Development of Indian cross section data files for Th-232 and U-233 and integral validation studies

International Nuclear Information System (INIS)

Ganesan, S.

1988-01-01

This paper presents an overview of the tasks performed towards the development of Indian cross section data files for Th-232 and U-233. Discrepancies in various neutron induced reaction cross sections in various available evaluated data files have been obtained by processing the basic data into multigroup form and intercomparison of the latter. Interesting results of integral validation studies for capture, fission and (n,2n) cross sections for Th-232 by analyses of selected integral measurements are presented. In the resonance range, energy regions where significant differences in the calculated self-shielding factors for Th-232 occur have been identified by a comparison of self-shielded multigroup cross sections derived from two recent evaluated data files, viz., ENDF/B-V (Rev.2) and JENDL-2, for several dilutions and temperatures. For U-233, the three different basic data files ENDF/B-IV, JENDL-2 and ENDL-84 were intercompared. Interesting observations on the predictional capability of these files for the criticality of the spherical metal U-233 system are given. The current status of Indian data file is presented. (author) 62 ref

Measurement of Fragment Mass Distributions in Neutron-induced Fission of {sup 238}U and {sup 232}Th at Intermediate Energies

Energy Technology Data Exchange (ETDEWEB)

Simutkin, V.D. [Uppsala University, P.O Box 525, SE-751 20 Uppsala (Sweden)

2008-07-01

Conceptual analysis of accelerator-driven systems assumes extensive use of nuclear data on neutron-induced reactions at intermediate energies. In particular, information about the fission fragment yields from the {sup 238}U(n,f) and {sup 232}Th(n,f) reactions is of particular interest at neutron energies from 10 to 200 MeV. However, there is a lack of such data for both {sup 238}U and {sup 232}Th. Up to now, the intermediate energy measurements have been performed for {sup 238}U only, and there are no data for the {sup 232}Th(n,f) reaction. The aim of the work is to provide such data. Fission fragment mass distributions for the {sup 232}Th(n,f) and {sup 238}U(n,f) reactions have been measured for the incident neutron energies 32.8 MeV, 45.3 MeV and 59.9 MeV. The experiments have been performed at the neutron beam facility of the Universite Catholique de Louvain, Belgium. A multi-section Frisch-gridded ionization chamber has been used as a fission fragment detector. The data obtained have been interpreted in terms of the multimodal random neck-rupture model (MMRNRM). (authors)

230Th-238U disequilibria in historical lavas from Iceland

International Nuclear Information System (INIS)

Condomines, M.; Morand, P.; Alleegre, C.J.; Sigvaldason, G.

1981-01-01

The 230 Th- 238 U disequilibrium studies on historical lavas from Iceland show a relative homogeneity for Th/U ratios and also a variation for ( 230 Th/ 232 Th) activity ratios at the scale of the island. The ( 230 Th/ 238 U) disequilibrium ratio is always greater than 1 which indicates that partial melting produces magmas with Th/U ratios greater than those of the mantle source. Furthermore, there seems to be a correlation between the variations of ( 230 Th/ 232 Th) (and delta 18 O) ratios and the geographical location of the samples along the active zones of Iceland. We develop and discuss several models in order to explain these variations. (orig.)

238U-230Th radioactive disequilibria in the volcanic products from Izu arc volcanoes, Japan

International Nuclear Information System (INIS)

Kurihara, Yuichi; Takahashi, Masaomi; Sato, Jun

2007-01-01

The timescale of magmatic processes of Izu arc volcanoes, Japan, was estimated by the 238 U- 230 Th disequilibria in the volcanic products from the volcanoes. The majority of the 230 Th/ 238 U activity ratios of the products were less than unity, being enriched in 238 U relative to 230 Th. The ( 230 Th/ 232 Th)-( 238 U/ 232 Th)diagram for younger Fuji and Izu-Oshima volcanoes formed a whole rock isochrons, and the ages were 1x10 4 and 2x10 4 years, respectively. The ( 230 Th/ 232 Th) - ( 238 U/ 232 Th) data set for younger Fuji volcano formed a cluster on the diagram, while those of Izu-Oshima formed another cluster apparently apart from each other, suggesting that the concentration of U and Th may possibly be un-uniform in the mantle beneath Izu arc. (author)

Optimization of the binary breeder reactor. VIII annular core fueled with 233U - 238U and Pu-238U

International Nuclear Information System (INIS)

Nascimento, J.A. do; Ishiguro, Y.

1988-04-01

First cycle burnup characteristics of a 1200 MWe binary breeder reactor with annular core fueled with metallic 233 U- 238 U-Zr, Pu- 238 U-Zr and Th in the blankets have been analysed. The Doppler effect is small as expected in a metal fueled fast reactor. The sodium void reactivity is, in general, smaller than in metal fueled homogeneous fast reactors of 1 m core height. The estimates of the required and available control rod worths show a large shutdown margin throughout the operational cycle. There are flexibilities in the blanket fueling and well balanced breeding in the two cycles, uranium and thorium, with doubling times of about 20 years are possible. (author) [pt

Cost-based optimizations of power density and target-blanket modularity for 232Th/233U-based ADEP

International Nuclear Information System (INIS)

Krakowski, R.A.

1995-01-01

A cost-based parametric systems model is developed for an Accelerator-Driven Energy Production (ADEP) system based on a 232 Th/ 233 U fuel cycle and a molten-salt (LiF/BeF 2 /ThF 3 ) fluid-fuel primary system. Simplified neutron-balance, accelerator, reactor-core, chemical-processing, and balance-of-plant models are combined parametrically with a simplified costing model. The main focus of this model is to examine trade offs related to fission power density, reactor-core modularity, 233 U breeding rate, and fission product transmutation capacity

Collective and single-particle excitations in the heavy deformable nuclei 234U, 233U, 231Th, 230Pa and 232Pa

International Nuclear Information System (INIS)

Kotthaus, Tanja

2010-01-01

In this thesis five heavy deformed isotopes from the mass region A≥230, namely 234 U, 233 U, 231 Th, 230 Pa and 232 Pa, were investigated by means of deuteron-induced neutron transfer reactions. The even-even isotope 234 U has been studied with the 4π-γ-spectrometer MINIBALL at the Cologne Tandem accelerator. Excited nuclei in the isotope 234 U were produced using the reaction 235 U(d,t) at a beam energy of 11 MeV. The target thickness was 3.5 mg/cm 2 . The analysis of the γγ-coincidence data yielded a reinterpretation of the level scheme in 12 cases. Considering its decay characteristics, the 4 + state at an excitation energy of 1886.7 keV is a potential candidate for a two-phonon vibrational state. The isotopes 233 U, 231 Th, 230 Pa and 232 Pa were investigated at the Munich Q3D spectrometer. For each isotope an angular distribution with angles between 5 and 45 were measured. In all four cases the energy of the polarized deuteron beam (vector polarization of 80%) was 22 MeV. As targets 234 U (160 μg/cm 2 ), 230 Th (140 μg/cm 2 ) and 231 Pa (140 μg/cm 2 ) were used. The experimental angular distributions were compared to results of DWBA calculations. For the odd isotope 233 U spin and parity for 33 states are assigned and in the other odd isotope 231 Th 22 assignments are made. The excitation spectra of the two odd-odd isotopes 230 Pa and 232 Pa were investigated for the first time. For the isotope 230 Pa 63 states below an excitation energy of 1.5 MeV are identified. Based on the new experimental data the Nilsson configuration of the ground state is either 1/2[530] p -5/2[633] n or 1/2[530] p +3/2[631] n . In addition 12 rotational bands are proposed and from this six values for the GM splitting energy are deduced as well as two new values for the Newby shift. In the other odd-odd isotope 232 Pa 40 states below an excitation energy of 850 keV are observed and suggestions for the groundstate band and its GM partner are made. From this one GM splitting

Neutron induced fission cross sections for 232Th, 235,238U, 237Np, and 239Pu

International Nuclear Information System (INIS)

Lisowski, P.W.; Ullmann, J.L.; Balestrini, S.J.; Hill, N.W.; Carlson, A.D.; Wasson, O.A.

1989-01-01

Neutron-induced fission cross section ratios for samples of 232 Th, 235,238 U, 237 Np and 239 Pu have been measured from 1 to 400 MeV. The fission reaction rate was determined for all samples simultaneously using a fast parallel plate ionization chamber at a 20-m flight path. A well characterized annular proton recoil telescope was used to measure the neutron fluence from 3 to 30 MeV. Those data provided the shape of the 235 U(n,f) cross section relative to the hydrogen scattering cross section. That shape was then normalized to the very accurately known value for 235 U(n,f) at 14.178 MeV. From 30 to 400 MeV cross section values were determined using the neutron fluence measured with a plastic scintillator. Cross section values of 232 Th, 235,238 U, 237 Np and 239 Pu were computed from the ratio data using the authors' values for 235 U(n,f). In addition to providing new results at high neutron energies, these data highlight several areas of deficiency in the evaluated nuclear data files and provide new information for the 235 U(n,f) standard

{sup 238}U and {sup 232}Th concentrations in various foodstuffs in Morocco and resulting radiation doses to the members of the public; Concentrations en {sup 238}U et {sup 232}Th dans differents aliments au Maroc et doses de radiations en resultant pour les membres du public

Energy Technology Data Exchange (ETDEWEB)

Misdaq, M.A.; Elamyn, H.; Erramli, H. [Cadi Ayyad Univ., Nuclear Physics and Techniques Lab., Faculty of Sciences Semlalia, Marrakech (Morocco)

2008-04-15

Uranium ({sup 238}U) and thorium ({sup 232}Th) concentrations were measured in different foods widely consumed in Morocco by using C.R.-39 and L.R.-115 type II solid state nuclear track detectors (S.S.N.T.D.). Data obtained were compared to those obtained by using isotope dilution mass spectrometry (I.D.M.S.). Total daily intakes of {sup 238}U and {sup 232}Th for a typical food basket were estimated to be 1.3 {+-} 0.1 mBq d{sup -1} and 0.98 {+-} 0.08 mBq d{sup -1}, 1.4 {+-} 0.1 mBq d{sup -1} and 1.06 {+-} 0.08 mBq d{sup -1}, 1.7 {+-} 0.1 mBq d{sup -1} and 1.26 {+-} 0.08 mBq d{sup -1} and 2.0 {+-} 0.1 mBq d{sup -1} and 1.5 {+-} 0.1 Bq d{sup -1} for the 2-7 years, 7-12 years, 12-17 years and adult's age groups, respectively. Alpha-activities due to annual {sup 238}U and {sup 232}Th intakes from the ingestion of the studied foodstuffs were determined in different organs and tissues of the human body of members of the public by using the ICRP gastrointestinal tract and systemic part models for these radionuclides. Committed equivalent doses due to annual intakes of {sup 238}U and {sup 232}Th were evaluated in the human body organs and tissues for different age groups of the Moroccan population by exploiting data obtained for alpha-doses deposited by 1 Bq of {sup 238}U and 1 Bq of {sup 232}Th in the considered human organs and tissues. The influence of the mass of the target tissue and activities due to {sup 238}U and {sup 232}Th on the committed equivalent doses due to annual intakes of these radionuclides in the organs and tissues of the human body was studied. (authors)

Environmental 238U and 232Th concentration measurements in an area of high level natural background radiation at Palong, Johor, Malaysia.

Science.gov (United States)

Ramli, A Termizi; Hussein, A Wahab M A; Wood, A Khalik

2005-01-01

Concentrations of uranium-238 and thorium-232 in soil, water, grass, moss and oil-palm fruit samples collected from an area of high background radiation were determined using neutron activation analysis (NAA). U-238 concentration in soil ranged from 4.9 mg kg(-1) (58.8 Bq kg(-1)) to 40.4 mg kg(-1) (484.8 Bq kg(-1)), Th-232 concentration ranged from 14.9 mg kg(-1) (59.6 Bq kg(-1)) to 301.0 mg kg(-1) (1204 Bq kg(-1)). The concentration of U-238 in grass samples ranged from below the detection limit to 0.076 mg kg(-1) (912 mBq kg(-1)), and Th-232 ranged from 0.008 mg kg(-1) (32 mBq kg(-1)) to 0.343 mg kg(-1) (1.372 Bq kg(-1)). U-238 content in water samples ranged from 0.33 mg kg(-1) (4.0 Bq L(-1)) to 1.40 mg kg(-1) (16.8 Bq L(-1)), and Th-232 ranged from 0.19 mg kg(-1) (0.76 Bq L(-1)) to 0.66 mg kg(-1) (2.64 Bq L(-1)). It can be said that the concentrations of environmental U-238 and Th-232 in grass and water samples in the study area are insignificant. Mosses were found to be possible bio-radiological indicators due to their high absorption of the heavy radioelements from the environment.

A dispersive optical model potential for nucleon induced reactions on 238U and 232Th nuclei with full coupling

Directory of Open Access Journals (Sweden)

Chiba Satoshi

2013-03-01

Full Text Available A dispersive coupled-channel optical model potential (DCCOMP that couples the ground-state rotational and low-lying vibrational bands of 238U and 232Th nuclei is studied. The derived DCCOMP couples almost all excited levels below 1 MeV of excitation energy of the corresponding even-even actinides. The ground state, octupole, beta, gamma, and non-axial bands are coupled. The first two isobar analogue states (IAS populated in the quasi-elastic (p,n reaction are also coupled in the proton induced calculation, making the potential approximately Lane consistent. The coupled-channel potential is based on a soft-rotor description of the target nucleus structure, where dynamic vibrations are considered as perturbations of the rigid rotor underlying structure. Matrix elements required to use the proposed structure model in Tamura coupled-channel scheme are derived. Calculated ratio R(U238/Th232 of the total cross-section difference to the averaged σT for 238U and 232Th nuclei is shown to be in excellent agreement with measured data.

Dissolution behaviour of 238U, 234U and 230Th deposited on filters from personal dosemeters

International Nuclear Information System (INIS)

Beckova, V.; Malatova, I.

2008-01-01

Kinetics of dissolution of 238 U, 234 U and 230 Th dust deposited on filters from personal alpha dosemeters was studied by means of a 26-d in vitro dissolution test with a serum ultra-filtrate simulant. Dosemeters had been used by miners at the uranium mine 'Dolni Rozinka' at Rozna, Czech Republic. The sampling flow-rate as declared by the producer is 4 l h -1 and the sampling period is typically 1 month. Studied filters contained 125 ± 6 mBq 238 U in equilibrium with 234 U and 230 Th; no 232 Th series nuclides were found. Half-time of rapid dissolution of 1.4 d for 238 U and 234 U and slow dissolution half-times of 173 and 116 d were found for 238 U and 234 U, respectively. No detectable dissolution of 230 Th was found. (authors)

Dissolution behaviour of 238U, 234U and 230Th deposited on filters from personal dosemeters.

Science.gov (United States)

Becková, Vera; Malátová, Irena

2008-01-01

Kinetics of dissolution of (238)U, (234)U and (230)Th dust deposited on filters from personal alpha dosemeters was studied by means of a 26-d in vitro dissolution test with a serum ultrafiltrate simulant. Dosemeters had been used by miners at the uranium mine 'Dolní Rozínka' at Rozná, Czech Republic. The sampling flow-rate as declared by the producer is 4 l h(-1) and the sampling period is typically 1 month. Studied filters contained 125 +/- 6 mBq (238)U in equilibrium with (234)U and (230)Th; no (232)Th series nuclides were found. Half-time of rapid dissolution of 1.4 d for (238)U and (234)U and slow dissolution half-times of 173 and 116 d were found for (238)U and (234)U, respectively. No detectable dissolution of (230)Th was found.

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)

Standard practice for the determination of 237Np, 232Th, 235U and 238U in urine by inductively coupled plasma-Mass spectrometry (ICP-MS) and gamma ray spectrometry.

CERN Document Server

American Society for Testing and Materials. Philadelphia

2005-01-01

1.1 This practice covers the separation and preconcentration of neptunium-237 (237Np), thorium-232 (232Th), uranium-235 (235U) and uranium-238 (238U) from urine followed by quantitation using ICP-MS. 1.2 This practice can be used to support routine bioassay programs. The minimum detectable concentrations (MDC) for this method, taking the preconcentration factor into account, are approximately 1E-2Bq for 237Np (0.38ng), 2E-6Bq for 232Th (0.50ng), 4E-5Bq for 235U (0.50ng) and 6E-6Bq for 238U (0.48ng). 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Measurement of the fission cross section induced by fast neutrons of the {sup 232}Th/{sup 233}U nuclei within the innovating fuel cycles framework; Mesure de la section efficace de fission induite par neutrons rapides des noyaux {sup 232}Th/{sup 233}U dans le cadre des cycles de combustible innovants

Energy Technology Data Exchange (ETDEWEB)

Grosjean, C

2005-03-15

The thorium-U{sup 233} fuel cycle might provided safer and cleaner nuclear energy than the present Uranium/Pu fuelled reactors. Over the last 10 years, a vast campaign of measurements has been initiated to bring the precision of neutron data for the key nuclei (Th{sup 232}, Pa{sup 233} and U{sup 233}) at the level of those for the U-Pu cycle. This is the framework of these measurements, the energy dependent neutron induced fission cross section of Th{sup 232} and U{sup 233} has been measured from 1 to 7 MeV with a target accuracy lesser than 5 per cent. These measurements imply the accurate determination of the fission rate, the number of the target nuclei as well as the incident neutron flux impinging on the target, the latter has been obtained using the elastic scattering (n,p). The cross section of which is very well known in a large neutron energy domain ({approx} 0,5 % from 1 eV to 50 MeV) compared to the U{sup 235}(n,f) reaction. This technique has been applied for the first time to the Th{sup 232}(n,f) and U{sup 233}(n,f) cases. A Hauser-Feshbach statistical model has been developed. It consists of describing the different decay channels of the compound nucleus U{sup 234} from 0,01 to 10 MeV neutron energy. The parameters of this model were adjusted in order to reproduce the measured fission cross section of U{sup 233}. From these parameters, the cross sections from the following reactions could be extracted: inelastic scattering U{sup 233}(n,n'), radiative capture U{sup 233}(n,{gamma}) and U{sup 233}(n,2n). These cross sections are still difficult to measure by direct neutron reactions. The calculated values have allowed us to fill the lack of experimental data for the major fissile nucleus of the thorium cycle. (author)

Estimation of radionuclide concentration of 238U, 226Ra, 232Th in air in Wuhan city

International Nuclear Information System (INIS)

Shi Jinhua; Chen Changhua

1989-01-01

The concentrations of 238 U, 226 Ra and 232 Th in air in Wuhan area were estimated by assuming that they originate from resuspended particles of soil and investigating the dust content in air and the concentrations of these radionuclides in soil. 60 soil samples were collected from April to October, 1984, and 7346 air dust samples during 1981-1985. The estimated mean air concentrations of 238 U, 226 Ra and 232 Th were 24.0 x 10 -9 , 18.9 x 10 -9 and 28.7 x 10 -9 , Bq/L, respectively. Their highest values were observed of 30.4 x 10 -9 , 23.9 x 10 -9 and 36.2 x 10 -9 Bq/L in 1983. Seasonal change of the concentrations was clear as shown in the data of 1984 and 1985, which was related to the meterological conditions. Among the 6 districts of Wuhan city, the highest concentration was in Qingshan and the lowest in Wuchang

Development of sequential analytical method for the determination of U-238, U-234, Th-232, Th-230, Th-228, Ra-226 and Ra-228 and its application in mineral waters

International Nuclear Information System (INIS)

Costa Lauria, D. da.

1986-01-01

A sequential analytical method for the determination of U-238, U-234, Th-232, Th-230, Th-228, Ra-226 and Ra-228 in environmental samples and applied to the analysis of mineral waters is studied. Thorium isotopes are coprecipitated with lanthanium fluoride before counting in alpha spectrometer, the uranium isotopes are determined by alpha spectrometry following extraction with TOPO onto a polymenic membrane. Radium-226 is determined with the radom emanation technique. (M.J.C.) [pt

Measurement of fast neutron induced fission cross sections of 232Th, 238U, 237Np and 243Am

International Nuclear Information System (INIS)

Kanda, Kazutaka; Sato, Osamu; Yoshida, Kazuo; Imaruoka, Hiromitsu; Terayama, Hiromichi; Yoshida, Masashi; Hirakawa, Naohiro

1984-01-01

Neutron induced fission cross sections of 232 Th, 238 U, 237 Np and 243 Am relative to 235 U were measured in the energy range from 1.5 to 6.6 MeV. The present results are compared with experimental results of others and evaluated data in JENDL-2 and ENDF/B-IV. (author)

238U-234U-230Th-232Th systematics and the precise measurement of time over the past 500,000 years

International Nuclear Information System (INIS)

Edwards, R.L.; Chen, J.H.; Wasserburg, G.J.

1987-01-01

We have developed techniques to measure the 230 Th abundance in corals by isotope dilution mass spectrometry. This, coupled with our previous development of mass spectrometric techniques for 234 U and 232 Th measurement, has allowed us to reduce significantly the analytical errors in 238 U- 234 U- 230 Th dating and greatly reduce the sample size. We show that 6x10 8 atoms of 230 Th can be measured to ±30per mille (2 σ) and 2x10 10 atoms of 230 Th to ±2per mille. The time over which useful age data on corals can be obtained ranges from a few years to ≅ 500 ky. The uncertainty in age, based on analytical errors, is ±5 y(2 σ) for a 180 year old coral (3 g), ±44 y at 8294 years and ±1.1 ky at 123.1 ky (250 mg of coral). We also report 232 Th concentrations in corals (0.083-1.57 pmol/g) that are more than two orders of magnitude lower than previous values. Ages with high analytical precision were determined for several corals that grew during high sea level stands ≅ 120 ky ago. These ages lie specifically within or slightly postdate the Milankovitch insolation high at 128 ky and support the idea that the dominant cause of Pleistocene climate change is Milankovitch forcing. (orig.)

High-resolution photofission measurements in 238U and 232Th. Progress report, June 1, 1980-February 10, 1981

International Nuclear Information System (INIS)

Lancman, H.

1981-02-01

Intense proton beam currents from the Dynamitron at Brooklyn College have been used to generate gamma rays of variable energy from a number of (p,γ) resonances in various nuclei. Spectra of photofission fragments of 238 U and 232 Th have been measured with an average gamma ray energy resolution of approx. 300 eV. Structure in the photofission cross section of 232 Th was observed at approx. 6176 keV

Delayed neutron kinetic functions for /sup 232/Th and /sup 238/U mixtures

Energy Technology Data Exchange (ETDEWEB)

Ganich, P P; Goshovskij, M V; Lendel, A I; Lomonosov, V I; Sikora, D I; Sychev, S I

1984-11-01

In order to investigate the applicability of the method based on using kinetic functions, describing the emission of delayed neutrons by samples for determination of the content of fissionable nuclides in binary mixtures, the /sup 232/Th+/sup 238/U mixtures have been analyzed with the M-30 microtron. Fresh samples containing ThO/sub 2/, U/sub 3/O/sub 8/ and their mixtures are irradiated by bremstrahlung at the 15.5 MeV energy of accelerated electrons and 9 ..mu..A average current. The mass of samples is about 6 g. To determine the kinetic functions, temporal distributions of delayed neutron pulses are used, their maximum number for different samples being (1.7-3.0) x 10/sup 4/. In processing the data obtained two methods of normalization of the delayed neutron number in the kinetic functions are used: to the total yield of delayed neutrons and to the yield of /sup 133/I ..gamma..-quanta. The conclusion is drawn that the method investigated permits to determine relative /sup 238/U concentrations in the mixtures considered with 0.06-0.2 errors. Error reduction is achieved during the normalization of the number of delayed neutrons to the yield of /sup 130/I ..gamma..-quanta.

Comparison of activity concentration of 238U, 232Th and 40K in different Layers of subsurface Structures in Dei-Dei and Kubwa, Abuja, northcentral Nigeria

International Nuclear Information System (INIS)

Maxwell, Omeje; Wagiran, Husin; Ibrahim, Noorddin; Lee, Siak Kuan; Sabri, Soheil

2013-01-01

The study of activity concentration of 232 Th, 238 U and 40 K of rock samples from site one (S1L1–S1L11, 70 m) and site two (S2L1–S2L9, 60 m) boreholes in Dei-Dei and Kubwa was presented and the first time in the region to be compared. Activity concentrations were analysed using a high resolution co-axial HPGe gamma ray spectrometer system. The activity concentration ranges in site one borehole were from 45±1 to 98±6 Bq kg −1 for 232 Th, from 18±2 to 37±4 Bq kg −1 for 238 U and from 254 ±32 Bq kg −1 to 1195 ±151 Bq kg −1 for 40 K. The activity concentration ranges in site two borehole were from 32±3 to 84±7 Bq kg −1 for 232 Th, from 15±2 to 52±5 Bq kg −1 for 238 U and from 119±15 to 705±94 for 40 K Bq kg −1 . Significantly higher concentration of 232 Th and 238 U occurs in samples collected from S1L7, S1L11 and S2L1 layers. These zones experienced granitic intrusions produced by denudation and tectonism. 40 K in rock samples of S1L4 and S2L4 activity concentrations is close; it could be that biotite granitic intrusion that is inferred as the formation in that layer reflects the same activity of potassium in rock's radioactivity measurement. The area requires further investigation of soil geochemistry and activity concentration of radionuclides in groundwater. - Highlights: • Activity concentration of 238 U, 232 Th and 40 K was noted high. • The two boreholes show significant different concentrations of 238 U, 232 Th and 40 K. • The Th/U ratio was high in both, but distinctly higher in first borehole. • 232 Th was increasing with depth in site one almost 100%. • The radiological monitoring on groundwater is recommended

Determination of specific concentrations of 40K, 238U and 232Th in mineral fertilizer samples

International Nuclear Information System (INIS)

Garcez, Ricardo W.D.; Lopes, Jose M.; Silva, Ademir X.

2015-01-01

The use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as 238 U, the 232 Th, and their descendants, beyond 40 K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of 232 Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg -1 , the values of 238 U specific concentrations ranged from 16.0 to 647.7 Bq.Kg -1 and 40 K specific concentrations ranged from 19.1 to 12713 Bq.Kg -1 . Concentrations of values are consistent with those found in literature. (author)

Natural activities of 40K, 238U and 232Th in elephant grass (Pennisetum purpureum) in Ibadan metropolis, Nigeria

International Nuclear Information System (INIS)

Jibiri, N.N.; Ajao, A.O.

2004-01-01

Samples of elephant grass collected at some pasturing farmlands across different locations in Ibadan metropolis were analyzed for their natural radioactivity concentrations due to 40 K, 238 U and 232 Th radionuclides. Radioactivity measurements were carried out using γ-ray spectroscopy. The average radioactivity concentration of 40 K was found to be 64.5±8.1 Bq kg -1 , 25.7±5.5 Bq kg -1 for 238 U and 33.4±3.9 Bq kg -1 for 232 Th. The radiological health implication to the population that may result from these values is found to be very low and almost insignificant. No artificial radionuclide, however, was detected in any of the samples, hence, measurements have been taken as representing baseline values of these radionuclides in the grass in the metropolis

Experimental 233U nondestructive assay with a random driver

International Nuclear Information System (INIS)

Goris, P.

1979-01-01

Nondestructive assay (NDA) of 233 U in quantities up to 15 grams containing 7 ppM 232 U age 2 years was investigated with a random driver. A passive singles counting technique showed a reproducibility within 0.2% at the 95% confidence level. This technique would be applicable throughout a process in which all of the 233 U had the same 232 U content at the same age. Where the 232 U content varies, determination of 233 U fissile content would require active NDA. Active coincidence counting utilizing a 238 Pu, Li neutron source and a plastic scintillator detector system showed a reproducibility limit within 15% at the 95% confidence limit. The active technique was found to be very dependent on the detector system resolving time in order to make proper random coincidence corrections associated with the high gamma activity from the 232 U decay chain

Status of thorium cycle nuclear data evaluations: Comparison of cross-section line shapes of JENDL-3 and ENDF-B-VI files for 230Th, 232Th, 231Pa, 233Pa, 232U, 233U and 234U

International Nuclear Information System (INIS)

Ganesan, S.; McLaughlin, P.K.

1992-02-01

Since 1990, one of the most interesting developments in the field of nuclear data for nuclear technology applications is that several new evaluated data files have been finalized and made available to the International Atomic Energy Agency (IAEA) for distribution to its Member States. Improved evaluated nuclear data libraries such as ENDF/B-VI from the United States and JENDL-3 from Japan were developed over a period of 10-15 years. This report is not an evaluation of the evaluations. The report as presented here gives a first look at the cross section line shapes of the isotopes that are important to the thorium fuel cycle derived from the two recently evaluated data files: JENDL-3 and ENDF/B-VI. The basic evaluated data files JENDL-3 and ENDF/B-VI were point-processed successfully using the codes LINEAR and RECENT. The point data were multigrouped in three different group structures using the GROUPIE code. Graphs of intercomparisons of cross section line shapes of JENDL-3 and ENDF/B-VI are presented in this paper for the following isotopes of major interest to studies of the thorium fuel cycle: 230 Th, 232 Th, 231 Pa, 233 Pa, 232 U, 233 U and 234 U. Comparisons between JENDL-3 and ENDF/B-VI which were performed at the point and group levels show large discrepancies in various cross sections. We conclude this report with a general remark that it is necessary to perform sensitivity studies to assess the impacts of the discrepancies between the two different sets of data on calculated reactor design and safety parameters of specific reactor systems and, based on the results of such sensitivity studies, to undertake new tasks of evaluations. (author). 2 refs, 245 figs, 8 tabs

A comparative study of 232Th and 238U activity estimation in soil samples by gamma spectrometry and Neutron Activation Analysis (NAA) technique

International Nuclear Information System (INIS)

Rekha, A.K.; Anilkumar, S.; Narayani, K.; Babu, D.A.R.

2012-01-01

Radioactivity in the environment is mainly due to the naturally occurring radionuclides like uranium, thorium with their daughter products and potassium. Even though Gamma spectrometry is the most commonly used non destructive method for the quantification of these naturally occurring radionuclides, Neutron Activation Analysis (NAA), a well established analytical technique, can also be used. But the NAA technique is a time consuming process and needs proper standards, proper sample preparation etc. In this paper, the 232 Th and 238 U activity estimated using gamma ray spectrometry and NAA technique are compared. In the case of direct gamma spectrometry method, the samples were analysed after sealing in a 250 ml container. Whereas for the NAA, about 300 mg of each sample, after irradiation were subjected to gamma spectrometry. The 238 U and 232 Th activities (in Bq/kg) in samples were estimated after the proper efficiency correction and were compared. The estimated activities by these two methods are in good agreement. The variation in 238 U and 232 Th activity values are within ± 15% which are acceptable for environmental samples

Dietary 232Th and 238U intakes for Japanese as obtained in a market basket study and contributions of imported foods to internal doses

International Nuclear Information System (INIS)

Shiraishi, K.

1995-01-01

Thorium-232 and 238 U contents in four food groups were measured by inductively coupled plasma mass spectrometry (ICP-MS). Daily intakes of 232 Th and 238 U for Japanese were estimated to 2.22 mBq and 15.5 mBq per person, respectively. Furthermore, preliminary estimations were made for the effects of imported foods on internal exposures for Japanese. (author). 16 refs., 1 fig., 3 tabs

232Th/238U in a uranium mobility estimate in an agricultural area in the municipality of Pedra-Pernambuco - Brazil

International Nuclear Information System (INIS)

Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Bezerra, Jairo Dias; Damascena, Kennedy Francys Rodrigues; Oliveira, Jose Valdez Monterazo de; Bispo, Rodrigo Cesar Bezerra; Silva, Cleomacio Miguel da; Rocha, Edilson Accioly

2011-01-01

The mobility of the radionuclides in soil depends primarily on the physic-chemical parameters. The uranium is easily oxidized in aqueous environment, which allows its characterization with higher mobility. The Thorium is practically insoluble, mainly if the environment has organic matter and sulfates. The geochemical characteristics of the rocks, associated with the weather and metamorphism produce alterations in the concentration diagrams of the natural radionuclides in different types of soil. The ratio 232 Th/ 238 U has been used as an indicator of oxidizing and reducing conditions. Th/U less than 2 suggests that the uranium is in its concentrated form abundantly when compared to the thorium. In reducing conditions, the value Th/U higher than 7 indicates a removal of the uranium. In this work it was possible to analyze the agricultural soil in the municipality of Pedra, Pernambuco, Brazil where there are uranium anomaly and thorium in rocky outcrops. Sixty-two samples of the horizon C soil were collected, in an area of 2 km 2 , where the main uranium occurrences are located. The analyses were done by High-Resolution Gamma-Spectroscopy. In the analyses the secular equilibrium was assumed and the 238 U and the 232 Th specific activities were used to estimate the oxidizing and reducing conditions defining the uranium mobility in the soil. The obtained findings show that the ratio Th/U varied from 0.3 to 13.4, with average of 4.6. The biggest 238 U fraction was fix (80.3%), with low mobility; the smallest fraction concentrated (6.6%) and a lixiviated intermediate fraction (13.1%). (author)

Intake of 238U and 232Th through the consumption of foodstuffs by tribal populations practicing slash and burn agriculture in an extremely high rainfall area

International Nuclear Information System (INIS)

Jha, S.K.; Gothankar, S.; Iongwai, P.S.; Kharbuli, B.; War, S.A.; Puranik, V.D.

2012-01-01

The concentration of naturally occurring radionuclides 232 Th, 238 U was determined using Instrumental Neutron Activation Analysis (INAA) in different food groups namely cereals, vegetables, leafy vegetables, roots and tubers cultivated and consumed by tribal population residing around the proposed uranium mine. The study area is a part of rural area K. P. Mawthabah (Domiasiat) in the west Khasi Hills District of Meghalaya, India located in the tropical region of high rainfall that remains steeped in tribal tradition without much outside influence. Agriculture by Jhum (slash and burn) cultivation and animal husbandry are the main occupation of the tribal populations. A total of 89 samples from locally grown food products were analyzed. The concentration of 238 U and 232 Th in the soil of the study area was found to vary 1.6–15.5 and 2.0–5.0 times respectively to the average mean value observed in India. The estimated daily dietary intake of 238 U and 232 Th were 2.0 μg d −1 (25 mBq d −1 ) and 3.4 μg d −1 (14 mBq d −1 ) is comparable with reported range 0.5–5.0 μg d −1 and 0.15–3.5 μg d −1 respectively for the Asian population. - Highlights: ► 232 Th, 238 U were determined using Instrumental Neutron Activation Analysis (INAA). ► Study area located in the tropical region of high rainfall that remains steeped in tribal tradition. ► Agriculture by Jhum (slash and burn) cultivation and animal husbandry are the main occupation of the tribal populations. ► The estimated daily intake of 232 Th and 238 U in high rainfall area was found to be 3.4 and 2.0 μg respectively.

Environmental geochemistry of 238U, 232Th, 40K and some heavy metals in River Nile sediments

International Nuclear Information System (INIS)

Siddeeg, S. M. B.

2007-06-01

Environmental geochemistry is concerned with the abundance, distribution, and mobility of chemical elements in surface materials at the surface of earth crust. This study aimed at better understanding of geochemical behavior of 238 U, 23 '2Th and 40 K in river sediments and some heavy elements with emphasis on Mg, Ca, Mn, Fe, Ni, Cu, Zn and Pb. The analysis was conducted for a total of 33 bulk sediment samples from White Nile, Blue Nile and River Nile within Khartoum, the samples were fractionated into seven grain sizes each (2000-1000, 1000-500, 500-250, 250-200, 200-125, 125-100 and > 100 μm), using high resolution gamma spectrometer for radionuclides measurements, whereas Particle Induced X-ray Emission (PIXE) was used for heavy metals analysis. On the average, the activity concentration of 238 U, 232 Th and 40 K were 17.90±5.23, 16.38±5.34 and 379.82±107.76 Bq -1 Kg in White Nile, 19.56±5.04, 17.72±4.69, and 494.36±105.79 Bq -1 Kg in Blue Nile and 19.27±2.88, 17.48±2.78, 359.50±83.15 Bq -1 Kg in the River Nile sediments. Results revealed inverse relationship between activity concentration and grain size in White and Blue Nile, while the trend is not clear in the River Nile. In general, the variation of the measured values within single grain size was smaller in White Nile compare to Blue and River Nile sediments, and it was observed that the data are highly scattered in grain size (200-125μm). The ratio between 238 U/ 232 Th is grater than unity in the three rivers indicating that there is relative enrichment of 238 U in the surface sediments. The activity concentration of the fallout radionuclide 137 Cs is one order of magnitude lower in the White Nile sediments (0.89±0.96) Bq -1 Kg compared to values in the Blue Nile sediments (3.60±1.55) Bq -1 Kg. Comparison of the values obtained for natural radionuclides and the fallout radionuclide ( 137 Cs in the three sites with the global data reflect low and /or insignificant difference. For heavy metal

High conversion Th-U{sup 233} fuel assembly for current generation of PWRs

Energy Technology Data Exchange (ETDEWEB)

Baldova, D.; Fridman, E. [Reactor Safety Div., Helmholtz-Zentrum Dresden-Rossendorf, POB 510119, Dresden, 01314 (Germany)

2012-07-01

This paper presents a preliminary design of a high conversion Th-U{sup 233} fuel assembly applicable for current generation of Pressurized Water Reactor (PWRs). The considered fuel assembly has a typical 17 x 17 PWR lattice. However in order to increase the conversion of Th{sup 232} to U{sup 233}, the assembly was subdivided into the two regions called seed and blanket. The central seed region has a higher than blanket U{sup 233} content and acts as a neutron source for the peripheral blanket region. The latest acts as a U{sup 233} breeder. While the seed fuel pins have a standard dimensions the blanket fuel radius was increased in order to reduce the moderation and to facilitate the resonance neutron absorption in blanket Th{sup 232}. The U{sup 233} content in the seed and blanket regions was optimized to achieve maximal initial to discharged fissile inventory ratio (FIR) taking into account the target fuel cycle length of 12 months with 3-batch reloading scheme. In this study the neutronic calculations were performed on the fuel assembly level using Helios deterministic lattice transport code. The fuel cycle length and the core k{sub eff} were estimated by applying the Non Linear Reactivity Model. The applicability of the HELIOS code for the analysis of the Th-based high conversion designs was confirmed with the help of continuous-energy Monte-Carlo code SERPENT. The results of optimization studies show that for the heterogeneous seed and blanket (SB) fuel assembly the FIR of about 0.95 can be achieved. (authors)

Determination of the concentration of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb in the feces of workers from a mining company of niobium and their families

International Nuclear Information System (INIS)

Oliveira, Roges de; Lopes, Ricardo T.; Melo, Dunstana R.; Juliao, Ligia M.Q.C.

2005-01-01

The object of this study consists of an open mine from which Niobium ore (pyrochlore) is extracted and a metallurgy company, where Fe-Nb alloys are produced for export. For geological reasons, the main ore is associated to natural radionuclides U and Th, and its decay products. The concentration of 234 U, 238 U, 232 Th, 226 Ra and 228 Ra, 228 Th, including 210 Pb in fecal excretion of 12:0 am, 29 workers and 13 family members were determined. The technique employed for the determination of the elements was the sequential method of radiochemical separation, followed by alpha spectrometry and counting α and β in proportional detector. Statistically significant difference was observed in the concentration of 234 U and 238 U, in feces samples, among the group of mining workers and family members; as well as for 232 Th in the feces of workers of crushing and metallurgy groups when compared with the Family Group. No statistically significant difference was detected at a concentration of 226 Ra, 228 Ra and 210 Pb, in feces of any group of workers of the installation in relation to the family group

High resolution photofission measurements in 238U and 232Th. Final report

International Nuclear Information System (INIS)

Lancman, H.

1985-12-01

A novel technique for measuring the photofission cross section with very high photon energy resolution has been developed. The photons are obtained from selected resonances in the (p,γ) reaction on various light nuclei. The photon energy resolution approaches 200 eV in favorable cases. The photon energy spread at each (p,γ) resonance is approx.20 keV on the average. Measurements of the photo-fission cross sections of 232 Th and 238 U have been carried out in the energy range from 5.8 to 12 MeV. Intermediate structure has been found in both nuclei at excitation energies around 6 MeV. Various properties of this structure, such as average areas of resonances, their spacing, width, and the underlying bakground, as well as the experimental fission probability averaged over the intermediate structure have been found to agree with theoretical predictions based on a double-humped fission barrier. In the case of 232 Th, the feature of this barrier, a rather high first hump and a deep secondary well, are quite different from those predicted by current theoretial barrier calculations. 13 refs., 4 figs., 3 tabs

Characterization of bauxite residue (red mud) for 235U, 238U, 232Th and 40K using neutron activation analysis and the radiation dose levels as modeled by MCNP.

Science.gov (United States)

Landsberger, S; Sharp, A; Wang, S; Pontikes, Y; Tkaczyk, A H

2017-07-01

This study employs thermal and epithermal neutron activation analysis (NAA) to quantitatively and specifically determine absorption dose rates to various body parts from uranium, thorium and potassium. Specifically, a case study of bauxite residue (red mud) from an industrial facility was used to demonstrate the feasibility of the NAA approach for radiological safety assessment, using small sample sizes to ascertain the activities of 235 U, 238 U, 232 Th and 40 K. This proof-of-concept was shown to produce reliable results and a similar approach could be used for quantitative assessment of other samples with possible radiological significance. 238 U and 232 Th were determined by epithermal and thermal neutron activation analysis, respectively. 235 U was determined based on the known isotopic ratio of 238 U/ 235 U. 40 K was also determined using epithermal neutron activation analysis to measure total potassium content and then subtracting its isotopic contribution. Furthermore, the work demonstrates the application of Monte Carlo Neutral-Particle (MCNP) simulations to estimate the radiation dose from large quantities of red mud, to assure the safety of humans and the surrounding environment. Phantoms were employed to observe the dose distribution throughout the human body demonstrating radiation effects on each individual organ. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measurement of 238U, 232Th and 40K concentrations in different regions of Colombia

Science.gov (United States)

Rodríguez, W.; Lizarazo, C.; Cortés, M. L.; Rodríguez, S. A.; Mendoza, E. F.; Cristancho, F.

2012-02-01

Taking into account the wide variety of geological structures in Colombia, we took a collection of samples both from sand beaches and high mountains systems and determined their concentration of 238U, 232Th and 40K using a high resolution gamma spectrometry system. The results show a variation of these concentrations for the different samples that we associate with the soil type and the environmental conditions of the chosen regions. We also compare our results with other studies carried out in regions with similar geological conditions.

Comparison of potential radiological impacts of 233U and 239Pu fuel cycles

International Nuclear Information System (INIS)

Meyer, H.R.; Little, C.A.; Witherspoon, J.P.; Till, J.E.

