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

Thorium and health: state of the art

International Nuclear Information System (INIS)

Leiterer, A.; Berard, Ph.; Menetrier, F.

2010-01-01

This report reviews data available in the literature on the subject: 'thorium and health'. Thorium is a natural radioactive element of the actinide series. It is widely distributed in the earth's crust and 99% is found as isotope thorium-232. Its various uses are explained by its chemical, physical, and nuclear properties. As a potential nuclear fuel, thorium is still in demonstration in pilot scale reactors. But thorium has already multiple and sometimes unknown industrial uses. Some mass market products are concerned like light bulb. This raises the issue of wastes, and of exposures of workers and public. Environmental exposure via food and drink of the general population is low, where as workers can be exposed to significant doses, especially during ore extraction. Data on bio-monitoring of workers and biokinetic of thorium, in particular those provided by ICRP, are gathered here. Studies on health effects and toxicity of thorium are scarce and mostly old, except outcomes of its previous medical use. Studies on other forms of thorium should be undertaken to provide substantial data on its toxicity. Concerning treatment, Ca-DTPA is the recommended drug even if its efficacy is moderate. LiHOPO molecule shows interesting results in animals, and further research on chelating agents is needed. (authors)

Isotopic exchange between 232Th and 234Th using ion exchange resins and its application for the radiochemical separation of thorium and europium

International Nuclear Information System (INIS)

Sepulveda Munita, C.J.A.; Atalla, L.T.

1980-01-01

The determination of thorium via the measurement of 233 Th activity (obtained by irradiating natural thorium with neutrons) may suffer the interference of various radioisotopes which may be also formed during irradiation, if their parent isotopes are present in the sample. Taking into account this possibility, another technique was chosen for the determination of thorium, based on isotopic exchange associated with ionic exchange. Conditions for the isotopic exchange between 234 Th in solution and 232 Th in the resin were optimized. It was verified that the behaviour of 233 Th and 234 Th is the same regarding isotopic exchange with 232 Th. 234 Th was chosen for the experiments since it has a longer half-life (24.1 days) than 233 Th (22.3 min), thus facilitating the performance of the work. As the major objective of this work is to separate thorium and europium isotopes, the behaviour of 152-154 Eu was studied in the same system used for thorium, envisaging a minimum retention of these radioisotopes in the resin. In order to establish the best conditions for separating 234-Th and 152/154-Eu, the following parameters were considered: the thorium concentration in the solution; the hydrochloric acid concentration in solution; the concentration of other elements in solution; the degree of cross-linking of the resin; the flow rate of the solution through the column. The other elements added to the elutant solution were: uranium, molybdenum, lanthanum, europium, ytterbium, bromine, cobalt, barium, manganese, indium, cesium and selenium. Europium was added so to dilute the 152/154-Eu tracer and avoid the retention of the latter in the resin. The other elements were added because they give rise to radioisotopes which interfere in the activation analysis of thorium when 233-Th activity is used and, the separation of these elements from thorium will also be subsequently studied by the method used in the present work. (C.L.B.) [pt

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)

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

Comparative study using different resins to determine thorium isotopes

Energy Technology Data Exchange (ETDEWEB)

Rosa, Mychelle M.L.; Silva, Paulo S.C.; Maihara, Vera A., E-mail: my_linhares@yahoo.com.br, E-mail: pscsilva@ipen.br, E-mail: vmaihara@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Taddei, Maria Helena T., E-mail: mhtaddei@cnen.gov.br [Comissão Nacional de Energia Nuclear (LAPOC/CNEN), Poços de Caldas, MG (Brazil). Laboratório de Pocos de Caldas; Cheberle, Luan T.V., E-mail: luancheberle@gmail.com [Ambientis Radioproteção, Barueri, SP (Brazil)

2017-07-01

Thorium is a naturally occurring radioactive element that is widely distributed in the crust of the Earth. This element is very common in mineral formations in regions with high levels of natural radioactivity, therefore, its determination in environmental samples is important. Thorium isotopes ({sup 228}Th, {sup 230}Th, and {sup 232}Th) were determined in a reference material, the IAEA Soil 327 sample, to validate the two methods employed using different resins. The initial preparation with acid dissolution is the same to both, in the first is used anion exchange resin (DOWEX 1 x 2) and electrodeposition in silver planchets. And in the second method is used a specific chromatographic resin (TEVA) and cerium fluoride microprecipitation. At the end both analysis are quantified by alpha spectrometry. The two methods the results obtained were satisfactory for the reference material used, with relative error of less than 4% for {sup 228}Th, {sup 230}Th, and {sup 232}Th. The main differences found between them were spectrums resolutions, time and cost of analysis. (author)

Quantifying dust input to the Subarctic North Pacific - Results from surface sediments and sea water thorium isotope measurements

Science.gov (United States)

Winckler, G.; Serno, S.; Hayes, C.; Anderson, R. F.; Gersonde, R.; Haug, G. H.

2012-12-01

The Subarctic North Pacific is one of the three primary high-nutrient-low chlorophyll regions of the modern ocean, where the biological pump is relatively inefficient at transferring carbon from the atmosphere to the deep sea. The system is thought to be iron-limited. Aeolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high-nutrient-low chlorophyll status of the Subarctic North Pacific. However, constraining the size of the dust flux to the surface ocean remains difficult. Here we apply two different approaches, based on surface sediment and water column samples, respectively, obtained during the SO202/INOPEX research cruise to the Subarctic North Pacific in 2009. We map the spatial patterns of Th/U isotopes, helium isotopes and rare earth elements across surface sediments from 37 multi-core core-top sediments across the Subarctic North Pacific. In order to deconvolve the detrital endmembers in regions of the North Pacific affected by volcanic material, IRD and hemipelagic input, we use a combination of trace elements with distinct characteristics in the different endmembers. This approach allows us to calculate the relative aeolian fraction, and in combination with Thorium230-normalized mass flux data, to quantify the dust supply. Secondly, we present an innovative approach to use paired Thorium-232 and Thorium-230 concentrations of upper-ocean seawater at 7 stations along the INOPEX track. Thorium-232 in the upper water column is dominantly derived from dissolution of aeolian dust, whereas Thorium-230 data provide a measure of the thorium removal from the surface waters and, thus, allow us to derive Thorium-232 fluxes. Combined with a mean Thorium-232 concentration in dust and estimate of the thorium solubility, the Thorium-232 flux can be translated in a dust flux to the surface ocean. Dust flux estimates for the Subarctic North Pacific will be

238U-234U-230Th chronometry of Fe-Mn crusts: Growth processes and recovery of thorium isotopic ratios of seawater

International Nuclear Information System (INIS)

Chabaux, F.; Cohen, A.S.; O'Nions, R.K.; Hein, J.R.

1995-01-01

Comparison of ( 234 U) excess /( 238 U) and ( 230 Th)/( 232 Th) activity ratios in oceanic Fe-Mn deposits provides a method for assessing the closed-system behaviour of 238 U- 234 U- 230 Th, as well as variations in the initial uranium and thorium isotopic ratios of the precipitated metal oxides. This approach is illustrated using a Fe-Mn crust from Lotab seamount (Marshall Islands, west equatorial Pacific). Here we report uranium and thorium isotopic compositions in five subsamples from the surface of one large 5 cm diameter botyroid of this crust, and from two depth profiles of the outermost rim of the same botyroid. The decrease of ( 234 U) excess /( 238 U) and ( 230 Th/ 232 Th) activity ratio with depth in the two profiles gives mean growth rates, for the last 150 ka, of 7.8 ± 2 mm/Ma and 6.6 ± 1 mm/Ma, respectively. All data points (surface and core samples) but one, define a linear correlation in the Ln ( 230 Th/ 232 Th) - Ln [( 234 U) excess ( 238 U)] diagram. This correlation indicates that for all points the U-Th system remained closed after the Fe-Mn layer precipitated, and that the different samples possessed the same initial Uranium and thorium isotope ratios. Furthermore, these results show that the preserved surface of this Fe-Mn crust may not be the present-day growth surface, and that the thorium and uranium isotopic ratios of seawater in west equatorial Pacific have not changed during the past 150 ka. The initial thorium activity ratio is estimated from the correlation obtained between Ln( 230 Th/ 232 Th) and Ln [( 234 U) excess /( 238 U)

Thematic network on the analysis of thorium and its isotopes in workplace materials

International Nuclear Information System (INIS)

Bernot, C.; Butler, O.; Howe, A.

2002-05-01

An EC-funded thematic network was established to bring together experts in the field of thorium analysis in order to co-ordinate research activity and identify best analytical practice, requirements for reference materials, etc. The work programme of the network included (i) a survey of past, current and proposed research to determine future research needs; (ii) a series of intercomparison exercises to test the performance of methods for measuring thorium in workplace materials; and (iii) a workshop to promote best practice and transfer information to regulatory authorities and industry. Three interlaboratory comparisons were carried out, as planned, to test the performance of techniques and methodologies available for measurement of thorium. Test solutions containing 232 Th and 228 Th in equilibrium, test solutions containing 232 Th and 228 Th in disequilibrium and solid test samples containing 232 Th and 228 Th in equilibrium were supplied to participants. These were analysed by a variety of techniques. Full details of the three laboratory intercomparisons are given in a series of HSL reports and in other publications

Thorium contents in soils, vegetables, cereals, and fruits

International Nuclear Information System (INIS)

Frindik, O.

1989-01-01

Thorium contents (α-activities of the naturally occurring isotopes Th-228, Th-230, and Th-232) were detrmined in soils, vegetables, cereals, and fruits. The thorium content of plants depends on the degree of contamination by soil resuspension and thus on the specific surface of the plants. The activity of the isotope Th-230 is almost the same as that of the main isotope Th-232. Th-228, with about the same activity as Th-232 in soil, increases to about 10-fold the activity in vegetables, 29-fold in sweet chestnuts and 740-fold in Brazil nuts. Thorium concentration factors from the soil to these vegetable products are calculated; they include the total concentration, not only the soluble portion of thorium. (orig.) [de

Standard test method for analysis of total and isotopic uranium and total thorium in soils by inductively coupled plasma-mass spectrometry

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 This test method covers the measurement of total uranium (U) and thorium (Th) concentrations in soils, as well as the determination of the isotopic weight percentages of 234U, 235U, 236U, and 238U, thereby allowing for the calculation of individual isotopic uranium activity or total uranium activity. This inductively coupled plasma-mass spectroscopy (ICP-MS) method is intended as an alternative analysis to methods such as alpha spectroscopy or thermal ionization mass spectroscopy (TIMS). Also, while this test method covers only those isotopes listed above, the instrumental technique may be expanded to cover other long-lived radioisotopes since the preparation technique includes the preconcentration of the actinide series of elements. The resultant sample volume can be further reduced for introduction into the ICP-MS via an electrothermal vaporization (ETV) unit or other sample introduction device, even though the standard peristaltic pump introduction is applied for this test method. The sample preparatio...

Thorium-applications and handling

International Nuclear Information System (INIS)

Reichelt, A.

1993-01-01

The most important aspects concerning the natural occurrence and extraction of thorium are presented the topics covered are: natural isotopes, occurence in minerals, thorium-activity-content of naturally occuring materials, the resulting radiation exposure, extraction of thorium from ores, time-dependent activity after separation. The sources of radiation exposure due to Thorium, caused by human activity, can be divided into two categories, namely, those in which thorium is deliberately added to (consumer) products in order to improve their usefullness, and those in which the thorium is present accidentally and unwanted due to the naturally occuring thorium in the material used in the manufacturing processes. Some examples of such products and substances will be presented and results about their specific thorium activity will be discussed. Experimental data from a currently running research programme, will be presented, and will include results concerning the radiation occupational exposure due to phosphate fertilizers, thorium impregnated gas mantles and the use of thoriated TIG-Electrodes in arc welding. (orig.) [de

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)

Uptake of uranium, thorium and radium isotopes by plants growing in dam impoundment Tasotkel and the Lower Shu region (Kazakhstan)

International Nuclear Information System (INIS)

Matveyeva, Ilona; Burkitbayev, Mukhambetkali

2016-01-01

The activity concentrations of isotopes of uranium, thorium and radium-226 in dominant species of plants (Xantium strumarium, Phragmites communis, Artemisia nitrosa and Artemisia serotina) growing on the territories contaminated by uranium industry of Kazakhstan (close to dam impoundment Tasotkel and the Lower Shu region) are presented. The obtained data showed the significant variations of activity concentrations of isotopes of uranium, thorium and radium-226 in above ground parts. The concentrations of most of the investigated radionuclides in the root system are higher than in the aboveground parts; it can be explained by root barrier. It was found that the highest root barrier has Xantium strumarium, especially for uranium isotopes. The concentration ratios of radionuclides were calculated, and as the result it was found that the highest accumulation ability in the investigated region has Artemisia serotina.

Uptake of uranium, thorium and radium isotopes by plants growing in dam impoundment Tasotkel and the Lower Shu region (Kazakhstan)

Energy Technology Data Exchange (ETDEWEB)

Matveyeva, Ilona; Burkitbayev, Mukhambetkali [al-Farabi Kazakh National University, Almaty (Kazakhstan). Faculty of Chemistry and Chemical Technology; Jacimovic, Radojko [Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences; Planinsek, Petra; Smodis, Borut [Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences; Jozef Stefan International Postgraduate School, Ljubljana (Slovenia)

2016-04-01

The activity concentrations of isotopes of uranium, thorium and radium-226 in dominant species of plants (Xantium strumarium, Phragmites communis, Artemisia nitrosa and Artemisia serotina) growing on the territories contaminated by uranium industry of Kazakhstan (close to dam impoundment Tasotkel and the Lower Shu region) are presented. The obtained data showed the significant variations of activity concentrations of isotopes of uranium, thorium and radium-226 in above ground parts. The concentrations of most of the investigated radionuclides in the root system are higher than in the aboveground parts; it can be explained by root barrier. It was found that the highest root barrier has Xantium strumarium, especially for uranium isotopes. The concentration ratios of radionuclides were calculated, and as the result it was found that the highest accumulation ability in the investigated region has Artemisia serotina.

Concentration of thorium isotopes and the activity ratios of 230Th/232Th and 228Th/232Th in seawater in the Pacific Ocean

International Nuclear Information System (INIS)

Miyake, Yasuo; Sugimura, Yukio; Yasujima, Tadahide.

1978-01-01

The concentration of thorium isotopes and the activity ratios of 230 Th/ 232 Th and 228 Th/ 232 Th in 500 l sea water samples collected in the Pacific Ocean were determined. Thorium isotopes were analyzed by alpha-ray spectrometry after separating them from other elements with an anion exchange resin. The average content of thorium ( 232 Th) of 0.9 ng l -1 was obtained in the open Pacific water. The average contents of 230 Th and 228 Th were 2.1 x 10 -2 pgl -1 and 1.2 agl -1 respectively. It was found that the ratios of 230 Th/ 232 Th and 228 Th/ 232 Th ranged respectively from 1.0 to 29, and from 0.4 to as high as 128. (author)

Alpha low activity determination from limitter isotopes of uranium, thorium ands radium in natural waters

International Nuclear Information System (INIS)

Gascon, J.L.; Crespo, M.T.; Acena, M.L.

1989-01-01

A method to concentrate uranium, thorium and radium in natural waters has been developed. The method, based on the adsorbing propert-ies of manganes dioxide, has been applied to determine the alpha emitter isotopes of these elements in drinking water of Madrid. In this work we present the description of the method, the analytical procedu-res and the obtained results. (Author)

Alpha spectrometry and secondary ion mass spectrometry of thorium

International Nuclear Information System (INIS)

Strisovska, Jana; Kuruc, Jozef; Galanda, Dusan; Matel, Lubomir; Velic, Dusan; Aranyosiova, Monika

2009-01-01

A sample of thorium content on steel discs was prepared by electrodeposition with a view to determining the natural thorium isotope. Thorium was determined by alpha spectrometry and by secondary ion mass spectrometry and the results of the two methods were compared

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)

The EC thematic network on the analysis of thorium and its isotopes in workplace materials

International Nuclear Information System (INIS)

Howe, A.M.; Bernot, C.; Woods, M.J.

2001-01-01

Accurate measurements of workplace exposure to 232 Th and its progeny are required to estimate internal radiation doses received by persons working with thorium-containing materials. However, a small intercomparison carried out in the mid-nineteen nineties raised doubts about the reliability of results obtained by methods available for measurement of thorium. An EC-funded thematic network was therefore established to bring together experts in the field of thorium analysis in order to coordinate research activity and identify best analytical practice, requirements for reference materials, etc. This network has now successfully completed its work programme, which included a survey to determine future research needs; a series of intercomparisons to test the performance of methods for measuring thorium in workplace materials, and a workshop held to promote best practice and transfer information to regulatory authorities and industry. Results of the work have been used to make various recommendations concerning future needs in this field. (author)

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)

Hydrogeochemical applications of natural isotope of the U (4n+2) and Th(4n) series in Morro do Ferro, Pocos de Caldas (MG), Brazil

International Nuclear Information System (INIS)

Bonotto, D.M.

1987-01-01

Uranium and thorium isotopic analysis were performed on well spoils of the ore body at Morro do Ferro, Pocos de Caldas (MG), Brazil, using groundwater from several boreholes in the area and surface water from a stream and that originates at the base of the hill. For uranium and thorium extraction, a chemical process was applied to samples; activites of 228 Th and 232 Th radioisotopes (4n+2 series) were determined by alpha spectrometry. The uranium concentration and 234 U/ 238 U isotope ratio in groundwater were applied to developed models for deducing proportions of water in a mixture and for characterizing uranium accumulation. The correlation between variability in concentration of uranium dissolved in groundwater and alteration of the level of the water table due to infiltration of rainfall was observed. Chemical analysis of the major and minor compounds for groundwater of the ore body zone were done. (Author) [pt

Determination of trace element concentrations and stable lead, uranium and thorium isotope ratios by quadrupole-ICP-MS in NORM and NORM-polluted sample leachates

International Nuclear Information System (INIS)

Mas, J.L.; Villa, M.; Hurtado, S.; García-Tenorio, R.

2012-01-01

Highlights: ► Polluted sediment and NORM samples. ► An efficient yet fast process allowing multi-parametric determinations in 206 Pb/ 207 Pb/ 208 Pb, 238 U/ 234 U and 232 Th/ 230 Th isotope ratios using a single sample aliquot and a single instrument (ICP-QMS). Eichrom UTEVA ® extraction chromatography minicolumns were used to separate uranium and thorium in sample leachates. Independent ICP-MS determinations of uranium and thorium isotope ratios were carried out afterwards. Previously a small aliquot of the leachate was used for the determination of trace element concentrations and lead isotope ratios. Several radiochemical arrangements were tested to get maximum performances and simplicity of the method. The performances of the method were studied in terms of chemical yields of uranium and thorium and removal of the potentially interfering elements. The established method was applied to samples from a chemical industry and sediments collected in a NORM-polluted scenario. The results obtained from our method allowed us to infer not only the extent, but also the sources of the contamination in the area.

Interpretation of thorium bioassay data

International Nuclear Information System (INIS)

Juliao, L.M.Q.C.; Azeredo, A.M.G.F.; Santos, M.S.; Melo, D.R.; Dantas, B.M.; Lipsztein, J.L.

1994-01-01

A comparison have been made between bioassay data of thorium-exposed workers from two different facilities. The first of these facilities is a monazite sand extraction plant. Isotopic equilibrium between 232 Th and 238 Th was not observed in excreta samples of these workers. The second facility is a gas mantle factory. An isotopic equilibrium between 232 Th and 228 Th was observed in extra samples. Whole body counter measurements have indicated a very low intake of thorium through inhalation. As the concentration of thorium in feces was very high it was concluded that the main pathway of entrance of the nuclide was ingestion, mainly via contamination through dirty hands. The comparison between the bioassay results of workers from the two facilities shows that the lack of Th isotopic equilibrium observed in the excretion from the workers at the monazite sand plant possibly occurred due to an additional Th intake by ingestion of contaminated fresh food. This is presumably because 228 Ra is more efficiently taken up from the soil by plants, in comparison to 228 Th or 232 Th, and subsequently, 228 Th grows in from its immediate parent, 228 Ra. (author) 5 refs.; 3 tabs

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

Thorium isotopes as indicators of scavenging rates in the Venice lagoon

International Nuclear Information System (INIS)

Cochran, J. K.; Hirschberg, D.J.; Barnes, C.

1995-01-01

The naturally occurring thorium isotopes 228 Th and 234 Th, produced in sea water from decay of 228 Ra and 238 U, respectively, were used to estimate the rate of scavenging onto particle surfaces and the rate of removal of particles from the water column of the Venice Lagoon. Large water samples (1000-2000 L) were collected at three sites in the shallow ( 2 -impregnated cartridges to extract dissolved thorium. Activities of particulate 234 Th ranged from 510 to 1335 μBq L -1 and dissolved 234 Th was -1 . Relative to calculated 238 U activities in the lagoon, the 234 Th data yielded mean residence times as short as 2 h for the scavenging of dissolved 234 Th onto particles and 12 h for the removal of particulate 234 Th. Resuspension rates of 0.6 to 8 mg cm -2 day -1 were estimated from the data on dissolved and particulate 234 Th, these values being comparable to those determined by sediment traps (1.8-9.5 mg cm -2 day -1 ) at the same sites. These results suggest that Th and other similarly reactive trace metals are removed rapidly from the waters of the Venice Lagoon to the sediments. 23 refs., 4 tabs., 2 figs

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

Thematic network on the analysis of thorium and its isotopes in workplace materials. Report on the 2nd intercomparison exercise

International Nuclear Information System (INIS)

Howe, A.; White, M.

2000-12-01

Work Package 2 (WP 2) of the EC Thematic Network on ''The analysis of thorium and its isotopes in workplace materials'' is concerned with ''Examination and comparison of analytical techniques for the determination of thorium and its progeny in bulk materials and the development of standards, both for the calibration of associated metrological facilities, and for routine quality control purposes''. The primary objective of WP 2 is ''To evaluate appropriate techniques and determine best practice for analysis of 232 Th at workplace levels and environments'', and is to be achieved through a series of intercomparison exercises. Following the results of the 1st intercomparison exercise, a 2nd intercomparison exercise was designed to evaluate the capability of the analytical methods currently being used by European laboratories to determine thorium at very low levels in the presence of a complex inorganic matrix. The intercomparison exercise involved the analysis of three samples of thorium in solution, prepared by the United Kingdom National Physical Laboratory. One sample was the equilibrium solution, analysed in the 1st intercomparison exercise. The other two samples were prepared by dilution of a non-equilibrium thorium solution, one of which was spiked with impurity elements. (i) The results showed a further improvement in the accuracy of measurements in the equilibrium solution, when compared with the results from the 1st intercomparison study. There was an overall drop in u-test values and the number of u-test values above the upper limit of significance fell from 6 to 3. (ii) Overall, participating laboratories also performed well in the analysis of the low level non-equilibrium solutions. However, several laboratories using y-spectrometry had insufficient sensitivity for measurement of low level non-equilibrium sample solutions and did not report results. (iii) There was little evidence that the presence of impurities had a detrimental effect on measurements made

Uranium isotopes as radioactive pollutants in groundwaters of the Morro do Ferro thorium deposit, Brazil

International Nuclear Information System (INIS)

Bonotto, D.M.

1991-01-01

Groundwater and surface water samples were collected at Morro do Ferro, a thorium and rare earth deposit located on the Pocos de Caldas Plateau, Minas Gerais State, Brazil, to evaluate if the mechanisms related to the migration of 238 U and 234 U isotopes can generate concentrations greater than the gross-alpha activity contaminant limit. The 238 U content range was 0.003-0.24 pCi/1 and the 234 U content range was 0.004-0.25 pCi/1, showing that the studied hydrologic environment doesn't indicate pollution by radioactivity due to these nuclides. However, 226 Ra and 228 Ra isotopes can be considered as radioactive pollutants in groundwaters but not in surface waters of the Morro do Ferro. (author)

Natural thorium isotopes in marine sediment core off Labuan port

Energy Technology Data Exchange (ETDEWEB)

Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.; Mohamed, C. A. R. [School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600, Bangi, Selangor (Malaysia)

2014-02-12

Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.

Evaluation of mass transport property using natural uranium-series and thorium-series nuclides in the Toki Granite

International Nuclear Information System (INIS)

Hama, Katsuhiro

2016-07-01

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host crystalline rock at Mizunami City in Gifu Prefecture, central Japan. The project proceeds in three overlapping phases, 'Phase I: Surface-based investigation Phase', 'Phase II: Construction Phase' and 'Phase III: Operation Phase'. As a part of the Phase III investigation, the mass transport property has been evaluated by using natural uranium-series and thorium-series nuclides in the Toki Granite. In this report, the compilation of existing data and preliminary evaluation was carried out. (author)

Nuclear energy from thorium

International Nuclear Information System (INIS)

Coote, G.E.

1977-06-01

Relevant topics in nuclear and reactor physics are outlined. These include: the thorium decay series; generation of fissile from fertile nuclides, in particular U-233 from Th-232; the princiiples underlying thermal breeder reactors; the production of U-232 in thorium fuel and its important influence on nuclear safeguards and the recycling of U-233. Development work is continuing on several types of reactor which could utilise thorium; each of these is briefly described and its possible role is assessed. Other tipics covered include safety aspects of thorium oxide fuel, reprocessing, fabrication of recycle fuel and the possibility of denaturing U-233 by adding natural uranium. It is concluded that previoue arguments for development of the thorium cycle are still valid but those relating to non-proliferation of weapons may become even more compelling. (auth.)

Differential geochemical behaviour of natural isotopes of U and Th in an aquifer in humid tropical terrain

International Nuclear Information System (INIS)

Bonotto, D.M.

1989-01-01

Uranium and thorium isotopic analyses were performed on spoil samples from the saturated zone of a borehole drilled in the main ore body of a high grade thorium/rare earth ore, and on groundwaters from a borehole drilled in the zone. The deposit is located at Morro do Ferro, a hill near the centre of the Pocos de Caldas Plateau (MG), where an aquifer system developed in the weathered mantle due to in situ intense alteration. For extraction of uranium and thorium a long chemical process was applied to the samples; activities of Th-228 and Th-232 isotopes (4n series) and also of U-238, U-234 and Th-230 isotopes (4n+2 series) were determined by the alpha spectrometry method. U-234/U-238 activity ratios in groundwaters were between 1 and 2 but Th-228/Th-232 activity ratios showed marked isotopic fractionation between these nuclides. The mechanism of mobilization of uranium by complexation with humic substances is considered. U-234/U-238, Th-228/Th-232 and Th-230/U-234 activity ratios in soil samples allowed consider action of other possible mechanisms related to the mobilization of uranium, such as, ion-exchange reaction and adsorption by Fe and Mn oxides. (author) [pt

The thorium alloys in aeronautics: from material analysis to regulation application

International Nuclear Information System (INIS)

Laroche, P.; Cazoulat, A.; Gerasimo, P.

1999-01-01

The thorium handled in aeronautics is a mixing in variable proportion of different thorium isotopes and its daughter products, but the regulation considers only two alpha emitters (Th-232 and Th-228): the thorium being considered as a natural radioactive substance, the legislation and the activities authorised are less restrictive than for artificial elements, it is a paradoxical situation because the thorium has the annual limit of intake the lowest of the regulation. (N.C.)

A PWR Thorium Pin Cell Burnup Benchmark

Energy Technology Data Exchange (ETDEWEB)

Weaver, Kevan Dean; Zhao, X.; Pilat, E. E; Hejzlar, P.

2000-05-01

As part of work to evaluate the potential benefits of using thorium in LWR fuel, a thorium fueled benchmark comparison was made in this study between state-of-the-art codes, MOCUP (MCNP4B + ORIGEN2), and CASMO-4 for burnup calculations. The MOCUP runs were done individually at MIT and INEEL, using the same model but with some differences in techniques and cross section libraries. Eigenvalue and isotope concentrations were compared on a PWR pin cell model up to high burnup. The eigenvalue comparison as a function of burnup is good: the maximum difference is within 2% and the average absolute difference less than 1%. The isotope concentration comparisons are better than a set of MOX fuel benchmarks and comparable to a set of uranium fuel benchmarks reported in the literature. The actinide and fission product data sources used in the MOCUP burnup calculations for a typical thorium fuel are documented. Reasons for code vs code differences are analyzed and discussed.

High-precision measurements of uranium and thorium isotopic ratios by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS)

Science.gov (United States)

Wang, Lisheng; Ma, Zhibang; Duan, Wuhui

2015-04-01

Isotopic compositions of U-Th and 230Th dating have been widely used in earth sciences, such as chronology, geochemistry, oceanography and hydrology. In this study, five ages of different carbonate samples were measured using 230Th dating technique with U-Th high-precision isotopic measurements by multi-collector inductively coupled plasma mass spectrometry, in Uranium-series Chronology Laboratory, Institute of Geology and Geophysics, Chinese Academy of Sciences.In this study, the precision and accuracy of uranium isotopic composition were estimated by measuring the uranium ratios of NBS-CRM 112A, NBS-CRM U500 and HU-1. The mean measured ratios, 234U/238U = 52.86 (±0.04) × 10-6 and δ234U = -38.36 (±0.77) × 10-3 for NBS-CRM 112A, 234U/238U = 10.4184 (±0.0001) × 10-3, 236U/238U = 15.43 (±0.01) × 10-4 and 238U/235U = 1.00021 (±0.00002) for NBS-CRM U500, 234U/238U = 54.911 (±0.007) and δ234U = -1.04 (±0.13) × 10-3 for HU-1 (95% confidence levels). The U isotope data for standard reference materials are in excellent agreement with previous studies, further highlighting the reliability and analytical capabilities of our technique. We measured the thorium isotopic ratios of three different thorium standards by MC-ICPMS. The three standards (Th-1, Th-2 and Th-3) were mixed by HU-1 and NBS 232Th standard, with the 230Th/232Th ratios from 10-4 to 10-6. The mean measured atomic ratios, 230Th/232Th = 2.1227 (±0.0024) × 10-6, 2.7246 (±0.0026) × 10-5, and 2.8358 (±0.0007) × 10-4 for Th-1, Th-2 and Th-3 (95% confidence levels), respectively. Using this technique, the following standard samples were dated by MC-ICPMS. Sample RKM-4, collected from Babardos Kendal Hill terrace, was used during the first stage of the Uranium-Series Intercomparison Project (USIP-I). Samples 76001, RKM-5 and RKM-6 were studied during the second stage of the USIP program (USIP-II). Sample 76001 is a laminated flowstone, collected from Sumidero Terejapa, Chiapas, Mexico, and samples

Verification of a Subgroup Generation Method for Thorium Fuel Assemblies

International Nuclear Information System (INIS)

Sim, Ohsung; Kim, Myunghyun

2013-01-01

Resonance parameter consists of subgroup level and weight. The subgroup weight is obtained by solving the ultrafine slowing down equation and fixed source problem. That means this cross section library procedure considers conservation of the shielded cross section for pin-cell in order to obtain subgroup parameters. There are some isotopes to be concerned for research such as actinides and thorium. Minor actinides(MA) are existing with very small amount in a spent fuel, but effect is not negligible in a high burnup fuel assemblies. Some MAs have high fission cross sections under thermal neutron spectrum. Thorium isotopes was not investigated as much as uranium, but it has high potential for future application. In this study, a new cross section library to be replaced with HELIOS library was generated and compared for the assembly calculation, specially for assembly with thorium. An average capture cross section value at a certain fuel pin and multiplication factor of assembly were compared with nTRACER calculation with HELIOS library and Monte Carlo calculation of MCNP with ENDF-B/II. The accuracy of library data generated for thorium isotope in nTRACER calculation was tested for WASB model. There was a great improvement in K-eff and capture cross section for this assembly compared with old library, HELIOS library

Titanium(IV), zirconium, hafnium and thorium

International Nuclear Information System (INIS)

Brown, Paul L.; Ekberg, Christian

2016-01-01

Titanium can exist in solution in a number of oxidation states. The titanium(IV) exists in acidic solutions as the oxo-cation, TiO 2+ , rather than Ti 4+ . Zirconium is used in the ceramics industry and in nuclear industry as a cladding material in reactors where its reactivity towards hydrolysis reactions and precipitation of oxides may result in degradation of the cladding. In nature, hafnium is found together with zirconium and as a consequence of the contraction in ionic radii that occurs due to the 4f -electron shell, the ionic radius of hafnium is almost identical to that of zirconium. All isotopes of thorium are radioactive and, as a consequence of it being fertile, thorium is important in the nuclear fuel cycle. The polymeric hydrolysis species that have been reported for thorium are somewhat different to those identified for zirconium and hafnium, although thorium does form the Th 4 (OH) 8 8+ species.

Determination of trace element concentrations and stable lead, uranium and thorium isotope ratios by quadrupole-ICP-MS in NORM and NORM-polluted sample leachates

Energy Technology Data Exchange (ETDEWEB)

Mas, J.L., E-mail: ppmasb@us.es [Dpto. Fisica Aplicada I, EPS, Universidad de Sevilla, 41012 Sevilla (Spain); Villa, M. [Servicio de Radioisotopos, Centro de Investigacion, Tecnologia e Innovacion (CITIUS), Universidad de Sevilla, Avda. Reina Mercedes 4b, 41012 Sevilla (Spain); Dpto. Fisica Aplicada II, ETS de Arquitectura, Universidad de Sevilla, Avda. Reina Mercedes 2, 41012 Sevilla (Spain); Hurtado, S. [Servicio de Radioisotopos, Centro de Investigacion, Tecnologia e Innovacion (CITIUS), Universidad de Sevilla, Avda. Reina Mercedes 4b, 41012 Sevilla (Spain); Garcia-Tenorio, R. [Dpto. Fisica Aplicada II, ETS de Arquitectura, Universidad de Sevilla, Avda. Reina Mercedes 2, 41012 Sevilla (Spain)

2012-02-29

Highlights: Black-Right-Pointing-Pointer Polluted sediment and NORM samples. Black-Right-Pointing-Pointer An efficient yet fast process allowing multi-parametric determinations in <3 days. Black-Right-Pointing-Pointer Trace element concentrations, Pb, Th and U isotope ratios with a single instrument. - Abstract: This work focuses on the monitoring of the potential pollution in scenarios that involve NORM-related industrial activities (environmental or in-door scenarios). The objective was to develop a method to determine extent and origin of the contamination, suitable for monitoring (i.e. simple, fast and economical) and avoiding the use of too many different instruments. It is presented a radiochemical method that allows the determination of trace element concentrations and {sup 206}Pb/{sup 207}Pb/{sup 208}Pb, {sup 238}U/{sup 234}U and {sup 232}Th/{sup 230}Th isotope ratios using a single sample aliquot and a single instrument (ICP-QMS). Eichrom UTEVA{sup Registered-Sign} extraction chromatography minicolumns were used to separate uranium and thorium in sample leachates. Independent ICP-MS determinations of uranium and thorium isotope ratios were carried out afterwards. Previously a small aliquot of the leachate was used for the determination of trace element concentrations and lead isotope ratios. Several radiochemical arrangements were tested to get maximum performances and simplicity of the method. The performances of the method were studied in terms of chemical yields of uranium and thorium and removal of the potentially interfering elements. The established method was applied to samples from a chemical industry and sediments collected in a NORM-polluted scenario. The results obtained from our method allowed us to infer not only the extent, but also the sources of the contamination in the area.

A review of the current status of nuclear data for major and minor isotopes of thorium fuel cycle

International Nuclear Information System (INIS)

Ganesan, S.

2000-03-01

In this paper, we present a critical overview of the status of the available nuclear data of isotopes of thorium fuel cycle, viz., 230 Th, 232 Th, 231 Pa, 233 Pa, 232 U, 233 U and 234 U. Induced in the main body of the paper is a critical analysis of information contained in the two basic evaluated nuclear data files JENDL-3.2 and ENDF/B-VI (Rev.5) recently released by the IAEA/NDS as a result of truly international efforts. In some of the cases, the information and data given in EXFOR is examined to get an idea of the status of measured nuclear data of these isotopes. Some comments regarding gaps in experimental data as of 1999 are included in the discussion. Most of these experimental data were those generated two decades ago. In addition, generally, these experimental data are very limited in comparison to the voluminous nuclear data generated for the uranium-plutonium cycle. Experimental data is absent in most of the cases and, in such cases, evaluated cross sections in the two basic evaluated nuclear data files JENDL-3.2 and ENDF/B-VI(Rev.5) are based upon theoretical models and nuclear systematics. Some of these differences between JEF-2.2 and its source ENDF/B-V that were carried over to ENDF/B-VI(Rev.5) are explained. The role and the importance of 231 Pa and 233 Pa in the thorium fuel cycle in advanced concepts such as the Energy Amplifier are mentioned. New calculations of criticality property of 231 Pa and 233 Pa are presented using the neutron reaction data of JENDL-3.2 and ENDF/B-VI(Rev.5). The possible influence of 230 Th is examined with respect to its cross sections and production of 231 Pa in a typical Indian PHWR environment. The quality assurance in design and safety studies in nuclear energy in the next few decades and centuries require new and improved data with high accuracy and energy resolution. As a starter, the nuclear data of the set of isotopes of thorium fuel cycle discussed in this paper is a challenging sample for consideration as a

Uranium, plutonium, and thorium isotopes in the atmosphere and the lithosphere

International Nuclear Information System (INIS)

Essien, I.O.

1983-01-01

Concentration of 238 U in rain and snow collected at Fayetteville (36 0 N, 94 0 W), Arkansas, showed a marked increase during the summer months of 1980, while Mount St. Helens remained active. This observed increase of 238 U can be explained as due to the fallout of natural uranium from the eruption of Mount St. Helens. Large increases in the concentration of thorium isotopes detected in rain and snow samples during the last months of 1982 and early months of 1983 probably originated from the eruption of El Chichon volcano, which occurred on 28 March 1982. About 450 Ci of 232 Th is estimated to have been injected into the atmosphere by this eruption. Isotopic anomalies were observed in atmospheric samples such as rain and snow. These anomalies can be attributed to various natural as well as man-made sources: nuclear weapon tests, nuclear accidents involving the burn-up of nuclear powered satellites, and volcanic eruptions. The variation of 234 U/ 238 U ratios in radioactive minerals when leached with nitric acid were also noticed and this variation, while 235 U/ 238 U remained fairly constant, can be explained in terms of the α-recoil effect and changes in oxidation state of uranium. Difference found in 239 Pu/ 238 U ratios in terrestrial samples and uranium minerals can be explained as due to fallout contamination

Alpha spectrometry and the secondary ion mass spectrometry of thorium

International Nuclear Information System (INIS)

Strisovska, J.; Kuruc, J.; Galanda, D.; Matel, L.; Aranyosiova, M.; Velic, D.

2009-01-01

The main objective of this master thesis was preparation of samples with thorium content on the steel discs by electrodeposition for determination of natural thorium isotope by alpha spectrometry and the secondary ion mass spectrometry and finding out their possible linear correlation between these methods. The samples with electrolytically excluded isotope of 232 Th were prepared by electrodeposition from solution Th(NO 3 ) 4 ·12 H2 O on steel discs in electrodeposition cell with use of solutions Na 2 SO 4 , NaHSO 4 , KOH and (NH 4 ) 2 (C 2 O 4 ) by electric current 0.75 A. Discs were measured by alpha spectrometer. Activity was calculated from the registered impulses for 232 Th and surface's weight. After alpha spectrometry measurements discs were analyzed by TOF-SIMS IV which is installed in the International Laser Centre in Bratislava. Intensities of isotope of 232 Th and ions of ThO + , ThOH + , ThO 2 H + , Th 2 O 4 H + , ThO 2 - , ThO 3 H - , ThH 3 O 3 - and ThN 2 O 5 H - were identified. The linear correlation is between surface's weights of Th and intensities of ions of Th + from SIMS, however the correlation coefficient has relatively low value. We found out with SIMS method that oxidized and hydride forms of thorium are significantly represented in samples with electroplated thorium. (authors)

Introduction and optimization of methods for isotopic determination of thorium and uranium via α-spectroscopy and their applications in analysis of water from Morro do Ferro, Brazil

International Nuclear Information System (INIS)

Vale, M.G.R.

1982-01-01

Methods for isotopic determination of thorium and uranium via α-spectroscopy, using a surface barrier detector, are described. The methods were applied in surface waters, borehole water, sediments and minerals from Morro do Ferro (MG), Brazil. Results and analysis by different techniques are compared and some discussions concerning to Th-concentration levels and anomalous isotopic and nuclidic ratios are presented. (Author) [pt

Extraction of thorium from solution using tribenzylamine

International Nuclear Information System (INIS)

Whitehead, N.E.; Ditchburn, R.G.

1975-01-01

A method is described for isolating thorium from solutions in a state sufficiently pure for alpha spectroscopy. It parallels the method described by Moore and Thern (Radiochemical Radioanalytical Letters 19(2), 117-125, 1974), but uses tribenzylamine instead of Adogen 364. The method involves extracting thorium from a solution in 8M nitric acid, into a 6% w/v solution of tribenzylamine in toluene. The thorium is concentrated in a third, interfacial layer which forms. This layer is isolated, diluted with chloroform, and back extracted with 10M HC1. Overall yields range between 83 and 90% for one extraction. The acidic solution is taken down to near dryness, diluted until the pH is 2 and extracted into 1.2 ml of thenoyltrifluoroacetone in toluene. This solution is evaporated onto a stainless steel disk, flamed, and the disk may be used for alpha spectroscopy of thorium isotopes. (auth.)

Analysis on specific nuclear data for reactors physics computations applied to CANDU reactors using thorium-based fuels

International Nuclear Information System (INIS)

Visan, Iuliana E.

2010-01-01

The purpose of this work is to analyze the evaluated nuclear data from ENDF libraries IAEA69 (69 energy groups library) and IAEA172 (172 energy groups library), respectively, in WIMS library format and to represent neutron fission yield, absorption and fission cross-section dependence for 233 Uranium, 232 Thorium isotopes and some actinides of interest on the incident energy. Our interest for these two isotopes is mainly based on the importance of 233 Uranium as 'fissile nucleus' in Thorium-Uranium fuel cycle. Nowadays, nuclear data evaluation for the actinides generated in Thorium-Uranium fuel cycle is seen as a world-wide priority. The fissile nucleus, 233 Uranium 'plays' the same function in Thorium-Uranium fuel cycle as the 235 Uranium in 'the classic' Uranium-Plutonium fuel cycle. As opposed to natural Uranium which contains 0.7 % of the fissile isotope 235 Uranium, natural Thorium doesn't contain fissile isotopes, being composed entirely by the fertile isotope 232 Thorium. Graphical evolutions of interest parameters versus the incident energy are presented. Our interest was also to observe the behavior of these nuclear data for fast, resonance and thermal energy groups, respectively. The ENDF nuclear data libraries are constantly up-dated, so that we can observe an improvement of the IAEA172 library, which disposes of evaluated nuclear data at higher energies (about 20 MeV), as opposed to IAEA69 library (which includes evaluated nuclear data below 10 MeV). Based on our graphical representation, a good agreement between the considered libraries has been observed, sustaining nuclear data validity. (authors)

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.

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

Thorium valency in molten alkali halides in equilibrium with metallic thorium

International Nuclear Information System (INIS)

Smirnov, M.V.; Kudyakov, V.Ya.

1983-01-01

Metallic thorium is shown to corrode in molten alkali halides even in the absence of external oxidizing agents, alkali cations acting as oxidizing agents. Its corrosion rate grows in the series of alkali chlorides from LiCl to CsCl at constant temperature. Substituting halide anions for one another exerts a smaller influence, the rate rising slightly in going from chlorides to bromides and iodides, having the same alkali cations. Thorium valency is determined coulometrically, the metal being dissolved anodically in molten alkali halides and their mixtures. In fluoride melts it is equal to 4 but in chloride, bromide and iodide ones, as a rule, it has non-integral values between 4 and 2 which diminish as the temperature is raised, as the thorium concentration is lowered, as the radii of alkali cations decrease and those of halide anions increase. The emf of cells Th/N ThHlsub(n) + (1-N) MHl/MHl/C, Hlsub(2(g)) where Hl is Cl, Br or I, M is Li, Na, K, Cs or Na + K, and N < 0.05, is measured as a function of concentration at several temperatures. Expressions are obtained for its concentration dependence. The emf grows in the series of alkali chlorides from LiCl to CsCl, other conditions being equal. (author)

Production of thorium nitrate from uranothorianite ores

International Nuclear Information System (INIS)

Brodsky, M.; Sartorius, R.; Sousseuer, Y.

1959-01-01

The separation of thorium and uranium from uranothorianite ores, either by precipitation or solvent-extraction methods, are discussed, and an industrial process for the manufacture of thorium nitrate is described. Reprint of a paper published in 'Progress in Nuclear Energy' Series III, Vol. 2 - Process Chemistry, 1959, p. 68-76 [fr

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)

Recovery of radiogenic lead-208 from a residue of thorium and rare earths obtained during the operation of a thorium nitrate purification pilot plant

International Nuclear Information System (INIS)

Seneda, Jose Antonio

2006-01-01

Brazil has a long tradition in thorium technology, from mineral dressing (monazite) to the nuclear grade thorium compounds. The estimate reserves are 1200,000. ton of ThO 2 . As a consequence from the work of thorium purification pilot plant at Instituto de Pesquisas Energeticas e Nucleares-CNEN/SP, about 25 ton of a sludge containing thorium and rare earths was accumulated. It comes as a raffinate and washing solutions from thorium solvent extraction. This sludge, a crude hydroxide named RETOTER contains thorium, rare earths and minor impurities including the radiogenic lead-208, with abundance 88.34 %. This work discusses the results of the studies and main parameters for its recovery by anionic ion exchange technique in the hydrochloric system. The isotope abundance of this lead was analyzed by high resolution mass spectrometer (ICPMS) and thermoionic mass spectrometer (TIMS) and the data was used to calculate the thermal neutron capture cross section. The value of s ? o = 14.6 +/- 0.7 mb was found, quite different from the s ? o = 174.2 +/- 7.0 mb measure cross section for the natural lead. Preliminary study for the thorium and rare earths separation and recovery was discussed as well. (author)

Recovery of Ra-223 from natural thorium irradiated by protons

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, Aleksandr N.; Ostapenko, Valentina S. [Lomonosov Moscow State Univ. (Russian Federation); Russian Academy of Sciences, Moscow-Troitsk (Russian Federation). Inst. for Nuclear Research; Lapshina, Elena V.; Ermolaev, Stanislav V.; Zhuikov, Boris L. [Russian Academy of Sciences, Moscow-Troitsk (Russian Federation). Inst. for Nuclear Research; Danilov, Sergey S. [Lomonosov Moscow State Univ. (Russian Federation); Kalmykov, Stepan N. [Lomonosov Moscow State Univ. (Russian Federation); National Research Center ' Kurchatov Institute' (NRC ' Kurchatov Institute' ), Moscow (Russian Federation)

2016-11-01

Irradiation of natural thorium with medium-energy protons is considered to be a prospective approach to large-scale production of {sup 225}Ac and {sup 223}Ra. In addition to the earlier-developed method of {sup 225}Ac isolation, the present work focuses on the simultaneous recovery of {sup 223}Ra from the same thorium target. Radiochemical procedure is based on liquid-liquid extraction, cation exchange and extraction chromatography. The procedure provides separation of radium from spallation and fission products generated in the thorium target. High chemical yield (85-90%) and radionuclide purity of {sup 223}Ra (> 99.8% except {sup 224}Ra and {sup 225}Ra isotopes) have been achieved.

