Photofission of 232Th

International Nuclear Information System (INIS)

Arruda Neto, J.D.T.; Rigolon, W.; Herdade, S.B.; Riette, H.L.

1983-11-01

The bremsstrahlung-induced fission cross section of 232 Th was measured in the energy region of the Giant Dipole Resonance. The data analysis, performed in terms of the bremsstrahlung spectrum calculated in the Davies-Bethe-Maximon approximation, suggested that the photofission cross section measured at Livermore is correct, and that the (γ,f) data from Saclay are highly questionable. (Author) [pt

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

Distribution of nuclear charge in the proton-induced fission of Th-232

Energy Technology Data Exchange (ETDEWEB)

Pate, B D [Brookhaven National Laboratory, Upton, New York (United States); Foster, J S; Yaffe, L [McGill Univ., Montreal, Quebec (Canada)

1958-09-15

A great deal of work has been done on the distribution of nuclear mass in the fission process. About the nuclear charge distribution less is known. Data exist on the distribution from the fission of U-235 with thermal neutrons and with 14 Mev neutrons. Data also exist for the fission of uranium by 170 Mev protons, of bismuth by 190 Mev deuterons, and of uranium, thorium and bismuth by 480 Mev protons, and there is fragmentary information from other systems. The present work was undertaken to investigate the changes that occur in the charge distribution from proton-induced fission of Th-232 as the bombarding energy is raised from 8 to 90 Mev, the maximum proton energy of the McGill synchrocyclotron. This energy range is of interest in view of the substantial changes observed in the mass distribution. Also in this interval a change presumably begins in the nature of the initial step in nuclear reactions, from simple compound-nucleus formation, to a mechanism of direct interaction with individual nucleons. Thus at the lower energies studied, excitation of the nuclei at the end of the first step of the reaction will be essentially monochromatic whereas at the higher end of the bombarding-energy range, a broad spectrum of excitation energies will be produced, with corresponding complexity of the reaction products observed. (author)

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)

Study of transfer induced fission and fusion-fission reactions for 28 Si + 232 Th system at 340 MeV

International Nuclear Information System (INIS)

Prete, G.; Rizzi, V.; Fioretto, E.; Cinausero, M.; Shetty, D.V.; Pesente, S.; Brondi, A.; La Rana, G.; Moro, R.; Vardaci, E.; Boiano, A.; Ordine, A.; Gelli, N.; Lucarelli, F.; Bortignon, P.F.; Saxena, A.; Nayak, B.K.; Biswas, D.C.; Choudhury, R.K.; Kapoor, R.S.

2001-01-01

Full text: Fission induced by nucleons transfer has been investigated in the reaction 28 Si + 232 Th at 340 MeV. Looking at the projectile-like-fragments (PLF), the fission yield increases as the transfer increases, but a decreases is observed for transfers with DZ . Light charged particles in coincidence with PLF and Fission have been detected with large solid angle and show an increasing multiplicity as the Z of PLF is reduced and a constant value when fission is requested. The present results indicate inhibition of transfer induced fission reaction for higher Z transfer and increasing probability for decay through charged particle evaporation. Fission is the dominant decay process in heavy reactions involving fissile systems but the dynamical evolution of the composite system is largely governed by the formation and decay mechanisms. Important insight into the formation and the survival probability of the heavy composite nuclei formed in heavy ion collisions can be gained by simultaneously investigate the fission process and light particle emission over a continuous range of excitation energy, angular momentum and fissility. This can be achieved by studying fission induced by transfer of nucleons between the interacting projectile and the target nucleus. In the present work, we have carried out measurements on multinucleon transfer induced fission reactions in 28 Si + 232 Th system at Elab = 340 MeV. The experiment has been performed at the Laboratori Nazionale di Legnaro (LNL) using the 8pLP detector in its final configuration with 257 DE-E telescopes. The backward detectors were used to measure both light charged particles and fission fragments. The projectile-like fragments were detected using separate DE-E telescopes around the grazing angle. Two neutron detectors were placed at a distance of 115.5 cm from the target to measure neutrons emitted in coincidence with fission fragments. Here we present the results of the data analysis of transfer induced fission

Mass dependence of azimuthal asymmetry in the fission of 232Th and 233,235,236,238U by polarized photons

International Nuclear Information System (INIS)

Denyak, V.V.; Khvastunov, V.M.; Paschuk, S.A.; Schelin, H.R.

2013-01-01

Fission of the even-even nuclei 232 Th, 236,238 U and even-odd nuclei 233,235 U by linearly polarized photons has been studied at excitation energies in the region of a giant dipole resonance. The performed investigations unambiguously showed the existence of the fragment mass dependence of the cross section azimuthal asymmetry in the photofission of 236 U and 238 U. In addition, the obtained results provided the first evidence for the possible difference between the asymmetry values in asymmetric and symmetric mass distribution regions in the case of 236 U. The measured cross section azimuthal asymmetry of the fission of 232 Th does not show any fragment mass dependence. In the even-odd nuclei 233 U and 235 U the difference between the far-asymmetric and other mass distribution regions was also observed but with the statistical uncertainty not small enough for definitive conclusion. (orig.)

Measurement of Fission Fragment Angular Distributions for 14 N+ 232 Th and 11 B+ 235 U at Near-Barrier Energies

International Nuclear Information System (INIS)

Behera, B.R.; Jena, S.; Satapathy, M.; Ison, V.V.; Kailas, S.; Chatterjee, A.; Shrivastava, A.; Mahata, K.; Satpathy, L.; Basu, P.; Roy, S.; Sharan, M.; Chatterjee, M.L; Datta, S.K.

2000-01-01

Fission fragment angular distributions of heavy-ion induced fission in actinide nuclei at near-barrier energies show anomalous fragment anisotropies. At above barrier energies entrance channel dependence is a probable cause and explanation in terms of pre-equilibrium fission and the critical mass asymmetry parameter (Businaro-Gallone) has been tried. Target deformation and ground state spin also seem to influence the measured anisotropy. To understand the extent of importance of some or all of these features, we performed a set of experiments where (i) entrance channel dependence (ii) mass asymmetry on the two sides of Businaro-Gallone and (iii) different ground state spins are present. The channels chosen are 14 N+ 232 Th and 11 B+ 235 U. Experiments were done using the Pelletron accelerators at NSC, New Delhi and BARC-TIFR, Bombay. Compound nucleus populated in both cases is 246 Bk. 232 Th has ground state spin zero and 235 U has spin 7/2. Fragment anisotropies have been measured from 10-15 % above barrier to 10 % below barrier at similar excitation energy (around 40 MeV to 58 MeV). The mean square angular momentum is matched at least at one energy. Results indicate that when both excitation energy and angular momentum are matched, there are differences in the measured values of fission anisotropies. This implies entrance channel dependence consistent with the expectation of pre-equilibrium fission model. (authors)

Mass distribution studies in 28Si + 232Th

International Nuclear Information System (INIS)

Sodaye, Suparna; Tripathi, R.; Sudarshan, K.; Pujari, P.K.

2014-01-01

Mass distribution is one of the important observables to understand the fusion-fission potential energy landscape. In the fission involving composite systems with Z ∼ 100, the fission barrier is lower and the saddle point is compact. Thus, apart from transfer induced fission,various non compound nucleus (NCN) fission processes like quasi-fission, pre-equilibrium fission and fast fission compete with the complete fusion fission (CFF). This would be further affected by the entrance channel parameters like choice of the target-projectile combination (mass asymmetry) and the projectile energy. Charge and mass distribution studies in such system would provide information about various fission processes such as complete fusion fission, non-compound nucleus fission and transfer induced fission, which would help in understanding the fusion-fission process in heavy ion collisions forming composite system in the heavy and trans-actinide region. In view of this, a systematic study of the charge and mass distribution in 28 Si+ 232 Th reaction was planned at beam energy close to and above the entrance channel Coulomb barrier. The experiments were carried out at the TIFR-LINAC booster facility. Self supporting foils of 232 Th were bombarded with 180 and 160 MeV 28 Si beam in a stack foil arrangement. The recoiling fission products were assayed radiochemically by off-line gamma-ray spectrometry. Results of charge distribution studies at E lab =180 MeV have been reported earlier. In the poster, the data on charge and mass distribution distribution will be presented.The results of the present studies will be compared with those from the reactions involving lighter and heavier composite systems

Mass distribution in 20Ne+232Th reaction

International Nuclear Information System (INIS)

Sodaye, Suparna; Tripathi, R.; Sudarshan, K.

2011-01-01

Mass distribution was measured in 20 Ne+ 232 Th reaction at E lab =145 MeV using recoil catcher technique followed by off-line gamma-ray spectrometry. Significant contribution from transfer fission was observed in the yield of comparatively neutron rich fission products. The variance of mass distribution for complete fusion fission, obtained by excluding neutron rich fission products, was observed to be consistent with the values reported in literature for similar reaction systems which showed a deviation from the systematics obtained using random neck rupture and liquid drop model. (author)

Measurements of isomeric yield ratios of fission products from proton-induced fission on natU and 232Th via direct ion counting

Directory of Open Access Journals (Sweden)

Rakopoulos Vasileios

2017-01-01

Full Text Available Independent isomeric yield ratios (IYR of 81Ge, 96Y, 97Y, 97Nb, 128Sn and 130Sn have been determined in the 25 MeV proton-induced fission of natU and 232Th. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL facility at the University of Jyväskylä. A direct ion counting measurement of the isomeric fission yield ratios was accomplished for the first time, registering the fission products in less than a second after their production. In addition, the IYRs of natU were measured by means of γ-spectroscopy in order to verify the consistency of the recently upgraded experimental setup. From the obtained results, indications of a dependence of the production rate on the fissioning system can be noticed. These data were compared with data available in the literature, whenever possible. Using the TALYS code and the experimentally obtained IYRs, we also deduced the average angular momentum of the fission fragments after scission.

Mass dependence of azimuthal asymmetry in the fission of {sup 232}Th and {sup 233,235,236,238}U by polarized photons

Energy Technology Data Exchange (ETDEWEB)

Denyak, V.V. [National Science Center ' ' Kharkov Institute of Physics and Technology' ' , Kharkiv (Ukraine); Pele Pequeno Principe Research Institute, Curitiba (Brazil); Khvastunov, V.M. [National Science Center ' ' Kharkov Institute of Physics and Technology' ' , Kharkiv (Ukraine); Paschuk, S.A. [Federal University of Technology - Parana, Curitiba (Brazil); Schelin, H.R. [Federal University of Technology - Parana, Curitiba (Brazil); Pele Pequeno Principe Research Institute, Curitiba (Brazil)

2013-04-15

Fission of the even-even nuclei {sup 232}Th, {sup 236,238}U and even-odd nuclei {sup 233,235}U by linearly polarized photons has been studied at excitation energies in the region of a giant dipole resonance. The performed investigations unambiguously showed the existence of the fragment mass dependence of the cross section azimuthal asymmetry in the photofission of {sup 236}U and {sup 238}U. In addition, the obtained results provided the first evidence for the possible difference between the asymmetry values in asymmetric and symmetric mass distribution regions in the case of {sup 236}U. The measured cross section azimuthal asymmetry of the fission of {sup 232}Th does not show any fragment mass dependence. In the even-odd nuclei {sup 233}U and {sup 235}U the difference between the far-asymmetric and other mass distribution regions was also observed but with the statistical uncertainty not small enough for definitive conclusion. (orig.)

Measurement of fission cross section for {sup 232}Th(n,f){sup 131}{sub Z}X (Z = 50, 51, 52, 53) reaction induced by neutrons around 14 MeV

Energy Technology Data Exchange (ETDEWEB)

Lan, Chang-lin; Qiu, Yi-jia; Wang, Qiang; Zhang, Zheng-wei; Zhang, Qian; Tan, Jun-cai; Fang, Kai-hong [Lanzhou University, School of Nuclear Science and Technology, Lanzhou (China); Lai, Cai-feng [China Academy of Engineering Physics, Institute of Nuclear Physics and Chemistry, Mianyang (China)

2017-06-15

The fission cross sections of {sup 232}Th(n,f){sup 131m,g}Sn, {sup 232}Th(n,f){sup 131}Sb, {sup 232}Th(n,f){sup 131m,g}Te, {sup 232}Th(n,f){sup 131}I fission reactions induced by 14 MeV neutrons were measured precisely with the neutron activation technique. The neutron flux was monitored by accompanying α particle in the irradiation and the neutron energies were determined by the cross section ratio of {sup 90}Zr(n,2n){sup 89}Zr to {sup 93}Nb(n,2n){sup 92m}Nb reaction. The values of the cross sections of {sup 232}Th(n,f){sup 131m,g}Sn were analyzed, and the cross sections of {sup 232}Th(n,f){sup 131}Sb were deduced to be 6.5±0.7, 6.3±0.6, 6.1±0.6 mb at 14.1±0.3, 14.5±0.3 and 14.8±0.3 MeV, respectively. The values of the cross sections of {sup 232}Th(n,f){sup 131g}Te were deduced to be 1.8 ± 0.1, 1.5 ± 0.1 and 1.4±0.1 mb at 14.1±0.3, 14.5±0.3 and 14.8±0.3 MeV, respectively. The values of the cross sections of {sup 232}Th(n,f){sup 131}I were given as 1.8±0.2, 1.6±0.2, 1.5±0.1 mb at 14.1±0.3, 14.5±0.3 and 14.8±0.3 MeV, respectively. (orig.)

Measurement of the neutron-induced fission cross section of 232Th relative to 235U from 0.7 to 30 MeV

International Nuclear Information System (INIS)

Behzens, T.W.; Ables, E.; Browne, T.C.

1982-01-01

The authors have measured the fission cross-section ratio 232 Th: 235 U as a function of neutron energy from 0.7 to 30 MeV using ionization fission chambers, the threshold cross-section method, and the time-of-flight technique at the Lawrence Livermore National Laboratory 100-MeV electron linear accelerator. The measured cross-section ratio, averaged over the neutron energy interval from 1.75 to 4.00 MeV, was 0.1086 + 0.0024

Measurement of fission yields for 232-Th (n,f) at 14,7 MeV by direct gamma spectrometric method

International Nuclear Information System (INIS)

Chouak, K.; Berrada, M.; Embarech, K.

1994-01-01

Fission yields for the reaction 232-Th (n,f) were measured at 14,7 MeV using the activation technique with direct gamma spectrometric method. Neutrons were produced via the T(d,n) sup 4 He reaction. The neutron fluences were determined relative to the well-known sup 2 sup 7 Al(n,p) sup 2 sup 7 Mg or sup 2 sup 7 Al(n,alpha) sup 2 sup 4 Na cross section, according to the irradiation time. Yields of fission products were determined by measuring the induced gamma ray activities of the irradiated Th foils, using a calibrated Ge(Li) detector. All necessary corrections were taken into account: self absorption, coincidence losses and natural gamma rays. Fifty six cumulative yields were measured and only twenty one corresponding results were found in the literature (Crouch,1977). A satisfactory agreement is observed between our results and the published data with the exception of the masses:A=134 and A=140. 1 tab., 2 refs. (author)

Delayed Fission Gamma-ray Characteristics of Th-232 U-233 U-235 U-238 and Pu-239

Energy Technology Data Exchange (ETDEWEB)

Lane, Taylor [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Parma, Edward J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-08-01

Delayed fission gamma-rays play an important role in determining the time dependent ioniz- ing dose for experiments in the central irradiation cavity of the Annular Core Research Reactor (ACRR). Delayed gamma-rays are produced from both fission product decay and from acti- vation of materials in the core, such as cladding and support structures. Knowing both the delayed gamma-ray emission rate and the time-dependent gamma-ray energy spectrum is nec- essary in order to properly determine the dose contributions from delayed fission gamma-rays. This information is especially important when attempting to deconvolute the time-dependent neutron, prompt gamma-ray, and delayed gamma-ray contribution to the response of a diamond photo-conducting diode (PCD) or fission chamber in time frames of milliseconds to seconds following a reactor pulse. This work focused on investigating delayed gamma-ray character- istics produced from fission products from thermal, fast, and high energy fission of Th-232, U-233, U-235, U-238, and Pu-239. This work uses a modified version of CINDER2008, a transmutation code developed at Los Alamos National Laboratory, to model time and energy dependent photon characteristics due to fission. This modified code adds the capability to track photon-induced transmutations, photo-fission, and the subsequent radiation caused by fission products due to photo-fission. The data is compared against previous work done with SNL- modified CINDER2008 [ 1 ] and experimental data [ 2 , 3 ] and other published literature, includ- ing ENDF/B-VII.1 [ 4 ]. The ability to produce a high-fidelity (7,428 group) energy-dependent photon fluence at various times post-fission can improve the delayed photon characterization for radiation effects tests at research reactors, as well as other applications.

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)

Coulomb fission and transfer fission at heavy ion collisions

International Nuclear Information System (INIS)

Himmele, G.

1981-01-01

In the present thesis the first direct evidence of nuclear fission after inelastic scattering of heavy ions (sup(183,184)W, 152 Sm → 238 U; 184 W → 232 Th; 184 W, 232 Th → 248 Cm) is reported. Experiments which were performed at the UNILAC of the Gesellschaft fuer Schwerionenforschung in Darmstadt show the observed heavy ion induced fission possesses significant properties of the Coulomb fission. The observed dependence of the fission probability for inelastic scattering on the projectile charge proves that the nuclear fission is mediated by the electromagnetic interaction between heavy ions. This result suggests moreover a multiple Coulomb-excitation preceding the fission. Model calculations give a first indication, that the Coulomb fission proceeds mainly from the higher β phonons. In the irradiation with 184 W the fission probability of 232 Th is for all incident energies about 40% smaller that at 238 U. The target dependence of the Coulomb fission however doesn't allow, to give quantitative statements about the position and B(E2)-values of higher lying β phonons. (orig./HSI) [de

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.

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)

Measurement of the neutron capture cross-section of 232Th using the neutron activation technique

International Nuclear Information System (INIS)

Naik, H.; Singh, Sarbjit; Goswami, A.; Manchanda, V.K.; Prajapati, P.M.; Surayanarayana, S.V.; Nayak, B.K.; Sharma, S.C.; Jagadeesan, K.C.; Thakare, S.V.; Raj, D.; Ganesan, S.; Mulik, V.K.; Sivashankar, B.S.; Mukherjee, S.

2011-01-01

The 232 Th(n, γ) reaction cross-section at average neutron energies of 3.7±0.3 MeV and 9.85±0.38 MeV from the 7 Li(p, n) reaction has been determined for the first time using activation and off-line γ -ray spectrometric technique. The 232 Th(n, 2n) reaction cross-section at the average neutron energy of 9.85±0.38 MeV has been also determined using the same technique. The experimentally determined 232 Th(n, γ) and 232 Th(n, 2n) reaction cross-sections were compared with the evaluated data of ENDF/B-VII, JENDL-4.0 and JEFF-3.1 and were found to be in good agreement. The present data along with literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels including fission. The 232 Th(n, γ) and 232 Th(n, 2n) reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were found to be slightly higher than the experimental data. (orig.)

Mass and energy distribution of fragments of sup 232 Th nucleus fission by 21-26. 4 MeV. alpha. -particles. Massovye i ehnergeticheskie raspredeleniya oskolkov deleniya yadra sup 232 Th. alpha. -chastitsami s ehnergiyami 21-26,4 MehV

Energy Technology Data Exchange (ETDEWEB)

Zaika, N I; Kibkalo, Yu V; Parlag, O A; Sikora, D I; Tokarev, V P; Shityuk, V A [AN Ukrainskoj SSR, Kiev (Ukrainian SSR). Inst. Yadernykh Issledovanij

1989-04-01

Two-parameter measurements of the mass and energy distributions of fission products in the fission of {sup 232}Th by 21.0-26.4 MeV {alpha}-particles (h=1 MeV) are conducted using the correlation method. The obtained results show that in the region under investigation the average total kinetic energies of the fission products E-bar{sub k} have no noticeable variations within the experimental error of {plus minus} 1.5 MeV and the dispersion {sigma}{sup 2}E{sub k} slowly increases. For the E-bar{sub k} mass dependence of heavy fraction the maximum is observed at A=132, that confirms a hypothesis on the influence of the closed-shell effects at the magic numbers of Z=50 and N=82. Assuming the existence of different barrier values for two models of the fission the ratio of symmetric and asymmetric fission yields are analyzed in the statistical model. It is shown that the barrier difference for two modes of fission is 1.3-1.4 MeV, which is in good agreement with the model of two fission modes.

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

International Nuclear Information System (INIS)

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

1978-01-01

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

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

The fission cross sections of 230Th, 232Th, 233U, 234U, 236U, 238U, 237Np, 239Pu and 242Pu relative 235U at 14.74 MeV neutron energy

International Nuclear Information System (INIS)

Meadows, J.W.

1986-12-01

The measurement of the fission cross section ratios of nine isotopes relative to 235 U at an average neutron energy of 14.74 MeV is described with particular attention to the determination of corrections and to sources of error. The results are compared to ENDF/B-V and to other measurements of the past decade. The ratio of the neutron induced fission cross section for these isotopes to the fission cross section for 235 U are: 230 Th - 0.290 +- 1.9%; 232 Th - 0.191 +- 1.9%; 233 U - 1.132 +- 0.7%; 234 U - 0.998 +- 1.0%; 236 U - 0.791 +- 1.1%; 238 U - 0.587 +- 1.1%; 237 Np - 1.060 +- 1.4%; 239 Pu - 1.152 +- 1.1%; 242 Pu - 0.967 +- 1.0%. 40 refs., 11 tabs., 9 figs

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

Measurement of fission cross-section for the {sup 232}Th(n,f){sup 141}Ba reaction induced by neutrons around 14 MeV

Energy Technology Data Exchange (ETDEWEB)

Lan, Chang-Lin; Fang, Kai-Hong [Lanzhou University, School of Nuclear Science and Technology, Lanzhou, Gansu Province (China); Lanzhou University, Engineering Research Center for Neutron Application, Ministry of Education, Lanzhou, Gansu Province (China); Liu, Shuang-Tong; Lv, Tao; Wang, Qiang; Zhang, Zheng-Wei [Lanzhou University, School of Nuclear Science and Technology, Lanzhou, Gansu Province (China); Lai, Cai-Feng [Chinese Academy of Engineering Physics, Institute of Nuclear Physics and Chemistry, Mianyang, Sichuan Province (China)

2016-11-15

The fission cross-section of the {sup 232}Th(n,f){sup 141}Ba reaction induced by neutrons around 14 MeV was measured precisely with the neutron activation and off-line gamma-ray spectrometric technique. Neutron fluence was monitored on-line using the accompanying α-particles from the {sup 3}H({sup 2}H,n){sup 4}He reaction, whereas the neutron energies were measured by the method of cross-section ratios of {sup 90}Zr(n,2n){sup 89}Zr to {sup 93}Nb(n,2n){sup 92m}Nb reactions. The experimentally determined {sup 232}Th(n,f){sup 141}Ba reaction cross-sections were 12.2 ± 0.4 mb at E{sub n} = 14.1 ± 0.3 MeV, 13.0 ± 0.5 mb at E{sub n} = 14.5 ± 0.3 MeV and 13.3 ± 0.5 mb at E{sub n} = 14.7 ± 0.3 MeV, respectively. (orig.)

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.)

