers, and the missing intermediate values were predicted using a machine learning technique (i.e., the Gaussian process regression approach). The obtained values are reliable in the wide temperature range employed and are therefore valuable data for many communities dealing with nonlocal thermal equilibrium conditions in different environments.

Elastic and electron capture processes in slow He+–He collision

Aims. The elastic and electron-capture processes of He+ ions with ground helium atoms are very important for studies in astrophysics. It is essential to have reliable state-selective charge transfer, elastic, and transport cross-sections, along with the corresponding reaction rate coefficient data, especially for low collision energies. Methods. We investigated the elastic and non-radiative electron-capture processes in He+(1s)–He(1s2) collisions are investigated employing the full quantum-mechanical molecular orbital close-coupling method. The adopted ab initio adiabatic potentials and coupling matrix elements were obtained by a multi-reference single- and double-excitation configuration interaction approach. Results. We computed the elastic, charge-transfer, and transport cross-sections in the energy range of 0.01–2500eVamu−1 and the reaction rate coefficient in the temperature range of 10–109 K. Good agreement was achieved when compared to the available experimental and theoretical results. Shape resonance, Regge, and Glory oscillations were also found in the elastic and charge transfer cross-sections in the energy region considered here.

Experimental Determination of the Dissociative Recombination Rate Coefficient for Rotationally Cold CH+ and Its Implications for Diffuse Cloud Chemistry

Observations of CH+ are used to trace the physical properties of diffuse clouds, but this requires an accurate understanding of the underlying CH+ chemistry. Until this work, the most uncertain reaction in that chemistry was dissociative recombination (DR) of CH+. Using an electron–ion merged-beams experiment at the Cryogenic Storage Ring, we have determined the DR rate coefficient of the CH+ electronic, vibrational, and rotational ground state applicable for different diffuse cloud conditions. Our results reduce the previously unrecognized order-of-magnitude uncertainty in the CH+ DR rate coefficient to ∼20% and are applicable at all temperatures relevant to diffuse clouds, ranging from quiescent gas to gas locally heated by processes such as shocks and turbulence. Based on a simple chemical network, we find that DR can be an important destruction mechanism at temperatures relevant to quiescent gas. As the temperature increases locally, DR can continue to be important up to temperatures of ∼600 K, if there is also a corresponding increase in the electron fraction of the gas. Our new CH+ DR rate-coefficient data will increase the reliability of future studies of diffuse cloud physical properties via CH+ abundance observations.

Electron–N2 interactions in RF E × B fields

This study reports on rate coefficient data for excitation of electronic states and ionization of N2 molecules by electrons exposed to mutually perpendicular radio frequency electric and magnetic fields. These quantities were obtained by means of a Monte Carlo simulation, which provides mean electron energies and corresponding energy distributions within one oscillation of the external fields. The time-resolved mean electron energies and rate coefficients as well as their period averaged values are presented. Calculations were performed for different field frequencies, including one of the standard frequencies in the industrial use, 13.56 MHz, and for effective reduced electric field values of 300 and 500 Td, while the effective reduced magnetic field was varied up to 2000 Hx. The fundamental aspect of the obtained results is discussed, which is followed by a collection of tabular data for their eventual use in future models of inductively coupled N2 plasma sources.

On the relevance of accurate input data for vibrational kinetics in air cold plasmas: the case of nitrogen fixation

The need for green chemistry processes is currently pressing the research world to find solutions suited for a direct use of inherently intermittent renewable energy sources. However, these solutions must be also energy efficient, due to the world-size magnitude of the production that has to be substituted in the near future. One of the top problems in this sense is the nitrogen fixation, responsible for at least 40% of world food production by the synthesis of fertilisers. Using air plasmas for this process is an old idea dating back to the first years of 1900, then rapidly substituted by other processes more economically but much less ecologically sustainable. Reaching a balance between these two aspects of a realistic sustainability using non-equilibrium plasmas is the present challenge. Chemical kinetics modelling including vibrational kinetics of heavy species is key in this sense, because it allows to experiment possible solutions in a much easier way than in the laboratory, provided the model is sufficiently complete and based on accurate input data, in order to smoothly reproduce the available experimental findings. The present paper is focussed on the state-of-the-art of some heavy-particle processes crucial in air plasmas in general and for nitrogen fixation in particular, including new specific rate coefficient data, on their comparisons with well-known data largely used in models and on their possible improvements in the near future.