1979-01-01

Nuclear fuel cycles utilizing 233 U are currently the subject of considerable interest in the United States. This paper focuses on the identification of significant differences between the off-site radiological hazards posed by 232 Th/ 233 U (Th/U) and 238 U/ 239 Pu (U/Pu) fuel cycles, and represents a portion of our involvement in the Nonproliferation Alternative Systems Assessment Program (NASAP), to be used in support of the International Fuel Cycle Evaluation (INFCE). The major contributors to radiological dose are likely to be uranium mining and milling (58.5% of total fuel cycle dose), reprocessing (33.9%), and light-water reactor power generation (7.3%). The remainder of the cycle, including enrichment processes, fuel fabrication, transportation, and waste management, contributes only 0.3% to total estimated fuel cycle dose

Availability of U-238 and Th-232 present in phosphogypsum used in agriculture: precision and accuracy of the methodology

International Nuclear Information System (INIS)

Malheiro, Luciano H.; Saueia, Catia H.R.; Mazzilli, Barbara P.

2013-01-01

Phosphogypsum (PG) can be classified as Technologically Enhanced Naturally Occurring Radioactive Material (TENORM), and it is obtained as a residue of the phosphate fertilizer industry. PG presents in its composition radionuclides of the natural U and Th series: mainly Ra-226, Ra-228, Th-232, Pb-210 and Po-210. The Brazilian producers stock the PG in dry stacks, posing risks to the surrounding environment. A possible solution to this problem is to reuse PG in agriculture; however, it is necessary to ensure that the radionuclides present in the PG will not be available to the agricultural products. This study is part of a research project sponsored by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP - 2010-10587-0) entitled 'Availability of metals and radionuclides in tropical soils amended with phosphogypsum', and its objective is to evaluate the reliability of an optimal methodology to determine U-238 and Th-232 in samples of soils amended with PG through percolation with water. The methodology comprises a sequential radiochemical separation of the radionuclides present in the leachate. The UTEVA resin was used for the purification and separation of U-238 and Th-232, and the final activity concentrations were determined by alpha spectrometry. The precision and accuracy of the methodology were checked by measuring standard reference material. The results obtained for the relative error and relative standard deviation varied respectively from 2.34 % to 5.92 % and 6.10 % to 6.21 % for uranium, and from 0.42 % to 3.13 % and 9.68 % to 10.97 % for thorium. (author)

Determination of specific concentrations of {sup 40}K, {sup 238}U and {sup 232}Th in mineral fertilizer samples

Energy Technology Data Exchange (ETDEWEB)

Garcez, Ricardo W.D.; Lopes, Jose M.; Silva, Ademir X., E-mail: r.w.o.g@fisica.if.uff.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Domingues, Alessandro M.; Lima, Marco F. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

2015-07-01

The use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as {sup 238}U, the {sup 232}Th, and their descendants, beyond {sup 40}K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of {sup 232}Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg{sup -1}, the values of {sup 238}U specific concentrations ranged from 16.0 to 647.7 Bq.Kg{sup -1} and {sup 40}K specific concentrations ranged from 19.1 to 12713 Bq.Kg{sup -1}. Concentrations of values are consistent with those found in literature. (author)

238 U, 232 Th and 40 K in wheat flour samples of Iraq markets

Directory of Open Access Journals (Sweden)

Ali Abid Abojassim

2015-05-01

Full Text Available Introduction. Wheat flour is a nutritious type of food that is widely consumed by various age groups in Iraq. This study investigates the presence of long-lived gamma emitters in different type of wheat flour in Iraqi market. Materials and methods. Uranium (238 U, Thorium (232 Th and Potassium (40 K specific activity in (Bq/kg were measured in (12 different types of wheat flours that are available in Iraqi markets. The gamma spectrometry method with a NaI(Tl detector has been used for radiometric measurements. Also in this study we have calculated the internal hazard index, radium equivalent and absorbed dose rate in all samples. Results and discussion. It is found that the specific activity in wheat flour samples were varied from (1.086±0.0866 Bq/kg to (12.532±2.026 Bq/kg with an average (6.6025 Bq/kg for 238 U, For 232 Th From (0.126±0.066 Bq/kg to (4.298±0.388 Bq/kg with an average (1.9465Bq/kg and for 40 K from (41.842±5.875 Bq/kg to (264.729±3.843 Bq/kg with an average (133.097 Bq/kg. Also, it is found that the radium equivalent and the internal hazard index in wheat flour samples ranged from (3.4031 Bq/kg to (35.1523 Bq/kg with an average (19.6346 Bq/kg and from (0.0091 to (0.1219 with an average (0.0708 respectively. Conclusion. This study prove that the natural radioactivity and radiation hazard indices were lower than the safe.

235U, 238U, 232Th, 40K and 137Cs activity concentrations in marine sediments along the northern coast of Oman Sea using high-resolution gamma-ray spectrometry

International Nuclear Information System (INIS)

Zare, Mohammad Reza; Mostajaboddavati, Mojtaba; Kamali, Mahdi; Abdi, Mohammad Reza; Mortazavi, Mohammad Seddigh

2012-01-01

The natural radioactivity levels in sediment samples of the northern coast of Oman Sea, covering the coastal strip from Hormoz canyon to Goatr seaport, as the first time has been determined. The results of measurements will serve as background reference level for Oman Sea coastlines. Sediments from 36 coastal and near shore locations were collected for analysis. Analysis on the collected samples were carried out to determine 235 U, 238 U, 232 Th, 40 K and 137 Cs using two high purity germanium detectors with 38.5% and 55% relative efficiencies. The concentration of 235 U, 238 U, 232 Th, 40 K and 137 Cs in sediment samples ranged between 1.01 and 2.87 Bq/kg, 11.83 and 22.68 Bq/kg, 10.7 and 25.02 Bq/kg, 222.89 and 535.07 Bq/kg and 0.14 and 2.8 Bq/kg, respectively. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose.

238U series isotopes and 232Th in carbonates and black shales from the Lesser Himalaya: implications to dissolved uranium abundances in Ganga-Indus source waters

International Nuclear Information System (INIS)

Singh, S.K.; Dalai, Tarun K.; Krishnaswami, S.

2003-01-01

238 U and 232 Th concentrations and the extent of 238 U- 234 U- 230 Th radioactive equilibrium have been measured in a suite of Precambrian carbonates and black shales from the Lesser Himalaya. These measurements were made to determine their abundances in these deposits, their contributions to dissolved uranium budget of the headwaters of the Ganga and the Indus in the Himalaya and to assess the impact of weathering on 238 U- 234 U- 230 Th radioactive equilibrium in them. 238 U concentrations in Precambrian carbonates range from 0.06 to 2.07 μg g -1 . The 'mean' U/Ca in these carbonates is 2.9 ng U mg -1 Ca. This ratio, coupled with the assumption that all Ca in the Ganga-Indus headwaters is of carbonate origin and that U and Ca behave conservatively in rivers after their release from carbonates, provides an upper limit on the U contribution from these carbonates, to be a few percent of dissolved uranium in rivers. There are, however, a few streams with low uranium concentrations, for which the carbonate contribution could be much higher. These results suggest that Precambrian carbonates make only minor contributions to the uranium budget of the Ganga-Indus headwaters in the Himalaya on a basin wide scale, however, they could be important for particular streams. Similar estimates of silicate contribution to uranium budget of these rivers using U/Na in silicates and Na* (Na corrected for cyclic and halite contributions) in river waters show that silicates can contribute significantly (∼40% on average) to their U balance. If, however, much of the uranium in these silicates is associated with weathering resistant minerals, then the estimated silicate uranium component would be upper limits. Uranium concentration in black shales averages about 37 μg g -1 . Based on this concentration, supply of U from at least ∼50 mg of black shales per liter of river water is needed to balance the average river water U concentration, 1.7 μg L -1 in the Ganga-Indus headwaters

The influence of the nature of soil and plant and pollution on the 238U, 232Th, 222Rn and 220Rn concentrations in various natural honey samples using nuclear track detectors: impact on the adult consumers

International Nuclear Information System (INIS)

Misdaq, M.A.; Mortassim, A.

2009-01-01

238 U and 232 Th concentrations as well as 222 Rn and 220 Rn α-activities per unit volume were measured in various natural honey samples collected from different regions in Morocco using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). These radionuclides were also measured in soils, plant flowers and nectar solutions corresponding to the honey samples studied. In addition, these radionuclides were measured in different imported honey samples. The measured 238 U, 232 Th, 222 Rn and 220 Rn concentrations ranged from (1.5 ± 0.1) mBq kg -1 to (10.6 ± 0.6) mBq kg -1 , (1.1 ± 0.1) mBq kg -1 to (4.2 ± 0.2) mBq kg -1 , (1.5 ± 0.1) Bq kg -1 to (10.6 ± 0.6) Bq kg -1 and (1.1 ± 0.1) Bq kg -1 to (4.2 ± 0.2) Bq kg -1 for the honey samples studied, respectively. Annual 238 U, 232 Th and 222 Rn intakes by Moroccan adults from the consumption of honey were assessed. The influence of the nature of soil and plant on the 238 U and 232 Th contents of the studied honey samples was investigated. These measurements were completed by an investigation of the 238 U and 232 Th transfer between soils and plant flowers and that between plant flowers and honey, and also by the investigation of the influence of pollution due to different material dusts on 238 U, 232 Th and 222 Rn in the honey samples studied. Committed equivalent doses due to the annual intake of 238 U, 232 Th and 222 Rn were evaluated in the organs of adult members of the Moroccan rural population from the ingestion of the honey samples. The maximum total committed effective dose due to 238 U, 232 Th and 222 Rn from the ingestion of natural honey by the Moroccan rural population was found to be equal to 0.64 μSνy -1 . (author)

Independent Yields of Kr Isotopes at Photofission of $^{232}$Th and $^{238}$U

CERN Document Server

Gangrsky, Yu P; Zemlyanoi, S G; Maslova, N Yu; Myshinskii, G V; Norov, K S; Penionzhkevich, Yu E; Selesh, O

2002-01-01

The yields of the primary fission fragments - Kr isotopes - at the photofission of ^{232}Th and ^{238}U were measured. The experiments were performed at the microtron of FLNR, JINR, with the energy of the accelerated electrons 25 MeV. The methodic of fission fragments transportation by the gas flow through the capillary and condensation of the inert gases in the cryostat at the liquid nitrogen temperature was used. The fission fragments of other elements were stopped by the filter on the entrance of the capillary. The identification of the Kr isotopes was performed using the gamma-spectra of their daughter products. The mass distribution of the Kr isotopes independent yields was obtained and the comparison with yields at the prompt and thermal neutron fission was discussed.

Distribution of radioactive pollution of 238U, 232Th, 40K and 137Cs in northwestern coasts of Persian Gulf, Iran

International Nuclear Information System (INIS)

Reza Abdi, Mohammad; Kamali, Mehdi; Vaezifar, Sedigheh

2008-01-01

A reconnaissance study has been made of the distribution of 238 U, 232 Th, 40 K and 137 Cs and geochemical features in soils and sediments samples at various locations in the northwestern coast of Persian Gulf. Activity concentration levels due to radionuclides were measured in 30 soil and sediment samples collected from this region. From the measured spectra, activity concentrations were determined for 40 K (range from 146 to 500 Bq kg -1 ), 137 Cs (from 5 to 20 Bq kg -1 ), 238 U (from 21 to 65 Bq kg -1 ) and 232 Th (from 15 to 45 Bq kg -1 ) with lowest limit detection (LLD) of 68, 3.2, 4.3 and 4.3 Bq kg -1 , respectively. The dose rate from ambient air at the soil ranges was between 19 and 58 nGy h -1 with an average of 37.41 ± 9.66 nGy h -1

Use of LabSOCS for determination of specific concentrations of 40K, 238U and 232Th in fertilizer samples

International Nuclear Information System (INIS)

Garcez, Ricardo Washington Dutra; Lopes, Jose Marques; Silva, Ademir Xavier da; Domingues, Alessandro Mariano; Lima, Marco Frota

2015-01-01

Use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as 238 U, the 232 Th, and their descendants, beyond 40 K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of 232 Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg -1 , the values of 238 U specific concentrations ranged from 16.0 to 647.7 Bq.Kg -1 and 40 K specific concentrations ranged from 19.1 to 12713 Bq.Kg -1 . Concentrations of values are consistent with those found in literature. (author)

Quantification of {sup 232}Th, {sup 234}U, {sup 235}U and {sup 238}U in river mollusks by magnetic sector mass spectrometry with inductively coupled plasma source (Icp-SFMS); Cuantificacion de {sup 232}Th, {sup 234}U, {sup 235}U y {sup 238}U en moluscos de rios por espectrometria de masas de sector magnetico con fuente de plasma acoplado inductivamente (ICP-SFMS)

Energy Technology Data Exchange (ETDEWEB)

Arevalo R, D. L.; Hernandez M, H.; Romero G, E. T.; Lara A, N. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Alfaro de la T, M. C., E-mail: arevalo0591@hotmail.com [Universidad Autonoma de San Luis Potosi, Dr. Salvador Nava s/n, Zona Universitaria, 78290 San Luis Potosi, SLP (Mexico)

2016-09-15

The present work deals with the methodology established for the quantification of {sup 232}Th, {sup 234}U, {sup 238}U and {sup 235}U in the shell of gastropod mollusks collected in the rivers Valles, Coy and Axtla of San Luis Potosi, Mexico, which belong to the Panuco River basin; these rivers have as main source of pollution the discharge of municipal sewage, waste from small industries, agricultural and cattle residues and from natural sources. Conventional methods for measuring radio-nuclides are confronted with certain conditions related to the requirement in measurement, basically in the characterization that is related to the concepts of precision and accuracy. The analysis of the gastropod mollusk shell was performed by the Icp-SFMS technique; the main advantages of this technique lie in the isotope quantification capacity, the high precision and the low limits of detection, in this study are very important because these elements are in concentrations between ppb and ppt. This technique allowed the analysis of the samples having a complex matrix by the presence CaCO{sub 3} minimizing the interferences thanks to the ionization efficiency of the Ar plasma. For the species Pachychilus monachus were found concentrations of {sup 232}Th of 0.16-5.37 μg/g and of total U of 0.101-4.081 μg/g being this species where the highest values of total U were found. For Thiara (melanoids) tuberculata the lowest values were found among the different species ({sup 232}Th 0.61-3.61 μg/g and total U 0.006-0.042 μg/g), for Pachychilus suturalis, values of {sup 232}Th of 0.58-6.4 μg/g and for Pachychilus sp. were found between 0.26-7.62 μg/g and for total U values between 0.28-3.33 μg/g. The method offers several advantages: speed, good precision, low values of quantification limits and high sensitivity in the measurement of radio-nuclides and heavy metals. (Author)

Natural Radioactivity of U-238, Th-232 and K-40 in Surface Soil of Baghdad, Nahrain and Al-Mustansiriyah University in Iraq

International Nuclear Information System (INIS)

Ridha, A.A.; Mutter, M.M.; Salim, M.D.

2015-01-01

The study of natural radioactivity in public universities soil is very important because of containing a large numbers of students and personnel in small areas and for long periodic times, especially the centers and gathering students areas. So it was chosen the most important universities in Baghdad city according with the students density, which is Baghdad and Nahrain University in Al-Jadriyah region in addition to Al-Mustansiriyah University in Palestine street region. Thirteen soil samples collected from these regions to estimate the radiological impact to the dweller, the concentrations of 238 U, 232 Th and 40 K present in the soil samples were analyzed using HPGe as Gamma-spectrometry. The results showed that the average radioactivity of 238 U is 26.262±4.52 Bq/ kg, for 232 Th is equal to 24.860±4.03 Bq/ kg and for 40 K is 293.706±16.62 Bq/ kg. Thus, the values of specific activity of 238 U, 232 Th and 40 K for all soil samples are in acceptable values of the worldwide average. The maximum value for Ra eq is 119.727±10.94 Bq/ kg recorded in sample (Bag2), with an average value of 76.938±8.44 Bq/ kg. All soil samples have Ra eq value below the 247 Bq/ kg (Iraqi permissibility limit). In addition to radium equivalent, the absorbed gamma dose rate (D), outdoor annual effective dose and hazard indices are calculated in this work and show low values compared with permissible limits. (author)

Production of 231Pa and 232U by irradiation of 230Th/232Th mixtures

International Nuclear Information System (INIS)

Kluge, E.; Lieser, K.H.

1981-01-01

The production of 231 Pa and of 232 U by irradiating a 230 Th/ 232 Th mixture (containing 12 mol per cent 230 Th) in form of ThO 2 at a thermal neutron flux of 6.9 x 10 13 cm -2 s -1 for 4 months was investigated. Pa, U and Th were separated and the chemical yields were determined. 2.6% of the 230 Th were transformed into 231 Pa and 0.13% into 232 U. These values are higher than those calculated for a thermal flux, but lower than those calculated for a flux ratio epithermal to thermal = 0.03. 231 Pa and 232 U were isolated in form of a protactinium solution and of U 3 O 8 with 94.9 and 89.1% chemical yields, respectively. Foreign activities were not detected. Thorium was recuperated and isolated as ThO 2 , with a chemical yield of 93.6%. (orig.)

Physics concept on the constellation type fissile fuels and its application to the prospective Th-232U Reactor

International Nuclear Information System (INIS)

Zhang, Jiahua

1994-01-01

In contrast with the conventional nuclear reactor which usually fuelled with on single fissile nuclide, a constellation type fissile fuels reactor consists of a parent nuclide such as 232 Th or 238 U and its whole family of neutron generated daughter nuclides. All of them are regarded as fissile fuels but of quite different fission ability. The concentration of each daughter nuclide is determined by its saturate concentration ratio with the parent nuclide. In such fuel system, the whole fuel consumed by neutron reaction almost completely results in fission products. In this article, some properties of such fuel system, determination of the saturate concentration of each daughter nuclide and applicability to Th- 233 U fueled reactor will be discussed. 3 refs., 1 tab., 2 figs

Two types of adakites revealed by 238U-230Th disequilibrium from Daisen volcano, southwestern Japan

International Nuclear Information System (INIS)

Tokunaga, Saimi; Nakai, Shun'ichi; Orihashi, Yuji

2010-01-01

Daisen volcano is located on the Quaternary volcanic front in southwestern Japan. The volcano is composed mainly of andesite and dacite, which chemically resemble adakites, with high Al 2 O 3 and Sr/Y, steep REE patterns, and no negative Eu anomaly. ( 238 U/ 230 Th) disequilibrium (herein, a ratio in parentheses denotes the activity ratio) and trace element analyses of adakites from two volcanic domes, Karasugasen and Misen, indicate two adakite types. Adakite from Karasugasen is characterized by excess ( 230 Th) over ( 238 U), typical of most adakites, whereas adakite from Misen is characterized by excess ( 238 U) over ( 230 Th). The latter is consistent with enrichment in fluid-mobile elements relative to fluid immobile elements compared to rocks from Karasugasen. The values of ( 230 Th/ 232 Th) of adakites from Karasugasen and Misen are, respectively, around 0.75 and 0.81. These low ( 230 Th/ 232 Th) ratios result from the incorporation of subducted sedimentary material. The ratios, nevertheless, are higher than that for the estimate of lower crustal material suggesting significant incorporation of lower crust is unlikely. As adakites from Misen have ( 238 U) excess over ( 230 Th), adakite magma must have interacted with wedge mantle metasomatized by a slab-derived fluid, confirming the presence of a fluid-metasomatized mantle beneath Daisen volcano. (author)

Radioactivity levels of 238U and 232Th, the α and β activities and associated dose rates from surface soil in Ulu Tiram, Malaysia

International Nuclear Information System (INIS)

Abdul Rahman, A.T.; Ramli, A.T.

2007-01-01

A survey was carried out to determine terrestrial gamma radiation dose rates, the concentration level of 238 U and 232 Th and α and β activities for the surface soil in Ulu Tiram, Malaysia. A 125 measurements were performed using a NaI(Tl) gamma-ray detector with crystal size of 1' x 1' on 15 soil samples collected from the site area about 102 km 2 . 238 U and 232 Th concentrations were determined in soils by using hyper pure germanium (HPGe) gamma-ray spectrometry. The activity of α and β from the surface soil was counted by using alpha beta counting system. The average value of 238 U and 232 Th concentrations in soil samples collected are 3.63±0.39 ppm within the range of 1.74±0.20 to 4.58±0.48 and 43.00±2.31 ppm within the range of 10.68±0.76 to 82.10±4.01 ppm, respectively. The average estimate of α and β activity in soil samples collected are 0.65±0.09 Bq x g -1 and 0.68±0.08 Bq x g -1 , respectively. The average of terrestrial gamma-radiation dose rates measured in Ulu Tiram was found to be 200 nGy x h -1 , within the range of 96 to 409 nGy x h -1 . The population weighted outdoor annual effective dose was 1.2 mSv. (author)

Transfer Rates of 238U and 232Th for E. globulus, A. mearnsii, H. filipendula and Hazardous Effects of the Usage of Medicinal Plants From Around Gold Mine Dump Environs

Directory of Open Access Journals (Sweden)

Victor M. Tshivhase

2015-12-01

Full Text Available Medicinal plant consumption can be a source of human exposure to radioactive elements such as 238U and 232Th, which can lead to internal radiation doses. The uptake of 238U and 232Th from soils to the leaf samples of three different medicinal plant species (Eucalyptus globulus, Acacia mearnsii and Hyparrhenia filipendula from the purlieu of the Princess gold mine dump, an abandoned contaminated tailings storage site (TSS, located at longitude 27°55′00″E and latitude 26°09′30″S in Davidsonville (Roodepoort, west of Johannesburg, South Africa was measured. This was done using ICP-MS spectrometry and substantial differences were observed in the soil-plant transfer factor (TF values between these radionuclides. The plant species E. globulus exhibited the highest uptake of 238U, with an average TF of 3.97, while that of H. filipendula was 0.01 and the lowest TF of 0.15 × 10−2 was measured for A. mearnsii. However, in the case of 232Th, the highest average TF was observed for A. mearnsii (0.29, followed by E. globulus (0.10 and lowest was measured for H. filipendula (0.27 × 10−2. The ratio of TF average value i.e., 238U to 232Th in the soil-plant leaves was 38.05 for E. globulus, 0.01 for A. mearnsii and 4.38 for H. filipendula.

Transfer Rates of 238U and 232Th for E. globulus, A. mearnsii, H. filipendula and Hazardous Effects of the Usage of Medicinal Plants From Around Gold Mine Dump Environs

Science.gov (United States)

Tshivhase, Victor M.; Njinga, Raymond L.; Mathuthu, Manny; Dlamini, Thulani C.

2015-01-01

Medicinal plant consumption can be a source of human exposure to radioactive elements such as 238U and 232Th, which can lead to internal radiation doses. The uptake of 238U and 232Th from soils to the leaf samples of three different medicinal plant species (Eucalyptus globulus, Acacia mearnsii and Hyparrhenia filipendula) from the purlieu of the Princess gold mine dump, an abandoned contaminated tailings storage site (TSS), located at longitude 27°55′00″E and latitude 26°09′30″S in Davidsonville (Roodepoort, west of Johannesburg, South Africa) was measured. This was done using ICP-MS spectrometry and substantial differences were observed in the soil-plant transfer factor (TF) values between these radionuclides. The plant species E. globulus exhibited the highest uptake of 238U, with an average TF of 3.97, while that of H. filipendula was 0.01 and the lowest TF of 0.15 × 10−2 was measured for A. mearnsii. However, in the case of 232Th, the highest average TF was observed for A. mearnsii (0.29), followed by E. globulus (0.10) and lowest was measured for H. filipendula (0.27 × 10−2). The ratio of TF average value i.e., 238U to 232Th in the soil-plant leaves was 38.05 for E. globulus, 0.01 for A. mearnsii and 4.38 for H. filipendula. PMID:26690462

The transport characteristics of {sup 238}U, {sup 232}Th, {sup 226}Ra, and {sup 40}K in the production cycle of phosphate rock

Energy Technology Data Exchange (ETDEWEB)

Jung, Yoon Hee; Lim, Jong Myoung; Ji, Young Yong; Chung, Kun Ho; Kang, Mun Ja [Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2017-03-15

Phosphate rock and its by-product are widely used in various industries to produce phosphoric acid, gypsum, gypsum board, and fertilizer. Owing to its high level of natural radioactive nuclides (e.g., 238U and 226Ra), the radiological safety of workers who work with phosphate rock should be systematically managed. In this study, 238U, 232Th, 226Ra, and 40K levels were measured to analyze the transport characteristics of these radionuclides in the production cycle of phosphate rock. Energy dispersive X-ray fluorescence and gamma spectrometry were used to determine the activity of 238U, 232Th, 226Ra, and 40K. To evaluate the extent of secular disequilibrium, the analytical results were compared using statistical methods. Finally, the distribution of radioactivity across different stages of the phosphate rock production cycle was evaluated. The concentration ratios of 226Ra and 238U in phosphate rock were close to 1.0, while those found in gypsum and fertilizer were extremely different, reflecting disequilibrium after the chemical reaction process. The nuclide with the highest activity level in the production cycle of phosphate rock was 40K, and the median 40K activity was 8.972 Bq·g−1 and 1.496 Bq·g−1, respectively. For the 238U series, the activity of 238U and 226Ra was greatest in phosphate rock, and the distribution of activity values clearly showed the transport characteristics of the radionuclides, both for the byproducts of the decay sequences and for their final products. Although the activity of 40K in k-related fertilizer was relatively high, it made a relatively low contribution to the total radiological effect. However, the activity levels of 226Ra and 238U in phosphate rock were found to be relatively high, near the upper end of the acceptable limits. Therefore, it is necessary to systematically manage the radiological safety of workers engaged in phosphate rock processing.

238U, 234U and 230Th in uranium miners' lungs

International Nuclear Information System (INIS)

Singh, M.P.; Wrenn, M.E.; Archer, V.E.; Saccomanno, G.

1981-01-01

Fourteen uranium miners' lungs from Colorado plateau were collected at autopsy and the concentrations of 238 U, 234 U and 230 Th were determined by radiochemical procedures utilizing solvent extraction - alpha spectrometric techniques. The uranium and thorium isotopes are in near equilibrium with average concentrations of 238 U, 234 U and 230 Th being 89.3, 95.2 and 91.1 pCi/kg respectively. The combined average radiation dose rate to lung from these three isotopes is about 24.2 mrad/year at death excluding the unmeasured contribution from the 226 Ra and daughters. The average concentration of 230 Th is about 65 times higher than the mean concentration of 230 Th in lungs of non-miners dying at comparable ages from the same region

230Th-238U radioactive disequilibria in tholeiites from the FAMOUS zone (Mid-Atlantic Ridge, 36050'N): Th and Sr isotopic geochemistry

International Nuclear Information System (INIS)

Condomines, M.; Morand, P.; Allegre, C.J.

1981-01-01

We analyzed, U, Th and 230 Th/ 232 Th activity ratios for a few tholeiites from the Mid-Atlantic Ridge FAMOUS zone at 36 0 50'N. The results show a fairly wider scatter for both Th/U and ( 230 Th/ 232 Th) ratios. Seawater contamination appears to be responsible for this scatter and, for the uranium, produces an increase in content yielding a ( 234 U/ 238 U) ratio greater than 1 and, for the Th, an increase of the ( 230 Th/ 232 Th) ratio which is a very sensitive indicator for contamination. Also, the latter often is selective: U, Th and Sr are not affected in the same manner. When discarding all data for contaminated samples, the FAMOUS zone appears to be very homogeneous with a Th/U ratio value of 3.05 and a ( 230 Th/ 232 Th) ratio value of 1.24. Comparison with other active volcanic areas reveals a negative correlation between ( 230 Th/ 232 Th) and 87 Sr/ 86 Sr ratios for present lavas which is indicative of a consistency in Th-U and Rb-Sr fractionation in the source regions of these magmas. The Th isotopic geochemistry can thus provide useful information for the study of present volcanism, information as valuable as that from Sr, Pb or Nd isotopes. (orig.)

238U, 234U and 230Th in uranium miners' lungs

International Nuclear Information System (INIS)

Singh, N.P.; Wrenn, M.E.; Bennett, D.B.; Archer, V.; Saccomanno, G.

1982-01-01

Fourteen uranium miners' lungs from the Colorado Plateau were collected at autopsy and the concentrations of 238 U, 234 U and 230 Th were determined by radiochemical procedures utilizing solvent extraction and alpha spectrometric techniques. The uranium and thorium isotopes are in near equilibrium with average concentrations of 238 U, 234 U and 230 Th being 89.3, 95.2, and 91.1 pCi/kg respectively. The combined average radiation dose rate to lung from these three isotopes is about 24.1 mrad/year at death excluding the unmeasured contribution from the 226 Ra and daughters. The average concentration of 230 Th is about 65 times higher than the mean concentration of 230 Th in lungs of non-miners from the same region dying at comparable ages

Neutron induced fission cross sections for /sup 232/Th, /sup 235,238/U, /sup 237/Np and /sup 239/Pu from 1 to 400 MeV

Energy Technology Data Exchange (ETDEWEB)

Lisowski, P.W.; Ullmann, J.L.; Balestrini, S.J.; Carlson, A.D.; Wasson, O.A.; Hill, N.W.

1988-01-01

Neutron-induced fission cross section ratios for samples of /sup 232/Th, /sup 235,238/U, /sup 237/Np and /sup 239/Pu have been measured from 1 to 400 MeV. The fission reaction rate was determined for all samples simultaneously using a fast parallel plate ionization chamber at a 20-m flight path. A well characterized annular proton recoil telescope was used to measure the neutron fluence up to 30 MeV. These data provided the shape of the /sup 235/U(n,f) cross section relative to the hydrogen scattering cross section. That shape was then normalized to the very accurately known values were determined using the neutron fluence measured with a second proton recoil telescope. Cross section values for /sup 232/Th, /sup 238/U, /sup 237/Np, and /sup 239/Pu were computed from the ratio data using our values for /sup 235/U(n,f). In addition to providing new results at high neutron energies, these data resolve long standing discrepancies among different data sets. 1 ref., 1 fig.

Consultants' Meeting on Review Benchmarking of Nuclear Data for the Th/U Fuel Cycle. Summary Report

International Nuclear Information System (INIS)

Capote Noy, R.

2011-02-01

A summary is given of the Consultants' Meeting (CM) on Review and Benchmarking of Nuclear Data for the Th/U Fuel Cycle. An IAEA Coordinated Research Project (CRP) on 'Nuclear Data for Th/U Fuel Cycle' was concluded in 2005. The CRP activities resulted in new evaluated nuclear data files for 232 Th, 231 , 233 Pa (later adopted for the ENDF/B-VII.0 library) and improvements to existing evaluations for 232 , 233 , 234 , 236 U. Available nuclear data evaluations for 230 - 232 Th, 231,233 Pa and 232 , 233 , 234 U were reviewed including ROSFOND2010, CENDL-3.1, JENDL-4, JEFF-3.1.1, MINSKACT, and ENDF/B-VII.0 libraries. Benchmark results of available evaluations for 232 Th and 233 U were also discussed. (author)

Quantification of "2"3"2Th, "2"3"4U, "2"3"5U and "2"3"8U in river mollusks by magnetic sector mass spectrometry with inductively coupled plasma source (Icp-SFMS)

International Nuclear Information System (INIS)

Arevalo R, D. L.; Hernandez M, H.; Romero G, E. T.; Lara A, N.; Alfaro de la T, M. C.

2016-09-01

The present work deals with the methodology established for the quantification of "2"3"2Th, "2"3"4U, "2"3"8U and "2"3"5U in the shell of gastropod mollusks collected in the rivers Valles, Coy and Axtla of San Luis Potosi, Mexico, which belong to the Panuco River basin; these rivers have as main source of pollution the discharge of municipal sewage, waste from small industries, agricultural and cattle residues and from natural sources. Conventional methods for measuring radio-nuclides are confronted with certain conditions related to the requirement in measurement, basically in the characterization that is related to the concepts of precision and accuracy. The analysis of the gastropod mollusk shell was performed by the Icp-SFMS technique; the main advantages of this technique lie in the isotope quantification capacity, the high precision and the low limits of detection, in this study are very important because these elements are in concentrations between ppb and ppt. This technique allowed the analysis of the samples having a complex matrix by the presence CaCO_3 minimizing the interferences thanks to the ionization efficiency of the Ar plasma. For the species Pachychilus monachus were found concentrations of "2"3"2Th of 0.16-5.37 μg/g and of total U of 0.101-4.081 μg/g being this species where the highest values of total U were found. For Thiara (melanoids) tuberculata the lowest values were found among the different species ("2"3"2Th 0.61-3.61 μg/g and total U 0.006-0.042 μg/g), for Pachychilus suturalis, values of "2"3"2Th of 0.58-6.4 μg/g and for Pachychilus sp. were found between 0.26-7.62 μg/g and for total U values between 0.28-3.33 μg/g. The method offers several advantages: speed, good precision, low values of quantification limits and high sensitivity in the measurement of radio-nuclides and heavy metals. (Author)

Determination of committed effective doses to skin due to 238U, 232Th and 222Rn from the application of various Moroccan black soap (Saboun Beldi) samples by members of the general public

International Nuclear Information System (INIS)

Misdaq, M. A.; Outeqablit, K.

2010-01-01

238 U, 232 Th, 222 Rn and 220 Rn concentrations were measured inside various Moroccan black soap samples widely used by the Moroccan population in traditional baths (Hammams) by using both CR-39 and LR-115 type II solid state nuclear track detectors. The measured 238 U, 232 Th, 222 Rn and 220 Rn concentrations, respectively, ranged from (3.7±0.2) to (11.7±0.7) mBq kg -1 , (0.11±0.01) to (0.32±0.02) mBq kg -1 , (3.8±0.2) to (11.6±0.6) Bq kg -1 and (0.10±0.01) to (0.31±0.02) Bq kg -1 for the Moroccan black soap samples studied. The influence of pollution on the concentrations of these radionuclides inside the considered Moroccan black soap was investigated. A new dosimetric model for evaluating annual committed effective doses due to 238 U, 232 Th and 222 Rn to the skin of different age groups of the Moroccan populations from the application of the black soap samples studied was developed. The maximum total committed effective dose to the skin due to 238 U, 232 Th and 222 Rn from the application of unpolluted black soap samples 20 min per week by the Moroccan populations was found to be equal to (0.88±0.05) μSv y -1 cm -2 . (authors)

230Th, 232Th and 238U determinations in phosphoric acid fertilizer and process products by ICP-MS

International Nuclear Information System (INIS)

Nascimento, Marcos R.L. do; Guerreiro, Luisa M.R.; Bonifacio, Rodrigo L.; Taddei, Maria H.T.

2015-01-01

Through processing of Santa Quiteria-CE mine phosphate rock, Brazil has established a project for production of phosphoric acid fertilizer and uranium as a by-product. Under leaching conditions of phosphate rock with sulfuric acid, which is the common route for preparing phosphoric acid fertilizer, a large part of uranium, thorium and their decay products naturally present in the rock are solubilized. In order to assess the contamination potential in phosphoric acid and others process products, this paper describes a previous precipitation and direct methods for routine analysis of thorium and uranium isotopes by ICP-MS. In all samples, 230 Th, 232 Th and 238 U were directly determined after dilution, except 230 Th in phosphoric acid loaded with uranium sample, which to overcome equipment contamination effect, was determined after its separation by oxalate precipitation using lanthanum as a carrier. The results obtained by the proposed method by ICP-MS, were in good agreement when compared to alpha spectrometry for 230 Th, and ICP-OES and spectrophotometry with arsenazo III for elementary uranium and thorium determinations. (author)

Influence of form factors and multistep effects on the 232Th(d,t) 231Th and 230Th(d,p) 231Th reactions

International Nuclear Information System (INIS)

Wilcke, W.; Felix, W.; Elze, Th.W.; Huizenga, J.R.; Thompson, R.C.; Dreisler, R.M.

1977-01-01

Tables of spectroscopic information are given for the nuclei 233 , 235 , 237 Pa, and 229 , 231 Ac studied in the reactions 234 , 236 , 238 U, and 230 , 232 Th(t,α), including spin, parity, differential cross sections, and spectra. These quantities are discussed and plotted

A study of rates of (n, f), (n, γ), and (n, 2n) reactions in natU and 232Th produced by the neutron fluence in the graphite set-up (gamma-3) irradiated by 2.33 GeV deuteron beam

International Nuclear Information System (INIS)

Adam, J.; Chitra Bhatia; Katovskij, K.

2011-01-01

Spallation neutrons produced in a collision of 2.33 GeV deuteron beam with the large lead target are moderated by the thick graphite block surrounding the target and used to activate the radioactive samples of nat U and Th put at the three different positions, identified as holes 'a', 'b' and 'c' in the graphite block. Rates of the (n, f), (n, γ), and (n, 2n) reactions in the two samples are determined using the gamma spectrometry. Ratio of the experimental reaction rates, R(n, 2n)/R(n, f) for the 232 Th and nat U are estimated in order to understand the role of reactions of (n, xn) type in Accelerator Driven Subcritical Systems. For the Th-sample, the ratio is ∼ 54(10)% in case of hole 'a' and ∼ 95(57)% in case of hole 'b' compared to 1.73(20)% for the hole 'a' and 0.710(9)% for the hole 'b' in case of the nat U sample. Also the ratio of fission rates in uranium to thorium, nat U(n, f)/ 232 Th(n, f), is ∼ 11.2(17) in case of hole 'a' and 26.8(85) in hole 'b'. Similarly, ratio 238 U(n, 2n)/ 232 Th(n, 2n) is 0.36(4) for the hole 'a' and 0.20(10) for the hole 'b' showing that 232 Th is more prone to the (n, xn) reaction than 238 U. All the experimental reaction rates are compared with the simulated ones by generating neutron fluxes at the three holes from MCNPX 2.6c and making use of LA150 library of cross sections. The experimental and calculated rates of all the three reactions are in good agreement. The transmutation power of the set-up is estimated using the rates of (n, γ) and (n, 2n) reactions for both the samples in the three holes and compared with some of the results of the 'Energy plus Transmutation' set-up and TARC experiment

Distribution of radioactive pollution of {sup 238}U, {sup 232}Th, {sup 40}K and {sup 137}Cs in northwestern coasts of Persian Gulf, Iran

Energy Technology Data Exchange (ETDEWEB)

Reza Abdi, Mohammad [Department of Physics, University of Isfahan, Isfahan 81747-73441 (Iran, Islamic Republic of)], E-mail: r.abdi@phys.ui.ac.ir; Kamali, Mehdi [Central Laboratory, University of Isfahan, Isfahan 81747-73441 (Iran, Islamic Republic of); Vaezifar, Sedigheh [Department of Chemistry, University of Isfahan, Isfahan 81747-73441 (Iran, Islamic Republic of)

2008-04-15

A reconnaissance study has been made of the distribution of {sup 238}U, {sup 232}Th, {sup 40}K and {sup 137}Cs and geochemical features in soils and sediments samples at various locations in the northwestern coast of Persian Gulf. Activity concentration levels due to radionuclides were measured in 30 soil and sediment samples collected from this region. From the measured spectra, activity concentrations were determined for {sup 40}K (range from 146 to 500 Bq kg{sup -1}), {sup 137}Cs (from 5 to 20 Bq kg{sup -1}), {sup 238}U (from 21 to 65 Bq kg{sup -1}) and {sup 232}Th (from 15 to 45 Bq kg{sup -1}) with lowest limit detection (LLD) of 68, 3.2, 4.3 and 4.3 Bq kg{sup -1}, respectively. The dose rate from ambient air at the soil ranges was between 19 and 58 nGy h{sup -1} with an average of 37.41 {+-} 9.66 nGy h{sup -1}.

Evidence for contamination of recent Hawaiian lavas from 230Th-238U data

International Nuclear Information System (INIS)

Condomines, M.; Bernat, M.; Allegre, C.J.

1976-01-01

230 Th- 238 U radioactive disequilibrium was studied in the historical lava flows of the Mauna Loa and Kilauea, Hawaii. Large variations of the ( 230 Th/ 232 Th) ratio among lavas of the same volcano that were erupted at a few years' interval are interpreted as due to contamination. The contamination probably occurs by assimilation of zeolitic minerals formed by seawater interaction while the magma resides in a superficial chamber. (Auth.)

Use of LabSOCS for determination of specific concentrations of {sup 40}K, {sup 238}U and {sup 232}Th in fertilizer samples; Uso de LabSOCS no calculo da eficiencia de detecao para determinacao da concentracao especifica de {sup 40}K, {sup 238}U e {sup 232}Th em amostras de fertilizantes

Energy Technology Data Exchange (ETDEWEB)

Garcez, Ricardo Washington Dutra; Lopes, Jose Marques; Silva, Ademir Xavier da, E-mail: rgarcez@con.ufrj.br, E-mail: marqueslopez@yahoo.com.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Domingues, Alessandro Mariano; Lima, Marco Frota, E-mail: slessandrodomingues@fisica.if.uff.br, E-mail: marcofrotalima@yahoo.com.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Biologia

2015-07-01

Use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as {sup 238}U, the {sup 232}Th, and their descendants, beyond {sup 40}K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of {sup 232}Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg{sup -1} , the values of {sup 238}U specific concentrations ranged from 16.0 to 647.7 Bq.Kg{sup -1} and {sup 40}K specific concentrations ranged from 19.1 to 12713 Bq.Kg{sup -1} . Concentrations of values are consistent with those found in literature. (author)

Th/U-233 multi-recycle in PWRs

International Nuclear Information System (INIS)

Yun, D.; Kim, T.K.; Taiwo, T.A.

2010-01-01

The use of thorium in current or advanced light water reactors (LWRs) has been of interest in recent years. These interests have been associated with the need to increase nuclear fuel resources and the perceived non-proliferation advantages of the utilization of thorium in the fuel cycle. Various options have been considered for the use of thorium in the LWR fuel cycle including: (1) its use in a once-through fuel cycle to replace non-fissile uranium or to extend fuel burnup due to its attractive fertile material conversion, (2) its use for fissile plutonium burning in limited recycle cores, and (3) its advantage in limiting the transuranic elements to be disposed off in a repository (if only Th/U-233 fuel is used). The possibility for thorium utilization in multirecycle system has also been considered by various researchers, primarily because of the potential for near breeders with Th/U-233 in the thermal energy range. The objective of this project is to evaluate the potential of the Th/U-233 fuel multirecycle in current LWRs, with focus this year on pressurized water reactors (PWRs). In this work, approaches for ensuring a sustainable multirecycle without the need for external source of makeup fissile material have been investigated. The intent is to achieve a design that allows existing PWRs to be used with minimal modifications. In all cases including homogeneous and heterogeneous assembly designs, the assembly pitch is kept consistent with that of the current PWRs (21.5 cm used). Because of design difficulties associated with using the same geometry and dimensions as a PWR core, the potential modifications (other than assembly pitch) that would be needed for PWRs to ensure a sustainable multirecycle system have been investigated and characterized. Additionally, the implications of the use of thorium on the LWR fuel cycle are discussed. In Section 2, background information on studies evaluating the use of thorium in the fuel cycle is provided, but focusing on

Th/U-233 multi-recycle in PWRs.

