Aspects of uranium/thorium series disequilibrium applications to radionuclide migration studies

International Nuclear Information System (INIS)

Ivanovich, M.

1989-11-01

The aim of this paper is to consider the contribution which the uranium/thorium series disequilibrium concept can make to understanding the retardation and transport of radionuclides in the far-field of a radioactive waste repository. In principle, naturally occurring isotopes of uranium, thorium and radium can be regarded as geochemical analogues of the divalent radionuclides and multivalent actinides expected to be present in the radioactive waste inventory. The study of their retardation and/or transport in real rock/water systems which have taken place over geological timescales, can make an important contribution to establishing a rational basis for long-term predictive modelling of radionuclide transport required for safety assessments. (author)

Process for the removal of radium from acidic solutions containing same

International Nuclear Information System (INIS)

Scheitlin, F.M.

1984-01-01

Radium is removed from an inorganic-acid solution contacting the solution with coal fly ash to effect adsorption of the radium on the ash. The radium-containing ash then is separated from the solution. The process is simple and efficient. High radium-distribution coefficients are obtained even at room temperature. Coal fly ash is an inexpensive, acid-resistant, high-surface-area material which is available in large quantities. The invention is applicable, for example, to the recovery of 226 Ra from nitric acid solutions which have been used to leach radium from uranium-mill tailings, and thus contain thorium and uranium. The contaminated fly ash may be incorporated in a suitable matrix and stored, and the residual solutions processed to separate uranium and thorium. (author)

Radium-226 in certified uranium reference ores DL-1a, BL-4a, DH-1a and BL-5

International Nuclear Information System (INIS)

Smith, C.W.; Steger, H.F.

1983-05-01

Radium-226 radioactivity in uranium reference ores BL-4a and BL-5 and uranium-thorium reference ores DL-1a and DH-1a was determined in an interlaboratory program. Twelve of thirteen participants used certified radium solutions from the United States National Bureau of Standards (NBS) for calibration purposes. Recommended values of sup(226)Ra activity and associated parameters were calculated by statistical treatment of the results. In all cases, the recommended values are within 2 percent of activities predicted assuming secular equilibrium in the sup(238)U decay series. The recommended values for radium activity are 1.40, 15.5, 31.5 and 857 Bq/ for DL-1a, BL-4a, DH-1a and BL-5, respectively

Radium removal from Canadian uranium mining effluents by a radium-selective ion exchange complexer

International Nuclear Information System (INIS)

1984-07-01

A laboratory test program was initiated by the Department of Energy, Mines and Resources as part of the National Uranium Tailings Program to investigate the applicability of a radium-selective ion exchange complexer for removing radium from Canadian uranium mining effluents. The ion exchange complexer was shown to be efficient in removing radium from contaminated water of uranium mining operations, with the ultimate loading capacity of the resin on one type of water treated being determined as approximately 1,600 Bq/cm 3 of new resin. The results showed that the resin was effective in removing radium but not any other contaminants

Microbial accumulation of uranium, radium, and cesium

International Nuclear Information System (INIS)

Strandberg, G.W.; Shumate, S.E. II; Parrott, J.R. Jr.; North, S.E.

1981-05-01

Diverse microbial species varied considerably in their ability to accumulate uranium, cesium, and radium. Mechanistic differences in uranium uptake by Saccharomyces cerevisiae and Pseudomonas aeruginosa were indicated. S. serevisiae exhibited a slow (hours) surface accumulation of uranium which was subject to environmental factors, while P. aeruginosa accumulated uranium rapidly (minutes) as dense intracellular deposits and did not appear to be affected by environmental parameters. Metabolism was not required for uranium uptake by either organism. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several species tested

Competitive biosorption of thorium and uranium by actinomycetes

International Nuclear Information System (INIS)

Nakajima, Akira; Tsuruta, Takehiko

2002-01-01

The competitive biosorption of thorium and uranium by actinomycetes was examined. Of the actinomycetes tested, Streptomyces levoris showed the highest ability to sorb both thorium and uranium from aqueous systems. Thorium sorption was not affected by co-existed uranium, while uranium sorption was strongly hindered by co-existed thorium. The amounts of both thorium and uranium sorbed by Streptomyces levoris cells increased with an increase of the solution pH. Although the equilibrium isotherm of uranium biosorption is in similar manner as that of thorium biosorption, uranium was sorbed much faster than thorium. Biosorption isotherm of each metal ion could be well fitted by Langmuir isotherm taking the ionic charge of metal ions into account. The Langmuir isotherm for binary system did not explain completely the competitive biosorption of thorium and uranium by Streptomyces levoris. However, the results suggested that the ion species of both metals in the cells should be Th(OH) 2 2+ and UO 2 2+ , respectively. (author)

Uranium ore processing

International Nuclear Information System (INIS)

Ritcey, G.M.; Haque, K.E.; Lucas, B.H.; Skeaff, J.M.

1983-01-01

The authors have developed a complete method of recovering separately uranium, thorium and radium from impure solids such as ores, concentrates, calcines or tailings containing these metals. The technique involves leaching, in at least one stage. The impure solids in finely divided form with an aqueous leachant containing HCl and/or Cl 2 until acceptable amounts of uranium, thorium and radium are dissolved. Uranium is recovered from the solution by solvent extraction and precipitation. Thorium may also be recovered in the same manner. Radium may be recovered by at least one ion exchange, absorption and precipitation. This amount of iron in the solution must be controlled before the acid solution may be recycled for the leaching process. The calcine leached in the first step is prepared in a two stage roast in the presence of both Cl 2 and a metal sulfide. The first stage is at 350-450 0 and the second at 550-700 0

Treatment of uranium mining and milling wastewater using biological adsorbents

International Nuclear Information System (INIS)

Tsezos, M.

1983-01-01

Selected samples of waste microbial biomass originating from various industrial fermentation processes and biological treatment plants have been screened for biosorbent properties in conjunction with uranium, thorium and radium in aqueous solutions. Biosorption isotherms were used for the evaluation of biosorptive uptake capacity of the biomass. The biomass was also compared to synthetic adsorbents such as activated carbon. Determined uranium, thorium and radium biosorption isotherms were independent of the initial solution concentrations. Solution pH affected uptake. Rhizopus arrhizus at pH 4 exhibited the highest uranium and thorium biosorptive uptake capacity in excess of 180 Mg/g. It removed about 2.5 and 3.3 times more uranium than the ion exchange resin and activated carbon tested. Penicillium chrysogenum adsorbed 50000 pCi/g radium at pH 7 and at an equilibrium radium concentration of 1000 pCi/L. The most effective biomass types studied exhibited removals in excess of 99% of the radium in solution

Port Radium Canada's Original Radium/Uranium Mine, The Complete Story of Canada's Historic Radium/Uranium Mine, 1932 to 2012 - 13159

International Nuclear Information System (INIS)

Chambers, Doug; Wiatzka, Gerd; Brown, Steve

2013-01-01

This paper provides the life story of Canada's original radium/uranium mine. In addition to the history of operations, it discusses the unique and successful approach used to identify the key issues and concerns associated with the former radium, uranium and silver mining property and the activities undertaken to define the remedial actions and subsequent remedial plan. The Port Radium Mine site, situated approximately 275 km north of Yellowknife on the east shore of Great Bear Lake, Northwest Territories, was discovered in 1930 and underground mining began in 1932. The mine operated almost continuously from 1932 to 1982, initially for recovery of radium, then uranium and finally, for recovery of silver. Tailings production totaled an estimated 900,000 tons and 800,000 tons from uranium and silver processing operations respectively. In the early days of mining, Port Radium miners were exposed to radon and associated decay product levels (in Working Level Months of exposure - WLM) hundreds of times greater than modern standards. The experience of the Port Radium miners provides important contribution to understanding the risks from radon. While the uranium mine was originally decommissioned in the early 1960's, to the standards of the day, the community of Deline (formerly Fort Franklin) had concerns about residual contamination at the mine site and the potential effects arising from use of traditional lands. The Deline people were also concerned about the possible risks to Deline Dene arising from their work as ore carriers. In the late 1990's, the community of Deline brought these concerns to national attention and consequently, the Government of Canada and the community of Deline agreed to move forward in a collaborative manner to address these concerns. The approach agreed to was to establish the Canada-Deline Uranium Table (CDUT) to provide a joint process by which the people of Deline could have their concerns expressed and addressed. A great deal of work was

Distribution and transport of radionuclides in a boreal mire – assessing past, present and future accumulation of uranium, thorium and radium

International Nuclear Information System (INIS)

Lidman, Fredrik; Ramebäck, Henrik; Bengtsson, Åsa; Laudon, Hjalmar

2013-01-01

The spatial distribution of 238 U, 226 Ra, 40 K and the daughters of 232 Th, 228 Ra and 228 Th, were measured in a small mire in northern Sweden. High activity concentrations of 238 U and 232 Th (up to 41 Bq 238 U kg −1 ) were observed in parts of the mire with a historical or current inflow of groundwater from the surrounding till soils, but the activities declined rapidly further out in the mire. Near the outlet and in the central parts of the mire the activity concentrations were low, indicating that uranium and thorium are immobilized rapidly upon their entering the peat. The 226 Ra was found to be more mobile with high activity concentrations further out into the mire (up to 24 Bq kg −1 ), although the central parts and the area near the outlet of the mire still had low activity concentrations. Based on the fluxes to and from the mire, it was estimated that approximately 60–70% of the uranium and thorium entering the mire currently is retained within it. The current accumulation rates were found to be consistent with the historical accumulation, but possibly lower. Since much of the accumulation still is concentrated to the edges of the mire and the activities are low compared to other measurements of these radionuclides in peat, there are no indications that the mire will be saturated with respect to radionuclides like uranium, thorium and radium in the foreseen future. On the contrary, normal peat growth rates for the region suggest that the average activity concentrations of the peat currently may be decreasing, since peat growth may be faster than the accumulation of radionuclides. In order to assess the total potential for accumulation of radionuclides more thoroughly it would, however, be necessary to also investigate the behaviour of other organophilic elements like aluminium, which are likely to compete for binding sites on the organic material. Measurements of the redox potential and other redox indicators demonstrate that uranium possibly could

Radium accumulation in animal thyroid glands: a possible method for uranium and thorium prospecting

International Nuclear Information System (INIS)

Wogman, N.A.; Brodzinski, R.L.; Middlesworth, L.V.

1976-01-01

A method of prospecting for uranium and thorium is proposed based on uptake of their radioactive daughters, 226 Ra and 228 Ra, by plants, the collection of plant material by herbivores, the concentration of the radioactive species by specific animal tissues, and the subsequent gamma-ray analysis of the tissues

Remediation of soil/concrete contaminated with uranium and radium by biological method

International Nuclear Information System (INIS)

Gye-Nam Kim; Seung-Su Kim; Hye-Min Park; Won-Suk Kim; Uk-Ryang Park; Jei-Kwon Moon

2013-01-01

Biological method was studied for remediation of soil/concrete contaminated with uranium and radium. Optimum experiment conditions for mixing ratios of penatron and soil, and the pH of soil was obtained through several bioremediations with soil contaminated with uranium and radium. It was found that an optimum mixing ratio of penatron for bioremediation of uranium soil was 1 %. Also, the optimum pH condition for bioremediation of soil contaminated with uranium and radium was 7.5. The removal efficiencies of uranium and radium from higher concentration of soil were rather reduced in comparison with those from lower concentration of soil. Meanwhile, the removal of uranium and radium in concrete by bioremediation is possible but the removal rate from concrete was slower than that from soil. The removal efficiencies of uranium and radium from soil under injection of 1 % penatron at pH 7.5 for 120 days were 81.2 and 81.6 %, respectively, and the removal efficiencies of uranium and radium from concrete under the same condition were 63.0 and 45.2 %, respectively. Beyond 30 days, removal rates of uranium and radium from soil and concrete by bioremediation was very slow. (author)

Soiled-based uranium disequilibrium and mixed uranium-thorium series radionuclide reference materials

International Nuclear Information System (INIS)

Donivan, S.; Chessmore, R.

1988-12-01

The US Department of Energy (DOE) Office of Remedial Action and Waste Technology has assigned the Technical Measurements Center (TMC), located at the DOE Grand Junction Colorado, Projects Office and operated by UNC Geotech (UNC), the task of supporting ongoing remedial action programs by providing both technical guidance and assistance in making the various measurements required in all phases of remedial action work. Pursuant to this task, the Technical Measurements Center prepared two sets of radionuclide reference materials for use by remedial action contractors and cognizant federal and state agencies. A total of six reference materials, two sets comprising three reference materials each, were prepared with varying concentrations of radionuclides using mill tailings materials, ores, and a river-bottom soil diluent. One set (disequilibrium set) contains varying amounts of uranium with nominal amounts of radium-226. The other set (mixed-nuclide set) contains varying amounts of uranium-238 and thorium-232 decay series nuclides. 14 refs., 10 tabs

Geochemical prospecting for thorium and uranium deposits

International Nuclear Information System (INIS)

Boyle, R.W.

1982-01-01

The basic purpose of this book is to present an analysis of the various geochemical methods applicable in the search for all types of thorium and uranium deposits. The general chemistry and geochemistry of thorium and uranium are briefly described in the opening chapter, and this is followed by a chapter on the deposits of the two elements with emphasis on their indicator (pathfinder) elements and on the primary and secondary dispersion characteristics of thorium and uranium in the vicinity of their deposits. The next seven chapters form the main part of the book and describe geochemical prospecting for thorium and uranium, stressing selection of areas in which to prospect, radiometric surveys, analytical geochemical surveys based on rocks (lithochemical surveys), unconsolidated materials (pedochemical surveys), natural waters and sediments (hydrochemical surveys), biological materials (biogeochemical surveys), gases (atmochemical surveys), and miscellaneous methods. A final brief chapter reviews radiometric and analytical methods for the detection and estimation of thorium and uranium. (Auth.)

Uranium production in thorium/denatured uranium fueled PWRs

International Nuclear Information System (INIS)

Arthur, W.B.

1977-01-01

Uranium-232 buildup in a thorium/denatured uranium fueled pressurized water reactor, PWR(Th), was studied using a modified version of the spectrum-dependent zero dimensional depletion code, LEOPARD. The generic Combustion Engineering System 80 reactor design was selected as the reactor model for the calculations. Reactors fueled with either enriched natural uranium and self-generated recycled uranium or uranium from a thorium breeder and self-generated recycled uranium were considered. For enriched natural uranium, concentrations of 232 U varied from about 135 ppM ( 232 U/U weight basis) in the zeroth generation to about 260 ppM ( 232 U/U weight basis) at the end of the fifth generation. For the case in which thorium breeder fuel (with its relatively high 232 U concentration) was used as reactor makeup fuel, concentrations of 232 U varied from 441 ppM ( 232 U/U weight basis) at discharge from the first generation to about 512 ppM ( 232 U/U weight basis) at the end of the fifth generation. Concentrations in freshly fabricated fuel for this later case were 20 to 35% higher than the discharge concentration. These concentrations are low when compared to those of other thorium fueled reactor types (HTGR and MSBR) because of the relatively high 238 U concentration added to the fuel as a denaturant. Excellent agreement was found between calculated and existing experimental values. Nevertheless, caution is urged in the use of these values because experimental results are very limited, and the relevant nuclear data, especially for 231 Pa and 232 U, are not of high quality

Uranium,Radium and Iron Absorption from Liquid Waste Uranium Ore Processing by Zeolite

International Nuclear Information System (INIS)

Wismawati, T; Sorot sudiro, A; Herjati, T

1998-01-01

The aim of this work is to determine zeolites sorption capacity and the distribution coefficient of uranium, radium, and iron in zeolite-liquid waste system. Mineralogical composition of zeolite used in the experiment has been determine by examining the thin sections of zeolite grains under a microscope. Zeolite has ben activated by the dilute sulfuric acid or sodium hydroxide solution. The results show that the use of 0.25 N sodium hydroxide solution could be optimizing the zeolite for uranium and iron ions sorption and that of 0.1 N sulfuric acid solution is for radium sorption. The re-activation process has been carried out in three hours. Under such a condition, the sorption efficiency of zeolite to those ions have been known to be 45.85% for uranium, 96.63 % for iron and 87.80 % for radium. The distribution coefficients of uranium, radium and iron ion in zeolite-liquid waste system have been calculated 0.85, 7.02, and 28.65 ml/g respectively

Port Radium Canada's Original Radium/Uranium Mine, The Complete Story of Canada's Historic Radium/Uranium Mine, 1932 to 2012 - 13159

Energy Technology Data Exchange (ETDEWEB)

Chambers, Doug; Wiatzka, Gerd [SENES Consultants Limited, 121 Granton Drive, Unit 12, Richmond Hill, ON L4B 3N4 (United States); Brown, Steve [SENES Consultants Limited, 8310 South Valley Highway, Suite 3016, Englewood, Colorado 80112 (United States)

2013-07-01

This paper provides the life story of Canada's original radium/uranium mine. In addition to the history of operations, it discusses the unique and successful approach used to identify the key issues and concerns associated with the former radium, uranium and silver mining property and the activities undertaken to define the remedial actions and subsequent remedial plan. The Port Radium Mine site, situated approximately 275 km north of Yellowknife on the east shore of Great Bear Lake, Northwest Territories, was discovered in 1930 and underground mining began in 1932. The mine operated almost continuously from 1932 to 1982, initially for recovery of radium, then uranium and finally, for recovery of silver. Tailings production totaled an estimated 900,000 tons and 800,000 tons from uranium and silver processing operations respectively. In the early days of mining, Port Radium miners were exposed to radon and associated decay product levels (in Working Level Months of exposure - WLM) hundreds of times greater than modern standards. The experience of the Port Radium miners provides important contribution to understanding the risks from radon. While the uranium mine was originally decommissioned in the early 1960's, to the standards of the day, the community of Deline (formerly Fort Franklin) had concerns about residual contamination at the mine site and the potential effects arising from use of traditional lands. The Deline people were also concerned about the possible risks to Deline Dene arising from their work as ore carriers. In the late 1990's, the community of Deline brought these concerns to national attention and consequently, the Government of Canada and the community of Deline agreed to move forward in a collaborative manner to address these concerns. The approach agreed to was to establish the Canada-Deline Uranium Table (CDUT) to provide a joint process by which the people of Deline could have their concerns expressed and addressed. A great

The hydrolysis of thorium dicarbide and of mixed uranium-thorium dicarbides; L'hydrolyse du dicarbure de thorium et des dicarbures mixtes d'uranium et de thorium

Energy Technology Data Exchange (ETDEWEB)

Del Litto, B [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1966-09-01

The hydrolysis of thorium dicarbide leads to the formation of a complex mixture of gaseous and condensed carbon hydrides. The temperature, between 25 and 100 deg. C, has no influence on the nature and composition of the gas phase. The reaction kinetics, however, are strongly temperature dependent. In a hydrochloric medium, an enrichment in hydrogen of the gas mixture is observed. On the other hand a decrease in hydrogen and an increase in acetylene content take place in an oxidizing medium. The general results can be satisfactorily interpreted through a reaction mechanism involving C-C radical groups. In the same way, the hydrolysis of uranium-thorium-carbon ternary alloys leads to the formation of gaseous and condensed carbon hydrides. The variation of the composition of the gas phase versus uranium content in the alloy suggests an hypothesis about the carbon-carbon distance in the alloy crystal lattice. The variation of methane content, on the other hand, has lead us to discuss the nature of the various phases present in uranium-carbon alloys and carbon-rich uranium-thorium-carbon alloys. We have reached the conclusion that these alloys include a proportion of monocarbide which is dependent upon the ratio. Th/(Th + U). We put forward a diagram of the system uranium-carbon with features proper to explain some phenomena which have been observed in the uranium-thorium-carbon ternary diagram. (author) [French] L'hydrolyse du dicarbure de thorium conduit a la formation d'un melange complexe d'hydrures de carbone gazeux et condenses. La temperature entre 25 et 100 deg. C n'a pas d'influence sur la nature ef la composition de la phase gazeuse. Par contre la cinetique en depend fortement. En milieu chlorhydrique, on observe un enrichissement en hydrogene du melange gazeux. Au contraire, en milieu oxydant il se produit une diminution du taux d'hydrogene et une augmentation tres nette du taux d'acetylene. L'ensemble des resultats obtenus peut etre interprete d'une maniere

Competitive biosorption of thorium and uranium by Micrococcus luteus

International Nuclear Information System (INIS)

Nakajima, A.; Tsuruta, T.

2004-01-01

Eighteen species of bacteria were screened for abilities to adsorb thorium and uranium. High adsorption capacity was observed for thorium by Arthrobacter nicotianae and Micrococcus luteus, and for uranium by Arthrobacter nicotianae. The adsorption of both thorium and uranium by Micrococcus luteus cells was rapid, was affected by the solution pH, and obeyed the Langmuir adsorption isotherm for binary systems in a competitive manner taking the ionic charge of the metal ion into account. The thorium selectivity in the competitive adsorption is assumed to be caused by the faster adsorption and the slower desorption rates of thorium than those of uranium. (author)

Chemistry of uranium, thorium, and radium isotopes in the Ganga-Brahmaputra river system: Weathering processes and fluxes to the Bay of Bengal

Science.gov (United States)

Sarin, M. M.; Krishnaswami, S.; somayajulu, B. L. K.; Moore, W. S.

1990-05-01

The most comprehensive data set on uranium, thorium, and radium isotopes in the Ganga-Brahmaputra, one of the major river systems of the world, is reported here. The dissolved 238U concentration in these river waters ranges between 0.44 and 8.32 μ/1, and it exhibits a positive correlation with major cations (Na + K + Mg + Ca). The 238U /∑Cations ratio in waters is very similar to that measured in the suspended sediments, indicating congruent weathering of uranium and major cations. The regional variations observed in the [ 234U /238U ] activity ratio are consistent with the lithology of the drainage basins. The lowland tributaries (Chambal, Betwa, Ken, and Son), draining through the igneous and metamorphic rocks of the Deccan Traps and the Vindhyan-Bundelkhand Plateau, have [ 234U /238U ] ratio in the range 1.16 to 1.84. This range is significantly higher than the near equilibrium ratio (~1.05) observed in the highland rivers which drain through sedimentary terrains. The dissolved 226Ra concentration ranges between 0.03 and 0.22 dpm/1. The striking feature of the radium isotopes data is the distinct difference in the 228Ra and 226Ra abundances between the highland and lowland rivers. The lowland waters are enriched in 228Ra while the highland waters contain more 226Ra. This difference mainly results from the differences in their weathering regimes. The discharge-weighted mean concentration of dissolved 238U in the Ganga (at Patna) and in the Brahmaputra (at Goalpara) are 1.81 and 0.63 μ/1, respectively. The Ganga-Brahmaputra river system constitutes the major source of dissolved uranium to the Bay of Bengal. These rivers transport annually about 1000 tons of uranium to their estuaries, about 10% of the estimated global supply of dissolved uranium to the oceans via rivers. The transport of uranium by these rivers far exceeds that of the Amazon, although their water discharge is only about 20% of that of the Amazon. The high intensity of weathering of uranium in

Geochemical prospecting for uranium and thorium deposits

International Nuclear Information System (INIS)

Boyle, R.W.

1980-01-01

A brief review of analytical geochemical prospecting methods for uranium and thorium is given excluding radiometric techniques, except those utilized in the determination of radon. The indicator (pathfinder) elements useful in geochemical surveys are listed for each of the types of known uranium and thorium deposits; this is followed by sections on analytical geochemical surveys based on rocks (lithochemical surveys), unconsolidated materials (pedochemical surveys), natural waters and sediments (hydrochemical surveys), biological materials (biogeochemical surveys) and gases (atmochemical surveys). All of the analytical geochemical methods are applicable in prospecting for thorium and uranium, particularly where radiometric methods fail due to attenuation by overburden, water, deep leaching and so on. Efficiency in the discovery of uranium and/or thorium orebodies is promoted by an integrated methods approach employing geological pattern recognition in the localization of deposits, analytical geochemical surveys, and radiometric surveys. (author)

Study on technology for radioactive waste treatment and management from uranium production

International Nuclear Information System (INIS)

Vu Hung Trieu; Vu Thanh Quang; Nguyen Duc Thanh; Trinh Giang Huong; Tran Van Hoa; Hoang Minh Chau; Ngo Van Tuyen; Nguyen Hoang Lan; Vuong Huu Anh

2007-01-01

There is some solid and liquid radioactive waste created during producing Uranium that needs being treated and managed to keep our environment safe. This radioactive waste contains Uranium (U-238), Thorium (Th-232), Radium (Ra-226) and some heavy metals and mainly is low radioactive waste. Our project has researched and built up appropriate technology for treating and managing the radioactive waste. After researching and experimenting, we have built up four technology processes as follows: Technology for separating Radium from liquid waste; Technology for treating and managing solid waste containing Ra; Technology for separating Thorium from liquid waste after recovering radium; Technology for stabilizing solid waste from Uranium production. (author)

The hydrolysis of thorium dicarbide and of mixed uranium-thorium dicarbides

International Nuclear Information System (INIS)

Del Litto, B.

1966-09-01

The hydrolysis of thorium dicarbide leads to the formation of a complex mixture of gaseous and condensed carbon hydrides. The temperature, between 25 and 100 deg. C, has no influence on the nature and composition of the gas phase. The reaction kinetics, however, are strongly temperature dependent. In a hydrochloric medium, an enrichment in hydrogen of the gas mixture is observed. On the other hand a decrease in hydrogen and an increase in acetylene content take place in an oxidizing medium. The general results can be satisfactorily interpreted through a reaction mechanism involving C-C radical groups. In the same way, the hydrolysis of uranium-thorium-carbon ternary alloys leads to the formation of gaseous and condensed carbon hydrides. The variation of the composition of the gas phase versus uranium content in the alloy suggests an hypothesis about the carbon-carbon distance in the alloy crystal lattice. The variation of methane content, on the other hand, has lead us to discuss the nature of the various phases present in uranium-carbon alloys and carbon-rich uranium-thorium-carbon alloys. We have reached the conclusion that these alloys include a proportion of monocarbide which is dependent upon the ratio. Th/(Th + U). We put forward a diagram of the system uranium-carbon with features proper to explain some phenomena which have been observed in the uranium-thorium-carbon ternary diagram. (author) [fr

The environmental behaviour of uranium and thorium

International Nuclear Information System (INIS)

Sheppard, M. I.

1980-08-01

Uranium and thorium have had many uses in the past, and their present and potential use as nuclear fuels in energy production is very significant. Both elements, and their daughter products, are of environmental interest because they may have effects from the time of mining to the time of ultimate disposal of used nuclear fuel. To assess the impact on the environment of man's use and disposal of uranium and thorium, we must know the physical, chemical and biological behaviour of these elements. This report summarizes the literature, updating and extending earlier reviews pertaining to uranium and thorium. The radiological properties, chemistry, forms of occurrence in nature, soil interactions, as well as distribution coefficients and mode of transport are discussed for both elements. In addition, uranium and thorium concentrations in plants, plant transfer coefficients, concentrations in soil organisms and methods of detection are summarized. (auth)

Radium 226 and uranium isotopes simultaneously determination in water samples using liquid scintillation counter

International Nuclear Information System (INIS)

Al-Masri, M.S.; Al-Akel, B.; Saaid, S.; Nashawati, A.

2007-04-01

In this work a method has been developed to determine simultaneously Radium 226 and Uranium isotopes in water samples by low back ground Liquid Scintillation Counter. Radium 226 was determined by its progeny Polonium 214 after one month of sample storage in order to achieve the equilibrium between Radium 226 and Polonium 214. Uranium isotopes were determined by subtracting Radium 226 activity from total alpha activity. The method detection limits were 0.049 Bq/L and 0.176 Bq/L for Radium 226 and Uranium isotopes respectively. The repeatability limits were ± 0.32 Bq/L and ± 0.9 Bq/L for Radium 226 and Uranium isotopes respectively. While relative errors were % 9.5 and %18.2 for Radium 226 and Uranium isotopes respectively. On the other hand, the report presented the results of different standard and natural samples.(author)

Methodology of simultaneous analysis of Uranium and Thorium by nuclear and atomic techniques. Application to the Uranium and Thorium dosing in mineralogic samples

International Nuclear Information System (INIS)

Fakhi, S.

1988-01-01

This work concerns essentially the potential applications of 100 kW nuclear reactor of Strasbourg Nuclear Research Centre to neutron activation analysis of Uranium and Thorium. The Uranium dosing has been made using: 239-U, 239-Np, fission products or delayed neutrons. Thorium has been showed up by means of 233-Th or 233-Pa. The 239-U and 233-Th detection leads to a rapid and non-destructive analysis of Uranium and Thorium. The maximum sensitivity is of 78 ng for Uranium and of 160 ng for Thorium. The Uranium and Thorium dosing based on 239-Np and 233-Pa detection needs chemical selective separations for each of these radionuclides. The liquid-liquid extraction has permitted to elaborate rapid and quantitative separation methods. The sensitivities of the analysis after extraction reach 30 ng for Uranium and 50 ng for Thorium. The fission products separation study has allowed to elaborate the La, Ce and Nd extractions and its application to the Uranium dosing gives satisfying results. A rapid dosing method with a sensitivity of 0.35 microgramme has been elaborated with the help of delayed neutrons measurement. These different methods have been applied to the Uranium and Thorium dosing in samples coming from Oklo mine in Gabon. The analyses of these samples by atomic absorption spectroscopy and by the proton induced X-ray emission (PIXE) method confirm that the neutron activation analysis methods are reliable. 37 figs., 14 tabs., 50 refs

Bioaccumulation of uranium and thorium from the solution containing both elements using various microorganisms

International Nuclear Information System (INIS)

Tsuruta, T.

2006-01-01

The effects of proton, thorium and uranium on the bioaccumulation of thorium and uranium from the solution (pH 3.5) containing uranium and thorium using Streptomyces levoris cells were examined. The amount of thorium accumulated using the cells decreased by the pre-contact between the cells and the solution (pH 3.5) containing no metals, whereas that of uranium was almost unaffected by the treatment. The amount of thorium was almost unaffected by the existence of uranium. On the other hand, the amount of uranium accumulated was strongly affected by the thorium, especially thorium addition after uranium accumulation. The decrease of uranium accumulated by the addition of thorium after the accumulation of uranium was higher than that from the solution containing both elements. Therefore, the contribution of uranium-thorium exchange reaction was higher than that of competition reaction. Accordingly, proton-uranium-thorium exchange reaction was occurred in the accumulation of thorium from the solution containing thorium and uranium. The gram-positive bacteria, such as Micrococcus luteus, Arthrobacter nicotianae, Bacillus subtilis and B. megaterium, has a much higher separation factor as thorium/uranium than that of actinomycetes. These gram-positive bacterial strains can be used for the accumulation of thorium from the solution containing uranium and thorium

Economic analysis of thorium-uranium fuel cycle introduced into PWRs

International Nuclear Information System (INIS)

Fan Li; Sun Qian

2014-01-01

Using PWR of Daya Bay Unit l as the reference reactor, a validated computer code was used to calculate the fuel cycle costs for uranium fuel cycle and thorium-uranium fuel cycle over the following 20 0perational years respectively. The calculation results show that the thorium-uranium fuel cycle is economically competitive with the uranium fuel cycle when reprocessing mode is adopted. For thorium-uranium fuel cycle, if the price of natural uranium is higher than 120 $ /pound U_3O_8, the fuel cycle cost of the direct disposal mode is greater than that of the reprocessing mode. Therefore, when the uranium price may maintain a high level long-termly, adopting reprocessing mode will benefit the economic advantage for the thorium-uranium fuel cycle introduced into PWRs. (authors)

Determination of Uranium and Thorium in Drinking and Seawater

International Nuclear Information System (INIS)

Rozmaric Macefat, M.; Gojmerac Ivsic, A.; Grahek, Z.; Barisic, D.

2008-01-01

Uranium and thorium are the first members of natural radioactive chain which makes their determination in natural materials interesting from geochemical and radioecological aspect. They are quantitatively determined as elements by spectrophotometric method and/or their radioisotopes by alpha spectrometry and ICP-MS. It is necessary to develop inexpensive, rapid and sensitive methods for the routine researches because of continuous monitoring of the radioactivity level. Development of a new method for the isolation of uranium and thorium from liquid samples and subsequent spectrophotometric determination is described in this paper. It is possible to isolate uranium and thorium from drinking and seawater using extraction chromatography or ion exchange chromatography. Uranium and thorium can be strongly bound on the TRU extraction chromatographic resin from 3 mol dm -3 HNO 3 (chemical recovery is 100 percent) and separated from other interfering elements (sodium, potassium, calcium, strontium etc). Their mutual separation is possible by using anion exchanger Amberlite CG-400 (NO 3 - form). From alcoholic solutions of nitric acid thorium can be strongly bound on the anion exchanger while uranium is much more weakly bound which enables its separation from thorium. After the separation, uranium and thorium are determined by spectrophotometric method with arsenazo III at 652 nm and 662 nm respectively. Developed method enables selection of the optimal mode of isolation for the given purposes.(author)

Recovery of thorium and rare earths by their peroxides precipitation from a residue produced in the thorium purification facility

International Nuclear Information System (INIS)

Freitas, Antonio Alves de

2008-01-01

As consequence of the operation of a Thorium purification facility, for pure Thorium Nitrate production, the IPEN (Instituto de Pesquisas Energeticas e Nucleares) has stored away a solid residue called RETOTER (REsiduo de TOrio e TErras Raras). The RETOTER is rich in Rare-Earth Elements and significant amount of Thorium-232 and minor amount of Uranium. Furthermore it contains several radionuclides from the natural decay series. Significant radioactivity contribution is generated by the Thorium descendent, mainly the Radium-228(T 1/2 =5.7y), known as meso thorium and Thorium-228(T 1/2 1.90y). An important thorium daughter is the Lead-208, a stable isotope present with an expressive quantity. After the enclosure of the operation of the Thorium purification facility, many researches have been developed for the establishment of methodologies for recovery of Thorium, Rare-Earth Elements and Lead-208 from the RETOTER. This work presents a method for RETOTER decontamination, separating and bordering upon some radioactive isotopes. The residue was digested with nitric acid and the Radium-228 was separated by the Barium Sulphate co-precipitation procedure. Finally, the Thorium was separated by the peroxide precipitation and the Rare-Earth Elements were also recovered by the Rare-Earth peroxide precipitation in the filtrate solution.(author)

Removal of radium-226 from uranium mining effluents

International Nuclear Information System (INIS)

Averill, D.W.; Moffett, D.; Webber, R.T.; Whittle, L.; Wood, J.A.

1984-12-01

Uranium mining and milling operations usually generate large quantities of solid and liquid waste materials. A slurry, consisting of waste rock and chemical solutions from the milling operation, is discharged to impoundment areas (tailings basins). Most of the radioactive material dissolved in tailings slurries is precipitated by the addition of lime and limestone prior to discharge from the mill. However, the activity of one radioisotope, radium-226, remains relatively high in the tailings basin effluents. In Canada, radium-226 is removed from uranium mining and milling effluents by the addition of barium chloride to precipitate barium-radium sulphate [(Ba,Ra)SO 4 ]. Although dissolved radium-226 activities are generally reduced effectively, the process is considered to have two undesirable characteristics: the first related to suspended radium-226 in the effluents and the second to ultimate disposal of the (Ba,Ra)SO 4 sludge. A government-industry mining task force established a radioactivity sub-group in 1974 to assist in the development of effluent guidelines and regulations for the uranium mining industry (Radioactivity Sub-group, 1974). The investigation of more effective removal methods was recommended, including the development of mechanical treatment systems as alternatives to settling ponds. Environment Canada's Wastewater Technology Centre (WTC) initiated a bench scale study in March, 1976 which was designed to assess the feasibility of using precipitation, coagulation, flocculation and sedimentation for the removal of radium-226. In 1977, the study was accelerated with financial assistance from the Atomic Energy Control Board. The results were favourable, with improved radium removals obtained in bench scale batch tests using barium chloride as the precipitant and either alum or ferric chloride as the coagulant. A more comprehensive bench scale and pilot scale process development and demonstration program was formulated. The results of the joint study

Microbial uptake of uranium, cesium, and radium

Energy Technology Data Exchange (ETDEWEB)

Strandberg, G.W.; Shumate, S.E. II; Parrott, J.R. Jr.; McWhirter, D.A.

1980-01-01

The ability of diverse microbial species to concentrate uranium, cesium, and radium was examined. Saccharomyces cerevisiae, Pseudomonas aeruginosa, and a mixed culture of denitrifying bacteria accumulated uranium to 10 to 15% of the dry cell weight. Only a fraction of the cells in a given population had visible uranium deposits in electron micrographs. While metabolism was not required for uranium uptake, mechanistic differences in the metal uptake process were indicated. Uranium accumulated slowly (hours) on the surface of S. cerevisiae and was subject to environmental factors (i.e., temperature, pH, interfering cations and anions). In contrast, P. aeruginosa and the mixed culture of denitrifying bacteria accumulated uranium rapidly (minutes) as dense, apparently random, intracellular deposits. This very rapid accumulation has prevented us from determining whether the uptake rate during the transient between the initial and equilibrium distribution of uranium is affected by environmental conditions. However, the final equilibrium distributions are not affected by those conditions which affect uptake by S. cerevisiae. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several microbial species tested. The potential utility of microorganisms for the removal and concentration of these metals from nuclear processing wastes and several bioreactor designs for contacting microorganisms with contaminated waste streams will be discussed.

A comparison between thorium-uranium and low enrichment uranium cycles in the high temperature reactors

Energy Technology Data Exchange (ETDEWEB)

Cerles, J M

1973-03-15

In a previous report, it was shown that the Uranium cycle could be used as well with multi-hole block (GGA type) as with tubular elements. Now, in a F.S.V. geometry, a comparison is made between Thorium cycle and Uranium cycle. This comparison will be concerned with the physical properties of the materials, the needs of natural Uranium, the fissile material inventory and, at last, an attempt of economical considerations. In this report the cycle will be characterizd by the fertile material. So, we write ''Thorium cycle'' for Highly Enriched Uranium - Thorium cycle and ''Uranium cycle'' for low Enrichment Uranium cycle.

State of uranium and radium radionuclides in the soil medium

International Nuclear Information System (INIS)

Vojnikova, E.V.; Sokolik, G.A.; Ovsyannikova, S.V.; Popenya, M.V.

2010-01-01

The reserves of migratory active, potentially mobile and potentially biologically available forms of uranium and radium in the mineral and organic soils of Belarus have been established. The uranium and radium species in the soil pore waters have been also studied. The received data makes possible the estimation of the radionuclide ability to participate in the processes of biogeochemical migration in terrestrial ecosystems. (authors)

Quantitative laws governing the migration of magnesium, calcium, radium-226, thorium-228 in the link between soils and plants

International Nuclear Information System (INIS)

Ashkinazi, E.I.

1982-02-01

Concentrations of magnesium, calcium, radium 226 and thorium 228 in podsolized chernozem and medium-loamy soils and in agricultural plants (wheat, barley, peas, potatoes, beets, and carrots) were determined. Transition coefficients of magnesium, calcium and radium 226 from soils to plants were calculated

Uranium tailings reference materials

International Nuclear Information System (INIS)

Smith, C.W.; Steger, H.F.; Bowman, W.S.

1984-01-01

Samples of uranium tailings from Bancroft and Elliot Lake, Ontario, and from Beaverlodge and Rabbit Lake, Saskatchewan, have been prepared as compositional reference materials at the request of the National Uranium Tailings Research Program. The four samples, UTS-1 to UTS-4, were ground to minus 104 μm, each mixed in one lot and bottled in 200-g units for UTS-1 to UTS-3 and in 100-g units for UTS-4. The materials were tested for homogeneity with respect to uranium by neutron activation analysis and to iron by an acid-decomposition atomic absorption procedure. In a free choice analytical program, 18 laboratories contributed results for one or more of total iron, titanium, aluminum, calcium, barium, uranium, thorium, total sulphur, and sulphate for all four samples, and for nickel and arsenic in UTS-4 only. Based on a statistical analysis of the data, recommended values were assigned to all elements/constituents, except for sulphate in UTS-3 and nickel in UTS-4. The radioactivity of thorium-230, radium-226, lead-210, and polonium-210 in UTS-1 to UTS-4 and of thorium-232, radium-228, and thorium-228 in UTS-1 and UTS-2 was determined in a radioanalytical program composed of eight laboratories. Recommended values for the radioactivities and associated parameters were calculated by a statistical treatment of the results

Comparison of the Environment, Health, And Safety Characteristics of Advanced Thorium- Uranium and Uranium-Plutonium Fuel Cycles

Science.gov (United States)

Ault, Timothy M.

The environment, health, and safety properties of thorium-uranium-based (''thorium'') fuel cycles are estimated and compared to those of analogous uranium-plutonium-based (''uranium'') fuel cycle options. A structured assessment methodology for assessing and comparing fuel cycle is refined and applied to several reference fuel cycle options. Resource recovery as a measure of environmental sustainability for thorium is explored in depth in terms of resource availability, chemical processing requirements, and radiological impacts. A review of available experience and recent practices indicates that near-term thorium recovery will occur as a by-product of mining for other commodities, particularly titanium. The characterization of actively-mined global titanium, uranium, rare earth element, and iron deposits reveals that by-product thorium recovery would be sufficient to satisfy even the most intensive nuclear demand for thorium at least six times over. Chemical flowsheet analysis indicates that the consumption of strong acids and bases associated with thorium resource recovery is 3-4 times larger than for uranium recovery, with the comparison of other chemical types being less distinct. Radiologically, thorium recovery imparts about one order of magnitude larger of a collective occupational dose than uranium recovery. Moving to the entire fuel cycle, four fuel cycle options are compared: a limited-recycle (''modified-open'') uranium fuel cycle, a modified-open thorium fuel cycle, a full-recycle (''closed'') uranium fuel cycle, and a closed thorium fuel cycle. A combination of existing data and calculations using SCALE are used to develop material balances for the four fuel cycle options. The fuel cycle options are compared on the bases of resource sustainability, waste management (both low- and high-level waste, including used nuclear fuel), and occupational radiological impacts. At steady-state, occupational doses somewhat favor the closed thorium option while low

On the radiology of thorium-uranium electro breeding

International Nuclear Information System (INIS)

Gai, E.V.; Rabotnov, N.S.; Shubin, Y.N.

1995-01-01

Radiological problems arising in thorium-uranium electro-breeding with thorium accelerator target are discussed. Following radiological problems are discussed and evaluated in simplified model calculations: U-232 formation, accumulation of light Th isotopes in (n, xn) reactions on thorium target: accumulation of the same nuclides in final repository after alpha-decay of uranium isotopes. The qualitative comparison of U-Pu and U-Th fuel cycles is performed. The problems seem to be serious enough to justify detailed quantitative investigation. (authors)

Road-map design for thorium-uranium breeding recycle in PWR - 031

International Nuclear Information System (INIS)

Shengyi, Si

2010-01-01

The paper was focused on designing a road-map to finally approach sustainable Thorium-Uranium ( 232 Th- 233 U) Breeding Recycle in current PWR, without any other change to the fuel lattice and the core internals, but substituting the UOX pellet with Thorium-based pellet. At first, the paper presented some insights to the inherence of Thorium-Uranium fuel conversion or breeding in PWR based on the neutronics theory and revealed the prerequisites for Thorium-Uranium fuel in PWR to achieve sustainable Breeding Recycle; And then, various Thorium-based fuels were designed and examined, and the calculation results further validated the above theoretical deductions; Based on the above theoretical analysis and calculation results, a road-map for sustainable Thorium-Uranium breeding recycle in PWR was outlined finally. (authors)

Quantitative regularities of magnesium, calcium, radium-226, and thorium migration from soils to plants

International Nuclear Information System (INIS)

Ashkinazi, Eh.I.

1980-01-01

Concentrations of magnesium, calcium, radium 226, thorium 228 in podsolized chernozem and grey medium-loamy soils were determined under conditions of ordinary farming. Concentrations of these elements were determined in soils and main agricultural plants: wheat, barley, peas, potatoes, beets, and carrots. Transition coefficients of magnesium, calcium, and radium 226 from soils to plants were calculated and the following series of transition coefficients were determined: to Mg> to Ca> to Ra. Transition coefficients from dern-podsolic soils were 3-27 times higher than from chernozem

Uranium, thorium and potassium contents and radioactive equilibrium states of the uranium and thorium series nuclides in phosphate rocks and phosphate fertilizers

Energy Technology Data Exchange (ETDEWEB)

Komura, K; Yanagisawa, M; Sakurai, J; Sakanoue, M

1985-10-01

Uranium, thorium and potassium contents and radioactive equilibrium states of the uranium and thorium series nuclides have been studied for 2 phosphate rocks and 7 phosphate fertilizers. Uranium contents were found to be rather high (39-117 ppm) except for phosphate rock from Kola. The uranium series nuclides were found to be in various equilibration states, which can be grouped into following three categories. Almost in the equilibrium state, 238U approximately 230Th greater than 210Pb greater than 226Ra and 238U greater than 230Th greater than 210Pb greater than 226Ra. Thorium contents were found to be, in general, low and appreciable disequilibrium of the thorium series nuclides was not observed except one sample. Potassium contents were also very low (less than 0.3% K2O) except for complex fertilizers. Based on the present data, discussions were made for the radiation exposure due to phosphate fertilizers.

Uranium and radium in Finnsjoen - an experimental approach for calculation of transfer factors

International Nuclear Information System (INIS)

Evans, S.; Bergman, R.

1981-01-01

The radiological safety studies for underground disposal of HLW show that the future individual and collective doses to an important extent may originate from groundwater borne radium and uranium which reach the biosphere. Indications that the dispersion rates presently used give rise to overestimations of calculated doses justified an investigation for more realistic turnover rates of radium and uranium than those which now are in use. Within one of the sites selected for testing, the area around lake Finnsjoen, a small number of environmental samples were collected and analyzed with respect to radium and uranium and the new transfer coefficients between soil and lake water were derived. The dose rates obtained with the new transfer factors show a close agreement for radium and a slight increase for uranium compared with earlier calculations. (Auth.)

Determination of transfer factors of uranium, thorium, radium and lead from soil to agricultural product in Japan for estimating internal radiation dose through ingestion

International Nuclear Information System (INIS)

Sasaki, Tomozo; Tashiro, Yoshikazu; Fujinaga, Hideshi; Ishii, Tomoaki; Gunji, Yasuyoshi

2002-01-01

The transfer factors (TFs) of uranium (U), thorium (Th), radium (Ra) and lead (Pb) from soil to agricultural products were determined in order to estimate the internal radiation dose to the human body through ingestion. Samples of rice, potato, onion, cabbage, mandarin orange, spinach, apple and soil were collected from various districts in Japan. After appropriate pretreatment of the samples, concentrations in the sample solutions were measured by Inductively coupled plasma-mass spectrometry (ICP-MS) (for U, Th and Pb) and liquid scintillation counter (for Ra). It was recognized that TFs were 4.9 x 10 -6 (apple) and 3.6 x 10 -4 (spinach) for U, 2.8 x 10 -6 (apple) and 2.3 x 10 -4 (spinach) for Th, and 4.0 x 10 -3 (hulled rice), 7.0 x 10 -5 (onion) and 5.0 x 10 -3 (hulled rice) for Pb. The TF of Ra, however, was not determined due to detection limitations. TF values obtained in the present study range from the same order of magnitude to 1/100 compared to the data in Technical Report Series No.364 (TRS364) as reported by IAEA. It was revealed that the internal radiation dose caused by the intake of uranium series radioactive nuclides through agricultural food ingestion was 16 μSv/y, where Pb was the most contributory nuclide. (author)

DH-1a: a certified uranium-thorium reference ore

International Nuclear Information System (INIS)

Steger, H.F.; Bowman, W.S.; Zechanowitsch, G.

1981-09-01

A 122-kg sample of uranium-thorium ore, DH-1a, from Elliot Lake, Ontario, was prepared as a compositional reference material to replace the similar certified ore, DH-1. DH-1a was ground to minus 74μm, blended in one lot, and bottled in 200 g units. The homogeneity of DH-1a with respect to uranium was confirmed using the volumetric umpire method. The recommended value for uranium is based on the data from the confirmation of homogeneity. For thorium, twelve laboratories provided results in a free choice analytical program. A statistical analysis of the data gave a recommended value of 0.263 percent for uranium and 0.091 percent for thorium

Evaluation of plutonium, uranium, and thorium use in power reactor fuel cycles

International Nuclear Information System (INIS)

Kasten, P.R.; Homan, F.J.

1977-01-01

The increased cost of uranium and separative work has increased the attractiveness of plutonium use in both uranium and thorium fuel cycles in thermal reactors. A technology, fuel utilization, and economic evaluation is given for uranium and thorium fuel cycles in various reactor types, along with the use of plutonium and 238 U. Reactors considered are LWRs, HWRs, LWBRs, HTGRs, and FBRs. Key technology factors are fuel irradiation performance and associated physical property values. Key economic factors are unit costs for fuel fabrication and reprocessing, and for refabrication of recycle fuels; consistent cost estimates are utilized. In thermal reactors, the irradiation performance of ceramic fuels appears to be satisfactory. At present costs for uranium ore and separative work, recycle of plutonium with thorium rather than uranium is preferable from fuel utilization and economic viewpoints. Further, the unit recovery cost of plutonium is lower from LWR fuels than from natural-uranium HWR fuels; use of LWR product permits plutonium/thorium fueling to compete with uranium cycles. Converting uranium cycles to thorium cycles increases the energy which can be extracted from a given uranium resource. Thus, additional fuel utilization improvement can be obtained by fueling all thermal reactors with thorium, but this requires use of highly enriched uranium; use of 235 U with thorium is most economic in HTGRs followed by HWRs and then LWRs. Marked improvement in long-term fuel utilization can be obtained through high thorium loadings and short fuel cycle irradiations as in the LWBR, but this imposes significant economic penalties. Similar operating modes are possible in HWRs and HTGRs. In fast reactors, use of the plutonium-uranium cycle gives advantageous fuel resource utilization in both LMFBRs and GCFRs; use of the thorium cycle provides more negative core reactivity coefficients and more flexibility relative to use of recycle fuels containing uranium of less than 20

The solubility of thorium and uranium from respirable monazite bearing dust in simulated lung and gut fluids

International Nuclear Information System (INIS)

Twining, J.; McGlinn, P.; Hart, K.

1993-01-01

The accurate assessment of the radiological dose to workers in the mineral sands industry requires information on the human bio-availability of thorium and uranium from monazite bearing respirable dust. The results of a short-term test to determine some of the solubility characteristics of these radionuclides are presented, together with a discussion on the optimum methods which may be applied to longer term studies. The solubility of thorium and uranium were found to be generally less than that of the parent monazite bearing dust in simulated lung and gut fluids over the one month extraction period. In particular, thorium was up to two orders of magnitude less soluble than its host mineral matrix. Assuming that the conservative nature of these radioactive constituents can be extrapolated to longer term exposures, these results imply that radiological dose estimates to the lung should be increased. Solubility of both elements was proportional to particle size. An exponential increase in solubility with decreasing diameter was observed, which implies a time variable solubility. There was also some indication of preferential solubility of radium progeny in both decay series. These factors may have to be accounted for in model estimates of committed dose. 16 refs., 4 tabs., 2 figs

Uranium- and thorium-bearing pegmatites of the United States

International Nuclear Information System (INIS)

Adams, J.W.; Arengi, J.T.; Parrish, I.S.