Recovery of radiogenic lead-208 from a residue of thorium and rare earths obtained during the operation of a thorium purification pilot plant

International Nuclear Information System (INIS)

Seneda, Jose Antonio

2006-01-01

Brazil has a long tradition in thorium technology, from mineral dressing (monazite) to the nuclear grade thorium compounds. The estimate reserves are 1200,000. ton of ThO 2 . As a consequence from the work of thorium purification pilot plant at Instituto de Pesquisas Energeticas e Nucleares-CNEN/IPEN-SP, about 25 ton of a sludge containing thorium and rare earths was accumulated. It comes as a raffinate and washing solutions from thorium solvent extraction. This sludge, a crude hydroxide named RETOTER contains thorium, rare earths and minor impurities including the radiogenic lead-208, with abundance 88.34 %. This work discusses the results of the studies and main parameters for its recovery by anionic ion exchange technique in the hydrochloric system. The isotope abundance of this lead was analyzed by high resolution mass spectrometer (ICPMS) and thermoionic mass spectrometer (TIMS) and the data was used to calculate the thermal neutron capture cross section. The value of σγ 0 = 14.6±0.7 mb was found, quite different from the σγ 0 = 174.2 ± 7.0 mb measure cross section for the natural lead. Preliminary study for the thorium and rare earths separation and recovery was discussed as well. (author)

U-series disequilibrium dating of Quaternary carbonates

International Nuclear Information System (INIS)

Stirling, C.

2006-01-01

One of the key dating methods used in paleoclimate research utilizes the natural radioactive decay of uranium to thorium in archives containing U-bearing minerals, such as the calcium carbonate forming the skeletons of fossil corals and speleothems. More specifically, this chronometer, commonly referred to as the U-series dating method, is based on the decay of 238 U to its longest-lived intermediate daughters, 234 U and 230 Th, and subsequent decay through to stable isotopes of Pb. It is the respective 250,000 and 75,000 year half-lives of these daughter isotopes, which make the U-series system particularly useful for dating Quaternary climate events spanning the last 600,000 years of Earth's history. The U-series thus bridges the gap between the ∼45,000 year upper limit of conventional radiocarbon dating and the ∼200,000 year lower limit of K-Ar and 40 Ar- 39 Ar dating. 2 refs., 5 figs

A review on the heterogeneous thorium fuel concept for PWR applications

International Nuclear Information System (INIS)

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

2001-08-01

Seed-blanket unit (SBU) and whole assembly seed and blanket (WASB) are being investigated for the PWR application as well as homogeneous thorium fuel under the US NERI program. For the verification of HELIOS capability for thorium analysis, the characteristics of heterogeneous thorium fuels was evaluated by HELIOS color-set calculation and compared with the calculation results of the US NERI. The infinite multiplication factors from HELIOS calculation are in good agreement with CASMO-4 except for SBU which uses metallic fuel for seed material. The maximum relative difference in power distribution is occurred in WASB case, and is about 5% compared to MCNP. The isotopic concentrations for Am-241, Am-243, and Cm-244 of HELIOS agree well with CASMO-4's, but show a significant discrepancy from MOCUP mainly caused by the old data of cross section and decay constants in ORIGEN. The nonproliferation characteristic of thorium-based fuel such as critical mass, spontaneous fission rate, decay heat generation rate are superior to the conventional uranium fuel. Even though the diversion of U-233 produced in blanket is a technically difficult, the enrichment of uranium isotopes including U-233 is slightly over the limit for safeguard aspects. The urnaium contents in thorium fuel is need to be adjusted in order to meet the safeguard limit. A preliminary assessment of fuel economics was performed based on the uranium utilization and SWU utilization. The natural uranium utilization factors of heterogeneous thorium-based fuel increased by 10δ18%, but the SWU utilization factor decreased by 6-δ11% compared to uranium fuel. The cost of uranium purchase of 50USI/KgU and SWU cost of 110USI/SWU-Kg, recommended by OECD/NEA, gives a comparable economics of thorium-based fuel to uraium fuel. The detailed fuel cycle analysis will take account of the other factors like the variation of uranium purchase cost and SWU cost, fabrication cost of thorium fuel, thorium purchase cost, the capcity

A review on the heterogeneous thorium fuel concept for PWR applications

Energy Technology Data Exchange (ETDEWEB)

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

2001-08-01

Seed-blanket unit (SBU) and whole assembly seed and blanket (WASB) are being investigated for the PWR application as well as homogeneous thorium fuel under the US NERI program. For the verification of HELIOS capability for thorium analysis, the characteristics of heterogeneous thorium fuels was evaluated by HELIOS color-set calculation and compared with the calculation results of the US NERI. The infinite multiplication factors from HELIOS calculation are in good agreement with CASMO-4 except for SBU which uses metallic fuel for seed material. The maximum relative difference in power distribution is occurred in WASB case, and is about 5% compared to MCNP. The isotopic concentrations for Am-241, Am-243, and Cm-244 of HELIOS agree well with CASMO-4's, but show a significant discrepancy from MOCUP mainly caused by the old data of cross section and decay constants in ORIGEN. The nonproliferation characteristic of thorium-based fuel such as critical mass, spontaneous fission rate, decay heat generation rate are superior to the conventional uranium fuel. Even though the diversion of U-233 produced in blanket is a technically difficult, the enrichment of uranium isotopes including U-233 is slightly over the limit for safeguard aspects. The urnaium contents in thorium fuel is need to be adjusted in order to meet the safeguard limit. A preliminary assessment of fuel economics was performed based on the uranium utilization and SWU utilization. The natural uranium utilization factors of heterogeneous thorium-based fuel increased by 10{delta}18%, but the SWU utilization factor decreased by 6-{delta}11% compared to uranium fuel. The cost of uranium purchase of 50USI/KgU and SWU cost of 110USI/SWU-Kg, recommended by OECD/NEA, gives a comparable economics of thorium-based fuel to uraium fuel. The detailed fuel cycle analysis will take account of the other factors like the variation of uranium purchase cost and SWU cost, fabrication cost of thorium fuel, thorium purchase cost

Radiotoxicity Characterization of Multi-Recycled Thorium Fuel - 12394

Energy Technology Data Exchange (ETDEWEB)

Franceschini, F.; Wenner, M. [Westinghouse Electric Company, Cranberry Township, PA (United States); Fiorina, C. [Polytechnic of Milano, Milan (Italy); Paul Sherrer Institute (Switzerland); Huang, M.; Petrovic, B. [Georgia Technology University, Atlanta, GA (United States); Krepel, J. [Paul Sherrer Institute (Switzerland)

2012-07-01

As described in companion papers, Westinghouse is proposing the implementation of a thorium based fuel cycle to burn the transuranic (TRU) contained in the used nuclear fuel. The potential of thorium as a TRU burner is described in another paper presented at this conference. This paper analyzes the long-term impact of thorium on the front-end and backend of the fuel cycle. This is accomplished by an assessment of the isotopic make-up of Th in a closed cycle and its impact on representative metrics, such as radiotoxicity, decay heat and gamma heat. The behavior in both thermal and fast neutron energy ranges has been investigated. Irradiation in a Th fuel PWR has been assumed as representative of the thermal range, while a Th fuel fast reactor (FR) has been employed to characterize the behavior in the high-energy range. A comparison with a U-fuel closed-cycle FR has been undertaken in an attempt of a more comprehensive evaluation of each cycle's long-term potential. As the Th fuel undergoes multiple cycles of irradiation, the isotopic composition of the recycled fuel changes. Minor Th isotopes are produced; U-232 and Pa-231 build up; the U vector gradually shifts towards increasing amounts of U-234, U-235 etc., eventually leading to the production of non negligible amounts of TRU isotopes, especially Pu-238. The impact of the recycled fuel isotopic makeup on the in-core behavior is mild, and for some aspects beneficial, i.e. the reactivity swing during irradiation is reduced as the fertile characteristics of the fuel increase. On the other hand, the front and the back-end of the fuel cycle are negatively affected due to the presence of Th-228 and U-232 and the build-up of higher actinides (Pu-238 etc.). The presence of U-232 can also be seen as advantageous as it represents an obstacle to potential proliferators. Notwithstanding the increase in the short-term radiotoxicity and decay heat in the multi-recycled fuel, the Th closed cycle has some potentially

Evaluation of thorium based nuclear fuel. Chemical aspects

International Nuclear Information System (INIS)

Konings, R.J.M.; Blankenvoorde, P.J.A.M.; Cordfunke, E.H.P.; Bakker, K.

1995-07-01

This report describes the chemical aspects of a thorium-based fuel cycle. It is part of a series devoted to the study of thorium-based fuel as a means to achieve a considerable reduction of the radiotoxicity of the waste from nuclear power production. Therefore special emphasis is placed on fuel (re-)fabrication and fuel reprocessing in the present work. (orig.)

Evaluation of thorium based nuclear fuel. Chemical aspects

Energy Technology Data Exchange (ETDEWEB)

Konings, R.J.M.; Blankenvoorde, P.J.A.M.; Cordfunke, E.H.P.; Bakker, K.

1995-07-01

This report describes the chemical aspects of a thorium-based fuel cycle. It is part of a series devoted to the study of thorium-based fuel as a means to achieve a considerable reduction of the radiotoxicity of the waste from nuclear power production. Therefore special emphasis is placed on fuel (re-)fabrication and fuel reprocessing in the present work. (orig.).

Parametric study of a thorium model

International Nuclear Information System (INIS)

Lourenco, M.C.; Lipsztein, J.L.; Szwarcwald, C.L.

2002-01-01

Models for radionuclides distribution in the human body and dosimetry involve assumptions on the biokinetic behavior of the material among compartments representing organs and tissues in the body. One of the most important problem in biokinetic modeling is the assignment of transfer coefficients and biological half-lives to body compartments. In Brazil there are many areas of high natural radioactivity, where the population is chronically exposed to radionuclides of the thorium series. The uncertainties of the thorium biokinetic model are a major cause of uncertainty in the estimates of the committed dose equivalent of the population living in high background areas. The purpose of this study is to discuss the variability in the thorium activities accumulated in the body compartments in relation to the variations in the transfer coefficients and compartments biological half-lives of a thorium-recycling model for continuous exposure. Multiple regression analysis methods were applied to analyze the results. (author)

Homogeneous Thorium Fuel Cycles in Candu Reactors

Energy Technology Data Exchange (ETDEWEB)

Hyland, B.; Dyck, G.R.; Edwards, G.W.R.; Magill, M. [Chalk River Laboratories, Atomic Energy of Canada Limited (Canada)

2009-06-15

The CANDU{sup R} reactor has an unsurpassed degree of fuel-cycle flexibility, as a consequence of its fuel-channel design, excellent neutron economy, on-power refueling, and simple fuel bundle [1]. These features facilitate the introduction and full exploitation of thorium fuel cycles in Candu reactors in an evolutionary fashion. Because thorium itself does not contain a fissile isotope, neutrons must be provided by adding a fissile material, either within or outside of the thorium-based fuel. Those same Candu features that provide fuel-cycle flexibility also make possible many thorium fuel-cycle options. Various thorium fuel cycles can be categorized by the type and geometry of the added fissile material. The simplest of these fuel cycles are based on homogeneous thorium fuel designs, where the fissile material is mixed uniformly with the fertile thorium. These fuel cycles can be competitive in resource utilization with the best uranium-based fuel cycles, while building up a 'mine' of U-233 in the spent fuel, for possible recycle in thermal reactors. When U-233 is recycled from the spent fuel, thorium-based fuel cycles in Candu reactors can provide substantial improvements in the efficiency of energy production from existing fissile resources. The fissile component driving the initial fuel could be enriched uranium, plutonium, or uranium-233. Many different thorium fuel cycle options have been studied at AECL [2,3]. This paper presents the results of recent homogeneous thorium fuel cycle calculations using plutonium and enriched uranium as driver fuels, with and without U-233 recycle. High and low burnup cases have been investigated for both the once-through and U-233 recycle cases. CANDU{sup R} is a registered trademark of Atomic Energy of Canada Limited (AECL). 1. Boczar, P.G. 'Candu Fuel-Cycle Vision', Presented at IAEA Technical Committee Meeting on 'Fuel Cycle Options for LWRs and HWRs', 1998 April 28 - May 01, also Atomic Energy

Thorium-based nuclear fuel: current status and perspectives

International Nuclear Information System (INIS)

1987-03-01

Until the present time considerable efforts have already been made in the area of fabrication, utilization and reprocessing of Th-based fuels for different types of reactors, namely: by FRG and USA - for HTRs; FRG and Brazil, Italy - for LWRs; India - for HWRs and FBRs. Basic research of thorium fuels and thorium fuel cycles are also being undertaken by Australia, Canada, China, France, FRG, Romania, USSR and other countries. Main emphasis has been given to the utilization of thorium fuels in once-through nuclear fuel cycles, but in some projects closed thorium-uranium or thorium-plutonium fuel cycles are also considered. The purpose of the Technical Committee on the Utilization of Thorium-Based Nuclear Fuel: Current Status and Perspective was to review the world thorium resources, incentives for further exploration, obtained experience in the utilization of Th-based fuels in different types of reactors, basic research, fabrication and reprocessing of Th-based fuels. As a result of the panel discussion the recommendations on future Agency activities and list of major worldwide activities in the area of Th-based fuel were developed. A separate abstract was prepared for each of the 9 papers in this proceedings series

Geochemistry of uranium and thorium series nuclides and of plutonium in the Gulf of Mexico: Final report

International Nuclear Information System (INIS)

Scott, M.R.

1986-01-01

This project focussed on the question of the transport of plutonium by the Mississippi River and the subsequent fate of that material when it entered the ocean. Samples were collected from the Mississippi and its tributaries, and from other rivers spanning a gradation in climate from the arid Rio Grande region to the subtropical Suwannee River. Plutonium analyses of water and of suspended and bottom sediments were complemented with Fe, Mn, Al, CaCO 3 , and organic matter measurements. Analyses of uranium and thorium isotopes, 210 Pb, and 226 Ra were made to serve both as tracers for transport processes, and (for the reactive nuclides) as steady state chemical analogues for plutonium

Possibility of determination of the Galaxy age by the method of uranium - thorium isotopic relations

International Nuclear Information System (INIS)

Lyutostanskij, Yu.S.; Malevannyj, S.V.; Panov, I.V.; Chechetkin, V.M.

1988-01-01

Calculations concerning the formation of heavy elements in an astrophysical fast nuclear process characteristics of the Supernova explosions are carried out in the kinetic model of nucleosynthesis. The age of the Galaxy T G has been calculated making use of the method of uranium-thorium isotopic relations supplemented with the data on 244 Pu abundance in meteorites. T G is shown to be strongly dependent upon the calculation method applied to production of nuclei in r process, upon the data on neutron-rich nuclei and as well upon the external conditions, i.e. the density and temperature in the explosing star. The possibility of nucleosynthesis takes place due to close Supernova explosion, which enriched the chemical content of earth matter with heavy elements is analyzed. The range of allowed values of parameters of the theory of nucleosynthesis is studied

The application of isotopic dating methods for prospection and exploration of nuclear raw material

International Nuclear Information System (INIS)

Komlev, L.V.; Anderson, E.B.

1977-01-01

Among the geological and geochemical methods for prospecting and searching the nuclear raw material, the isotope-dating methods determine the most important search criterion - the time of the ore-forming. The elaboration and use of these methods in uranium-ore regions reveal a series of geochemical epochs of uranium and thorium accumulation connected naturally with the history of geological evolution of the earth crust. The isotope-dating methods enable with confidence to establish the stages of tectono-magmatic activity resulting in the redistribution and the local concentration of uranium. The wide use of isotopic methods is a necessary condition for reasonable trends of the modern geological exploration [ru

Thematic network on the analysis of thorium and its isotopes in workplace materials. Interim report on current research activity and future research needs

International Nuclear Information System (INIS)

Howe, A.; Rosen, P.; White, M.

1999-12-01

The task of Work Package 1 (WP 1) of the EC Thematic Network 'The analysis of thorium and its isotopes in workplace materials' was to prepare an 'Inventory of current research activities in participating member states concerning thorium analysis in the workplace and environment'. The specific objective of WP 1 was 'to identify common research areas and co-ordinate activity for better management of resources'. This was to be achieved by carrying out a survey of network and national laboratories to establish the extent of current and proposed research activity in the field, evaluation of survey by network members, and production of a report containing results and conclusions. A preliminary literature review revealed that the majority of thorium analysis is carried out by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) or a radiochemical technique, alpha counting and neutron activation being the most popular. In many instances there is a preconcentration or separation step, which usually involves an ion exchange column to isolate the thorium and remove the majority of the matrix. Papers concerned with the application of ICP-MS were found to feature prominently amongst recent publications, which is not surprising, as the technique is fairly newly established. Thorium was most commonly measured in geological matrixes, including soil and ores. On the basis of the results of the literature review and survey of research activity, the Network identified two key areas of priority for further research: sample preparation methods for thorium analysis; and traceable standards and certified reference materials for thorium analysis. The Network considered how best to distribute the results to interested parties to facilitate links between laboratories with common research areas, and decided that: at this stage, the findings should simply be published in the form of this interim report, which is freely available to all interested parties; the Network should continue to

U-series isotopes in arc magma

Energy Technology Data Exchange (ETDEWEB)

Hawkesworth, C.; Turner, S.; McDermott, F.; Peate, D.; Van Calsteren, P.

1997-12-31

Thorium is not readily mobilized in the fluid component along destructive plate margins. Uranium is mobilized, and the resultant fractionation in U/Th can be used to estimate the rates of transfer slab derived components through the mantle wedge. The variations in Th/Yb, and by implication in the fractionation-corrected Th abundances of arc magmas largely depend on the contributions from subducted sediments. It is inferred that the distinctive high Th/Ta ratios of subduction related magmas primarily reflect the Th/Ta ratios of the subducted sediments, and that such high Th/Ta ratios are generated by processes other than those associated with recent subduction-related magmatism. Uranium and thorium isotopes have also been used to evaluate magma residence times within the crust. Thus, separated minerals and groundmass from six rocks erupted in the last 4,000 years from Soufriere on St. Vincent in the Lesser Antilles, scatter about a 50,000 year errorchron on the U-Th equiline diagram (Heath et al., 1977). Models are currently being developed to investigate how such apparent ages may relate to calculated replenishment times in steady state systems. Bulk continental crust has a lower U/Th ratio (0.25) than at least some estimates for the bulk Earth (0.26) and the depleted upper mantle (0.39). However, the island arc rocks with low U/Th ratios appear to have inherited those from subducted sediments, and arc rocks with a low sediment contribution have significantly higher U/Th. Consequently, the U/Th ratios of new crustal material generated along destructive plate margins are significantly higher than those of bulk continental crust. The low average U/Th of bulk crust may be primarily due to different crust generation processes in the Archaean, when U would be less mobile because conditions were less oxidising, and when residual garnet may have had more of a role in crust generation processes. Extended abstract. 4 figs., 23 refs.

Determination of thorium and uranium particles in monazite airborne

International Nuclear Information System (INIS)

Cunha, K.M. de A.D. da

1988-01-01

The work is the determination of the Mass Median Aerodynamic Diameter of Airborne particles of Th and U, produced during the milling of monazite in Monozite Sand Plants. The air samples was collected using a Cascade Impactor from Delron DCI-6 with a flux of 12,5 1/min and cut-off diametes of 0,5, 1,0, 4,0, 8,0 and 16,0 μm. Each stage of the cascate impactor was analysed by measuring the X rays induced in collision with 2 MeV protons acellereted by a 4 MV Van de Graaff acceletor located at University Catolic, PUC, RJ. The MMAD found for Th and U was of 1,15 μm with a geometric standard desviation of 2,0. Take in acount that there are more thorium than uranium in the brazilian monazite, and the 232 Th 238 U are thr principal isotopes at the Th and U natural radioative decay series, we considered the mass and the activity distribution as equal. The mean concentration of Th (17,0 Bq/m 3 ) record in the air was 42% above 3/10 of international limit for concentration of oxides of thorium in the air, while the concentration of U remaind below 1/10 of the limit for concentration of U 3 O 8 in the air. (author) [pt

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

Operation of CANDU power reactor in thorium self-sufficient fuel cycle

Indian Academy of Sciences (India)

These disadvantages of thorium fuel cycle were seemingly the reasons why that ... According to the data of figure 2, maximum (equilibrium) content of 233U in ..... Self-sufficient mode is related with rather big effort in the extraction of isotopes of.

Determination of traces of thorium in ammonium/sodium diuranate by ICP-AES method

International Nuclear Information System (INIS)

Nair, V.R.; Kartha, K.N.M.

1999-01-01

Full text: Indian Rare Earths Ltd., Alwaye, produces ammonium diuranate from the thorium concentrate, obtained during monazite processing. This process involves a series of steps. The final uranium product obtained always contains microgram amounts of thorium as impurity. An analytical procedure has been standardised for the estimation of microgram amounts of thorium in ammonium/sodium diuranate. The method involves solvent extraction of uranium by using a tertiary amine followed by the determination of thorium by ICP-AES method in the raffinate. The recoveries of thorium were checked by standard addition to the uranium matrix. Limit of detection is adequate for the analysis of nuclear grade material

The Thorium-Cycle: safe, abundant power for the new millennium

Science.gov (United States)

Don, May; George, Kim; Peter, Mcintyre; Charles, Meitzler; Robert, Rogers; Akhdior, Sattarov; Mustafa, Yavuz

2001-10-01

A design has been developed for using accelerator-driven thorium fission to produce electric power. A thorium-cycle reactor works by electro-breeding. A pattern of thorium fuel rods is supported in a vessel containing molten lead. A beam of high-energy (1 GeV) protons is targeted in the center of the vessel, and produces a copious flux of energetic neutrons by spallation. The neutrons transmute the thorium nuclei two steps up the periodic table to U233, which fissions rapidly to produce thermal energy. The lead serves as the spallation target, the moderator, and the heat exchange medium to transfer heat from the core to steam exchangers above the core. The thorium cycle has several important advantages over current uranium-cycle fission technology: it is intrinsically stable it cannot melt down; it eats its own waste; it cannot produce bomb-grade isotopes; and there are sufficient thorium reserves to supply the entire Earth’s energy economy for the next millennium. The concept of a thorium-cycle power reactor was first proposed by Rubbia in 1995. Key problems in the original concept were the proton injector (15 MW beam power), reliability of accelerator systems, and parasitic absorption of neutrons by fission products during the life of the core. We have addressed all three problems in a design for a flux-coupled stack of isochronous cyclotrons, delivering a pattern of 7 independent beams to the core. An interdisciplinary collaboration is being formed to develop the concept to a serious design.

Verification study of thorium cross section in MVP calculation of thorium based fuel core using experimental data

International Nuclear Information System (INIS)

Mai, V. T.; Fujii, T.; Wada, K.; Kitada, T.; Takaki, N.; Yamaguchi, A.; Watanabe, H.; Unesaki, H.

2012-01-01

Considering the importance of thorium data and concerning about the accuracy of Th-232 cross section library, a series of experiments of thorium critical core carried out at KUCA facility of Kyoto Univ. Research Reactor Inst. have been analyzed. The core was composed of pure thorium plates and 93% enriched uranium plates, solid polyethylene moderator with hydro to U-235 ratio of 140 and Th-232 to U-235 ratio of 15.2. Calculations of the effective multiplication factor, control rod worth, reactivity worth of Th plates have been conducted by MVP code using JENDL-4.0 library [1]. At the experiment site, after achieving the critical state with 51 fuel rods inserted inside the reactor, the measurements of the reactivity worth of control rod and thorium sample are carried out. By comparing with the experimental data, the calculation overestimates the effective multiplication factor about 0.90%. Reactivity worth of the control rods evaluation using MVP is acceptable with the maximum discrepancy about the statistical error of the measured data. The calculated results agree to the measurement ones within the difference range of 3.1% for the reactivity worth of one Th plate. From this investigation, further experiments and research on Th-232 cross section library need to be conducted to provide more reliable data for thorium based fuel core design and safety calculation. (authors)

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

The evolutionary adoption of thorium beginning with its application in niche LWR fuels

International Nuclear Information System (INIS)

Drera, Saleem

2015-01-01

Since the inception of nuclear energy, the use of thorium as a nuclear fuel has been envisioned. Thorium boasts benefits, however, drawbacks which are both economic and technical including its the lack of a naturally occurring fissile isotope implies that its utility is inherently more difficult. The implementation of thorium as a nuclear fuel requires that it must provide sound technical advantages in combination with attractive economics as compared to standard uranium fuel. Revolutionary thorium concepts such as molten salt reactors and accelerator driven systems may provide theoretical merit, however, their exotic nature and associated technical challenges label them as long-term solutions at best. A near-to-medium term solution for thorium must be based on an evolutionary approach utilizing light/heavy water reactor platforms. While thorium does not provide a near-to-medium term complete replacement of uranium, it does provide substantial benefit within niche applications. To license and bring to market these niche fuels, Thor Energy and an international consortium of entities (including: Fortum, KAERI, Westinghouse, NNL, ITU, IFE, and a few other minor entities) have initiated a fuel development and irradiation test program to characterize the performance of these thoria-containing fuels. (author)

Neutronic and Isotopic Simulation of a Thorium-TRU's fuel Closed Cycle in a Lead Cooled ADS

International Nuclear Information System (INIS)

Garcia-Sanz, J. M.; Embid, M.; Fernandez, R.; Gonzalez, E. M.; Perez-Parra, A.

2000-01-01

The FACET group at CIEMAT is studying the properties and potentialities of several lead-cooled ADS designs for actinide and fission product transmutation. The main characteristics of these systems are the use of lead as primary coolant and moderator and fuels made by transuranics inside a thorium oxide matrix. The strategy assumed in this simulation implies that every discharge of the ADS will be reprocessed and would produce four waste streams: fission and activation products, remaining ''232 Th, produced ''233 U and remaining TRU's. The ''233 U is separated for other purposes; the remaining TRU are recovered altogether and mixed with the adequate amount of ''232 Th and fresh TRUs coming from LWR spent fuel. The simulations performed in this study have been focused primarily in the evolution of the fuel isotopic composition during and after each ADS burn-up cycle. (Author) 10 refs

The comparative distribution of thorium and plutonium in human tissues

International Nuclear Information System (INIS)

Singh, Narayani P.; Shawki Amin Ibrahim; Cohen, Norman; Wrenn, McDonald E.

1978-01-01

Thorium is the most chemically and biologically similar natural element to the manmade element plutonium. Both are actinides, and for both the most stable valency state is +4, and solubility in natural body fluids is low. They are classified together in ICRP Lung Model. The present paper deals with the question of whether or not the analogy between the two actinides in terms of deposition and retention in human tissues is a good one. Preliminary results on the thorium contents ( 228,230 Th and 232 Th) of three sets of human tissues from a western U.S. town containing a uranium tailings pile are compared with the reported values of plutonium content of human tissues from the general populations who are exposed to environmental plutonium from fallout of nuclear detonations. Samples were taken at autopsy where sudden death had occurred. For the three isotopes of thorium, the ratio of the content of each (pCi/organ, normalized by organ weight to ICRP Reference Man) in lung to lymph nodes varies from 2-25 for individuals with a mean of 8; this is similar to that we infer from the literature for 239 , 240 Pu which suggests a ratio of lung to lymph nodes with a mean of approximately 7. However, the relative thorium contents of lung and liver are dissimilar, lung/liver for thorium being 3.5 and for plutonium 0.2 to 0.1. Similarly, the ratios of thorium and plutonium content of liver and bone vary significantly; the ratio for thorium is 0.1 and for plutonium 0.8 to 0.5. The most significant observation at this stage is that the relative accumulation of thorium in human liver is much less than that of plutonium. Some of the plausible reasons will be discussed. (author)

Breeding and plutonium characterization analysis on actinides closed water-cooled thorium reactor

International Nuclear Information System (INIS)

Permana, Sidik; Sekimoto, Hiroshi; Takaki, Naoyuki

2009-01-01

Higher difficulties (barrier) or more complex design of nuclear weapon, material fabrication and handling and isotopic enrichment can be achieved by a higher isotopic barrier. The isotopic material barrier includes critical mass, heat-generation rate, spontaneous neutron generation and radiation. Those isotopic barriers in case of plutonium isotope is strongly depend on the even mass number of plutonium isotope such as 238 Pu, 240 Pu and 242 Pu and for 233 U of thorium cycle depends on 232 U. In this present study, fuel sustainability as fuel breeding capability and plutonium characterization as main focus of proliferation resistance analysis have been analyzed. Minor actinide (MA) is used as doping material to be loaded into the reactors with thorium fuel. Basic design parameters are based on actinide closed-cycle reactor cooled by heavy water. The evaluation use equilibrium burnup analysis coupled with cell calculation of SRAC and nuclear data library is JENDL.32. Parametrical survey has been done to analyze the effect of MA doping rate, different moderation ratio for several equilibrium burnup cases. Plutonium characterization which based on plutonium isotope composition is strongly depending on MA doping concentration and different moderation conditions. Breeding condition can be achieved and high proliferation resistance level can be obtained by the present reactor systems. Higher isotopic plutonium composition of Pu-238 (more than 40%) can be obtained compared with other plutonium isotopes. In addition, higher moderation ratio gives the isotope composition of 238 Pu increases, however, it obtains lower composition when MA doping is increased and it slightly lower composition for higher burnup. Meanwhile, higher 240 Pu composition can be achieved by higher MA doping rate as well as for obtaining higher breeding capability. (author)

Thorium cycles and proliferation

International Nuclear Information System (INIS)

Lovins, A.B.

1979-01-01

This paper analyzes several prevalent misconceptions about nuclear fuel cycles that breed fissile uranium-233 from thorium. Its main conclusions are: U-233, despite the gamma radioactivity of associated isotopes, is a rather attractive material for making fission bombs, and is a credible material for subnational as well as national groups to use for this purpose; (2) pure thorium cycles, which in effect merely substitute U-233 for Pu, would take many decades and much U to establish, and offer no significant safeguards advantage over Pu, cycles; (3) denatured Th-U cycles, which dilute the U-233 with inert U-238 to a level not directly usable in bombs, are not an effective safeguard even against subnational bomb-making; (4) several other features of mixed Th-U cycles are rather unattractive from a safeguards point of view; (5) thus, Th cycles of any kind are not a technical fix for proliferation (national or subnational) and, though probably more safeguardable than Pu cycles, are less so than once-through U cycles that entail no reprocessing; (6) while thorium cycles have some potential technical advantages, including flexibility, they cannot provide major savings in nuclear fuel resources compared to simpler ways of saving neutrons and U; and (7) while advocates of nuclear power may find Th cycles worth exploring, such cycles do not differ fundamentally from U cycles in any of the respects--including safeguards and fuel resources--that are relevant to the broader nuclear debate, and should not be euphorically embraced as if they did

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

Analysis of burnup of Angra 2 PWR nuclear with addition of thorium dioxide fuel using ORIGEN-ARP

Energy Technology Data Exchange (ETDEWEB)

Goncalves, Isadora C.; Wichrowski, Caio C.; Oliveira, Claudio L. de; Vellozo, Sergio O.; Baptista, Camila O., E-mail: isadora.goncalves@ime.eb.br, E-mail: wichrowski@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). Secao de Engenharia Nuclear

2017-11-01

It is known that isotope {sup 232}thorium is a fertile nuclide with the ability to convert into {sup 233}uranium, a potentially fissile isotope, after absorbing a neutron. As there is a large stock of available thorium in the world, this element shows great promise in mitigate the world energy crisis, more particularly in the problem of uranium scarcity, besides being an alternative nuclear fuel for those currently used in reactors, and yet presenting advantages as an option for the non-proliferation movement, among others. In this study, the analysis of the remaining nuclides of burnup was carried out for the core configuration of a PWR (pressurized water reactor) reactor, specifically the Angra 2 reactor, using only uranium dioxide, its current configuration, and in different configurations including a mixed oxide of uranium and thorium in three concentrations, allowing a preliminary assessment of the feasibility of the modification of the fuel, the resulting production of {sup 233}uranium, the emergence of {sup 231}protactinium (an isotope that only occurs as a fission product of {sup 232}Th) resulting from burning. The study was carried out using data obtained from FSAR (Final Safety Analysis Report) of Angra 2, using the SCALE 6.1, a modeling and simulation nuclear code, especially its ORIGEN-ARP module, which analyzes the depletion of isotopes presents in a reactor. (author)

Analysis of burnup of Angra 2 PWR nuclear with addition of thorium dioxide fuel using ORIGEN-ARP

International Nuclear Information System (INIS)

Goncalves, Isadora C.; Wichrowski, Caio C.; Oliveira, Claudio L. de; Vellozo, Sergio O.; Baptista, Camila O.

2017-01-01

It is known that isotope "2"3"2thorium is a fertile nuclide with the ability to convert into "2"3"3uranium, a potentially fissile isotope, after absorbing a neutron. As there is a large stock of available thorium in the world, this element shows great promise in mitigate the world energy crisis, more particularly in the problem of uranium scarcity, besides being an alternative nuclear fuel for those currently used in reactors, and yet presenting advantages as an option for the non-proliferation movement, among others. In this study, the analysis of the remaining nuclides of burnup was carried out for the core configuration of a PWR (pressurized water reactor) reactor, specifically the Angra 2 reactor, using only uranium dioxide, its current configuration, and in different configurations including a mixed oxide of uranium and thorium in three concentrations, allowing a preliminary assessment of the feasibility of the modification of the fuel, the resulting production of "2"3"3uranium, the emergence of "2"3"1protactinium (an isotope that only occurs as a fission product of "2"3"2Th) resulting from burning. The study was carried out using data obtained from FSAR (Final Safety Analysis Report) of Angra 2, using the SCALE 6.1, a modeling and simulation nuclear code, especially its ORIGEN-ARP module, which analyzes the depletion of isotopes presents in a reactor. (author)

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)

Recovering of thorium contained in wastes from Thorium Purification Plant

International Nuclear Information System (INIS)

Brandao Filho, D.; Hespanhol, E.C.B.; Baba, S.; Miranda, L.E.T.; Araujo, J.A. de.

1992-08-01

A study has been developed in order to establish a chemical process for recovering thorium from wastes produced at the Thorium Purification Plant of the Instituto de Pesquisas Energeticas e Nucleares. The recovery of thorium in this process will be made by means of solvent extraction technique. Solutions of TBP/Varsol were employed as extracting agent during the runs. The influence of thorium concentration in the solution, aqueous phase acidity, volume ratio of the phases, percentage of TBP/Varsol and the contact time of the phases on the extraction of thorium and lanthanides was determined. (author)

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

A fertile material, plentiful in nature. The thorium sector, energy for the next millenniums

International Nuclear Information System (INIS)

Perrier, Raymond

2014-01-01

Thorium exhibits very interesting properties. It is weakly radioactive, mainly emits weakly penetrating alpha radiations, produces 70 times more energy than uranium, is between three and four times more plentiful than uranium, and is consumed at 99 per cent in reactors whereas uranium is consumed at 1 per cent. This article first discusses the future of the uranium sector, and then presents the properties of thorium. It discusses ore types and the characteristics of the different types of deposits. It evokes world reserves and indicates the different types of nuclear reactors and the main isotopes they use. It describes the uranium sector related to nuclear reactors. It presents the principle of a thorium-fuelled nuclear reactor, recalls experiments performed since the 1950's in different countries (USA, Germany, India, so on) as well as the existence of some commercial reactors using thorium. It evokes more recent projects: proton accelerator reactors, molten salt reactors. It outlines the benefits and drawbacks of this last reactor type, and that Europe is late in the development of thorium-fuelled reactors with respect to China, USA and India

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)

Radon in air concentrations arising from storage of articles containing radium or thorium

International Nuclear Information System (INIS)

Slater, M.; Gooding, M.

2006-01-01

A major component of public and occupational radiation exposure worldwide arises from the inhalation of radon and thoron gases, produced during the decay of naturally occurring uranium and thorium respectively. Whilst radon and thoron exposures are normally associated with the natural environment, there may also be a risk associated with sources, manufactured articles and waste produced through refining and concentration of naturally occurring radioactive material. Sources and articles manufactured from refined uranium do not normally give rise to the release of radon as the uranium progeny are largely removed during production and, if removed, will take thousands of years to reach full equilibrium with the uranium parent isotopes. Exposure to radon -222 ( 222 Rn) may, however, arise in areas where the uranium-238 ( 238 U) daughter radium-226 ( 226 Ra) is concentrated, for example in the form of sources, luminous articles or low-specific activity (LSA) scale. Exposure to radon- 220 ( 220 Rn), otherwise known as thoron, may occur in areas where thorium isotopes are concentrated, for example as manufactured laboratory thorium compounds. This paper explores the issues affecting radon and thoron release from manufactured articles containing uranium and thorium and their progeny. A methodology is provided for the calculation of 222 Rn and 220 Rn in air concentrations likely to arise as a result of the storage and use of articles containing radium-226 ( 226 Ra) or thorium-232 ( 232 Th). The methodology provided in the document allows derivation of the equilibrium equivalent radon concentration and the radon exposure rate in circumstances where the ventilation rate and volume of the facility can be reliably estimated and the quantities of 226 Ra or 232 Th held are known. A critical variable in the calculation is the release fraction (i.e. the proportion of radon generated that is release to atmosphere), and this paper considers methods for estimating this parameter

Development of simple and rapid radioactivity analysis for thorium series in the products containing naturally occurring radioactive materials (NORM)

Energy Technology Data Exchange (ETDEWEB)

Yoo, Jae Ryong; Park, Se Young; Yoon, Seok Won; Ha, Wi Ho [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Lee, Jae Kook; Kim, Kwang Pyo [Kyung Hee University, Seoul (Korea, Republic of)

2016-05-15

It is necessary to analyze radioactivity of naturally occurring radioactive materials (NORM) in products to ensure radiological safety required by Natural Radiation Safety Management Act. The pretreatments for the existing analysis methods require high technology and time. Such destructive pretreatments including grinding and dissolution of samples make impossible to reuse products. We developed a rapid and simple procedure of radioactivity analysis for thorium series in the products containing NORM. The developed method requires non-destructive or minimized pretreatment. Radioactivity of the product without pretreatment is initially measured using gamma spectroscopy and then the measured radioactivity is adjusted by considering material composition, mass density, and geometrical shape of the product. The radioactivity adjustment can be made using scaling factors, which is derived by radiation transport Monte Carlo simulation. Necklace, bracelet, male health care product, and tile for health mat were selected as representative products for this study. The products are commonly used by the public and directly contacted with human body and thus resulting in high radiation exposure to the user. The scaling factors were derived using MCNPX code and the values ranged from 0.31 to 0.47. If radioactivity of the products is measured without pretreatment, the thorium series may be overestimated by up to 2.8 times. If scaling factors are applied, the difference in radioactivity estimates are reduced to 3-24%. The developed procedure in this study can be used for other products with various materials and shapes and thus ensuring radiological safety.

Studies on the preparation of thorium metal sponge from thorium oxalate

International Nuclear Information System (INIS)

Vijay, P.L.; Sehra, J.C.; Sundaram, C.V.; Gurumurthy, K.R.; Raghavan, R.V.

1978-01-01

The results of investigations carried out on the production of high purity thorium metal sponge, starting with thorium oxalate are presented. The flow sheet includes chlorination of thorium oxalate, purification of raw thorium tetrachloride, magnesium reduction of anhydrous thorium tetrachloride, slag metal separation, vacuum distillation for removal of residual MgCl 2 and excess magnesium, and consolidation of the metal sponge. Studies have been carried out to investigate the optimum chlorination efficiency and chlorine utilization attainable using different chlorinating agents, and to compare the quality of the sponge obtained with single and double distilled chloride. The overall process efficiency under optimum conditions was 81%. The thorium metal button, prepared from the sponge by arc-melting, analysed : O 2 - 847, N 2 - 20, C - 179, Mg - 100, Fe - 49, Ni<50, Al - 11, Cr - 7 (expressed in parts per million parts of thorium). The button could be further purified by electron beam melting to improve its ductility. (author)

Sr and Nd isotope geochemistry of coexisting alkaline magma series, Cantal, Massif Central, France

International Nuclear Information System (INIS)

Downes, H.

1984-01-01

Sr and Nd isotope analyses are presented for Tertiary continental alkaline volcanics from Cantal, Massif Central, France. The volcanics belong to two main magma series, silica-saturated and silica-undersaturated (with rare nephelinites). Trace element and isotopic data indicate a common source for the basic parental magmas of both major series; the nephelinites in contrast must have been derived from a mantle source which is isotopically and chemically distinct from that which gave rise to the basalts and basanites. 87 Sr/ 86 Sr initial ratios range from 0.7034 to 0.7056 in the main magma series (excluding rhyolites) and 143 Nd/ 144 Nd ratios vary between 0.512927 and 0.512669; both are correlated with increasing SiO 2 in the lavas. The data can be explained by a model of crustal contamination linked with fractional crystallisation. This indicates that crustal magma chambers are the sites of differentiation since only rarely do evolved magmas not show a crustal isotopic signature and conversely basic magmas have primitive isotopic ratios unless they contain obviuos crustal-derived xenocrysts. Potential contaminants include lower crustal granulites or partial melts of upper crustal units. Equal amounts of contamination are required for both magma series, refuting hypotheses of selective contamination of the silica-saturated series. The isotopic characteristics of the apparently primary nephelinite lavas demonstrates widespread heterogeneity in the mantle beneath Cantal. Some rhyolites, previously thought to be extremely contaminated or to be crustally derived, are shown to have undergone post-emplacement hydrothermal alteration. (orig.)

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

Thorium fuel cycle management

International Nuclear Information System (INIS)

Zajac, R.; Darilek, P.; Breza, J.; Necas, V.

2010-01-01

In this presentation author deals with the thorium fuel cycle management. Description of the thorium fuels and thorium fuel cycle benefits and challenges as well as thorium fuel calculations performed by the computer code HELIOS are presented.

Evaluation of Solid Geologic Reference Materials for Uranium-Series Measurements via LA-ICPMS

Science.gov (United States)

Matthews, K. A.; Goldstein, S. J.; Norman, D. E.; Nunn, A. J.; Murrell, M. T.

2008-12-01

Uranium-series geochemistry and geochronology have a wide range of applications in paleoclimatology, volcanology and other disciplines. To further explore these fields, the geoanalytical community has now begun to exploit recent advances in in situ, micron-scale sampling via laser ablation-ICPMS. Unfortunately, improvements in instrumentation have generally outpaced development of the appropriate geologic reference materials required for in situ U-series work. We will report results for uranium and thorium isotopic ratios and elemental concentrations measured in a suite of solid standards from the USGS (e.g., BCR-2G, BHVO-2G, GSD-1G, MACS-1, NKT-2G), as well as those from the MPI-DING series (e.g., ATHO-G, T1-G, StHs6/80-G). Specifically created for microanalysis, two of these standards are synthetic (GSD-1G, MACS-1) and the remainder are naturally-sourced glasses. They cover a range of compositions, ages (± secular equilibrium), elemental concentrations and expected isotopic ratios. The U-series isotopics of some powdered source materials have been characterized (e.g., BCR-2, BHVO-2), although there is no confirmation of the same ratios in the glass. Bulk measurement of these solid standards via TIMS and solution multicollector-ICPMS can then be used to assess the performance of LA-ICPMS techniques which require matrix-matched solid standards for correction of U-series elemental and isotopic ratios. These results from existing, widely-available reference materials will also facilitate quantification and comparison of U-series data among laboratories in the broader geoscience community.

Thorium-230 dating of thermal waters in the vicinity of the Nevada Test Site

International Nuclear Information System (INIS)

Holloway, R.W.; Carilli, J.T.; Faller, S.H.; Liu, C.K.; Kuroda, P.K.

1989-01-01

Radiochemical measurements of the concentrations of thorium and uranium isotopes were carried out for a total of 10 samples of hot springs, mineral springs, and lakes collected in the vicinity of the Nevada Test Site. The uranium-to-thorium ratios in the water samples were found to be generally much greater than those in soils and in rain water. The apparent (230)Th ages calculated from the (230)Th/(232)Th and (234)U/(238)U ratios for most of these water samples were less than 100 years

Virginia ADS consortium - thorium utilization

International Nuclear Information System (INIS)

Myneni, Ganapati

2015-01-01

A Virginia ADS consortium, consisting of Virginia Universities (UVa, VCU, VT), Industry (Casting Analysis Corporation, GEM*STAR, MuPlus Inc.), Jefferson Lab and not-for-profit ISOHIM, has been organizing International Accelerator-Driven Sub-Critical Systems (ADS) and Thorium Utilization (ThU) workshops. The third workshop of this series was hosted by VCU in Richmond, Virginia, USA Oct 2014 with CBMM and IAEA sponsorship and was endorsed by International Thorium Energy Committee (IThEC), Geneva and Virginia Nuclear Energy Consortium Authority. In this presentation a brief summary of the successful 3 rd International ADS and ThU workshop proceedings and review the worldwide ADS plans and/or programs is given. Additionally, a report on new start-ups on Molten Salt Reactor (MSR) systems is presented. Further, a discussion on potential simplistic fertile 232 Th to fissile 233 U conversion is made

Potential of thorium-based fuel cycle for PWR core to reduce plutonium and long-term toxicity

Energy Technology Data Exchange (ETDEWEB)

Joo, Hyung Kook; Kim, Taek Kyum; Kim, Young Jin [Korea Atomic Energy Research Institute, Taejon (Korea)

1999-01-01

The cross section libraries and calculation methods of the participants were inter-compared through the first stage benchmark calculation. The multiplication factor of unit cell benchmark are in good agreement, but there is significant discrepancies of 2.3 to 3.5 %k at BOC and at EOC between the calculated infinite multiplication factors of each participants for the assembly benchmark. Our results with HELIOS show a reasonable agreement with the others except the MTC value at EOC. To verify the potential of the thorium-based fuel to consume the plutonium and to reduce the radioactivity from the spent fuel, the conceptual core with ThO{sub 2}-PuO{sub 2} or MOX fuel were constructed. The composition and quantity of plutonium isotopes and the radioactivity level of spent fuel for conceptual cores were analyzed, and the neutronic characteristics of conceptual cores were also calculated. The nuclear characteristics for ThO{sub 2}-PuO{sub 2} thorium fueled core was similar to MOX fueled core, mainly due to the same seed fuel material, plutonium. For the capability of plutonium consumption, ThO{sub 2}-PuO{sub 2} thorium fuel can consume plutonium 2.1-2.4 times MOX fuel. The fraction of fissile plutonium in the spent ThO{sub 2}-PuO{sub 2} thorium fuel is more favorable in view of plutonium consumption and non-proliferation than MOX fuel. The radioactivity of spent ThO{sub 2}-PuO{sub 2} thorium and MOX fuel batches were calculated. Since plutonium isotopes are dominant for the long-term radioactivity, ThO{sub 2}-PuO{sub 2} thorium has almost the same level of radioactivity as in MOX fuel for a long-term perspective. (author). 22 figs., 11 tabs.