Energy Technology Data Exchange (ETDEWEB)

Yun, D.; Kim, T. K.; Taiwo, T. A.; Nuclear Engineering Division

2010-09-07

The use of thorium in current or advanced light water reactors (LWRs) has been of interest in recent years. These interests have been associated with the need to increase nuclear fuel resources and the perceived non-proliferation advantages of the utilization of thorium in the fuel cycle. Various options have been considered for the use of thorium in the LWR fuel cycle including: (1) its use in a once-through fuel cycle to replace non-fissile uranium or to extend fuel burnup due to its attractive fertile material conversion, (2) its use for fissile plutonium burning in limited recycle cores, and (3) its advantage in limiting the transuranic elements to be disposed off in a repository (if only Th/U-233 fuel is used). The possibility for thorium utilization in multirecycle system has also been considered by various researchers, primarily because of the potential for near breeders with Th/U-233 in the thermal energy range. The objective of this project is to evaluate the potential of the Th/U-233 fuel multirecycle in current LWRs, with focus this year on pressurized water reactors (PWRs). In this work, approaches for ensuring a sustainable multirecycle without the need for external source of makeup fissile material have been investigated. The intent is to achieve a design that allows existing PWRs to be used with minimal modifications. In all cases including homogeneous and heterogeneous assembly designs, the assembly pitch is kept consistent with that of the current PWRs (21.5 cm used). Because of design difficulties associated with using the same geometry and dimensions as a PWR core, the potential modifications (other than assembly pitch) that would be needed for PWRs to ensure a sustainable multirecycle system have been investigated and characterized. Additionally, the implications of the use of thorium on the LWR fuel cycle are discussed. In Section 2, background information on studies evaluating the use of thorium in the fuel cycle is provided, but focusing on

The transport characteristics of "2"3"8U, "2"3"2Th, "2"2"6Ra, and "4"0K in the production cycle of phosphate rock

International Nuclear Information System (INIS)

Jung, Yoon Hee; Lim, Jong Myoung; Ji, Young Yong; Chung, Kun Ho; Kang, Mun Ja

2017-01-01

Phosphate rock and its by-product are widely used in various industries to produce phosphoric acid, gypsum, gypsum board, and fertilizer. Owing to its high level of natural radioactive nuclides (e.g., 238U and 226Ra), the radiological safety of workers who work with phosphate rock should be systematically managed. In this study, 238U, 232Th, 226Ra, and 40K levels were measured to analyze the transport characteristics of these radionuclides in the production cycle of phosphate rock. Energy dispersive X-ray fluorescence and gamma spectrometry were used to determine the activity of 238U, 232Th, 226Ra, and 40K. To evaluate the extent of secular disequilibrium, the analytical results were compared using statistical methods. Finally, the distribution of radioactivity across different stages of the phosphate rock production cycle was evaluated. The concentration ratios of 226Ra and 238U in phosphate rock were close to 1.0, while those found in gypsum and fertilizer were extremely different, reflecting disequilibrium after the chemical reaction process. The nuclide with the highest activity level in the production cycle of phosphate rock was 40K, and the median 40K activity was 8.972 Bq·g−1 and 1.496 Bq·g−1, respectively. For the 238U series, the activity of 238U and 226Ra was greatest in phosphate rock, and the distribution of activity values clearly showed the transport characteristics of the radionuclides, both for the byproducts of the decay sequences and for their final products. Although the activity of 40K in k-related fertilizer was relatively high, it made a relatively low contribution to the total radiological effect. However, the activity levels of 226Ra and 238U in phosphate rock were found to be relatively high, near the upper end of the acceptable limits. Therefore, it is necessary to systematically manage the radiological safety of workers engaged in phosphate rock processing

Distribution of 238U, 232Th, 40K, and 137Cs concentrations in soil samples nearby a nuclear laboratory, Capao Island, Brazil

Directory of Open Access Journals (Sweden)

Oliveira Luciano S.R.

2015-01-01

Full Text Available Absolute soil concentrations of 238U, 232Th, 40K, and 137Cs samples were measured using high-resolution gamma spectrometry. The area of interest encompasses an embankment in a mangrove swamp in Guaratiba, Rio de Janeiro, called Capao Island, where nuclear, chemical and biological defense laboratories of the Brazilian Army Technology Center are in operation for more than 30 years. In order to ensure that no significant environmental impact has resulted from neutron physics experiments performed in a graphite exponential pile in addition to the operation of two cesium-driven irradiating facilities, radiation monitoring of the isotopes was carried out. A total of eight 250 ml soil samples were extracted within an area of 300 m x 300 m. No trace of 137Cs was detected and the measured levels of 238U were found to be close to the global mean. However, some data that slightly exceeded the expected normal range for 232Th (60 % of samples and 40K (20 % of samples should be attributed to the construction debris (cement, rocks, and sand used in the embankment at the site. Since there is no handling of those isotopes at that site or adjacent facilities that could affect their presence, it was concluded that no detectable contamination has occurred.

230Th-238U disequilibrium systematics in oceanic tholeiites from 210N on the East Pacific Rise

International Nuclear Information System (INIS)

Newman, S.; Finkel, R.C.; MacDougall, J.D.

1983-01-01

Significant disequilibrium occurs between 230 Th and its parent, 238 U, in a suite of fresh basalt glasses from the RISE Project study area at 21 0 N on the East Pacific Rise. The ( 230 Th/ 232 Th) activity ratios observed for eight of nine samples from the crest of the axis at this site are constant within analytical uncertainty, with a value of 1.22. This observed homogeneity of ( 230 Th/ 232 Th) has two possible interpretations. First, the measured ( 230 Th/ 232 Th) can be considered to indicate a mantle-source for the RISE basalts with Th/U of 2.5. This interpretation, however, conflicts with the proposed correlation between ( 230 Th/ 232 Th) and 87 Sr/ 86 Sr which predicts that ( 230 Th/ 232 Th) should equal 1.33 at the RISE site. A second possible interpretation is that radioactive decay of 230 Th, in the basalts themselves or in a magma chamber, has decreased ( 230 Th/ 232 Th) from 1.33 to the observed values. The required time span is 11,000 to > 100,000 years. However, petrologic arguments rule against long residence time in a magma chamber, and the spreading rate of this section of the East Pacific Rise (6 cm/yr) predicts that the maximum age for axis basalts is 27,000 years. Both interpretations of the measured ( 230 Th/ 232 Th) imply a low Th/U ratio for the RISE basalt source and suggest that the MORB source at this location is depleted in Th with respect to U relative to primitive mantle or bulk earth. (orig./WL)

Implantation of alpha spectrometry methodology for the determination of U and Th isotopes in igneous rocks: application to the study of radioactive desequilibrium in the Trindade Island, Brazil

International Nuclear Information System (INIS)

Santos, Rosana Nunes dos

2001-01-01

This work describes the implementation of experimental procedures for alpha spectrometry measurement of 238 U, 234 U and 230 Th activities in silicates. The best experimental conditions were defined using 233 U, 232 U and 229 Th radioactive tracers and simulating the usual conditions found in processing silicates. The chemical procedures consists of the following steps: radioactive tracer addition and sample dissolution by acid digestion, U and Th pre-concentration by co-precipitation, element separation and purification by ion exchange chromatography and electrodeposition in inox steel disks. In order to evaluate its effectiveness, the procedure was applied to the Brazilian geological standards BB-1 (basalt) and GB-1 (granite). The obtained chemical yields for uranium and thorium are of about 60% and 70%, respectively, for both matrices. The described methodology furnishes activity measurements with less than 4% relative precision and accuracies of about 1%, that are essential for petrogenetic applications. The 238 U and 232 Th series disequilibrium conditions were investigated by alpha spectrometry, together with neutron activation analysis and natural gamma-ray spectrometry. 234 U/ 238 U, 238 U/ 232 Th and 230 Th/ 232 Th activity ratios and the 234 Th, 214 Pb, 214 Bi, 235 U, 228 Ac, 212 Pb, 212 Bi and 208 Tl specific activities were obtained. These results were interpreted with the help of additional constraints given by the larger and smaller elements concentrations, measured by X-ray fluorescence. The 232 Th series is in secular radioactive equilibrium in all analysed samples. In the case of the 238 U series, the equilibrium condition was verified, as expected, in the oldest rocks from the Trindade Island (Trindade Complex and Desejado Sequence). On the other hand, the results show that, in the samples from the last three volcanic episodes in the island (Morro Vermelho Formation, Valado Formation and Vulcao do Paredao), the 230 Th and 238 U are not in

Fuel utilization improvement in PWRs using the denatured 233U-Th cycle

International Nuclear Information System (INIS)

Jones, H.M.; Schwenk, G.A.; Toops, E.C.; Yotinen, V.O.

1980-06-01

A number of changes in PWR core design and/or operating strategy were evaluated to assess the fuel utilization improvement achievable by their implementation in a PWR using thorium-based fuel and operating in a recycle mode. The reference PWR for this study was identical to the B and W Standard Plant except that the fuel pellets were of denatured ( 233 U/ 238 U-Th)O 2 . An initial scoping study identified the three most promising improvement concepts as (1) a very tight lattice, (2) thorium blankets, and (3) ThO 2 rods placed in available guide tubes. A conceptual core design incorporating these changes was then developed, and the fuel utilization of this modified design was compared with that of the reference case

Speciation analysis of 129I, 137Cs, 232Th, 238U, 239Pu and 240Pu in environmental soil and sediment

DEFF Research Database (Denmark)

Qiao, Jixin; Hansen, Violeta; Hou, Xiaolin

2012-01-01

The environmental mobility and bioavailability of radionuclides are related to their physicochemical forms, namely species. We here present a speciation analysis of important radionuclides including 129I (also 127I), 137Cs, 232Th, 238U and plutonium isotopes (239Pu and 240Pu) in soil (IAEA-375......) and sediment (NIST-4354) standard reference materials and two fresh sediment samples from Øvre Heimdalsvatnet Lake, Norway. A modified sequential extraction protocol was used for the speciation analysis of these samples to obtain fractionation information of target radionuclides. Analytical results reveal...

Evaluation of fission cross sections and covariances for 233U, 235U, 238U, 239Pu, 240Pu, and 241Pu

International Nuclear Information System (INIS)

Kawano, Toshihiko; Matsunobu, Hiroyuki; Murata, Toru

2000-02-01

A simultaneous evaluation code SOK (Simultaneous evaluation on KALMAN) has been developed, which is a least-squares fitting program to absolute and relative measurements. The SOK code was employed to evaluate the fission cross sections of 233 U, 235 U, 238 U, 239 Pu, 240 Pu, and 241 Pu for the evaluated nuclear data library JENDL-3.3. Procedures of the simultaneous evaluation and the experimental database of the fission cross sections are described. The fission cross sections obtained were compared with evaluated values given in JENDL-3.2 and ENDF/B-VI. (author)

Computational Approach in Determination of 233U and 233Th Fermi Energy

International Nuclear Information System (INIS)

Kurniadi, R.; Perkasa, Y. S.; Waris, A.

2010-01-01

There are several methods to get Fermi energy such as hermit polynomial expansion and Wigner-Kirkwood expansion, these are analytical method. In this paper will be discussed numerical approach of calculating Fermi energy of 233 Th and 233 U nuclei. Our work demonstrates the simple technique of determining Fermi energy.

Relics of continental lithosphere in the atlantic by data of (Th/U)th, (Th/U)pb, and K/Ti systematics

International Nuclear Information System (INIS)

Titayeva, N.A.; Mironov, Y.

1996-01-01

The problem of mantle heterogeneity of the Atlantic Ocean has been investigated. Th/U ratio is a sensitive geochemical tracer. This ratio can be calculated from 232Th/230Th or from 208Pb/206Pb since 230Th and 206Pb are decay product of 238U and 208Pb is a product of 232Th decay. The former way to get Th/U ratio is valid for quaternary volcanic rocks because of the relatively short 230Th half life (80000 years), the latter way gives an integral quantity characterizing the pre-oceanic history beginning from the onset of earth formation and ending about 150 million years ago. Clear distinctions between ''depleted oceanic'' and ''enriched continental'' reservoirs have been drawn from comparative analysis of rocks. (A.C.)

Rapid screening of natually occurring radioactive nuclides({sup 2}'3{sup 8}U, {sup 232}Th) in raw materials and by-products samples using XRF

Energy Technology Data Exchange (ETDEWEB)

Park, Ji Young; Lim, Chung Sup [Radiation Biotechnology and Applied Radioiostope Science, University of Science and Technology, Daejeon (Korea, Republic of); Lim, Jong Myoung; Ji, Young Yong; Chung, Kun Ho; Lee, Wan No; Kang, Mun Ja [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Jang, Byung Uck [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2016-12-15

As new legislation has come into force implementing radiation safety management for the use of naturally occurring radioactive materials (NORM), it is necessary to establish a rapid and accurate measurement technique. Measurement of {sup 238}U and {sup 232}Th using conventional methods encounter the most significant difficulties for pretreatment (e.g., purification, speciation, and dilution/enrichment) or require time-consuming processes. Therefore, in this study, the applicability of ED-XRF as a non-destructive and rapid screening method was validated for raw materials and by-product samples. A series of experiments was conducted to test the applicability for rapid screening of XRF measurement to determine activity of {sup 238}U and {sup 23{sup 2}}Th based on certified reference materials (e.g., soil, rock, phosphorus rock, bauxite, zircon, and coal ash) and NORM samples commercially used in Korea. Statistical methods were used to compare the analytical results of ED-XRF to those of certified values of certified reference materials (CRM) and inductively coupled plasma mass spectrometry (ICP-MS). Results of the XRF measurement for {sup 238}U and {sup 232}Th showed under 20% relative error and standard deviation. The results of the U-test were statistically significant except for the case of U in coal fly ash samples. In addition, analytical results of {sup 238}U and {sup 232}Th in the raw material and by-product samples using XRF and the analytical results of those using ICP-MS (R{sup 2}≥0.95) were consistent with each other. Thus, the analytical results rapidly derived using ED-XRF were fairly reliable. Based on the validation results, it can be concluded that the ED-XRF analysis may be applied to rapid screening of radioactivities ({sup 238}U and {sup 232}Th) in NORM samples.

Daily ingestion of 232Th, 238U, 226Ra, 228Ra and 210Pb in vegetables by inhabitants of Rio de Janeiro City

International Nuclear Information System (INIS)

Santos, E.E.; Lauria, D.C.; Amaral, E.C.S.; Rochedo, E.R.

2002-01-01

The concentrations of the naturally occurring radionuclides 232 Th, 238 U, 210 Pb, 226 Ra and 228 Ra were determined in the vegetables (leafy vegetables, fruit, root, bean and rice) and derived products (sugar, coffee, manioc flour, wheat flour, corn flour and pasta) consumed most by the adult inhabitants of Rio de Janeiro City. A total of 88 samples from 26 different vegetables and derived products were analyzed. The highest contribution to radionuclide intake arises from bean, wheat flour, manioc flour, carrot, rice, tomato and potato consumption. The estimated daily intakes due to the consumption of vegetables and derived products are 1.9 mBq of 232 Th (0.47 μg), 2.0 mBq of 238 U (0.17 μg), 19 mBq of 226 Ra, 26 mBq of 210 Pb and 47 mBq of 228 Ra. The estimated annual effective dose due to the ingestion of vegetables and their derived products with the long-lived natural radionuclides is 14.5 μSv. Taking into account literature data for water and milk from Rio de Janeiro the dose value increases to 29 μSv, with vegetables and derived products responsible for 50% of the dose and water for 48%. 210 Pb (62%) and 228 Ra (24%) were found to be the main sources for internal irradiation

Fission Product Yields of 233U, 235U, 238U and 239Pu in Fields of Thermal Neutrons, Fission Neutrons and 14.7-MeV Neutrons

Science.gov (United States)

Laurec, J.; Adam, A.; de Bruyne, T.; Bauge, E.; Granier, T.; Aupiais, J.; Bersillon, O.; Le Petit, G.; Authier, N.; Casoli, P.

2010-12-01

The yields of more than fifteen fission products have been carefully measured using radiochemical techniques, for 235U(n,f), 239Pu(n,f) in a thermal spectrum, for 233U(n,f), 235U(n,f), and 239Pu(n,f) reactions in a fission neutron spectrum, and for 233U(n,f), 235U(n,f), 238U(n,f), and 239Pu(n,f) for 14.7 MeV monoenergetic neutrons. Irradiations were performed at the EL3 reactor, at the Caliban and Prospero critical assemblies, and at the Lancelot electrostatic accelerator in CEA-Valduc. Fissions were counted in thin deposits using fission ionization chambers. The number of fission products of each species were measured by gamma spectrometry of co-located thick deposits.

Assessment of natural radionuclides concentration from 238U and 232Th series in Virginia and Burley varieties of Nicotiana tabacum L

International Nuclear Information System (INIS)

Silva, Carolina Fernanda da

2015-01-01

Brazil is the largest exporter and second largest producer of tobacco worldwide, according to the crop production of 2013/2014. The tobacco plant (Nicotiana tabacum L.) is used to manufacture all derivatives and the chemical composition of the resulting tobacco products varies with the type of tobacco leaves, how they are grown, the region where they are cultivated, the characteristics of preparation (compression, filter and paper) and the temperature variations resulting from the incomplete combustion of tobacco. Tobacco products are extensively used throughout the world, and the most consumed are cigarettes, cigars and narghile. The damaging effects that these products cause to human health are discussed globally, and many surveys are performed with the aim of relating the use of these products with various illnesses. There is a lack of information about the radiological characterization of the tobacco plant both in international and Brazilian literature. The objective of this study was to determine the concentration of radionuclides 238 U, 234 U, 230 Th, 22 '6Ra, 210 Pb and 210 Po, members from the 238 U decay series, and the radionuclides 232 Th and 228 Ra members of the 232 Th decay series in the varieties Burley and Virginia, which are the most cultivated in Brazil. Plants from these varieties were cultivated in pots with organic substrate and fertilizer and also acquired from the producers and analyzed by alpha spectrometry for U and Th isotopes and 210 Po determination, and gross alpha and beta counting, 228 Ra, 226 Ra and 210 Pb determination. The whole plant, from both places, was analyzed; root, stem, leaves, as well as the organic substrate, the fertilizers, and the soil. The results for U and Th isotopes presented values below the detection limits of the methods to the leaves and stems of all plants analyzed, with measurable results only in roots, soil, and substrate. The radionuclides 226 Ra, 228 Ra, 210 Pb, and 210 Po, were determined in most

Calibration of 232U solution; Calibracion de una disolucion de 232U

Energy Technology Data Exchange (ETDEWEB)

Galan Valera, M P; Acena Berrenechea, M L

1988-07-01

A method for as certain the activity by alpha spectroscopy with semiconductor detectors, of a solution of 232U is presented. It consists of the comparison with a 233U solution activity previously measured in a gridded ionization chamber of 2{pi} geometry. The total measurement uncertainty is about + - 0,02. (Author) 9 refs.

Mass spectrometric 230Th-234U-238U dating of the Devils Hole calcite vein

International Nuclear Information System (INIS)

Ludwig, K.R.; Simmons, K.R.; Szabo, B.J.; Riggs, A.C.; Winograd, I.J.; Landwehr, J.M.; Hoffman, R.J.

1992-01-01

The Devils Hole calcite vein contains a long-term climatic record, but requires accurate chronologic control for its interpretation. Mass-spectrometric U-series ages for samples from core DH-11 yielding 230 Th ages with precisions ranging from less than 1,000 years (2σ) for samples younger than ∼140 ka (thousands of years ago) to less than 50,000 years for the oldest samples (∼566 ka). The 234 U/ 238 U ages could be determined to a precision of ∼20,000 years for all ages. Calcite accumulated continuously from 566 ka until ∼60 ka at an average rate of 0.7 millimeter per 10 3 years. The precise agreement between replicate analyses and the concordance of the 230 Th/ 238 U and 234 U/ 238 U ages for the oldest samples indicate that the DH-11 samples were closed systems and validate the dating technique in general

(232)Th(d,4n)(230)Pa cross-section measurements at ARRONAX facility for the production of (230)U.

Science.gov (United States)

Duchemin, C; Guertin, A; Haddad, F; Michel, N; Métivier, V

2014-05-01

(226)Th (T1/2=31 min) is a promising therapeutic radionuclide since results, published in 2009, showed that it induces leukemia cells death and activates apoptosis pathways with higher efficiencies than (213)Bi. (226)Th can be obtained via the (230)U α decay. This study focuses on the (230)U production using the (232)Th(d,4n)(230)Pa(β-)(230)U reaction. Experimental cross sections for deuteron-induced reactions on (232)Th were measured from 30 down to 19 MeV using the stacked-foil technique with beams provided by the ARRONAX cyclotron. After irradiation, all foils (targets as well as monitors) were measured using a high-purity germanium detector. Our new (230)Pa cross-section values, as well as those of (232)Pa and (233)Pa contaminants created during the irradiation, were compared with previous measurements and with results given by the TALYS code. Experimentally, same trends were observed with slight differences in orders of magnitude mainly due to the nuclear data change. Improvements are ongoing about the TALYS code to better reproduce the data for deuteron-induced reactions on (232)Th. Using our cross-section data points from the (232)Th(d,4n)(230)Pa reaction, we have calculated the thick-target yield of (230)U, in Bq/μA·h. This value allows now to a full comparison between the different production routes, showing that the proton routes must be preferred. Copyright © 2014 Elsevier Inc. All rights reserved.

A four phases model to simulate the dispersion of 226Ra, 238U and 232Th in an estuary affected by phosphate rock processing

International Nuclear Information System (INIS)

Perianez, R.; Abril, J.M.; Garcia-Leon, M.

1997-01-01

A numerical model to simulate the dispersion of non conservative radionuclides in tidal waters has been developed. The model includes four phases: water, suspended matter and two grain size sediment fractions. Ionic exchanges between water and the solid phases have been formulated in terms of kinetic transfer coefficients instead of distribution coefficients, because the model was developed for nonequilibrium conditions. The model simultaneously solves the shallow water hydrodynamic equations, the suspended matter dispersion equation and the four equations which give the time evolution of specific activity in each phase. The model has been applied to the Odiel river (southwest Spain), where a phosphate complex releases its wastes. It gives good results in predicting concentrations of 226 Ra, 238 U and 232 Th in water, suspended matter, distribution coefficients and Th/U mass rations. (author)

230Th/U-dating of a late Holocene low uranium speleothem from Cuba

International Nuclear Information System (INIS)

Fensterer, Claudia; Mangini, Augusta; Scholz, Denis; Hoffmann, Derik; Pajon, Jesus M

2010-01-01

We present 22 U-series ages for a stalagmite from north-western Cuba based on multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and thermal ionisation mass spectrometry (TIMS). Our results reveal that the stalagmite continuously grew within the last ∼1400a. Low uranium content of the sample and thus, extremely low 230 Th concentrations limit the precision and accuracy of 230 Th/U-dating by TIMS. Samples measured by MC-ICPMS show a high variability of 232 Th content along the growth axis with some sections significantly affected by initial 230 Th from a detrital phase. An a-priori bulk earth ratio for ( 238 U/ 232 Th) cannot be used to accurately account for this initial 230 Th. Using an age model based on the 230 Th/U ages determined on samples with low or negligible 232 Th concentration, we find that the ( 238 U/ 232 Th) activity ratio of the detrital phase is an order of magnitude larger than the bulk earth value, indicating the importance of an accurately determined correction factor.

Studies on use of reflector material and its position within FBR core for reducing U{sup 232} content of U produced in ThO{sub 2} radial blankets

Energy Technology Data Exchange (ETDEWEB)

Sen, Sujoy, E-mail: sujoy@igcar.gov.in [Core Design Group, IGCAR, Kalpakkam (India); Prasad, Rajeev Ranjan; Bagchi, Subhrojit [Core Design Group, IGCAR, Kalpakkam (India); Mohanakrishnan, P. [MCNS, Manipal University, Manipal (India); Arul, A. John; Puthiyavinayagam, P. [Core Design Group, IGCAR, Kalpakkam (India)

2015-11-15

Highlights: • Nuclear data processing for multigroup neutron transport calculation. • Discrete ordinate and Monte Carlo neutron transport. • Breeding of Thorium in Fast Reactor. • Minimization of U{sup 232} in U{sup 233}. • Fuel burn up using Neutron Diffusion. - Abstract: Presence of U{sup 232} in U{sup 233} bred in thorium blanket of fast reactor is a major concern in fuel reprocessing. The former's daughter products being hard gamma emitter and the isotope itself having substantial half life, its presence beyond 10 ppm makes fuel recycle complicated and expensive. In this study possibility of decreasing U{sup 232} production in a typical FBR blanket by means of spectrum modification is examined. SS, depleted B{sub 4}C, SiC, Mo and W regions were introduced between core and radial blanket and evolution of isotopes were studied to arrive at an optimal configuration that satisfies requirements of breeding U{sup 233} and lowering U{sup 232}concentration. SS, B{sub 4}C, SiC, Mo and W are known to be high temperature material with appropriate stability in harsh fast reactor environment. Study has shown that introducing two SS reflector rows can achieve the required low value of U{sup 232}concentration without greatly compromising the U{sup 233}production.

Assessment of natural radionuclides concentration from {sup 238}U and {sup 232}Th series in Virginia and Burley varieties of Nicotiana tabacum L; Avaliacao da concentracao dos radionuclideos naturais das series do {sup 238}U e {sup 232}Th nas variedades Burley e Virginia da Nicotiana tabacum L.

Energy Technology Data Exchange (ETDEWEB)

Silva, Carolina Fernanda da

2015-07-01

Brazil is the largest exporter and second largest producer of tobacco worldwide, according to the crop production of 2013/2014. The tobacco plant (Nicotiana tabacum L.) is used to manufacture all derivatives and the chemical composition of the resulting tobacco products varies with the type of tobacco leaves, how they are grown, the region where they are cultivated, the characteristics of preparation (compression, filter and paper) and the temperature variations resulting from the incomplete combustion of tobacco. Tobacco products are extensively used throughout the world, and the most consumed are cigarettes, cigars and narghile. The damaging effects that these products cause to human health are discussed globally, and many surveys are performed with the aim of relating the use of these products with various illnesses. There is a lack of information about the radiological characterization of the tobacco plant both in international and Brazilian literature. The objective of this study was to determine the concentration of radionuclides {sup 238}U, {sup 234}U, {sup 230}Th, {sup 22}'6Ra, {sup 210}Pb and {sup 210}Po, members from the {sup 238}U decay series, and the radionuclides {sup 232}Th and {sup 228}Ra members of the {sup 232}Th decay series in the varieties Burley and Virginia, which are the most cultivated in Brazil. Plants from these varieties were cultivated in pots with organic substrate and fertilizer and also acquired from the producers and analyzed by alpha spectrometry for U and Th isotopes and {sup 210}Po determination, and gross alpha and beta counting, {sup 228}Ra, {sup 226}Ra and {sup 210}Pb determination. The whole plant, from both places, was analyzed; root, stem, leaves, as well as the organic substrate, the fertilizers, and the soil. The results for U and Th isotopes presented values below the detection limits of the methods to the leaves and stems of all plants analyzed, with measurable results only in roots, soil, and substrate. The

Assessment of radiological impact in mineral industrial plants caused by deposition of wastes with U238 and/or Th232 associated

International Nuclear Information System (INIS)

Ladeira, Paula C.; Alves, Rex Nazare; Ruperti Junior, Nerbe J.

2011-01-01

The industrial-mining facilities constantly produce, in Brazil and in abroad, wastes from its production, many times containing uranium and/or thorium associated. Due to the large quantities generated, these wastes are usually deposited at the site of the facility, close to the place where they were produced. Since the chains of radioactive U 238 and Th 232 with alpha-emitting radionuclides have long half-life, waste deposits associated with these elements may cause radiological impact on the man and on the environment, even in the long term. Mathematical models are often used to represent the biosphere and the transport of radionuclides near to the surface. Thus, it was decided, through the software M athematica , to present a methodology based on the solution of Bateman equations for the calculation of radiological impact on individuals from the public exposed to contamination. The radiological impact appraisal was carried out considering a scenario of intrusion into landfills containing U 238 and / or Th 232 in post-operational phase of an industrial-mining installation. The critical group examined was represented by farmers who used water from an artesian well for daily consumption and which feed themselves on vegetables locally grown in clay soil. As a result, there was the exposure in pathways evaluated, a minor contribution of dose for ingestion of contaminated water. The conclusion of this work, show us that calculated doses were within the accepted international limits for the intrusion scenario. Parameters associated with mathematical models defining the choice of project to build a landfill for the purpose of deposition, whereas rates of doses can be estimated in each of the scenarios proposed. (author)

Rare-gas yields in 238U and 232Th fission by 14MeV neutrons, measured by an emanating method

International Nuclear Information System (INIS)

Feu Alvim, C.A.; Bocquet, J.P.; Brissot, R.; Crancon, J.; Moussa, A.

1977-01-01

A direct method, using emanation of rare gases by uranyle stearate and thorium stearate, has been applied to the measurement of cumulative fractional yields of certain isotopes of krypton and xenon, in the fissions of 238 U and 232 Th by 14MeV-neutrons. The independent yields of the same isotopes were measured previously by means of isotopic on-line separation. From these results, the widths of the mass and charge distributions, the relative chain yields, the fractional cumulative yields of certain bromine and iodine isotopes, the values of Zsub(p) the most probable charge, in the isobaric chains 87-93 and 137-142, and the elemental yields of krypton and xenon were calculated [fr

232Th and 238U neutron emission cross section calculations and analysis of experimental data

International Nuclear Information System (INIS)

Tel, E.

2004-01-01

In this study, pre-equilibrium neutron-emission spectra produced by (n,xn) reactions on nuclei 2 32Th and 2 38U have been calculated. Angle-integrated cross sections in neutron induced reactions on targets 2 32Th and 2 38U have been calculated at the bombarding energies up to 18 MeV. We have investigated multiple pre-equilibrium matrix element constant from internal transition for 2 32Th (n,xn) neutron emission spectra. In the calculations, the geometry dependent hybrid model and the cascade exciton model including the effects of pre-equilibrium have been used. In addition, we have described how multiple pre-equilibrium emissions can be included in the Feshbach-Kerman-Koonin (FKK) fully quantum-mechanical theory. By analyzing (n,xn) reaction on 232 T h and 2 38U, with the incident energy from 2 Me V to 18 Me V, the importance of multiple pre-equilibrium emission can be seen cleady. All calculated results have been compared with experimental data. The obtained results have been discussed and compared with the available experimental data and found agreement with each other

Compilation of criticality data involving thorium or 233U and light water moderation

Energy Technology Data Exchange (ETDEWEB)

Gore, B.F.

1978-07-01

The literature has been searched for criticality data for light water moderated systems which contain thorium or /sup 233/U, and data found are compiled herein. They are from critical experiments, extrapolations, and exponential experiments performed with homogeneous solutions and metal spheres of /sup 233/U; with lattices of fuel rods containing highly enriched /sup 235/UO/sub 2/ - ThO/sub 2/ and /sup 233/UO/sub 2/ - ThO/sub 2/; and with arrays of cyclinders of /sup 233/U solutions. The extent of existing criticality data has been compared with that necessary to implement a thorium-based fuel cycle. No experiments have been performed with any solutions containing thorium. Neither do data exist for homogeneous /sup 233/U systems with H/U < 34, except for solid metal systems. Arrays of solution cylinders up to 3 x 3 x 3 have been studied. Data for solutions containing fixed or soluble poisons are very limited. All critical lattices using /sup 233/UO/sub 2/ - ThO/sub 2/ fuels (LWBR program) were zoned radially, and in most cases axially also. Only lattice experiments using /sup 235/UO/sub 2/ - ThO/sub 2/ fuels have been performed using a single fuel rod type. Critical lattices of /sup 235/UO/sub 2/ - ThO/sub 2/ rods poisoned with boron have been measured, but only exponential experiments have been performed using boron-poisoned lattices of /sup 233/UO/sub 2/ - ThO/sub 2/ rods. No criticality data exist for denatured fuels (containing significant amounts of /sup 238/U) in either solution or lattice configurations.

Origin of the {sup 238}U-{sup 230}Th disequilibrium in magmas from subduction zones: the Arenal example; Origine du desequilibre {sup 238}U-{sup 230}TH dans les magmas des zones de subduction: exemple de l`Arenal

Energy Technology Data Exchange (ETDEWEB)

Villemant, B [Paris-6 Univ., 75 (France)

1997-12-31

The existence in some volcanic products of strong excess of {sup 238}U with respect to {sup 230}Th is one of the characteristics of volcanic arc magmas. These excesses are generally attributed to fluid additions inside mantellic sources before magma segregation, differentiation and eruption. These fluids should be linked to the dehydration of the subducted rocks. These hypotheses are essentially based on correlations between {sup 10}Be, {sup 87}Sr anomalies, Ba/La ratios and on the distribution of volcanic centers with respect to the subduction zone. Recent studies suggest an evolution of the composition of volcanic sources in Central America from a depleted mantle type (MORB) in the North (Nicaragua) to a less transformed enriched type (OIB) in the South (Costa Rica). The Arenal volcano belongs to a transition zone between these two types. The preliminary study of trace elements and {sup 238}U-{sup 230}Th disequilibria in recent volcanic products (1968-1993) indicates a more complex situation. At least two different mantle sources were successively involved characterized by different Th/La and La/Yb ratios and very different to the OIB type. Also most lavas are in equilibrium with {sup 238}U/{sup 232}Th ratios of about 1.2 to 1.3. However, in eruptive cycle, some lavas are characterized by a strong {sup 238}U excess with respect to {sup 230}Th with cannot be linked to the sources, even when modified by fluids in depth. These results are interpreted in terms of heterogeneities of mantle sources and low depths late interactions with hydrothermal fluids during eruptions. Abstract only. (J.S.). 2 refs.

Origin of the {sup 238}U-{sup 230}Th disequilibrium in magmas from subduction zones: the Arenal example; Origine du desequilibre {sup 238}U-{sup 230}TH dans les magmas des zones de subduction: exemple de l`Arenal

Energy Technology Data Exchange (ETDEWEB)

Villemant, B. [Paris-6 Univ., 75 (France)

1996-12-31

The existence in some volcanic products of strong excess of {sup 238}U with respect to {sup 230}Th is one of the characteristics of volcanic arc magmas. These excesses are generally attributed to fluid additions inside mantellic sources before magma segregation, differentiation and eruption. These fluids should be linked to the dehydration of the subducted rocks. These hypotheses are essentially based on correlations between {sup 10}Be, {sup 87}Sr anomalies, Ba/La ratios and on the distribution of volcanic centers with respect to the subduction zone. Recent studies suggest an evolution of the composition of volcanic sources in Central America from a depleted mantle type (MORB) in the North (Nicaragua) to a less transformed enriched type (OIB) in the South (Costa Rica). The Arenal volcano belongs to a transition zone between these two types. The preliminary study of trace elements and {sup 238}U-{sup 230}Th disequilibria in recent volcanic products (1968-1993) indicates a more complex situation. At least two different mantle sources were successively involved characterized by different Th/La and La/Yb ratios and very different to the OIB type. Also most lavas are in equilibrium with {sup 238}U/{sup 232}Th ratios of about 1.2 to 1.3. However, in eruptive cycle, some lavas are characterized by a strong {sup 238}U excess with respect to {sup 230}Th with cannot be linked to the sources, even when modified by fluids in depth. These results are interpreted in terms of heterogeneities of mantle sources and low depths late interactions with hydrothermal fluids during eruptions. Abstract only. (J.S.). 2 refs.

{sup 230}Th/U-dating of a late Holocene low uranium speleothem from Cuba

Energy Technology Data Exchange (ETDEWEB)

Fensterer, Claudia; Mangini, Augusta [Forschungsstelle Radiometrie, Heidelberg Academy of Sciences, Im Neuenheimer Feld 229, 69120 Heidelberg (Germany); Scholz, Denis; Hoffmann, Derik [School of Geographical Sciences, University of Bristol, University Road, BS8 1SS, Bristol (United Kingdom); Pajon, Jesus M, E-mail: Claudia.Fensterer@iup.uni-heidelberg.d [Department of Archaeology, Cuban Institute of Anthropology, Amargura No. 203, e/n Habana y Aguiar, Ciudad de La Habana, CP: 10 100 (Cuba)

2010-03-15

We present 22 U-series ages for a stalagmite from north-western Cuba based on multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and thermal ionisation mass spectrometry (TIMS). Our results reveal that the stalagmite continuously grew within the last {approx}1400a. Low uranium content of the sample and thus, extremely low {sup 230}Th concentrations limit the precision and accuracy of {sup 230}Th/U-dating by TIMS. Samples measured by MC-ICPMS show a high variability of {sup 232}Th content along the growth axis with some sections significantly affected by initial {sup 230}Th from a detrital phase. An a-priori bulk earth ratio for ({sup 238}U/{sup 232}Th) cannot be used to accurately account for this initial {sup 230}Th. Using an age model based on the {sup 230}Th/U ages determined on samples with low or negligible {sup 232}Th concentration, we find that the ({sup 238}U/{sup 232}Th) activity ratio of the detrital phase is an order of magnitude larger than the bulk earth value, indicating the importance of an accurately determined correction factor.

Calibration of 232U solution

International Nuclear Information System (INIS)

Galan Valera, M. P.; Acena Berrenechea, M. L.

1988-01-01

A method for as certain the activity by alpha spectroscopy with semiconductor detectors, of a solution of 232U is presented. It consists of the comparison with a 233U solution activity previously measured in a gridded ionization chamber of 2π geometry. The total measurement uncertainty is about + - 0,02. (Author) 9 refs

Assessment of radiological impact in mineral industrial plants caused by deposition of wastes with U{sup 238} and/or Th{sup 232} associated

Energy Technology Data Exchange (ETDEWEB)

Ladeira, Paula C.; Alves, Rex Nazare, E-mail: rexnazare@ime.eb.b [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil); Ruperti Junior, Nerbe J., E-mail: nruperti@cnen.gov.b [Comissao Nacional de Energia Nuclear (DIREJ/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Rejeitos Radioativos

2011-07-01

The industrial-mining facilities constantly produce, in Brazil and in abroad, wastes from its production, many times containing uranium and/or thorium associated. Due to the large quantities generated, these wastes are usually deposited at the site of the facility, close to the place where they were produced. Since the chains of radioactive U{sup 238} and Th{sup 232} with alpha-emitting radionuclides have long half-life, waste deposits associated with these elements may cause radiological impact on the man and on the environment, even in the long term. Mathematical models are often used to represent the biosphere and the transport of radionuclides near to the surface. Thus, it was decided, through the software {sup M}athematica{sup ,} to present a methodology based on the solution of Bateman equations for the calculation of radiological impact on individuals from the public exposed to contamination. The radiological impact appraisal was carried out considering a scenario of intrusion into landfills containing U{sup 238} and / or Th{sup 232} in post-operational phase of an industrial-mining installation. The critical group examined was represented by farmers who used water from an artesian well for daily consumption and which feed themselves on vegetables locally grown in clay soil. As a result, there was the exposure in pathways evaluated, a minor contribution of dose for ingestion of contaminated water. The conclusion of this work, show us that calculated doses were within the accepted international limits for the intrusion scenario. Parameters associated with mathematical models defining the choice of project to build a landfill for the purpose of deposition, whereas rates of doses can be estimated in each of the scenarios proposed. (author)

Determination of 233U, 235U, 238U and 239Pu fission yields induced by fission and 14.7 MeV neutrons

International Nuclear Information System (INIS)

Laurec, Jean; Adam, Albert; Bruyne, Thierry de.

1981-12-01

The 233 U, 235 U, 238 U, 239 Pu fission yields have been determined by a radiochemical method. A target and a fission chamber made of same fissible material are irradied together. The total fission number is measured from the fission chamber. The fission product activities are directly measured on the target using calibrated Ge-Li detectors. The fissible material masses are determined by alpha and mass spectrometries. The irradiations were made on the critical assemblies PROSPERO and CALIBAN and on the 14 MeV neutron generator of C.E. VALDUC. 3 to 5% fission yield errors are got for the most measured nuclides: 95 Zr, 97 Zr, 99 Mo, 103 Ru, 131 I, 132 Te, 140 Ba, 141 Ce, 143 Ce, 144 Ce, 147 Nd [fr

Production of 232,233Pa in 6Li+232Th Collisions in the Classical Trajectory Approach

International Nuclear Information System (INIS)

Aleshin, V.P.

2000-01-01

The semiclassical model of nuclear reactions with loosely bound projectiles (V.P. Aleshin, B.I. Sidorenko, Acta Phys. Pol. B29, 325 (1998)) is refined and compared with experimental data of Rama Rao et al. on the excitation function for the production of 232,233 Pa in 6 Li+ 232 Th collisions at E = 30-50 MeV. The main contribution to the production of 232 Pa is the 2 neutron emission from excited states of 234 Pa formed in the ( 6 Li,α) reaction. The main source of 233 Pa is the ( 6 Li,αp) reaction followed by γ transitions from excited states of 233 Th to 233 Th (g.s.) which transforms to 233 Pa through β - decay. The ground state of 6 Li regarded as a combination of n+p+α is modeled with the K=2, l x =l y =0 hyperspherical function. The calculation underpredicts the excitation function of 232 Pa by a factor of 0.6 and overpredicts the excitation function of 233 Pa by a factor of 2.3, on the average. With the more realistic wave function of 6 Li both factors are expected to be closer to 1. (author)

230Th/238U and 226Ra/230Th fractionation in young basaltic glasses from the East Pacific Rise

International Nuclear Information System (INIS)

Reinitz, I.; Turekian, K.K.

1989-01-01

Mid-ocean ridge basalt (MORB) glasses treated to remove manganese and iron oxyhydroxide coatings containing U and Th decay chain nuclides sequestered from the ambient aqueous environment show little fractionation of ( 230 Th) from ( 238 U), but extensive enrichment of ( 226 Ra) over ( 230 Th). Chronometry based on ( 230 Th)-( 238 U) disequilibrium yields a mean age of 151,000 ± 55,000 (2σ) years ago for Th-U fractionation, from a source region with Th/U (atom ratio) = 1.58 ± 0.43 (2σ). ( 226 Ra) excesses over ( 230 Th) indicate an enrichment event more recent than the fractionation of Th from U. ( 226 Ra/ 230 Th) correlates well with K/U, providing a rough means of estimating the age since eruption of MORB glasses. (orig.)

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

Measurements of 234U, 238U and 230Th in excreta of uranium-mill crushermen

International Nuclear Information System (INIS)

Fisher, D.R.; Jackson, P.O.; Brodacynski, G.G.; Scherpelz, R.I.