1980-04-01

This report is part of the National Uranium Resource Evaluation (NURE) Program designed to identify criteria favorable for the occurrence of the world's significant uranium deposits. This project deals specifically with uranium- and thorium-bearing pegmatites in the United States and, in particular, their distribution and origin. From an extensive literature survey and field examination of 44 pegmatite localities in the United States and Canada, the authors have compiled an index to about 300 uranium- and thorium-bearing pegmatites in the United States, maps giving location of these deposits, and an annotated bibliography to some of the most pertinent literature on the geology of pegmatites. Pegmatites form from late-state magma differentiates rich in volatile constituents with an attendant aqueous vapor phase. It is the presence of an aqueous phase which results in the development of the variable grain size which characterizes pegmatites. All pegmatites occur in areas of tectonic mobility involving crustal material usually along plate margins. Those pegmatites containing radioactive mineral species show, essentially, a similar distribution to those without radioactive minerals. Criteria such as tectonic setting, magma composition, host rock, and elemental indicators among others, all serve to help delineate areas more favorable for uranium- and thorium-bearing pegmatites. The most useful guide remains the radioactivity exhibited by uranium- and thorium-bearing pegmatites. Although pegmatites are frequently noted as favorable hosts for radioactive minerals, the general paucity and sporadic distribution of these minerals and inherent mining and milling difficulties negate the resource potential of pegmatites for uranium and thorium

Uranium- and thorium-bearing pegmatites of the United States

Energy Technology Data Exchange (ETDEWEB)

Adams, J.W.; Arengi, J.T.; Parrish, I.S.

1980-04-01

This report is part of the National Uranium Resource Evaluation (NURE) Program designed to identify criteria favorable for the occurrence of the world's significant uranium deposits. This project deals specifically with uranium- and thorium-bearing pegmatites in the United States and, in particular, their distribution and origin. From an extensive literature survey and field examination of 44 pegmatite localities in the United States and Canada, the authors have compiled an index to about 300 uranium- and thorium-bearing pegmatites in the United States, maps giving location of these deposits, and an annotated bibliography to some of the most pertinent literature on the geology of pegmatites. Pegmatites form from late-state magma differentiates rich in volatile constituents with an attendant aqueous vapor phase. It is the presence of an aqueous phase which results in the development of the variable grain size which characterizes pegmatites. All pegmatites occur in areas of tectonic mobility involving crustal material usually along plate margins. Those pegmatites containing radioactive mineral species show, essentially, a similar distribution to those without radioactive minerals. Criteria such as tectonic setting, magma composition, host rock, and elemental indicators among others, all serve to help delineate areas more favorable for uranium- and thorium-bearing pegmatites. The most useful guide remains the radioactivity exhibited by uranium- and thorium-bearing pegmatites. Although pegmatites are frequently noted as favorable hosts for radioactive minerals, the general paucity and sporadic distribution of these minerals and inherent mining and milling difficulties negate the resource potential of pegmatites for uranium and thorium.

Uranium and thorium recovery in thorianite ore-preliminary results

Energy Technology Data Exchange (ETDEWEB)

Gaiotte, Joao V.M. [Universidade Federal de Alfenas, Pocos de Caldas, MG (Brazil); Villegas, Raul A.S.; Fukuma, Henrique T., E-mail: rvillegas@cnen.gov.br, E-mail: htfukuma@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Pocos de Caldas, MG (Brazil). Lab. de Pocos de Caldas

2011-07-01

This work presents the preliminary results of the studies aiming to develop a hydrometallurgical process to produce uranium and thorium concentrates from thorianite ore from Amapa State, Brazil. This process comprises two major parts: acid leaching and Th/U recovery using solvent extraction strategies. Thorianite ore has a typical composition of 60 - 70% of thorium, 8 - 10% lead and 7 - 10% uranium. Sulfuric acid leaching operational conditions were defined as follows: acid/ore ratio 7.5 t/t, ore size below 65 mesh (Tyler), 2 hours leaching time and temperature of 100 deg C. Leaching tests results showed that uranium and thorium recovery exceeded 95%, whereas 97% of lead ore content remained in the solid form. Uranium and thorium simultaneous solvent extraction is necessary due to high sulfate concentration in the liquor obtained from leaching, so the Primene JM-T primary anime was used for this extraction step. Aqueous raffinate from extraction containing sulfuric acid was recycled to the leaching step, reducing acid uptake around 60%, to achieve a net sulfuric acid consumption of 3 t/t of ore. Uranium and thorium simultaneous stripping was performed using sodium carbonate solution. In the aqueous stripped it was added sulfuric acid at pH 1.5, followed by a second solvent extraction step using the tertiary amine Alamine 336. The following stripping step was done with a solution of sodium chloride, resulting in a final solution of 23 g L-1 uranium. (author)

Placement of radium/barium sludges in tailings areas

International Nuclear Information System (INIS)

Murphy, K.L.; Multamaki, G.E.

1980-01-01

Currently radium is removed from uranium mining and milling effluents by the addition of barium chloride to precipitate the radium as radium/barium sulphate. The precipitate is allowed to settle in sedimentation basins prior to discharge of the effluent. The sedimentation basins are not suitable for final disposal of the sludge, and placement of the sludges in the tailings area has been proposed. The geochemical environment of fresh tailings areas was characterized as an acidic, oxidized surface zone underlain by an alkaline, reduced zone comprising the rest of the tailings. The quantity of sludge produced was estimated to be small relative to the quantity of tailings, and therefor a relatively small amount of radium would be added to the tailings disposal area by the addition of sludge. To confirm whether sludge addition affected radionuclide solubilization, laboratory leaching tests were conducted on slurries of acid leach tailings, and sludge-tailings mixtures. Radium in the (Ra,Ba)SO 4 sludge was at least as stable as radium in the tailings, and the sludge was able to absorb radium released from the tailings. The addition of sludge did not affect uranium and thorium solubilization. From these results it appears that the placement of sludge in tailings areas would not adversely affect the stability of radionuclides in the tailings or sludge. (auth)

Certain distribution characteristics of uranium and thorium in apatite-carbonate ores

Energy Technology Data Exchange (ETDEWEB)

Kharitonova, R Sh; Faizullin, R N; Kozlov, E N; Berman, I B

1979-01-01

A study of the total radioactivity, uranium content, thorium content, U/Th ratio, and the spatial distribution of uranium by the f-radiographic method has demonstrated that the apatite ores of the deposit contain elevated concentrations of radioactive elements that are essentially of thorium origin. The main concentration of uranium and thorium is in the cinnemon-brown apatite. Elevated uranium concentrations are also found in hematite and accessory minerals (monacite, zirconium, titanite). Dolomite, quartz, martite, and second generation apatite were found to be weakly radioactive. The uranium and thorium concentration is correlated to the concentration of phosphorus and other petrogenic elements. An analysis of uranium, thorium, and Th/U distribution indicates that the concentration of radioactive elements is not caused by their primary content in carbonate rock but by the outside introduction of these elements together with phosphorus. The cited analyses confirm the chemogenic-sedimentary origin of the dolomite substrate and the metamorphogenic hydrothermal genesis of apatite mineralization. The data on radioactivity may be used as a reliable exploratory criterion for apatite potential. 3 references, 3 figures.

The Environmental Behaviour of Radium: Revised Ed

Energy Technology Data Exchange (ETDEWEB)

NONE

2014-03-15

A number of industrial activities produce residues containing either uranium or thorium series radionuclides or both. These include the mining and milling of uranium and of other metalliferous and non-metallic ores; the production of coal, oil and gas; the extraction and purification of water; and the production of industrial minerals such as phosphates. Residues from such activities have become of increasing interest from a radiological impact assessment point of view in recent years and isotopes of radium are often of particular interest in such assessments. The IAEA attaches high importance to the dissemination of information that can assist Member States with the implementation and improvement of activities related to radiation safety standards, including management of radioactive residues containing natural radionuclides, such as radium isotopes. In 1990, the IAEA published Technical Reports Series No. 310 (TRS 310), The Environmental Behaviour of Radium. Since the publication of TRS 310, a considerable number of publications related to the environmental behaviour of radium have appeared in the literature. It was therefore considered timely to produce a replacement report providing up to date information on key transfer processes, concepts and models that are important in radiological assessments and environmental applications of radium. This report outlines radium behaviour in terrestrial, freshwater and marine environments. The primary objective of the report is to provide IAEA Member States with information for use in the radiological assessment of accidental releases and routine discharges of radium in the environment, and in remediation planning for areas contaminated by radium. Additionally, applications of radium isotopes as tracers of environmental processes are discussed.

The Environmental Behaviour of Radium: Revised Ed

International Nuclear Information System (INIS)

2014-01-01

A number of industrial activities produce residues containing either uranium or thorium series radionuclides or both. These include the mining and milling of uranium and of other metalliferous and non-metallic ores; the production of coal, oil and gas; the extraction and purification of water; and the production of industrial minerals such as phosphates. Residues from such activities have become of increasing interest from a radiological impact assessment point of view in recent years and isotopes of radium are often of particular interest in such assessments. The IAEA attaches high importance to the dissemination of information that can assist Member States with the implementation and improvement of activities related to radiation safety standards, including management of radioactive residues containing natural radionuclides, such as radium isotopes. In 1990, the IAEA published Technical Reports Series No. 310 (TRS 310), The Environmental Behaviour of Radium. Since the publication of TRS 310, a considerable number of publications related to the environmental behaviour of radium have appeared in the literature. It was therefore considered timely to produce a replacement report providing up to date information on key transfer processes, concepts and models that are important in radiological assessments and environmental applications of radium. This report outlines radium behaviour in terrestrial, freshwater and marine environments. The primary objective of the report is to provide IAEA Member States with information for use in the radiological assessment of accidental releases and routine discharges of radium in the environment, and in remediation planning for areas contaminated by radium. Additionally, applications of radium isotopes as tracers of environmental processes are discussed

Early injuries on the tibia and vertebrae of the mouse after incorporation of thorium 227 and radium 224

Energy Technology Data Exchange (ETDEWEB)

Poemsl, H

1974-08-06

After incorporation of 5 and 50 ..mu..Ci/kg thorium 227 as well as 25 ..mu..Ci/kg radium 224, the tibia and lumbar vertebrae of the mouse were histologically and, using cell counting, morphometrically investigated within a period of 12 weeks. Osteoblasts and mesenchymal cells proved to be the most sensitive to radiation. They were temporarily decimated after 25 ..mu..Ci/kg radium 224 in the tibial metaphysis, but soon regenerated. After 5 ..mu..Ci/kg thorium 227, osteoblasts and mesenchymal cells were only slightly reduced, but more so in the lumbar vertebrae than in the tibia. The cells of osteogenic tissue were almost completely killed by 50 ..mu..Ci/kg thorium 227. In the subsequent regeneration phase, larger regions of atypical bone occured in the tibia metaphysis which was pushed off in the further course by newly formed compact substance of epiphysial cartilage.

Controlled synthesis of thorium and uranium oxide nano-crystals

International Nuclear Information System (INIS)

Hudry, Damien; Apostolidis, Christos; Walter, Olaf; Gouder, Thomas; Courtois, Eglantine; Kubel, Christian; Meyer, Daniel

2013-01-01

Very little is known about the size and shape effects on the properties of actinide compounds. As a consequence, the controlled synthesis of well-defined actinide-based nano-crystals constitutes a fundamental step before studying their corresponding properties. In this paper, we report on the non-aqueous surfactant-assisted synthesis of thorium and uranium oxide nano-crystals. The final characteristics of thorium and uranium oxide nano-crystals can be easily tuned by controlling a few experimental parameters such as the nature of the actinide precursor and the composition of the organic system (e.g., the chemical nature of the surfactants and their relative concentrations). Additionally, the influence of these parameters on the outcome of the synthesis is highly dependent on the nature of the actinide element (thorium versus uranium). By using optimised experimental conditions, monodisperse isotropic uranium oxide nano-crystals with different sizes (4.5 and 10.7 nm) as well as branched nano-crystals (overall size ca. 5 nm), nano-dots (ca. 4 nm) and nano-rods (with ultra-small diameters of 1 nm) of thorium oxide were synthesised. (authors)

49 CFR 173.426 - Excepted packages for articles containing natural uranium or thorium.

Science.gov (United States)

2010-10-01

... outer surface of the uranium or thorium is enclosed in an inactive sheath made of metal or other durable... uranium or thorium. 173.426 Section 173.426 Transportation Other Regulations Relating to Transportation....426 Excepted packages for articles containing natural uranium or thorium. A manufactured article in...

The uranium and thorium separation in the chemical reprocessing of the irradiated fuel of thorium and uranium mixed oxides

International Nuclear Information System (INIS)

Oliveira, E.F. de.

1984-09-01

A bibliographic research has been carried out for reprocessing techniques of irradiated thorium fuel from nuclear reactors. The Thorex/Hoechst process has been specially considered to establish a method for reprocessing thorium-uranium fuel from PWR. After a series of cold tests performed in laboratory it was possible to set the behavior of several parameters affecting the Thorex/Hoechst process. Some comments and suggestions are presented for modifications in the process flosheet conditions. A discussion is carried out for operational conditions such as the aqueous to organic flow ratio the acidity of strip and scrub solutions in the process steps for thorium and uranium recovery. The operation diagrams have been constructed using equilibrium experimental data which correspond to conditions observed in laboratory. (Author) [pt

Geological development and uranium and thorium evolutions in volcanic basin No.460

International Nuclear Information System (INIS)

Zhou Dean.

1989-01-01

On the basis of summarizing the geological features and the developmental history of tectono-magmatic activity, the uranium and thorium evolutional rules of rocks in different times are studied. It is suggested that the uranium and thorium increments caused by potassic migmatization of late Archean basement rocks in this area is the material base which affected the subsequent evolution of the cover of volcanic rocks and uranium mineralization. The Upper Jurassic acid volcanic cover belonging to crustal remelting origin constituted the favorable stratigraphic background for uranium mineralization in this area due to its wide distribution, large thickness, various rock associations and lithological sequences, as well as high content of uranium and thorium. During the late Yanshanian stage acid subvolanic rocks or small intrusions with high uranium intruded along the regional fractures are the decisive factors for the emplacement of uranium mineralization in this area, which othen became the favorable wall rocks for preserving ores itself. During the late stage the hydrothermal uranium mineralization was the main geological process from which uranium and thorium in stratigraphy and terrain were finally separated

Durability of adhesive bonds to uranium alloys, tungsten, tantalum, and thorium

International Nuclear Information System (INIS)

Childress, F.G.

1975-01-01

Long-term durability of epoxy bonds to alloys of uranium (U-Nb and Mulberry), nickel-plated uranium, thorium, tungsten, tantalum, tantalum--10 percent tungsten, and aluminum was evaluated. Significant strengths remain after ten years of aging; however, there is some evidence of bond deterioration with uranium alloys and thorium stored in ambient laboratory air

Sequential extraction procedure for determination of uranium, thorium, radium, lead and polonium radionuclides by alpha spectrometry in environmental samples

Science.gov (United States)

Oliveira, J. M.; Carvalho, F. P.

2006-01-01

A sequential extraction technique was developed and tested for common naturally-occurring radionuclides. This technique allows the extraction and purification of uranium, thorium, radium, lead, and polonium radionuclides from the same sample. Environmental materials such as water, soil, and biological samples can be analyzed for those radionuclides without matrix interferences in the quality of radioelement purification and in the radiochemical yield. The use of isotopic tracers (232U, 229Th, 224Ra, 209Po, and stable lead carrier) added to the sample in the beginning of the chemical procedure, enables an accurate control of the radiochemical yield for each radioelement. The ion extraction procedure, applied after either complete dissolution of the solid sample with mineral acids or co-precipitation of dissolved radionuclide with MnO2 for aqueous samples, includes the use of commercially available pre-packed columns from Eichrom® and ion exchange columns packed with Bio-Rad resins, in altogether three chromatography columns. All radioactive elements but one are purified and electroplated on stainless steel discs. Polonium is spontaneously plated on a silver disc. The discs are measured using high resolution silicon surface barrier detectors. 210Pb, a beta emitter, can be measured either through the beta emission of 210Bi, or stored for a few months and determined by alpha spectrometry through the in-growth of 210Po. This sequential extraction chromatography technique was tested and validated with the analysis of certified reference materials from the IAEA. Reproducibility was tested through repeated analysis of the same homogeneous material (water sample).

The cohesive energy of uranium dioxide and thorium dioxide

International Nuclear Information System (INIS)

Childs, B.G.

1958-08-01

Theoretical values have been calculated of the heats of formation of uranium dioxide and thorium dioxide on the assumption that the atomic binding forces in these solids are predominantly ionic in character. The good agreement found between the theoretical and observed values shows that the ionic model may, with care, be used in calculating the energies of defects in the uranium and thorium dioxide crystal structures. (author)

Simultaneous determination of uranium and thorium with Arsenazo III by second-derivative spectrophotometry

International Nuclear Information System (INIS)

Kuroda, Rokuro; Kurosaki, Mayumi; Hayashibe, Yutaka; Ishimaru, Satomi

1990-01-01

A derivative spectrophotometric method has been developed for the simultaneous determination of microgram quantities of uranium and thorium with Arsenazo III in hydrochloric acid medium. The second-derivative absorbances of the uranium and thorium Arsenazo III complexes at 679.5 and 684.4 nm are used for their quantification. Uranium and thorium, both in the range 0.1-0.7 μg/ml have been determined simultaneously with good precision. The procedure does not require separation of uranium and thorium, and allows the determination of both metals in the presence of alkaline-earth metals and zirconium, but lanthanides interfere. (author)

Radon/radium detection increases uranium drilling effectiveness

International Nuclear Information System (INIS)

Morse, R.H.; Cook, L.M.

1979-01-01

The use of portable radon detectors has become routine in reconnaissance uranium surveys where water and sediment samples are analyzed in field labs for radon and radium, and in detailed work where drill hole locations are pinpointed by field determinations of radon in soil gas from shallow holes. During the drilling program itself, however, very few operators are taking advantage of radon and radium analyses to decide whether a barren drill hole was a near miss or whether the immediate area can be written off. The technique, which is outlined here, is effective both above and below the water table

Method for analysing radium in powder samples and its application to uranium prospecting

International Nuclear Information System (INIS)

Gong Xinxi; Hu Minzhi.

1987-01-01

The decayed daughter of Rn released from the power sample (soil) in a sealed bottle were collected on a piece of copper and the radium in the sample can be measured by counting α-particles with an Alphameter for uranium prospection, thus it is called the radium method. This method has many advantages, such as high sensitivity (the lowest limit of detection for radium sample per gram is 2.7 x 10 -15 g), high efficiency, low cost and easy to use. On the basis of measuring more than 700 samples taken along 20 sections in 8 deposits, the results show that the radium method is better than γ-measurement and equal to 210 Po method for the capability to descover anomalies. The author also summarizes the anomaly intensities of radium method, 210 Po method and γ-measurement respectively at the surface with deep blind ores, with or without surficial mineralization, and the figures of their profiles and the variation of Ra/ 210 Po ratios. According to the above-mentioned distinguishing features, the uranium mineralization located in deep and/or shallow parts can be distinguishd. The combined application of radium, 210 Po and γ-measurement methods may be regarded as one of the important methods used for anomaly assessment. Based on the experiments of the radium measurements with 771 stream sediments samples in an area of 100 km 2 , it is demonstrated that the radium mehtod can be used in the stages of uranium reconnaissance and prospecting

Relative probabilities of the uranium isotopes for thorium x-ray emission and fluorescence of uranium x-rays

International Nuclear Information System (INIS)

Parker, J.L.

1991-01-01

Both thorium x-rays from decaying uranium isotopes and self-fluoresced uranium x-rays are prominent in high-resolution gamma-ray spectra of uranium-bearing materials. Useful application of the information carried by those x-rays has been curtailed because the probabilities of the uranium isotopes for thorium x-ray emission and for uranium x-ray fluorescence have not been known. By analyzing enrichment-meter geometry spectra from uranium oxide standards whose enrichments ranged from 0.7% to 91%, relative values, primarily, have been obtained for the probabilities of both processes. Thorium x-ray emission is very heavily dominated by 235 U. In all ordinarily occurring uranium isotopic distributions, thorium x-rays may be used as a valid 235 U signature. The probability for a thorium K α1 x-ray to be emitted in the decay of a 235 U atom is 0.048 ±0.002. In infinitely thick uranium oxide materials, the relative ratios of effectiveness for self-fluorescence, on a per unit mass basis, are approximately 234 U : 235 U : 236 U : 238 U = 1.13 : 1.00 : 0.52 : 0.028. on a per decay basis, the approximate ratios are 0.00039 : 1.00 : 0.017 : 0.18. These results imply that, contrary to what has often been stated, gamma rays are far more important than alpha particles in the self-fluorescence of uranium. Because of the importance of gamma-ray self-fluorescence, the uranium x-ray yield will be somewhat influenced by the size, shape, and composition of the materials. 4 refs., 1 fig

Potential of Melastoma malabathricum as bio-accumulator for uranium and thorium from soil

Energy Technology Data Exchange (ETDEWEB)

Saat, Ahmad, E-mail: ahmad183@salam.uitm.edu.my [Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Kamsani, Ain Shaqina; Kamri, Wan Nur Aina Nadzira; Talib, Nur Hasyimah Mat; Wood, Ab Khalik; Hamzah, Zaini [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia)

2015-04-29

Uranium and Thorium are naturally occuring radionuclides. However, due to anthropogenic activities in some locations their concentrations in the soils could be elevated. This study explores the potential of Melastoma malabathricum (locally known as ‘pokok senduduk’) as bio-accumulator of uranium and thorium from soils of three different study areas, namely former tin mining, industrial and residential/commercial areas in Peninsular Malaysia. The study found elevated concentrations of uranium and thorium in former tin mining soils as compared to natural abundance. However in industral and residential/commercial areas the concentrations are within the range of natural abundance. In terms of transfer factor (TF), in ex-mining areas TF > 1 for uranium in the leaf, stem and roots, indicating accumulation of uranium from soil. However for thorium TF < 1, indicating the occurence of transfer from soil to root, stem and leaf, but no accumulation. For other areas only transfer of uranium and thorium were observed. The results indicated the potential of Melastoma malabathricum to be used as bio-accumulatior of uranium, especially in areas of elevated concentration.

Potential of Melastoma malabathricum as bio-accumulator for uranium and thorium from soil

International Nuclear Information System (INIS)

Saat, Ahmad; Kamsani, Ain Shaqina; Kamri, Wan Nur Aina Nadzira; Talib, Nur Hasyimah Mat; Wood, Ab Khalik; Hamzah, Zaini

2015-01-01

Uranium and Thorium are naturally occuring radionuclides. However, due to anthropogenic activities in some locations their concentrations in the soils could be elevated. This study explores the potential of Melastoma malabathricum (locally known as ‘pokok senduduk’) as bio-accumulator of uranium and thorium from soils of three different study areas, namely former tin mining, industrial and residential/commercial areas in Peninsular Malaysia. The study found elevated concentrations of uranium and thorium in former tin mining soils as compared to natural abundance. However in industral and residential/commercial areas the concentrations are within the range of natural abundance. In terms of transfer factor (TF), in ex-mining areas TF > 1 for uranium in the leaf, stem and roots, indicating accumulation of uranium from soil. However for thorium TF < 1, indicating the occurence of transfer from soil to root, stem and leaf, but no accumulation. For other areas only transfer of uranium and thorium were observed. The results indicated the potential of Melastoma malabathricum to be used as bio-accumulatior of uranium, especially in areas of elevated concentration

Radium and uranium concentrations and associated hydrogeochemistry in ground water in southwestern Pueblo County, Colorado

Science.gov (United States)

Felmlee, J. Karen; Cadigan, Robert Allen

1979-01-01

Radium and uranium concentrations in water from 37 wells tapping the aquifer system of the Dakota Sandstone and Purgatoire Formation in southwestern Pueblo County, Colorado, have a wide range of values and define several areas of high radioactivity in the ground water. Radium ranges from 0.3 to 420 picocuries per liter and has a median value of 8.8, and uranium ranges from 0.02 to 180 micrograms per liter and has a median value of 2.4. Radon concentrations, measured in 32 of the 37 wells, range from less than 100 picocuries per liter to as much as 27,000 and have a median value of 580. Relationships among the radioactive elements and 28 other geochemical parameters were studied by using correlation coefficients and R-mode factor analysis. Five factor groups were determined to represent major influences on water chemistry: (1) short-term solution reactions, (2) oxidation reactions, (3) hydrolysis reactions, (4) uranium distribution, and (5) long-term solution reactions. Uranium concentrations are most strongly influenced by oxidation reactions but also are affected by solution reactions and distribution of uranium in the rocks of the aquifer system. Radon and radium concentrations are mostly controlled by uranium distribution; radium also shows a moderate negative relationship with oxidation. To explain the statistical and spatial relationships among the parameters, a model was developed involving the selective leaching of uranium-bearing phases and metal sulfides which occur in discontinuous zones in sandstone and shale. When reducing conditions prevail, uranium is immobile, but radium can be taken into solution. When faults and associated fractured rocks allow oxidizing conditions to dominate, uranium can be taken into solution; radium can also be taken into solution, or it may become immobilized by coprecipitation with iron and manganese oxides or with barite. Several areas within the study area are discussed in terms of the model.

A method for the quantitative determination of uranium-233 in an irradiated thorium rod; Une methode de dosage de l'uranium 233 contenu dans un barreau de thorium irradie

Energy Technology Data Exchange (ETDEWEB)

Bathellier, A; Sontag, R; Chesne, A [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1961-07-01

A rapid method for the quantitative determination of uranium-233 in irradiated thorium is described. A 30 per cent solution of trilaurylamine in xylene is used to extract the uranium from an aqueous hydrochloric acid solution and separate it from the thorium. This may be followed by {alpha} counting or fluorimetry. The practical operating conditions of the separation are discussed in detail. (author) [French] Une methode rapide de dosage de l'uranium-233 contenu dans le thorium irradie est decrite. Elle utilise la trilauryfamine a 30 pour cent dans le xylene pour extraire l'uranium d'une dissolution aqueuse chlorhydrique et le separer du thorium. Le comptage {alpha} ou la fluorimetrie sont alors possibles. Les conditions operatoires de la separation sont discutees et precisees. (auteur)

Uranium and thorium determination in water samples taken along River Kura

International Nuclear Information System (INIS)

Ahmadov, M.M.; Ibadov, N.A.; Safarova, K.S.; Humbatov, F.Y.; Suleymanov, B.A.

2014-01-01

Full text : In the present investigation, uranium and thorium concentration in rivers water of Azerbaijan has been measured using inductively coupled plasma mass spectrometry. The Agilent 7700x series ICP-MS applied for analysis of water samples. This method is based on direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma plasma mass spectrometer. Uranium and thorium was determined at the mass mass numbers of 238 and 232 respectively using Bi-209 as internal standard. The main purpose of the study is to measure the level of uranium and thorium in water samples taken along river Kura

Physicochemical aspects of extraction of uranium concentrate from the wastes and thermodynamic characteristics of thorium-uranium compounds

International Nuclear Information System (INIS)

Khamidov, F.A.

2017-01-01

The purpose of present work is elaboration of physicochemical aspects of extraction of uranium concentrate from the wastes and study of thermodynamic characteristics of thorium-uranium compounds. Therefore, the radiological monitoring of tailing dumps of Tajikistan has been conducted; the obtaining of uranium concentrate from the tailing dumps of uranium production has been studied; the obtaining of uranium concentrate from the tailing dumps of uranium production with application of local sorbents has been studied as well; thermal stability and thermodynamic characteristics of uranium-thorium compounds has been investigated; the flowsheets of extraction of uranium concentrate from the wastes have been elaborated.

Concentrations of uranium and thorium isotopes in uranium millers' and miners' tissues

International Nuclear Information System (INIS)

Wrenn, M.E.; Singh, N.P.; Paschoa, A.S.; Lloyd, R.D.; Saccomanno, G.

1985-09-01

The alpha-emitting isotopes of uranium and thorium were determined in the lungs of 14 former uranium miners and in soft tissues and bones of three miners and two millers. These radionuclides were also determined in soft tissues and bones of seven normal controls. The average concentrations in pCi/kg wet weight in 17 former miners' lungs are as follows: 238 U, 75; 234 U, 80; 230 Th, 79. Concentrations of each nuclide ranged from 2 to 325 pCi/kg. The average ratio of 238 U/ 234 U was 0.92, ranging from 0.64 to 1.06. The mean ratio of 230 Th/ 234 U was 1.04, ranging from 0.33 to 3.54. The near equilibrium between 230 Th and /sup 238,234/U indicates that the rate of elimination of uranium and thorium from lungs is the same in former uranium miners. The concentrations of 234 U and 238 U were highest in lung; however, the concentration of 230 Th in bones was either higher than or comparable to its concentration in lung. The concentration ratios of 230 Th/ 234 U in bone of uranium miners and millers measured in our laboratory have been compared with results predicted by ICRP-30 metabolic models. These results indicate that the ICRP metabolic models for thorium and uranium were only marginally successful in predicting the ratio of 230 Th/ 234 U in bones, and that effective release rate of uranium from skeleton may be more rapid than predicted by the ICRP model. 9 figs., 21 tabs

Uranium and radium activities in samples of aquifers of the main cities of the Estado de Chihuahua

International Nuclear Information System (INIS)

Villalba, L.; Colmenero S, L.; Montero C, M.E.

2003-01-01

The natural uranium is in four valence states +3, +4, +5 and +6 being the hexavalent state the more soluble, which plays an important role in the transport of the uranium in the environment. The high concentrations of uranium in water not only in near waters to uranium mines, but also are in some mineral waters or in waters that are extracted of deep wells as it happens in the State of Chihuahua, where the underground waters are the fundamental source of consumption. The radium is a disintegration product of the uranium, the radio content in water is considered the second source of natural radioactivity. The distribution of radium in water is in function of the uranium content present in the aquifer. It was determined the uranium and radium content in samples of underground water of the main cities of the State of Chihuahua according to their number of inhabitants. The extraction methods for uranium and sulfates precipitation of Ba-Ra by means of the addition of barium carriers for the radium were used. The measures of the activities of uranium and radium were carried out by means of a portable liquid scintillation detector trade mark Thiathler-OY HIDEX. The obtained results have demonstrated that the content of uranium and radium in dissolution are in most of the sampling wells above the permissible maximum levels that manage the Mexican regulations. The high contents of uranium and radio can be attributed since to the influence of the geologic substrate characteristic of the zone in the State of Chihuahua they exist but of 50 uranium deposits. (Author)

Uranium and thorium recovery from a sub-product of monazite industrial processing

International Nuclear Information System (INIS)

Gomiero, L.A.; Ribeiro, J.S.; Scassiotti Filho, W.

1994-01-01

In the monazite alkaline leaching industrial process for the production of rare earth elements, a by-product is formed, which has a high concentration of thorium and a lower but significant one of uranium. A procedure for recovery of the thorium and uranium contents in this by-product is presented. The first step of this procedure is the leaching with sulfuric acid, followed by uranium extraction from the acid liquor with a tertiary amine, stripping with a Na Cl solutions and precipitation as ammonium diuranate with N H 4 O H. In order to obtain thorium concentrates with higher purity, it is performed by means of the extraction of thorium from the acid liquor, with a primary amine, stripping by a Na Cl solution and precipitation as thorium hydroxide or oxalate. (author)

A new method for the determination of radium-228, thorium-228, and radium-224 in groundwaters via thoron (radon-220)

International Nuclear Information System (INIS)

Smith, M.R.; Lautensleger, A.W.; Laul, J.C.

1988-01-01

An improved method for determining radium and thorium from the 232 Th decay series has been developed which measures the activity of 220 Rn as an assay of its parents. Although some ingrowth corrections and minor separation procedures for Th are required, the results to date show that the dynamic counting of 220 Rn via de-emanation and alpha counting by the alpha-scintillation method is preferable. The method for lower limit detection depends on the emanation rate. (author) 3 refs.; 6 figs

Distribution of uranium and thorium in sediments and plants from a granitic fluvial area

International Nuclear Information System (INIS)

Vargas, M.J.; Tome, F.V.; Sanchez, A.M.; Vazquez, M.T.C.; Murillo, J.L.G.

1997-01-01

A study of the presence of natural uranium and thorium isotopes in sediments and plants belonging to a granitic fluvial region of the Ortigas river (west of Spain) has been carried out. The existence of two uranium mines in the neighbourhood of the sampled sites and the granitic characteristics of the zone produce significant concentrations of natural radionuclides. Temporal and spatial variations of uranium and thorium concentrations and the activity ratios 234 U/ 238 U, 228 Th/ 232 Th and Th/U were studied to better understand the mobilization mechanisms such as leaching and transport at play in the studied system. These determinations were made using alpha-particle spectrometry with silicon detectors. The measurements were also compared with the results previously found for waters of this fluvial area. Uranium in sediments showed variations due to changes in rainfall, but thorium content was nearly constant. Uranium and thorium concentrations in plants were lower after rainfall. Incorporation of uranium into the plants seemed to be mainly from water, whereas incorporation of thorium seemed to be from both sediments and water. (Author)

Uranium and thorium mining and milling: material security and risk assessment

International Nuclear Information System (INIS)

Steinhaeusler, F.; Zaitseva, L.

2005-01-01

Full text: At present physical protection for the front end of the nuclear fuel cycle is typically at a significantly lower level than at any other part of the nuclear fuel cycle. In view of past experiences (Israel, South Africa, Pakistan, India) it is feasible to take into consideration some generic threat scenarios, potentially resulting in loss of control over uranium or thorium, respectively their concentrates, such as: illegal mining of an officially closed uranium- or thorium mine; covert diversion of uranium- or thorium ore whilst officially mining another ore; covert transport of radioactive ore or product, using means of public rail, road, ship, or air transport; covert en route diversion of an authorized uranium- or thorium transport; covert removal of uranium-or thorium ore or concentrate from an abandoned facility. The Stanford-Salzburg database on nuclear smuggling, theft, and orphan radiation sources (DSTO) contains information on trafficking incidents involving mostly uranium, but also some thorium, from 30 countries in five continents with altogether 113 incidents in the period 1991 to 2004. These activities range from uranium transported in backpacks by couriers in Afghanistan, to a terrorist organization purchasing land in order to mine covertly for uranium in Australia, and the clandestine shipment of almost two tons of uranium hexafluoride from Asia to Africa, using the services of a national airline. Potential participants in such illegal operations range from entrepreneurs to members of organized crime, depending on the level of sophistication of the operation. End-users and 'customers' of such illegal operations are suspected to be non-state actors, organizations or governments involved in a covert operation with the ultimate aim to acquire a sufficient amount of nuclear material for a nuclear device. The actual risk for these activities to succeed in the acquisition of an adequate amount of suitable radioactive material depends on one or

Uranium and radium content in the soil solutions of the south-western part of Belarus

International Nuclear Information System (INIS)

Sokolik, G.A.; Ovsyannikova, S.V.; Vojnikova, E.V.; Popenya, M.V.

2008-01-01

The contents of uranium and radium in the pore soil solutions, which are the main chain in the geochemical and biological migration of the chemical elements, has been determined for the first time in Belarus. The control sites have been located outside the zone of Chernobyl fallout radionuclide contamination, that allowed evaluating the current background level of uranium and radium content in the soil solutions. The data on accumulation of the radioactive elements in the pore solutions give the opportunity to estimate the reserve of the radioactive elements in the migratory active forms in the soils. In the majority of soils studied, uranium content in the pore solution is higher than radium content, that points to the higher migratory ability of uranium. The direct correlation between content of fulvic acids' components in the soil solutions and accumulation of uranium in such solutions has been established. (authors)

Preliminary concepts: coordinated safeguards for materials management in a thorium--uranium fuel reprocessing plant

International Nuclear Information System (INIS)

Hakkila, E.A.; Barnes, J.W.; Dayem, H.A.; Dietz, R.J.; Shipley, J.P.

1978-10-01

This report addresses preliminary concepts for coordinated safeguards materials management in a typical generic thorium--uranium-fueled light-water reactor (LWR) fuels reprocessing plant. The reference facility is designed to recover thorium and uranium from first-generation (denatured 235 U) startup fuels, first-recycle and equilibrium (denatured 233 U) thorium--uranium LWR fuels, and to recover the plutonium generated in the 238 U denaturant as well. 12 figures, 3 tables

Landscape control of uranium and thorium in boreal streams – spatiotemporal variability and the role of wetlands

Directory of Open Access Journals (Sweden)

F. Lidman

2012-11-01

Full Text Available The concentrations of uranium and thorium in ten partly nested streams in the boreal forest region were monitored over a two-year period. The investigated catchments ranged from small headwaters (0.1 km² up to a fourth-order stream (67 km². Considerable spatiotemporal variations were observed, with little or no correlation between streams. The fluxes of both uranium and thorium varied substantially between the subcatchments, ranging from 1.7 to 30 g km⁻² a⁻¹ for uranium and from 3.2 to 24 g km⁻² a⁻¹ for thorium. Airborne gamma spectrometry was used to measure the concentrations of uranium and thorium in surface soils throughout the catchment, suggesting that the concentrations of uranium and thorium in mineral soils are similar throughout the catchment. The fluxes of uranium and thorium were compared to a wide range of parameters characterising the investigated catchments and the chemistry of the stream water, e.g. soil concentrations of these elements, pH, TOC (total organic carbon, Al, Si and hydrogen carbonate, but it was concluded that the spatial variabilities in the fluxes of both uranium and thorium mainly were controlled by wetlands. The results indicate that there is a predictable and systematic accumulation of both uranium and thorium in boreal wetlands that is large enough to control the transport of these elements. On the landscape scale approximately 65–80% of uranium and 55–65% of thorium entering a wetland were estimated to be retained in the peat. Overall, accumulation in mires and other types of wetlands was estimated to decrease the fluxes of uranium and thorium from the boreal forest landscape by 30–40%, indicating that wetlands play an important role for the biogeochemical cycling of uranium and thorium in the boreal forest landscape. The atmospheric deposition of uranium and thorium was also quantified, and its contribution to boreal streams was

Recovery of thorium and rare earths by their peroxides precipitation from a residue produced in the thorium purification facility; Recuperacao de torio e terras raras via peroxido do residuo originado na unidade de purificacao de torio

Energy Technology Data Exchange (ETDEWEB)

Freitas, Antonio Alves de

2008-07-01

As consequence of the operation of a Thorium purification facility, for pure Thorium Nitrate production, the IPEN (Instituto de Pesquisas Energeticas e Nucleares) has stored away a solid residue called RETOTER (REsiduo de TOrio e TErras Raras). The RETOTER is rich in Rare-Earth Elements and significant amount of Thorium-232 and minor amount of Uranium. Furthermore it contains several radionuclides from the natural decay series. Significant radioactivity contribution is generated by the Thorium descendent, mainly the Radium-228(T{sub 1/2}=5.7y), known as meso thorium and Thorium-228(T{sub 1/2} 1.90y). An important thorium daughter is the Lead-208, a stable isotope present with an expressive quantity. After the enclosure of the operation of the Thorium purification facility, many researches have been developed for the establishment of methodologies for recovery of Thorium, Rare-Earth Elements and Lead-208 from the RETOTER. This work presents a method for RETOTER decontamination, separating and bordering upon some radioactive isotopes. The residue was digested with nitric acid and the Radium-228 was separated by the Barium Sulphate co-precipitation procedure. Finally, the Thorium was separated by the peroxide precipitation and the Rare-Earth Elements were also recovered by the Rare-Earth peroxide precipitation in the filtrate solution.(author)

Gold, uranium and thorium in zones of greenschist displacement metamorphism

International Nuclear Information System (INIS)

Gavrilenko, B.V.; Savitskij, A.V.; Titov, V.V.

1987-01-01

Distribution of gold, uranium (bar and mobile) and thorium in 15 zones of greenschist dislocated metamorphism in different structures of the Karelo-Kola region carried out by geologic formations of the Early-Archean-Late-Proterozoic age has been studied. More than 200 samples of well core from 0-200 m depths have been analyzed. The results obtained testify to the increase of gold, uranium and less thorium content in zones of green-schist dislocated metamorphism in comparison with the enclosing rocks 1.4-3.1 times. The variation coefficient of gold, uranium and thorium content in green-schist dislocated tectonites increases 1.5-2.9 times. The correlation coefficient of Au/U mob. pair is +0.69, and Au/U bar pair -+0.87. Essential correlation between concentrations of all three elements in enclosing rocks is absent

Radionuclide migration around uranium ore bodies in the Alligator Rivers region of the Northern Territory, Australia - analogue of radioactive waste repositories

International Nuclear Information System (INIS)

Airey, P.L.; Roman, D.; Golian, C.; Short, S.; Nightingale, T.; Lowson, R.T.; Davey, B.G.; Gray, D.

1984-01-01

Appropriate geochemical analogues may be used to reduce the uncertainties in predicting the long-term transport of actinides, radium and fission products from laboratory adsorption and hydrological data. In this study the migration of uranium series nuclides within, and down-gradient of ore bodies in the Alligator Rivers uranium province of the Northern Territory of Australia is described. A mathematical framework was developed to permit calculation of the rate of leaching or deposition of uranium and radium between defined zones of the ore bodies, and the rate of loss of the nuclides due to groundwater transport and surface erosion. A detailed study was made of the distribution of uranium, thorium and radium isotopes within various minerals comprising the weathered ore assemblage. Uranium and thorium concentrate principally in the iron minerals and radium in the clay-quartz phases. Substantial disequilibria are observed, which are attributed to a combination of α-recoil and chemical effects. Evidence of the relative lability of iron phases is presented. The transport of uranium series nuclides in groundwater intersecting the deposits was investigated. Down-gradient of the Ranger One deposit, the maximum retardation factor of uranium is 250. The role of colloids in groundwater transport is being studied. Uranium is transported principally in solution. There appears to be an equilibrium between solute and articulate uranium

Different periods of uranium and thorium occurrence in Madagascar (1960)

International Nuclear Information System (INIS)

Moreau, M.

1960-01-01

In Madagascar, the first typical occurrences of thorium and uranium are about 500 million years old. Previously thorium and uranium were rather concentrated in the granitic and charnockitic zones, chiefly in minerals such as monazite, apatite and zircon. At the end of the Precambrian period, metasomatic granites occur especially in the anticlinal series (Andriba orthite granite). The granitization is followed by the formation of the main pegmatitic areas in the Island with Th-U niobotantalates, uraninite and beryl. The pegmatites are well developed in the synclinal series with a poor migmatization or no migmatization at all. In the same time a large uranium and thorium province with uranothorianite deposits appears within the calcomagnesian series of the Southern part of Madagascar. Later, large amounts of monazite were carried down to the detritic Karroo sediments during tile erosion of the metamorphic precambrian rocks. Monazite has been concentrated again by frequent marine incursions, till the present time. In the medium Karroo, near Folakara, uranium minerals occur in direct relation with carbonaceous material. Finally we must note the uranium occurrence in the pleistocene carbonaceous shales of Antsirabe basin, in contact with crystalline rocks. (author) [fr

Effects of solution pH and complexing reagents on uranium and thorium desorption under saturated equilibrium conditions

International Nuclear Information System (INIS)

Wang, Yug-Yea; Yu, C.

1992-01-01

Three contaminated bulk surface soils were used for investigating the effect of solution pH and complexing reagents on uranium and thorium desorption. At a low solution pH, the major chemical species of uranium and thorium, uranyl UO 2 +2 , thorium dihydroxide Th(OH) 2 +2 , and thorium hydroxide Th(OH) +3 , tend to form complexes with acetates in the solution phase, which increases the fractions of uranium and thorium desorbed into this phase. At a high solution pH, important uranium and thorium species such as uranyl tricarbonate complex UO 2 (CO) 33 -4 and thorium tetrahydroxide complex Th(OH) 4 tend to resist complexation with acetates. The presence of complexing reagents in solution can release radionuclides such as uranium and/or thorium from the soil to the solution by forming soluble complexes. Sodium bicarbonate (NaHCO 3 ) and diethylenetriaminepentaacetic acid (DTPA) are strong complex formers that released 38% to 62% of total uranium activity and 78% to 86% of total thorium activity, respectively, from the soil samples investigated. Solutions of 0.1 molar sodium nitrate (NaNO 3 ) and 0.1 molar sodium sulfate (Na 2 SO 4 ) were not effective complex formers with uranium and thorium under the experimental conditions. Fractions of uranium and thorium desorbed by 0.15g/200ml humic acid ranged from 4.62% to 6.17% and 1.59% to 7.09%, respectively. This work demonstrates the importance of a knowledge of solution chemistry in investigating the desorption of radionuclides

Reconnaissance study of the uranium and thorium contents of plutonic rocks of the southwestern Seward Peninsula, Alaska

International Nuclear Information System (INIS)

Miller, T.P.; Bunker, C.M.

1976-01-01

Large granitic Cretaceous plutons are exposed along and adjacent to an arcuate belt of igneous and high-grade metamorphic rocks in the southeastern Seward Peninsula of Alaska. Reconnaissance studies of these plutons have shown that the Darby pluton has well above average amounts of uranium and thorium (11.2 ppm and 58.7 ppm, respectively), the Kachauik pluton contains average to above average uranium and thorium (5.7 ppm and 22.5 ppm, respectively), and the Bendeleben pluton contains average amounts of uranium and thorium (3.4 ppm and 16.7 ppm, respectively). The three plutons show compositional and textural differences indicative of different source materials that may have controlled the distribution of uranium and thorium. The high uranium and thorium contents of the Darby pluton, similar to those of the Conway Granite of New Hampshire which has been mentioned as a possible low-grade thorium resource, suggest that this pluton may be a favorable area for economic concentrations of uranium and thorium

Sorption behaviour of uranium and thorium on cryptomelane-type hydrous manganese dioxide from aqueous solution

International Nuclear Information System (INIS)

El-Naggar, I.M.; El-Absy, M.A.; Abdel-Hamid, M.M.; Aly, H.F.

1993-01-01

The kinetics of sorption of uranium and thorium from aqueous nitrate solutions on cryptomelane-type hydrous manganese dioxide (CRYMO) was studied. The exchange of uranium is particle diffusion controlled while that of thorium is chemical reaction at the exchange sites. Sorption of uranium and thorium by CRYMO has been also studied as a function of metal concentrations and temperature. The sorption of both cations is found to be an endothermic process and increases markedly with temperature between 30 and 60 degree C. The sorption results have been analysed by the langmuir adsorption isotherm over the entire range of uranium and thorium concentrations investigated. 35 refs., 8 figs., 5 tabs

Comparison of the radiological impacts of thorium and uranium nuclear fuel cycles

International Nuclear Information System (INIS)

Meyer, H.R.; Witherspoon, J.P.; McBride, J.P.; Frederick, E.J.

1982-03-01

This report compares the radiological impacts of a fuel cycle in which only uranium is recycled, as presented in the Final Generic Environmental Statement on the Use of Recycle Plutonium in Mixed Oxide Fuel in Light Water Cooled Reactors (GESMO), with those of the light-water breeder reactor (LWBR) thorium/uranium fuel cycle in the Final Environmental Statement, Light Water Breeder Reactor Program. The significant offsite radiological impacts from routine operation of the fuel cycles result from the mining and milling of thorium and uranium ores, reprocessing spent fuel, and reactor operations. The major difference between the impacts from the two fuel cycles is the larger dose commitments associated with current uranium mining and milling operations as compared to thorium mining and milling. Estimated dose commitments from the reprocessing of either fuel type are small and show only moderate variations for specific doses. No significant differences in environmental radiological impact are anticipated for reactors using either of the fuel cycles. Radiological impacts associated with routine releases from the operation of either the thorium or uranium fuel cycles can be held to acceptably low levels by existing regulations

Separation and purification of uranium product from thorium in thorex process by precipitation technique

International Nuclear Information System (INIS)

Ramanujam, A.; Dhami, P.S.; Gopalakrishnan, V.; Mukherjee, A.; Dhumwad, R.K.

1989-01-01

A sequential precipitation technique is reported for the separation of uranium and thorium present in the uranium product stream of a single cycle 5 per cent TBP Thorex Process. It involves the precipitation of thorium as oxalate in 1M HNO 3 medium at 60-70degC and after filtration, precipitation of uranium as ammonium diuranate at 80-90degC from the oxalate supernatant. This technique has several advantages over the ion-exchange process normally used for treating these products. In order to meet the varying feed conditions, this method has been tested for feeds containing 10 g/1 uranium and 1-50 g/1 thorium in 1-6M HNO 3 . Various parameters like feed acidities, uranium and thorium concentrations, excess oxalic acid concentrations in the oxalate supernatant, precipitation temperatures, precipitate wash volumes etc. have been optimised to obtain more than 99 per cent recovery of thorium and uranium as their oxides with less than 50 ppm uranium losses to ammonium diuranate filtrate. The distribution patterns of different fission products and stainless steel corrosion products during various steps of this procedure have also been studied. For simulating the actual Thorex plant scale operation, experiments have been conducted with 25g and 100g lots of uranium per batch. (author). 6 tabs., 8 figs., 22 refs

Studies on supercritical fluid extraction behaviour of uranium and thorium nitrates using amides

International Nuclear Information System (INIS)

Sujatha, K.; Kumar, R.; Sivaraman, N.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2007-01-01

Supercritical fluid extraction studies of uranyl nitrate and thorium nitrate in mixture were carried out using various amides such as N,N-di(2-ethylhexyl) isobutyramide (D2EHIBA),N,N-dihexyl octanamide (DHOA) and Diisooctyl Butanamide (DiOBA). These studies established a preferential extraction of uranium over thorium. Among the various amides studied, D2EHIBA offered the best rate of preferential extraction of uranium over thorium. (author)

Uranium and thorium occurrences in New Mexico: distribution, geology, production, and resources. Appendix 1

International Nuclear Information System (INIS)

McLemore, V.T.