Single-pulse shock-tube study on the pyrolysis of small esters (ethyl and propyl propanoate, isopropyl acetate) and methyl isopropyl carbonate

Single-pulse shock-tube experiments were used to study the thermal decomposition of selected oxygenated hydrocarbons: Ethyl propanoate (C2H5OC(O)C2H5; EP), propyl propanoate (C3H7OC(O)C2H5; PP), isopropyl acetate ((CH3)2HCOC(O)CH3; IPA), and methyl isopropyl carbonate ((CH3)2HCOC(O)OCH3; MIC) The consumption of reactants and the formation of stable products such as C2H4 and C3H6 were measured with gas chromatography/mass spectrometry (GC/MS). Depending on the considered reactant, the temperatures range from 716–1102 K at pressures between 1.5 and 2.0 bar. Rate-coefficient data were obtained from first-order analysis. All reactants primarily decompose by six-center eliminations: EP → C2H4 + C2H5COOH (propionic acid); PP → C3H6 + C2H5COOH; IPA → C3H6 + CH3COOH (acetic acid); MIC → C3H6 + CH3OC(O)OH (methoxy formic acid). Experimental rate-coefficient data can be well represented by the following Arrhenius expressions: k(EP → products) = 1013.49±0.16 exp(−214.95±3.25 kJ/mol/RT) s−1; k(PP → products) = 1012.21±0.16 exp(–191.21±2.79 kJ/mol/RT) s−1; k(IPA → products) = 1013.10±0.31 exp(–186.38±5.10 kJ/mol/RT) s−1; k(MIC → products) = 1012.43±0.29 exp(–165.25±4.46 kJ/mol/RT) s−1. The determination of rate coefficients was based on the amount of C2H4 or C3H6 formed. The potential energy surface (PES) of the thermal decomposition of these four reactants was determined with the G4 composite method. A master-equation analysis was conducted based on energies and molecular properties from the G4 computations. The results indicate that the length of a linear alkyl substituent does not significantly influence the rate of six-center eliminations, whereas the change from a linear to a branched alkyl substituent results in a significant reactivity increase. The comparison between rate-coefficient data also shows that alkyl carbonates have higher reactivity towards decomposition by six-center elimination than esters. The results are discussed in in the context of reactivity patterns of carbonyl compounds.

Selected Ion Flow Tube – Mass Spectrometry (SIFT-MS) study of the reactions of H3O+, NO+ and O2+ with a range of oxygenated volatile organic carbons (OVOCs)

Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS) uses soft chemical ionisation, typically by H3O+, NO+ and O2+, to analyse trace gases in real time at mixing ratios down to low parts per trillion by volume (pptv) and has recently been demonstrated as an effective method for monitoring volatile organic compounds (VOCs) in the atmosphere. SIFT-MS analysis requires accurate rate coefficient and product ion branching ratio data to allow for accurate mixing ratio calculations without the need for calibration standards. Most rate constant data have been measured using helium as the carrier gas. Here we report rate constants of a number of oxygenated volatile organic compounds (OVOCs) alongside benzene for H3O+, NO+ and O2+ reagent ions in nitrogen carrier gas, using a permeation tube calibration source and a certified gas standard to introduce known concentrations into the SIFT-MS. This includes the first reported literature rate constant for nonanal using SIFT-MS. We found that the rate constants for most compounds measured in nitrogen carrier gas were similar to those measured in helium. However, the NO+ rate constants for ketones measured in nitrogen were 1.2–5 times lower than those measured in helium. We observe higher fragmentation due to changes made to the lens voltages of the instrument in order to tune for higher sensitivity, altering the reagent ion energies. We also show the impact of increasing the flow tube temperature and voltage on the sensitivity and ionisation of benzene, butanone and butanal under both dry and humid conditions. Some of the SIFT-MS compound library entries are data from historic SIFT-MS instruments that lacked a heated flow tube, and therefore suffered from higher water clustering than current commercial SIFT-MS models. We show that a higher flow tube temperature reduces the amount of water adduct formation thereby simplifying compound concentration determination. These results demonstrate the need to ensure that the library data used are acquired under the same conditions as the experiment being performed.