The status of 232Th and 233U for CENDL-3.0

International Nuclear Information System (INIS)

Liu Ping

2003-01-01

The new version CENDL-3.0 of China: Evaluated nuclear data library has been updated, and contains about 200 nuclides. Among them, the data of following nuclides have been newly evaluated or reevaluated: fissile nuclides 15, structure materials 18, light nuclides 3, fission products 116. The 232 Th and 233 U are newly evaluated

Neutron-induced fission fragment angular distribution at CERN n TOF: The Th-232 case

CERN Document Server

Tarrio, Diego; Paradela, Carlos

This thesis work was done in the frame of the study of the neutron-induced fission of actinides and subactinides at the CERN n TOF facility using a fast Parallel Plate Avalanche Counters (PPACs) setup. This experimental setup provide us with an intense neutron beam with a white spectrum from thermal to 1 GeV and with an outstanding high resolution provided by its flight path of 185 m. In our experiment, fission events were identified by detection of both fission fragments in time coincidence in the two PPAC detectors flanking the corresponding target. This technique allowed us to discriminate the fission events from the background produced by α disintegration of radioactive samples and by particles produced in spallation reactions. Because PPAC detectors are insensitive to the γ flash, it is possible to reach energies as high as 1 GeV. The stripped cathodes provide the spatial position of the hits in the detectors, so that the emission angle of the fission fragments can be measured. Inside the reaction cham...

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)

Method of measurement of cross sections of heavy nuclei fission induced by intermediate energy protons

International Nuclear Information System (INIS)

Kotov, Alexander; Chtchetkovski, Alexander; Fedorov, Oleg; Gavrikov, Yuri; Chestnov, Yuri; Poliakov, Vladimir; Vaishnene, Larissa; Vovchenko, Vil; Fukahori, Tokio

2003-01-01

The purpose of this work is experimental studies of the energy dependence of the fission cross sections of heavy nuclei, nat Pb, 209 Bi, 232 Th, 233 U, 235 U, 238 U, 237 Np and 239 Pu, by protons at the energies from 200 to 1000 MeV. At present experiment the method based on use of the gas parallel plate avalanche counters (PPACs) for registration of complementary fission fragments in coincidence and the telescope of scintillation counters for direct counting of the incident protons on the target has been used. First preliminary results of the energy dependences of proton induced fission cross sections for nat Pb, 209 Bi, 235 U and 238 U are reported. (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

Fission fragment angular distributions and fission cross section validation

International Nuclear Information System (INIS)

Leong, Lou Sai

2013-01-01

The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238 U and 232 Th have been investigated up to 100 MeV in a single experiment. The n-TOF Collaboration performed the fission cross section measurement of several actinides ( 232 Th, 235 U, 238 U, 234 U, 237 Np) at the n-TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232 Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3. chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232 Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237 Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n-TOF facility at CERN. When compared to previous measurements, the n-TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n-TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237 Np. This

Collection and evaluation of nuclear data of Th-232

International Nuclear Information System (INIS)

Osawa, Takaaki

1979-01-01

Present status of the requirement to and measurement and evaluation of the nuclear data of Th-232 is presented. The accuracy and energy range of the observed data at present are not enough to the demand from reactor engineering. The data of total cross-section are given in the energy range from 1.5 to 15 MeV from the data by Foster and Fasoli. The data by Uttley for the energy less than 1.5 MeV were accepted. Recently, Whalen and Kobayashi presented new data. Optical potential parameters were deduced. Re-normalization of the capture cross-sections of Th-232 was made on the basis of the evaluated values by Matsunobu and by Kanda. The values are a little smaller than the values in ENDF/B-4. Fission cross-sections were given by Henkel up to 9 MeV, and by Rago and Pankratov for the energy range above 9 MeV. Recently, Behrens presented new data for wide energy range. The accuracy of the measured cross-sections of inelastic scattering is not enough for reactor design. The accurate values of the cross-sections of (n, 2n) reaction of Th-232 have been demanded. Resonance parameters have been measured for wide energy range. In the energy range of thermal neutrons, the capture cross-section is about 7.4 barn. The characteristics of velocity dependence of the capture cross-section in this range should be investigated. (Kato, T.)

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.

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.

A new neutron counter for fission research

Energy Technology Data Exchange (ETDEWEB)

Laurent, B., E-mail: benoit.laurent@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Granier, T.; Bélier, G.; Chatillon, A.; Martin, J.-F.; Taieb, J. [CEA, DAM, DIF, F-91297 Arpajon (France); Hambsch, F.-J. [EC-JRC Institute for Reference Materials and Measurements (IRMM), Retieseweg, 2440 Geel (Belgium); Tovesson, F.; Laptev, A.B.; Haight, R.C.; Nelson, R.O.; O' Donnell, J.M. [Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2014-05-01

A new neutron counter for research experiments on nuclear fission has been developed. This instrument is designed for the detection of prompt fission neutrons within relatively high levels of gamma and neutron background. It is composed of a set of {sup 3}He proportional counters arranged within a block of polyethylene which serves as moderator. The detection properties have been studied by means of Monte Carlo simulations and experiments with radioactive sources. These properties are confirmed by an experiment on neutron-induced fission of {sup 238}U at the WNR facility of the Los Alamos Neutron Science Center during which the mean prompt fission neutron multiplicity, or ν{sup ¯} has been measured from 1 to 20 MeV of incident neutron energy.

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

Angular distribution in the neutron-induced fission of actinides

Directory of Open Access Journals (Sweden)

Leong L.S.

2013-12-01

Full Text Available Above 1 MeV of incident neutron energy the fission fragment angular distribution (FFAD has generally a strong anisotropic behavior due to the combination of the incident orbital momentum and the intrinsic spin of the fissioning nucleus. This effect has to be taken into account for the efficiency estimation of devices used for fission cross section measurements. In addition it bears information on the spin deposition mechanism and on the structure of transitional states. We designed and constructed a detection device, based on Parallel Plate Avalanche Counters (PPAC, for measuring the fission fragment angular distributions of several isotopes, in particular 232Th. The measurement has been performed at n_TOF at CERN taking advantage of the very broad energy spectrum of the neutron beam. Fission events were recognized by back to back detection in coincidence in two position-sensitive detectors surrounding the targets. The detection efficiency, depending mostly on the stopping of fission fragments in backings and electrodes, has been computed with a Geant4 simulation and validated by the comparison to the measured case of 235U below 3 keV where the emission is isotropic. In the case of 232Th, the result is in good agreement with previous data below 10 MeV, with a good reproduction of the structures associated to vibrational states and the opening of second chance fission. In the 14 MeV region our data are much more accurate than previous ones which are broadly scattered.

A comprehensive test specification for pulse fission counters

Energy Technology Data Exchange (ETDEWEB)

Roberts, D L [Control and Instrumentation Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

1962-02-15

The following test specification is based on the memorandum AERE - M 728 which it now replaces It contains a standard acceptance test procedure for the many U.K.A.E.A, designed pulse fission counters now commercially available. This test specification may be used for any pulse fission counter provided a specification sheet as shown in Appendix 3 is supplied to the contractor quoting this report and including specified values for the measured quantities. (author)

Statistical and dynamical aspects in fission process: The rotational ...

Indian Academy of Sciences (India)

the fission process, during the evolution from compound nucleus to the ..... For fission induced by light particles like n, p, and α, the total angular momenta ... 96 MeV. 16O+232Th. SaddleTSM. 72 MeV. 10B+232Th. 1.2. 1.4. 1.6. 1.8. 80 ... Systematic investigations in both light- and heavy-ion-induced fissions have shown that.

Development of a “Fission-proxy” Method for the Measurement of 14-MeV Neutron Fission Yields at CAMS

Energy Technology Data Exchange (ETDEWEB)

Gharibyan, Narek [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-25

Relative fission yield measurements were made for 50 fission products from 25.6±0.5 MeV alpha-induced fission of Th-232. Quantitative comparison of these experimentally measured fission yields with the evaluated fission yields from 14-MeV neutron-induced fission of U-235 demonstrates the feasibility of the proposed fission-proxy method. This new technique, based on the Bohr-independence hypothesis, permits the measurement of fission yields from an alternate reaction pathway (Th-232 + 25.6 MeV α → U-236* vs. U-235 + 14-MeV n → U-236*) given that the fission process associated with the same compound nucleus is independent of its formation. Other suitable systems that can potentially be investigated in this manner include (but are not limited to) Pu-239 and U-237.

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...

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 and /sup 242/Pu relative /sup 235/U at 14. 74 MeV neutron energy

Energy Technology Data Exchange (ETDEWEB)

Meadows, J.W.

1986-12-01

The measurement of the fission cross section ratios of nine isotopes relative to /sup 235/U at an average neutron energy of 14.74 MeV is described with particular attention to the determination of corrections and to sources of error. The results are compared to ENDF/B-V and to other measurements of the past decade. The ratio of the neutron induced fission cross section for these isotopes to the fission cross section for /sup 235/U are: /sup 230/Th - 0.290 +- 1.9%; /sup 232/Th - 0.191 +- 1.9%; /sup 233/U - 1.132 +- 0.7%; /sup 234/U - 0.998 +- 1.0%; /sup 236/U - 0.791 +- 1.1%; /sup 238/U - 0.587 +- 1.1%; /sup 237/Np - 1.060 +- 1.4%; /sup 239/Pu - 1.152 +- 1.1%; /sup 242/Pu - 0.967 +- 1.0%. 40 refs., 11 tabs., 9 figs.

An integral experiment on thorium oxide/depleted uranium cylinders with D-T neutrons for 232Th(n, 2n) reaction

International Nuclear Information System (INIS)

Feng, S.; Yang, Y.W.; Lu, X.X.; Liu, R.; Jiang, L.; Zhu, T.H.; Wang, M.; Qin, J.G.

2015-01-01

Highlights: • An integral experiment for 232 Th(n, 2n) reaction was carried out on the newly-established ThO 2 /depleted uranium cylinders. • 232 Th(n, 2n) reaction rate distribution was obtained in the assemblies with an uncertainty of about 7%. • Experiments were analyzed by MCNP code with ENDF/B-VI.8, ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries. • Experimental results could be used to re-evaluate the cross sections of 232 Th(n, 2n) reaction. - Abstract: In order to verify the evaluated cross sections of 232 Th(n, 2n) reaction for the conceptual design of the thorium based subcritical blanket in the fusion–fission hybrid reactor, an integral experiment on thorium oxide/depleted uranium cylinders was carried out with D-T neutrons using the activation technique. 232 Th(n, 2n) reaction rate distribution was obtained at the central axis direction in the assemblies with an uncertainty of about 7%. Experiments were analyzed by using MCNP code with ENDF/B-VI.8, ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries to validate the nuclear data libraries of 232 Th(n, 2n) reaction, the calculated results with JENDL-4.0 agree with the measurements the best with discrepancies within the experimental uncertainty. The average values of C/E for the three benchmark assemblies are 1.058, 1.044 and 0.980. Calculations with different evaluated libraries in the benchmark assemblies show a large discrepancy. The experimental results can be used to re-evaluate the cross sections of the 232 Th(n, 2n) reaction

Muon-induced fission

International Nuclear Information System (INIS)

Polikanov, S.

1980-01-01

A review of recent experimental results on negative-muon-induced fission, both of 238 U and 232 Th, is given. Some conclusions drawn by the author are concerned with muonic atoms of fission fragments and muonic atoms of the shape isomer of 238 U. (author)

Measurement of the angular distribution of fission fragments using a PPAC assembly at CERN n{sub T}OF

Energy Technology Data Exchange (ETDEWEB)

Tarrío, D., E-mail: dtarriov@gmail.com [Universidade de Santiago de Compostela (Spain); Leong, L.S.; Audouin, L. [Centre National de la Recherche Scientifique/IN2P3 -Université Paris-Sud - IPN, Orsay (France); Duran, I.; Paradela, C. [Universidade de Santiago de Compostela (Spain); Tassan-Got, L.; Le Naour, C.; Bacri, C.O.; Petitbon, V.; Mottier, J. [Centre National de la Recherche Scientifique/IN2P3 -Université Paris-Sud - IPN, Orsay (France); Caamaño, M. [Universidade de Santiago de Compostela (Spain); Altstadt, S. [Johann-Wolfgang-Goethe Universität, Frankfurt (Germany); Andrzejewski, J. [Uniwersytet Łódzki, Lodz (Poland); Barbagallo, M. [Istituto Nazionale di Fisica Nucleare, Bari (Italy); Bécares, V. [Centro de Investigaciones Energeticas Medioambientales y Tecnológicas (CIEMAT), Madrid (Spain); Bečvář, F. [Charles University, Prague (Czech Republic); Belloni, F. [Commissariat à l’Énergie Atomique (CEA) Saclay - Irfu, Gif-sur-Yvette (France); Berthoumieux, E. [Commissariat à l’Énergie Atomique (CEA) Saclay - Irfu, Gif-sur-Yvette (France); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Billowes, J. [University of Manchester, Oxford Road, Manchester (United Kingdom); Boccone, V. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); and others

2014-04-11

A fission reaction chamber based on Parallel Plate Avalanche Counters (PPACs) was built for measuring angular distributions of fragments emitted in neutron-induced fission of actinides at the neutron beam available at the Neutron Time-Of-Flight (n{sub T}OF) facility at CERN. The detectors and the samples were tilted 45° with respect to the neutron beam direction to cover all the possible values of the emission angle of the fission fragments. The main features of this setup are discussed and results on the fission fragment angular distribution are provided for the {sup 232}Th(n,f) reaction around the fission threshold. The results are compared with the available data in the literature, demonstrating the good capabilities of this setup.

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)

Binary and ternary photofission of thorium 232

Energy Technology Data Exchange (ETDEWEB)

Titterton, E W; Brinkley, T A

1950-05-01

Work by Titterton and Goward (1949) has shown that uranium undergoes photofission into three charged fragments. Experiments have been conducted to determine whether a similar process takes place in the photofission of thorium. Some difficulties were encountered in loading plates with /sup 232/Th atoms, but this was finally accomplished by means of a technique described in detail. Plates loaded by this method were irradiated with a continuous spectrum of ..gamma.. rays of maximum energy 24 MeV from the (Atomic Energy Research Establishment) Synchrotron. Three irradiations, of 100, 150, and 180 r, were made and the resulting plates showed a fission density of 2.5 x 10/sup 4//cc at the 150 r level. In an examination involving 2500 binary photofissions, 5 cases of ternary fission involving the emission of a long range light fragment, probably an ..cap alpha..-particle, were observed. These events are described. A number-range curve was determined for the photofission tracks and is compared with a similar curve for tracks formed by the slow neutron fission of /sup 235/U in a D/sub 1/ emulsion under conditions of similar emulsion sensitivity. It appears that the energy release in the photofission of /sup 232/Th is smaller than that in the slow neutron fission of /sup 235/U. The data indicate that 124 MeV is the mean kinetic energy released in the photofission of /sup 232/Th.

Concentration of 232Th, 230Th and 228Th in various tissues of Japanese subjects

International Nuclear Information System (INIS)

Takizawa, Y.; Qingmei, H.; Hisamatsu, S.; Abe, T.

1997-01-01

The concentration of 232 Th, 230 Th and 228 Th in various human tissues of Japanese subjects obtained at autopsies are reported. The tissue samples were weighed, spiked with 234 Th tracer and ashed by acid. The solution was dried on a hot-plate. Separation of thorium radionuclides was accomplished through cation-exchange resin chromatography and electrodeposition. The concentrations of thorium isotopes were measured by α-spectrometry. Thorium-232 and 230 Th concentrations were found to be highest in lung, followed by bone. The maximum concentration of 228 Th was in bone. The lowest concentrations of thorium isotopes were in muscle. (author)

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

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

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

Angular distributions in the neutron-induced fission of actinides

CERN Multimedia

In 2003 the n_TOF Collaboration performed the fission cross section measurement of several actinides ($^{232}$Th, $^{233}$U, $^{234}$U, $^{237}$Np) at the n_TOF facility using an experImental setup made of Parallel Plate Avalanche Counters (PPAC). The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. We have been therefore able to cover the very broad neutron energy range 1eV-1GeV, taking full benefit of the unique characteristics of the n_TOF facility. Figure 1 shows an example obtained in the case of $^{237}$Np where the n_ TOF measurement showed that the cross section was underestimated by a large factor in the resonance region.

Experimental study of energy dependence of proton induced fission cross sections for heavy nuclei in the energy range 200-1000 MeV

Energy Technology Data Exchange (ETDEWEB)

Kotov, A.A.; Gavrikov, Yu.A.; Vaishnene, L.A.; Vovchenko, V.G.; Poliakov, V.V.; Fedorov, O.Ya.; Chestnov, Yu.A.; Shchetkovskiy, A.I [Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, Orlova roscha 1, 188300 (Russian Federation); Fukahori, T. [Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan)

2005-07-01

The results of the total fission cross sections measurements for {sup nat}Pb, {sup 209}Bi, {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu nuclei at the energy proton range 200-1000 MeV are presented. Experiments were carried out at 1 GeV synchrocyclotron of Petersburg Nuclear Physics Institute (Gatchina). The measurement method is based on the registration in coincidence of both complementary fission fragments by two gas parallel plate avalanche counters, located at a short distance and opposite sides of investigated target. The insensitivity of parallel plate avalanche counters to neutron and light charged particles allowed us to place the counters together with target immediately in the proton beam providing a large solid angle acceptance for fission fragment registration and reliable identification of fission events. The proton flux on the target to be studied was determined by direct counting of protons by scintillation telescope. The measured energy dependence of the total fission cross sections is presented. Obtained results are compared with other experimental data as well as with calculation in the frame of the cascade evaporation model. (authors)

Electrodisintegration of 232Th by neutron emission

International Nuclear Information System (INIS)

Terremoto, L.A.A.

1986-01-01

The one neutron decay of the giant electric quadrupole resonance was studied by means of electrodisintegration and photodisintegration reactions. The separation of the multipole components of the photonuclear cross section σ γ,n (E) in 232 90 Th was also performed. The 232 Th(e,n) 231 Th cross section and the 232 Th(B,n) 231 Th bremsstrahlung yield were measured in the incident electron energy range 8-60 MeV and 25-60 MeV, respectively. These measurements have been performed using the electron beam of the Linear Accelerator of the IFUSP and the experimental technique of activation analysis. The virtual photon spectra corrected for nuclear finite size in the analysis of the experimental data obtained in order to separate the multipole components of the photonuclear cross section, was used. An electric dipole component σ EL γ,n (E) that exhausts (60+-7)% of the El sum rule (integrated uσ to 16,5 MeV) was shown. This result is in agreement with the one Obtained in experiments where monoenergetic photons were used. An electric quadrupole component σ E2 γ,n (E) whose value corresponds to (32+-6)% of the E2 sum rule, was also obtained. (author) [pt

The preparation of Th-232 target by molecular plating method

International Nuclear Information System (INIS)

Yang Chunli; Wu Junde; Su Shuxin; Yang Jingling

2010-01-01

In order to measure the reaction cross-section of 232 Th(α,2n) 234 U, the preparation of uniform and adherent Th-232 targets on Al foils of thickness 2-8 μm fixed on target frame by molecular plating technique from isopropanol was described. The substrate of electrolytic cell was reconstructed and the optimum acidity for the deposition of thorium were investigated. Through deposition yield analysis, the target thickness of 100- 200μg/cm 2 was determined. The α-spectrometry for the Th-232 targets shows a good energy resolution. (authors)

232Th, a rigid rotor

International Nuclear Information System (INIS)

Singh, M.; Pradeep Kumar; Singh, Y.; Varshney, A.K.; Gupta, D.K.

2014-01-01

We undertake the present work to treat 232 Th with a soft rotor formula used recently by C. Bihari et. al for γ-band and modified by J.B. Gupta et. al. It describes energy in terms of moment of inertia and softness parameter

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

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)

230,232Th in milk, meat, and grain in Korea

International Nuclear Information System (INIS)

Lin, Xiujing; Choi, Minseok; Kim, Wan; Kang, Heedong; Doh, Sihhong; Kim, Dosung; Kim, Changkyu

2004-01-01

The concentrations of natural radioisotopes 230 Th and 232 Th in Korean foods were measured by the method of calcium oxalate co-precipitation in addition to the conventional anion-exchange method and alpha spectroscopic measurement. The 230 Th concentrations (mBq/kg-fresh) in Korean foods were found to be as follows: milk 0.14-2.45, pork 2.98-8.97, beef 1.94-9.80, chicken 1.22-13.0, rice 0.43-2.35, wheat 0.53-14.4, and soybeans, 8.44-91.6. The 232 Th concentrations (mBq/kg-fresh) in Korean foods were found to be as follows: milk 0.01-2.46, pork 0.28-9.32, beef 1.02-5.34, chicken 0.56-4.98, rice 0.32-2.54, wheat 0.53-20.0, and soybeans, 2.30-42.2. The annual internal dose of Th was also estimated. The annual internal dose of 230 Th and 232 Th in milk was about 0.006 μSv/yr and much lower than that of other countries because of the low intake of milk in Korea compared to other countries. The annual internal dose of 230 Th and 232 Th in the rice was about 0.043 μSv/yr and highest because rice is the staple food of Koreans. (author)

Estimation of throium deposited in thorotrast patients by whole body counter

International Nuclear Information System (INIS)

Tatsumi-Miyajima, Junko; Okajima, Shunzo; Takao, Hideaki; Norimura, Toshiyuki.

1986-01-01

Thorotrast, a colloidal solution of thorium dioxide was injected to wounded soldiers, for angiography from 1930 to 1945. The patients who received Thorotrast are interesting objects for finding a biological effect due to the internal irradiation by 232 Th. To determine a distribution and body burden of 232 Th, forty-one Thorotrast patients were measured their gamma-rays with a pair of NaI(T1) scintillation detectors coaxially positioned above and below the coach in the whole body counter of Nagasaki University. The comparison between the usual method using constant values and the method using individual values depend on the organ positions determined with CT (Computed Tomography) scanner for patients was performed to estimate the errors due to the individual differences in the detection efficiency of 232 Th. From the results, the estimates by the whole body counter of the amounts of 232 Th deposits in abdominal region were obtained within the uncertainties of 16 %. And the absorbed dose in the liver and the spleen was also estimated from the amounts of 232 Th. (author)

SYMMETRICAL AND ASYMMETRIC TERNARY FISSION OF HOT NUCLEI

NARCIS (Netherlands)

SIWEKWILCZYNSKA, K; WILCZYNSKI, J; LEEGTE, HKW; SIEMSSEN, RH; WILSCHUT, HW; GROTOWSKI, K; PANASIEWICZ, A; SOSIN, Z; WIELOCH, A

Emission of a particles accompanying fusion-fission processes in the Ar-40 + Th-232 reaction at E(Ar-40) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight

Asymmetrically deformed states of thorium isotopes during fission process

International Nuclear Information System (INIS)

Blons, J.

1982-05-01

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

Spatial variability of initial 230Th/ 232Th in modern Porites from the inshore region of the Great Barrier Reef

Science.gov (United States)

Clark, Tara R.; Zhao, Jian-xin; Feng, Yue-xing; Done, Terry J.; Jupiter, Stacy; Lough, Janice; Pandolfi, John M.

2012-02-01

The main limiting factor in obtaining precise and accurate uranium-series (U-series) ages of corals that lived during the last few hundred years is the ability to constrain and correct for initial thorium-230 ( 230Th 0), which is proportionally much higher in younger samples. This is becoming particularly important in palaeoecological research where accurate chronologies, based on the 230Th chronometer, are required to pinpoint changes in coral community structure and the timing of mortality events in recent time (e.g. since European settlement of northern Australia in the 1850s). In this study, thermal ionisation mass spectrometry (TIMS) U-series dating of 43 samples of known ages collected from living Porites spp. from the far northern, central and southern inshore regions of the Great Barrier Reef (GBR) was performed to spatially constrain initial 230Th/ 232Th ( 230Th/ 232Th 0) variability. In these living Porites corals, the majority of 230Th/ 232Th 0 values fell within error of the conservative bulk Earth 230Th/ 232Th atomic value of 4.3 ± 4.3 × 10 -6 (2 σ) generally assumed for 230Th 0 corrections where the primary source is terrestrially derived. However, the results of this study demonstrate that the accuracy of 230Th ages can be further improved by using locally determined 230Th/ 232Th 0 values for correction, supporting the conclusion made by Shen et al. (2008) for the Western Pacific. Despite samples being taken from regions adjacent to contrasting levels of land modification, no significant differences were found in 230Th/ 232Th 0 between regions exposed to varying levels of sediment during river runoff events. Overall, 39 of the total 43 230Th/ 232Th 0 atomic values measured in samples from inshore reefs across the entire region show a normal distribution ranging from 3.5 ± 1.1 to 8.1 ± 1.1 × 10 -6, with a weighted mean of 5.76 ± 0.34 × 10 -6 (2 σ, MSWD = 8.1). Considering the scatter of the data, the weighted mean value with a more

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)

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)

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.