1983-09-01

The following compilation of uranium and thorium occurrences, prospects, deposits, and mines and their descriptions is the most comprehensive tabulation of natural-occurring radioactive occurrences in New Mexico to date. It is possible that many additional occurrences will be discovered in the future. For the purposes of this compilation any locality where uranium or thorium mineralization is reported or produced, or where uranium or thorium concentration exceeds 0.001%, or where the radioactivity is twice background radioactivity or greater is considered an occurrence

Eliminating radium from uranium mill acid effluent with barium chloride-sodium carbonate precipitation

International Nuclear Information System (INIS)

Xiao Jiayuan

1998-01-01

The eliminating radium procedure, barium chloride-sodium carbonate-sand filtering, being used, radium can be eliminated to 3.7 x 10 -2 Bq/L order of magnitude from uranium mill acid effluents which contain 3.7 Bq/L Ra and pH 6∼9 when Ba 2+ is added by 3∼5 mg per litre, Na 2 CO 3 5mg. The radium elimination rate is more than 90%

Uranium-thorium fuel cycle in a very high temperature hybrid system

International Nuclear Information System (INIS)

Hernandez, C.R.G.; Oliva, A.M.; Fajardo, L.G.; Garcia, J.A.R.; Curbelo, J.P.; Abadanes, A.

2011-01-01

Thorium is a potentially valuable energy source since it is about three to four times as abundant as Uranium. It is also a widely distributed natural resource readily accessible in many countries. Therefore, Thorium fuels can complement Uranium fuels and ensure long term sustainability of nuclear power. The main advantages of the use of a hybrid system formed by a Pebble Bed critical nuclear reactor and two Pebble Bed Accelerator Driven Systems (ADSs) using a Uranium-Thorium (U + Th) fuel cycle are shown in this paper. Once-through and two step U + Th fuel cycle was evaluated. With this goal, a preliminary conceptual design of a hybrid system formed by a Graphite Moderated Gas-Cooled Very High Temperature Reactor and two ADSs is proposed. The main parameters related to the neutronic behavior of the system in a deep burn scheme are optimized. The parameters that describe the nuclear fuel breeding and Minor Actinide stockpile are compared with those of a simple Uranium fuel cycle. (author)

Biomonitoring of environmental pollution by thorium and uranium in selected regions of the Republic of Kazakhstan

Energy Technology Data Exchange (ETDEWEB)

Zoriy, P., E-mail: p.zoriy@fz-juelich.d [Institute of Safety and Radiation Protection in the Environment, Forschungszentrum Juelich, D-52428 Juelich (Germany); Ostapczuk, P.; Dederichs, H.; Hoebig, J.; Lennartz, R.; Zoriy, M. [Institute of Safety and Radiation Protection in the Environment, Forschungszentrum Juelich, D-52428 Juelich (Germany)

2010-05-15

Two former uranium mines and a uranium reprocessing factory in the city of Aktau, Kazakhstan, may represent a risk of contaminating the surrounding areas by uranium and its daughter elements. One of the possible fingerprinting tools for studying the environmental contamination is using plant samples, collected in the surroundings of this city in 2007 and 2008. The distribution pattern of environmental pollution by uranium and thorium was evaluated by determining the thorium and uranium concentrations in plant samples (Artemisia austriaca) from the city of Aktau and comparing these results with those obtained for the same species of plants from an unpolluted area (town of Kurchatov). The determination of the uranium and thorium concentrations in different parts of A. austriaca plants collected from the analyzed areas demonstrated that the main contamination of the flora in areas surrounding the city of Aktau was due to dust transported by the wind from the uranium mines. The results obtained demonstrate that all the areas surrounding Aktau have a higher pollution level due to thorium and uranium than the control area (Kurchatov). A few 'hot points' with high concentrations of uranium and thorium were found near the uranium reprocessing factory and the uranium mines.

Uranium and thorium deposits of Northern Ontario

International Nuclear Information System (INIS)

Robertson, J.A.; Gould, K.L.

1983-01-01

This, the second edition of the uranium-thorium deposit inventory, describes briefly the deposits of uranium and/or thorium in northern Ontario, which for the purposes of this circular is defined as that part of Ontario lying north and west of the Grenville Front. The most significant of the deposits described are fossil placers lying at or near the base of the Middle Precambrian Huronian Supergroup. These include the producing and past-producing mines of the Elliot Lake - Agnew Lake area. Also included are the pitchblende veins spatially associated with Late Precambrian (Keweenawan) diabase dikes of the Theano Point - Montreal River area. Miscellaneous Early Precambrian pegmatite, pitchblende-coffinite-sulphide occurrences near the Middle-Early Precambrian unconformity fringing the Lake Superior basin, and disseminations in diabase, granitic rocks, alkalic complexes and breccias scattered throughout northern Ontario make up the rest of the occurrences

Analysis of Uranium and Thorium in Radioactive Wastes from Nuclear Fuel Cycle Process

International Nuclear Information System (INIS)

Gunandjar

2008-01-01

The assessment of analysis method for uranium and thorium in radioactive wastes generated from nuclear fuel cycle process have been carried out. The uranium and thorium analysis methods in the assessment are consist of Titrimetry, UV-VIS Spectrophotometry, Fluorimetry, HPLC, Polarography, Emission Spectrograph, XRF, AAS, Alpha Spectrometry and Mass Spectrometry methods. From the assessment can be concluded that the analysis methods of uranium and thorium content in radioactive waste for low concentration level using UV-VIS Spectrometry is better than Titrimetry method. While for very low concentration level in part per billion (ppb) can be used by Neutron Activation Analysis (NAA), Alpha Spectrometry and Mass Spectrometry. Laser Fluorimetry is the best method of uranium analysis for very low concentration level. Alpha Spectrometry and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) methods for isotopic analysis are favourable in the precision and accuracy aspects. Comparison of the ICP-MS and Alpha Spectrometry methods shows that the both of methods have capability to determining of uranium and thorium isotopes content in the waste samples with results comparable very well, but the time of its analysis using ICP-MS method is faster than the Alpha Spectrometry, and also the cost of analysis for ICP-MS method is cheaper. NAA method can also be used to analyze the uranium and thorium isotopes, but this method needs the reactor facility and also the time of its analysis is very long. (author)

Comparison studies adsorption of thorium and uranium on pure clay minerals and local Malaysian soil sediments

International Nuclear Information System (INIS)

Syed, H.S.

1999-01-01

Adsorption studies of thorium and uranium radionuclides on 9 different pure clay minerals and 4 local Malaysian soil sediments were conducted. Solution containing dissolved thorium and uranium at pH 4.90 was prepared from concentrate sludges from a long term storage facility at a local mineral processing plant. The sludges are considered as low level radioactive wastes. The results indicated that the 9 clay minerals adsorbed more uranium than thorium at pH ranges from 3.74 to 5.74. Two local Malaysian soils were observed to adsorb relatively high concentration of both radionuclides at pH 3.79 to 3.91. The adsorption value 23.27 to 27.04 ppm for uranium and 33.1 to 50.18 ppm for thorium indicated that both soil sediments can be considered as potential enhanced barrier material for sites disposing conditioned wastes containing uranium and thorium. (author)

United States Geological Survey: uranium and thorium resource assessment and exploration research program, fiscal year 1979

International Nuclear Information System (INIS)

Offield, T.W.

1978-01-01

Objectives and current plans are given for the following projects: uranium geochemistry and mineralogy; uranium in sedimentary environments; uranium in igneous and metamorphic environments; geophysical techniques in uranium and thorium exploration; and thorium investigations and resource assessment. Selected noteworthy results of FY 1978 research are given

Separation of protactinum, actinium, and other radionuclides from proton irradiated thorium target

Science.gov (United States)

Fassbender, Michael E.; Radchenko, Valery

2018-04-24

Protactinium, actinium, radium, radiolanthanides and other radionuclide fission products were separated and recovered from a proton-irradiated thorium target. The target was dissolved in concentrated HCl, which formed anionic complexes of protactinium but not with thorium, actinium, radium, or radiolanthanides. Protactinium was separated from soluble thorium by loading a concentrated HCl solution of the target onto a column of strongly basic anion exchanger resin and eluting with concentrated HCl. Actinium, radium and radiolanthanides elute with thorium. The protactinium that is retained on the column, along with other radionuclides, is eluted may subsequently treated to remove radionuclide impurities to afford a fraction of substantially pure protactinium. The eluate with the soluble thorium, actinium, radium and radiolanthanides may be subjected to treatment with citric acid to form anionic thorium, loaded onto a cationic exchanger resin, and eluted. Actinium, radium and radiolanthanides that are retained can be subjected to extraction chromatography to separate the actinium from the radium and from the radio lanthanides.

The selective uptake of uranium and thorium from the environment by some vegetables

International Nuclear Information System (INIS)

Yusof, A.M.; Ghazali, Z.; Abdul-Rahman, S.; Sharif, J.

1991-01-01

An attempt was made to establish baseline information on environmental pollution in locally-grown vegetables by uranium and thorium. Lowland and highland species together with soil and fertilizer samples were collected and analyzed using fluorimetry, spectrophotometry and delayed neutron counting techniques. All leafy vegetables observed showed high uranium and thorium uptake especially those grown in the lowlands. Those grown in the highlands reflected no direct relationship in uranium and thorium contents. Several species common in both sampling areas exhibited direct relationship between these two elements making them as potential bio-indicators. Figures calculated for fruit-type and leafy vegetables were not only comparatively low but bore no direct correlation between the two elements. The use of phosphate-based fertilizers on some of the leafy species in the lowlands did not enhance the uptake of these elements in spite of the higher uranium and thorium contents in soil samples from the lowlands, between 20-85 μg/g for uranium and 43-226 μg/g thorium compared to about 13-20 μg/g and 35-55 μg/g respectively for soil samples in the highlands. Statistical analysis was done to substantiate these findings. Climatic conditions were also taken into account as one of the factors affecting selective uptake of these elements in the vegetables

A passive technique using SSNTDs for Estimation of thorium to uranium ratios in rocks

International Nuclear Information System (INIS)

Kenawy, M.A.; Sayyah, T.A.; Said, A.F.; Hafez, A.F.

2005-01-01

A passive technique using plastic nuclear track detectors (CR-39 and LR-115) is presented to estimate Th/U ratios and consequently the thorium and uranium content in granites taken from uranium exploration mines in Egyptian desert. The registration sensitivities of both CR-39 and LR-115 detector for close contact alpha-radiography uranium and thorium concentrations in ppm were computed

Influence of the soil bioavailability of radionuclides on the transfer of uranium and thorium to mushrooms

Energy Technology Data Exchange (ETDEWEB)

Baeza, A. [Department of Physics, Faculty of Veterinary, University of Extremadura, Avda. Universidad s/n, 10071 Caceres (Spain)]. E-mail: ymiralle@unex.es; Guillen, J. [Department of Physics, Faculty of Veterinary, University of Extremadura, Avda. Universidad s/n, 10071 Caceres (Spain)

2006-09-15

The soil-mushroom transfer of thorium and uranium was analyzed in two ecologically similar but geographically separated Spanish ecosystems by means of the transfer factor, TF. Uranium TF values were in the range 0.043-0.49, and thorium TF values in the range 0.030-0.62. These values were similar to those of {sup 9}Sr, {sup 239+24}Pu, and {sup 241}Am found previously in the same ecosystems. Given the low availability of uranium and thorium, the available transfer factors, ATF, were also determined. These were higher than the TF values by one order of magnitude for {sup 234,238}U, and by 2-3 orders of magnitude for {sup 228,230,232}Th. The ATF value of thorium was similar to that of {sup 137}Cs, and that of uranium similar to that of {sup 4}K. Hebeloma cylindrosporum presented the highest uranium and thorium transfer factors, confirming this species as a good bioindicator of a soil's radioactive content.

Determination of microquantities of zirconium and thorium in uranium dioxide

International Nuclear Information System (INIS)

Weber de D'Alessio, Ana; Zucal, Raquel.

1975-07-01

A method for the determination of 10 to 50 ppm of zirconium and thorium in uranium IV oxide of nuclear purity is established. Zirconium and thorium are retained in a strong cation-exchange resin Dowex 50 WX8 in 1 M HCl. Zirconium is eluted with 0,5% oxalic acid solution and thorium with 4% ammonium oxalate. The colorimetric determination of zirconium with xilenol orange is done in perchloric acid after destructtion of oxalic acid and thorium is determined with arsenazo III in 5 M HCl. 10 μg of each element were determined with a standard deviation of 2,1% for thorium and 3,4% for zirconium. (author) [es

The measurements of critical mass with uranium fuel elements and thorium rods

International Nuclear Information System (INIS)

Yao Zhiquan; Chen Zhicheng; Yao Zewu; Ji Huaxiang; Bao Borong; Zhang Jiahua

1991-01-01

The critical experiments with uranium elements and Thorium rods have been performed in zero power reactor at Shanghai Institute of Nuclear Research. The critical masses have been measured in various U/Th ratios. The fuels are 3% 235 U-enriched uranium. The Thorium rods are made from power of ThF 4 . Ratios of calculated values to experimental values are nearly constant at 0.995

Determination of uranium and thorium isotopes by solid phase extraction and alpha spectrometry

International Nuclear Information System (INIS)

Kuruc, J.; Kovacova, M.; Strisovska, J.; Galanda, D.

2013-01-01

The aim of this work was to test the modified method suitable for the separation of isotopes of uranium and thorium samples of rocks, including gold ore and gold concentrate using of extraction chromatography method, after digestion of the sample, concentrating, separate the isotopes of uranium and thorium isotopes to prepare sources for the measurement of alpha spectra. Samples of rocks, gold ore and gold concentrate were digered in microwave decomposition in the environment of hydrogen peroxide and concentrated nitric acid. For the separation of uranium and thorium the vacuum box with cartridges DGA Resin and Resin(R) UTEVA (Triskem International, France) was used. Both sorbents allow separation of uranium from thorium. The results confirmed that the both sorbents give the same results within expanded uncertainty. The mass activity of monitored uranium and thorium radioisotopes was determined by alpha spectrometry method. The yields of separation were determined using uranium-232 as a tracer radionuclide; the activity of 232 U was 0.1438 Bq. Alpha spectra were measured on the Alpha spectrometer EG and G ORTEC 576A with the software MAESTRO, MCA Emulator and Gamma Vision-32 for Windows, USA. Mass activities of radionuclides were converted to mass concentration of isotopes 238 U, 234 U, 232 Th, 230 Th and 228 Th. The highest concentration of 238 U was sampled in granodiorite (Tunnel S-XIV-2, southwards, mining of Cu ore, not working there since 1990), where m( 238 U) = (0.81 ± 0.09) mg kg -1 (DGA Resin) and m( 238 U) = (0.90 ± 0.09) mg kg -1 (UTEVA(R) Resin), as well as m( 232 Th) = (18.8 ± 1.7) mg kg -1 (DGA Resin) and m( 232 Th) = (17.8 ± 1.5) mg kg -1 (UTEVA(R) Resin). In other samples of rocks, gold ore and gold concentrates have specific masses of isotopes of uranium and thorium two-to ten-folds lower. It can be concluded that the rocks, gold ores and concentrates of gold from the 'Rozalia' mine contain lower concentrations of uranium several times against

Alkaline autoclave leaching of refractory uranium-thorium minerals

International Nuclear Information System (INIS)

Milani, S. A.; Sam, S.

2011-01-01

This paper deals with the study of an innovative method for processing the Oman placer ores by alkaline leaching in ball mill autoclaves, where grinding and leaching of the refractory minerals take place simultaneously. This was followed by the selective separation of thorium and uranium from lanthanides by autoclave leaching of the hydroxide cake with ammonium carbonate-bicarbonate solutions. The introduced method is based on the fact that thorium and uranium form soluble carbonate complexes with ammonium carbonate, while lanthanides form sparingly soluble double carbonates. It was found that a complete alkaline leaching of Oman placer ores (98.0 P ercent ) was attained at 150 and 175 d egree C within 2.5 and 2h, respectively. Oman placer ores leaching was intensified and accelerated in a ball mill autoclaves as a result of the grinding action of steel balls, removal of the hydroxide layer covering ores grains and the continuous contact of fresh ore grains with alkaline solution. The study of selective carbonate processing of hydroxide cake with ammonium carbonate-bicarbonate solutions on autoclave under pressure revealed that the complete thorium recovery (97.5 P ercent ) with uranium recovery (90.8 P ercent ) and their separation from the lanthanides were attained at 70-80 d egree C during l-2h. The extraction of lanthanides in carbonate solution was low and did not exceed 4.6 P ercent .

Brazil's uranium/thorium deposits: geology, reserves, potential

International Nuclear Information System (INIS)

McNeil, M.

1979-01-01

With its area of 8.5 million square kilometers (3.3 million square miles) Brazil is the world's fifth largest nation, occupying almost one half of the continent of South America. Its vastness and its wide variety of geological terrain suggest that parts of Brazil may be favorable for many kinds of uranium deposits. The nation's favorability for uranium is indicated by the high correspondence between discoveries and the amount of exploration done to date. For the first time, the uranium and thorium resources of Brazil and their geologic setting are described here in a single volume. 270 refs

Uranium, radium and radon exhalation study in some soil samples using track etch technique

International Nuclear Information System (INIS)

Harmanjit, Singh; Joga, Singh; Surinder, Singh; Bajwa, B.S.

2006-01-01

Full text of publication follows: Uranium, radium concentration and radon exhalation rates have been determined in the soil samples collected from some areas of Punjab using the L.R.-115 nuclear track detectors. Radium concentration in these samples has been found to be varying from 0.80 to 5.34 Bq Kg-1. The radon exhalation rate in these samples has been found to be varying from 0.99 to 6.60 mBq Kg -1 h -1 (32.82 to 218.49 mBqm -2 h -1 ). A good correlation has been observed between radon exhalation rate and radium concentration observed in the soil samples. The uranium concentration in all these samples is being carried out and the other correlations will also be established. (authors)

Global Uranium And Thorium Resources: Are They Adequate To Satisfy Demand Over The Next Half Century?

Science.gov (United States)

Lambert, I. B.

2012-04-01

This presentation will consider the adequacy of global uranium and thorium resources to meet realistic nuclear power demand scenarios over the next half century. It is presented on behalf of, and based on evaluations by, the Uranium Group - a joint initiative of the OECD Nuclear Energy Agency and the International Atomic Energy Agency, of which the author is a Vice Chair. The Uranium Group produces a biennial report on Uranium Resources, Production and Demand based on information from some 40 countries involved in the nuclear fuel cycle, which also briefly reviews thorium resources. Uranium: In 2008, world production of uranium amounted to almost 44,000 tonnes (tU). This supplied approximately three-quarters of world reactor requirements (approx. 59,000 tU), the remainder being met by previously mined uranium (so-called secondary sources). Information on availability of secondary sources - which include uranium from excess inventories, dismantling nuclear warheads, tails and spent fuel reprocessing - is incomplete, but such sources are expected to decrease in market importance after 2013. In 2008, the total world Reasonably Assured plus Inferred Resources of uranium (recoverable at less than 130/kgU) amounted to 5.4 million tonnes. In addition, it is clear that there are vast amounts of uranium recoverable at higher costs in known deposits, plus many as yet undiscovered deposits. The Uranium Group has concluded that the uranium resource base is more than adequate to meet projected high-case requirements for nuclear power for at least half a century. This conclusion does not assume increasing replacement of uranium by fuels from reprocessing current reactor wastes, or by thorium, nor greater reactor efficiencies, which are likely to ameliorate future uranium demand. However, progressively increasing quantities of uranium will need to be mined, against a backdrop of the relatively small number of producing facilities around the world, geopolitical uncertainties and

Geochemistry of Thorium and Uranium in Soils of the Southern Urals

Science.gov (United States)

Asylbaev, I. G.; Khabirov, I. K.; Gabbasova, I. M.; Rafikov, B. V.; Lukmanov, N. A.

2017-12-01

Specific features of the horizontal and vertical distribution of uranium and thorium in soils and parent materials of the Southern Urals within the Bashkortostan Republic have been studied with the use of mass spectrometry with inductively coupled plasma. The dependence of distribution patterns of these elements on the local environmental conditions is shown. A scale for soil evaluation according to the concentrations of uranium and thorium (mg/kg) is suggested: the low level, up to 3; medium, up to 9; high, up to 15; and very high, above 15 mg/kg. On the basis of to this scale, the ecological state of the soils is evaluated, and the schematic geochemical map of the region is compiled. The territory of Bashkortostan is subdivided into two parts according to the contents of radioactive elements in soils: the western part with distinct accumulation of uranium and the eastern part with predominant thorium accumulation. This finding supports the charriage (thrust fault) nature of the fault zone of the Southern Urals. The vertical distribution patterns of uranium and thorium in soils of the region are of the same character. The dependence between the contents of these two elements and rare-earth elements has been established. The results of this study are applied for assessing the ecological state of soils in the region.

Kinetics of dissolution of thorium and uranium doped britholite ceramics

Energy Technology Data Exchange (ETDEWEB)

Dacheux, N., E-mail: nicolas.dacheux@univ-montp2.f [Groupe de Radiochimie, Institut de Physique Nucleaire d' Orsay, Bat. 100, Universite Paris-Sud-11, 91406 Orsay (France); Institut de Chimie Separative de Marcoule, UMR 5257 (Universite Montpellier 2/CNRS/CEA/ENSCM), Bat. 426, Centre de Marcoule, BP 17171, 30207 Bagnols sur ceze cedex (France); Du Fou de Kerdaniel, E. [Groupe de Radiochimie, Institut de Physique Nucleaire d' Orsay, Bat. 100, Universite Paris-Sud-11, 91406 Orsay (France); Clavier, N. [Groupe de Radiochimie, Institut de Physique Nucleaire d' Orsay, Bat. 100, Universite Paris-Sud-11, 91406 Orsay (France); Institut de Chimie Separative de Marcoule, UMR 5257 (Universite Montpellier 2/CNRS/CEA/ENSCM), Bat. 426, Centre de Marcoule, BP 17171, 30207 Bagnols sur ceze cedex (France); Podor, R. [Institut de Chimie Separative de Marcoule, UMR 5257 (Universite Montpellier 2/CNRS/CEA/ENSCM), Bat. 426, Centre de Marcoule, BP 17171, 30207 Bagnols sur ceze cedex (France); Institut Jean Lamour - Departement CP2S - Equipe 206, Faculte des Sciences et Techniques - Nancy Universite, BP 70239, 54506 Vandoeuvre les Nancy cedex (France); Aupiais, J. [CEA DAM DIF, 91297 Arpajon (France); Szenknect, S. [Institut de Chimie Separative de Marcoule, UMR 5257 (Universite Montpellier 2/CNRS/CEA/ENSCM), Bat. 426, Centre de Marcoule, BP 17171, 30207 Bagnols sur ceze cedex (France)

2010-09-01

In the field of immobilization of actinides in phosphate-based ceramics, several thorium and uranium doped britholite samples were submitted to leaching tests. The normalized dissolution rates determined for several pH values, temperatures and acidic media from the calcium release range from 4.7 x 10{sup -2} g m{sup -2} d{sup -1} to 21.6 g m{sup -2} d{sup -1}. Their comparison with that determined for phosphorus, thorium and uranium revealed that the dissolution is clearly incongruent for all the conditions examined. Whatever the leaching solution considered, calcium and phosphorus elements were always released with higher R{sub L} values than the other elements (Nd, Th, U). Simultaneously, thorium was found to quickly precipitate as alteration product, leading to diffusion phenomena for uranium. For all the media considered, the uranium release is higher than that of thorium, probably due to its oxidation from tetravalent oxidation state to uranyl. Moreover, the evaluation of the partial order related to proton concentration and the apparent energy of activation suggest that the reaction of dissolution is probably controlled by surface chemical reactions occurring at the solid/liquid interface. Finally, comparative leaching tests performed in sulphuric acid solutions revealed a significant influence of such media on the chemical durability of the leached pellets, leading to higher normalized dissolution rates for all the elements considered. On the basis of the results of chemical speciation, this difference was mainly explained in the light of higher complexion constants by sulfate ions compared to nitrate, chloride and phosphate.

Thorium, uranium and plutonium in human tissues of world-wide general population

International Nuclear Information System (INIS)

Singh, N.P.

1990-01-01

The results on the concentrations of thorium, uranium and plutonium in human tissues of world-wide general populations are summarized. The majority of thorium and uranium are accumulated in the skeleton, whereas, plutonium is divided between two major organs: the liver and skeleton. However, there is a wide variation in the fractions of plutonium in the liver and the skeleton of the different populations. (author) 44 refs.; 15 figs

Report on intercomparisons S-14, S-15, and S-16 of the determination of uranium and thorium in thorium ores

International Nuclear Information System (INIS)

Pszonicki, L.; Hanna, A.N.; Suschny, O.

1983-06-01

Twenty-nine laboratories from 18 countries took part in this intercomparison, organized by the IAEA's Analytical Quality Control Service, to help laboratories engaged in this task to check the reliability of their results. An additional aim was to establish the concentrations of thorium and uranium in three large batches of thorium ores and certifying them as reference materials. The evaluation was based on 438 individual results (108 laboratory means) for thorium, and on 412 individual results (106 laboratory means) for uranium. The number of laboratory means per element and per sample varied from 34 to 38. The methods most frequently used in the determination of both elements were neutron activation analysis and radiometry. They were followed by spectrophotometry and X-ray fluorescence analysis for thorium and by fluorimetry, X-ray fluorescence analysis and spectrophotometry for uranium determination, respectively. The relative uncertainty of all computed overall medians which were used as the best estimations of true values, does not exceed +-10% and +-5% for the concentration values below and above 0.1%, respectively

Analysis of Uranium and Thorium in Waste Water from Rare Earth Research and Development by ICP Spectrometry

International Nuclear Information System (INIS)

Pichestapong, Pipat; Injareon, Uthaiwan

2007-08-01

Full text: Waste water from Rare Earth Research and Development Center (RRDC) was analyzed to determine uranium and thorium concentration using ICP spectrometry. RRDC processes monazite ore to separate uranium, thorium and rare earth elements from the ore. Water samples from the ditch surrounding the center and from the canal nearby were also analyzed. Matrix spike technique was applied in this analysis. It was found that the highest concentration of uranium and thorium in the waste water samples were 3028±11 and 439±7 ppb, respectively. The concentration of uranium and thorium in the waste water samples were higher than those in water samples from the ditch and canal

Radium-226 in vegetation and substrates at inactive uranium mill sites

Energy Technology Data Exchange (ETDEWEB)

Marple, M.L.

1980-01-01

Results of a study of the content of radium-226 in plants growing on inactive uranium mill tailings sites in the Four Corners Region of the southwestern United States and in plants grown under greenhouse conditions with minimal surficial contamination are reported. Field plant samples and associated substrates were analyzed from two carbonate tailings sites in the Grants Mineral Belt of New Mexico. Radium activities in air-cleaned samples ranged from 5 to 368 pCi/g (dry weight) depending on species and location: activities in plants growing on local soils averaged 1.0 pCi/g. The talings and local soils contain 140 to 1400 pCi/g and 2.1 pCi/g, respectively. An evaluation of cleaning methods on selected samples showed that from 17 to 79% of the radium activity measured in air-cleaned samples was due to surficial contamination, which varied with species and location. A survey of 18 inactive uranium mill sites in the Four Corners Region was performed. Radium activity in plant tissues from nine species ranged from 2 to 210 pCi/g on bare tailings and from 0.3 to 30 pCi/g on covered tailings The radium content in most of the soil overburdens on the covered tailings piles was 10 to 17 pCi/g. An experiment was performed to measure radium-226 uptake by two species grown on tailings covered with a shallow (5 cm) soil layer. A grass, Sporobolus airoides (alkali sacaton) and a shrub, Atriplex canescens (four-wing saltbush), were studied. The tailings were a mixture of sands and slimes from a carbonate pile. The tailings treatments were plants grown in a soil cover over tailings; the controls were plants grown only in soil. Three soil types, dune sand, clay loam, and loam, were used. The radium activity of the plant tissue from the tailings treatment compared to that of the appropriate control was 1 to 19 times greater for the grass and 4 to 27 times greater for the shrub.

Radium-226 in vegetation and substrates at inactive uranium mill sites

International Nuclear Information System (INIS)

Marple, M.L.

1980-01-01

Results of a study of the content of radium-226 in plants growing on inactive uranium mill tailings sites in the Four Corners Region of the southwestern United States and in plants grown under greenhouse conditions with minimal surficial contamination are reported. Field plant samples and associated substrates were analyzed from two carbonate tailings sites in the Grants Mineral Belt of New Mexico. Radium activities in air-cleaned samples ranged from 5 to 368 pCi/g (dry weight) depending on species and location: activities in plants growing on local soils averaged 1.0 pCi/g. The talings and local soils contain 140 to 1400 pCi/g and 2.1 pCi/g, respectively. An evaluation of cleaning methods on selected samples showed that from 17 to 79% of the radium activity measured in air-cleaned samples was due to surficial contamination, which varied with species and location. A survey of 18 inactive uranium mill sites in the Four Corners Region was performed. Radium activity in plant tissues from nine species ranged from 2 to 210 pCi/g on bare tailings and from 0.3 to 30 pCi/g on covered tailings The radium content in most of the soil overburdens on the covered tailings piles was 10 to 17 pCi/g. An experiment was performed to measure radium-226 uptake by two species grown on tailings covered with a shallow (5 cm) soil layer. A grass, Sporobolus airoides (alkali sacaton) and a shrub, Atriplex canescens (four-wing saltbush), were studied. The tailings were a mixture of sands and slimes from a carbonate pile. The tailings treatments were plants grown in a soil cover over tailings; the controls were plants grown only in soil. Three soil types, dune sand, clay loam, and loam, were used. The radium activity of the plant tissue from the tailings treatment compared to that of the appropriate control was 1 to 19 times greater for the grass and 4 to 27 times greater for the shrub

Solid phase extraction of uranium and thorium on octadecyl bonded silica modified with Cyanex 302 from aqueous solutions

International Nuclear Information System (INIS)

Nilchi, A.; Shariati Dehaghan, T.; Rasouli Garmarodi, S.

2013-01-01

A simple and reliable method for rapid extraction and determination of uranium and thorium using octadecyl-bonded silica modified with Cyanex 302 is presented. Extraction efficiency and the influence of various parameters such as aqueous phase pH, flow rate of sample solution and amount of extractant has been investigated. The study showed that the extraction of uranium and thorium increase with increasing pH value and was found to be quantitative at pH 6; and the retention of ions was not affected significantly by the flow rate of sample solution. The extraction percent were found to be 89.55 and 86.27 % for uranium and thorium, respectively. The maximal capacity of the cartridges modified by 30 mg of Cyanex 302 was found to be 20 mg of uranium and thorium. The method was successfully applied to the extraction and determination of uranium and thorium in aqueous solutions. The percentage recovery of uranium and thorium in a number of natural as well as seawater samples of Iran were also investigated and found to be in the range of 85-95%. (author)

Simultaneous determinations of uranium, thorium, and plutonium in soft tissues by solvent extraction and alpha-spectrometry

International Nuclear Information System (INIS)

Singh, N.P.; Zimmerman, C.J.; Lewis, L.L.; Wrenn, M.E.

1984-01-01

A radiochemical procedure for the simultaneous determination of uranium, thorium, and plutonium, in soft tissues has been developed. The weighed amounts of tissues, spiked with 232 U, 242 Pu, and 229 th tracers, are wet ashed. Uranium, thorium, and plutonium are coprecipitated with iron as hydroxides, dissolved in concentrated HCl and the acidity adjusted to 10 M. Uranium and plutonium are extracted into 20% TLA solution in xylene, leaving thorium in the aqueous phase. Plutonium is back-extracted by reducing to the trivalent state with 0.05 M NH 4 I solution in 8 M HCl, and uranium is back-extracted with 0.1 M HCl. Thorium is extracted into 20% TLA solution from 4 M HNO 3 and back-extracted with 10 M HCl. Uranium, thorium and plutonium are electrodeposited separately onto platinum discs and counted alpha-spectrometrically using surface barrier silicon diodes and a multichannel analyzer. The method was developed using bovine liver and applied to dog and human tissues. The mean radiochemical recoveries of these actinides in different organs were better than 70%. 6 references, 2 tables

Thorium and uranium separation from Rare Earth complex minerals in Turkey

International Nuclear Information System (INIS)

Uzmen, R.

2014-01-01

Conclusion: • Thorium and uranium separation from a REEs solution is possible in by using simple traditional methods. • Main advantage of this method is to separate with high recovery yield uraniumand almost completely thorium which is an undesirable element due to its radioactive property in the different REEs group or individual REE. • Separation of thorium before any other step of REE’s group or individual element separation is crucial. • By using this flowsheet it would be possible to obtain uranium and other valuable elements (Zr, Ti, etc.) as coproducts of REEs. • Another important point, during REEs production, it is avoided to accumalate U and Th contaminated process wastes. • Thus, in the contrary, radioactive elements are refined and contained for safe storage.

Laser-induced breakdown spectroscopy measurements of uranium and thorium powders and uranium ore

Energy Technology Data Exchange (ETDEWEB)

Judge, Elizabeth J. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Barefield, James E., E-mail: jbarefield@lanl.gov [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Berg, John M. [Manufacturing Engineering and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Clegg, Samuel M.; Havrilla, George J.; Montoya, Velma M.; Le, Loan A.; Lopez, Leon N. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2013-05-01

Laser-induced breakdown spectroscopy (LIBS) was used to analyze depleted uranium and thorium oxide powders and uranium ore as a potential rapid in situ analysis technique in nuclear production facilities, environmental sampling, and in-field forensic applications. Material such as pressed pellets and metals, has been extensively studied using LIBS due to the high density of the material and more stable laser-induced plasma formation. Powders, on the other hand, are difficult to analyze using LIBS since ejection and removal of the powder occur in the laser interaction region. The capability of analyzing powders is important in allowing for rapid analysis of suspicious materials, environmental samples, or trace contamination on surfaces since it most closely represents field samples (soil, small particles, debris etc.). The rapid, in situ analysis of samples, including nuclear materials, also reduces costs in sample collection, transportation, sample preparation, and analysis time. Here we demonstrate the detection of actinides in oxide powders and within a uranium ore sample as both pressed pellets and powders on carbon adhesive discs for spectral comparison. The acquired LIBS spectra for both forms of the samples differ in overall intensity but yield a similar distribution of atomic emission spectral lines. - Highlights: • LIBS analysis of mixed actinide samples: depleted uranium oxide and thorium oxide • LIBS analysis of actinide samples in powder form on carbon adhesive discs • Detection of uranium in a complex matrix (uranium ore) as a precursor to analyzing uranium in environmental samples.

Distribution of uranium and radium radionuclides in the 'solid phase-interstitial soil solution' system and their migratory properties in ecosystems

International Nuclear Information System (INIS)

Sokolik, G.A.; Ovsyannikova, S.V.; Vojnikova, E.V.; Popenya, M.V.

2008-01-01

The background content of the main alpha-emitting radionuclides of uranium and radium in the soils of the south-east territory of the Republic of Belarus has been established. The reserve of migratory active species of uranium and radium in the soils has been determined using the data on the content of the radionuclides in the interstitial soil solutions, which are the most important chain of geochemical and biological migration of the chemical elements in ecosystems. The values of radionuclides distribution coefficients in the 'solid phase - interstitial solution of soil' system were estimated. It was shown that the migratory ability of uranium in the investigated soils is higher than that of radium. A direct correlation between the contents of organic components and uranium in the soil solution has been revealed. The used approach to the investigation of the uranium and radium behavior allows comparing their abilities to the migration in dependence of the soil medium peculiarities. (authors)

Migration of radium from the thorium ore deposit of Morro do Ferro, Pocos de Caldas, Brazil

International Nuclear Information System (INIS)

Campos, M.J.; Penna-Franca, E.; Lobao, N.; Trindade, H.; Sachett, I.

1986-01-01

A large thorium ore deposit is located in Morro de Ferro, a hill in the Pocos de Caldas Plateau, Minas Gerais, Brazil, which contains an estimated 30 000 t of Th and 100 t of U in a highly weathered matrix exposed to erosion and leaching. 228 Ra and 226 Ra were analyzed in surface waters collected at various points in the drainage basin and in groundwaters from wells drilled through and around the ore body. The concentrations in groundwater demonstrated that radium is markedly leached by rainwater percolating through the ore body. In its transit underground, radium is removed from groundwater by sorption on soil particles and this natural process greatly reduces the radium discharged to the environment. In dry weather, the concentration of dissolved 228 Ra in the main stream draining the Morro do Ferro is 7.0+-1.1 mBq litre -1 and in a control stream 1.6+-0.3 mBq litre -1 . The estimated 228 Ra mobilization rate by solubilization is of the order of 10 -7 y -1 . (author)

Recovery of thorium along with uranium 233 from Thorex waste solution employing Chitosan

International Nuclear Information System (INIS)

Priya, S.; Reghuram, D.; Kumaraguru, K.; Vijayan, K.; Jambunathan, U.

2003-01-01

The low level waste solution, generated from Thorex process during the processing of U 233 , contains thorium along with traces of Th 228 and U 233 . Chitosan, a natural bio-polymer derived from Chitin, was earlier used to recover the uranium and americium. The studies were extended to find out its thorium sorption characteristics. Chitosan exhibited very good absorption of thorium (350 mg/g). Chitosan was equilibrated directly with the low level waste solution at different pH after adjusting its pH, for 60 minutes with a Chitosan to aqueous ratio of 1:100 and the raffinates were filtered and analysed. The results showed more than 99% of thorium and U 233 could be recovered by Chitosan between pH 4 and 5. Loaded thorium and uranium could be eluted from the Chitosan by 1M HNO 3 quantitatively. (author)

Distribution of radium-226 body burden among workers in an underground uranium mine in India

International Nuclear Information System (INIS)

Patnaik, R.L.; Srivastava, V.S.; Kumar, Rajesh; Shukla, A.K.; Tripathi, R.M.; Puranik, V.D.

2007-01-01

Workers are exposed to ore dust containing uranium and its daughter products during mining and processing of uranium ore. These radio nuclides may be an inhalation hazard to the workers during the course of their occupation. The most significant among these radio nuclides is 226 Ra. Measurement of radium body burden of uranium mine and mill workers are important to control the exposure of workers within the prescribed limit. Radon-in-breath measurement technique is used for measurement of radium body burden. Workers associated with different category of underground mining operations were monitored. The measurement results indicate that workers associated with different category of underground mining operations are having 226 Ra body burden ranging from 0.15 - 2.85 kBq. It was also observed that workers involved in timbering operation are having maximum average 226 Ra body burden of 0.97 ± 0.54 kBq. Overall average radium body burden observed for 683 workers is 0.80 kBq. (author)

Average contents of uranium and thorium in the most important types of rocks of the Ukrainian shield

International Nuclear Information System (INIS)

Belevtsev, Ya.N.; Egorov, Yu.P.; Titov, V.K.; Sukhinin, A.M.; Grechishnikova, Z. M.; Zayats, V.B.; Tikhonenko, V.A.; Zhukova, A.M.

1975-01-01

The data given concern uranium and thorium contents in the most important rock types of the Ukraina shield. The smallest quantities of uranium are characteristic for the vulcanic rocks of basic and ultrabasic rocks. Archean formations, whose source materials were mainly basic and ultrabasic vulcanites, are marked by this low uranium content. The highest uranium content is observed in the clastogenic rocks of low Proterozoic. The average uranium content is observed in silty argellite rocks represented by crystal slates and paragneissis. Rheomorphic and metasomatic granites and granosyenites of low and middle Proterozoic are also characterized by an increased content of uranium. The platform precipitation rocks of high Proterozoic possess a relatively low uranium content. Thorium concentrations with low thorium-uranium proportions in granites, syenites and granosyenites prove their enrichment in uranium

Determination of ultratrace amounts of uranium and thorium in aluminium and aluminium alloys by electrothermal vaporization/ICP-MS

International Nuclear Information System (INIS)

Nakamura, Yasushi; Kobayashi, Yoshio; Kakurai, Yousuke

1993-01-01

A method has been developed for determining the 0.01 ng g -1 level of uranium and thorium in aluminium and aluminium alloys by electrothermal vaporization (ETV)/ICP-MS. This method was found to be significantly interfered with any matrices or other elements contained. An ion-exchange technique was therefore applied to separate uranium and thorium from aluminium and other elements. It was known that uranium are adsorbed on an anion-exchange resin and thorium are adsorbed on cation-exchange resin. However, aluminium and copper were eluted with 6 M hydrochloric acid. Dissolve the sample with hydrochloric acid containing copper which was added for analysis of pure aluminium, and oxidize with hydrogen peroxide. Concentration of hydrochloric acid in the solution was adjusted to 6 M, and then passed the solution through the mixed ion-exchange resin column. After the uranium and thorium were eluted with 1 M hydrofluoric acid-0.1 M hydrochloric acid, the solution was evaporated to dryness. It was then dissolved with 1 M hydrochloric acid. Uranium and thorium were analyzed by ETV/ICP-MS using tungsten and molybdenum boats, respectively, since the tungsten boat contained high-level thorium and the molybdenum boat contained uranium. The determination limit of uranium and thorium were 0.003 and 0.005 ng g -1 , respectively. (author)

Sorption of Uranium(VI and Thorium(IV by Jordanian Bentonite

Directory of Open Access Journals (Sweden)

Fawwaz I. Khalili

2013-01-01

Full Text Available Purification of raw bentonite was done to remove quartz. This includes mixing the raw bentonite with water and then centrifuge it at 750 rpm; this process is repeated until white purified bentonite is obtained. XRD, XRF, FTIR, and SEM techniques will be used for the characterization of purified bentonite. The sorption behavior of purified Jordanian bentonite towards and Th4+ metal ions in aqueous solutions was studied by batch experiment as a function of pH, contact time, temperature, and column techniques at 25.0∘C and . The highest rate of metal ions uptake was observed after 18 h of shaking, and the uptake has increased with increasing pH and reached a maximum at . Bentonite has shown high metal ion uptake capacity toward uranium(VI than thorium(IV. Sorption data were evaluated according to the pseudo- second-order reaction kinetic. Sorption isotherms were studied at temperatures 25.0∘C, 35.0∘C, and 45.0∘C. The Langmuir, Freundlich, and Dubinin-Radushkevich (D-R sorption models equations were applied and the proper constants were derived. It was found that the sorption process is enthalpy driven for uranium(VI and thorium(IV. Recovery of uranium(VI and thorium(IV ions after sorption was carried out by treatment of the loaded bentonite with different concentrations of HNO3 1.0 M, 0.5 M, 0.1 M, and 0.01 M. The best percent recovery for uranium(VI and thorium(IV was obtained when 1.0 M HNO3 was used.

Leaching of radium from mine deposits - application for planning of ground reclamation

International Nuclear Information System (INIS)

Chalupnik, S.

2002-01-01

Saline waters occurring in underground coal mines in Poland often contain natural radioactive isotopes, mainly 226 Ra from uranium series and 228 Ra from thorium series. Approximately 40% of total amount of radium remains underground in a form of radioactive deposits, but 225 MBq of 226 Ra and 400 MBq of 228 Ra are released daily into the rivers with mine effluents through surface settling ponds. Very peculiar situation is observed in coal mines, where as a result of precipitation of radium from radium-bearing waters radioactive deposits are formed. Sometimes natural radioactivity of such materials is very high, in case of scaling from coal mines radium concentration may reach 400000 Bq/kg - similar activity as for 3% uranium ore. Usually such deposits can be found underground, but sometimes co-precipitation of radium and barium takes place on the surface, in settling pond and in rivers. Therefore maintenance of solid and liquid waste with technologically enhanced natural radioactivity (TENORM) is a very important subject. Lately another problem appeared - due to the decrease of the production in Poland coal industry and dismantling of several coal mines, also the ground reclamation should be done in their vicinity. But in several cases deposits in the ponds contain enhanced levels of radium concentration. Therefore laboratory tests were done to investigate a possibility of the re-entry of radium into ground water or river waters from such deposits. Results show, that in the case of insoluble barium and radium sulphates co-precipitated out from waters type A, re-entry ratio is very small. Different situation can be observed in case of radium, adsorbed on bottom of sediments from waters type B, because re-entry ratio is much higher. Nevertheless, this phenomenon seems to be not so important and significant for the further pollution of the adjacent areas of the settling ponds in the future. (author)

Denver Radium Site -- Operable Unit I closeout report for the US Environmental Protection Agency

International Nuclear Information System (INIS)

1992-08-01

The Denver Radium Site consists of properties in the Denver, Colorado, area having radioactive contamination left from radium processing in the early 1900s. The properties are divided into 11 gaps or operable units to facilitate remedial action of the Site. Operable Unit I is an 8-acre block bounded by Quivas Street to the east, Shoshone Street to the west, West 12th Avenue to the south, and West 13th Avenue to the north. The primary focus of interest concerning investigations of radiological contamination was a radium, vanadium, and uranium processing facility at 1201 Quivas Street owned by the Pittsburgh Radium Company (PRC) from 1925 until 1926. The Radium Ores Company, which was associated with PRC, operated the facility until 1927. A Remedial investigation (RI) of Operable Unit I was prepared by Jacobs Engineering Group and CH 2 M Hill on behalf of EPA in April 1986. The draft Feasibility Study (FS), prepared by Jacobs Engineering Group and CH 2 M Hill, was issued in July 1987 (the final FS is the Community Relations Responsiveness Summary with an errata to the draft, issued September 1987). The RI focused on radium uranium processing residues discarded in the early 1900s. These residues contained uranium, radium, and thorium. EPA s Community Relations Plan involved the community in the decision-making process relating to the remedy to be implemented at Operable Unit X, and promoted communications among interested parties throughout the course of the project. The remedial action alternative preferred by EPA for Operable Unit I was Off-Site Permanent Disposal. Because a permanent disposal facility was not available at the time the Record of Decision was issued in September 1987, EPA selected the On-Site Temporary Containment (capping) with the Off-Site Permanent Disposal alternative

Decommissioning of nuclear facilities involving operations with uranium and thorium

International Nuclear Information System (INIS)

Shum, E.Y.; Neuder, S.M.

1990-01-01

When a licensed nuclear facility ceases operation, the U.S. Nuclear Regulatory Commission (NRC) ensures that the facility and its site are decontaminated to acceptable levels so they may safely be released for unrestricted public use. Because specific environmental standards or broad federal guidelines governing release of residual radioactive contamination have not been issued, NRC has developed ad hoc cleanup criteria for decommissioning nuclear facilities that involved uranium and thorium. Cleanup criteria include decontamination of buildings, equipment, and land. We will address cleanup criteria and their rationale; procedures for decommissioning uranium/thorium facilities; radiological survey designs and procedures; radiological monitoring and measurement; and cost-effectiveness to demonstrate compliance

Arbuscular mycorrhiza reduces phytoextraction of uranium, thorium and other elements from phosphate rock

DEFF Research Database (Denmark)

Roos, Per; Jakobsen, Iver

2008-01-01

Uptake of metals from uranium-rich phosphate rock was studied in Medicago truncatula plants grown in symbiosis with the arbuscular mycorrhizal fungus Glomus intraradices or in the absence of mycorrhizas. Shoot concentrations of uranium and thorium were lower in mycorrhizal than in non-mycorrhizal......-fungus uptake systems. The results support the role of arbuscular mycorrhiza as being an important component in phytostabilization of uranium. This is the first study to report on mycorrhizal effect and the uptake and root-to-shoot transfer of thorium from phosphate rock. (c) 2007 Elsevier Ltd. All rights...

Processing of Indian monazite for the recovery of thorium and uranium values

International Nuclear Information System (INIS)

Mukherjee, T.K.

2004-01-01

The mineral monazite, a phosphate of rare earths and thorium with significant quantity of uranium is one of the six heavy minerals present in the beach sands of specific coastal areas of India. Indian Rare Earths Ltd is mining and processing monazite at its Rare Earths Division for the last many decades with an aim of building up enough stock of thorium concentrate for its future use in the three stage nuclear power programme of the country. The present paper briefly describes the monazite resource position of he country, the past and present modified processing schemes and the future programme commensurate with the requirement of the country for quality thorium and uranium bearing nuclear materials

Methods for obtaining sorption data from uranium-series disequilibria

International Nuclear Information System (INIS)

Finnegan, D.L.; Bryant, E.A.

1987-12-01

Two possible methods have been identified for obtaining in situ retardation factors from measurements of uranium-series disequilibria at Yucca Mountain. The first method would make use of the enhanced 234 U/ 238 U ratio in groundwater to derive a signature for exchangeable uranium sorbed on the rock; the exchangeable uranium would be leached and assayed. The second method would use the ratio of 222 Rn to 234 U in solution, corrected for weathering, to infer the retardation factor for uranium. Similar methods could be applied to thorium and radium

On origin of radium aureoles around Triassic uranium mineralization zones in the Peribaltic Syneclize

International Nuclear Information System (INIS)

Szewczyk, J.

1985-01-01

In the second half of the seventies, the Geological Institute began search for sandstone uranium deposits in the Triassic of the Peribaltic Syneclize. Detailed analysis of both laboratory and geophysical data showed presence of radium (Ra-226) aureoles around uranium ore bodies hitherto found by drillings. The mechanism of origin of the aureoles is explained and methodological proposal of their use in further search for uranium deposits is given. Theoretical modelling showed that origin of the aureoles is mainly related to movement of deposit waters percolating through uranium ore body. The influence of shape and dimensions of radium aureole-generating ore bodies on extent of the aureoles appears subordinate. Aureoles interesting from the point of view of prospecting may originate when velocity of percolating waters falls within the range from 10 -8 to 10 -6 cm/s. 23 refs., 7 figs., 1 tab. (author)

Potency of Thorium and Uranium in West Bangka Region

International Nuclear Information System (INIS)

Ngadenin; Heri Syaeful; Kurnia Setiawan Widana; Muhammad Nurdin

2014-01-01

Thorium and uranium in Bangka Island are mainly found in monazite mineral. In the geological point of view the monazite formed in S type granite, sandstones and alluvial deposits. In Bangka Barat where several S types granite and also alluvial deposits and this area considered as a potential area for monazite placer. S type granites are predicted as a source of monazite while alluvial deposits are considered as a dispersion place for deposition of monazite. The purpose of this study is to determine the geological information and to know the hypothetical potency of thorium and uranium resources in alluvial deposits. The methods used in this study are geological mapping, measurement of thorium and uranium contents in the rock, sampling of granite for petrographic analysis, sampling of heavy mineral in alluvial deposits for grain size analysis. Results of the research show that the lithology of West Bangka region composed of schist unit, meta-sandstone unit, granite intrusion, diabase intrusion, sandstone unit and alluvial deposits. Monazite is found in granite intrusion, sandstone unit and alluvial deposits. Evolving fault strand to northwest-southeast, northeast-southwest and west-east. The results of the grain size analysis of heavy mineral shows the average percentage of monazite in the heavy mineral is 6.34%. Other potential minerals contained in placer deposits are zircon 36.65%, ilmenite 19.67% and cassiterite 14.75%. (author)

Acid pressure leaching of a concentrate containing uranium, thorium and rare earth elements

International Nuclear Information System (INIS)

Lan Xinghua; Peng Ruqing.