Features and aspects of radioactive flow and slippage velocity on rotating two-phase Prandtl nanofluid with zero mass fluxing and convective constraints

The communication aims to analyze the conduct of rotating Prandtl nanofluid with the inclusion of effects like MHD, variable species diffusivity, nonlinear warm radiation, convective limit conditions, velocity slip and chemical reaction on fluid moving along a stretchable surface. Buongiorno model is implemented in orde to catch the Brownian movement and thermophoresis impacts by the presence of nanofluids. The effect of viscous dissemination and Joule heating is used in the current review. Using suitable similarity variables, the governing differential conditions with respect to momentum, energy, and concentration are improved into customary, ordinary differential equations and these equations numerically with the shooting technique. The ranges of different dimensionless parameters used in our study are Prandtl fluid parameter 0 ≤ α ≤ 3.5, elastic parameter 1 ≤ β ≤ 7, thermal radiation 1 ≤ Rd ≤ 2, temperature ratio parameter 1 ≤ θw ≤ 1.6, Eckart number 0.3 ≤ Ec ≤ 0.7, velocity slip parameter 0 ≤ γ1 ≤ 1, thermophoresis parameter 0.1 ≤ Nt ≤ 4, Brownian motion parameter 0.1 ≤ Nb ≤ 1.5, Prandtl number 1.7 ≤ Pr ≤ −2.6, magnetic parameter 0.1 ≤ M ≤ 0.8, chemical reaction parameter 0.2 ≤ δ ≤ 1, convection parameter 0.3 ≤ γ2 ≤ 1.1, rotational parameter 0.1 ≤ λ ≤ 0.7, Schmidt number 0.1 ≤ Sc ≤ 0.7, variable species diffusivity 0.1 ≤ ϵ ≤ 0.5 which shows up during mathematical arrangement are shown as tables and charts. These results are enhanced with the data for the heat transfer rate and skin friction coefficients. It is seen that the temperature profile enhanced on account of an increase in temperature convection boundary and mass fraction field raises due to an improvement in species diffusivity parameter.

Update and critical reanalysis of IUPAC benchmark propagation rate coefficient data

The dataset used to generate IUPAC benchmark Arrhenius parameters for propagation rate coefficients in radical polymerization is extended and reanalyzed, taking into account systematic interlaboratory variation.

Direct rate-constant measurements and theoretical insight into the mechanism of the reactions H + hexamethyldisiloxane and H + tetramethyldisiloxane*

ABSTRACT Shock-tube experiments were conducted to determine rate-coefficient data of the H-atom abstraction reactions H + HMDSO (hexamethyldisiloxane) → H2 + HMDSO−H and H + TMDSO (tetramethyldisiloxane) → H2 + TMDSO−H. The experiments comprised a temperature range of 1109–1240 K and pressures between 1.2 and 1.5 bar. In all experiments, C2H5I was used as a precursor for H atoms. H-atom concentrations were measured with atomic resonance absorption spectrometry (ARAS) and rate-coefficient data were obtained from pseudo-first-order analysis of temporal H-atom concentration profiles. Experimental total rate-coefficients were well represented by the following Arrhenius equations: k total,HMDSO(T) = 10−9.49±0.36 exp(−32.4 ± 8.1 kJmol−1/RT) cm3molecule−1s−1 for H + HMDSO and k total,TMDSO(T) = 10−8.00±0.36 exp(−53.3 ± 7.9 kJ mol−1/RT) cm3molecule−1s−1 for H + TMDSO. Multiple reaction channels were explored by computations at G4//B3lyp-D3BJ level of theory.