Yields of fission products produced by thermal-neutron fission of 229Th

International Nuclear Information System (INIS)

Dickens, J.K.; McConnell, J.W.

1983-01-01

Absolute yields have been determined for 47 gamma rays emitted in the decay of 37 fission products representing 25 mass chains created during thermal-neutron fission of 229 Th. Using a Ge(Li) detector, spectra were obtained of gamma rays emitted between 15 min and 0.4 yr after very short irradiations by thermal neutrons of a 15-μg sample of 229 Th. On the basis of measured gamma-ray yields and known nuclear data, yields for cumulative production of 37 fission products were deduced. The absolute overall normalization uncertainty is 235 U, we postulate a simple functional dependence sigma = sigma(Z/sub p/), and using this dependence obtain values of Z/sub p/(A) for 15 mass chains created during fission of 229 Th. Values of Z/sub p/(A) were estimated for other mass chains based upon results of a recent study of Z/sub p/(A). Charge distributions determined using the deduced mass distribution and the deduced sets of Z/sub p/(A) and sigma(Z/sub p/) are in very good agreement with recent measurements, exhibiting a pronounced even-odd effect in elemental yields. These results may be used to predict unmeasured yields for 229 Th fission

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

Determination of 228Th, 230Th, and 232Th in environmental samples from uranium mining and milling operations

International Nuclear Information System (INIS)

Durham, R.W.; Joshi, S.R.

1979-01-01

A method is described for the determination of 228 Th, 230 Th, and 232 Th in environmental samples from uranium mining and milling operations. The analytical procedure is based on the direct determination of 228 Th in the sample by high resolution γ-spectrometry followed by extraction and purification of the thorium fraction using high molecular weight amines and an anion-exchange technique, respectively, prior to α-spectrometry to determine isotopic ratios. The lowest level of detection for each thorium isotope is 0.01 pCi/g for solid samples and 20 pCi/l for aqueous samples. Replicate analyses of a typical mine waste stream gave a standard deviation of +-3% for 228 Th. Standard deviations of the 230 Th and 232 Th increased to +-11% apparently due to traces of 210 Po interfering in the α-spectrometry. (author)

Measurement and analysis of thorium fission rate in a polyethylene shell with a D-T neutron source

Energy Technology Data Exchange (ETDEWEB)

Zheng, Lei [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Yang, Yiwei, E-mail: winfield1920@126.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Liu, Zhujun [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Department of Nuclear Engineering and Technology, Sichuan University, Chengdu 610065,China (China); Liu, Rong, E-mail: liurongzy@163.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Jiang, Li; Wang, Mei [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

2016-12-15

Highlights: • Associated angular dependencies of the source neutron energy and intensity was given. • Two sets of fission yields from evaluated libraries were considered and applied. • Calculated results employing ENDF/B-VII.0 agreed with the experimental ones best. • Small discrepancies exist between thorium fission cross section evaluated libraries. - Abstract: In order to validate the {sup 232}Th fission cross section, an integral experiment was carried out using the activation method in a polyethylene shell with a D-T neutron source. Thorium samples were arranged in the 0° direction to the incident D{sup +} beam. The {sup 232}Th fission rate was determined by measuring the 151.195 keV characteristic γ ray emitted from the fission fragment {sup 85m}Kr, and the experimental uncertainties were about 5.3%. MCNP calculation results employing ENDF/B-VII.0, JENDL-3.3, JENDL-4.0 libraries are in good agreement with that of experiments within uncertainties except that employing ENDF/B-VII.1 (∼6.5%). The experiment results can be used to re-evaluate the {sup 232}Th fission cross section.

Status of fission product yield data

International Nuclear Information System (INIS)

Cuninghame, J.G.

1978-01-01

The topics covered in this paper are: (a) cumulative yields in thermal neutron fission and in fast fission up to 14 MeV incident neutron energy, (b) dependence of the yields on incident neutron energy and spectrum, (c) independent yields, (d) charge dispersion and distribution, and (e) yields of light particles from ternary fission. The paper reviews information on these subjects for fission of actinides from 232 Th upwards with special emphasis on data published since the 1973 Bologna FPND Panel, compares data sets, and discusses the gaps still to be found in them. (author)

Influence of nuclear dissipation on fission dynamics of the excited ...

Indian Academy of Sciences (India)

A stochastic approach to fission dynamics based on two-dimensional Langevin equations was applied to calculate the anisotropy of the fission fragments angular distribution and average pre-scission neutron multiplicities for the compound nucleus 248Cf formed in the $${16}$O+$^{232}$Th reactions. Postsaddle nuclear ...

Recent progress in fission at saddle point and scission point

International Nuclear Information System (INIS)

Blons, J.; Paya, D.; Signarbieux, C.

High resolution measurements of 230 Th and 232 Th fission cross sections for neutrons exhibit a fine structure. Such a structure is interpreted as a superposition of two rotational bands in the third, asymmetric, well of the fission barrier. The fragment mass distribution in the thermal fission of 235 U and 233 U does not show any even-odd effect, even at the highest kinetic energies. This is the mark of a strong viscosity in the descent from saddle point to scission point [fr

Non-compound nucleus fission in actinide and pre-actinide regions

Indian Academy of Sciences (India)

Data on the evaporation residue cross-sections, in addition to those on mass and angular distributions, are necessary for better understanding of the contribution from non-compound nucleus fission in the pre-actinide region. Measurement of mass-resolved angular distribution of fission products in 20Ne+232Th reaction ...

Measurement of the 232Th-series activity in gas sockets

International Nuclear Information System (INIS)

Sutarman, I.

1995-01-01

The activity of 232 Th and its daughters in Th-based gas sockets is required for health risk assessment. By absolute measurement of the 228 Ac-and 212 Pb/ 208 Tl-activities, the total activity of the sockets can be assessed. It is governed by 228 Ra and 228 Th and the product age. (author) 1 fig.; 2 tabs

Benchmark testing calculations for 232Th

International Nuclear Information System (INIS)

Liu Ping

2003-01-01

The cross sections of 232 Th from CNDC and JENDL-3.3 were processed with NJOY97.45 code in the ACE format for the continuous-energy Monte Carlo Code MCNP4C. The K eff values and central reaction rates based on CENDL-3.0, JENDL-3.3 and ENDF/B-6.2 were calculated using MCNP4C code for benchmark assembly, and the comparisons with experimental results are given. (author)

Distribution of Th-232 and Th-228 in Santos and Sao Vicente Estuary, Sao Paulo, Brazil

Energy Technology Data Exchange (ETDEWEB)

Silva, P.S.C.; Mazzilli, B.P.; Favaro, D.I.T. [Instituto de Pesquisas Energeticas e Nucleares, Av. Lineu Prestes, 2242, Caixa Postal 05508-000, Cidade Universitaria, Sao Paulo (Brazil)]. e-mail: Pscsilva@ipen.br

2004-07-01

In the last decades considerable attention has been given to technologically enhanced natural occurring radioactive material (TENORM). Within this frame, of particular concern is the phosphate fertilizer industry. Santos Basin, located in Southwest Brazil, Sao Paulo State, comprising Santos and Sao Vicente estuarine system, is considered the most important industrial region of the country. Among the industrial activities present, phosphate fertilizer plants are responsible for the production of 69 millions tons of phosphogypsum waste, which is stockpiled in the surrounding environment. This waste concentrates radionuclides of the natural series originally present in the phosphate rock used as raw material. This study aims to evaluate the environmental impact of such activities in the sediments of the estuarine system. {sup 232} Th and {sup 228} Th concentrations in Santos and San Vicente estuary sediments were determined by Neutron activation analysis and Gamma spectrometry, respectively. {sup 232} Th concentration ranged from 6.5 to 198 Bq kg{sup -1} with mean value of 57 {+-} 39 Bq kg{sup -1}, for 42 samples. {sup 228} Th content varied from 12 to 110 Bq kg{sup -1} with a mean value of 74 {+-} 23 Bq kg{sup -1}, for 18 samples. It can be seen that the amount of {sup 232} Th is higher in the rivers close to the phosphogypsum piles, at least five points were identified as being affected by anthropogenic factor. (Author)

Distribution of Th-232 and Th-228 in Santos and Sao Vicente Estuary, Sao Paulo, Brazil

International Nuclear Information System (INIS)

Silva, P.S.C.; Mazzilli, B.P.; Favaro, D.I.T.

2004-01-01

In the last decades considerable attention has been given to technologically enhanced natural occurring radioactive material (TENORM). Within this frame, of particular concern is the phosphate fertilizer industry. Santos Basin, located in Southwest Brazil, Sao Paulo State, comprising Santos and Sao Vicente estuarine system, is considered the most important industrial region of the country. Among the industrial activities present, phosphate fertilizer plants are responsible for the production of 69 millions tons of phosphogypsum waste, which is stockpiled in the surrounding environment. This waste concentrates radionuclides of the natural series originally present in the phosphate rock used as raw material. This study aims to evaluate the environmental impact of such activities in the sediments of the estuarine system. 232 Th and 228 Th concentrations in Santos and San Vicente estuary sediments were determined by Neutron activation analysis and Gamma spectrometry, respectively. 232 Th concentration ranged from 6.5 to 198 Bq kg -1 with mean value of 57 ± 39 Bq kg -1 , for 42 samples. 228 Th content varied from 12 to 110 Bq kg -1 with a mean value of 74 ± 23 Bq kg -1 , for 18 samples. It can be seen that the amount of 232 Th is higher in the rivers close to the phosphogypsum piles, at least five points were identified as being affected by anthropogenic factor. (Author)

Fission profits of thorium: Distribution in charge and mass

International Nuclear Information System (INIS)

Guarnieri, A.A.

1985-01-01

It is presented the improvement of a semi-empiric model to describe behavior fo the 235 U + thermal neutrons system. The model is applied to fission of the 232 Th case reproducing the distribution of mass profits of fission products from the behavior of independent profits of fragments related the mass and charge, and the emission of prompt neutrons per fragment. (M.C.K.) [pt

Uranium content of petroleum by Fission track technique

International Nuclear Information System (INIS)

Paschaa, A.S.; Mafra, O.Y.; Oliveira, C.A.N.; Pinto, L.R.

1982-01-01

This paper examines the feasibility of the fission track registration technique to investigate the natural uranium concentration in petroleum. The application is briefly described and the results obtained indicate the presence of uranium concentrations in samples of Brazilian petroleum which are over the detection limit of the fission track technique. The irradiations were performed by using fluxes with predominance of thermal neutrons, which have a fission cross-section for U 235 equal to 579 barns. Since the neutron fluxes were not comp sed exclusively of thermal neutrons, fissions from fast neutrons would also be taken into account for U 238 and Th 232

Probing the time scale of asymmetric fission

International Nuclear Information System (INIS)

Kamanin, D.

1999-12-01

The author describes the measurement of the mass-energy distributions of fission fragments in the reactions 197 Au( 14 N,X) at 34 A.MeV and 232 Th( 7 Li,X) at 43 A.MeV. He presents results on the mass-asymmetry and excitation energy sharing. (HSI)

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

Impulse transfer and light particles emission during the reaction α + 232Th at 70 MeV/u

International Nuclear Information System (INIS)

Nguyen, M.S.

1988-02-01

We have measured during the reaction 4 He + 232 Th at 70 MeV/u the angular correlation of heavy fragments of fission, the inclusive energy spectra of light particles (p, d, t, 3 He and α) and triple coincidence between two fission fragments and a light ejectile. Energy spectra show an evaporation component at low energy, a component of projectile fragmentation at energy equivalent to beam velocity and an intermediate component attributed to pre-equilibrium emission. The analysis of the correlation between linear momentum transfer to the fissioning nucleus and the characteristics of the ejectile in coincidence shows a phenomenon of incomplete massive transfer. We run an Intra-Nuclear Cascade (INC) computation to reproduce ejectile energy spectra, but the agreement with experiment was very bad. We conclude to the impossibility to apply INC computation at intermediate energy of 70 MeV/u. We also applied Distorted Wave Born Approximation (DWBA) for direct transfer reaction extended to continuum states: but the agreement with experiment was again deceiving. Finally, we used an analysis by moving sources for which we propose a model of generalized fragmentation giving a continuous representation of the emission source phenomenon from low energy up to high energy [fr

The status of fission product yield data (FPND) in 1977

International Nuclear Information System (INIS)

Cuninghame, J.G.

1977-05-01

The topics covered is this paper are:- (a) cumulative yields in thermal neutron fission and in fast fission up to 14 MeV incident neutron energy; (b) dependence of the yields on incident neutron energy and spectrum; (c) independent yields; (d) charge dispersion and distribution, and (e) yields of light particles from ternary fission. The paper reviews information on these subjects for fission of actinides from 232 Th upwards, with special emphasis on data published since the 1973 Bologna FPND Panel, compares data sets and discusses the gaps still to be found in them. (author)

Measurement of {sup 232}Th(n, 5nγ) cross sections from 29 MeV to 42 MeV

Energy Technology Data Exchange (ETDEWEB)

Kerveno, M.; Baumann, P.; Dessagne, P.; Rudolf, G. [Universite de Strasbourg, IPHC, Strasbourg (France); CNRS, UMR7178, Strasbourg (France); Nolte, R.; Reginatto, M. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Jericha, E. [Technische Universitaet Wien, Atominstitut, Wien (Austria); Jokic, S.; Lukic, S. [Vinca Institute of Nuclear Sciences, Belgrade (Serbia); Koning, A.J. [Nuclear Research and Consultancy Group, Petten (Netherlands); Meulders, J.P. [Institut de Physique Nucleaire, Louvain-la-Neuve (Belgium); Nachab, A. [Universite Cadi Ayyad, Departement de physique, Faculte Poly-disciplinaire de Safi, Safi (Morocco); Pavlik, A. [Faculty of Physics, University of Vienna, Wien (Austria)

2014-10-15

The excitation function of the reaction {sup 232} Th(n, 5nγ){sup 228} Th from 29 to 42 MeV has been measured for the first time at the quasi-monoenergetic neutron beam of the UCL cyclotron CYCLONE employing the {sup 7}Li(p,n) source reaction. Taking advantage of the good energy resolution of the planar High-Purity Germanium (HPGe) detectors, prompt γ-ray spectroscopy was used to detect the γ-rays resulting from the decay of excited states of nuclei created by the (n,xn) reactions. The neutron beam was characterized by a combination of time of flight measurements carried out using a liquid scintillation detector and a {sup 238}U fission ionization chamber. Fluence measurements were performed using a proton recoil telescope. The results are compared with TALYS-1.4 code calculations. (orig.)

Gamma-ray multiplicities in sub-barrier fission of 226Th

International Nuclear Information System (INIS)

Chubaryan, G.G.; Hurst, B.J.; O'Kelly, D.J.

1998-01-01

The γ rays from the multimodal fission of the 226 Th formed in 18 O + 208 Pb were investigated at the sub-barrier energies. The corresponding excitation energies at the saddle point, E sp * , ranged from 16.4 to 19.2 MeV. The average γ-ray multiplicities and relative γ-ray energies as a function of the mass of the fission fragments exhibit a complex structure and strong variations. Such strong variations have never been previously observed in heavy ion-induced fusion-fission reactions. Obtained results may be explained with the influence of shell effects on the properties of the fission fragments. The present work is one in series of investigations of the multimodal fission phenomena in At-Th region

Fast fission assisted ignition of thermonuclear microexplosions

International Nuclear Information System (INIS)

Winterberg, F.

2006-01-01

It is shown that the requirements for fast ignition of thermonuclear microexplosions can be substantially relaxed if the deuterium-tritium (DT) hot spot is placed inside a shell of U-238 (Th-232). An intense laser - or particle beam-projected into the shell leads to a large temperature gradient between the hot DT and the cold U-238 (Th-232), driving thermomagnetic currents by the Nernst effect, with magnetic fields large enough to entrap within the hot spot the α-particles of the DT fusion reaction. The fast fission reactions in the U-238 (Th-232) shell implode about 1/2 of the shell onto the DT, increasing its density and reaction rate. With the magnetic field generated by the Nernst effect, there is no need to connect the target to a large current carrying transmission line, as it is required for magnetized target fusion, solving the so-called ''stand off'' problem for thermonuclear microexplosions. (orig.)

Contribution to the study of the influences of the excitation energy on the characteristics of the fission process

International Nuclear Information System (INIS)

Wagemans, C.

1979-01-01

Neutron induced and spontaneous fission with neutron energies from 10 -2 to 2.10 5 eV have been studied. Thermal neutron induced fission measurements in Pa 231 , Th 232 , Np 237 , U 233 , U 235 , Pu 239 and Pu 241 are reported. Energy and mass distributions of heavy fission fragments due to the spontaneous fission of Pu 240 are compared to the results obtained by thermal neutron fission of Pu 239 ; the events observed with U 236 , Pu 240 , Pa 232 and Np 238 are explained by the Bohr theory of fission channels. Ternary fission phenomena of U 233 , U 235 , Pu 239 , Pa 231 and Np 237 induced by thermal neutrons are explained and compared to models of Carjan and Feather. (MDC)

Studies on 232Th and 238U levels in marine algae collected from the coast of Niigata Prefecture

International Nuclear Information System (INIS)

Kato, Kenji; Tonouchi, Shigemasa; Maruta, Fumiyuki; Ebata, Hidekazu

2001-01-01

To evaluate the properties of algae to concentrate radioactive elements, 14 species of algae like Sargassum were collected in the Prefecture and analyzed for their 232 Th and 238 U levels with Yokogawa HP4500 ICP-MS apparatus. The places of collection included those near the water discharge of an atomic power station. Mean 232 Th and 238 U levels were found to be 120 and 260 ng/g dry wt, respectively, and Phaeophyta showed more than several times higher 238 U level than Chlorophyta and Rhodophyta. There was no clear difference in 232 Th levels. No difference between places of collection was observed in Sargassum 232 Th or 238 U level. Adsorption of 232 Th particle to and incorporation of soluble 238 U into algae body were suggested. Mean 232 Th and 238 U radioactivities were found 73 and 510 μBq/g wet wt, respectively, and the respective annual committed effective doses, 0.2 and 0.3 μSv, calculated from those values were confirmed to be enough lower than the annual public dose limit, 1 mSv. (K.H.)

Fission properties of actinide nuclei from proton-induced fission at 26.5 and 62.9 MeV incident proton energies

International Nuclear Information System (INIS)

Demetriou, P.; Keutgen, Th.; Prieels, R.; El Masri, Y.

2010-01-01

Fission properties of proton-induced fission on 232 Th, 237 Np, 238 U, 239 Pu, and 241 Am targets, measured at the Louvain-la-Neuve cyclotron facility at proton energies of 26.5 and 62.9 MeV, are compared with the predictions of the state-of-the-art nuclear reaction code talys. The code couples the multimodal random neck-rupture model with the pre-equilibrium exciton and statistical models to predict fission fragment mass yields, pre- and post-scission neutron multiplicities, and total fission cross sections in a consistent approach. The sensitivity of the calculations to the input parameters of the code and possible improvements are discussed in detail.

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.

Disentangling effects of breakup coupling and incomplete fusion in 6Li + 232Th reaction

International Nuclear Information System (INIS)

Jha, V.; Parkar, V.V.; Mohanty, A.K.; Kailas, S.

2014-01-01

A component of fusion that is very important but quite difficult to evaluate is the incomplete fusion (ICF), in which only a part of the nucleus fuses with the target. ICF occurs together with the usual complete fusion (CF), in which the whole projectile fuses or all the projectile fragments after breakup fuse with the target nucleus. The ICF leads to the flux removal from the fusion channel and its calculation is essential for a comprehensive description of the fusion process. In the present work, a recently developed method of calculating the ICF cross-section (σ ICF ) is used in a novel way to disentangle the ICF effect on the fusion process from those due to breakup couplings. The total fusion cross-section σ TF and σ ICF for the 6 Li + 232 Th system are calculated at energies above and below the Coulomb barrier, where the measured fusion-fission data is available

Analysing of 228Th, 232Th, 228Ra in human bone tissues for the purpose of determining the post mortal interval

International Nuclear Information System (INIS)

Kandlbinder, R.; Geissler, V.; Schupfner, R.; Wolfbeis, O.; Zinka, B.

2009-01-01

Bone tissues of thirteen deceased persons were analyzed to determine the activity concentration of the radionuclides 228 Ra, 228 Th, 232 Th and 2 30 Th. The activity ratios enable to assess the post-mortem-interval PMI). The samples were prepared for analysis by incinerating and pulverizing. 228 Ra was directly detected by γ-spectrometry. 2 28 Th, 230 Th, 232 Th were detected by α-spectrometry after radiochemical purification and electrodeposition. It is shown that the method s principally suited to determine the PMI. A minimum of 300 g (wet weight) f human bone tissue is required for the analysis. Counting times are in the range of one to two weeks. (author)

Binary scission configurations in fission of light actinides

Energy Technology Data Exchange (ETDEWEB)

Ohtsuki, Tsutomu [Tohoku Univ., Sendai (Japan). Lab. of Nuclear Science; Nagame, Y.; Nishinaka, I.; Tsukada, K.; Ikezoe, H.; Tanikawa, M.; Zhao, Y.L.; Sueki, K.; Nakahara, H.

1997-07-01

Mass and kinetic energy distributions of fission fragments have been accurately measured by a double velocity time-of-flight technique in the 13 MeV proton-induced fissions of {sup 232}Th and {sup 238}U. A binary structure is observed in total kinetic energy distributions in the fragments with mass number around A=130 for both the fissions, indicating that there are at least two kinds of scission configurations. A correlation between the scission configurations and mass yield distributions reveals that elongated scission configurations are associated with the symmetric mass distribution and compact scission configurations with the asymmetric mass distribution. (author)

238U, 234U and 232Th in seawater

International Nuclear Information System (INIS)

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

1986-01-01

We have developed techniques to determine 238 U, 234 U and 232 Th concentrations in seawater by isotope dilution mass spectrometry. Using these techniques, we have measured 238 U, 234 U and 232 Th in vertical profiles of unfiltered, acidified seawater from the Atlantic and 238 U and 234 U in vertical profiles from the Pacific. Determinations of 234 U/ 238 U at depths ranging from 0 to 4900 m in the Atlantic (7 0 44'N, 40 0 43'W) and the Pacific (14 0 41'N, 160 0 01'W) Oceans are the same within experimental error (±5per mille, 2σ). The average of these 234 U/ 238 U measurements is 144±2per mille (2σ) higher than the equilibrium ratio of 5.472 x 10 -5 . U concentrations, normalized to 35per mille salinity, range from 3.162 to 3.281 ng/g, a range of 3.8%. The average concentration of the Pacific samples (31 0 4'N, 159 0 1'W) is ∝1% higher than that of the Atlantic (7 0 44'N, 40 0 43'W and 31 0 49'N, 64 0 6'W). 232 Th concentrations from an Atlantic profile range from 0.092 to 0.145 pg/g. The observed constancy of the 234 U/ 238 U ratio is consistent with the predicted range of 234 U/ 238 U using a simple two-box model and the residence time of deep water in the ocean determined from 14 C. The variation in salinity-normalized U concentrations suggests that U may be much more reactive in the marine environment than previously thought. (orig./WB)

Levels of 232Th activity in the South Adriatic Sea marine environment of Montenegro

International Nuclear Information System (INIS)

Antovic, N.M.