1987-01-01

The acid pressure leaching of a concentrate containing rinkolite for recovering uranium, thorium and rare earth elements is described. The laboratory and the pilot plant test results are given. Under the optimum leaching conditions, the recovery of uranium, thorium and rare earth elements are 82.9%, 86.0% and 88.3% respectively. These results show that the acid pressure leaching process is a effective process for treating the concentrate

A new method for determining the uranium and thorium distribution in volcanic rock samples using solid state nuclear track detectors

International Nuclear Information System (INIS)

Misdaq, M.A.; Bakhchi, A.; Ktata, A.; Koutit, A.; Lamine, J.; Ait nouh, F.; Oufni, L.

2000-01-01

A method based on using solid state nuclear track detectors (SSNTD) CR- 39 and LR-115 type II and calculating the probabilities for the alpha particles emitted by the uranium and thorium series to reach and be registered on these films was utilized for uranium and thorium contents determination in various geological samples. The distribution of uranium and thorium in different volcanic rocks has been investigated using the track fission method. In this work, the uranium and thorium contents have been determined in different volcanic rock samples by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD). The mean critical angles of etching of the solid state nuclear track detectors utilized have been calculated. A petrographical study of the volcanic rock thin layers studied has been conducted. The uranium and thorium distribution inside different rock thin layers has been studied. The mechanism of inclusion of the uranium and thorium nuclei inside the volcanic rock samples studied has been investigated. (author)

Investigation and analytical application of thorium and uranium complexes with amino acids

International Nuclear Information System (INIS)

Korenman, I.M.; Sergeev, G.M.

1979-01-01

The coordination is investigated of thorium (4) and uranium (6) with aminoacids, particularly, with aspartic acid. With the latter the metals form chelates, which have a particular structure and a stationary inner sphere. A description is made of the composition, conditions of formation (gr H), and a stability of some asparaginate complexes of actinoids, the coordination methods of aspartic acid. An asparaginatometric method is proposed for a direct complexometric titration of microgram amounts of thorium in the presence of uranium, zirconium and rare earth elements with photometric indication. As metal-chromic indicators the sulfophthaleins are applied. The given procedure allows measurement of impurities of accompanying elements, viz., beryllium (up to 1%) in thorium preparations. Application of aspartic acid and arsenazo 1 indicator permits us to define Be(2) with a relative error not higher than 5% in thorium compounds, which exclude the analysis by other methods

Retardation of uranium and thorium by a cementitious backfill developed for radioactive waste disposal.

Science.gov (United States)

Felipe-Sotelo, M; Hinchliff, J; Field, L P; Milodowski, A E; Preedy, O; Read, D

2017-07-01

The solubility of uranium and thorium has been measured under the conditions anticipated in a cementitious, geological disposal facility for low and intermediate level radioactive waste. Similar solubilities were obtained for thorium in all media, comprising NaOH, Ca(OH) 2 and water equilibrated with a cement designed as repository backfill (NRVB, Nirex Reference Vault Backfill). In contrast, the solubility of U(VI) was one order of magnitude higher in NaOH than in the remaining solutions. The presence of cellulose degradation products (CDP) results in a comparable solubility increase for both elements. Extended X-ray Absorption Fine Structure (EXAFS) data suggest that the solubility-limiting phase for uranium corresponds to a becquerelite-type solid whereas thermodynamic modelling predicts a poorly crystalline, hydrated calcium uranate phase. The solubility-limiting phase for thorium was ThO 2 of intermediate crystallinity. No breakthrough of either uranium or thorium was observed in diffusion experiments involving NRVB after three years. Nevertheless, backscattering electron microscopy and microfocus X-ray fluorescence confirmed that uranium had penetrated about 40 μm into the cement, implying active diffusion governed by slow dissolution-precipitation kinetics. Precise identification of the uranium solid proved difficult, displaying characteristics of both calcium uranate and becquerelite. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environmental considerations on uranium and radium from phosphate fertilizers

International Nuclear Information System (INIS)

Cioroianu, T.M.; Bunus, F.; Filip, D.; Filip, Gh.

2001-01-01

In the process of fertilizer production from natural phosphates of sedimentary origin, most of the existing radioactivity will be found in the final product. The phosphates exploited for fertilizer production at about 150 mill. tons/year are processed by two chemical methods: sulphuric and nitric acid attack. In the process of sulphuric acid attack of the phosphate rock, phosphoric acid and phosphogypsum are produced. The first product is used for fertilizer production, either as triplesuperphosphate (TSP) or diammonium phosphate (DAP). The phosphogypsum waste is deposited on stacks thus becoming a source of concern. In the case of nitric acid attack, the result is a phosphonitric (PN) solution, which is used to produce a complex fertilizer NPK. Uranium and 226Ra (usually in secular equilibrium) are dissolved and distributed between the intermediary products. Thus the average concentration of 100 mg/kg U in the phosphate rock is dissolved in 90-95 % in phosphoric acid while the 226Ra of initial 1000 / 2000 Bq/kg concentration is completely precipitated together with phosphogypsum. Therefore phosphogypsum waste has 1000-1500 Bq/kg 226Ra. The TSP fertilizer being produced by partial neutralization of phosphoric acid with phosphate rock with 100-150 mg/kg U, while 226Ra is only introduced in the neutralization process i.e. 500-800 Bq/kg. In the case of DAP, the uranium content is 140-170 mg/kg without the present of 226Ra. The complex fertilizer obtained through the process of nitric acid attack will have the whole uranium and radium of the phosphate rock (both are dissolved in nitric acid) with uranium and radium contents of 120-160 mg/kg, 1000-1500 Bq/kg respectively. The radioactivities of fertilizers produced may be a source of concern since both uranium and radium are exceeding the present accepted limits for their disposal in the environment. About 10,000-15,000 tons/yr. of uranium is spread every year on the agricultural lands worldwide by the use of phosphate

Accumulation of uranium, cesium, and radium by microbial cells: bench-scale studies

International Nuclear Information System (INIS)

Strandberg, G.W.; Shumate, S.E. II.

1982-07-01

This report describes bench-scale studies on the utilization of microbial cells for the concentration and removal of uranium, radium, and cesium from nuclear processing waste streams. Included are studies aimed at elucidating the basic mechanism of uranium uptake, process development efforts for the use of a combined denitrification-uranium removal process to treat a specific nuclear processing waste stream, and a preliminary investigation of the applicability of microorganisms for the removal of 137 Cs and 226 Ra from existing waste solutions

Coprecipitation of thorium and uranium peroxides from acid solutions

Energy Technology Data Exchange (ETDEWEB)

McTaggart, D.R.; Mailen, J.C.

1981-01-01

The factors affecting successful coprecipitation of thorium and uranium peroxides from acid media were studied. Variables considered in this work were H/sup +/ concentration, H/sub 2/O/sub 2/ concentration, duration of contact, and rate of feed solution addition. In all experiments, stock solutions of Th(NO/sub 3/)/sub 4/ and UO/sub 2/(NO/sub 3/)/sub 2/ were fed at a controlled rate into H/sub 2/O/sub 2/ solutions with constant stirring. Samples were taken as a function of time to follow the H/sup +/ concentration of the solution, uranium precipitation, thorium precipitation, precipitant weight/volume of solution, and crystalline structure and growth. The optimum conditions for maximum coprecipitation are low H/sup +/ concentration, high H/sub 2/O/sub 2/ concentration, and extended contact time between the solutions.

The levels of uranium and thorium in soils and vegetables from Cornwall and Sutherland

International Nuclear Information System (INIS)

Nicholson, S.; Long, S.E.; McEwen, I.

1990-02-01

Soils from Sutherland and Cornwall may contain high natural levels of uranium and thorium. Samples of soil and vegetables were taken from agricultural land in these regions, and the levels of uranium and thorium were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Delayed Neutron Activation Analysis (DNAA). Mean levels of uranium and thorium in the soils were, respectively, 3.5 times and 1.5 times greater than the British average. Uptake factors were calculated from these data and found to be of the order 10 -4 to 10 -3 which is in agreement with published literature. The Tessier extraction scheme was applied to some of the soils and the low levels present in the ''exchangeables'' fraction are consistent with the uptake factors. (author)

Thorium/uranium mixed oxide nano-crystals: Synthesis, structural characterization and magnetic properties

International Nuclear Information System (INIS)

Hudry, Damien; Griveau, Jean-Christophe; Apostolidis, Christos; Colineau, Eric; Rasmussen, Gert; Walter, Olaf; Wang, Di; Venkata Sai Kiran Chakravadhaluna; Courtois, Eglantine; Kubel, Christian

2014-01-01

One of the primary aims of the actinide community within nano-science is to develop a good understanding similar to what is currently the case for stable elements. As a consequence, efficient, reliable and versatile synthesis techniques dedicated to the formation of new actinide-based nano-objects (e.g., nano-crystals) are necessary. Hence, a 'library' dedicated to the preparation of various actinide based nano-scale building blocks is currently being developed. Nano-scale building blocks with tunable sizes, shapes and compositions are of prime importance. So far, the non-aqueous synthesis method in highly coordinating organic media is the only approach which has demonstrated the capability to provide size and shape control of actinide-based nano-crystals (both for thorium and uranium, and recently extended to neptunium and plutonium). In this paper, we demonstrate that the non-aqueous approach is also well adapted to control the chemical composition of the nano-crystals obtained when mixing two different actinides. Indeed, the controlled hot co-injection of thorium acetylacetonate and uranyl acetate (together with additional capping agents) into benzyl ether can be used to synthesize thorium/uranium mixed oxide nano-crystals covering the full compositional spectrum. Additionally, we found that both size and shape are modified as a function of the thorium/uranium ratio. Finally, the magnetic properties of the different thorium/uranium mixed oxide nano-crystals were investigated. Contrary to several reports, we did not observe any ferromagnetic behavior. As a consequence, ferromagnetism cannot be described as a universal feature of nano-crystals of non-magnetic oxides as recently claimed in the literature. (authors)

Economics of uranium and thorium for the generation of electricity

Energy Technology Data Exchange (ETDEWEB)

Lewis, W B

1958-09-15

Only a few years ago there was serious talk of the prospect that economically available supplies of uranium and thorium might restrict the development of nuclear power. Now the position is reversed and the state of technical development of nuclear power threatens to restrict the market for the abundant supply of these minerals. Uranium and thorium are essentially fuels well suited to the generation of large blocks of electricity. As such, they must be assessed in relation to competitive fuels -- coal, oil and natural gas and the other large sources, namely water power. The most relevant basis is therefore a study of the demand for electric power and the costs of available sources where this demand exists. (author)

Uranium and thorium migration under dislocative metamorphism

International Nuclear Information System (INIS)

Titov, V.K.; Bilibina, T.V.; Dashkova, A.D.; Il'in, V.K.; Makarova, L.I.; Shmuraeva, L.Ya.

1978-01-01

Investigated were peculiarities of uranium and thorium behaviour in the process of dislocation metamorphism on the basis of regional fracture zones of early-proterozoic embedding of Ukrainian, Aldan and Baltic shields. The studied zones correspond to tectonite of green-shale and almandin-amphibolite facies of regional metamorphism according to mineral associations. The most peculiar feature of the tectonites of green-shale facies is uranium presence in migrationally able forms, which can be involved afterwards into the ore process by hydrothermal solutions. Adsorved forms of uranium on the crystal surface or separate grains and in the cracks, as well as microinclusions of uranium minerals, selectively timed to mineral structure defects prevail among easily mobile uranium compounds. Dissolved uranium is present, evidently in gas-liquid inclusions in minerals and pore waters. There forms of uranium presence are peculiar for epidote-chlorite mylonites, as well as cataclasites and diaphthorites related to them by blastomylonites of almandin-amphibolite facies. Wide range of manifestation of this process, caused by multikilometer extension of deep fracture zones permit to consider the formations of green-shale facies of dislocation metamorphism as one of the main uranium sources in deposit formation in different uranium-ore associations different age

Study on reprocessing of uranium-thorium fuel with solvent extraction for HTGR

International Nuclear Information System (INIS)

Jiao Rongzhou; He Peijun; Liu Bingren; Zhu Yongjun

1992-08-01

A single cycle process by solvent extraction with acid feed solution is suggested. The purpose is to reprocess uranium-thorium fuel elements which are of high burn-up and rich of 232 U from HTGR (high temperature gas cooled reactor). The extraction cascade tests have been completed. The recovery of uranium and thorium is greater than 99.6%. By this method, the requirement, under remote control to re-fabricate fuel elements, of decontamination factors for Cs, Sr, Zr-Nb and Ru has been reached

Determination of uranium, thorium and potassium contents of rock samples in Yemen

International Nuclear Information System (INIS)

Abdulrahman Abdul-Hadi; Wedad Al-Qadhi; Enayat El-Zeen

2011-01-01

Uranium, thorium and potassium contents in 16 different rock samples from various sites in Republic of Yemen were determined using three different techniques of analysis: γ-spectrometry, Instrumental neutron activation analyses (INAA) and X-ray fluorescence (XRF). The concentration range for thorium, uranium and potassium were found to be from 9,810 ± 272 to 3.6 ± 1.3 ppm, 1,072 ± 40 to 1.2 ± 0.7 ppm and 11 ± 1 to 0.26 ± 0.05%, respectively. (author)

Uranium-thorium disequilibria and partitioning on melting of garnet peridotite

International Nuclear Information System (INIS)

Beattie, P.

1993-01-01

The abundances of isotopes in the 238 U decay series can be used as both tracers and chronometers of magmatic processes. In the subsolidus asthenosphere, the activity of each daughter isotope (defined as the product of its concentration and decay constant, and denoted by parentheses) is assumed to be equal to that of its parent. By contrast, ( 230 Th/ 238 U) is greater than unity in most recent mid-ocean-ridge and ocean-island basalts, implying that thorium is more incompatible (that is, it is partitioned into the melt phase more strongly) than uranium. Melting of spinel peridotite cannot produce the ( 230 Th) excesses, because measured partition coefficients for pyroxenes and olivine demonstrate that uranium is more incompatible than thorium for this rock. Here I report garnet-melt partitioning data which show that for this mineral-melt pair thorium does behave more incompatibility than uranium, thus supporting the suggestion that mid-ocean-ridge basalts (MORB) are produced by melting initiated at depths where garnet is stable. Using these data, I show that the observed ( 230 Th/ 238 U) ratios of MORB and most ocean-island basalts can be explained by slow, near-fractional melting initiated in the garnet stability field. (author)

An extraction method of uranium 233 from the thorium irradiates in a reactor core; Une methode d'extraction de l'uranium-233 a partir du thorium irradie dans une pile

Energy Technology Data Exchange (ETDEWEB)

Chesne, A; Regnaut, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

Description of the conditions of separation of the thorium, of the uranium 233 and of the protactinium 233 in hydrochloric solution by absorption then selective elution on anion exchange resin. A precipitation of the thorium by the oxalic acid permits the recuperation of the hydrochloric acid which is recycled, the main, raw material consumed being the oxalic acid. (authors) [French] Description des conditions de separation du thorium, de l'uranium 233 et du protactinium 233 en solution chlorhydrique par absorption puis elution selective sur resine echangeuse d'anions. Une precipitation du thoriun par l'acide oxalique permet la recuperation de l'acide chlorhydrique qui est recycle, la principale matiere premiere consommee etant l'acide oxalique. (auteurs)

Current extraction and separation of uranium, thorium and rare earths elements from monazite leach solution using organophosphorous extractants

International Nuclear Information System (INIS)

Biswas, Sujoy; Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.

2014-01-01

A new process based on solvent extraction has been developed for separation of uranium, thorium and rare earths from monazite leach solution using organophosphorous extractants. The Thorium cake coming from monazite source was dissolved in HNO 3 medium in presence of trace amount of HF for feed preparation. The separation of U(VI) was carried out by liquid-liquid extraction using tris-2-ethyl hexyl phosphoric acid (TEHP) in dodecane leaving thorium and rare earths elements in the raffinate. The thorium from raffinate was selectively extracted using 1M tri iso amyl phosphate (TiAP) in dodecane in organic phase leaving all rare earths elements in aqueous solution. The uranium and thorium from organic medium was quantitatively stripped using 0.05 M HNO 3 counter current mode. Results indicate the quantitative separation of uranium, thorium and rare earths from thorium cake (monazite source) using organophosphorous extractant in counter current mode

76 FR 30696 - Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

Science.gov (United States)

2011-05-26

... in the reimbursement ceilings). Title X requires DOE to reimburse eligible uranium and thorium... DEPARTMENT OF ENERGY Reimbursement for Costs of Remedial Action at Active Uranium and Thorium... reimbursement under Title X of the Energy Policy Act of 1992. In our Federal Register Notice of November 24...

76 FR 24871 - Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

Science.gov (United States)

2011-05-03

... in the reimbursement ceilings). Title X requires DOE to reimburse eligible uranium and thorium... DEPARTMENT OF ENERGY Reimbursement for Costs of Remedial Action at Active Uranium and Thorium... reimbursement under Title X of the Energy Policy Act of 1992. DATES: In our Federal Register Notice of November...

Trace determination of uranium and thorium in biological samples by radiochemical neutron activation analysis

International Nuclear Information System (INIS)

Benedik, Ljudmila; Repinc, Urska; Byrne, Anthony R.; Stegnar, Peter

2002-01-01

Radiochemical neutron activation analysis (RNAA) is an excellent method for determining uranium and thorium; it offers unique possibilities for their ultratrace analysis using selective radiochemical separations. Regarding the favourably sensitive nuclear characteristics of uranium and of thorium with respect to RNAA, but the different half-lives of their induced nuclides, two different approaches were used. In the first approach uranium and thorium were determined separately via 239 U, 239 Np and 233 Pa. In the second approach these elements were 239 239 233 determined simultaneously in a single sample using U and/or Np and Pa. Isolation of induced nuclides was based on separation by extraction and/or anion exchange chromatography. Chemical yields were measured in each sample aliquot using added 235 U, 238 Np and 231 Pa radioisotopic tracers. (author)

Recovery of valuable products from the raffinate of uranium and thorium pilot-plant

International Nuclear Information System (INIS)

Martins, E.A.J.

1990-01-01

IPEN-CNEN/SP has being very active in refining yellow cake to pure ammonium diuranate which is converted to uranium trioxide, uranium dioxide, uranium tetra-and hexa-fluoride in sequential way. The technology of the thorium purification and its conversion to nuclear grade products has been a practice since several years as well. For both elements the major waste to be worked is the raffinate from purification via TBP-varsol in pulsed columns. In this paper the actual processing technology is reviewed with special emphasis on the recovery of valuable products, mainly nitric acid, ammonium nitrate, uranium, thorium and rare earth elements. Ammonium nitrate from the precipitation of uranium diuranate is of good quality, being radioactivity and uranium-free, and recommended to be applied as fertilizer. In conclusion the main effort is to maximize the recycle and reuse of the above mentioned chemicals. (author)

75 FR 71677 - Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

Science.gov (United States)

2010-11-24

... DEPARTMENT OF ENERGY Reimbursement for Costs of Remedial Action at Active Uranium and Thorium... in FY 2011 from eligible active uranium and thorium processing site licensees for reimbursement under... approximately $24.3 million of Recovery Act funds available for reimbursement in FY 2011, as well as the $10...

Thorium and Uranium in the Rock Raw Materials Used For the Production of Building Materials

Science.gov (United States)

Pękala, Agnieszka

2017-10-01

Thorium and uranium are constant components of all soils and most minerals thereby rock raw materials. They belong to the particularly dangerous elements because of their natural radioactivity. Evaluation of the content of the radioactive elements in the rock raw materials seems to be necessary in the early stage of the raw material evaluation. The rock formations operated from deposits often are accumulated in landfills and slag heaps where the concentration of the radioactive elements can be many times higher than under natural conditions. In addition, this phenomenon may refer to buildings where rock raw materials are often the main components of the construction materials. The global control system of construction products draws particular attention to the elimination of used construction products containing excessive quantities of the natural radioactive elements. In the presented study were determined the content of thorium and uranium in rock raw materials coming from the Bełachatów lignite deposit. The Bełchatów lignite deposit extracts mainly lignite and secondary numerous accompanying minerals with the raw material importance. In the course of the field works within the framework of the carried out work has been tested 92 samples of rocks of varied petrographic composition. There were carried out analyses of the content of the radioactive elements for 50 samples of limestone of the Jurassic age, 18 samples of kaolinite clays, and 24 samples of siliceous raw materials, represented by opoka-rocks, diatomites, gaizes and clastic rocks. The measurement of content of the natural radioactive elements thorium and uranium based on measuring the frequency counts of gamma quantum, recorded separately in measuring channels. At the same time performed measurements on volume patterns radioactive: thorium and uranium. The studies were carried out in Mazar spectrometer on the powdered material. Standardly performed ten measuring cycles, after which were calculated

The uptake of uranium and radium from food and water in relation to calcium

International Nuclear Information System (INIS)

Wrenn, M.E.

1988-01-01

Observed ratios for dietary radium and calcium suggest that at least a 20 to 70 fold discrimination exists against radium uptake in the skeleton relative to calcium. It has been widely shown in many countries around the world that the relative radium to calcium ratio in the human skeleton varies from country to country, but within geographic areas, it appears to be relatively invariant with age. The ratio of radium-226 to calcium in intake, relative to the radium-226 to calcium value in the skeleton, is called the observed ratio, and varies over the world from a value of 0.013 to 0.039, with a mean of 0.024. In 1975, I inferred a mean observed ratio for uranium of 0.057 for the US. These findings suggest that man is in equilibrium with radium-226 with respect to the calcium in food and water. Most of the calcium would be ingested in diet, as would a significant amount, but not necessarily all, of the radium. The role of calcium for intake in water has not been examined

Critical review of analytical techniques for safeguarding the thorium-uranium fuel cycle

International Nuclear Information System (INIS)

Hakkila, E.A.

1978-10-01

Conventional analytical methods applicable to the determination of thorium, uranium, and plutonium in feed, product, and waste streams from reprocessing thorium-based nuclear reactor fuels are reviewed. Separations methods of interest for these analyses are discussed. Recommendations concerning the applicability of various techniques to reprocessing samples are included. 15 tables, 218 references

The Influenced of Salting Out Agent of Phosphat Ion and Ferrosulfamic in Extraction of Thorium and Uranium

International Nuclear Information System (INIS)

Busron Masduki; Didiek Herhady, R.

2002-01-01

It was carried out thorium-uranium extraction using one stage mixer settler to investigate the influenced of salting out agent of nitric acid and nitric aluminium. The result of this experiment showed the salting out of agent for nitric aluminium of 0.5 M much more significantly increase the distribution coefficient of uranium, but not for the thorium. The distribution coefficient of thorium much more significantly increased after nitric aluminium addition ≥1.0 M. There was not any meaningly differences the waste volume between nitric acid and nitric aluminium in its utilization. Reductor agent of ion Fe 2+ for chromi and decontaminate agent for protactinium in feed extraction, did not any influences of thorium and uranium distribution coefficient. (author)

Thermal diffusivity and conductivity of thorium- uranium mixed oxides

Science.gov (United States)

Saoudi, M.; Staicu, D.; Mouris, J.; Bergeron, A.; Hamilton, H.; Naji, M.; Freis, D.; Cologna, M.

2018-03-01

Thorium-uranium oxide pellets with high densities were prepared at the Canadian Nuclear Laboratories (CNL) by co-milling, pressing, and sintering at 2023 K, with UO2 mass contents of 0, 1.5, 3, 8, 13, 30, 60 and 100%. At the Joint Research Centre, Karlsruhe (JRC-Karlsruhe), thorium-uranium oxide pellets were prepared using the spark plasma sintering (SPS) technique with 79 and 93 wt. % UO2. The thermal diffusivity of (Th1-xUx)O2 (0 ≤ x ≤ 1) was measured at CNL and at JRC-Karlsruhe using the laser flash technique. ThO2 and (Th,U)O2 with 1.5, 3, 8 and 13 wt. % UO2 were found to be semi-transparent to the infrared wavelength of the laser and were coated with graphite for the thermal diffusivity measurements. This semi-transparency decreased with the addition of UO2 and was lost at about 30 wt. % of UO2 in ThO2. The thermal conductivity was deduced using the measured density and literature data for the specific heat capacity. The thermal conductivity for ThO2 is significantly higher than for UO2. The thermal conductivity of (Th,U)O2 decreases rapidly with increasing UO2 content, and for UO2 contents of 60% and higher, the conductivity of the thorium-uranium oxide fuel is close to UO2. As the mass difference between the Th and U atoms is small, the thermal conductivity decrease is attributed to the phonon scattering enhanced by lattice strain due to the introduction of uranium in ThO2 lattice. The new results were compared to the data available in the literature and were evaluated using the classical phonon transport model for oxide systems.

Fixation and separation of the elements thorium and uranium using anion exchange resins in nitrate solution; Fixation et separation des elements thorium et uranium par les resines echangeuses d'anions en milieu nitrate

Energy Technology Data Exchange (ETDEWEB)

Korgaonkar, V. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-10-01

The exchange of thorium and uranium between a strong base anion resin and a mixed water + ethanol solvent containing nitrate ions is studied. It is assumed that in the resin the thorium and uranium are fixed in the form of the complexes Th(NO{sub 3}){sub 6}{sup 2-} and UO{sub 2}(NO{sub 3}){sub 4}{sup 2-} in solution these elements are present in the form of complexes having the general formula: Th(NO{sub 3}){sub 6-n}{sup n-2} and UO{sub 2}(NO{sub 3}){sub 4-n}{sup n-2} It has been possible to deduce a law for the changes in the partition functions of thorium and uranium as a function of the concentrations of the various species in solution and of the complexing ion NO{sub 3}. From this has been deduced the optimum operational conditions for separating a mixture of these two elements. Finally, in these conditions, the influence of a few interfering ions has been studied: Ba, Bi, Ce, La, Mo, Pb, Zr. The method proposed can be used either as a preparation, or for the dosage of thorium by a quantitative separation. (author) [French] On etudie l'echange du thorium et de l'uranium entre une resine anion base forte et un solvant mixte eau + ethanol charge en ions nitrates. On a suppose que, dans la resine, le thorium et l'uranium sont fixes sous forme de complexes Th(NO{sub 3}){sub 6}{sup 2-} et UO{sub 2}(NO{sub 3}){sub 4}{sup 2-} en solution, ces elements sont engages dans des complexes de formule generale: Th(NO{sub 3}){sub 6-n}{sup n-2} and UO{sub 2}(NO{sub 3}){sub 4-n}{sup n-2} On a pu degager une loi de variation des coefficients de partage du thorium et de l'uranium en fonction des concentrations des diverses especes en solution et de l'anion complexant NO{sub 3}{sup -}. On en a deduit les conditions operatoires optimales necessaires pour separer les deux elements a partir de leurs melanges. Enfin, dans ces conditions, on a etudie l'influence de quelques elements genants: Ba, Bi, Ce, La, Mo, Pb, Zr. La methode preconisee peut etre

The Influences of Percent of Tributyl Phosphate and Ratio of Feed and Solvent on the Uranium-Thorium Extraction of Thorex Process

International Nuclear Information System (INIS)

Setyadji, Moch; Endang Susiantini

2002-01-01

The investigation of uranium and thorium extraction in water phase of thorex process first cycle using tributyl phosphate diluted in kerosine as extractant has been done. The one stage extractor was used. The effects of percent of tributyl phosphate and ratio of feed and solvent on the extraction efficiency and distribution coefficients of uranium and thorium were studied. The result of experiment showed that percent of tributyl phosphate and ratio of feed and solvent very influence on the extraction efficiency and distribution coefficients of uranium and thorium. The best results were reached at about 55% of tributyl phosphate and ratio of feed and solvent was 1:3. The extraction efficiencies of uranium and thorium and distribution coefficients of uranium and thorium at the condition above were 90% , 90.4% , 9.0 and 9.4. (author)

Recovery of valuable products in liquid effluents from uranium and thorium pilot units

International Nuclear Information System (INIS)

Jardim, E.A.; Abrao, A.

1988-01-01

IPEN-CNEN/SP has being very active in refining yellowcake to pure ammonium diuranate which is converted to uranium trioxide, uranium dioxide, uranium tetra- and hexafluoride in a sequential way. The technology of the thorium purification and its conversion to nuclear grade products has been a practice since several years as well. For both elements the major waste to be worked is the refinate from the solvent extraction column where uranium and thorium are purified via TBP-varsol in pulsed columns. In this paper the actual processing technology is reviewed with special emphasis on the recovery of valuable products, mainly nitric acid and ammonium nitrate. Distilled nitric acid and the final sulfuric acid as residue are recycle. Ammonium nitrate from the precipitation of uranium diuranate is of good quality, being radioactivity and uranium-free, and recommended to be applied as fertilizer. In conclusion the main effort is to maximise the recycle and reuse of the abovementioned chemicals. (author) [pt

Investigations on the elution behaviour of TOPO complexes of uranium and thorium using supercritical fluid chromatography

International Nuclear Information System (INIS)

Kumar, R.; Sivaraman, N.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2004-01-01

In summary uranium and thorium could be separated by supercritical fluid chromatography technique as their TOPO complexes. The elution profiles with pre-complexation of the metal nitrate indicate a better separation than the in-situ complexation. The technique can also be employed for the assay of uranium and thorium at low levels

Comparative Study of Uranium and Thorium Content of Some ...

African Journals Online (AJOL)

... of INAA on related cereals. Quality control and Quality Assurance of the method was tested by analyzing an analytical quality control service (AQCS) reference material (lichen) from International Atomic Energy Agency (IAEA). Keywords: Key words: Uranium, Thorium, neutron activation analysis, Cereals, Katsina, Maradi.

Practical aspects of monitoring and dosimetry of long-lived dust in uranium mines and mills - determination of the annual limit on intake for uranium and uranium/thorium ore dust

International Nuclear Information System (INIS)

Duport, P.; Horvath, F.

1989-01-01

Based on the recommendations of ICRP Publication 26, the dosimetric and metabolic data of ICRP Publication 30, and using available information on the physical and solubility characteristics of uranium and uranium/thorium ore, the ALI values for airborne ore dust were calculated. Four hypothetical types of ore were considered: uranium ore with no radon emanation, uranium ore with 50% radon emanation, uranium/thorium ore with neither 222 Rn nor thoron emanation, and uranium/thorium ore with 50% 22 Rn and 220 Rn emanation. Furthermore, the ALI values were calculated assuming the radionuclides present in the ore were all: (a) solubility class Y: (b) solubility class W; and (c) equal parts of classes Y and W. The ALI values were also calculated for Activity Median Aerodynamic Diameters (AMAD) ranging from 1 to 10 μm. The results of the calculations show that the solubility class of the radionuclides is the single most important factor that governs ALI values. The ALI value for uranium and uranium-thorium ore dust is proportional to (AMAD) 0.5 for class Y materials, (AMAD) 0.2 for a mixture of equal parts of class Y and class W materials, and is independent of the AMAD for class W materials. A series of graphs is given from which it is possible to evaluate the ALI for airborne ore dust when the AMAD of the dust and the solubility characteristics are known approximately. (author)

Controls on radium transport by adsorption to iron minerals

Science.gov (United States)

Chen, M.; Wang, T.; Kocar, B. D.

2015-12-01

Radium is a naturally occurring radioactive metal found in many subsurface environments. Radium isotopes are generated by uranium and thorium decay, and are particularly abundant within groundwaters where minimal porewater flux leads to accumulation. These isotopes are used as natural tracers for estimating submarine groundwater discharge (SGD) [1], allowing for large scale estimation of GW fluxes into and out of the ocean [2]. They also represent a substantial hazard in wastewater produced after hydraulic fracturing for natural gas extraction [3], resulting in a significant risk of environmental release to surface and near-surface waters, and increased cost for water treatment or disposal. Adsorption to mineral surfaces represents a dominant pathway of radium retention in subsurface environments. For SGD studies, adsorption processes impact estimates of GW fluxes, while in hydraulic fracturing, radium adsorption to aquifer solids mediates wastewater radium activities. Analysis of past sorption studies revealed large variability in partition coefficients [4], while examination of radium adsorption kinetics and surface complexation have only recently started [5]. Accordingly, we present the results of sorption and column experiments of radium with a suite of iron minerals representative of those found within deep saline and near-surface (freshwater) aquifers, and evaluate impacts of varying salinity solutions through artificial waters. Further, we explore the impacts of pyrite oxidation and ferrihydrite transformation to other iron-bearing secondary minerals on the transport and retention of radium. These results will provide critical information on the mineralogical controls on radium retention in subsurface environments, and will therefore improve predictions of radium groundwater transport in natural and contaminated systems. [1] Charette, M.A., Buesseler, K.O. & Andrews, J.E., Limnol. Oceanogr. (2001). [2] Moore, W.S., Ann. Rev. Mar. Sci. (2010). [3] Vengosh, A

Uranium and thorium mining regulations: Amendments relating to financial assurances and decommissioning of uranium mining facilities. Consultative document

Energy Technology Data Exchange (ETDEWEB)

Brooks, G L [Atomic Energy of Canada Ltd., Sheridan Park, ON (Canada). CANDU Operations

1993-12-23

The purpose of this document is to describe the objectives, scope, substance and application of proposed amendments to the Uranium and Thorium Mining Regulations; in particular, amendments relating to the provision of financial assurances for the decommissioning of Canadian uranium mines. (author).

Uranium and thorium mining regulations: Amendments relating to financial assurances and decommissioning of uranium mining facilities. Consultative document

International Nuclear Information System (INIS)

Brooks, G.L.

1993-01-01

The purpose of this document is to describe the objectives, scope, substance and application of proposed amendments to the Uranium and Thorium Mining Regulations; in particular, amendments relating to the provision of financial assurances for the decommissioning of Canadian uranium mines. (author)

Atomic Energy Control Board and its role in the regulation of uranium and thorium mines

International Nuclear Information System (INIS)

Dory, A.B.

1980-05-01

Laws governing the Atomic Energy Control Board (AECB), its structure and functions is described in the context of the Board's role in uranium and thorium mining. The licensing and compliance procedures are described as they pertain to the objectives of the AECB in protecting workers, the public and the environment during construction, operating and closure of uranium and thorium mining and milling facilities. (OT)

Research on the removal of radium from uranium effluent by air-aeration hydrated manganese hydroxide adsorption

International Nuclear Information System (INIS)

Zhang Jianguo; Chen Shaoqing; Qi Jing

2002-01-01

In the acidic leaching uranium process, pyrolusite or manganese oxide (MnO 2 ) powder is often used as an oxidizer. In the processed effluent, manganese ion present as a contaminant in addition to U, Ra, Th, As, Zn, Cu, F, SO 4 2- , etc. Manganese ion content is about 100∼200 mg/1 in effluent. In this case, a new process technique can be developed to treat the effluent using the Mn 2+ present in the effluent. The approach is as follows: The effluent is neutralized by lime milk to pH about 11. As a result, most contaminants are precipitated to meet the uranium effluent discharge standards (U, Th, Mn, SO 4 2- etc.), but radium is still present in the effluent. In this process, manganese ion forms manganese hydroxide Mn(OH) 2 . The manganese hydroxide is easily to oxide to form MnO(OH) 2 by air aeration. This hydrated manganese hydroxide complex can then be used to adsorb radium in effluent. The experiments show: (1) Effluent pH, manganese concentration in effluent, and aeration strength and time etc. influence the radium removal efficiency. Under the test conditions, when manganese in effluent is between 100∼300 mg/l, and pH is over 10.5, radium can be reduced to lower 1.11 Bq/1 in the processed effluent. Higher contents of impurity elements such as aluminum, silicon and magnesium in the effluent affect the removal efficiency; (2) Under the experimental conditions, the lime precipitation air-aeration formed hydrated manganese hydroxide complex sludge is stable. There is no obvious release of radium from the adsorbed hydrated manganese hydroxide complex sludge; (3) The current experiments show that hydrated manganese hydroxide complex sludge has a very good re-adsorption ability for removal of radium from uranium effluent. Some experimental parameters have been measured. (author)

A comparative study on determination of composition of uranium thorium mixed oxides by tube and radioisotope excited EDXRF

International Nuclear Information System (INIS)

Dhara, Sangita; Sanjay Kumar, S.; Misra, N.L.; Aggarwal, S.K.; Singh, Ajit Kumar; Lodha, G.S.

2009-01-01

Energy Dispersive X-ray Fluorescence (EDXRF) methods for determination of uranium and thorium in their mixed oxide matrices using tube and radioisotope excitation sources have been developed. The methodology involves preparation of mixed oxide calibration/sample mixtures of uranium and thorium oxides, mixing of fixed amount of internal standard Yttrium in form of Yttrium oxide, pelletizing these mixtures after thorough mixing and recording their EDXRF spectra using Rh target as well as 109 Cd radioisotope source. The samples were analysed for uranium and thorium on the basis of calibration plots

Comparison of open cycles of uranium and mixed oxides of thorium-uranium using advanced reactors

International Nuclear Information System (INIS)

Gonçalves, Letícia C.; Maiorino, José R.

2017-01-01

A comparative study of the mass balance and production costs of uranium oxide fuels was carried out for an AP1000 reactor and thorium-uranium mixed oxide in a reactor proposal using thorium called AP-Th1000. Assuming the input mass values for a fuel load the average enrichment for both reactors as well as their feed mass was determined. With these parameters, the costs were calculated in each fuel preparation process, assuming the prices provided by the World Nuclear Association. The total fuel costs for the two reactors were quantitatively compared with 18-month open cycle. Considering enrichment of 20% for the open cycle of mixed U-Th oxide fuel, the total uranium consumption of this option was 50% higher and the cost due to the enrichment was 70% higher. The results show that the use of U-Th mixed oxide fuels can be advantageous considering sustainability issues. In this case other parameters and conditions should be investigated, especially those related to fuel recycling, spent fuel storage and reduction of the amount of transuranic radioactive waste

Biosorption of uranium, radium, and cesium

International Nuclear Information System (INIS)

Strandberg, G.W.

1982-01-01

Some fundamental aspects of the biosorption of metals by microbial cells were investigated. These studies were carried out in conjunction with efforts to develop a process to utilize microbial cells as biosorbents for the removal of radionuclides from waste streams generated by the nuclear fuel cycle. It was felt that an understanding of the mechanism(s) of metal uptake would potentially enable the enhancement of the metal uptake phenomenon through environmental or genetic manipulation of the microorganisms. Also presented are the results of a preliminary investigation of the applicability of microorganisms for the removal of 137 cesium and 226 radium from existing waste solutions. The studies were directed primarily at a characterization of uranium uptake by the yeast, Saccharomyces cerevisiae, and the bacterium, Pseudomonas aeruginosa

Simultaneous determination of radium and uranium in soil

International Nuclear Information System (INIS)

Yamamoto, Takashi; Yuki, Eiji; Ishida, Tatsuo

1977-01-01

Radium and uranium contents in soil are the fundamental indexes for natural radioactivity. In this connection, the simultaneous determination of Ra and U has been studied. To a soil sample, 133 Ba is added and the mixture is dried. It is decomposed with sulfuric and nitric acids. Then a Ba-carrier is added, and the insoluble residue (Ra analysis sample) and the solution (U analysis sample) are obtained for simultaneous determination of Ra and U. The rates of recovery of Ra and U in soil are both over 90%. (Mori, K.)

Determination for levels of uranium and thorium in water along Oum Er-Rabia river using alpha track detectors

Directory of Open Access Journals (Sweden)

M. Amrane

2017-07-01

Full Text Available Different river water samples have been collected and analyzed from different locations along Oum Er-Rbia River in Morocco. The uranium and thorium concentrations were investigated in the studied river and dam water samples. Mean activity concentrations of uranium and thorium in water were found to be between 12 and 37 Bq.m−3 and 2–10 Bq.m−3, respectively. The pH measured at all river water simples was slightly alkaline and ranged from 7.5 to 8.75. The electrical conductivity ranged from 2790 to 794 μS cm−1. It was found that uranium and thorium concentrations were correlated with some chemical parameters in Oum Er-Rabia River water. Uranium and thorium measurements in this river are important for monitoring environmental radioactivity and to know the geochemical behaviour of these radionuclides in the surficial water bearing environments.

Determination of ultratrace concentrations of uranium and thorium in natural waters by x-ray fluorescence

International Nuclear Information System (INIS)

Stewart, J.H. Jr.; Brooksbank, R.D.

1981-01-01

An x-ray fluorescence method for the simultaneous determination of uranium and thorium at the less than 1 ppM level in natural waters is described. Uranium and thorium are coprecipitated with an internal standard, yttrium, and incorporated into an iron-aluminum hydroxide carrier. The hydroxide precipitate is filtered, and the filter disk is analyzed by the energy-dispersive x-ray fluorescence technique. Matrix interferences caused by the presence of unpredictable anions and cations are compensated for by the internal standard. The U/Y and Th/Y ratios are linear over the 5- to 100-μg range of interest, and the detection limit of each element on the filter disk is 2 μg (3 sigma). Relative standard deviation was 17% at the 15-μg and 4% at the 100-μg level for thorium and 11% at the 11-μg and 2% at the 100-μg level for uranium. Analysis of spiked solutions showed a recovery of 19.6 +- 0.3 μg for uranium and 19.8 +- 0.3 μg for thorium at the 20-μg level, and the normal lower reporting limit is 5 μg. Fifty disks can be routinely measured during a normal working day

Behaviour of radium isotopes released with brines and sediments from coal mines in Poland

International Nuclear Information System (INIS)

Wysocka, M.; Chalupnik, S.; Mielnikow, A.; Lebecka, J.; Skubacz, K.

1998-01-01

Saline waters occurring in underground coal mines in Poland often contain natural radioactive isotopes, mainly 226 Ra from uranium series and 228 Ra from thorium series. Approximately 40% of total amount of radium remains underground in a form of radioactive deposits, but 225 MBq of 226 Ra and 380 MBq of 228 Ra are released daily to the rivers with mine effluents. Technical measures as spontaneous precipitation of radium in gobs, decreasing of amounts of water inflowing into underground working etc. have been undertaken in several coal mines and in the result total amount of radium released to the surface waters diminished by about 60% during last 5-6 years. Mine waters can cause a severe impact on the natural environment. The enhancement of radium concentration in river waters, bottom sediments and vegetation is observed. Sometimes radium concentration in rivers exceeds 0.7 kBq/m 3 , which is due to Polish law a permissible level for liquid radioactive waste. It was necessary to undertake investigations for development the methods of the purification of mine waters from radium. The radium balance in effluents has been calculated and a map of radioactive contamination of river waters have been prepared. Solid wastes with enhanced natural radioactivity have been produced in huge amounts in energy and coal industries in Poland. There are two main sources of these waste products. As a result of combustion of coal in power plants low radioactive waste materials are produced, with 226 Ra concentration seldom exceeding few hundreds of Bq/kg. Different situation is be observed in coal mines, where as a result of precipitation of radium from radium-bearing waters radioactive deposits are formed. Sometimes natural radioactivity of such materials is very high, in case of scaling from coal mines radium concentration may reach 4x10 5 Bq/kg - similar activity as for 3% uranium ore. Therefore maintenance of solid waste with technologically enhanced natural radioactivity (TENR

The speciation of dissolved elements in aquatic solution. Radium and actinides

International Nuclear Information System (INIS)

Haesaenen, E.

1994-01-01

In the publication, the chemistry and speciation of radium, thorium, protactinium, uranium, neptunium, lutonium, americium and curium in ground-water environment is reviewed. Special attention is given to the transuranium elements, which have a central role in the repository of nuclear wastes. The most important methods used in the speciation of these elements is presented. The laser-induced methods, developed in the 1980's, are especially discussed. These have made it possible, e.g., to speciate the transuranium elements in their very low, actual repository ground-water concentrations (10-100 ng/l). (54 refs., 10 figs., 3 tabs.)

Pollution of agricultural crops with lanthanides, thorium and uranium studied

Czech Academy of Sciences Publication Activity Database

Kučera, Jan; Mizera, Jiří; Řanda, Zdeněk; Vávrová, M.

2007-01-01

Roč. 271, č. 3 (2007), s. 581-587 ISSN 0236-5731 Institutional research plan: CEZ:AV0Z10480505 Keywords : thorium, uranium * agricultural crops * neutron activation analysis Subject RIV: BE - Theoretical Physics Impact factor: 0.499, year: 2007

Groundwater radon, radium and uranium concentrations in Regiao dos Lagos, Rio de Janeiro State, Brazil

International Nuclear Information System (INIS)

Almeida, R.M.R.; Lauria, D.C.; Ferreira, A.C.; Sracek, O.

2004-01-01

Ground water from Regiao dos Lagos, a coastal area of Rio de Janeiro state, was analysed for 226 Ra, 228 Ra, 222 Rn, 238 U, major ion concentrations, and physico-chemical parameters were also measured. Concentrations values ranged from -1 for 226 Ra, from -1 for 228 Ra and from -4 to 8.0x10 -2 Bq l -1 for 238 U. Detectable 222 Rn concentrations (>3 Bq l -1 ) were found only in two samples. The spatial distribution of Ra concentration delineated one distinct area and some hot spots with high Ra concentration. Low pH value is the most important water parameter linked to high radium concentration. This is probably related to limited adsorption of radium on soil ferric oxides and hydroxides at low pH range. There was a significant correlation between uranium concentrations and electrical conductivity values, and also between uranium concentrations and concentrations of Ca, Mg, Na, K, and Cl, indicating sea water impact. Uranium concentrations were lower than maximum contaminant level for drinking water, whereas 17 out of the 88 ground water samples had levels of radium that exceeded the maximum contaminant level for tap water. The total annual effective dose for adult due to the water consumption reaches values up to 0.8 mSv

Accumulation of thorium and uranium by microbes. The effect of pH, concentration of metals, and time course on the accumulation of both elements using streptomyces levoris

International Nuclear Information System (INIS)

Tsuruta, Takehiko

2006-01-01

The accumulation of thorium and uranium by various microorganisms from a solution containing both metals at pH 3.5 was examined. Among the tested species, a high accumulation ability for thorium was exhibited by strains of gram-positive bacteria, such as Arthrobacter nicotianae, Bacillus megaterium, B. subtilis, Micrococcus luteus, Rhodococcus erythropolis, and Streptomyces levoris. Though uranium was accumulated in small amounts by most of microorganisms. A. nicotianae, S. flavoviridis, and S. levoris had relatively high uranium accumulation abilities. In these high performance thorium- and uranium-accumulating microorganisms, S. levoris, which accumulated the largest amount of uranium from the solution containing only uranium at pH 3.5, accumulated about 300 μmol thorium and 133 μmol uranium per gram dry weight of microbial cells from a solution containing both thorium and uranium at pH 3.5. The amount and time course of the thorium accumulation were almost unaffected by the co-existing uranium, while those of uranium were strongly affected by the co-existing thorium. The effects of pH, the thorium and uranium concentrations, and time course on both metal accumulations were also evaluated by numerical formulas. (author)

The environmental behaviour of radium

International Nuclear Information System (INIS)

Sheppard, M.I.

1980-09-01

Radium-226 and its daughter, radon-222, an inert gas, are important members of the uranium decay series as far as human exposure is concerned. Radon diffuses from rocks, soil and water into the atmosphere, and its daughter products polonium-218 and polonium-214 can be retained in the lungs. Radium and radon are contained in emissions from fossil fuel plants, fertilizers, natural gas, building materials and uranium ore. To assess the impact of man's use, intentional or not, of radium and its daughters, we must know their physical, chemical and biological behaviour. This report examines the literature pertinent to the natural levels of radium found in rock, soil, water and plants. Information concerning radium is integrated from several disciplines. The radiological properties and chemistry of radium, and radium-soil interactions are discussed as well as the soil distribution coefficient and the mode of soil transport of radium. Plant transfer coefficients for radium and methods of analysis and measurement are given. A list of topics requiring further research concludes the report. (auth)

Concentration of thorium and uranium in the ecosystem of Atlantic Forest (Mata Atlantica) of Pernambuco state

International Nuclear Information System (INIS)

Ferreira, Fabiano S.; Silva, Waldecy A.; Lira, Marcelo B.G.; Souza, Ebenezer M. de; França, Elvis de

2017-01-01

Thorium (Th) and Uranium (U) are distributed throughout the earth's crust. The mean thorium concentration ranges from 6 to 15 ppm, which makes it 3 times more abundant than uranium. These radionuclides in their natural form, and in low amounts, do not present a risk to the population because they have low activity, but the effects caused by the accumulation in living beings have not yet been fully elucidated. This work aims to evaluate the concentration of Th and U in the soils of an excerpt in the Atlantic Forest in the State of Pernambuco. Soil sampling (depth 0-20 cm) occurred in the projection of tree crowns of the predominant species in the studied areas. After drying and comminution, samples of 0.1 g of soil were submitted to chemical treatment to enable the analysis. This treatment consisted in the addition of 9 ml of HNO 3 (nitric acid) and 3 ml of HF (hydrofluoric acid) with subsequent heating of the sample and reference materials in a digester oven. The concentrations of Th and U were quantified by Inductively Coupled Plasma Mass Spectrometry - ICP-MS. The mean concentrations found were: 10.5 mg kg -1 for thorium and 2.18 mg.kg -1 for uranium, with values of 35 mg.kg -1 and 26 mg.kg -1 quantified in a thorium sample and uranium respectively. In this region, uranium and thorium hotspot were found, which reinforces the need for greater attention to these radionuclides in the Atlantic Forest of the State of Pernambuco

A study of uranium and thorium migration at the Koongarra uranium deposit with application to actinide transport from nuclear waste repositories

International Nuclear Information System (INIS)

Payne, T.E.

1991-01-01

One way to gain confidence in modelling possible radionuclide releases is to study natural systems which are similar to components of the multibarrier waste repository. Several such analogues are currently under study and these provide useful data about radionuclide behaviour in the natural environment. One such system is the Koongarra uranium deposit in the Northern Territory. In this dissertation, the migration of actinides, primarily uranium and thorium, has been studied as an analogue for the behaviour of transuranics in the far-field of a waste repository. The major findings of this study are: 1. the main process retarding uranium migration in the dispersion fan at Koongarra is sorption, which suppresses dissolved uranium concentrations well below solubility limits, with ferrihydrite being a major sorbing phase; 2. thorium is extremely immobile, with very low dissolved concentrations and corresponding high distribution ratios for 230 Th. Overall, it is estimated that colloids are relatively unimportant in Koongarra groundwater. Uranium migrates mostly as dissolved species, whereas thorium and actinium are mostly adsorbed to larger, relatively immobile particles and the stationary phase. However, of the small amount of 230 Th that passes through a 1μm filter, a significant proportion is associated with colloidal particles. Actinium appears to be slightly more mobile than thorium and is associated with colloids to a greater extent, although generally present in low concentrations. These results support the possibility of colloidal transport of trivalent and tetravalent actinides in the vicinity of a nuclear waste repository. 112 refs., 23 tabs., 32 figs

Relativistic Hartree-Bogoliubov description of thorium and uranium isotopes

International Nuclear Information System (INIS)

Naz, Tabassum; Ahmad, Shakeb

2016-01-01

The relativistic Hartree-Bogoliubov (RHB) theory is a relativistic extension of the Hartree-Fock- Bogoliubov theory. It is a unified description of mean-field and pairing correlations and successfully describe the various phenomenon of nuclear structure. In the present work, RHB is applied to study the thorium and uranium isotopes

Behavior of radioactive elements (uranium and thorium) in Bayer process

International Nuclear Information System (INIS)

Sato, C.; Kazama, S.; Sakamoto, A.; Hirayanagi, K.