1982-07-01

Uranium and thorium levels in excreta of uranium mill crushermen who are routinely exposed to airborne uranium ore dust were measured. The purpose was to determine whether 230 Th was preferentially retained over either 234 U or 238 U in the body. Urine and fecal samples were obtained from fourteen active crushermen with long histories of exposure to uranium ore dust, plus four retired crushermen and three control individuals for comparison. Radiochemical procedures were used to separate out the uranium and thorium fractions, which were then electroplated on stainless steel discs and assayed by alpha spectrometry. Significantly greater activity levels of 234 U and 238 U were measured in both urine and fecal samples obtained from uranium mill crushermen, indicating that uranium in the inhaled ore dust was cleared from the body with a shorter biological half-time than the daughter product 230 Th. The measurements also indicated that uranium and thorium separate in vivo and have distinctly different metabolic pathways and transfer rates in the body. The appropriateness of current ICRP retention and clearance parameters for 230 Th in ore dust is questioned

Direct Measurement of Initial 230TH/ 232TH Ratios in Central Texas Speleothems for More Accurate Age Determination

Science.gov (United States)

Wortham, B. E.; Banner, J. L.; James, E.; Loewy, S. L.

2013-12-01

Speleothems, calcite deposits in caves, preserve a record of climate in their growth rate, isotope ratios and trace element concentrations. These variables must be tied to precise ages to produce pre-instrumental records of climate. The 238U-234U- 230Th disequilibrium method of dating can yield precise ages if the amount of 230Th from the decay of radiogenic 238U can be constrained. 230Th in a speleothem calcite growth layer has two potential sources - 1) decay of radioactive 238U since the time of growth of the calcite layer; and 2) initial detrital 230Th, incorporated along with detrital 232Th, into the calcite layer at the time it grew. Although the calcite lattice does not typically incorporate Th, samples can contain impurities with relatively high Th contents. Initial 230Th/232Th is commonly estimated by assuming a source with bulk-Earth U/Th values in a state of secular equilibrium in the 238U-decay chain. The uncertainty in this 230Th/232Th estimate is also assumed, typically at +/-100%. Both assumptions contribute to uncertainty in ages determined for young speleothems. If the amount of initial detrital 230Th can be better quantified for samples or sites, then U-series ages will have smaller uncertainties and more precisely define the time series of climate proxies. This study determined the initial 230Th/232Th of modern calcite to provide more precise dates for central Texas speleothems. Calcite was grown on glass-plate substrates placed under active drips in central Texas caves. The 230Th/232Th of this modern calcite was determined using thermal ionization mass spectrometry. Results show that: 1) initial 230Th/232Th ratios can be accurately determined in these young samples and 2) measuring 230Th/232Th reduces the uncertainties in previously-determined ages on stalagmites from under the same drips. For example, measured initial 230Th/232Th in calcite collected on substrates from different locations in the cave at Westcave Preserve are 15.3 × 0.67 ppm

Application of activation technique for mass and nuclear charge distributions studies of 3 Mev and 14 Mev neutrons induced 238-U(n,f) and 232-Th(n,f)

International Nuclear Information System (INIS)

Embarch, K.

1988-01-01

Fission product cumulative and independent yields were determined for 238-U(n,f) and 232-Th(n,f) reactions with essentially monoenergetic neutrons of 3 and 14 Mev. Fission product activities were measured by Ge(Li)γ-ray spectrometry of irradiated 238-U and 232-Th foils. These experiments allowed us to measure a great number of cumulative yields and to obtain the fission product mass distributions corresponding to the studied reactions mentioned above. The mass distributions were completely interpreted by nucleon shell effects and proton even-odd effects. The independent yield measurements are sometimes not possible using the activation technique because of the fission fragment decay data. The values which can not be measured were determined using the measured mass yields and a prediction systematic of fractional independent yield. The results allowed us to obtain the nuclear charge distributions and to estimate proton even-odd effect corresponding values. This effect decreases when the excitation energy of the fissioning nucleus increases, this shows the importance of this parameter in the viscosity study of the nuclear matter. In conclusion, the shell effects observed in the mass distributions show that the static aspect of the fission mechanism plays a great role during the fission process, and observed proton even-odd effects act for a weak nuclear viscosity. 54 refs., 27 figs., 25 tabs

230Th-238U disequilibrium and the melting processes beneath ridge axes

International Nuclear Information System (INIS)

McKenzie, D.

1985-01-01

The activity ratio ( 230 Th/ 238 U) is calculated for a simple model of melting, for which the melt fraction in chemical and radioactive equilibrium with the solid residium remains constant as melting proceeds. The activity ratio in the melt is only significantly different from unity if the melting is slow compared with the half-life of 230 Th and if the melt fraction present at any time does not exceed a few percent. The observation that ( 230 Th/ 238 U) is about 1.25 for many ocean ridge basalts is therefore most easily explained if the melt fraction in the source region is less than 2% and if the melting occurs in a broad region more than 100 km wide beneath the ridge axis. These results are compatible with other geophysical observations. Measurements of ( 226 Ra/ 238 U) might provide useful constraints on the time required to reach chemical equilibrium between the melt and the matrix. (orig.)

Limitations on the precision of 238U/235U measurements and implications for environmental monitoring

International Nuclear Information System (INIS)

Russ III, G.P.

1997-01-01

The ability to determine the isotopic composition of uranium in environmental samples is an important component of the International Atomic Energy Agency's (IAEA) safeguards program, and variations in the isotopic ratio 238 U/ 235 U provide the most direct evidence of isotopic enrichment activities. The interpretation of observed variations in 238 U/ 235 U depends on the ability to distinguish enrichment from instrumental biases and any variations occurring in the environment but not related to enrichment activities. Instrumental biases that have historically limited the accuracy of 238 U/ 235 U determinations can be eliminated by the use of the 233 U/ 236 U double-spike technique. With this technique, it is possible to determine the 238 U/ 235 U in samples to an accuracy equal to the precision of the measurement, ca. 0.1% for a few 10's of nanograms of uranium. Given an accurate determination of 238 U/ 235 U, positive identification of enrichment activities depends on the observed value being outside the range of 238 U/ 235 U's expected as a result of natural or environmental variations. Analyses of a suite of soil samples showed no variation beyond 0.2% in 238 U/ 235 U

Evaluation of fission cross sections and covariances for {sup 233}U, {sup 235}U, {sup 238}U, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu

Energy Technology Data Exchange (ETDEWEB)

Kawano, Toshihiko [Kyushu Univ., Fukuoka (Japan); Matsunobu, Hiroyuki [Data Engineering, Inc. (Japan); Murata, Toru [AITEL Corporation, Tokyo (JP)] [and others

2000-02-01

A simultaneous evaluation code SOK (Simultaneous evaluation on KALMAN) has been developed, which is a least-squares fitting program to absolute and relative measurements. The SOK code was employed to evaluate the fission cross sections of {sup 233}U, {sup 235}U, {sup 238}U, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu for the evaluated nuclear data library JENDL-3.3. Procedures of the simultaneous evaluation and the experimental database of the fission cross sections are described. The fission cross sections obtained were compared with evaluated values given in JENDL-3.2 and ENDF/B-VI. (author)

Mass-yield distributions of fission products from 20, 32, and 45 MeV proton-induced fission of 232Th

Science.gov (United States)

Naik, H.; Goswami, A.; Kim, G. N.; Kim, K.; Suryanarayana, S. V.

2013-10-01

The yields of various fission products in the 19.6, 32.2, and 44.8 MeV proton-induced fission of 232Th have been determined by recoil catcher and an off-line γ-ray spectrometric technique using the BARC-TIFR Pelletron in India and MC-50 cyclotron in Korea. The mass-yield distributions were obtained from the fission product yield using the charge distribution corrections. The peak-to-valley (P/V) ratio of the present work and that of literature data for 232Th(p,f) and 238U(p,f) were obtained from the mass yield distribution. The present and the existing literature data for 232Th(p,f), 232Th(n,f), and 232Th( γ,f) at various energies were compared with those for 238U(p,f), 238U(n,f), and 238U( γ,f) to examine the probable nuclear structure effect. The role of Th-anomaly on the peak-to-valley ratio in proton-, neutron-, and photon-induced fission of 232Th was discussed with the similar data in 238U. On the other hand, the fine structure in the mass yield distributions of the fissioning systems at various excitation energies has been explained from the point of standard I and II asymmetric mode of fission besides the probable role of even-odd effect, A/ Z ratio, and fissility parameter.

Tracing changes in mantle and crustal influences in individual cone-building stages at Mt. Shasta using U-Th and Sr isotopes

Science.gov (United States)

Wende, Allison M.; Johnson, Clark M.; Beard, Brian L.

2015-10-01

230Th-excess is rare in most arc lavas, but common in the Cascades, yet the origin of such excesses remains unclear. At Mt. Shasta, age-corrected (230Th/232Th) and (238U/232Th) activity ratios range from 1.108 to 1.290 and from 0.987 to 1.309 (27.3% 230Th-excess to 6.1% 238U-excess), respectively. Although small degrees of zircon crystallization (ancestral cone (Sand Flat) was followed by four cone-building stages, three of which lie in the age range of U-series geochronology. Lavas within individual eruptive stages have relatively constant (230Th/232Th)0 ratios that are interpreted to reflect specific mixtures of mantle (m) and lower crustal (lc) melts that are characteristic of a specific stage (Mm:lc). High (230Th/232Th)0 ratios identify higher proportions of lower crust in the Misery Hill stage (Mm:lc = ∼ 85 : 15), whereas low (230Th/232Th)0 ratios reflect the more mantle-like composition of the Shastina lavas (Mm:lc = ∼ 95 : 5); in the case of Shastina lavas, very low 87Sr/86Sr ratios, down to 0.7029, support a substantial mantle contribution. Changes in (230Th/232Th)0 ratios correlate with eruptive volume, where the most voluminous stage (Misery Hill) is inferred to have the largest proportion of crustal melt and highest (230Th/232Th)0 ratios. Variable (230Th/238U)0 ratios within, and between, eruptive groups likely reflect a combination of residence time in the lower crust and differential assimilation of bulk, non-garnet-bearing crust that had (230Th/238U) = 1. The volume-(230Th/232Th)0 relations are accompanied by correlations with 87Sr/86Sr ratios, where the most radiogenic Sr is associated with the largest eruptive volumes, indicating that the largest magmatic episodes produced the largest amount of lower crustal interaction. The new U-Th and Sr isotope measurements of this study, along with U-series data for other Cascade centers suggest that interaction with the lower crust exerts greater control on Cascade magma chemistry than previously

238U + n resolved resonance energies

International Nuclear Information System (INIS)

Olsen, D.K.; de Saussure, G.; Perez, R.B.; Difilippo, F.C.; Ingle, R.W.

1978-01-01

Neutron transmission measurements from 100 eV to 170 keV at 150 m through four 238 U samples are reported. The energy calibration is described, and the resultant 233 U resolved resonance energies are found to be intermediate between those from other workers. In addition, some energies for sharp resonances in 23 Na, 27 Al, 32 S, and 206 Pb are given

Measurements of prompt fission neutron spectra and double-differential neutron inelastic-scattering cross sections for 238U and 232Th

International Nuclear Information System (INIS)

Baba, Mamoru; Itoh, Nobuo; Maeda, Kazuto; Hirakawa, Naohiro; Wakabayashi, Hidetaka.

1989-10-01

This report presents the summary of experimental studies of prompt fission neutron spectra and double-differential neutron inelastic-scattering cross sections of 238 U and 232 Th. The experiments were performed at Tohoku University Fast Neutron Laboratory employing a time-of-flight technique and Dynamitron accelerator as the pulsed neutron generator. From the experiments, we obtained the following data for both nuclei; 1. prompt fission neutron spectrum for 2 MeV neutrons, 2. double-differential neutron inelastic-scattering cross sections for 1.2, 2.0, 4.2, 6.1 and 14.1 MeV incident neutrons. Both in experiments and data processing, cares were taken to obtain reliable data by avoiding systematic uncertainty. The experimental data were compared with those by other experiments, evaluations and model calculations. Through the data comparison, some fundamental problems were found in the experiments by previous authors and the evaluations. The present data will provide useful data base for refinement of the evaluated data and theoretical models. (author)

Reply to Comment on "Zircon U-Th-Pb dating using LA-ICP-MS: Simultaneous U-Pb and U-Th dating on the 0.1 Ma Toya Tephra, Japan"

Science.gov (United States)

Ito, Hisatoshi

2015-04-01

Guillong et al. (2015) mentioned that corrections for abundance sensitivity for 232Th and molecular zirconium sesquioxide ions (Zr2O3+) are critical for reliable determination of 230Th abundances in zircon for LA-ICP-MS analyses. There is no denying that more rigorous treatments are necessary to obtain more reliable ages than those in Ito (2014). However, as shown in Fig. 2 in Guillong et al. (2015), the uncorrected (230Th)/(238U) for reference zircons except for Mud Tank are only 5-20% higher than unity. Since U abundance of Toya Tephra zircons that have U-Pb ages Ito (2014) obtained U-Th ages of the Toya Tephra by comparison with Fish Canyon Tuff (FCT) data. Because both the FCT and the Toya Tephra have similar trends of overestimation of 230Th, the effect of overestimation of 230Th to cause overestimation of U-Th age should be cancelled out or negligible. Therefore the pivotal conclusion in Ito (2014) that simultaneous U-Pb and U-Th dating using LA-ICP-MS is possible and useful for Quaternary zircons holds true.

Neutron-induced reactions on U and Th - A new approach via AMS

International Nuclear Information System (INIS)

Wallner, A.; Capote, R.; Christl, M.; Fifield, L.K.; Srncik, M.; Tims, S.; Hotchkis, M.; Krasa, A.; Lachner, J.; Lippold, J.; Plompen, A.; Semkova, V.; Steier, P.; Winkler, S.

2014-01-01

Recent studies exhibit discrepancies at keV and MeV energies between major nuclear data libraries for 238 U(n,γ), 232 Th(n,γ) and also for (n,xn) reactions. We have extended our initial (n,γ) measurements on 235,238 U to higher neutron energies and to additional reaction channels. Neutron-induced reactions on 232 Th and 238 U were measured by a combination of the activation technique and atom counting of the reaction products using accelerator mass spectrometry (AMS). Natural thorium and uranium samples were activated with quasi-monoenergetic neutrons at IRMM. Neutron capture data were produced for neutron energies between 0.5 and 5 MeV. Fast neutron-induced reactions were studied in the energy range from 17 to 22 MeV. Preliminary data indicate a fair agreement with data libraries; however at the lower band of existing data. This approach represents a complementary method to on-line particle detection techniques and also to conventional decay counting. (authors)

Measurement of the cross sections for the 238U(n,2n) and 232Th(n,2n) reactions in the 13.5 - 14.8 MeV energy range

International Nuclear Information System (INIS)

Raics, P.; Nagy, S.; Daroczy, S.; Kornilov, N.V.

1990-10-01

(n,2n) reaction cross sections have been determined for 238 U and 232 Th by using the activation method. Neutrons were produced in D-T reaction by bombarding a TiT target with analyzed deuteron beam from a Cockcroft-Walton accelerator. Neutron energy was varied by changing the emission angle to the deuteron beam. The activities of the 237 U and 231 Th residual nuclei were measured by a Ge(Li) and a HP Ge gamma-spectrometer, respectively. Several standard reactions were used for the determination of the neutron flux density. An overall precision of 3.5 - 4.5% was estimated and a 1.4 - 3.5% reproducibility was achieved. Comparison of the recent results to literature data and a brief analysis of the monitor reactions are given. (author). 48 refs, 3 figs, 7 tabs

A comparison on determining activities of 238U and 232Th based on transfer samples and some associations of ideas for some investigation passed of environment radiation

International Nuclear Information System (INIS)

Su Qiong; Cheng Jianping; Diao Lijun; Li Guiqun

2006-01-01

A comparison on determining activities of 238 U and 232 Th based on transfer samples is reported in the paper. Especially, disturbance of X-ray from out-sources i.e. non-nucleus-self are studied and more detailed. And other factors that influence this time comparison result are discussed too in the work. In the paper it is pointed out definitely that the characteristic peaks that are disturbed by characteristic X-rays from out-sources ought to be not adopted to determine activities of the samples. In final some associations of ideas for some investigation passed of environment radiation are also described. (authors)

A comparison on determining activities of 238U and 232Th based on transfer samples and some associations of ideas for some investigation passed of environment radiation

International Nuclear Information System (INIS)

Su Qiong; Cheng Jianping; Diao Lijun; Li Guiqun

2007-01-01

A comparison on determining activities of 238 U and 232 Th based on transfer samples is reported in the paper. Especially, disturbance of X-ray from out-sources i.e. non-nucleus-self are studied and more detailed. And other factors that influence this time comparison result are discussed too in the work. In the paper it is pointed out definitely that the characteristic peaks that are disturbed by characteristic X-rays from out-sources ought to be not adopted to determine activities of the samples. In final some associations of ideas for some investigation passed of environment radiation are also described. (authors)

Neutron scattering cross sections for 232Th and 238U inferred from proton scattering and charge exchange measurements

International Nuclear Information System (INIS)

Hansen, L.F.; Grimes, S.M.; Pohl, B.A.; Poppe, C.H.; Wong, C.

1980-01-01

Differential cross sections for the (p,n) reactions to the isobaric analog states (IAS) of 232 Th and 238 U targets were measured at 26 and 27 MeV. The analysis of the data was done in conjunction with the proton elastic and inelastic (2 + , 4 + , 6 + ) differential cross sections measured at 26 MeV. Because collective effects are important in this mass region, deformed coupled-channels calculations were carried out for the simultaneous analysis of the proton and neutron outgoing channels. The sensitivity of the calculations was studied with respect to the optical model parameters used in the calculations, the shape of the nuclear charge distribution, the type of coupling scheme assumed among the levels, the magnitude of the deformation parameters, and the magnitude of the isovector potentials, V 1 and W 1 . A Lane model-consistent analysis of the data was used to infer optical potential parameters for 6- to 7-MeV neutrons. The neutron elastic differential cross sections obtained from these calculations are compared with measurements available in the literature, and with results obtained using neutron parameters from global sets reported at these energies. 7 figures, 3 tables

A study on physical characteristics of supercritical light - water reactor loaded with (232U-238Th-238U) oxide fuel

International Nuclear Information System (INIS)

Kulikov, E. G.; Shmelev, A. N.; Apse, V. A.; Kulikov, G. G.

2007-01-01

The attractiveness of using (U-Th)-fuel in supercritical light water reactor is considered. The dilution of 2 33U in 2 38U is proposed with the purpose of increasing non-proliferation of this fissile isotope. Comparison of different fuel compositions is accomplished from the point of view of fissile isotope breeding and achieved burn-up; parasitic neutron absorption cross-sections are also compared. It is analyzed the impact for neutron balance of both cladding materials: zirconium alloy and stainless steel

Neutron induced fission cross section ratios for 232Th, 235,238U, 237Np and 239Pu from 1 to 400 MeV

International Nuclear Information System (INIS)

Lisowski, P.W.; Ullmann, J.L.; Balestrini, S.J.; Carlson, A.D.; Wasson, O.A.; Hill, N.W.

1988-01-01

Time-of-flight measurements of neutron induced fission cross section ratios for 232 Th, 235,238 U, 237 Np, and 239 Pu, were performed using the WNR high intensity spallation neutron source located at Los Alamos National Laboratory. A multiple-plate gas ionization chamber located at a 20-m flight path was used to simultaneously measure the fission rate for all samples over the energy range from 1 to 400 MeV. Because the measurements were made with nearly identical neutron fluxes, we were able to cancel many systematic uncertainties present in previous measurements. This allows us to resolve discrepancies among different data sets. In addition, these are the first neutron-induced fission cross section values for most of the nuclei at energies above 30 MeV. (author)

EFFECTIVE SPECIFIC ACTIVITY OF NATURAL RADIONUCLIDES FOR THE NORM BELONGED TO 238U AND 232TH SERIES BEING IN THE STATE OF DISTURBED RADIOACTIVE EQUILIBRIUM

Directory of Open Access Journals (Sweden)

I. P. Stamat

2008-01-01

Full Text Available In the Sanitary Rules SR 2.6.1.1292-03 and SR 2.6.6.1169-02 classification of the industrial waste containing naturally occurring radioactive materials is adopted in accordance to the values of their effective specific activity Aeff. In a case of the disturbed equilibrium in 238U and 232Th series it is necessary to take into consideration actual contribution of the separate natural radionuclides of the mentioned series into the value of gamma dose rate of the waste. This will permit to avoid unjustified overestimating or understating of the waste category which prevents as unjustified expenditures on their treating so undertaking of the necessary measures providing radiation safety.

Void reactivity feedback analysis for U-based and Th-based LWR incineration cycles

Energy Technology Data Exchange (ETDEWEB)

Lindley, B.A.; Parks, G.T. [Cambridge University Engineering Department, Trumpington Street, Cambridge, CB2 1PZ (United Kingdom); Franceschini, F. [Westinghouse Electric Company LLC, Cranberry Township, PA (United States)

2013-07-01

In reduced-moderation LWRs, an external supply of transuranic (TRU) can be incinerated by mixing it with a fertile isotope ({sup 238}U or {sup 232}Th) and recycling all the actinides after each cycle. Performance is limited by coolant reactivity feedback - the moderator density coefficient (MDC) must be kept negative. The MDC is worse when more TRU is loaded, but TRU feed is also needed to maintain criticality. To assess the performance of this fuel cycle in different neutron spectra, three LWRs are considered: 'reference' PWRs and reduced-moderation PWRs and BWRs. The MDC of the equilibrium cycle is analysed by reactivity decomposition with perturbed coolant density by isotope and neutron energy. The results show that using {sup 232}Th as a fertile isotope yields superior performance to {sup 238}U. This is due essentially to the high resonance η of U bred from Th (U3), which increases the fissility of the U3-TRU isotope vector in the Th-fueled system relative to the U-fueled system, and also improves the MDC in a sufficiently hard spectrum. Spatial separation of TRU and U3 in the Th-fueled system renders further improvement by hardening the neutron spectrum in the TRU and softening it in the U3. This improves the TRU η and increases the negative MDC contribution from reduced thermal fission in U3. (authors)

Mass-yield distributions of fission products from 20, 32, and 45 MeV proton-induced fission of {sup 232}Th

Energy Technology Data Exchange (ETDEWEB)

Naik, H.; Goswami, A. [Bhabha Atomic Research Centre, Radiochemistry Division, Mumbai (India); Kim, G.N.; Kim, K. [Kyungpook National University, Department of Physics, Daegu (Korea, Republic of); Suryanarayana, S.V. [Bhabha Atomic Research Centre, Nuclear Physics Division, Mumbai (India)

2013-10-15

The yields of various fission products in the 19.6, 32.2, and 44.8 MeV proton-induced fission of {sup 232}Th have been determined by recoil catcher and an off-line {gamma}-ray spectrometric technique using the BARC-TIFR Pelletron in India and MC-50 cyclotron in Korea. The mass-yield distributions were obtained from the fission product yield using the charge distribution corrections. The peak-to-valley (P/V) ratio of the present work and that of literature data for {sup 232}Th(p,f) and {sup 238}U(p,f) were obtained from the mass yield distribution. The present and the existing literature data for {sup 232}Th(p,f), {sup 232}Th(n,f), and {sup 232}Th({gamma},f) at various energies were compared with those for {sup 238}U(p,f), {sup 238}U(n,f), and {sup 238}U({gamma},f) to examine the probable nuclear structure effect. The role of Th-anomaly on the peak-to-valley ratio in proton-, neutron-, and photon-induced fission of {sup 232}Th was discussed with the similar data in {sup 238}U. On the other hand, the fine structure in the mass yield distributions of the fissioning systems at various excitation energies has been explained from the point of standard I and II asymmetric mode of fission besides the probable role of even-odd effect, A/Z ratio, and fissility parameter. (orig.)

Within the framework of the new fuel cycle 232Th/233U, determination of the 233Pa(n.γ) radiative capture cross section for neutron energies ranging between 0 and 1 MeV

International Nuclear Information System (INIS)

Boyer, S.

2004-10-01

The Thorium cycle Th 232 /U 233 may face brilliant perspectives through advanced concepts like molten salt reactors or accelerator driven systems but it lacks accurate nuclear data concerning some nuclei. Pa 233 is one of these nuclei, its high activity makes the direct measurement of its radiative neutron capture cross-section almost impossible. This difficulty has been evaded by considering the transfer reaction Th 232 (He 3 ,p)Pa 234 * in which the Pa 234 nucleus is produced in various excited states according to the amount of energy available in the reaction. The first chapter deals with the thorium cycle and its assets to contribute to the quenching of the fast growing world energy demand. The second chapter gives a detailed description of the experimental setting. A scintillation detector based on deuterated benzene (C 6 D 6 ) has been used to counter gamma ray cascades. The third chapter is dedicated to data analysis. In the last chapter we compare our experimental results with ENDF and JENDL data and with computed values from 2 statistical models in the 0-1 MeV neutron energy range. Our results disagree clearly with evaluated data: our values are always above ENDF and JENDL data but tend to near computed values. We have also perform the measurement of the radiative neutron cross-section of Pa 231 for a 110 keV neutron: σ(n,γ) 2.00 ± 0.14 barn. (A.C.)

Extreme fractionation of 234U 238U and 230Th 234U in spring waters, sediments, and fossils at the Pomme de Terre Valley, southwestern Missouri

Science.gov (United States)

Szabo, B. J.

1982-01-01

Isotopic fractionation as great as 1600% exists between 234U and 238U in spring waters, sediments, and fossils in the Pomme de Terre Valley, southwestern Missouri. The activity ratios of 234U 238U in five springs range from 7.2 to 16 in water which has been discharged for at least the past 30,000 years. The anomalies in 234U 238U ratio in deep water have potential usefulness in hydrologic investigations in southern Missouri. Clayey units overlying the spring bog sediments of Trolinger Spring are enriched in 230Th relative to their parent 234U by as much as 720%. The results indicate that both preferential displacement via alpha recoil ejection and the preferential emplacement via recoiling and physical entrapment are significant processes that are occurring in the geologic environment. ?? 1982.

Characterization of {sup 238}U, {sup 232}Th, {sup 40}K, and {sup 226}Ra in NORM and Air Particulate Occurring from Phosphate Processing Facility

Energy Technology Data Exchange (ETDEWEB)

Jung, Yoon Hee; Lim, Jong Myoung; Ji, Young Yong; Kim, Hyun Cheol; Kim, Chang Jong; Park, Ji Yong; Chung, Kun Ho; Kang, Mun Ja [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In this study, radio-activities of {sup 238}U, {sup 232}Th, {sup 40}K, and {sup 226}Ra occurring in raw materials and by-products at phosphate processing facility were complementally determined using ED-XRF, γ-spectrometry and ICP-MS method. Although the degree of immersion in the human body varies depending on the particle size and density, the particle size is especially used as a key factor in assessing dose. Thus, size distribution characteristics of {sup 238}U concentrations in airborne particulates collected at the phosphate processing facility were also evaluated. The naturally occurring radioactive materials (NORM) are widely spread throughout the environment, it occupies the largest part of public radioactivity exposure. According to report of the US National Academy of Sciences, 82% of the human radiation dose received annually comes from the natural radionuclides. Radiation exposure doses from natural radionuclides is not significantly concerned level compared to those from artificial radionuclides which could be released into the environment by nuclear tests and power plant accident. It could make a serious risk problem to unspecific public when exposed to the natural radionuclides during long-term period at high activity concentration levels. Therefore, it is essential to make a professional and systematic approach for the proper handling and diminution.

A preliminary simulation of an ADS using MCNPX for U233 production

International Nuclear Information System (INIS)

Barros, Graiciany P.; Pereira, Claubia; Veloso, Maria A.F.; Costa, Antonella L.

2009-01-01

The code MCNPX is used to evaluate a simplified model of a hybrid system regenerator accelerator (ADS - Accelerator Driven Subcritical), for energy and 233 U production. The concept consists of coupling a high-energy particle accelerator with a sub-critical reactor core, using 232 ThO 2 + 233 UO 2 as initial composition. In this work, the spallation source definition used in MCNPX is a point source of 1000 MeV. The system consists in three coaxial cylinders. The internal cylinder is the spallation target that is a thick natural Pb. The intermediate cylinder is the core, composed by the mixture of fuel ( 232 ThO 2 + 9.5% 233 UO 2 ) and Pb coolant; and lead, as reflector, composes the external cylinder. The goal is to begin studies to evaluate the regenerator blanket composition when submitted to a neutron flux during a time step. The effective multiplication coefficient of the system and the variation of the composition of the regenerative layer are analyzed. The preliminary results show the possibility of utilization of this system. (author)

Comment on "Zircon U-Th-Pb dating using LA-ICP-MS: Simultaneous U-Pb and U-Th dating on 0.1 Ma Toya Tephra, Japan" by Hisatoshi Ito

Science.gov (United States)

Guillong, M.; Schmitt, A. K.; Bachmann, O.

2015-04-01

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of eight zircon reference materials and synthetic zircon-hafnon end-members indicate that corrections for abundance sensitivity and molecular zirconium sesquioxide ions (Zr2O3+) are critical for reliable determination of 230Th abundances in zircon. Other polyatomic interferences in the mass range 223-233 amu are insignificant. When corrected for abundance sensitivity and interferences, activity ratios of (230Th)/(238U) for the zircon reference materials we used average 1.001 ± 0.010 (1σ error; mean square of weighted deviates MSWD = 1.45; n = 8). This includes the 91500 and Plešovice zircons, which were deemed unsuitable for calibration of (230Th)/(238U) by Ito (2014). Uranium series zircon ages generated by LA-ICP-MS without mitigating (e.g., by high mass resolution) or correcting for abundance sensitivity and molecular interferences on 230Th such as those presented by Ito (2014) are potentially unreliable.

Neutron induced fission cross section ratios for 232Th, /sup 235,238/U, 237Np, and 239Pu from 1 to 400 MeV

International Nuclear Information System (INIS)

Lisowski, P.W.; Ullmann, J.L.; Balestrini, S.J.; Carlson, A.D.; Wasson, O.A.; Hill, N.W.

1988-01-01

Time-of-flight measurements of neutron induced fission cross section ratios for 232 Th, /sup 235,238/U, 237 Np, and 239 Pu, were performed using the WNR high intensity spallation neutron source located at Los Alamos National Laboratory. A multiple-plate gas ionization chamber located at a 20-m flight path was used to simultaneously measure the fission rate for all samples over the energy range from 1 to 400 MeV. Because the measurements were made with nearly identical neutron fluxes, we were able to cancel many systematic uncertainties present in previous measurements. This allows us to resolve discrepancies among different data sets. In addition, these are the first neutron-induced fission cross section values for most of the nuclei at energies above 30 MeV. 8 refs., 3 figs

234Th/238U disequilibrium in near-shore sediment: particle reworking and diagenetic time scales

International Nuclear Information System (INIS)

Aller, R.C.; Cochran, J.K.

1976-01-01

The distribution of 234 Th (tsub(1.2)=24.1 days) in excess of its parent 238 U in the upper layers of near-shore sediment makes possible the evaluation of short-term sediment reworking and diagenetic rates. 234 Th has a maximum residence time in Long Island Sound water of 1.4 days. Seasonal measurement of 234 Th/ 238 U disequilibrium in sediment at a single station in central Long Island Sound demonstrates rapid particle reworking and high 234 Thsub(XS)(>1 dpm/g) in the upper 4 cm of sediment with slower, irregular reworking and low 234 Thsub(XS) to at least 12 cm. The rate of rapid particle reworking varies seasonally and is highest in the fall. The rapidly mixed zone is characterized by steep gradients in sediment chemistry implying fast reactions spanned by 234 Th decay time scales. 238 U is depleted in the upper mixed zone and shows addition in reducing sediment at depth. (Auth.)

Determination of the extraction efficiency for {sup 233}U source α-recoil ions from the MLL buffer-gas stopping cell

Energy Technology Data Exchange (ETDEWEB)

Wense, Lars v.d.; Seiferle, Benedict; Thirolf, Peter G. [Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Laatiaoui, Mustapha [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Helmholtz Institut Mainz, Mainz (Germany)

2015-03-01

Following the α decay of {sup 233}U, {sup 229}Th recoil ions are shown to be extracted in a significant amount from the MLL buffer-gas stopping cell. The produced recoil ions and subsequent daughter nuclei are mass purified with the help of a customized quadrupole mass spectrometer. The combined extraction and mass purification efficiency for {sup 229}Th{sup 3+} is determined via MCP-based measurements and via the direct detection of the {sup 229}Th α decay. A large value of (10±2)% for the combined extraction and mass purification efficiency of {sup 229}Th{sup 3+} is obtained at a mass resolution of about 1u/e. In addition to {sup 229}Th, also other α-recoil ions of the {sup 233,} {sup 232}U decay chains are addressed. (orig.)

Monte Carlo analyses of simple U233 O2-ThO2 and U235 O2-ThO2 lattices with ENDF/B-IV data (AWBA development program)

International Nuclear Information System (INIS)

Hardy, J. Jr.; Ullo, J.J.

1980-09-01

A number of water-moderated Th-U235 and Th-U233 lattice integral experiments were analyzed in a consistent manner, with ENDF/B-IV data and detailed Monte Carlo methods. These experiments provide a consistent test of the nuclear data. The ENDF/B-IV data are found to perform reasonably well. Adequate agreement is found with integral measurements of thorium capture. Calculated K/sub eff/ values show a generally coherent pattern which is consistent with K/sub eff/ results obtained for homogeneous aqueous critical assemblies. Harder prompt fission spectra for U233 and U235 can correct the principal discrepancy observed with ENDF/B-IV, a bias trend in K/sub eff/ attributed to an underprediction of leakage

Contribution to the study of {sup 233}U production with MOX-ThPu fuel in PWR reactor. Transition scenarios towards Th/{sup 233}U iso-generating concepts in thermal spectrum. Development of the MURE fuel evolution code; Contribution a l'etude de la production d'{sup 233}U en combustible MOX-ThPu en reacteur a eau sous pression. Scenarios de transition vers des concepts isogenerateurs Th/{sup 233}U en spectre thermique. Developpement du code MURE d'evolution du combustible

Energy Technology Data Exchange (ETDEWEB)

Michel-Sendis, F

2006-12-15

If nuclear power is to provide a significant fraction of the growing world energy demand, only through the breeding concept can the development of sustainable nuclear energy become a reality. The study of such a transition, from present-day nuclear technologies to future breeding concepts is therefore pertinent. Among these future concepts, those using the thorium cycle Th/U-233 in a thermal neutron spectrum are of particular interest; molten-salt type thermal reactors would allow for breeding while requiring comparatively low initial inventories of U-233. The upstream production of U-233 can be obtained through the use of thorium-plutonium mixed oxide fuel in present-day light water reactors. This work presents, firstly, the development of the MURE evolution code system, a C++ object-oriented code that allows the study, through Monte Carlo (M.C.) simulation, of nuclear reactors and the evolution of their fuel under neutron irradiation. The M.C. methods are well-suited for the study of any reactor, whether it'd be an existing reactor using a new kind of fuel or a future concept altogether, the simulation is only dependent on nuclear data. Exact and complex geometries can be simulated and continuous energy particle transport is performed. MURE is an interface with MCNP, the well-known and validated transport code, that allows, among other functionalities, to simulate constant power and constant reactivity evolutions. Secondly, the study of MOX ThPu fuel in a conventional light water reactor (REP) is presented; it explores different plutonium concentrations and isotopic qualities in order to evaluate their safety characteristics. Simulation of their evolution allows us to quantify the production of U-233 at the end of burnup. Last, different french scenarios validating a possible transition towards a park of thermal Th/U-233 breeders, are presented. In these scenarios, U-233 is produced in ThPu moxed light water reactors. (author)

Assessment of airborne 238U and 232Th exposure and dust load impact on people living in the vicinity of a cement factory in Ghana

International Nuclear Information System (INIS)

Addo, Moses Ankamah; Gbadago, J.K.; Ameyaw, Felix; Darko, E.O.; Gordon, Chris; Davor, Peter; Faanu, A.; Kpeglo, David

2014-01-01

Globally, the cement industry has been identified as one which causes significant particle pollution. In Ghana, environmental research in the neighborhood of the cement industry especially on human health is scanty. In the present work, attempts were made to evaluate the concentration of airborne dust at various distances and directions around the Diamond Cement Factory in the Volta Region of Ghana. The samples of dust were collected on filter papers and later analyzed for the concentration (mg/kg) of 232 Th and 23 '8U using neutron activation analysis. The principal objective of the study was to generate data intended at assessing the annual effective dose due to 232 Th and 238 U inhalation for both adult and children population living in the vicinity of cement factory. The data generated were supposed to assist in remediation decision making, if required. The study recorded a few incidences of higher total dust load concentrations as compared to the permissible limit of 150 μg/m 3 specified by the Ghana Environmental Protection Agency. The calculated mean effective doses were 28.2 ± 1.06 μSv/year and 25.9 ± 0.91 μSv/year for both adult and child, respectively. From the radiological point of view, the study concluded that the people living in the vicinity of the cement factory are not at risk to significant radiological hazards. However, the study indicated the need to have a complete evaluation of the impact of the factory on the environment assessment programs which should include both chemical and radiological toxicity. (author)

A LMFBR for thorium utilization and for the U233/Th fuel rods specification

International Nuclear Information System (INIS)

Ishiguro, Y.; Dias, A.F.

1982-01-01

The use of U 233 /Th as fuel in the middle part of LMFBR core and the Pu/U in the external part of the core, are proposed. The basic neutronic and safety characteristics and the specifications of fuel rods to be used in the internal core, are presented. (E.G.) [pt

Measurement of activity concentrations of {sup 40}K, 2{sup 32T}h and {sup 238}U in TSP aerosols and the associated inhalation annual effective radiation dose to the public in Gosan site, Jeju

Energy Technology Data Exchange (ETDEWEB)

Han, Chung Hun; Park, Youn Hyun; Park, Jae Woo [Jeju National University, Jeju (Korea, Republic of)

2016-10-15

Gamma radiation emitted from naturally occurring radioisotopes, such as 40K and the radionuclides from the {sup 232}Th and {sup 238}U series and their decay products, which exist at trace levels in all ground formations, represents the main external source of irradiation to the human body. The objective of the current study is to determine the activity concentrations of 40K, {sup 232}Th and {sup 238}U in airborne TSP and the associated internal radiation dose to the public due to inhalation in Gosan site, Jeju Island, Korea. The atmospheric total suspended particulates (TSP) aerosols were collected at Gosan site of Jeju Island, which is one of the background sites of Korea, during January to April 2013. This study analyzed using ICP-DRC-MS the concentrations of potassium, uranium and thorium, and evaluated the annual effective dose by breathing from the results. The correlations between the studied natural isotopes is a good positive correlation between {sup 232}Th and {sup 238}U, supporting the conclusion that they originated from the same source, mostly the crust. The backward trajectory analysis has confirmed that the 40K, {sup 238}U and {sup 232}Th are delivered as the air masses have moved from the China continent. The inhalation annual effective radiation dose (default mode F) to the public due to natural isotopes of the airborne TSP was in the range 16.195 - 77.051 nSv/y, depending on the age group. Jeju Island with less pollution source and low population density is also one of the best places as a background area in Asia.

Fission cross sections of some thorium, uranium, neptunium and plutonium isotopes relative to /sup 235/U

Energy Technology Data Exchange (ETDEWEB)

Meadows, J W

1983-10-01

Earlier results from the measurements, at this Laboratory, of the fission cross sections of /sup 230/Th, /sup 232/Th, /sup 233/U, /sup 234/U, /sup 236/U, /sup 238/U, /sup 237/Np, /sup 239/Pu, /sup 240/Pu, and /sup 242/Pu relative to /sup 235/U are reviewed with revisions to include changes in data processing procedures, alpha half lives and thermal fission cross sections. Some new data have also been included. The current experimental methods and procedures and the sample assay methods are described in detail and the sources of error are presented in a systematic manner. 38 references.

Determination of radioactivity levels in phosphate-containing fertilizers, copper and gold ores by direct gamma-ray spectroscopy. U-238, Th-232, K-40, and Ra-226 in fertilizers and ores

International Nuclear Information System (INIS)

Constantinescu, B.; Constantin, F.; Dusoiu, N.; Pascovoici, G.

1996-01-01

Two particular sources from the natural radiation background which may be encountered in Romanian industry are here presented: the phosphate containing fertilizers and the gold and copper ores, respectively. U-238, Th-232, K-40, and Ra-226 activity levels for several imported phosphorites, superphosphates and also for concentrated Cu and Au indigenous ores are reported. A simple and efficient radioactivity determination procedure based on a large volume NaI(Tl) detector, coupled to a Romanian design portable multichannel analyzer is described. Potential radiological impacts for the specialized workers are also discussed. (author) 1 fig., 4 tabs. 6 refs

Within the framework of the new fuel cycle {sup 232}Th/{sup 233}U, determination of the {sup 233}Pa(n.{gamma}) radiative capture cross section for neutron energies ranging between 0 and 1 MeV; Dans le cadre du nouveau cycle de combustible {sup 232}Th/{sup 233}U, determination de la section efficace de capture radiative {sup 233}Pa(n,{gamma}) pour des energies de neutrons comprises entre 0 et 1 MeV

Energy Technology Data Exchange (ETDEWEB)

Boyer, S

2004-10-15

The Thorium cycle Th{sup 232}/U{sup 233} may face brilliant perspectives through advanced concepts like molten salt reactors or accelerator driven systems but it lacks accurate nuclear data concerning some nuclei. Pa{sup 233} is one of these nuclei, its high activity makes the direct measurement of its radiative neutron capture cross-section almost impossible. This difficulty has been evaded by considering the transfer reaction Th{sup 232}(He{sup 3},p)Pa{sup 234}* in which the Pa{sup 234} nucleus is produced in various excited states according to the amount of energy available in the reaction. The first chapter deals with the thorium cycle and its assets to contribute to the quenching of the fast growing world energy demand. The second chapter gives a detailed description of the experimental setting. A scintillation detector based on deuterated benzene (C{sub 6}D{sub 6}) has been used to counter gamma ray cascades. The third chapter is dedicated to data analysis. In the last chapter we compare our experimental results with ENDF and JENDL data and with computed values from 2 statistical models in the 0-1 MeV neutron energy range. Our results disagree clearly with evaluated data: our values are always above ENDF and JENDL data but tend to near computed values. We have also perform the measurement of the radiative neutron cross-section of Pa{sup 231} for a 110 keV neutron: {sigma}(n,{gamma}) 2.00 {+-} 0.14 barn. (A.C.)

Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O+232Th reaction

Directory of Open Access Journals (Sweden)

R. Léguillon

2016-10-01

Full Text Available It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O+232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model.