Determination of natural thorium in urines; Dosage du thorium dans les urines

Energy Technology Data Exchange (ETDEWEB)

Jeanmaire, L; Jammet, H [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

A procedure for the quantitative analysis of thorium in urine is described. After precipitation with ammonium hydroxide, dissolution of the precipitate, extraction at pH 4-4.2 with cupferron in chloroformic solution and mineralization, a colorimetric determination of thorium with thorin is performed. It is thus possible to detect about 2 {gamma} of thorium in the sample. (author) [French] Cet article decrit une technique de dosage du thorium dans l'urine. Apres precipitation par l'ammoniaque, remise en solution, extraction a pH 4-4,2 par le cupferron en solution chloroformique et mineralisation, le thorium est dose par colorimetrie avec le thorin. Cette methode permet de deceler environ 2 {gamma} de thorium dans l'echantillon. (auteur)

Feasibility study and economic analysis on thorium utilization in heavy water reactors

International Nuclear Information System (INIS)

1978-07-01

Even though natural uranium is a more easily usable fuel in heavy water reactors, thorium fuel cycles have also been considered owing to certain attractive features of the thorium fuel cycle in heavy water reactors. The relatively higher fission neutron yield per thermal neutron absorption in 233 U combined with the very low neutron absorption cross section of heavy water make it possible to achieve breeding in a heavy water reactor operating on Th- 233 U fuel cycle. Even if the breeding ratio is very low, once a self-sustaining cycle is achieved, thereafter dependence on uranium can be completely eliminated. Thus, with a self-sustaining Th- 233 U fuel cycle in heavy water reactors, a given quantity of natural uranium will be capable of supporting a much larger installed generating capacity to significantly longer period of time. However, since thorium does not contain any fissile isotope, fissile material has to be added at the beginning. Concentrated fissile material is considerably more expensive than the 235 U contained in natural uranium. This makes the fuel cycle cost higher with thorium fuel cycle, at least during the initial stages. The situation is made worse by the fact that, because of its higher thermal neutron absorption cross section, thorium requires a higher concentration of fissile material than 238 U. Nevertheless, because of the superior nuclear characteristics of 233 U, once uranium becomes more expensive, thorium fuel cycle in heavy water reactors may become economically acceptable. Furthermore, the energy that can be made available from a given quantity of uranium is considerably increased with a self-sustaining thorium fuel cycle

Assessment of thorium and thoron decay products in air - thorium plant

International Nuclear Information System (INIS)

Dhandayutham, R.; Gohel, C.O.; Shetty, P.N.; Savant, P.B.; Rao, D.V.V.

1977-01-01

For the evaluation of radiation dose to the lungs in a thorium plant, it is necessary to estimate the concentration of thorium, thoron and its daughter products in air. Methods employed in estimating thorium and its decay products and 'working level' are presented. (M.G.B.)

Utilization of BSS-Safety Series 115 in facilities for mining ore with uranium and thorium associated to it

International Nuclear Information System (INIS)

Matta, Luiz Ernesto S. de C.; Ferreira, Paulo R. Rocha; Mouco, Charles D. do C.L.

1999-01-01

During the year of 1995, the Brazilian Nuclear Energy Commission, started a investigation program called Mining Project. The main objective of this program was to create a integrated study of environmental and occupational conditions of mining ores with uranium and thorium associated to it. Several technical visits were done at four different types of mines: coal, phosphate, niobium and gold. This work presents the area monitoring results obtained by the occupational radiation protection group. The data found in these inspections were compared to limits established by national rules. A special assessment of the data obtained was done for a future adoption of the BSS-Safety Series 115 recommendations. (author)

Determination of sulfate in thorium salts using gravimetric technique with previous thorium separation

International Nuclear Information System (INIS)

Silva, C.M. da; Pires, M.A.F.

1994-01-01

Available as short communication only. A simple analytical method to analyze sulfates in thorium salt, is presented. The method is based on the thorium separation as hydroxide. The gravimetric technique is used to analyze the sulfate in the filtered as barium sulfate. Using this method, the sulfate separation from thorium has been reach 99,9% yield, and 0,1% precision. This method is applied to thorium salts specifically thorium sulfate, carbonate and nitrate. (author). 5 refs, 2 tabs

Transformation of thorium sulfate in thorium nitrate by ion exchange resin

International Nuclear Information System (INIS)

Pereira, W.

1991-01-01

A procedure for transforming thorium sulfate into thorium nitrate by means of a strong cationic ion exchanger is presented. The thorium sulfate solution (approximately 15 g/L Th (SO 4 ) 2 ) is percolate through the resin and the column is washed first with water, with a 0,2 M N H 4 OH solution and then with a 0.2 M N H 4 NO 3 solution in order to eliminate sulfate ion. Thorium is eluted with a 2 M solution of (N H 4 ) 2 CO 3 . This eluate is treated with a solution of nitric acid in order to obtain the complete transformation into Th (NO 3 ) 4 . The proposed procedure leads to good quality thorium nitrate with high uranium decontamination. (author)

Radkowsky Thorium Fuel Project

International Nuclear Information System (INIS)

Todosow, Michael

2006-01-01

In the early/mid 1990's Prof. Alvin Radkowsky, former chief scientist of the U.S. Naval Reactors program, proposed an alternate fuel concept employing thorium-based fuel for use in existing/next generation pressurized water reactors (PWRs). The concept was based on the use of a 'seed-blanket-unit' (SBU) that was a one-for-one replacement for a standard PWR assembly with a uranium-based central 'driver' zone, surrounded by a 'blanket' zone containing uranium and thorium. Therefore, the SBU could be retrofit without significant modifications into existing/next generation PWRs. The objective was to improve the proliferation and waste characteristics of the current once-through fuel cycle. The objective of a series of projects funded by the Initiatives for Proliferation Prevention program of the U.S. Department of Energy (DOE-IPP) - BNL-T2-0074,a,b-RU 'Radkowsky Thorium Fuel (RTF) Concept' - was to explore the characteristics and potential of this concept. The work was performed under several BNL CRADAs (BNL-C-96-02 and BNL-C-98-15) with the Radkowsky Thorium Power Corp./Thorium Power Inc. and utilized the technical and experimental capabilities in the Former Soviet Union (FSU) to explore the potential of this concept for implementation in Russian pressurized water reactors (VVERs), and where possible, also generate data that could be used for design and licensing of the concept for Western PWRs. The Project in Russia was managed by the Russian Research Center-?'Kurchatov Institute' (RRC-KI), and included several institutes (e.g., PJSC 'Electrostal', NPO 'LUCH' (Podolsk), RIINM (Bochvar Institute), GAN RF (Gosatomnadzor), Kalininskaja NPP (VVER-1000)), and consisted of the following phases: Phase-1 ($550K/$275K to Russia): The objective was to perform an initial review of all aspects of the concept (design, performance, safety, implementation issues, cost, etc.) to confirm feasibility/viability and identify any 'show-stoppers'; Phase-2 ($600K/$300K to Russia

Neutron irradiation effects on the mechanical properties of thorium and thorium--carbon alloy

International Nuclear Information System (INIS)

Wang, S.C.P.

1978-04-01

The effects of neutron exposure to 3.0 x 10 18 neutrons/cm 2 on the mechanical properties of thorium and thorium-carbon alloy are described. Tensile measurements were done at six different test temperatures from 4 0 K to 503 0 K and at two strain rates. Thorium and thorium-carbon alloy are shown to display typical radiation hardening like other face-centered cubic metals. The yield drop phenomenon of the thorium-carbon alloy is unchanged after irradiation. The variation of shear stress and effective shear stress with test temperature was fitted to Seeger's and Fleischer's equations for irradiated and unirradiated thorium and thorium-carbon alloy. Neutron irradiation apparently contributes an athermal component to the yield strength. However, some thermal component is detected in the low temperature range. Strain-rate parameter is increased and activation volume is decreased slightly for both kinds of metal after irradiation

Use of thorium in the generation IV Molten Salt reactors and perspectives for Brazil

International Nuclear Information System (INIS)

Seneda, Jose A.; Lainetti, Paulo E.O.

2013-01-01

Interest in thorium stems mainly from the fact that it is expected a substantial increase in uranium prices over the next fifty years. The reactors currently in operation consume 65,500 tons of uranium per year. Each electrical gigawatt (GWe) additional need about 200 tU mined per year. So advanced fuel cycles, which increase the reserves of nuclear materials are interesting, particularly the use of thorium to produce the fissile isotope 233 U. It is important to mention some thorium advantages. Thorium is three to five times more abundant than uranium in the earth's crust. Thorium has only one oxidation state. Additionally, thoria produces less radiotoxicity than the UO 2 because it produces fewer amounts of actinides, reducing the radiotoxicity of long life nuclear waste. ThO 2 has higher corrosion resistance than UO 2 , besides being chemically stable due to their low water solubility. The burning of Pu in a reactor based in thorium also decreases the inventories of Pu from the current fuel cycles, resulting in lower risks of material diversion for use in nuclear weapons. There are some ongoing projects in the world, taking into consideration the proposed goals for Generation IV reactors, namely: sustainability, economics, safety and reliability, proliferation resistance and physical protection. Some developments on the use of thorium in reactors are underway, with the support of the IAEA and some governs. Can be highlighted some reactor concepts using thorium as fuel: CANDU; ADTR -Accelerator Driven Thorium Reactor; AHWR -Advanced Heavy Water Reactor proposed by India (light water cooled and moderated by heavy water) and the MSR -Molten Salt Reactor. The latter is based on a reactor concept that has already been successfully tested in the U.S. in the 50s, for use in aircrafts. In this paper, we discuss the future importance of thorium, particularly for Brazil, which has large mineral reserves of this strategic element, the characteristics of the molten salt

Use of thorium in the generation IV Molten Salt reactors and perspectives for Brazil

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-01

Interest in thorium stems mainly from the fact that it is expected a substantial increase in uranium prices over the next fifty years. The reactors currently in operation consume 65,500 tons of uranium per year. Each electrical gigawatt (GWe) additional need about 200 tU mined per year. So advanced fuel cycles, which increase the reserves of nuclear materials are interesting, particularly the use of thorium to produce the fissile isotope {sup 233}U. It is important to mention some thorium advantages. Thorium is three to five times more abundant than uranium in the earth's crust. Thorium has only one oxidation state. Additionally, thoria produces less radiotoxicity than the UO{sub 2} because it produces fewer amounts of actinides, reducing the radiotoxicity of long life nuclear waste. ThO{sub 2} has higher corrosion resistance than UO{sub 2}, besides being chemically stable due to their low water solubility. The burning of Pu in a reactor based in thorium also decreases the inventories of Pu from the current fuel cycles, resulting in lower risks of material diversion for use in nuclear weapons. There are some ongoing projects in the world, taking into consideration the proposed goals for Generation IV reactors, namely: sustainability, economics, safety and reliability, proliferation resistance and physical protection. Some developments on the use of thorium in reactors are underway, with the support of the IAEA and some governs. Can be highlighted some reactor concepts using thorium as fuel: CANDU; ADTR -Accelerator Driven Thorium Reactor; AHWR -Advanced Heavy Water Reactor proposed by India (light water cooled and moderated by heavy water) and the MSR -Molten Salt Reactor. The latter is based on a reactor concept that has already been successfully tested in the U.S. in the 50s, for use in aircrafts. In this paper, we discuss the future importance of thorium, particularly for Brazil, which has large mineral reserves of this strategic element, the

Thorium utilization

Energy Technology Data Exchange (ETDEWEB)

Trauger, D B [Oak Ridge National Lab., TN (USA)

1978-01-01

Some of the factors that provide incentive for the utilization of thorium in specific reactor types are explored and the constraints that stand in the way are pointed out. The properties of thorium and derived fuels are discussed, and test and reactor operating experience is reviewed. In addition, symbiotic systems of breeder and converter reactor are suggested as being particularly attractive systems for energy production. Throughout the discussion, the High-Temperature Gas-Cooled Reactor and Molten Salt Reactor are treated in some detail because they have been developed primarily for use with thorium fuel cycles.

Recent trends of plutonium deposition observed in Japan: comparison with naturallithogenic radionuclides, thorium isotopes

International Nuclear Information System (INIS)

Hirose, K.; Igarashi, Y.; Aoyama, M.

2005-01-01

Plutonium in monthly deposition samples from 2000 to end of 2003 collected to Tsukuba (the Meteorological Research Institute), Japan is reported, together with monthly thorium deposition. The annual deposition of 239,240 Pri during the past 18 years. ranged from 1.7 to 7.8 mBq m -2 y -1 shows no systematic inter-annual variation. However, a maximum annual 239,240 Pu deposition (7.8 mBq m -2 y -1 ) was observed in 2002. On the other hand, monthly 239,240 Pu depositions show a typical seasonal variation with a maximum in spring season (March to April), which corresponds to the seasonal cycle of generation of dust storms in the East Asian arid area. Thorium, which is a typical lithogenic radionuclide, reflects soil-derived particles in the atmospheric dust. The monthly Th deposition showed a typical seasonal trend with a maximum in spring and minimum in summer. The 230 Th/ 232 Th activity ratios in the deposition samples significantly differed from that in surface soils collected in Tsukuba area, which means that a significant part of thorium in deposition samples is not derived from suspension of local soil particles. The result reveals that the resent 239,240 Pu deposition observed in Japan are attributed to resuspension of deposited plutonium; resuspended plutonium originates from the East Asian continent desert and arid areas. These findings suggest that a significant amount of soil dust observed in Tsukuba is attributable to the long-range transport of continental dust from the East Asian arid areas. Plutonium in deposition samples as does thorium would become a proxy of the environmental change in the Asian continent.

Sr isotopes and U series radionuclides in the Sangemini area (Central Italy: Hydrogeology implications

Directory of Open Access Journals (Sweden)

Maurizio Barbieri

2014-06-01

Full Text Available The strontium isotopic ratio (expressed as 87Sr/86Sr of groundwater represents a useful method for studying and understanding the groundwater circulations, also, the U and Ra isotopic compositions can vary as function of the groundwater residence time. This paper reports an evaluation of the probable recharge area of the Sangemini mineral water springs (Terni-Umbria Central Italy and an estimate of the residence time of the aquifer by coupling Sr and U series isotopic systematics. For this study have been analyzed four water sample for the isotope ratio of 87Sr/86Sr, and eleven samples, shallow waters and groundwaters, for U and Ra, furthermore were determined the values of isotopic ratio for sample of typical rocks of the area. The results of this study allow to identify: a recharge area in a restricted sector of the Meso-Cenozoic carbonates a longer and more effective water/rock interaction in the Quaternary series. U and Ra recoil models allow to estimate a groundwater residence time of about 350 years and a total water volume whose value (64*106 m3 agrees with the limited extension of the aquifer. The extension of the aquifer was constrained by comparing Sr isotopic composition of waters and local geological formations. Groundwaters seem mainly to circulate in clayey sandy Quaternary series characterized by low redox conditions.

Status of thorium technology

International Nuclear Information System (INIS)

Garg, R.K.; Raghavan, R.V.; Karve, V.M.; Narayandas, G.R.

1977-01-01

Although a number of studies have been conducted in various countries to evolve reactor systems based on thorium fuel cycle, its use, so far, is limited to only a few reactors. However, for countries having large reserves of thorium, its utilization is of great significance for their nuclear power programmes. Reasonably assured world resources of thorium in the lower price range have been estimated at more than 500,000 tons of ThO 2 . While most of these resources are in placer deposits in various parts of the world, some vein deposits and uranium ores are other important sources of thorium. Monazite, the most important mineral of thorium, is found in the beach sand deposits along with other heavy minerals like ilmenite, rutile, zircon, and sillimanite etc. Mining of these deposits is usually carried out by suction dredging and separation of monazite from other minerals is effected by a combination of magnetic, electrostatic and gravity separation techniques. Chemical processing of monazite is carried out either by sulphuric acid or caustic treatment, followed by separation of the rare earths and thorium by partial precipitation or leaching. The thorium concentrate is further processed to obtain mantle grade thorium nitrate by chemical purification steps whereas solvent extraction using TBP is adopted for making nuclear-grade material. The purified thorium nitrate is converted to the oxide usually by precipitation as oxalate followed by calcination. The oxide is reduced directly with calcium or converted to the chloride or fluoride and then reduced by calcium or magnesium to obtain thorium metal. Various fuel designs based on the metal or its alloys, mixed oxides or carbides, and dispersed type fuel elements have been developed and accordingly, different fabrication techniques have been employed. Work on irradiation of thorium containing fuel elements and separation of U 233 is being carried out. This paper reviews the status of thorium technology in the world with

The thorium alloys in aeronautics: from material analysis to regulation application; Les alliages thories de l'aeronautique: de l'analyse du materiel a l'application de la reglementation

Energy Technology Data Exchange (ETDEWEB)

Laroche, P.; Cazoulat, A.; Gerasimo, P. [Sce de Protection Radiologique des Armees, 92 - Clamart (France)

1999-07-01

The thorium handled in aeronautics is a mixing in variable proportion of different thorium isotopes and its daughter products, but the regulation considers only two alpha emitters (Th-232 and Th-228): the thorium being considered as a natural radioactive substance, the legislation and the activities authorised are less restrictive than for artificial elements, it is a paradoxical situation because the thorium has the annual limit of intake the lowest of the regulation. (N.C.)

High resolution analysis of uranium and thorium concentration as well as U-series isotope distributions in a Neanderthal tooth from Payre (Ardèche, France) using laser ablation ICP-MS

Science.gov (United States)

Grün, Rainer; Aubert, Maxime; Joannes-Boyau, Renaud; Moncel, Marie-Hélène

2008-11-01

We have mapped U ( 238U) and Th ( 232Th) elemental concentrations as well as U-series isotope distributions in a Neanderthal tooth from the Middle Palaeolithic site of Payre using laser ablation ICP-MS. The U-concentrations in an enamel section varied between 1 and 1500 ppb. The U-concentration maps show that U-migration through the external enamel surface is minute, the bulk of the uranium having migrated internally via the dentine into the enamel. The uranium migration and uptake is critically dependent on the mineralogical structure of the enamel. Increased U-concentrations are observed along lineaments, some of which are associated with cracks, and others may be related to intra-prismatic zones or structural weaknesses reaching from the dentine into the enamel. The uranium concentrations in the dentine vary between about 25,000 and 45,000 ppb. Our systematic mapping of U-concentration and U-series isotopes provides insight into the time domain of U-accumulation. Most of the uranium was accumulated in an early stage of burial, with some much later overprints. None of the uranium concentration and U-series profiles across the root of the tooth complied with a single stage diffusion-adsorption (D-A) model that is used for quality control in U-series dating of bones and teeth. Nevertheless, in the domains that yielded the oldest apparent U-series age estimates, U-leaching could be excluded. This means that the oldest apparent U-series ages of around 200 ka represent a minimum age for this Neanderthal specimen. This is in good agreement with independent age assessments (200-230 ka) for the archaeological layer, in which it was found. The Th elemental concentrations in the dental tissues were generally low (between about 1 and 20 ppb), and show little relationship with the nature of the tissue.

ZIRCONIUM-CLADDING OF THORIUM

Science.gov (United States)

Beaver, R.J.

1961-11-21

A method of cladding thorium with zirconium is described. The quality of the bond achieved between thorium and zirconium by hot-rolling is improved by inserting and melting a thorium-zirconium alloy foil between the two materials prior to rolling. (AEC)

Study of the isotopic exchange associated with ionic exchange for the radiochemical separation of 233-Th

International Nuclear Information System (INIS)

Sepulveda Munita, C.J.A.

1983-01-01

The isotopic ion exchange procedure is applied in order to establish an analytical method for the determination of thorium by means of the 233 Th activity, when the presence of interfering elements does not allow a direct non-destructive activation analysis. The separation is based on the retention of 233 Th by a thorium saturated resin, due to the isotopic exchange effect, and subsequent elution of the interfering radioisotopes with a solution of thorium in diluted hydrochloric acid. The interfering elements were those which either present a great affinity for the resin or emit gamma rays with energies close to that of 233 Th (86.6 KeV), when a NaI(Tl) detector is used to obtain the gama-ray spectra of the irradiated samples. The equilibrium time for the thorium isotopic ion exchange and the distribution coefficients for the interfering elements were determined by using Bio-Rad AG 50W resins (100-200 mesh), with 4% to 8% of divinylbenzene. The best separation conditions were established in terms of the thorium and hydrochloric acid concentrations in the solution, the resin cross-linking degree, and the solution flow through the resin. The analytical method was applied to the determination of thorium in samples of ammonium diuranate as well in standard rock samples from the United States Geological Survey. The sensitivity, precision and accuracy of the method are also discussed. (Author) [pt

Study Of Thorium As A Nuclear Fuel.

Directory of Open Access Journals (Sweden)

Prakash Humane

2017-10-01

Full Text Available Conventional fuel sources for power generation are to be replacing by nuclear power sources like nuclear fuel Uranium. But Uranium-235 is the only fissile fuel which is in 0.72 found in nature as an isotope of Uranium-238. U-238 is abundant in nature which is not fissile while U-239 by alpha decay naturally converted to Uranium- 235. For accompanying this nuclear fuel there is another nuclear fuel Thorium is present in nature is abundant can be used as nuclear fuel and is as much as safe and portable like U-235.

Quantitative analysis of thorium-containing materials using an Industrial XRF analyzer

International Nuclear Information System (INIS)

Hasikova, J.; Titov, V.; Sokolov, A.

2014-01-01

Thorium (Th) as nuclear fuel is clean and safe and offers significant advantages over uranium. The technology for several types of thorium reactors is proven but still must be developed on a commercial scale. In the case of commercialization of thorium nuclear reactor thorium raw materials will be on demand. With this, mining and processing companies producing Th and rare earth elements will require prompt and reliable methods and instrumentation for Th quantitative on-line analysis. Potential applicability of X-ray fluorescence conveyor analyzer CON-X series is discussed for Th quantitative or semi-quantitative on-line measurement in several types of Th-bearing materials. Laboratory study of several minerals (zircon sands and limestone as unconventional Th resources; monazite concentrate as Th associated resources and uranium ore residues after extraction as a waste product) was performed and analyzer was tested for on-line quantitative measurements of Th contents along with other major and minor components. Th concentration range in zircon sand is 50-350 ppm; its detection limit at this level is estimated at 25- 50 ppm in 5 minute measurements depending on the type of material. On-site test of the CON-X analyzer for continuous analysis of thorium traces along with other elements in zircon sand showed that accuracy of Th measurements is within 20% relative. When Th content is higher than 1% as in the concentrate of monazite ore (5-8% ThO_2) accuracy of Th determination is within 1% relative. Although preliminary on-site test is recommended in order to address system feasibility at a large scale, provided results show that industrial conveyor XRF analyzer CON-X series can be effectively used for analytical control of mining and processing streams of Th-bearing materials. (author)

Measuring small time periods in earth sciences by uranium series disequilibrium

International Nuclear Information System (INIS)

Choudhary, A.K.

2008-01-01

During the last three decades mass spectrometry in India has seen its application in almost every field of science. In particular, TIMS has revolutionized geological sciences by taking it from a mainly descriptive to modern quantitative Earth Sciences. It has largely contributed in measurement of precise time scales of geological processes. During the last decade, focus has primarily been on measurement of time scales of these fundamental processes. Some of the radiometric methods initially developed for measuring shorter time-scales have their own problems. The intermediate nuclides in the uranium and thorium decay series having much shorter half lives compared to their parents, provide a useful tool to measure intermediate time scales. These isotopes had earlier been ignored due to analytical difficulties associated with their measurement. The development of new generation mass spectrometers with very high abundance sensitivity has now made it possible to measure these isotopic ratios. Consequently U-series isotopic measurements have put unique and at times the only quantitative constraints on the processes taking place in the interior of the Earth. Since such mass spectrometers have recently been installed in some of the laboratories in India, scientific investigation may now be taken up in some of the unexplored areas of Earth Sciences in our country

Comparison of two thorium fuel cycles for use in light water prebreeder/breeder reactor systems (AWBA Development Program)

International Nuclear Information System (INIS)

Merriman, F.C.; McCoy, D.F.; Boyd, W.A.; Dwyer, J.R.

1983-05-01

Light water prebreeder/breeder conceptual reactor systems have been developed which have the potential to significantly improve the fuel utilization of present generation light water reactors. The purpose of this study is to describe and compare two possible types of thorium fuel cycles for use in these light water prebreeder and breeder concepts. The two types of thorium fuel cycles basically differ in the fuel rod design used in the prebreeder cores and the uranium isotopic concentration of fuel supplied to the breeder cores

Speleothem Mg-isotope time-series data from different climate belts

Science.gov (United States)

Riechelmann, S.; Buhl, D.; Richter, D. K.; Schröder-Ritzrau, A.; Riechelmann, D. F. C.; Niedermayr, A.; Vonhof, H. B.; Wassenburg, J.; Immenhauser, A.

2012-04-01

Speleothem Mg-isotope time-series data from different climate belts Sylvia Riechelmann (1), Dieter Buhl(1), Detlev K. Richter (1), Andrea Schröder-Ritzrau (2), Dana F.C. Riechelmann (3), Andrea Niedermayr (1), Hubert B. Vonhof (4) , Jasper Wassenburg (1), Adrian Immenhauser (1) (1) Ruhr-University Bochum, Institute for Geology, Mineralogy and Geophysics, Universitätsstraße 150, D-44801 Bochum, Germany (2) Heidelberg Academy of Sciences, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany (3) Johannes Gutenberg-University Mainz, Institute of Geography, Johann-Joachim-Becher-Weg 21, D-55128 Mainz, Germany (4) Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands The Magnesium isotope proxy in Earth surface research is still underexplored. Recently, field and laboratory experiments have shed light on the complex suite of processes affecting Mg isotope fractionation in continental weathering systems. Magnesium-isotope fractionation in speleothems depends on a series of factors including biogenic activity and composition of soils, mineralogy of hostrock, changes in silicate versus carbonate weathering ratios, water residence time in the soil and hostrock and disequilibrium factors such as the precipitation rate of calcite in speleothems. Furthermore, the silicate (here mainly Mg-bearing clays) versus carbonate weathering ratio depends on air temperature and rainfall amount, also influencing the soil biogenic activity. It must be emphasized that carbonate weathering is generally dominant, but under increasingly warm and more arid climate conditions, silicate weathering rates increase and release 26Mg-enriched isotopes to the soil water. Furthermore, as shown in laboratory experiments, increasing calcite precipitation rates lead to elevated delta26Mg ratios and vice versa. Here, data from six stalagmite time-series Mg-isotope records (Thermo Fisher Scientific Neptune MC-ICP-MS) are shown. Stalagmites

Non-Proliferative, Thorium-Based, Core and Fuel Cycle for Pressurized Water Reactors

International Nuclear Information System (INIS)

Todosow, M.; Raitses, G.; Galperin, A.

2009-01-01

Two of the major barriers to the expansion of worldwide adoption of nuclear power are related to proliferation potential of the nuclear fuel cycle and issues associated with the final disposal of spent fuel. The Radkowsky Thorium Fuel (RTF) concept proposed by Professor A. Radkowsky offers a partial solution to these problems. The main idea of the concept is the utilization of the seed-blanket unit (SBU) fuel assembly geometry which is a direct replacement for a 'conventional' assembly in either a Russian pressurized water reactor (VVER-1000) or a Western pressurized water reactor (PWR). The seed-blanket fuel assembly consists of a fissile (U) zone, known as seed, and a fertile (Th) zone known as blanket. The separation of fissile and fertile allows separate fuel management schemes for the thorium part of the fuel (a subcritical 'blanket') and the 'driving' part of the core (a supercritical 'seed'). The design objective for the blanket is an efficient generation and in-situ fissioning of the U233 isotope, while the design objective for the seed is to supply neutrons to the blanket in a most economic way, i.e. with minimal investment of natural uranium. The introduction of thorium as a fertile component in the nuclear fuel cycle significantly reduces the quantity of plutonium production and modifies its isotopic composition, reducing the overall proliferation potential of the fuel cycle. Thorium based spent fuel also contains fewer higher actinides, hence reducing the long-term radioactivity of the spent fuel. The analyses show that the RTF core can satisfy the requirements of fuel cycle length, and the safety margins of conventional pressurized water reactors. The coefficients of reactivity are comparable to currently operating VVER's/PWR's. The major feature of the RTF cycle is related to the total amount of spent fuel discharged for each cycle from the reactor core. The fuel management scheme adopted for RTF core designs allows a significant decrease in the

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)

Estimates of naturally occurring pools of thorium, uranium and iodine in boreal forests of southeast Sweden

International Nuclear Information System (INIS)

Loefgren, A.; Kautsky, U.

2009-01-01

The distribution patterns of naturally occurring radionuclides or their stable isotopes have been used to study the long-term behaviour of the radionuclides that may originate from nuclear waste. The Swedish Nuclear Fuel and Waste Management Company is performing investigations at two potential sites for nuclear waste disposal in southern Sweden. Here is the distribution and total content of the three naturally occurring radionuclides/stable isotopes, thorium, uranium and iodine, described for six forest localities at those sites. (LN)

Recovery of radiogenic lead-208 from a residue of thorium and rare earths obtained during the operation of a thorium purification pilot plant; Separacao e recuperacao de chumbo-208 dos residuos de torio terras raras gerados na unidade piloto de purificacao de nitrato de torio

Energy Technology Data Exchange (ETDEWEB)

Seneda, Jose Antonio

2006-07-01

Brazil has a long tradition in thorium technology, from mineral dressing (monazite) to the nuclear grade thorium compounds. The estimate reserves are 1200,000. ton of ThO{sub 2}. As a consequence from the work of thorium purification pilot plant at Instituto de Pesquisas Energeticas e Nucleares-CNEN/IPEN-SP, about 25 ton of a sludge containing thorium and rare earths was accumulated. It comes as a raffinate and washing solutions from thorium solvent extraction. This sludge, a crude hydroxide named RETOTER contains thorium, rare earths and minor impurities including the radiogenic lead-208, with abundance 88.34 %. This work discusses the results of the studies and main parameters for its recovery by anionic ion exchange technique in the hydrochloric system. The isotope abundance of this lead was analyzed by high resolution mass spectrometer (ICPMS) and thermoionic mass spectrometer (TIMS) and the data was used to calculate the thermal neutron capture cross section. The value of {sigma}{gamma}{sup 0} = 14.6{+-}0.7 mb was found, quite different from the {sigma}{gamma}{sup 0} = 174.2 {+-} 7.0 mb measure cross section for the natural lead. Preliminary study for the thorium and rare earths separation and recovery was discussed as well. (author)

Thorium: Issues and prospects in Malaysia

Energy Technology Data Exchange (ETDEWEB)

AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman; Bahri, Che Nor Aniza Che Zainul [Nuclear Science Programme, School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia. walareqi@yahoo.com (Malaysia)

2015-04-29

In Malaysia, thorium exists in minerals and rare earth elements production residue. The average range of thorium content in Malaysian monazite and xenotime minerals was found about 70,000 and 15,000 ppm respectively. About 2,636 tonnes of Malaysian monazite was produced for a period of 5 years (2006-2010) and based on the above data, it can be estimated that Malaysian monazite contains about 184.5 tonnes of thorium. Although thorium can become a major radiological problem to our environment, but with the significant deposit of thorium in Malaysian monazite, it has a prospect as a future alternative fuel in nuclear technology. This paper will discuss the thorium issues in Malaysia especially its long term radiological risks to public health and environment at storage and disposal stages, the prospect of exploring and producing high purity thorium from our rare earth elements minerals for future thorium based reactor. This paper also highlights the holistic approach in thorium recovery from Malaysian rare earth element production residue to reduce its radioactivity and extraction of thorium and rare earth elements from the minerals with minimum radiological impact to health and environment.

Thorium: Issues and prospects in Malaysia

International Nuclear Information System (INIS)

AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman; Bahri, Che Nor Aniza Che Zainul

2015-01-01

In Malaysia, thorium exists in minerals and rare earth elements production residue. The average range of thorium content in Malaysian monazite and xenotime minerals was found about 70,000 and 15,000 ppm respectively. About 2,636 tonnes of Malaysian monazite was produced for a period of 5 years (2006-2010) and based on the above data, it can be estimated that Malaysian monazite contains about 184.5 tonnes of thorium. Although thorium can become a major radiological problem to our environment, but with the significant deposit of thorium in Malaysian monazite, it has a prospect as a future alternative fuel in nuclear technology. This paper will discuss the thorium issues in Malaysia especially its long term radiological risks to public health and environment at storage and disposal stages, the prospect of exploring and producing high purity thorium from our rare earth elements minerals for future thorium based reactor. This paper also highlights the holistic approach in thorium recovery from Malaysian rare earth element production residue to reduce its radioactivity and extraction of thorium and rare earth elements from the minerals with minimum radiological impact to health and environment

Thorium: Issues and prospects in Malaysia

Science.gov (United States)

AL-Areqi, Wadeeah M.; Majid, Amran Ab.; Sarmani, Sukiman; Bahri, Che Nor Aniza Che Zainul

2015-04-01

In Malaysia, thorium exists in minerals and rare earth elements production residue. The average range of thorium content in Malaysian monazite and xenotime minerals was found about 70,000 and 15,000 ppm respectively. About 2,636 tonnes of Malaysian monazite was produced for a period of 5 years (2006-2010) and based on the above data, it can be estimated that Malaysian monazite contains about 184.5 tonnes of thorium. Although thorium can become a major radiological problem to our environment, but with the significant deposit of thorium in Malaysian monazite, it has a prospect as a future alternative fuel in nuclear technology. This paper will discuss the thorium issues in Malaysia especially its long term radiological risks to public health and environment at storage and disposal stages, the prospect of exploring and producing high purity thorium from our rare earth elements minerals for future thorium based reactor. This paper also highlights the holistic approach in thorium recovery from Malaysian rare earth element production residue to reduce its radioactivity and extraction of thorium and rare earth elements from the minerals with minimum radiological impact to health and environment.

Hydrologic and environmental controls on uranium-series and strontium isotope ratios in a natural weathering environment

Science.gov (United States)

White, A. M.; Ma, L.; Moravec, B. G.; McIntosh, J. C.; Chorover, J.

2017-12-01

In a remote, volcanic headwater catchment of the Jemez River Basin Critical Zone Observatory (JRB-CZO) in NM, stable water isotopes and solute chemistry have shown that snowmelt infiltrates and is stored before later discharging into springs and streams via subsurface flowpaths that vary seasonally. Therefore, water-rock reactions are also expected to change with season as hydrologic flowpaths transport water, gases and solutes through different biogeochemical conditions, rock types and fracture networks. Uranium-series isotopes have been shown to be a novel tracer of water-rock reactions and source water contributions while strontium isotopes are frequently used as indicators of chemical weathering and bedrock geology. This study combines both isotopes to understand how U and Sr isotope signatures evolve through the Critical Zone (CZ). More specifically, this work examines the relationship between seasonality, water transit time (WTT), and U-series and Sr isotopes in stream and spring waters from three catchments within the JRB-CZO, as well as lithology, rock type and CZ structure in solid phase cores. Samples from ten springs with known WTTs were analyzed for U and Sr isotopes to determine the effect of WTT on the isotopic composition of natural waters. Results suggest that WTT alone cannot explain the variability of U and Sr isotopes in JRB-CZO springs. Stream samples were also collected across two water years to establish how seasonality controls surface water isotopic composition. U and Sr isotope values vary with season, consistent with a previous study from the La Jara catchment; however, this study revealed that these changes do not show a systematic pattern among the three catchments suggesting that differences in the mineralogy and structure of the deep CZ in individual catchments, and partitioning of water along deep vs surficial and fracture vs matrix flow paths, likely also control isotopic variability. The distribution of U-series and Sr isotopes in

Systematic study on Thorium fuel

International Nuclear Information System (INIS)

Shibata, Toshikazu; Kimura, Itsuro; Iwata, Shiro; Furuya, Hirotaka; Suzuki, Susumu.

1988-01-01

Introduced is the activities of the Joint Research Project Team on Thorium Fuel organized by mainly university researchers in Japan and supported by the Ministry of Education, Science and Culture for seven years since 1980. Four major groups were organized; (1) nuclear data, reactor physics and design, (2) nuclear fuel, (3) down stream and (4) biological effects of thorium. The first group covered measurements and analysis on nuclear data of thorium related nuclides, experiment and analysis on nuclear characteristics of thorium containing cores, basic engineering on a thorium molten salt reactor, and designs of several types of reactors. Fabrication and irradiation tests of thorium oxide fuel, and basic studies on new type thorium fuels (e.g. carbide and nitride) were studied by the second group. The third group covered the use of solutions in reprocessing of spent fuel, behavior of fission products, immobilization of high level radioactive waste, and continuous reprocessing for a molten salt reactor. The fourth group performed the trace study for patients who had been intravascularly injected with thorotrast for diagnosis of war injuries during the Second World War. (author)

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

Thorium as an energy source. Opportunities for Norway; Thorium som energikilde - Muligheter for Norge

Energy Technology Data Exchange (ETDEWEB)

2008-02-15

Final Recommendations of the Thorium Report Committee: 1) No technology should be idolized or demonized. All carbon-dioxide (Co2) emission-free energy production technologies should be considered. The potential contribution of nuclear energy to a sustainable energy future should be recognized. 2) An investigation into the resources in the Fen Complex and other sites in Norway should be performed. It is essential to assess whether thorium in Norwegian rocks can be defined as an economical asset for the benefit of future generations. Furthermore, the application of new technologies for the extraction of thorium from the available mineral sources should be studied. 3) Testing of thorium fuel in the Halden Reactor should be encouraged, taking benefit of the well recognized nuclear fuel competence in Halden. 4) Norway should strengthen its participation in international collaborations by joining the EURATOM fission program and the GIF program on Generation IV reactors suitable for the use of thorium. 5) The development of an Accelerator Driven System (ADS) using thorium is not within the capability of Norway working alone. Joining the European effort in this field should be considered. Norwegian research groups should be encouraged to participate in relevant international projects, although these are currently focused on waste management. 6) Norway should bring its competence in waste management up to an international standard and collaboration with Sweden and Finland could be beneficial. 7) Norway should bring its competence with respect to dose assessment related to the thorium cycle up to an international standard. 8) Since the proliferation resistance of uranium-233 depends on the reactor and reprocessing technologies, this aspect will be of key concern should any thorium reactor be built in Norway. 9) Any new nuclear activities in Norway, e.g. thorium fuel cycles, would need strong international pooling of human resources, and in the case of thorium, a strong long

Assessment of surface reactivity of thorium oxide in conditions close to chemical equilibrium by isotope exchange {sup 229}Th/{sup 232}Th method

Energy Technology Data Exchange (ETDEWEB)

Suzuki-Muresan, Tomo; Perrigaud, Katy; Vandenborre, Johan; Ribet, Solange; Grambow, Bernd [Nantes Univ., CNRS/IN2P3 (France). SUBATECH Unite Mixte de Recherche 6457; Takamasa, Inai [TOKAI Univ., Kanagawa (Japan)

2017-08-01

This work aims to assess the solubility and the surface reactivity of crystallized thorium at pH 3.0 in presence of three types of solids: synthesized powder at 1300 C, crushed kernel, and intact kernel. In this study, the kernel is composed by the core solid from high temperature reactors (HTR) sphere particles. The originality of this work consisted in following in a sequential order the kinetic of dissolution, the surface reactivity in presence of isotope tracer {sup 229}Th, and its desorption process. Long time experiments (634 days) allowed to get deeper understanding on the behavior of the surface reactivity in contact with the solution. Solubility values are ranging from 0.3 x 10{sup -7} mol.L{sup -1} to 3 x 10{sup -7} mol.L{sup -1} with a dissolution rate of 10{sup -6}-10{sup -4} g.m{sup -2} day{sup -1}. PHREEQC modeling showed that crystallized ThO{sub 2}(cr, 20 nm) phase controls the equilibrium in solution. Isotope exchange between {sup 229}Th and {sup 232}Th indicated that well-crystallized phase exist as an inert surface regarding to the absence of exchange between surface solid and solution.

Thorium research and development in Turkey

International Nuclear Information System (INIS)

Güngör, Görkem

2015-01-01

Turkey has a great potential regarding thorium resources. Thorium exploration activities have been done in the past mainly by state organizations for determining the thorium resources in Turkey. Thorium occurs as complex mineral together with barite, fluorite and rare earth elements (REE). The increase in global demand for REE creates the opportunity for REE production which will also produce thorium as a by-product. The development of nuclear energy program in Turkey provides the stimulus for research and development activities in nuclear technologies. The final declaration of the workshop emphasizes the importance of thorium reserves in Turkey and the necessity for thorium exploration and development activities in order to determine the feasibility of thorium mining and fuel cycle in Turkey. These activities should be conducted together with the development of technologies for separation of these complex minerals and purification of thorium, REE and other minerals to be utilized as commercial products. There are advanced academic research studies on thorium fuel cycle which should be supported by the industry in order to commercialize the results of these studies. Turkey should be integrated to international R and D activities on ADS which is expected to commercialize on medium term. The legislative framework should be developed in order to provide the industrial baseline for nuclear technologies independent from nuclear regulatory activities

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)

Thorium utilization in power reactors

International Nuclear Information System (INIS)

Saraceno; Marcos.

1978-10-01

In this work the recent (prior to Aug, 1976) literature on thorium utilization is reviewed briefly and the available information is updated. After reviewing the nuclear properties relevant to the thorium fuel cycle we describe briefly the reactor systems that have been proposed using thorium as a fertile material. (author) [es

Information from uranium and thorium isotopes recorded in lake bottom sediment - Lake Kawaguchi. Attempt to evaluate environmental changes

International Nuclear Information System (INIS)

Sakaguchi, A.; Yamamoto, M.; Shimizu, T.; Sasaki, K.; Koshimizu, S.

2003-01-01

Lake sediments, as well as ice cores and marine sediments, have been used to reveal past environmental changes caused by both natural and artificial events with local and global scales. Particles in the lake originate from soil and other suspended matter which are carried in from the inflowing water or from direct discharge (lithogenous particles), and they are also formed in the lake as a result of the growth, metabolism and death of plants and animals (autogenous particles). The settling particles contain U and Th isotopes due to lithogenous particles (soil), and adsorbed U to the particles. Thorium has an exceedingly low solubility in water and is very strongly adsorbed onto particles. If we can distinguish these two different components in the mixture of U due to lithogenous particles themselves and adsorption fractions, the former might provide useful information on past environmental changes by natural events, while the latter information on past environmental changes by artificial events. In this paper, we aimed to test the above hypothesis using data on U and Th isotopes of sediment cores (0- ca. 40 cm depth, covering periods of past several hundred years) from 3 points in Lake Kawaguchi of Fuji-Goko in Japan. By using model equation and results obtained from analysis, we distinguished U due to lithogenous and autogenous particles. And these depth profiles were compared with changes in the rainfall during the period of 1933 - 2001. Although the changes in the 238 U/ 232 Th ratios with depth for lithogenous particles and rainfall do not fluctuate synchronously, some parts of depth coincided with each other. The results suggest strongly that variation in the U and Th isotopic ratios separated by model might be helpful in tracing the past environmental changes in regional scale. To check the usefulness of this method, physical and chemical data such as grain size, grain density, water content and biogenic SiO 2 in the sediment will be further compared with the

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

Evaluation of new geological reference materials for uranium-series measurements: Chinese Geological Standard Glasses (CGSG) and macusanite obsidian.

Science.gov (United States)

Denton, J S; Murrell, M T; Goldstein, S J; Nunn, A J; Amato, R S; Hinrichs, K A

2013-10-15

Recent advances in high-resolution, rapid, in situ microanalytical techniques present numerous opportunities for the analytical community, provided accurately characterized reference materials are available. Here, we present multicollector thermal ionization mass spectrometry (MC-TIMS) and multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) uranium and thorium concentration and isotopic data obtained by isotope dilution for a suite of newly available Chinese Geological Standard Glasses (CGSG) designed for microanalysis. These glasses exhibit a range of compositions including basalt, syenite, andesite, and a soil. Uranium concentrations for these glasses range from ∼2 to 14 μg g(-1), Th/U weight ratios range from ∼4 to 6, (234)U/(238)U activity ratios range from 0.93 to 1.02, and (230)Th/(238)U activity ratios range from 0.98 to 1.12. Uranium and thorium concentration and isotopic data are also presented for a rhyolitic obsidian from Macusani, SE Peru (macusanite). This glass can also be used as a rhyolitic reference material, has a very low Th/U weight ratio (around 0.077), and is approximately in (238)U-(234)U-(230)Th secular equilibrium. The U-Th concentration data agree with but are significantly more precise than those previously measured. U-Th concentration and isotopic data agree within estimated errors for the two measurement techniques, providing validation of the two methods. The large (238)U-(234)U-(230)Th disequilibria for some of the glasses, along with the wide range in their chemical compositions and Th/U ratios should provide useful reference points for the U-series analytical community.

Review of investigations on U, Tr, Ra isotopes migration in biosphere

International Nuclear Information System (INIS)

Titaeva, N.A.; Taskaev, A.I.

1983-01-01

Fragmentary data on uranium, thorium and radium isotope migration in biosphere which have been accumulated by today are generalized. It is shown that isotopes of one element with different degree of intensity migrate by the chain soil-plants. Lack of data on soil and plants is observed alongside with good awareness of U, Th and Ra isotope composition in abiogenic natural formations such as, soils, waters and bottom depositions

Thorium fuel cycle analysis

Energy Technology Data Exchange (ETDEWEB)

Yamaji, K [Central Research Inst. of Electric Power Industry, Tokyo (Japan)

1980-07-01

Systems analysis of the thorium cycle, a nuclear fuel cycle accomplished by using thorium, is reported in this paper. Following a brief review on the history of the thorium cycle development, analysis is made on the three functions of the thorium cycle; (1) auxiliary system of U-Pu cycle to save uranium consumption, (2) thermal breeder system to exert full capacity of the thorium resource, (3) symbiotic system to utilize special features of /sup 233/U and neutron sources. The effects of the thorium loading in LWR (Light Water Reactor), HWR (Heavy Water Reactor) and HTGR (High Temperature Gas-cooled Reactor) are considered for the function of auxiliary system of U-Pu cycle. Analysis is made to find how much uranium is saved by /sup 233/U recycling and how the decrease in Pu production influences the introduction of FBR (Fast Breeder Reactor). Study on thermal breeder system is carried out in the case of MSBR (Molten Salt Breeder Reactor). Under a certain amount of fissile material supply, the potential system expansion rate of MSBR, which is determined by fissile material balance, is superior to that of FBR because of the smaller specific fissile inventory of MSBR. For symbiotic system, three cases are treated; i) nuclear heat supply system using HTGR, ii) denatured fuel supply system for nonproliferation purpose, and iii) hybrid system utilizing neutron sources other than fission reactor.

Feasibility of Thorium Fuel Cycles in a Very High Temperature Pebble-Bed Hybrid System

Directory of Open Access Journals (Sweden)

L.P. Rodriguez

2015-08-01

Full Text Available Nuclear energy presents key challenges to be successful as a sustainable energy source. Currently, the viability of the use thorium-based fuel cycles in an innovative nuclear energy generation system is being investigated in order to solve these key challenges. In this work, the feasibility of three thorium-based fuel cycles (232Th-233U, 232Th-239Pu, and 232Th-U in a hybrid system formed by a Very High Temperature Pebble-Bed Reactor (VHTR and two Pebble-Bed Accelerator Driven Systems (ADSs was evaluated using parameters related to the neutronic behavior such as nuclear fuel breeding, minor actinide stockpile, the energetic contribution of each fissile isotope, and the radiotoxicity of the long lived wastes. These parameters were used to compare the fuel cycles using the well-known MCNPX ver. 2.6e computational code. The results obtained confirm that the 232Th-233U fuel cycle is the best cycle for minimizing the production of plutonium isotopes and minor actinides. Moreover, the inclusion of the second stage in the ADSs demonstrated the possibility of extending the burnup cycle duration and reducing the radiotoxicity of the discharged fuel from the VHTR.

