A novel sampling system for radiocarbon measurements of atmospheric methane 

2021 ◽  
Author(s):  
Giulia Zazzeri ◽  
Xiaomei Xu ◽  
Heather Graven
Keyword(s):  
Molecular Sieves ◽  
Nuclear Power ◽  
Power Plants ◽  
Methane Emissions ◽  
Measurement Precision ◽  
Imperial College ◽  
Atmospheric Methane ◽  
Sampling System ◽  
Mass Spectrometry Facility ◽  
Better Than

<p>Radiocarbon in atmospheric methane (Δ<sup>14</sup>CH<sub>4</sub>) is a powerful tracer of fossil methane emissions and can be used to attribute methane emissions to fossil or biogenic sources. However, few Δ<sup>14</sup>CH<sub>4 </sub>measurements are reported since 2000<sup>1,2</sup>, due to challenges in sampling enough carbon for <sup>14</sup>C measurements and in assessing the influence of <sup>14</sup>C emissions from nuclear power plants on the <sup>14</sup>C observations.</p><p>At Imperial College London we addressed the sampling limitation by developing a unique sampling system that separates carbon at the point of sampling and uses small traps of molecular sieves. Collection of a sample is made by three main steps: 1) removal of CO<sub>2</sub> and CO from air, 2) combustion of CH<sub>4</sub> into CO<sub>2</sub> and 3) adsorption of the combustion-derived CO<sub>2</sub> onto the molecular sieve trap. <sup>14</sup>C analysis of our samples was carried out at the accelerator mass spectrometry facility at UCI. This novel system has been used for collection of samples in central London and has been made portable for collection of samples in different settings. </p><p>Here we describe the system and report the evaluation of the measurement uncertainty and the processing blank. We achieved a measurement precision of 6 ‰, which is similar to or better than the reported precision of the most recent observations<sup>1,3</sup>.</p><p><sup>1</sup> Townsend‐Small et al JGR 117(D7) 2012</p><p><sup>2</sup> Sparrow et al Sci. Adv 4(1) 2018</p><p><sup>3</sup> Espic et al Radiocarbon 61( 5) 2019</p>

scholarly journals Monitoring global tropospheric OH concentrations using satellite observations of atmospheric methane

2018 ◽  
Vol 18 (21) ◽  
pp. 15959-15973 ◽  
Author(s):  
Yuzhong Zhang ◽  
Daniel J. Jacob ◽  
Joannes D. Maasakkers ◽  
Melissa P. Sulprizio ◽  
Jian-Xiong Sheng ◽  
...  
Keyword(s):  
Simulation Experiment ◽  
Short Wave ◽  
Methane Emissions ◽  
Satellite Observations ◽  
Atmospheric Methane ◽  
The Past ◽  
Methyl Chloroform ◽  
Systematic Component ◽  
Observing System Simulation Experiment ◽  
Better Than

Abstract. The hydroxyl radical (OH) is the main tropospheric oxidant and the main sink for atmospheric methane. The global abundance of OH has been monitored for the past decades using atmospheric methyl chloroform (CH3CCl3) as a proxy. This method is becoming ineffective as atmospheric CH3CCl3 concentrations decline. Here we propose that satellite observations of atmospheric methane in the short-wave infrared (SWIR) and thermal infrared (TIR) can provide an alternative method for monitoring global OH concentrations. The premise is that the atmospheric signature of the methane sink from oxidation by OH is distinct from that of methane emissions. We evaluate this method in an observing system simulation experiment (OSSE) framework using synthetic SWIR and TIR satellite observations representative of the TROPOMI and CrIS instruments, respectively. The synthetic observations are interpreted with a Bayesian inverse analysis, optimizing both gridded methane emissions and global OH concentrations. The optimization is done analytically to provide complete error accounting, including error correlations between posterior emissions and OH concentrations. The potential bias caused by prior errors in the 3-D seasonal OH distribution is examined using OH fields from 12 different models in the ACCMIP archive. We find that the satellite observations of methane have the potential to constrain the global tropospheric OH concentration with a precision better than 1 % and an accuracy of about 3 % for SWIR and 7 % for TIR. The inversion can successfully separate the effects of perturbations to methane emissions and to OH concentrations. Interhemispheric differences in OH concentrations can also be successfully retrieved. Error estimates may be overoptimistic because we assume in this OSSE that errors are strictly random and have no systematic component. The availability of TROPOMI and CrIS data will soon provide an opportunity to test the method with actual observations.

