International Atomic Energy Association Research Articles

Electrolytic Process for Concentrating Trace Tritium in Water for Tritium Activity Measurement by Liquid Scintillation Counter

In arid regions, the water contains very low levels of tritium, which cannot be detected by conventional liquid scintillation counters (LSC). For the evaluation of the tritium activity concentration, it is crucial to enrich the low-level tritium of groundwater with a known factor. To address this, we developed an electrolysis process with specially designed electrolytic cells following the guidelines of the International Atomic Energy Association (IAEA). The electrolysis process enriched nine spiked samples with known quantities of tritium, and the tritium activity concentration was measured by a scintillation counter. The enriched water showed comparable activity levels to the spiked samples. In addition, the enrichment factor and tritium activity are correlated. Our study demonstrated that the electrolysis process with fabricated electrolytic cells could achieve an enrichment factor of approximately ten to forty times the initial tritium concentration. The simple design and fabrication of the electrolysis process and its ability to control various parameters make it cost-effective for measuring low-level tritium using a conventional LSC.

Development of a polystyrene phantom for quality assurance of a Gamma Knife®

A polystyrene phantom was developed following the guidance of the International Atomic Energy Association (IAEA) for gamma knife (GK) quality assurance. Its performance was assessed by measuring the absorbed dose rate to water and dose distributions. The phantom was made of polystyrene, which has an electron density (1.0156) similar to that of water. The phantom included one outer phantom and four inner phantoms. Two inner phantoms held PTW T31010 and Exradin A16 ion chambers. One inner phantom held a film in the XY plane of the Leksell coordinate system, and another inner phantom held a film in the YZ or ZX planes. The absorbed dose rate to water and beam profiles of the machine-specific reference (msr) field, namely, the 16 mm collimator field of a GK Perfexion™ or Icon™, were measured at seven GK sites. The measured results were compared to those of an IAEA-recommended solid water (SW) phantom. The radius of the polystyrene phantom was determined to be 7.88 cm by converting the electron density of the plastic, considering a water depth of 8 g/cm2. The absorbed dose rates to water measured in both phantoms differed from the treatment planning program by less than 1.1%. Before msr correction, the PTW T31010 dose rates (PTW Freiberg GmbH, New York, NY, USA) in the polystyrene phantom were 0.70 (0.29)% higher on average than those in the SW phantom. The Exradin A16 (Standard Imaging, Middleton, WI, USA) dose rates were 0.76 (0.32)% higher in the polystyrene phantom. After msr correction factors were applied, there were no statistically significant differences in the A16 dose rates measured in the two phantoms; however, the T31010 dose rates were 0.72 (0.29)% higher in the polystyrene phantom. When the full widths at half maximum and penumbras of the msr field were compared, no significant differences between the two phantoms were observed, except for the penumbra in the Y-axis. However, the difference in the penumbra was smaller than variations among different sites. A polystyrene phantom developed for gamma knife dosimetry showed dosimetric performance comparable to that of a commercial SW phantom. In addition to its cost effectiveness, the polystyrene phantom removes air space around the detector. Additional simulations of the msr correction factors of the polystyrene phantom should be performed.