2010-01-01

232 Th activities in the South Adriatic Sea-water, surface sediment, mud with detritus, seagrass (Posidonia oceanica) samples, and the mullet (Mugilidae) species Mugil cephalus, as well as soil and sand from the Montenegrin Coast, were measured using the six-crystal spectrometer PRIPYAT-2M, which has relatively high detection efficiency and a good sensitivity, and allows a short acquisition time, and measuring samples of any shape, without preliminary preparation and calibration measurements for different sample geometries. An average 232 Th activity concentration in surface soil layer is found to be 40.33 Bq kg -1 , while in sand-4.7 Bq kg -1 . The absorbed dose rate in air due to 232 Th gamma radiation from surface soil layer ranged from 11.76 to 63.39 nGy h -1 , with a mean of 24.06 nGy h -1 . Corresponding average annual effective dose rate has been found to be 0.03 mSv y -1 . The absorbed dose rates due to the thorium gamma radiation in air at 1 m above sand surface on the Montenegrin beaches have been found to be from 0.41 to 9.08 nGy h -1 , while annual effective dose rates ranged from 0.0005 to 0.011 mSv y -1 . 232 Th activity concentration in seawater ranged from 0.06 to 0.22 Bq L -1 , as in the mullet (Mugil cephalus) whole individuals from 0.63 to 1.67 Bq kg -1 . Annual intake of 232 Th by human consumers of this fish species has been estimated to provide an effective dose of about 0.003 mSv y -1 . (author)

Identifying resuspended sediment in an estuary using the 228Th/232Th activity ratio: the fate of lagoon sediment in the Bega River estuary, Australia

International Nuclear Information System (INIS)

Hancock, G.J.

2000-01-01

Thorium-series nuclides ( 228 Th and 232 Th) have been used to identify resuspended sediment in the Bega River estuary, south-eastern Australia. A non-conservative increase in concentration of suspended sediment of water in the vicinity of mid-estuary back-flow lagoons was associated with a decrease in the 228 Th/ 232 Th activity ratio (AR) of the suspended sediment. The lagoon sediment is characterized by a low estuarine 228 Th/ 232 Th signature, distinguishing it from freshwater suspended sediment recently delivered to the estuary, and identifying it as the likely source of the additional suspended sediment. Sediment-core 210 TPb profiles show that the lagoons are accumulating sediment, presumably during high river-flow events. However this study indicates that during intervening periods of low flow, 40% of sediment deposited in the lagoons is subsequently resuspended and exported to the lower estuary, and possibly to the ocean. The utility of the 228 Th/ 232 Th AR to quantify sediment resuspension in estuaries is likely to be estuary-dependent, and is controlled by the extent of scavenging of dissolved 228 Th by suspended particles. Copyright (2000) CSIRO Publishing

Laboratory Bioaccumulation, Depuration And Total Dose Rate Of Waterborne Th-232 In Freshwater Fish Of Anabas Testudineus

International Nuclear Information System (INIS)

Zal U'yun Wan Mahmood; Norfaizal Mohamed; Nita Salina Abu Bakar

2014-01-01

Preliminary results on the study of bioaccumulation, depuration and total dose rate of Th-232 in the whole body of Anabas testudineus are presented. The objective of this study was to evaluate the effect of Th-232 concentration activity on the laboratory bioaccumulation, depuration and total dose rate in Anabas testudineus. Anabas testudineus adults were exposed to different waterborne Th-232 levels: 0 BqL -1 (control), 50 BqL -1 and 100 BqL -1 for 30 day (uptake phase), followed by exposure to radionuclide-free water for 30 days (loss phase). Radionuclide concentration ratios between the whole body levels and water levels, percentage of Th-232 remaining in fish were calculated and total dose rates using ERICA Assessment Tool were also estimated. The results showed the increase of waterborne Th-232 concentration corresponded to a progressive increase of Th accumulation and total dose rate (internal and external) in the whole body of Anabas testudineus. Considering the ERICA dose rate screening value of 10 μGyh -1 , the findings can be concluded the estimated of total dose rate (< 5 μGyh -1 ) in Anabas testudineus is in order of small magnitude. Nevertheless, these preliminary results showed that the Anabas testudineus has a potential to accumulate thorium. (author)

Features of the neutron spectra accompanying the fission of actinide nuclei

International Nuclear Information System (INIS)

Lovchikova, G.N.; Trufanov, A.M.; Svirin, M.I.; Polyakov, A.V.; Vinogradov, V.A.; Dmitriev, V.D.; Boykov, G.S.

2000-01-01

The spectra of fission neutrons from 238 U are measured by the time-of-flight technique at incident-neutron energies E n = 5.0 and 13.2 MeV. The data are compared with those obtained in the previous studies for 232 Th, 235,238 U, 237 Np at E n = 2.9 and 14.7 MeV; for 232 Th at E n = 14.6 and 17.7 MeV; for 238 U at 16.0 and 17.7 MeV. An excess of soft neutrons, which is observed in comparing experimental spectra for E n 13.2, 14.7, 16.0 and 17.7 MeV with the results of traditional theoretical calculations, is reproduced fairly well under the assumption that, at high excitation energies of a compound system, some part of post-fission neutrons can be emitted by nonaccelerated fragments [ru

Investigation of the 232Th neutron cross-sections in resonance energy range

International Nuclear Information System (INIS)

Grigoriev, Yu.V.; Kitaev, V.Ya.; Sinitsa, V.V.; Zhuravlev, B.V.; Borzakov, S.B.; Faikov-Stanchik, H.; Ilchev, G.L.; Panteleev, Ts.Ts.; Kim, G.N.

2001-01-01

The alternative path in the development of atomic energy is the uranium-thorium cycle. In connection with this, the measurements of the 232 Th neutron capture and total cross-sections and its resonance self-shielding coefficients in resonance energy range are necessary because of their low accuracy. In this work, the results of the investigations of the thorium-232 neutron cross-sections are presented. The measurements have been carried out on the gamma-ray multisection liquid detector and neutron detector as a battery of boron counters on the 120 m flight path of the pulsed fast reactor IBR-30. As the filter samples were used the metallic disks of various thickness and diameter of 45 mm. Two plates from metallic thorium with thickness of 0.2 mm and with the square of 4.5x4.5 cm 2 were used as the radiator samples. The group neutron total and capture cross-sections within the accuracy of 2-7% in the energy range of (10 eV-10 keV) were obtained from the transmissions and the sum spectra of g-rays from the fourth multiplicity to the seventh one. The neutron capture group cross-sections of 238 U were used as the standard for obtaining of thorium ones. Analogous values were calculated on the GRUCON code with the ENDF/B-6, JENDL-3 evaluated data libraries. Within the limits of experimental errors an agreement between the experiment and calculation is observed, but in some groups the experimental values are larger than the calculated ones. (author)

Production and release of the fission gas in (Th U)O2 fuel rods

International Nuclear Information System (INIS)

Dias, Marcio S.

1982-06-01

The volume, composition and release of the fission gas products were caculated for (Th, U)O 2 fuel rods. The theorectical calculations were compared with experimental results available on the literature. In ThO 2 + 5% UO 2 fuel rods it will be produced approximated 5% more fission gas as compared to UO 2 fuel rods. The fission gas composition or Xe to Kr ratio has showed a decreasing fuel brunup dependence, in opposition to that of UO 2 . Under the same fuel rod operational conditions, the (Th, U)O 2 fission gas release will be smaller as compared to UO 2 . This behaviour of (Th, U)O 2 fuel comes from smallest gas atom difusivity and higher activation energies of the processes that increase the fission gas release. (Author) [pt

Determination of 228Th, 232Th, and228Ra in wild mushroom from a naturally high radioactive region in Brazil

International Nuclear Information System (INIS)

Rosa, Mychelle M.L.; Taddei, Maria Helena T.; Silva, Marco A.; Ferreira, Marcelo T.

2011-01-01

Mushrooms are fungi which efficiently accumulate radionuclides, as verified by radiochemistry analyses of specimens collected in contaminated areas, specifically after the Chernobyl nuclear accident. Many studies have demonstrated that mushrooms can be used in monitoring of ecosystem contamination and quality. The present paper is part of a broader study conducted in the Pocos de Caldas plateau region in Minas Gerais, Brazil, investigating assimilation of natural Uranium and Thorium radionuclide series by mushrooms. This region has elevated natural radioactivity due to the presence of radiological anomalies of volcanic origin. These anomalies are ore bodies containing Uranium and Thorium, the later being highly predominant. Many researchers have been conducted concerning radionuclide incorporation by agricultural products on the plateau. The present paper aims to determine 232 Th, 228 Th, and 228 Ra radionuclides in wild mushrooms collected at different locations in the plateau region. 228 Ra was determined by radiochemical separation using sulphate coprecipitation followed by beta radiometry. 232 Th and 228 Th were determined using anion exchange resin purification followed by alpha spectrometry. Higher values were obtained to 228 Th than to 232 Th. This is due to higher 228 Ra mobility, which decays to 228 Th. The accuracy of the analytical methods employed was evaluated using the reference sample IAEA Soil 327. These methods had high chemical recovery and high sensitivity. It was possible to confirm that mushrooms accumulate radionuclide and so can be used in environmental contamination and quality assessment. (author)

Studies on {sup 232}Th and {sup 238}U levels in marine algae collected from the coast of Niigata Prefecture

Energy Technology Data Exchange (ETDEWEB)

Kato, Kenji; Tonouchi, Shigemasa; Maruta, Fumiyuki; Ebata, Hidekazu [Niigata Prefectural Inst. of Public Health and Environmental Sciences (Japan)

2001-12-01

To evaluate the properties of algae to concentrate radioactive elements, 14 species of algae like Sargassum were collected in the Prefecture and analyzed for their {sup 232}Th and {sup 238}U levels with Yokogawa HP4500 ICP-MS apparatus. The places of collection included those near the water discharge of an atomic power station. Mean {sup 232}Th and {sup 238}U levels were found to be 120 and 260 ng/g dry wt, respectively, and Phaeophyta showed more than several times higher {sup 238}U level than Chlorophyta and Rhodophyta. There was no clear difference in {sup 232}Th levels. No difference between places of collection was observed in Sargassum {sup 232}Th or {sup 238}U level. Adsorption of {sup 232}Th particle to and incorporation of soluble {sup 238}U into algae body were suggested. Mean {sup 232}Th and {sup 238}U radioactivities were found 73 and 510 {mu}Bq/g wet wt, respectively, and the respective annual committed effective doses, 0.2 and 0.3 {mu}Sv, calculated from those values were confirmed to be enough lower than the annual public dose limit, 1 mSv. (K.H.)

Development of a position-sensitive fission counter and measurement of neutron flux distributions

International Nuclear Information System (INIS)

Yamagishi, Hideshi; Soyama, Kazuhiko; Kakuta, Tsunemi

2001-08-01

A position-sensitive fission counter (PSFC) that operates in high neutron flux and high gamma-ray background such as at the side of a power reactor vessel has been developed. Neutron detection using the PSFC with a solenoid electrode is based on a delay-line method. The PSFC that has the outer diameter of 25 mm and the sensitive length of 1000 mm was manufactured for investigation of the performances. The PSFC provided output current pulses that were sufficiently higher than the alpha noise, though the PSFC has a solenoid electrode and large electrode-capacitance. The S/N ratio of PSFC outputs proved to be higher than that of ordinary fission counters with 200 mm sensitive length. A performance test to measure neutron flux distributions by a neutron measuring system with the PSFC was carried out by the side of a graphite pile, W2.4 x H1.4 x L1.2 m, with neutron sources, Am-Be 370 GBq x 2. It was confirmed that the neutron flux distribution was well measured with the system. (author)

Mobility of 232Th and 210Po in red mud.

Science.gov (United States)

Hegedűs, Miklós; Tóth-Bodrogi, Edit; Jónás, Jácint; Somlai, János; Kovács, Tibor

2018-04-01

The valorization of industrial by-products such as red mud became a tempting opportunity, but the understanding of the risks involved is required for the safe utilization of these products. One of the risks involved are the elevated levels of radionuclides (in the 100-1300 Bq/kg range for both the 238 U and 232  Th decay chains, but usually lower than 1000 Bq/kg, which is the recommended limit for excemption or clearance according to the EU BSS released in 2013) in red mud that can affect human health. There is no satisfactory answer for the utilization of red mud; the main current solution is still almost exclusively disposal into a landfill. For the safe utilization and deposition of red mud, it is important to be able to assess the leaching behaviour of radionuclides. Because there is no commonly accepted measurement protocol for testing the leaching of radionuclides in the EU a combined measurement protocol was made and tested based on heavy metal leaching methods. The leaching features of red mud were studied by methods compliant with the MSZ-21470-50 Hungarian standard, the CEN/TS 14429 standard and the Tessier sequential extraction method for 232 Th and 210 Po. The leached solutions were taken to radiochemical separation followed by spontaneous deposition for Po and electrodeposition for Th. The 332 ± 33 Bq/kg 232 Th content was minimally mobile, 1% became available for distilled water 1% and 6% for Lakanen-Erviö solution; the Tessier extraction showed minimal mobility in the first four steps, while more than 85% remained in the residue. The 210 Po measurements had a severe disturbing effect in many cases, probably due to large amounts of iron present in the red mud, from the 310 ± 12 Bq/kg by aqua regia digestion, distilled water mobilized 23%, while Lakanen-Erviö solution mobilized ∼13%. The proposed protocol is suitable for the analysis of Th and Po leaching behaviour. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of daily intake of 238U and 232Th in a Korean mixed diet sample using RNAA

International Nuclear Information System (INIS)

Chung, Yong Sam; Moon, Jong Hwa; Kim, Sun Ha; Park, Kwang Won; Kang, Sang Hoon; Cho, Seung Yeon

2000-01-01

To estimate the degree of intake of 238 U and 232 Th through daily diet, a Korean mixed diet sample was prepared after the investigation of the amount of consumption of the daily diet which corresponds to the age of 20 to 60 years. For the analysis of U and Th, the RNAA method was applied. Two standard reference materials were used for quality control and assurance and the analytical results were compared with a certified value. The determination of U and Th in the Korean mixed diet sample was carried out under the same analytical conditions and procedures with SRM. It is found that the concentration of U and Th in a Korean mixed diet was about 35.4 ppb and 3.4 ppb. From these results, the daily intake of 238 U and 232 Th by diet is evaluated to be 6.98 and 0.67 μg per day, respectively. Radioactivities related to the intake of 238 U and 232 Th were estimated to be about 86 mBq per person per day and the annual dose equivalents from 238 U and 232 Th revealed as 3.18 μSv and 0.29 μSv per person, respectively

Evaluation of cross sections of Th-232 and U-233

International Nuclear Information System (INIS)

Dias, A.M.

1978-01-01

The cross sections in multigroups of Th-232 and U-233 are evaluated by comparison of theoretical results and experimental data obtained through experiments on the fast reactors IBR-I, EBR-II, BR-I and AETR. The deviation between calculated values and experimental results is about 10%. They are therefore satisfatory for neutronic calculations [pt

Contamination level of natural 238U and 232Th radionuclides in offshore of coal power plant (assessment at offshore of Panjang Island and Lada Bay, Banten)

International Nuclear Information System (INIS)

Sabam Parsaoran Situmorang; Harpasis Selamet Sanusi; June Mellawati

2011-01-01

This study had been carried out by collecting sample of the surficial sediments, sea water, seaweeds, anchovies (Stolephorus and Anchoa) and mussels (Codakia) from 4 locations in waters of Pulau Panjang and coastal of Lada Bay (as control/comparison site), Banten in June - July 2010. Natural radionuclides (Th) concentration in samples was measured using neutron activation analysis (NAA) method. The results showed that the total radionuclides concentration in sediment ( 238 U: 18.6160 - 35.0013 Bq/kg; 232 Th: 11.2020 - 35.6685 Bq/kg), seawater ( 238 U: undetected; 232 Th: 0.0790 - 0.1299 Bq/l), cultivation seaweeds ( 238 U: undetected; 232 Th: 3.6735 - 4.8345 Bq/kg), natural seaweeds ( 238 U: 3.6851 - 48.0430 Bq/kg; 232 Th: 3.9941 - 9.0788 Bq/kg), Stolephorus ( 238 U: undetected; 232 Th: 3.3078 Bq/kg) and Codakia ( 238 U: 6.8903 Bq/kg; 232 Th: 3.6023 Bq/kg) in Pulau Panjang, Banten around Suralaya coal power plant higher than control site that were around the Labuan coal power plant, namely in sediments ( 238 U: 10.4253 Bq/kg; 232 Th: 16.5952 Bq/kg), seawater( 238 U: undetected; 232 Th: 0.0671 Bq/l), cultivation seaweeds ( 238 U: undetected; 232 Th: 2.3005 Bq/kg), natural seaweeds ( 238 U: 19.5367 Bq/kg; 232 Th: 2.6729 Bq/kg) and Anchoa ( 238 U: undetected; 232 Th: 2.0603 Bq/kg). (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

Photon and proton induced fission on heavy nuclei at intermediate energies

Directory of Open Access Journals (Sweden)

Andrade-II E.

2014-04-01

Full Text Available We present an analysis of fission induced by intermediate energy protons or photons on actinides. The 660 MeV proton induced reactions are on 241Am, 238U, and 237Np targets and the Bremmstrahlung-photons with end-point energies at 50 MeV and 3500 MeV are on 232Th and 238U targets. The study was performed by means of the Monte Carlo simulation code CRISP. A multimodal fission extension was added to the code within an approach which accounts for the contribution of symmetric and asymmetric fission. This procedure allowed the investigation of fission cross sections, fissility, number of evaporated nucleons and fission-fragment charge distributions. The comparison with experimental data show a good agreement between calculations and experiments.

Investigation of the heavy nuclei fission with anomalously high values of the fission fragments total kinetic energy

Science.gov (United States)

Khryachkov, Vitaly; Goverdovskii, Andrei; Ketlerov, Vladimir; Mitrofanov, Vecheslav; Sergachev, Alexei

2018-03-01

Binary fission of 232Th and 238U induced by fast neutrons were under intent investigation in the IPPE during recent years. These measurements were performed with a twin ionization chamber with Frisch grids. Signals from the detector were digitized for further processing with a specially developed software. It results in information of kinetic energies, masses, directions and Bragg curves of registered fission fragments. Total statistics of a few million fission events were collected during each experiment. It was discovered that for several combinations of fission fragment masses their total kinetic energy was very close to total free energy of the fissioning system. The probability of such fission events for the fast neutron induced fission was found to be much higher than for spontaneous fission of 252Cf and thermal neutron induced fission of 235U. For experiments with 238U target the energy of incident neutrons were 5 MeV and 6.5 MeV. Close analysis of dependence of fission fragment distribution on compound nucleus excitation energy gave us some explanation of the phenomenon. It could be a process in highly excited compound nucleus which leads the fissioning system from the scission point into the fusion valley with high probability.

The fission time scale measured with an atomic clock

NARCIS (Netherlands)

Kravchuk, VL; Wilschut, HW; Hunyadi, M; Kopecky, S; Lohner, H; Rogachevskiy, A; Siemssen, RH; Krasznahorkay, A; Hamilton, JH; Ramayya, AV; Carter, HK

2003-01-01

We present a new direct method of measuring the fission absolute time scale using an atomic clock based on the lifetime of a vacancy in the atomic K-shell. We studied the reaction Ne-20 + Th-232 -> O-16 + U-236* at 30 MeV/u. The excitation energy of about 115 MeV in such a reaction is in the range

Bimodal nature in low-energy fission of light actinides

International Nuclear Information System (INIS)

Nagame, Yuichiro; Nishinaka, Ichiro; Tsukada, Kazuaki; Ikezoe, Hiroshi; Otsuki, Tsutomu; Sueki, Keisuke; Nakahara, Hiromichi; Kudo, Hisaaki.

1995-01-01

To solve various problems in the mass division process of light actinoids, some experiments on the basis of bimodal fission were carried. Mass and kinetic energy distribution of Th-232 and U-238 were determined. Pa-225 (N= 134) and Pa-227 (N=136), fission nuclei, were produced by Bi-209 + 0-16 and Bi-209 + 0-18 heavy ion nucleus reactions, and the mass yield distribution were determined by the time-of-flight method and the radiochemical procedure. From the results, two independent deforming processes were proved in the fission process of light actinoid nuclei. On the deforming process through the low fission barrier, nucleus fissioned after small deformation under the influence of stabilization of the shell structure of fission product. In the case of process through the high barrier, however, the nucleus fissioned after large deformation. The unsymmetrical mass division was derived from the former and the symmetrical one from the latter. (S.Y.)

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Systematics of fission cross sections at the intermediate energy region

Energy Technology Data Exchange (ETDEWEB)

Fukahori, Tokio; Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-03-01

The systematics was obtained with fitting experimental data for proton induced fission cross sections of Ag, {sup 181}Ta, {sup 197}Au, {sup 206,207,208}Pb, {sup 209}Bi, {sup 232}Th, {sup 233,235,238}U, {sup 237}Np and {sup 239}Pu above 20 MeV. The low energy cross section of actinoid nuclei is omitted from systematics study, since the cross section has a complicated shape and strongly depends on characteristic of nucleus. The fission cross sections calculated by the systematics are in good agreement with experimental data. (author)

Fission fragment spins and spectroscopy

International Nuclear Information System (INIS)

Durell, J.L.

1988-01-01

Prompt γ-ray coincidence experiments have been carried out on γ-rays emitted from post-neutron emission fission fragments produced by the aup 19F + 197 Au and 18 O + 232 Th reactions. Decay schemes have been established for even-even nuclei ranging from 78 Se to 148 Nd. Many new states with spin up to ∼ 12h have been observed. Apart from providing a wealth of new information on the spectroscopy of neutron-rich nuclei, the data have been analyzed to determine the average spin of primary fission fragments as a function of fragment mass. The results suggest that the fragment spins are determined by the temperature and shape of the primary fragments at or near to scission

Investigate the capability of INAA absolute method to determine the concentrations of 238U and 232Th in rock samples

International Nuclear Information System (INIS)

Alnour, I.A.

2014-01-01

This work aimed to study the capability of INAA absolute method in determining the elemental concentration of 238 U and 232 Th in the rock samples. The INAA absolute method was implemented in PUSPATI TRIGA Mark II research reactor, Malaysian Nuclear Agency (NM). The accuracy of INAA absolute method was performed by analyzing the IAEA certified reference material (CRM) Soil-7. The analytical results showed the deviations between experimental and certified values were mostly less than 10 % with Z-score in most cases less than 1. In general, the results of analysed CRM Soil-7 show a good agreement between certified and experimental results which mean that the INAA absolute method can be used accurately for elemental analysis of uranium and thorium in various types of samples. The concentration of 238 U and 232 Th ranged from 1.77 to 24.25 and 0.88 to 95.50 ppm respectively. The highest value of 238 U and 232 Th was recorded for granite rock sample G17 of 238 U and sample G9 of 232 Th, whereas the lower value was 1.77 ppm of 238 U recorded in sandstone rock and 0.88 ppm of 232 Th for gabbro. Moreover, a comparison of the 238 U and 232 Th results obtained by the INAA absolute method shows an acceptable level of consistency with those obtained by the INAA relative method. (author)

Fission-energy release for 16 fissioning nuclides. Final report

International Nuclear Information System (INIS)

Sher, R.