Contribution to the study of {sup 233}U production with MOX-ThPu fuel in PWR reactor. Transition scenarios towards Th/{sup 233}U iso-generating concepts in thermal spectrum. Development of the MURE fuel evolution code; Contribution a l'etude de la production d'{sup 233}U en combustible MOX-ThPu en reacteur a eau sous pression. Scenarios de transition vers des concepts isogenerateurs Th/{sup 233}U en spectre thermique. Developpement du code MURE d'evolution du combustible

Energy Technology Data Exchange (ETDEWEB)

Michel-Sendis, F

2006-12-15

If nuclear power is to provide a significant fraction of the growing world energy demand, only through the breeding concept can the development of sustainable nuclear energy become a reality. The study of such a transition, from present-day nuclear technologies to future breeding concepts is therefore pertinent. Among these future concepts, those using the thorium cycle Th/U-233 in a thermal neutron spectrum are of particular interest; molten-salt type thermal reactors would allow for breeding while requiring comparatively low initial inventories of U-233. The upstream production of U-233 can be obtained through the use of thorium-plutonium mixed oxide fuel in present-day light water reactors. This work presents, firstly, the development of the MURE evolution code system, a C++ object-oriented code that allows the study, through Monte Carlo (M.C.) simulation, of nuclear reactors and the evolution of their fuel under neutron irradiation. The M.C. methods are well-suited for the study of any reactor, whether it'd be an existing reactor using a new kind of fuel or a future concept altogether, the simulation is only dependent on nuclear data. Exact and complex geometries can be simulated and continuous energy particle transport is performed. MURE is an interface with MCNP, the well-known and validated transport code, that allows, among other functionalities, to simulate constant power and constant reactivity evolutions. Secondly, the study of MOX ThPu fuel in a conventional light water reactor (REP) is presented; it explores different plutonium concentrations and isotopic qualities in order to evaluate their safety characteristics. Simulation of their evolution allows us to quantify the production of U-233 at the end of burnup. Last, different french scenarios validating a possible transition towards a park of thermal Th/U-233 breeders, are presented. In these scenarios, U-233 is produced in ThPu moxed light water reactors. (author)

Chain and independent fission product yields adjusted to conform with physical conservation laws. Part 2

International Nuclear Information System (INIS)

Crouch, E.A.C.

1976-01-01

Previously reported adjustments to the chain yields and independent yields for the thermal neutron induced fission of 233 U, 235 U, 239 Pu and 241 Pu, the fast neutron induced fission of 232 Th, 233 U, 235 U, 238 U, 239 Pu, 240 Pu and 241 Pu, and the 14 MeV neutron induced fission of 232 Th, 233 U, 235 U and 238 U, have been recalculated using the principle of least squares. The adjustments to the chain yields so found are much smaller than those previously reported. (author)

Determination of 232Th, 230Th and 228Th in liquid effluents from uranium mining

International Nuclear Information System (INIS)

Godoy, Jose Marcus de Oliveira

1979-10-01

A liquid scintillator αlpha spectrometer was built for the determination of Th- 228 , Th- 230 and Th- 232 in liquid effluents from Uranium mines and mills. The resolution of the αlpha spectrometer was found to be 200-300 KeV, when the scintillator was 8% T0P0, 0,77% scintimix-4 (91% PP0 and 9% Dimetil-P0P0P) and 10% of naphthalene in toluene. Aliquat-336 in xylene (30% v/v) was used to separate the thorium isotopes from other interfering radionuclides (U- 238 , U- 234 , Ra- 226 , Po- 210 ). Under the extraction experimental conditions, the detection limits were 1,2 pCi/1 for Th- 232 , 1,2 pCi/1 for Th- 230 and 0,9 pCi/1 for Th- 228 , for 1000 minutes of counting time. (author)

Radiological impact due to natural radionuclides (U and Th-isotopes) in soils from Salamanca, Mexico

Energy Technology Data Exchange (ETDEWEB)

Mandujano G, C. D.; Sosa, M. [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Loma del Bosque 103, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Mantero, J.; Manjon, G.; Garcia T, R. [Universidad de Sevilla, Grupo en Fisica Nuclear Aplicada, Av. Reina Mercedes No. 2, 41012 Sevilla (Spain); Costilla, R., E-mail: cmandujano@fisica.ugto.mx [Universidad de Guanajuato, Division de Ciencias de la Vida, Departamento de Ciencias Ambientales, Ex-Hacienda El Copal Km 9 Irapuato-Silao, 36500 Irapuato, Guanajuato (Mexico)

2015-10-15

Full text: Activity concentrations of U ({sup 238}U, {sup 234}U) and Th ({sup 232}Th, {sup 230}Th) radionuclides in samples of superficial urban soils surrounding an industrial complex in Salamanca, Mexico have been determined. Levels of naturally occurring radionuclides (Norm) in the environment may be affected due to the presence of different industrial activities in this zone, representing a potential radiological risk for the population which should be evaluated. Alpha-particle Spectrometry with Pips detectors has been used for the radiometric characterization. A well established radiochemical procedure was used for the isolation of the radionuclides of interest. Alkali fusion for sample digestion, liquid-liquid extraction with Tbp (tri-butyl-phosphate) for U and Th isolation and electrodeposition in stainless steel dishes for measurement conditioning has been used. The results cover the ranges of 10-42, 12-60, 12-52 and 11-51 Bq·kg{sup -1} for {sup 238}U, {sup 234}U, {sup 230}Th, and {sup 232}Th respectively, being not observed any clear anthropogenic increments in relation with the values normally found in unaffected soils. Although there is disequilibrium between U isotopes and {sup 230}Th in some soil samples, it can be attributed to natural processes. The radiological impact of the industrial activities in the surrounding soils can be then evaluated as very low. Hence, from the Radiological Protection point of view, the soils studied do not represent a radiological risk for the health of the population. (Author)

238U-230Th-226Ra radioactive disequilibria in the products from 1707 eruption of Fuji volcano, Japan

International Nuclear Information System (INIS)

Kurihara, Yuichi; Takahashi, Masaomi; Sato, Jun

2008-01-01

Time scale of magmatic processes in the 1707 eruptive activity of Fuji volcano, Japan, was estimated by the 238 U- 230 Th- 226 Ra disequilibria observed in the 1707 volcanic products. The activity ratios of 226 Ra/ 230 Th in the products were larger than unity, being enriched in 226 Ra relative to 230 Th. The decay-corrected 226 Ra/ 230 Th activity ratio to the time of the eruption versus 238 U/ 230 Th activity ratio diagram for the 1707 volcanic products showed a positive correlation, suggesting that the 238 U/ 230 Th- 226 Ra disequilibria occurred during the magma genesis of Fuji volcano. The 230 Th- 226 Ra disequilibria in the 1707 volcanic products suggested that the time scale from the magma genesis to the eruption, including the melting of the mantle wedge, magma storage and magmatic differentiation from basalt to andesite, was less than 8000 years. (author)

Analysis of photofission reactions of 235U, 238U, 232Th, 209Bi, natPb, 197Au, natPt, natW, 181Ta, and 27Al by photons of 69 MeV

International Nuclear Information System (INIS)

Paiva, Eduardo de

1997-04-01

Fission reactions induced in 235 U, 238 U, 232 Th, 209 Bi nat Pb, 197 Au, nat Pt, nat W, 181 Ta. and 27 Al nuclei by monochromatic photons of 69 MeV produced at the LADON facility of the Frascati National Laboratories (INFN-LNF, Frascati, Italy) have been analyzed on the basis of a simplified two-step model. In the first step of the reaction the incoming photon is considered to be absorbed by a neutron-proton pair ('quasi-deuteron') leading to excitation of the nucleus, followed, in the second step, by a mechanism of particle evaporation-fission competition for the excited residual nucleus. Estimates of nuclear fissility at 69 MeV show to be critically dependent on the parameter r (ratio of the level-density parameter at the fission saddle point to the level-density parameter of the residual nucleus after neutron evaporation), which can be determined in a semiempirical way from induced fission reaction data for various nuclei obtained at 60 - 80 MeV of excitation energy. Fissilities calculated by means of the simplified photofission reactions model are then compared with experimental data available in the literature. (author)

Mobility of radionuclides and trace elements in soil from legacy NORM and undisturbed naturally 232Th-rich sites.

Science.gov (United States)

Mrdakovic Popic, Jelena; Meland, Sondre; Salbu, Brit; Skipperud, Lindis

2014-05-01

Investigation of radionuclides (232Th and 238U) and trace elements (Cr, As and Pb) in soil from two legacy NORM (former mining sites) and one undisturbed naturally 232Th-rich site was conducted as a part of the ongoing environmental impact assessment in the Fen Complex area (Norway). The major objectives were to determine the radionuclide and trace element distribution and mobility in soils as well as to analyze possible differences between legacy NORM and surrounding undisturbed naturally 232Th-rich soils. Inhomogeneous soil distribution of radionuclides and trace elements was observed for each of the investigated sites. The concentration of 232Th was high (up to 1685 mg kg(-1), i.e., ∼7000 Bq kg(-1)) and exceeded the screening value for the radioactive waste material in Norway (1 Bq g(-1)). Based on the sequential extraction results, the majority of 232Th and trace elements were rather inert, irreversibly bound to soil. Uranium was found to be potentially more mobile, as it was associated with pH-sensitive soil phases, redox-sensitive amorphous soil phases and soil organic compounds. Comparison of the sequential extraction datasets from the three investigated sites revealed increased mobility of all analyzed elements at the legacy NORM sites in comparison with the undisturbed 232Th-rich site. Similarly, the distribution coefficients Kd (232Th) and Kd (238U) suggested elevated dissolution, mobility and transportation at the legacy NORM sites, especially at the decommissioned Nb-mining site (346 and 100 L kg(-1) for 232Th and 238U, respectively), while the higher sorption of radionuclides was demonstrated at the undisturbed 232Th-rich site (10,672 and 506 L kg(-1) for 232Th and 238U, respectively). In general, although the concentration ranges of radionuclides and trace elements were similarly wide both at the legacy NORM and at the undisturbed 232Th-rich sites, the results of soil sequential extractions together with Kd values supported the expected differences

Hydrogeochemical utilization of natural isotopes from U(4n+2) and Th(4n) series at Morro do Ferro, Pocos de Caldas (MG)

International Nuclear Information System (INIS)

Bonotto, D.M.

1991-01-01

Uranium and thorium isotopic analysis were performed on well spoils of the main ore body at Morro do Ferro, Pocos de Caldas (MG), using groundwater from several boreholes in the area and surface water from a steam that originates at the base of the hill. For extraction of uranium and thorium a long chemical process was applied to samples; activities of 228Th and 232 Th isotopes (4n series) and also of 238U, 234U and 230Th isotopes (4n+2 series)were determined by the alpha spectrometry method. The ratios 234U?238U determined for well spoils did not show marked disequilibria between these isotopes. However, the ratios 228Th/232Th and 230Th/234U obtained in some samples showed a high disequilibrium between these isotopes, associated with the presence of possible zones of removal of uranium and precipitation of radium.(author)

238U-230Th dating of chevkinite in high-silica rhyolites from La Primavera and Yellowstone calderas

Science.gov (United States)

Vazquez, Jorge A.; Velasco, Noel O.; Schmitt, Axel K.; Bleick, Heather A.; Stelten, Mark E.

2014-01-01

Application of 238U-230Th disequilibrium dating of accessory minerals with contrasting stabilities and compositions can provide a unique perspective on magmatic evolution by placing the thermochemical evolution of magma within the framework of absolute time. Chevkinite, a Th-rich accessory mineral that occurs in peralkaline and metaluminous rhyolites, may be particularly useful as a chronometer of crystallization and differentiation because its composition may reflect the chemical changes of its host melt. Ion microprobe 128U-230Th dating of single chevkinite microphenocrysts from pre- and post-caldera La Primavera, Mexico, rhyolites yields model crystallization ages that are within 10's of k.y. of their corresponding K-Ar ages of ca. 125 ka to 85 ka, while chevkinite microphenocrysts from a post-caldera Yellowstone, USA, rhyolite yield a range of ages from ca. 110 ka to 250 ka, which is indistinguishable from the age distribution of coexisting zircon. Internal chevkinite-zircon isochrons from La Primavera yield Pleistocene ages with ~5% precision due to the nearly two order difference in Th/U between both minerals. Coupling chevkinite 238U-230Th ages and compositional analyses reveals a secular trend of Th/U and rare earth elements recorded in Yellowstone rhyolite, likely reflecting progressive compositional evolution of host magma. The relatively short timescale between chevkinite-zircon crystallization and eruption suggests that crystal-poor rhyolites at La Primavera were erupted shortly after differentiation and/or reheating. These results indicate that 238U-230Th dating of chevkinite via ion microprobe analysis may be used to date crystallization and chemical evolution of silicic magmas.

Interim assessment of the denatured 233U fuel cycle: feasibility and nonproliferation characteristics

International Nuclear Information System (INIS)

Abbott, L.S.; Bartine, D.E.; Burns, T.J.

1979-12-01

A fuel cycle that employs 233 U denatured with 238 U and mixed with thorium fertile material is examined with respect to its proliferation-resistance characteristics and its technical and economic feasibility. The rationale for considering the denatured 233 U fuel cycle is presented, and the impact of the denatured fuel on the performance of Light-Water Reactors, Spectral-Shift-Controlled Reactors, Gas-Cooled Reactors, Heavy-Water Reactors, and Fast Breeder Reactors is discussed. The scope of the R, D and D programs to commercialize these reactors and their associated fuel cycles is also summarized and the resource requirements and economics of denatured 233 U cycles are compared to those of the conventional Pu/U cycle. In addition, several nuclear power systems that employ denatured 233 U fuel and are based on the energy center concept are evaluated

Contribution of some food categories on intakes of U, Th and other nuclides

International Nuclear Information System (INIS)

Shiraishi, Kunio

1999-01-01

The assessment of radiation dose in human from radioactive 232 Th, 238 U, 137 Cs, and 90 Sr are important because those nuclides are the largest contributors to committed internal doses. A market basket study was conducted to clarify the food pathways of the nuclides in Japanese subjects. Foodstuffs of 336 were purchased from markets in the vicinity of Mito-City during 1994-1995. Statistical consumption data were used for collection of the food samples. Thorium-232, 238 U, and stable isotope ( 133 Cs) in eighteen food groups were determined by inductively coupled mass spectrometry (ICP-MS). Radioisotopes ( 137 Cs) was analyzed by γ-spectrometry. Stable strontium ( 88 Sr) was also analyzed by inductively coupled atomic emission spectrometry (ICP-AES). Big contributors to the nuclide intakes in Japanese were as follows: 232 Th fishes and shellfishes (44%) and green vegetables (11%); 238 U seaweeds (50%) and fishes and shellfishes (26%); 88 Sr seaweeds (53%) and fishes and shellfishes (14%); 137 Cs mushrooms (17%), fishes and shell fishes (15%), milk products (11%), meats (9%), and potatoes (7%). The food categories of oil and fats, eggs and cooked meals were minor contributors in those nuclides. Dietary intake studies by using eighteen or more food categories should be effective procedure to resolve critical food and critical pathway for Japanese. Furthermore, critical pathways of radionuclides could be estimated by the analyses of stable isotopes. (author)

Development of automation and remotisation systems for fabrication of (Th-233U)O2 MOX fuel for AHWR

International Nuclear Information System (INIS)

Saraswat, Anupam; Danny, K.M.; Chakraborty, S.; Somayajulu, P.S.; Kumar, Arun; Mittal, R.; Prasad, R.S.; Mahule, K.N.; Panda, S.; Jayarajan, K.

2011-01-01

To meet the ever increasing power requirement of India, country is planning to utilize its large thorium reserves for the third stage of nuclear power program based on Thorium-Uranium 233 fuel in A.H.W.R. Although there are many advantages of (Th- 233 U)O 2 fuel cycle, presence of radiological hazards due to the presence of 1000-2000 ppm level of 232 U in the 233 U fuel and inertness of ThO 2 makes handling and fabrication of fuel difficult. The associated high alpha and gamma activity demands high level of automation and remote handling in alpha tight hot cells. To demonstrate automation and remotisation in (Th- 233 U)O 2 fuel fabrication, a mock up facility is being set up at BARC. This facility shall develop automation systems required for remote fuel fabrication in a simulated hot cell environment. There are many innovative schemes and systems being developed like integrated powder pellet system, remote viewing system for hot cell application etc. Low visibility inside the hot cell has always been a problem for the operator. To overcome this problem a remote viewing system has been developed by which entire hot cell area can be scanned with the use of a joystick and the display can be seen on a LCD monitor. The viewing system is made up of radiation resistant optics which can work even in high gamma fields. It consists of objective end assembly which is used to scan the hot cell area with the help of prism doublets and drive mechanism for capturing full 360 deg solid angle view. There is a Galilean telescope and focusing system used for focusing images of distant objects. Drive mechanism can be controlled by the joystick available to the operator. System has a high resolution CCD display and camera which gives a clear display of objects lying inside the hot cell area. Integrated powder pellet system is being developed for fabrication of MOX pellets from feed powder. This will be automated system which will take input in the form of MOX powder and convert it

Neutron induced fission cross section ratios for /sup 232/Th, /sup 235,238/U, /sup 237/Np, and /sup 239/Pu from 1 to 400 MeV

Energy Technology Data Exchange (ETDEWEB)

Lisowski, P.W.; Ullmann, J.L.; Balestrini, S.J.; Carlson, A.D.; Wasson, O.A.; Hill, N.W.

1988-01-01

Time-of-flight measurements of neutron induced fission cross section ratios for /sup 232/Th, /sup 235,238/U, /sup 237/Np, and /sup 239/Pu, were performed using the WNR high intensity spallation neutron source located at Los Alamos National Laboratory. A multiple-plate gas ionization chamber located at a 20-m flight path was used to simultaneously measure the fission rate for all samples over the energy range from 1 to 400 MeV. Because the measurements were made with nearly identical neutron fluxes, we were able to cancel many systematic uncertainties present in previous measurements. This allows us to resolve discrepancies among different data sets. In addition, these are the first neutron-induced fission cross section values for most of the nuclei at energies above 30 MeV. 8 refs., 3 figs.

Determination of the isotopic ratio 234 U/238 U and 235 U/238 U in uranium commercial reagents by alpha spectroscopy

International Nuclear Information System (INIS)

Iturbe G, J.L.

1990-02-01

In this work the determination of the isotope ratio 234 U/ 238 U and 235 U/ 238 U obtained by means of the alpha spectroscopy technique in uranium reagents of commercial marks is presented. The analyzed uranium reagents were: UO 2 (*) nuclear purity, UO 3 (*) poly-science, metallic uranium, uranyl nitrate and uranyl acetate Merck, uranyl acetate and uranyl nitrate Baker, uranyl nitrate (*) of the Refinement and Conversion Department of the ININ, uranyl acetate (*) Medi-Lab Sigma of Mexico and uranyl nitrate Em Science. The obtained results show that the reagents that are suitable with asterisk (*) are in radioactive balance among the one 234 U/ 238 U, since the obtained value went near to the unit. In the case of the isotope ratio 235 U/ 238 U the near value was also obtained the one that marks the literature that is to say 0.04347, what indicates that these reagents contain the isotope of 235 U in the percentage found in the nature of 0.71%. The other reagents are in radioactive imbalance among the 234 U/ 238 U, the found values fluctuated between 0.4187 and 0.1677, and for the quotient of activities 235 U/ 238 U its were of 0.0226, and the lowest of 0.01084. Also in these reagents it was at the 236 U as impurity. The isotope of 236 U is an isotope produced artificially, for what is supposed that the reagents that are in radioactive imbalance were synthesized starting from irradiated fuel. (Author)

U-Th-Ra disequilibria at the Masaya (Nicaragua); Desequilibres U-Th-Ra au Masaya (Nicaragua)

Energy Technology Data Exchange (ETDEWEB)

Sigmarsson, O; Condomines, M [Centre de Recherches Volcanologiques, CNRS URA-10, 63 - Clermont Ferrand (France)

1997-12-31

{sup 238}U-{sup 230}Th-{sup 226}Ra radioactive disequilibria were measured in several basalt samples of the post-caldera flows of the Masaya volcano (Nicaragua). {sup 230}Th/{sup 232}Th ratios are from the highest known in the world (about 2.53) with {sup 230}Th/{sup 238}U ratios close to 1. These exceptionally high isotopic thorium ratios from the Masaya and other neighboring volcanoes (Conception, Cerro Negro, Momotombo) are followed by very high {sup 10}Be/{sup 9}Be ratios (60 10{sup -11} for the 1722 flow). These geochemical characteristics with {delta}{sup 18}O of typical mantle origin (5.55) suggest an influence of the subducted sediments fluids in the magma source. The age of the metasomatism ranges from 10 to 0.3 Ma. Initial {sup 226}Ra/{sup 230}Th ratios measured in four historical flows vary from 1.3 to 1.4 and are anti-correlated with the Th content. These variations are probably linked to the fractionated crystallisation of plagioclase minerals. The initial {sup 226}Ra/Ba ratio remains constant and suggests the existence of a huge stationary magmatic reservoir. This hypothesis is also confirmed by the disproportion between the SO{sub 2} quantity emitted by the volcano and by the degassing of lavas on the ground. The {sup 226}Ra excess observed in the Masaya lavas can be the result of a second stage of metasomatism which occurred less than 8000 years B.P. during partial fusion. Abstract only. (J.S.).

U-Th-Ra disequilibria at the Masaya (Nicaragua); Desequilibres U-Th-Ra au Masaya (Nicaragua)

Energy Technology Data Exchange (ETDEWEB)

Sigmarsson, O.; Condomines, M. [Centre de Recherches Volcanologiques, CNRS URA-10, 63 - Clermont Ferrand (France)

1996-12-31

{sup 238}U-{sup 230}Th-{sup 226}Ra radioactive disequilibria were measured in several basalt samples of the post-caldera flows of the Masaya volcano (Nicaragua). {sup 230}Th/{sup 232}Th ratios are from the highest known in the world (about 2.53) with {sup 230}Th/{sup 238}U ratios close to 1. These exceptionally high isotopic thorium ratios from the Masaya and other neighboring volcanoes (Conception, Cerro Negro, Momotombo) are followed by very high {sup 10}Be/{sup 9}Be ratios (60 10{sup -11} for the 1722 flow). These geochemical characteristics with {delta}{sup 18}O of typical mantle origin (5.55) suggest an influence of the subducted sediments fluids in the magma source. The age of the metasomatism ranges from 10 to 0.3 Ma. Initial {sup 226}Ra/{sup 230}Th ratios measured in four historical flows vary from 1.3 to 1.4 and are anti-correlated with the Th content. These variations are probably linked to the fractionated crystallisation of plagioclase minerals. The initial {sup 226}Ra/Ba ratio remains constant and suggests the existence of a huge stationary magmatic reservoir. This hypothesis is also confirmed by the disproportion between the SO{sub 2} quantity emitted by the volcano and by the degassing of lavas on the ground. The {sup 226}Ra excess observed in the Masaya lavas can be the result of a second stage of metasomatism which occurred less than 8000 years B.P. during partial fusion. Abstract only. (J.S.).

Isotopic dilution requirements for 233U criticality safety in processing and disposal facilities

International Nuclear Information System (INIS)

Elam, K.R.; Forsberg, C.W.; Hopper, C.M.; Wright, R.Q.

1997-11-01

The disposal of excess 233 U as waste is being considered. Because 233 U is a fissile material, one of the key requirements for processing 233 U to a final waste form and disposing of it is to avoid nuclear criticality. For many processing and disposal options, isotopic dilution is the most feasible and preferred option to avoid nuclear criticality. Isotopic dilution is dilution of fissile 233 U with nonfissile 238 U. The use of isotopic dilution removes any need to control nuclear criticality in process or disposal facilities through geometry or chemical composition. Isotopic dilution allows the use of existing waste management facilities, that are not designed for significant quantities of fissile materials, to be used for processing and disposing of 233 U. The amount of isotopic dilution required to reduce criticality concerns to reasonable levels was determined in this study to be ∼ 0.66 wt% 233 U. The numerical calculations used to define this limit consisted of a homogeneous system of silicon dioxide (SiO 2 ), water (H 2 O), 233 U, and depleted uranium (DU) in which the ratio of each component was varied to determine the conditions of maximum nuclear reactivity. About 188 parts of DU (0.2 wt% 235 U) are required to dilute 1 part of 233 U to this limit in a water-moderated system with no SiO 2 present. Thus, for the US inventory of 233 U, several hundred metric tons of DU would be required for isotopic dilution

Capture and Fission rate of 232-Th, 238-U, 237-Np and 239-Pu from spallation neutrons in a huge block of lead.

CERN Document Server

Vlachoudis, Vasilis

2000-01-01

The study is centered on the research of the incineration possibility of nuclear waste, by the association of a particle accelerator with a multiplying medium of neutrons, in the project "Energy Amplifier" of C. Rubbia. It consists of the experimental determination of the rates of capture and fission of certain elements (232-Th, 238-U, 237-Np and 239-Pu) subjected to a fluence of fast spallation neutrons. These neutrons are produced by the interaction of high kinetic energy protons (several GeV) provided by the CERN-PS accelerator, on a large lead solid volume. The measurement techniques used in this work, are based on the activation of elements in the lead volume and the subsequent gamma spectroscopy of the activated elements, and also by the detection of fission fragment traces. The development, of a Monte Carlo code makes it possible, on one hand, to better understand the relevant processes, and on the other hand, to validate the code, by comparison with measurements, for the design and the construction of...

Behavior of uranium along Jucar River (Eastern Spain). Determination of 234U/238U and 235U/238U ratios

International Nuclear Information System (INIS)

Rodriguez-Alvarez, M.J.; Sanchez, F.

1995-01-01

The uranium concentration and the 234 U/ 238 U, 235 U/ 238 U activity ratios were studied in water samples from Jucar River, using low-level α-spectrometry. The effects of pH, temperature and salinity were considered and more detailed sampling was done in the neighbourhood of Cofrentes Nuclear Plant (Valencia, Spain). Changes were observed in the uranium concentration with the salinity and the 234 U/ 238 U activity ratio was found to vary with pH. Leaching and dilution, which depend on pH and salinity, are the probable mechanisms for these changes in the concentration of uranium and the activity ratios. (author) 25 refs.; 4 figs.; 1 tab

Radionuclides (40K, 232Th and 238U) and Heavy Metals (Cr, Ni, Cu, Zn, As and Pb) Distribution Assessment at Renggam Landfill, Simpang Renggam, Johor, Malaysia

Science.gov (United States)

Zaidi, E.; FahrulRazi, MJ; Azhar, ATS; Hazreek, ZAM; Shakila, A.; Norshuhaila, MS; Omeje, M.

2017-08-01

The assessment of radioactivity levels and the distribution of heavy metals in soil samples at CEP Farm landfill, Renggam in Johor State was to determine the activity concentrations of naturally occurring radionuclides and heavy metal concentrations of this landfill. The background radiation was monitored to estimate the exposure level. The activity concentrations of radionuclides in soil samples were determined using HPGe gamma ray spectroscopy whereas the heavy metal concentration was measured using X-RF analysis. The mean exposure rate at the landfill site was 36.2±2.4 μR hr-1 and the annual effective dose rate at the landfill site was 3.19 ± 0.22 mSv yr-1. However, residential area has lower mean exposure dose rate of about 16.33±0.72 μR hr-1 and has an annual effective dose rate of 1.43±0.06 mSv yr-1 compared to landfill sites. The mean activity concentration of 40K, 238U and 232Th at landfill site were 239.95±15.89 Bq kg-1, 20.90±2.49 Bq kg-1 and 40.61±4.59 Bq kg-1, respectively. For heavy metal compositions, Cr, Ni and Cu have mean concentration of 232±10 ppm, 23±2 ppm, and 46±19 ppm, respectively. Whereas, Zn has concentration of 64±9 ppm and concentration of 12±1 ppm and 71±2 ppm was estimated for As and Pb respectively. The higher activity concentration of 40K down the slope through leaching process whereas the higher activity level of 238U content at the landfill site may be attributed to the soil disruption to local equilibrium.

Determination of 230Th/232Th and correct methods by High Resolution Inductively Coupled Plasma Mass Spectrometry

International Nuclear Information System (INIS)

Xie Shengkai; Guo Dongfa; Tan Jing; Zhang Yanhui; Huang Qiuhong; Gao Aiguo

2013-01-01

It is very important for the rapid and reliable determination of 230 Th/ 232 Th in the thorium-230 dating. A method of measuring 230 Th/ 232 Th in natural samples by high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) was developed on the base of our former work. The precise and accurate of natural 230 Th in geology samples is challenging, as the peak tailing to the high intensity of neighboring peak at 232 Th and the mass discrimination of the instrument. The peak tailing of 238 U to 236 U was used to decrease the peak tailing effect of 232 Th to 230 Th. The mass discrimination factor K between ture and measured isotope ratio was calculated after measuring different 230 Th/ 232 Th ratio solutions. Lab used standard samples was digested in mixed acids of HN0 3 -HF-HCI-HCl0 4 , and separated by the Bio-rad AG 1 × 8 Cl - resin. The measurement method of blank-standard-blank-sample procession was used to determinate the 230 Th/ 232 Th. The measured result of 230 Th/ 232 Th was at (7.29 ± 0.34) × 10 -6 , which agreed with the reference value of (7.33 ± 0.17) × 10 -6 . (authors)

Uranium Age Determination by Measuring the 230Th / 234U Ratio

International Nuclear Information System (INIS)

LAMONT, STEPHEN P.

2004-01-01

A radiochemical isotope dilution mass spectrometry method has been developed to determine the age of uranium materials. The amount of 230Th activity, the first progeny of 234U, that had grown into a small uranium metal sample was used to determine the elapsed time since the material was last radiochemically purified. To preserve the sample, only a small amount of oxidized uranium was removed from the surface of the sample and dissolved. Aliquots of the dissolved sample were spiked with 233U tracer and radiochemically purified by anion-exchange chromatography. The 234U isotopic concentration was then determined by thermal ionization mass spectrometry. Additional aliquots of the sample were spiked with 229Th tracer, and the thorium was purified using two sequential anion-exchange chromatography separations. The isotopic concentrations of 230Th and 232Th were determined by TIMS. The lack of any 232Th confirmed the assumption that all thorium was removed from the uranium sample at the time of purification. The 230Th and 234U mass concentrations were converted to activities and the 230Th/234U ratio for the sample was calculated. The experimental 230Th/234U ratio showed the uranium in this sample was radiochemically purified in about 1945. Isotope dilution thermal ionization mass spectrometry has sufficient sensitivity to determine the age of 100 samples of uranium. This method could certainly be employed as a nuclear forensic method to determine the age of small quantities of uranium metal or salts. Accurate determination of the ultra-trace 230Th radiochemically separated from the uranium is possible due to the use of 229Th as an isotope dilution tracer. The precision in the experimental age of the uranium could be improved by making additional replicate measurements of the 230Th/234U isotopic ratio or using a larger initial sample

Assessment of the concentrations of U and Th in PM2.5 from Mexico City and their potential human health risk

International Nuclear Information System (INIS)

Mendez-Garcia, Carmen Grisel; Solis-Rosales, Corina; Rafael Chavez-Lomeli, Efrain

2017-01-01

This is one of the first studies in small particulate matter (PM 2.5 ) by inductively coupled plasma sector field mass spectrometry to measure the activity concentrations of isotopic uranium ( 234 , 235 and 238 U) and thorium ( 232 Th) in these fine particulates, to know their origin and their impact on human health in Mexico City. A different isotopic composition from the natural uranium composition was found. The 235 U/ 238 U atom ratio values are considered as low enrichment uranium, around 2% of 235 U enrichment. Both 235 U/ 238 U and 234 U/ 238 U ratios suggested anthropological rather natural source is impacting the composition of uranium in PM 2.5 . (author)

Measurement of 233U/234U ratios in contaminated groundwater using alpha spectrometry

International Nuclear Information System (INIS)

Harrison, Jennifer J.; Payne, Timothy E.; Wilsher, Kerry L.; Thiruvoth, Sangeeth; Child, David P.; Johansen, Mathew P.; Hotchkis, Michael A.C.

2016-01-01

The uranium isotope 233 U is not usually observed in alpha spectra from environmental samples due to its low natural and fallout abundance. It may be present in samples from sites in the vicinity of nuclear operations such as reactors or fuel reprocessing facilities, radioactive waste disposal sites or sites affected by clandestine nuclear operations. On an alpha spectrum, the two most abundant alpha emissions of 233 U (4.784 MeV, 13.2%; and 4.824 MeV, 84.3%) will overlap with the 234 U doublet peak (4.722 MeV, 28.4%; and 4.775 MeV, 71.4%), if present, resulting in a combined 233+234 U multiplet. A technique for quantifying both 233 U and 234 U from alpha spectra was investigated. A series of groundwater samples were measured both by accelerator mass spectrometry (AMS) to determine 233 U/ 234 U atom and activity ratios and by alpha spectrometry in order to establish a reliable 233 U estimation technique using alpha spectra. The Genie™ 2000 Alpha Analysis and Interactive Peak Fitting (IPF) software packages were used and it was found that IPF with identification of three peaks ( 234 U minor, combined 234 U major and 233 U minor, and 233 U major) followed by interference correction on the combined peak and a weighted average activity calculation gave satisfactory agreement with the AMS data across the 233 U/ 234 U activity ratio range (0.1–20) and 233 U activity range (2–300 mBq) investigated. Correlation between the AMS 233 U and alpha spectrometry 233 U was r 2  = 0.996 (n = 10). - Highlights: • Describes a technique for deconvoluting the combined 233 U and 234 U multiplet in alpha spectra. • Enables 233 U and 234 U activities and 233 U/ 234 U ratios to be quantified without requiring additional analysis and measurement. • Applicable to an environmental matrix (groundwater) using standard alpha spectrometry counting equipment, operation and set-up.

Vertical and horizontal distribution of radionuclides (232Th, 238U and 40K) in sediment from Manjung coastal water area Perak, Malaysia

Science.gov (United States)

Abdullah, Anisa; Hamzah, Zaini; Saat, Ahmad; Wood, Ab. Khalik

2016-01-01

Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides (232Th, 238U and 40K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (Igeo) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (Hex).

Vertical and horizontal distribution of radionuclides (232Th, 238U and 40K) in sediment from Manjung coastal water area Perak, Malaysia

International Nuclear Information System (INIS)

Abdullah, Anisa; Hamzah, Zaini; Wood, Ab. Khalik; Saat, Ahmad

2016-01-01

Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides ( 232 Th, 238 U and 40 K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (I geo ) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (H ex )

Preserving high-purity 233U

International Nuclear Information System (INIS)

Krichinsky, Alan; Giaquinto, Joe; Canaan, Doug

2016-01-01

The MARC X Conference hosted a workshop for the scientific community to communicate needs for high-purity 233 U and its by-products in order to preserve critical items otherwise slated for downblending and disposal. Currently, only small portions of the U.S. holdings of separated 233 U are being preserved. However, many additional kilograms of 233 U (>97 % pure) still are destined to be disposed, and it is unlikely that this material will ever be replaced due to a lack of operating production capability. Summaries of information conveyed at the workshop and feedback obtained from the scientific community are presented herein. (author)

Determination of the isotopic ratio {sup 234} U/{sup 238} U and {sup 235} U/{sup 238} U in uranium commercial reagents by alpha spectroscopy; Determinacion de la relacion isotopica {sup 234} U/{sup 238} U y {sup 235} U/{sup 238} U en reactivos comerciales de uranio por espectrometria alfa

Energy Technology Data Exchange (ETDEWEB)

Iturbe G, J L

1990-02-15

In this work the determination of the isotope ratio {sup 234} U/{sup 238} U and {sup 235} U/{sup 238} U obtained by means of the alpha spectroscopy technique in uranium reagents of commercial marks is presented. The analyzed uranium reagents were: UO{sub 2} (*) nuclear purity, UO{sub 3} (*) poly-science, metallic uranium, uranyl nitrate and uranyl acetate Merck, uranyl acetate and uranyl nitrate Baker, uranyl nitrate (*) of the Refinement and Conversion Department of the ININ, uranyl acetate (*) Medi-Lab Sigma of Mexico and uranyl nitrate Em Science. The obtained results show that the reagents that are suitable with asterisk (*) are in radioactive balance among the one {sup 234} U/{sup 238} U, since the obtained value went near to the unit. In the case of the isotope ratio {sup 235} U/{sup 238} U the near value was also obtained the one that marks the literature that is to say 0.04347, what indicates that these reagents contain the isotope of {sup 235} U in the percentage found in the nature of 0.71%. The other reagents are in radioactive imbalance among the {sup 234} U/{sup 238} U, the found values fluctuated between 0.4187 and 0.1677, and for the quotient of activities {sup 235} U/{sup 238} U its were of 0.0226, and the lowest of 0.01084. Also in these reagents it was at the {sup 236} U as impurity. The isotope of {sup 236} U is an isotope produced artificially, for what is supposed that the reagents that are in radioactive imbalance were synthesized starting from irradiated fuel. (Author)

Application of 234U/238U isotope ratio data for the study of geochemical problems associated with local water sources from Aguas da Prata (SP, Brazil)

International Nuclear Information System (INIS)

Bonotto, D.M.

1982-01-01

The uranium-238, uranium-234 and radon content of spring waters of Aguas da Prata (SP) - Platina, Paiol, Villela, Sao Bento, Prata-Radioativa, Prata-Nova, Boi, Vitoria and Prata-Antiga - was found; the activity ratio AR ( 234 U/ 238 U) was applied to the geochemistry of local water sources. The uranium analysis procedure consisted of the following steps: adition of 232 U- 228 Th spike to the samples, coprecipitation with iron, iron extraction with organic solvent, separation on anion-exchange resin, extraction with TTA, deposition on stainless steel disc and determination of uranium content by alpha spectrometry. The uranium-238 content changed from 0,10 to 11,56 ppb (average value = 2,3 ppb). The higher values were observed for the waters circulating through sandstones and the lower through volcanic rocks. The inverse correlation (r sub(s) =-0,76) between pH and uranium-238 content confirmed the contribution of this factor on its solubility. The significative correlation r sub(s) = 0,76 between dissolved oxygen and uranium-238 content also confirmed the higher uranium on the more oxidizing zones. The AR changed from 2,84 to 11,68 (average value = 6). These values defined the regional aquifer systems as mineralized in uranium. The higher AR were observed for the deep groundwaters and the lower for the shallow one. Because the 238 U→ 234 Th decay, the 234 Th ejection to the solution was confirmed as the most important factor responsible for the extreme observed isotopic fractionation. (Author) [pt

Interim assessment of the denatured 233U fuel cycle: feasibility and nonproliferation characteristics

International Nuclear Information System (INIS)

Abbott, L.S.; Bartine, D.E.; Burns, T.J.

1978-12-01

A fuel cycle that employs 233 U denatured with 238 U and mixed with thorium fertile material is examined with respect to its proliferation-resistance characteristics and its technical and economic feasibility. The rationale for considering the denatured 233 U fuel cycle is presented, and the impact of the denatured fuel on the performance of Light-Water Reactors, Spectral-Shift-Controlled Reactors, Gas-Cooled Reactors, Heavy-Water Reactors, and Fast Breeder Reactors is discussed. The scope of the R, D and D programs to commercialize these reactors and their associated fuel cycles is also summarized and the resource requirements and economics of denatured 233 U cycles are compared to those of the conventional Pu/U cycle. In addition, several nuclear power systems that employ denatured 233 U fuel and are based on the energy center concept are evaluated. Under this concept, dispersed power reactors fueled with denatured or low-enriched uranium fuel are supported by secure energy centers in which sensitive activities of the nuclear cycle are performed. These activities include 233 U production by Pu-fueled transmuters (thermal or fast reactors) and reprocessing. A summary chapter presents the most significant conclusions from the study and recommends areas for future work

Heterogeneity in the 238U/235U Ratios of Angrites.

Science.gov (United States)

Tissot, F.; Dauphas, N.; Grove, T. L.

2016-12-01

Angrites are differentiated meteorites of basaltic composition, of either volcanic or plutonic origin, that display minimal post-crystallization alteration, metamorphism, shock or impact brecciation. Because quenched angrites cooled very rapidly, all radiochronometric systems closed simultaneously in these samples. Quenched angrites are thus often used as anchors for cross-calibrating short-lived dating methods (e.g., 26Al-26Mg) and the absolute dating techniques (e.g, Pb-Pb). Due to the constancy of the 238U/235U ratio in natural samples, Pb-Pb ages have long been calculated using a "consensus" 238U/235U ratio, but the discovery of resolvable variations in the 238U/235U ratio of natural samples, means that the U isotopic composition of the material to date also has to be determined in order to obtain high-precision Pb-Pb ages. We set out (a) to measure at high-precision the 238U/235U ratio of a large array of angrites to correct their Pb-Pb ages, and (b) to identify whether all angrites have a similar U isotopic composition, and, if not, what were the processes responsible for this variability. Recently, Brennecka & Wadhwa (2012) suggested that the angrite-parent body had a homogeneous 238U/235U ratio. They reached this conclusion partly because they propagated the uncertainties of the U isotopic composition of the various U double spikes that they used onto the final 238U/235U ratio the sample. Because this error is systematic (i.e., it affects all samples similarly), differences in the δ238U values of samples corrected by the same double spike are better known than one would be led to believe if uncertainties on the spike composition are propagated. At the conference, we will present the results of the high-precision U isotope analyses for six angrite samples: NWA 4590, NWA 4801, NWA 6291, Angra dos Reis, D'Orbigny, and Sahara 99555. We will show that there is some heterogeneity in the δ238U values of the angrites and will discuss the possible processes by

Influence of soil texture on the distribution and availability of 238U, 230Th, and 226Ra in soils

International Nuclear Information System (INIS)

Blanco Rodriguez, P.; Vera Tome, F.; Lozano, J.C.; Perez-Fernandez, M.A.