Analysis of aluminium by atomic absorption spectrometry and analysis of thorium and uranium by alpha spectrometry in the black sand of Egypt

International Nuclear Information System (INIS)

Hannachi, Dhouha; Mathlouthi, Nadia

2008-01-01

Throughout the period of our project of end of study carried out in the Center ; main road Sciences and Nuclear Engineering's CNSTN in one is tallied took one Egypt black sand simple with an aim has of knowing the activities of the existing radio elements and especially Uranium and Thorium. In the same mining, we try to take another Egypt black sand simple an aim has knowing the mass of aluminum by using a techniques in Atomique Absorption Spectrophotometer. After the radio chemical and Spectrometry analysis of the black sand sample we found the results following: - Egypt black sand is contains isotopes of Uranium such as 234 U and 238 U; - The Egypt black sand is contains isotopes of Thorium such as 230 Th and 232 Th. - L' Aluminum is a major. (Author)

Radiological significance of thorium processing in manufacturing

International Nuclear Information System (INIS)

Davis, M.W.

1985-01-01

The study of thorium processing in manufacturing comprised monitoring programs at a plant where thorium dioxide was in use and another where the use of thorium nitrate had been discontinued. The measurements of the solubility in simulated lung fluid proved that both materials belonged in the Y Class with dissolution half-times greater than 500 days. Bioassay measurements of 20 subjects from both facilities proved that in vitro monitoring methods, urine, feces, hair and nails analysis were not sufficient indicators of thorium uptake. In vivo monitoring by phoswich and large sodium iodide detectors were proven to be good methods of determining thorium lung burdens. The thoron in breath technique was shown to have a lower limit of sensitivity than lung counting, however, due to lack of information regarding the thoron escape rate from the thorium particles in the lungs the method is not as accurate as lung counting. Two subjects at the thorium dioxide facility had lung burdens of 21+- 16 Bq and 29+- 24 Bq Th 232 and one at the thorium nitrate facility had a lung burden of 37+- 13 Bq. Improvements in the procedures and use of a glove box were among the recommendations to reduce the inhalation of thorium by workers at the thorium dioxide facility. Decontamination of several rooms at the thorium nitrate facility and sealing of the walls and floors were recommended in order to reduce the escape of thoron gas into the room air. The risk to non Atomic Radiation Workers was primarily due to thoron daughters in air while gamma radiation and thorium in air were less important. Conversely, at the thorium dioxide facility the inhalation of thorium in air was the most significant exposure pathway

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)

Symbiotic energy demand and supply system based on collaboration between rare-earth and thorium utilization

International Nuclear Information System (INIS)

Kamei, Takashi

2011-01-01

Progressive economic growth as well as prodigious consumption of energy are expected among Asian countries. Nuclear power has myriad advantages, among them particularly being its status as a low carbon technology and therefore nuclear power would make a significant contribution to curtailing CO 2 emissions. However, the prospects for nuclear power are hindered by some unresolved problems: perceived adverse safety, environmental, and health effects; potential security risks stemming from proliferation; and unresolved challenges in long-term management of nuclear wastes. Thorium utilization as a nuclear fuel will serve as a cornerstone of circumventing such problems, because thorium produces less radioactive waste (i.e. less plutonium) and thus safety, which is of paramount concern, will be enhanced. The deployment of electric vehicles (EVs) as an alternative to supplant gasoline engine cars in the transportation network, will significantly contribute in the reduction of global CO 2 emissions. Rare-earth materials such as neodymium and dysprosium will be essential as a new material for electric automobiles. Thorium is often obtained as a by-product of rare-earth metals, but it is still not utilized as a nuclear fuel currently due to the lack of its own fissionable isotopes and as such, it cannot be employed in the production of nuclear weapons. Recent trends of nuclear disarmament and accumulation of plutonium from uranium fuel cycle can propel the deployment of thorium. The implementation capacity of thorium nuclear power is estimated to be about 392 GWe at 2050. The utilization of thorium will both help to provide clean energy and to supply rare-earth materials for clean automobiles. In order for us to effect the commercial deployment of thorium resources, establishment of an international framework to supply resources from developing countries as well as to supply technology from developed countries is indeed imperative. Herein, the author propose 'The Bank

Thorium utilisation in thermal reactors

International Nuclear Information System (INIS)

Balakrishnan, K.

1997-01-01

It is now more or less accepted that the best way to use thorium is in thermal reactors. This is due to the fact that U233 is a good material in the thermal spectrum. Studies of different thorium cycles in various reactor concepts had been carried out in the early days of nuclear power. After three decades of neglect, the world is once again looking at thorium with some interest. We in India have been studying thorium cycles in most of the existing thermal reactor concepts, with greater emphasis on heavy water reactors. In this paper, we report some of the work done in India on different thorium cycles in the Indian pressurized heavy water reactor (PHWR), and also give a description of the design of the advanced heavy water reactor (AHWR). (author). 1 ref., 2 tabs., 5 figs

Thorium resources and energy utilization (14)

International Nuclear Information System (INIS)

Unesaki, Hironobu

2014-01-01

After the accident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company, thorium reactor has been attracting attention from the viewpoint of safety. Regarding thorium as the resources for nuclear energy, this paper explains its estimated reserves in the whole world and each country, its features such as the situation of utilization, and the reason why it attracts attention now. The following three items are taken up here as the typical issues among the latest topics on thorium: (1) utilization of thorium as a tension easing measure against environmental effects involved in nuclear energy utilization, (2) thorium-based reactor as the next generation type reactor with improved safety, and (3) thorium utilization as the improvement policy of nuclear proliferation resistance. The outline, validity, and problems of these items are explained. Thorium reactor has been adopted as a research theme since the 1950s up to now mainly in the U.S. However, it is not enough in the aspect of technological development and also insufficient in the verification of reliability based on technological demonstration, compared with uranium-fueled light-water reactor. This paper explains these situations, and discusses the points for thorium utilization and future prospects. (A.O.)

Review of Brazilian activities related to the thorium fuel cycle and production of thorium compounds at IPEN-CNEN/SP

International Nuclear Information System (INIS)

Lainetti, Paulo E.O.; Freitas, Antonio A.; Mindrisz, Ana C.

2013-01-01

The Brazilian's interest in the nuclear utilization of thorium has started in the 50's as a consequence of the abundant occurrence of monazite sands. Since the sixties, IPEN-CNEN/SP has performed some developments related to the thorium fuel cycle. The production and purification of thorium compounds was carried out at IPEN for about 18 years and the main product was the thorium nitrate with high purity, having been produced over 170 metric tons of this material in the period, obtained through solvent extraction. The thorium nitrate was supplied to the domestic industry and used for gas portable lamps (Welsbach mantle). Although the thorium compounds produced have not been employed in the nuclear area, several studies were conducted. Therefore, those activities and the accumulated experience are of strategic importance, on one hand due to huge Brazilian thorium reserves, on the other hand by the resurgence of the interest of thorium for the Generation IV Advanced Reactors. This paper presents a review of the Brazilian research and development activities related to thorium technology. (author)

Investigation of thorium hydroxotrifluoroacetates

International Nuclear Information System (INIS)

Andryushin, V.G.; Samatov, A.V.; Chuklinov, R.N.; Shmidt, V.S.

1984-01-01

The precipitation process of thorium hydroxotrifluoroacetates in the Th(NO 3 ) 4 -HNO 3 -CF 3 COOH-NH 4 OH-H 2 O system in the pH range from 0.1 to 8.6 at a 100 g/l thorium concentration in it has been investigated. The curve of the pH dependence of the main thorium salts solubility in the pH=4.4 range exhibits a local maximum, the position of the latter being in complete accordance with its earlier established relation to the parameter of the ligand anion nucleophility. The composition of isolated hydroxotrifluoroacetate hydrates corresponds to the generic formula Th(OH)sub(x)(CFsub(3)COO)sub(4-x)xnHsub(2)O, where 3.0 >= x >= 1.5, and n=1.0-6.0. The density of the crystals obtained is measured and the thermal stability is studied. It is established, that, for the thorium hydroxotrifluoroacetate hydrates, the same general regularities in the effect of degree of hydrolysis and hydration on the position of decomposition temperature effects and on the density of compounds hold, as has been previously found in studying thorium- and plutonium hydroxosalts

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)

Alpha spectroscopy with ionization chamber to determine uranium and thorium in environmental samples

International Nuclear Information System (INIS)

Carvalho Conti, L.F. de.

1983-01-01

A high-resolution, parallel Frisch ionization chamber with an efficient area of 320 cm 2 was developed and applied as an alpha spectrometer. The resolution of the spectrum is approximatelly 40 KeV fwhm (full width half maximum) for 233 U point source. The spectrum is recorded by a 1024 channels pulse-height analyser. The counting gas is commercial available mixture of argon and methane. The counting efficiency for 233 U energy-window selected is in order of 42% for a calibration source placed on the cathode axis. No radial dependence of this efficiency was observed. The chamber was used for counting the activity of uranium and thorium isotopes on large area stainless steel planchets. The large area thin sources were prepared extracting the uranium and thorium isotopes from 1M HNO 3 - aqueous solution with polymeric membranes containing tri-n-octyl-phosphine oxide adhered on the surface of the 314 cm 2 planchet. The integral back-ground is typically 7 counts/min between 4 and 6 MeV. The sensitivity of the procedure used ofr 238 U is about 30 Bq/1 based on 3S of back-ground, 1 liter sample volume and 30 min counting time. (Author) [pt

Determination of thorium in seawater by neutron activation analysis and mass spectrometry

International Nuclear Information System (INIS)

Huh, Chih-An.

1987-01-01

The recent development of neutron activation analysis and mass spectrometric methods for the determination of 232 Th in seawater has made possible rapid sampling and analysis of this long-lived, non-radiogenic thorium isotope on small-volume samples. The marine geochemical utility of 232 Th, whose concentration in seawater is extremely low, warrants the development of these sensitive techniques. The analytical methods and some results are presented and discussed in this article. 24 refs., 3 figs

Determination of uranium and thorium isotopes and polonium in sediment profiles from Baixada Santista, SP

International Nuclear Information System (INIS)

Ramos, Guilherme da Franca

2010-01-01

The objective of the present work is to determine the activity concentration of uranium and thorium isotopes and polonium in estuarine sediments from Baixada Santista. The area comprehends nine cities in the Brazilian coast (Bertioga, Guaruja, Santos, Sao Vicente, Cubatao, Praia Grande, Mongagua, Itanhaem and Peruibe). It is one of the most important industrial areas in Brazil due to the large number of industries operating in Cubatao, such as steel, petrochemical and fertilizer industries. That, together with a large population, causes a negative impact on the marine biota. In the present work 10 profiles of sediment cores, with depth varying from 41 to 98 cm, were analyzed. The cores were obtained from Santos, Cubatao, Sao Vicente and Bertioga. The cores were sliced every 2 cm and were treated with both physical and chemical processes, including drying, grinding and sieving. The samples were dissolved by acid digestion, till total dissolution and destruction of organic matter. After the acid digestion, the samples were filtered and evaporated till dryness. The radiochemical techniques used to separate the radionuclides and to prepare the final source for alpha counting were ion exchange chromatography and spontaneous deposition for polonium and electrodeposition for U and Th. The final sources were counted in a surface barrier alpha spectrometer. Values obtained for the radionuclides analyzed were similar to the activity concentrations of sediments in non polluted areas, with the exception of a few samples that showed anthropic influence. (author)

Drying characteristics of thorium fuel corrosion products

Energy Technology Data Exchange (ETDEWEB)

Smith, R.-E. E-mail: rzl@inel.gov

2004-07-01

The open literature and accessible US Department of Energy-sponsored reports were reviewed for the dehydration and rehydration characteristics of potential corrosion products from thorium metal and thorium oxide nuclear fuels. Mixed oxides were not specifically examined unless data were given for performance of mixed thorium-uranium fuels. Thorium metal generally corrodes to thorium oxide. Physisorbed water is readily removed by heating to approximately 200 deg. C. Complete removal of chemisorbed water requires heating above 1000 deg. C. Thorium oxide adsorbs water well in excess of the amount needed to cover the oxide surface by chemisorption. The adsorption of water appears to be a surface phenomenon; it does not lead to bulk conversion of the solid oxide to the hydroxide. Adsorptive capacity depends on both the specific surface area and the porosity of the thorium oxide. Heat treatment by calcination or sintering reduces the adsorption capacity substantially from the thorium oxide produced by metal corrosion.

Assessment of the insertion of reprocessed fuel spiked with thorium in a PWR core

Energy Technology Data Exchange (ETDEWEB)

Castro, Victor F.; Monteiro, Fabiana B.A.; Pereira, Claubia, E-mail: victorfc@fis.grad.ufmg.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

2017-07-01

Reprocessed fuel by UREX+ technique and spiked with thorium was inserted in a PWR core and neutronic parameters have been analyzed. Based on the Final Safety Analysis Report (FSAR) of the Angra-2 reactor, the core was modeled and simulated with SCALE6.0 package. The neutronic data evaluation was carried out by the analysis of the effective and infinite multiplication factors, and the fuel evolution during the burnup. The conversion ratio (CR) was also evaluated. The results show that, when inserting reprocessed fuel spiked with thorium, the insertion of burnable poison rods is not necessary, due to the amount of absorber isotopes present in the fuel. Besides, the conversion ratio obtained was greater than the presented by standard UO{sub 2} fuel, indicating the possibility of extending the burnup. (author)

Remarks on the thorium cycle

International Nuclear Information System (INIS)

Teller, E.

1978-01-01

The use of thorium and neutrons to make 233 U would provide energy for many thousands of years. Thorium is more abundant than uranium and 233 U is the best fissile material for thermal neutron reactors. Four approaches to the use of thorium are worth developing: heavy water moderated reactors with conversion ratios greater than 0.9, such as modified CANDU with lower cost of separating D 2 O and 235 U; molten salt breeder reactors, from which fission products and excess fuel may be continuously removed; fusion-fission hybrids that produce adequate tritium and excess neutrons for sustenance and 233 U production in a subcritical thorium 233 U blanket; and by fission-initiated thermo-nuclear explosions in cavities in salt beds one mile below the earth's surface, yielding 233 U from the excess neutrons and thorium and decontaminated steam for power production. (author)

Thorium nuclear fuel cycle technology

International Nuclear Information System (INIS)

Eom, Tae Yoon; Do, Jae Bum; Choi, Yoon Dong; Park, Kyoung Kyum; Choi, In Kyu; Lee, Jae Won; Song, Woong Sup; Kim, Heong Woo

1998-03-01

Since thorium produces relatively small amount of TRU elements after irradiation in the reactor, it is considered one of possible media to mix with the elements to be transmuted. Both solid and molten-salt thorium fuel cycles were investigated. Transmutation concepts being studied involved fast breeder reactor, accelerator-driven subcritical reactor, and energy amplifier with thorium. Long-lived radionuclides, especially TRU elements, could be separated from spent fuel by a pyrochemical process which is evaluated to be proliferation resistance. Pyrochemical processes of IFR, MSRE and ATW were reviewed and evaluated in detail, regarding technological feasibility, compatibility of thorium with TRU, proliferation resistance, their economy and safety. (author). 26 refs., 22 figs

Principle of natural and artificial radioactive series equivalency

International Nuclear Information System (INIS)

Vasilyeva, A.N.; Starkov, O.V.

2001-01-01

In the present paper one approach used under development of radioactive waste management conception is under consideration. This approach is based on the principle of natural and artificial radioactive series radiotoxic equivalency. The radioactivity of natural and artificial radioactive series has been calculated for 10 9 - years period. The toxicity evaluation for natural and artificial series has also been made. The correlation between natural radioactive series and their predecessors - actinides produced in thermal and fast reactors - has been considered. It has been shown that systematized reactor series data had great scientific significance and the principle of differential calculation of radiotoxicity was necessary to realize long-lived radioactive waste and uranium and thorium ore radiotoxicity equivalency conception. The calculations show that the execution of equivalency principle is possible for uranium series (4n+2, 4n+1). It is a problem for thorium. series. This principle is impracticable for neptunium series. (author)

Review of thorium fuel reprocessing experience

International Nuclear Information System (INIS)

Brooksbank, R.E.; McDuffee, W.T.; Rainey, R.H.

1978-01-01

The review reveals that experience in the reprocessing of irradiated thorium materials is limited. Plants that have processed thorium-based fuels were not optimized for the operations. Previous demonstrations of several viable flowsheets provide a sound technological base for the development of optimum reprocessing methods and facilities. In addition to the resource benefit by using thorium, recent nonproliferation thrusts have rejuvenated an interest in thorium reprocessing. Extensive radiation is generated as the result of 232 U-contamination produced in the 233 U, resulting in the remote operation and fabrication operations and increased fuel cycle costs. Development of the denatured thorium flowsheet, which is currently of interest because of nonproliferation concerns, represents a difficult technological challenge

Thorium Energy for the World

CERN Document Server

Revol, Jean-Pierre; Bourquin, Maurice; Kadi, Yacine; Lillestol, Egil; De Mestral, Jean-Christophe; Samec, Karel

2016-01-01

The Thorium Energy Conference (ThEC13) gathered some of the world’s leading experts on thorium technologies to review the possibility of destroying nuclear waste in the short term, and replacing the uranium fuel cycle in nuclear systems with the thorium fuel cycle in the long term. The latter would provide abundant, reliable and safe energy with no CO2 production, no air pollution, and minimal waste production. The participants, representatives of 30 countries, included Carlo Rubbia, Nobel Prize Laureate in physics and inventor of the Energy Amplifier; Jack Steinberger, Nobel Prize Laureate in physics; Hans Blix, former Director General of the International Atomic Energy Agency (IAEA); Rolf Heuer, Director General of CERN; Pascal Couchepin, former President of the Swiss Confederation; and Claude Haegi, President of the FEDRE, to name just a few. The ThEC13 proceedings are a source of reference on the use of thorium for energy generation. They offer detailed technical reviews of the status of thorium energy ...

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)

Minerals yearbook, 1991: Thorium. Annual report

International Nuclear Information System (INIS)

Hedrick, J.B.

1992-10-01

Domestic mine production data for thorium-bearing monazite are developed by the U.S. Bureau of Mines from a voluntary survey of U.S. operations entitled, 'Rare Earths, Thorium, and Scandium.' The one mine to which a survey form was sent responded, representing 100% of domestic production. Mine production data for thorium are withheld to avoid disclosing company proprietary data. Statistics on domestic thorium consumption are developed by surveying various processors and end users, evaluating import-export data, and analyzing Government stockpile shipments

Thorium ore deposits

International Nuclear Information System (INIS)

Angelelli, Victorio.

1984-01-01

The main occurences of the thorium minerals of the Argentine Republic which have not been exploited, due to their reduced volume, are described. The thoriferous deposits have three genetic types: pegmatitic, hydrothermal and detritic, being the most common minerals: monazite, thorite and thorogummite. The most important thorium accumulations are located in Salta, being of less importance those of Cordoba, Jujuy and San Juan. (M.E.L.) [es

The importance of thorium in the context of the generation in advanced reactors and the IPEN's experience

International Nuclear Information System (INIS)

Lainetti, Paulo E.O.; Mindrisz, Ana C.; Freitas, Antonio A.

2011-01-01

Globally, the 80's and 90's years were characterized by a significant reduction in the rate of growth of nuclear energy. However, from the 2000's, there has been a significant change in the international arena, with the 'renaissance' of interest in nuclear energy, even in countries that had abandoned nuclear power. To answer questions like security, reducing the generation of radioactive waste, control of proliferation risks and long-term sustainability, some initiatives have been adopted by some countries. In 2000, the Department of Energy - DOE - United States created the GIF - Generation IV International Forum for Nuclear Reactors. Six reactor concepts were selected based on criteria such as: reduction of radioactive wastes, safety and cost effective to meet the increasing energy demand on a sustainable basis, being resistant to diversion of materials for nuclear weapons proliferation and safer against terrorist attacks. In this context, it becomes important to use thorium as nuclear fuel for the Generation IV Advanced Reactors, with startup scheduled for 2030. Although the thorium does not present significant commercial value nowadays, in a not too distant future it will probably be an important commodity. Unfortunately, contrarily to what is happening in most developed countries in recent years, Brazil is paying little attention to the thorium, even less than in the past, despite its large reserves. Thorium is three to four times more abundant than uranium in the Earth's crust and, although not fissile, all thorium can be used to produce 233 U, by absorption of neutrons and subsequent radioactive decay. This uranium isotope is an excellent fuel for use in almost all types of nuclear reactors. It is possible that the thorium constitutes the largest Brazilian energy reserve, supplanting much oil (despite the findings of the pre-salt) and uranium. Brazil has a long tradition in the thorium technology, from mining of monazite until the obtainment of high purity

Thorium fuel cycle - Potential benefits and challenges

International Nuclear Information System (INIS)

2005-05-01

There has been significant interest among Member States in developing advanced and innovative technologies for safe, proliferation resistant and economically efficient nuclear fuel cycles, while minimizing waste and environmental impacts. This publication provides an insight into the reasons for renewed interest in the thorium fuel cycle, different implementation scenarios and options for the thorium cycle and an update of the information base on thorium fuels and fuel cycles. The present TECDOC focuses on the upcoming thorium based reactors, current information base, front and back end issues, including manufacturing and reprocessing of thorium fuels and waste management, proliferation-resistance and economic issues. The concluding chapter summarizes future prospects and recommendations pertaining to thorium fuels and fuel cycles

Asymmetrically deformed states of thorium isotopes during fission process

International Nuclear Information System (INIS)

Blons, J.

1982-05-01

Some theoretical considerations are recalled on fission barriers calculated from macroscopic, microscopic or macroscopic-microscopic and ''thorium anomaly'' problem is set. Experimental techniques used to measure fission cross sections in (n,f) reactions near the threshold are described. Fission dectector is described; stray resonance problems and retrodiffused neutrons are discussed. Results obtained in experimental study of 230 Th(n,f) and 232 Th(n,f) reactions are presented. They are compared with results obtained in other laboratories. The analysis model which allows to describe a (n,f) reaction is exposed. The compound nucleus formation cross section and transmission coefficients in neutron and gamma output channel are presented according to neutron energy for each value of angular moment and parity. Cross-section analysis and angular distribution obtained respectively in 230 Th(n,f) and 232 Th(n,f) reactions is exposed. Result interpretation show new aspects of nuclei rotational spectra and new nuclear forms [fr

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 owing to the excellent neutronic characteristics of 233 U, and the widespread and cheap thorium resources. Rapidly increasing uranium prices, public reluctance for widespread Pu recycling and expected delays for the market penetration of fast breeders have led to a reconsideration of the thorium fuel cycle merits. In addition, problems associated with reprocessing and waste handling, particularly with re-fabrication by remote handling of 233 U, are certainly not appreciably more difficult than for Pu recycling. To divert from uranium as a nuclear energy source it seems worth while intensifying future efforts for closing the Th/ 233 U fuel cycle. HTGRs are particularly promising for economic application. However, further research and development activities should not concentrate on this reactor type alone. Light- and heavy-water-moderated reactors, and even future fast breeders, may just as well take advantage of a demonstrated thorium fuel cycle. (author)

A new method for determination of trace amount thorium-spectrophotometric determination of thorium in aqueous phase by chlorophosphonazo-mA

International Nuclear Information System (INIS)

Xia Yuanxian; Qian Hesheng

1986-01-01

In this paper the spectrophotometric method for determination of trace amount of thorium in weak acidic medium by chlorophosphonazo-mA is described. The composition of the complex was estimated to be 1:4 by slope ratio method. The apparent molar absorption of thorium at 675 nm is 9.2 x 10 4 . Beer's law is obeyed for 0-12.0 μg of thorium in 10 ml solution. The coefficient of variation for thorium is 0.88%. The method has been applied to the determination of trace amounts of thorium in the extraction process of thorium

Particle dynamics study in the wake of Kerguelen Island using thorium isotopes

International Nuclear Information System (INIS)

Venchiarutti, C.; Jeandel, C.; Roy-Barman, M.

2008-01-01

In the context of the Kerguelen Ocean and Plateau compared Study (KEOPS, 19 January-13 February 2005), particle dynamics were investigated using thorium isotope measurements over and off the Kerguelen plateau. Dissolved and particulate 230 Th and 232 Th samples were collected at nine stations. Dissolved excess 230 Th concentrations ( 230 Th(xs)) vary from 0.5 to 20.8 fg/kg and particulate 230 Th(xs) concentrations from 0.1 to 10.0 fg/kg. Dissolved and particulate 232 Th concentration ranges are 16.8-450.2 pg/kg and 3.8-502.8 pg/kg, respectively. The 230 Th(xs) concentrations increase linearly with depth down to the bottom at most of the plateau stations and down to 1000 m at the off-plateau stations. This linear trend is observed down to the bottom (1550 m) at Kerfix, the open-ocean 'upstream' station located west of the Kerguelen plateau. A simple reversible scavenging model applied to these data allowed the estimation of adsorption rate constant (k 1 ≅ 0.2-0.8 year -1 ), desorption rate constant (k -1 ) ≅ 1-8 year -1 ) and partition coefficients (average K = 0.16 ± 0.07). Calculated particle settling velocities S deduced from this simple model are ca. 500 m/year at most of the plateau stations and 800 m/year at all the off-plateau stations. The plateau settling velocities are relatively low for such a productive site, compared to the surrounding HNLC areas. The difference might reflect the fact that lateral advection is neglected in this model. Taking this advection into account allows the reconstruction of the observed 230 Th(xs) linear distributions, but only if faster settling velocities are considered. This implies that the 1 D model strongly underestimates the settling velocity of the particles. In the deep layers, the occurrence of intense boundary scavenging along the escarpment due to bottom sediment re-suspension and interaction with a nepheloid layer, yielding a removal of similar to 50% of the Th stock along the northwestward transect, is

Burn-up calculation of different thorium-based fuel matrixes in a thermal research reactor using MCNPX 2.6 code

Directory of Open Access Journals (Sweden)

Gholamzadeh Zohreh

2014-12-01

Full Text Available Decrease of the economically accessible uranium resources and the inherent proliferation resistance of thorium fuel motivate its application in nuclear power systems. Estimation of the nuclear reactor’s neutronic parameters during different operational situations is of key importance for the safe operation of nuclear reactors. In the present research, thorium oxide fuel burn-up calculations for a demonstrative model of a heavy water- -cooled reactor have been performed using MCNPX 2.6 code. Neutronic parameters for three different thorium fuel matrices loaded separately in the modelled thermal core have been investigated. 233U, 235U and 239Pu isotopes have been used as fissile element in the thorium oxide fuel, separately. Burn-up of three different fuels has been calculated at 1 MW constant power. 135X and 149Sm concentration variations have been studied in the modelled core during 165 days burn-up. Burn-up of thorium oxide enriched with 233U resulted in the least 149Sm and 135Xe productions and net fissile production of 233U after 165 days. The negative fuel, coolant and void reactivity of the used fuel assures safe operation of the modelled thermal core containing (233U-Th O2 matrix. Furthermore, utilisation of thorium breeder fuel demonstrates several advantages, such as good neutronic economy, 233U production and less production of long-lived α emitter high radiotoxic wastes in biological internal exposure point of view

The determination of environmental levels of uranium and thorium series isotopes and 137Cs in aquatic and terrestrial samples

International Nuclear Information System (INIS)

Wilkinson, P.

1985-01-01

This publication details the analytical methods used at the Freshwater Institute for the radiochemical analysis of aquatic and terrestrial samples. Sample collection methods are described with emphasis on water sampling. A detailed 'Calculations' section contains the mathematical formulae used to determine the absolute activity of each isotope analyzed. 25 refs

Rapid collection of iron hydroxide for determination of Th isotopes in seawater

Energy Technology Data Exchange (ETDEWEB)

Okubo, Ayako, E-mail: okubo.ayako@jaea.go.jp [Japan Atomic Energy Agency, Research Group for Analytical Chemistry (Japan); Obata, Hajime, E-mail: obata@aori.u-tokyo.ac.jp [Atmosphere Ocean Research Institute, The University of Tokyo (Japan); Magara, Masaaki, E-mail: magara.masaaki@jaea.go.jp [Japan Atomic Energy Agency, Research Group for Analytical Chemistry (Japan); Kimura, Takaumi, E-mail: kimura.takaumi@jaea.go.jp [Japan Atomic Energy Agency, Research Group for Analytical Chemistry (Japan); Ogawa, Hiroshi, E-mail: hogawa@aori.u-tokyo.ac.jp [Atmosphere Ocean Research Institute, The University of Tokyo (Japan)

2013-12-04

Graphical abstract: -- Highlights: •DIAION CR-20 chelating resin has successfully collected iron-hydroxide with Th isotopes. •Ferric ions in the iron hydroxide were bonded to functional groups of the chelating resin. •The time of preconcentration step was markedly reduced from a few days to 3–4 h. -- Abstract: This work introduces a novel method of recovery of iron hydroxide using a DIAION CR-20 chelating resin column to determine Th isotopes in seawater with a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). Thorium isotopes in seawater were co-precipitated with iron hydroxide, and this precipitate was sent to chelating resin column. Ferric ions in the iron hydroxide were bonded to functional groups of the chelating resin directly, resulting in a pH increase of the effluent by release of hydroxide ion from the iron hydroxide. The co-precipitated thorium isotopes were quantitatively collected within the column, which indicated that thorium was retained on the iron hydroxide remaining on the chelating column. The chelating column quantitatively collected {sup 232}Th with iron hydroxide in seawater at flow rates of 20–25 mL min{sup −1}. Based on this flow rate, a 5 L sample was processed within 3–4 h. The >20 h aging of iron hydroxide tends to reduce the recovery of {sup 232}Th. The rapid collection method was successfully applied to the determination of {sup 230}Th and {sup 232}Th in open-ocean seawater samples.

Technology of getting of microspheric thorium dioxide

International Nuclear Information System (INIS)

Balakhonov, V.G.; Matyukha, V.A.; Saltan, N.P.; Filippov, E.A.; Zhiganov, A.N.

1999-01-01

There has been proposed a technique for getting granulated thorium dioxide from its salts solutions according to the cryogenic technology by the method of a solid phase conversion. It includes the following operations: dispersion of the initial solution into liquid nitrogen and getting of cryogranules of the necessary size by putting oscillations of definite frequency on a die device and by charging formed drops in the constant electric field; solid phase conversion of thorium salts into its hydroxide by treating cryogranules with a cooled ammonia solution, drying and calcination of hydroxide granules having got granulated thorium dioxide. At the pilot facility there have been defined and developed optimum regimes for getting granulated thorium dioxide. The mechanism of thorium hydroxide cryogranules conversion into thorium dioxide was investigated by the thermal analysis methods. (author)

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

Uranium and thorium decay series radionuclides in human and animal foodchains - a review

International Nuclear Information System (INIS)

Linsalata, P.

1994-01-01

Human exposures along plant and animal pathways to isotopes of U, Th, Ra, Pb, and Po are reviewed. The range and variability of intakes among human populations resulting from dietary sources are presented. Also discussed are the sources of intake among fare animals reared for consumption. Under most circumstances, the soil-plant-human pathway is the predominant route of intake for humans and livestock. Radionuclide distributions within livestock and human tissues, and the transfer factors used to model intakes along various food chain pathways an summarized. Bone is the major site of deposition in livestock and humans. Where possible, summary data and conclusions from previous reviews are considered along with some notable gaps in the data base for natural series radionuclides. 67 refs., 4 figs., 6 tabs

Hodgkin's disease following thorium dioxide angiography

Energy Technology Data Exchange (ETDEWEB)

Gotlieb, A I; Kirk, M E [McGill Univ., Montreal, Quebec (Canada). Dept. of Pathology; Hutchison, J L [Montreal General Hospital, Quebec (Canada)

1976-09-04

Hodgkin's disease occurred in a 53-year-old man who, 25 years previously, had undergone cerebral angiography, for which thorium dioxide suspension (Thorotrast) was used. Deposits of thorium dioxide were noted in reticuloendothelial cells in various locations. An association between thorium dioxide administration and the subsequent development of malignant tumours and neoplastic hematologic disorders has previously been reported.

Thorium oxalate solubility and morphology

International Nuclear Information System (INIS)

Monson, P.R. Jr.; Hall, R.

1981-10-01

Thorium was used as a stand-in for studying the solubility and precipitation of neptunium and plutonium oxalates. Thorium oxalate solubility was determined over a range of 0.001 to 10.0 in the concentration parameter [H 2 C 2 O 4 ]/[HNO 3 ] 2 . Morphology of thorium oxide made from the oxalate precipitates was characterized by scanning electron microscopy. The different morphologies found for oxalate-lean and oxalate-rich precipitations were in agreement with predictions based on precipitation theory

Microscopic study of positive-parity yrast bands of Th isotopes

Indian Academy of Sciences (India)

tor arrays. Thorium is one of the isotopic mass chains that has been studied. The level ... the valence space and np-interaction in SOP orbits plays a crucial role in determining the ..... parameters suggested by Rozmej [37] in the actinide region.

Determination of Uranium, Thorium and Radium 226 in Zircon containig sands by alpha spectrometry

International Nuclear Information System (INIS)

Spezzano, P.

1985-01-01

The industrial utilization of Zircon sands for the production of refractories presents radiological problems owing to the risk of inhalation of Uranium, Thorium and their decay products, present in high concentrations in such materials. A method of analysis was realized for the determination of Uranium, Thorium and Radium-226 in Zircon sands, including the total dissolution of the sample, radiochemical separation and final measurement by alpha spectrometry with surface barrier detector. The concentrations of the main alpha-emitting radionuclides presents in two samples of Zircon sands have been determined and the possibility of disequilibrium along the decay series has been pointed out

Magellanic Clouds Cepheids: Thorium Abundances

Directory of Open Access Journals (Sweden)

Yeuncheol Jeong

2018-03-01

Full Text Available The analysis of the high-resolution spectra of 31 Magellanic Clouds Cepheid variables enabled the identification of thorium lines. The abundances of thorium were found with spectrum synthesis method. The calculated thorium abundances exhibit correlations with the abundances of other chemical elements and atmospheric parameters of the program stars. These correlations are similar for both Clouds. The correlations of iron abundances of thorium, europium, neodymium, and yttrium relative to the pulsational periods are different in the Large Magellanic Cloud (LMC and the Small Magellanic Cloud (SMC, namely the correlations are negative for LMC and positive or close to zero for SMC. One of the possible explanations can be the higher activity of nucleosynthesis in SMC with respect to LMC in the recent several hundred million years.

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)

Research and development of thorium fuel cycle

International Nuclear Information System (INIS)

Oishi, Jun.

1994-01-01

Nuclear properties of thorium are summarized and present status of research and development of the use of thorium as nuclear fuel is reviewed. Thorium may be used for nuclear fuel in forms of metal, oxide, carbide and nitride independently, alloy with uranium or plutonium or mixture of the compound. Their use in reactors is described. The reprocessing of the spent oxide fuel in thorium fuel cycle is called the thorex process and similar to the purex process. A concept of a molten salt fuel reactor and chemical processing of the molten salt fuel are explained. The required future research on thorium fuel cycle is commented briefly. (T.H.)

Determination of natural thorium in urines

International Nuclear Information System (INIS)

Jeanmaire, L.; Jammet, H.

1959-01-01

A procedure for the quantitative analysis of thorium in urine is described. After precipitation with ammonium hydroxide, dissolution of the precipitate, extraction at pH 4-4.2 with cupferron in chloroformic solution and mineralization, a colorimetric determination of thorium with thorin is performed. It is thus possible to detect about 2 γ of thorium in the sample. (author) [fr

Advanced thorium cycles in LWRs and HWRs

International Nuclear Information System (INIS)

Radkowsky, A.

The main aspects of advanced thorium cycles in LWRs and HWRs are reviewed. New concepts include the seed blanket close packed heavy water breeder, the light water seed blanket thorium burner and self-induced thorium cycle in CANDU type reactors. (author)

International Isotopes Markets

Directory of Open Access Journals (Sweden)

Stanislaw Z. Zhiznin

2016-01-01

Full Text Available The paper studies world markets of stable and radioactive isotopes. Isotopes have found various applications in science, industry, agriculture and other sectors of the economy, but especially - in medicine. Nuclear medicine is developing intensively all over the world thanks to the success in the treatment of various diseases with the help of radioactive pharmaceuticals (radiopharmaceuticals. The article uses empirical data from a forecast study of the global radiopharmaceuticals market made in 2015 by a research company «Markets and Markets» for the European, North American and global markets. The paper also analyzes the statistical data on the global export and import of natural uranium, enriched and depleted uranium, plutonium, thorium and some stable isotopes of non-medical purposes, presented by a company «Trend economy» in 2014. Despite a unique industrial base for the production of isotopes created in the Soviet Union Russia occupies a modest position on the world market of nuclear medicine except for certain areas. More than 80% of isotopes, produced in USSR were consumed domestically, the export of the stable and radioactive isotopes was in equal proportions. Now the country's domestic radiopharmaceuticals market is poorly developed. To radically change the situation, it is necessary to carry out reforms that stimulate the development of nuclear medicine.

Analysis of the thorium inclusion in the fuel of a fast reactor cooled by lead

International Nuclear Information System (INIS)

Juarez M, L. C.; Francois L, J. L.

2017-09-01

In the present work, we first verified a model of the European reactor cooled with lead (ELFR). The calculations were made with the code Monte Carlo serpent 2.27 and the library of cross sections Jeff-3.1. For this verification, three neutron parameters were compared: the evolution of the neutron multiplication factor, the Doppler constant and the effect of the vacuum fraction of the refrigerant, obtaining a good approximation with the reference values. Subsequently, the inclusion of thorium as a fertile material within the fuel was analyzed and the same neutron parameters were compared with the original fuel. The evolution of criticality for the case of thorium fuel differs significantly with respect to that of the original fuel (without thorium); this is due mainly to the breeding of the fissile isotope 233 U. Therefore, is possible to have a longer fuel cycle, favoring the availability factor of the plant, without compromising the performance of the reactor since both the Doppler constant and the effect of the vacuum fraction of the refrigerant show a similar tendency to those of the original fuel, being negative in both cases. (Author)

Utilization of thorium in thermal reactors

International Nuclear Information System (INIS)

Srinivasan, K.R.; Nakra, A.N.

1978-01-01

Large deposits of thorium are found in India. 233 U produced by neutron capture in 232 Th is a more valuable fuel for thermal reactors than the plutonium that results from capture in 238 U. These two facts are the main reasons for the interest in utilizing thorium in power reactors. But natural thorium does not contain any fissile material and its capture cross section is nearly two and a half times that of 238 U. These have made the fuelling cost high. However, in certain conditions and certain types of reactors the costs are comparable with those using uranium fuel. The relative cost effectiveness of different fuels is discussed. Apart from long term interest, the short term interest of using thorium fuel in RAPP type reactors is also briefly described. Finally the reactor physics experiments using thorium fuel and their comparison with calculations are presented. (author)

Inhalation exposures at a thorium refinery

International Nuclear Information System (INIS)

Mausner, L.F.

1982-01-01

There is a current interest in the metabolism and health effects of thorium due to its potential use in the 232 Th - 233 U nuclear fuel cycle. The airborne concentrations of thorium, thoron daughters and rare earths in a plant which produced thorium and rare earth chemicals from 1932 to 1973 were calculated from past records of alpha counting and air filter samples. This analysis showed that high airborne concentrations of 232 Th, 220 Rn, 212 Pb, 212 Bi and rare earth elements were sometimes reached during plant operations. Limited measurements on autopsy samples of former employees of the plant showed increased tissue concentrations of thorium and rare earths. (U.K.)

Direct quantification of thorium, uranium and rare earth element concentration in natural waters by ICP-MS

International Nuclear Information System (INIS)

Palmieri, Helena E.L.; Knupp, Eliana A.N.; Auler, Lucia M.L.A.; Gomes, Luiza M.F.; Windmoeller, Claudia C.

2011-01-01

A direct quantification of the thorium, uranium and rare earth elements in natural water samples using inductively coupled plasma mass spectrometry (ICP-MS) was evaluated with respect to selection of isotopes, detection limits, accuracy, precision, matrix effects for each isotope and spectral interferences. Accuracy of the method was evaluated by analysis of Spectra pure Standards (SPS-SW1 Batch 116-Norway) for the rare earth elements (REEs), thorium, uranium, scandium and yttrium. The measurements were carried out for each of the following analytical isotopes: 139 La, 140 Ce, 141 Pr, 143 Nd, 147 Sm, 151 Eu, 160 Gd, 159 Tb, 163 Dy, 165 Ho, 167 Er, 16 9Tm, 174 Yb, 175 Lu, 45 Sc, 89 Y, 232 Th and 238 U. Recovery percentage values found in these certified samples varied between 95 and 107%. The method was applied to the analysis of spring water samples collected in fountains spread throughout the historical towns of Ouro Preto, Mariana, Sabara and Diamantina in the state of Minas Gerais, Brazil. In the past these fountains played an essential and strategic role in supplying these towns with potable water. Until today this water is used by both the local population and tourists who believe in its quality. REE were quantified at levels comparable to those found in estuarine waters, which are characterized by low REE concentrations. In two fountains analyzed the concentration of REEs presented high levels and thus possible health risks for humans may not be excluded. (author)

Validation of main nuclear libraries used in thorium reactors using the Serpent code

International Nuclear Information System (INIS)

Faga, Lucas J.

2017-01-01

The purpose of this work is to validate the library of the Serpent standard database for systems containing U-233, U-235, Th-232, Pu-239 and Pu-240. The project will support the other projects of the newly created study group of Nuclear Engineering Center (CEN) of Instituto de Pesquisas Energéticas e Nucleares (IPEN), linked to the study of several types of reactors and their application in thorium cycles, a subject that gains more and more visibility, due to strong and potential promises of energy revolution. The results obtained at the end of the simulations were satisfactory, with the multiplication factors being effective close to 100 PCM of the values provided by the benchmarks, as expected for a validated library. The minimum distance between these values was 2 PCM and the maximum of 280 PCM. The final analysis demonstrates that the ENDF / B-VII library has validated nuclear data for the isotopes of interest and may be used in future thorium study group projects

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

Thorium-230 contamination

International Nuclear Information System (INIS)

Noey, K.C.; Liedle, S.D.; Hickey, C.R.; Doane, R.W.

1989-01-01

The authors are currently performing radiological surveys on approximately ninety properties in the St. Louis, Missouri area as part of the U.S. Department of Energy's Formerly Utilized Sites Remedial Action Program. The properties involved are the St. Louis Airport Site, Latty Avenue Properties, St. Louis Downtown Site, Coldwater Creek, and the associated roads and vicinity properties. The primary radioactive contaminant on these properties is thorium-230. Since field instrumentation is not available to detect the presence of alpha-emitting contamination in soil, soil samples are being collected and sent to an analytical laboratory for analysis. Thorium-230 analysis is costly and time-consuming, and as a result, soil sample analysis results are not available to help direct the field sampling program. This paper provides discussion of the manner in which the properties became radioactively contaminated, followed by a discussion of the difficulties associated with the detection of thorium-230. Finally, new methodologies for detecting alpha-emitting radionuclides in the field are described

Thoron and associated risks in the handling of thorium compounds; Le thoron et les risques associes dans la manipulation des composes du thorium

Energy Technology Data Exchange (ETDEWEB)

Pradel, J; Billard, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-07-01

1. Thorium compounds continually give off thoron and its daughters and their radioactivity can constitute a danger for operators who may inhale them. 2. By analogy with radon the maximum admissible content in air of thoron and its daughters has been set at 10{sup -7} {mu}c/cm{sup 3}. However the differences in behaviour between radon and its active deposit on the one hand, and thoron and its daughters on the other, appear great enough to justify more thorough investigation. In fact it seemed probable that, contrary to what takes place with radon, the thoron + thorium A content at a given point may differ appreciable from the thorium B + thorium C + thorium C' + thorium C'' content at the same point, because of the considerable differences in half-life which allow a greater or lesser distribution. 3. To determine the relative concentrations it was necessary to develop a method for estimating thoron in equilibrium with thorium A, the measurement of thorium B and its daughters being carried out in the conventional way by counting the activity collected on a filter. 4. Another object of this study was to estimate the danger presented by thoron in equilibrium with thorium A in the immediate vicinity of thorium sources, in a plant extracting thorium from urano-thorianite. (author) [French] 1. Le thoron et ses descendants se degagent constamment des composes du thorium et leur radioactivite peut presenter un danger pour les personnes qui sont amenees a les respirer. 2. Par analogie avec le radon, la teneur maximum admissible dans l'air de thoron et de ses descendants a ete fixee a 10{sup -7} {mu}c/cm{sup 3}. Mais, les differences de comportement du radon et de son depot actif d'une part, du thoron et de ses descendants d'autre part, ont paru suffisantes pour justifier une etude plus complete. Il semblait en effet probable, contrairement a ce qui se produit pour le radon, qu'en un meme point, la teneur en thoron + thorium A puisse differer notablement de la teneur en

Thoron and associated risks in the handling of thorium compounds; Le thoron et les risques associes dans la manipulation des composes du thorium

Energy Technology Data Exchange (ETDEWEB)

Pradel, J.; Billard, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-07-01

1. Thorium compounds continually give off thoron and its daughters and their radioactivity can constitute a danger for operators who may inhale them. 2. By analogy with radon the maximum admissible content in air of thoron and its daughters has been set at 10{sup -7} {mu}c/cm{sup 3}. However the differences in behaviour between radon and its active deposit on the one hand, and thoron and its daughters on the other, appear great enough to justify more thorough investigation. In fact it seemed probable that, contrary to what takes place with radon, the thoron + thorium A content at a given point may differ appreciable from the thorium B + thorium C + thorium C' + thorium C'' content at the same point, because of the considerable differences in half-life which allow a greater or lesser distribution. 3. To determine the relative concentrations it was necessary to develop a method for estimating thoron in equilibrium with thorium A, the measurement of thorium B and its daughters being carried out in the conventional way by counting the activity collected on a filter. 4. Another object of this study was to estimate the danger presented by thoron in equilibrium with thorium A in the immediate vicinity of thorium sources, in a plant extracting thorium from urano-thorianite. (author) [French] 1. Le thoron et ses descendants se degagent constamment des composes du thorium et leur radioactivite peut presenter un danger pour les personnes qui sont amenees a les respirer. 2. Par analogie avec le radon, la teneur maximum admissible dans l'air de thoron et de ses descendants a ete fixee a 10{sup -7} {mu}c/cm{sup 3}. Mais, les differences de comportement du radon et de son depot actif d'une part, du thoron et de ses descendants d'autre part, ont paru suffisantes pour justifier une etude plus complete. Il semblait en effet probable, contrairement a ce qui se produit pour le radon, qu'en un meme point, la teneur en thoron + thorium A puisse

Equipment for the handling of thorium materials

International Nuclear Information System (INIS)

Heisler, S.W. Jr.; Mihalovich, G.S.