1986-01-01

It is essential that alumina used for manufacturing electronic devices should contain an extremely low level of alpha-radiation. The principal source of alpha-radiation in alumina is uranium, a minor source being thorium. Uranium in bauxite dissolves into the liquor in the digestion process and is fixed to the red mud as the desilication reaction progresses. A part of uranium remaining in the liquor precipitates together with aluminum hydroxide in the precipitation process. The uranium content of aluminum hydroxide becomes lower as the precipitation velocity per unit surface area of the seed becomes slower. Organic matters in the Bayer liquor has an extremely significant impact on the uranium content of aluminum hydroxide. Aluminum hydroxide free of uranium is obtainable from the liquor that does not contain organic matters

The economics of thorium fuel cycles

International Nuclear Information System (INIS)

James, R.A.

1978-01-01

The individual cost components and the total fuel cycle costs for natural uranium and thorium fuel cycles are discussed. The thorium cycles are initiated by using either enriched uranium or plutonium. Subsequent thorium cycles utilize recycled uranium-233 and, where necessary, either uranium-235 or plutonium as topping. A calculation is performed to establish the economic conditions under which thorium cycles are economically attractive. (auth)

Reducing uranium and thorium level in Zircon: effect of heat treatment on rate of leaching

International Nuclear Information System (INIS)

Meor Yusoff Meor Sulaiman

2002-01-01

Considerable amount of uranium and thorium are found in Malaysian zircon and the level is much higher than the minimum value adopted by many importing countries. Selective leaching had been applied as an important technique to reduce these elements. An initial study was carried out using hydrochloric acid leaching system but the result was not favourable. The rate of uranium and thorium leached can be further improved by introducing a heat pretreatment process prior to leaching (Author)

PWR core design, neutronics evaluation and fuel cycle analysis for thorium-uranium breeding recycle

International Nuclear Information System (INIS)

Bi, G.; Liu, C.; Si, S.

2012-01-01

This paper was focused on core design, neutronics evaluation and fuel cycle analysis for Thorium-Uranium Breeding Recycle in current PWRs, without any major change to the fuel lattice and the core internals, but substituting the UOX pellet with Thorium-based pellet. The fuel cycle analysis indicates that Thorium-Uranium Breeding Recycle is technically feasible in current PWRs. A 4-loop, 193-assembly PWR core utilizing 17 x 17 fuel assemblies (FAs) was taken as the model core. Two mixed cores were investigated respectively loaded with mixed reactor grade Plutonium-Thorium (PuThOX) FAs and mixed reactor grade 233 U-Thorium (U 3 ThOX) FAs on the basis of reference full Uranium oxide (UOX) equilibrium-cycle core. The UOX/PuThOX mixed core consists of 121 UOX FAs and 72 PuThOX FAs. The reactor grade 233 U extracted from burnt PuThOX fuel was used to fabrication of U 3 ThOX for starting Thorium-. Uranium breeding recycle. In UOX/U 3 ThOX mixed core, the well designed U 3 ThOX FAs with 1.94 w/o fissile uranium (mainly 233 U) were located on the periphery of core as a blanket region. U 3 ThOX FAs remained in-core for 6 cycles with the discharged burnup achieving 28 GWD/tHM. Compared with initially loading, the fissile material inventory in U 3 ThOX fuel has increased by 7% via 1-year cooling after discharge. 157 UOX fuel assemblies were located in the inner of UOX/U 3 ThOX mixed core refueling with 64 FAs at each cycle. The designed UOX/PuThOX and UOX/U 3 ThOX mixed core satisfied related nuclear design criteria. The full core performance analyses have shown that mixed core with PuThOX loading has similar impacts as MOX on several neutronic characteristic parameters, such as reduced differential boron worth, higher critical boron concentration, more negative moderator temperature coefficient, reduced control rod worth, reduced shutdown margin, etc.; while mixed core with U 3 ThOX loading on the periphery of core has no visible impacts on neutronic characteristics compared

Determination of thorium and uranium isotopes in the mining lixiviation liquor samples

International Nuclear Information System (INIS)

Reis Júnior, Aluísio de Souza; Monteiro, Roberto Pellacani Guedes

2017-01-01

The alpha spectrometric analysis refers to determination of thorium and uranium isotopes in the mining lixiviation liquor samples. The analytical procedure involves sample preparation steps for rare earth elements, thorium and uranium separation using selective etching with hydrofluoric acid and further radiochemical separation of these using TRU chromatographic resins (Eichrom Industries Inc. USA) besides electroplating of the isolated radionuclides. An isotopic tracer is used to determine the overall chemical yield and to ensure traceability to a national standard. The results are compared to results obtained for the same samples by Becquerel laboratory. We improved the method looking for reproducibility and isotopes isolation as required by alpha spectrometry and the method showing effective in analysis of mining liquor. (author)

Determination of thorium and uranium isotopes in the mining lixiviation liquor samples

Energy Technology Data Exchange (ETDEWEB)

Reis Júnior, Aluísio de Souza; Monteiro, Roberto Pellacani Guedes, E-mail: reisas@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

The alpha spectrometric analysis refers to determination of thorium and uranium isotopes in the mining lixiviation liquor samples. The analytical procedure involves sample preparation steps for rare earth elements, thorium and uranium separation using selective etching with hydrofluoric acid and further radiochemical separation of these using TRU chromatographic resins (Eichrom Industries Inc. USA) besides electroplating of the isolated radionuclides. An isotopic tracer is used to determine the overall chemical yield and to ensure traceability to a national standard. The results are compared to results obtained for the same samples by Becquerel laboratory. We improved the method looking for reproducibility and isotopes isolation as required by alpha spectrometry and the method showing effective in analysis of mining liquor. (author)

Assessment of nonpoint source chemical loading potential to watersheds containing uranium waste dumps associated with uranium exploration and mining, Browns Hole, Utah

Science.gov (United States)

Marston, Thomas M.; Beisner, Kimberly R.; Naftz, David L.; Snyder, Terry

2012-01-01

During August of 2008, 35 solid-phase samples were collected from abandoned uranium waste dumps, undisturbed geologic background sites, and adjacent streambeds in Browns Hole in southeastern Utah. The objectives of this sampling program were (1) to assess impacts on human health due to exposure to radium, uranium, and thorium during recreational activities on and around uranium waste dumps on Bureau of Land Management lands; (2) to compare concentrations of trace elements associated with mine waste dumps to natural background concentrations; (3) to assess the nonpoint source chemical loading potential to ephemeral and perennial watersheds from uranium waste dumps; and (4) to assess contamination from waste dumps to the local perennial stream water in Muleshoe Creek. Uranium waste dump samples were collected using solid-phase sampling protocols. Solid samples were digested and analyzed for major and trace elements. Analytical values for radium and uranium in digested samples were compared to multiple soil screening levels developed from annual dosage calculations in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act's minimum cleanup guidelines for uranium waste sites. Three occupancy durations for sites were considered: 4.6 days per year, 7.0 days per year, and 14.0 days per year. None of the sites exceeded the radium soil screening level of 96 picocuries per gram, corresponding to a 4.6 days per year exposure. Two sites exceeded the radium soil screening level of 66 picocuries per gram, corresponding to a 7.0 days per year exposure. Seven sites exceeded the radium soil screening level of 33 picocuries per gram, corresponding to a 14.0 days per year exposure. A perennial stream that flows next to the toe of a uranium waste dump was sampled, analyzed for major and trace elements, and compared with existing aquatic-life and drinking-water-quality standards. None of the water-quality standards were exceeded in the stream samples.

Uranium and radium-226 in the environment of the post-uranium mining areas in Poland

Energy Technology Data Exchange (ETDEWEB)

Kardas, M.; Suplinska, M.; Ciupek, K. [Central Laboratory for Radiological Protection (Poland)

2014-07-01

The work carried out under the project NCBiR - 'Technologies Supporting Development of Safe Nuclear Power Engineering'; Task 3: Meeting the Polish nuclear power engineering's demand for fuel - fundamental aspects. Depending on location, environmental components may have different concentration levels of radionuclides. Main source of uranium and radium in the natural environment is atmospheric precipitation of the material resulting weathering and erosion of older rocks, enhanced due to human activity by fertilizers used in agriculture and fossil fuel combustion. The waste heaps and dumps, especially derived from post-uranium mining and phosphate fertilizer industry are the another source of uranium and radium in the environment. Our studies include post-uranium mining areas (inactive mines and waste dumps) and those adjacent meadows and grassland at the area of the Giant Mountains (Karkonosze Mountains) in the south-west Poland. Samples of soil and mineral material from mine shafts, water samples from ponds, streams and small rivers and vegetation samples (grass, alfalfa, birch leaves) were analyzed. Also, similar samples from agricultural regions of Poland were examined as a reference level. Uranium isotopes were determined by radiochemical method (ion exchange and extraction) and activity measurement using alpha spectrometry. Concentration of {sup 226}Ra was determined radiochemically using emanation method. For the validation of the method, determinations of uranium isotopes and radium-226 in reference samples were performed. Depending on location, the different levels of activity concentration of analyzed radionuclides were detected. Samples from the mine shafts and dumps, both water and soil, were characterized by the activity concentrations of {sup 238}U and {sup 226}Ra even by several orders higher than outside of those areas. The concentrations of the radionuclides in the areas located in further distances from mine and dumps are similar to

Safe management of wastes from the mining and milling of uranium and thorium ores

International Nuclear Information System (INIS)

1987-01-01

Wastes from the mining and milling of uranium and thorium ores pose potential environmental and public health problems because of their radioactivity and chemical composition. This document consists of two parts: a Code of Practice (Part I) and a Guide to the Code (Part II). The Code sets forth the requirements for the safe and responsible handling of the wastes resulting from the mining and milling of uranium and thorium ores, while the Guide presents further guidance in the use of the Code together with some discussion of the technology and concepts involved

Problems in the separation of radium from uranium ore tailings

Energy Technology Data Exchange (ETDEWEB)

Seeley, F.G.

1976-01-01

The radium content of a representative sandstone type of uranium ore was found to be distributed uniformly according to particle size before leaching, but in sulfuric acid-leached tailings was found predominantly in the -325 mesh fraction. The radium leaching characteristics from both ore and sulfate-leached tailings were investigated. Several 1 M salt solutions showed poor to moderate RaSO/sub 4/ dissolution from ''slimes solids'' tailings, while 3 M HNO/sub 3/ or HCl solutions dissolved approximately 95% of the radium content of either ore or tailings. Tests are reported in which -325 mesh sand particles were coated with alkaline-earth sulfates by a special technique to simulate slime solids tailings. The dissolution of RaSO/sub 4/ from these coated sands was decreased by the presence of BaSO/sub 4/, but increased by the presence of CaSO/sub 4/. The interrelationships in the dissolution of mixtures of CaSO/sub 5/, SrSO/sub 4/, BaSO/sub 4/, and RaSO/sub 4/ are shown, and a generalized equation for the estimation of the dissolution of a minor component is presented.

Seepage from uranium tailing ponds and its impact on ground water

International Nuclear Information System (INIS)

Rahn, P.H.; Mabes, D.L.

1978-01-01

A typical uranium mill produces about 1800 metric tons of tailing per day. An assessment of the seepage from an unlined tailing impoundment of a hypothetical mill in northwestern New Mexico indicates that about 2x10 5 m 3 /yr of water will seep over a period of 23 years. The seepage water will move vertically to the water table, and then spread out radially and ultimately downgradient with ground water. The principal dissolved contaminants in the tailing pond liquid are radium, thorium, sulfate, iron, manganese, and selenium; in addition, the liquid is acidic (pH=2). Many contaminants precipitate out as neutralization of seepage water occurs. At the termination of mill operation, radium will have advanced about 0.4 m and thorium no more than 0.1 m below the bottom of the tailing pond

Uranium and thorium content of some sedimentary and igneous rocks from the Rolla 10 x 20 quadrangle, Missouri

International Nuclear Information System (INIS)

Odland, S.K.; Millard, H.T. Jr.

1979-01-01

Uranium and thorium contents of 175 samples of Precambrian and overlying sedimentary rocks from 28 drill holes in the Rolla 1 0 x 2 0 quadrangle, Missouri, were determined in 1978 as part of the National Uranium Resource Evaluation (NURE) effort. The limited number of drill-hole samples analyzed and the great distance between drill holes does not provide sufficient analytical data for an evaluation of the uranium potential in this quadrangle. However, because NURE studies in the quadrangle have been recessed, the data at hand are being made available in this report. The 175 rock samples for uranium and thorium analyses were selected to determine the uranium and thorium content of lower Paleozoic stratigraphic units in the quadrangle, and to test the conceptual model of uranium accumulation in basal sandstones, conglomerates, and arkoses that onlap the Precambrian igneous rocks. The conceptual model of uranium in intragranitic veins was not tested, because not all drill holes penetrate Precambrian rocks and none penetrate them more than a few meters

Production of chelating agents by Pseudomonas aeruginosa grown in the presence of thorium and uranium

International Nuclear Information System (INIS)

Premuzic, E.T.; Lin, M.; Francis, A.J.; Schubert, J.

1986-01-01

Chelating agents produced by microorganisms enhance the dissolution of iron increasing the mobility and bioavailability of the metal. Since some similarities exist in the biological behavior of ferric, thorium and uranyl ions, microorganisms resistant to these metals and which grow in their presence may produce sequestering agents of Th and U, and other metals in a manner similar to the complexation of iron by siderophores. The ability of P. aeruginosa to elaborate sequestering agents in medium containing thorium or uranium salts was tested. Uranium has a stronger inhibitory effect on growth of the organism than thorium at similar concentrations. Analyses of the culture media have shown, that relative to the control, and under the experimental conditions used, the microorganisms have produced several new chelating agents for thorium and uranium. Extracts containing these chelating agents have been tested for their decorporation potential. In vitro mouse liver bioassay and in vivo mouse toxicity tests indicate that their efficiency is comparable to DTPA and DFOA and that they are virtually non-toxic to mice. The bacterially produced compounds resemble, but are not identical to the known iron chelating siderophores isolated from microorganisms. Some of their chemical properties are also discussed. (author)

Chloride metallurgy for uranium recovery: concept and costs

International Nuclear Information System (INIS)

Campbell, M.C.; Ritcey, G.M.; Joe, E.G.

1982-01-01

Uranium, thorium and radium are all effectively solubilized in chloride media. This provides a means to separate and isolate these species for ultimate sale or disposal. The laboratory work on the applications of hydrochloric acid leaching, chlorine assisted leaching and high temperature chlorination is reviewed. An indication of costs and benefits is provided to enable the evaluation of this technology as an option for reducing the environmental impact of tailings

Determination of Uranium and Thorium in Brazilian coals by epithermal neutron activation analysis

International Nuclear Information System (INIS)

Bernedo, L.F.B.

1981-08-01

An experimental technique for the determination of uranium and thorium in coal by epithermal neutron activation was developed and systemized. Seventeen different coal samples, six copper monitors for neutron flux corrections and three NBS standard coal samples were irradiated together in a cadmium cylinder. Uranium and thorium were determined by measuring the 239 N sub(p) and 233 P sub(a) activities respectively, being both produced in (n,γ) reactions and subsequent β - decay. The 239 N sub(p) was measured by counting the 106.4 KeV γ-ray in a LEPS detector and the 233 P sub(a) by counting the 311.8 KeV γ-ray, but in a Ge(Li) detector. A 4096 multichannel analizer and a PDP-11 computer complemented the basic measuring equipment. An average precision of 3% was obtained in the analysis of seventeen coal samples coming from different strata and heights of Charqueadas and Morungava mines in Rio Grande do Sul State. The sensitivity of the method is around 100 ppb. This technique will allow determinations of up to twenty elements, besides uranium and thorium, and it can be applied in routine analysis. (Author) [pt

Fixation and separation of the elements thorium and uranium using anion exchange resins in nitrate solution

International Nuclear Information System (INIS)

Korgaonkar, V.

1967-10-01

The exchange of thorium and uranium between a strong base anion resin and a mixed water + ethanol solvent containing nitrate ions is studied. It is assumed that in the resin the thorium and uranium are fixed in the form of the complexes Th(NO 3 ) 6 2- and UO 2 (NO 3 ) 4 2- in solution these elements are present in the form of complexes having the general formula: Th(NO 3 ) 6-n n-2 and UO 2 (NO 3 ) 4-n n-2 It has been possible to deduce a law for the changes in the partition functions of thorium and uranium as a function of the concentrations of the various species in solution and of the complexing ion NO 3 . From this has been deduced the optimum operational conditions for separating a mixture of these two elements. Finally, in these conditions, the influence of a few interfering ions has been studied: Ba, Bi, Ce, La, Mo, Pb, Zr. The method proposed can be used either as a preparation, or for the dosage of thorium by a quantitative separation. (author) [fr

Feasibility study on AFR-100 fuel conversion from uranium-based fuel to thorium-based fuel

Energy Technology Data Exchange (ETDEWEB)

Heidet, F.; Kim, T.; Grandy, C. (Nuclear Engineering Division)

2012-07-30

Although thorium has long been considered as an alternative to uranium-based fuels, most of the reactors built to-date have been fueled with uranium-based fuel with the exception of a few reactors. The decision to use uranium-based fuels was initially made based on the technology maturity compared to thorium-based fuels. As a result of this experience, lot of knowledge and data have been accumulated for uranium-based fuels that made it the predominant nuclear fuel type for extant nuclear power. However, following the recent concerns about the extent and availability of uranium resources, thorium-based fuels have regained significant interest worldwide. Thorium is more abundant than uranium and can be readily exploited in many countries and thus is now seen as a possible alternative. As thorium-based fuel technologies mature, fuel conversion from uranium to thorium is expected to become a major interest in both thermal and fast reactors. In this study the feasibility of fuel conversion in a fast reactor is assessed and several possible approaches are proposed. The analyses are performed using the Advanced Fast Reactor (AFR-100) design, a fast reactor core concept recently developed by ANL. The AFR-100 is a small 100 MW{sub e} reactor developed under the US-DOE program relying on innovative fast reactor technologies and advanced structural and cladding materials. It was designed to be inherently safe and offers sufficient margins with respect to the fuel melting temperature and the fuel-cladding eutectic temperature when using U-10Zr binary metal fuel. Thorium-based metal fuel was preferred to other thorium fuel forms because of its higher heavy metal density and it does not need to be alloyed with zirconium to reduce its radiation swelling. The various approaches explored cover the use of pure thorium fuel as well as the use of thorium mixed with transuranics (TRU). Sensitivity studies were performed for the different scenarios envisioned in order to determine the

Comparison of uranium and radium isotopes activities in some wells and thermal springs samples in Morroco

International Nuclear Information System (INIS)

Hakam, O.K.; Choukri, A.; Reyss, J.L.; Lferde, M.

2000-01-01

Activities and activity ratios of uranium and radium isotopes ( 234 U, 238 U, 226 Ra, 228 Ra, 234 U/ 238 U, 226 Ra/ 238 U, 228 Ra/ 226 Ra) have been determined, for the first time in Morocco, for 15 well water samples and 12 spring water samples. The obtained results show that, unlike well waters, the thermal spring waters present relatively low 238 U activities and elevated 226 Ra activities and 234 U/ 238 U activity ratios. Uranium and radium activities are similar to those published for other non polluting regions of the world, they are inferior to the Maximum Contaminant Levels and don't present any risk for public health in Morocco. (author) [fr

Radium and uranium levels in vegetables grown using different farming management systems

Energy Technology Data Exchange (ETDEWEB)

Lauria, D.C. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Av. Salvador Allende s/n, Recreio dos Bandeirantes, Rio de Janeiro, RJ, CEP 22780-160 (Brazil)], E-mail: dejanira@ird.gov.br; Ribeiro, F.C.A. [Centro Regional de Ciencias Nucleares (CRCN/CNEN), Av. Prof. Luiz Freire 200, Cidade Universitaria Recife, PE, CEP 50740-540 (Brazil); Conti, C.C. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Av. Salvador Allende s/n, Recreio dos Bandeirantes, Rio de Janeiro, RJ, CEP 22780-160 (Brazil); Loureiro, F.A. [Estacao Experimental de Nova Friburgo, Empresa de Pesquisa Agropecuaria do Estado do Rio de Janeiro, Pesagro (Brazil)

2009-02-15

Vegetables grown with phosphate fertilizer (conventional management), with bovine manure fertilization (organic management) and in a mineral nutrient solution (hydroponic) were analyzed and the concentrations of {sup 238}U, {sup 226}Ra and {sup 228}Ra in lettuce, carrots, and beans were compared. Lettuce from hydroponic farming system showed the lowest concentration of radionuclides 0.51 for {sup 226}Ra, 0.55 for {sup 228}Ra and 0.24 for {sup 238}U (Bq kg{sup -1} dry). Vegetables from organically and conventionally grown farming systems showed no differences in the concentration of radium and uranium. Relationships between uranium content in plants and exchangeable Ca and Mg in soil were found, whereas Ra in vegetables was inversely correlated to the cation exchange capacity of soil, leading to the assumption that by supplying carbonate and cations to soil, liming may cause an increase of U and a decrease of radium uptake by plants. The soil to plant transfer varied from 10{sup -4} to 10{sup -2} for {sup 238}U and from 10{sup -2} to 10{sup -1} for {sup 228}Ra.

Radium and uranium levels in vegetables grown using different farming management systems

International Nuclear Information System (INIS)

Lauria, D.C.; Ribeiro, F.C.A.; Conti, C.C.; Loureiro, F.A.

2009-01-01

Vegetables grown with phosphate fertilizer (conventional management), with bovine manure fertilization (organic management) and in a mineral nutrient solution (hydroponic) were analyzed and the concentrations of 238 U, 226 Ra and 228 Ra in lettuce, carrots, and beans were compared. Lettuce from hydroponic farming system showed the lowest concentration of radionuclides 0.51 for 226 Ra, 0.55 for 228 Ra and 0.24 for 238 U (Bq kg -1 dry). Vegetables from organically and conventionally grown farming systems showed no differences in the concentration of radium and uranium. Relationships between uranium content in plants and exchangeable Ca and Mg in soil were found, whereas Ra in vegetables was inversely correlated to the cation exchange capacity of soil, leading to the assumption that by supplying carbonate and cations to soil, liming may cause an increase of U and a decrease of radium uptake by plants. The soil to plant transfer varied from 10 -4 to 10 -2 for 238 U and from 10 -2 to 10 -1 for 228 Ra

Radium and uranium levels in vegetables grown using different farming management systems.

Science.gov (United States)

Lauria, D C; Ribeiro, F C A; Conti, C C; Loureiro, F A

2009-02-01

Vegetables grown with phosphate fertilizer (conventional management), with bovine manure fertilization (organic management) and in a mineral nutrient solution (hydroponic) were analyzed and the concentrations of (238)U, (226)Ra and (228)Ra in lettuce, carrots, and beans were compared. Lettuce from hydroponic farming system showed the lowest concentration of radionuclides 0.51 for (226)Ra, 0.55 for (228)Ra and 0.24 for (238)U (Bq kg(-1) dry). Vegetables from organically and conventionally grown farming systems showed no differences in the concentration of radium and uranium. Relationships between uranium content in plants and exchangeable Ca and Mg in soil were found, whereas Ra in vegetables was inversely correlated to the cation exchange capacity of soil, leading to the assumption that by supplying carbonate and cations to soil, liming may cause an increase of U and a decrease of radium uptake by plants. The soil to plant transfer varied from 10(-4) to 10(-2) for (238)U and from 10(-2) to 10(-1) for (228)Ra.

Radiotoxicity study of a boiling water reactor core design based on a thorium-uranium fuel concept

International Nuclear Information System (INIS)

Nunez C, A.; Espinosa P, G.

2007-01-01

Full text: The innovative design of a Boiling Water Reactor (BWR) equilibrium core using the thorium-uranium (blanket-seed) concept in the same integrated fuel assembly is presented in this paper. The lattice design uses the thorium conversion capability to 233 U in a BWR spectrum. A core design was developed to achieve an equilibrium cycle of one effective full power year in a standard BWR. A comparison of the toxicity of the spent fuel showed that toxicity is lower in the thorium cycle than other commercial fuels as UO 2 and MOX (uranium and plutonium) in case of the one-through cycle for LWR. (Author)

Determining factors in the elimination of uranium and radium from groundwaters during a standard potabilization process

Energy Technology Data Exchange (ETDEWEB)

Baeza, A. [Departamento de Fisica, Facultad de Veterinaria, Universidad de Extremadura, Avda. de la Universidad s/n 10071 Caceres (Spain)], E-mail: ymiralle@unex.es; Salas, A. [Departamento de Fisica, Facultad de Veterinaria, Universidad de Extremadura, Avda. de la Universidad s/n 10071 Caceres (Spain); Legarda, F. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Superior de Ingenieros, Universidad de Pais Vasco, Alameda de Urquijo s/n 48013 Bilbao (Spain)

2008-11-15

We studied the physico-chemical and radioactive characteristics of four waters of subsurface origin. They were chosen for having the highest natural radioactivity levels of waters for human consumption in the Autonomous Community of Extremadura, Spain Their activity levels for alpha emitting radionuclides are between 120 and 19 300 mBq L{sup -1}, all exceeding the 100 mBq L{sup -1} threshold established in the European Union above which radioactive isotopes that are present in water should be investigated to determine which corrective action, if any, is needed. These waters were used to compare the efficiency in eliminating their uranium and radium content of two potabilization processes - one the standard chlorination-only process used by their respective municipalities, and the other a procedure consisting of coagulation, flocculation, settling, filtration, and chlorination stages, specifically designed to maximize the elimination of their natural radioactive content. The results showed the uranium and radium elimination efficiencies to depend strongly on the water's hydrogencarbonate, calcium, and magnesium ion concentrations. In particular, with increasing concentrations of any of these ions, the uranium elimination efficiency fell from 90% to 60% at its optimal working pH, pH = 6, while the radium elimination efficiency rose from 50% to 90% at its optimal working pH, pH = 10.

Determining factors in the elimination of uranium and radium from groundwaters during a standard potabilization process.

Science.gov (United States)

Baeza, A; Salas, A; Legarda, F

2008-11-15

We studied the physico-chemical and radioactive characteristics of four waters of subsurface origin. They were chosen for having the highest natural radioactivity levels of waters for human consumption in the Autonomous Community of Extremadura, Spain Their activity levels for alpha emitting radionuclides are between 120 and 19300 mBq L(-1), all exceeding the 100 mBq L(-1) threshold established in the European Union above which radioactive isotopes that are present in water should be investigated to determine which corrective action, if any, is needed. These waters were used to compare the efficiency in eliminating their uranium and radium content of two potabilization processes - one the standard chlorination-only process used by their respective municipalities, and the other a procedure consisting of coagulation, flocculation, settling, filtration, and chlorination stages, specifically designed to maximize the elimination of their natural radioactive content. The results showed the uranium and radium elimination efficiencies to depend strongly on the water's hydrogencarbonate, calcium, and magnesium ion concentrations. In particular, with increasing concentrations of any of these ions, the uranium elimination efficiency fell from 90% to 60% at its optimal working pH, pH=6, while the radium elimination efficiency rose from 50% to 90% at its optimal working pH, pH=10.

Determining factors in the elimination of uranium and radium from groundwaters during a standard potabilization process

International Nuclear Information System (INIS)

Baeza, A.; Salas, A.; Legarda, F.

2008-01-01

We studied the physico-chemical and radioactive characteristics of four waters of subsurface origin. They were chosen for having the highest natural radioactivity levels of waters for human consumption in the Autonomous Community of Extremadura, Spain Their activity levels for alpha emitting radionuclides are between 120 and 19 300 mBq L -1 , all exceeding the 100 mBq L -1 threshold established in the European Union above which radioactive isotopes that are present in water should be investigated to determine which corrective action, if any, is needed. These waters were used to compare the efficiency in eliminating their uranium and radium content of two potabilization processes - one the standard chlorination-only process used by their respective municipalities, and the other a procedure consisting of coagulation, flocculation, settling, filtration, and chlorination stages, specifically designed to maximize the elimination of their natural radioactive content. The results showed the uranium and radium elimination efficiencies to depend strongly on the water's hydrogencarbonate, calcium, and magnesium ion concentrations. In particular, with increasing concentrations of any of these ions, the uranium elimination efficiency fell from 90% to 60% at its optimal working pH, pH = 6, while the radium elimination efficiency rose from 50% to 90% at its optimal working pH, pH = 10

Qualitative microanalysis of rare earths (ceric and yttric), of thorium and uranium in minerals; Microanalyse qualitative des terres rares (ceriques et yttriques), du thorium et de l'uranium dans les mineraux

Energy Technology Data Exchange (ETDEWEB)

Agrinier, H [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

1955-07-01

We propose in this study to give a general method of attack of the niobio-titanates, niobio-tantalates, oxides, phosphates or silicates containing rare earths (ceric or yttric), uranium or thorium, and to put in evidence these different elements by microchemical reactions giving crystallization or the characteristic colorations. (M.B.) [French] Nous nous proposons dans cette etude de donner une methode generale d'attaque des niobotitanates, niobotantalates, oxydes, phosphates ou silicates contenant des terres rares (ceriques ou yttriques), de l'uranium ou du thorium, et de mettre en evidence ces differents elements au moyen de reactiors microchimiques donnant des cristallisations ou des colorations caracteristiques. (MB)

Device for the chlorinating volatization of thorium and/or uranium

International Nuclear Information System (INIS)

Laser, M.; Bohnenstingl, J.; Fischer, E.

1976-01-01

The invention relates to a device for the chlorinating volatization of nuclear fuel or breeding elements, preferably of thorium or uranium carbide and/or thorium or uranium oxide. A cupola furnace serves as reaction vessel, being connected to the condenser via a reactiongas pipe. In the interior of the cupola furnace, a tube is arranged consisting of porous graphite and heatable by direct current transfer, the tube being surrounded by a casing of ceramic material (sillimanite or rotosile). The chlorine gas is introduced into the cupola furnace via an additional socket. The gaseous reaction products penetrate the porous wall of the inner tube and enter the condenser first via the space between casing and inner tube and then via the reaction-gas pipe. The condenser consists of a gas-permeable tube and a surrounding tube, the space between being passed by the coolant gas. The maximum grain size of the ground pellets should be smaller than 300 μm. (HPH) [de

Occupational exposure to nickel, uranium and thorium in a nickel mine

International Nuclear Information System (INIS)

Azeredo, A.M.; Lipsztein, J.L.; Dias da Cunha, K.; Lourenco, M.C.; Lipsztein, J.L.; Miekeley, N.T.

2002-01-01

The workers involved in mining and milling ores are exposed in the workplace to many hazardous agents that can cause a health detriment. In this work, the measurements obtained in a nickel mineral processing facility in the Brazilian Central-West are presented. One of the most important hazardous agents in this facility is the aerosol present in the air that contains nickel, uranium and thorium. The aerosol is inhaled or ingested, metabolised and deposited in the whole body or in specific organs. The surveillance of internal contamination of workers was performed by analysis of urine, fecal and hair samples. The ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) method was used to analytically determine nickel, uranium and thorium in these biological samples. Additional data were obtained by the collection of air samples in the workplace. A cascade impactor with six stages was used to collect mineral dust particles with an aerodynamic diameter in the range of 0.64 to 19.4 μm. The particles impacted in each stage of the cascade impactor were analysed by PIXE (Particle Induced X ray Emission), which permits the determination of elemental mass air concentration and the MMAD (Mass Median Aerodynamic Diameter). The concentrations of nickel, uranium and thorium were determined in the aerosol samples. All the results were analysed using statistical methods and biokinetical modelling was applied to evaluate the internal contamination and to make a risk estimation. (author)

Fluor determination by alkaline hydrolysis of the uranium and thorium fluorides

International Nuclear Information System (INIS)

Barrachina Gomez, L.; Gasco Sanchez, L.

1961-01-01

The alkaline hydrolysis of the uranium and thorium fluorides is studded and a new method for the determination of the fluoride, on the basis of a indirect volumetric titration with standard soda, is proposed. The compounds that may influence the hydrolysis of the uranium fluoride and that may be occasionally found in it as impurities are also studied. the method can be applied to the uranium fluoride except when there is a great quantity of F 2 UO 2 or UO 3 present in the sample. (Author) 20 refs

Arbuscular mycorrhiza reduces phytoextraction of uranium, thorium and other elements from phosphate rock

International Nuclear Information System (INIS)

Roos, Per; Jakobsen, Iver

2008-01-01

Uptake of metals from uranium-rich phosphate rock was studied in Medicago truncatula plants grown in symbiosis with the arbuscular mycorrhizal fungus Glomus intraradices or in the absence of mycorrhizas. Shoot concentrations of uranium and thorium were lower in mycorrhizal than in non-mycorrhizal plants and root-to-shoot ratio of most metals was increased by mycorrhizas. This protective role of mycorrhizas was observed even at very high supplies of phosphate rock. In contrast, phosphorus uptake was similar at all levels of phosphate rock, suggesting that the P was unavailable to the plant-fungus uptake systems. The results support the role of arbuscular mycorrhiza as being an important component in phytostabilization of uranium. This is the first study to report on mycorrhizal effect and the uptake and root-to-shoot transfer of thorium from phosphate rock

Arbuscular mycorrhiza reduces phytoextraction of uranium, thorium and other elements from phosphate rock

Energy Technology Data Exchange (ETDEWEB)

Roos, Per [Radiation Research Department, Riso National Laboratory, Technical University of Denmark, DK-4000 Roskilde (Denmark); Jakobsen, Iver [Biosystems Department, Riso National Laboratory, Technical University of Denmark, DK-4000 Roskilde (Denmark)], E-mail: iver.jakobsen@risoe.dk

2008-05-15

Uptake of metals from uranium-rich phosphate rock was studied in Medicago truncatula plants grown in symbiosis with the arbuscular mycorrhizal fungus Glomus intraradices or in the absence of mycorrhizas. Shoot concentrations of uranium and thorium were lower in mycorrhizal than in non-mycorrhizal plants and root-to-shoot ratio of most metals was increased by mycorrhizas. This protective role of mycorrhizas was observed even at very high supplies of phosphate rock. In contrast, phosphorus uptake was similar at all levels of phosphate rock, suggesting that the P was unavailable to the plant-fungus uptake systems. The results support the role of arbuscular mycorrhiza as being an important component in phytostabilization of uranium. This is the first study to report on mycorrhizal effect and the uptake and root-to-shoot transfer of thorium from phosphate rock.

Radium equivalent activity of building materials and gamma ray dose rates in ordinary houses of Sao Paulo, Brazil

International Nuclear Information System (INIS)

Campos, M.P.; Pecequilo, B.R.S.

1994-01-01

The external radiation exposure from natural radioactivity represents, approximately, 50% of the average annual dose caused to the human body by all natural and artificial radiation sources. Natural radioactivity in building materials is the most important source of external radiation exposure in dwellings because of the gamma rays emitted from potassium 40 and member of the uranium 238 and thorium 232 decay chains. Concrete is one of the most potential sources of elevated radiation exposure, however, little is known about the natural radioactivity of Brazilian construction materials. A study to predict the exposure rates of several ordinary houses built almost of concrete, consisting of 38 samples of 6 different materials was conducted by using high resolution gamma-ray spectrometry. The radium equivalent activity was calculated for all 38 samples in order to compare the specific activities of the construction materials containing different amounts of radium, thorium, and potassium. The effective dose rate due to the indoor gamma radiation from the building materials was performed following the 1988 UNSCEAR procedures

Coordination compounds of titanium, zirconium, tin, thorium and uranium

International Nuclear Information System (INIS)

Deshpande, S.G.; Jain, S.C.

1990-01-01

Reactions of isatin, furoic acid and picolinic acid have been carried out with titanium tetrachloride, tin tetrachloride, thorium tetrachloride, zirconyl chloride and uranyl nitrate. While 2:3(metal:ligand) type compounds of isatin have been obtained with Ti(IV) and Sn(IV), zirconium(IV), thorium(IV), and uranium(VI) do not react with the ligand under similar experimental conditions. Furoic acid (FAH) and picolinic acid(PicH) form various chloro furoates and picolinates when reacted with TiCl 4 , ZrOCl 2 and ThCl 4 , but do not react with SnCl 4 . The various compounds synthesised have been characterised on the basis of elemental analysis, infrared studies, conductivity and thermogravimetric measurements. (author). 1 tab., 10 refs

Biogeochemical investigation in south eastern Andhra Pradesh: the distribution of rare earths, thorium and uranium in plants and soils

International Nuclear Information System (INIS)

Raju, K.K.; Raju, A.N.

2000-01-01

The concentration of rare earth elements (REE), thorium and uranium were determined by inductively coupled plasma mass spectrometry (ICP-MS) in the plant species, Pterocarpus santalinus, P. marsupium and P. dalbergioides, and the soils on which they were growing. Higher concentrations of lanthanum (La), cerium (Ce) were observed in both plants and soils. Large amounts of thorium and uranium were found in the soil. In all tree species, the concentration of REEs were higher in the heartwood than the leaves. The heartwood of P. santalinus accumulated larger quantities of uranium (average concentration of 1.22 ppm) and thorium (mean value of 2.57 ppm) than the other two species. (orig.)

Anticipated radiological impacts from the mining and milling of thorium for the nonproliferative fuels

International Nuclear Information System (INIS)

Meyer, H.R.; Till, J.E.

1978-01-01

Recent emphasis on proliferation-resistant fuel cycles utilizing thorium--uranium-233 fuels has necessitated evaluation of the potential radiological impact of mining and milling thorium ore. Therefore, an analysis has been completed of hypothetical mine-mill complexes using population and meteorological data representative of a thorium resource site in the Lemhi Pass area of Idaho/Montana, United States of America. Source terms for the site include thorium-232 decay chain radionuclides suspended as dusts and radon-220 and daughters initially released as gas. Fifty-year dose commitments to maximally exposed individuals of 2.4 mrem to total body, 9.5 mrem to bone, and 35 mrem to lungs are calculated to result from facility operation. Radium-228, thorium-228, thorium-232 and lead-212 (daughter of radon-220) are found to be the principal contributors to dose. General population doses for a 50-mile radius surrounding the facility are estimated to be 0.05 man-rem to total body, 0.1 man-rem to bone, and 0.7 man-rem to lungs. Generally speaking, the results of this study indicate that the radiological aspects of thorium mining and milling should pose no significant problems with regard to implementation of thorium fuel cycles

Natural Transmutation of Actinides via the Fission Reaction in the Closed Thorium-Uranium-Plutonium Fuel Cycle

Science.gov (United States)

Marshalkin, V. Ye.; Povyshev, V. M.

2017-12-01

It is shown for a closed thorium-uranium-plutonium fuel cycle that, upon processing of one metric ton of irradiated fuel after each four-year campaign, the radioactive wastes contain 54 kg of fission products, 0.8 kg of thorium, 0.10 kg of uranium isotopes, 0.005 kg of plutonium isotopes, 0.002 kg of neptunium, and "trace" amounts of americium and curium isotopes. This qualitatively simplifies the handling of high-level wastes in nuclear power engineering.

The Amster concept: a configuration generating its own uranium with a mixed thorium and uranium support

International Nuclear Information System (INIS)

Vergnes, J.; Garzenne, C.; Lecarpentier, D.; Mouney, H.; Delpech, M.

2001-01-01

AMSTER is a continuously reloaded, graphite-moderated molten salt critical reactor, using a 238 U or 232 Th fuel support, slightly enriched with 235 U if necessary. Using this concept, one can define a large number of configurations according to the products loaded and recycled. The choice of thorium fuel support leads to two configurations requiring no additional 235 U as fissile material: a configuration with one moderating zone, incinerating Transuranium elements (TRU); a configuration with 2 moderating zones self-consuming TRU and regenerating the fissile uranium ( 233 U). In this configuration, it is even possible to burn 238 U (from depleted uranium) by adding it to the thorium support. These configurations use a minimum amount of fuel (100 kg of 232 Th or 100 kg of a 232 Th- 238 U mix per TWh) and produce very little TRU (a few tens of grams per TWh). (author)

All heavy metals closed-cycle analysis on water-cooled reactors of uranium and thorium fuel cycle systems

International Nuclear Information System (INIS)

Permana, Sidik; Sekimoto, Hiroshi; Waris, Abdul; Takaki, Naoyuki

2009-01-01

Uranium and Thorium fuels as the basis fuel of nuclear energy utilization has been used for several reactor types which produce trans-uranium or trans-thorium as 'by product' nuclear reaction with higher mass number and the remaining uranium and thorium fuels. The utilization of recycled spent fuel as world wide concerns are spent fuel of uranium and plutonium and in some cases using recycled minor actinide (MA). Those fuel schemes are used for improving an optimum nuclear fuel utilization as well to reduce the radioactive waste from spent fuels. A closed-cycle analysis of all heavy metals on water-cooled cases for both uranium and thorium fuel cycles has been investigated to evaluate the criticality condition, breeding performances, uranium or thorium utilization capability and void reactivity condition. Water-cooled reactor is used for the basic design study including light water and heavy water-cooled as an established technology as well as commercialized nuclear technologies. A developed coupling code of equilibrium fuel cycle burnup code and cell calculation of SRAC code are used for optimization analysis with JENDL 3.3 as nuclear data library. An equilibrium burnup calculation is adopted for estimating an equilibrium state condition of nuclide composition and cell calculation is performed for calculating microscopic neutron cross-sections and fluxes in relation to the effect of different fuel compositions, different fuel pin types and moderation ratios. The sensitivity analysis such as criticality, breeding performance, and void reactivity are strongly depends on moderation ratio and each fuel case has its trend as a function of moderation ratio. Heavy water coolant shows better breeding performance compared with light water coolant, however, it obtains less negative or more positive void reactivity. Equilibrium nuclide compositions are also evaluated to show the production of main nuclides and also to analyze the isotopic composition pattern especially

A density functional theory study of uranium-doped thoria and uranium adatoms on the major surfaces of thorium dioxide

Energy Technology Data Exchange (ETDEWEB)

Shields, Ashley E. [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Santos-Carballal, David [School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom); Leeuw, Nora H. de, E-mail: DeLeeuwN@Cardiff.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom)

2016-05-15

Thorium dioxide is of significant research interest for its use as a nuclear fuel, particularly as part of mixed oxide fuels. We present the results of a density functional theory (DFT) study of uranium-substituted thorium dioxide, where we found that increasing levels of uranium substitution increases the covalent nature of the bonding in the bulk ThO{sub 2} crystal. Three low Miller index surfaces have been simulated and we propose the Wulff morphology for a ThO{sub 2} particle and STM images for the (100), (110), and (111) surfaces studied in this work. We have also calculated the adsorption of a uranium atom and the U adatom is found to absorb strongly on all three surfaces, with particular preference for the less stable (100) and (110) surfaces, thus providing a route to the incorporation of uranium into a growing thoria particle. - Highlights: • Uranium substitution in ThO{sub 2} is found to increase the covalent nature of the ionic bonding. • The (111), (110), and (100) surfaces of ThO{sub 2} are studied and the particle morphology is proposed. • STM images of the (111), (110), and (100) surfaces of ThO{sub 2} are simulated. • Uranium adsorption on the major surfaces of ThO{sub 2} is studied.

Phthalocyaninato complexes of thorium, protactinium and uranium

International Nuclear Information System (INIS)

Beck, O.F.

1985-01-01

For the preparation of Bis(phthalocyaninato)-actinoid(IV) complexes, AnPc 2 , a new optimizing synthesis procedure was developed, with which it was possible to prepare spectrally pure, that is, H 2 Pc-free, ThPc 2 , UPc 2 and the isostructurally similar 231 PaPc 2 .PaPc 2 . This was verified with the help of electron spectra, which were compared to preparations which were synthesized in another manner. The corresponding perfluorinated compounds were also produced for thorium and uranium by use of tetrafluorophthalic acid nitrile instead of phthalic acid nitrile as initial product. Electron and infrared spectra show the typical bands of the non-substituted complexes. By the attempt to produce a mono(phthalocyaninato)-thorium complex with the use of ThI 4 as initial material a pyridine-extracted pure ThPcI 2 (py) 2 was obtained with a typical mono(phthalocyaninato) complex electron spectrum, an extremely moisture sensitive compound which in water or acids decomposes and produces H 2 Pc. (orig./RB) [de

Uranium, radium and 40K isotopes in bottled mineral waters from Outer Carpathians, Poland

International Nuclear Information System (INIS)

Kozlowska, B.; Walencik, A.; Dorda, J.; Przylibski, T.A.

2007-01-01

Radioactivity content in commercially bottled mineral waters from Outer Carpathians was investigated on the basis of 28 samples. Activity concentration results for radium isotopes 226,228 Ra, uranium isotopes 234,238 U and isotopic ratios 234 U/ 238 U were determined. The correlations between investigated isotopes and calculated potassium 40 K ions dissolved in water were carried out. The results show a correlation between TDS (total dissolved solids) values and dissolved radionuclides. High correlation coefficients were observed between total radium content and 40 K. The isotopic ratio of 234 U/ 238 U varies in the range from 1.6 to 7 in all investigated waters which means that there is no radioactive equilibrium between the parent nuclide 238 U and its daughter 234 U. The effective radiation dose coming from studied radium and uranium radionuclides consumed with mineral water from the Outer Carpathians obtained by a statistical Pole is equal to 4.3μSv/year (58 l/year water consumption) and do not exceed the permissible limit equal to 100μSv/year. Assuming 0.5 l consumption per day, i.e. 182.5 l/year, the effective dose is equal to 13.4μSv/year, what is still below the unit

Preconcentration of low-grade uranium ores with environmentally acceptable tailings, part I

International Nuclear Information System (INIS)

Raicevic, D.; Raicevic, M.; McCarthy, D.R.

1979-08-01

The low-grade ore sample used for this investigation originated from Agnew Lake Mines Limited, Espanola, Ontario. It contained about 1% pyrite and 0.057% uranium, mainly as uranothorite with a small amount of brannerite. Both of these minerals occur in the quartz-sericite matrix of a conglomerate. A preconcentration process has been developed to give a high uranium recovery, reject pyrite, radium and thorium from the ore and produce environmentally acceptable tailings. This process applies flotation in combination with high intensity magnetic separation and gravity concentration

Method to evaluate covariance data for the thorium-uranium fuel cycle

International Nuclear Information System (INIS)

Kawano, T.; Chadwick, M.B.

2003-01-01

This power point presentation gives an overview about the evaluation strategy for the experimental data for the thorium-uranium fuel cycle. Uncertainties, error propagation and calculation methods are outlined. Covariance evaluation tools and computer codes have been developed and results are presented

Recovery of valuable products in the raffinate of the uranium and thorium pilot-plant

International Nuclear Information System (INIS)

Jardim, E.A.; Abrao, A.

1988-11-01

IPEN-CNEN/SP has being very active in refining yellowcake to pure ammonium diuranate which is converted to uranium trioxide, uranium dioxide, tetra - and hexafluoride in a sequential way. The technology of the thorium purification and its conversion to nuclear grade products has been a practice since several years as well. For both elements the major to be worked is the raffinate from the solvent extraction colum where and thorium are purified via TBP-varsol in pulsed columns. In this paper the actual processing technology is reviewed with special emphasis on the recovery of valuable products, mainly nitric acid and ammonium nitrate. Distilled nitric acid and the final sulfuric acid as residue are recycle. Ammonium nitrate from the precipitation of uranium diuranate is of good quality, being radioactivity and uranium - free, and recommended to be applied as fertilizer. In conclusion the main effort is to maximize the recycle and reuse of the above mentioned chemicals. (author) [pt

Towards proliferation-resistant thorium fuels

International Nuclear Information System (INIS)

Alhaj, M. Yousif; Mohamed, Nader M.A.; Badawi, Alya; Abou-Gabal, Hanaa H.

2017-01-01

Thorium-plutonium mixture is proposed as alternative nuclear reactor fuel to incinerate the increasing stockpile plutonium. However, this fuel will produce an amount of uranium with about 90% 233U at applicable discharge burnups (60GWD/MTU). This research focuses on proposing an optimum non proliferative thorium fuel, by adding a small amount of 238U to reduce the attractiveness of the resultant uranium. Three types of additive which contain 238U were used: 4.98% enriched, natural and depleted uranium. We found that introducing uranium to the fresh thorium-plutonium fuel reduces its performance even if the uranium was enriched up to 5%. While uranium admixtures reduce the quality of the reprocessed uranium, it also increases the quality of the plutonium. However, this increase is very low compared to the reduced quality of uranium. We also found that using uranium as admixture for thorium-plutonium mixed fuel increases the critical mass of the extracted uranium by a factor of two when using only 1% admixture of uranium. The higher the percentage of uranium admixture the higher the critical mass of the reprocessed one.

An extraction method of uranium 233 from the thorium irradiates in a reactor core

International Nuclear Information System (INIS)

Chesne, A.; Regnaut, P.

1955-01-01

Description of the conditions of separation of the thorium, of the uranium 233 and of the protactinium 233 in hydrochloric solution by absorption then selective elution on anion exchange resin. A precipitation of the thorium by the oxalic acid permits the recuperation of the hydrochloric acid which is recycled, the main, raw material consumed being the oxalic acid. (authors) [fr

Radium Adsorption to Iron Bearing Minerals in Variable Salinity Waters

Science.gov (United States)

Chen, M.; Kocar, B. D.

2014-12-01

Radium is a common, naturally occurring radioactive metal found in many subsurface environments. Radium isotopes are a product of natural uranium and thorium decay, and are particularly abundant within groundwaters where minimal flux leads to accumulation within porewaters. Radium has been used as a natural tracer to estimate submarine groundwater discharge (SGD) [1], where the ratios of various radium isotopes are used to estimate total groundwater flux to and from the ocean [2]. Further, it represents a substantial hazard in waste water produced after hydraulic fracturing for natural gas extraction [3], resulting in a significant risk of environmental release and increased cost for water treatment or disposal. Adsorption to mineral surfaces represents a primary pathway of radium retention within subsurface environments. For SGD studies, it is important to understand adsorption processes to correctly estimate GW fluxes, while in hydraulic fracturing, radium adsorption to aquifer solids will mediate the activities of radium within produced water. While some studies of radium adsorption to various minerals have been performed [4], there is a limited understanding of the surface chemistry of radium adsorption, particularly to iron-bearing minerals such as pyrite, goethite and ferrihydrite. Accordingly, we present the results of sorption experiments of radium to a suite of iron-bearing minerals representative of those found within deep saline and near-surface (freshwater) aquifers, and evaluate impacts of varying salinity solutions through the use of artificial groundwater, seawater, and shale formation brine. Further, we explore the impacts of pyrite oxidation and ferrihydrite transformation to other iron-bearing secondary minerals on the retention of radium. This work lays the groundwork for further study of radium use as a tracer for SGD, as well as understanding mechanisms of radium retention and release from deep aquifer materials following hydraulic fracturing

A data base for PHW reactor operating on a once-through, low enriched uranium-thorium cycle

International Nuclear Information System (INIS)

Lungu, S.