2008-01-01

The influence of soil texture on the distribution and availability of 238 U, 230 Th, and 226 Ra in soils was studied in soil samples collected at a rehabilitated uranium mine located in the Extremadura region in south-west Spain. The activity concentration (Bq kg -1 ) in the soils ranged from 60 to 750 for 238 U, from 60 to 260 for 230 Th, and from 70 to 330 for 226 Ra. The radionuclide distribution was determined in three soil fractions: coarse sand (0.5-2 mm), medium-fine sand (0.067-0.5 mm), and silt and clay ( 238 U, 230 Th, and 226 Ra between the activity concentration per fraction and the total activity concentration in the bulk soil. Thus, from the determination of the activity concentration in the bulk soil, one could estimate the activity concentration in each fraction. Correlations were also found for 238 U and 226 Ra between the labile activity concentration in each fraction and the total activity concentration in bulk soil. Assuming that there is some particle-size fraction that predominates in the process of soil-to-plant transfer, the parameters obtained in this study should be used as correction factors for the transfer factors determined from the bulk soil in previous studies

Disequilibria in the disintegration series of U and Th and chemical parameters in thermal spring waters from the Tatun volcanic area (Taiwan)

International Nuclear Information System (INIS)

Lin Chunchih; Chu Tiehchi; Huang Yufen

2003-01-01

The activity concentrations of 238 U, 234 U, 230 Th, 226 Ra, 232 Th, and 228 Th in thermal spring waters in the Tatun volcanic area were determined. Parameters including acidity, Cl - and SO 4 2- concentrations in spring waters at the sampling sites have been investigated to allow interpretation of the migration of the radionuclides, and to elucidate the influence of these parameters on the variations of radionuclide contents. Radioactive disequilibria were found in uranium and thorium series in thermal spring waters. The contents of uranium and thorium decreased with increasing pH. The ratios of 230 Th/ 234 U, 226 Ra/ 230 Th and 228 Th/ 232 Th show significant disequilibria. The 226 Ra/ 230 Th ratio (0.60-34.8) decreased with the Cl - or SO 4 2- concentration. All 228 Th/ 232 Th ratios (1.01-9.49) deviated from unity due to the co-precipitation of 228 Ra with barium and lead sulfate. (orig.)

The metrological activity determination of 238 U and 230 Th by gamma spectrometry to industrial fuel-cycle application

International Nuclear Information System (INIS)

Almeida M, M.C. de; Delgado, J.U.; Poledna, R.

2006-01-01

This work describes the difficulty for determining the activity of 238 U and 230 Th using gamma spectrometry due to the low gamma-ray emission probabilities of 92 and 67 keV, and, mainly, the associated high uncertainties about 13 and 11%, respectively. 230 Th is a 238 U daughter and it is product from uranium mills and refineries. 230 Th decays to 226 Ra and this decay has to be measured because these radionuclides are not in secular equilibrium with their daughter products, besides the gamma-energies have high uncertainties in the emission probabilities. These radionuclides, mostly 238 U, are important in the nuclear fuel-cycle, since the mining of uranium ore, where the nominal isotopic content of natural uranium is 99.27% of 238 U, until the irradiated fuel reprocessing, where this isotope, a fertile material, is recovered to be used again. The uranium and thorium are considered safeguarded nuclear materials and the metrology tries to calibrate and standardize these materials to improve the activity determination techniques applied in different fuel-cycle scopes. The essential characteristics of the safeguarded materials are low gamma energies (less than 100 keV) and emission probabilities but with high uncertainties. In this way, the metrology can contribute to homeland security defense against illicit nuclear trafficking with the identification and quantification of the safeguarded radionuclides such as uranium and thorium, using specific gamma window energy and high resolution planar or coaxial germanium detector. The efficiency curve is obtained from the reference source spectrum considering the photopeak areas corresponding the standard activities. This curve depends on radiation energy, sample geometry, photon attenuation (sample absorption and material absorption between sample-detector), dead time and sample-detector position. The metrological activity determinations of 238 U solid sources, and of 230 Th, in solution (5 ml flask), were performed using

Interim assessment of the denatured /sup 233/U fuel cycle: feasibility and nonproliferation characteristics

Energy Technology Data Exchange (ETDEWEB)

Abbott, L.S.; Bartine, D.E.; Burns, T.J. (eds.)

1978-12-01

A fuel cycle that employs /sup 233/U denatured with /sup 238/U and mixed with thorium fertile material is examined with respect to its proliferation-resistance characteristics and its technical and economic feasibility. The rationale for considering the denatured /sup 233/U fuel cycle is presented, and the impact of the denatured fuel on the performance of Light-Water Reactors, Spectral-Shift-Controlled Reactors, Gas-Cooled Reactors, Heavy-Water Reactors, and Fast Breeder Reactors is discussed. The scope of the R, D and D programs to commercialize these reactors and their associated fuel cycles is also summarized and the resource requirements and economics of denatured /sup 233/U cycles are compared to those of the conventional Pu/U cycle. In addition, several nuclear power systems that employ denatured /sup 233/U fuel and are based on the energy center concept are evaluated. Under this concept, dispersed power reactors fueled with denatured or low-enriched uranium fuel are supported by secure energy centers in which sensitive activities of the nuclear cycle are performed. These activities include /sup 233/U production by Pu-fueled transmuters (thermal or fast reactors) and reprocessing. A summary chapter presents the most significant conclusions from the study and recommends areas for future work.

Sources of neutronics data involving thorium of 233U and light water moderation

International Nuclear Information System (INIS)

Davenport, L.C.

1978-11-01

A literature search has been conducted to locate sources of neutronics data for light water moderated systems which contain thorium and/or uranium-233. It is concluded that insufficient data is currently available to validate neutronics design methods for licensing the 233 UO 2 -ThO 2 fuel cycle in light water reactors. A summary of the neutronics data sources found is reported in this document. These sources include critical and exponential experiments with lattices of fuel rods containing 233 U + Th or 235 U + Th. A few experiments using homogeneous aqueous solutions of 233 UO 2 (NO 3 ) 2 or 233 UO 2 F 2 are also included. The only critical lattice data using both 233 U and Th came from the LWBR program. All these experiments were zoned radially and in most cases axially also. Geometrically clean lattice critical data were measured for the CETR and TUPE programs. Both series used 235 UO 2 -ThO 2 pellets. A series of 21 exponential experiments using 3% 233 UO 2 - 97% ThO 2 fuel vibratory compacted to 92% of theoretical density in Zircaloy-2 tubing was performed at BNL using both unpoisoned and boric acid poisoned H 2 O moderator. For completeness, homogeneous systems are listed in which basic neutronics data have been measured. However, it is expected that most data concerning homogeneous systems will be applied to criticality safety problems rather than neutronics methods validation

U-series radioactive disequilibria 238U-230Th-226Ra: discussions on sources and processes responsible for volcanism of the Andean cordillera and on the deglaciation in Iceland

International Nuclear Information System (INIS)

Chmeleff, J.

2005-10-01

Thanks to precise analyses of uranium series radioactive disequilibria, permitted by improvements of mass spectrometry data acquisition and optimization of chemistry, two questions were tackled and answers about the periods of glaciation in Iceland and the petrogenesis of Andean lavas were proposed. Two methods were used to date lava flows from the Reykjanes peninsula and the island of Heimaey, in Iceland, directly linked to the periods of deglaciation or reheating around the last ice age. An original method based on the use of segregation veins present in the lava flows has been developed. Thanks to the formation of this particular geological object this methods permits to be freed from xeno-crystals when using the internal isochron method in the 238 U- 230 Th system. Using this method some constraints are brought both on the quaternary geology of the area of Reykjavik and on the age of the end of the Wurm glaciation on Heirnaey. In parallel, due to the homogeneity of the historical and Holocene lavas of the Reykjanes peninsula, regarding the ( 230 Th/ 232 Th) and Th/U ratios, it is possible to derive the ( 230 Th/ 232 Th) ratio in time to determine the age of lava flows installed during the ice age. Thus we confirmed that the magnetic excursion recorded in the Skalamaelifell lava flow is most probably the same one as that of Laschamp-Olby and that at this time (approximately 48.000 years) the Reykjanes peninsula was entirely covered with a glacier. Thanks to this method the extent of the glacier was also constrained by dating of a picritic shield around 22.000 years, thus the peninsula has to be free of any ice cap despite the fact that glaciation is the most intense around this time.Then Andean arc magmas petrogenesis was constrained in time and space. Almost systematic excesses of 226 Ra compared to 230 Th in lavas of austral, southern and northern volcanic zones of the Andes (AVZ, SVZ and NVZ) constrain the ascending time from the source to the surface after

Magmatic evolution of a volcano studied by 230Th-238U disequilibrium and trace elements systematics: the Etna case

International Nuclear Information System (INIS)

Condomines, M.; Allegre, C.J.; Tanguy, J.C.; Kieffer, G.

1982-01-01

Age determinations of several lava flows from Etna through 230 Th- 238 U disequilibrium (internal isochrons) yield a precise chronology of the volcano's history for the last 200,000 years, and emphasize the main episodes in the formation of this huge complex strato-volcano. Study of ( 230 Th/ 232 Th) 0 initial ratios of lavas together with their trace-element compositions yields a consistent model of magmatic evolution implying the existence, for 200,000 years, of a deep reservoir of alkalic magma periodically mixed with magmas of tholeiitic affinity. These short periods of mixing appear to be related to the formation of the large calderas of Etna. In addition to these processes affecting the deep reservoir, fractional crystallization also occurred in more superficial levels of the volcanic edifice, thereby yielding several series of differentiation of relatively short duration. As for its geochemistry, Etna's volcanism is of oceanic type but with its own characteristics and in a peculiar geodynamic context, at the edge of the African Plate. (author)

Discriminating assimilants and decoupling deep- vs. shallow-level crystal records at Mount Adams using 238U-230Th disequilibria and Os isotopes

Science.gov (United States)

Jicha, B.R.; Johnson, C.M.; Hildreth, Wes; Beard, B.L.; Hart, G.L.; Shirey, S.B.; Singer, B.S.

2009-01-01

A suite of 23 basaltic to dacitic lavas erupted over the last 350??kyr from the Mount Adams volcanic field has been analyzed for U-Th isotope compositions to evaluate the roles of mantle versus crustal components during magma genesis. All of the lavas have (230Th/238U) > 1 and span a large range in (230Th/232Th) ratios, and most basalts have higher (230Th/232Th) ratios than andesites and dacites. Several of the lavas contain antecrysts (crystals of pre-existing material), yet internal U-Th mineral isochrons from six of seven lavas are indistinguishable from their eruption ages. This indicates a relatively brief period of time between crystal growth and eruption for most of the phenocrysts (olivine, clinopyroxene, plagioclase, magnetite) prior to eruption. One isochron gave a crystallization age that is ~ 20-25??ka older than its corresponding eruptive age, and is interpreted to reflect mixing of older and juvenile crystals or a protracted period of magma storage in the crust. Much of the eruptive volume since 350??ka consists of lavas that have small to moderate 230Th excesses (2-16%), which are likely inherited from melting of a garnet-bearing intraplate ("OIB-like") mantle source. Following melt generation and subsequent migration through the upper mantle, most Mt. Adams magmas interacted with young, mafic lower crust, as indicated by 187Os/188Os ratios that are substantially more radiogenic than the mantle or those expected via mixing of subducted material and the mantle wedge. Moreover, Os-Th isotope variations suggest that unusually large 230Th excesses (25-48%) and high 187Os/188Os ratios in some peripheral lavas reflect assimilation of small degree partial melts of pre-Quaternary basement that had residual garnet or Al-rich clinopyroxene. Despite the isotopic evidence for lower crustal assimilation, these processes are not generally recorded in the erupted phenocrysts, indicating that the crystal record of the deep-level 'cryptic' processes has been

Effects on elevating cancer risk in population exposed to natural radionuclide 226Ra if parent radionuclide 238U is entered the body by inhalation or ingestion

International Nuclear Information System (INIS)

Zupunski, Lj.; Trobok, M.; Gordanic, V.; Spasic-Jokic, V.; Sovilj, P.

2009-01-01

People have always been exposed to ionizing radiation originating from natural radionuclides including 238 U, 40 K, 232 Th that exist in earths crust. Although received doses are small, due to the fact that threshold does not exist, there is a certain risk of developing cancer. Purpose of this study was to measure 238 U concentrations in soil of Bela Crkva territory. Based on these measurements, risks of developing cancers are calculated using Monte Carlo method.(author) [sr

Options for the deduction of target and intervention values for radon precursors of the 238U- and 232Th-series in soils

International Nuclear Information System (INIS)

Stoop, P.; Lembrechts, J.

1993-04-01

Radiation protection policy in the Netherlands applies to human activities in which ionizing radiation presents a hazard, not to naturally occurring sources of radiation. The risk levels (maximum permissible risk and negligible risk) apply to sources of radiation that cause an additional risk. Translation of these levels into practical environmental quality objectives therefore implies that both the extent and the origin of the risk are determined. The distinction between the natural and the additional radiation dose is of particular interest. In this report various possibilities are described for measuring, explaining and predicting the naturally occurring concentrations of the precursors of the element radon in the two radioactive decay series starting with 238 U and 232 Th. Several methods are given that may be used to derive environmental quality objectives for the soil with respect to these radionuclides. These environmental quality objectives are an important basis for among other things the soil sanitation policy. The nature of the radionuclides considered may have consequences for the choice of sanitation techniques. Because possible sources and cases of soil pollution may have important consequences for the Dutch policy on soil sanitation, a short overview is given of data published on these subjects. The foundation and the control of intervention levels requires insight in the relative importance of pollution pathways. As a result, pathways have been given ample attention. 9 figs., 17 tabs., 66 refs

Coulomb effects in isobaric cold fission from reactions 233U(nth,f), 235U(nth,f),239Pu(nth,f) and 252Cf(sf)

International Nuclear Information System (INIS)

Montoya, Modesto

2013-01-01

The Coulomb effect hypothesis, formerly used to interpret fluctuations in the curve of maximal total kinetic energy as a function of light fragment mass in reactions 233 U(n th ,f), 235 U(n th ,f) and 239 Pu(n th ,f), is confirmed in high kinetic energy as well as in low excitation energy windows, respectively. Data from reactions 233 U(n th ,f), 235 U(n th ,f), 239 Pu(n th ,f) and 252 Cf(sf) show that, between two isobaric fragmentations with similar Q-values, the more asymmetric charge split reaches the higher value of total kinetic energy. Moreover, in isobaric charge splits with different Q-values, similar preference for asymmetrical fragmentations is observed in low excitation energy windows. (author).

Thermal Stabilization of 233UO2, 233UO3, and 233U3O8

International Nuclear Information System (INIS)

Thein, S.M.; Bereolos, P.J.

2000-01-01

This report identifies an appropriate thermal stabilization temperature for 233 U oxides. The temperature is chosen principally on the basis of eliminating moisture and other residual volatiles. This report supports the U. S. Department of Energy (DOE) Standard for safe storage of 233 U (DOE 2000), written as part of the response to Recommendation 97-1 of the Defense Nuclear Facilities Safety Board (DNFSB), addressing safe storage of 233 U

Determination of U, Th and K in bricks by gamma-ray spectrometry, X-ray fluorescence analysis and neutron activation analysis

Science.gov (United States)

Bártová, H.; Kučera, J.; Musílek, L.; Trojek, T.; Gregorová, E.

2017-11-01

Knowledge of the content of natural radionuclides in bricks can be important in some cases in dosimetry and application of ionizing radiation. Dosimetry of naturally occurring radionuclides in matter (NORM) in general is one of them, the other one, related to radiation protection, is radon exposure evaluation, and finally, it is needed for the thermoluminescence (TL) dating method. The internal dose rate inside bricks is caused mostly by contributions of the natural radionuclides 238U, 232Th, radionuclides of their decay chains, and 40K. The decay chain of 235U is usually much less important. The concentrations of 238U, 232Th and 40K were measured by various methods, namely by gamma-ray spectrometry, X-ray fluorescence analysis (XRF), and neutron activation analysis (NAA) which was used as a reference method. These methods were compared from the point of view of accuracy, limit of detection (LOD), amount of sample needed and sample handling, time demands, and instrument availability.

Vertical and horizontal distribution of radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) in sediment from Manjung coastal water area Perak, Malaysia

Energy Technology Data Exchange (ETDEWEB)

Abdullah, Anisa, E-mail: coppering@ymail.com; Hamzah, Zaini; Wood, Ab. Khalik [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor (Malaysia); Saat, Ahmad [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor (Malaysia); Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

2016-01-22

Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides ({sup 232}Th, {sup 238}U and {sup 40}K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (I{sub geo}) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (H{sub ex})

Search for surviving actinides and superheavy nuclei in damped collisions of 238U with 238U and 248Cm

International Nuclear Information System (INIS)

Kratz, J.V.

1980-03-01

In the present talk aspects of the reaction mechanism related to the survival probability of the heaviest fragments in 238 U + 238 U collisions are discussed first. This is followed by a description of the experiments that have been performed to search for surviving superheavy fragments in the 238 U + 238 U reaction and by a presentation of the results obtained so far. In a third section our recent first attempts with the 238 U + 248 Cm reaction are described and preliminary results are discussed. (orig.)

Isotope shift of 234U, 236U, 238U in U I

International Nuclear Information System (INIS)

Gagne, J.M.; Nguyen Van, S.; Saint-Dizier, J.P.; Pianarosa, P.

1976-01-01

New and very accurate data of isotope shifts and relative isotope shifts in 234 U, 236 U, 238 U are presented. The invariance of the relative isotope shift, for the transitions we have investigated, supports the hypothesis that the so called specific mass effect is negligible in uranium

233U Assay A Neutron NDA System

International Nuclear Information System (INIS)

Hensley, D.C.; Lucero, A.J.; Pierce, L.

1998-01-01

The assay of highly enriched 233 U material presents some unique challenges. Techniques which apply to the assay of materials of Pu or enriched 235 U do not convert easily over to the assay of 233 U. A specialized neutron assay device is being fabricated to exploit the singles neutron signal, the weak correlated neutron signal, and an active correlated signal. These pieces of information when combined with γ ray isotopics information should give a good overall determination of 233 U material now stored in bldg. 3019 at the Oak Ridge National Laboratory

Accumulation of 226Ra, 238U and 230Th by wetland plants in a vicinity of U-mill tailings at Zirovski vrh (Slovenia)

International Nuclear Information System (INIS)

Marko Cerne; Borut Smodis; Marko Strok; Radojko Jacimovic

2010-01-01

The impact of a U-mill tailing on radionuclide accumulation by plants was assayed. In particular, a preliminary screening of 226 Ra, 238 U and 230 Th in Marsh marigold (Caltha palustris L.), soft rush (Juncus effusus L.) and Tall Moor grass (Molinia arundinacea (L.) Moench) grown in a marsh habitat is presented. Activity concentrations for the studied radionuclides and their transfer factors for the particular plants are shown and discussed. (author)

233U Assay A Neutron NDA System

Energy Technology Data Exchange (ETDEWEB)

Hensley, D.C.; Lucero, A.J.; Pierce, L.

1998-11-17

The assay of highly enriched {sup 233}U material presents some unique challenges. Techniques which apply to the assay of materials of Pu or enriched {sup 235}U do not convert easily over to the assay of {sup 233}U. A specialized neutron assay device is being fabricated to exploit the singles neutron signal, the weak correlated neutron signal, and an active correlated signal. These pieces of information when combined with {gamma} ray isotopics information should give a good overall determination of {sup 233}U material now stored in bldg. 3019 at the Oak Ridge National Laboratory.

Retention and translocation of inhaled uranyl nitrate (233U and 232U) in rats

International Nuclear Information System (INIS)

Ballou, J.E.; Gies, R.A.; Wogman, N.A.

1978-01-01

The uranium-thorium breeder reactors proposed for nuclear power production, and other thorium fuel systems in conventional reactors, utilize fuels and fuel recycle process solutions that have not been evaluated for biological hazard. This project emphasizes studies of the metabolism of the oxide fuels and the nitrate solutions of the major radionuclides, following inhalation, ingestion, or cutaneous application in rodents. Preliminary data are reported for the clearance of inhaled 233 UO 2 (NO 3 ) 2 and 232 UO 2 (NO 3 ) 2 from the lung and their translocation to skeleton

The metrological activity determination of {sup 238} U and {sup 230} Th by gamma spectrometry to industrial fuel-cycle application

Energy Technology Data Exchange (ETDEWEB)

Almeida M, M.C. de; Delgado, J.U.; Poledna, R. [Instituto de Radioprotecao e Dosimetria- IRD/SEMRA, CNEN, Av. Salvador Allende s/n, Recreio, CEP 22780-160, Rio de Janeiro (Brazil)]. e-mail: marcandida@yahoo.com.br

2006-07-01

This work describes the difficulty for determining the activity of {sup 238} U and {sup 230} Th using gamma spectrometry due to the low gamma-ray emission probabilities of 92 and 67 keV, and, mainly, the associated high uncertainties about 13 and 11%, respectively. {sup 230} Th is a {sup 238} U daughter and it is product from uranium mills and refineries. {sup 230} Th decays to {sup 226} Ra and this decay has to be measured because these radionuclides are not in secular equilibrium with their daughter products, besides the gamma-energies have high uncertainties in the emission probabilities. These radionuclides, mostly {sup 238} U, are important in the nuclear fuel-cycle, since the mining of uranium ore, where the nominal isotopic content of natural uranium is 99.27% of {sup 238} U, until the irradiated fuel reprocessing, where this isotope, a fertile material, is recovered to be used again. The uranium and thorium are considered safeguarded nuclear materials and the metrology tries to calibrate and standardize these materials to improve the activity determination techniques applied in different fuel-cycle scopes. The essential characteristics of the safeguarded materials are low gamma energies (less than 100 keV) and emission probabilities but with high uncertainties. In this way, the metrology can contribute to homeland security defense against illicit nuclear trafficking with the identification and quantification of the safeguarded radionuclides such as uranium and thorium, using specific gamma window energy and high resolution planar or coaxial germanium detector. The efficiency curve is obtained from the reference source spectrum considering the photopeak areas corresponding the standard activities. This curve depends on radiation energy, sample geometry, photon attenuation (sample absorption and material absorption between sample-detector), dead time and sample-detector position. The metrological activity determinations of {sup 238} U solid sources, and of

Nondestructive analysis for 232U and decay progeny in animal tissues

International Nuclear Information System (INIS)

Ballou, J.E.; Wogman, N.A.

1977-01-01

Direct determination of 232 U and its decay products in animal tissues appears to be feasible using an intrinsic Ge(Li) diode detector (for energies of 5-100 keV) and a NaI(Tl) anticoincidence-shielded Ge(Li) diode for higher-energy gamma photons. The detection sensitivity for 232 U and 228 Th is 0.03 and 0.01 nCi, respectively, using a 300-min counting time

Assay of Uranium Isotopic Ratios 234U/238U, 235U/238U in Bottom Sediment Samples Using Destructive and Non Destructive Techniques (Nasser Lake)

International Nuclear Information System (INIS)

Agha, A.R.; El-Mongy, S.A.; Kandel, A.E.

2011-01-01

Nasser Lake is the greatest man-made lake in the World. It is considered as the main source of water where the Nile water is impounded behind the Aswan high dam.. Uranium has three naturally occurring isotopes 234 U, 235 U and 238 U with isotopic abundance 0.00548, 0.7200 and 99.2745 atom percent. Dissolved uranium in the lake is primary due to weathering process. Monitoring of the isotopic ratios of uranium is used as a good indicator to trace and evaluate the origin and activities associated with any variation of uranium in the lake environment. The main objective of the present study is to clarify any potential variation of natural uranium 234 U/ 238 U, 235 U/ 238 U ratios in sediment samples of Nasser Lake by using destructive alpha and non destructive gamma- techniques. The results show that the uranium isotopic activity ratios are very close to the natural values. This study can also be used for radiological protection and safety evaluation purposes.

HI-resolution gamma spectrometry measurements of U-238, TH-232, K-40 and CS-137 concentrations in soil samples from Capao Island at CTEx

International Nuclear Information System (INIS)

Oliveira, Luciano S.R.; Oliveira, Celio J.V.; Vilela, Paulo R.T.; Vital, Helio C.

2013-01-01

Absolute soil concentrations of U-238, Th-232, K-40 and Cs-137 samples collected from Capao Island have been measured by using Hi-Resolution Gamma HPGe Spectrometry. The area of interest encompasses an embankment in a mangrove swamp in Guaratiba, Rio de Janeiro, where nuclear, chemical and biological defense laboratories of the Brazilian Army Technology Center (CTEx) are located. In order to ensure that no significant environmental impact has resulted from neutron physics experiments performed in a graphite subcritical assembly in addition to the operation of two cesium-driven irradiating facilities, routine monitoring of those isotopes have been regularly performed. A total of eight 250 ml samples of mangrove and embankment soils were extracted from four sites of known coordinates within an area of 300 x 300 m 2 and remained stored for a minimum thirty-day period to allow equilibrium to be reached. Collection and preparation of samples were made according to previously established procedures. High purity germanium detectors were used to obtain high-resolution gamma spectra and counting times were required to exceed 30 hours in order to yield sufficient statistical accuracy. Energy and efficiency calibration curves of the counting system were determined by using the GENIE 2000 software for analysis of the gamma spectrum generated by nine standard sources with a total of 11 peak energies ranging from 0.05 to 1.3 MeV. The results, corrected for background, have been expressed as absolute specific activities. All experiments have been made in the Laboratory for Identification of Radiological Agents (LIAR) at CTEx. No trace of cesium-137 has been found and the measured levels of uranium-238, in the order of 10 Bq/kg, are close to the global mean. However, some data have been found to slightly exceed the expected normal range for thorium-232 (60% of samples) and potassium-40 (20% of samples). Since there is no handling of those isotopes in the site or others that could

HI-resolution gamma spectrometry measurements of U-238, TH-232, K-40 and CS-137 concentrations in soil samples from Capao Island at CTEx

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Luciano S.R.; Oliveira, Celio J.V.; Vilela, Paulo R.T.; Vital, Helio C., E-mail: vital@ctex.eb.br [Centro Tecnologico do Exercito (DDQBN/CTEX), Rio de Janeiro, RJ (Brazil). Div. de Defesa Quimica, Biologica e Nuclear. Secao de Defesa Nuclear

2013-07-01

Absolute soil concentrations of U-238, Th-232, K-40 and Cs-137 samples collected from Capao Island have been measured by using Hi-Resolution Gamma HPGe Spectrometry. The area of interest encompasses an embankment in a mangrove swamp in Guaratiba, Rio de Janeiro, where nuclear, chemical and biological defense laboratories of the Brazilian Army Technology Center (CTEx) are located. In order to ensure that no significant environmental impact has resulted from neutron physics experiments performed in a graphite subcritical assembly in addition to the operation of two cesium-driven irradiating facilities, routine monitoring of those isotopes have been regularly performed. A total of eight 250 ml samples of mangrove and embankment soils were extracted from four sites of known coordinates within an area of 300 x 300 m{sup 2} and remained stored for a minimum thirty-day period to allow equilibrium to be reached. Collection and preparation of samples were made according to previously established procedures. High purity germanium detectors were used to obtain high-resolution gamma spectra and counting times were required to exceed 30 hours in order to yield sufficient statistical accuracy. Energy and efficiency calibration curves of the counting system were determined by using the GENIE 2000 software for analysis of the gamma spectrum generated by nine standard sources with a total of 11 peak energies ranging from 0.05 to 1.3 MeV. The results, corrected for background, have been expressed as absolute specific activities. All experiments have been made in the Laboratory for Identification of Radiological Agents (LIAR) at CTEx. No trace of cesium-137 has been found and the measured levels of uranium-238, in the order of 10 Bq/kg, are close to the global mean. However, some data have been found to slightly exceed the expected normal range for thorium-232 (60% of samples) and potassium-40 (20% of samples). Since there is no handling of those isotopes in the site or others that

Determination of natural radionuclides, U, Th-232, Ra-226, Ra-228, Pb-210 and K-40 in sediments from CananÉIa-Iguape System, Brazil

International Nuclear Information System (INIS)

Jesus, Gleyka J.D.; Chiozzini, Vitor G.; Saueia, Cátia H.R.; Nisti, Marcelo B.; Braga, Elisabete S.; Fávaro, Deborah I.T.; Universidade de São Paulo

2017-01-01

The Cananéia-Iguape estuarine-lagoon complex, located in the south of São Paulo State, Brazil, is a protected area recognized by UNESCO as part of the Biosphere Reserve, due to its importance as a natural ecosystem. However, along the years, the mining activities in the region affected the river basin, to such an extent that contamination was observed for As, Cu, Pb and Zn. Since the mining activities can also enhance the levels of natural radioactivity in the sediments, this study aimed to determine the activity concentration of the natural radionuclides (K-40, U, Ra-226, Pb-210, Th-232 and Ra-228) in 34 bottom sediments samples collected in the Cananéia-Iguape system. The samples were measured by gamma spectrometry, using a HPGe for the determination of K-40, Ra-226, Pb-210 and Ra-228. The concentration of U and Th-232 was determined by instrumental neutron activation analysis. The activity concentration of K-40 varied from 119 ± 17 to 522 ± 74 Bq kg"-"1; U-238 varied from 0.31 ± 0.05 to 5.8 ± 0.3 mg kg"-"1; Ra-226 varied from 3.7 ± 0.3 to 43.3 ± 1.5 Bq kg"-"1; Pb-210 varied from 5.8 ± 2.6 to 118 ± 12 Bq kg"-"1; Th-232 varied from 0.67 ± 0.02 to 16.6 ± 0.4 mg kg"-"1 and Ra-228 varied from 3.5 ± 0.6 to 64.9 ± 2.4 Bq kg"-"1. These results were compared with literature values for the region, indicating that they are the background of the region and no contamination was observed from NORM (Naturally Occurring Radioactive Material) industries. (author)

Determination of natural radionuclides, U, Th-232, Ra-226, Ra-228, Pb-210 and K-40 in sediments from CananÉIa-Iguape System, Brazil

Energy Technology Data Exchange (ETDEWEB)

Jesus, Gleyka J.D.; Chiozzini, Vitor G.; Saueia, Cátia H.R.; Nisti, Marcelo B.; Braga, Elisabete S.; Fávaro, Deborah I.T., E-mail: gjdjesus@ipen.br, E-mail: chsaueia@ipen.br, E-mail: mbnisti@ipen.br, E-mail: defavaro@ipen.br, E-mail: vitor.chio@usp.br, E-mail: edsbraga@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Universidade de São Paulo (USP), SP (Brazil). Instituto Oceanográfico

2017-07-01

The Cananéia-Iguape estuarine-lagoon complex, located in the south of São Paulo State, Brazil, is a protected area recognized by UNESCO as part of the Biosphere Reserve, due to its importance as a natural ecosystem. However, along the years, the mining activities in the region affected the river basin, to such an extent that contamination was observed for As, Cu, Pb and Zn. Since the mining activities can also enhance the levels of natural radioactivity in the sediments, this study aimed to determine the activity concentration of the natural radionuclides (K-40, U, Ra-226, Pb-210, Th-232 and Ra-228) in 34 bottom sediments samples collected in the Cananéia-Iguape system. The samples were measured by gamma spectrometry, using a HPGe for the determination of K-40, Ra-226, Pb-210 and Ra-228. The concentration of U and Th-232 was determined by instrumental neutron activation analysis. The activity concentration of K-40 varied from 119 ± 17 to 522 ± 74 Bq kg{sup -1}; U-238 varied from 0.31 ± 0.05 to 5.8 ± 0.3 mg kg{sup -1}; Ra-226 varied from 3.7 ± 0.3 to 43.3 ± 1.5 Bq kg{sup -1}; Pb-210 varied from 5.8 ± 2.6 to 118 ± 12 Bq kg{sup -1}; Th-232 varied from 0.67 ± 0.02 to 16.6 ± 0.4 mg kg{sup -1} and Ra-228 varied from 3.5 ± 0.6 to 64.9 ± 2.4 Bq kg{sup -1}. These results were compared with literature values for the region, indicating that they are the background of the region and no contamination was observed from NORM (Naturally Occurring Radioactive Material) industries. (author)

Activity disequilibrium between 234U and 238U isotopes in natural environment

OpenAIRE

Bory?o, Alicja; Skwarzec, Bogdan

2014-01-01

The aim of this work was to calculate the values of the 234U/238U activity ratio in natural environment (water, sediments, Baltic organisms and marine birds from various regions of the southern Baltic Sea; river waters (the Vistula and the Oder River); plants and soils collected near phosphogypsum waste heap in Wi?linka (Northern Poland) and deer-like animals from Northern Poland. On the basis of the studies it was found that the most important processes of uranium geochemical migration in th...

Bi-stability in accelerator driven 233U breeders

International Nuclear Information System (INIS)

Ghosh, Biplab; Degweker, S.B.

2011-01-01

Research on Accelerator Driven Systems (ADSs) is being carried out around the world primarily with the objective of waste transmutation. Presently, the volume of waste in India is small and therefore there is little incentive to develop ADS based waste transmutation technology immediately. On the other hand, the indigenous U availability is limited and hence there is a strong incentive for breeding. Moreover the large Th deposits in the country provide a clear incentive to develop Th related technologies. Th has the additional advantage that it produces very little trans-uranic waste. While Pu fuelled fast reactors using advanced metallic fuel can have high breeding ratios due to the hard spectrum in such reactors, Th fuelled critical reactors can at best be self sustaining or marginal breeders. A possible way to improve the breeding of Th fueled reactors is to use an external neutron source as is done in ADSs. ADSs can not only give improved breeding but also permit greater flexibility in type of fuel that may be used and have the potential to considerably simplify the Th fuel cycle as in the case of the Th burner. In this paper we study various issues associated with breeding in ADSs such as the energy economics of breeding in ADSs using various types of neutron sources and the effect of the reactor spectrum and the discharge fluence (or irradiation time) of the fuel on the breeding performance. We show that even with non-fissioning, non-power- producing targets such as Pb or LBE it is possible to choose the fuel irradiation time so that the breeder produces sufficient power to drive the accelerator and export the balance to the grid, without significantly diminishing the 233 U breeding rate. By increasing the discharge fluence (irradiation time) it is possible to increase the power. However, the 233 U production rate falls off rapidly to about half its maximum value. This is the Th burner region. As the equations governing the breeding process are non

Optimization of binary breeder reactor IV - Conception of mixed fuel at central part of the core

International Nuclear Information System (INIS)

Dias, A.F.; Ishiguro, Y.

1986-04-01

Neutronic characteristics of some LMFBRs are analized for a fueling mode that is different from those reported previously. In an inner part of the core both 233 U/ 232 Th and Pu/U assemblies are placed while the outer zone is fueled with Pu/U assemblies. Both oxide metal fuels and 232 Th and 238 U blankets are considered. (Author) [pt

Using {sup 233}U-doped crystals to access the few-eV isomeric transition in {sup 229}Th

Energy Technology Data Exchange (ETDEWEB)

Stellmer, Simon; Schreitl, Matthias; Kazakov, Georgy A.; Sterba, Johannes H.; Schumm, Thorsten [Vienna Center for Quantum Science and Technology (VCQ) and Atominstitut, TU Wien, Vienna (Austria)

2016-07-01

The isotope {sup 229}Th possesses an exceptionally low-lying isomeric state at an energy of only a few eV. While direct laser excitation of the isomer is a tantalizing future prospect, the stage is not yet set for nuclear laser spectroscopy: too little is known about the energy, lifetime, and internal conversion pathways of the isomer. Alternative routes to populate the isomer are needed for further investigations. We use the alpha decay {sup 233}U →{sup 229g,m}Th to populate the isomer with a probability of 2%. The {sup 233}U is embedded into VUV-transparent crystals, as the isomer transition is expected around 160 nm. The wavelength of the gamma ray, emitted upon de-excitation of the isomer into the ground state, is measured with a spectrometer. Calculations show that the isomer emission is not obscured by radioluminescence of the crystal. We report on the current status of the experiment.

Strategy for the future use and disposition of Uranium-233: History, inventories, storage facilities, and potential future uses

International Nuclear Information System (INIS)

Bereolos, P.J.; Lewis, L.C.

1998-06-01

This document provides background information on the man-made radioisotope 233 U. It is one of a series of four reports that map out potential national strategies for the future use and disposition of 233 U pending action under the National Environmental Policy Act (NEPA). The scope of this report is separated 233 U, where separated refers to nonwaste 233 U or 233 U that has been separated from fission products. Information on other 233 U, such as that in spent nuclear fuel (SNF), is included only to recognize that it may be separated at a later date and then fall under the scope of this report. The background information in this document includes the historical production and current inventory of 233 U, the uses of 233 U, and a discussion of the available facilities for storing 233 U. The considerations for what fraction of the current inventory should be preserved for future use depend on several issues. First, 233 U always contains a small amount of the contaminant isotope 232 U. The decay products of 232 U are highly radioactive and require special handling. The current inventory has a variety of qualities with regard to 232 U content, ranging from 1 to about 200 ppm (on a total uranium basis). It is preferable to use 233 U with the minimum amount of 232 U in all applications. The second issue pertains to other isotopes of uranium mixed in with the 233 U, specifically 235 U and 238 U. A large portion of the inventory has a high quantity of 235 U associated with it. The presence of bulk amounts of 235 U complicates storage because of the added volume needing safeguards and criticality controls. Isotopic dilution using DU may remove safeguards and criticality concerns, but it increases the overall mass and may limit applications that depend on the fissile nature of 233 U. The third issue concerns the packaging of the material. There is no standard packaging (although one is being developed); consequently, the inventory exists in a variety of packages. For some

Determination of natural radionuclides from 238U and 232Th series, trace and major elements in sediment cores from baixada Santista and evaluation of impacted areas

International Nuclear Information System (INIS)

Damatto, Sandra Regina

2010-01-01

Baixada Santista is the region of higher population of the coast of Sao Paulo State, where it is located the largest port in Latin America, in the city of Santos, and the most important industrial complex of Latin America, in the city of Cubatao. This region has received in recent years a considerable load of industrial and domestic effluents in its water bodies, as a direct result of the industrial and port activities and the large population growth in recent decades, and is considered nowadays highly impacted. In the present study sediment cores were collected in the estuary of Santos-Cubatao, in the estuary of Sao Vicente, in the channel of Bertioga and Santos Bay, in order to determine the concentration of trace and major elements and natural radionuclides from the 238 U and 232 Th series. The techniques used were neutron activation analysis, X-ray fluorescence and gamma spectrometry, respectively. The obtained values for the elements Cr, Sb, Ta and Zn in some cores, are higher than data from literature, and can indicate a possible anthropic contribution. Comparing the obtained values of Cr and Zn elements determined in the sediment cores with the values of TEL and PEL index for sediment quality, it was verified that the studied region presents Cr levels higher than TEL in Santos-Cubatao estuary and Bertioga channel and Zn element presented values higher than TEL for some core slices of Santos-Cubatao estuary, for one core of Sao Vicente estuary, one core in Bertioga channel and Santos Bay. For the other elements, the values obtained in this study can be considered as reference values for the region. Although the element As presented higher values than the TEL in all the studied environments, the concentrations obtained are of the same order of magnitude as literature data and, therefore, can be considered also as reference values for the region. No enrichment was found for the major elements in all the ecosystems studied, with the exception for the element P

Study of the variation with the energy of the fission cross-sections of {sup 233}U, {sup 235}U, {sup 239}Pu for the fast neutrons; Etude de la variation avec l'energie des sections efficaces de fission de {sup 233}U, {sup 235}U, {sup 239}Pu pour les neutrons rapides

Energy Technology Data Exchange (ETDEWEB)

Szteinsznaider, D; Naggiar, V; Netter, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

This measurements have been done while taking the value of the fission cross-sections of {sup 238}U as reference. The neutrons are produced by the reaction {sup 7}Li(p,n) in the Van de Graaff generator of Saclay. The explored domain spreads from some tenths to 2000 keV. We find: for {sup 239}Pu: {sigma}{sub f} = 2,04 {+-} 0,12 barns, cross-section constant between 150 and 2000 keV, for {sup 235}U: {sigma}{sub f} = 1,15 {+-} 0,15 barns, cross-section constant between 700 and 1000 keV, for {sup 233}U: {sigma}{sub f} = 1,92 {+-} 0,25 barns, for neutrons of 850 keV. (authors) [French] Ces mesures ont ete effectuees en prenant la valeur de la section efficace de fission de {sup 238}U comme reference. Les neutrons sont produits par la reaction {sup 7}Li(p,n) au generateur Van de Graaff de Saclay. Le domaine explore s'etend de quelques dizaines de kev a 2000 kev. Nous trouvons: pour {sup 239}Pu: {sigma}{sub f} = 2,04 {+-} 0,12 barns, section efficace constante entre 150 et 2000 kev. pour {sup 235}U: {sigma}{sub f} = 1,15 {+-} 0,15 barns, section efficace constante entre 700 et 1000 kev. pour {sup 233}U: {sigma}{sub f} = 1,92 {+-} 0,25 barns, pour des neutrons de 850 kev. (auteurs)

Microscopic structure of superdeformed states in Th, U, Pu and Cm isotopes with Gogny force

International Nuclear Information System (INIS)

Girod, M.; Delaroche, J.P.; Romain, P.; Libert, J.

2002-01-01

The structure properties of the even-even nuclei 226, 228, 230, 232, 234 Th, 230, 232, 234, 236, 238, 240 U, 240, 242, 244, 246 Pu, and 242, 244, 246, 248 Cm have been investigated at normal and superdeformed shapes in microscopic mean-field calculations based on Gogny force. Collective levels are predicted from constrained Hartree-Fock-Bogoliubov and configuration mixing calculations. Two quasiparticle states are also predicted from blocking calculations for neutron and proton configurations. Predictions are shown and compared with experimental data at superdeformed shapes. (orig.)

Review of thorium-U233 cycle thermal reactor benchmark studies (AWBA Development Program)

International Nuclear Information System (INIS)

Ullo, J.J.; Hardy, J. Jr.; Steen, N.M.

1980-03-01

A survey is made of existing integral experiments for U233 systems and thorium-uranium based fuel systems. The aim is to understand to what extent they give a consistent test of ENDF/B-IV nuclear data. A principal result is that ENDF/B-IV leads to an underprediction of neutron leakage. Results from testing alternate thorium data sets are presented. For one evaluation due to Leonard, the results depict a possible growing discrepancy between measured integral parameters such as rho 02 and I 232 and the differential data, which underpredicts these parameters. Sensitivities to other nuclear data components, notably the fission neutron spectrum, were determined. A new harder U233 spectrum significantly reduces a bias trend in K/sub eff/ vs leakage

Sequential determination of natural ({sup 232}Th, {sup 238}U) and anthropogenic ({sup 137}Cs, {sup 90}Sr, {sup 241}Am, {sup 239+240}Pu) radionuclides in environmental matrix

Energy Technology Data Exchange (ETDEWEB)

Michel, H.; Levent, D.; Barci, V.; Barci-Funel, G.; Hurel, C. [Laboratoire de Radiochimie, Sciences Analytiques et Environnement (LRSAE), Universite de Nice Sophia-Antipolis 06108 Nice Cedex (France)

2008-07-01

A new sequential method for the determination of both natural (U, Th) and anthropogenic (Sr, Cs, Pu, Am) radionuclides has been developed for application to soil and sediment samples. The procedure was optimised using a reference sediment (IAEA-368) and reference soils (IAEA-375 and IAEA-326). Reference materials were first digested using acids (leaching), 'total' acids on hot plate, and acids in microwave in order to compare the different digestion technique. Then, the separation and purification were made by anion exchange resin and selective extraction chromatography: Transuranic (TRU) and Strontium (SR) resins. Natural and anthropogenic alpha radionuclides were separated by Uranium and Tetravalent Actinide (UTEVA) resin, considering different acid elution medium. Finally, alpha and gamma semiconductor spectrometer and liquid scintillation spectrometer were used to measure radionuclide activities. The results obtained for strontium-90, cesium-137, thorium-232, uranium- 238, plutonium-239+240 and americium-241 isotopes by the proposed method for the reference materials provided excellent agreement with the recommended values and good chemical recoveries. (authors)

U-series dating using thermal ionisation mass spectrometry (TIMS)

International Nuclear Information System (INIS)

McCulloch, M.T.

