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Abstract
Measurements of aerosol239, 240Pu and241Am activity concentrations have been made in the vicinity of the Waste Isolation Pilot Plant (WIPP). Samples for total suspended particulate matter (TSP) and particulate matter less than or equal to 10±2 μm aerodynamic diameter (PM10) collected on 20×25-cm2 glass fiber filters at a site approximately 1 km from the WIPP exhaust shaft. Samples for both TSP and PM10 were collected concurrently at 5 m above ground level. Other concurrent PM10 samples were also collected at 2 m above ground level. At the 5-m level, approximately 50% of the mass and the239,240Pu and241Am activities in the TSP are contained in the PM10 fraction. Comparison of the PM10 data from 2-and 5-m levels indicates that239,240Pu activity concentrations at the 2-m elevation are approximately 50% higher than the activity concentrations at the 5-m elevation. The overall average of the activity ratio between241Am and239,240Pu is 0.40±0.02 which is in good agreement with other published values.
Abstract
The dynamic adsorption of Kr and Xe in activated charcoal were measured. The temperature dependence of breakthrough curves for individual isotopes of85mKr,87Kr,88Kr and135Xe have been determined from the 
-spectra at temperatures from 78 K to 291 K. The effective hold up and dynamic adsorption coefficient have been deduced. We find that adsorption is very sensitive to temperature and also depends on the size rather than on the mass of the adsorbed atom. Form total growth radioactivity, the time dependent brakthrough curves at the temperatures of 113, 195 and 220 K have been constructed. The curves were analyzed and compared with the model calculations. Fick's law describing the mass transfer of gas into porous solid was employed to obtain the adsorption coefficient from fitting the experimental data. The results show fairly good agreement between model predictions and the experiments.
Abstract
The minimum oxygen concentration (MOC) is an important safety parameter of safety for fire/explosion prevention of practical processes with fuel-air-inert mixtures. In this study, the critical fire and explosion properties stand for the explosion sensitivity (lower explosion limit (LEL), upper explosion limit (UEL)), explosion maximum indices (maximum explosion pressure (P max), maximum rate of explosion pressure rise (dP dt −1)max) and explosion damage degree (gas or vapor deflagration index (K g)/St Class). These imperative parameters of various toluene/methanol mixing solvents (100/0, 75/25, 50/50, 25/75 and 0/100 vol.%) were experimentally determined within a closed spherical vessel of 20 L (20-L-Apparatus) at 101 kPa and 150 °C. Particularly, we discussed the variations both on the above characteristics and implied flammability hazard degree within different initial oxygen circumstances; the specific effects on toluene/methanol mixing solvents were to be clarified accompanied with reducing loading oxygen concentrations, gradually approaching up to the MOC in this present work. Finally, a triangle flammability diagram with the five toluene/methanol components in our testing arrangements and conditions was established for graphically indicating the dangerous fire/explosion hazard region. It has been confirmed that this study would be very useful in relevant industrial processes for a proactive loss prevention program. The experimentally derived outcomes are recommended for the inherently safer design (ISD) for forestalling any accidents from fires and explosions.
Abstract
Knowledge of material safety properties is critical for safe handing in the chemical process industries, especially for flammable chemicals that might result in serious fires and explosions. This study investigated the flammability characteristics of methanol under working conditions during the process. The targeted fire and explosion properties, like explosion limits (UEL and LEL), vapor deflagration index (K g), maximum explosion pressure (P max), and maximum explosion pressure rise [(dP dt −1)max], were deliberately obtained via a 20-L-Apparatus in 101 kPa (i.e., 760 mmHg/1 atm), 150 and 200 °C, along with various experimental arrangements containing nitrogen (N2) or carbon dioxide (CO2) as inert component. Particularly, this study discussed and elucidated the inert influence on the above safety-related parameters by two different inerting gases of N2 and CO2. The results indicated that adding an inert component to fuel–inert gas mixtures determined the decrease of explosion range and flammability hazard degree. The results also demonstrated that CO2 possessed higher inerting capability than N2 in this study.
Abstract
IAEA reference materials (radionuclides in the marine environment) collected in areas affected by nuclear reprocessing plants and nuclear weapons tests have been analysed by semiconductor alpha-spectrometry (SAS), liquid scintillation spectrometry (LSS) and mass spectrometric techniques (high resolution ICP-MS and AMS) with the aim of developing analytical procedures and to study the geochemical behavior of plutonium in the marine environment. The Pu results obtained by SAS, ICP-MS and AMS were in reasonably good agreement (R 2 = 0.99). The mean atom ratios of 240Pu/239Pu in IAEA reference materials, IAEA-134, 135 and 381 were (0.212±0.010), (0.211±0.004) and (0.242±0.004), respectively. IAEA-384 (Fangataufa Lagoon Sediment) gave a 240Pu/239Pu mean atom ratio of 0.051±0.001. The results of 241Pu obtained by ICP-MS and LSS also show reasonable agreement (R 2 = 0.91). Pu isotopic signatures were useful in tracing Pu origin and in interpreting biogeochemical processes involving Pu in the marine environment.