1984-04-01

The study of a detailed data base for a new once-through uranium-thorium cycle using low enriched uranium (4 and 5,5% wt. U-235) and distinct UO 2 and ThO 2 fuel channels has been performed. With reference to a standard 638 MWe CANDU-type PHWR with 380 channels, evaluation of economics, fuel behaviour and safety has been performed. The Feinberg-Galanin method (code FEINGAL) has been used for calculation of axial flux distribution. All parameters have been provided by LATREP code following up the irradiation history. Economical assessment has shown that this fuel cycle is competitive with the natural uranium fuel cycle for 1979-based values of the parameters. Fuel behaviour and safety features modelling has shown that core behaviour of the uranium-thorium reactor under abnormal and accident conditions would be at least as good as that of the standard natural uranium reactor

The development of the production process for the thorium/uranium dicarbide fuel kernels for the first charge of the Dragon Reactor

International Nuclear Information System (INIS)

Burnett, R.C.; Hankart, L.J.; Horsley, G.W.

1965-05-01

The development of methods of producing spheroidal sintered porous kernels of hyperstoichiometric thorium/uranium dicarbide solid solution from thorium/uranium monocarbide/carbon and thoria/urania/carbon powder mixes is described. The work has involved study of (i) Methods of preparing green kernels from UC/Th/C powder mixes using the rotary sieve technique. (ii) Methods of producing green kernels from UO2/Th02/C powder mixes using the planetary mill technique. (iii) The conversion by appropriate heat treatment of green kernels produced by both routes to sintered porous kernels of thorium/uranium carbide. (iv) The efficiency of the processes. (author)

Transfer of radionuclides from the environment to human milk

International Nuclear Information System (INIS)

Chiu, N.; Dean, J.; Veska, E.

1988-03-01

This report gives detailed procedures for: collecting, storing and shipping human milk samples; complete decomposition of human milk samples by nitric acid-perchloric acid oxidation; and sequential separation and determinations of lead 210, radium 226, thorium 230, natural thorium and natural uranium from decomposed human milk solutions. This sequential separation method is capable of detecting 0.025 Bq of radium 226, thorium 230 and thorium 232 and 0.05 Bq of lead 210. Recoveries are approximately 70% for radium 226 and 90% for thorium 230, thorium 232 and lead 210. This report also outlines a proposed field study program

Occurrence of Radium-224, Radium-226 and Radium-228 in Water from the Vincentown and Wenonah-Mount Laurel Aquifers, the Englishtown Aquifer System, and the Hornerstown and Red Bank Sands, Southwestern and South-Central New Jersey

Science.gov (United States)

dePaul, Vincent T.; Szabo, Zoltan

2007-01-01

This investigation is the first regionally focused study of the presence of natural radioactivity in water from the Vincentown and Wenonah-Mount Laurel aquifers, Englishtown aquifer system, and the Hornerstown and Red Bank Sands. Geologic materials composing the Vincentown and Wenonah-Mount Laurel aquifers and the Hornerstown and Red Bank Sands previously have been reported to contain radioactive (uranium-enriched) phosphatic strata, which is common in deposits from some moderate-depth coastal marine environments. The decay of uranium and thorium gives rise to natural radioactivity and numerous radioactive progeny, including isotopes of radium. Naturally occurring radioactive isotopes, especially those of radium, are of concern because radium is a known human carcinogen and ingestion (especially in water used for drinking) can present appreciable health risks. A regional network in southwestern and south-central New Jersey of 39 wells completed in the Vincentown and Wenonah-Mount Laurel aquifers, the Englishtown aquifer system, and the Hornerstown and Red Bank Sands was sampled for determination of gross alpha-particle activity; concentrations of radium radionuclides, major ions, and selected trace elements; and physical properties. Concentrations of radium-224, radium-226, and radium-228 were determined for water from 28 of the 39 wells, whereas gross alpha-particle activity was determined for all 39. The alpha spectroscopic technique was used to determine concentrations of radium-224, which ranged from less than 0.5 to 2.7 pCi/L with a median concentration of less than 0.5pCi/L, and of radium-226, which ranged from less than 0.5 to 3.2 pCi/L with a median concentration of less than 0.5 pCi/L. The beta-counting technique was used to determine concentrations of radium-228. The concentration of radium-228 ranged from less than 0.5 to 4.3 pCi/L with a median of less than 0.5. Radium-228, when quantifiable, had the greatest concentration of the three radium

Uranium and thorium occurrences in Precambrian rocks, Upper Peninsula of Michigan and northern Wisconsin, with thoughts on other possible settings

International Nuclear Information System (INIS)

Kalliokoski, J.

1976-01-01

The following areas are covered: Precambrian geology of northern Michigan; mode of occurrence of uranium and thorium in the Precambrian rocks of the Upper Peninsula of Michigan; selected stratigraphic relationships, Precambrian rocks of Michigan; mode of occurrence of uranium and thorium in Precambrian rocks of Wisconsin; and background data for geochemical exploration

A novel HPLC method for separation of uranium from thorium using BEHSA modified semi preparative support

International Nuclear Information System (INIS)

Raju, Ch.Siva Kesava; Subramanian, M.S.; Sivaraman, N.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2006-01-01

The determination of uranium and thorium is of great importance with respect to nuclear industry and environmental samples. High performance liquid chromatography (HPLC) has revolutionized as a powerful separation and analytical tool in the field of chemistry, biology, medicine, pharmacy, chemical technology, food science and many more. The major advantages of HPLC are its ability to provide rapid, high performance separations and extending the separations range from laboratory scale to preparative scale purification. HPLC became powerful technique for the separation of uranium and thorium. These methods were widely employed in applications such as separation of uranium from fission products and for the measurement of number of fissions as in the case of burn-up measurements on nuclear reactor fuels

800-MeV proton irradiation of thorium and depleted uranium targets

Energy Technology Data Exchange (ETDEWEB)

Russell, G.J.; Brun, T.O.; Pitcher, E.J. [Los Alamos National Laboratory, NM (United States)] [and others

1995-10-01

As part of the Los Alamos Fertile-to-Fissile-Conversion (FERFICON) program in the late 1980`s, thick targets of the fertile materials thorium and depleted uranium were bombarded by 800-MeV protons to produce the fissile materials {sup 233}U and {sup 239}Pu, respectively. The amount of {sup 233}U made was determined by measuring the {sup 233}Pa activity, and the yield of {sup 239}Pu was deduced by measuring the activity of {sup 239}Np. For the thorium target, 4 spallation products and 34 fission products were also measured. For the depleted uranium target, 3 spallation products and 16 fission products were also measured. The number of fissions in each target was deduced from fission product mass-yield curves. In actuality, axial distributions of the products were measured, and the distributions were then integrated over the target volume to obtain the total number of products for each reaction.

Determination of radium and uranium isotopes in natural waters by sorption on hydrous manganese dioxide followed by alpha-spectrometry

International Nuclear Information System (INIS)

Bojanowski, R.; Radecki, Z.; Burns, K.

2005-01-01

Water samples, spiked with 133 Ba and 232 U radiotracers, are scavenged for radium and uranium isotopes using hydrous manganese dioxide which is produced in-situ, by reacting manganese (+2) and permanganate ions at pH 8-9. The precipitate is solubilized with ascorbic and acetic acids and the resulting solution filtered through a glass fibre filter GF/F to remove particulate matter. The radium is co-precipitated with barium ions by the addition of a saturated Na 2 SO 4 solution where a small amount of BaSO 4 suspension is introduced to initiate crystallization. The micro precipitate containing the radium is collected on a 0.1 membrane filter and the filtrate saved for follow-up uranium analysis. The 226 Ra on the filter is determined by alpha-spectrometry and its recovery is assessed by measuring the 133 Ba on the same filter using gamma-spectrometry. The filtrate containing uranium is passed through a Dowex AG 1 x 4 ion-exchange resin in the SO 4 2- form which retains uranium while other ions are eluted by dilute (0.25M) sulphuric acid. Uranium is eluted from the column by distilled water, electrodeposited on a silver disc and the uranium isotopes and their recovery are determined by alpha-spectrometry. The method was tested on a variety of natural and spiked water samples with known concentrations of 226 Ra and 238 U and was found to yield accurate results within ±10% RSD of the target values. (author)

Where are uranium and thorium stored in the Archean basement

Energy Technology Data Exchange (ETDEWEB)

Schwinner, R

1949-01-01

The author advances a theory which makes it possible to predict where prospecting for new deposits of uranium and thorium should prove successful. According to this theory, such deposits occur chiefly where the equatorial and the meridional branches of the oldest primitive rock systems cross one another. An outline of the earth's Archean basement is included.

Thorium in nuclear fuel

International Nuclear Information System (INIS)

Stankevicius, Alejandro

2012-01-01

We revise the advantages and possible problems on the use of thorium as a nuclear fuel instead of uranium. The following aspects are considered: 1) In the world there are three times more thorium than uranium 2) In spite that thorium in his natural form it is not a fisil, under neutron irradiation, is possible to transform it to uranium 233, a fisil of a high quality. 3) His ceramic oxides properties are superior to uranium or plutonium oxides. 4) During the irradiation the U 233 due to n,2n reaction produce small quantities of U 232 and his decay daughters' bismuth 212 and thallium 208 witch are strong gamma source. In turn thorium 228 and uranium 232 became, in time anti-proliferate due to there radiation intensity. 5) As it is described in here and experiments done in several countries reactors PHWR can be adapted to the use of thorium as a fuel element 6) As a problem we should mentioned that the different steps in the process must be done under strong radiation shielding and using only automatized equipment s (author)

Analysis for the radionuclides of the natural uranium and thorium decay chains with special reference to uranium mine tailings

International Nuclear Information System (INIS)

Lowson, R.T.; Short, S.A.

1986-08-01

A detailed review is made of the experimental techniques that are available, or are in the process of development, for the determination of 238 U, 235 U, 234 U, 231 Pa, 232 Th, 230 Th, 228 Th, 228 Ra, 226 Ra, 223 Ra, 210 Po and 210 Pb. These products of the uranium and thorium decay chains are found in uranium mine tailings. Reference is also made to a procedure for the selective phase extraction of mineral phases from uranium mine tailings

Sorption behaviour of uranium and thorium on hydrous tin oxide from aqueous and mixed-solvent HNO3 media

International Nuclear Information System (INIS)

Misak, N.Z.; Salama, H.N.; El-Naggar, I.M.

1983-01-01

In aqueous nitric acid, uranyl and thorium ions seem to be sorbed on hydrous tin oxide mainly by a cation exchange mechanism. In 10 - 3 M aqueous solutions, the hydrous oxide prefers thorium to uranium at the relative low pH values, while the reverse is true at the higher pH values. The exchange of uranium is particle diffusion controlled while that of thorium is chemically controlled, and the isotherms point to the presence of different-energy sites in the hydrous oxide. Except for the solutions containing 80% of methanol, ethanol, or acetone, cation exchange is probably still the main mechanism of sorption of uranium. Anionic sorption of thorium seems to occur in all the mixed-solvent solutions and is perhaps the main mechanism in 80% ethanol. The equilibrium distribution coefficient K sub (d) increases almost in all cases with organic solvent content, probably due to dehydration of sorbed ions and to increasing superposition on anionic sorption. Unlike the aqueous medium, large U/Th separation factors are achieved in many of the mixed-solvent solutions and separation schemes are suggested. (Authors)

Determination of uranium and thorium contents using a 14 MeV neutron generator and a radiometric method

International Nuclear Information System (INIS)

Casagrande, J.A.

1981-04-01

A simple method was developed which can determine uranium and thorium in uranium ores, by 14MeV neutron activation and delayed neutron counting. The process can be used in field laboratories to select samples for processing. The method does not require a previous treatment of the samples and the analysis time is below 5 minutes. The detection limit of the method is about 2 ppm, when the yield of the 14MeV source has a value of 2 X 10 11 neutrons/second, and an optimized delayed neutron counter is used. A radiometric method is used determine separately the thorium content of the sample, and this result is combined with the activation one in order to obtain uranium content. The radiometric method in the counting of the 2,6 MeV gamma rays from 208 Tl using a NaI(Tl) detector. Delayed neutron counting is performed with BF 3 detectors inside a paraffin box. The problem of radioactive equilibrium does not affect thorium determination since the biggest activities of thorium daughters are much smaller than the times involved in the displacements of mineral which can give origin to the radioactive desequilibrium. (Author) [pt

Neutron activation analysis in geological samples containing rare earths, uranium and thorium

International Nuclear Information System (INIS)

Vasconcellos, M.B.A.; Figueiredo, A.M.G.; Berretta, J.R.; Soares, J.C.A.C.R.; Fratin, L.; Goncales, O.L.; Botelho, S.

1990-01-01

The neutron activation analysis method was used for determination of rare earths, uranium, thorium and other tracks in geological samples, under the geological standard JB-1 (Geological Survey of Japan) and S-8 and S-13 (IAEA). (L.C.J.A.)

Radium and thorium with barium in micronodules of cattle thyroids

International Nuclear Information System (INIS)

Van Middlesworth, L.

1980-01-01

Radium isotopes were found concentrated in thyroid glands of cattle. The incidence of measurable radium varied from 80% to less than 0.1% in thyroids from different abattoirs. The radium was concentrated in microscopic bodies containing predominantly barium and sulfur and lying within the storage of thyroglobulin, adjacent to follicular cells. Some thyroid cells may receive biologically significant doses of alpha radiation from these sources

Studies on supercritical fluid extraction of uranium and thorium from liquid and solid matrix

International Nuclear Information System (INIS)

Kumar, Pradeep; Pal, Ankita; Saxena, M.K.; Ramakumar, K.L.

2006-05-01

Supercritical fluid extraction (SFE) is being widely used in pharmaceutical and food industry. Because of its simplicity, ease of operation and more importantly the reduction in the analytical waste generation, this technique is being viewed as a potential application technique in nuclear industry also. CO 2 is employed as supercritical fluid (SCF) as it is easily recyclable, non-toxic, chemically inert, radiochemically stable and inexpensive. Radioanalytical chemistry section (Radiochemistry and Isotope group) has recently procured a supercritical fluid extraction/chromatography system. The present report describes the work carried out on the system. Detailed study on uranium and thorium extraction from highly acidic medium and tissue paper matrix has been carried out. Direct dissolution and extraction of uranium compounds employing SCF has been carried out. CO 2 was employed as supercritical fluid along with very small amount of Tri n-butyl phosphate (TBP) and Tri n-octyl phosphine oxide (TOPO) as co-solvents. The effect of various operating parameters like CO 2 flow rate, co-solvent percentage, temperature and pressure on extraction was investigated and parameters for maximum extraction were optimized. For comparison, the modes of extraction viz. static and dynamic and modes of complexation viz. in-situ and online were studied. Uranium extraction of ∼98% has been achieved from nitric acid medium employing TBP as co-solvent in 30 minutes extraction time, whereas with TOPO ∼99% uranium extraction could be achieved. Uranium from tissue paper matrix could be extracted upto the extent of 98% with TOPO as co-solvent whereas with TBP extraction of (66.83± 9.80)% was achievable. Direct dissolution of UO 2 , U 3 O 8 , U metal, U-Al alloy solids into SCF CO 2 was carried out employing TBP-HNO 3 complex and SFE of uranium was performed using TBP as co-solvent. UO 2 and U 3 O 8 solids could be dissolved within 20 minutes and extraction of ∼98% was achieved. For U

Port Radium start to finish life cycle: a case study on Canada's historic radium/uranium mine, initial operation and closure, concerns of the aboriginal Dene people, subsequent assessments, remediation - 59332

International Nuclear Information System (INIS)

Wiatzka, Gerd; Brown, Steve

2012-01-01

Document available in abstract form only. Full text of publication follows: This paper provides a life study cycle case study on the historic Port Radium mine. In addition to the history of operations, it discusses the unique and successful approach used to identify the key issues and concerns associated with the former radium, uranium and silver mining property and the program activities undertaken to define the remedial issues and options that ultimately lead to the development of a preferred remedial plan. The Port Radium Mine site, situated approximately 275 km north of Yellowknife on the east shore of Great Bear Lake, Northwest Territories, was operated almost continuously between 1932 and 1982, initially for recovery of radium and uranium and subsequently for recovery of silver. Tailings production equalled an estimated 900, 000 tons from uranium ore processing and 800, 000 tons from silver processing operations. While the site was decommissioned at mine closure, site investigations were undertaken to address concerns expressed by residents of the community of Deline about residual contamination at the site and exposure of Deline residents as traditional land users and to identify residual environmental and safety issues based on current closure standards. Assessment of past radiation exposures of worker based on past practices associated with ore handling and concentrate shipping were also addressed. The paper provides insights into the approach and activities undertaken over a seven (7) year period that ultimately concluded with the final decommissioning of the site in 2007 and post remedial actions being carried out under the long term care and maintenance program. (authors)

Separation of uranium(V I) from binary solution mixtures with thorium(IV), zirconium(IV) and cerium(III) by foaming

International Nuclear Information System (INIS)

Shakir, K.; Aziz, M.; Benyamin, K.

1992-01-01

Foam separation has been investigated for the removal of uranium(V I), thorium(IV), zirconium(IV) and cerium(III) from dilute aqueous solutions at pH values ranging from about I to about II. Sodium laurel sulphate (Na L S) and acetyl trimethyl ammonium bromide (CTAB), being a strong anionic and a strong cationic surfactants, were used as collectors. The results indicate that Na L S can efficiently remove thorium(IV), zirconium(IV) and cerium(III) but not uranium(V I). CTAB, on the other hand, can successfully float only uranium(V I) and zirconium(IV). These differences in flotation properties of the different cations could be used to establish methods for the separation of uranium(V I) from binary mixtures with thorium(IV), zirconium(IV) or cerium(III). The results are discussed in terms of the hydrolytic behaviour of the tested cations and properties of used collectors.2 fig., 1 tab

Study of lifetimes of fluorescence levels of tetravalent uranium in the incommensurate phase of thorium tetrabromide and tetrachloride

International Nuclear Information System (INIS)

Milicic, A.

1989-01-01

The lifetimes of radiative levels of tetravalent uranium in the incommensurate phase of thorium tetrahalides have been measured as a function of different parameters: site symmetry, temperature and concentration. The incommensurate phase of thorium tetrabromide and tetrachloride is characterized by a continuous distribution of site symmetries induced by a continuous and weak displacement of the halides around the thorium (uranium) ions. At low temperature, 4.2 K, the lifetime variation as a function of excited classes of symmetry is governed by the radiative process probability as well as the energy transfer between uranium ions in different sites. At higher temperature, a model based on a Boltzmann equilibrium between closed energy levels is able to reproduce the experimental lifetime variation as a function of the temperature, for a given class of symmetry. For the variation of lifetime as a function of uranium ion concentrations, at high dilution and in the case of U 4+ : ThBr 4 , there is a competition between the energy transfer and thermal population of excited states [fr

Processes for extracting radium from uranium mill tailings

International Nuclear Information System (INIS)

Nirdosh, I.; Baird, M.H.; Muthuswami, S.V.

1987-01-01

This patent describes a process for the extraction of radium from uranium mill tailings solids including the steps of contacting the tailings with a liquid leaching agent, leaching the tailings therewith and subsequently separating the leachate liquid and the leached solids. The improvement described here is wherein the leaching agent comprises: (a) a complexing agent in an amount of from 2 to 10 times the stoichiometric amount needed to complex the metal ions to be removed thereby from the tailings; and (b) a reducing agent reducing the hydrolysable ions of the metal ions to be removed to their lower oxidation states, the reduction agent being present in an amount from 2 to 10 times the stoichiometric amount needed for reducing the hydrolysable metals present in the tailings

Measurement of uranium and thorium in marine sediments

International Nuclear Information System (INIS)

Denden, Ibtihel

2009-01-01

Lakes, oceans and seas accumulate sediments. These sediments constitute a file of the last environmental conditions going up in some cases to thousands of years. In our study, we consulted this file by analyzing radioisotopes of Uranium and Thorium that are included in a carrot of marine sediment taken from the south of Mediterranean Sea. When we applied the technique developed by the maritime environment's laboratory of Monaco, we found spectra with bad resolutions. For this reason, the optimization of this protocol appeared necessary. (Author).

Sor/88-243, 21 April 1988, uranium and thorium mining regulations

International Nuclear Information System (INIS)

1988-05-01

These Regulations deal with radiological health and safety in uranium mining facilities and in effect, they formalise previous requirements imposed on such facilities through licence conditions. Licences are required for removing or excavating uranium or thorium; siting, constructing or operating a mine or a mill; and for decommissioning a mining facility. Applications for licences include technical conditions relevant to each type of activity concerned, the common condition being detailed descriptions of the activity, the radiation protection and environmental protection measures as well as the radiation monitoring programme [fr

Selective separation of uranium and thorium from lanthanides on sulphonic ion exchangers

Energy Technology Data Exchange (ETDEWEB)

Hubicki, Z; Hubicka, H; Jusiak, S [Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland)

1977-01-01

Separation of uranium and thorium from rare earth elements was studied on sulphonic ion exchangers of various types. Ammonium acetate, ammonium salicylate, aliphatic amine acetates, metaphosphoric acid and others were used as eluants. The most effective separation was attained by using metaphosphoric acid as eluant.

Sorption behaviour of uranium and thorium on hydrons tin oxide from aqueous and mixed-solvent H2SO4 media

International Nuclear Information System (INIS)

Misak, N.Z.; Salema, H.N.; El-Naggar, J.M.

1983-01-01

At pH values > about 2 in 10 -3 -10 -2 M aqueous sulphate solutions, uranium seems to be sorbed by hydrous tin oxide mainly as cations, while thorium is sorced as cations and as the neutral complex. At pH values of about 1.1-1.4, both uranium and thorium seem to be mainly sorbed as the neutral complexes. while at lower pH values, sorption of anionic commplexes comes into play. The sorption of uranium generally increased progressively on addition of increasing amounts of methanol, ethanol or acetone. The sorption of thorium decreases a little at 0.01 N H 2 SO 4 and increases a little at 0.5 N H 2 SO 4 on adding the organic solvents. At 0.1 N H 2 SO 4 , the addition of 20percent of the organic solvents brings the sorption of thorium to almost negligible values, which seems to offer an attractive means for U/Th separation. (author)

Criticality analysis for mixed thorium-uranium fuel in the Angra-2 PWR reactor using KENO-VI

Energy Technology Data Exchange (ETDEWEB)

Wichrowski, Caio C.; Gonçalves, Isadora C.; Oliveira, Claudio L.; Vellozo, Sergio O.; Baptista, Camila O., E-mail: wichrowski@ime.eb.br, E-mail: isadora.goncalves@ime.eb.br, E-mail: d7luiz@yahoo.com.br, E-mail: vellozo@ime.eb.br, E-mail: camila.oliv.baptista@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Seção de Engenharia Nuclear

2017-07-01

The increasing energy demand associated to the current sustainability challenges have given the thorium nuclear fuel cycle renewed interest in the scientific community. Studies have focused on energy production in different reactor designs through the fission of uranium 233, the product of thorium fertilization by neutrons. In order to make it possible for near future applications a strategy based on the adaptation of current nuclear reactors for the use of thorium fuels is being considered. In this work, bearing in mind these limitations, a code was used to evaluate the effect on criticality (k{sub inf}) of the mixing of thorium and uranium in different proportions in the fuel of a PWR, the German designed Angra-2 Brazilian reactor in order to scrutinise its behaviour and determine the feasibility of an adapted ThO{sub 2}-UO{sub 2} mixed fuel cycle using current PWR technology. The analysis is performed using the KENO-VI module in the SCALE 6.1 nuclear safety analysis simulation code and the information is taken from the Angra-2 FSAR (Final Security Analysis Report). (author)

Determination of uranium and thorium in complex matrices by two solvent extraction separation techniques and photon electron rejecting alpha liquid spectrometry

International Nuclear Information System (INIS)

Ayranov, M.; Wacker, L.; Kraehenbuehl, U.

2001-01-01

The separation of uranium and thorium from complex matrixes such as marine sediments using solvent extraction and determination by means of photon-electron rejecting liquid alpha spectrometry (PERALS trademark) has successfully been performed. Two extraction schemes, using TOPO and HDEHP, respectively, were compared for the separation of uranium and thorium from the matrix components. The results show recoveries between 73 and 92% for 234 U, 238 U, 232 Th, 230 Th and 238 Th with an accuracy of the methods ±12%. Minimum detectable activities for counting time up to 500 000 seconds for 0.5 g sample material were between 0.34-1.15 Bq/kg for uranium and 0.31-1.66 Bq/kg for thorium. (orig.)

Mapping of uranium and thorium in radioactive rocks using nuclear track solid detectors

International Nuclear Information System (INIS)

Bouch, C.M.

1982-01-01

α-Autoradiography and studies of induced fission in a research nuclear reactor (IEA-R1, IPEN, Sao Paulo) were done, employing Solid-State Nuclear Track detectors, in order to study the distribution of α-emitters, U and Th in rocks. Polished sections of rocks were prepared and photographed. Etching conditions were studied in order to adapt the detectors to the studies of microdistribution and macrodistribution of tracks. Polycarbonate foils (Bayer, Makrofol) were chosen as fission-fragments detectors and the technique of fission induced with reactor neutrons to obtain the distribution of U and Th were studied. Uranium and thorium standards evaporated on the surface of the detectors, as well as thorite and uraninite grains, were irradiated in order to measure the integrated flux of neutrons, the effective cross sections for fission with reactor neutrons for 232 Th(0,05b) and 238 U(0,30b) and to study the contribution of 238 U fission in thorium mapping. A technique for determination of uranium and thorium in minerals was studied and applied to Mica, for which were determined the contents of 4,2 ppb U e 58 ppb Th. (Author) [pt

Near field chemical speciation: the reaction of uranium and thorium with Hanford basalt and elevated pH

International Nuclear Information System (INIS)

Perry, D.L.

1984-01-01

The hydrolysis of radionuclides such as thorium and uranium and their subsequent chemisorption on Hanford basalt have been studied using a variety of techniques, including x-ray photoelectron and infrared spectroscopy. Data obtained to date indicate mixed complexes of uranium and thorium to be on the basalt surface, the complexes being radionuclide oxides, hydrated oxides (hydroxides), and carbonates. These findings are discussed with respect to their importance for input for models describing speciation and dissolution processes involving nuclear waste repository materials such as Hanford basalt. 5 figures, 2 tables

77 FR 3460 - Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

Science.gov (United States)

2012-01-24

... available funding, the approved claim amounts will be reimbursed on a prorated basis. All reimbursements are...., statutory increases in the reimbursement ceilings). Title X requires DOE to reimburse eligible uranium and... DEPARTMENT OF ENERGY Reimbursement for Costs of Remedial Action at Active Uranium and Thorium...

78 FR 21352 - Update on Reimbursement for Costs of Remedial Action at Active Uranium and Thorium Processing Sites

Science.gov (United States)

2013-04-10

... reimbursement ceilings). Title X requires DOE to reimburse eligible uranium and thorium licensees for certain... DEPARTMENT OF ENERGY Update on Reimbursement for Costs of Remedial Action at Active Uranium and... not currently available for reimbursement for cleanup work performed by licensees at eligible uranium...

Southern complex: geology, geochemistry, mineralogy, and mineral chemistry of selected uranium- and thorium-rich granites

International Nuclear Information System (INIS)

Hoffman, M.A.

1987-01-01

Four major rock groups are defined in the Southern Complex: the Bell Creek Granite (BCG), the Clotted Granitoids (CGR), the Albite Granite (AGR), and the Migmatite Complex. Metatexites of the Migmatite Complex are the oldest rocks and include paleosome of a metasedimentary and metavolcanic protolith represented by Banded Iron Formation, Banded Amphibolite, and Banded Gneisses, and interlayered or crosscutting leucogranites. The CGR span the range from metatexite to diatexite and represent in-situ partial melting of metapelitic layers in the protolith during intrusion of the BCG. The BCG cuts the migmatites, is locally cut by the CGR, and was derived by partial melting of a dominantly metasedimentary protolith at some depth below the presently exposed migmatites during a regional tectonothermal event. The Albite Granite is a 2km diameter, muscovite-fluorite-columbite-bearing intrusive stock that cuts all other major units. The thorium history of the BCG is a function of the history of monazite. The thorium history of the CGR is also dominated by monazite but the thorium content of this unit cannot be entirely accounted for by original restite monazite. The uranium history of the BCG and CGR was dominated by magmatic differentiation and post magmatic, metamorphic and supergene redistributions and is largely independent of the thorium history. The thorium and uranium history of the AGR was dominated by magmatic/deuteric processes unlike the BCG and CGR

A study of uranium-thorium mixed lattices; Etude de reseaux mixtes uranium - thorium

Energy Technology Data Exchange (ETDEWEB)

Bacher, P; Eckert, R; Mazancourt, R de [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1957-07-01

Some subcritical experiments have been carried out during the charging of the pile G1 by introducing thorium bars in a regular lattice into the pile. The spreading out of these experiments over a period of three months has permitted: a) work on a pile gradually increasing in size and b) measurements on comparable charges in so far that they have either the same number of bars of thorium, or the same concentration of thorium. From the measurements at constant charge and at constant concentration, it is possible by extrapolation to determine the critical charges and concentrations. The values obtained have showed that the material Laplacian of the lattice depends linearly on the thorium concentration and must cancel out for a concentration T = 8.8 {+-} 0.3 per cent by volume. These results have been found, to a very good approximation, by a simple calculation. (author) [French] Des experiences sous-critiques ont ete effectuees au cours du chargement de la pile G1 en introduisant des barres de thorium reparties suivant un reseau regulier dans la pile. L'etalement de ces experiences sur trois mois a permis d'operer sur une pile de plus en plus grosse et de faire un grand nombre de mesures sur des chargements comparables par le fait qu'ils avaient soit le meme nombre de barres de thorium, soit la meme concentration en thorium. A partir des mesures a chargement constant et a concentration constante, il a ete possible de determiner par extrapolation les chargements et concentrations critiques. Les valeurs obtenues ont montre que le laplacien matiere moyen du reseau dependait lineairement de la concentration en thorium, et devrait s'annuler pour une concentration T = 8,8 {+-} 0,3% en volume. Ces resultats ont ete retrouves avec une tres bonne approximation par un calcul elementaire. (auteur)

The radium distribution in some Swedish soils and its effects on radon emanation

International Nuclear Information System (INIS)

Edsfeldt, Cecilia

2001-08-01

The aim of this study has been to clarify how the radium distribution in soils affects the radon emanation. The distribution of radium, uranium and thorium has been determined using sequential extractions. In the study, soils from two different locations were investigated. In the first part the applicability of the sequential extraction method for determining Ra distribution in different soil types was investigated, using a simple sequential extraction method. Sampled soils were clay, sand and till from the vicinity of the Stockholm Esker. The main part of Rn emanating Ra was associated with Fe oxides in the soil. The methods applied provided information about the radon risk of the soil, but, in order to gain more information on the processes governing Ra distribution and radon emanation in soils, a more detailed sequential extraction procedure would be desirable. The second part consisted of a detailed study of the radionuclide distribution and the geochemistry in a podzolised glacial till from Kloten in northern Vaestmanland. A more detailed sequential extraction procedure was used, and the specific surface area of samples was measured. Samples were taken from E, B, and C horizons; radium and thorium were enriched in the B horizon, whereas uranium had its maximum concentration in the C horizon. Extractable radium primarily occurred in the exchangeable pool, possibly organically complexed, whereas extractable uranium and thorium were mainly Fe oxide bound. Oxide-bound Ra was important only in the B horizon. The radon emanation was not correlated with the amount of exchangeable Ra, but instead with the oxide bound Ra. However, the amount of oxide-bound Ra was too small to account for all the emanated Rn, thus, exchangeable Ra was interpreted as the main source of emanated Rn. This exchangeable Ra was more emanative in the B horizon than in the C horizon. The explanation is the larger surface area of the B horizon samples; the specific surface area appears to be the

Radioactive mineral spring precipitates, their analytical and statistical data and the uranium connection

Science.gov (United States)

Cadigan, R.A.; Felmlee, J.K.

1982-01-01

Major radioactive mineral springs are probably related to deep zones of active metamorphism in areas of orogenic tectonism. The most common precipitate is travertine, a chemically precipitated rock composed chiefly of calcium carbonate, but also containing other minerals. The mineral springs are surface manifestations of hydrothermal conduit systems which extend downward many kilometers to hot source rocks. Conduits are kept open by fluid pressure exerted by carbon dioxide-charged waters rising to the surface propelled by heat and gas (CO2 and steam) pressure. On reaching the surface, the dissolved carbon dioxide is released from solution, and calcium carbonate is precipitated. Springs also contain sulfur species (for example, H2S and HS-), and radon, helium and methane as entrained or dissolved gases. The HS- ion can react to form hydrogen sulfide gas, sulfate salts, and native sulfur. Chemical salts and native sulfur precipitate at the surface. The sulfur may partly oxidize to produce detectable sulfur dioxide gas. Radioactivity is due to the presence of radium-226, radon-222, radium-228, and radon-220, and other daughter products of uranium-238 and thorium-232. Uranium and thorium are not present in economically significant amounts in most radioactive spring precipitates. Most radium is coprecipitated at the surface with barite. Barite (barium sulfate) forms in the barium-containing spring water as a product of the oxidation of sulfur species to sulfate ions. The relatively insoluble barium sulfate precipitates and removes much of the radium from solution. Radium coprecipitates to a lesser extent with manganese-barium- and iron-oxy hydroxides. R-mode factor analysis of abundances of elements suggests that 65 percent of the variance of the different elements is affected by seven factors interpreted as follows: (1) Silica and silicate contamination and precipitation; (2) Carbonate travertine precipitation; (3) Radium coprecipitation; (4) Evaporite precipitation

Future perspective of thorium based nuclear fuels and thorium potential of Turkey

International Nuclear Information System (INIS)

Unak, T.; Yildirim, Y.

2001-01-01

Today's nuclear technology has principally been based on the use of fissile U-235 and Pu-239. he existence of thorium in the nature and its potential use in the nuclear technology were not unfortunately into account with a sufficient importance. The global distributions of thorium and uranium reserves indicate that in general some developed countries such as the USA, Canada, Australia, France have considerable uranium reserves, and contrarily only some developing countries such as Turkey, Brazil, India, Egypt have considerable thorium reserves. The studies carried out on the thorium during the last 50 years have clearly showed that the thorium based nuclear fuels have the potential easily use in most of reactor types actually operated with the classical uranium based nuclear fuels without any considerable modification. In the case of the use of thorium based nuclear fuels in future nuclear energy production systems, the serious problems such as the excess of Pu-239, the proliferation potential of nuclear weapons, and also the anxious of nuclear terrorism will probably be resolved, and sustainable nuclear energy production will be realized in the next new century. (authors)

Future perspective of thorium based nuclear fuels and thorium potential of Turkey

International Nuclear Information System (INIS)

Unak, T.; Yildirim, Y.

2000-01-01

Today's nuclear technology has principally been based on the use of fissile U-235 and Pu-239. The existence of thorium in the nature and its potential use in the nuclear technology were not unfortunately into account with a sufficient importance. The global distributions of thorium and uranium reserves indicate that in general some developed countries such as the USA, Canada, Australia, France have considerable uranium reserves, and contrarily only some developing countries such as Turkey, Brazil, India, Egypt have considerable thorium reserves. The studies carried out on the thorium during the last 50 years have clearly showed that the thorium based nuclear fuels have the potential easily use in most of reactor types actually operated with the classical uranium based nuclear fuels without any considerable modification. In the case of the use of thorium based nuclear fuels in future nuclear energy production systems, the serious problems such as the excess of Pu-239, the proliferation potential of nuclear weapons, and also the anxious of nuclear terrorism will probably be resolved, and sustainable nuclear energy production will be realized in the next new century. (authors)

Synthesis of uranium and thorium dioxides by Complex Sol-Gel Processes (CSGP). Synthesis of uranium oxides by Complex Sol-Gel Processes (CSGP)

International Nuclear Information System (INIS)

Deptula, A.; Brykala, M.; Lada, W.; Olczak, T.; Wawszczak, D.; Chmielewski, A.G.; Modolo, G.; Daniels, H.

2010-01-01

In the Institute of Nuclear Chemistry and Technology (INCT), a new method of synthesis of uranium and thorium dioxides by original variant of sol-gel method - Complex Sol-Gel Process (CSGP), has been elaborated. The main modification step is the formation of nitrate-ascorbate sols from components alkalized by aqueous ammonia. Those sols were gelled into: - irregularly agglomerates by evaporation of water; - medium sized microspheres (diameter <150) by IChTJ variant of sol-gel processes by water extraction from drops of emulsion sols in 2-ethylhexanol-1 by this solvent. Uranium dioxide was obtained by a reduction of gels with hydrogen at temperatures >700 deg. C, while thorium dioxide by a simple calcination in the air atmosphere. (authors)

Decree of the 23-rd of June 2015 related to installations implementing radioactive materials, radioactive wastes or solid residues of uranium, thorium or radium ore submitted to authorization according to entry 1716, to entry 1735 and to entry 2797 of the nomenclature of classified installations

International Nuclear Information System (INIS)

Blanc, P.

2015-01-01

This decree defines general prescriptions applicable to installations implementing radioactive materials, to installations used as depository, warehousing or storage of radioactive materials under the form of solid residues of radium, thorium or uranium ore, as well as some processing products, and to installations used for the management of radioactive wastes in an industrial or commercial facility. The decree contains general arrangements about authorisation request, financial guarantees and conditions of exploitation. It addresses measures and arrangements for the management of installations, for the management of radioactive materials and wastes, for the prevention of atmospheric pollution, for the protection of water resources and aquatic media. It also contains general rules for waste management, specific rules for radioactive waste management. It addresses measures and arrangements regarding the prevention of technological risks, the monitoring of installations and of their impact. An appendix addresses the various aspects of the quality management system: organisation and personnel, risk identification and assessment, process management and exploitation monitoring, management of modifications, planning of emergency situation, return on experience, performance monitoring. A last appendix addresses the monitoring of underground waters

Once-through uranium thorium fuel cycle in CANDU reactors

International Nuclear Information System (INIS)

Ozdemir, S.; Cubukcu, E.

2000-01-01

In this study, the performance of the once-through uranium-thorium fuel cycle in CANDU reactors is investigated. (Th-U)O 2 is used as fuel in all fuel rod clusters where Th and U are mixed homogeneously. CANDU reactors have the advantage of being capable of employing various fuel cycle options because of its good neutron economy, continuous on line refueling ability and axial fuel replacement possibility. For lattice cell calculations transport code WIMS is used. WIMS cross-section library is modified to achieve precise lattice cell calculations. For various enrichments and Th-U mixtures, criticality, heavy element composition changes, diffusion coefficients and cross-sections are calculate. Reactor core is modeled by using the diffusion code CITATION. We conclude that an overall saving of 22% in natural uranium demand can be achieved with the use of Th cycle. However, slightly enriched U cycle still consumes less natural Uranium and is a lot less complicated. (author)

Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France)

International Nuclear Information System (INIS)

Hubert, A.

2005-09-01

With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium ( 234 U et 238 U), thorium ( 230 Th et 232 Th), 226 Ra and 222 Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during α-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and α-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

The thorium fuel cycle in water-moderated reactor systems

International Nuclear Information System (INIS)

Critoph, E.

1977-01-01

Current interest in the thorium cycle, as an alternative to the uranium cycle, for water-moderated reactors is based on two attractive aspects of its use - the extension of uranium resources, and the related lower sensitivity of energy costs to uranium price. While most of the scientific basis required is already available, some engineering demonstrations are needed to provide better economic data for rational decisions. Thorium and uranium cycles are compared with regard to reactor characteristics and technology, fuel-cycle technology, economic parameters, fuel-cycle costs, and system characteristics. There appear to be no major feasibility problems associated with the use of thorium, although development is required in the areas of fuel testing and fuel management. The use of thorium cycles implies recycling the fuel, and the major uncertainties are in the associated costs. Experience in the design and operation of fuel reprocessing and active-fabrication facilities is required to estimate costs to the accuracy needed for adequately defining the range of conditions economically favourable to thorium cycles. In heavy-water reactors (HWRs) thorium cycles having uranium requirements at equilibrium ranging from zero to a quarter of those for the natural-uranium once-through cycle appear feasible. An ''inventory'' of uranium of between 1 and 2Mg/MW(e) is required for the transition to equilibrium. The cycles with the lowest uranium requirements compete with the others only at high uranium prices. Using thorium in light-water reactors, uranium requirements can be reduced by a factor of between two and three from the once-through uranium cycle. The light-water breeder reactor, promising zero uranium requirements at equilibrium, is being developed. Larger uranium inventories are required than for the HWRs. The lead time, from a decision to use thorium to significant impact on uranium utilization (compared to uranium cycle, recycling plutonium), is some two decades

Review of experience gained in fabricating nuclear grade uranium and thorium compounds and their analytical quality control at the Instituto de Energia Atomica, Sao Paulo, Brazil

International Nuclear Information System (INIS)

Abrao, A.; Franca, J.M. Jr.; Ikuta, A.; Pueschel, C.R.; Federgruen, L.; Lordello, A.R.; Tomida, E.K.; Moraes, S.; Brito, J. de; Gomes, R.P.; Araujo, J.A.; Floh, B.; Matsuda, H.T.

1977-01-01

This paper summarizes the main activities dealing with the fabrication of nuclear grade uranium and thorium compounds at the Instituto de Energia Atomica, Sao Paulo. Identification of problems and their resolutions, the experience gained in plant operation, the performance characteristics of an ion-exchange facility and a solvent extraction unit (a demonstration plant based on pulsed columns for purification of uranium and production of ammonium diuranate) are described. A moving-bed facility for UF 4 preparation and its operation is discussed. A pilot plant for uranium and thorium oxide microsphere preparation based on internal gelation for HTGR fuel type is also described. A solvent extraction pilot plant for thorium purification based on a compound extraction-scrubbing column and a mixer-settler battery and the involved technology for thorium purification are commented. The main products, namely ammonium diuranate, uranyl amonium tricarbonate, uranium trioxide, uranium tetrafluoride, thorium nitrate and thorium oxalate and their quality are commented. The development of necessary analytical procedures for the quality control of the mentioned nuclear grade products is summarized. A great majority of such procedures was particularly suitable for analyzing traces impurities. Designed for installation are the units for denitration of uranyl nitrate solutions and pilot plants for elemental fluorine and UF 6 . The installation of a laboratory-scale plant designed for reprocessing irradiated uranium and an experimental unit for the recovery of protactinium from irradiated thorium is in progress

An evaluation of once-through homogeneous thorium fuel cycle for light water reactors

International Nuclear Information System (INIS)

Joo, H. K.; Noh, J. M.; Yoo, J. W.

2002-01-01

The other ways enhancing the economic potential of thorium fuel has been assessed ; the utilization of lower enriched uranium in thorium-uranium fuel, duplex thorium fuel concept, thorium utilization in the mixed core with uranium fuel assembly and thorium blanket utilization in the uranium core. The fuel economics of the proposed ways of thorium fuel increased compared to the previous homogeneous thorium fuel cycle. Compared to uranium fuel cycle, however, they do not show any economic incentives. From the view of proliferation resistance potential, thorium fuel option has the advantage to reduce the inventory of plutonium production. Any of proposed thorium options are less economical than uranium fuel option, the thorium fuel option has the potential to be utilized in the future for the sake of the effective consumption of excessive plutonium and the preparation against the using up of uranium resource

Proceedings of the 9. international conference on health effects of incorporated radionuclides emphasis on radium, thorium, uranium and their daughter products - HEIR 2004

Energy Technology Data Exchange (ETDEWEB)

Oeh, U.; Roth, P.; Paretzke, H.G. (eds.) [GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany)

2005-07-01

The ninth international conference on 'Health Effects of Incorporated Radionuclides - Emphasis on Radium, Thorium, Uranium and their Daughter Products' HEIR 2004 was held at GSF-National Research Center for Environment and Health, Neuherberg, Germany, from November 29 until December 1, 2004. The growing popularity of this topic among the scientific community, especially the radiation protection community, was demonstrated by the largest number of participants in comparison to the earlier conferences. In all, there were 157 participants from 20 different countries of the world. In the conference 62 scientific and 12 poster presentations were included in 13 sessions. The scope of the conference covered studies related to the long-term follow-up of thorotrast subjects in Japan, Germany and Portugal, and also of the subjects exposed to Ra-224 for the treatment of bone tuberculosis and ankylosing spondylitis. The studies and discussions on these topics are important in view of the large number of liver cancers observed in the thorotrast patients and the number of bone cancers in the cases treated with Ra-224. A growth stunting was also observed for the subjects who received the Ra-224 injections early in their lives. Besides atom bomb survivors, the data from thorotrast patients could well help towards a better understanding of the health effects of irradiations. In addition to the scientific presentations on the above topics, there were a number of presentations on the incidence of lung cancer from radon exposure of miners and plutonium exposures causing lung cancer among the Mayak workers in the Russian Federation. Other stimulating presentations were on the tissue damaging mechanisms of alpha particles, having very high L.E.T., and also the related radiation weighting factor in comparison to beta and gamma radiations. There were also interesting presentations on the topics of uncertainties involved in the internal dose assessment from radiation exposure and

Proceedings of the 9. international conference on health effects of incorporated radionuclides emphasis on radium, thorium, uranium and their daughter products - HEIR 2004

International Nuclear Information System (INIS)

Oeh, U.; Roth, P.; Paretzke, H.G.

2005-01-01

The ninth international conference on 'Health Effects of Incorporated Radionuclides - Emphasis on Radium, Thorium, Uranium and their Daughter Products' HEIR 2004 was held at GSF-National Research Center for Environment and Health, Neuherberg, Germany, from November 29 until December 1, 2004. The growing popularity of this topic among the scientific community, especially the radiation protection community, was demonstrated by the largest number of participants in comparison to the earlier conferences. In all, there were 157 participants from 20 different countries of the world. In the conference 62 scientific and 12 poster presentations were included in 13 sessions. The scope of the conference covered studies related to the long-term follow-up of thorotrast subjects in Japan, Germany and Portugal, and also of the subjects exposed to Ra-224 for the treatment of bone tuberculosis and ankylosing spondylitis. The studies and discussions on these topics are important in view of the large number of liver cancers observed in the thorotrast patients and the number of bone cancers in the cases treated with Ra-224. A growth stunting was also observed for the subjects who received the Ra-224 injections early in their lives. Besides atom bomb survivors, the data from thorotrast patients could well help towards a better understanding of the health effects of irradiations. In addition to the scientific presentations on the above topics, there were a number of presentations on the incidence of lung cancer from radon exposure of miners and plutonium exposures causing lung cancer among the Mayak workers in the Russian Federation. Other stimulating presentations were on the tissue damaging mechanisms of alpha particles, having very high L.E.T., and also the related radiation weighting factor in comparison to beta and gamma radiations. There were also interesting presentations on the topics of uncertainties involved in the internal dose assessment from radiation exposure and the

Proceedings of the 9. international conference on health effects of incorporated radionuclides emphasis on radium, thorium, uranium and their daughter products - HEIR 2004

Energy Technology Data Exchange (ETDEWEB)

Oeh, U; Roth, P; Paretzke, H G [GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany)

2005-07-01

The ninth international conference on 'Health Effects of Incorporated Radionuclides - Emphasis on Radium, Thorium, Uranium and their Daughter Products' HEIR 2004 was held at GSF-National Research Center for Environment and Health, Neuherberg, Germany, from November 29 until December 1, 2004. The growing popularity of this topic among the scientific community, especially the radiation protection community, was demonstrated by the largest number of participants in comparison to the earlier conferences. In all, there were 157 participants from 20 different countries of the world. In the conference 62 scientific and 12 poster presentations were included in 13 sessions. The scope of the conference covered studies related to the long-term follow-up of thorotrast subjects in Japan, Germany and Portugal, and also of the subjects exposed to Ra-224 for the treatment of bone tuberculosis and ankylosing spondylitis. The studies and discussions on these topics are important in view of the large number of liver cancers observed in the thorotrast patients and the number of bone cancers in the cases treated with Ra-224. A growth stunting was also observed for the subjects who received the Ra-224 injections early in their lives. Besides atom bomb survivors, the data from thorotrast patients could well help towards a better understanding of the health effects of irradiations. In addition to the scientific presentations on the above topics, there were a number of presentations on the incidence of lung cancer from radon exposure of miners and plutonium exposures causing lung cancer among the Mayak workers in the Russian Federation. Other stimulating presentations were on the tissue damaging mechanisms of alpha particles, having very high L.E.T., and also the related radiation weighting factor in comparison to beta and gamma radiations. There were also interesting presentations on the topics of uncertainties involved in the internal dose assessment from radiation exposure and the

Biomedical and environmental aspects of the thorium fuel cycle: a selected, annotated bibliography

International Nuclear Information System (INIS)

Faust, R.A.; Fore, C.S.; Cone, M.V.; Meyer, H.R.; Till, J.E.

1979-07-01

This bibliography was compiled to assist in the evaluation of the health and environmental consequences of high specific activity thorium and related nuclides which could be released to the environment by activities related to the Thorium Fuel Cycle. The general scope covers studies regarding potential releases, environmental transport, metabolism, dosimetry, dose assessment, and overall risk assessment for radionuclides specific to the NASAP project. This publication of 740 abstracted references highlights the biological and medical aspects of thorium 228 and thorium 232 in man and animals. Similar studies on related nuclides such as radium 224, radium 226, radium 228, and thorium 230 are also emphasized. Additional categories relevant to these radionuclides are included as follows: chemical analysis; ecological aspects; energy; geological aspects; instrumentation; legal and political aspects; monitoring, measurement and analysis; physical aspects; production; radiation safety and control; and waste disposal and management. Environmental assessment and sources categories were used for entries which contain a multiple use of categories. Leading authors appear alphabetically within each category. Indexes are provided for : author(s), geographic location, keywords, title, and publication description. The bibliography contains literature dating from December 1925 to February 1978

Biomedical and environmental aspects of the thorium fuel cycle: a selected, annotated bibliography

Energy Technology Data Exchange (ETDEWEB)

Faust, R.A.; Fore, C.S.; Cone, M.V.; Meyer, H.R.; Till, J.E.