1999-01-01

U-series dating is based on the decay of the two long-lived isotopes 238 U(τ 1/2 =4.47 x 10 9 years) and 235 U (τ 1/2 0.7 x 10 9 years). 238 U and its intermediate daughter isotopes 234 U (τ 1/2 = 245.4 ka) and 230 Th (τ 1/2 = 75.4 ka) have been the main focus of recently developed mass spectrometric techniques (Edwards et al., 1987) while the other less frequently used decay chain is based on the decay 235 U to 231 Pa (τ 1/2 = 32.8 ka). Both the 238 U and 235 U decay chains terminate at the stable isotopes 206 Pb and 207 Pb respectively. Thermal ionization mass spectrometry (TIMS) has a number of inherent advantages, mainly the ability to measure isotopic ratios at high precision on relatively small samples. In spite of these now obvious advantages, it is only since the mid-1980's when Chen et al., (1986) made the first precise measurements of 234 U and 232 Th in seawater followed by Edwards et al., (1987) who made combined 234 U- 230 Th measurements, was the full potential of mass spectrometric methods first realised. Several examples are given to illustrate various aspects of TIMS U-series

Mass distributions in monoenergetic-neutron-induced fission of 232Th

International Nuclear Information System (INIS)

Glendenin, L.E.; Gindler, J.E.; Ahmad, I.; Henderson, D.J.; Meadows, J.W.

1980-01-01

Fission product yields for 38 masses were determined for the fission of 232 Th with essentially monoenergetic neutrons of 2.0, 3.0, 4.0, 5.9, 6.4, 6.9, 7.6, and 8.0 MeV. Fission product activities were measured by Ge(Li) γ-ray spectrometry of irradiated 232 Th foils and by chemical separation of the fission product elements followed by β counting. The mass yield data for 232 Th(n,f ) show a sensitive increase of fission yields in the near-symmetric mass region (valley) with increasing incident neutron energy E/sub n/ and a pronounced dip in yield at the onset of second-chance fission just above the neutron binding energy (at approx. 6 MeV) where the excitation energy is lowered by competition with neutron evaporation prior to fission. The effect of second-chance fission is also seen in the yields of asymmetric peak products. A distinct third peak is observed at symmetry in the valley of the mass distribution, and enhanced yields are observed in the asymmetric peaks at masses associated with even Z (proton pairing effect). The fission yeilds of 232 Th(n,f ) are compared with those of 238 U(n,f ) and 232 Th

Distribution of uranium-238 in environmental samples from a residential area impacted by mining and milling activities

International Nuclear Information System (INIS)

McConnell, M.A.; Ramanujam, V.M.S.; Alcock, N.W.; Gabehart, G.J.; Au, W.W.

1998-01-01

The northern region of Karnes County, Texas, USA, has been the site of extensive mining/milling of uranium for over 30 years. A previous study in their laboratory indicates that residents living near these facilities have increased chromosomal aberrations and a reduced DNA repair capacity. In this study, the long-lived radionuclides uranium-238 ( 238 U) and thorium-232 ( 232 Th) were measured in order to evaluate the extent of contamination from mining/milling facilities. 232 Th was quantified simultaneously and served as a reference. Soil samples were collected from the yards of previously studied households and adjacent areas near former mining and mining/milling sites at the surface and 30 cm subsurface. Additionally, samples from drinking water wells were collected from selected households. Sites located over 14 km from the study area with no known history of mining/milling served as the control. In the control area, 238 U concentrations in soil were consistent between surface (0.13--0.26 mg/kg) and subsurface samples. Near mining/milling sites, 238 U in surface soil was found to be consistently and statistically higher than corresponding subsurface samples. Near mining-only areas, 238 U in surface soil, however, was not significantly increased over subsurface soil. As expected, 238 U was much higher overall in the mining/milling and mining-only areas compared to the control sites. No trends were detected in the distribution of 232 Th. The concentration of 238 U was up to six times higher in a drinking water well near a former mining/milling operation, indicating possible leaching into the groundwater, while 232 Th concentrations were low and uniform. Furthermore, lead isotope ratio analysis indicates contamination from the interstate shipping of ore by rail to and from a mining/milling facility. These data indicate contamination of the environment by the mining/milling activities in a residential area

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

Distribution of naturally occurring radionuclides (U, Th) in Timahdit's black shale (Morocco)

International Nuclear Information System (INIS)

Galindo, C.; Mougin, L.; Nourreddine, A.; Fakhi, S.

2006-01-01

Attention has been recently focused on the use of Moroccan's black shale as the raw material for production of a new type of adsorbents. The purpose of the present work was to characterize a black shale specimen, collected in the region of Timahdit, in terms of the total uranium and thorium contents, measurements of some geochemically important elements (Al, Fe, Si, K, Mn, P, Ca), and XRD/SEM analysis. Selective leaching procedure, followed by radiochemical purification and alpha-counting, was also performed to assess the distribution of 238 U, 234 U, 235 U, 232 Th, 228 Th, 230 Th in the main structures. It was found that calcite, dolomite, quartz, clays constitute the main bulk composition of inorganic matrix. Organic matter counts for at least 15 wt. % of the sample. As in most other organic rich rocks, uranium is highly enriched in the black shale. It was interpreted to have been concentrated over a long period of time under anaerobic environment. This actinide is associated predominantly with humic acids, the precursor of kerogen. An integrated isotopic approach points out its mobilization from these humic acids to carbonates and apatite phases. The radionuclide that is the less mobile in this environment is 232 Th, as was expected from its chemical properties, and in agreement with the most common view in the literature. It is partitioned between silicate minerals (49%), pyrite and kerogen (51%). Speciation, chemical behaviour of uranium and thorium and alpha decay related processes are widely responsible for disequilibria in the uranium decay series. (author)

Concentrations and biological availability of 238U and 230Th in the environs of a uranium milling operation

International Nuclear Information System (INIS)

Ibrahim, S.; Flot, S.; Whicker, F.W.

1982-01-01

This paper reports on a study whose objectives were to determine 238 U and 230 Th concentrations in soil and native plants from various sites around a conventional acid leach uranium milling operation in the Western US, and to estimate plant/soil concentration factors. Soil and vegetation samples were collected from exposed, weathered tailings; near the edge of a tailings pond; from a reclamation area; and at several native range background (control) locations. The results indicate that mean plant/soil concentration factors varied significantly among sites and between radionuclides, but no significant differences between plant groups were found. Concentration factors for 230 Th were greater than for 238 U for plants growing at the edge of the tailings pond. It is speculated that the lower concentration factors for uranium relative to thorium at this site may be due to the proportion of their contents in soil that is biologically available for plant uptake

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

International Nuclear Information System (INIS)

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

2001-01-01

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

Measurement and Analysis of Specific Activities of 238U, 232Th,226Ra, 40K and 137Cs in Soil Samples from Phatthalung Province (Thailand) using Gamma Ray Spectrometry

International Nuclear Information System (INIS)

Daoh, Murnee; Kessaratikoon, Prasong; Udomsomporn, Suchin

2011-06-01

Full text: Specific activity of natural (238 U , 232 T h, 226 R a and 40 K ) and anthropogenic radionuclide (137 C s) in 109 soil samples collected from 11 districts in Phathalung province have been measured and analyzed. Experimental results were obtained by using a high purity germanium (HPGe) detector and gamma spectrometry analysis system at Nuclear and Material Physics laboratory in Department of Physics Faculty of Science Thaksin University Songkhla Campus. Gamma ray radioactive standard sources 60 C o, 137 C s and 133 B a were used to calibrate the measurement system. The KCl and two reference materials (RGU-1 and RGTh-1) obtained from the International Atomic Energy Agency were also used to analyze and compute the 40 K , 238 U (or 226 R a) and 232 T h specific activity in all soil samples. The IAEA/SL-2 was also used to evaluate the specific activity of 137 C s in all soil samples. The measuring time of each sample was 10,800 seconds. It was found that specific activity ranged from 148.17 to 11276.78 Bq/kg for 40 K , 58.29 to 518.45 Bq/kg for 226 R a, 8.40 to 236.19 Bq/kg for 232 T h and 0.00 tp 12.39 Bq/kg for 137 C s with mean values of 3573.35 ± 203.89 Bq/kg, 135.89 ± 6.71 Bq/kg, 76.34 ± 5.32 Bq/kg and 1.05 ± 0.70 Bq/kg respectively. Furthermore, absorbed dose rate in air (D), radium equivalent activity (Ra e q), external hazard index (H e x), and annual effective dose rate (AEDout) of this area were also evaluated by using the mean values of specific activities of the 40 K , 226 R a and 232 T h. Moreover, the experimental results were also compared with Office of Atoms for Peace (OAP) research data, Thailand and global radioactivity measurement and evaluations. The radioactive contour maps of specific activities of natural and anthropogenic radionuclides from this study were created by using the program ArcGis Version 9.2

Storage and disposition of weapons usable fissile materials (FMD) PEIS: Blending of U-233 to <12% or <5% enrichment at the Idaho National Engineering Laboratory. Data report, Draft: Version 1

International Nuclear Information System (INIS)

Shaber, E.L.

1995-08-01

Uranium-233 (U-233), a uranium isotope, is a fissionable material capable of fueling nuclear reactors or being utilized in the manufacturing of nuclear weapons. As such, it is controlled as a special nuclear material. The Idaho National Engineering Laboratory (INEL) and Oak Ridge National Laboratory (ORNL) currently store the Department of Energy's (DOE's) supply of unirradiated U-233 fuel materials. Irradiated U-233 is covered by the national spent nuclear fuel (SNF) program and is not in the scope of this report. The U-233 stored at ORNL is relatively pure uranium oxide in the form of powder or monolithic solids. This material is currently stored in stainless steel canisters of variable lengths measuring about 3 inches in diameter. The ORNL material enrichment varies with some material containing considerable amounts of U-235. The INEL material is fuel from the Light Water Breeder Reactor (LWBR) Program and consists of enriched uranium and thorium oxides in zircaloy cladding. The DOE inventory of U-233 contains trace quantities of U-232, and daughter products from the decay of U-232 and U-233, resulting in increased radioactivity over time. These increased levels of radioactivity generally result in the need for special handling considerations

A 233U/236U/242Pu/244Pu spike for isotopic and isotope dilution analysis by mass spectrometry with internal calibration

International Nuclear Information System (INIS)

Stepanov, A.; Belyaev, B.; Buljanitsa, L.

1989-11-01

The Khlopin Radium Institute prepared on behalf of the IAEA a synthetic mixture of 233 U, 236 U, 242 Pu and 244 Pu isotopes. The isotopic composition and elemental concentration of uranium and plutonium were certified on the basis of analyses done by four laboratories of the IAEA Network, using mass spectrometry with internal standardization. The certified values for 233 U/ 236 U ratio and the 236 U chemical concentration have a coefficient of variation of 0.05%. The latter is fixed by the uncertainty in the 235 U/ 238 U ratio of NBS500 used as internal standard. The coefficients of variation of the 244 Pu/ 242 Pu ratio and the 242 Pu chemical concentration are respectively 0.10% and 0.16% and limited by the uncertainty in the 240 Pu/ 239 Pu ratio of NBS947. This four isotope mixture was used as an internal standard as well as a spike, to analyze 30 batches of LWR spent fuel solutions. The repeatability of the mass spectrometric measurements have a coefficient of variation of 0.025% for the uranium concentration, and of 0.039% for the plutonium concentration. The spiking and treatment errors had a coefficient of variation of 0.048%. (author). Refs, figs and tabs

Investigation of neutronic behavior in a CANDU reactor with different (Am, Th, {sup 235}U)O{sub 2} fuel matrixes

Energy Technology Data Exchange (ETDEWEB)

Gholamzadeh, Z. [Talca Univ. (Chile). Dept. of Physics; Feghhi, S.A.H. [Shahid Beheshti Univ., Tehran (Iran, Islamic Republic of). Dept. of Radiation Application

2014-11-15

Recently thorium-based fuel matrixes are taken into consideration for nuclear waste incineration because of thorium proliferation resistance feature moreover its breeding or convertor ability in both thermal and fast reactors. In this work, neutronic influences of adding Am to (Th-{sup 235}U)O{sub 2} on effective delayed neutron fraction, reactivity coefficients and burn up of a fed CANDU core has been studied using MCNPX 2.6.0 computational code. Different atom fractions of Am have been introduced in the fuel matrix to evaluate its effects on neutronic parameters of the modeled core. The computational data show that adding 2% atom fraction of Am to thorium-based fuel matrix won't noticeably change reactivity coefficients in comparison with the fuel matrix containing 1% atom fraction of Am. The use of 2% atom fraction of Am resulted in a higher delayed neutron fraction. According to the obtained data, 32.85 GWd burn up of the higher Americium-containing fuel matrix resulted in 55.2%, 26.5%, 41.9% and 2.14% depletion of {sup 241}Am, {sup 243}Am, {sup 235}U and {sup 232}Th respectively. 132.8 kg of {sup 233}U fissile element is produced after the burn up time and the nuclear core multiplication factor increases in rate of 2390 pcm. The less americium-containing fuel matrix resulted in higher depletion of {sup 241/243}Am, {sup 235}U and {sup 232}Th while the nuclear core effective multiplication factor increases in rate of 5630 pcm after the burn up time with 9.8 kg additional {sup 233}U production.

The Effect of Early Diagenesis on the 238U/235U Ratio of Platform Carbonates.

Science.gov (United States)

Tissot, F.; Chen, C.; Go, B. M.; Naziemiec, M.; Healy, G.; Swart, P. K.; Dauphas, N.

2017-12-01

In the past 15 years, the so-called non-traditional stable isotopes systems (e.g., Mg, Fe, Mo, U) have emerged as powerful tracers of both high-T and low-T geochemical processes (e.g., [1]). Of particular interest for paleoredox studies is the ratio of "stable" isotopes of U (238U/235U), which has the potential to track the global extent of oceanic anoxia (e.g., [2, 3]). Indeed, in the modern ocean, U exists in two main oxidation states, soluble U6+ and insoluble U4+, and has a mean residence time of 400 kyr ([4]), much longer than the global ocean mixing time (1-2 kyr). As such the salinity-normalized ocean is homogeneous with regards to both U concentrations and isotopes (δ238USW = -0.392±0.005 ‰, [2]). The value of δ238USW at any given time is therefore the balance between U input to the ocean, mainly from rivers, and U removal, mostly into biogenic carbonates, anoxic/euxinic sediments and suboxic/hypoxic sediments (e.g., [2, 5]). Because the 238U/235U ratio of the past ocean cannot be measured directly, it has to be estimated from the measurement of the 238U/235U ratio of a sedimentary rock and assuming a constant fractionation factor. Carbonates appear as a promising record since they span most of Earth's history, and the δ238U values of modern primary carbonate precipitates and well-preserved fossil aragonitic coral up to 600 ka are indistinguishable from that of seawater (e.g., [2, 6, 7]). Yet, the effect of secondary processes on the δ238U values of non-coral carbonates, which represent the bulk of the rock record, has only been studied in a handful of shallow samples (down to 40cm, [6]) and remains poorly understood. To investigate the effect of early diagenesis on the 238U/235U ratio of carbonates on the 30kyr to 1Myr timescale, we measured δ13C, δ18O, and δ238U in samples from a 220m long drill core from the Bahamas carbonate platform. In order to separate lattice bound U from secondary U we developed a leaching protocol applicable to carbonate

Study of the desintegration of short-life fission products. Application to the mass distribution in the fission of 238U and 233U induced by 14MeV neutrons

International Nuclear Information System (INIS)

Cavallini, Pierre.

1975-01-01

Nuclear spectrometry of short-life fission products was investigated, together with direct applications to the study of mass and charge distribution in fission reactions. It is shown that, by choosing judiciously the target in which the fission product is created and owing to the differences in stabilities and evaporation temperatures of the compounds obtained, it is possible to separate some elements. For example, niobium was separated by heating after irradiation of a mixture of UC and RuCl 3 , and sublimation in a tube with temperature gradient. It was thus possible to study the 99 Nb isotope. Other classical chemical separation processes were used for yttrium and strontium. The half-lifes beta and gamma spectra, decay schemes of 93 Sr, 94 Y and 95 Y were studied. It was shown how to obtain mass distribution in fission using a nondestructive gamma analysis method. As an application, results obtained in the fission of 233 U and 238 U at 14 MeV are given [fr

Plutonium and U-233 mines

International Nuclear Information System (INIS)

Milgram, M.S.

1983-08-01

A comparison is made among second generation reactor systems fuelled primarily with fissile plutonium and/or U-233 in uranium or thorium. This material is obtained from irradiated fuel from first generation CANDU reactors fuelled by natural or enriched uranium and thorium. Except for plutonium-thorium reactors, second generation reactors demand similar amounts of reprocessing throughput, but the most efficient plutonium burning systems require a large prior allocation of uranium. Second generation reactors fuelled by U-233 make more efficient use of resources and lead to more flexible fuelling strategies, but require development of first generation once-through thorium cycles and early demonstration of the commercial viability of thorium fuel reprocessing. No early implementation of reprocessing technology is required for these cycles

Uranium contents and 234U/238U activity ratios of modern and fossil marine bivalle molluscan shells

International Nuclear Information System (INIS)

Mitsuda, Hiroshi

1984-01-01

Uranium contents and 234 U/ 238 U activity ratios in modern and fossil marine bivalle molluscan shells were measured by alpha-spectrometry. Uranium contents and 234 U/ 238 U activity ratios in modern shells were averaged to be 0.266 (dpm/g), and 1.18, respectively and those in fossil shells were averaged to be 0.747 (dpm/g), and 1.19, respectivily. Uranium contents in fossil shells were obviously higher than those in modern shells. It can be explained by the addition of uranium to shell during the deposition. In fossil shells, 234 U/ 238 U activity ratio decreases as 238 U content increases the same tendency is not found in modern shells. The author proposed a mechanism of selective loss of 238 U from the fossil shells for the explanation of this tendency. The height activity ratio of 234 U/ 238 U measured on the fossil shells than that measured on the modern shells, also support the selective loss of 238 U from the fossil shells. (author)

Evaluation and compilation of fission product yields 1993

International Nuclear Information System (INIS)

England, T.R.; Rider, B.F.

1995-01-01

This document is the latest in a series of compilations of fission yield data. Fission yield measurements reported in the open literature and calculated charge distributions have been used to produce a recommended set of yields for the fission products. The original data with reference sources, and the recommended yields axe presented in tabular form. These include many nuclides which fission by neutrons at several energies. These energies include thermal energies (T), fission spectrum energies (F), 14 meV High Energy (H or HE), and spontaneous fission (S), in six sets of ten each. Set A includes U235T, U235F, U235HE, U238F, U238HE, Pu239T, Pu239F, Pu241T, U233T, Th232F. Set B includes U233F, U233HE, U236F, Pu239H, Pu240F, Pu241F, Pu242F, Th232H, Np237F, Cf252S. Set C includes U234F, U237F, Pu240H, U234HE, U236HE, Pu238F, Am241F, Am243F, Np238F, Cm242F. Set D includes Th227T, Th229T, Pa231F, Am241T, Am241H, Am242MT, Cm245T, Cf249T, Cf251T, Es254T. Set E includes Cf250S, Cm244S, Cm248S, Es253S, Fm254S, Fm255T, Fm256S, Np237H, U232T, U238S. Set F includes Cm243T, Cm246S, Cm243F, Cm244F, Cm246F, Cm248F, Pu242H, Np237T, Pu240T, and Pu242T to complete fission product yield evaluations for 60 fissioning systems in all. This report also serves as the primary documentation for the second evaluation of yields in ENDF/B-VI released in 1993

Evaluation and compilation of fission product yields 1993

Energy Technology Data Exchange (ETDEWEB)

England, T.R.; Rider, B.F.

1995-12-31

This document is the latest in a series of compilations of fission yield data. Fission yield measurements reported in the open literature and calculated charge distributions have been used to produce a recommended set of yields for the fission products. The original data with reference sources, and the recommended yields axe presented in tabular form. These include many nuclides which fission by neutrons at several energies. These energies include thermal energies (T), fission spectrum energies (F), 14 meV High Energy (H or HE), and spontaneous fission (S), in six sets of ten each. Set A includes U235T, U235F, U235HE, U238F, U238HE, Pu239T, Pu239F, Pu241T, U233T, Th232F. Set B includes U233F, U233HE, U236F, Pu239H, Pu240F, Pu241F, Pu242F, Th232H, Np237F, Cf252S. Set C includes U234F, U237F, Pu240H, U234HE, U236HE, Pu238F, Am241F, Am243F, Np238F, Cm242F. Set D includes Th227T, Th229T, Pa231F, Am241T, Am241H, Am242MT, Cm245T, Cf249T, Cf251T, Es254T. Set E includes Cf250S, Cm244S, Cm248S, Es253S, Fm254S, Fm255T, Fm256S, Np237H, U232T, U238S. Set F includes Cm243T, Cm246S, Cm243F, Cm244F, Cm246F, Cm248F, Pu242H, Np237T, Pu240T, and Pu242T to complete fission product yield evaluations for 60 fissioning systems in all. This report also serves as the primary documentation for the second evaluation of yields in ENDF/B-VI released in 1993.

Measurement of the $^{233}$U neutron capture cross section at the n_TOF facility at CERN

CERN Document Server

Carrapiço, Carlos; Berthoumieux, Eric; Gonçalves, Isabel; Gunsing, Frank

2012-12-12

The Thorium-Uranium (Th-U) fuel cycle has been envisaged as an alternative to the Uranium-Plutonium (U-Pu) fuel cycle for electricity generation using nuclear power reactors. Indeed, thorium can be used as a nuclear fuel, and several studies and R&D programs seem to provide evidence on the sustainability of the Th-U fuel cycle, due to (i) the natural abundance of Thorium, (ii) the improved proliferation resistance offered by the Th-U fuel cycle relative to the U-Pu fuel cycle, (iii) the better neutronics performance of the Th-U fuel cycle throughout the whole neutron energy range compared to the U-Pu fuel cycle, (iv) the lower radiotoxicity of the generated spent fuel in reactors with Th-U fuel cycle and, consequently (v) better economics and public acceptance of the reactors operated using the Th-U fuel cycle compared to those using the U-Pu fuel cycle (prior to the Generation IV nuclear reactors). In a nuclear reactor operated using the Th-U fuel cycle, $^{233}$U is a key nuclide governing the neutr...

Intake of 210Po, 234U and 238U radionuclides with beer in Poland

International Nuclear Information System (INIS)

Skwarzec, B.; Struminska, D.I.; Borylo, A.; Falandysz, J.

2004-01-01

238 U, 234 U and 210 Po activity concentrations were determined in beer in Poland by alpha-spectrometry with low-level activity silicon detectors. The results revealed that the mean concentrations of 238 U, 234 U and 210 Po in the analyzed beer samples were 4.63, 4.11 and 4.94 mBq x dm -3 , respectively, the highest in Tyskie (5.71 for 210 Po, 5.06 for 234 U and 6.11 for 238 U) and the lowest in Lech (2.49 for 210 Po). The effective radiation dose due to uranium and polonium ingestions by beer was calculated and were compared to the effective radiation dose from drinking water. (author)

U-Th series nuclides in the Gulf of Mexico

International Nuclear Information System (INIS)

Scott, M.R.

1981-01-01

A study of U and Th series nuclides is being conducted on sediments from the Gulf of Mexico. Uranium concentrations as a function of depth have been determined, as well as changes in the 234 U/ 238 U activity ratio. The geochemical behavior of uranium in shelf sediments is discussed

Microscopic structure of superdeformed states in Th, U, Pu and Cm isotopes with Gogny force

Energy Technology Data Exchange (ETDEWEB)

Girod, M.; Delaroche, J.P.; Romain, P. [CEA/DIF, DPTA/SPN, Boite Postale 12, 91680 Bruyeres-le-Chatel (France); Libert, J. [Institut de Physique Nucleaire Centre National de la Recherche Scientifique-IN2P3, F-91406 Orsay (France)

2002-10-01

The structure properties of the even-even nuclei {sup 226,} {sup 228,} {sup 230,} {sup 232,} {sup 234}Th, {sup 230,} {sup 232,} {sup 234,} {sup 236,} {sup 238,} {sup 240}U, {sup 240,} {sup 242,} {sup 244,} {sup 246}Pu, and {sup 242,} {sup 244,} {sup 246,} {sup 248}Cm have been investigated at normal and superdeformed shapes in microscopic mean-field calculations based on Gogny force. Collective levels are predicted from constrained Hartree-Fock-Bogoliubov and configuration mixing calculations. Two quasiparticle states are also predicted from blocking calculations for neutron and proton configurations. Predictions are shown and compared with experimental data at superdeformed shapes. (orig.)

Study of the variation with the energy of the fission cross-sections of 233U, 235U, 239Pu for the fast neutrons

International Nuclear Information System (INIS)

Szteinsznaider, D.; Naggiar, V.; Netter, F.

1955-01-01

This measurements have been done while taking the value of the fission cross-sections of 238 U as reference. The neutrons are produced by the reaction 7 Li(p,n) in the Van de Graaff generator of Saclay. The explored domain spreads from some tenths to 2000 keV. We find: for 239 Pu: σ f = 2,04 ± 0,12 barns, cross-section constant between 150 and 2000 keV, for 235 U: σ f = 1,15 ± 0,15 barns, cross-section constant between 700 and 1000 keV, for 233 U: σ f = 1,92 ± 0,25 barns, for neutrons of 850 keV. (authors) [fr

235U and 238U (n,xn gamma) cross-sections

International Nuclear Information System (INIS)

Bacquias, A.; Dessagne, Ph.; Kerveno, M.; Rudolf, G.; Thiry, J.C.; Borcea, C.; Negret, A.L.; Drohe, J.C.; Nankov, N.; Nyman, M.; Plompen, A.; Rouki, C.; Stanoiu, M.

2014-01-01

The (n,n') and (n,2n) are important processes in the energy domain of fission neutrons, but the cross-sections suffer from large uncertainties, not compatible with the objectives fixed for future and advanced nuclear reactors. This paper presents our experimental effort to improve 235 U and 238 U (n,xnγ) cross-section data. The experiments were performed at the GELINA facility (Belgium), which provides a pulsed (800 Hz) neutron beam covering a wide energy spectrum (from a few eV to about 20 MeV). The GRAPhEME set-up is designed for prompt gamma spectroscopy and time-of-flight measurement. The analysis methods are presented. Already published results on 235 U are shown, as well as results on 238 U. The interpretation and discussion rely on the comparison with TALYS and EMPIRE predictions. (authors)

Storage and disposition of weapons usable fissile materials (FMD) PEIS: Blending of U-233 to {lt}12% or {lt}5% enrichment at the Idaho National Engineering Laboratory. Data report, Draft: Version 1

Energy Technology Data Exchange (ETDEWEB)

Shaber, E.L.

1995-08-01

Uranium-233 (U-233), a uranium isotope, is a fissionable material capable of fueling nuclear reactors or being utilized in the manufacturing of nuclear weapons. As such, it is controlled as a special nuclear material. The Idaho National Engineering Laboratory (INEL) and Oak Ridge National Laboratory (ORNL) currently store the Department of Energy`s (DOE`s) supply of unirradiated U-233 fuel materials. Irradiated U-233 is covered by the national spent nuclear fuel (SNF) program and is not in the scope of this report. The U-233 stored at ORNL is relatively pure uranium oxide in the form of powder or monolithic solids. This material is currently stored in stainless steel canisters of variable lengths measuring about 3 inches in diameter. The ORNL material enrichment varies with some material containing considerable amounts of U-235. The INEL material is fuel from the Light Water Breeder Reactor (LWBR) Program and consists of enriched uranium and thorium oxides in zircaloy cladding. The DOE inventory of U-233 contains trace quantities of U-232, and daughter products from the decay of U-232 and U-233, resulting in increased radioactivity over time. These increased levels of radioactivity generally result in the need for special handling considerations.

Study of Advanced Reactor Mixed Oxide Fuel Production of (U,Th)O2

International Nuclear Information System (INIS)

Busron-Masduki; Damunir; Pristi-Hartati; R-Sukarsono; Bangun-Wasito

2000-01-01

The high price and starting scarcity of reserved of oil drive the people to drill the alternative nuclear energy. Accelerator-driven Transmutation Waste (ATW) is a prospective technology to solve the problem of used fuel waste, to reduce the anxiety of long term disposal waste, to increase the public acceptance of nuclear energy enter into the third millennium. The future of large nuclear energy appears in many-branched industry will depend on the capability to generate relatively low priced fuel on the basis of commercial nuclear energy. Utilization of uranium-233 -thorium cycle insures long-term fuel supply, makes the nuclear energy production more flexible and enables the self-provision regime to be realized in future. Flowsheet of mixed oxide fuel production for advanced reactor of (U,Th)O 2 is a combination of existing manufacturing equipment and quality assurance program from commercial LWR and HTR. The front-end of flowsheet using sol-gel process. The external sol-gel process is chosen due to simple equipment can anticipate refabrication of U-233 which always contains a few hundred ppm of U-232 and its gamma-emitting daughters, besides yielding smaller waste. The decision to choose external sol-gel process encourages to develop External Gelation Thorium (EGT). In order to get higher density and relatively low compaction pressures (i.e. for advanced LWR) adopted flowsheet EGT is developed to be Sol-Gel Microsphere Pelletization (SGMP). Using the optimal parameters, SGMP become established flowsheet for producing mixed oxide fuel of (U,Th)O 2 for advanced reactor. (author)

Determination of the activity of the uranium isotopes U-234, U-235 and U-238 in environmental samples by alpha spectrometry

International Nuclear Information System (INIS)

Kromphorn, G.

1996-02-01

Different materials containing urandium are regularly investigated in the Laboratory for Environmental Radioactivity of the Physikalisch-Technische Bundesanstalt (PTB) with respect to the activity of the uranium isotopes ( 234 U, 235 U, and 238 U). Moreover for reasons of quality assurance, the PTB takes part in international comparisons where also uranium contents are to be determined in environmental samples and in the framework of which reference materials can be certified. Finally in national comparisons the PTB has the task to determine values of the specific activity for the different isotopes which can play the role of nominal (orientation) values. The single steps of uranium analyses are described after a compilation of the most important data of the uranium isotopes contained in natural uranium: The use of 232 U as tracer, the chemical separation analytics, the production of α-sources and the measuring methods. Analyses of a soil sample and a waste water sample with respect to their specific uranium activity have been chosen as examples of a practical application. (orig.) [de

Determination of uranium concentrations and "2"3"4U/"2"3"8U activity ratio in some granitic rock samples by alpha spectrometry: application of a radiochemical procedure

International Nuclear Information System (INIS)

Khattab, Mahmoud R.

2016-01-01

The present study is an application of a radiochemical procedure using alpha spectrometry technique for determination of uranium isotopes "2"3"8U, "2"3"4U and "2"3"5U on 13 granitic samples. These samples were collected from Gabal Gattar area, Northeastern Desert, Egypt. The collected samples were digested using microwave technique with aqua regia and spiked with "2"3"2U for chemical yield and activity calculation. Separation of uranium isotopes from the samples was done by Dowex 1 x 4 (50-100 mesh) resin followed by source preparation using microprecipitation technique. The concentrations of "2"3"8U were ranged between 28.9±0.9 and 134.8±1.8 Bq/g, and the "2"3"4U concentrations were between 24±0.6 and 147.7±2.2 Bq/g. For the "2"3"5U, the activity concentrations were between 1.3±0.2 and 6.7±1.2 Bq/g. The activity ratio of "2"3"4U/"2"3"8U was calculated and varied from 0.80 to 1.30. (author)

222Rn content and 234U/238U activity ratio in groundwaters

International Nuclear Information System (INIS)

Olguin, M.T.; Segovia, N.; Ordonez, E.; Iturbe, J.L.; Bulbulian, S.; Carrillo, J.

1990-01-01

Geochemical radioanalytical studies of ground water were perfomed in the valleys of Villa de Reyes and San Luis Potosi, Mexico. The experiments were designed to measure radon and uranium content and 234 U/ 238 U activity ratio in ground water samples taken from wells in these sites and at the Nuclear Center of Salazar, Mexico. 222 Rn content varied depending on the sample source, reaching a maximum value of 235 pCi/l; uranium concentration results were less than 1 μg/l and 234 U/ 238 U activity ratios were close to equilibrium. (author) 9 refs.; 1 fig.; 1 tab

Water-Reflected 233U Uranyl Nitrate Solutions in Simple Geometry

International Nuclear Information System (INIS)

Elam, K.R.

2001-01-01

A number of critical experiments involving 233 U were performed in the Oak Ridge National Laboratory Building 9213 Critical Experiments Facility during the years 1952 and 1953. These experiments, reported in Reference 1, were directed toward determining bounding values for the minimum critical mass, minimum critical volume, and maximum safe pipe size of water-moderated solutions of 233 U. Additional information on the critical experiments was found in the experimental logbooks. Two experiments utilizing uranyl nitrate (UO 2 (NO 3 ) 2 ) solutions in simple geometry are evaluated in this report. Experiment 37 is in a 10.4-inch diameter sphere, and Experiment 39 is in a 10-inch diameter cylinder. The 233 U concentration ranges from 49 to 62 g 233 U/l. Both experiments were reflected by at least 6 inches of water in all directions. Paraffin-reflected uranyl nitrate experiments, also reported in Reference 1, are evaluated elsewhere. Experiments with smaller paraffin reflected 5-, 6-, and 7.5-inch diameter cylinders are evaluated in U233-SOL-THERM-004. Experiments with paraffin reflected 8-, 8.5-, 9-, 10-, and 12-inch diameter cylinders are evaluated in U233-SOL-THERM-002. Later experiments with highly-enriched 235 U uranyl fluoride solution in the same 10.4-inch diameter sphere are reported in HEU-SOL-THERM-010. Both experiments were judged acceptable for use as criticality-safety benchmark experiments

238U content in soils of Byelorussia

International Nuclear Information System (INIS)

Shagalova, Eh.D.

1986-01-01

Results of detection in Byelorussian soils of a heavy natural radionuclide 238 U and its content in humus horizons of the soils on map-schemes are presented. 238 U content is determined by complete decomposition of soils by acids, isolation from thorium using EhDEh-10 P anionite and subsequent solution colorimetry. It is shown that the content of uranium-238 in soils decreases from the North to the South. Its maximum amount (>2x10 -4 %) is detected in turfy-podsolic soils in lake-glacier loams; the minimum one ( -4 %)- in peatymarshy soils. The map-scheme of 238 U content is a background base. Using the background base it is possible to trace the change in uranium content in soils under conditions of technogenic effect and to substantiate the efficiency of environment protection measures

U-series dating using thermal ionisation mass spectrometry (TIMS)

Energy Technology Data Exchange (ETDEWEB)

McCulloch, M.T. [Australian National University, Canberra, ACT (Australia). Research School of Earth Science

1999-11-01

U-series dating is based on the decay of the two long-lived isotopes{sup 238}U({tau}{sub 1/2}=4.47 x 10{sup 9} years) and {sup 235}U ({tau}{sub 1/2} 0.7 x 10{sup 9} years). {sup 238}U and its intermediate daughter isotopes {sup 234}U ({tau}{sub 1/2} = 245.4 ka) and {sup 230}Th ({tau}{sub 1/2} = 75.4 ka) have been the main focus of recently developed mass spectrometric techniques (Edwards et al., 1987) while the other less frequently used decay chain is based on the decay {sup 235}U to {sup 231}Pa ({tau}{sub 1/2} = 32.8 ka). Both the {sup 238}U and {sup 235}U decay chains terminate at the stable isotopes {sup 206}Pb and {sup 207}Pb respectively. Thermal ionization mass spectrometry (TIMS) has a number of inherent advantages, mainly the ability to measure isotopic ratios at high precision on relatively small samples. In spite of these now obvious advantages, it is only since the mid-1980`s when Chen et al., (1986) made the first precise measurements of {sup 234}U and {sup 232}Th in seawater followed by Edwards et al., (1987) who made combined {sup 234}U-{sup 230}Th measurements, was the full potential of mass spectrometric methods first realised. Several examples are given to illustrate various aspects of TIMS U-series 9 refs., 3 figs.

The inflow of 234U and 238U from the River Odra drainage basin to the Baltic Sea

Directory of Open Access Journals (Sweden)

Bogdan Skwarzec

2010-12-01

Full Text Available In this study the activity of uranium isotopes 234U and 238U in Odra river water samples, collected from October 2003 to July2004, was measured using alpha spectrometry. The uranium concentrations were different in each of the seasons analysed; the lowest values were recorded in summer. In all seasons, uranium concentrations were the highest in Bystrzyca river waters (from 27.81 ± 0.29Bq m-3 of 234U and 17.82 ± 0.23 Bq m-3 of 238U in spring to 194.76 ± 3.43 Bq m-3 of 234U and 134.88 ± 2.85 Bq m-3 of 238U in summer. The lowest concentrations were noted in the Mała Panew (from 1.33 ± 0.02 Bq m-3 of 234U and 1.06 ± 0.02 Bq m-3 of 238U in spring to 3.52 ± 0.05 Bq m-3 of 234U and 2.59± 0.04 Bq m-3 of 238U in autumn. The uranium radionuclides 234U and 238U in the water samples were not in radioactive equilibrium. The 234U / 238U activity ratios were the highest in Odra water samples collected at Głogów (1.84 in autumn, and the lowest in water from the Noteć (1.03 in winter and spring. The 234U / 238U activity ratio decreases along the main stream of the Odra, owing to changes in the salinity of the river's waters. Annually, 8.19 tons of uranium (126.29 G Bq of 234U and 100.80 G Bq of 238U flow into the Szczecin Lagoon with Odra river waters.

Uranium 234U and 238U isotopes in the southern Baltic environment

International Nuclear Information System (INIS)

Borylo, A.; Skwarzec, B.

2002-01-01

The concentration and distribution of uranium in water and sediment of selected basins of the southern Baltic Sea have been analysed. It was observed that the concentration of uranium in sediments increases with core depth. This is probably connected to diffusion processes from sediments to water through interstitial water where uranium concentration is much higher than in bottom water. The measurements of 234 U/ 238 U activity ratios indicate that sedimentation of terrigenic material and transport through Vistula river are the major sources of uranium in sediments of the southern Baltic Sea. Estimation of the 234 U/ 238 U ratios in reduction areas of the Baltic Deep and the Bornholm Deep suggest that the processes of reduction of U(VI) to U(IV) and of removal of authogenic uranium from seawater to sediments do not play major roles in the Gdansk Deep. (author)

Multiplicity and energy of neutrons from {sup 233}U(n{sub th},f) fission fragments

Energy Technology Data Exchange (ETDEWEB)

Nishio, Katsuhisa; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan)

1998-03-01

The correlation between fission fragments and prompt neutrons from the reaction {sup 233}U(n{sub th},f) was measured with improved accuracy. The results determined the neutron multiplicity and emission energy as a function of fragment mass and total kinetic energy. The average energy as a function of fragment mass followed a nearly symmetric distribution centered about the equal mass-split and formed a remarkable contrast with the saw-tooth distribution of the average neutron multiplicity. The neutron multiplicity from the specified fragment decreases linearly with total kinetic energy, and the slope of multiplicity with kinetic energy had the minimum value at about 130 u. The level density parameter versus mass determined from the neutron data showed a saw-tooth structure with the pronounced minimum at about 128 and generally followed the formula by Gilbert and Cameron, suggesting that the neutron emission process was very much affected by the shell-effect of the fission fragment. (author)

Study of the uranium availability through the research method Th/U

Energy Technology Data Exchange (ETDEWEB)

Fernandez, Zahily Herrero; Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Santos, Josineide Marques do Nascimento; Damascena, Kennedy Francys Rodrigues; Medeiros, Nilson Vicente da Silva; Maciel Neto, Jose de Almeida, E-mail: zahily1985@gmail.com, E-mail: jaraujo@ufpe.br, E-mail: romilton@ufpe.br, E-mail: neideden@hotmail.com, E-mail: kennedy.eng.ambiental@gmail.com, E-mail: nvsmedeiros@gmail.com, E-mail: profjosemaciel@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociencias. Departamento de Energia Nuclear; Alvarez, Juan Reinaldo Estevez, E-mail: jestevez@ceaden.cu [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Havana (Cuba); Silva, Alberto Antonio da, E-mail: alberto.silva@barreiros.ifpe.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Barreiros, PE (Brazil)

2015-07-01

The uranium and thorium, precursors of the main natural radioactive series, have different concentrations in the Earth's crust. The ratio Th/U has been used as an indicator of oxidizing and reducing conditions, whose factors suggest availability of uranium to displacement in the environment and incorporations in different matrices. This parameter become essential to determine possible conditions of availability by the chemical form and incorporation in the food chain. The state of Paraiba, in northeastern Brazil, has a uranium deposits located in Sao Jose de Espinharas, where there are agricultural practices in areas surrounding the deposit of natural uranium. The Environmental Monitoring Program and Radioecological, making it an area that offers all the features for research mobility of uranium, chemical form and availability of incorporation, in addition to understanding the kinetics and transport of this natural radionuclide in the environment. Soil samples were collected from agricultural areas, close to the uraniferous occurrences where the samples were analyzed in the Laboratorio de Radioecologia e Controle Ambiental (LARCA) of the Departamento de Energia Nuclear at the Universidade Federal de Pernambuco (UFPE) by High Resolution Gamma Spectrometry, obtaining the experimental activities of {sup 238}U and {sup 232}Th using indirect gamma measures. The obtained findings show that the ratio Th/U varied from 0.11 to 1.33, with an average of 0.69. (author)

Study of the uranium availability through the research method Th/U

International Nuclear Information System (INIS)

Fernandez, Zahily Herrero; Santos Junior, Jose Araujo dos; Amaral, Romilton dos Santos; Santos, Josineide Marques do Nascimento; Damascena, Kennedy Francys Rodrigues; Medeiros, Nilson Vicente da Silva; Maciel Neto, Jose de Almeida; Silva, Alberto Antonio da

2015-01-01

The uranium and thorium, precursors of the main natural radioactive series, have different concentrations in the Earth's crust. The ratio Th/U has been used as an indicator of oxidizing and reducing conditions, whose factors suggest availability of uranium to displacement in the environment and incorporations in different matrices. This parameter become essential to determine possible conditions of availability by the chemical form and incorporation in the food chain. The state of Paraiba, in northeastern Brazil, has a uranium deposits located in Sao Jose de Espinharas, where there are agricultural practices in areas surrounding the deposit of natural uranium. The Environmental Monitoring Program and Radioecological, making it an area that offers all the features for research mobility of uranium, chemical form and availability of incorporation, in addition to understanding the kinetics and transport of this natural radionuclide in the environment. Soil samples were collected from agricultural areas, close to the uraniferous occurrences where the samples were analyzed in the Laboratorio de Radioecologia e Controle Ambiental (LARCA) of the Departamento de Energia Nuclear at the Universidade Federal de Pernambuco (UFPE) by High Resolution Gamma Spectrometry, obtaining the experimental activities of 238 U and 232 Th using indirect gamma measures. The obtained findings show that the ratio Th/U varied from 0.11 to 1.33, with an average of 0.69. (author)

U/Th-isotopes as natural analogues for the mobility of actinides in granitic rocks

International Nuclear Information System (INIS)

Mengel, K.; Gerdes, A.