Summary
A procedure is described to extend the current radiochemical method of seawater analysis for Pu and Am including Np. Short-lived 239Np tracer was prepared by separation from its 243Am parent. Irish Sea Water reference material (IAEA-381) containing known concentrations of 237Np, Pu isotopes and 241Am was used to test the procedure for small water volumes. Inductively-coupled plasma mass spectrometry (ICP-MS) was used in addition to alpha spectrometry for measurement of 237Np in the purified final Np fractions.
Abstract
A pyrochemical processing has become one of the potential technologies for a future nuclear fuel cycle. An integrated multi-physics simulation and electrotransport model of a molten-salt electrolytic process are proposed and discussed with respect to the recovery of pure uranium when using thermochemical data. This study has been performed to provide information for diffusion boundary layers between the molten salt (KCl-LiCl) and electrode. The diffusion-controlled electrochemical model demonstrate a prediction of the electrotransport behaviors of LWR spent fuel as a function of the time up to the corresponding electrotransport satisfying a given applied current based on a galvanostatic electrolysis.
Summary
It is impossible to detect 14C and 3H by direct methods such as γ-spectroscopy because they are pure b-emitters and thus they are classified as hard to measure nuclides (HTM). In this paper the analysis results of 14C and 3H in the low level radioactive wastes (LLWs), including spent ion exchange resin, evaporated bottom and sludge are presented. The LLWs were generated by three nuclear power plants (NPPs), in Korea all with pressurized water type reactors (PWRs). A simultaneous separation procedure for 14C and 3H in LLWs was established by wet oxidation-acid stripping. A liquid scintillation analyzer was used for the measurement of 14C and 3H. It was found that the recovery of 14C and 3H was 82-99 and 78-103%, respectively, by wet oxidation-acid stripping with diluted standard solutions. At the lowest injection of 14C and 3H, i.e., at 1.44 Bq for 14C and 1.22 Bq for 3H, the minimum detectable activity (MDA) of 14C and 3H was calculated as 0.88 and 0.78 Bq/g, respectively, for the minimum allowable sample weight, using wet oxidation and 16 wt% H2SO4 acid. By the wet oxidation-16 wt% H2SO4 stripping method no interfering nuclides were detected in the trapping solution of 14CO2 and the distillate of 3H. The activity concentration range of 14C in the analyzed samples, i.e., spent ion exchange resin, evaporated bottom and sludge, was 0.17-110,000, 8.4-1380 and 0.1-10,006 Bq/g, respectively, and that of 3H in the same was from no detectable to 769, 134-14,383 and 0.7-4820 Bq/g, respectively.
Data on about 27 new for South Korea species of lichen-forming and lichenicolous fungi, including one new for science genus Verseghya and 11 new for science species, i.e.: Agominia loekoesii, Lecanora pseudosambuci, Nectriopsis verseghyklarae, Polysporina golubkovae, Protoparmeliopsis zerovii, Psoroglaena chirisanensis, Pyrenopsis chejudoensis, Ropalospora chirisanensis, Thelopsis chirisanensis, Trapelia coreana, and Verseghya klarae, as well as 27 taxa newly recorded for the country (Biatora aff. subduplex, Buellia cf. uberior, Caloplaca kedrovopadensis, Catillaria chalybaea, Coenogonium isidiatum, Dibaeis yurii, Halecania australis, H. lobulata, Intralichen christiansenii, Ivanpisutia oxneri, Lecania cf. olivacella, Lecanora lojkahugoi, L. sulphurea, Lecidella mandshurica, Lichenoconium erodens, Micarea lithinella, M. aff. stipitata, Muellerella pygmaea var. pygmaea, Oxneria alfredii, Pertusaria aff. flavocorallina, Phaeosporobolus alpinum, Polycoccum innatum, Porina fluminea, Rinodina xanthophaea, Ropalospora chloantha, Stigmidium cladoniicola, and S. epiramalina) are provided.
Additional localities for the recently reported or described 39 species from South Korea, and for 1 species (Oxnerella safavidiorum) from Iran and China (for the first time for China) are provided.
The following taxa newly recorded for South Korea, i.e. Ivanpisutia oxneri, Lecanora lojkahugoi, Lecidella mandshurica, Rinodina xanthophaea, Ropalospora chloantha, as well as the newly described Buellia chujadoensis and Verseghya klarae found to be rather common in this country.
Abstract
An improved method of fission track (FT) sample preparation was developed, in which the detector of fission track and the layer containing particles are separated, in order to apply the FT-thermal ionization mass spectrometry (TIMS) for particle analysis of safeguards environmental samples. The developed FT sample enabled us to detect the particle of interest simply by observing the fission tracks. The process of particle identification was difficult due to the discrepancy between the position of the particles and fission tracks, which were observed in the conventional FT sample. The proposed method has significantly resolved this problem.