Near Field Simulation of Low Level Waste Water Released from Nuclear Power Plants in Rivers through Surface by CORMIX

2013 ◽  
Vol 807-809 ◽  
pp. 113-117 ◽  
Author(s):  
Yang Yang ◽  
Yong Ye Liu ◽  
Ya Hua Qiao ◽  
Fu Dong Liu ◽  
Chun Ming Zhang ◽  
...  
Keyword(s):  
Cross Section ◽  
Concentration Distribution ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Near Field ◽  
Actual Measurement ◽  
Environmental Evaluation ◽  
Low Level ◽  
Better Than

CORMIX obtaining the approval from USEPA is widely used in the environmental evaluation of US inland nuclear power plants. Carry out 3-d simulation for the low level radioactive liquid effluent released from an inland nuclear power plant in rivers through surface by CORMIX. Compare the diluent effect of different discharge capacity (2 and 4 units) and different season (summer and winter). Dilution ratios of these four simulation conditions are all reach 10 at 500m downstream. The 0.1C0 isoconcentration line range of four units is much larger than two units. It is found from the concentration distribution of cross-section at 1km downstream that the diffusing vertically of effluent in summer is better than it in winter. The accuracy of the software will be confirmed by actual measurement.

scholarly journals Monitoring Global Tropospheric OH Concentrations using Satellite Observations of Atmospheric Methane

2018 ◽  
Author(s):  
Yuzhong Zhang ◽  
Daniel J. Jacob ◽  
Joannes D. Maasakkers ◽  
Melissa P. Sulprizio ◽  
Jian-Xiong Sheng ◽  
...  
Keyword(s):  
Methane Emissions ◽  
Satellite Observations ◽  
Atmospheric Methane ◽  
Replacement Method ◽  
Methyl Chloroform ◽  
Methane Budget ◽  
Interhemispheric Difference ◽  
Shortwave Infrared ◽  
Observing System Simulation Experiment ◽  
Better Than

Abstract. The hydroxyl radical (OH) is the main tropospheric oxidant and is the largest sink for atmospheric methane. The global abundance of OH has been monitored for the past decades with the methyl chloroform (CH3CCl3) proxy. This approach is becoming ineffective as atmospheric CH3CCl3 concentrations decline. Here we propose that satellite observations of atmospheric methane in the shortwave infrared (SWIR) and thermal infrared (TIR) can provide an effective replacement method. The premise is that the atmospheric signature of the methane sink from oxidation by OH is distinct from that of methane emissions. We evaluate this method in an observing system simulation experiment (OSSE) framework using synthetic SWIR and TIR satellite observations representative of the TROPOMI and CrIS instruments, respectively. The synthetic observations are interpreted with a Bayesian inverse analysis optimizing both gridded methane emissions and global OH concentrations with detailed error accounting, including errors in meteorological fields and in OH distributions. We find that the satellite observations can constrain the global tropospheric OH concentrations with a precision better than 1 % and an accuracy of about 3 % for SWIR and 7 % for TIR. The inversion can successfully separate contributions from methane emissions and OH concentrations to the methane budget and its trend. We also show that satellite methane observations can constrain the interhemispheric difference in OH. The main limitation to the accuracy is uncertainty in the spatial and seasonal distribution of OH.

scholarly journals 14CH4 Emissions from Nuclear Power Plants in Northwestern Europe

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 475-483 ◽  
Author(s):  
Roos Eisma ◽  
Alex T. Vermeulen ◽  
Klaas Van Der Borg
Keyword(s):  
Nuclear Power ◽  
Inverse Method ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Transport Model ◽  
Boiling Water Reactors ◽  
Sampling Station ◽  
Atmospheric Methane ◽  
Pressurized Water ◽  
Water Reactors

We measured the 14C content of atmospheric methane at a 200-m-high sampling station in The Netherlands. Combined with trajectories and a transport model, it is possible to estimate the 14CH4 emissions from nuclear power plants in northwestern Europe. We demonstrate here two different methods of analyzing the data: forward modeling and an inverse method. Our data suggest that the emissions from pressurized water reactors are 260 ± 50 GBq per GW installed power per year, ca. 1.6 ± 0.4 times higher than generally assumed. We also find that, in addition to the known nuclear sources of 14CH4 (pressurized and boiling water reactors), there are two very strong sources of 14CH4 (520 ± 200 and 1850 ± 450 GBq yr−1, respectively), probably two test reactors near the sampling station.

scholarly journals Levels of 14C in the Terrestrial Environment in the Vicinity of Two European Nuclear Power Plants

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 863-868 ◽  
Author(s):  
åsa Magnusson ◽  
Kristina Stenström ◽  
Göran Skog ◽  
Diana Adliene ◽  
Gediminas Adlys ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Specific Activity ◽  
Sampling Location ◽  
Gaseous Emissions ◽  
Terrestrial Environment ◽  
Mass Spectrometry Facility ◽  
European Nuclear

Radiocarbon is produced in all types of nuclear reactors. Most of the 14C released into the environment is in the form of gaseous emissions. Recent data on the 14C concentration found in terrestrial samples taken in the vicinity of nuclear power plants in Romania and Lithuania are presented. We found increased 14C levels in the surroundings of both power plants. At the Romanian power plant Cernavoda, we found excess levels of 14C in grass within a distance of about 1000 m, the highest 14C specific activity being 311 Bq/kg C (approximately 28% above the contemporary 14C background) found at a distance of 200 m from the point of release (nearest sampling location). At the Lithuanian power plant Ignalina, samples of willow, pine, and spruce showed a 14C excess of similar magnitude, while significantly higher values were found in moss samples. The samples were analyzed at the accelerator mass spectrometry facility in Lund, Sweden.