1979-07-01

This bibliography was compiled to assist in the evaluation of the health and environmental consequences of high specific activity thorium and related nuclides which could be released to the environment by activities related to the Thorium Fuel Cycle. The general scope covers studies regarding potential releases, environmental transport, metabolism, dosimetry, dose assessment, and overall risk assessment for radionuclides specific to the NASAP project. This publication of 740 abstracted references highlights the biological and medical aspects of thorium 228 and thorium 232 in man and animals. Similar studies on related nuclides such as radium 224, radium 226, radium 228, and thorium 230 are also emphasized. Additional categories relevant to these radionuclides are included as follows: chemical analysis; ecological aspects; energy; geological aspects; instrumentation; legal and political aspects; monitoring, measurement and analysis; physical aspects; production; radiation safety and control; and waste disposal and management. Environmental assessment and sources categories were used for entries which contain a multiple use of categories. Leading authors appear alphabetically within each category. Indexes are provided for : author(s), geographic location, keywords, title, and publication description. The bibliography contains literature dating from December 1925 to February 1978.

Extrapolation studies on desorption of thorium and uranium at different solution compositions on contaminated soil sediments (Malaysia)

International Nuclear Information System (INIS)

Syed Hakimi Sakuma

2000-01-01

By means of batch desorption experiments, the thorium and uranium desorption properties of contaminated soil sediments are investigated as a function of the effect of cations present in the groundwater. A phenomenological correlation between the desorption coefficient and the concentration of Ca and Mg in the water is determined. Kd Thorium -0.15849 ± 0.03237 log (Ca + Mg) + 5.06715 ± 0.09106; Kd Uranium = -0.11984 ± 0.03237 log (Ca + Mg) + 2.99909 ± 0.09105. By these models the sorption/desorption behaviour of soils can be predicted phenomenologically as function of the groundwater composition. (author)

Uranium and radium activities in samples of aquifers of the main cities of the Estado de Chihuahua; Actividades de uranio y radio en muestras de agua subterranea de las principales ciudades del Estado de Chihuahua

Energy Technology Data Exchange (ETDEWEB)

Villalba, L.; Colmenero S, L.; Montero C, M.E. [CIMAV, Av. Miguel de Cervantes Saavedra 120, 31109 Chihuahua (Mexico)]. e-mail: lourdes.villalba@cimav.edu.mx

2003-07-01

The natural uranium is in four valence states +3, +4, +5 and +6 being the hexavalent state the more soluble, which plays an important role in the transport of the uranium in the environment. The high concentrations of uranium in water not only in near waters to uranium mines, but also are in some mineral waters or in waters that are extracted of deep wells as it happens in the State of Chihuahua, where the underground waters are the fundamental source of consumption. The radium is a disintegration product of the uranium, the radio content in water is considered the second source of natural radioactivity. The distribution of radium in water is in function of the uranium content present in the aquifer. It was determined the uranium and radium content in samples of underground water of the main cities of the State of Chihuahua according to their number of inhabitants. The extraction methods for uranium and sulfates precipitation of Ba-Ra by means of the addition of barium carriers for the radium were used. The measures of the activities of uranium and radium were carried out by means of a portable liquid scintillation detector trade mark Thiathler-OY HIDEX. The obtained results have demonstrated that the content of uranium and radium in dissolution are in most of the sampling wells above the permissible maximum levels that manage the Mexican regulations. The high contents of uranium and radio can be attributed since to the influence of the geologic substrate characteristic of the zone in the State of Chihuahua they exist but of 50 uranium deposits. (Author)

Supercritical fluid extraction of uranium and thorium employing dialkyl amides

International Nuclear Information System (INIS)

Rao, Ankita; Kumar, Pradeep

2014-01-01

Extraction and purification of actinides from different matrices is of utmost importance to the nuclear industry. In recent decades, supercritical fluid extraction (SFE) has emerged as a promising alternative to solvent extraction owing to its inherent potential of minimization of liquid waste generation. N,N-dialkyl aliphatic amides have been proposed to be an alternative to TBP in the reprocessing of spent nuclear fuel due to several attractive features like innocuous nature of degradation products (mainly carboxylic acids/ amines), possibility of complete incineration of the used extractant leading to reduction in volume of secondary waste. Also, physico-chemical properties of this class of extractants can be tuned by the judicious choice of alkyl groups. In the present work, N,N-dialkyl aliphatic amides with varying alkyl groups viz. N,N-dibutyl-2-ethylhexanamide (DBEHA), N,N-dibutyl-3,3-dimethylbutanamide (DBDMBA), N,N-dihexyloctanamide (DHOA), N,N-disecbutylpentamide (DBPA), N,N-dibutyloctanamide (DBOA), have been evaluated for supercritical fluid extraction (SFE) of uranium and thorium from nitric acid medium as well as tissue paper matrix. Amides were obtained from Department of Chemistry, Delhi University and were used as such. This fact could be exploited for separation of thorium and uranium

Prospective thorium fuels for future nuclear energy generation

International Nuclear Information System (INIS)

Lainetti, Paulo E.O.

2017-01-01

In the beginning of the Nuclear Era, many countries were interested on thorium, particularly during the 1950 1970 periods. Nevertheless, since its discovery almost two centuries ago, the use of thorium has been restricted to gas mantles employed in gas lighting. The future world energy needs will increase and, even if we assumed a conservative contribution of nuclear generation, it will be occur a significant increasing in the uranium prices, taking into account that uranium, as used in the present thermal reactors, is a finite resource. Nowadays approximately the worldwide yearly requirement of uranium for about 435 nuclear reactors in operation is 65,000 metric t. Therefore, alternative solutions for future must be developed. Thorium is nearly three times more abundant than uranium in The Earth's crust. Despite thorium is not a fissile material, 232 Th can be converted to 233 U (fissile) more efficiently than 238 U to 239 Pu. Besides this, thorium is an environment alternative energy source and also inherently resistant to proliferation.. Many countries had initiated research on thorium in the past, Nevertheless, the interest evanesced due new uranium resources discoveries and availability of enriched uranium at low prices from obsolete weapons. Some papers evaluate the thorium resources in Brazil over 1.200.000 metric t. Then, the thorium alternative must be seriously considered in Brazil for strategic reasons. A brief history of thorium and its utilization are presented, besides a very short discussion about prospective thorium nuclear fuels for the next generation of nuclear reactors. (author)

Prospective thorium fuels for future nuclear energy generation

Energy Technology Data Exchange (ETDEWEB)

Lainetti, Paulo E.O., E-mail: lainetti@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2017-07-01

In the beginning of the Nuclear Era, many countries were interested on thorium, particularly during the 1950 1970 periods. Nevertheless, since its discovery almost two centuries ago, the use of thorium has been restricted to gas mantles employed in gas lighting. The future world energy needs will increase and, even if we assumed a conservative contribution of nuclear generation, it will be occur a significant increasing in the uranium prices, taking into account that uranium, as used in the present thermal reactors, is a finite resource. Nowadays approximately the worldwide yearly requirement of uranium for about 435 nuclear reactors in operation is 65,000 metric t. Therefore, alternative solutions for future must be developed. Thorium is nearly three times more abundant than uranium in The Earth's crust. Despite thorium is not a fissile material, {sup 232}Th can be converted to {sup 233}U (fissile) more efficiently than {sup 238}U to {sup 239}Pu. Besides this, thorium is an environment alternative energy source and also inherently resistant to proliferation.. Many countries had initiated research on thorium in the past, Nevertheless, the interest evanesced due new uranium resources discoveries and availability of enriched uranium at low prices from obsolete weapons. Some papers evaluate the thorium resources in Brazil over 1.200.000 metric t. Then, the thorium alternative must be seriously considered in Brazil for strategic reasons. A brief history of thorium and its utilization are presented, besides a very short discussion about prospective thorium nuclear fuels for the next generation of nuclear reactors. (author)

Investigation of Alaska's uranium potential. Part 1. Reconnaissance program, West-Central Alaska and Copper River basin. Part 2. Uranium and thorium in granitic and alkaline rocks in Western Alaska

International Nuclear Information System (INIS)

Eakins, G.R.; Jones, B.K.; Forbes, R.B.

1977-02-01

A 6-week reconnaissance program was conducted in west-central Alaska and in the Copper River basin--Chitina River valley area to aid in determining the uranium potential of the state. Division personnel also submitted samples from the Healy, Eagle, and Charley River quadrangles. Collected were 916 stream-sediment samples and 427 bedrock samples for uranium, thorium, and potassium oxide determinations, and 565 water samples for uranium analyses. A statistical analysis of the determinations was made using a computer at the University of Alaska. Thresholds, anomalies, and U:Th ratios were calculated for eight separate regions. Anomalous values of the U, Th, and K 2 O, and radiometric measurements are discussed. A combination of all uranium exploration techniques is needed to locate potential uranium deposits in Alaska. Correlations between aerial and ground radiometric surveys and geochemical surveys were often lacking, indicating that each method may or may not be effective, depending on local conditions. One hundred and eight rock samples were selected from traverses across five plutons in western Alaska and analyzed for uranium, thorium, and potassium. The highest uranium concentrations detected were 86 and 92 ppM from a mineralized dike intrusion zone in the Selawik Lake Complex. Analysis of individual plutons yields strong correlations between mineralogy and radioactivity. The mineralogical variable that correlates with uranium or thorium varies from one pluton to the next. Based on these correlations, mineralogical guidelines are offered for the selection of uranium enriched variants in four of the five plutons

Study of rare earth elements, uranium and thorium migration in rocks from Espinharas uranium deposit, Paraiba - Brazil

International Nuclear Information System (INIS)

Conceicao, Cirilo C.S.

2009-01-01

The determination of rare earth elements as natural analogue in patterns geologic has grown as a tool for predicting the long-term safety of nuclear disposal in geological formation. Migration of natural radionuclides is one of the most serious problems in the waste deposit from nuclear fuel cycle. Rare earth elements show the same kinetic behavior in rocks as natural radionuclides. This similar property of the analogues allows perform studies and models on the subject of radionuclides migration. The aim of this study was to determine the distribution of rare earth elements in rocks located at Espinharas - Paraiba - Brazil, uranium deposit. In this work are presented the results from the study above the distribution of rare earth elements in function of the degree of mineralized rocks, composition and the conditions of radioactive equilibrium of the uranium and thorium in some fractures on the rocks from radioactive occurrence of Espinharas-Brazil. The results show that there is a correlation of heavy rare earth elements, uranium and Thorium concentrations to oxidation factor of the rocks. However this correlation was not observed for light rare earth elements. It means that heavy rare earth elements follow the natural radionuclides in oxidation process of rocks. The samples were analyzed by ICP-MS, alpha and gamma spectrometry, X-ray diffraction and fluorimetry. (author)

Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings (40 CFR Part 192)

Science.gov (United States)

This regulation sets standards for the protection of public health, safety, and the environment from radiological and non-radiological hazards from uranium and thorium ore processing and disposal of associated wastes.

Review of experience gained in fabricating nuclear grade uranium and thorium compounds and their analytical quality control at the Instituto de Energia Atomica, Sao Paulo, Brazil

International Nuclear Information System (INIS)

Abrao, A.; Franca Junior, J.M.; Ikuta, A.

1977-01-01

The main activities developed at 'Instituto de Energia Atomica' Sao Paulo, Brazil, on the recovery of uranium from ores, the purification of uranium and thorium raw concentrates and their transformation in nuclear grade compounds, are reviewed. The design and assemble of pilot facilities for ammonium diuranate (ADV) uranium tetrafluoride, uranium trioxide, uranium oxide microspheres, uranyl nitrate denitration, uranim hexafluoride and thorium compounds are discussed. The establishment of analytical procedures are emphasized [pt

The thorium fuel cycle in water-moderated reactor systems

International Nuclear Information System (INIS)

Critoph, E.

1977-05-01

Thorium and uranium cycles are compared with regard to reactor characteristics and technology, fuel-cycle technology, economic parameters, fuel-cycle costs, and system characteristics. In heavy-water reactors (HWRs) thorium cycles having uranium requirements at equilibrium ranging from zero to a quarter of those for the natural-uranium once-through cycle appear feasible. An 'inventory' of uranium of between 1 and 2 Mg/MW(e) is required for the transition to equilibrium. The cycles with the lowest uranium requirements compete with the others only at high uranium prices. Using thorium in light-water reactors, uranium requirements can be reduced by a factor of between two and three from the once-through uranium cycle. The light-water breeder reactor, promising zero uranium requirements at equilibrium, is being developed. Larger uranium inventories are required than for the HWRs. The lead time, from a decision to use thorium to significant impact on uranium utilization (compared to uranium cycle, recycling plutonium) is some two decades

Transmutation of uranium and thorium in the particle field of the Quinta sub-critical assembly

Science.gov (United States)

Hashemi-Nezhad, S. R.; Asquith, N. L.; Voronko, V. A.; Sotnikov, V. V.; Zhadan, Alina; Zhuk, I. V.; Potapenko, A.; Husak, Krystsina; Chilap, V.; Adam, J.; Baldin, A.; Berlev, A.; Furman, W.; Kadykov, M.; Khushvaktov, J.; Kudashkin, I.; Mar'in, I.; Paraipan, M.; Pronskih, V.; Solnyshkin, A.; Tyutyunnikov, S.

2018-03-01

The fission rates of natural uranium and thorium were measured in the particle field of Quinta, a 512 kg natural uranium target-blanket sub-critical assembly. The Quinta assembly was irradiated with deuterons of energy 4 GeV from the Nuclotron accelerator of the Joint Institute for Nuclear Research (JINR), Dubna, Russia. Fission rates of uranium and thorium were measured using Gamma spectroscopy and fission track techniques. The production rate of 239Np was also measured. The obtained experimental results were compared with Monte Carlo predictions using the MCNPX 2.7 code employing the physics and fission-evaporation models of INCL4-ABLA, CEM03.03 and LAQGSM03.03. Some of the neutronic characteristics of the Quinta are compared with the "Energy plus Transmutation (EpT)" subcritical assembly, which is composed of a lead target and natU blanket. This comparison clearly demonstrates the importance of target material, neutron moderator and reflector types on the performance of a spallation neutron driven subcritical system. As the dimensions of the Quinta are very close to those of an optimal multi-rod-uranium target, the experimental and Monte Carlo calculation results presented in this paper provide insights on the particle field within a uranium target as well as in Accelerator Driven Systems in general.

Determination of uranium and thorium isotopes in soil samples by coprecipitation

International Nuclear Information System (INIS)

Ngo Quang Huy; Trinh Thi Bich; Nguyen Van Suc

2012-01-01

The paper presents a procedure to prepare soil samples for U and Th isotope measurement by alpha-spectrometry after coprecipitation with LaF 3 . In this procedure the reduction of U(VI) to U(IV) was performed by Zn metal in 4M HCl solution. The recoveries of chemical separation equal to ε U-chemistry = 78±4% for uranium and ε Th-chemistry = 82±4% for thorium. Canberra alpha-spectrometer was used with PIPS detectors of A-1200-37-AM Model of 1200 mm 2 active area. The counting efficiency of the measuring system equals to ε counting = 18% and the total efficiencies were ε U = ε counting - ε U-chemistry = 14.0 ± 0.7% for uranium and ε Th = ε counting - ε Th-chemistry = 14.7 ± 0.7% for thorium. The recoveries of chemical separation were rather high (about 80%), that leads to the use of a small weight of soil sample (about 0.5 g). The efficiencies were also stable, that allows analyzing the soil sample without using radiotracers. They are advantages of the sample preparation procedure of this work. (author)

Chemical analysis used in nuclear fuels reprocessing of uranium and thorium

International Nuclear Information System (INIS)

Schvartzman, M.M.A.M.

1986-01-01

An overall review of the analytical chemistry in nuclear fuel reprocessing is done. In Purex and Thorex process flowsheets, the analyses required to the control of the process, balance and accountability of fissile and fertile materials, and final product specification are pointed out. Some analytical methods applied to the determination of uranium, plutonium, thorium, nitric acid, tributylphosphate and fission products are described. Specific features of the analytical laboratories are presented. The radioactivity level of the samples requires facilities as shielded cells and glove boxes, and handling by remote control. Finally it is reported an application of one analytical method to evaluate thorium content in organic and aqueous solutions, in cold tests of Thorex process. These tests were performed at CDTN/NUCLEBRAS. (author) [pt

Solvent extraction of uranium(VI) and thorium(IV) from nitrate media by carboxylic acid amides

International Nuclear Information System (INIS)

Preston, J.S.; Preez, A.C. du

1995-01-01

A series of nineteen N-alkyl carboxylic acid amides (R.CO.NHR') has been prepared, in which the alkyl groups R and R' have been varied in order to introduce different degrees of steric complexity into the compounds. A smaller number of N,N-dialkyl amides (R.CO.NR 2 ') and non-substituted amides (R.CO.NH 2 ) has also been prepared for comparison purposes. These amides were characterized by measurement of their boiling points, melting points, refractive indices and densities. The solvent extraction of uranium(VI) and thorium(IV) from sodium nitrate media by solutions of the amides in toluene was studied. Increasing steric bulk of the alkyl groups R and R' was found to cause a marked decrease in the extraction of thorium, with a much smaller effect on the extraction of uranium, thus considerably enhancing the separation between these metals. Vapour pressure osmometry studies indicate that the N-alkyl amides are self-associated in toluene solution, with aggregation numbers up to about 2.5 for 0.6 M solutions at 35 degree C. In contrast, the N,N-dialkyl amides behave as monomers under these conditions. The distribution ratios for the extraction of uranium and thorium show second- and third-order dependences, respectively, on the extractant concentration for both the N-alkyl and N,N-dialkyl amides. 15 refs., 8 figs., 8 tabs

Feasibility study of the dissolution rates of uranium ore dust, uranium concentrates and uranium compounds in simulated lung fluid

International Nuclear Information System (INIS)

Robertson, R.

1986-01-01

A flow-through apparatus has been devised to study the dissolution in simulated lung fluid of aerosol materials associated with the Canadian uranium industry. The apparatus has been experimentally applied over 16 day extraction periods to approximately 2g samples of < 38um and 53-75um particle-size fractions of both Elliot Lake and Mid-Western uranium ores. The extraction of uranium-238 was in the range 24-60% for these samples. The corresponding range for radium-226 was 8-26%. Thorium-230, lead-210, polonium-210, and thorium-232 were not significantly extracted. It was incidentally found that the elemental composition of the ores studied varies significantly with particle size, the radionuclide-containing minerals and several extractable stable elements being concentrated in the smaller size fraction. Samples of the refined compounds uranium dioxide and uranium trioxide were submitted to similar 16 day extraction experiments. Approximately 0.5% of the uranium was extracted from a 0.258g sample of unsintered (fluid bed) uranium dioxide of particle size < 38um. The corresponding figure for a 0.292g sample of uranium trioxide was 97%. Two aerosol samples on filters were also studied. Of the 88ug uranium initially measured on stage 2 of a cascade impactor sample collected from the yellow cake packing area of an Elliot Lake mill, essentially 100% was extracted over a 16 day period. The corresponding figure for an open face filter sample collected in a fuel fabrication plant and initially measured at 288ug uranium was approximately 3%. Recommendations are made with regard to further work of a research nature which would be useful in this area. Recommendations are also made on sampling methods, analytical methods and extraction conditions for various aerosols of interest which are to be studied in a work of broader scope designed to yield meaningful data in connection with lung dosimetry calculations

Impact of uranium-233/thorium cycle on advanced accountability concepts and fabrication facilities. Addendum 2 to application of advanced accountability concepts in mixed oxide fabrication

International Nuclear Information System (INIS)

Bastin, J.J.; Jump, M.J.; Lange, R.A.; Crandall, C.C.

1977-11-01

The Phase I study of the application of advanced accountability methods (DYMAC) in a uranium/plutonium mixed oxide facility was extended to cover the possible fabrication of uranium-233/thorium fuels. Revisions to Phase II of the DYMAC plan which would be necessitated by such a process are specified. These revisions include shielding requirements, measurement systems, licensing conditions, and safeguards considerations. The impact of the uranium/thorium cycle on a large-scale fuel fabrication facility was also reviewed; it was concluded that the essentially higher radioactivity of uranium/thorium feeds would lead to increased difficulties which tend to preclude early commercial application of the process. An amended schedule for Phase II is included

Model for the behaviour of thorium and uranium fuels at pelletization

International Nuclear Information System (INIS)

Ferreira Neto, Ricardo Alberto

2000-11-01

In this work, a model for the behaviour of thorium-uranium-mixed oxide microspheres in the pelletizing process is presented. This model was developed in a program whose objective was to demonstrate the viability of producing fissile material through the utilization of thorium in pressurized water reactors. This is important because it allows the saving of the strategic uranium reserves, and makes it possible the nuclear utilization of the large brazilian thorium reserves. The objective was to develop a model for optimizing physical properties of the microspheres, such as density, fracture strength and specific surface, so as to produce fuel pellets with microstructure, density, open porosity and impurity content, in accordance with the fuel specification. And, therefore, to adjust the sol-gel processing parameters in order to obtain these properties, and produce pellets with an optimized microstructure, adequate to a stable behaviour under irradiation. The model made it clear that to achieve this objective, it is necessary to produce microspheres with density and specific surface as small as possible. By changing the sol-gel processing parameters, microspheres with the desired properties were produced, and the model was experimentally verified by manufacturing fuel pellets with optimized microstructures, density, open porosity and impurity content, meeting the specifications for this new nuclear fuel for pressurized water reactors. Furthermore it was possible to obtain mathematical expressions that enables to calculate from the microspheres properties and the utilized compaction pressure, the sinter density that will be obtained in the sintered pellet and the necessary compaction pressure to reach the sintered density specified for the fuel. (author)

Radium-bearing waters in the Upper Silesian Coal Basin

International Nuclear Information System (INIS)

Tomza, I.; Lebecka, J.; Pluta, I.

1986-01-01

Natural waters with a high radium content occuring in underground workings of coal mines in Upper Silesia are described. Above 1500 water samples from carbonifereous aquifers were taken and the concentration of 226 Ra was measured. In about 100 samples also uranium was determined. The 226 Ra concentration varied in a wide range from 0.01 kBq/m 3 to 270 kBq/m 3 , while the uranium content was usually much lower than one could expect from the equilibrium between radium and uranium. It was observed that the 226 Ra concentration increases with mineralization of water, however the correlation was rather poor. Two types of radium-bearing waters were distinguished. Waters type A - containing Ba 2+ ions and waters type B - containing SO 4 2- ions. Waters type A are always reach in radium and usually have higher concentration of 226 Ra than waters type B. The described waters have one of the highest radium concentration which have been found so far in the natural environment. (author)

Thorium and its future importance for nuclear energy generation

International Nuclear Information System (INIS)

Lainetti, Paulo E.O.

2015-01-01

Thorium was discovered in 1828 by the Swedish chemist Jons J. Berzelius. Despite some advantages over uranium for use in nuclear reactors, its main use, in the almost two centuries since its discovery, the use of thorium was restricted to use for gas mantles, especially in the early twentieth century. In the beginning of the Nuclear Era, many countries had interested on thorium, particularly during the 1950-1970 period. There are about 435 nuclear reactors in the world nowadays. They need more than 65.000 tons of uranium yearly. The future world energy needs will increase and, even if we assumed a conservative contribution of nuclear generation, it will be occur a significant increasing in the uranium prices, taking into account that uranium, as used in the present thermal reactors, is a finite resource. Thorium is nearly three times more abundant than uranium in the Earth's crust. Despite thorium is not a fissile material, 232 Th can be converted to 233 U (fissile) more efficiently than 238 U to 239 Pu. Besides this, since it is possible to convert thorium waste into nonradioactive elements, thorium is an environment-friendly alternative energy source. Thorium fuel cycle is also inherently resistant to proliferation. Some papers evaluate the thorium resources in Brazil over 1.200.000 metric t. Then, the thorium alternative must be seriously considered in Brazil for strategic reasons. In this paper a brief history of thorium is presented, besides a review of the world thorium utilization and a discussion about advantages and restrictions of thorium use. (author)

The environmental behaviour of radium. V.1

International Nuclear Information System (INIS)

1990-01-01

The objective of this publication is to provide an up to date review of the environmental behaviour of radium, including methods for analysis, assessment and control. The need for a reference text on the subject was identified at an early stage of the International Atomic Energy Agency's Co-ordinated Research Programme (CRP) on radium behaviour in relation to uranium mining and milling wastes, which began in 1976. There were two CRPs: (1) The Source, Distribution, Movement and Deposition of Radium in Inland Waterways and Aquifers (1976-1980; final report: IAEA-TECDOC-301, published in 1984). (2) The Environmental Migration of Radium and Other Contaminants Present in Liquid and Solid Wastes from the Mining and Milling of Uranium (1981-1985; final report: IAEA-TECDOC-370, published in 1986). This publication deals with the sources, properties, environmental behaviour and the methods of analysis, control and assessment of 226 Ra. It is an outgrowth of Agency programmes directed towards the environmental problems involved in uranium mining and milling. The emphasis in several of the sections reflects these origins. For example, many of the contributions in Volume 2 of this report on technologically enhanced sources of radium (Part 1), methods of control and abatement (Part 2) and the impact on man (Part 3) are concerned with uranium mining and milling. In Volume 1, coverage of the natural distribution (Part 2), analytical methods (Part 3), environmental migration (Part 4) and biological uptake (Part 5), is more general. It is likely that the reader will find the information needed on the environmental behaviour of radium in this report, or will at least find references to other, more appropriate, texts contained in it. Refs, figs and tabs

232Th Mass Determination in a Uranium/Thorium Mixture for Safeguards Purposes

International Nuclear Information System (INIS)

Nangu, M.; Marumo, B.; Mbedzi, E.; Rasweswe, M.; Croft, S.; McElroy, R.; Chapman, J.; Bosko, A.

2015-01-01

In nuclear safeguards it is required that thorium content in safeguarded material should be quantified and reported as appropriate. As such the South African State System of Control and Accounting (SSAC) on discovering a number of safeguarded waste drums which contained considerable quantities of thorium decided to initiate a project to properly quantify their thorium content using a high purity germanium detector and In Situ Object Counting System (ISOCS) efficiency calibration software. These metal waste drums are contained inside overpacks which for health reasons cannot be opened and thus giving rise to the challenge of determining the exact fill heights and the density of the material. Fill heights determined using transmission sources and the material density calculated from them together with the geometry used for the overpacks could be used to further refine the ISOCS calibration geometry and thus improving the quantitative result. In order to have confidence on the ISOCS measurements, it was decided to also validate the ISOCS results through the preparation of similar density standards that would be used for the efficiency calibration in the determination of the 232Th activity in the material. In addition, MGAU v4.2, which was used to determine uranium enrichment in a measured material, also provides an approximate 232Th abundance relative to uranium content. ISOCS measurements of 232Th masses in waste drums were compared to MGAU results. Results of these studies are presented in this paper. (author)

Determination of natural alpha-emitting isotopes of uranium and thorium in environmental and geological samples

International Nuclear Information System (INIS)

Crespo, M.T.

1996-01-01

It is described the complete radiochemical procedure used for the determination of uranium and thorium isotopes in environmental and geological samples by alpha spectrometry. Source preparation methods, alpha-counting and spectral analysis are also included

Determination of thorium and uranium at the nanogram per gram level in semiconductor potting plastics by neutron activation analysis

International Nuclear Information System (INIS)

Dyer, F.F.; Emery, J.F.; Bate, L.C.

1985-01-01

A method was developed to determine thorium and uranium in semiconductor potting plastics. The method is based on neutron activation and subsequent radiochemical separation to isolate and permit measurement of the induced 233 Pa and 239 Np. These plastics typically contain macro amounts of silicon, bromine and antimony and nanogram per gram amounts of thorium and uranium. The radiochemical method provides the necessary sensitivity and makes it possible to easily attain adequate decontamination of the tiny amounts of 233 Pa and 239 Np from the high levels of radioactive bromine and antimony. 8 refs

Monitoring of workers and members of the general public for the incorporation of thorium and uranium in the EU and selected countries outside the EU

International Nuclear Information System (INIS)

Werner, E.; Oeh, U.; Hoellriegl, V.; Roth, P.; Regulla, D.

2003-01-01

Among the 92 natural elements, thorium and uranium are elements with only radioactive isotopes. Due to their long half-lives, 232 Th, 235 U and 238 U are the parent nuclides of decay chains, each comprising about 12 daughter isotopes. The daughter isotopes always include several α-emitters and β-emitters. Therefore, incorporation of thorium and uranium may result in significant internal radiation exposure. Indeed, isotopes of these two elements are among those with the highest effective dose following intake by inhalation or ingestion[1]. Thorium and uranium are ubiquitously abundant in the human environment in varying concentrations and therefore may enter also the biosphere. Consequently, these elements are present in food and drinking water and also in the human body. Differences in the environ-mental concentrations, but also dietary habits will influence the internal radiation dose of members of the public. Moreover, human activities may lead to accumulation of thorium and uranium in particular areas. Both the elements have numerous applications even in the non-nuclear industry. Increased concentrations require adequate monitoring of workers. Besides the selection of a method suitable to assess intake or body content of thorium and uranium with the necessary sensitivity and accuracy, the interpretation of measured data with regard to occupational exposure requires the differentiation between incorporation of thorium and uranium at work place and uptake from natural sources respectively. In order to keep the internal exposure due to thorium and uranium for workers as well as for members of the public within acceptable limits and to differentiate between occupational and natural sources of exposure, adequate knowledge is required on: sources of natural Th und U uptake, use of Th und U in industry, procedures to assess individual internal exposure, methods to determine committed effective doses for intakes of Th and U. In the reporting period, studies were

Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds

Energy Technology Data Exchange (ETDEWEB)

Pitchaiah, K.C.; Sujatha, K.; Rao, C.V.S. Brahmmananda; Subramaniam, S.; Sivaraman, N.; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

2015-06-01

In recent years, Supercritical Fluid Extraction (SFE) technique has been widely used for the extraction of metal ions. In the present study, extraction of uranium from nitric acid medium was investigated using supercritical carbon dioxide (Sc-CO{sub 2}) containing various organophosphorous compounds such as trialkyl phosphates e.g. tri-iso-amyl phosphate (TiAP), tri-sec-butyl phosphate (TsBP) and tri-n-butyl phosphate (TBP), dialkylalkyl phosphonates, e.g. diamylamyl phosphonate (DAAP) and dibutyl butyl phosphonate (DBBP), dialkyl hydrogen phosphonates, e.g. dioctyl hydrogen phosphonate (DOHP), dioctylphosphineoxide (DOPO), trioctyl phosphine oxide (TOPO), n-octylphenyl N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) and di-2-ethyl-hexyl phosphoric acid (HDEHP). Some of these ligands have been investigated for the first time in the supercritical phase for the extraction of uranium. The extraction efficiency of uranium was studied with TiAP, DAAP and DBBP as a function of nitric acid concentration; the kinetics of the equilibration period (static extraction) and transportation of the metal complex (dynamic extraction) was investigated. The influence of pressure and temperature on the extraction behaviour of uranium with DAAP was studied from 4 N HNO{sub 3}. The extraction efficiency of uranium from 4 N nitric acid medium was found to increase in the order of phosphates < phosphonates < HDEHP < TOPO < CMPO. In the case of phosphates and phosphonates, the maximum extraction of uranium was found to be from 4 N HNO{sub 3} medium. The acidic extractants, HDEHP and DOHP showed relatively higher extraction at lower acidities. The relative extraction of uranium and thorium from their mixture was also examined using Sc-CO{sub 2} containing phosphates, phosphonates and TOPO. The ligand, TsBP provided better fractionation between uranium and thorium compared to trialkyl phosphates, dialkyl alkyl phosphonates and TOPO.

Derivation of guidelines for uranium residual radioactive material in soil at the New Brunswick Site, Middlesex County, New Jersey

International Nuclear Information System (INIS)

Dunning, D.; Kamboj, S.; Nimmagadda, M.; Yu, C.

1996-02-01

Residual radioactive material guidelines for uranium in soil were derived for the New Brunswick Site, located in Middlesex County, New Jersey. This site has been designated for remedial action under the Formerly Utilized Sites Remedial Action Program of the US Department of Energy (DOE). Residual radioactive material guidelines for individual radionuclides of concern and total uranium were derived on the basis of the requirement that the 50-year committed effective dose equivalent to a hypothetical individual who lives or works in the immediate vicinity of the New Brunswick Site should not exceed a dose of 30 mrem/yr following remedial action for the current-use and likely future-use scenarios or a dose of 100 mrem/yr for less likely future-use scenarios. The DOE residual radioactive material guideline computer code, RESRAD, was used in this evaluation; RESRAD implements the methodology described in the DOE manual for establishing residual radioactive material guidelines. The guidelines derived in this report are intended to apply to the remediation of these remaining residual radioactive materials at the site. The primary radionuclides of concern in these remaining materials are expected to be radium-226 and, to a lesser extent, natural uranium and thorium. The DOE has established generic cleanup guidelines for radium and thorium in soil; however, cleanup guidelines for other radionuclides must be derived on a site-specific basis

Uranium series geochemistry in aquifers: quantification of transport mechanisms of uranium and daughter products: the chalk aquifer (Champagne, France); Desequilibres des series de l'uranium dans les aquiferes: quantification des mecanismes de transport de l'uranium et de ses descendants: cas de l'aquifere de la craie (Champagne, France)

Energy Technology Data Exchange (ETDEWEB)

Hubert, A

2005-09-15

With the increase of contaminant flux of radionuclides in surface environment (soil, river, aquifer...), there is a need to understand and model the processes that control the distribution of uranium and its daughter products during transport within aquifers. We have used U-series disequilibria as an analogue for the transport of uranium and its daughter products in aquifer to understand such mechanisms. The measurements of uranium ({sup 234}U et {sup 238}U), thorium ({sup 230}Th et {sup 232}Th), {sup 226}Ra and {sup 222}Rn isotopes in the solid and liquid phases of the chalk aquifer in Champagne (East of France) allows us to understand the processes responsible for fractionation within the uranium decay chain. Fractionations are induced by physical and chemical properties of the elements (leaching, adsorption) but also by radioactive properties (recoil effect during {alpha}-decay). For the first time a comprehensive sampling of the solid phase has been performed, allowing quantifying mechanisms responsible for the long term evolution of the aquifer. A non steady state 1D model has been developed which takes into account leaching, adsorption processes as well as radioactive filiation and {alpha}-recoil effect. Retardation coefficients have been calculated for uranium, thorium and radium. The aquifer is characterised by a double porosity, and the contribution of fracture and matrix porosity on the water/rock interaction processes has been estimated. (author)

Australia's Uranium and thorium resources and their global significance

International Nuclear Information System (INIS)

Lambert, I.B.; McKay, A.; Miezitis, Y.

2006-01-01

Full text: Full text: Australia's world-leading uranium endowment appears to result from the emplacement of uranium enriched felsic igneous rocks in three major periods during the geological evolution of the continent. Australia has over 27% of the world's total reasonably assured uranium resources (RAR) recoverable at < US$80/kgU (which approximates recent uranium spot prices). Olympic Dam is the largest known uranium deposit, containing approximately 19% of global RAR (and over 40% of global inferred resources) recoverable at < US$80/kg U; the uranium is present at low concentrations and the viability of its recovery is underpinned by co-production of copper and gold. Most of Australia's other identified resources are within Ranger, Jabiluka, Koongarra, Kintyre and Yeelirrie, the last four of which are not currently accessible for mining. In 2004, Australia's three operating uranium mines - Ranger, Olympic Dam, and Beverley -produced 22% of global production. Canada was the only country to produce more uranium (29%) and Kazakhstan (9%) ranked third. Considerably increased uranium production has been recently foreshadowed from Australia (through developing a large open pit at Olympic Dam), Canada (mainly through opening of the Cigar Lake mine), and Kazakhstan (developing several new in situ leach mines). These increases should go a long way towards satisfying demand from about 2010. Olympic Dam has sufficient resources to sustain such increased production over many decades. Thorium is expected to be used in some future generations of nuclear reactors. Australia also has major (but incompletely quantified) resources of this commodity, mainly in heavy mineral sands deposits and associated with alkaline igneous rocks. It is inevitable that the international community will be looking increasingly to Australia to sustain its vital role in providing fuels for future nuclear power generation, given its world-leading identified resources, considerable potential for new

Determination of uranium and thorium contents inside different materials using track detectors and mean critical angles

CERN Document Server

Misdaq, M A; Ktata, A; Merzouki, A; Youbi, N

1999-01-01

The critical angles of the CR-39 (theta sub c) and LR-115 type II (theta sub c ') solid state nuclear track detectors (SSNTD) for detecting alpha-particles emitted by the uranium and thorium series have been evaluated by calculating the corresponding ranges of the emitted alpha-particles in different material samples and in the SSNTD studied. The influence of the emitted alpha-particles initial and residual energies on the critical angles of the SSNTD studied has been investigated. The uranium and thorium contents of different geological samples have been evaluated by exploiting data obtained for the critical angles of the CR-39 and LR-115 type II solid state nuclear track detectors and measuring the corresponding densities of tracks.

Concentrations of Uranium,Thorium and Potassium in Sweden

International Nuclear Information System (INIS)

Thunholm, Bo; Linden, Anders H.; Gustafsson, Bosse

2005-04-01

This report is largely a result of the Swedish contribution to an IAEA co-ordinated research programme (CRP) on the use of selected safety indicators in the assessment of radioactive waste disposal. The CRP was focusing on the assessment of the longterm safety of radioactive waste disposal by means of additional safety indicators based on data from natural systems with emphasis on description of existing data on radioactive elements and radionuclides. A major part of the work was focused on collecting data on geophysics as well as geochemistry and groundwater chemistry; mainly uranium (U), thorium (Th) and potassium (K). Data were interpreted resulting in maps and statistical description

Concentrations of Uranium,Thorium and Potassium in Sweden

Energy Technology Data Exchange (ETDEWEB)

Thunholm, Bo; Linden, Anders H.; Gustafsson, Bosse [Geological Survey of Sweden, Uppsala (Sweden)

2005-04-01

This report is largely a result of the Swedish contribution to an IAEA co-ordinated research programme (CRP) on the use of selected safety indicators in the assessment of radioactive waste disposal. The CRP was focusing on the assessment of the longterm safety of radioactive waste disposal by means of additional safety indicators based on data from natural systems with emphasis on description of existing data on radioactive elements and radionuclides. A major part of the work was focused on collecting data on geophysics as well as geochemistry and groundwater chemistry; mainly uranium (U), thorium (Th) and potassium (K). Data were interpreted resulting in maps and statistical description.

Uranium and thorium series disequilibrium in quaternary carbonate deposits from the Serra da Bodoquena and Pantanal do Miranda, Mato Grosso do Sul State, central Brazil

International Nuclear Information System (INIS)

Ribeiro, Fernando Brenha; Roque, Arnaldo; Boggiani, Paulo Cesar; Flexor, J.-M.

2001-01-01

Activities of gamma-ray emitting members of the uranium ( 238 U) and thorium ( 232 Th) series were measured in a quaternary limestone deposit that outcrops in the southeastern Pantanal Matogrossense Basin and in quaternary tufas deposited at the drainage of the Serra da Bodoquena. It is a first step in a study of the mobilization of uranium and thorium series and its relation to surface hydrology, in a region where carbonate deposits are being continuously dissolved and reprecipitated. The obtained results show that all these deposits are characterized by very low concentrations of uranium and thorium. The 238 U/ 226 Ra and 228 Th/ 228 Ra activity ratios are significantly different than 1.0, indicating that both series are in radioactive disequilibrium. Although the Serra da Bodoquena deposits seem to be very recent, their very fine granulation and high porosity suggest that they behave as open systems for geochemical exchanges of uranium and thorium series members. The Pantanal do Miranda limestone has a radiocarbon age of 3900 yr BP. Since the thorium series is in disequilibrium it is also concluded that this deposit behaves as an open system for geochemical exchanges

Manual on radiological safety in uranium and thorium mines and mills

International Nuclear Information System (INIS)

1976-01-01

The manual describes the personnel radiation hazards in uranium and thorium mines and mills. Measures which should be taken in order to protect the workers are outlined. The problems of air born radioactivity, external radiation, surface contamination and radioactive waste are treated. Safety standards in relation to the above mentioned subjects are given. An outline is given for monitoring programme. Monitoring methods, control methods and means of medical control are given

Properties of uranium and thorium in host rocks of multi-metal (Ag, Pb, U, Cu, Bi, Z, F) Big Kanimansur deposit (Tajikistan)

International Nuclear Information System (INIS)

Fayziev, A.R.

2007-01-01

Multi-metal Big Kanimansur Deposit host rocks contain high averages of uranium and thorium which are more than clark averages by 7 and 2.5 times accordingly. The second property of radio-active elements distribution are low ratio of thorium to uranium. That criteria can be used as prospecting sings for flanks and depth of know ore fields as well as for new squares of multi-metal mineralisation

Potentialities and practical limitations of absolute neutron dosimetry using thin films of uranium and thorium applied to the fission track dating

CERN Document Server

Bigazzi, G; Hadler-Neto, J C; Iunes, P J; Paulo, S R; Oddone, M; Osorio, A M A; Zúñiga, A G

1999-01-01

Neutron dosimetry using natural uranium and thorium thin films makes possible that mineral dating by the fission-track method can be accomplished, even when poor thermalized neutron facilities are employed. In this case, the contributions of the fissions of sup 2 sup 3 sup 5 U, sup 2 sup 3 sup 8 U and sup 2 sup 3 sup 2 Th induced by thermal, epithermal and fast neutrons to the population of tracks produced during irradiation are quantified through the combined use of natural uranium and thorium films. If the Th/U ratio of the sample is known, only one irradiation (where the sample and the films of uranium and thorium are present) is necessary to perform the dating. However, if that ratio is unknown, it can be determined through another irradiation where the mineral to be dated and both films are placed inside a cadmium box. Problems related with film manufacturing and calibration are discussed. Special attention is given to the utilization of thin films having very low uranium content. The problems faced sugg...

Distribution of radium and chemical toxins in the environment of a uranium complex

International Nuclear Information System (INIS)

Markose, P.M.; Eapen, K.P.; Venkataraman, S.; Kamath, P.R.

1978-01-01

The discharge of waste effluents from mining and milling of uranium ore brings into the aquatic environment radioactive pollutants and chemical toxins. The radioactive element of primary concern is radium and the nonactive pollutants are manganese, chlorides, sulphates and water hardness. In the Uranium Complex, Bihar (India), the low grade ore is mined and processed for recovery of uranium. The waste slurries from the process are neutralised and discharged into the tailings pond(TP) where the solids settle and the effluents flow out into a natural stream, Jurianala. The TP effluent mixes with mine water and floor washings from the mill in the canal on its down stream course to the river, R. Subarnarekha. This study was conducted to assess the total pollution from the liquid discharges in the environment and the impact of discharge on water quality. The results of the study of movement of pollutants in the biosphere and laboratory investigations on containment are presented. (author)

Uranium and thorium uptake by live and dead cells of Pseudomonas Sp

International Nuclear Information System (INIS)

Siva Prasath, C.S.; Manikandan, N.; Prakash, S.

2010-01-01

This study presents uptake of uranium (U) and thorium (Th) by live and dead cells of Pseudomonas Sp. Increasing concentration of U and Tb showed decrease in absorption by Pseudomonas Sp. Dead cells of Pseudomonas Sp. exhibited same or more uptake of U and Th than living cells. Increasing temperature promotes uptake of U and Th by Pseudomonas Sp. (author)

Evaluation of thorium based nuclear fuel. Extended summary

International Nuclear Information System (INIS)

Franken, W.M.P.; Bultman, J.H.; Konings, R.J.M.; Wichers, V.A.

1995-04-01

Application of thorium based nuclear fuels has been evaluated with emphasis on possible reduction of the actinide waste. As a result three ECN-reports are published, discussing in detail: - The reactor physics aspects, by comparing the operation characteristics of the cores of Pressurized Water Reactors and Heavy Water Reactors with different fuel types, including equilibrium thorium/uranium free, once-through uranium fuel and equilibrium uranium/plutonium fuel, - the chemical aspects of thorium based fuel cycles with emphasis on fuel (re)fabrication and fuel reprocessing, - the possible reduction in actinide waste as analysed for Heavy Water Reactors with various types of thorium based fuels in once-through operation and with reprocessing. These results are summarized in this report together with a short discussion on non-proliferation and uranium resource utilization. It has been concluded that a substantial reduction of actinide radiotoxicity of the disposed waste may be achieved by using thorium based fuels, if very efficient partitioning and multiple recycling of uranium and thorium can be realized. This will, however, require large efforts to develop the technology to the necessary industrial scale of operation. (orig.)

Radium and heavy metal transport beneath an abandoned uranium tailings dam

International Nuclear Information System (INIS)

Jeffery, J.J.; Sinclair, G.; Lowson, R.T.

1988-09-01

An abandoned uranium tailings dam at Moline in the Northern Territory of Australia was the site of a study to assess the movement of potentially toxic elements from tailings into subsoil. The tailings at Moline were first laid down in 1959 and have since been leached by prevailing rainfall. Sixteen sampling sites were selected to give a good representation of the dam. At each site, a trench was excavated through the tailings and into the subsoil, then samples of subsoil were taken at 10 cm intervals down to a depth of 50 cm. A sample of the tailings overlying the tailings-subsoil interface was also taken. Samples were analysed for radium, uranium, copper, zinc, and lead. At most sites there was only minor accumulation of these elements in the 0-10 cm subsoil layer immediately below the interface, with concentrations typically one or two orders of magnitude less than the concentrations in overlying tailings. Below 10 cm, the concentrations were typically at or close to background concentrations

Rapid non-destructive quantitative estimation of urania/ thoria in mixed thorium uranium di-oxide pellets by high-resolution gamma-ray spectrometry

Energy Technology Data Exchange (ETDEWEB)

Shriwastwa, B.B.; Kumar, Anil; Raghunath, B.; Nair, M.R.; Abani, M.C.; Ramachandran, R.; Majumdar, S.; Ghosh, J.K

2001-06-01

A non-destructive technique using high-resolution gamma-ray spectrometry has been standardised for quantitative estimation of uranium/thorium in mixed (ThO{sub 2}-UO{sub 2}) fuel pellets of varying composition. Four gamma energies were selected; two each from the uranium and thorium series and the time of counting has been optimised. This technique can be used for rapid estimation of U/Th percentage in a large number of mixed fuel pellets from a production campaign.

Rapid non-destructive quantitative estimation of urania/ thoria in mixed thorium uranium di-oxide pellets by high-resolution gamma-ray spectrometry

International Nuclear Information System (INIS)

Shriwastwa, B.B.; Kumar, Anil; Raghunath, B.; Nair, M.R.; Abani, M.C.; Ramachandran, R.; Majumdar, S.; Ghosh, J.K.

2001-01-01

A non-destructive technique using high-resolution gamma-ray spectrometry has been standardised for quantitative estimation of uranium/thorium in mixed (ThO 2 -UO 2 ) fuel pellets of varying composition. Four gamma energies were selected; two each from the uranium and thorium series and the time of counting has been optimised. This technique can be used for rapid estimation of U/Th percentage in a large number of mixed fuel pellets from a production campaign

Measurement of the radioactive concentration in consumer's goods containing natural uranium and thorium and evaluation of the exposure by their utilization

International Nuclear Information System (INIS)

Yoshida, Masahiro; Satou, Shigerou; Ohhata, Tsutomu; Watanabe, Masatoshi; Ohyama, Ryutaro; Furuya, Hirotaka; Endou, Akira

2005-01-01

A number of consumer's goods which contain natural uranium and thorium are circulated in the familiar living environment. Based on various kinds of information sources, 20 kinds of these consumer's goods were collected and their radioactive concentrations were measured by using ICP-MS and Ge semiconductor detector. As this result, it was found that the concentrations of uranium and thorium in the consumer's goods used at home and industries were below 34 Bq/g and below 270 Bq/g, respectively. Next, the concentrations of daughter nuclides were not so different from the ones of uranium or thorium, which showed that the secular radioactive equilibrium held between both concentrations. In addition, the radiation exposures for public consumer were evaluated when four kinds of typical consumer's goods frequently used in daily life are utilized. The results computed by MCNP-4C code were below 250 μSv/y. (author)

Analysis of the gamma spectra of the uranium, actinium, and thorium decay series

International Nuclear Information System (INIS)

Momeni, M.H.

1981-09-01

This report describes the identification of radionuclides in the uranium, actinium, and thorium series by analysis of gamma spectra in the energy range of 40 to 1400 keV. Energies and absolute efficiencies for each gamma line were measured by means of a high-resolution germanium detector and compared with those in the literature. A gamma spectroscopy method, which utilizes an on-line computer for deconvolution of spectra, search and identification of each line, and estimation of activity for each radionuclide, was used to analyze soil and uranium tailings, and ore

Correlation between gamma radiation levels and soil radium concentrations at the Edgemont uranium mill site

International Nuclear Information System (INIS)

Wallace, R.G.; Reed, R.P.; Polehn, J.L.; Wilson, G.T.

1985-01-01

The Tennessee Valley Authority's uranium mill in Edgemont, South Dakota, is being decommissioned. Approximately 4 million tons of contaminated tailings, building equipment, and contaminated soil and debris on the mill site will be removed to the disposal site located approximately 3 kilometers to the southeast. To minimize recontamination of cleaned areas, tailings removal will progress from the northwest corner to the southeast corner of the mill site. As specific areas are cleaned, surveys will be conducted to determine if the concentrations of radium-226 in soil are within the limits outlined in 40 CFR, Part 192. Conformance with the criteria will be demonstrated by a gamma survey of the area employing the differential, or delta-measurement, technique. This technique involves fitting the detector with a base and a receptacle for a removable high-density filter. By making measurements with and without the filter in place, a gamma radiation level proportional to the radium-226 concentration in soil can be determined. This paper describes the results obtained in the development of the correlation between the gamma survey measurements and the soil radium concentrations

Correlation between gamma radiation levels and soil radium concentrations at the Edgemont uranium mill site

International Nuclear Information System (INIS)

Wallace, R.G.; Reed, R.P.; Polehn, J.L.; Wilson, G.T.

1986-01-01

The Tennessee Valley Authority's uranium mill in Edgemont, South Dakota is being decommissioned. Approximately 4 million tons of contaminated tailings, building equipment, and contaminated soil and debris on the mill site will be removed to the disposal site located approximately 3 kilometers to the southeast. To minimize recontamination of cleaned areas, tailings removal will progress from the northwest corner to the southeast corner of the mill site. As specific areas are cleaned, surveys will be conducted to determine if the concentrations of radium-226 in soil are within the limits outlined in 40 CFR, Part 192. Conformance with the criteria will be demonstrated by a gamma survey of the area employing the differential, or delta-measurement, technique. This technique involves fitting the detector with a base and a receptacle for a removable high-density filter. By making measurements with and without the filter in place, a gamma radiation level proportional to the radium-226 concentration in soil can be determined. This paper describes the results obtained in the development of the correlation between the gamma survey measurements and the soil radium concentrations

Uranium and thorium concentration process during partial fusion and crystallization of granitic magma

International Nuclear Information System (INIS)

Cuney, M.