NIFS Atomic and Molecular Numerical Database for Collision Processes

The National Institute for Fusion Science (NIFS) has compiled and developed atomic and molecular numerical databases for various collision processes and makes it accessible from the internet to the public. The database contains numerical data of cross sections and rate coefficients for electron collision or ion collisions with atoms and molecules, attached with bibliographic information on their data sources. The database system provides query forms to search data, and numerical data are retrievable. The graphical output is helpful to understand energy dependence of cross sections and temperature dependence of rate coefficients obtained by various studies. All data are compiled mainly from published literature, and data sources can be tracked by the bibliographic information. We also have data of sputtering yields and back-scattering coefficients for solid surfaces collided by ions in the database. All data in the database are applicable to understand atomic and molecular processes in various plasmas, such as fusion plasma, astrophysical plasma and applied plasma, as well as for understanding plasma–surface interaction in plasmas.

Ab initio calculation of the proton transfer reaction rate coefficients to volatile organic compounds related to cork taint in wine.

We compute the proton transfer rates to a range of volatile organic compounds (VOCs) related to cork taint in wine. These rates are useful to support quantification in proton-transfer-reaction mass spectrometry (PTR-MS) and in selected-ion flow-tube mass spectrometry (SIFT-MS). We apply the average dipole orientation theory and the parameterized trajectory method to evaluate the rate coefficients for proton transfer occurring in ion-molecule collision, from both H3 O+ and NH to the VOCs. The main input ingredients for these methods are the electric dipole moment and polarizability of the VOC molecules, which we evaluate by means of quantum chemical calculations based on density functional theory. We provide new data for proton transfer rate coefficients of compounds responsible for cork taint and off-flavor in wine such as chloroanisoles, bromoanisoles, methylisoborneol, guaiacol, and terpenes.

Release behavior of radionuclides from MOX fuels irradiated in a fast reactor during heating tests

In order to obtain the release rate coefficients from fuels for fast reactors (FRs), heating tests and the subsequent analyses of the fission products (FPs) and actinides that are released were carried out using samples of uranium-plutonium mixed oxide (MOX) fuel pellets irradiated at the experimental fast reactor Joyo. Three heating tests targeting temperatures of 2773, 2973 and 3173 K were conducted using an FP release behavior test apparatus equipped with a high-frequency induction furnace and solid FP sampling systems consisting of a thermal gradient tube (TGT) and filters. Irradiated fuel pellets were placed into a tungsten crucible, then loaded into the induction furnace. The temperature was raised continuously at a heating rate of 10 K/s to the targeted temperature and maintained for 500 s in a flowing argon gas atmosphere. The FPs and actinides released from the MOX fuels and deposited in the TGT and filters were quantified by gamma-ray spectrometry and inductively coupled plasma mass spectrometry analysis. Based on the analysis, the release rates of radionuclides from MOX fuels for FRs were obtained and compared with literature data for light water reactor (LWR) fuels. The release rate coefficients of FPs obtained in this study were found to be similar to or lower than the literature values for LWR fuels. It was also found that the release rate coefficient data for actinides were within the range of variation of literature values for LWR fuels.