Legal Aspect of Uranium Mining in India: Issues and Concerns

A large number of nuclear energy power plants being set up across India with 22 nuclear power plants working produce 2.8% of the total electricity generated across the country. Also, there are 6 under construction and 31 under a proposal for construction have the basic fuel requirement as the radioactive minerals like uranium isotopes, plutonium, and thorium. The demand for the fuel is going to increase with time and there is a need to either import or to excavate out the ores of radioactive substances like the Uraninite ore deposits found across the states of Jharkhand, Telangana, Meghalaya, etc. that fulfill the requirement. The ore is excavated out by the Uranium Corporation of India Limited which is controlled by the Department of Atomic Energy and the mining and processing of the same is regulated by the Atomic Energy Act 1962. In the research paper, the author has acknowledged the issue of contradiction between the mining grants given to Uranium Corporation of India Limited (UCIL) under the Atomic Energy Act, 1962 and the environment protection laws like Wildlife Protection Act, 1972 which declared the area as restricted area for any human activity. The scope of powers given to UCIL under the Atomic Energy Act, 1962 for the mining of uranium and the restrictions that can be put on the same by the Forest (Conservation) Act, 1980 is also critically analyzed. India's ratification of the International Atomic Energy Association's Additional protocols and the UCIL's way of dealing with the sustainable goal of IAEA, in line with its Atoms for peace and development set out in the United Nations Agenda (2030) for Sustainable Development is also examined. In its conclusion, the author has said that there was a violation of the Article 19 (1) (d) and (e) and Article 21 in the Jaduguda mining project and non-compliance with the procedures mentioned under the various environmental laws in the uranium mining projects in Nalgonda like Environment Protection Strategy (EPS) 2002, Wildlife (Protection) Amendment Act 2006 and Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act 2006. It is also concluded that the best stand of government could be to import uranium from the other nations by complying with the IAEA guidelines and by bilateral treaties like the Indo-US nuclear deal of 2007 thus surpassing the restrictions placed on the country for not being the signatory to the Non-Proliferation Treaty (NPT) and not being the member of Nuclear Suppliers Group (NSG).

Emergent Stateness: Critical Urban Geopolitics in Slavutych

The city of Slavutych was built specifically to house the workers who would continue to work post-disaster at the Chornobyl Nuclear Power Plant (ChNPP) and their families. It was the pinnacle of Soviet planned cities, the culmination of decades of lessons learned from similar projects, and the architectural embodiment of Soviet multinationalism. However, in spite of all the excitement the new city elicited, within just a few years the now-independent Ukrainian government, under pressure from international organizations like the International Atomic Energy Association and the United Nations, established a hard expiration date for the shutdown of all ChNPP reactors, which in turn would mean economic devastation for Slavutych and render its existence wholly unnecessary. Rather than wait for the inevitable, city leaders and residents leveraged global and national interest in the Chornobyl disaster and its aftermath, drawing investments from multinational corporations, international organizations, and states to keep the city alive. Their scattergun approach to economic diversification and pre-emptive urban revitalization paid off, as Slavutych thrived even as the rest of Ukraine suffered major economic and demographic crises. This paper examines how Slavutych citizens were able to forge, and then to act upon, geopolitical relationships to mitigate the lingering social, political, and economic effects of the Chornobyl disaster in the city.

Why we need a centralized repository for isotopic data

Organizational structure for the proposed IsoBank. A central executive group would oversee four subcommittees (SC): Information technology, integrative disciplinary, education and training, and analytical expertise. GNIP, Global Network of Isotopes in Precipitation; IAEA, International Atomic Energy Association; QA/QC, quality assurance/quality control.

The voice of the most vulnerable: lessons from the nuclear crisis in Fukushima, Japan

The voice of the most vulnerable: lessons from the nuclear crisis in Fukushima, Japan

Lessons learned from radiation disasters

The triple catastrophe that began in Japan on March 11, 2011 was unprecedented. In the wake of the devastating earthquake and tsunami, the Fukushima Daiichi nuclear power plant crisis deteriorated to a Level 7 nuclear accident, the most severe level reserved by the International Atomic Energy Association for accidents involving significant re- leases of radioactive material having the potential for extensive environmental contamination and health consequences. The evacuation zone encompassed 50,000 people living within 20 km of the facility. However, as occurred after the Chernobyl accident, additional communities with high levels of contamination were subsequently identified and evacuated.