1988-01-01

The Feed Materials Production Center (FMPC) is the United States Department of Energy's storage facility for thorium. FMPC thorium handling and overpacking projects ensure the continued safe handling and storage of the thorium inventory until final disposition of the materials is determined and implemented. The handling and overpacking of the thorium materials requires the design of a system that utilizes remote handling and overpacking equipment not currently utilized at the FMPC in the handling of uranium materials. The use of remote equipment significantly reduces radiation exposure to personnel during the handling and overpacking efforts. The design system combines existing technologies from the nuclear industry, the materials processing and handling industry and the mining industry. The designed system consists of a modified fork lift truck for the transport of thorium containers, automated equipment for material identification and inventory control, and remote handling and overpacking equipment for material identification and inventory control, and remote handling and overpacking equipment for repackaging of the thorium materials

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)

Uranium series disequilibrium: application to studies of the groundwater regime of the Harwell region

International Nuclear Information System (INIS)

Ivanovich, M.; Alexander, J.

1985-03-01

Regional groundwater systems incorporating argillaceous formations beneath the Harwell site have been studied as part of a national research programme of investigation into the feasibility of disposal of low and intermediate radioactive wastes into argillaceous rocks. The principal aim of the programme is to establish the groundwater flow patterns using hydrogeological and geochemical methods in association with isotope contents and uranium series disequilibrium and thus provide an independent approach to the study of effective permeabilities of clay lithologies in a sedimentary sequence. Thirty four groundwater samples derived from the high permeability formations in the Harwell region have been analysed for uranium and thorium content and 234 U/ 238 U, 230 Th/ 234 U and 230 Th/ 232 Th activity ratios. The uranium isotopic signatures have been interpreted in terms of the regional groundwater circulation and mixing patterns. The most significant zones of groundwater mixing determined from uranium isotopic data are situated just beneath the edge of the confined strata. These zones coincide with the locations of hydraulic lows in the Great Oolite and the Corallian formations towards which the regional groundwaters move. It is concluded that the uranium isotopic signatures can be used to identify water masses and to evaluate mixing of groundwaters in a sedimentary sequence on a regional scale. (author)

Safety and Regulatory Issues of the Thorium Fuel Cycle

Energy Technology Data Exchange (ETDEWEB)

Ade, Brian [ORNL; Worrall, Andrew [ORNL; Powers, Jeffrey [ORNL; Bowman, Steve [ORNL; Flanagan, George [ORNL; Gehin, Jess [ORNL

2014-02-01

Thorium has been widely considered an alternative to uranium fuel because of its relatively large natural abundance and its ability to breed fissile fuel (233U) from natural thorium (232Th). Possible scenarios for using thorium in the nuclear fuel cycle include use in different nuclear reactor types (light water, high temperature gas cooled, fast spectrum sodium, molten salt, etc.), advanced accelerator-driven systems, or even fission-fusion hybrid systems. The most likely near-term application of thorium in the United States is in currently operating light water reactors (LWRs). This use is primarily based on concepts that mix thorium with uranium (UO2 + ThO2), add fertile thorium (ThO2) fuel pins to LWR fuel assemblies, or use mixed plutonium and thorium (PuO2 + ThO2) fuel assemblies. The addition of thorium to currently operating LWRs would result in a number of different phenomenological impacts on the nuclear fuel. Thorium and its irradiation products have nuclear characteristics that are different from those of uranium. In addition, ThO2, alone or mixed with UO2 fuel, leads to different chemical and physical properties of the fuel. These aspects are key to reactor safety-related issues. The primary objectives of this report are to summarize historical, current, and proposed uses of thorium in nuclear reactors; provide some important properties of thorium fuel; perform qualitative and quantitative evaluations of both in-reactor and out-of-reactor safety issues and requirements specific to a thorium-based fuel cycle for current LWR reactor designs; and identify key knowledge gaps and technical issues that need to be addressed for the licensing of thorium LWR fuel in the United States.

Thorium Th

International Nuclear Information System (INIS)

Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

1978-01-01

The basic methods for extracting thorium from monazites and determining it photometrically and complexometrically are described. Monazite is decomposed by fusion with sodium peroxide, then thorium and the totality of lanthanides are precipitated in the form of oxalates. After the oxalates have been broken down, thorium is determined photometrically with the aid of arsenazo 1, quercetin of 1-2(-pyridylazo)-resorcin. It takes 25 to 30 minutes to photometrically determine Th in monazites with the aid of arsenazo 2 (error: 3 to 5%). Arsenazo 2 is recommended for analysis of monazites containing 20 to 30% of lanthanides. Arsenazo 3 permits determining Th in zircon and in Nb-containing materials. In this case, the determination is possible in strongly acidic solutions, the ratio of arsenazo 3 to Th being 7.5:1. Arsenazo 3 can also be used in determining trace amounts of Th (1x10 -5 to 1x10 -4 %) in rocks, as well as in extraction-photometric determination of Th traces. The dyed compound of Th with arsenazo 3 is extracted with isoamyl alcohol in the presence of diphenylguanidinium chloride and monochloroacetic acid. The method permits determining Th at 1:5x10 8 (0.002 g/ml) dilution. Also described is the iodate-complexometric method for determining Th

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)

Thorium in occupationally exposed men

International Nuclear Information System (INIS)

Stehney, A. F.

1999-01-01

Higher than environmental levels of 232 Th have been found in autopsy samples of lungs and other organs from four former employees of a thorium refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Examination of the distribution of thorium among the organs revealed poor agreement with the distribution calculated from the dosimetric models in Publication 30 of the International Commission on Radioprotection (ICRP). Concentrations in the lungs relative to pulmonary lymph nodes, bone or liver were much higher than calculated from the model for class Y thorium and the exposure histories of the workers. Much better agreement was found with more recently proposed models in Publications 68 and 69 of the ICRP. Radiation doses estimated from the amounts of thorium in the autopsy samples were compatible with health studies that found no significant difference in mortality from that of the general population of men in the US

Experimental studies of thorium ion implantation from pulse laser plasma into thin silicon oxide layers

Science.gov (United States)

Borisyuk, P. V.; Chubunova, E. V.; Lebedinskii, Yu Yu; Tkalya, E. V.; Vasilyev, O. S.; Yakovlev, V. P.; Strugovshchikov, E.; Mamedov, D.; Pishtshev, A.; Karazhanov, S. Zh

2018-05-01

We report the results of experimental studies related to implantation of thorium ions into thin silicon dioxide by pulsed plasma flux expansion. Thorium ions were generated by laser ablation from a metal target, and the ionic component of the laser plasma was accelerated in an electric field created by the potential difference (5, 10 and 15 kV) between the ablated target and a SiO2/Si (0 0 1) sample. The laser ablation system installed inside the vacuum chamber of the electron spectrometer was equipped with a YAG:Nd3  +  laser having a pulse energy of 100 mJ and time duration of 15 ns in the Q-switched regime. The depth profile of thorium atoms implanted into the 10 nm thick subsurface areas together with their chemical state as well as the band gap of the modified silicon oxide at different conditions of implantation processes were studied by means of x-ray photoelectron spectroscopy and reflected electron energy loss spectroscopy methods. Analysis of the chemical composition showed that the modified silicon oxide film contains complex thorium silicates. Depending on the local concentration of thorium atoms, the experimentally established band gaps were located in the range 6.0–9.0 eV. Theoretical studies of the optical properties of the SiO2 and ThO2 crystalline systems were performed by ab initio calculations within hybrid functional. The optical properties of the SiO2/ThO2 composite were interpreted on the basis of the Bruggeman effective medium approximation. A quantitative assessment of the yield of isomeric nuclei in ‘hot’ laser plasma at the early stages of expansion was performed. The estimates made with experimental results demonstrated that the laser implantation of thorium ions into the SiO2 matrix can be useful for further research of low-lying isomeric transitions in a 229Th isotope with energy of 7.8 +/- 0.5 eV.

Model Matematik Reduksi Thorium dalam Proses Elektrokoagulasi

Directory of Open Access Journals (Sweden)

Prayitno

2017-11-01

Full Text Available Thorium reduction by electrocoagulation has been conducted on radioactive waste with thorium contaminant grade of 5x10-4Kg/l through a batch system using aluminium electrodes. This study aims to determine a mathematical model of thorium reduction through speed reaction, constante reaction rate and reaction order which are affected by electrocoagulation process parameters like voltage, time, electrode distance, and pH. The research results the optimum voltage condition at 12.5 V at 1 cm electrode spacing, pH 7, and 30 minutes of processing time with 99.6 % efficiency. Prediction on thorium decline rate constante is obtained through mathematic integral method calculation. The research results thorium decline rate is following second order constante with its value at 5x10-3KgL-1min-1.

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

Status and development of the thorium fuel cycle

International Nuclear Information System (INIS)

Yi Weijing; Wei Renjie

2003-01-01

A perspective view of the thorium fuel cycle is provided in this paper. The advantages and disadvantages of the thorium fuel cycle are given and the development of thorium fuel cycle in several types of reactors is introduced. The main difficulties in developing the thorium fuel cycle lie in the reprocessing and disposal of the waste and its economy, and the ways tried by foreign countries to solve the problems are presented in the paper

Contribution of lead and thorium to the history of the Oklo reactors

International Nuclear Information System (INIS)

Devillers, C.; Menes, J.

1978-01-01

The authors report the results of measuring lead and thorium in a series of representative samples of the superconcentrations of uranium found in the Oklo mineralization. Interpretation of the data reveals the complexity of the history of lead in the deposit, but makes it possible to derive a number of important facts, namely early disturbance and recent, massive remobilization of lead. One is led to conclude that the date of the uranium emplacement may be greater than 1900 million years. The absence of high thorium contents in the ''normal'' rich ore confirms the importance of dating the nuclear reaction on the basis of the Th/U balance. This determination, which draws on the same set of data as for the Nd/U balance, gives a mean value close to 1930 million years. (author)

U.S. leans toward denatured thorium cycle

International Nuclear Information System (INIS)

Smock, R.

1977-01-01

Denatured thorium appears to be the most promising among the nonproliferating alternatives to the plutonium cycle, which the Carter Administration is trying to cancel. Criteria for a better system include uranium utilization comparable to current light water reactors and minimal separation of fissile material into the waste stream. Comparisons with other systems conclude that thorium is preferable because it can lead to an acceptable fast breeder. The thorium cycle can be placed in energy centers for sensitive facilities and can also be introduced into ongoing light water systems. Reprocessing can be handled in the centers, where thorium can be mixed with plutonium for use in reactors within the center, while light water reactors operate on the outside. Any fuel leaving the center would be unsuitable for weapons. Later adaptation to in-center fast breeders will extend energy supplies, although a thorium breeder will be less efficient than a plutonium fast breeder. Denatured thorium is a technical answer to a complex political problem, but those in the nuclear industry see the U.S. goal of a nonproliferating fuel as futile in the light of world politics and breeder efforts in other countries

Behavior of uranium and thorium isotopes in soils of the Boreon area, Mercantour Massif (S.E. France). Leaching and weathering rate modeling

International Nuclear Information System (INIS)

Rezzoug, S.; Michel, H.; Barci-Funel, G.; Barci, V.; Fernex, F.

2009-01-01

Four cores were collected in weathered rocks and soils in the Boreon forest area (1765 m, Mercantour Massif, France). The samples were analyzed for the isotopes 230 Th, 232 Th, 234 U and 238 U. The activity and isotopic ratio profiles suggest that uranium was mobilized (leaching and precipitation) during the weathering process, as well as thorium but in a much less proportion. A model was drawn up to evaluate the U leaching rate and the time that some levels of the weathered rocks have been subjected to weathering. It utilizes LATHAM and SCHWARCZ's two equations,15 expressed as 234 U/ 238 U and 230 Th/ 238 U activity ratios, which assume that the alpha recoil effect allows easier leaching for 234 U than 238 U and no Th mobility. But this last assumption does not correspond to the observations made in the Boreon area, since it appears that in some soil deeper layers 230 Th and 228 Th are in radioactive deficit relatively to their parents. As there are four unknown quantities (the time, the leaching rates of 238 U, 234 U, 230 Th), the problem to be solved requires two more equations; these can be obtained utilizing the U activity ratio in water, and taking into account the 232 Th behavior. In some sites the 238 U leaching rate is high in deeper soil levels (near the fresh rocks); this would correspond to a loss of half the U amount in less than 24 000 years. (author)

Thoron and associated risks in the handling of thorium compounds

International Nuclear Information System (INIS)

Pradel, J.; Billard, F.

1959-01-01

1. Thorium compounds continually give off thoron and its daughters and their radioactivity can constitute a danger for operators who may inhale them. 2. By analogy with radon the maximum admissible content in air of thoron and its daughters has been set at 10 -7 μc/cm 3 . However the differences in behaviour between radon and its active deposit on the one hand, and thoron and its daughters on the other, appear great enough to justify more thorough investigation. In fact it seemed probable that, contrary to what takes place with radon, the thoron + thorium A content at a given point may differ appreciable from the thorium B + thorium C + thorium C' + thorium C'' content at the same point, because of the considerable differences in half-life which allow a greater or lesser distribution. 3. To determine the relative concentrations it was necessary to develop a method for estimating thoron in equilibrium with thorium A, the measurement of thorium B and its daughters being carried out in the conventional way by counting the activity collected on a filter. 4. Another object of this study was to estimate the danger presented by thoron in equilibrium with thorium A in the immediate vicinity of thorium sources, in a plant extracting thorium from urano-thorianite. (author) [fr

Gas-Cooled Thorium Reactor with Fuel Block of the Unified Design

Directory of Open Access Journals (Sweden)

Igor Shamanin

2015-01-01

Full Text Available Scientific researches of new technological platform realization carried out in Russia are based on ideas of nuclear fuel breeding in closed fuel cycle and physical principles of fast neutron reactors. Innovative projects of low-power reactor systems correspond to the new technological platform. High-temperature gas-cooled thorium reactors with good transportability properties, small installation time, and operation without overloading for a long time are considered perspective. Such small modular reactor systems at good commercial, competitive level are capable of creating the basis of the regional power industry of the Russian Federation. The analysis of information about application of thorium as fuel in reactor systems and its perspective use is presented in the work. The results of the first stage of neutron-physical researches of a 3D model of the high-temperature gas-cooled thorium reactor based on the fuel block of the unified design are given. The calculation 3D model for the program code of MCU-5 series was developed. According to the comparison results of neutron-physical characteristics, several optimum reactor core compositions were chosen. The results of calculations of the reactivity margins, neutron flux distribution, and power density in the reactor core for the chosen core compositions are presented in the work.

Thorium as an energy source. Opportunities for Norway

International Nuclear Information System (INIS)

2008-01-01

Final Recommendations of the Thorium Report Committee: 1) No technology should be idolized or demonized. All carbon-dioxide (Co2) emission-free energy production technologies should be considered. The potential contribution of nuclear energy to a sustainable energy future should be recognized. 2) An investigation into the resources in the Fen Complex and other sites in Norway should be performed. It is essential to assess whether thorium in Norwegian rocks can be defined as an economical asset for the benefit of future generations. Furthermore, the application of new technologies for the extraction of thorium from the available mineral sources should be studied. 3) Testing of thorium fuel in the Halden Reactor should be encouraged, taking benefit of the well recognized nuclear fuel competence in Halden. 4) Norway should strengthen its participation in international collaborations by joining the EURATOM fission program and the GIF program on Generation IV reactors suitable for the use of thorium. 5) The development of an Accelerator Driven System (ADS) using thorium is not within the capability of Norway working alone. Joining the European effort in this field should be considered. Norwegian research groups should be encouraged to participate in relevant international projects, although these are currently focused on waste management. 6) Norway should bring its competence in waste management up to an international standard and collaboration with Sweden and Finland could be beneficial. 7) Norway should bring its competence with respect to dose assessment related to the thorium cycle up to an international standard. 8) Since the proliferation resistance of uranium-233 depends on the reactor and reprocessing technologies, this aspect will be of key concern should any thorium reactor be built in Norway. 9) Any new nuclear activities in Norway, e.g. thorium fuel cycles, would need strong international pooling of human resources, and in the case of thorium, a strong long

Thorium as an energy source. Opportunities for Norway

Energy Technology Data Exchange (ETDEWEB)

2008-01-15

Final Recommendations of the Thorium Report Committee: 1) No technology should be idolized or demonized. All carbon-dioxide (Co2) emission-free energy production technologies should be considered. The potential contribution of nuclear energy to a sustainable energy future should be recognized. 2) An investigation into the resources in the Fen Complex and other sites in Norway should be performed. It is essential to assess whether thorium in Norwegian rocks can be defined as an economical asset for the benefit of future generations. Furthermore, the application of new technologies for the extraction of thorium from the available mineral sources should be studied. 3) Testing of thorium fuel in the Halden Reactor should be encouraged, taking benefit of the well recognized nuclear fuel competence in Halden. 4) Norway should strengthen its participation in international collaborations by joining the EURATOM fission program and the GIF program on Generation IV reactors suitable for the use of thorium. 5) The development of an Accelerator Driven System (ADS) using thorium is not within the capability of Norway working alone. Joining the European effort in this field should be considered. Norwegian research groups should be encouraged to participate in relevant international projects, although these are currently focused on waste management. 6) Norway should bring its competence in waste management up to an international standard and collaboration with Sweden and Finland could be beneficial. 7) Norway should bring its competence with respect to dose assessment related to the thorium cycle up to an international standard. 8) Since the proliferation resistance of uranium-233 depends on the reactor and reprocessing technologies, this aspect will be of key concern should any thorium reactor be built in Norway. 9) Any new nuclear activities in Norway, e.g. thorium fuel cycles, would need strong international pooling of human resources, and in the case of thorium, a strong long

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.)

Determination of boron spectrophotometry in thorium sulfate

International Nuclear Information System (INIS)

Federgrun, L.; Abrao, A.

1976-01-01

A procedure for the determination of microquantities of boron in nuclear grade thorium sulfate is described. The method is based on the extraction of BF - 4 ion associated to monomethylthionine (MMT) in 1,2 - dichloroethane. The extraction of the colored BF - 4 -MMT complex does not allow the presence of sulfuric and phosphoric acids; other anions interfere seriously. This fact makes the dissolution of the thorium sulfate impracticable, since it is insoluble in both acids. On the other hand, the quantitative separation of thorium is mandatory, to avoid the precipitation of ThF 4 . To overcome this difficulty, the thorium sulfate is dissolved using a strong cationic ion exchanger, Th 4+ being totally retained into the resin. Boron is then analysed in the effluent. The procedure allows the determination of 0.2 to 10.0 microgramas of B, with a maximum error of 10%. Thorium sulfate samples with contents of 0.2 to 2.0μg B/gTh have being analysed [pt

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)

Radioisotope dilution analyses of geological samples using 236U and 229Th

International Nuclear Information System (INIS)

Rosholt, J.N.

1984-01-01

The use of 236 U and 229 Th in alpha spectrometric measurements has some advantages over the use of other tracers and measurement techniques in isotope dilution analyses of most geological samples. The advantages are: 1) these isotopes do not occur in terrestrial rocks, 2) they have negligible decay losses because of their long half lives, 3) they cause minimal recoil contamination to surface-barrier detectors, 4) they allow for simultaneous determination of the concentration and isotopic composition of uranium and thorium in a variety of sample types, and 5) they allow for simple and constant corrections for spectral interferences, 0.5% of the 238 U activity is subtracted for the contribution of 235 U in the 236 U peak and 1% of the 229 Th activity is subtracted from the 230 Th activity. Disadvantages in using 236 U and 229 Th are: 1) individual separates of uranium and thorium must be prepared as very thin sources for alpha spectrometry, 2) good resolution in the spectrometer system is required for thorium isotopic measurements where measurement times may extend to 300 h, and 3) separate calibrations of the 236 U and 229 Th spike solution with both uranium and thorium standards are required. The use of these tracers in applications of uranium-series disequilibrium studies has simplified the measurements required for the determination of the isotopic composition of uranium and thorium because of the minimal corrections needed for alpha spectral interferences. (orig.)

Radioisotope dilution analyses of geological samples using 236U and 229Th

Science.gov (United States)

Rosholt, J.N.

1984-01-01

The use of 236U and 229Th in alpha spectrometric measurements has some advantages over the use of other tracers and measurement techniques in isotope dilution analyses of most geological samples. The advantages are: (1) these isotopes do not occur in terrestrial rocks, (2) they have negligible decay losses because of their long half lives, (3) they cause minimal recoil contamination to surface-barrier detectors, (4) they allow for simultaneous determination of the concentration and isotopic composition of uranium and thorium in a variety of sample types, and (5) they allow for simple and constant corrections for spectral inferences, 0.5% of the 238U activity is subtracted for the contribution of 235U in the 236U peak and 1% of the 229Th activity is subtracted from the 230Th activity. Disadvantages in using 236U and 229Th are: (1) individual separates of uranium and thorium must be prepared as very thin sources for alpha spectrometry, (2) good resolution in the spectrometer system is required for thorium isotopic measurements where measurement times may extend to 300 h, and (3) separate calibrations of the 236U and 229Th spike solution with both uranium and thorium standards are required. The use of these tracers in applications of uranium-series disequilibrium studies has simplified the measurements required for the determination of the isotopic composition of uranium and thorium because of the minimal corrections needed for alpha spectral interferences. ?? 1984.

Recovering of thorium contained in wastes from Thorium Purification Plant; Reaproveitamento do torio contido em residuos provenientes da Usina de Purificacao do Torio

Energy Technology Data Exchange (ETDEWEB)

Brandao Filho, D; Hespanhol, E C.B.; Baba, S; Miranda, L E.T.; Araujo, J.A. de

1992-08-01

A study has been developed in order to establish a chemical process for recovering thorium from wastes produced at the Thorium Purification Plant of the Instituto de Pesquisas Energeticas e Nucleares. The recovery of thorium in this process will be made by means of solvent extraction technique. Solutions of TBP/Varsol were employed as extracting agent during the runs. The influence of thorium concentration in the solution, aqueous phase acidity, volume ratio of the phases, percentage of TBP/Varsol and the contact time of the phases on the extraction of thorium and lanthanides was determined. (author).

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.

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

Polarographic determination of trace amounts of thorium

Energy Technology Data Exchange (ETDEWEB)

Zaofan Zhao; Xiaohua Cai; Peibiao Li; Handong Yang

1986-07-01

A sensitive linear-sweep polarographic method for the determination of thorium is described. It is based on the thorium complex with Xylidyl Blue I (XBI) in a medium containing ethylenediamine, 1, 10-phenanthroline, oxalic acid and ninhydrin, at pH 10.5-11.5. The complex has been proved to be Th(XBI)/sub 2/, with log ..beta..'=9.6. The method can be used to determine trace amounts of thorium over the range 3.5x10/sup -8/-3x10/sup -6/M. The detection limit is 1x10/sup -8/M. A solvent extraction procedure is necessary to eliminate interference from several cations. The method has been applied to determination of traces of thorium in minerals, with good results.

Present state and perspective of research on thorium cycle

International Nuclear Information System (INIS)

Kimura, Itsuro

1994-01-01

For the prosperity of Japan and the welfare of mankind in the world, enormous quantity of energy is required in 21st century, and the general circumstances of energy and nuclear power are described. In addition to the present nuclear power using mostly 235 U and the plutonium produced from 238 U, it is the thorium cycle that 233 U produced from the third nuclear fuel, thorium, is used for electric power generation as an energy source. In this report, the 'General research on thorium cycle as a promising energy source in and after 21st century' is outlined, which has been advanced by accepting the subsidy of scientific research expense of the Ministry of Education. The features of the thorium cycle and the nuclear data and the nuclear characteristics in comparison with uranium-plutonium reactors are described. The trend of the research and development in the world and in Japan is reported. Two general researches were carried out for five years from fiscal year 1988 to 1992 on the thorium cycle. The results of the research on the nuclear data, the design of thorium reactors, the criticality experiment and analysis, thorium hybrid, thorium fuel, molten salt, fuel reprocessing and radiation safety are reported. (K.I.)

Extractive spectrophotometric determination of thorium

International Nuclear Information System (INIS)

Venkatesan, M.; Gopalakrishnan, V.; Ramanujam, A.; Nadkarni, M.N.

1981-01-01

An extractive spectrophotometric method has been standardized for the analysis of 0.2 to 1.6 milligrams of thorium present in nitric acid solutions. The method involves the extraction of thorium from nitric acid solutions into 0.5 M thenoyl trifluoro acetone (HTTA) in benzene and its direct estimation from the organic extract by spectrophotometry as Thoron colour complex. In this method, interference due to iron upto 5 milligrams can be suppressed by adding ascorbic acid in the ratio of 1:2 prior to HTTA extraction. Uranium(VI) does not interefere even when present in 2000 times the amount of thorium. Plutonium and cerium do not interfere at one milligram level whereas zirconium interferes in this method. The overall error variation and precision of this method has been determined to be +- 3.5%. (author)

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

Distribution of uranium and thorium isotopes in iron-manganese concretions of the Pacific ocean

International Nuclear Information System (INIS)

Kuznetsov, V.Yu.; Andreev, S.I.

1995-01-01

Distribution of 238 U, 234 U, 232 Th, 230 Th in cross sections of samples from the Pacific Ocean iron-manganese concretions (IMC) of different genetic types has been studied, the results are presented. Possible influence of diagenetic processes in the deposits mentioned on distribution of the radionuclides in iron-manganese septarian nodules has been considered. The assumption is made that remobilization of Mn, Ni, Cu from IMC containing deposits does not upset uranium and thorium distribution in the concretions resulted from sedimentation mechanism of their formation. 18 refs., 3 tabs

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

International Nuclear Information System (INIS)

Steinhaeusler, F.; Zaitseva, L.

2005-01-01

several of the following pre-requisites in order to breach the current level of security at mining and milling facilities: covert political support; covert support by members of the security forces and/or intelligence community; adequate transport capability for bulk shipments or material by rail, road, ship, or air; corruption at the level of government officials, such as export control agencies, customs officers, and border guards. The number of illicit trafficking cases involving uranium and thorium that are known to have occurred shows that the current system of physical protection and accounting is in need of improvement. In order to reduce this risk in the future a series of practically applicable actions are recommended. (author)

Thorium: An energy source for the world of tomorrow ?

CERN Multimedia

CERN. Geneva

2014-01-01

To meet the tremendous world energy needs, systematic R&D has to be pursued to replace fossil fuels. The ThEC13 conference organized by iThEC at CERN last October has shown that thorium is seriously considered by developing countries as a key element of their energy strategy. Developed countries are also starting to move in the same direction. How thorium could make nuclear energy (based on thorium) acceptable to society will be discussed. Thorium can be used both to produce energy and to destroy nuclear waste. As thorium is not fissile, one elegant option is to use an accelerator, in so-called “Accelerator Driven Systems (ADS)”, as suggested by Carlo Rubbia. CERN’s important contributions to R&D on thorium related issues will be mentioned as well as the main areas where CERN could contribute to this field in the future.

Thorium oxide dissolution kinetics for hydroxide and carbonate complexation

International Nuclear Information System (INIS)

Jardin, R.; Curran, V.; Czerwinski, K.R.

2002-01-01

The purpose of this project was to determine the kinetics and thermodynamics of thorium oxide dissolution in the environment. Solubility is important because it establishes an upper concentration limit on the concentration of a dissolved radionuclide in solution L1. While understanding the behavior of thorium fuels in the proposed repository at Yucca Mountain is most applicable, a more rigorous study of thorium solubility over a wide pH range was performed so that the data could also be used to model the behavior of thorium fuels in any environmental system. To achieve this, the kinetics and thermodynamics of thorium oxide dissolution under both pure argon and argon with P CO2 of 0. 1 were studied under the full pH range available in each atmosphere. In addition, thorium oxide powder remnants were studied after each experiment to examine structural changes that may affect kinetics

Sequential determination of environmental levels of isotopic thorium, uranium and the light rare earth elements within the terrestrial food chain by induced coupled plasma (ICP) and alpha spectrometry

International Nuclear Information System (INIS)

Linsalata, P.; Morse, R.; Ford, H.

1986-01-01

A radioecological study designed to measure soil to plant and soil to animal (livestock) transfer of Th, U, Ra and the light rare earth elements (REE) in typical and naturally-enhanced radiation environments required the development of radiochemical methods suitable for low-level determinations in a broad suite of environmental matrices including soil, edible vegetables and vegetation, and the major organs and tissues of various livestock. Earlier work has demonstrate the reliability of the methods summarized here for measuring the isotopic thorium and REE content of human feces, and that in the edible portions of various vegetables grown under field conditions. The very high degree of biological discrimination against Th and REE uptake in plants as well as in animal soft tissues necessitated the analysis of typical sample masses of 1-4 kg (fresh weight) to insure reasonably precise (eg., 10-20%) concentration estimates for most of the elements and isotopes of interest. As a result of the ''bone-seeking'' nature and relatively long retention times for these elements in skeletal tissue, typical analytical masses required for analysis of bone range from 40 to 70 g (fresh weight) except for the REE's in which a larger aliquot is recommended when determination is by induced coupled plasma spectrometry

A survey of thorium utilization in thermal power reactors

International Nuclear Information System (INIS)

Oosterkamp, W.J.

1974-01-01

The present status of thorium utilization in thermal reactors HTGR's, HWR's and LWR's has been reviewed. Physics considerations are made to obtain the optimum use of thorium. Existing information on reprocessing and refabrication is given together with the properties of thorium metal and thoria

Atmospheric dust contribution to budget of U-series nuclides in weathering profiles. The Mount Cameroon volcano

Science.gov (United States)

Pelt, E.; Chabaux, F. J.; Innocent, C.; Ghaleb, B.

2009-12-01

, the dust contribution will not significantly influence U-series dating. Chabaux F., Bourdon B., Riotte J. (2008). U-series Geochemistry in weathering profiles, river waters and lakes. Radioactivity in the Environment, 13, 49-104. Dia A., Chauvel C., Bulourde M. and Gérard M. (2006). Eolian contribution to soils on Mount Cameroon: Isotopic and trace element records. Chem. Geol. 226, 232-252. Rydell H.S. and Prospero J.M. (1972). Uranium and thorium concentrations in wind-borne Saharan dust over the western equatorial north atlantic ocean. EPSL 14, 397-402.

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.)

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

Uranium and thorium nuclides series determined in medicinal plants commonly used in Brazil

Energy Technology Data Exchange (ETDEWEB)

Silva, P.; Francisconi, L.; Damatto, S. [IPEN/CNEN-SP, Sao Paulo (Brazil)

2014-07-01

In recent years the study of medicinal plants has become the focus of ever more extensive research all over the world due to their diversity and potential as source of medicinal products. According to the World Health Organization approximately 80% of world population makes use of medicinal herbs due to their believed therapeutic action. Besides being used as medicine, medicinal plants are also largely used as dietary supplements. The presence of radionuclides in plants constitutes one of the main pathways for their transfer to man. The amount of radioactive nuclides from U and Th series in edible vegetables are relatively well known since they have been the main concern of research conducted worldwide. Medicinal plants, on the other hand, have been neglected in these studies, possibly because the ingestion of radioactive material through their consumption has not been recognized or was considered insignificant. The objective of the present study was to determine the content of natural radionuclides from {sup 238}U and {sup 232}Th series in 25 species of medicinal plants used in Brazil, both as medicine and as dietary supplement. The medicinal plant samples were obtained in specialized pharmacies and drugstores. The raw plant and their extracts, produced as recommended by the National Agency for Sanitary Vigilance, were analyzed by Instrumental Neutron Activation Analyses for the determination of U and Th and by Total Alpha and Beta Counting after Radiochemical Separation for determination of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb. In the raw plants the activity concentrations varied from 0,08 Bq kg{sup -1} to 8,0 Bq kg{sup -1} for thorium, from < LID to 22 Bq kg{sup -1} for uranium, from 1,8 Bq kg{sup -1} to 12 Bq kg{sup -1} for {sup 226}Ra, from 33 Bq kg{sup -1} to 74 Bq kg{sup -1} for {sup 228}Ra and from 10 Bq kg{sup -1} to 120 Bq kg{sup -1} for {sup 210}Pb. In the extracts, the activity concentrations varied from 9 mBq kg{sup -1} to 137 mBq kg{sup -1} for Th

Transuranic Waste Burning Potential of Thorium Fuel in a Fast Reactor - 12423

Energy Technology Data Exchange (ETDEWEB)

Wenner, Michael; Franceschini, Fausto; Ferroni, Paolo [Westinghouse Electric Company LLC,Cranberry Township, PA, 16066 (United States); Sartori, Alberto; Ricotti, Marco [Politecnico di Milano, Milan (Italy)

2012-07-01

Westinghouse Electric Company (referred to as 'Westinghouse' in the rest of this paper) is proposing a 'back-to-front' approach to overcome the stalemate on nuclear waste management in the US. In this approach, requirements to further the societal acceptance of nuclear waste are such that the ultimate health hazard resulting from the waste package is 'as low as reasonably achievable'. Societal acceptability of nuclear waste can be enhanced by reducing the long-term radiotoxicity of the waste, which is currently driven primarily by the protracted radiotoxicity of the transuranic (TRU) isotopes. Therefore, a transition to a more benign radioactive waste can be accomplished by a fuel cycle capable of consuming the stockpile of TRU 'legacy' waste contained in the LWR Used Nuclear Fuel (UNF) while generating waste which is significantly less radio-toxic than that produced by the current open U-based fuel cycle (once through and variations thereof). Investigation of a fast reactor (FR) operating on a thorium-based fuel cycle, as opposed to the traditional uranium-based is performed. Due to a combination between its neutronic properties and its low position in the actinide chain, thorium not only burns the legacy TRU waste, but it does so with a minimal production of 'new' TRUs. The effectiveness of a thorium-based fast reactor to burn legacy TRU and its flexibility to incorporate various fuels and recycle schemes according to the evolving needs of the transmutation scenario have been investigated. Specifically, the potential for a high TRU burning rate, high U-233 generation rate if so desired and low concurrent production of TRU have been used as metrics for the examined cycles. Core physics simulations of a fast reactor core running on thorium-based fuels and burning an external TRU feed supply have been carried out over multiple cycles of irradiation, separation and reprocessing. The TRU burning capability as well as

Thorium: An energy source for the world of tomorrow

Directory of Open Access Journals (Sweden)

Revol J.-P.

2015-01-01

Full Text Available To meet the tremendous world energy needs, systematic R&D has to be pursued to replace fossil fuels. Nuclear energy, which produces no green house gases and no air pollution, should be a leading candidate. How nuclear energy, based on thorium rather than uranium, could be an acceptable solution is discussed. Thorium can be used both to produce energy and to destroy nuclear waste. The thorium conference, organized by iThEC at CERN in October 2013, has shown that thorium is seriously considered by some major developing countries as a key element of their energy strategy. However, developed countries do not seem to move fast enough in that direction, while global cooperation is highly desirable in this domain. Thorium is not fissile. Various possible ways of using thorium will be reviewed. However, an elegant option is to drive an “Accelerator Driven System (ADS” with a proton accelerator, as suggested by Nobel Prize laureate Carlo Rubbia .

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)

Practical introduction of thorium fuel cycles

International Nuclear Information System (INIS)

Kasten, P.R.

1982-01-01

The pracitcal introduction of throrium fuel cycles implies that thorium fuel cycles compete economically with uranium fuel cycles in economic nuclear power plants. In this study the reactor types under consideration are light water reactors (LWRs), heavy water reactors (HWRs), high-temperature gas-cooled reactors (HTGRs), and fast breeder reactors (FBRs). On the basis that once-through fuel cycles will be used almost exclusively for the next 20 or 25 years, introduction of economic thorium fuel cycles appears best accomplished by commercial introduction of HTGRs. As the price of natural uranium increases, along with commercialization of fuel recycle, there will be increasing incentive to utilize thorium fuel cycles in heavy water reactors and light water reactors as well as in HTGRs. After FBRs and fuel recycle are commercialized, use of thorium fuel cycles in the blanket of FBRs appears advantageous when fast breeder reactors and thermal reactors operate in a symbiosis mode (i.e., where 233 U bred in the blanket of a fast breeder reactor is utilized as fissile fuel in thermal converter reactors)

Light water reactors with a denatured thorium fuel cycle

International Nuclear Information System (INIS)

1978-05-01

Discussed in this paper is the performance of denatured thorium fuel cycles in PWR plants of conventional design, such as those currently in operation or under construction. Although some improvement in U 3 O 8 utilization is anticipated in PWRs optimized explicitly for the denatured thorium fuel cycle, this paper is limited to a discussion of the performance of denatured thorium fuels in conventional PWRs and consequently the data presented is representative of the use of thorium fuel in existing PWRs or those presently under construction. In subsequent sections of this paper, the design of the PWR, its performance on the denatured thorium fuel cycle, safety, accident and environmental considerations, and technological status and R and D requirements are discussed

Automated methods for thorium determination in liquids, solids and aerosols

International Nuclear Information System (INIS)

Robertson, R.; Stuart, J.E.

1984-01-01

Methodology for determining trace thorium levels in a variety of sample types for compliance purposes was developed. Thorium in filtered water samples is concentrated by ferric hydroxide co-precipitation. Aerosols on glass-fibre, cellulose ester or teflon filters are acid digested and thorium is concentrated by lanthanum fluoride co-precipitation. Chemical separation and measurement are then done on a Technicon AAII-C auto-analyzer via TTA-solvent extraction and colorimetry using the thorium-arsenazo III colour complex. Solid samples are acid digested and thorium is concentrated and separated using lanthanum fluoride co-precipitation followed by anion-exchange chromatography. Measurement is then carried out on the autoanalyzer by direct development of the thorium-arsenazo III colour complex. Chemical yields are determined through the addition of thorium-234 tracer with assay by gamma-ray spectrometry. The sensitivities of the methods for liquids, aerosols and solids are approximately 1μg/L,0.5μg and 0.5 μg/g respectively. At thorium levels about ten times the detection limits, accuracy and reproducibility are typically +-10 percent for liquids and aerosols and +- 15 percent for solid samples

Thorium-particulate matter interaction. Thorium complexing capacity of oceanic particulate matter: Theory

International Nuclear Information System (INIS)

Hirose, Katsumi; Tanque, Eiichiro

1994-01-01

The interaction between thorium and oceanic particulate matter was examined experimentally by using chemical equilibrium techniques. Thorium reacts quantitatively with the organic binding site of Particulate Matter (PM) in 0.1 mol/L HCl solution by complexation, which is equilibrated within 34 h. According to mass balance analysis, thorium forms a 1:1 complex with the organic binding site in PM, whose conditional stability constant is 10 6.6 L/mol. The Th adsorption ability is present even in 6.9 mol/L HCl solution although the amount of Th adsorption decreases with increasing acidity in the solution. Interferences to Th adsorption by Fe(III) suggests that other metals cannot react with PM in more than 0.1 mol/L HCl solutions when concentrations of other metals are the same level of Th. The competitive reaction between Th and Fe(III) occurs in higher Fe concentrations, which means that the organic binding site is nonspecific for Th. A vertical profile of Th complexing capacity of PM in the western North Pacific is characterized; that is, the Th complexing capacity shows a surface maximum and decreases rapidly with depth

Chemistry of titanium, zirconium and thorium picramates

International Nuclear Information System (INIS)

Srivastava, R.S.; Agrawal, S.P.; Bhargava, H.N.

1976-01-01

Picramates of titanium, zirconium and thorium are prepared by treating the aqueous sulphate, chloride and nitrate solutions with sodium picramate. Micro-analysis, colorimetry and spectrophotometry are used to establish the compositions (metal : ligand ratio) of these picramates as 1 : 2 (for titanium and zirconium) and 1 : 4 (for thorium). IR studies indicate H 2 N → Me coordination (where Me denotes the metal). A number of explosive properties of these picramates point to the fact that the zirconium picramate is thermally more stable than the picramates of titanium and thorium. (orig.) [de

Measurement of thorium content in gas mantles produced in India

Energy Technology Data Exchange (ETDEWEB)

Gaur, P K [Bhabha Atomic Research Centre, Mumbai (India). Radiological Physics Div.; Chury, A J; Venkataraman, G [Bhabha Atomic Research Centre, Mumbai (India). Radiation Protection Services Div.

1994-04-01

Incandescent gas mantles, processed with thorium nitrate, were monitored for thorium content, using a 2 inch thick Nal(Tl) detector and detecting medium energy gamma radiations emitted by thorium daughters. Thirty different brands, manufactured in the country have been counted and most of them were found to contain thorium within the permissible limit specified by Atomic Energy Regulatory Board (AERB). (author). 5 refs., 1 fig., 3 tabs.

Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico.

Science.gov (United States)

Goldstein, Steven J; Abdel-Fattah, Amr I; Murrell, Michael T; Dobson, Patrick F; Norman, Deborah E; Amato, Ronald S; Nunn, Andrew J

2010-03-01

Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low ( approximately 10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that (230)Th/(238)U activity ratios range from 0.005 to 0.48 and (226)Ra/(238)U activity ratios range from 0.006 to 113. (239)Pu/(238)U mass ratios for the saturated zone are 1000 times lower than the U mobility. Saturated zone mobility decreases in the order (238)U approximately (226)Ra > (230)Th approximately (239)Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico

International Nuclear Information System (INIS)

Goldstein, S.J.; Abdel-Fattah, A.I.; Murrell, M.T.; Dobson, P.F.; Norman, D.E.; Amato, R.S.; Nunn, A.J.

2009-01-01

Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low (∼10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that 230 Th/ 238 U activity ratios range from 0.005-0.48 and 226 Ra/ 238 U activity ratios range from 0.006-113. 239 Pu/ 238 U mass ratios for the saturated zone are -14 , and Pu mobility in the saturated zone is >1000 times lower than the U mobility. Saturated zone mobility decreases in the order 238 U∼ 226 Ra > 230 Th∼ 239 Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

Proposal and application of methodology for monitoring workers occupationally exposed to Thorium-232 and its decay products

International Nuclear Information System (INIS)

Dantas, Bernardo Maranhao

1993-08-01

Thorium-232 is the parent of one of the naturally occurring decay series and is widely spread on the earth's crust, being also present in higher concentrations at some deposits located mainly in Brazil and India. The occupational exposure to this radionuclide may occur in several steps of the thorium cycle. In Brazil, there is a large number of workers that should be monitored because they manipulate directly or indirectly different kinds of ores, raw materials and products containing significant amounts of thorium in its composition. In this study, the techniques developed specifically for the in vivo and in vitro monitoring of these workers are presented together with the application of these techniques to a group of selected workers classified as occupationally exposed. It is also presented the methodology by which the results obtained with these measurements are interpreted with the objective of identifying the main pathways of incorporation and reducing the internal doses to values as low as reasonably achievable. (author)

Moving towards sustainable thorium fuel cycles

International Nuclear Information System (INIS)

Hyland, B.; Hamilton, H.

2011-01-01

The CANDU reactor has an unsurpassed degree of fuel-cycle flexibility as a consequence of its fuel-channel design, excellent neutron economy, on-power refueling, and simple fuel bundle design. These features facilitate the introduction and full exploitation of thorium fuel cycles in CANDU reactors in an evolutionary fashion. Thoria (ThO 2 ) based fuel offers both fuel performance and safety advantages over urania (UO 2 ) based fuel, due its higher thermal conductivity which results in lower fuel-operating temperatures at similar linear element powers. Thoria fuel has demonstrated lower fission gas release than UO 2 under similar operating powers during test irradiations. In addition, thoria has a higher melting point than urania and is far less reactive in hypothetical accident scenarios owing to the fact that it has only one oxidation state. This paper examines one possible strategy for the introduction of thorium fuel cycles into CANDU reactors. In the short term, the initial fissile material would be provided in a heterogeneous bundle of low-enriched uranium and thorium. The medium term scenario uses homogeneous Pu/Th bundles in the CANDU reactor, further increasing the energy derived from the thorium. In the long term, the full energy potential from thorium would be realized through the recycle of the U-233 in the used fuel. With U-233 recycle in CANDU reactors, plutonium would then only be required to top up the fissile content to achieve the desired burnup. (author)

Interaction between thorium and potential clad materials

International Nuclear Information System (INIS)

Kale, G.B.; Gawde, P.S.; Sengupta, Pranesh

2005-01-01

Thorium based fuels are being used for nuclear reactors. The structural stability of fuel-clad assemblies in reactor systems depend upon the nature of interdiffusion reaction between fuel-cladding materials. Interdiffusion reaction thorium and various cladding materials is presented in this paper. (author)

Environmental and radiological aspects of thorium processing in India

International Nuclear Information System (INIS)

Rudran, Kamala; Paul, A.C.; Pillai, P.M.B.; Saha, S.C.; Vidyasagar, D.; Sawant, Pramilla D.

1997-01-01

India has an active programme for using thorium as third stage self- sustaining nuclear fuel. A significant amount of thorium is also used in the gas mantle industry. The presently estimated monazite deposits amounting to five million tonnes are distributed in the beach sands of south western and eastern coasts and some areas in Andhra Pradesh. The sands are processed for recovery of rare earth minerals and thorium. The mineral processing and thorium separation involves hazards to workers from exposure to radiation, radioactive and silica bearing dusts as well as from conventional chemicals used in the processing. Releases of wastes from the plants may necessitate environmental surveillance. The present paper reviews the hazards envisaged, steps taken to mitigate such hazards and achievements in this regard in the thorium industry in India. (author)

Large-scale nuclear energy from the thorium cycle

International Nuclear Information System (INIS)

Lewis, W.B.; Duret, M.F.; Craig, D.S.; Veeder, J.I.; Bain, A.S.

1973-02-01

The thorium fuel cycle in CANDU (Canada Deuterium Uranium) reactors challenges breeders and fusion as the simplest means of meeting the world's large-scale demands for energy for centuries. Thorium oxide fuel allows high power density with excellent neutron economy. The combination of thorium fuel with organic caloporteur promises easy maintenance and high availability of the whole plant. The total fuelling cost including charges on the inventory is estimated to be attractively low. (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)

Naturally occurring radionuclides in food and drinking water from a thorium-rich area

International Nuclear Information System (INIS)

Costa Lauria, Dejanira da; Rochedo, Elaine R.R.; Godoy, Maria Luisa D.P.; Santos, Eliane E.; Hacon, Sandra S.

2012-01-01

This paper focuses on a survey of uranium and thorium decay chain radionuclides in food and drinking water from the thorium-rich (monazite-bearing) region of Buena, which is located in the state of Rio de Janeiro, Brazil. The radionuclide concentration values in the food and drinking water from Buena reached values higher than 100-fold the international reference values. The daily intake of radionuclides by the local population is similar to that of another high background radiation area in Brazil, but the intake is higher than that of residents from a normal background radiation area. Approximately 58 % of the food consumed by Buena inhabitants is produced locally. Based on that figure, locally produced food and the dilution of total radionuclides in the diet of residents caused by food importation are both highly relevant to a population's intake of radionuclides. The concentration values for 210 Pb and the radium isotopes in drinking water from Buena are among the highest values to be reported in the literature. 228 Ra is the most important radionuclide ingested with both food and water among the inhabitants of Buena. (orig.)

Parametric analyses of single-zone thorium-fueled molten salt reactor fuel cycle options

International Nuclear Information System (INIS)

Powers, J.J.; Worrall, A.; Gehin, J.C.; Harrison, T.J.; Sunny, E.E.