1982-01-01

Two major processes, frequently difficult to distinguish, lead to uranium and thorium enrichment in igneous rocks and more particularly in granitoids; these are partial melting and fractional crystallization. Mont-Laurier uranothoriferous pegmatoids, Bancroft and Roessing deposits are examples of radioelement concentrations resulting mostly of low grade of melting on essentially metasedimentary formations deposited on a continental margin or intracratonic. Fractional crystallization follows generally partial melting even in migmatitic areas. Conditions prevailing during magma crystallization and in particular oxygen fugacity led either to the formation of uranium preconcentrations in granitoids, or to its partition in the fluid phase expelled from the magma. No important economic uranium deposit appears to be mostly related to fractional crystallization of large plutonic bodies

The environmental behaviour of radium. V.2

International Nuclear Information System (INIS)

1990-01-01

The objective of this publication is to provide an up to date review of the environmental behaviour of radium, including methods for analysis, assessment and control. The need for a reference text on the subject was identified at an early stage of the International Atomic Energy Agency's Co-ordinated Research Programme (CRP) on radium behaviour in relation to uranium mining and milling wastes. This publication deals with the sources, properties, environmental behaviour and the methods of analysis, control and assessment of 226 Ra. It is an outgrowth of Agency programmes directed towards the environmental problems involved in uranium mining and milling. The emphasis in several of the sections reflects these origins. For example, many of the contributions in Volume 2 of this report on technologically enhanced sources of radium (Part 1), methods of control and abatement (Part 2) and the impact on man (Part 3) are concerned with uranium mining and milling. Refs, figs and tabs

Crystal and molecular structures of thorium and uranium tetrakis(hexafluoroacetonylpyrazolide) complexes

International Nuclear Information System (INIS)

Volz, K.; Zalkin, A.; Templeton, D.H.

1976-01-01

Triclinic crystals of thorium(IV) and uranium(IV) tetrakis(hexafluoroacetonylpyrazolide) are isostructural, with space group P1 and Z = 2. At 23 0 C for Th(C 6 H 3 ON 2 F 6 ) 4 α = 11.282 (5) A, b = 16.245 (7) A, c = 10.836 (5) A, α = 90.14 (5) 0 , β = 108.75 (5) 0 , and γ = 107.07 (5) 0 . For the uranium compound a = 11.302 (5) A, b = 16.377 (8) A, c = 11.000 (5) A, α = 87.85 (5) 0 , β = 111.02 (5) 0 , and γ = 109.95 (5) 0 . X-ray diffraction data were measured with a scintillation counter, theta-2theta scans, and Mo Kα radiation. For thorium the conventional R value is 0.026 for 2966 unique data with I greater than sigma(I), and for uranium it is 0.027 for 4125 unique data with I greater than sigma(I). The full-matrix least-squares refinement of the 598 parameters of each structure included anisotropic thermal parameters for the 61 nonhydrogen atoms and isotropic ones for the 12 hydrogen atoms. The actinide ion is at the center of an irregular polyhedron of four oxygen and four nitrogen atoms. The average Th-O, Th-N, U-O, and U-N distances are 2.291 (4), 2.637 (5), 2.237 (3), and 2.574 (5) A. The molecules are packed in a manner which resembles cubic closest packing but which is more nearly analogous to the body-centered tetragonal structure of protactinium metal

Contamination of settling ponds and rivers as a result of discharge of radium-bearing waters from Polish coal mines.

Science.gov (United States)

Chalupnik, S; Michalik, B; Wysocka, M; Skubacz, K; Mielnikow, A

2001-01-01

Saline waters from underground coal mines in Poland often contain natural radioactive isotopes, mainly 226Ra from the uranium decay series and 228Ra from the thorium series. Approximately 40% of the total amount of radium remains underground as radioactive deposits, but 225 MBq of 226Ra and 400 MBq of 228Ra are released daily into the rivers along with the other mine effluents from all Polish coal mines. Technical measures such as inducing the precipitation of radium in gobs, decreasing the amount of meteoric inflow water into underground workings, etc. have been undertaken in several coal mines, and as a result of these measures, the total amount of radium released to the surface waters has diminished by about 60% during the last 5-6 years. Mine water can have a severe impact on the natural environment, mainly due to its salinity. However, associated high levels of radium concentration in river waters, bottom sediments and vegetation have also been observed. Sometimes radium concentrations in rivers exceed 0.7 kBq/m3, which is the permitted level for waste waters under Polish law. The extensive investigations described here were carried out for all coal mines and on this basis the total radium balance in the effluents has been calculated. Measurements in the vicinity of mine settling ponds and in rivers have given us an opportunity to study radium behaviour in river waters and to assess the degree of contamination. Solid waste materials with enhanced natural radioactivity have been produced in huge amounts in the power and coal industries in Poland. As a result of the combustion of coal in power plants, low-radioactive waste materials are produced, with 226Ra concentration seldom exceeding a few hundreds of Bq/kg. A different situation is observed in coal mines, where, as a result of precipitation of radium from radium-bearing waters, highly radioactive deposits are formed. Sometimes the radioactivity of such materials is extremely high; precipitates from coal

Different periods of uranium and thorium occurrence in Madagascar (1960); Cycles uraniferes et thoriferes a Madagascar (1960)

Energy Technology Data Exchange (ETDEWEB)

Moreau, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

In Madagascar, the first typical occurrences of thorium and uranium are about 500 million years old. Previously thorium and uranium were rather concentrated in the granitic and charnockitic zones, chiefly in minerals such as monazite, apatite and zircon. At the end of the Precambrian period, metasomatic granites occur especially in the anticlinal series (Andriba orthite granite). The granitization is followed by the formation of the main pegmatitic areas in the Island with Th-U niobotantalates, uraninite and beryl. The pegmatites are well developed in the synclinal series with a poor migmatization or no migmatization at all. In the same time a large uranium and thorium province with uranothorianite deposits appears within the calcomagnesian series of the Southern part of Madagascar. Later, large amounts of monazite were carried down to the detritic Karroo sediments during tile erosion of the metamorphic precambrian rocks. Monazite has been concentrated again by frequent marine incursions, till the present time. In the medium Karroo, near Folakara, uranium minerals occur in direct relation with carbonaceous material. Finally we must note the uranium occurrence in the pleistocene carbonaceous shales of Antsirabe basin, in contact with crystalline rocks. (author) [French] A Madagascar, le premier cycle uranifere et thorifere bien caracterise se situe aux alentours de 500 millions d'annees. Auparavant, le thorium et l'uranium sont concentres de preference dans les zones granitiques et charnockites sous forme de monazite, apatite ou zircon. Vers la fin du Precambrien, se produisent des granitisations metasomatiques, surtout dans les zones anticlinales (type Andriba a orthite). La fin de cette granitisation s'accompagne de la formation des principaux champs pegmatitiques de l'Ile a niobotantalates uraniferes, uraninite et beryl, qui se developpent de preference dans les series synclinales peu ou pas migmatisees. A cette meme epoque s'individualise au sein des series

An assessment of once-through homogeneous thorium fuel economics for light water reactors

International Nuclear Information System (INIS)

Joo, Hyung Kook; Noh, Jae Man; Yoo, Jae Woon

2001-01-01

The fuel economics of an once-through homogeneous thorium fuel concept for PWR was assessed by doing a detailed core analysis. In addition to this, the fuel economics assessment was also performed for two other ways enhancing the economic potential of thorium fuel; thorium utilization in the mixed core with uranium fuel assembly and Duplex thorium fuel concepts. As a results of fuel economics assessment, the thorium fuel cycle does not show any economic incentives in preference to uranium fuel cycle under the 18-months fuel cycle for PWR. However, the utilization of thorium is the mixed core with uranium fuel assembly and Duplex thorium fuel cycle and show superior fuel economics to uranium fuel under the longer fuel cycle scheme. The economic potential of once-through thorium fuel cycle is expected to be increased further by utilizing the Duplex thorium fuel in the mixed core with uranium fuel assembly

Determination of thorium, uranium and potassium elemental concentrations in surface soils in Cyprus

International Nuclear Information System (INIS)

Tzortzis, Michalis; Tsertos, Haralabos

2004-01-01

A comprehensive study was conducted to determine thorium, uranium and potassium elemental concentrations in surface soils throughout the accessible area of Cyprus using high-resolution γ-ray spectrometry. A total of 115 soil samples was collected from all over the bedrock surface of the island based on the different lithological units of the study area. The soil samples were air-dried, sieved through a fine mesh, sealed in 1000-ml plastic Marinelli beakers, and measured in the laboratory in terms of their gamma radioactivity for a counting time of 18 h each. From the measured γ-ray spectra, elemental concentrations were determined for thorium (range from 2.5x10 -3 to 9.8 μg g -1 ), uranium (from 8.1x10 -4 to 3.2 μg g -1 ) and potassium (from 1.3x10 -4 to 1.9%). The arithmetic mean values (A.M.±S.D.) calculated from all samples are: (1.2±1.7) μg g -1 , (0.6±0.7) μg g -1 and (0.4±0.3)%, for thorium, uranium and potassium, respectively, which are by a factor of three-six lower than the world average values of 7.4 μg g -1 (Th), 2.8 μg g -1 (U) and 1.3% (K) derived from all data available worldwide. The best-fitting relation between the concentrations of Th and K versus U and also of K versus Th, is essentially of linear type with a correlation coefficient of 0.93, 0.84 and 0.90, respectively. The Th/U, K/U and K/Th ratios (slopes) extracted are equal to 2.0, 2.8x10 3 and 1.4x10 3 , respectively

Determination of uranium and thorium by X-ray fluorescence analysis in ores and derivatives

International Nuclear Information System (INIS)

Sato, I.M.

1979-01-01

A method to determinate the elements thorium and uranium by X-rays fluorescence in ores and derivatives is presented. The chosen samples are ores from Morro do Agostinho, Pocos de Caldas, Minas Gerais and monazite concentrated from Nucleomon which has the feature of being complex, and which is a type of material frequently found in nuclear technology. The method of fusion is chosen to prepare the samples, in which they are fused in borax in its natural form thus, proposing analyses of those elements without any previous chemical treatment. In the analyses of uranium, the effect of absorption of iron existing in the distinctive line ULα (n=2) of second order is mathematically corrected, instead of baing eliminated by chemical separation. The determination of thorium is made through the method of double-dilution in which several reasons have shown the advantages of its employment. The precision in function the coefficient of variation in percentage and the accuracy of the method proposed are discussed [pt

Analysis of uranium, thorium, and potassium in the soil and rocks in northwestern Taiwan

International Nuclear Information System (INIS)

Shyong, J.; Wu, C.

1984-01-01

The contents of uranium, thorium, and potassium in terrestrial samples in northwestern Taiwan were determined by field survey and core sampling techniques. NaI(Tl) scintillation survey meters were applied to field survey. Analysis of radionuclides in the soil and rocks was performed by a 60 cm 3 Ge(Li) detector connected with a 4096-channel pulse height analyzer and a minicomputer PDP 11/04. Computer programs were used to identify energies of photopeaks, to integrate peak areas, and to evaluate the contents of radionuclides to ppm order. All the factors such as counting efficiency, statistical uncertainty, dead time, etc. had been taken into consideration. Natural terrestrial radiation exposure rates ranging from 6.5 to 20.5 uR.hr -1 were observed in 65 villages or hamlets. The average concentration of each of uranium, thorium, and potassium was 3.7+.0.8 ppm, 12.0+.2.8 ppm, and 1.3+.0.5 percent respectively

The determination of trace quantities of thorium and uranium in thick ore samples by proton-induced x-ray emission

International Nuclear Information System (INIS)

Cohen, D.D.; Duerden, P.; Clayton, E.

1979-07-01

Proton-induced X-ray emission (PIXE) techniques have been used to estimate the concentrations of trace quantities of thorium and uranium in powdered rock and ore samples. Standards of known concentrations were prepared in a carbon matrix and the yields from these used to determine simultaneously the concentrations of thorium and uranium in the ore samples. The experimental detection limit of the technique was found to be 3 to 4 μg g -1 for a 100 μC irradiation. The appropriate matrix corrections for a carbon and ore matrix have been calculated for thick targets and taken into consideration

The determination of radium-226 in uranium ores and mill products by alpha energy spectrometry

International Nuclear Information System (INIS)

Zimmerman, J.B.; Armstrong, V.C.

1975-12-01

A reliable routine procedure for determining 226 Ra by alpha energy spectrometry is described. Radium is isolated as sulphate from the sample matrix by co-precipitation with a small mass of barium and analysed using a ruggedized silicon surface barrier detector. The method is capable of providing high accuracy over a large 226 Ra concentration range and is applicable to materials such as uranium ores, uranium mill products and effluent streams. Samples resulting from nitric acid leach experiments with Elliot Lake ores were examined using the procedure. The distribution of 223 Ra, 224 Ra and 226 Ra between the leach products, (residue and leach liquor), is discussed. (author)

Research on uranium and thorium elements exploration through the study of petrography, petrology and geophysical method in the Saghand Area (Central Iran) Islamic Republic of Iran

International Nuclear Information System (INIS)

Iranmanesh, J.; Fattahi, V.; Raziani, S.

2014-01-01

This study is a research on uranium and thorium exploration by use of the petrography, petrology and radiometric data in the Saghand area, Central Iran plateau. The lithologies of this area comprise of granite and metasomatized granite. As a result of metasomatic process, uranium and thorium bearing minerals such as davidite and alanite were formed. Sericitization and albitization are the main alterations detected in the study area and thorium mineralization is more common in albitization. By investigation of the chemical classification, non-radioactive specimens, rock types include: diorite and granodiorite, while radioactive specimens consist of gabbroic rocks (basalt). According to the magma source graphs, these rocks formed by calc-alkaline series magma. A scintillometer and spectrometer (MGS-150) were used for radiometric data acquisition. 1001 data points have been obtained from 11 profiles and total counts for, K, U, Th were measured. After primary data processing, data logarithms were calculated for normalizing, and the radiometric data show that uranium and thorium enrichment is more than potassium, while thorium and uranium enrichment are approximately equal. After data integration, two probable anomalies were determined in northwest and northeast parts of the study area. (author)

Uranium and thorium occurrences in New Mexico: distribution, geology, production, and resources, with selected bibliography. Open-file report OF-183

International Nuclear Information System (INIS)

McLemore, V.T.

1983-09-01

Over 1300 uranium and thorium occurrences are found in over 100 formational units in all but two counties, in all 1- by 2-degree topographic quadrangles, and in all four geographic provinces in New Mexico. Uranium production in New Mexico has surpassed yearly production from all other states since 1956. Over 200 mines in 18 counties in New Mexico have produced 163,010 tons (147,880 metric tons) of U 3 O 8 from 1948 to 1982, 40% of the total uranium production in the United States. More than 99% of this production has come from sedimentary rocks in the San Juan Basin area in northwestern New Mexico; 96% has come from the Morrison Formation alone. All of the uranium reserves and the majority of the potential uranium resources in New Mexico are in the Grants uranium district. About 112,500 tons (102,058 metric tons) of $30 per pound of U 3 O 8 reserves are in the San Juan Basin, about 55% of the total $30 reserves in the United States. Thorium reserves and resources in New Mexico have not been adequately evaluated and are unknown. Over 1300 uranium and thorium occurrences are described in this report, about 400 of these have been examined in the field by the author. The occurrence descriptions include information on location, commodities, production, development, geology, and classification. Over 1000 citations are included in the bibliography and referenced in the occurrence descriptions. Production statistics for uranium mines that operated from 1948 to 1970 are also included. Mines that operated after 1970 are classified into production categories. 43 figures, 9 tables

Direct separation of uranium and thorium from Qatrani phosphatic raw ore by consecutive percolation leaching

Energy Technology Data Exchange (ETDEWEB)

Hussein El-Sayed, M

1984-07-01

Phosphatic sandstone of Qatrani area contains high concentrations of uranium and thorium (1450 and 870 ppm respectively). These elements were directly separated from a representative sample of the ore by percolation leaching. Separation made was carried out by using two different leaching reagents, citric and nitric acids for obtaining two separate concentrates of U and Th consecutively from the sample. Uranium was leached first by using citric acid where other rock ingredients were left intact. The effects of: (a) increasing acid input amounts and (b) increasing leaching solution volumes (dilution) on U leaching efficiency were studied. The results revealed that citric acid reaction upon phosphate is limited in spite of higher residual acidity reported in the leach liquors. Regarding uranium, its leaching efficiency increased by increasing acid amounts and/or leaching solution volumes while fixing the acid input amounts. The efficiency of U leaching is more pronounced in the second case than in the first. Increasing U leaching while phosphate dissolution is limited could be interpreted as that the relative complexing affinity of citrate anion for hexavalent uranium is by far much greater than with phosphate. Thorium was thereafter leached by using dilute solutions of nitric acid to avoid dissolution of nitric acid to avoid dissolution of impurities. Percolation leaching experiments were thus performed on the uranium-free samples in the columns used previously in uranium leaching. The effects of increasing acid amounts and increasing leach liquor recycles on Th (and P/sub 2/O/sub 5/) leaching efficiency were studied.

Denver radium site's - Case history

International Nuclear Information System (INIS)

Topolski, T.T.

1985-01-01

In developing this case history of the Denver radium sites, an attempt is made to establish the Colorado carnotite connection from the point of discovery to early development and its eventual role in the inception of the National Radium Institute and Denver's radium legacy. Early exploitive mining activities and the exportation of the highest grades of uranium ore to Europe greatly disturbed key officials at the U.S. Bureau of Mines. With its proximity to known carnotite deposits and industrial capacity, Denver's destiny as one of America's early radium production centers became a reality by 1914. With African pitchblend discoveries, Belgium competition spelled the beginning of the end of Denver's romance with radium by 1920. The sites where Denver made or used its radium were lost in obscurity for 60 years and rediscovered in 1979. Thirty one sites and a characterization of their radioactive impact are now a part of the Superfund National Priorities listing for eventual cleanup

Radioanalytical methods manual

International Nuclear Information System (INIS)

Chiu, N.W.; Dean, J.R.

1986-01-01

This Radioanalytical Methods manual is comprised of 12 chapters. It includes a review of the pertinent literature up to the end of 1982 pertaining to the measurement of the radioactive species listed under the terms of the contract. Included is methodology recommended for the decompositions of soils, tailings, ores, biological samples and air filters. Detailed analytical methodology for the measurement of gross alpha, gross beta, gross gamma, uranium, radium-226, radium-228, lead-210, thorium-232, thorium-230, thorium-228, total thorium, radon-222, radon-220 and radon-219 is presented

A study of solvent extraction of uranium and thorium with a crown either carboxylic acid

International Nuclear Information System (INIS)

Du Hongshan

1995-03-01

The solvent extraction of uranium and thorium with a new type of extractant sym-dibenzo-16-crown-5-oxyacetic acid in chloroform has been studied. The extraction efficiencies for both elements depend strongly on pH. At pH 3.5, UO 2 2+ is not extractable, whereas Th 4+ is extracted with greater than 98% efficiency. The dependence of the distribution ratios of UO 2 2+ and Th 4+ on the concentration of sym-dibenzo-16-crown-5-oxyacetic acid are linear and the slopes are 1 and 2 respectively. The results suggest that uranium and thorium appear to form a 1 : 1 and 1 : 2 extraction complex with ligand. A new method for separating U and Th is established, and U and Th with high purity can be obtained. This method have important application to analytical chemistry and nuclear industry. (8 refs., 3 figs.)

Unusual case of radium exposure

International Nuclear Information System (INIS)

Toohey, R.E.; Sha, J.Y.; Urnezis, P.W.; Hwang, E.Y.

1984-01-01

We have determined the body content, distribution, retention, and excretion rate of 226 Ra for a uranium mill worker who inhaled 226 Ra in an unknown form. Radium was retained in the lung with a biological half-life of 120 days, an the amount initially inhaled was estimated to be 180 +- 30 Bq. These values, combined with an observed radon retention factor of 71%, implied a 50-year dose commitment of 0.16 +- 0.04 Sv to the lung. Although it is believed that this case represents an isolated incident, it is possible that some uranium mill workers may form a contemporary population that is occupationally exposed to radium. 5 references, 2 figures, 2 tables

Wayne Interim Storage Site environmental report for calendar year 1992, 868 Black Oak Ridge Road, Wayne, New Jersey

International Nuclear Information System (INIS)

1993-05-01

This report describes the environmental surveillance program at the Wayne Interim Storage Site (WISS) and provides the results for 1992. The fenced, site, 32 km (20 mi) northwest of Newark, New Jersey, was used between 1948 and 1971 for commercial processing of monazite sand to separate natural radioisotopes - predominantly thorium. Environmental surveillance of WISS began in 1984 in accordance with Department of Energy (DOE) Order 5400.1 when Congress added the site to DOE's Formerly Utilized Sites Remedial Action Program (FUSRAP). The environmental surveillance program at WISS includes sampling networks for radon and thoron in air; external gamma radiation exposure; radium-226, radium-228, thorium-230, thorium-232, total uranium, and several chemicals in surface water and sediment; and total uranium, radium-226, radium-228, thorium-230, thorium-232, and organic and inorganic chemicals in groundwater. Monitoring results are compared with applicable Environmental Protection Agency (EPA) and state standards, DOE derived concentration guides (DCGs), dose limits, and other DOE requirements. This monitoring program assists in fulfilling the DOE policy of measuring and monitoring effluents from DOE activities and calculating hypothetical doses. Results for environmental surveillance in 1992 show that the concentrations of all radioactive and most chemical contaminants were below applicable standards

Wayne Interim Storage Site environmental report for calendar year 1992, 868 Black Oak Ridge Road, Wayne, New Jersey. Formerly Utilized Sites Remedial Action Program (FUSRAP)

Energy Technology Data Exchange (ETDEWEB)

1993-05-01

This report describes the environmental surveillance program at the Wayne Interim Storage Site (WISS) and provides the results for 1992. The fenced, site, 32 km (20 mi) northwest of Newark, New Jersey, was used between 1948 and 1971 for commercial processing of monazite sand to separate natural radioisotopes - predominantly thorium. Environmental surveillance of WISS began in 1984 in accordance with Department of Energy (DOE) Order 5400.1 when Congress added the site to DOE`s Formerly Utilized Sites Remedial Action Program (FUSRAP). The environmental surveillance program at WISS includes sampling networks for radon and thoron in air; external gamma radiation exposure; radium-226, radium-228, thorium-230, thorium-232, total uranium, and several chemicals in surface water and sediment; and total uranium, radium-226, radium-228, thorium-230, thorium-232, and organic and inorganic chemicals in groundwater. Monitoring results are compared with applicable Environmental Protection Agency (EPA) and state standards, DOE derived concentration guides (DCGs), dose limits, and other DOE requirements. This monitoring program assists in fulfilling the DOE policy of measuring and monitoring effluents from DOE activities and calculating hypothetical doses. Results for environmental surveillance in 1992 show that the concentrations of all radioactive and most chemical contaminants were below applicable standards.

Ecotoxicity evaluation of an amended soil contaminated with uranium and radium using sensitive plants

Science.gov (United States)

Abreu, M. M.; Lopes, J.; Magalhães, M. C. F.; Santos, E.

2012-04-01

In the centre-north granitic regions of Portugal, during the twenty century radium and uranium were exploited from approximately 60 mines. The closure of all uranium mines, in 2001, raised concerns regarding the possible chemical and radiological effects on the inhabitants health around the mine areas. The main objective of this work was to evaluate the effect of organic amendments and organic hydroxiapatite in the ecotoxicity reduction of agricultural soils contaminated with uranium and radium, by germination and growth tests of two sensitive plants (Lactuca sativa L. and Zea mays L.). Pot experiments, under controlled conditions, were undertaken during two months of incubation at 70% of the soil water-holding capacity. Fluvisol from Urgeiriça region containing large concentration of Utotal (635 mg/kg) and 226Ra (2310 Bq/kg) was used. The soil available fraction, extracted with ammonium acetate, corresponds to 90% and 25% of total concentration of Utotal and 226Ra, respectively. Fine ground bone (FB) and sheep manure (OM) single or mixtures were used as amendments. Four treatments, plus control were carried out in triplicate: (A) soil+40 Mg/ha of FB; (B) soil+70 Mg/ha of OM; (C) soil+70 Mg/ha of OM+40 Mg/ha of FB; (D) soil+70 Mg/ha of OM+20 Mg/ha of FB. After the incubation moist soils were kept at 4-5 °C and subsamples were used for leachates extraction following DIN 38414-S4 method. Maize and lettuce seeds were sown in filter paper moistened with the leachates aqueous solutions and in the moist soil for germination and growth tests. Seedlings after three days of germination were used for growth tests in hydroponic, during seven days, using the leachates. Five seeds per replicate were used. Soil presented: pH(H2O)=5.15, EC=7.3 µS/cm; and Corgnic=12.5 g/kg. After two months of incubation soil pH increased to a maximum of 6.53 in amended samples, and EC showed a dramatic increase when compared to the control (0.398 dS/m), from 1.5 dS/m (treatment-A) to 4.7 d

Qualitative microanalysis of rare earths (ceric and yttric), of thorium and uranium in minerals

International Nuclear Information System (INIS)

Agrinier, H.

1955-01-01

We propose in this study to give a general method of attack of the niobio-titanates, niobio-tantalates, oxides, phosphates or silicates containing rare earths (ceric or yttric), uranium or thorium, and to put in evidence these different elements by microchemical reactions giving crystallization or the characteristic colorations. (M.B.) [fr

Linearity assumption in soil-to-plant transfer factors of natural uranium and radium in Helianthus annuus L

International Nuclear Information System (INIS)

Rodriguez, P. Blanco; Tome, F. Vera; Fernandez, M. Perez; Lozano, J.C.

2006-01-01

The linearity assumption of the validation of soil-to-plant transfer factors of natural uranium and 226 Ra was tested using Helianthus annuus L. (sunflower) grown in a hydroponic medium. Transfer of natural uranium and 226 Ra was tested in both the aerial fraction of plants and in the overall seedlings (roots and shoots). The results show that the linearity assumption can be considered valid in the hydroponic growth of sunflowers for the radionuclides studied. The ability of sunflowers to translocate uranium and 226 Ra was also investigated, as well as the feasibility of using sunflower plants to remove uranium and radium from contaminated water, and by extension, their potential for phytoextraction. In this sense, the removal percentages obtained for natural uranium and 226 Ra were 24% and 42%, respectively. Practically all the uranium is accumulated in the roots. However, 86% of the 226 Ra activity concentration in roots was translocated to the aerial part

Linearity assumption in soil-to-plant transfer factors of natural uranium and radium in Helianthus annuus L

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, P. Blanco [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain); Tome, F. Vera [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain)]. E-mail: fvt@unex.es; Fernandez, M. Perez [Area de Ecologia, Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain); Lozano, J.C. [Laboratorio de Radiactividad Ambiental, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain)

2006-05-15

The linearity assumption of the validation of soil-to-plant transfer factors of natural uranium and {sup 226}Ra was tested using Helianthus annuus L. (sunflower) grown in a hydroponic medium. Transfer of natural uranium and {sup 226}Ra was tested in both the aerial fraction of plants and in the overall seedlings (roots and shoots). The results show that the linearity assumption can be considered valid in the hydroponic growth of sunflowers for the radionuclides studied. The ability of sunflowers to translocate uranium and {sup 226}Ra was also investigated, as well as the feasibility of using sunflower plants to remove uranium and radium from contaminated water, and by extension, their potential for phytoextraction. In this sense, the removal percentages obtained for natural uranium and {sup 226}Ra were 24% and 42%, respectively. Practically all the uranium is accumulated in the roots. However, 86% of the {sup 226}Ra activity concentration in roots was translocated to the aerial part.

Determination of uranium and thorium during chemical treatment of monazite

International Nuclear Information System (INIS)

El-Nadi, Y.A.; Daoud, J.A.; Aly, H.F.; Kregsamer, P.

2000-01-01

Total reflection x-ray fluorescence (TXRF) is a very useful technique for both qualitative and quantitative analysis because of its high detection power and its needed to small sample volumes (less than 100 μl are sufficient). In this work TXRF was used to determine the initial concentrations of the elements included in monazite sand and following up the chemical steps for treatment of monazite with special attention to uranium and thorium concentration as well as lanthanides. The results were compared to those obtained from EDXRF and ICP-MS techniques. (author)

Radium-226 in the food chain near the site of a French uranium mine

International Nuclear Information System (INIS)

Fourcade, N.; Marple, M.L.; Zettwoog, P.

1982-01-01

As part of a study of the final radiological state of a French uranium mine, the links of milk, vegetable and fish food chains were analysed for radium-226. The site chosen is located in low mountains where the radioactivity transfer vector is the water of a deeply embanked river. The mining of this site (10,000 tonnes of uranium) has now been completed, after a period of 20 years. Ore treatment residues have been stored on site in an artificial ten-hectare basin constructed behind a dam erected across the river valley. Analyses have shown great differences in concentration between the different soils and samples of animal food, the higher values being those of samples taken in the immediate vicinity of the water in zones easily flooded. Nevertheless, no major variation in concentration in milk has been noted. On the whole, the vegetables downstream show the same concentration as upstream. In the flesh of fish the concentration downstream is approximately ten times higher than upstream. This suggests that it is possible to observe radioactivity anomalies in the immediate surroundings by analysing the physical and biological media for radium-226. However, the food chains are only partly affected (milk, in which the concentration is lower than in some commercialized waters in the region, and also fish) and the incorporation levels are lower than the annual limits recommended for the public. (author)

A comparative study of distribution coefficients (Kd) for naturally occurring Uranium (U) and Thorium (Th) in two different aquatic environments

International Nuclear Information System (INIS)

Kumar, Ajay; Karpe, Rupali; Rout, Sabyasachi; Narayanan, Usha; Ravi, P.M.

2012-01-01

The uranium and thorium contents and their mobility in aqueous systems are mainly controlled by the pH, alkalinity, the oxidation reduction potential (ORP) and the type of complexing agents present, such as carbonates, phosphates, vanadates, fluorides, sulfates and silicates, etc. A comparative study of distribution coefficients (K d ) for U and Th in sediment-seawater and soil-groundwater system has been carried out. K d was determined using a batch method. In this method, 5 g dried sediment samples was placed in each of seven empty conical flasks and equilibrated for 7 days with 150 mL of sea water containing 10, 20, 30, 40, 50, 75 and 100 mg/L of uranium and thorium contents followed by shaking using end-over end shaker at 25°C. After equilibration time, the samples of each set were centrifuged, filtered through 0.45 μm filter paper and supernatant analyzed for uranium and thorium. In the similar way, experiments were conducted for soil-groundwater system. The concentration of uranium in aliquots of equilibrium solution was measured using laser fluorimeter and Th was determined using anion exchange column followed by co-precipitation with ferric hydroxide and estimated by gross alpha counter. Physico-chemical parameters of soil, sediments, seawater and groundwater were also studied. In this study, K d values have been reported as the mean from two sets of experimental determinations. Based on the resulting data set, it can be concluded that K d values of uranium and thorium are not only dependent on properties of adsorbed phases but also on the kinds of minerals present in that medium. The results of K d values obtained indicated that the sediments have better sorption properties than soil

Survey of thorium utilization in power reactor systems

International Nuclear Information System (INIS)

Schwartz, M.H.; Schleifer, P.; Dahlberg, R.C.

1976-01-01

It is clear that thorium-fueled thermal power reactor systems based on current technology can play a vital role in serving present and long-term energy needs. Advanced thorium converters and thermal breeders can provide an expanded resource base from which the world's growing energy demands can be met. Utilization of a symbiotic system of fast breeders and thorium-fueled thermal reactors can be particularly effective in providing low cost power while conserving uranium resources. Breeder reactors are characterized by high capital costs and very low fuel costs since they produce more fuel than they consume. This excess fuel can be used to fuel thermal converter reactors whose capital costs are low. This symbiosis is optimized when 233 U is bred in the fast breeders and then used to fuel high-conversion-ratio thermal converter reactors operating on the thorium-uranium fuel cycle. The thorium-cycle HTGR, after undergoing more than fifteen years of development in both the United States and Europe, provides for the optimum utilization of our limited uranium resources. Other thermal reactor systems, previously operating on the uranium cycle, also show potential in their capability to utilize the thorium cycle effectively

Supercritical fluid extraction of uranium and thorium using modifier free delivery of ligands

International Nuclear Information System (INIS)

Sujatha, K.; Kumar, R.; Sivaraman, N.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2009-01-01

The modifier free controlled delivery of octyl (phenyl)-N,N-diisobutylcarbamoylmethy phosphineoxide (CMPO) using supercritical carbon dioxide was established for the extraction of uranyl nitrate as well as uranyl nitrate sorbed on tissue paper matrix and the results were compared with modifier method. The preferential extraction of uranium over thorium was also demonstrated using di (2-ethylhexyl)isobutyramide (D2EHIBA). (author)

Low-level radiation in coals utilized and ashes produced at New York State electric utilities

International Nuclear Information System (INIS)

Hornibrook, C.

1981-01-01

Eight coal-fired power plants in New York State were sampled for coal, fly ash and bottom ash. Samples were analyzed for uranium 238, uranium 235, uranium 234, thorium 232, thorium 230, radium 226, lead 210, polonium 210, radon 222. The leachate of six fly ash samples was analyzed for all of the above except radon 222. Some data on fly ash analysis are included

Biological effects of radium

International Nuclear Information System (INIS)

Drosselmeyer, E.

1982-12-01

It is evident from a survey of the current literature that a problem exists in finding the correlation between the exposure of the human body to radiation, with the subsequent development of diseases, particularly for certain types of cancer. A brief history of the early experiences of radium incorporation into humans is given followed by data collected on some important polulation groups exposed to radium body burden, such as miners in rare metal and uranium mines, dial painters and some groups of patients. The medical and technical applications of radium are discussed. A summary is also given of the natural occurence of radium and the amounts in which it is present in the environment. Incorporation, retention and excretion pathways are outlined. In order to study the metabolism and the induction of diseases by radium several animal studies have been performed. The ICRP regards radium-226 as the best known and most studied radionuclide. It can thus serve as a guideline for setting limits for other radionuclides, e.g. plutonium. The valid limiting value for radium-226 of 0.1 μCi for whole body exposure is generally accepted and regarded as sufficiently safe. Finally, transfer factors have been collected as fas as they were available in the literature. (orig./MG) [de

Study on complexation behaviour of uranium and thorium with amino acids at different temperatures in aqueous media

International Nuclear Information System (INIS)

Joshi, J.D.; Patel, M.R.; Patel, A.D.

1992-01-01

The complexation behaviour of uranium and thorium with important amino acids have been studied using Irving-Rossotti titration technique at 25deg, 35deg and 45degC in inert atmosphere of nitrogen and 0.1M ionic strength using NaClO 4 . The thermodynamic parameters ΔG, ΔH and ΔS have been calculated. Results indicate that thorium (IV) is forming more stable complexes than UO 2 2+ . (author). 3 refs., 2 tab

Uranium series disequilibrium measurements at Mol, Belgium

International Nuclear Information System (INIS)

Ivanovich, M.; Wilkins, M.A.

1985-02-01

The contract just completed has funded two parallel uranium series disequilibrium studies and the aims of and the progress to completion of these studies are given in this report. The larger study was concerned with the measurement of uranium series disequilibrium in ground waters derived from sand layers above and below the Boom Clay formation in North East Belgium. The disequilibrium data are analysed in terms of uranium, thorium and radium isotopic geochemistries and in terms of water types and their mixing in the regional groundwater system. It is concluded that most sampled waters are mixtures of younger and older waters. No true old water end-members have been sampled. Simple considerations of the uranium isotopic data indicate that the longest residence times of the sampled waters are not much in excess of 1 to 10 x 10 3 y. Detailed mixing patterns could not be established from this limited data set particularly in the absence of more detailed modelling in conjunction with groundwater hydraulic pressure and flow direction data. (author)

The indispensable role of thorium for creating a sustainable society

International Nuclear Information System (INIS)

Kamei, T.

2012-01-01

Several approaches are required in parallel for constructing a sustainable society. One of them is to fight against global warming. The other one is to make this world nuclear weapon free. Nuclear power has been used for peaceful purpose because nuclear power produces electricity without emitting CO 2 . Nearly 15% of world electricity is produced by nuclear power. Through nuclear power plant has a possibility of severe accident such as Fukushima Daiichi, its advantage is still valuable for the world. President Obama's speech in Prague in 2009 brought a impact to the world to move toward the world without nuclear weapon. The remaining subject is how to treat dismantled fissionable materials. Existing nuclear power plants utilize uranium because only uranium contains natural occurring fissionable material, uranium-235. The spent uranium fuel contains fissionable plutonium-239. Thus, uranium fuel cycle always accompanies possibility of nuclear proliferation. Thorium plays an important role for both solving global warming and nuclear weapon. Fertile thorium can be used as nuclear fuel by support of fissionable plutonium-239 from spent uranium fuel or weapon head. Preliminary calculation indicates that the USA's and Russia's dismantle nuclear weapon enable to start more than 10 GWe of thorium nuclear power plants. In addition, plutonium-239 obtained from uranium fuel is available of 392 GWe of thorium nuclear power. Uranium-233 coming from thorium is also a fissionable but it is hard to be used for weapon because of its accompanied gamma-ray. Thorium itself is now obtained as by-product of rare-earth mining, which is used for high-tech products including photovoltaic cell, wind-mill, and hybrid-vehicle. However, thorium is not taken care adequately and becomes environmental hazard. Both to take care of environment, to support implementation of high-tech product and to make the world without nuclear weapon, a comprehensive role of thorium will be presented

Radium and uranium in phosphate fertilizers and their impact on the radioactivity of waters

International Nuclear Information System (INIS)

Barisic, D.; Lulic, S.; Miletic, P.

1992-01-01

The study of radioactivity in the phosphate fertilizers and water ways of the Kanovci area was performed in order to determine the influence of the application of phosphate fertilizers on the radioactive pollution of these waters. The activity of 226 Ra, 228 Ra, 235 U and 238 U was measured in different types of phosphate fertilizers and waters by means of γ-ray spectrometry. Surface water, water from drainage channels, shallow groundwater and deep groundwater samples were collected from the Kanovci agricultural and well field area in Eastern Slavonia, where phosphate fertilizers have been used for the past 15 years. 137 Cs was also measured in water samples. The typical phosphate fertilizer used in the Kanovci area contains 75 Bq kg -1 of 226 Ra, 9 Bq kg -1 of 228 Ra, 52 Bq kg -1 of 235 U and 1120 Bq kg -1 of 238 U. The estimated annual deposition of uranium and radium in soils of the agricultural and well field area in Kanovci is: 4.5 Bq m -2 for 226 Ra, 0.5 Bq m -2 for 228 Ra, 3.1 Bq m -2 for 235 U and 67 Bq m -2 for 238 U. The greatest concentrations of both uranium isotopes are measured in water from drainage channels with a mean value of 120 Bq m -3 for 238 U and 5.5 Bq m -3 for 235 U. The concentrations of both radium isotopes generally increase with depth of water as distinct from uranium, whose concentrations in deep groundwater are much lower. The highest concentrations of 137 Cs were measured in water from drainage channels; it was not detected in deep groundwater. The 238 U/ 226 Ra activity ratio (AR) is the highest in water from drainage channels and the Bosut River, while in deep groundwater the ratio is only 1.6. Results indicate that high uranium concentrations in surface water, shallow groundwater and water from drainage channels are caused by phosphate fertilizer application in agriculture on the Kanovci area. (author)

The behaviour of radium in soil and in uranium mine-tailings

International Nuclear Information System (INIS)

Shoesmith, D.W.

1984-09-01

The existence of a number of historical wastes has prompted the need to develop a disposal strategy for material contaminated with radium-226. This report reviews the pertinent radiological and chemical properties of radium. Chemical factors that determine the mobility of radium in soil/groundwater environments are discussed. The mineralogy of mine tailings and attempts to leach them are reviewed. Radium levels in leached residues are compared to the standards for radium levels, and realistic targets are suggested for leaching methods. Techniques for scrubbing soil, immobilizing radium and treating wastewater containing radium are reviewed. Recommendations are made for a possible leaching strategy for radium-contaminated soil, and for further research to develop an effective disposal strategy

Alpha spectrometry Analysis of radioisotopes of thorium and uranium in the soil (IAEA soil reference ground 375 and the natural region of Utique (Bizerte))

International Nuclear Information System (INIS)

Mejri, Mouna

2008-01-01

Since the formation of the terrestrial crust, the primordial radionuclides are present in the minerals. The main are the radioactive elemnts of the Uranium 238, of Uranium 235, of the Thorium 232 chains, Potassium 40 and the Ribidium 87. In this survey, we will present the methodology of analysis of the natural radioisotopes of uranium ( 238 U, 235 U and 234 U) and those of the thorium ( 232 Th, 230 Th and 228 Th) presents to the state of tracers in the natural soils. The method of measurement used is the alpha spectrometry. This technique is very important in the radiometric analysis, especially for the pure alpha emitters or for the low levels of radioactivity analysis. The results if analysis of the Thorium are compared to those gotten by the ICP - AES ( t he Atomic Emission Spectrometry Coupled to an inductive Plasma ) . (Author)

Further study of extraction equilibrium of uranium(VI) with dicyclohexano-18-crown-6 and its application to separating uranium and thorium

International Nuclear Information System (INIS)

Wang Wenji; Sun Qing; Chen Bozhong

1987-01-01

The extraction equilibrium of uranium(VI) from aqueous hydrochloric acid solution with dicyclohexano-18-crown-6 isomer A (Ia) and isomer B (Ib) in 1,2-dichloroethane is presented. The extracted species are found to be 1:2 (metal/crown) for Ia and 2:3 for Ib from slope analysis and direct determination of extracted complexes. The extraction equilibrium constants (Kex) were determined at 25 deg C, and were equal to 29.5 for the former and 0.208 for the latter. It is concluded that Ia has stronger coordinate ability for uranium than Ib. The method is effective and selective. The results can be used for the separation of uranium and thorium. (author)

Quantitative electrochromatography of uranium and platinum on papers impregnated with thorium and antimony based cation exchanger

International Nuclear Information System (INIS)

Misra, A.K.

1992-01-01

Electrochromatography of 32 metal ions have been studied on papers impregnated with thorium antimonate cation exchanger in aq. organic acids, aq. nitric acid as well as in EDTA buffers. On the basis of differential migration which depends on the ion exchange properties of thorium antimonate and nature of complexes formed with the electrolytes, some useful qualitative and quantitative separations of synthetic mixtures of metal ions have been achieved. The effect of some other physical parameter has also been discussed. Quantitative separation of platinum and uranium has been developed. (author). 13 refs., 2 figs., 5 tabs

The thorium fuel cycle

International Nuclear Information System (INIS)

Merz, E.R.

1977-01-01

The utilization of the thorium fuel cycle has long since been considered attractive due to the excellent neutronic characteristics of 233 U, and the widespread and cheap thorium resources. Although the uranium ore as well as the separative work requirements are usually lower for any thorium-based fuel cycle in comparison to present uranium-plutonium fuel cycles of thermal water reactors, interest by nuclear industry has hitherto been marginal. Fast increasing uranium prices, public reluctance against widespread Pu-recycling and expected retardations for the market penetration of fast breeders have led to a reconsideration of the thorium fuel cycle merits. In addition, it could be learned in the meantime that problems associated with reprocessing and waste handling, but particularly with a remote refabrication of 233 U are certainly not appreciably more difficult than for Pu-recycling. This may not only be due to psychological constraints but be based upon technological as well as economical facts, which have been mostly neglected up till now. In order to diversify from uranium as a nuclear energy source it seems to be worthwhile to greatly intensify efforts in the future for closing the Th/ 233 U fuel cycle. HTGR's are particularly promising for economic application. However, further R and D activites should not be solely focussed on this reactor type alone. Light and heavy-water moderated reactors, as well as even fast breeders later on, may just as well take advantage of a demonstrated thorium fuel cycle. A summary is presented of the state-of-the-art of Th/ 233 U-recycling technology and the efforts still necessary to demonstrate this technology all the way through to its industrial application

Analysis of thorium and uranium fuel cycles in an iso-breeder lead fast reactor using extended-EQL3D procedure

International Nuclear Information System (INIS)

Fiorina, Carlo; Krepel, Jiri; Cammi, Antonio; Franceschini, Fausto; Mikityuk, Konstantin; Ricotti, Marco Enrico

2013-01-01

Highlights: ► Extension of EQL3D procedure to calculate radio-toxicity and decay heat. ► Characterization of uranium- and thorium-fueled LFR from BOL to equilibrium. ► Safety improvements for a LFR in a closed thorium cycle. ► Advantages of thorium-fueled LFR in terms of decay heat and radio-toxicity generation. ► Safety, decay heat and radio-toxicity concerns for a Th–Pu beginning-of-life core. - Abstract: Use of thorium in fast reactors has typically been considered as a secondary option, mainly thanks to a possible self-sustaining thorium cycle already in thermal reactors and due to the limited breeding capabilities compared to U–Pu in the fast neutron energy range. In recent years nuclear waste management has become more important, and the thorium option has been reconsidered for the claimed potential to burn transuranic waste and the lower build-up of hazardous isotopes in a closed cycle. To ascertain these claims and their limitations, the fuel cycle isotopic inventory, and associated waste radio-toxicity and decay heat, should be quantified and compared to the case of the uranium cycle using realistic core configurations, with complete recycle of all the actinides. Since the transition from uranium to thorium fuel cycles will likely involve a transuranic burning phase, this transition and the challenges that the evolving fuel actinide composition presents, for instance on reactor feedback parameters, should also be analyzed. In the present paper, these issues are investigated based on core physics analysis of the Lead-cooled Fast Reactor ELSY, performed with the fast reactor ERANOS code and the EQL3D procedure allowing full-core characterization of the equilibrium cycle and the transition cycles. In order to compute radio-toxicity and decay heat, EQL3D has been extended by developing a new module, which has been assessed against ORIGEN-S and is presented here. The capability of the EQL3D procedure to treat full-core 3D geometries allowed to

Uranium, thorium and their decay products in human food-chain

International Nuclear Information System (INIS)

Jeambrun, M.

2012-01-01

Uranium, thorium and their decay products are present in trace amounts in all rocks on Earth. Weathering, Mechanisms of soil formation and soil-plant transfers lead to the presence of these radionuclides in all the components of the environment and, through the food-chain transfers, they are also present in animals and men. The objective of this study consists in improving the knowledge on the levels and the variability of the activities of these radionuclides in various foodstuffs and on their sources and transfers. This study is based on the geological variability of the studied sites (granitic, volcanic and alluvial areas) where various foodstuffs are sampled (vegetables, cereals, meat, eggs and dairy products). The possible sources of radionuclides (irrigation waters and soils for plants; water, food and soils for animals) are also sampled in order to study their contribution to the measured activities in the foodstuffs. The results obtained present high variability of the activities in plants, less pronounced in animal products. For plants, the main radionuclide source seems to be the crop soils. Irrigation water, soil particle resuspension and their adhesion to plant surface seems to be important in some cases. For the activities in animal products, a significant contribution of the soil to thorium activity was highlighted. Water contribution to uranium activity in meat and eggs is an area worth further researches. Thus, this study of the possible sources of radionuclides highlights the importance of their role in the understanding of the radionuclide transfers to foodstuffs. (author)

Some applications of x-ray fluorescence spectrography to the determination of uranium and thorium

International Nuclear Information System (INIS)

Jones, R.W.

1959-04-01

Several methods for the determination of uranium and thorium by X-ray fluorescence spectrography are described. In pure solutions the sensitivity for these elements is 5-10 ppm. For solutions containing gross concentrations of impurities, strontium is added as an internal standard. Precision and accuracy of the determinations are about 1% when working in the optimum concentration range. (author)

Uranium's scientific history

International Nuclear Information System (INIS)

Goldschmidt, B.

1990-01-01

The bicentenary of the discovery of uranium coincides with the fiftieth anniversary of the discovery of fission, an event of worldwide significance and the last episode in the uranium -radium saga which is the main theme of this paper. Uranium was first identified by the German chemist Martin Klaproth in 1789. He extracted uranium oxide from the ore pitchblende which was a by-product of the silver mines at Joachimsthal in Bohemia. For over a century after its discovery, the main application for uranium derived from the vivid colours of its oxides and salts which are used in glazes for ceramics, and porcelain. In 1896, however, Becquerel discovered that uranium emitted ionizing radiation. The extraction by Pierre and Marie Curie of the more radioactive radium from uranium in the early years of the twentieth century and its application to the treatment of cancer shifted the chief interest to radium production. In the 1930s the discovery of the neutron and of artificial radioactivity stimulated research in a number of European laboratories which culminated in the demonstration of fission by Otto Frisch in January 1939. The new found use of uranium for the production of recoverable energy, and the creation of artificial radioelements in nuclear reactors, eliminated the radium industry. (author)

Application of ground bone and sheep manure on soils from two contaminated sites and influence on oat growth, uranium and radium uptake and translocation

Science.gov (United States)

Abreu, M. M.; Pacheco, A.; Santos, E.; Magalhães, M. C. F.

2012-04-01

Past radium and uranium exploitation and processing in Urgeiriça mine and radium processing in Barracão (centre-north of Portugal) led to soils and waters contamination. Most of the soils, located in rural areas, are cultivated for vegetables, fruit trees, and/or pasturage, and the waters used for soils irrigation. The objective of this work was to evaluate the capacity of organic amendments and hydroxiapatite to reduce the soil available fraction of Utotal and 226Ra in soils of two areas after four months of incubation. Influence on oat growth, uranium and radium uptake and translocation was also studied. Pot experiments, under controlled conditions, were undertaken during four months of incubation at 70% of the soil water-holding capacity. Urgeiriça (Urg) and Barracão (Brc) soils containing large concentrations of Utotal (635 and 189 mg/kg, respectively), and 226Ra (2310 and 1770 Bq/kg, respectively) were used. The available fraction of these elements, extracted with ammonium acetate, corresponds to: 90 and 20% of total concentration of uranium and radium, respectively, for Urgeiriça soil, and 19 and 43% of total concentration of uranium and radium, respectively, for Barracão soil. Fine ground bone (FB), sheep manure (OM), and vermicompost (V) single or mixtures were used as amendments. Control (soil) and treatments were made in triplicate: (T1) soil+96 g FB/kg of soil; (T2) soil+168 g OM/kg of soil; (T3) soil+168 g OM/kg of soil+96 g FB/kg of soil; (T4) soil+168 g V/kg of soil. After incubation, soil subsamples were analysed for pH, electric conductivity (EC), and available fractions of Utotal and 226Ra. The remaining soils were used for oat (Avena sativa L.) cultivation. Soils had pH 5.15 (Urg) and 6.04 (Brc), and EC 57.3 µS/cm (Urg) and 36.3 µS/cm (Brc). After incubation soil pH increased to a maximum of 6.82 (Urg) and 7.10 (Brc) in amended samples, and EC showed a large increase (15-19 times) when compared to the control. A decrease of the available

Advanced plutonium management in PWR - complementarity of thorium and uranium cycles