Numerical estimation of the oxygen impurity transport in the Aditya tokamak

The present study illustrates an approach to solving the one-dimensional impurity transport equation in tokamak plasma, without the loss of generality, using a semi-implicit numerical method. The radial profiles of number density distribution of different ionization states of oxygen (Z = 1 to Z = 8) have been estimated using the ionization and recombination rate coefficient data from the Atomic Data and Analysis Structure database. The rate coefficients are determined based on the electron temperature and number density distribution in the Aditya tokamak. The radial number density profile of the O4+ ion, obtained using the semi-implicit impurity transport equation, has been applied further in determining the radial emissivity profiles of the characteristic 650.024 nm transition of the Be-like O4+ ion. The simulated O4+ emissivity is then matched with respect to the experimental emissivity values along inboard (high toroidal magnetic field) and outboard (low toroidal magnetic field) regions of the Aditya tokamak. The comparison estimates the nature of the radial diffusivity profile of oxygen ions, which in turn demonstrates the nature of oxygen transport in Aditya plasma. Large values of oxygen ion diffusivity (> neo-classical values) are observed toward the plasma edge in both regions of the Aditya tokamak. These diffusivity values point toward a fluctuation induced transport in the edge region of Aditya plasma. The simulated results are benchmarked with the STRAHL code. The semi-implicit form of the radial impurity transport equation can be extended to deduce the distributions of other light impurities in tokamak plasma.

Estimation of External Contamination and Exposure Rates Due to Fission Product Release

In the event of a radiological incident, the release of fission products into the surrounding environment and the ensuing external contamination present a challenge for triage assessment by emergency response personnel. Reference exposure rate and skin dose rate calibration data for emergency response personnel are currently lacking for cases where receptors are externally contaminated with fission products. Simulations were conducted to compute reference exposure rate coefficients and skin dose rate coefficients from photon-emitting fission products of radiological concern. To accomplish this task, simplified mathematical skin phantoms were created using surface area and height specifications from International Commission on Radiological Protection Publication 89. Simulations were conducted using Monte Carlo radiation transport code using newborn, 1-y-old, 5-y-old, 10-y-old, 15-y-old, and adult phantoms for 22 photon-emitting radionuclides. Exposure rate coefficient data were employed in a case study simulating the radionuclide inventory for a 17 × 17 Westinghouse pressurized water reactor, following three burn-up cycles at 14,600 MWd per metric ton of uranium. The decay times following the final cycle represent the relative activity fractions over a period of 0.5-30 d. The resulting data can be used as calibration standards for triage efforts in emergency response protocols.

A xenon collisional-radiative model applicable to electric propulsion devices: II. Kinetics of the 6s, 6p, and 5d states of atoms and ions in Hall thrusters

Electric propulsion devices of using xenon propellant are nowadays widely adopted for the space missions. A collisional-radiative (CR) model of xenon needs to be developed to understand the kinetic mechanisms of the excited and energetic species in these devices and also to support their optical diagnostics. Previously, due to limitations in the fundamental cross section data, Xe CR models focused on the atomic species; the ionic species, which also play important roles for the thrusters, were not studied in detail. In our previous paper, a fully relativistic Dirac B-spline R-matrix method was applied to calculate the relevant cross sections for electron collisions with the Xe+ ion. Based on these data, a comprehensive CR model—with the kinetics of metastable and excited levels of both Xe and Xe+ included—could be built. The calculated density distributions of atomic and ionic levels are examined by optical measurements in Hall thrusters in all of the four typical regions (near-anode-, ionization-, acceleration-, and plume-region). The special kinetic behaviors of the excited species are analyzed, and a set of rate coefficient data used for the Xe CR model is also provided.

Organ and detriment-weighted dose rate coefficients for exposure to radionuclide-contaminated soil considering body morphometries that differ from reference conditions: adults and children.