Distinguishing Sources of Ground Water Recharge by Using δ2H and δ18O

Stable isotope values of hydrogen and oxygen from precipitation and ground water samples were compared by using a volumetrically based mixing equation and stable isotope gradient to estimate the season and location of recharge in four basins. Stable isotopes were sampled at 11 precipitation sites of differing elevation during a 2-year period to quantify seasonal stable isotope contributions as a function of elevation. Supplemental stable isotope data collected by the International Atomic Energy Association during a 14-year period were used to reduce annual variability of the mean seasonal stable isotope data. The stable isotope elevation relationships and local precipitation elevation relationships were combined by using a digital elevation model to calculate the total volumetric contribution of water and stable isotope values as a function of elevation within the basins. The results of these precipitation calculations were compared to measured ground water stable isotope values at the major discharge points near the terminus of the basins. Volumetric precipitation contributions to recharge were adjusted to isolate contributing elevations. This procedure provides an improved representation of recharge contributions within the basins over conventional stable isotope methods. Stable isotope values from wells and springs at the terminus of each basin were used to infer the elevations of precipitation important for recharge of the regional ground water flow system. Ancillary climatic, geologic, and stable isotope values were used to further constrain the location where precipitation is entering the ground water flow system.

Recent progress toward high performance above the Greenwald density limit in impurity seeded discharges in limiter and divertor tokamaks

An overview is given of recent advances toward the realization of high density, high confinement plasmas with radiating mantles in limiter and divertor tokamaks worldwide. Radiatively improved mode discharges on the Torus Experiment for Technology Oriented Research 94 (TEXTOR-94) [Proceedings of the 16th IEEE Symposium on Fusion Engineering, 1995 (Institute for Electrical and Electronics Engineers, Piscataway, NJ, 1995), p. 470] have recently been obtained at trans-Greenwald densities (up to n̄/nGW=1.4) with high confinement mode free of edge localized modes (ELM-free H-mode) confinement quality. Experiments in DIII-D [J. Luxon et al., Proceedings of the 11th IAEA Conference on Plasma Physics and Controlled Nuclear Fusion Research (International Atomic Energy Association, Vienna, 1987), Vol. 1, p. 159] divertor plasmas with a low confinement mode edge have confirmed the dramatic changes in confinement observed with impurity seeding on TEXTOR-94. Recent experiment with impurity seeding on the Joint European Torus [Rebut et al., Fusion Eng. Des. 22, 7 (1993)], and the Japanese Atomic Energy Research Institute Tokamak 60 Upgrade [Horiike et al., Fusion Eng. Des. 16, 285 (1991); Hosogane et al., Proceedings of the 16th IAEA Conference on Plasma Physics and Controlled Nuclear Fusion Research Montreal, 1987 (International Atomic Energy Association, Vienna, 1987), Vol. 3, p. 555] have extended high confinement in ELMy H-mode plasmas to higher densities. Finally, recent progress in the physical understanding of radiating mantle plasmas is summarized.

Use of NADP archive samples to determine the isotope composition of precipitation: characterizing the meteoric input function for use in ground water studies.

Stable oxygen and hydrogen isotopes have been used in ground water studies to investigate recharge, mixing, ground water/surface water interaction, advective-diffusive transport, paleohydrogeologic interactions and to estimate ground water ages. Such studies require that the isotopic composition of precipitation be known, as precipitation is a major input to ground water and surface water systems. As oxygen-18 and deuterium data for precipitation are lacking across much of the United States, there is need to establish additional local meteoric water lines as isotope input functions across the region, as well as to develop better understanding of the isotopic climate linkages that control oxygen and hydrogen isotope ratios in precipitation. In the absence of long-term monitoring stations, one possible solution to this problem is to determine the delta 18O and delta 2H values of precipitation using archive samples collected at monitoring stations managed by the National Atmospheric Deposition Program (NADP). This study describes and interprets the seasonal delta 18O and delta 2H composition of archived precipitation samples collected in eastern Nebraska near the town of Mead during the years 1992-1994. Values for delta 18O range from -23.6 to -0.7@1000. Values for delta 2H range from -172 to 0@1000. Yearly arithmetic mean delta 18O and delta 2H values for the Mead station are -8.1@1000 and -53@1000, respectively. Weighted yearly means for delta 18O and delta 2H were -7.4@1000 and -48@1000, respectively. Mead values show a strong isotopic enrichment between winter and summer precipitation, and a strong delta 18O-T correlation (r2 = 0.91) for mean monthly values of about 0.5@1000 per degree Celsius. The local meteoric water line for the Mead site is delta 2H = 7.40 delta 18O + 7.32. Deuterium excess values suggest that most of the moisture across the region is derived primarily from a Gulf of Mexico source. The results of this study demonstrate that in the absence of long-term monitoring stations such as those operated globally by the International Atomic Energy Association, NADP archive samples can be used to determine the isotopic composition of precipitation, to characterize the local meteoric water line and establish the various climatic relationships, and define the meteoric input function for use in ground water studies.