2013-01-01

Analyses of fuel cycle options based on thorium-fueled Molten Salt Reactors (MSRs) have been performed in support of fuel cycle screening and evaluation activities for the United States Department of Energy. The MSR options considered are based on thermal spectrum MSRs with 3 different separations levels: full recycling, limited recycling, and 'once-through' operation without active separations. A single-fluid, single-zone 2250 MWth (1000 MWe) MSR concept consisting of a fuel-bearing molten salt with graphite moderator and reflectors was used as the basis for this study. Radiation transport and isotopic depletion calculations were performed using SCALE 6.1 with ENDF/B-VII nuclear data. New methodology developed at Oak Ridge National Laboratory (ORNL) enables MSR analysis using SCALE, modeling material feed and removal by taking user-specified parameters and performing multiple SCALE/TRITON simulations to determine the resulting equilibrium operating conditions. Parametric analyses examined the sensitivity of the performance of a thorium MSR to variations in the separations efficiency for protactinium and fission products. Results indicate that self-sustained operation is possible with full or limited recycling but once-through operation would require an external neutron source. (authors)

Environmental control technology for mining, milling, and refining thorium

International Nuclear Information System (INIS)

Weakley, S.A.; Blahnik, D.E.; Young, J.K.; Bloomster, C.H.

1980-02-01

The purpose of this report is to evaluate, in terms of cost and effectiveness, the various environmental control technologies that would be used to control the radioactive wastes generated in the mining, milling, and refining of thorium from domestic resources. The technologies, in order to be considered for study, had to reduce the radioactivity in the waste streams to meet Atomic Energy Commission (10 CFR 20) standards for natural thorium's maximum permissible concentration (MPC) in air and water. Further regulatory standards or licensing requirements, either federal, state, or local, were not examined. The availability and cost of producing thorium from domestic resources is addressed in a companion volume. The objectives of this study were: (1) to identify the major waste streams generated during the mining, milling, and refining of reactor-grade thorium oxide from domestic resources; and (2) to determine the cost and levels of control of existing and advanced environmental control technologies for these waste streams. Six potential domestic deposits of thorium oxide, in addition to stockpiled thorium sludges, are discussed in this report. A summary of the location and characteristics of the potential domestic thorium resources and the mining, milling, and refining processes that will be needed to produce reactor-grade thorium oxide is presented in Section 2. The wastes from existing and potential domestic thorium oxide mines, mills, and refineries are identified in Section 3. Section 3 also presents the state-of-the-art technology and the costs associated with controlling the wastes from the mines, mills, and refineries. In Section 4, the available environmental control technologies for mines, mills, and refineries are assessed. Section 5 presents the cost and effectiveness estimates for the various environmental control technologies applicable to the mine, mill, and refinery for each domestic resource

The possibility of precipitating thorium soap from aqueous solutions

International Nuclear Information System (INIS)

Drathen, H.

1975-01-01

The purpose of the analysis was firstly to determine the precipitation process of thorium with soap and the influence of foreign ions, secondly to explain the conditions for the best method of decontaminating waste waters contaminated by thoriuum. The result was that if thorium is precipitated with soap both thorium soaps and thorium hydroxide are formed. The proportion of each substance depends considerably upon the pH value. All the precipitation compounds exist independently. No adsorption or mixed crystal formation took place. By adding bivalent or multivalent cations the one-step decontamination factor increases to more than 20. Quantitatively, the decontamination of thorium contaminated waste waters can be carried out down to a thorium concentration of 10 -5 mol/1. Technical soaps provide the least expensive solution without displaying any qualitative disadvantages. The only disadvantage is that this method cannot be used continuously. Therefore ion exchangers provide a great advantage, although they are very expensive and have a limited capacity. The best solution, then, is a combination of ion exchangers and precipitation with soap. (orig.) [de

Neutronics assessment of thorium-based fuel assembly in SCWR

International Nuclear Information System (INIS)

Liu, Shichang; Cai, Jiejin

2013-01-01

Highlights: • A novel thorium-based fuel assembly for SCWR has been introduced and investigated. • Neutronic properties of three thorium fuels have been studied, compared with UO 2 fuel. • The thorium-based fuel has advantages on fuel utilization and lower MAs generation. -- Abstract: Aiming to take advantage of neutron spectrum of SCWR, a novel thorium-based fuel assembly for SCWR is introduced in this paper. The neutronic characteristics of the introduced fuel assembly with three different thorium fuel types have been investigated using the “dragon” codes. The parameters in different working conditions, such as infinite multiplication factors, radial power peaking factor, temperature coefficient of reactivity and their relation with the operation period have been assessed by comparing with conventional uranium assembly. Moreover, the moderator-to-fuel ratio (MFR) was changed in order to investigate its influence on the neutronic characteristics of fuel assembly. Results show that the thorium-based fuel has advantages on both efficient fuel utilization and lower minor actinide generation, with some similar neutronic properties to the uranium fuel

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

Possible types of breeders with thorium cycle

International Nuclear Information System (INIS)

Ishiguro, Y.; Gouveia, A.S. de

1981-01-01

Neutronics calculations of simplified homogeneous reactor models show the possibility that metal-fueled LMFBRs and coated particle fueled gas cooled reactors achieve doubling times of around 10 years with the thorium cycle. Three concepts of gas-cooled thorium cycle breeders are discussed. (Author) [pt

Possible types of breeders with thorium cycle

International Nuclear Information System (INIS)

Ishiguro, Y.; Gouveia, A.S. de.

1981-02-01

Neutronics calculations of simplified homogeneous reactor models show the possibility that metal-fueled LMFBRs and coated particle fueled gas cooled reactors achieve reactor doubling times of around 10 years with the thorium cycle. Three concepts of gas-cooled thorium cycle breeders are discused. (Author) [pt

Recovery of lead-208 radiogenic of residues of thorium with rare earth

International Nuclear Information System (INIS)

Ferreira, J.C.; Freitas, A.A. de; Seneda, J.A.F.; Carvalho, M.S. de; Abrao, A.

2008-01-01

In the middle of the years 1970 in IPEN, considerable work for the purification and conversion of uranium and thorium project, the production of thorium nitrate, a pilot scale from different compounds of Thorium was accomplished; This installation of thorium nitrate produced for national marketing, given the industry of incandescent lighting gas mangles.. The method used by this installation was the purification by solvent extraction with pulsed columns. The thorium was in the organic phase, which was reversed as of thorium nitrate with a high degree of purity. The aqueous phase of this chemical process, containing impurities, some not extracted thorium and virtually all rare earths was precipitated in the form of a hydroxide. This was called RETOTER hydroxide (residue of Thorium and Rare Earth). This residue containing thorium, rare earth and some impurities such as lead-208 product of the decay of thorium-232 were stored in the shed of safeguarding IPEN for further recovery of thorium and rare earth. In this work was studied the recovery of lead-208, nuclear material of interest, separating it by the technique of cementation , where it adds zinc metallic to an acid solution of RETOTER, holding up the lead on the surface of the metallic zinc. (author)

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

Health status and body radioactivity of former thorium workers

International Nuclear Information System (INIS)

Stehney, A.F.; Polednak, A.P.; Rundo, J.; Brues, A.M.; Lucas, H.F. Jr.; Patten, B.C.; Rowland, R.E.

1981-01-01

The objectives of the study are: (1) to assess possible health effects of employment in the thorium milling industry by comparison of mortality and morbidity characteristics of former thorium workers with those of suitable general populations; (2) to examine disease outcomes by estimated exposure levels of thorium and thoron daughter products for possible radiation-related effects; and (3) to determine the body distribution of inhaled thorium (and daughters) and rare earths in humans by radioactivity measurements in vivo and by analysis of autopsy samples. The principal end points for investigation are respiratory disease and cancers of lung, liver, bone, and bone marrow

Hydriding of metallic thorium

International Nuclear Information System (INIS)

Miyake, Masanobu; Katsura, Masahiro; Matsuki, Yuichi; Uno, Masayoshi

1983-01-01

Powdered thorium is usually prepared through a combination of hydriding and dehydriding processes of metallic thorium in massive form, in which the hydriding process consists of two steps: the formation of ThH 2 , and the formation of Th 4 H 15 . However, little has yet been known as to on what stage of hydriding process the pulverization takes place. It is found in the present study that the formation of Th 4 H 15 by the reaction of ThH 2 with H 2 is responsible for pulverization. Temperature of 70 deg C adopted in this work for the reaction of formation Th 4 H 15 seems to be much more effective for production of powdered thorium than 200 - 300 deg C in the literature. The pressure-composition-temperature relationships for Th-H system are determined at 200, 300, 350, and 800 deg C. From these results, a tentative equilibrium phase diagram for the Th-H system is proposed, attention being focused on the two-phase region of ThH 2 and Th 4 H 15 . Pulverization process is discussed in terms of the tentative phase diagram. (author)

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)

Thorium fuels for heavy water reactors. Romanian experience

International Nuclear Information System (INIS)

Glodeanu, F.; Mirion, I.; Mehedinteanu, S.; Balan, V.

1984-01-01

The renewed interest in thorium fuel cycle due to the increased demand for fissile materials has resulted in speeding up the related research and development activities. For heavy water reactors the thorium cycles, especially SSET, are very promising and many efforts are made to demonstrate their feasibility. In our country, at INPR, the research and development activity has been initiated in the following areas: the conceptual design of thorium bearing fuel elements; fuel modelling; nuclear grade thorium dioxide powder technology; mixed oxide fuel technology. In the design area, the key factors in performance limitation, especially at extended burnup have been accounted and different remedies proposed. An irradiation programme has been settled and will start this year. The modelling activities are focused on mixed oxide behaviour and material data measurements are in progress. In the nuclear grade thorium powder technology area, a good piece of work has been done to develop an integrated technology for monasite processing (thorium being a by-product in lanthanides extraction). As regards the mixed oxide fuel technology, efforts have been made to obtain (ThU)O 2 pellets with good homogeneity and high density at different compositions. Besides the mixing powders route, other non-conventional technologies for refabrication like: microspheres, pellet impregnation and clay extrusion are studied. Experimental fuel rods for irradiation testing have been manufactured. (author)

Organ burdens and elimination rates of inhaled thorium and plutonium

International Nuclear Information System (INIS)

Unnikrishnan, K.; Murthy, K.B.S.; Sunta, C.M.

1986-01-01

For the purpose of interpreting observations from internal monitoring programmes, organ burdens and excretion rates resulting from inhalation of long-lived isotopes of plutonium and thorium have been calculated, on the basis of the ICRP model. Two types of inhalation, instantaneous (acute) and at a steady rate (chronic) are considered. The expected buildups of the burden in lungs, lymph nodes, bone, liver and other tissues, as well as the excretion rates, have been calculated for aerosol classes W and Y, and particle sizes of AMAD 1 μm and 6 μm. Further, in view of their use in selecting the periodicity of routine monitoring, theoretical results are also presented for the case of a total inhalation of 1 ALI in one year, instantaneously or at a constant rate. (author)

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

Vil løyse global energikrise med thorium

CERN Multimedia

Aure, Gyri

2007-01-01

A professor from Bergen claims thorium can contribute to save the world from a global energy crisis. He wants Norway to construct the first accelerator driven reactor in the world powered by thorium. (5 pages)

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.

Immobilization of thorium over fibroin by polyacrylonitrile (PAN)

International Nuclear Information System (INIS)

Aslani, M.A.A.; Akyil, S.; Eral, M.

1997-01-01

This report describes a process for immobilization of thorium over fibroin, which was used as a bio-adsorbant, by polyacrylonitrile. The amounts of thorium in aqueous solutions which may be leached in various aqueous ambients were detected by a spectrophotometer. The results show that polyacrylonitrile processes are feasible to immobilize spent fibroins. The leachability of the materials immobilized with polyacrylonitrile can meet the requirements of storage and final disposal. The leachability of thorium ions from immobilized spent fibroin was rather low for 8 months

Growth scenarios with thorium fuel cycles in pressurised heavy water reactors

International Nuclear Information System (INIS)

Balakrishnan, M.R.

1991-01-01

Since India has generous deposits of thorium, the availability of thorium will not be a limiting factor in any growth scenario. It is fairly well accepted that the best system for utilisation of thorium is the heavy water reactor. The growth scenarios possible using thorium in HWRs are considered. The base has been taken as 50,000 tons of natural uranium and practically unlimited thorium. The reference reactor has been assumed to be the PHWR, and all other growth scenarios are compared with the growth scenario provided by the once-through natural cycle in the PHWR. Two reactor types have been considered: the heavy water moderated, heavy water cooled, pressure tube reactor, known as the PHWR; and the heavy water moderated and cooled pressure vessel kind, similar to the ATUCHA reactor in Argentina. For each reactor, a number of different fuel cycles have been studied. All these cycles have been based on thorium. These are: the self-sustaining equilibrium thorium cycle (SSET); the high conversion ratio high burnup cycle; and the once through thorium cycle (OTT). The cycle have been initiated in two ways: one is by starting the cycle with natural uranium, reprocessing the spent fuel to obtain plutonium, and use that plutonium to initiate the thorium cycle; the other is to enrich the uranium to about 2-3% U-235 (the so-called Low Enriched Uranium or LEU), and use the LEU to initiate the thorium cycle. Both cases have been studied, and growth scenarios have been projected for every one of the possible combinations. (author). 1 tab

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)

A proposal for rational thorium utilization: thorims-nes

International Nuclear Information System (INIS)

Kurukawa, K.; Erbay, L. B.

1997-01-01

In this study, a globally applicable system depending on a new philosophy has been introduced for solving the problems connected with nuclear safety, ratio-waste, anti-nuclear proliferation and terrorism and public/institutional acceptance and economy. This rational thorium breeding fuel-cycle system named as THORIMS-NES (Thorium Molten- Salt Nuclear Energy Synergetics ) appears to be particularly promising and can be the way of nuclear power development. THORIMS-NES depends on three principles: I. Thorium utilization, II. Application of molten-fluoride fuel technology and III. Separation of fissile producing breeders and power producing reactors. Thorium fuel cycle has benefit on the reduction of trans-U elements and for recycling fuels produced by all kinds of military, research and industrial reactors. A system for the realization of THORIMS-NES has been introduced by the explanation of connections/relations between facilities. In this study, the status of countries/groups working on Th and Th fuel cycle has been summarized. Additionally, the resultant announcement of the International Conference on Thorium Molten Salt Reactor Development (8-11 April, 1997, Santa Monica) has been mentioned to present the cooperation of scientists and engineers for the realization of THORIMS-NES

The influence of different hydroponic conditions on thorium uptake by Brassica juncea var. foliosa.

Science.gov (United States)

Wang, Dingna; Zhou, Sai; Liu, Li; Du, Liang; Wang, Jianmei; Huang, Zhenling; Ma, Lijian; Ding, Songdong; Zhang, Dong; Wang, Ruibing; Jin, Yongdong; Xia, Chuanqin

2015-05-01

The effects of different hydroponic conditions (such as concentration of thorium (Th), pH, carbonate, phosphate, organic acids, and cations) on thorium uptake by Brassica juncea var. foliosa were evaluated. The results showed that acidic cultivation solutions enhanced thorium accumulation in the plants. Phosphate and carbonate inhibited thorium accumulation in plants, possibly due to the formation of Th(HPO4)(2+), Th(HPO4)2, or Th(OH)3CO3 (-) with Th(4+), which was disadvantageous for thorium uptake in the plants. Organic aids (citric acid, oxalic acid, lactic acid) inhibited thorium accumulation in roots and increased thorium content in the shoots, which suggested that the thorium-organic complexes did not remain in the roots and were beneficial for thorium transfer from the roots to the shoots. Among three cations (such as calcium ion (Ca(2+)), ferrous ion (Fe(2+)), and zinc ion (Zn(2+))) in hydroponic media, Zn(2+) had no significant influence on thorium accumulation in the roots, Fe(2+) inhibited thorium accumulation in the roots, and Ca(2+) was found to facilitate thorium accumulation in the roots to a certain extent. This research will help to further understand the mechanism of thorium uptake in plants.

A review on the status of development in thorium-based nuclear fuels

International Nuclear Information System (INIS)

Lee, Young Woo; Na, S. H.; Lee, Y. W.; Kim, H. S.; Kim, S. H.; Joung, C.Y.

2000-02-01

Thorium as an alternative nuclear energy source had been widely investigated in the 1950s-1960s because it is more abundant than uranium, but the studies of thorium nuclear fuel cycle were discontinued by political and economic reasons in the 1970s. Recently, however, renewed interest was vested in thorium-based nuclear fuel cycle because it may generate less long-lived minor actinides and has a lower radiotoxicity of high level wastes after reprocessing compared with the thorium fuel cycle. In this state-of the art report, thorium-based nuclear cycle. In this state-of the art report, thorium-based nuclear fuel cycle and fuel fabrication processes developed so far with different reactor types are reviewed and analyzed to establish basic technologies of thorium fuel fabrication which could meet our situation. (author)

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

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

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

Impacts of Dust on Tropical Volcanic Soil Formation: Insights from Strontium and Uranium-Series Isotopes in Soils from Basse-Terre Island, French Guadeloupe

Science.gov (United States)

Pereyra, Y.; Ma, L.; Sak, P. B.; Gaillardet, J.; Buss, H. L.; Brantley, S. L.

2015-12-01

Dust inputs play an important role in soil formation, especially for thick soils developed on tropical volcanic islands. In these regions, soils are highly depleted due to intensive chemical weathering, and mineral nutrients from dusts have been known to be important in sustaining soil fertility and productivity. Tropical volcanic soils are an ideal system to study the impacts of dust inputs on the ecosystem. Sr and U-series isotopes are excellent tracers to identify sources of materials in an open system if the end-members have distinctive isotope signatures. These two isotope systems are particularly useful to trace the origin of atmospheric inputs into soils and to determine rates and timescales of soil formation. This study analyzes major elemental concentrations, Sr and U-series isotope ratios in highly depleted soils in the tropical volcanic island of Basse-Terre in French Guadeloupe to determine atmospheric input sources and identify key soil formation processes. We focus on three soil profiles (8 to 12 m thick) from the Bras-David, Moustique Petit-Bourg, and Deshaies watersheds; and on the adjacent rivers to these sites. Results have shown a significant depletion of U, Sr, and major elements in the deep profile (12 to 4 m) attributed to rapid chemical weathering. The top soil profiles (4 m to the surface) all show addition of elements such as Ca, Mg, U, and Sr due to atmospheric dust. More importantly, the topsoil profiles have distinct Sr and U-series isotope compositions from the deep soils. Sr and U-series isotope ratios of the top soils and sequential extraction fractions confirm that the sources of the dust are from the Saharan dessert, through long distance transport from Africa to the Caribbean region across the Atlantic Ocean. During the transport, some dust isotope signatures may also have been modified by local volcanic ashes and marine aerosols. Our study highlights that dusts and marine aerosols play important roles in element cycles and

Heavy water reactors on the denatured thorium cycles

International Nuclear Information System (INIS)

1978-05-01

This paper presents preliminary technical and economic data to INFCE on the denatured U-233/Thorium fuel cycle for use in early comparisons of alternate nuclear systems. The once-through uranium fuel cycle is discussed in a companion paper. In presenting this preliminary information at this time, it is recognized that there are several other denatured thorium fuel cycles of potential interest, such as the U-235/thorium cycle which could be implemented at an earlier date. Information on these alternate cycles is currently being developed, and will be provided to INFCE when available

Preparation of microcuries of 234-thorium

International Nuclear Information System (INIS)

Suner, A.; La Gamma de Batistoni, A.M.; Botbol, J.

1974-11-01

A procedure for the preparation of microcuries of 234 Th from hydrochloric acid solutions of uranium (VI) is described. A solution of uranyl chloride in radioactive equilibrium with 234 Th (older than 6 months) and having 232 Th as carrier, is percoled through a Dowex 50 Wx8 (H + ) resin bed, wherein is absorbed 85% of Th and some uranium, which is then desorbed with 10 N HCl. The thorium remains in the column and is extracted later with a 0,025 M SO 4 H 2 plus 1 M SO 4 (NH 4 ) 2 solution. The thorium solution is freed from sulfate by precipitation with ammonia, dissolving the precipitate with 10 N HCl, whose solution is treated with Dowex 2x8 resin. The ion exchanger absorbs the anionic impurities and the thorium obtained is of high chemical and radiochemical purity. (author)

Uranium series disequilibrium studies at the Broubster analogue site

International Nuclear Information System (INIS)

Longworth, G.; Ivanovich, M.; Wilkins, M.A.

1990-11-01

Uranium series measurements at a natural analogue site at Broubster, Caithness have been used to investigate radionuclide migration over periods ranging from several hundred to 10 6 years. The measured values for the uranium concentration and activity values 234 U/ 238 U and 230 Th/ 234 U indicate that the geochemical system is more complicated than that originally proposed of uranium dispersion and water transport into a peat bog. There appears to be little thorium mobility although there is evidence for an appreciable fraction of thorium on the colloidal phase. (author)

Uranium series disequilibrium studies at the Broubster analogue site

International Nuclear Information System (INIS)

Longworth, G.; Ivanovich, M.; Wilkins, M.A.

1989-09-01

Uranium series measurements at a natural analogue site at Broubster, Caithness have been used to investigate radionuclide migration over a period of several hundred to 10 6 years. The measured values for the uranium concentration and activity ratios 234 U/ 238 U and 230 Th/ 234 U indicate that the geochemical system is more complicated than that originally proposed of uranium dispersion and water transport into a peat bog. There appears to be little thorium mobility although there is evidence for an appreciable fraction of thorium on the colloidal phases. (author)

Promises and Challenges of Thorium Implementation for Transuranic Transmutation - 13550

Energy Technology Data Exchange (ETDEWEB)

Franceschini, F.; Lahoda, E.; Wenner, M. [Westinghouse Electric Company LLC, Cranberry Township, PA (United States); Lindley, B. [University of Cambridge (United Kingdom); Fiorina, C. [Polytechnic of Milan (Italy); Phillips, C. [Energy Solutions, Richland, WA (United States)

2013-07-01

This paper focuses on the challenges of implementing a thorium fuel cycle for recycle and transmutation of long-lived actinide components from used nuclear fuel. A multi-stage reactor system is proposed; the first stage consists of current UO{sub 2} once-through LWRs supplying transuranic isotopes that are continuously recycled and burned in second stage reactors in either a uranium (U) or thorium (Th) carrier. The second stage reactors considered for the analysis are Reduced Moderation Pressurized Water Reactors (RMPWRs), reconfigured from current PWR core designs, and Fast Reactors (FRs) with a burner core design. While both RMPWRs and FRs can in principle be employed, each reactor and associated technology has pros and cons. FRs have unmatched flexibility and transmutation efficiency. RMPWRs have higher fuel manufacturing and reprocessing requirements, but may represent a cheaper solution and the opportunity for a shorter time to licensing and deployment. All options require substantial developments in manufacturing, due to the high radiation field, and reprocessing, due to the very high actinide recovery ratio to elicit the claimed radiotoxicity reduction. Th reduces the number of transmutation reactors, and is required to enable a viable RMPWR design, but presents additional challenges on manufacturing and reprocessing. The tradeoff between the various options does not make the choice obvious. Moreover, without an overarching supporting policy in place, the costly and challenging technologies required inherently discourage industrialization of any transmutation scheme, regardless of the adoption of U or Th. (authors)

Remeasurement of thorium-230 in the pore water of Lacnor tailings

International Nuclear Information System (INIS)

Snodgrass, W.J.; Hart, D.R.

1990-02-01

A resampling of the Lacnor tailings management area was undertaken under a comprehensive quality assurance programme to establish levels of thorium 230 in pore water. A quality assurance programme was established for field sampling, sample handling and transport, and laboratory procedures and reporting. The external audit was used to evaluate analytical bias (on synthetic and field samples) and precision (by comparison of duplicate-duplicate results). Accuracy was assessed using synthetic samples. The external audit indicates that thorium 230 measurements by the main laboratory are not significantly different from the interlaboratory average within standard statistical limits. The results of the audit are based on measurement of environmental samples and known synthetic samples. This shows that present and previous measurements of thorium 230 varying from 0,1 to 150 Bq/L are valid data. A qualitative interpretation of the controls on thorium 230 geochemistry is provided in terms of control by thorium 232 and thorium dioxide(c) solid phase. Generic dose estimates for consumption of water containing thorium 230 are made but require refinement ot account for the actual pH of the drinking water and the degree of dilution of the pore water. The results of this project indicate that the performance of the laboratory that will conduct future thorium 230 measurements can be assessed satisfactorily with a smaller scale external laboratory assurance programme. The programme should include replicate samples sent to each laboratory and interlaboratory comparison on samples having high and low values of thorium 230

Thorium prospect of placer deposits in Koba area and its surroundings

International Nuclear Information System (INIS)

Ngadenin; Fd Dian Indrastomo; Widodo

2012-01-01

The objective of the present study of the thorium in placer of Koba, Central Bangka District. Bangka Belitung Province and its surrounding is to find out thorium prospect in alluvial deposits. The study method are geological and radiometrical mapping, grain counting and thorium grade analysis of pan concentrated. Result of the research reveals that lithology of the investigation area compose of meta sandstone unit with radiometric value of 35 c/s - 200 c/s, granite intrusion with radiometric value of 140-550 c/s and alluvial with radiometric value of 40-300 c/s SPP2NF. Content of monazite in the pan concentrated is approximately 7.54 %, content of thorium in pan concentrated of 1410 ppm, covered alluvial deposits of about 400 kilometers square with average thickness 3.77 meters. According to the study thorium prospect in Koba area is feasible to be Based on the type of deposit (placer) which are relatively easy to be mined at low cost, high content of monazite and thorium so that the prospect thorium Koba feasible to develop. (author)

Study on Thorium Hidroxide and Ammonium Diuranate precipitation

International Nuclear Information System (INIS)

Damunir; Sukarsono, R; Busron-Masduki; Indra-Suryawan

1996-01-01

Thorium hydroxide and ammonium diuranate precipitation studied by the reaction of mixed thorium nitrate and uranyl nitrate using ammonium hydroxide. The purposes of this research was study of pH condition. U/Th ratio and NH 4 OH concentration on the precipitation. Mixed of thorium nitrate and uranyl nitrate 50 ml was reacted by excess ammonium hydroxide 2 - 10 M, pH 4-8, 40-80 o C of temperature and 5 - 100 % ratio of U/Th. The best of precipitation depend on thorium and uranium content on the precipitation. The experiment result for the best condition of precipitation was 25 % of ratio U/Th, pH 6 - 8, 60-80 o C of temperature, and 6 - 10 M concentration of ammonium hydroxide, was produced precipitate by 3,938 - 5,455 weight percent of mean concentration of U and 22,365-31,873 weight percent of mean concentration of Th

Uranium-series constraints on radionuclide transport and groundwater flow at the Nopal I uranium deposit, Sierra Pena Blanca, Mexico

Energy Technology Data Exchange (ETDEWEB)

Goldstein, S.J.; Abdel-Fattah, A.I.; Murrell, M.T.; Dobson, P.F.; Norman, D.E.; Amato, R.S.; Nunn, A. J.

2009-10-01

Uranium-series data for groundwater samples from the Nopal I uranium ore deposit were obtained to place constraints on radionuclide transport and hydrologic processes for a nuclear waste repository located in fractured, unsaturated volcanic tuff. Decreasing uranium concentrations for wells drilled in 2003 are consistent with a simple physical mixing model that indicates that groundwater velocities are low ({approx}10 m/y). Uranium isotopic constraints, well productivities, and radon systematics also suggest limited groundwater mixing and slow flow in the saturated zone. Uranium isotopic systematics for seepage water collected in the mine adit show a spatial dependence which is consistent with longer water-rock interaction times and higher uranium dissolution inputs at the front adit where the deposit is located. Uranium-series disequilibria measurements for mostly unsaturated zone samples indicate that {sup 230}Th/{sup 238}U activity ratios range from 0.005-0.48 and {sup 226}Ra/{sup 238}U activity ratios range from 0.006-113. {sup 239}Pu/{sup 238}U mass ratios for the saturated zone are <2 x 10{sup -14}, and Pu mobility in the saturated zone is >1000 times lower than the U mobility. Saturated zone mobility decreases in the order {sup 238}U{approx}{sup 226}Ra > {sup 230}Th{approx}{sup 239}Pu. Radium and thorium appear to have higher mobility in the unsaturated zone based on U-series data from fractures and seepage water near the deposit.

Thorium (IV) toxicity of green microalgae from Scenedesmus and Monoraphidium genera

International Nuclear Information System (INIS)

Queiroz, Juliana Cristina de

2009-01-01

The toxicity of thorium by two green microalgae species, Monoraphidium sp. and Scenedesmus sp was studied. During the toxicity tests, the microalgae cultures were inoculated in ASM-I culture medium in the presence and absence of thorium (cultures at pH 8.0 and 6.0 in the absence of thorium, - control - and at pH 6.0 for thorium concentrations ranging from 0.5 to 100.0 mg/L Th). Its effect was monitored by direct counting on Fuchs-Rosenthal chamber and with the help of software developed by the group during the experiments. The difference in pH value in the culture medium did not affect the growth of the microalgae, and pH 6.0 was chosen as a reference in order not to compromise solubility and speciation of thorium in solution. The toxicity of the metal over the species was observed just for thorium concentrations over 50.0 mg/L. A Monoraphidium sp. culture containing 6.25x10 5 microorganisms/mL reached a final concentration of 5.52x10 7 microorganisms/mL in the presence of thorium in the concentration of 10.0 mg/L. If we consider the 100.0 ppm thorium solution reached a final concentration of 8.57x10 6 microorganisms/mL. Control tests indicated a final concentration of 2.51x10 7 microorganisms/mL at the end of the growth. Scenedesmus sp. cells proved to be more resistant to the presence of thorium in solution. Low concentrations of the radionuclide favored the growth of these microalgae. A culture containing 7.65x10 5 microorganisms/mL reached a final concentration of 2.25x10 6 microorganisms/mL, in the absence of thorium in the medium. Toxicological tests indicated a final culture concentration of 5.87x10 6 microorganisms/mL in the presence of 0.5 mg/L thorium. The software used for comparison of direct count method proved to be very useful for the improvement of accuracy of the results obtained and a decrease in the uncertainty in counting. Beyond these advantages it also allowed recording of the data. From the present results one can conclude, that the presence

Stable isotope time series and dentin increments elucidate Pleistocene proboscidean paleobiology

Science.gov (United States)

Fisher, Daniel; Rountrey, Adam; Smith, Kathlyn; Fox, David

2010-05-01

Investigations of stable isotope composition of mineralized tissues have added greatly to our knowledge of past climates and dietary behaviors of organisms, even when they are implemented through 'bulk sampling', in which a single assay yields a single, time-averaged value. Likewise, the practice of 'sclerochronology', which documents periodic structural increments comprising a growth record for accretionary tissues, offers insights into rates of growth and age data at a scale of temporal resolution permitted by the nature of structural increments. We combine both of these approaches to analyze dental tissues of late Pleistocene proboscideans. Tusk dentin typically preserves a record of accretionary growth consisting of histologically distinct increments on daily, approximately weekly, and yearly time scales. Working on polished transverse or longitudinal sections, we mill out a succession of temporally controlled dentin samples bounded by clear structural increments with a known position in the sequence of tusk growth. We further subject each sample (or an aliquot thereof) to multiple compositional analyses - most frequently to assess δ18O and δ13C of hydroxyapatite carbonate, and δ13C and δ15N of collagen. This yields, for each animal and each series of years investigated, a set of parallel compositional time series with a temporal resolution of 1-2 months (or finer if we need additional precision). Patterns in variation of thickness of periodic sub-annual increments yield insight into intra-annual and inter-annual variation of tusk growth rate. This is informative even by itself, but it is still more valuable when coupled with compositional time series. Further, the controls on different stable isotope systems are sufficiently different that the data ensemble yields 'much more than the sum of its parts.' By assessing how compositions and growth rates covary, we monitor with greater confidence changes in local climate, diet, behavior, and health status. We

Simulation an Accelerator driven Subcritical Reactor core with thorium fuel

International Nuclear Information System (INIS)

Shirmohammadi, L.; Pazirandeh, A.

2011-01-01

The main purpose of this work is simulation An Accelerator driven Subcritical core with Thorium as a new generation nuclear fuel. In this design core , A subcritical core coupled to an accelerator with proton beam (E p =1 GeV) is simulated by MCNPX code .Although the main purpose of ADS systems are transmutation and use MA (Minor Actinides) as a nuclear fuel but another use of these systems are use thorium fuel. This simulated core has two fuel assembly type : (Th-U) and (U-Pu) . Consequence , Neutronic parameters related to ADS core are calculated. It has shown that Thorium fuel is use able in this core and less nuclear waste ,Although Iran has not Thorium reserves but study on Thorium fuel cycle can open a new horizontal in use nuclear energy as a clean energy and without nuclear waste

A study of the running-in period of a CANDU-PHW thorium converter

International Nuclear Information System (INIS)

Dormuth, K.W.; Lidstone, R.F.

1977-08-01

One of the concepts being studied as part of an evaluation of advanced fuel cycles for the Canadian nuclear power program is that of a Candu reactor whose initial fuel is a mixture of thorium and plutonium and whose bred uranium is recycled back to the same core with plutonium topping. From start-up of this reactor, when the fuel contains no uranium, to the attainment of equilibrium, when the uranium content of the feed fuel becomes constant, the core is in a transitional state because the composition of the feed fuel is changing. Since this so-called running-in period constitutes a large portion of the reactor life, it is essential that it be accounted for in fuel management calculations. The presence of the relatively long-lived intermediate nuclide, 233 Pa, in the thorium conversion chain complicates such calculations, because it causes the concentration of the important fissile isotope, 233 U, to depend rather strongly on flux history. A computational method based on the lattice code, WIMS, and the one-dimensional diffusion-depletion code, FEVER-7, has been developed and used to analyse the running-in period of a 1200 MWe (Th,Pu,U)O 2 -fuelled CANDU-PHW. (author)

Rates of carbonate soil evolution from carbon, U- and Th-series isotope studies: Example of the Astian sands (SE France)

Science.gov (United States)

Barbecot, Florent; Ghaleb, Bassam; Hillaire-Marcel, Claude

2015-04-01

In carbonate rich soils, C-isotopes (14C, 13C) and carbonate mass budget may inform on centennial to millennial time scale dissolution/precipitation processes and weathering rates, whereas disequilibria between in the U- and Th-decay series provide tools to document high- (228Ra-228Th-210Pb) to low- (234U, 230Th, 231Pa, 226Ra) geochemical processes rate, covering annual to ~ 1Ma time scales, governing both carbonate and silicate soil fractions. Because lithology constitutes a boundary condition, we intend to illustrate the behavior of such isotopes in soils developed over Astian sands formation (up to ~ 30% carbonate) from the Béziers area (SE France). A >20 m thick unsaturated zone was sampled firstly along a naturally exposed section, then in a cored sequence. Geochemical and mineralogical analyses, including stable isotopes and 14C-measurements, were complemented with 228U, 234U, 230Th, 226Ra, 210Pb and 228Th, 232Th measurements. Whereas the upper 7 m depict geochemical and isotopic features forced by dissolution/precipitation processes leading to variable radioactive disequilibria, but overall deficits in more soluble elements of the decay series, the lower part of the sequence shows strong excesses in 234U and 230Th over parent isotopes (i.e., 238U and 234U, respectively). These features might have been interpreted as the result of successive phases of U-loss and gains. However, 226Ra and 230Th are in near-equilibrium, thus leading to conclude at a more likely slow enrichment process in both 234Th(234U) and 230Th, which we link to dissolved U-decay during groundwater recharge events. In addition, 210Pb deficits (vs parent 226Ra) are observed down to 12 m along the natural outcropping section and below the top-soil 210Pb-excess in the cored sequence, due to gaseous 222Rn-diffusion over the cliff outcrop. Based on C-isotope and chemical analysis, reaction rates at 14C-time scale are distinct from those estimates at the short- or long-lived U-series isotopes

Thorium Nitrate Stockpile--From Here to Eternity

International Nuclear Information System (INIS)

Hermes, W. H.; Hylton, T. D.; Mattus, C.H.; Storch, S. N.; Singley, P.S.; Terry, J. W.; Pecullan, M.; Reilly, F. K.

2003-01-01

The Defense National Stockpile Center (DNSC), a field level activity of the Defense Logistics Agency (DLA) has stewardship of a stockpile of thorium nitrate that has been in storage for decades. The stockpile is made up of approximately 3.2 million kg (7 million lb) of thorium nitrate crystals (hydrate form) stored at two depot locations in the United States. DNSC sought technical assistance from Oak Ridge National Laboratory (ORNL) to define and quantify the management options for the thorium nitrate stockpile. This paper describes methodologies and results comprising the work in Phase 1 and Phase 2. The results allow the DNSC to structure and schedule needed tasks to ensure continued safe long-term storage and/or phased disposal of the stockpile

Inhalation radiotoxicity of irradiated thorium as a heavy water reactor fuel

International Nuclear Information System (INIS)

Edwards, G.W.R.; Priest, N.D.; Richardson, R.B.

2013-01-01

The online refueling capability of Heavy Water Reactors (HWRs), and their good neutron economy, allows a relatively high amount of neutron absorption in breeding materials to occur during normal fuel irradiation. This characteristic makes HWRs uniquely suited to the extraction of energy from thorium. In Canada, the toxicity and radiological protection methods dealing with personnel exposure to natural uranium (NU) spent fuel (SF) are well-established, but the corresponding methods for irradiated thorium fuel are not well known. This study uses software to compare the activity and toxicity of irradiated thorium fuel ('thorium SF') against those of NU. Thorium elements, contained in the inner eight elements of a heterogeneous high-burnup bundle having LEU (Low-enriched uranium) in the outer 35 elements, achieve a similar burnup to NU SF during its residence in a reactor, and the radiotoxicity due to fission products was found to be similar. However, due to the creation of such inhalation hazards as U-232 and Th-228, the radiotoxicity of thorium SF was almost double that of NU SF after sufficient time has passed for the decay of shorter-lived fission products. Current radio-protection methods for NU SF exposure are likely inadequate to estimate the internal dose to personnel to thorium SF, and an analysis of thorium in fecal samples is recommended to assess the internal dose from exposure to this fuel. (authors)

Inhalation radiotoxicity of irradiated thorium as a heavy water reactor fuel

Energy Technology Data Exchange (ETDEWEB)

Edwards, G.W.R.; Priest, N.D.; Richardson, R.B. [Atomic Energy of Canada Ltd., Chalk River, Ontario, K0J 1J0 (Canada)

2013-07-01

The online refueling capability of Heavy Water Reactors (HWRs), and their good neutron economy, allows a relatively high amount of neutron absorption in breeding materials to occur during normal fuel irradiation. This characteristic makes HWRs uniquely suited to the extraction of energy from thorium. In Canada, the toxicity and radiological protection methods dealing with personnel exposure to natural uranium (NU) spent fuel (SF) are well-established, but the corresponding methods for irradiated thorium fuel are not well known. This study uses software to compare the activity and toxicity of irradiated thorium fuel ('thorium SF') against those of NU. Thorium elements, contained in the inner eight elements of a heterogeneous high-burnup bundle having LEU (Low-enriched uranium) in the outer 35 elements, achieve a similar burnup to NU SF during its residence in a reactor, and the radiotoxicity due to fission products was found to be similar. However, due to the creation of such inhalation hazards as U-232 and Th-228, the radiotoxicity of thorium SF was almost double that of NU SF after sufficient time has passed for the decay of shorter-lived fission products. Current radio-protection methods for NU SF exposure are likely inadequate to estimate the internal dose to personnel to thorium SF, and an analysis of thorium in fecal samples is recommended to assess the internal dose from exposure to this fuel. (authors)

Thorium determination by x-ray fluorescence spectrometry in simulated thorex process solutions

International Nuclear Information System (INIS)

Yamaura, M.; Matsuda, H.T.

1991-11-01

The X-ray fluorescence method for thorium determination in aqueous and organic (TBP/n-dodecane) solutions is described. The thin film technique for sample preparation and a suitable internal standard had been used. The best conditions for Thorium determination had been established studying some parameters as analytical line, internal standard, filter paper, paper geometry, sample volume and measurement conditions. With the established conditions, thorium was concentration range of to 200 g Th/L and in organic solutions (2-63g Th/L) with 1,5% of precision. The accuracy of the proposed method was 3% in aqueous and organic phases. The detection limit was 1,2μg thorium for aqueous solutions and 1,4μg for organic solutions. Uranium, fission products, corrosion products and Thorex reagent components were studied as interfering elements in the thorium analysis. The matrix effect was also studied using the Thorex process simulated solutions. Finally, the method was applied to thorium determination in irradiated thorium solutions with satisfactory results. (author)

Spectral shift controlled reactors, denatured U-233/thorium cycle

International Nuclear Information System (INIS)

1978-05-01

This paper presents technical and economic data on the SSCR which may be of use in the International Fuel Cycle Evaluation Program to intercompare alternative nuclear systems. Included in this paper are data on the denatured U-233/thorium cycle. This cycle shows a proliferation advantage over more classical thorium fuel cycle (e.g., highly-enriched U-235/thorium or plutonium/thorium) due to the elimination of chemically-separable, concentrated fissile material from unirradiated nuclear fuel. The U-233 is denatured by mixing with depleted uranium to a concentration no greater than 12 w/o. An exogenous source of U-233 is assumed in this paper, since U-233 does not occur in nature and only a limited supply has been produced to date for research and development work

Experiences in running solvent extraction plant for thorium compounds [Paper No. : V-5

International Nuclear Information System (INIS)

Gopalkrishnan, C.R.; Bhatt, J.P.; Kelkar, G.K.

1979-01-01

Indian Rare Earths Ltd. operates a Plant using thorium concentrates as raw material, employing hydrocarbonate route, for the manufacture of thorium compounds. A small demonstration solvent extraction plant designed by the Chemical Engineering Division, B.A.R.C. is also being operated for the same purpose using a partly purified thorium hydrocarbonate as raw material. In the solvent extraction process, separation of pure thorium is done in mixer settlers using 40% mixture of tri-butyl phosphate in kerosene. Though a comparatively purer raw material of hydrocarbonate than thorium concentrate is used, heavy muck formation is encountered in the extraction stage. Production of nuclear grade thorium oxide has been successful so far as quality is concerned. The quality of thorium nitrate suffers in the yellow colouration and high phosphate content, the former being only partly controlled through the use of pretreated kerosene. When a larger solvent extraction plant is to be designed to use thorium concentrates as raw material, some of the problems encountered will be considered. (author)

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

Comparison of direct alpha spectrometry and neutron activation analysis of aerosol filters for determination of workplace thorium air concentrations

Energy Technology Data Exchange (ETDEWEB)

Hoetzl, H.; Winkler, R. [Institut fuer Strahlenschutz, Oberschleibheim (Germany); Riedmann, W.; Weinmueller, K. [Strahlenschutz und Isotopentechnik, Muenchen (Germany)

1996-05-01

Direct alpha spectrometry with three different filter types was investigated for the determination of thorium air concentrations at workplaces in the manufacturing process of discharge lamps containing thoriated tungsten electrodes. The method was compared with neutron activation analysis over an activity range of five orders of magnitude. Within the experimental limits of error, both methods were found to be comparable with respect to sensitivity and accuracy. The advantage of direct alpha spectrometry, however, is that it is less laborious than neutron activation analysis and that it supplies information on the degree of radioactive equilibrium of the thorium series, which is important with regard to the estimation of dose. 20 refs., 2 figs., 1 tab.

Selective Precipitation of Thorium lodate from a Tartaric Acid-Hydrogen Peroxide Medium Application to Rapid Spectrophotometric Determination of Thorium in Silicate Rocks and in Ores

Science.gov (United States)

Grimaldi, F.S.

1957-01-01

This paper presents a selective iodate separation of thorium from nitric acid medium containing d-tartaric acid and hydrogen peroxide. The catalytic decomposition of hydrogen peroxide is prevented by the use of 8quinolinol. A few micrograms of thorium are separated sufficiently clean from 30 mg. of such oxides as cerium, zirconium, titanium, niobium, tantalum, scandium, or iron with one iodate precipitation to allow an accurate determination of thorium with the thoronmesotartaric acid spectrophotometric method. The method is successful for the determination of 0.001% or more of thorium dioxide in silicate rocks and for 0.01% or more in black sand, monazite, thorite, thorianite, eschynite, euxenite, and zircon.

Role of thorium in ensuring long term energy security to India

International Nuclear Information System (INIS)

Malhotra, S.K.

2013-01-01

Role of nuclear power in ensuring energy security to the world is inevitable due to a) dwindling fossil fuel resources and b) need for minimising green house gas emission that poses the risk of global climate change. India, keeping in mind its limited uranium and vast thorium resources, is pursuing a three stage nuclear power programme. The first stage is based on reactors that use uranium as fuel. It comprises of the indigenous Pressurised Heavy Water Reactors using natural uranium as fuel and light water reactors that employ enriched uranium as fuel and are to be set up in technical collaboration with other countries. The second stage is based on fast breeder reactors that employ plutonium derived from reprocessing of spent fuel from the first stage reactors. The third stage envisages reactors which will employ thorium based fuel after its irradiation in the second stage reactors. This programme is sequential in nature and has an ultimate objective of securing long term energy security to India through judicial use of its thorium resources. Thorium based reactors offer advantages in terms of better neutronic characteristics of thorium, it being better fertile host for plutonium disposition and better thermo-mechanical properties and slower fuel deterioration of thorium oxide. It is planned to introduce thorium in the Indian Nuclear Power Programme after sufficient (about 200 GWe) capacity build-up in the second stage. DAE is a global leader in the development of the entire thorium fuel cycle. It has a mature technology for extraction of thorium and preparation of thoria pellets. It has long back carried out irradiation of thoria pellets in its research reactors and also in PHWRs, post irradiation examination and reprocessing of irradiated thoria, fabrication of 233 U based fuel. It has KAMINI - the world's only operating reactor employing 233 U as fuel. An Advanced Heavy Water Reactor (AHWR) has been designed as a technology demonstrator for large scale

Recovery and purification of rare earth elements and thorium

International Nuclear Information System (INIS)

Sungur, A.; Saygi, Z.; Yildiz, H.

1985-01-01

Rare earth elements and thorium found in the low-grade Eskisehir-Beylikahir ore have been recovered by HCl leaching, Lanthanides and thorium were separated and purified from the leach solutions through the precipitation sequence as double sulphate, hydroxide and oxalate. The Ln 2 O 3 and Th(OH) 4 products, finally obtained contained 36% Ce and 65% Th. The analysis of rare earth elements, thorium and other present ingredients were carried out by instrumental neutron activation analysis, atomic absorption spectroscopy, vis-spectroscopy and gravimetry. (author)

Computer simulations for thorium doped tungsten crystals

International Nuclear Information System (INIS)

Eberhard, Bernd

2009-01-01

Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO 2 , as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a set of Langevin equations, i.e. stochastic

Depth-Resolved Cathodoluminescence of Thorium Dioxide

Science.gov (United States)

2013-03-01

plutonium-239 (239Pu)-based nuclear weapons. Thorium also results in less highly radioactive waste in comparison to the uranium fuels. Thorium is four...diameters (1/4 – 3/8”) (Mann & Thompson, 2010). The 99.99% ThO2 powder was placed into the ampoule with a basic mineralizer such as cesium fluoride...conversion ranging from 1 pA/V to 1 mA/V. The electrical noise is further reduced by cooling the PMT housing unit with liquid nitrogen as seen in

Thorium-Based Fuel Cycles in the Modular High Temperature Reactor

Institute of Scientific and Technical Information of China (English)

CHANG Hong; YANG Yongwei; JING Xingqing; XU Yunlin

2006-01-01

Large stockpiles of civil-grade as well as weapons-grade plutonium have been accumulated in the world from nuclear power or other programs of different countries. One alternative for the management of the plutonium is to incinerate it in the high temperature reactor (HTR). The thorium-based fuel cycle was studied in the modular HTR to reduce weapons-grade plutonium stockpiles, while producing no additional plutonium or other transuranic elements. Three thorium-uranium fuel cycles were also investigated. The thorium absorption cross sections of the resolved and unresolved resonances were generated using the ZUT-DGL code based on existing resonance data. The equilibrium core of the modular HTR was calculated and analyzed by means of the code VSOP'94. The results show that the modular HTR can incinerate most of the initially loaded plutonium amounting to about 95.3% net 239Pu for weapons-grade plutonium and can effectively utilize the uranium and thorium in the thorium-uranium fuel cycles.