The system of protection established by the International Commission on Radiological Protection (ICRP) provides a robust framework for ionizing radiation exposure justification, optimization, and dose limitation. The system is built upon fundamental concepts of a reference person, defined in ICRP Publication 89, and the radiation protection quantity effective dose, defined in ICRP Publication 103. For external exposures to radionuclide-contaminated soil, values of the organ dose rate coefficient (Gy/s per Bq/m2) and effective dose rate coefficient (Sv/s per Bq/m2) have been computed by several authors and national laboratories using ICRP-compliant reference phantoms-both stylized and voxelized. These coefficients are of great value in post-accident exposure assessments as seen in Japan following the 2011 Fukushima Daiichi nuclear power station disaster. Questions arise, however, among the general public regarding the accuracy of organ and effective dose estimates based upon reference phantom methodologies, especially for those individuals with height and/or total body mass that differ modestly or even substantially from the nearest age-matched reference person. In this pilot study, this issue is explored through use of the extended 351-member UF/NCI hybrid phantom library in which values of organ and detriment-weighted dose rate coefficients are computed for sex/height/mass-specific phantoms, and systematically compared to their values of the effective dose rate coefficient computed using corresponding reference phantoms. Results are given for monoenergetic photons, and then for some 33 different radionuclides, with all dose rate coefficient data provided in a series of electronic annexes. For environmentally relevant radionuclides such as 89Sr, 90Sr, 137Cs, and 131I, percent differences between the detriment-weighted dose rate coefficient computed using non-reference and the effective dose rate coefficient computed using reference phantoms vary only ± 5% for young children approximated by the reference 1-year-old phantom. With increased body size and age, the range of percent differences in these two quantities increases to +7% to -14% for the reference 5-year-old, to +10% to -27% for the reference 10-year-old, to +33% to -31% for the reference 15-year-old, and to +15% to -40% for male and female adults.

Investigation of the plasma parameters of a laboratory argon plasma source using a collisional radiative model with the comparison of experimental and simulated spectra

Plasma spectroscopy is a common method for diagnosing the radiative behaviour and predicting the key properties of a plasma. Plasma spectroscopy may be merged with plasma modelling and simulation to perform numerical diagnostics. A new Collisional Radiative (CR) model is developed for argon plasma at low temperature and low pressure. In the developed model, rather than grouping the energy levels into lumped sets, all the energy levels up to a maximum level were modeled for both the argon neutrals and the argon single ions. With the gathered data of collisional and radiative rate coefficients from LANL (Los Alamos National Laboratory) and NIST (National Institute of Standards and Technology), this model calculates the time-varying population densities of 101 atomic and 222 ionic energy levels. The model considers the emissions of 146 Ar-I lines (in 86.68–2397.3 nm range) and 303 Ar-II lines (in 71.8–6985.3 nm range), and gives the simulated spectra over the optical and near-optical region. The simulated radiation emission spectra were then compared with the measured spectra of a laboratory helicon plasma source for the prediction of the plasma parameters such as electron temperature and electron density.

Modeling of CO2 plasma: effect of uncertainties in the plasma chemistry

Low-temperature plasma chemical kinetic models are particularly important to the plasma community. These models typically require dozens of inputs, especially rate coefficients. The latter are not always precisely known and it is not surprising that the error on the rate coefficient data can propagate to the model output. In this paper, we present a model that uses N = 400 different combinations of rate coefficients based on the uncertainty attributed to each rate coefficient, giving a good estimation of the uncertainty on the model output due to the rate coefficients. We demonstrate that the uncertainty varies a lot with the conditions and the type of output. Relatively low uncertainties (about 15%) are found for electron density and temperature, while the uncertainty can reach more than an order of magnitude for the population of the vibrational levels in some cases and it can rise up to 100% for the CO2 conversion. The reactions that are mostly responsible for the largest uncertainties are identified. We show that the conditions of pressure, gas temperature and power density have a great effect on the uncertainty and on which reactions lead to this uncertainty. In all the cases tested here, while the absolute values may suffer from large uncertainties, the trends observed in previous modeling work are still valid. Finally, in accordance with the work of Turner, a number of ‘good practices’ is recommended.