1981-03-01

Results are presented of a least-squares evaluation of the components of energy release per fission in 232 Th, 233 U, 235 U, 238 U, 239 Pu, and 241 Pu. For completeness, older (1978) results based on systematics are presented for these and ten other isotopes of interest. There have been recent indications that the delayed energy components may be somewhat higher than those used previously, but the LSQ results do not seem to change significantly when modest (approx. 1 MeV) increases in the total delayed energy are included in the inputs. Additional measurements of most of the energy components are still needed to resolve remaining discrepancies

(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.

Photon and proton induced fission on heavy nuclei at intermediate energies

Energy Technology Data Exchange (ETDEWEB)

Andrade-II, E.; Karapetyan, G.S.; Deppman, A.; Guimaraes, V. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica; Balabekyan, A.R. [Yerevan State University, Alex Manoogian 1, Yerevan (Armenia); Demekhina, N.A. [Yerevan Physics Institute, Alikhanyan Brothers 2, Yerevan (Armenia); Joint Institute for Nuclear Research (JINR), Flerov Laboratory of Nuclear Reactions (LNR), Moscow (Russian Federation)

2014-07-01

We present an analysis of fission induced by intermediate energy protons or photons on actinides. The 660 MeV proton induced reactions are on {sup 241}Am, {sup 238}U, and {sup 237}Np targets and the Bremsstrahlung-photons with end-point energies at 50 MeV and 3500 MeV are on {sup 232}Th and {sup 238}U targets. The study was performed by means of the Monte Carlo simulation code CRISP. A multimodal fission extension was added to the code within an approach which accounts for the contribution of symmetric and asymmetric fission. This procedure allowed the investigation of fission cross sections, fissility, number of evaporated nucleons and fission-fragment charge distributions. The comparison with experimental data show a good agreement between calculations and experiments. (author)

Proton-induced fission of actinides at energies 26.5 and 62.9 MeV--Theoretical interpretation

International Nuclear Information System (INIS)

Demetriou, P.; Keutgen, Th.; Prieels, R.; El Masri, Y.

2011-01-01

Fission properties of proton-induced fission on 232 Th, 237 Np, 238 U, 239 Pu and 241 Am targets, measured at the Louvain-la-Neuve cyclotron facility at proton energies of 26.5 and 62.9 MeV, are compared with the predictions of the state-of-the-art nuclear reaction code TALYS. The sensitivity of the calculations to the input parameters of the code and possible improvements are discussed.

Comparison of fission and capture cross sections of minor actinides

International Nuclear Information System (INIS)

Nakagawa, Tsuneo; Iwamoto, Osamu

2003-01-01

The fission and capture cross sections of minor actinides given in JENDL-3.3 are compared with other evaluated data and experimental data. The comparison was made for 32 nuclides of Th-227, 228, 229, 230, 233, 234, Pa-231, 232, 233, U-232, 234, 236, 237, Np-236, 237, 238, Pu-236, 237, 238, 242, 244, Am-241, 242, 242m, 243, Cm-242, 243, 244, 245, 246, 247 and 248. Given in the present report are figures of these cross sections and tables of cross sections at 0.0253 eV and resonance integrals. (author)

Fission Product Yields from {sup 232}Th, {sup 238}U, and {sup 235}U Using 14 MeV Neutrons

Energy Technology Data Exchange (ETDEWEB)

Pierson, B.D., E-mail: bpnuke@umich.edu [Department of Nuclear Engineering Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48109 (United States); Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Greenwood, L.R. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Flaska, M. [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, 227 Reber Bldg., University Park, PA 16802 (United States); Pozzi, S.A. [Department of Nuclear Engineering Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48109 (United States)

2017-01-15

Neutron-induced fission yield studies using deuterium-tritium fusion-produced 14 MeV neutrons have not yet directly measured fission yields from fission products with half-lives on the order of seconds (far from the line of nuclear stability). Fundamental data of this nature are important for improving and validating the current models of the nuclear fission process. Cyclic neutron activation analysis (CNAA) was performed on three actinide targets–thorium-oxide, depleted uranium metal, and highly enriched uranium metal–at the University of Michigan's Neutron Science Laboratory (UM-NSL) using a pneumatic system and Thermo-Scientific D711 accelerator-based fusion neutron generator. This was done to measure the fission yields of short-lived fission products and to examine the differences between the delayed fission product signatures of the three actinides. The measured data were compared against previously published results for {sup 89}Kr, −90, and −92 and {sup 138}Xe, −139, and −140. The average percent deviation of the measured values from the Evaluated Nuclear Data Files VII.1 (ENDF/B-VII.1) for thorium, depleted-uranium, and highly-enriched uranium were −10.2%, 4.5%, and −12.9%, respectively. In addition to the measurements of the six known fission products, 23 new fission yield measurements from {sup 84}As to {sup 146}La are presented.

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

Fission barriers and asymmetric ground states in the relativistic mean-field theory

International Nuclear Information System (INIS)

Rutz, K.; Reinhard, P.G.; Greiner, W.

1995-01-01

The symmetric and asymmetric fission path for 240 Pu, 232 Th and 226 Ra is investigated within the relativistic mean-field model. Standard parametrizations which are well fitted to nuclear ground-state properties are found to deliver reasonable qualitative and quantitative features of fission, comparable to similar nonrelativistic calculations. Furthermore, stable octupole deformations in the ground states of radium isotopes are investigated. They are found in a series of isotopes, qualitatively in agreement with nonrelativistic models. But the quantitative details differ amongst the models and between the various relativistic parametrizations. (orig.)

Radiochemical studies on fission

Energy Technology Data Exchange (ETDEWEB)

None

1973-07-01

Research progress is reported on nuclear chemistry; topics considered include: recoil range and kinetic energy distribution in the thermal neutron ftssion of /sup 245/Cm; mass distribution and recoil range measurements in the reactor neutron-induced fission of /sup 232/U; fission yields in the thermal neutron fission of /sup 241/PU highly asymmetric binary fission of uranium induced by reactor neutrons; and nuclear charge distribution in low energy fission. ( DHM)

232-Th and 238-U radioactive contaminations of sediments along the South China Sea of East Coast Peninsular Malaysia by INAA

International Nuclear Information System (INIS)

Khadijeh Rezaee Ebrahim Saraee; Elias Saion; Naghavi, K.

2009-01-01

The concentrations of 232 Th and 238 U were determined in 30 sediment samples, collected from the South China Sea bed of the east coast peninsular Malaysia. The samples were dried in an oven for 10 days at 65 C and stored in polyethylene bottles for future analysis. INAA used to analyse surficial sediments. The 232 Th and 238 U activities in surficial sediments determined. These activities increased from 14.02 to 30.17 Bq Kg -1 and from 47.49 to 113.69 Bq Kg -1 for 232 Th and 238 U , respectively. Results show diffuse distribution of 232 Th and 238 U actinides in studied area. The Th/Sc and U/Sc ratios of the suricial sediments have same distribution and the highest their values are in station EC12. The radioactive contamination of the investigated sector is compared with the results obtained of other coastal sediments of Malaysia. Results show activity contamination in coastal sediments of the South China Sea is lower than the Straits of Malacca and is the same with the Straits of Johor. (Author)

Fission gas release from ThO2 and ThO2--UO2 fuels (LWBR development program)

International Nuclear Information System (INIS)

Goldberg, I.; Spahr, G.L.; White, L.S.; Waldman, L.A.; Giovengo, J.F.; Pfennigwerth, P.L.; Sherman, J.

1978-08-01

Fission gas release data are presented from 51 fuel rods irradiated as part of the LWBR irradiations test program. The fuel rods were Zircaloy-4 clad and contained ThO 2 or ThO 2 -UO 2 fuel pellets, with UO 2 compositions ranging from 2.0 to 24.7 weight percent and fuel densities ranging from 77.8 to 98.7 percent of theoretical. Rod diameters ranged from 0.25 to 0.71 inches and fuel active lengths ranged from 3 to 84 inches. Peak linear power outputs ranged from 2 to 22 kw/ft for peak fuel burnups up to 56,000 MWD/MTM. Measured fission gas release was quite low, ranging from 0.1 to 5.2 percent. Fission gas release was higher at higher temperature and burnup and was lower at higher initial fuel density. No sensitivity to UO 2 composition was evidenced

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.

Modeling fission gas release in high burnup ThO2-UO2 fuel

International Nuclear Information System (INIS)

Long, Y.; Yuan, Y.; Pilat, E.E.; Rim, C.S.; Kazimi, M.S.

2001-01-01

A preliminary fission gas release model to predict the performance of thoria fuel using the FRAPCON-3 computer code package has been formulated. The following modeling changes have been made in the code: - Radial power/burnup distribution; - Thermal conductivity and thermal expansion; - Rim porosity and fuel density; - Diffusion coefficient of fission gas in ThO 2 -UO 2 fuel and low temperature fission gas release model. Due to its lower epithermal resonance absorption, thoria fuel experiences a much flatter distribution of radial fissile products and radial power distribution during operation as compared to uranian fuel. The rim effect and its consequences in thoria fuel, therefore, are expected to occur only at relatively high burnup levels. The enhanced conductivity is evident for ThO 2 , but for a mixture the thermal conductivity enhancement is small. The lower thermal fuel expansion tends to negate these small advantages. With the modifications above, the new version of FRAPCON-3 matched the measured fission gas release data reasonably well using the ANS 5.4 fission gas release model. (authors)

Thorium determination in water and biological materials by fission track

International Nuclear Information System (INIS)

Melo Ferreira, A.C. de.

1989-01-01

As a segment of a research programme on the study of bioaccumulation of radionuclides, in animals and vegetables from Morro do Ferro, Pocos de Caldas, MG, a fission track method for the determination of low levels of thorium in environmental samples was developed as an alternative for alpha spectroscopy. The study was carried out in early alpha spectroscopy samples, containing high levels of 228 Th activity, which makes difficult the 232 Th determination. A dry way method for thorium evaluation was developed. Pieces of membrane filters, containing La F 3 (Th), coupled to Makrofol detectors, were irradiated in the core of a research reactor, IEA-R1 (IPEN). (author)

Mica fission detectors

International Nuclear Information System (INIS)

Wong, C.; Anderson, J.D.; Hansen, L.; Lehn, A.V.; Williamson, M.A.

1977-01-01

The present development status of the mica fission detectors is summarized. It is concluded that the techniques have been refined and developed to a state such that the mica fission counters are a reliable and reproducible detector for fission events

Fission physics experiments at the time-of-flight spectrometer GNEIS in Gatchina (PNPI)

International Nuclear Information System (INIS)

Shcherbakov, O.A.

1994-01-01

The outline of and fission physics experiments at the Gatchina neutron spectrometer GNEIS based on the 1 GeV PNPI proton synchrotron are presented. The prefission gamma-ray spectrum of the (n, gamma f) reaction were investigated. The capture gamma-ray spectra for 721.6 eV and 1211.4 eV resonances in U-238 were measured and the nature of the 721.6 eV resonance in U-238 were examined. The forward-backward asymmetry in slow neutron fission of U-235 and energy dependence of the forward-backward and instrumental asymmetry coefficients were obtained. Fission cross section ratios for Th-232 to U-235 and for U-238 to U-235 in the energy range up to 200 MeV were measured. The results of the cross section ratios agreed well with those of Behrens et al. and Difilippo et al. (T.H.)

Neutron inelastic-scattering cross sections of 232Th, 233U, 235U, 238U, 239Pu and 240Pu

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.

1982-01-01

Differential-neutron-emission cross sections of 232 Th, 233 U, 235 U, 238 U, 239 Pu and 240 Pu are measured between approx. = 1.0 and 3.5 MeV with the angle and magnitude detail needed to provide angle-integrated emission cross sections to approx. 232 Th, 233 U, 235 U and 238 U inelastic-scattering values, poor agreement is observed for 240 Pu, and a serious discrepancy exists in the case of 239 Pu

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)

226Ra, 232Th and 40K analysis in sand samples from some beaches of Great Vitoria, Espirito Santo, Brazil: preliminary results

International Nuclear Information System (INIS)

Aquino, Reginaldo R.; Pecequilo, Brigitte R.S.

2009-01-01

The natural radioactivity in superficial beach sand samples of 7 beaches of Great Vitoria, metropolitan region of the State of Espirito Santo, southeast Brazil, was determined from the 226 Ra, 232 Th and 4 0 K contents. The assessed beaches were Manguinhos, Camburi, Praia do Canto, Curva da Jurema, Itapua, Setibao and Areia Preta. Three samples of each beach were sealed in standard 100 mL polyethylene flasks and stored in order to obtain secular equilibrium in the 238 U and 232 Th series. All samples were measured by high resolution gamma spectrometry and the spectra were analyzed with the WinnerGamma software. The 232 Th concentration was determined from the average concentrations of 228 Ac, 212 Pb and 212 Bi and the 226 Ra concentration was determined from the average concentrations of 214 Pb and 214 Bi. Preliminary results show concentrations varying from 9 Bq.kg -1 to 6035 Bq.kg -1 for 232 Th, from 4 Bq.kg -1 to 575 Bq.kg -1 for 226 Ra and from 13 Bq.kg -1 to 142 Bq.kg -1 for 40 K. Areia Preta beach shows the highest values for 232 Th, while the highest value for 226 Ra was observed for Camburi beach. High values of 40 K were observed for Curva da Jurema beach. (author)

226Ra, 232Th and 40K analysis in water samples from Assiut, Egypt

International Nuclear Information System (INIS)

El-Gamal, H.; Abdel Mageed, A.I.; El-Attar, A.L; Abdel Hamid, M.

2013-01-01

The activity concentrations of 226 Ra, 232 Th and 40 K were determined in water samples, using 2”x 2” NaI(Tl) scintillation detector. Water activity ranges from 0.07 to 0.59 Bq L−1 for 226 Ra, 0.05 to 0.37 Bq L−1 for 232 Th and 3.25 to 8.72 Bq L−1 for 40 K with mean values of 2.64, 2.22 and 119.50 Bq L−1, respectively. As far as the measured gamma radionuclides is concerned, the mean annual effective doses for all analyzed samples of water are in the range of 0.02–0.08, 0.03-0.17 and 0.03-0.10 mSv yr -1 for infants, children and adults, respectively, all being lower than the reference level of the committed effective dose recommended by the WHO.

US industry optimistic on fission's 50th anniversary

International Nuclear Information System (INIS)

Anon.

1992-01-01

The United States (US) nuclear industry is looking to the future even as it prepares to celebrate the 50th anniversary of the first fission chain reaction - that momentous event which took place on a cold 2 December 1942 morning below the stands of a football field at the University of Chicago. Plans to incorporate nuclear power into US energy policy are well advanced. (Author)

Symmetric and asymmetric ternary fission of hot nuclei

International Nuclear Information System (INIS)

Siwek-Wilczynska, K.; Wilczynski, J.; Leegte, H.K.W.; Siemssen, R.H.; Wilschut, H.W.; Grotowski, K.; Panasiewicz, A.; Sosin, Z.; Wieloch, A.

1993-01-01

Emission of α particles accompanying fusion-fission processes in the 40 Ar + 232 Th reaction at E( 40 Ar) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight measurements allowed us to reconstruct the complete kinematics of each ternary event. The coincident energy spectra of α particles were analyzed by using predictions of the energy spectra of the statistical code CASCADE . The analysis clearly demonstrates emission from the composite system prior to fission, emission from fully accelerated fragments after fission, and also emission during scission. The analysis is presented for both symmetric and asymmetric fission. The results have been analyzed using a time-dependent statistical decay code and confronted with dynamical calculations based on a classical one-body dissipation model. The observed near-scission emission is consistent with evaporation from a dinuclear system just before scission and evaporation from separated fragments just after scission. The analysis suggests that the time scale of fission of the hot composite systems is long (about 7x10 -20 s) and the motion during the descent to scission almost completely damped

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.)

Neutron data evaluation of 232U

International Nuclear Information System (INIS)

Maslov, V.M.; Porodzinskij, Yu.V.; Tetereva, N.A.; Kagalenko, A.B.; Kornilov, N.V.; Baba, M.; Hasegawa, A.

2003-03-01

Consistent evaluation of 232 U measured data base is performed. Hauser-Feshbach- Moldauer theory, coupled channel model and double-humped fission barrier model are employed. Total, differential scattering, fission and (n,xn) data are consistently reproduced as a major constraint for inelastic scattering cross section estimate. The direct excitation of ground state and higher band levels is calculated within rigid rotator and soft (deformable) rotator model, respectively. Prompt fission neutron spectra data are described. Average resonance parameters are provided, which reproduce evaluated cross sections in the range of 10-150 keV. (author)

Extension of the Th-232 burnup chain in the WIMSD/4 program library

International Nuclear Information System (INIS)

Caldeira, A.D.

1991-07-01

The Th-232 burnup chain was extended through U-236, in the WIMSD/4 program library. The evolution of the values of k i nf and U-235 number density, as function of time, for the modified TRX1 problem, calculated with the new library, shows an improvement in the results when compared with LEOPARD program. (author)

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.

{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)

Activity concentrations of 226Ra, 232Th and 40K in brands of fertilisers used in Nigeria

International Nuclear Information System (INIS)

Jibiri, N. N.; Fasae, K. P.

2012-01-01

The activity concentration of naturally occurring radionuclides 40 K, 226 Ra and 232 Th have been measured in different brands of fertiliser samples sold to farmers in retail markets in six commercial cities in southwestern Nigeria. Gamma ray spectroscopy was employed in the measurements of these radionuclides. The results of measurements showed that the average activity concentration of 40 K in the nitrogen, phosphorus and potassium fertilisers across the cities varied from 3972.0 ±416.9 to 5089.3 ±111.3 Bq kg -1 , 9.9 ±7.3 to 450.6 ±14.3 Bq kg -1 for 226 Ra, while for 232 Th it varied from less than lower limit of detection to 15.1 ±2.8 Bq kg -1 . The activity concentrations of 40 K, 226 Ra and 232 Th in single super phosphate (SSP) fertilisers and phosphate rocks were also determined. However, high activity concentrations of 226 Ra were obtained in the SSP fertiliser and phosphate rocks and in particular, two brands of fertilisers from ITL/TAK and F and C companies. The values of the activity concentration of the radionuclides in the brands of fertilisers used in Nigeria are within the range of values reported in several other countries except 40 K. (authors)

Fission yield correlation generation and impact on nuclear problems - 15570

International Nuclear Information System (INIS)

Fiorito, L.; Stankovskiy, A.; Van den Eynde, G.

2015-01-01

In our work we defined a scheme to update fission yields and their covariance matrices. We implemented a Generalised Linear Least Square (GLLS) updating procedure to produce inter-isotope fission yield correlations. At each update, a constraining equation was selected and the related set of observables calculated using the prior knowledge of the fission yield data and uncertainties. Then, available extra information on each observable was introduced into the system - e.g. a data set of direct measurements or uncertainties. Our GLLS-based updating tool calculates best-estimate posterior fission yields and covariance matrices which merge both the extra and prior data. The major result of the update is the generation of fission yield correlations. We created complete updated covariance matrices for 6 nuclides (Th 232 , U 233 , U 235 , U 238 , Pu 239 and Pu 241 ) and a total of 14 fissioning systems using the JEFF-3.1.1 files. The fission yield covariance matrices were tested against the criticality and nuclide inventory calculations of the REBUS single pin benchmark after one irradiation cycle. It appears that fission yield correlations reduce the uncertainties to a very great extent, which in many cases are 4 times smaller than those obtained with uncorrelated data

Study of electron-capture delayed fission in Am-232

International Nuclear Information System (INIS)

Kreek, S.A.; Hall, H.L.; Hoffman, D.C.; Strellis, D.; Gregorich, K.E.

1996-01-01

An automated x-ray-fission coincidence system was designed and constructed by LLNL and Lawrence Berkeley National Laboratory (LBNL) for use inside the Gammasphere high efficiency gamma-ray detector array at LBNL. The x-ray-fission coincidence apparatus detection station consists of two surface barrier detectors (for detection of fission fragments) and two high-purity Ge (HPGe) planar x-ray detectors (for measurement of x-rays and low-energy gamma rays). The detection station is placed inside Gammasphere at the 88-Inch Cyclotron at LBNL and used in conjunction with Gammasphere to measure the x-rays, low-energy gamma-rays and fission fragments resulting from the ECDF process. A series of collaborative experiment between LLNL, LBNL, and LANL utilizing various components of the x-ray-fission coincidence apparatus to measure x-rays and gamma-rays in the decay of a stationary 252 Cf source were performed to test the various components of the x-ray-fission coincidence apparatus. The test experiments have been completed and the data is currently being analyzed by LBNL. Preliminary test results indicate that the system performed better than expected (e.g., the x-ray detectors performed better than expected with no evidence of microphonic noise that would reduce the photon energy resolution)

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.

232Th(d,4n)230Pa cross-section measurements at ARRONAX facility

International Nuclear Information System (INIS)

Duchemin, C.; Guertin, A.; Metivier, V.; Haddad, F.

2015-01-01

Full text of publication follows. The ARRONAX cyclotron [Ref.1], acronym for 'Accelerator for Research in Radiochemistry and Oncology at Nantes Atlantique' is a new facility installed in Nantes, France. A dedicated program has been launched on production of innovative radionuclides for PET imaging and for β- and α- targeted radiotherapy using proton or α particle. Since the accelerator is also able to deliver deuteron beams up to 35 MeV, we have reconsidered the possibility to use them to produce medical isotopes. In this study, we have focused on cross section measurements using the stacked-foil technique [Ref. 2] of one isotope dedicated to alpha radio-immunotherapy (α RIT) [Ref.3], 226 Th which can be produced through different routes. It's of great interest since it has been found to be a more potent alpha particle emitter for leukemia therapies than Bi 213 [Ref.4]. Indeed, the 226 Th decay produced a cascade of four α particles with a cumulated energy of 27.7 MeV. An additional interest is the possible use of a radionuclide generator system 230 U/ 226 Th. 230 U could be produced directly via 231 Pa(p, 2n) 230 U, and indirectly via 230 Pa using proton or deuteron beams through 232 Th(p, 3n) 230 Pa → 230 U, 232 Th(d, 4n) 230 Pa → 230 U. Twelve data sets are published concerning the 230 Pa cross section induced by proton [Ref 5], only one by deuteron [Ref.6]. As sometimes deuteron induced reaction gives higher cross section values, it seems interesting to focus our study on their use as projectile on 232 Th target to produce 230 Pa. Contaminants created during irradiation are also measured since a good optimization of the process is supposed to find the best compromise between production yield and purity of the final product. Our new sets of data are compared with the existing data [Refs.5,6] on other existing production routes and with results given by TALYS code calculations [Ref.7]. References: 1] F. Haddad and al., Eur. J. Med. Mol

Production of 11Li in the (11B,11Li) reaction on 232Th

International Nuclear Information System (INIS)

Scott, D.K.; Buenerd, M.; Hendrie, D.L.; KeKelis, G.; Mahoney, J.; Menchaca-Rocha, A.; Olmer, C.

1975-01-01

Production of the neutron-rich nucleus 11 Li in the bombardment of 232 Th by 11 B at 114 MeV suggests that multinucleon transfer reactions induced by neutron excess heavy ions on heavy targets present a feasible method of measuring the mass excess of exotic light nuclei in the limit of stability

U and Th thin film neutron dosimetry for fission-track dating: application to the age standard Moldavite

International Nuclear Information System (INIS)

Iunes, P.J.; Bigazzi, G.; Hadler Neto, J.C.; Laurenzi, M.A.; Balestrieri, M.L.; Norelli, P.; Osorio Araya, A.M.; Guedes, S.; Tello S, C.A.; Paulo, S.R.; Moreira, P.A.F.P.; Palissari, R.; Curvo, E.A.C.