An Instrumental Correction for the Determination of Mercury in Biological and Sediment Samples Using Cold Vapor Atomic Absorption Spectrophotometry

Low recovery rate and inconsistent measurements were found in the determination of mercury by method of cold vapor atomic absorption spectrophotometry using the hydride formation system (Hitachi HFS-2, Hitachi Ltd., Tokyo). To overcome this problem of insufficient reaction time we developed a simple T-joint device attaching to the commercial HFS-2 system for the determination of mercury in various biological tissues and sediment samples. The T-joint device was designed to combine sample and reductant injection which increased the reaction time of the sample allowing a complete formation of mercury vapor and speeding up the analysis process in comparison to the traditional cold vapor atomic absorption spectrometric method. Recoveries of mercury were in the range 95% - 100%. The corrected procedure gave precise and accurate readings with several certified reference materials: NIES No. 2 from the Japan Environment Agency; IAEA-356 from the International Atomic Energy Association, and DOLT-2, DORM-2, TORT-2, PACS-1 and MESS-2 from the National Research Council of Canada. Simple acid digestion methods were developed based on the sample Hg level and the nature of the sample. The sample detection limits were 0.0125 μg g−1 fresh weight and 0.0625 μg g−1 dry weight for biological samples, and as low as 0.0125 μg g−1 dry weight for sediment samples. These analytical protocols we established met the general requirements in environmental research and monitoring of mercury pollution.

On‐line quantitative determination of 2H/1H isotope ratios in organic and water samples using an elemental analyser coupled to an isotope ratio mass spectrometer

A rapid continuous-flow technique for the quantitative determination of hydrogen isotope ratios in organic materials and water, at natural abundance levels, is described. Samples are pyrolysed in a helium stream at 1080°C over an inert form of carbon. Hydrogen is separated from the other pyrolysis gases by gas chromatography and enters the ion source of the isotope ratio mass spectrometer (IRMS) via a crimp. The 2H/1H ratio of the gas was determined by the simultaneous integration of the m/z 2 (1H1H) and m/z 3 (2H‰1H) ion beams over time. δ2H‰ values of organic and water samples were determined by comparison with organic and water standards, respectively. The precision of the on-line δ2H‰ measurement is <3.3‰. The accuracy of the method was demonstrated by the analysis of a laboratory standard water (NTW), a European Community Bureau Reference material, N,N-tetramethylurea (TMU) and an International Atomic Energy Association polyethylene reference material (IAEA-CH-7). The measured values were NTW -39.4‰, TMU -144.1‰ and IAEA-CH-7 -100.7‰ (reference values are NTW -38.5‰, TMU -147.4‰ and IAEA-CH-7 -100.3‰). No apparent memory effect was observed when measuring samples at the natural abundance level. Calibration of organic measurements with water reference materials did not give satisfactory results, probably owing to differences in their respective pyrolysis pathways. The potential of the technique for food analysis was demonstrated by measuring the δ2H‰ values of vanillin samples derived from natural and synthetic sources and by the analyses of hexamethylenetetramine synthesized from beet, cane and apple juice sugars. © Crown copyright 1998. Reproduced with the permission of the Controller of Her Majesty’s Stationery Office.