Perspectives of CsI:Tl Crystals in g-Spectrometers

ANRI ◽  
2021 ◽  
Vol 0 (2) ◽  
pp. 24-40
Author(s):  
Maksim Belousov ◽  
Maksim Gorbunov ◽  
Oleg Ignat'ev ◽  
Andrey Krymov ◽  
Anton Kupchinskiy ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Nuclear Power ◽  
Power Plants ◽  
Light Flash ◽  
Relative Energy ◽  
Development Work ◽  
137Cs Source ◽  
Silicon Photomultipliers ◽  
Extended Range ◽  
Better Than

The article describes the problems of creating a scintillation spectrometer with a CsI:Tl crystal to replace spectrometers with NaI:Tl crystals which are widely used at nuclear power plants (NPPs) to monitor the activity of air, waste water and adjacent territories. The advantages of CsI:Tl-spectrometers are in the best energy resolution; much greater resistance to mechanical and electromagnetic influences due to the use of silicon photomultipliers (SiPM) instead of vacuum photomultiplier tubes (VPMT); much greater durability due to the very low hygroscopicity of the material. The strong mismatch between the emission spectrum of the crystal and the spectral sensitivity of the VPMT photocathodes, the relatively long decay time and the complex, multicomponent form of the light flash made spectrometers with CsI:Tl crystals not competitive. The paper describes the methods of constructing a spectrometer, which made it possible to realize the useful properties inherent in a crystal and to level its disadvantages. As a result of the cycle of research and development work, the Stark-02 intellectual detector has been designed and described. Typical relative energy resolution with crystals of volume 45 cm3 at an energy of 662 keV of the 137Cs source is better than 6.5% in the ambient temperature range Q = +10 ÷ +45 °C and not worse than 7.5% in the extended range Q = –25 ÷ +55 °C.

Nitrogen Diffusion in the Nb-1.0wt%Zr Measured by Mechanical Spectroscopy

2008 ◽  
Vol 273-276 ◽  
pp. 261-265 ◽  
Author(s):  
Armando Cirilo Souza ◽  
Carlos Roberto Grandini ◽  
Odila Florêncio
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Technological Development ◽  
Nitrogen Diffusion ◽  
Mechanical Spectroscopy ◽  
Interstitial Diffusion ◽  
Friction Measurements ◽  
Better Than ◽  
Zr Alloy ◽  
Scientific And Technological Development

The scientific and technological development in the area of new materials contributed to several applications of niobium and its alloys in nuclear power plants as well as in aerospace, aeronautics, automobile and naval industries. This paper presents the interstitial diffusion coefficients of nitrogen in solid solution in the Nb-1.0wt%Zr alloy using internal friction measurements obtained by mechanical spectroscopy, which uses a torsion pendulum operating at an oscillation frequency between 1.0 Hz and 10.0 Hz. The temperature range varies from 300K to 700K, at a heating rate of 1 K/min and vacuum better than 2 x 10-6 Torr. The results showed an increase of the interstitial diffusion coefficient of nitrogen that was correlated with configurational considerations for the octahedral interstitials.

The Effects of Ion Implantation on the Surface Features of Inconel 600

1985 ◽  
Vol 43 ◽  
pp. 288-289
Author(s):  
John D. Rubio
Keyword(s):  
Grain Boundary ◽  
Ion Implantation ◽  
Nuclear Power ◽  
Power Plants ◽  
Surface Region ◽  
Selective Dissolution ◽  
Boundary Region ◽  
Near Surface ◽  
Inconel 600 ◽  
Steam Generator Tubing

The degradation of steam generator tubing at nuclear power plants has become an important problem for the electric utilities generating nuclear power. The material used for the tubing, Inconel 600, has been found to be succeptible to intergranular attack (IGA). IGA is the selective dissolution of material along its grain boundaries. The author believes that the sensitivity of Inconel 600 to IGA can be minimized by homogenizing the near-surface region using ion implantation. The collisions between the implanted ions and the atoms in the grain boundary region would displace the atoms and thus effectively smear the grain boundary.To determine the validity of this hypothesis, an Inconel 600 sample was implanted with 100kV N2+ ions to a dose of 1x1016 ions/cm2 and electrolytically etched in a 5% Nital solution at 5V for 20 seconds. The etched sample was then examined using a JEOL JSM25S scanning electron microscope.

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