2005-01-01

Neutron dosimetry based on U and Th thin films was used for fission-track dating of the age standard Moldavite, the central European tektite, from the Middle Miocene deposit of Jankov (southern Bohemia, Czech Republic). Our fission-track age (13.98+/-0.58Ma) agrees with a recent 40 Ar/ 39 Ar age, 14.34+/-0.04Ma, based on several determinations on Moldavites from different sediments, including the Jankov deposit. This result indicates that the U and Th thin film neutron dosimetry represents a reliable alternative for an absolute approach in fission-track dating

Qualitative analysis of Th-232 in soil samples with portable radiological identifiers NaI (Tl) and LaBr{sub 3} (Ce); Análise qualitativa de Th-232 em amostras de solo com identificadores radiológicos portáteis NaI(Tl) e LaBr{sub 3}(Ce)

Energy Technology Data Exchange (ETDEWEB)

Oliveira, L.S.R.; Amorim, A.S.; Balthar, M.C.V.; Vilela, P.RT.; Santos, A. [Instituto de Defesa, Química, Biológica, Radiológica e Nuclear (IDQBRN), Rio de Janeiro, RJ (Brazil); Cardoso, D.O.; Izidoro, A.C.A.C. [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil); Pelegrineli, S.Q.; Silva, L.B.; Silva, S.L. [MAXIM Treinamento e Assessoria, Rio de Janeiro, RJ (Brazil); Santos, F.R.; Ribeiro, C.A.M.; Silva, D.C., E-mail: lucianosantarita@gmail.com, E-mail: domingosoliveiralvr71@gmail.com, E-mail: samuelfisica@yahoo.com.br [Universidade Estácio de Sá, Rio de Janeiro, RJ (Brazil)

2017-07-01

The identification of the occurrence of Th-232 in open environments using portable radiological identifiers (IRP) with scintillators, discriminating the environmental condition and NORM is important for the operational teams of the Institute of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN) of the Army. The qualitative analysis by gamma energy spectrometry for the energies of Th-232 and its daughter radioisotopes, given the resolution that characterizes the scintillation crystals (NaI (Tl) - 7.5% and LaBr{sub 3} (Ce) - 2.9%) makes it possible to identify them. The purpose is to perform a qualitative analysis of the reliability of the response of these IRPs to the measurements of Th-232 generally found in the environment and in samples extracted from points where the thorium concentration is highest. The results show that the identification of this radionuclide by the IRP in the samples with the highest natural occurrence is achieved by measuring the energies of the daughter isotopes Ac-228, Tl-208, Bi-212 and Pb-212 allowing the discrimination of soils with natural occurrence of Th -232 and NORM. These measurements will be based on the procedures used by the operational teams in the field actions aimed at reducing exposure to this radiation, both for individuals occupationally exposed and for the population.

Neutron radiative capture cross section of 232Th in the energy range 0.1 to 1.2 MeV

International Nuclear Information System (INIS)

Jain, H.M.; Kailas, S.

1987-01-01

Recently reported neutron radiative capture cross section of 232 Th measurements in the energy range 0.1 to 1.2 MeV are compared with the calculations based on the statistical model Hauser-Feshbach theory using the spherical optical model transmission coefficients and simple Fermi gas level density formula. The calculations are in good agreement with the recent experimental data, reproducing both the absolute magnitude and the shape exhibited by the excitation function. The results of this comparative study can be used for improving the evaluation of the neutron radiative capture cross section of 232 Th. 16 refs., 3 tables, 4 figures. (author)

Neutron radiative capture cross section of 232Th in the energy range 0.1 to 1.2 MeV

International Nuclear Information System (INIS)

Jain, H.M.; Kailas, S.

1987-03-01

Recently reported neutron radiative capture cross section of Th-232 measurements in the energy range 0.1 to 1.2 MeV are compared with the calculations based on the statistical model Hauser-Feshbach theory using the spherical optical model transmission coefficients and simple Fermi gas level density formula. The calculations are in good agreement with the recent experimental data, reproducing both the absolute magnitude and the shape exhibited by the excitation function. The results of this comparative study can be used for improving the evaluation of the neutron radiative capture cross section of Th-232. (author)

A semi-empirical formula on the pre-neutron-emission fragment mass distribution in nuclear fission

International Nuclear Information System (INIS)

Wang Fucheng; Hu Jimin

1988-03-01

A 5-Gauss semi-empirical formula on the pre-neutron-emission fragment mass distribution is given. The absolute standard deviation and maximum departure between calculated values and experimental data for (n,f) and (n,n'f) fission reactions from 232 Th to 245 Cm are approximately 0.4% and 0.8%, respectively. The error will get bigger if the formula is used at higher excitation energies

Development and manufacturing of special fission chambers for in-core measurement requirements in nuclear reactors

International Nuclear Information System (INIS)

Geslot, B.; Berhouet, F.; Oriol, L.; Breaud, S.; Jammes, C.; Filliatre, P.; Villard, J. F.

2009-01-01

The Dosimetry Command control and Instrumentation Laboratory (LDCI) at CEA/Cadarache is specialized in the development, design and manufacturing of miniature fission chambers (from 8 mm down to 1.5 mm in diameter). The LDCI fission chambers workshop specificity is its capacity to manufacture and distribute special fission chambers with fissile deposits other than U 235 (typically Pu 242 , Np 237 , U 238 , Th 232 ). We are also able to define the characteristics of the detector for any in-core measurement requirements: sensor geometry, fissile deposit material and mass, filling gas composition and pressure, operating mode (pulse, current or Campbelling) with associated cable and electronics. The fission chamber design relies on numerical simulation and modeling tools developed by the LDCI. One of our present activities in fission chamber applications is to develop a fast neutron flux instrumentation using Campbelling mode dedicated to measurements in material testing reactors. (authors)

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 226Ra, 232Th and 40K in soils and sugar cane crops at Corumbatai river basin, Sao Paulo State, Brazil

International Nuclear Information System (INIS)

Tomazini da Conceicao, Fabiano; Bonotto, Daniel Marcos; Jimenez-Rueda, Jairo Roberto; Frutuoso Roveda, Jose Arnaldo

2009-01-01

The common use of phosphate fertilizers NPK and amendments in sugar cane crops in Brazilian agriculture may increase the 226 Ra, 232 Th and 40 K activity concentrations in soils and their availability for plants and human food chain. Thus, the main aim of this study was to evaluate the distribution of 226 Ra, 232 Th and 40 K in soils and sugar cane crops in the Corumbatai river basin, Sao Paulo State, Brazil. The gamma spectrometry was utilized to measure the 226 Ra, 232 Th and 40 K activity concentration in all samples. The soil-to-sugar cane transfer factors (TF) were quantified using the ratio between the radionuclide activity concentration in sugar cane and its activity concentration in soil. The results show that, although radionuclides incorporated in phosphate fertilizers and amendments are annually added in the sugar cane crops, if utilized in accordance with the recommended rates, their use does not lead to hazards levels in soils. The soil-to-sugar cane transfer of radionuclides occurred in the following order 40 K> 226 Ra> 232 Th. Therefore, under these conditions, radionuclides intake through consumption of sugar is not hazardous to human health.

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

P-wave assignment of 232Th neutron resonances

International Nuclear Information System (INIS)

Corvi, F.; Pasquariello, G.; Veen, T. van der

1978-01-01

A method of p-wave assignment which exploits the parity dependence of the primary capture γ-ray spectrum was applied to the 232 Th resonance. The yield of capture γ-rays above 4.4 MeV from a 6 mm thick metallic thorium disk was measured in the neutron energy range 20-2200 eV and compared to a similar run with γ-rays in the range 3.7 - 4.4 MeV. A total of 58 resonances showing an enhancement of the high energy γ-ray yield were assigned as p-waves. Assuming that their reduced neutron widths follow a Porter-Thomas distribution, their average value and then the p-wave strength function S 1 were estimated with a maximum likelihood method. The results are: average neutron width=3.4(+0.8 or -0.6)meV; S 1 = 2.0 (+0.5 or -0.4).10 -4

The Distributions of the Radionuclides Ra-226, Th-232 and K-40 in Various Parts of The Alfalfa Plant

International Nuclear Information System (INIS)

Salahel Din, K.; Harb, S.; Abbady, A.; Saad, N.

2011-01-01

The distribution of naturally occurring Ra-226, Th-232 and K-40 in different part of alfalfa plant from two different soils of Qena (South Valley University and Qena governorate farms) was studied under natural field conditions. Sixty two samples (alfalfa plant and its soil) were taken from nine sites inside farms. The samples were analyzed for their Ra-226, Th-232 and K-40 activity concentrations using gamma ray spectrometer consists of 3 x 3 NaI (Tl). The daily intakes of these radioisotopes by calves, milking cattle and sheep were calculated by multiplying concentrations in alfalfa and the daily consumption rates of these plants.

Excitation of giant resonances through inelastic scattering of 170 at 84 MeV/u. Fission decay of giant resonances

International Nuclear Information System (INIS)

Cabot, C.; Barrette, J.; Mark, S.K.; Turcotte, R.; Xing, J.; Van der Woude, A.; Van Den Berg, A. M.

1991-01-01

Inelastic scattering of 84 MeV/u 17 0 projectiles have been used to excite the giant resonances (GR) in various nuclei ranging from A=60 to A=232. For the isoscalar giant quadrupole resonance (ISGQR), the energy and width of the resonance, as well as the EWSR obtained from the measured cross sections, are in agreement with the known systematics for A>40. The observed GMR strengths are close to 100% EWRS and are consistent with other recent experimental results using heavy ion projectiles. These results lead to a somewhat different picture than that provided by previous studies using light projectiles. Strength is also observed at high excitation energy. The analysis of these resonances is in progress. Our study of the fission decay of GR in 232 Th leads to a somewhat different conclusion than previously deduced from data obtained with light ion projectiles, where no evidence for the fission decay of the ISGQR has been found. In the present work, due to the very good peak-to-continuum ratio, a structure is observed in the fission coincidence spectrum around 10 MeV which can be attributed to the fission decay of giant resonances. The measured fission probability is consistent with a statistical decay of the ISGQR. 10 figs

Fusion-Fission Hybrid for Fissile Fuel Production without Processing

Energy Technology Data Exchange (ETDEWEB)

Fratoni, M; Moir, R W; Kramer, K J; Latkowski, J F; Meier, W R; Powers, J J

2012-01-02

Two scenarios are typically envisioned for thorium fuel cycles: 'open' cycles based on irradiation of {sup 232}Th and fission of {sup 233}U in situ without reprocessing or 'closed' cycles based on irradiation of {sup 232}Th followed by reprocessing, and recycling of {sup 233}U either in situ or in critical fission reactors. This study evaluates a third option based on the possibility of breeding fissile material in a fusion-fission hybrid reactor and burning the same fuel in a critical reactor without any reprocessing or reconditioning. This fuel cycle requires the hybrid and the critical reactor to use the same fuel form. TRISO particles embedded in carbon pebbles were selected as the preferred form of fuel and an inertial laser fusion system featuring a subcritical blanket was combined with critical pebble bed reactors, either gas-cooled or liquid-salt-cooled. The hybrid reactor was modeled based on the earlier, hybrid version of the LLNL Laser Inertial Fusion Energy (LIFE1) system, whereas the critical reactors were modeled according to the Pebble Bed Modular Reactor (PBMR) and the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) design. An extensive neutronic analysis was carried out for both the hybrid and the fission reactors in order to track the fuel composition at each stage of the fuel cycle and ultimately determine the plant support ratio, which has been defined as the ratio between the thermal power generated in fission reactors and the fusion power required to breed the fissile fuel burnt in these fission reactors. It was found that the maximum attainable plant support ratio for a thorium fuel cycle that employs neither enrichment nor reprocessing is about 2. This requires tuning the neutron energy towards high energy for breeding and towards thermal energy for burning. A high fuel loading in the pebbles allows a faster spectrum in the hybrid blanket; mixing dummy carbon pebbles with fuel pebbles enables a softer spectrum in

Measurement of neutron-induced fission cross-sections of Th232, U238, U233 and Np237 relative to U235 from 1 MeV to 200 MeV

Energy Technology Data Exchange (ETDEWEB)

Shcherbakov, O.A.; Laptev, A.B.; Petrov, G.A. [Petersburg Nuclear Physics Inst., Gatchina, Leningrad district (Russian Federation); Fomichev, A.V.; Donets, A.Y.; Osetrov, O.I.

1998-11-01

The measurements of neutron-induced cross-section ratios for Th232, U238, U233 and Np237 relative to U235 have been carried out in the energy range from 1 MeV up to 200 MeV using the neutron time-of-flight spectrometer GNEIS based on 1 GeV proton synchrocyclotron. Below 20 MeV, the results of present measurements are roughly in agreement with evaluated data though there are some discrepances to be resolved. (author)

Development and manufacturing of special fission chambers for in-core measurement requirements in nuclear reactors

Energy Technology Data Exchange (ETDEWEB)

Geslot, B.; Berhouet, F.; Oriol, L.; Breaud, S.; Jammes, C.; Filliatre, P.; Villard, J. F. [CEA, DEN, Dosimetry Command Control and Instrumentation Laboratory, F-13109 Saint-Paul-lez-Durance (France)

2009-07-01

The Dosimetry Command control and Instrumentation Laboratory (LDCI) at CEA/Cadarache is specialized in the development, design and manufacturing of miniature fission chambers (from 8 mm down to 1.5 mm in diameter). The LDCI fission chambers workshop specificity is its capacity to manufacture and distribute special fission chambers with fissile deposits other than U{sup 235} (typically Pu{sup 242}, Np{sup 237}, U{sup 238}, Th{sup 232}). We are also able to define the characteristics of the detector for any in-core measurement requirements: sensor geometry, fissile deposit material and mass, filling gas composition and pressure, operating mode (pulse, current or Campbelling) with associated cable and electronics. The fission chamber design relies on numerical simulation and modeling tools developed by the LDCI. One of our present activities in fission chamber applications is to develop a fast neutron flux instrumentation using Campbelling mode dedicated to measurements in material testing reactors. (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)

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

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

Fission-evaporation competition in excited uranium and fermium nuclei

International Nuclear Information System (INIS)

Sagajdak, R.N.; Chepigin, V.I.; Kabachenko, A.P.

1997-01-01

The production cross sections and excitation functions for the 223-226 U neutron deficient isotopes have been measured in the 20 Ne+ 208 Pb and 22 Ne+ 208 Pb reactions for (4,5)n and (4-7)n evaporation channels of the de-excitation of the compound nuclei 228 U* and 230 U*, respectively. The present study considers in addition the de-excitation via the (5,6)n evaporation channels of the 224 U* compound nucleus formed in the 27 Al+ 197 Au reaction. The production cross sections of 247g,246 Fm formed after evaporation of (5,6)n and (7,8)n from the 252 Fm* and 254 Fm* compound nuclei produced in the 20 Ne+ 232 Th and 22 Ne+ 232 Th reactions were also measured respectively. The evaporation residues emerging from the target were separated in-flight from the projectiles and background reaction products by the electrostatic recoil separator VASSILISSA [1]. The investigation regards the U and Fm compound nuclei in the 40-80 MeV excitation energy range. For the analysis of the (Hl, xn) evaporation cross sections the advanced statistical model [2] calculations were used. The angular momentum dependence of the shell correction to the fission barrier, and the effects of the nuclear viscosity and dynamical deformation for these fissile excited nuclei are considered. The n /Γ t > values at the initial steps of the de-excitation cascade for the U and Fm compound nuclei were derived from the measured excitation functions and discussed from the point of view of the consequences for the fission process dynamics

Evaluation of Ra-226, Th-232 and K-40 activities concentrations and radium equivalent index in several Brazilian economic wall paints

International Nuclear Information System (INIS)

Fonseca, Leandro M.; Pecequilo, Brigitte R.S.

2015-01-01

The titanium dioxide used as the white pigment in paints is produced from the processing of ilmenite minerals. As monazite, the main ilmenite radioactive contaminant, contains 1 to 20% thorium dioxide and also some uranium traces, so, eventually, wall paints can contain radioactivity. Activity concentrations of the naturally occurring radionuclides 226 Ra, 232 Th and 40 K were determined in 15 Brazilian economic wall paints samples, by high resolution gamma-ray spectrometry. The activities concentrations in the studied samples ranged from 1.3 ± 0.2 Bq/kg to 23.4 ± 0.7 Bq/kg for 226 Ra; from 2.5 ± 0.4 Bq/kg to 45.8 ± 1.5 Bq/kg for 232 Th and from 5.8 ± 2.1 Bq/kg to 157 ± 22 Bq/kg for 40 K. The radium equivalent index, calculated from the 226 Ra, 232 Th and 40 K concentrations, varied from 1.30 Bq/kg up to 95.9 Bq/kg, below the value of 370 Bq/kg recommended by OECD for a safety use in residential building applications. (author)

Determination of Ra-226 and Th-232 in samples of natural phosphates, industrial gypsums and surface soils by gamma spectrometry

International Nuclear Information System (INIS)

Pessenda, L.C.R.; Nascimento Filho, V.F. do; Nadai, E.A. de; Barros Ferraz, E.S. de; Sao Paulo Univ., Piracicaba

1988-01-01

The natural radioactivity in Ra-226 and Th-232 in samples of natural phosphates, industrial gypsums (phosphogypsums) and surface soils of different regions was measured by γ-ray spectrometry. The majority of phosphates and gypsums examined showed significantly higher values than soils, mainly in relation to Ra-226 activity. The activity ranges found for phosphates, gypsums and soils were: 79.1 - 3180 Bq/kg, 56.3 - 986.6 Bq/kg, 8.8 - 54.3 Bq/kg for Ra-226 and 33.6 - 1450.3 Bq/kg; 17.4 - 130,1 Bq/kg, 9.8 - 108.9 Bq/kg for Th-232, respectively. (author) [pt

Measuring 137Cs, 40K and decay products of 226Ra and 232Th in samples of different nature by a multidetector spectrometer

International Nuclear Information System (INIS)

Antovic, N.M.; Popovic, V.; Vukotic, P.

2011-01-01

A coincidence method for measuring 137 Cs, 40 K, 226 Ra and 232 Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of 137 Cs, 226 Ra and 232 Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer ones. (author)

Review of the neutron capture process in fission reactors

International Nuclear Information System (INIS)

Poenitz, W.P.

1981-07-01

The importance of the neutron capture process and the status of the more important cross section data are reviewed. The capture in fertile and fissile nuclei is considered. For thermal reactors the thermal to epithermal capture ratio for 238 U and 232 Th remains a problem though some improvements were made with more recent measurements. The capture cross section of 238 U in the fast energy range remains quite uncertain and a long standing discrepancy for the calculated versus experimental central reaction rate ratio C28/F49 persists. Capture in structural materials, fission product nuclei and the higher actinides is also considered

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

International Nuclear Information System (INIS)

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

1980-01-01

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

A Monte Carlo method for nuclear evaporation and fission at intermediate energies

International Nuclear Information System (INIS)

Deppman, A.; Likhachev, V.P.; Mesa, J.; Pina, S.R. de; Arruda-Neto, J.D.T.; Goncalves, M.; Rodriguez, O.

2003-04-01

We describe a Monte Carlo method to calculate the characteristics of the competition between particle evaporation and nuclear fission processes taking place in the compound nucleus formed after the intranuclear cascade following the absorption of intermediate energy photons by the nucleus. In this version we include not only neutrons, but also protons and alphas as possible evaporating particles. However, this method allows an ease inclusion of other evaporating particles, as deuteron or heavier clusters. Some results for 237 Np, 238 U, and 232 Th are shown. (author)

Studies on the Th biodistribution in internal contamination by the fission track method using animals

International Nuclear Information System (INIS)

Ciubotariu, M.; Danis, A.; Dumitrescu, G.; Cucu, M.

1998-01-01

In our previous studies on the U internal contamination, qualitative and quantitative results were obtained by using the fission track methods. In order to obtain complete data on the fissionable element internal contamination using animals, we started a similar study using Th as contaminating element and Wistar London breed rats as laboratory animals. Different ways to obtain internal contaminations were investigated: ingestion, inhalation, absorption by skin and through wounds. In this stage, Wistar-London breed rats of the same sex, weight and age were internal contaminated by 1 ml Th solution ingestion for each rat corresponding to an Annual Limit Intake.The animals were kept in normal life conditions and under permanent medical surveillance up to their sacrifice. Also, their evacuations where sampled every 24 hours. They were sacrificed at different time intervals after their contamination: 2 days (RAT 1), 7 days (RAT 2) and 14 days (RAT 3). After sacrifice, their vital organs were sampled, weighed, calcined, reweighed and finally analysed by track detection using the fission track micromapping technique. This technique was used in the following conditions: - mica-muscovite as track detector pre-etched for fossil tracks 18 h in HF; - the neutron irradiations were performed in the nuclear reactor VVR-S Bucharest at the neutron fluences of 3x10 15 - 2x10 16 fast neutrons/cm 2 . In order to check whether there is any U contribution to the fission track densities obtained in track detectors, U existing in the rat body due to food and water, the neutron irradiations of the ensembles were performed with and without 1 mm Cd shielding; - the visualization of the Th induced fission tracks were obtained by chemical etching in HF, 3 h at room temperature; - the Th track micromappings obtained in track detectors were studied by optical microscopy using a stereomicroscope WILD M7S for ensemble study (X6-X31) and a binocular ZEISS JENA microscope for qualitative and

The target preparation of "2"3"2Th plated on the nickel with copper as substrate and "2"3"0Pa generation

International Nuclear Information System (INIS)

Shen Hua; Geng Junxia; Gao Size; Zhang Guoxin; Zhang Lan; Li Wenxin; Li Qingnuan; Wu Guozhong

2014-01-01

The electrochemical parameters on nickel plating on the copper have been studied using aqueous electroplating technique. And thorium is plated on the nickel flake using molecular plating technique. The better experimental parameters are obtained. According to these optimized parameters, the "2"3"2Th target which is suitable for Cyclone-30 accelerator is prepared. The proton beam with energy of 21 MeV bombed the "2"3"2Th target (total beam time 20 μAh). The results showed that the better range of plating current density of nickel plated on copper is l.30∼1.68 A/dm"2. The thickness of nickel plating layer can reach more than 10 μm. The current density is 3∼5 mA/cm"2, and the thickness of plated thorium layer is up to micrometer scale. The binding force of as-prepared "2"3"2Th target is very well. There is "2"3"0Pa appeared after the target is bombed by the proton beam. (authors)

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)

Reprocessing free nuclear fuel production via fusion fission hybrids

Energy Technology Data Exchange (ETDEWEB)

Kotschenreuther, Mike, E-mail: mtk@mail.utexas.edu [Intitute for Fusion Studies, University of Texas at Austin (United States); Valanju, Prashant; Mahajan, Swadesh [Intitute for Fusion Studies, University of Texas at Austin (United States)

2012-05-15

Fusion fission hybrids, driven by a copious source of fusion neutrons can open qualitatively 'new' cycles for transmuting nuclear fertile material into fissile fuel. A totally reprocessing-free (ReFree) Th{sup 232}-U{sup 233} conversion fuel cycle is presented. Virgin fertile fuel rods are exposed to neutrons in the hybrid, and burned in a traditional light water reactor, without ever violating the integrity of the fuel rods. Throughout this cycle (during breeding in the hybrid, transport, as well as burning of the fissile fuel in a water reactor) the fissile fuel remains a part of a bulky, countable, ThO{sub 2} matrix in cladding, protected by the radiation field of all fission products. This highly proliferation-resistant mode of fuel production, as distinct from a reprocessing dominated path via fast breeder reactors (FBR), can bring great acceptability to the enterprise of nuclear fuel production, and insure that scarcity of naturally available U{sup 235} fuel does not throttle expansion of nuclear energy. It also provides a reprocessing free path to energy security for many countries. Ideas and innovations responsible for the creation of a high intensity neutron source are also presented.