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

Economics and utilization of thorium in nuclear reactors

International Nuclear Information System (INIS)

1978-05-01

Information on thorium utilization in power reactors is presented concerning the potential demand for nuclear power, the potential supply for nuclear power, economic performance of thorium under different recycle policies, ease of commercialization of the economically preferred cases, policy options to overcome institutional barriers, and policy options to overcome technological and regulatory barriers

Technical soaps - a possibility of decontaminating thorium-contaminated waste waters

International Nuclear Information System (INIS)

Drathen, H.; Erichsen, L. v.

1977-01-01

Thorium-contaminated waste waters showing a concentration of thorium higher than 10sup(-5) mol/l can be quantitatively decontaminated by adding soaps. Concentrations of impurity ions of both tap and sea waters have been taken into consideration. As there is no difference between soaps and soap mixtures concerning the quantity of precipitation rates, technical soaps are from the economic point of view best suited for decontaminating thorium-contaminated waste waters. Having a soap concentration of 200% of the stoichiometric amount of thorium and a concentration of impurity ions of 10sup(-2) mol/l, it is assumed that decontamination factors of more than 20 can be reached in one step. (orig.) [de

Transformation using peroxide of a crude thorium hydroxide in nitrate for mantle grade

International Nuclear Information System (INIS)

Freitas, Antonio Alves de; Carvalho, Fatima Maria Sequeira de; Ferreira, Joao Coutinho; Abrao, Alcidio

2002-01-01

An alternative process for the recovery and purification of thorium starting from a crude thorium hydroxide as the precursor is outlined in this paper. Its composition is 60.1% thorium oxide (ThO 2 ), 18.6% rare earth oxides (TR 2 O 3 ), and common impurities like silicium, iron, titanium, lead and sodium. This material was produced industrially from the monazite processing in Brazil and has been stocked since several years. The crude thorium hydroxide is treated with hot nitric acid and after the digestion and addition of floculant it is filtered for the separation of the insoluble fraction. Using this nitrate solution, the thorium peroxide is precipitated after adjustment of pH and controlled addition of hydrogen peroxide. The final thorium peroxide is dissolved with nitric acid and the resulting thorium nitrate is mantle grade quality. Rare earth elements are recovered from the thorium peroxide filtrate. The main process parameters for the peroxide precipitation, like pH and temperature and main the results are presented and discussed. (author)

U-series dating and stable isotope records of speleothem records from the Scladina Cave (Belgium)

Science.gov (United States)

van der Lubbe, Jeroen; Bonjean, Dominique; Hellstrom, John; Verheyden, Sophie; Vonhof, Hubert

2015-04-01

The Scladina cave, situated in the village of Sclayn (Ardennes, Belgium) at the southern bank of the Meuse, is famous for its Neanderthal fossils and artefacts. The infilling of the cave consists of a succession of flowstone layers interbedded with reworked loess sediment from outside the cave. The younger flowstone layers correspond to interglacials MIS 5 and the Holocene, while the reworked loess sediments represent cooler conditions. By careful diagenetic screening, well-preserved speleothem material was selected for U-series dating and stable isotope analysis of calcite and fluid inclusions. The results provide important new constraints on the age of Neanderthal fossils and artefacts, and bracket the time periods with a hydroclimate favorable for speleothem growth. The combination of fluid inclusion and calcite isotope analysis documents climate variability in the interglacials at high temporal resolution.

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)

Establishing bounding internal dose estimates for thorium activities at Rocky Flats.

Science.gov (United States)

Ulsh, Brant A; Rich, Bryce L; Chew, Melton H; Morris, Robert L; Sharfi, Mutty; Rolfes, Mark R

2008-07-01

As part of an evaluation of a Special Exposure Cohort petition filed on behalf of workers at the Rocky Flats Plant, the National Institute for Occupational Safety and Health (NIOSH) was required to demonstrate that bounding values could be established for radiation doses due to the potential intake of all radionuclides present at the facility. The main radioactive elements of interest at Rocky Flats were plutonium and uranium, but much smaller quantities of several other elements, including thorium, were occasionally handled at the site. Bounding potential doses from thorium has proven challenging at other sites due to the early historical difficulty in detecting this element through urinalysis methods and the relatively high internal dose delivered per unit intake. This paper reports the results of NIOSH's investigation of the uses of thorium at Rocky Flats and provides bounding dose reconstructions for these operations. During this investigation, NIOSH reviewed unclassified reports, unclassified extracts of classified materials, material balance and inventory ledgers, monthly progress reports from various groups, and health physics field logbooks, and conducted interviews with former Rocky Flats workers. Thorium operations included: (1) an experimental metal forming project with 240 kg of thorium in 1960; (2) the use of pre-formed parts in weapons mockups; (3) the removal of Th from U; (4) numerous analytical procedures involving trace quantities of thorium; and (5) the possible experimental use of thorium as a mold coating compound. The thorium handling operations at Rocky Flats were limited in scope, well-monitored and documented, and potential doses can be bounded.

Candu reactors with thorium fuel cycles

International Nuclear Information System (INIS)

Hopwood, J.M.; Fehrenbach, P.; Duffey, R.; Kuran, S.; Ivanco, M.; Dyck, G.R.; Chan, P.S.W.; Tyagi, A.K.; Mancuso, C.

2006-01-01

Over the last decade and a half AECL has established a strong record of delivering CANDU 6 nuclear power plants on time and at budget. Inherently flexible features of the CANDU type reactors, such as on-power fuelling, high neutron economy, fuel channel based heat transport system, simple fuel bundle configuration, two independent shut down systems, a cool moderator and a defence-in-depth based safety philosophy provides an evolutionary path to further improvements in design. The immediate milestone on this path is the Advanced CANDU ReactorTM** (ACRTM**), in the form of the ACR-1000TM**. This effort is being followed by the Super Critical Water Reactor (SCWR) design that will allow water-cooled reactors to attain high efficiencies by increasing the coolant temperature above 550 0 C. Adaptability of the CANDU design to different fuel cycles is another technology advantage that offers an additional avenue for design evolution. Thorium is one of the potential fuels for future reactors due to relative abundance, neutronics advantage as a fertile material in thermal reactors and proliferation resistance. The Thorium fuel cycle is also of interest to China, India, and Turkey due to local abundance that can ensure sustainable energy independence over the long term. AECL has performed an assessment of both CANDU 6 and ACR-1000 designs to identify systems, components, safety features and operational processes that may need to be modified to replace the NU or SEU fuel cycles with one based on Thorium. The paper reviews some of these requirements and the associated practical design solutions. These modifications can either be incorporated into the design prior to construction or, for currently operational reactors, during a refurbishment outage. In parallel with reactor modifications, various Thorium fuel cycles, either based on mixed bundles (homogeneous) or mixed channels (heterogeneous) have been assessed for technical and economic viability. Potential applications of a

REGENERATION OF FISSION-PRODUCT-CONTAINING MAGNESIUM-THORIUM ALLOYS

Science.gov (United States)

Chiotti, P.

1964-02-01

A process of regenerating a magnesium-thorium alloy contaminated with fission products, protactinium, and uranium is presented. A molten mixture of KCl--LiCl-MgCl/sub 2/ is added to the molten alloy whereby the alkali, alkaline parth, and rare earth fission products (including yttrium) and some of the thorium and uranium are chlorinated and

Thorium-U Recycle Facility (7930)

Data.gov (United States)

Federal Laboratory Consortium — The Thorium-U Recycle Facility (7930), along with the Transuranic Processing Facility (7920). comprise the Radiochemical Engineering Development Complex. 7930 is a...

Determination of the total nitrate content of thorium nitrate solution with a selective electrode

International Nuclear Information System (INIS)

Wirkner, F.M.

1979-01-01

The nitrate content of thorium nitrate solutions is determined with a liquid membrane nitrate selective electrode utilizing the known addition method in 0.1 M potassium fluoride medium as ionic strength adjustor. It is studied the influence of pH and the presence of chloride, sulphate, phosphate, meta-silicate, thorium, rare earths, iron, titanium, uranium and zirconium at the same concentrations as for the aqueous feed solutions in the thorium purification process. The method is tested in synthetic samples and in samples proceeding from nitric dissolutions of thorium hidroxide and thorium oxicarbonate utilized as thorium concentrates to be purified [pt

Enhanced fuel production in thorium/lithium hybrid blankets utilizing uranium multipliers

International Nuclear Information System (INIS)

Pitulski, R.H.

1979-10-01

A consistent neutronics analysis is performed to determine the effectiveness of uranium bearing neutron multiplier zones on increasing the production of U 233 in thorium/lithium blankets for use in a tokamak fusion-fission hybrid reactor. The nuclear performance of these blankets is evaluated as a function of zone thicknesses and exposure by using the coupled transport burnup code ANISN-CINDER-HIC. Various parameters such as U 233 , Pu 239 , and H 3 production rates, the blanket energy multiplication, isotopic composition of the fuels, and neutron leakages into the various zones are evaluated during a 5 year (6 MW.y.m -2 ) exposure period. Although the results of this study were obtained for a tokomak magnetic fusion device, the qualitative behavior associated with the use of the uranium bearing neutron multiplier should be applicable to all fusion-fission hybrids

Computer simulations for thorium doped tungsten crystals

Energy Technology Data Exchange (ETDEWEB)

Eberhard, Bernd

2009-07-17

Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO{sub 2}, as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a

Thorium based fuel options for the generation of electricity: Developments in the 1990s

International Nuclear Information System (INIS)

2000-05-01

The IAEA has maintained an interest in the thorium fuel cycle and its worldwide utilization within its framework of activities. Periodic reviews have assessed the current status of this fuel cycle, worldwide applications, economic benefits, and perceived advantages with respect to other nuclear fuel cycles. Since 1994, the IAEA convened a number of technical meetings on the thorium fuel cycle and related issues. Between 1995 and 1997 individual contributions on the thorium fuel cycle were elicited from experts from France, Germany, India, Japan, the Russian Federation and the USA. These contributions included evaluations of the status of the thorium fuel cycle worldwide; the new incentives to use thorium due to large stockpiles of plutonium produced in nuclear reactors; new reactor concepts utilizing thorium; strategies for thorium use; and an evaluation of toxicity of the thorium fuel cycle waste compared to that from other fuel cycles. The results of this updated evaluation are summarized in this publication

Thorium Molten Salt Nuclear Energy Synergetic System (THORIMS-NES)

International Nuclear Information System (INIS)

Yoshioka, Ritsuo; Mitachi, Koshi

2013-01-01

The authors have been promoting nuclear energy technology based on thorium molten salt as Thorium Molten Salt Nuclear Energy Synergetic System (THORIMS-NES). This system is a combination of fission power reactor of Molten Salt Reactor (MSR), and Accelerator Molten Salt Breeder (AMSB) for production of fissile 233 U with connecting chemical processing facility. In this paper, concept of THORIMS-NES, advantages of thorium and molten salt recent MSR design results such as FUJI-U3 using 233 U fuel, FUJI-Pu, large sized super-FUJI, pilot plant miniFUJI, AMSB, and chemical processing facility are described. (author)

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.

Studies of the presence of gamma emitters in the natural environment of eastern Poland

International Nuclear Information System (INIS)

Chibowski, S.; Szczypa, J.; Zygmunt, J.

1996-01-01

Radioactive pollution of natural environment is produced by continual fall out of dusts and aerosols containing radioactive isotopes. These isotopes come to atmosphere as a result of coal combustion, nuclear explosions and nuclear incidents. The level of contamination is increased by activity of man, who employs isotopes in industry, agriculture, science and medicine. Traditional power industry, based on coal fuel, is a source of uranium and thorium series. So, all in all, contamination of territory is a sum of all above elements

Dynamic Analysis of the Thorium Fuel Cycle in CANDU Reactors

International Nuclear Information System (INIS)

Jeong, Chang Joon; Park, Chang Je

2006-02-01

The thorium fuel recycle scenarios through the Canada deuterium uranium (CANDU) reactor have been analyzed for two types of thorium fuel: homogeneous ThO 2 UO 2 and ThO 2 UO 2 -DUPIC fuels. The recycling is performed through the dry process fuel technology which has a proliferation resistance. For the once-through fuel cycle model, the existing nuclear power plant construction plan was considered up to 2016, while the nuclear demand growth rate from the year 2016 was assumed to be 0%. After setting up the once-through fuel cycle model, the thorium fuel CANDU reactor was modeled to investigate the fuel cycle parameters. In this analysis, the spent fuel inventory as well as the amount of plutonium, minor actinides and fission products of the multiple recycling fuel cycle were estimated and compared to those of the once-through fuel cycle. From the analysis results, it was found that the closed or partially closed thorium fuel cycle can be constructed through the dry process technology. Also, it is known that both the homogeneous and heterogeneous thorium fuel cycles can reduce the SF accumulation and save the natural uranium resource compared with the once-through cycle. From the material balance view point, the heterogeneous thorium fuel cycle seems to be more feasible. It is recommended, however, the economic analysis should be performed in future

Dynamic Analysis of the Thorium Fuel Cycle in CANDU Reactors

Energy Technology Data Exchange (ETDEWEB)

Jeong, Chang Joon; Park, Chang Je

2006-02-15

The thorium fuel recycle scenarios through the Canada deuterium uranium (CANDU) reactor have been analyzed for two types of thorium fuel: homogeneous ThO{sub 2}UO{sub 2} and ThO{sub 2}UO{sub 2}-DUPIC fuels. The recycling is performed through the dry process fuel technology which has a proliferation resistance. For the once-through fuel cycle model, the existing nuclear power plant construction plan was considered up to 2016, while the nuclear demand growth rate from the year 2016 was assumed to be 0%. After setting up the once-through fuel cycle model, the thorium fuel CANDU reactor was modeled to investigate the fuel cycle parameters. In this analysis, the spent fuel inventory as well as the amount of plutonium, minor actinides and fission products of the multiple recycling fuel cycle were estimated and compared to those of the once-through fuel cycle. From the analysis results, it was found that the closed or partially closed thorium fuel cycle can be constructed through the dry process technology. Also, it is known that both the homogeneous and heterogeneous thorium fuel cycles can reduce the SF accumulation and save the natural uranium resource compared with the once-through cycle. From the material balance view point, the heterogeneous thorium fuel cycle seems to be more feasible. It is recommended, however, the economic analysis should be performed in future.

An optical chemical sensor for thorium (IV) determination based on thorin

International Nuclear Information System (INIS)

Rastegarzadeh, S.; Pourreza, N.; Saeedi, I.

2010-01-01

A selective method for the determination of thorium (IV) using an optical sensor is described. The sensing membrane is prepared by immobilization of thorin-methyltrioctylammonium ion pair on triacetylcellulose polymer. The sensor produced a linear response for thorium (IV) concentration in the range of 6.46 x 10 -6 to 9.91 x 10 -5 mol L -1 with detection limit of 1.85 x 10 -6 mol L -1 . The regeneration of optode was accomplished completely at a short time (less than 20 s) with 0.1 mol L -1 of oxalate ion solution. The relative standard deviation for ten replicate measurements of 2.15 x 10 -5 and 8.62 x 10 -5 mol L -1 of thorium was 2.71 and 1.65%, respectively. The optode membrane exhibits good selectivity for thorium (IV) over several other ionic species and are comparable to those obtained in case of spectrophotometric determination of thorium using thorin in solution. A good agreement with the ICP-MS and spiked method was achieved when the proposed optode was applied to the determination of thorium (IV) in dust and water samples.

An optical chemical sensor for thorium (IV) determination based on thorin.

Science.gov (United States)

Rastegarzadeh, S; Pourreza, N; Saeedi, I

2010-01-15

A selective method for the determination of thorium (IV) using an optical sensor is described. The sensing membrane is prepared by immobilization of thorin-methyltrioctylammonium ion pair on triacetylcellulose polymer. The sensor produced a linear response for thorium (IV) concentration in the range of 6.46 x 10(-6) to 9.91 x 10(-5)mol L(-1) with detection limit of 1.85 x 10(-6)mol L(-1). The regeneration of optode was accomplished completely at a short time (less than 20s) with 0.1 mol L(-1) of oxalate ion solution. The relative standard deviation for ten replicate measurements of 2.15 x 10(-5) and 8.62 x 10(-5)mol L(-1) of thorium was 2.71 and 1.65%, respectively. The optode membrane exhibits good selectivity for thorium (IV) over several other ionic species and are comparable to those obtained in case of spectrophotometric determination of thorium using thorin in solution. A good agreement with the ICP-MS and spiked method was achieved when the proposed optode was applied to the determination of thorium (IV) in dust and water samples.

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

238 series isotopes at different soil depths and disequilibrium over various geology and soil classifications along transects in selected parts of Ireland

International Nuclear Information System (INIS)

McAulay, I.R.; Hayes, A.

1996-01-01

Sampling of soils was carried out along linear transects in selected regions of the country, a technique known as Transect Sampling. This was a controlled rather than a random sampling technique. The transects were located in regions which were previously known to contain high levels of the 226 Ra isotope, from the 238 U series. The soil sampling was carried out at selected sites along these transects. At each transect site, two different soil depths were examined and the soil samples collected were identified as the top and bottom soil samples. This transect data set, consisting of the isotope activity levels and the influencing variables transect geology and soil types, provided a data base for investigation. Comparisons were made between the soil isotope activity levels measured at different soil depths. An examination of the 238 U decay series showed the existence of disequilibrium. Relationships between the disequilibrium data and the associated geology and soil types were investigated. (author)

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)

Reprocessing in the thorium fuel cycle

International Nuclear Information System (INIS)

Merz, E.

1984-01-01

An overview of the authors personal view is presented on open questions in regard to still required research and development work for the thorium fuel cycle before its application in a technical-industrial scale may be tackled. For a better understanding, all stations of the back-end of the thorium fuel cycle are briefly illustrated and their special features discussed. They include storage and transportation measures, all steps of reprocessing, as well as the entire radioactive waste treatment. Knowledge gaps are, as far as they are obvious, identified and proposals put forward for additional worthwile investigations. (orig.) [de

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

Effect of Thorium on Growth and Uptake of Some Elements by Maize Plant

International Nuclear Information System (INIS)

Al-Shobaki, M.E.E.

2012-01-01

A pot experiment (sand culture) was carried out to investigate the effect of thorium on maize dry matter yield, contents and uptake of N,P ,K, Na and Fe and thorium accumulation in maize plant.The pots were contaminated by thorium as Thorium Nitrate(Th (NO 3 ) 4 ,H 2 O)at concentrations 0,5,10,11,12,13,14,15 and 50 ppm. Pots irrigated by 1/10 Hogland solution for 15 days, increased tol/4 Hogland solution after that.The results show that the dry matter (shoot, root and whole plant)decreased with increasing thorium concentration in soil up to 12 ppm and slightly increased with increasing Th to 13 ppm . The Nitrogen content and its uptake decreased with increasing thorium concentration in media growth up to 11 ppm .They were slightly increased at Th concentration between 11-14 ppm in maize shoot and root. The shoots always contained N-content and uptake more than that found in roots . P- uptake decreased in both shoots and roots with increasing in thorium concentration in media growth.

Influence of plant activity and phosphates on thorium bioavailability in soils from Baotou area, Inner Mongolia

International Nuclear Information System (INIS)

Guo Pengran; Jia Xiaoyu; Duan Taicheng; Xu Jingwei; Chen Hangting

2010-01-01

Harm of thorium to living organisms is governed by its bioavailability. Thorium bioavailability in the soil-plant system of Baotou rare earth industrial area was studied using pot experiments of wheat and single extraction methods. The effects of wheat growth stage and phosphate on thorium bioavailability were also investigated. Based on extractabilities of various extraction methods (CaCl 2 , NH 4 NO 3 , EDTA, HOAc) and correlation analysis of thorium uptake by wheat plant and extractable thorium, a mixture of 0.02 M EDTA + 0.5 M NH 4 OAc (pH 4.6) was found suitable for evaluation of thorium bioavailability in Baotou soil, which could be predicted quantitatively by multiple regression models. Because of differences of wheat root activities, thorium bioavailability in rhizosphere soil was higher than in bulk soil at tillering stage, but the reverse occurred at jointing stage. Phosphate addition induced the mineralization of soluble thorium by forming stable thorium phosphate compounds, and reduced thorium bioavailability in soil.

Influence of plant activity and phosphates on thorium bioavailability in soils from Baotou area, Inner Mongolia

Energy Technology Data Exchange (ETDEWEB)

Guo Pengran [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, 5625 Renmin Street, Changchun, Jilin 130022 (China); School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Jia Xiaoyu; Duan Taicheng; Xu Jingwei [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, 5625 Renmin Street, Changchun, Jilin 130022 (China); Chen Hangting, E-mail: guopengran@gmail.co [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, 5625 Renmin Street, Changchun, Jilin 130022 (China)

2010-09-15

Harm of thorium to living organisms is governed by its bioavailability. Thorium bioavailability in the soil-plant system of Baotou rare earth industrial area was studied using pot experiments of wheat and single extraction methods. The effects of wheat growth stage and phosphate on thorium bioavailability were also investigated. Based on extractabilities of various extraction methods (CaCl{sub 2}, NH{sub 4}NO{sub 3}, EDTA, HOAc) and correlation analysis of thorium uptake by wheat plant and extractable thorium, a mixture of 0.02 M EDTA + 0.5 M NH{sub 4}OAc (pH 4.6) was found suitable for evaluation of thorium bioavailability in Baotou soil, which could be predicted quantitatively by multiple regression models. Because of differences of wheat root activities, thorium bioavailability in rhizosphere soil was higher than in bulk soil at tillering stage, but the reverse occurred at jointing stage. Phosphate addition induced the mineralization of soluble thorium by forming stable thorium phosphate compounds, and reduced thorium bioavailability in soil.

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

Feasibility and desirability of employing the thorium fuel cycle for power generation - 254

International Nuclear Information System (INIS)

Sehgal, B.R.

2010-01-01

Thorium fuel cycle for nuclear power generation has been considered since the very start of the nuclear power era. In spite of a very large amount of research, experimentation, pilot scale and prototypic scale installations, the thorium fuel was not adopted for large scale power generation [1,2]. This paper reviews the developments over the years on the front and the back-end of the thorium fuel cycle and describes the pros and cons of employing the thorium fuel cycle for large generation of nuclear power. It examines the feasibility and desirability of employing the thorium fuel cycle in concert with the uranium fuel cycle for power generation. (authors)

Introduction of Thorium in the Nuclear Fuel Cycle. Short- to long-term considerations

International Nuclear Information System (INIS)

Allibert, M.; Merle-Lucotte, E.; Ghetta, V.; Ault, T.; Krahn, S.; Wymer, R.; Croff, A.; Baron, P.; Chauvin, N.; Eschbach, R.; Rimpault, G.; Serp, J.; Bergeron, A.; Bromley, B.; Floyd, M.; Hamilton, H.; Hyland, B.; Wojtaszek, D.; McDonald, M.; Collins, E.; Cornet, S.; Michel-Sendis, F.; ); Feinberg, O.; Ignatiev, V.; Hesketh, K.; Kelly, J.F.; Porsch, D.; Vidal, J.; Taiwo, T.; Uhlir, J.; Van Den Durpel, L.; Van Den Eynde, G.; Vitanza, C.; Butler, Gregg; Cornet, Stephanie; Dujardin, Thierry; Greneche, Dominique; Nordborg, Claes; Rimpault, Gerald; Van Den Durpel, Luc; Michel-Sendis, Franco

2015-01-01

Since the beginning of the nuclear era, significant scientific attention has been given to thorium's potential as a nuclear fuel. Although the thorium fuel cycle has never been fully developed, the opportunities and challenges that might arise from the use of thorium in the nuclear fuel cycle are still being studied in many countries and in the context of diverse international programmes around the world. This report provides a scientific assessment of thorium's potential role in nuclear energy both in the short to longer term, addressing diverse options, potential drivers and current impediments to be considered if thorium fuel cycles are to be pursued. (authors)

Mechanical structure and problem of thorium molten salt reactor

International Nuclear Information System (INIS)

Kamei, Takashi

2011-01-01

After Fukushima Daiichi accident, there became great interest in Thorium Molten Salt Reactor (MSR) for the safety as station blackout leading to auto drainage of molten salts with freeze valve. This article described mechanical structure of MSR and problems of materials and pipes. Material corrosion problem by molten salts would be solved using modified Hastelloy N with Ti and Nb added, which should be confirmed by operation of an experimental reactor. Trends in international activities of MSR were also referred including China declaring MSR development in January 2011 to solve thorium contamination issues at rare earth production and India rich in thorium resources. (T. Tanaka)

Integral benchmarks with reference to thorium fuel cycle

International Nuclear Information System (INIS)

Ganesan, S.

2003-01-01

This is a power point presentation about the Indian participation in the CRP 'Evaluated Data for the Thorium-Uranium fuel cycle'. The plans and scope of the Indian participation are to provide selected integral experimental benchmarks for nuclear data validation, including Indian Thorium burn up benchmarks, post-irradiation examination studies, comparison of basic evaluated data files and analysis of selected benchmarks for Th-U fuel cycle

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)

Component activities in the system thorium nitrate-nitric acid-water at 25oC

International Nuclear Information System (INIS)

Lemire, R.J.; Brown, C.P.

1982-01-01

The equilibrium composition of the vapor above thorium nitrate-nitric acid-water mixtures has been studied as a function of the concentrations of thorium nitrate and nitric acid using a transpiration technique. At 25 o C, the thorium nitrate concentrations m T ranged from 0.1 to 2.5 molal and the nitric acid concentrations m N from 0.3 to 25 molal. The vapor pressure of the nitric acid was found to increase with increasing thorium nitrate concentration for a constant molality of nitric acid in aqueous solution. At constant m T , the nitric acid vapor pressure was particularly enhanced at low nitric acid concentrations. The water vapor pressures decreased regularly with increasing concentrations of both nitric acid and thorium nitrate. The experimental data were fitted to Scatchard's ion-component model, and to empirical multiparameter functions. From the fitting parameters, and available literature data for the nitric acid-water and thorium nitrate-water systems at 25 o C, expressions were calculated for the variation of water and thorium nitrate activities, as functions of the nitric acid and thorium nitrate concentrations, using the Gibbs-Duhem equation. Calculated values for the thorium nitrate activities were strongly dependent on the form of the function originally used to fit the vapor pressure data. (author)

Thorium: in search of a global solution

CERN Multimedia

Antonella Del Rosso

2013-01-01

Last week, an international conference held at CERN brought together the world’s main experts in the field of alternative nuclear technology for the first time to discuss the use of thorium for the production of energy and the destruction of nuclear waste. Among the different technologies presented and discussed at the conference was ADS (Accelerator-Driven Systems) which relies primarily on particle accelerators.   The conference Chair (far left), the organisers and some of the distinguished participants of the ThEC13 conference held at CERN from 27 to 31 October 2013. “CERN has always been interested in finding ways in which fundamental research can help to resolve the problems of society,” says Jean-Pierre Revol, a physicist at the ALICE experiment who recently retired from CERN and is President of iThEC, the international not-for-profit organisation which promotes research and development in the field of thorium and which organised the Thorium Energy 2013 (Th...

Complexation of thorium with pyridine monocarboxylates: A thermodynamic study by experiment and theory

International Nuclear Information System (INIS)

Rama Mohana Rao, D.; Rawat, Neetika; Manna, D.; Sawant, R.M.; Ghanty, T.K.; Tomar, B.S.

2013-01-01

Highlights: ► The thermodynamic parameters have been determined for the first time. ► The Th-picolinate complexation was exothermic in nature. ► The complexation of Th(IV) with the other two isomers was endothermic process. ► Isonicotinate forms stronger complexes than nicotinate with Th(IV). ► The theoretically calculated values are in line with the experimental results. -- Abstract: Complexation of thorium with pyridine monocarboxylates namely picolinic acid (pyridine-2-carboxylic acid), nicotinic acid (pyridine-3-carboxylic acid) and isonicotinic acid (pyridine-4-carboxylic acid) has been studied by potentiometry and calorimetry to determine the thermodynamic parameters (log K, ΔG, ΔH and ΔS) of complexation. All the studies were carried out at 1.0 M ionic strength adjusted by NaClO 4 and at a temperature of 298 K. The detailed analysis of potentiometric data by Hyperquad confirmed the formation of four complexes, ML i (i = 1–4) in case of picolinate but only one complex (ML) in case of nicotinate and isonicotinate. The stepwise formation constant for ML complex (log K ML ) of thorium-picolinate is higher than those of thorium-nicotinate and thorium-isonicotinate complexes. Further the changes in enthalpy during formation of thorium-picolinate complexes are negative whereas the same for the complexes of thorium with the other two isomers was positive. This difference in the complexation process is attributed to chelate formation in case of thorium-picolinate complexes in which the thorium ion is bound to the picolinate through both the nitrogen in the pyridyl ring and one of the carboxylate oxygen atoms. The complexation process of thorium-nicotinate and thorium-isonicotinate are found to be endothermic in nature and are entropy driven confirming the similar binding nature as in simple carboxylate complexes of thorium. The complexation energies, bond lengths and charges on each atom in the complexes of various possible geometries were calculated

Technology of thorium concentrates purification and their transformation in pure nuclear products

International Nuclear Information System (INIS)

Ikuta, A.

1977-01-01

An experimental study for the purification of thorium concentrates by solvent extraction is presented. The product of purification is appropriate for utilization in the fabrication of nuclear reactor fuel elements. The experiments are carried out in a laboratory scale and the following operations are studied: dissolution, extraction-scrubbing, stripping-scrubbing, thorium oxalate precipitation, and thorium nitrate coagulation [pt

Simulating evaporation of surface atoms of thorium-alloyed tungsten in strong electronic fields

International Nuclear Information System (INIS)

Bochkanov, P.V.; Mordyuk, V.S.; Ivanov, Yu.I.

1984-01-01

By the Monte Carlo method simulating evaporation of surface atoms of thorium - alloyed tungsten in strong electric fields is realized. The strongest evaporation of surface atoms of pure tungsten as compared with thorium-alloyed tungsten in the contentration range of thorium atoms in tungsten matrix (1.5-15%) is shown. The evaporation rate increases with thorium atoms concentration. Determined is in relative units the surface atoms evaporation rate depending on surface temperature and electric field stront

Study of treatment of a thorium and rare earths residue by extraction chromatography

International Nuclear Information System (INIS)

Zini, Josiane; Abrao, Alcidio; Carvalho, Fatima Maria Sequeira de; Freitas, Antonio Alves de; Scapin, Marcos Antonio

2005-01-01

In the 70's was established at IPEN the project of a thorium compounds purification pilot plant that had the goal of fulfilling the nuclear technology purity standards. The used method was the purification by extraction with solvents in pulsed columns. The thorium remaining in the organic phase was back extracted as thorium nitrate with a high degree of purity. Impurities, thorium non-extracted and practically all rare earths in aqueous phase of this chemical process were precipitated as hydroxide, generating a product containing thorium and rare earths, that was denominated RETOTER (residue of thorium and rare earths). This residue was accumulated and today there are 25 (twenty-five) metric tons of this by product stored in the safeguard storage shed at IPEN that must to be treated due to the radiation of the thorium and mainly his daughters. The average composition of this residue is, 68% in thorium oxide (ThO 2 ), 5% in rare earths oxides (R 2 O 3 ), 0,3% in uranium oxide (U 3 O 8 ) and common impurities such as phosphorus, iron, titanium, lead and sodium. In this work a new method is presented for separation and purification of thorium from this residue, obtaining a concentrate with high degree of purity for nuclear and non-nuclear use. This process will contribute to establish a decreasing of residue volumes, to have a mind to the minimization of environmental impacts, the reduction of worker's exposition and reduction of the storage costs. In this process the separation and purification of uranium and thorium is done by chromatography extraction, being used polymeric resins, that are previously functionalized with organic solvent (extractor agent). The effluent of this process is a concentrate of rare earths that can be reprocessed in a subsequent fractionating for to obtaining the individual fractions. (author)

Self-Sustaining Thorium Boiling Water Reactors

International Nuclear Information System (INIS)

Greenspan, Ehud; Gorman, Phillip M.; Bogetic, Sandra; Seifried, Jeffrey E.; Zhang, Guanheng; Varela, Christopher R.; Fratoni, Massimiliano; Vijic, Jasmina J.; Downar, Thomas; Hall, Andrew; Ward, Andrew; Jarrett, Michael; Wysocki, Aaron; Xu, Yunlin; Kazimi, Mujid; Shirvan, Koroush; Mieloszyk, Alexander; Todosow, Michael; Brown, Nicolas; Cheng, Lap

2015-01-01

The primary objectives of this project are to: Perform a pre-conceptual design of a core for an alternative to the Hitachi proposed fuel-self- sustaining RBWR-AC, to be referred to as a RBWR-Th. The use of thorium fuel is expected to assure negative void coefficient of reactivity (versus positive of the RBWR-AC) and improve reactor safety; Perform a pre-conceptual design of an alternative core to the Hitachi proposed LWR TRU transmuting RBWR-TB2, to be referred to as the RBWR-TR. In addition to improved safety, use of thorium for the fertile fuel is expected to improve the TRU transmutation effectiveness; Compare the RBWR-Th and RBWR-TR performance against that of the Hitachi RBWR core designs and sodium cooled fast reactor counterparts - the ARR and ABR; and, Perform a viability assessment of the thorium-based RBWR design concepts to be identified along with their associated fuel cycle, a technology gap analysis, and a technology development roadmap. A description of the work performed and of the results obtained is provided in this Overview Report and, in more detail, in the Attachments. The major findings of the study are summarized.

Self-Sustaining Thorium Boiling Water Reactors

Energy Technology Data Exchange (ETDEWEB)

Greenspan, Ehud [Univ. of California, Berkeley, CA (United States); Gorman, Phillip M. [Univ. of California, Berkeley, CA (United States); Bogetic, Sandra [Univ. of California, Berkeley, CA (United States); Seifried, Jeffrey E. [Univ. of California, Berkeley, CA (United States); Zhang, Guanheng [Univ. of California, Berkeley, CA (United States); Varela, Christopher R. [Univ. of California, Berkeley, CA (United States); Fratoni, Massimiliano [Univ. of California, Berkeley, CA (United States); Vijic, Jasmina J. [Univ. of California, Berkeley, CA (United States); Downar, Thomas [Univ. of Michigan, Ann Arbor, MI (United States); Hall, Andrew [Univ. of Michigan, Ann Arbor, MI (United States); Ward, Andrew [Univ. of Michigan, Ann Arbor, MI (United States); Jarrett, Michael [Univ. of Michigan, Ann Arbor, MI (United States); Wysocki, Aaron [Univ. of Michigan, Ann Arbor, MI (United States); Xu, Yunlin [Univ. of Michigan, Ann Arbor, MI (United States); Kazimi, Mujid [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Shirvan, Koroush [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Mieloszyk, Alexander [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Todosow, Michael [Brookhaven National Lab. (BNL), Upton, NY (United States); Brown, Nicolas [Brookhaven National Lab. (BNL), Upton, NY (United States); Cheng, Lap [Brookhaven National Lab. (BNL), Upton, NY (United States)

2015-03-15

The primary objectives of this project are to: Perform a pre-conceptual design of a core for an alternative to the Hitachi proposed fuel-self- sustaining RBWR-AC, to be referred to as a RBWR-Th. The use of thorium fuel is expected to assure negative void coefficient of reactivity (versus positive of the RBWR-AC) and improve reactor safety; Perform a pre-conceptual design of an alternative core to the Hitachi proposed LWR TRU transmuting RBWR-TB2, to be referred to as the RBWR-TR. In addition to improved safety, use of thorium for the fertile fuel is expected to improve the TRU transmutation effectiveness; Compare the RBWR-Th and RBWR-TR performance against that of the Hitachi RBWR core designs and sodium cooled fast reactor counterparts - the ARR and ABR; and, Perform a viability assessment of the thorium-based RBWR design concepts to be identified along with their associated fuel cycle, a technology gap analysis, and a technology development roadmap. A description of the work performed and of the results obtained is provided in this Overview Report and, in more detail, in the Attachments. The major findings of the study are summarized.

Partial thorium loading in the initial core of Kakrapar atomic power reactor

International Nuclear Information System (INIS)

Balakrishnan, M.R.

1993-01-01

The first unit of Kakrapar nuclear power station has gone critical with some thorium oxide fuel bundles loaded in its core. The thorium helps to flatten the power by reducing neutron flux in the centre of the reactor. However, the placing of the thorium had to be planned with care, because if the neutron flux at a point where a safety rod is located is depressed, the reactivity worth of the safety rod gets reduced. Using a dynamic programing approach, the Reactor Engineering Division of Bhabha Atomic Research Centre worked out a satisfactory configuration for loading the thorium bundles

Thorium determination by X-ray Fluorescence Spectrometry in simulated thorex process solutions

International Nuclear Information System (INIS)

Yamaura, M.; Matsuda, H.T.

1989-01-01

The X-ray fluorescence method for thorium determination in aqueous and organic (TBP-n-dodecane) solutions is described. The thin film-technique for sample preparation and a suitable internal standard have been used. Some parameters as analytical line, internal standard, filter paper, paper geometry, sample volume and measurement conditions were studied. Uranium, fission products, corrosion products and thorex reagent components were studied as interfering elements in the thorium analysis, as well as the matrix effect by using the thorex process simulated solutions the method to thorium determination in irradiated thorium solutions was applied. (M.J.C.) [pt

Once-through thorium cycles in Candu reactors

International Nuclear Information System (INIS)

Milgram, M.S.

1982-01-01

In once-through thorium cycles pure thorium fuel bundles can be irradiated conjointly with uranium fuel bundles in a CANDU reactor with parameters judiciously chosen such that the overall fuel cycle cost is competitive with other possibilities - notably low-enriched uranium. Uranium 233 can be created and stockpiled for possible future use with no imperative that it be used unless future conditions warrant, and a stockpile can be begun independently of the state of reprocessing technology. The existence and general properties of these cycles are discussed

Enhanced fuel production in thorium/lithium hybrid blankets utilizing uranium multipliers

Energy Technology Data Exchange (ETDEWEB)

Pitulski, R.H.

1979-10-01

A consistent neutronics analysis is performed to determine the effectiveness of uranium bearing neutron multiplier zones on increasing the production of U/sup 233/ in thorium/lithium blankets for use in a tokamak fusion-fission hybrid reactor. The nuclear performance of these blankets is evaluated as a function of zone thicknesses and exposure by using the coupled transport burnup code ANISN-CINDER-HIC. Various parameters such as U/sup 233/, Pu/sup 239/, and H/sup 3/ production rates, the blanket energy multiplication, isotopic composition of the fuels, and neutron leakages into the various zones are evaluated during a 5 year (6 MW.y.m/sup -2/) exposure period. Although the results of this study were obtained for a tokomak magnetic fusion device, the qualitative behavior associated with the use of the uranium bearing neutron multiplier should be applicable to all fusion-fission hybrids.

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

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

Chromatographic behavior of carbonate complexes of lanthanides and of thorium in alumina

International Nuclear Information System (INIS)

Tomida, E.K.

1977-01-01

The chromatographic behavior of some rare earth elements and thorium on alumina is studied in order to evaluate the possibility of separation from concentration of trace rare earths from high-purity thorium compounds. The effect of some factors on complex thorium carbonate formation and the extent of thorium solubility in sodium and potassium carbonate solutions investigated. The sorption of rare earth elements and thoriuum on alumina from alkali carbonate solution is observed, despite the reports that alumina acts as a cation exchanger in alkali media and that thorium and rare earths form stable anionic carbonate complexes. The formation of these elements between alumina and potassium carbonate solutions is studied as a function of pH, carbonate concentration and metal ion concentration. Also the elution of rare earths from alumina is studied and the best results are obtained with mineral acids and EDTA plus alkali carbonate solutions. The effect of some parameters as column aging, mixed solvents, column treatment with organic solvents, temperature, aluant concentration is investigated. Attempting to understand this sorption mechanism, some experiments with strongly basic anion exchanger and cation exchangers of strongly acid and weakly acid type are accomplished. It is observed that there are significant differences, in some conditions, between the behavior of rare earths and of thorium, pointing our the possibility of separation of one lanthanide from others and of these from thorium [pt

Effectiveness of intragastric administration of 8102 for removal of thorium-234 in rats

International Nuclear Information System (INIS)

Luo Meichu; Li Landi; Sun Meizhen; Ye Qian; Liu Yi

1992-01-01

8102, a 1,2-dihydroxy-3,6-bismethylamino diacetic derivative, is a new chelating agent for decorporation of radionuclides. The effectiveness of intragastric administration of this drug at different doses (50-1000 mg/kg of body) and at different times before or after giving thorium-234 in rats was reported. The results show that for rats given intragastricly 1000 mg/kg of 8102, the excretion of thorium-234 in urine for first two days is 4.5 times more than that for control rats and accumulations of thorium-234 in liver, skeleton and kidney for these rats were 30%, 62% and 68% as those for control rats, respectively. The effectiveness was reduced with decrease in dosage of 8102. Administration of 8102 at 1 or 2 h before injection of thorium-234 can improve the effectiveness for decorporation of thorium-234: accumulation of thorium-234 in liver was markedly less than that for rats given 8102 immediately after injection of thorium-234. Delayed administration of 9102 resulted in reduction of the effectiveness. The practicality of oral administration of 8102 in clinic for decorporation of radionuclides was discussed

Transmutation of minor actinide using thorium fueled BWR core

International Nuclear Information System (INIS)

Susilo, Jati

2002-01-01

One of the methods to conduct transmutation of minor actinide is the use of BWR with thorium fuel. Thorium fuel has a specific behaviour of producing a little secondary minor actinides. Transmutation of minor actinide is done by loading it in the BWR with thorium fuel through two methods, namely close recycle and accumulation recycle. The calculation of minor actinide composition produced, weigh of minor actinide transmuted, and percentage of reminder transmutation was carried SRAC. The calculations were done to equivalent cell modeling from one fuel rod of BWR. The results show that minor actinide transmutation is more effective using thorium fuel than uranium fuel, through both close recycle and accumulation recycle. Minor actinide transmutation weight show that the same value for those recycle for 5th recycle. And most of all minor actinide produced from 5 unit BWR uranium fuel can transmuted in the 6 t h of close recycle. And, the minimal value of excess reactivity of the core is 12,15 % Δk/k, that is possible value for core operation

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)

Use of thorium for high temperature gas-cooled reactors

Energy Technology Data Exchange (ETDEWEB)

Guimarães, Cláudio Q., E-mail: claudio_guimaraes@usp.br [Universidade de São Paulo (USP), SP (Brazil). Instituto de Física; Stefani, Giovanni L. de, E-mail: giovanni.stefani@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Santos, Thiago A. dos, E-mail: thiago.santos@ufabc.edu.br [Universidade Federal do ABC (UFABC), Santo André, SP (Brazil)

2017-07-01

The HTGR ( High Temperature Gas-cooled Reactor) is a 4{sup th} generation nuclear reactor and is fuelled by a mixture of graphite and fuel-bearing microspheres. There are two competitive designs of this reactor type: The German “pebble bed” mode, which is a system that uses spherical fuel elements, containing a graphite-and-fuel mixture coated in a graphite shell; and the American version, whose fuel is loaded into precisely located graphite hexagonal prisms that interlock to create the core of the vessel. In both variants, the coolant consists of helium pressurised. The HTGR system operates most efficiently with the thorium fuel cycle, however, so relatively little development has been carried out in this country on that cycle for HTGRs. In the Nuclear Engineering Centre of IPEN (Instituto de Pesquisas Energéticas e Nucleares), a study group is being formed linked to thorium reactors, whose proposal is to investigate reactors using thorium for {sup 233}U production and rejects burning. The present work intends to show the use of thorium in HTGRs, their advantages and disadvantages and its feasibility. (author)

Design and evaluation of a thorium (IV) selective optode

International Nuclear Information System (INIS)

Safavi, Afsaneh; Sadeghi, Marzieh

2006-01-01

A novel optical sensor has been proposed for sensitive determination of thorium (IV) ion in aqueous solutions. The thorium sensing membrane was prepared by incorporating 4-(p-nitrophenyl azo)-pyrocatechol (NAP) as ionophore in the plasticized PVC membrane containing tributyl phosphate (TBP) as plasticizer. The membrane responds to thorium ion by changing color reversibly from yellow to red-brown in glycine buffer solution at pH 3.5. The proposed sensor displays a linear range of 8.66 x 10 -6 -2.00 x 10 -4 M with a limit of detection of 6 x 10 -6 M. The response time of the optode was about 8.8-12.5 min, depending on the concentration of Th (IV) ions. The selectivity of optode to Th (IV) ions in glycine buffer is good. The sensor can readily be regenerated by exposure to a solution mixture of sodium fluoride and 5-sulfosalicylic acid (dihydrate) (0.01 M each). The optode is fully reversible. The proposed optode was applied to the determination of thorium (IV) in environmental water samples

Flowchart evaluations of irradiated fuel treatment process of low burnup thorium

International Nuclear Information System (INIS)

Linardi, M.

1987-01-01

A literature survey has been carried out, on some versions of the acid-thorex process. Flowsheets of the different parts of the process were evaluated with mixer-settlers experiments. A low burnup thorium fuel (mass ratio Th/U∼100/1), proposed for Brazilian fast breeder reactor initial program, was considered. The behaviour of some fission products was studied by irradiated tracers techniques. Modifications in some of the process parameters were necessary to achieve low losses of 233 U and 232 U and 232 Th. A modified acid-thorex process flowsheet, evaluated in a complete operational cycle, for the treatment of low burnup thorium fuels, is presented. High decontamination factors of thorium in uranium, with reasonable decontamination of uranium in thorium, were achieved. (author) [pt

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

Separation of thorium from cerium by the ion-exchange sorption method. Pt. 3

International Nuclear Information System (INIS)

Sozanski, A.

1981-01-01

The method is described of separation of trace-quantities of thorium from chloride and ceric sulfate solutions. Thorium is sorbed selectively on the ion exchanger chelating Vofatite MC-50. Thorium-free ceric solutions were achieved and after ionite eluation concentrates of oxides were considerably enriched. (author)

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...