2001-01-01

The short-lived decay products of 238 U ( 234 U and 230 Th) can be used as natural analogues for actinides in a hard rock repository. Their mobility in the past may serve as a key for understanding actinide migration in the future. For generally old calcites of the HRL Aespoethe age of disturbance of 238 U/ 234 U and 234 U/ 230 Th activity ratios ranges from 30 000 to 436 000 years at degrees of disturbance ranging from 0.5 to 6.7. The results obtained imply that during the past 440 000 years U was mobile throughout the tunnel sections of the HRL Aespoeinvestigated here. For the FL Grimsel, the disequilibrium states of the 234 U/ 238 U and 230 Th/ 234 U activity ratios in fracture minerals (calcites silicates) also imply that the reactions causing isotopic disturbances have occurred within the past 500 000 years. The U/Th-isotope data of both the samples from the HRL Aespoeand the FL Grimsel have in common the mobilization of U in secondary fracture minerals by migrating solutions within the past 500 000 years. As for the question of a final disposal of radioactive waste in granite host rocks, the transport of U - and thus of similarly behaving actinides - in migrating underground solutions can therefore not be ruled out, if suitable hydraulic systems are considered. (orig.)

Distribution of activity concentrations of {sup 238}U and {sup 232}Th in soil samples from Minas Gerais state; Distribuicao das concentracoes de atividade de {sup 238}U e {sup 232}Th em amostras de solo do Estado de Minas Gerais

Energy Technology Data Exchange (ETDEWEB)

Peixoto, C.M.; Rodrigues, P.C.H.; Carvalho Filho, C.A.; Feliciano, V.M.D., E-mail: Patricia.fernandes@meioambiente.mg.gov.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Fernandes, P.R.M., E-mail: cmp@cdtn.br, E-mail: pchr@cdtn.br, E-mail: cacf@cdtn.br, E-mail: vmfj@cdtn.br [Fundacao Estadual do Meio Ambiente (FEAM), Belo Horizonte, MG (Brazil)

2016-07-01

Soil contamination by radionuclides, heavy metal, pesticides, among others, threatens ecosystems and human health. Environmental monitoring bodies and agencies need reference values for these contaminants in order to assess the impacts of anthropogenic activities on soil contamination. Quality Reference Values (QRVs) reflect the natural concentrations of contaminants in soils without anthropic interference and must be regionally established. The aim of this study was the determination of natural concentrations and quality reference values for U and Th in soils from Minas Gerais State, Brazil. A large variation of the natural activity concentration of these radionuclides in soil was observed. The QRV for U was 86.5 Bq kg{sup -1} and 90.81 Bq kg{sup -1} for Th. Statistical analysis showed that the two elements have a positive correlation with the clay and organic matter content in soil, and with the soil orders Ultisol and Inceptisol. Uranium shows a strong correlation with As, Sb, Se and Hg, while Thorium does not show correlation with any of the trace elements. (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

U-Th Burial Dates on Ostrich Eggshell

Science.gov (United States)

Sharp, W. D.; Fylstra, N. D.; Tryon, C. A.; Faith, J. T.; Peppe, D. J.

2015-12-01

Obtaining precise and accurate dates at archaeological sites beyond the range of radiocarbon dating is challenging but essential for understanding human origins. Eggshells of ratites (large flightless birds including ostrich, emu and others) are common in many archaeological sequences in Africa, Australia and elsewhere. Ancient eggshells are geochemically suitable for the U-Th technique (1), which has about ten times the range of radiocarbon dating (>500 rather than 50 ka), making eggshells attractive dating targets. Moreover, C and N isotopic studies of eggshell provide insights into paleovegetation and paleoprecipitation central to assessing past human-environment interactions (2,3). But until now, U-Th dates on ratite eggshell have not accounted for the secondary origin of essentially all of their U. We report a novel approach to U-Th dating of eggshell that explicitly accounts for secondary U uptake that begins with burial. Using ostrich eggshell (OES) from Pleistocene-Holocene east African sites, we have measured U and 232Th concentration profiles across OES by laser ablation ICP-MS. U commonly peaks at 10s to 100s of ppb and varies 10-fold or more across the ~2 mm thickness of OES, with gradients modulated by the layered structure of the eggshell. Common Th is high near the shell surfaces, but low in the middle "pallisade" layer of OES, making it optimal for U-Th dating. We determine U-Th ages along the U concentration gradient by solution ICP-MS analyses of two or more fractions of the pallisade layer. We then estimate OES burial dates using a simple model for diffusive uptake of uranium. Comparing such "U-Th burial dates" with radiocarbon dates for OES calcite from the same shells, we find good agreement in 7 out of 9 cases, consistent with rapid burial and confirming the accuracy of the approach. The remaining 2 eggshells have anomalous patterns of apparent ages that reveal they are unsuitable for U-Th dating, thereby providing reliability criteria innate

234U/238U activity ratio in groundwater - an indicator of past hydrogeological processes

International Nuclear Information System (INIS)

Rasilainen, K.; Suksi, J.; Marcos, N.; Nordman, H.

2005-01-01

In this report we describe the long-term behaviour of the uranium isotopes, U-234 and U-238 in groundwater systems. U is a redox sensitive element what for its behaviour is largely controlled by changes in the environmental conditions. A striking feature in U isotope geochemistry is seemingly different behaviour of U-238 and U-234. U isotopes fractionate at the rock-groundwater interface depending on chemical and radiological factors. Changes of the redox conditions in groundwater may thus affect the behaviour of U and its isotopes resulting in variable U concentration and U-234/U-238 activity ratios (AR). We examined the formation of ARs in different groundwater types from a geochemical and a physical/radiological point of view. It was envisaged that AR in groundwater is the consequence of radiological, chemical and hydrological processes. Groundwater condition (redox, flow, etc.) play a very important role in controlling the mass flow of U isotopes. Quantitative α-recoil modelling showed that α-recoil induced flux can be considered insignificant in cases of high-flow. This was an important finding because the exclusion of direct a-recoil means that it is groundwater chemistry and its variations which controls the U-234 mass flow and the formation of AR. Therefore, AR values could be used more confidently to indicate past redox changes and possibly flow paths. (orig.)

A statistical study of {sup 238}U and {sup 234}U/{sup 238}U distributions in coral samples from the Egyptian shoreline of the north-western Red sea and in fossil mollusk shells from the Atlantic coast of High Atlas in Morocco: implications for {sup 230}Th/{sup 234}U dating

Energy Technology Data Exchange (ETDEWEB)

Choukri, A.; Hakam, O.K. [Lab. des Faibles Radioactivites et d' Environnements, UFR: Faibles Radioactivites, Mathematiques physiques et environnement, Kenitra (Morocco); Reyss, J.L. [Lab. des Sciences de Climat et de l' Environnement, Domaine du CNRS, Gif sur Yvette (France); Plaziat, J.C. [Univ. de Paris-Sud, Dept. des Sciences de la Terre, Orsay (France)

2002-07-01

In this work, radiochemical analysis results of 126 uncrystallized coral samples from the Egyptian shoreline of northwestern Red Sea and 120 fossil mollusk shell samples from the Atlantic coast of Moroccan High Atlas at the North of Agadir City in Morocco are presented and discussed. The coral samples were collected in Egypt from the emerged coral reef terraces over 500 km from The Ras Gharib-Ras Shukeir depression (28 10') in the north to Wadi Lahami (north of Ras Banas, 24 10') in the south. The fossil mollusk shells were collected in Morocco from Agadir-Harbour in the south to Tamri village in the north extending over about 50 km. The statistical distributions of results ({sup 238}U content, {sup 234}U/{sup 238}U activity ratio and ages) obtained on the dated materials in the two different regions were compared for three fossil sea levels corresponding to three different climatic stages (Holocene, 5e, 7 and/or 9) in the aim to establish methodological criteria for judging validity of the measured ages. For corals, {sup 238}U content varies in narrow interval around the same average value of 3 ppm for the three sea levels, the calculated initial {sup 234}U/{sup 238}U values are in agreement with the actual sea water ratio (1.15) with some values slightly higher than for the older sea levels. The obtained ages are in good agreement with the ages reported previously for the three emerged fossil sea levels on unrecrystallized corals by alpha spectrometry and by mass spectrometry. For mollusk shells, except for Holocene sea level, {sup 238}U and initial {sup 234}U/{sup 238}U activity ratios vary for the older levels in wide intervals, independent of species and calcite contents of samples. The high {sup 238}U contents and {sup 234}U/{sup 238}U activity ratio are due eventually to a post-incorporation of secondary uranium from sea water or from continental waters drained away rivers. This incorporation leads to a rejuvenation of mollusk shell ages and is

Emanation of 232U and its radioactive daughter products from respirable size particles

International Nuclear Information System (INIS)

Cuddihy, R.G.; Griffith, W.C.; Hoover, M.D.; Kanapilly, G.M.; Stalnaker, N.D.

1978-01-01

This study is to develop a model for the emanation of 232 U and its radioactive daughter products from particles of Th-U fuel material. The radiation doses to internal organs following inhalation of these particles can only be calculated by knowing the rate of emanation of the daughters from particles in the lung and the subsequent excretion or translocation of the daughters to other organs. The emanation mechanisms are recoil of the daughter nuclei from the particle during alpha decay of the parent, diffusion of inert gas daughters from the particle and dissolution of the particle itself in biological fluids. Experiments to evaluate these mechanisms will involve ThO 2 and UO 2 particles in the size range 0.1 to 1.0 μm MMAD uniformly labeled with 232 U. The influence of the material temperature history on emanation will be investigated by heat treating particles at 600 and 1400 0 C

Fast and thermal data testing of 233U critical assemblies

International Nuclear Information System (INIS)

Wright, R.Q.; Jordan, W.C.; Leal, L.C.

1999-01-01

Many sources have been used to obtain 233 U benchmark descriptions. Unfortunately, some of these are not reliable since a thorough and complete benchmark evaluation often has not been done. For 24 yr a principal source for 233 U benchmarks has been the Cross Section Evaluation Working Group (CSEWG) Benchmark Specifications. The CSEWG specifications included only two fast benchmarks and three thermal benchmarks. The thermal benchmarks were H 2 O-moderated thorium-oxide exponential lattices. Since the thorium-oxide lattices were exponential experiments, they have not been widely used. CSEWG has also used the 233 U Oak Ridge National Laboratory (ORNL) spheres for many years. One advantage of the CSEWG fast benchmarks, JEZEBEL-23 and FLATTOP-23, is that experiments were done for central-reaction-rate ratios. These reaction-rate ratios provide very valuable information to data testers and evaluators that would not otherwise be available. In recent years the International Handbook of Evaluated Criticality Safety Benchmark Experiments has, in general, been a very useful and reliable source. The Handbook does not include central-reaction-rate ratio experiments, however. A new set of 233 U benchmark experiments has been added to the most recent release of the Handbook, U233-SOL-THERM-004. These are paraffin-reflected cylinders of 233 U uranyl-nitrate solutions. Unfortunately, the estimated benchmark uncertainties are on the order of 0.9 to 1.0% in k eff . Benchmark testing has been done for some of these U233-SOL-THERM-004 experiments. The authors have also discovered that the benchmark specifications for the Thomas uranyl-nitrate experiments given in Ref. 5 are incorrect. One problem with the Ref. 5 specifications is that the excess acid was not included. As part of this work, the authors developed revised specifications that include an excess acid correlation based on information from the experimental logbook

Field studies on the terrestrial behavior of actinide elements in East Tennessee

International Nuclear Information System (INIS)

Garten, C.T. Jr.; Bondietti, E.A.; Trabalka, J.R.; Walker, R.L.; Scott, T.G.

1984-01-01

Field studies on the comparative uptake of various actinide elements ( 232 Th, 233 U, 238 U, 239 Pu, 241 Am, and 244 Cm) by plants and animals inhabiting historically contaminated environments on the Oak Ridge National Laboratory (ORNL) reservation in East Tennessee are summarized. The present-day pattern of actinide element bioaccumulation from a flood plain site contaminated with Pu in 1944 is U > Th approx. Pu. Thus the environmentally dispersed 239 Pu exhibits a transfer from floodplain soil to biota comparable to that of indigenous 232 Th and less than that of the indigenous 238 U. This ranking agrees with the chemical extractability of U, Th, and Pu from soil, using either weak acids or strongly basic reagents. The pattern of actinide element uptake from the shoreline of a historically contaminated pond is Pu 238 U = 233 U. This ranking also agrees with the chemical extractability of Pu, Am, Cm, and U from shoreline sediment, using weak acids. Results from field studies at ORNL agree with what has been generally inferred about the relative food chain transfer of the actinides, based on laboratory studies and field studies at other sites in the United States. Because they share the same valence state, there are apparent strong similarities in soil sorption, plant uptake, and animal uptake between trivalent Am and Cm and between tetravalent Pu and Th. Available evidence suggests that knowledge of the behavior of naturally occurring 232 Th in the terrestrial food chain can be useful for predicting the long-term fate of environmentally dispersed 239 Pu, while data on 238 U might be used to place an upper limit on the expected long-term food chain transfer of all transuranic elements except Np. 33 references, 5 figures, 1 table

Initial ORNL site assessment report on the storage of 233U

International Nuclear Information System (INIS)

Bereolos, P.J.; Yong, L.K.; Sadlowe, A.R.; Ramey, D.W.; Krichinsky, A.M.

1998-03-01

The 233 U storage facility at ORNL is Building 3019. The inventory stored in Building 3019 consists of 426.5 kg of 233 U contained in 1,387.1 kg of total uranium. The inventory is primarily in the form of uranium oxides; however, uranium metal and other compounds are also stored. Over 99% of the inventory is contained in 1,007 packages stored in tube vaults within the facility. A tank of thorium nitrate solution, the P-24 Tank, contains 0.13 kg of 233 U in ∼ 4,000 gal. of solution. The facility is receiving additional 233 U for storage from the remediation of the Molten Salt Reactor Experiment (MSRE) at ORNL. Consolidation of material from sites with small holdings is also adding to the 233 U inventory. Additionally, small quantities ( 233 U are in other research facilities at ORNL. A risk assessment process was chosen to evaluate the stored material and packages based on available package records. The risk scenario was considered the failure of a package (or a group of similar packages) in the Building 3019 inventory. The probability of such a failure depends on packaging factors such as the age and material of construction of the containers. The consequence of such a failure depends on the amount and form of the material within the packages. One thousand seven packages were categorized with this methodology resulting in 859 low-risk packages, 147 medium-risk packages, and 1 high-risk package. This initial assessment also documents the status of the evaluation of the Building 3019 and its systems for safe storage of 233 U. The final assessment report for ORNL storage of 233 U is scheduled for June 1999. The report will document the facility assessments, the specific package inspection plan, and the results of initial package inspections

Natural radionuclides from U-238 and Th-232 series and inorganic chemical characterization of soil profiles and sediment cores of the TaiaÇUpeba Reservoir, SÃO Paulo, Brazil

International Nuclear Information System (INIS)

Souza, J.M.; Damatto, S.R.; Surkov, A.M.; Silva, A.R.; Maduar, M.F.; Gonçalves, P.N.; Leonardo, L.

2017-01-01

Taiaçupeba reservoir, located in the state of São Paulo, Brazil, belongs to Producer System of Alto Tietê (Sistema Produtor Alto Tietê) and it is responsible for water supply for about 3.1million of people. The water quality of a reservoir is very important, but this is reduced by the increase of environmental degradation of the soil around the reservoir and its different uses. The study of soil profiles and sediment cores is an important tool for understanding the geophysical and geochemical aspects of an aquatic ecosystem. The objective of this work was to present the natural radionuclides 238 U, 226 Ra, 210 Pb, 232 Th, 228 Th, 228 Ra and 40 K activity concentrations and also the inorganic chemical characterization of four soil profiles and four sediment cores collected in the area of influence area of Taiaçupeba reservoir. The analytical techniques, gamma spectrometry and instrumental neutron activation analysis were used in the determination. In the soil profiles the highest activity concentrations were obtained for the radionuclides 40 K and 228 Th and the lowest for 210 Pb; in the sediment cores the highest activity concentrations were obtained for the radionuclide 210 Pb and the lowest for 226 Ra and 228 Ra. For the inorganic chemical characterization the highest values obtained were for Na, As and Sb; in a sediment core a very high concentration was obtained for the element Zn indicating a probable accumulation of this element inside the reservoir; enrichment factor was used to evaluate a possible anthropic contamination in the soil and sediment at the margins of Taiaçupeba reservoir. (author)

Gamma-spectrometric determination of {sup 232}U in uranium-bearing materials

Energy Technology Data Exchange (ETDEWEB)

Zsigrai, Jozsef [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), 76125 Karlsruhe, P.O. Box 2340 (Germany); Nguyen, Tam Cong [Centre for Energy Research of the Hungarian Academy of Sciences (EK), 1525 Budapest 114, P.O. Box 49 (Hungary); Berlizov, Andrey [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), 76125 Karlsruhe, P.O. Box 2340 (Germany)

2015-09-15

The {sup 232}U content of various uranium-bearing items was measured using low-background gamma spectrometry. The method is independent of the measurement geometry, sample form and chemical composition. Since {sup 232}U is an artificially produced isotope, it carries information about previous irradiation of the material, which is relevant for nuclear forensics, nuclear safeguards and for nuclear reactor operations. A correlation between the {sup 232}U content and {sup 235}U enrichment of the investigated samples has been established, which is consistent with theoretical predictions. It is also shown how the correlation of the mass ratio {sup 232}U/{sup 235}U vs. {sup 235}U content can be used to distinguish materials contaminated with reprocessed uranium from materials made of reprocessed uranium.

Seasonal variations of total 234Th and dissolved 238U concentration activities in surface water of Bransfield Strait, Antarctica, from March to October 2011

International Nuclear Information System (INIS)

Lapa, Flavia V.; Oliveira, Joselene de; Costa, Alice M.R.; Braga, Elisabete S.

2013-01-01

In this study the naturally occurring radionuclides 234 Th and 238 U were used to investigate the magnitude of upper ocean particulate organic carbon export in Bransfield Strait, Southern Ocean. This region is the largest oceanic high-nitrate low-chlorophyll (HNLC) area in the world and is known to contribute to regulate of the atmospheric CO 2 via the biological pump. Due to its different geochemical behavior in seawater, the resulting U/Th disequilibria can be easily used to constrain the transport rates of particles and reaction processes between solution and particulate phases. Sampling occurred during the summer (March and November) 2011. Total 234 Th activities in surface seawater samples ranged from 1.3 to 3.7 dpm L -1 (station EB 011) during March/11 campaign, while in October/11 total 234 Th activity concentrations varied from 1.4 to 2.9 dpm L -1 . Highest total 234 Th activities were found late in the austral summer season. Activity concentrations of dissolved 238 U in surface seawater varied from 2.1 to 2.4 dpm L -1 . Taking into account all sampling stations established in March and October/11 the relative variability of total 234 Th distribution was 22%. (author)

A compact multi-plate fission chamber for the simultaneous measurement of 233U capture and fission cross-sections

Directory of Open Access Journals (Sweden)

Bacak M.

2017-01-01

Full Text Available 233U plays the essential role of fissile nucleus in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section which is about one order of magnitude lower than the fission cross-section on average. Therefore, the accuracy in the measurement of the 233U capture cross-section essentially relies on efficient capture-fission discrimination thus a combined setup of fission and γ-detectors is needed. At CERN n_TOF the Total Absorption Calorimeter (TAC coupled with compact fission detectors is used. Previously used MicroMegas (MGAS detectors showed significant γ-background issues above 100 eV coming from the copper mesh. A new measurement campaign of the 233U capture cross-section and alpha ratio is planned at the CERN n_TOF facility. For this measurement, a novel cylindrical multi ionization cell chamber was developed in order to provide a compact solution for 14 active targets read out by 8 anodes. Due to the high specific activity of 233U fast timing properties are required and achieved with the use of customized electronics and the very fast ionizing gas CF4 together with a high electric field strength. This paper describes the new fission chamber and the results of the first tests with neutrons at GELINA proving that it is suitable for the 233U measurement.

Research on the reliability of measurement of natural radioactive nuclide concentration of U-238

Energy Technology Data Exchange (ETDEWEB)

Cha, Seok Ki; Kim, Gee Hyun [Dept. of Nuclear engineering, Univ. of SeJong, Seoul (Korea, Republic of); Joo, Sun Dong; Lee, Hoon [KoFONS, Seongnam (Korea, Republic of)

2016-12-15

Naturally occurred radioactive materials (NORM) can be found all around us and people are exposed to this no matter what they do or where they live. In this study, two indirect measurement methods of NORM U-238 has been reviewed; one that has used HPGe on the basis of the maintenance, and the other is disequilibrium theory of radioactive equilibrium relationships of mother and daughter nuclide at Decay-chain of NORM U-238. For this review, complicated pre-processing process (Breaking->Fusion->Chromatography->Electron deposit) has been used , and then carried out a comparative research with direct measurement method that makes use of and measures Alpha spectrometer. Through the experiment as above, we could infer the daughter nuclide whose radioactive equilibrium has been maintained with U-238. Therefore, we could find out that the daughter nuclide suitable to be applied to Gamma indirect measurement method was Th-234. Due to Pearson Correlation statistics, we could find out the reliability of the result value that has been analyzed by using Th-234.

Measurement of the 235U/238U fission cross section ratio in the 235U fission neutron spectrum

International Nuclear Information System (INIS)

Azimi-Garakani, D.; Bagheri-Darbandi, M.

1983-06-01

Fission cross section ratio of 235 U to 238 U has been measured in the fast neutron field generated by the 235 U fission plate installed on the thermal column of the Tehran Research Reactor (TRR) with a Makrofol solid state nuclear track detector. The experiments were carried out with a set of total six enriched 235 U and depleted 238 U deposits with different masses and Makrofol films of 0.025mm and 0.060mm thicknesses. The chemically etched tracks were counted by an optical microscope. No significant differences were observed with the thin and the thick films. The results showed that the average fission cross section ratio is 3.83+-0.25. (author)

IAEA CIELO Evaluation of Neutron-induced Reactions on 235U and 238U Targets

Science.gov (United States)

Capote, R.; Trkov, A.; Sin, M.; Pigni, M. T.; Pronyaev, V. G.; Balibrea, J.; Bernard, D.; Cano-Ott, D.; Danon, Y.; Daskalakis, A.; Goričanec, T.; Herman, M. W.; Kiedrowski, B.; Kopecky, S.; Mendoza, E.; Neudecker, D.; Leal, L.; Noguere, G.; Schillebeeckx, P.; Sirakov, I.; Soukhovitskii, E. S.; Stetcu, I.; Talou, P.

2018-02-01

Evaluations of nuclear reaction data for the major uranium isotopes 238U and 235U were performed within the scope of the CIELO Project on the initiative of the OECD/NEA Data Bank under Working Party on Evaluation Co-operation (WPEC) Subgroup 40 coordinated by the IAEA Nuclear Data Section. Both the mean values and covariances are evaluated from 10-5 eV up to 30 MeV. The resonance parameters of 238U and 235U were re-evaluated with the addition of newly available data to the existing experimental database. The evaluations in the fast neutron range are based on nuclear model calculations with the code EMPIRE-3.2 Malta above the resonance range up to 30 MeV. 235U(n,f), 238U(n,f), and 238U(n,γ) cross sections and 235U(nth,f) prompt fission neutron spectrum (PFNS) were evaluated within the Neutron Standards project and are representative of the experimental state-of-the-art measurements. The Standards cross sections were matched in model calculations as closely as possible to guarantee a good predictive power for cross sections of competing neutron scattering channels. 235U(n,γ) cross section includes fluctuations observed in recent experiments. 235U(n,f) PFNS for incident neutron energies from 500 keV to 20 MeV were measured at Los Alamos Chi-Nu facility and re-evaluated using all available experimental data. While respecting the measured differential data, several compensating errors in previous evaluations were identified and removed so that the performance in integral benchmarks was restored or improved. Covariance matrices for 235U and 238U cross sections, angular distributions, spectra and neutron multiplicities were evaluated using the GANDR system that combines experimental data with model uncertainties. Unrecognized systematic uncertainties were considered in the uncertainty quantification for fission and capture cross sections above the thermal range, and for neutron multiplicities. Evaluated files were extensively benchmarked to ensure good performance in

Photoneutron and Photonuclear Cross Sections According to Packed cluster Model

International Nuclear Information System (INIS)

El-Mekkawi, L.S.; El-Bakty, O.M.

1998-01-01

Photonuclear gross sections have been estimated for 232 Th, 237 Np, 239 Pu, 233 U, 234 U, 235 U, 238 U in the energy range from threshold up to 20 MeV, by perturbation balance in Packed Cluster. The Packed Cluster (gamma, f) and (gamma, n) cross sections require complete absence of any (gamma,2n) or (gamma,nf) cross sections for 233 U and 234 U as in experiment. It also explains the early (gamma,n) and gamma,nf) reactions in 235 U

Beta decay heat following U-235, U-238 and Pu-239 neutron fission

Science.gov (United States)

Li, Shengjie

1997-09-01

This is an experimental study of beta-particle decay heat from 235U, 239Pu and 238U aggregate fission products over delay times 0.4-40,000 seconds. The experimental results below 2s for 235U and 239Pu, and below 20s for 238U, are the first such results reported. The experiments were conducted at the UMASS Lowell 5.5-MV Van de Graaff accelerator and 1-MW swimming-pool research reactor. Thermalized neutrons from the 7Li(p,n)7Be reaction induced fission in 238U and 239Pu, and fast neutrons produced in the reactor initiated fission in 238U. A helium-jet/tape-transport system rapidly transferred fission fragments from a fission chamber to a low background counting area. Delay times after fission were selected by varying the tape speed or the position of the spray point relative to the beta spectrometer that employed a thin-scintillator-disk gating technique to separate beta-particles from accompanying gamma-rays. Beta and gamma sources were both used in energy calibration. Based on low-energy(energies 0-10 MeV. Measured beta spectra were unfolded for their energy distributions by the program FERD, and then compared to other measurements and summation calculations based on ENDF/B-VI fission-product data performed on the LANL Cray computer. Measurements of the beta activity as a function of decay time furnished a relative normalization. Results for the beta decay heat are presented and compared with other experimental data and the summation calculations.

Performance evaluation of indigenous thermal ionization mass spectrometer for determination of 235U/238U atom ratios

International Nuclear Information System (INIS)

Alamelu, D.; Parab, A.R.; Sasi Bhushan, K.; Shah, Raju V.; Jagdish Kumar, S.; Rao, Radhika M.; Aggarwal, S.K.; Bhatia, R.K.; Yadav, V.K.; Sharma, Madhavi P.; Tulsyan, Puneet; Chavda, Pradip; Sriniwasan, P.

2014-07-01

A magnetic sector based Thermal Ionization Mass Spectrometer (TIMS) designed and developed at Technical Physics Division, B.A.R.C., was evaluated for its performance for the determination of 235 U/ 238 U atom ratios in uranium samples. This consisted of evaluating the precision and accuracy on the 235 U/ 238 U atom ratios in various isotopic reference materials as well as indigenously generated uranium samples. The results obtained by the indigenous TIMS were also compared with those obtained using a commercially available TIMS system. The internal and external precision were found to be around 0.1% for determining 235 U/ 238 U atom ratios close to those of natural uranium ( i.e. 0.00730). (author)

Response of gadolinium doped liquid scintillator to charged particles: measurement based on intrinsic U/Th contamination

Science.gov (United States)

Du, Q.; Lin, S. T.; He, H. T.; Liu, S. K.; Tang, C. J.; Wang, L.; Wong, H. T.; Xing, H. Y.; Yue, Q.; Zhu, J. J.

2018-04-01

A measurement is reported for the response to charged particles of a liquid scintillator named EJ-335 doped with 0.5% gadolinium by weight. This liquid scintillator was used as the detection medium in a neutron detector. The measurement is based on the in-situ α-particles from the intrinsic Uranium and Thorium contamination in the scintillator. The β–α and the α–α cascade decays from the U/Th decay chains were used to select α-particles. The contamination levels of U/Th were consequently measured to be (5.54±0.15)× 10‑11 g/g, (1.45±0.01)× 10‑10 g/g and (1.07±0.01)× 10‑11 g/g for 232Th, 238U and 235U, respectively, assuming secular equilibrium. The stopping power of α-particles in the liquid scintillator was simulated by the TRIM software. Then the Birks constant, kB, of the scintillator for α-particles was determined to be (7.28±0.23) mg/(cm2ṡMeV) by Birks' formulation. The response for protons is also presented assuming the kB constant is the same as for α-particles.

Calculations of neutron and proton induced reaction cross sections for actinides in the energy region from 10 MeV to 1 GeV

International Nuclear Information System (INIS)

Konshin, V.A.

1995-01-01

Several nuclear model codes were applied to calculations of nuclear data in the energy region from 10 MeV to 1 GeV. At energies up to 100 MeV the nuclear theory code GNASH was used for nuclear data calculation for incident neutrons for 238 U, 233-236 U, 238-242 Pu, 237 Np, 232 Th, 241-243 Am and 242-247 Cm. At energies from 100 MeV to 1 GeV the intranuclear cascade exciton model including the fission process was applied to calculations of protons and neutrons with 233 U, 235 U, 238 U, 232 Th, 232 Pa, 237 Np, 238 Np, 239 Pu, 241 Am, 242 Am and 242-248 Cm. Determination of parameter systematics was a major effort in the present work that was aimed at improving the predictive capability of the models used. An emphasis was made on a simultaneous analysis of data for a variety of reaction channels for the nucleus considered, as well as of data that are available for nearby nuclei or other incident particles. Comparison with experimental data available on multiple reaction cross sections, isotope yields, fission cross sections, particle multiplicities, secondary particle spectra, and double differential cross sections indicates that the calculations reproduce the trends, and often the details, of the experimental data. (author)

Calculations of neutron and proton induced reaction cross sections for actinides in the energy region from 10MeV to 1GeV

International Nuclear Information System (INIS)

Konshin, V.A.

1995-06-01

Several nuclear model codes were applied to calculations of nuclear data in the energy region from 10MeV to 1GeV. At energies up to 100MeV the nuclear theory code GNASH was used for nuclear data calculation for neutrons incident for on 238 U, 233-236 U, 238-242 Pu, 237 Np, 232 Th, 241-243 Am and 242-247 Cm. At energies from 100MeV to 1GeV the intranuclear cascade exciton model including the fission process was applied to calculations of protons and neutrons with 233 U, 235 U, 238 U, 232 Th, 232 Pa, 237 Np, 238 Np, 239 Pu, 241 Am, 242 Am and 242-248 Cm. Determination of parameter systematics was a major effort in the present work that was aimed at improving the predictive capability of the models used. An emphasis was placed upon a simultaneous analysis of data for a variety of reaction channels for the nuclei considered, as well as of data that are available for nearby nuclei or for other incident particles. Comparisons with experimental data available on multiple reaction cross sections, isotope yields, fission cross sections, particle multiplicities, secondary particle spectra, and double differential cross sections indicate that the calculations reproduce the trends, and often the details, of the measurements data. (author) 82 refs

Transfer of 238U, 230Th, 226Ra, and 210Pb from soils to tree and shrub species in a Mediterranean area

International Nuclear Information System (INIS)

Blanco Rodriguez, P.; Vera Tome, F.; Lozano, J.C.; Perez Fernandez, M.A.

2010-01-01

The soil-to-plant transfer factors of natural uranium isotopes ( 238 U and 234 U), 230 Th, 226 Ra, and 210 Pb were studied in a disused uranium mine located in the Extremadura region in the south-west of Spain. The plant samples included trees (Quercus ilex, Quercus suber, and Eucalyptus cameldulensis) and one shrub (Cytisus multiflorus). All of them are characteristic of Mediterranean environments. The activity concentrations in leaves and fruit were determined for the tree species at different stages of growth. For the shrub, the total above-ground fraction was considered in three seasons. For old leaves and fruit, the highest activity concentrations were found in Eucalyptus cameldulensis for all the radionuclides studied, except in the case of 230 Th that presented similar activity concentrations in all of the tree species studied. In every case, the transfer to fruit was less than the transfer to leaves. In the shrub, the results depended on the season of sampling, with the highest value obtained in spring and the lowest in autumn. Important correlations were obtained for 238 U and 226 Ra between the activity ratio in soils with that in leaves or fruit.

Natural radionuclides from U-238 and Th-232 series and inorganic chemical characterization of soil profiles and sediment cores of the TaiaÇUpeba Reservoir, SÃO Paulo, Brazil

Energy Technology Data Exchange (ETDEWEB)

Souza, J.M.; Damatto, S.R.; Surkov, A.M.; Silva, A.R.; Maduar, M.F.; Gonçalves, P.N., E-mail: jmarques@ipen.br, E-mail: damatto@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Leonardo, L. [Centro Universitário São Camilo (Campus Ipiranga), São Paulo, SP (Brazil)

2017-07-01

Taiaçupeba reservoir, located in the state of São Paulo, Brazil, belongs to Producer System of Alto Tietê (Sistema Produtor Alto Tietê) and it is responsible for water supply for about 3.1million of people. The water quality of a reservoir is very important, but this is reduced by the increase of environmental degradation of the soil around the reservoir and its different uses. The study of soil profiles and sediment cores is an important tool for understanding the geophysical and geochemical aspects of an aquatic ecosystem. The objective of this work was to present the natural radionuclides {sup 238}U, {sup 226}Ra, {sup 210}Pb, {sup 232}Th, {sup 228}Th,{sup 228}Ra and {sup 40}K activity concentrations and also the inorganic chemical characterization of four soil profiles and four sediment cores collected in the area of influence area of Taiaçupeba reservoir. The analytical techniques, gamma spectrometry and instrumental neutron activation analysis were used in the determination. In the soil profiles the highest activity concentrations were obtained for the radionuclides {sup 40}K and {sup 228}Th and the lowest for {sup 210}Pb; in the sediment cores the highest activity concentrations were obtained for the radionuclide {sup 210}Pb and the lowest for {sup 226}Ra and {sup 228}Ra. For the inorganic chemical characterization the highest values obtained were for Na, As and Sb; in a sediment core a very high concentration was obtained for the element Zn indicating a probable accumulation of this element inside the reservoir; enrichment factor was used to evaluate a possible anthropic contamination in the soil and sediment at the margins of Taiaçupeba reservoir. (author)

Calculating the mass distribution of heavy nucleus fission product by neutrons

International Nuclear Information System (INIS)

Gudkov, A.N.; Koldobskij, A.B.; Kolobashkin, V.M.; Semenova, E.V.

1981-01-01

The technique of calculating the fission product mass yields by neutrons which are necessary for performing nucleus physical calculations in designing nuclear reactor cores is considered. The technique is based on the approximation of fission product mass distribution over the whole mass range by five Gauss functions. New analytical expressions for determining energy weights of used gaussians are proposed. The results of comparison of experimental data with calculated values for fission product mass obtained for reference processes in the capacity of which the fission reactions are chosen: 233 U, 235 U fission by thermal neutrons, 232 Th, 233 U, 235 U, 238 U by fission spectrum neutrons and 14 MeV neutrons and for 232 Th fission reactions by 11 MeV neutrons and 238 U by 7.7 MeV neutrons. On the basis of the analysis of results obtained the conclusion is drawn on a good agreement of fission product mass yield calculation values obtained using recommended values of mass distribution parameters with experimental data [ru

Present status of radiochemical double β decay study (238U)

International Nuclear Information System (INIS)

Chevallier, A.; Chevallier, J.; Escoubes, B.; Schulz, N.; Sens, J.C.; Madic, C.; Maillard, C.

1989-01-01

The reasons for which the 238 U is a suitable candidate for the β β decay processes are explained. The strategy adopted for the radiochemical separation of the 234 U is given. A chemical system based on extraction chromatography is applied. The Pu IV breakthrough curves obtained at 40C during 238 Pu/ 238 U separation cycles are presented. A short description of the chromatographic facility is given. The solution adopted for the low background α spectrometer is explained

Criticality considerations for 233U fuels in an HTGR fuel refabrication facility

International Nuclear Information System (INIS)

McNeany, S.R.; Jenkins, J.D.

1978-01-01

Eleven 233 U solution critical assemblies spanning an H/ 233 U ratio range of 40 to 2000 and a bare metal 233 U assembly have been calculated with the ENDF/B-IV and Hansen-Roach cross sections. The results from these calculations are compared with the experimental results and with each other. An increasing disagreement between calculations with ENDF/B and Hansen-Roach data with decreasing H/ 233 U ratio was observed, indicative of large differences in their intermediate energy cross sections. The Hansen-Roach cross sections appeared to give reasonably good agreement with experiments over the whole range; whereas the ENDF/B calculations yielded high values for k/sub eff/ on assemblies of low moderation. It is concluded that serious problems exist in the ENDF/B-IV representation of the 233 U cross sections in the intermediate energy range and that further evaluation of this nuclide is warranted. In addition, it is recommended that an experimental program be undertaken to obtain 233 U criticality data at low H/ 233 U ratios for verification of generalized criticality safety guidelines. Part II of this report presents the results of criticality calculations on specific pieces of equipment required for HTGR fuel refabrication. In particular, fuel particle storage hoppers and resin carbonization furnaces are criticality safe up to 22.9 cm (9.0 in.) in diameter providing water or other hydrogenous moderators are excluded. In addition, no criticality problems arise due to accumulation of particles in the off-gas scrubber reservoirs provided reasonable administrative controls are exercised

Sub-barrier photofission of 238U

International Nuclear Information System (INIS)

Bhandari, B.S.

Photofission cross section of 238 U below threshold have been calculated using a double humped potential barrier parameterized by smoothly joining four parabolas, and a coulomb potential at and beyond the scission point. Relative strength in the fission channel has been calculated and an attempt has been made to interpret the apparent resonance structures observed recently in photofission experiments of 238 U as excited states of the fission isomer. A set of parameters for a double humped barrier are found which are consistent with known spontaneous fission and isomeric fission half lives. In addition to reproducing satisfactorily the observed resonance structure near threshold, the calculation also predicts several low energy resonances in the cross sections [pt

Seasonal variations of total {sup 234}Th and dissolved {sup 238}U concentration activities in surface water of Bransfield Strait, Antarctica, from March to October 2011

Energy Technology Data Exchange (ETDEWEB)

Lapa, Flavia V.; Oliveira, Joselene de; Costa, Alice M.R., E-mail: fvlapa@ipen.br, E-mail: jolivei@ipen.br, E-mail: lice_mrc@hotmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Laboratorio de Radiometria Ambiental; Braga, Elisabete S., E-mail: edsbraga@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. Oceanografico. Lab. de Nutrientes, Micronutrientes e Tracos nos Oceanos

2013-07-01

In this study the naturally occurring radionuclides {sup 234}Th and {sup 238}U were used to investigate the magnitude of upper ocean particulate organic carbon export in Bransfield Strait, Southern Ocean. This region is the largest oceanic high-nitrate low-chlorophyll (HNLC) area in the world and is known to contribute to regulate of the atmospheric CO{sub 2} via the biological pump. Due to its different geochemical behavior in seawater, the resulting U/Th disequilibria can be easily used to constrain the transport rates of particles and reaction processes between solution and particulate phases. Sampling occurred during the summer (March and November) 2011. Total {sup 234}Th activities in surface seawater samples ranged from 1.3 to 3.7 dpm L{sup -1} (station EB 011) during March/11 campaign, while in October/11 total {sup 234}Th activity concentrations varied from 1.4 to 2.9 dpm L{sup -1}. Highest total {sup 234}Th activities were found late in the austral summer season. Activity concentrations of dissolved {sup 238}U in surface seawater varied from 2.1 to 2.4 dpm L{sup -1}. Taking into account all sampling stations established in March and October/11 the relative variability of total {sup 234}Th distribution was 22%. (author)

Multimode approximation for {sup 238}U photofission at intermediate energies

Energy Technology Data Exchange (ETDEWEB)

Demekhina, N. A., E-mail: demekhina@lnr.jinr.ru [Yerevan Physics Institute (Armenia); Karapetyan, G. S. [Yerevan State University (Armenia)

2008-01-15

The yields of products originating from {sup 238}U photofission are measured at the bremsstrahlung endpoint energies of 50 and 3500 MeV. Charge and mass distributions of fission fragments are obtained. Symmetric and asymmetric channels in {sup 238}U photofission are singled out on the basis of the model of multimode fission. This decomposition makes it possible to estimate the contributions of various fission components and to calculate the fissilities of {sup 238}U in the photon-energy regions under study.

@u234@@Th scavenging and particle export fluxes from the upper 100 m of the Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Sarin, M.M.; Rengarajan, R.; Ramaswamy, V.

for the upper 100 m yields a mean scavenging residence time of ~k30 days and a removal rate of ~k 3400 dpm m@u-2@@ d@u-1@@ for @u234@@Th, from dissolved to particulate phases. The deficiency of total @u234@@Th (dissolved + particulate) relative to @u238@@U...

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)

226Ra/238U disequilibrium in an upland organic soil exhibiting elevated natural radioactivity

International Nuclear Information System (INIS)

Dowdall, M.; O'Dea, J.

2002-01-01

This paper presents the results of a study into the anomalous 226 Ra/ 238 U disequilibrium ( 226 Ra/ 238 U of 0.5-9) exhibited by an upland organic soil in Co. Donegal, Ireland. Radiochemical speciation of 226 Ra, 238 U and 228 Ra indicates that in this organic soil the high 226 Ra/ 238 U ratio is due to loss of 238 U relative to 226 Ra via oxidation and mobilisation of 238 U in the upper layers of the soil and subsequent loss in solution. At the lower, more reducing depths of the soil profile, 238 U and 226 Ra are essentially in equilibrium. Loss of 238 U appears to occur primarily from the easily oxidised organic and iron oxide fractions of the soil, samples exhibiting high 226 Ra/ 238 U ratios displaying significantly lower 238 U levels in these fractions than samples whose ratio is below the average value for the soil of the valley. Selective enrichment of 226 Ra by plants or preferential leaching of 226 Ra from the underlying rock is not supported by the results of this study