Reprocessing free nuclear fuel production via fusion fission hybrids

International Nuclear Information System (INIS)

Kotschenreuther, Mike; Valanju, Prashant; Mahajan, Swadesh

2012-01-01

Fusion fission hybrids, driven by a copious source of fusion neutrons can open qualitatively “new” cycles for transmuting nuclear fertile material into fissile fuel. A totally reprocessing-free (ReFree) Th 232 –U 233 conversion fuel cycle is presented. Virgin fertile fuel rods are exposed to neutrons in the hybrid, and burned in a traditional light water reactor, without ever violating the integrity of the fuel rods. Throughout this cycle (during breeding in the hybrid, transport, as well as burning of the fissile fuel in a water reactor) the fissile fuel remains a part of a bulky, countable, ThO 2 matrix in cladding, protected by the radiation field of all fission products. This highly proliferation-resistant mode of fuel production, as distinct from a reprocessing dominated path via fast breeder reactors (FBR), can bring great acceptability to the enterprise of nuclear fuel production, and insure that scarcity of naturally available U 235 fuel does not throttle expansion of nuclear energy. It also provides a reprocessing free path to energy security for many countries. Ideas and innovations responsible for the creation of a high intensity neutron source are also presented.

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)

Determination of minor actinides fission cross sections by means of transfer reactions

Energy Technology Data Exchange (ETDEWEB)

Jurado, B.; Aiche, M.; Barreau, G.; Boyer, S.; Czajkowski, S.; Dassie, D.; Grosjean, C.; Guiral, A.; Haas, B.; Osmanov, B.; Petit, M. [CENBG - UMR 5795 CNRS/IN2P3-Univ. Bordeaux 1- Le Haut Vigneau, 33175 Gradignan (France); Berthoumieux, E.; Gunsing, F.; Perrot, L.; Theisen, Ch. [CEN Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette cedex (France); Bauge, E. [CEA, SPhN, BP12 91680 Bruyeres-le-Chatel (France); Michel-Sendis, F. [IPN, 15 rue G. Clemenceau, 91406 Orsay cedex (France); Billebaud, A. [LPSC, 53 Avenue des Martyrs, 38026 Grenoble cedex (France); Wilson, J. N. [IPN, 15 rue G. Clemenceau, 91406 Orsay cedex (France); LPSC, 53 Avenue des Martyrs, 38026 Grenoble cedex (France); Ahmad, I.; Greene, J.P.; Janssens, R. V. F. [ANL, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

2005-07-01

We present an original method that allows to determine neutron-induced cross sections of very short-lived minor actinides. This indirect method, based on the use of transfer reactions, has already been applied with success for the determination of the neutron-induced fission and capture cross section of {sup 233}Pa, a key nucleus in the {sup 232}Th - {sup 233}U fuel cycle. A recent experiment using this technique has been performed to determine the neutron-induced fission cross sections of {sup 242,243,244}Cm and {sup 241}Am which are present in the nuclear waste of the current U-Pu fuel cycle. These cross sections are highly relevant for the design of reactors capable to incinerate minor actinides. The first results will be illustrated. (authors)

A Monte Carlo method for nuclear evaporation and fission at intermediate energies

International Nuclear Information System (INIS)

Deppman, A.; Tavares, O.A.P.; Duarte, S.B.; Arruda-Neto, J.D.T.; Goncalves, M.; Likhachev, V.P.; Mesa, J.; Oliveira, E.C. de; Pina, S.R. de; Rodriguez, O.

2003-01-01

We describe a Monte Carlo method to calculate the characteristics of the competition between particle evaporation and nuclear fission processes taking place in the compound nucleus formed after the intranuclear cascade following the absorption of intermediate energy photons by the nucleus. In this version we include not only neutrons, but also protons and alphas as possible evaporating particles. The present method allows the easy inclusion of other evaporating particles, such as deuteron or heavier clusters. Some fissility results are discussed for the target nuclei 237 Np, 238 U and 232 Th

Th{sup 232} (n,2n) Th{sup 231} cross section from threshold to 20.4 Mev

Energy Technology Data Exchange (ETDEWEB)

Butler, J P; Santry, D C

1961-07-01

The excitation curve for the reaction Th{sup 232} (n,2n) Th{sup 231} has been measured by the activation method from the threshold energy, 6.34 Mev, to 20.4 Mev, relative to the known cross section for the S{sup 32} (n, p) P{sup 32} reaction. Monoenergetic neutrons were obtained from the D (d,n) He{sup 3} and T (d,n) He{sup 4} reactions employing a Tandem Van de Graaff accelerator. From threshold to 9.0 Mev, the (n,2n) cross section rises rapidly, reaching its maximum value of 1.88 {+-} 0.09 barns in the region of 9.5 to 11.0 Mev. Above 11.5 Mev the (n,2n) cross section decreases due to competition of the (n,3n) and (n,2nf) reactions and at 20.4 Mev it has a value of 0.22{sub 5} {+-} 0.01{sub 5} barns. (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

QUEIMAP: a computer routine for punctual analysis of a nuclear fuel depletion with accumulation of fission fragments

International Nuclear Information System (INIS)

Couto, R.T.

1990-01-01

QUEIMAP is a computer routine for burnup calculation, composed of five FORTRAN-77 subroutines. Its objective is to solve depletion equation of four radionuclides conversion chain, U238, U235, Th232, as well as fission fragments equations. In this paper the burnup is considered punctual and evolutioned under cross section. It presents the solution algorithms employed by QUEIMAP, the validation of its results and the way of use it. (M.I.)

Measurement of the 232Th neutron capture cross section in the region 5 keV-150 keV

International Nuclear Information System (INIS)

Lobo, Georges; Corvi, Franco; Schillebeeckx, Peter; Brusegan, Antonio; Mutti, Paolo; Janeva, Natalia

2002-01-01

The average capture cross-section of 232 Th has been measured at the 14.37 m flight path of GELINA, IRMM-Geel, in the energy range from 5 to 150 keV. The capture events were detected by two C 6 D 6 liquid scintillators and the neutron flux was measured with a 10 B-loaded ionisation chamber. The data, corrected with the pulse-height weighting technique, have been normalised to the well-isolated and nearly saturated 232 Th (n, γ) resonances at 21.8 eV and 23.5 eV. Below 15 keV neutron energy, we do not observe the discrepancies, up to 40%, with the evaluated ENDF/B-VI data as reported by Wisshak et al.. Between 5 and 80 keV our results are about 10% systematically above the ENDF/B-VI data and approach the evaluated data between 80 and 100 keV. (author)

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

Improved Fission Neutron Data Base for Active Interrogation of Actinides

Energy Technology Data Exchange (ETDEWEB)

Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

2013-11-06

This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

Enhanced emission of high-energy photons perpendicular to the reaction plane in α+Th reactions

International Nuclear Information System (INIS)

Tegner, P.; Marianski, B.; Morsch, H.P.; Rogge, M.; Bargholtz, C.; Decowski, P.; Zemlo, L.

1991-01-01

High-energy photon and neutron emission has been measured in coincidence with fission fragments in α+ 232 Th reactions at 170 MeV. From measurements parallel and perpendicular to the fission plane, anisotropies relative to the reaction plane were determined. The in-plane/out-of-plane intensity ratio is 0.72(7) for photons with energies above 20 MeV and 11(3) for neutrons at 35 MeV. The result for high-energy photons can be explained by nucleon-nucleon bremsstrahlung if the initial flow of nucleons has a correlation to the reaction plane similar to the one observed for fast neutrons

Thorium-uranium fission radiography

Science.gov (United States)

Haines, E. L.; Weiss, J. R.; Burnett, D. S.; Woolum, D. S.

1976-01-01

Results are described for studies designed to develop routine methods for in-situ measurement of the abundance of Th and U on a microscale in heterogeneous samples, especially rocks, using the secondary high-energy neutron flux developed when the 650 MeV proton beam of an accelerator is stopped in a 42 x 42 cm diam Cu cylinder. Irradiations were performed at three different locations in a rabbit tube in the beam stop area, and thick metal foils of Bi, Th, and natural U as well as polished silicate glasses of known U and Th contents were used as targets and were placed in contact with mica which served as a fission track detector. In many cases both bare and Cd-covered detectors were exposed. The exposed mica samples were etched in 48% HF and the fission tracks counted by conventional transmitted light microscopy. Relative fission cross sections are examined, along with absolute Th track production rates, interaction tracks, and a comparison of measured and calculated fission rates. The practicality of fast neutron radiography revealed by experiments to data is discussed primarily for Th/U measurements, and mixtures of other fissionable nuclei are briefly considered.

Experimental data on fission and (n,xn) reactions; Donnees experimentales de fission et de reactions (n,xn)

Energy Technology Data Exchange (ETDEWEB)

Belier, G.; Chatillon, A.; Granier, T.; Laborie, J.M.; Laurent, B.; Ledoux, X.; Taieb, J.; Varignon, C.; Bauge, E.; Bersillon, O.; Aupiais, J.; Le Petit, G. [CEA Bruyeres-le-Chatel, 91 (France); Authier, N.; Casoli, P. [CEA Valduc, 21 - Is-sur-Tille (France)

2011-07-15

Investigations on neutron-induced fission of actinides and the deuteron breakup are presented. Neutron-induced fission has been studied for 10 years at the WNR (Weapons Neutron Research) neutron facility of the Los Alamos Neutron Science Center (LANSCE). Thanks to this white neutron source the evolution of the prompt fission neutron energy spectra as a function of the incident neutron energy has been characterized in a single experiment up to 200 MeV incident energy. For some isotopes the prompt neutron multiplicity has been extracted. These experimental results demonstrated the effect on the mean neutron energy of the neutron emission before scission for energies higher than the neutron binding energy. This extensive program ({sup 235}U and {sup 238}U, {sup 239}Pu, {sup 237}Np and {sup 232}Th were measured) is completed by neutron spectra measurements on the CEA 4 MV accelerator. The D(n,2n) reaction is studied both theoretically and experimentally. The cross-section was calculated for several nucleon-nucleon interactions including the AV18 interaction. It has also been measured on the CEA 7 MV tandem accelerator at incident neutron energies up to 25 MeV. Uncertainties lower than 8% between 5 and 10 MeV were obtained. In particular these experiments have extended the measured domain for cross sections. (authors)

Resonance Region Covariance Analysis Method and New Covariance Data for Th-232, U-233, U-235, U-238, and Pu-239

International Nuclear Information System (INIS)

Leal, Luiz C.; Arbanas, Goran; Derrien, Herve; Wiarda, Dorothea

2008-01-01

Resonance-parameter covariance matrix (RPCM) evaluations in the resolved resonance region were done for 232Th, 233U, 235U, 238U, and 239Pu using the computer code SAMMY. The retroactive approach of the code SAMMY was used to generate the RPCMs for 233U, 235U. RPCMs for 232Th, 238U and 239Pu were generated together with the resonance parameter evaluations. The RPCMs were then converted in the ENDF format using the FILE32 representation. Alternatively, for computer storage reasons, the FILE32 was converted in the FILE33 cross section covariance matrix (CSCM). Both representations were processed using the computer code PUFF-IV. This paper describes the procedures used to generate the RPCM with SAMMY.

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.

Measurements of thermal fission and capture cross sections of minor actinides within the Mini-INCA project

Energy Technology Data Exchange (ETDEWEB)

Bringer, O.; Chabod, S.; Dupont, E.; Letourneau, A.; Panebianco, S.; Veyssiere, Ch. [CEA Saclay, Dept. d' Astrophysique de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, 91- Gif sur Yvette (France); Oriol, L. [CEA Cadarache, Dept. d' Etudes des Reacteurs, 13 - Saint Paul lez Durance (France); Chartier, F. [CEA Saclay, Dept. de Physico-Chimie, 91 - Gif sur Yvette (France); Mutti, P. [Institut Laue Langevin, 38 - Grenoble, (France); AlMahamid, I. [Wadsworth Center, New York State Dept. of Health, Albany, NY (United States)

2008-07-01

In the framework of nuclear waste transmutation studies, the Mini-INCA project has been initiated at Cea/DSM to determine optimal conditions for transmutation and incineration of Minor Actinides in high intensity neutron fluxes in the thermal region. Our experimental tool is based on alpha- and gamma-spectroscopy of irradiated samples and microscopic fission-chambers. It can provide both microscopic information on nuclear reactions (total and partial cross sections for neutron capture and/or fission reactions) and macroscopic information on transmutation and incineration potentials. The {sup 232}Th, {sup 237}Np, {sup 241}Am, and {sup 244}Cm transmutation chains have been explored in details, showing some discrepancies in comparison with evaluated data libraries but in overall good agreement with recent experimental data. (authors)

Measurements of thermal fission and capture cross sections of minor actinides within the Mini-INCA project

International Nuclear Information System (INIS)

Bringer, O.; Chabod, S.; Dupont, E.; Letourneau, A.; Panebianco, S.; Veyssiere, Ch.; Oriol, L.; Chartier, F.; Mutti, P.; AlMahamid, I.

2008-01-01

In the framework of nuclear waste transmutation studies, the Mini-INCA project has been initiated at Cea/DSM to determine optimal conditions for transmutation and incineration of Minor Actinides in high intensity neutron fluxes in the thermal region. Our experimental tool is based on alpha- and gamma-spectroscopy of irradiated samples and microscopic fission-chambers. It can provide both microscopic information on nuclear reactions (total and partial cross sections for neutron capture and/or fission reactions) and macroscopic information on transmutation and incineration potentials. The 232 Th, 237 Np, 241 Am, and 244 Cm transmutation chains have been explored in details, showing some discrepancies in comparison with evaluated data libraries but in overall good agreement with recent experimental data. (authors)

Experimental data on fission and (n,xn) reactions

International Nuclear Information System (INIS)

Belier, G.; Chatillon, A.; Granier, T.; Laborie, J.M.; Laurent, B.; Ledoux, X.; Taieb, J.; Varignon, C.; Bauge, E.; Bersillon, O.; Aupiais, J.; Le Petit, G.; Authier, N.; Casoli, P.

2011-01-01

Investigations on neutron-induced fission of actinides and the deuteron breakup are presented. Neutron-induced fission has been studied for 10 years at the WNR (Weapons Neutron Research) neutron facility of the Los Alamos Neutron Science Center (LANSCE). Thanks to this white neutron source the evolution of the prompt fission neutron energy spectra as a function of the incident neutron energy has been characterized in a single experiment up to 200 MeV incident energy. For some isotopes the prompt neutron multiplicity has been extracted. These experimental results demonstrated the effect on the mean neutron energy of the neutron emission before scission for energies higher than the neutron binding energy. This extensive program ( 235 U and 238 U, 239 Pu, 237 Np and 232 Th were measured) is completed by neutron spectra measurements on the CEA 4 MV accelerator. The D(n,2n) reaction is studied both theoretically and experimentally. The cross-section was calculated for several nucleon-nucleon interactions including the AV18 interaction. It has also been measured on the CEA 7 MV tandem accelerator at incident neutron energies up to 25 MeV. Uncertainties lower than 8% between 5 and 10 MeV were obtained. In particular these experiments have extended the measured domain for cross sections. (authors)

Standard Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission Dosimeters

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 This test method describes two procedures for the measurement of reaction rates by determining the amount of the fission product 140Ba produced by the non-threshold reactions 235U(n,f), 241Am(n,f), and 239Pu(n,f), and by the threshold reactions 238U(n,f), 237Np(n,f), and 232Th(n,f). 1.2 These reactions produce many fission products, among which is 140Ba, having a half-life of 12.752 days. 140Ba emits gamma rays of several energies; however, these are not easily detected in the presence of other fission products. Competing activity from other fission products requires that a chemical separation be employed or that the 140Ba activity be determined indirectly by counting its daughter product 140La. This test method describes both procedure (a), the nondestructive determination of 140Ba by the direct counting of 140La several days after irradiation, and procedure (b), the chemical separation of 140Ba and the subsequent counting of 140Ba or its daughter 140La. 1.3 With suitable techniques, fission neutron fl...

Nuclear-charge polarization at scission in fission from moderately excited light-actinide nuclei

International Nuclear Information System (INIS)

Nishinaka, Ichiro

2009-01-01

Fragment mass yields and the average neutron multiplicity in the proton-induced fission of 232 Th and 238 U were measured by a double time-of-flight method. The most probable charges of secondary fragments were evaluated from the fragment mass yields measured by the double time-of-flight method and the fractional cumulative and independent yields reported in literature. The nuclear-charge polarization of primary fragments at scission was obtained by correcting the most probable charge of secondary fragments for neutron evaporation. The results show that the nuclear-charge polarization at scission is associated with the liquid-drop properties of nuclei and the proton shell effect with Z = 50 of heavy fragments and that it is practically insensitive to mass and excitation energy of the fissioning nucleus in the region of light-actinide nuclei. (author)

Natural radioactivity (226Ra, 232Th and 40K) and assessment of radiological hazards in the Kestanbol granitoid, Turkey.

Science.gov (United States)

Canbaz, Buket; Cam, N Füsun; Yaprak, Günseli; Candan, Osman

2010-09-01

The surveys of natural gamma-emitting radionuclides in rocks and soils from the Ezine plutonic area were conducted during 2007. Direct dose measurement using a survey meter was carried out simultaneously. The present study, which is part of the survey, analysed the activity concentrations of (238)U, (232)Th and (40)K in granitoid samples from all over the region by HPGe gamma spectrometry. The activity concentrations of (226)Ra ranged from 94 to 637 Bq kg(-1), those of (232)Th ranged from 120 to 601 Bq kg(-1)and those of (40)K ranged from 1074 to 1527 Bq kg(-1) in the analysed rock samples from different parts of the pluton. To evaluate the radiological hazard of the natural radioactivity in the samples, the absorbed dose rate (D), the annual effective dose rate, the radium equivalent activity (Ra(eq)) and the external (H(ex)) hazard index were calculated according to the UNSCEAR 2000 report. The thorium-to-uranium concentration ratios were also estimated.

Proton-recoil proportional counter tests at TREAT

International Nuclear Information System (INIS)

Fink, C.L.; Eichholz, J.J.; Burrows, D.R.; DeVolpi, A.

1979-01-01

A methane filled proton-recoil proportional counter will be used as a fission neutron detector in the fast-neutron hodoscope. To provide meaningful fuel-motion information the proportional counter should have: a linear response over a wide range of reactor powers background ratio (the number of high energy neutrons detected must be maximized relative to low energy neutrons, and gamma ray sensitivity must be kept small); and a detector efficiency for fission neutrons above 1 MeV of approximately 1%. In addition, it is desirable that the detector and the associated amplifier/discriminator be capable of operating at counting rates in excess of 500 kHz. This paper reports on tests that were conducted on several proportional counters at the TREAT reactor

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.)

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.

Measurements of Fission Cross Sections of Actinides

CERN Multimedia

Wiescher, M; Cox, J; Dahlfors, M

2002-01-01

A measurement of the neutron induced fission cross sections of $^{237}$Np, $^{241},{243}$Am and of $^{245}$Cm is proposed for the n_TOF neutron beam. Two sets of fission detectors will be used: one based on PPAC counters and another based on a fast ionization chamber (FIC). A total of 5x10$^{18}$ protons are requested for the entire fission measurement campaign.

Crystal blocking measurements of the induced fission time in the sup 2 sup 3 sup 2 Th+p and sup 2 sup 3 sup 2 Th+ sup 3 He reactions

CERN Document Server

Drozdov, V A; Fotina, O V; Giardina, G; Malaguti, F; Platonov, S Y; Tulinov, A F; Yuminov, O A

2002-01-01

The crystal blocking technique has been used to measure the induced fission lifetimes for the sup 2 sup 3 sup 2 sup , sup 2 sup 3 sup 3 Pa and sup 2 sup 3 sup 2 U nuclei produced in the sup 2 sup 3 sup 2 Th+p and sup 2 sup 3 sup 2 Th+ sup 3 He reactions at bombarding energies of protons and sup 3 He included in the 6.8-7.8 MeV and 20.8-23.4 MeV ranges, respectively. The experimental fission lifetimes observed in these reactions vary from 10 sup - sup 1 sup 6 to 10 sup - sup 1 sup 4 s, depending on the projectile energy. Experimental data have been compared with the statistical model calculations that take into account the existence of both classes of excited states of fissioning nucleus, realized in the first and second potential wells of the double-humped fission barrier. By the analysis of the measured decay times it is possible to determine the absolute values of the level density in the second well, type of shape symmetry in the second well, and also the unknown early values of the shell correction for th...

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

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)

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)

Efficiency calibration of solid track spark auto counter

International Nuclear Information System (INIS)

Wang Mei; Wen Zhongwei; Lin Jufang; Liu Rong; Jiang Li; Lu Xinxin; Zhu Tonghua

2008-01-01

The factors influencing detection efficiency of solid track spark auto counter were analyzed, and the best etch condition and parameters of charge were also reconfirmed. With small plate fission ionization chamber, the efficiency of solid track spark auto counter at various experiment assemblies was re-calibrated. The efficiency of solid track spark auto counter at various experimental conditions was obtained. (authors)

Distribution of 226Ra, 232Th, and 40K in soils of Rio Grande do Norte (Brazil)

International Nuclear Information System (INIS)

Malanca, A.; Pessina, V.; Dallara, G.

1996-01-01

A survey programme aimed at studying the environmental radioactivity in the Brazilian state of Rio Grande do Norte was undertaken. Fifty-two soil samples, together with two rock and two uraniferrous ore samples were collected from the eastern and central regions of this state. Concentrations of radioelements in samples were determined by γ-ray spectrometry. The average concentrations of 226 Ra, 232 Th, and 40 K in the surveyed soils were 29.2 ± 19.5 (SD), 47.8 ± 37.3, and 704 ± 437 Bq kg -1 , respectively. Higher values were found in the rock samples. The distributions of 226 Ra and 232 Th were fitted by log-normal curves. Radiological measurements carried out with a portable scintillometer at the sampled sites revealed an average absorbed dose rate of 55 ± 27 (SD) nGy h -1 . Computed dose rates obtained through the Beck formula ranged from 15-179 nGy h -1 , with a mean value of 72.6 ± 38.7 (SD) nGy h -1 , and their distribution fitted a log-normal curve. An annual average effective dose equivalent of 552 μSν (range: 117-1361 μSν) was estimated for 51 sites in Rio Grande do Norte. (author)

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.

STUDY OF NATURAL RADIOACTIVITY (226Ra, 232Th AND 40K) IN SOIL SAMPLES FOR THE ASSESSMENT OF AVERAGE EFFECTIVE DOSE AND RADIATION HAZARDS.