On-line quantitative determination of2H/1H isotope ratios in organic and water samples using an elemental analyser coupled to an isotope ratio mass spectrometer

A rapid continuous-flow technique for the quantitative determination of hydrogen isotope ratios in organic materials and water, at natural abundance levels, is described. Samples are pyrolysed in a helium stream at 1080°C over an inert form of carbon. Hydrogen is separated from the other pyrolysis gases by gas chromatography and enters the ion source of the isotope ratio mass spectrometer (IRMS) via a crimp. The 2 H/ 1 H ratio of the gas was determined by the simultaneous integration of the m/z 2 ( 1 H 1 H) and m/z 3 ( 2 H‰ 1 H) ion beams over time. δ 2 H‰ values of organic and water samples were determined by comparison with organic and water standards, respectively. The precision of the on-line δ 2 H‰ measurement is <3.3‰. The accuracy of the method was demonstrated by the analysis of a laboratory standard water (NTW), a European Community Bureau Reference material, N,N-tetramethylurea (TMU) and an International Atomic Energy Association polyethylene reference material (IAEA-CH-7). The measured values were NTW -39.4‰, TMU - 144.1‰ and IAEA-CH-7 - 100.7‰ (reference values are NTW -38.5‰, TMU - 147.4‰ and IAEA-CH-7 - 100.3‰). No apparent memory effect was observed when measuring samples at the natural abundance level. Calibration of organic measurements with water reference materials did not give satisfactory results, probably owing to differences in their respective pyrolysis pathways. The potential of the technique for food analysis was demonstrated by measuring the δ 2 H‰ values of vanillin samples derived from natural and synthetic sources and by the analyses of hexamethylenetetramine synthesized from beet, cane and apple juice sugars. © Crown copyright 1998. Reproduced with the permission of the Controller of Her Majesty's Stationery Office.

Internal and external checks in the NOSAMS sample preparation laboratory for target quality and homogeneity

In the NOSAMS sample preparation laboratory (SPD we have developed rigorous internal procedures aimed at ensuring that sample preparation introduces as little error into our analyses as possible and identifying problems rapidly. Our three major CO 2 preparation procedures are: stripping inorganic carbon from seawater, hydrolyzing CaCO 3, and oxidizing organic matter. For seawater, approximately 10% of our analyses are standards or blanks which we use to demonstrate extraction of virtually all the inorganic carbon. Analysis of the stable carbon isotopic composition of the CO 2 extracted from our standards indicates a precision of better than 0.15–0.20‰. We also routinely process 14C-free CO 2 in our stripping lines to demonstrate the absence of a significant process-dependent blank. For organic combustions and CaCO 3 hydrolyses, we use the carbon yield (% organic carbon (OC) or % CaCO 3 by weight) as a check on our sample procedures. We have analyzed the blank contribution of these procedures as a function of sample size. Our organic carbon blank is constant at approximately 0.4% modern for samples containing greater than 1 mg C and our carbonate blank is less than 0.2% modern for samples containing more than 0.5 mg C. We use a standard Fe/H 2 catalytic reduction to prepare graphite from CO 2. We check the completeness of our reactions with the pressure data stored during the reaction as well as use a robot to determine a gravimetric yield. All graphite undergoes a visual inspection and is rejected if any heterogeneities are present. We have recombusted graphite made from CO 2 with δ 13C values ranging from −42 to 1‰ and determined that the δ 13C of the recombusted carbon agrees with that from the pure gas to within 0.05‰, demonstrating little or no fractionation during the treatment of the sample. The δ 13C we measure on the CO 2 generated from more than 75% of our samples is compared to the δ 13C measured on the AMS as a further check of our procedures. As further external checks, we analyzed the International Atomic Energy Association (IAEA) samples during the establishment of our laboratory and are presently participating in the third international radiocarbon intercalibration (TIRI) exercise.