Analytical method for the isotopic characterization of soils

International Nuclear Information System (INIS)

Sibello Hernandez, Rita; Cozzella, Maria Letizia; Mariani, Mario

2014-01-01

The aim of this work was to develop an analytical method in order to determine the isotopic composition of different elements in soil samples and to determine the existence of contamination. The method used in the digestion of the samples was the EPA 3050B, and some metal concentration were determined including uranium and thorium. For elements with even lower concentrations such as plutonium and radium a treatment after mineralization by EPA, was necessary. The measurement technique used was mass spectrometry with quadrupole and plasma induced associated (ICP-MS). Results of the analysis performed in two laboratories showed a good correspondence. This method allowed to perform the isotopic characterization of studied soils and results showed that the studied soils do not present any local pollution and that the presence of plutonium-239, is due to global failure

Historical and perspectives of thorium compounds production and purification at IPEN-CNEN/SP

International Nuclear Information System (INIS)

Lainetti, Paulo E.O.; Abrao, A.; Freitas, Antonio A.; Carvalho, Fatima M.S. de; Bergamaschi, Vanderlei S.; Cunha, Edgar F.; Ayoub, Jamil M.S.; Mindrisz, Ana C.

2000-01-01

The production and purification of some thorium compounds has been performed in the IPEN in the last 15 years. Some raw materials have been employed in this production, obtained from the monazite exploitation in industrial scale that it was performed in Sao paulo during the period 1948 until 1994. More than 160 t of high purity thorium nitrate were produced, purified by the solvent extraction process. The thorium nitrate has been supplied for the Brazilian portable gaslight industry to the production of Welsbach Mantle. Nowadays, a new facility is being designed and built. The main concern is the recovering of the production capacity, lost after some years of operation without suitable maintenance. This activity has an important strategic role, considering the huge Brazilian thorium resources and the renewed interest in thorium fuel cycle. This paper describes a brief historical background of thorium activities in the IPEN as well as their perspectives. (author)

Thorium Energy Resources and its Potential of Georgian Republic, The Caucasus

Science.gov (United States)

Gogoladze, Salome; Okrostsvaridze, Avtandil

2017-04-01

Energy resources, currently consumed by modern civilization, are represented by hydrocarbons - 78-80 %, however these reserves are exhausting. In light of these challenges, search of new energy resources is vital importance problem for the modern civilization. Based on the analysis of existing energy reserves and potential, as the main energy resources for the future of our civilization, the renewable and nuclear energy should be considered. However, thorium has a number of advantages compared to Uranium (Kazimi, 2003; et al.): It is concentrated in the earth crust 4-5 times more than uranium; extraction and enrichment of thorium is much cheaper than uranium's; It is less radioactive; complete destruction of its waste products is possible; thorium yields much more energy than uranium. Because of unique properties and currently existed difficult energetic situation thorium is considered as the main green energy resource in the 3rd millennium of the human civilization (Martin, 2009). Georgia republic, which is situated in the central part of Caucasus, poor of hydrocarbons, but has a thorium resource important potential. In general the Caucasus represents a collisional orogen, that formed along the Eurasian North continental margin and extends over 1200 km from Caspian to Black Sea. Three major units are distinguished in its construction: the Greater and Lesser Caucasian mobile belts and the Transcaucasus microplate. Currently it represents the Tethyan segment connecting the Mediterranean and Iran-Himalayan orogenic belts, between the Gondvana-derived Arabian plate and East European platform. Now in Georgian Republic are marked thorium four ore occurrences (Okrostsvaridze, 2014): 1- in the Sothern slope of the Greater Caucasus, in the quartz -plagioclases veins (Th concentrations vary between 51g/t - 3882 g/t); 2- in the Transcaucasus Dzirula massif hydrothermally altered rocks of the Precambrian quartz-diorite gneisses (Th concentrations vary between 117 g/t -266 g

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.

Determination of thorium 230Th in soils

International Nuclear Information System (INIS)

Alvarez, A.; Palomares, J.

1988-01-01

A method for the determination of 230 Th in environmental soils is described. Hydroxides formed, previous fusion with sodium peroxide are dissolved with HNO 3 8N. The thorium is coprecipitated with F 3 La and purified by anion exchange (AG 1x8 50-100 mesh). Thorium is electroplated onto a stainless steel disc, 230 Th is counted by alpha spectrometry and 234 Th used as a tracer by beta counting. The chemical yield for 1g of soil sample is 60-80%. Minimum detectable activities are about 2 mBq/g. (Author)

Thorium deposits in the commonwealth of independent states and their prospective characteristics

International Nuclear Information System (INIS)

Kotova, V.M.; Skorovarov, J.I.

1997-01-01

Since 1956, the All-Russian Research Institute of Chemical Technology has been engaged in the research of assessing thorium deposits and ore occurrence, as well as developing its production technology from various ore types. From the known CIS thorium and thorium-bearing deposits and occurrences (2500) only 241 sites have their resources estimated. They include 132 monazite placers of the Quarternary age, 6 complex Quarternary deposits of placer type (4 polarite, 1 uranium-thorianite and 1 thorium-platinum placers), 66 endogenous deposits and occurrences and 38 complex ones (including zircon-ilmenite Tertiary and older buried placers). This paper gives a summary of the author's attempt to classify thorium deposits according to their genetic types. The proposed classification scheme is based on formational principles and integrates geological-tectonic, magmatic and other criterions. The deposits is based on formation principles and integrates geological-tectonic, magmatic and other criterions. The deposits which are located in igneous, metamorphic and sedimentary rocks are further observed according to their geological setting and types of mother rocks. Thorium deposits are known in the numerous metallogenetic provinces of the CIS. (author). 1 tab

Separation of Protactinium from Neutron Irradiated Thorium Oxide

International Nuclear Information System (INIS)

Dominguez, G.; Gutierrez, L.; Ropero, M.

1983-01-01

The chemical separation of thorium and protactinium can be carried out by leaching most of the last one, about 95%, with aqueous HF from neutron irradiated thorium oxide. This leaching reaction la highly favored by the transformation reaction of the ThO 2 material into ThF 4 . For both reactions, leaching and transformation, the reagents concentration, agitation speed and temperature influences were studied and the activation energies were found. (Author) 18 refs

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)

Spectrophotometric Determination of Thorium in Low Grade Minerals and Ores

Energy Technology Data Exchange (ETDEWEB)

Arnfelt, A L; Edmundsson, I

1960-08-15

The following method is intended for the determination of microgram quantities of thorium in samples of minerals and ores. The mineral sample is decomposed by repeated sintering with sodium peroxide. After digestion with water thorium peroxide hydrate is recovered by centrifugation and dissolved in hydrochloric acid. Thorium is determined spectrophotometrically with naphtarson after its separation from metals forming chloro complexes which are adsorbed on a strongly basic anion exchange resin. Interferences from a few different ions have been studied. The time required for the analysis of one sample is about 4 hours, when analysing 12 samples simultaneously

Spectrophotometric Determination of Thorium in Low Grade Minerals and Ores

International Nuclear Information System (INIS)

Arnfelt, A.L.; Edmundsson, I.

1960-08-01

The following method is intended for the determination of microgram quantities of thorium in samples of minerals and ores. The mineral sample is decomposed by repeated sintering with sodium peroxide. After digestion with water thorium peroxide hydrate is recovered by centrifugation and dissolved in hydrochloric acid. Thorium is determined spectrophotometrically with naphtarson after its separation from metals forming chloro complexes which are adsorbed on a strongly basic anion exchange resin. Interferences from a few different ions have been studied. The time required for the analysis of one sample is about 4 hours, when analysing 12 samples simultaneously

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)

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

Review of problems associated with the utilization of available thorium resources

International Nuclear Information System (INIS)

O'Hara, F.A.; Gray, R.A.

1975-01-01

Portions of the U. S. Thorium Stockpile are in danger of literally ''going to waste.'' These raw materials, with their high concentrations of thorium, are valuable resources which can be utilized to fuel thermal converter reactors. A portion of this stockpile was transferred to Mound Laboratory in the early 1950's. In 1972, the material was determined to be excess to all present and foreseeable future national requirements. Disposal by burial was recommended by the AEC. Following a detailed study of the potential usefulness of the material and the costs associated with land burial, the AEC agreed to offer the material on surplus sale. Risks and benefits associated with retention of the thorium stockpile are described. Nuclear Materials Managers are uniquely situated to exercise influence and direct the future course of remaining thorium reserves

Thorium content of a mineral ore from Morro do Ferro by fission track technique

International Nuclear Information System (INIS)

Oliveira, C.A.N. de.

1980-10-01

The feasibility to determine thorium concentrations by fission track technique in samples of mineral ore has been demonstrated. The literature registers only the application of the fission track technique to mineral ore in the case where the fissionable element is uranium. The technique was applied to determine the thorium concentration of an ore sample from Morro do Ferro, taking advantage of the high thorium to uranium ratio in that mineral. The sample analysed presented a thorium concentration of 2467 +- 400 mg Th/Kg ore. The so called wet method was adopted by using the Bayer made Makrofol KG 10μm thick, as the detector foil, immersed in the thorium solution. The technique is also useful to determine thorium concentrations in environmental samples because of the following aspects: high sensitivity; fast chemical separation of interfering elements; low cost; and operational simplicity. (Author) [pt

Activities of the research committee on thorium cycle in atomic energy society of Japan

International Nuclear Information System (INIS)

Hohki, Shiro

1985-01-01

In 1978 the Research Committee on Thorium Cycle was established as one of committees of the Atomic Energy Society of Japan, and the Committee published a report titled 'The Thorium Cycle - Present Status and Future Prospect' in October 1980 as a result of investigations on the status of the thoirum cycle in Japan as well as that in overseas. Based on this investigation, the Committee is intending to evaluate synthetically the thorium utilization in Japan under the prospect for the middle and long term by intensifying the activities of the Committee. Furthermore, from this viewpoint, the author supplements comments on following three points: (1) Reasons why the thorium utilization has not received positive evaluation in Japan; (2) Reasons why Japan has to pay attention to thorium; (3) How the technology on thorium should be developed in Japan. (author)

A study on the structure of thorium salt solutions

International Nuclear Information System (INIS)

Magini, M.; Cabrini, A.; Di Bartolomeo, A.

1975-01-01

The structure of highly hydrolyzed thorium salt solutions has been investigated by large and small angle X-ray scattering techniques. The diffraction data obtained with large angle measurements show the presence in solution of microcrystalline particles with the thorium oxide structure. Particles larger than those were discovered by small angle measurements. A possible shape of these colloidal particles has been discussed

Thorium spectrophotometric analysis with high precision

International Nuclear Information System (INIS)

Palmieri, H.E.L.

1983-06-01

An accurate and precise determination of thorium is proposed. Precision of about 0,1% is required for the determination of macroquantities of thorium processed. After an extensive literature search concerning this subject, spectrophotometric titration has been chosen, using disodium ethylenediaminetetraacetate (EDTA) solution and alizarin S as indicator. In order to obtain such a precision, an amount of 0,025 M EDTA solution precisely measured has been added and the titration was completed with less than 5 ml of 0,0025 M EDTA solution. It is usual to locate the end-point graphically, by plotting added titrant versus absorbance. The non-linear minimum square fit, using the Fletcher e Powell's minimization process and a computer program. (author)

Performance of Energy Multiplier Module (EM2) with long-burn thorium fuel cycle

International Nuclear Information System (INIS)

Choi, Hangbok; Schleicher, Robert; Gupta, Puja

2015-01-01

Energy Multiplier Module (EM 2 ) is a helium-cooled fast reactor being developed by General Atomics for the 21 st century grid. It is designed as a modular plant with a net electric output of 265 MWe with an evaporative heat sink and 240 MWe with an air-cooled heat sink. EM 2 core performance is examined for the baseline loading of low-enriched uranium (LEU) as fissile material with depleted uranium (DU) as fertile material and compared to the alternate LEU with thorium loading. The latter has two options: a heterogeneous loading of thorium fuel in the place of DU that produces a longer fuel cycle, and homogeneously mixed thorium-uranium fuel loading. Compared to the baseline LEU/DU core, the cycle length of both thorium options is reduced due to higher neutron absorptions by thorium. However, for both, heterogeneous and homogenous thorium loading options, the fuel cycle length is over 24 years without refueling or reshuffling of fuel assemblies. The physics properties of the EM 2 thorium core are close to those of the baseline core which constitute low excess reactivity, negative fuel temperature coefficient, and very small void reactivity. However, unlike the case of baseline EM 2 , the homogeneous thorium fuel loading provides additional advantage in reducing the power peaking of the core, which in turn reduces the cladding material neutron damage rate by 23%. It is interpreted that the relatively slow 233 U buildup as compared to 239 Pu for baseline core retards reactivity increase without the need for a complicated fuel loading pattern of the heterogeneous fuel loading, while maintaining the peak power density low. Therefore both the heterogeneous and homogeneous thorium loading options will be feasible in the EM 2

Measurements of Fission Cross Sections for the Isotopes relevant to the Thorium Fuel Cycle

CERN Multimedia

2002-01-01

The present concern about a sustainable energy supply is characterised by a considerable uncertainty: the green house effect and foreseeable limits in fossil fuel resources on the one hand, the concern about the environmental impact of nuclear fission energy and the long term fusion research on the other hand, have led to the consideration of a variety of advanced strategies for the nuclear fuel cycle and related nuclear energy systems. The present research directories concern such strategies as the extension of the life span of presently operating reactors, the increase of the fuel burn-up, the plutonium recycling, and in particular the incineration of actinides and long-Lived fission products, the accelerator driven systems (ADS), like the "Energy Amplifier" (EA) concept of C. Rubbia, and the possible use of the Thorium fuel cycle. The detailed feasibility study and safety assessment of these strategies requires the accurate knowledge of neutron nuclear reaction data. Both, higher fuel burn-up and especiall...

Long term radiological impact of thorium extraction

International Nuclear Information System (INIS)

Menard, S.; Schapira, J.P.

1995-01-01

Thorium extraction produces a certain amount of radioactive wastes. Potential long term radiological impact of these residues has been calculated using the recent ICRP-68 ingestion dose factors in connection with the computing code DECAY, developed at Orsay and described in this work. This code solves the well known Bateman's equations which govern the time dependence of a set of coupled radioactive nuclei. Monazites will be very likely the minerals to be exploited first, in case of an extensive use of thorium as nuclear fuel. Because monazites contain uranium as well, mining residues will contain not only the descendants of 232 Th and a certain proportion of non-extracted thorium (taken here to be 5%), but also this uranium, if left in the wastes for economical reasons. If no uranium would be present at all in the mineral, the potential radiotoxicity would strongly decrease in approximately 60 years, at the pace of the 5.8 years period of 228 Ra, which becomes the longest-lived radionuclide of the 4n radioactive family in the residues. Moreover, there is no risk due to radon exhalation, because of the very short period of 220 Rn. These significant differences between uranium and thorium mining have to be considered in view of some estimated long term real radiological impacts due to uranium residues, which could reach a value of the order of 1 mSv/year, the dose limit recommended for the public by the recent ICRP-60. (authors). 15 refs., 4 figs., 3 tabs., 43 appendices

Determination of rare earth elements, thorium and uranium by inductively coupled plasma mass spectrometry and strontium isotopes by thermal ionization mass spectrometry in soil samples of Bryansk region contaminated due to Chernobyl accident

International Nuclear Information System (INIS)

Sahoo, S.K.; Yonehara, H.; Kurotaki, K.; Shiraishi, K.; Ramzaev, V.; Barkovski, A.

2001-01-01

Inductively coupled plasma mass spectrometric (ICP-MS) determination of rare earth elements (REEs), thorium and uranium in forest, pasture, field and kitchen garden soils from a Russian territory and in certified reference materials (JLK-1, JSD-2 and BCR-1) is described. In addition to concentration data, strontium isotopic composition of the soil samples were measured by thermal ionization mass spectrometry. The measurements contributed to the understanding of the background levels of these elements in an area contaminated due to Chernobyl accident. There was not a significant variation in the concentration of REEs at different depth levels in forest soil samples, however, the ratio of Th/U varied from 3.32 to 3.60. Though concentration of U and Th varied to some extent, the ratio did not show much variation. The value of 87 Sr/ 86 Sr ratio, was in the top layer soil sample relatively higher than in the lower layers. (author)

Determination of rare earth impurities in thorium by spectrographic methods

Energy Technology Data Exchange (ETDEWEB)

Wray, L W

1957-08-15

A method for determining rare earth impurities in thorium in the fractional ppm range is described. Before spectrographic examination is possible, the impurities must be freed from the thorium matrix. This is accomplished by removing the bulk of the thorium by extraction with TBP-CCl{sub 4} and the remainder by extraction with TTA-C{sub 6}H{sub 6}. This results in a consistent recovery of rare earths of about 85% with an average sensitivity of 0.2 ppm. The experimental error is within 10%. Details of the procedure are given together with working curves for the major neutron absorbing rare earths; i.e. dysprosium, europium, gadolinium and samarium. (author)

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.

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)

Study of the thorium incorporation by inhalation in individuals occupationally exposed

International Nuclear Information System (INIS)

Holanda e Vasconcellos Carvalho, B. de.

1983-01-01

A mathematical model describing the metabolism of inhaled thorium in the human body was developed. Through this model theoretical limits of excretion were calculated for workers of a monazite plant (Usina Santo Amaro). This limits were based on International Commission on Radiological Protection publication 30, 1979. Excreta samples from twelve workers of Usina Santo Amaro were collected and analysed for thorium. All samples were bellow the theoretical limits of excretion indicating that Usina Santo Amaro workers are exposed to thorium levels bellow the Annual Limits of Intake recommended by ICRP, publication 30. (author)

Global recovery process of thorium and rare earths in a nitrate medium

International Nuclear Information System (INIS)

Cailly, F.; Mottot, Y.

1993-01-01

The aqueous solution of thorium and rare earth nitrates, obtained by leaching the ore with nitric acid, is extracted by an organic phosphorous compound (phosphate, phosphonate, phosphinate or phosphine oxide) and a cationic extractant chosen among phosphoric acid di-esters. Extraction of thorium and rare earths is possible even in presence of phosphate ions in the aqueous solution. Thorium and rare earths are separated by liquid-liquid extraction of the organic phase

Stable isotope compositions and water contents of boninite series volcanic rocks from Chichi-jima, Bonin Islands, Japan

Science.gov (United States)

Dobson, P.F.; O'Neil, J.R.

1987-01-01

Measurements of stable isotope compositions and water contents of boninite series volcanic rocks from the island of Chichi-jima, Bonin Islands, Japan, confirm that a large amount (1.6-2.4 wt.%) of primary water was present in these unusual magmas. An enrichment of 0.6??? in 18O during differentiation is explained by crystallization of 18O-depleted mafic phases. Silicic glasses have elevated ??18O values and relatively low ??D values indicating that they were modified by low-temperature alteration and hydration processes. Mafic glasses, on the other hand, have for the most part retained their primary isotopic signatures since Eocene time. Primary ??D values of -53 for boninite glasses are higher than those of MORB and suggest that the water was derived from subducted oceanic lithosphere. ?? 1987.

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)

Activities of AREVA Med. Extraction and purification of the 212Pb isotope from Thorium for radio-immunotherapy

International Nuclear Information System (INIS)

Miquel, Pierre

2012-01-01

After having recalled the definition of radio-immunotherapy (RIT) and the benefits of alpha RIT for the treatment of some cancers, this document explains the choice of the 212-Pb isotope instead of the 212-Bi isotope (the first one has a longer half-life than the second). The Pb isotope in fact progressively transforms itself into the Bi isotope. The production process is evoked with its important steps. A second part reports the first clinic tests performed in the Alabama Centre for the treatment of different cancer (breast, colon, ovarian, pancreas, stomach). Processes and doses are discussed

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

Radiochemical studies of neutron deficient actinide isotopes

International Nuclear Information System (INIS)

Williams, K.E.

1978-04-01

The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, 242 Bk, was produced with a cross-section of approximately 10 μb in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, αxn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,αxn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z 1 + Z 2 = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,αxn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of 228 Pu, 230 Pu, 232 Cm, or 238 Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes

Seasonal fluctuations of the uranium and thorium contents in aerosols in surface air

International Nuclear Information System (INIS)

Kolb, W.

1985-01-01

An estimate in the UNSCEAR report the only source considered for the uranium and thorium contents is ground dust. A significant portion of the aerosols, however, comes from chimneys. Aerosol samples taken monthly in Brunswick, Berlin, Skibotn (Northern Norway) were, therefore, scrutinized alpha-spectrometrically for U-238, U-234, Th-230, and Th-232. The activity concentration in surface air of Northern Norway is only about 30 nBq/cm 3 . In Brunswick and Berlin, the concentration was higher by a factor of one to two due to the higher specific activity of the mineral aerosols. Significant differences of the isotope ratios allow conclusions as to the origin of the aerosols. The activity concentrations measured and their seasonal fluctuations must be taken into account in the evaluation of environment monitoring of nuclear fuel factories. (orig./HP) [de

Indirect complexometric determination of thorium(IV) using sodium fluoride as masking agent

International Nuclear Information System (INIS)

Sreekumar, N.V.; Nazareth, R.A.; Narayana, B.; Hegde, P.; Manjunatha, B.R.

2002-01-01

A complexometric method for the determination of thorium(IV) in presence of other metal ions based on the selective masking ability of sodium fluoride towards thorium is described. Thorium(IV) present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated against bismuth nitrate solution at pH 2-3 using xylenol orange as indicator. A known excess of sodium fluoride (5 %) is then added and the EDTA released from the Th-EDTA complex is titrated against standard bismuth nitrate solution. Reproducible and accurate results are obtained for 5 mg to 280 mg of thorium with relative errors ±0.65 % and standard deviations /leq 0.75 mg. The interference of various ions was studied. (author)

A study of the use of seeded ultrafiltration for the treatment of Thorium-uranium mining waste streams

International Nuclear Information System (INIS)

El-Sourougy, M.R.; Hooper, E.W.

1994-01-01

The use of seeded ultrafiltration for the treatment of radioactive waste streams arising from the nuclear industry has demonstrated its high potential as an efficient process for the removal of radionuclides present in the radwaste streams. The experimental data on simulated mining streams has given indications on the suitability of this technique for the treatment of mining waste streams. The results also show that the proper choice of absorbers can reduce not only the radioactivity level but also remove most of the products of both the thorium and uranium decay series. Decontamination factor (DF) for the system using manganese dioxide (MnO 2 ) are only slightly affected by the preparation method. On the contrary, the DF achieved using titanium hydroxide (HTiO) absorber was found to be dependent on the preparation method. The experimental data shows that total activity levels can be reduced to below detection limit (3E-3Bq/ml). The extent of decontamination of thorium containing waste streams was found to be dependent on the absorber used; in the order Diuranate > HTiO > Fe(OH) 3 > MnO 2 . The use of HTiO reduced the decay product activity of almost all the thorium daughters to nearly background levels. A DF of the order of 300 can easily be achieved using diuranate floc

Neutronic design of a plutonium-thorium burner small nuclear reactor

International Nuclear Information System (INIS)

Hartanto, Donny

2010-02-01

A small nuclear reactor using thorium and plutonium fuel has been designed from the neutronic point of view. The thermal power of the reactor is 150 MWth and it is proposed to be used to supply electricity in an island in Indonesia. Thorium and plutonium fuel was chosen because in recent years the thorium fuel cycle is one of the promising ways to deal with the increasing number of plutonium stockpiles, either from the utilization of uranium fuel cycle or from nuclear weapon dismantling. A mixed fuel of thorium and plutonium will not generate the second generation of plutonium which will be a better way to incinerate the excess plutonium compared with the MOX fuel. Three kinds of plutonium grades which are the reactor grade (RG), weapon grade (WG), and spent fuel grade (SFG) plutonium, were evaluated as the thorium fuel mixture in the 17x17 Westinghouse PWR Fuel assembly. The evaluated parameters were the multiplication factor, plutonium depletion, fissile buildup, neutron spectrum, and temperature reactivity feedback. An optimization was also done to increase the plutonium depletion by changing the Moderator to Fuel Ratio (MFR). The computer codes TRITON (coupled NEWT and ORIGEN-S) in SCALE version 6 were used as the calculation tool for this assembly level. From the evaluation and optimization of the fuel assembly, the whole core was designed. The core was consisted of 2 types of thorium fuel with different plutonium grade and it followed the checkerboard loading pattern. A new concept of enriched burnable poison was also introduced to the core. The core life is 6.4 EFPY or 75 GWd/MTHM. It can burn up to 58% of its total mass of initial plutonium. VENTURE was used as the calculation tool for the core level

Resistivity recovery of neutron-irradiated and cold-worked thorium

International Nuclear Information System (INIS)

Tang, J.T.

1977-02-01

Results from a study of the resistivity recovery of neutron-irradiated and cold-worked thorium on isochronal annealing, activation energies, and isothermal annealing and kinetics are discussed. The nature and extent of radiation effects on the resistivity of thorium at 80 0 K, interpretation of stage II recovery above 80 0 K, and activation energy and interpretation of stage III recovery are also discussed. There are 79 references

The use of thorium as an alternative nuclear fuel

International Nuclear Information System (INIS)

Wilson, D.J.

1982-04-01

The use of thorium as an alternative or supplementary nuclear fuel is examined and compared with uranium. A description of various reactor types and their suitability to thorium fuel, and a description of various aspects of the fuel cycle from mining to waste disposal, are included. Comments are made on the safety and economics of each aspect of the fuel cycle and the extension of the lifetime of nuclear fuel

Study of thorium uptake by inhabitants of a high background radiation area

International Nuclear Information System (INIS)

Melo, D.R.; Lipsztein, J.L.; Juliao, L.M.Q.C.; Lourenco, M.C.; Lauria, D.

2002-01-01

Buena, located in the North of Rio de Janeiro, is characterized by its high natural radiation background, due to large deposits of monazite sand. The foodstuffs consumed by the population are basically composed of local products, which contain significant amounts of thorium. The analysis of complete cooked meals have shown an average daily intake of 18 mBq.d -1 of 232 Th and 189 mBq.d -1 of 228 Th. The average urine to feces ratio of 232 Th from samples of volunteers was found equal to 7.5x10 -2 . The comparison of the experimental data with the predicted urine to feces ratios derived using the biokinetic model for thorium described by the ICRP publication 69 and simulating inhalation and ingestion separately, lead to the conclusion that the thorium intake is a combination of inhalation and ingestion. The clearance rate of thorium of monazite in lungs has apparently behaved as Type M compound. Inhalation is the biggest contributor for the committed effective dose due to thorium internal exposure. (author)

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)

Sequential determination of U and Th isotopes, 226Ra, 228Ra, 210Pb, and 210Po in mushroom

International Nuclear Information System (INIS)

Rosa, Mychelle M.L.; Taddei, Maria Helena T.; Dias, Fabiana F.; Maihara, Vera A.

2009-01-01

For this study, mushroom samples were collected in Brazil at the Sao Paulo Metropolitan Region and at the Pocos de Caldas Plateau (PC; a region of elevated natural radioactivity, which houses the first Brazilian uranium mine). This paper discusses a sequential methodology to determine natural series radionuclides in mushrooms, such as uranium ( 238 U and 234 U) and thorium ( 232 Th, 230 Th, and 228 Th) isotopes, radium-226, radium-228, as well as lead-210 and polonium-210; using Alpha Spectrometry, Gamma Spectrometry, and Total Alpha and Beta Counting. The method involves total sample dissolution in a closed system in order to avoid loss of Polonium and employment of specific chromatographic resins for radionuclide purification. A subsequent interpretation of the results can provide information on pollutants present in mushrooms and infer possible contamination in the areas sampled as well as allow an association of measured concentrations to radioactive anomalies in the Plateau. (author)

The Growth of Monoraphidium sp. and Scenedesmus sp. Cells in the Presence of Thorium

Directory of Open Access Journals (Sweden)

Juliana Cristina de Queiroz

2012-01-01

Full Text Available Toxicity of thorium by Monoraphidium sp. and Scenedesmus sp. was studied. Microalgal cultures were inoculated in ASM-1 medium in presence and absence of thorium. Its effect was monitored by direct counting on Fuchs-Rosenthal chamber and with software. The toxicity of thorium over the species was observed for concentrations over 50.0 mg/L. After 30 days, Monoraphidium cells decreased their concentration from 4.23×106 to 4.27×105 and 8.57×105 cells/mL, in the presence of 50.0 and 100.0 mg/L of thorium, respectively. Scenedesmus sp. cells were more resistant to thorium: for an initial cell concentration of 7.65×104 cells/mL it was observed a change to 5.25×105 and 5.12×105 cells/mL, in the presence of thorium at 50.0 and 100.0 mg/L, respectively. This is an indication that low concentrations of the radionuclide favored the growth, and that Scenedesmus cells are more resistant to thorium than Monoraphidium cells. The software used for comparison with direct count method proved to be useful for the improvement of accuracy of the results obtained, a decrease in the uncertainty and allowed recording of the data. The presence of thorium suggests that low concentrations have a positive effect on the growth, due to the presence of the nitrate, indicating its potential for ecotoxicological studies.

The Growth of Monoraphidium sp. and Scenedesmus sp. Cells in the Presence of Thorium

Science.gov (United States)

de Queiroz, Juliana Cristina; Ferreira, Ana Cristina de Melo; da Costa, Antonio Carlos Augusto

2012-01-01

Toxicity of thorium by Monoraphidium sp. and Scenedesmus sp. was studied. Microalgal cultures were inoculated in ASM-1 medium in presence and absence of thorium. Its effect was monitored by direct counting on Fuchs-Rosenthal chamber and with software. The toxicity of thorium over the species was observed for concentrations over 50.0 mg/L. After 30 days, Monoraphidium cells decreased their concentration from 4.23 × 106 to 4.27 × 105 and 8.57 × 105 cells/mL, in the presence of 50.0 and 100.0 mg/L of thorium, respectively. Scenedesmus sp. cells were more resistant to thorium: for an initial cell concentration of 7.65 × 104 cells/mL it was observed a change to 5.25 × 105 and 5.12 × 105 cells/mL, in the presence of thorium at 50.0 and 100.0 mg/L, respectively. This is an indication that low concentrations of the radionuclide favored the growth, and that Scenedesmus cells are more resistant to thorium than Monoraphidium cells. The software used for comparison with direct count method proved to be useful for the improvement of accuracy of the results obtained, a decrease in the uncertainty and allowed recording of the data. The presence of thorium suggests that low concentrations have a positive effect on the growth, due to the presence of the nitrate, indicating its potential for ecotoxicological studies. PMID:22649297

Recovery of thorium from monazite

International Nuclear Information System (INIS)

Karve, V.M.; Mukherjee, T.K.

1997-01-01

The process practised in the monazite processing plant involves caustic soda digestion of finely ground monazite followed by aqueous processing to recover mixed rare earth chloride solution, thorium and uranium values in the form of hydroxide cake and tri sodium phosphate as a byproduct

Mechanism of thorium biosorption by the cells of the soil fungal isolate Geotrichum sp. dwc-1

Energy Technology Data Exchange (ETDEWEB)

Ding, Congcong; Feng, Su [Sichuan Univ., Chengdu (China). Key Laboratory of Biological Resource and Ecological Environment; Li, Xiaolong [Sichuan Univ., Chengdu (China). Key Laboratory of Radiation Physics and Technology; and others

2014-04-01

In order to understand the impact of microorganisms on the fate of thorium in soils, we investigated the thorium biosorption behavior and the corresponding mechanisms by the cells of Geotrichum sp. dwc-1, one of the dominant species of fungal group isolated from 3.5 m depth soil layer in Southwest China. It was observed that fast thorium adsorption onto cells of G. sp. dwc-1 could take place, with a high distribution coefficient K{sub d} (0.93 mL/mg) obtained, when Geotrichum sp. dwc-1and thorium concentrations were 5 g/L and 10 mg/L, respectively. The thorium biosorption behavior was dependent on the pH value, and the lower pH could disrupt cell membrane of G. sp. dwc-1. At pH 1, thorium was accumulated in the cytoplasmic region of the cells. When pH was higher than 1, thorium was adsorbed on the cell surface of G. sp. dwc-1, like in periplasmic region or in the outer membrane. FTIR study combined with biosorption experiments further indicated that the thorium distribution and binding behavior on cell surface were associated with amino, hydroxyl groups and phosphate or sulphur functional groups, and might also be governed by electrostatic interaction. Moreover, PIXE and EPBS showed that ion-exchange mechanism contributed to the thorium biosorption process, in which the tetravalent thorium ions replaced smaller counter-ions (K{sup +}, Ca{sup 2+} and Fe{sup 3+}) occuring on the cell surface. (orig.)

Production yields of noble-gas isotopes from ISOLDE UC$_{x}$/graphite targets

CERN Document Server

Bergmann, U C; Catherall, R; Cederkäll, J; Diget, C A; Fraile-Prieto, L M; Franchoo, S; Fynbo, H O U; Gausemel, H; Georg, U; Giles, T; Hagebø, E; Jeppesen, H B; Jonsson, O C; Köster, U; Lettry, Jacques; Nilsson, T; Peräjärvi, K; Ravn, H L; Riisager, K; Weissman, L; Äystö, J

2003-01-01

Yields of He, Ne, Ar, Kr and Xe isotopic chains were measured from UC$_{x}$/graphite and ThC$_{x}$/graphite targets at the PSB-ISOLDE facility at CERN using isobaric selectivity achieved by the combination of a plasma-discharge ion source with a water-cooled transfer line. %The measured half-lives allowed %to calculate the decay losses of neutron-rich isotopes in the %target and ion-source system, and thus to obtain information on the in-target %productions from the measured yields. The delay times measured for a UC$_x$/graphite target allow for an extrapolation to the expected yields of very neutron-rich noble gas isotopes, in particular for the ``NuPECC reference elements'' Ar and Kr, at the next-generation radioactive ion-beam facility EURISOL. \\end{abstract} \\begin{keyword} % keywords here, in the form: keyword \\sep keyword radioactive ion beams \\sep release \\sep ion yields \\sep ISOL (Isotope Separation On-Line) \\sep uranium and thorium carbide targets. % PACS codes here, in the form: \\PACS code \\sep code...

Decontamination of liquid radioactive waste by thorium phosphate

International Nuclear Information System (INIS)

Rousselle, J.; Grandjean, S.; Dacheux, N.; Genet, M.

2004-01-01

In the field of the complete reexamination of the chemistry of thorium phosphate and of the improvement of the homogeneity of Thorium Phosphate Diphosphate (TPD, Th 4 (PO 4 ) 4 P 2 O 7 ) prepared at high temperature, several crystallized compounds were prepared as initial powdered precursors. Due to the very low solubility products associated to these phases, their use in the field of the efficient decontamination of high-level radioactive liquid waste containing actinides (An) was carefully considered. Two main processes (called 'oxalate' and 'hydrothermal' chemical routes) were developed through a new concept combining the decontamination of liquid waste and the immobilization of the actinides in a ceramic matrix (TPD). In phosphoric media ('hydrothermal route'), the key-precursor was the Thorium Phosphate Hydrogen Phosphate hydrate (Th 2 (PO 4 ) 2 (HPO 4 ). H 2 O, TPHP, solubility product log(K S,0 0 ) ∼ - 67). The replacement of thorium by other tetravalent actinides (U, Np, Pu) in the structure, leading to the preparation of Th 2-x/2 An x/2 (PO 4 ) 2 (HPO 4 ). H 2 O solid solutions, was examined. A second method was also considered in parallel to illustrate this concept using the more well-known precipitation of oxalate as the initial decontamination step. For this method, the final transformation to single phase TPD containing actinides was purchased by heating a mixture of phosphate ions with the oxalate precipitate at high temperature. (authors)

Investigation of the use of thorium in LWRs for improving reactor core performance

International Nuclear Information System (INIS)

Lau, Cheuk Wah

2012-01-01

Thorium is a fertile material and most of the past research has focused on breeding thorium into fissile material to achieve a more sustainable use of nuclear power. However, the focus in this report is on using thorium to improve reactor core performance. The improvement of reactor core performance is achieved by increasing the thermal margins by homogeneously distributing thorium in the fuel pellets. A proposed uranium-thorium-based fuel assembly is simulated for the Swedish Ringhals-3 PWR core in a realistic demonstration. In order to fully grasp the benefits and drawbacks of the newly proposed uranium-thorium-based fuel, a reload safety evaluation has been performed. For a real core, the Swedish Radiation Safety Authority would require an identical evaluation method to ensure that safety criteria are met during the whole cycle. In this report, only a few key safety parameters, such as isothermal- and Doppler-temperature coefficients of reactivity, pin peak power, boron worth, shutdown margins, and core average beta-effective are presented. The calculations were performed by the two-dimensional transport code CASMO-4E, and the two group three dimensional nodal code SIMULATE-3K from Studsvik Scandpower. The results showed that the uranium-thorium-based fuel assembly improves the thermal margins, both in the pin peak power and the local power (Fq). The improved thermal margins would allow more flexible core loading patterns with less neutron leakage, and could be used in power uprated cores to offer better safety margins

Investigation of the use of thorium in LWRs for improving reactor core performance

Energy Technology Data Exchange (ETDEWEB)

Lau, Cheuk Wah

2012-07-01

Thorium is a fertile material and most of the past research has focused on breeding thorium into fissile material to achieve a more sustainable use of nuclear power. However, the focus in this report is on using thorium to improve reactor core performance. The improvement of reactor core performance is achieved by increasing the thermal margins by homogeneously distributing thorium in the fuel pellets. A proposed uranium-thorium-based fuel assembly is simulated for the Swedish Ringhals-3 PWR core in a realistic demonstration. In order to fully grasp the benefits and drawbacks of the newly proposed uranium-thorium-based fuel, a reload safety evaluation has been performed. For a real core, the Swedish Radiation Safety Authority would require an identical evaluation method to ensure that safety criteria are met during the whole cycle. In this report, only a few key safety parameters, such as isothermal- and Doppler-temperature coefficients of reactivity, pin peak power, boron worth, shutdown margins, and core average beta-effective are presented. The calculations were performed by the two-dimensional transport code CASMO-4E, and the two group three dimensional nodal code SIMULATE-3K from Studsvik Scandpower. The results showed that the uranium-thorium-based fuel assembly improves the thermal margins, both in the pin peak power and the local power (Fq). The improved thermal margins would allow more flexible core loading patterns with less neutron leakage, and could be used in power uprated cores to offer better safety margins.

Comparative uptake of thorium-230, radium-226, lead-210 and polonium-210 by plants

Energy Technology Data Exchange (ETDEWEB)

D' Souza, T J; Mistry, K B

1970-01-01

The entry and translocation of /sup 230/thorium, /sup 226/radium, /sup 210/lead, and /sup 210/polonium were examined in nutrient culture experiments. Strontium-89 was included for comparison. Red kidney beans (Phaseolus vulgaris L.) were treated for a period of 15 days. Results indicate that accumulation of /sup 230/thorium, /sup 210/lead and /sup 210/polonium occurs predominantly in roots and only very small amounts of these nuclides are translocated to shoots. Over comparable periods, the accumulation of /sup 226/radium in roots is 2-3 times lower than that of the other nuclides of uranium series. However, the most significant difference between /sup 226/radium and other nuclides is in the extent of their upward transport which for radium is 50-200 times greater. The amount of radium translocated to shoots is comparable to that of strontium. The present evidence of rapid transfer of /sup 226/radium to shoots suggests that among the nuclides examined, /sup 226/radium is likely to make the major contribution to radioactivity in aerial tissues of plants grown under conditions where root absorption is the principal route of entry of the nuclides.

Assessment of the thorium fuel cycle in power reactors

International Nuclear Information System (INIS)

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

1977-01-01

A study was conducted at Oak Ridge National Laboratory to evaluate the role of thorium fuel cycles in power reactors. Three thermal reactor systems were considered: Light Water Reactors (LWRs); High-Temperature Gas-Cooled Reactors (HTGRs); and Heavy Water Reactors (HWRs) of the Canadian Deuterium Uranium Reactor (CANDU) type; most of the effort was on these systems. A summary comparing thorium and uranium fuel cycles in Fast Breeder Reactors (FBRs) was also compiled

Use of nuclear recoil for separating 228Ra, 224Ra, and 233Pa from colloidal thorium

International Nuclear Information System (INIS)

Beydon, J.; Gratot, I.

1968-01-01

By using α-recoil it is possible to separate by dialysis the α disintegration products (224 Ra; 228 Ra) of thorium from colloidal thorium hydroxide.The use of n, γ recoil allows the separation of 233 Pa produced by the neutron irradiation of thorium, on condition that the colloidal thorium hydroxide is irradiated in the presence of a dispersing. (author) [fr

Physicochemical studies as thorium soaps in solid state

International Nuclear Information System (INIS)

Mehrotra, K.N.; Gahlaut, A.S.; Sharma, M.

1987-01-01

The thermal decomposition of thorium soaps is kinetically of zero order and the energy of activation for the decomposition process lies in the range of 6-11 kcal mol -1 . Infrared spectral data indicate that the fatty acids exist with dimeric structure through hydrogen bonding between the carboxyl groups of acid molecules whereas the metal soaps have an ionic character. The X-ray diffraction studies of these soaps revealed that thorium soaps have double layer structure with molecular axes slightly inclined to the basal plane. (author). 10 refs., 5 figures

Thorium Fuel Performance in a Tight-Pitch Light Water Reactor Lattice

International Nuclear Information System (INIS)

Kim, Taek Kyum; Downar, Thomas J.

2002-01-01

Research on the utilization of thorium-based fuels in the intermediate neutron spectrum of a tight-pitch light water reactor (LWR) lattice is reported. The analysis was performed using the Studsvik/Scandpower lattice physics code HELIOS. The results show that thorium-based fuels in the intermediate spectrum of tight-pitch LWRs have considerable advantages in terms of conversion ratio, reactivity control, nonproliferation characteristics, and a reduced production of long-lived radiotoxic wastes. Because of the high conversion ratio of thorium-based fuels in intermediate spectrum reactors, the total fissile inventory required to achieve a given fuel burnup is only 11 to 17% higher than that of 238 U fertile fuels. However, unlike 238 U fertile fuels, the void reactivity coefficient with thorium-based fuels is negative in an intermediate spectrum reactor. This provides motivation for replacing 238 U with 232 Th in advanced high-conversion intermediate spectrum LWRs, such as the reduced-moderator reactor or the supercritical reactor

Isotopes a very short introduction

CERN Document Server

Ellam, Rob

2016-01-01

An isotope is a variant form of a chemical element, containing a different number of neutrons in its nucleus. Most elements exist as several isotopes. Many are stable while others are radioactive, and some may only exist fleetingly before decaying into other elements. In this Very Short Introduction, Rob Ellam explains how isotopes have proved enormously important across all the sciences and in archaeology. Radioactive isotopes may be familiar from their use in nuclear weapons, nuclear power, and in medicine, as well as in carbon dating. They have been central to establishing the age of the Earth and the origins of the solar system. Combining previous and new research, Ellam provides an overview of the nature of stable and radioactive isotopes, and considers their wide range of modern applications. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subjec...

Development of an automated method for determination of thorium in soil samples and aerosols

International Nuclear Information System (INIS)

Stuart, J.E.; Robertson, R.

1986-09-01

Methodology for determining trace thorium levels in a variety of sample types was further developed. Thorium in filtered water samples is concentrated by ferric hydroxide precipitation followed by dissolution and co-precipitation with lanthanum fluoride. Aerosols on glass fibre, cellulose ester, or teflon filters and solid soil and sediment samples are acid digested. Subsequently thorium is concentrated by lanthanum fluoride co-precipitation. Chemical separation and measurement is then done on a Technicon AA11-C autoanalyzer, using solvent extraction into thenoyltrifuoroacetone in kerosene followed by back extraction into 2 N H NO 3 , and colourometric measurement of the thorium arsenazo III complex. Chemical yields are determined by the addition of thorium-234 tracer using gamma-ray spectrometry. The sensitivities of the methods for water, aerosol and solid samples are approximately 1.0 μg/L, 0.5 μg/g and 1.0 μg/g respectively. At thorium levels about ten times the detection limit, accuracy is estimated to be ± 10% for liquids and aerosols and ± 15% for solid samples, and precision ± 5% for all samples

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)

Geochemistry and petrology of surface samples, six boreholes and brines from the Salton Sea geothermal field: A natural analog of a nuclear waste repository in salt: Report No. 3

International Nuclear Information System (INIS)

1987-05-01

Cuttings from six wells in the Salton Sea geothermal field, and rocks at outcrop that are correlative in age with those encountered at depth in the wells were analyzed in detail. Mineralogy, petrography, x-ray diffraction, electron microprobe, instrumental neutron activation analysis, fission track radiography, oxygen and stable carbon isotopic, uranium-thorium series disequilibrium, and fluid inclusion analyses are reported. Where fluids were being produced from wells, brine chemistry as well as stable isotope and uranium-thorium series analyses are reported. Particular attention has been paid to defining zones of fluid-rock interaction in which analyses of coexisting geothermal reservoir brine and hydrothermally altered sediments could be acquired. A wide span of temperatures, from surficial to greater than 300/degree/C, and salinities ranging from relatively dilute ground waters up to brines of 25 wt% total dissolved solids, span a range of environments that might be encountered in a waste repository in salt. Progressive hydrothermal alteration, mineral formation and element mobility are documented in the data presented. 52 refs., 25 figs., 49 tabs

Release of radium and other decay-series isotopes from Florida phosphate rock. Final report

International Nuclear Information System (INIS)

Burnett, W.C.; Chin, P.; Deetae, S.; Panik, P.

1988-01-01

The purpose of this research was to determine the conditions under which uranium decay-series isotopes are released from phosphate rock into the environment. Particular attention was given to the behavior of radium, radon, and polonium. The emphasis was justified because of several documented cases citing elevated concentrations of these radioelements occurring in Florida ground waters. When it became clear that polonium was occasionally present at exceedingly high concentrations in shallow ground waters, the scope of the project was expanded to include a study of the distribution of Po-210 in the surficial aquifer of west central Florida. Studies of a series of phosphate rock samples representing various degrees of chemical weathering show that almost all uranium-series radionuclides display higher activities in weathered samples compared to fresh material. Most samples display a Pb-210/Ra-226 activity ratio less than secular equilibrium because of Rn-222 leakage. An unexpected result was the deficiency of Po-210, relative to Pb-210 in several samples. This implies that polonium, under certain conditions, may be more mobile than lead. Many wells in central Florida contain high concentrations of Po-210. Characteristics which high-polonium groundwaters have in common include low pH, presence of sulfide, and at least moderately high radon

Temporal and spatial distribution of isotopes in river water in Central Europe: 50 years experience with the Austrian network of isotopes in rivers.

Science.gov (United States)

Rank, Dieter; Wyhlidal, Stefan; Schott, Katharina; Weigand, Silvia; Oblin, Armin

2018-05-01

The Austrian network of isotopes in rivers comprises about 15 sampling locations and has been operated since 1976. The Danube isotope time series goes back to 1963. The isotopic composition of river water in Central Europe is mainly governed by the isotopic composition of precipitation in the catchment area; evaporation effects play only a minor role. Short-term and long-term isotope signals in precipitation are thus transmitted through the whole catchment. The influence of climatic changes has become observable in the long-term stable isotope time series of precipitation and surface waters. Environmental 3 H values were around 8 TU in 2015, short-term 3 H pulses up to about 80 TU in the rivers Danube and March were a consequence of releases from nuclear power plants. The complete isotope data series of this network will be included in the Global Network of Isotopes in Rivers database of the International Atomic Energy Agency (IAEA) in 2017. This article comprises a review of 50 years isotope monitoring on rivers and is also intended to provide base information on the (isotope-)hydrological conditions in Central Europe specifically for the end-users of these data, e.g. for modelling hydrological processes. Furthermore, this paper includes the 2006-2015 supplement adding to the Danube isotope set published earlier.