Science.gov (United States)

Bangotra, Pargin; Mehra, Rohit; Kaur, Kirandeep; Jakhu, Rajan

2016-10-01

The activity concentration of 226 Ra (radium), 232 Th (thorium) and 40 K (potassium) has been measured in the soil samples collected from Mansa and Muktsar districts of Punjab (India) using NaI (Tikl) gamma detector. The concentration of three radionuclides ( 226 Ra, 232 Th and 40 K) in the studied area has been varied from 18±4 to 46±5, 53±7 to 98±8 and 248±54 to 756±110 Bq kg -1 , respectively. Radium equivalent activities (Ra eq ) have been calculated in soil samples for the assessment of the radiation hazards arising due to the use of these soil samples. The absorbed dose rate of 226 Ra, 232 Th and 40 K in studied area has been varied from 8 to 21, 33 to 61 and 9 to 25 nGy h -1 , respectively. The corresponding indoor and outdoor annual effective dose in studied area was 0.38 and 0.09 mSv, respectively. The external and internal hazard has been also calculated for the assessment of radiation hazards in the studied area. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

Masses and fission barriers of nuclei in the LSD model

Energy Technology Data Exchange (ETDEWEB)

Pomorski, Krzysztof

2009-07-01

Recently developed Lublin-Strasbourg Drop (LSD) model together with the microscopic corrections taken r is very successful in describing many features of nuclei. In addition to the classical liquid drop model the LSD contains the curvature term proportional to the A{sup 1/3}. The r.m.s. deviation of the LSD binding energies of 2766 isotopes with Z,N>7 from the experimental ones is 0.698 MeV only. It turns out that the LSD model gives also a satisfactory prediction of the fission barrier heights. In addition, it was found in that taking into account the deformation dependence of the congruence energy proposed by Myers and Swiatecki significantly approaches the LSD-model barrier-heights to the experimental data in the case of light isotopes while the fission barriers for heavy nuclei remain nearly unchanged and agree well with experiment. It was also shown in that the saddle point masses of transactinides from {sup 232}Th to {sup 250}Cf evaluated using the LSD differ by less than 0.67 MeV from the experimental data.

CACA-2: revised version of CACA-a heavy isotope and fission-product concentration calculational code for experimental irradiation capsules

International Nuclear Information System (INIS)

Allen, E.J.

1976-02-01

A computer program is described which calculates nuclide concentration histories, power or neutron flux histories, burnups, and fission-product birthrates for fueled experimental capsules subjected to neutron irradiations. Seventeen heavy nuclides in the chain from 232 Th to 242 Pu and a user-specified number of fission products are treated. A fourth-order Runge-Kutta calculational method solves the differential equations for nuclide concentrations as a function of time. For a particular problem, a user-specified number of fuel regions may be treated. A fuel region is described by volume, length, and specific irradiation history. A number of initial fuel compositions may be specified for each fuel region. The irradiation history for each fuel region can be divided into time intervals, and a constant power density or a time-dependent neutron flux is specified for each time interval. Also, an independent cross-section set may be selected for each time interval in each irradiation history. The fission-product birthrates for the first composition of each fuel region are summed to give the total fission-product birthrates for the problem

Comparison of two ultra-sensitive methods for the determination of 232Th by recovery corrected pre-concentration radiochemical neutron activation analysis

International Nuclear Information System (INIS)

Glover, S.E.; Qu, H.; LaMont, S.P.; Grimm, C.A.; Filby, R.H.

2001-01-01

The determination of isotopic thorium by alpha spectrometric methods is a routine practice for bioassay and environmental measurement programs. Alpha-spectrometry has excellent detection limits (by mass) for all isotopes of thorium except 232 Th due to its extremely long half-life. Improvements in the detection limit an sensitivity over previously reported methods of pre-concentration neutron activation analysis (PCNAA) for the recovery corrected, isotopic determination of thorium in various matrices is discussed. Following irradiation, the samples were dissolved, 231 Pa added as a tracer, and Pa isolated by two different methods and compared (extraction chromatography and anion exchange chromatography) followed by alpha spectrometry for recovery correction. Ion exchange chromatography was found to be superior for this application at this time, principally for reliability. The detection limit for 232 Th of 3.5 x 10 -7 Bq is almost three orders of magnitude lower than for alpha spectrometry using the PCRNAA method and one order of magnitude below previously reported PCNAA methods. (author)

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)

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.)

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-08-01

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

Determination of specific activity of 226Ra, 232Th and 40K for assessment of environmental hazards

International Nuclear Information System (INIS)

Al-Haydari, A.; Al Sharabi, E. S. A.; Al Buhairi, M. H.

2012-01-01

Studies have been carried out using gamma-spectrometric techniques to determine the natural radioactivity in some rocks that are used as building materials in Yemen. The concentrations of the natural radionuclides namely 226 Ra, 232 Th and 40 K in the rock samples collected from different rock markets in Yemen have been determined using an NaI(Tl) detector. The concentrations of 226 Ra, 232 Th and 40 K in the studied rock samples range from 22.2 to 88.8 Bq kg -1 , 8.12 to 113.68 Bq kg -1 and 31.3 to 2222.3 Bq kg -1 , respectively. The concentrations of these radionuclides are compared with the typical world values. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, the representative level index and the values of both external and internal hazard indices were evaluated and compared with the internationally approved values. The radium equivalent activity values of all rock samples are lower than the limit of 370 Bq kg -1 except for one sample which is about 413.386. The values of external hazard index (H ex ) and internal hazard index (H in ), absorbed doses in indoor air and the corresponding effective dose equivalents in a typical dwelling are presented. The need for further studies is also discussed. (authors)

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)

Study of the number of neutrons produced by fission of {sup 239}Pu; Etude du nombre de neutrons produits par la fission de {sup 239}Pu

Energy Technology Data Exchange (ETDEWEB)

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

1958-07-01

Study of the number of neutrons produced by fission of {sup 239}Pu. The counting by coincidence of fissions and neutrons produced by these fissions allows the study of the variation of the mean number of neutrons emitted by {nu} fission. In the first chapter, it studied the variation of the mean number of neutrons emitted by {sup 239}Pu fission with the energy of the incident neutron. A description of the experiment is given: a spectrometer with a crystal of sodium chloride or beryllium (mounted on a goniometer) is used, a fission chamber containing 10 mg of {sup 239}Pu and the neutron detection system constituted of BF{sub 3} counters which are enriched in {sup 10}B. In the second part, the counting by coincidence of fissions and neutrons produced by the same fission and received by two different groups of counters allow the determination of a relationship between the root mean square and the average of neutron number produced by fission. The variation of the mean number of neutrons emitted by fission of {sup 239}Pu is studied when we change from a thermal spectra of neutrons to a fission spectra of incident neutrons. Finally, when separating in two different part the fission chamber, it is possible to measure the mean number of neutrons emitted from fission of two different sources. It compared the mean number of neutrons emitted by fission of {sup 239}Pu and {sup 233}U. (M.P.)

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

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)

Fission product yields

International Nuclear Information System (INIS)

Valenta, V.; Hep, J.

1978-01-01

Data are summed up necessary for determining the yields of individual fission products from different fissionable nuclides. Fractional independent yields, cumulative and isobaric yields are presented here for the thermal fission of 235 U, 239 Pu, 241 Pu and for fast fission (approximately 1 MeV) of 235 U, 238 U, 239 Pu, 241 Pu; these values are included into the 5th version of the YIELDS library, supplementing the BIBFP library. A comparison is made of experimental data and possible improvements of calculational methods are suggested. (author)

Evaluated nuclear data file of Th-232

International Nuclear Information System (INIS)

Meadows, J.; Poenitz, W.; Smith, A.; Smith, D.; Whalen, J.; Howerton, R.

1977-09-01

An evaluated nuclear data file for thorium is described. The file extends over the energy range 0.049 (i.e., the inelastic-scattering threshold) to 20.0 MeV and is formulated within the framework of the ENDF system. The input data base, the evaluation procedures and judgments, and ancillary experiments carried out in conjunction with the evaluation are outlined. The file includes: neutron total cross sections, neutron scattering processes, neutron radiative capture cross sections, fission cross sections, (n;2n) and (n;3n) processes, fission properties (e.g., nu-bar and delayed neutron emission) and photon production processes. Regions of uncertainty are pointed out particularly where new measured results would be of value. The file is extended to thermal energies using previously reported resonance evaluations thereby providing a complete file for neutronic calculations. Integral data tests indicated that the file was suitable for neutronic calculations in the MeV range

Study of the sensitivity of integral parameters related to 232 Thorium cross sections

International Nuclear Information System (INIS)

Guimaraes, L.N.F.; Menezes, A.

1986-01-01

The THOR critical assembly is used to test 232 Th basic nuclear data from ENDL-78, ENDF/B-IV, INDL-83, JENDL-1 and JENDL-2. The FORSS and UNISENS systems are used to calculate integral parameters and sensitivity profiles. The results show that 232 Th from JENDL-2 is superior to the others, with ENDL-78 showing the worst performance. The discrepancies can be credited to the different evaluations for the 232 Thorium scattering cross section. (Author) [pt

A preliminary study on 226Ra, 232Th, 40K and 137Cs activity concentrations in vegetables and fruits frequently consumed by inhabitants of Elazig Region, Turkey

International Nuclear Information System (INIS)

Cumhur Canbazoglu; Mahmut Dogru

2013-01-01

Determining radioactivity levels in foodstuffs is of great importance for the protection of human health. In addition, the literature includes few studies related to this subject in Turkey. In this study, gamma spectroscopic system was used in order to measure 226 Ra, 232 Th, 40 K and 137 Cs activity concentrations in vegetables and fruits produced in Elazig( Region. The average activity concentrations in vegetables was calculated as 0.64 ± 0.26 Bq kg -1 for 226 Ra, 0.65 ± 0.14 Bq kg -1 for 232 Th, 13.98 ± 1.22 Bq kg -1 for 40 K, and 0.54 ± 0.04 Bq kg -1 for 137 Cs. The average activity concentrations in fruits were 1.52 ± 0.34, 0.98 ± 0.23, 18.66 ± 1.13 and 0.59 ± 0.16 Bq kg -1 , respectively for 226 Ra, 232 Th, 40 K and 137 Cs. Total committed effective dose value was determined as 20 and 30.55 μSv y -1 , respectively for vegetables and fruits. The findings were compared with previous data reported for Turkey and other regions of the world. (author)

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

Influence of the cosmic-ray induced fission tracks on the fission track of extraterrestric minerals via the 238U spontaneous fission

International Nuclear Information System (INIS)

Damm, G.; Thiel, K.

1977-01-01

The age determined by counting fission tracks of lunar and meteorite materials is obviously falsified by additional fission track parts not to be accounted for by the spontaneous fission of uranium 238. For this p and n induced fissions of U, Th and other hreavy elements through the cosmic radiation come into consideration. In order to determine the possible part of such interference factors, a simulation experiment at the proton synchrocycloton (CERN, Geneva) has been carried out and independently of this, the production rates for the p and n induced U, Th, Bi, Pb and Au in the surface-near regolith layers of the moon were calculated. It could be seen that the irradiation age as well as the spacial distribution of the heavy metals in the samples to be dated must be considered. (RB) [de

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)

Rapid Late Miocene Exhumation in the Central Alps, Constrained by (U-Th)/He and Fission Track Thermochronology

Science.gov (United States)

Aramowicz, A.; Cosca, M.; Stockli, D.; Farley, K.; Seward, D.

2007-12-01

Zircon and apatite (U-Th)/He thermochronological data together with apatite fission track analyses are used to explore uplift and exhumation of the western part of the Aar massif in the central Swiss Alps. A total of 27 samples were collected from the surface and underground, from the world's deepest tunnel (Loetschberg NEAT), with an overall elevation difference of almost 2500 m. Zircon (U-Th)/He ages range from 5.5 to 7.6 Ma, apatite fission track ages range from 5.7 to 6.5 Ma and apatite (U-Th)/He ages range from 3 to 5.5 Ma. All zircon age-elevation profiles from three traverses, show distinct brakes in slope that mark a drastic, 10-fold acceleration of exhumation at 6 ± 0.5 Ma ago (from 0.3 km/Ma to 3 km/Ma). The trend of fast exhumation appears to be maintained in the apatite fission track data while apatite (U-Th)/He ages suggest a return to moderate, apparent exhumation rates of 0.5 km/Ma. We propose that the accelerated exhumation may be linked to the Messinian desiccation of the Mediterranean. During that event, Mediterranean sea level dropped locally by as much as 3 km which accelerated erosion in the Alps. Consequently, the erosion in the Alps must have increased. If wedge mechanics are considered, the increased erosional flux reduced the active width of the orogen and, during latest convergence, deformation focused in the internal parts of the Alps, i.e. Aar massif. This interpretation implies a strong and prompt feedback between external forcing and tectonic response of the orogen. The slower exhumation rate apparent from the apatite (U-Th)/He data may reflect a decline in deformation. Alternatively, due to its low closure temperature, this system is prone to resetting by heat advected through hydrothermal circulation. This scenario needs further investigation but abundant hot-water (ca. 50 °C) discharge in the sampled tunnel is not uncommon.

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

The fission cross section ratios and error analysis for ten thorium, uranium, neptunium and plutonium isotopes at 14.74 MeV neutron energy

International Nuclear Information System (INIS)

Meadows, J.W.

1987-03-01

The error information from the recent measurements of the fission cross section ratios of nine isotopes, 230 Th, 232 Th, 233 U, 234 U, 236 U, 238 U, 237 Np, 239 Pu, and 242 Pu, relative to 235 U at 14.74 MeV neutron energy was used to calculate their correlations. The remaining 36 non-trivial and non-reciprocal cross section ratios and their errors were determined and compared to evaluated (ENDF/B-V) values. There are serious differences but it was concluded that the reduction of three of the evaluated cross sections would remove most of them. The cross sections to be reduced are 230 Th - 13%, 237 Np - 9.6% and 239 Pu - 7.6%. 5 refs., 6 tabs

Optimization of the recoil-shadow projection method for the investigation of short-lived fission isomers

Energy Technology Data Exchange (ETDEWEB)

Helmecke, M.; Thirolf, P.G.; Habs, D.; Gartzke, E.; Kolhinen, V.; Lang, C.; Szerypo, J.; Trepl, L. [Fakultaet f. Physik, LMU Muenchen (Germany); Maier-Leibnitz Laboratory, Garching (Germany)

2009-07-01

Spectroscopic studies of super- and hyperdeformed actinide nuclei offer the possibility to gain insight into the multiple-humped fission barrier landscape. With the identification of deep third minima in {sup 234}U and {sup 236}U the systematics of fission isomers in light actinides was revisited, especially searching for isomers in light uranium isotopes with half-lives in the pico-second range. Using the recoil-shadow projection method and solid state nuclear track detectors, an experimental search for their observation has been started. This well-established detection technique nowadays benefits from an efficient analysis technology based on a PC-controlled auto-focus microscope and a CCD camera together with pattern recognition software. The flatness and the definition of the shadow edge of the target is the critical point of this method: Due to the energy loss of the beam the target carrier foil (1{mu}m Ni) may develop thermal distortions in the {mu}m range, leading to misinterpretations of isomeric fission fragments. Therefore the flatness of the target foil is continuously monitored via a capacitance measurement. First results applying this method to the search of a fission isomer in {sup 234}U via the {sup 232}Th({alpha},2n) reaction are presented.

Study on the technical feasibility of Fission-Track dating at two irradiation positions of the RA-6 research reactor

International Nuclear Information System (INIS)

Dorval, Eric

2005-01-01

The method of Fission-Track dating is based upon the detection of the damage caused by fission fragments from the Uranium contained in geological samples.In order to determine the age of a sample, both the amount of spontaneous fissions occurred and the Uranium concentration must be known.The latter requires the irradiation of the samples inside a reactor with a well-thermalized flux, so that fissions are induced over 235 U targets only. Therefore, the Uranium concentration may be determined.The main inconvenient presented by the irradiation sites at the RA-6 MTR-type reactor is that neutron flux is not completely thermal there, which means that fissions due to epithermal and fast neutrons will not be negligible.In the same way, tracks due to fissions of 238 U and 232 Th will be detected. In order to know the corrections that must be applied to those measurements performed in this reactor, it is necessary to characterize fast flux.Because of it, this laboratory's gamma spectrometry equipment had to be calibrated. After that, several activation detectors were irradiated and results were analyzed. Finally, it was determined that it is feasible to Fission-Track date at the I6 position. However, limitations associated to this method were analyzed for the values of flux measured in the different sites

Thorium-232 in human tissues: Metabolic parameters and radiation doses

International Nuclear Information System (INIS)

Stehney, A.F.

1994-01-01

Higher than environmental levels of 232 Th have been found in autopsy samples of lungs and other organs from four former employees of a Th refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Concentrations of 232 Th in these samples and in tissues from two cases of non-occupational exposure were examined for compatibility with dosimetric models in Publication 30 of the International Commission on Radiological Protection (ICPP 1979a). The concentrations of 232 Th in the lungs of the Th workers relative to the concentrations in bone or liver were much higher than calculated from the model for class Y aerosols of Th and the exposure histories of the subjects, and concentrations in the pulmonary lymph nodes were much lower than calculated for three of the Th workers and both non-occupational cases. Least-squares fits to the measured concentrations showed that the biological half-times of Th in liver, spleen, and kidneys are similar to the half-time in bone instead of the factor of 10 less suggested in Publication 30, and the fractions translocated from body fluids were found to be about 0.03, 0.02, and 0.005, respectively, when the fraction to bone was held at the suggested value of 0.7. Fitted values of the respiratory parameters differed significantly between cases and the differences were ascribable to aerosol differences. Average inhalation rates calculated for individual Th workers ranged from 50 to 110 Bq 232 Th y -1 , and dose equivalents as high as 9.3 Sv to the lungs, 2.0 Sv to bone surfaces, and 1.1 Sv effective dose equivalent were calculated from the inhalation rates and fitted values of the metabolic parameters. The radiation doses were about the same when calculated from parameter values fitted with an assumed translocation fraction of 0.2 from body fluids to bone instead of 0.7

Long-term tissue distribution and steady state activity ratios of 232Th and its daughters in rats after intravascular injection of thorotrast

International Nuclear Information System (INIS)

Norimura, Toshiyuki; Tsuchiya, Takehiko; Hatakeyama, Satoru; Yamamoto, Hisao; Okajima, Shunzo.

1989-01-01

To estimate the absorbed dose in the critical organs of Thorotrast patients, it is necessary to know not only the distribution and concentration of 232 Th but also its daughter nuclides in the body. The present investigation was undertaken in order to clarify the long-term 232 Th tissue distribution and steady state activity ratios between subsequent daughters in the critical tissues, using about 30 Wister male rats, as a basis for estimating absorbed doses. The tissue distribution of thorium was examined by means of an autoradiographty of the whole body and/or the gamma-ray spectrometry at various times during 2 to 24 months following injection. The concentrations of daughter nuclides in tissues were determined by repetitive gamma examination over a period from 1 hr to 35 days after being sacrificed. The data indicate (1) that approximately 90% of injected Thorotrast is retained in the body for a prolonged period, but about 50% of radium and 10% of radon produced from thorium are eliminated from the body, (2) that the mean steady state activity ratios of 224 Ra and 212 Pb to 228 Th for liver are 0.56 and 0.28, and 0.54 and 0.16 for spleen, 0.58 and 0.82 for lungs, respectively, and (3) that the parent 228 Th is translocated to the bone. (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

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)

Assay of fissionable isotopes in aqueous solution by pulsed neutron interrogation

International Nuclear Information System (INIS)

Campbell, P.; Gardy, E.M.; Boase, D.G.

1978-04-01

Non-destructive assay of uranium-235 and thorium-232 in aqueous nitric acid solutions has been accomplished by irradiation with pulses of neutrons from a 14-MeV Cockcroft-Walton neutron generator, and counting of the delayed neutrons emitted from the fissions induced. Design of the delayed neutron detector assemblies is described, together with the neutron pulse timing and counting systems. The effects of irradiation time, counting time, neutron moderation, detector design and sample geometry on the delayed neutron response from uranium-235 and 238 and thorium-232 are discussed. By using polyethylene to moderate the interrogating neutrons, solutions can be analyzed for both uranium-235 and thorium. Comparative analyses with chemical and γ-spectrometric methods show good agreement. The neutron method is rapid and is shown to be unaffected by the presence in solution of impurities such as iron, nickel, chromium, and aluminum. With the experimental equipment described, detection limits of 0.6 mg of 235 U and 9 mg of 232 Th in a sample volume of 25 mL have been achieved. Analyses of highly radioactive samples may be done easily since the measurements are not affected by the presence of large amounts of βγ radiation. Samples can be enclosed in small lead-shielded flasks during analysis to protect the analyst. The potential of the technique to on-line analysis applications is explored briefly. (author)

Molten Salt Fuel Version of Laser Inertial Fusion Fission Energy (LIFE)

International Nuclear Information System (INIS)

Moir, R.W.; Shaw, H.F.; Caro, A.; Kaufman, L.; Latkowski, J.F.; Powers, J.; Turchi, P.A.

2008-01-01

Molten salt with dissolved uranium is being considered for the Laser Inertial Confinement Fusion Fission Energy (LIFE) fission blanket as a backup in case a solid-fuel version cannot meet the performance objectives, for example because of radiation damage of the solid materials. Molten salt is not damaged by radiation and therefore could likely achieve the desired high burnup (>99%) of heavy atoms of 238 U. A perceived disadvantage is the possibility that the circulating molten salt could lend itself to misuse (proliferation) by making separation of fissile material easier than for the solid-fuel case. The molten salt composition being considered is the eutectic mixture of 73 mol% LiF and 27 mol% UF 4 , whose melting point is 490 C. The use of 232 Th as a fuel is also being studied. ( 232 Th does not produce Pu under neutron irradiation.) The temperature of the molten salt would be ∼550 C at the inlet (60 C above the solidus temperature) and ∼650 C at the outlet. Mixtures of U and Th are being considered. To minimize corrosion of structural materials, the molten salt would also contain a small amount (∼1 mol%) of UF 3 . The same beryllium neutron multiplier could be used as in the solid fuel case; alternatively, a liquid lithium or liquid lead multiplier could be used. Insuring that the solubility of Pu 3+ in the melt is not exceeded is a design criterion. To mitigate corrosion of the steel, a refractory coating such as tungsten similar to the first wall facing the fusion source is suggested in the high-neutron-flux regions; and in low-neutron-flux regions, including the piping and heat exchangers, a nickel alloy, Hastelloy, would be used. These material choices parallel those made for the Molten Salt Reactor Experiment (MSRE) at ORNL. The nuclear performance is better than the solid fuel case. At the beginning of life, the tritium breeding ratio is unity and the plutonium plus 233 U production rate is ∼0.6 atoms per 14.1 MeV neutron

Distribution of 137Cs, 90Sr, 239+240Pu, 241Am and 230,232Th on the fractions of natural organic species soils of ChNPP alienation zone

International Nuclear Information System (INIS)

Odintsov, A.A.; Sazhenyuk, A.D.

2003-01-01

The experimental data determination of distribution 137 Cs, 90 Sr, 239+240 Pu, 241 Am 'Chernobyl' releases and 230 , 232 Th on the fraction of humic and fulvic acids sandy- podsolic, meadow and peaty soils taken in the exclusive zone ChNPP are presents. Soils organic matter was isolated by conventional alkali extraction (Turin's method). It was shown that, with depending of soils types 15-45 % 241 Am associate with fulvic acids. In all investigated types of soils 30 - 40 % 239+240 Pu connects with humic acids, as strong complexes. The distribution of environmental 230 , 232 Th and artificial 239+240 Pu on the fraction natural organic species is the same

Study of the number of neutrons produced by fission of 239Pu

International Nuclear Information System (INIS)

Jacob, M.

1958-01-01

Study of the number of neutrons produced by fission of 239 Pu. The counting by coincidence of fissions and neutrons produced by these fissions allows the study of the variation of the mean number of neutrons emitted by ν fission. In the first chapter, it studied the variation of the mean number of neutrons emitted by 239 Pu fission with the energy of the incident neutron. A description of the experiment is given: a spectrometer with a crystal of sodium chloride or beryllium (mounted on a goniometer) is used, a fission chamber containing 10 mg of 239 Pu and the neutron detection system constituted of BF 3 counters which are enriched in 10 B. In the second part, the counting by coincidence of fissions and neutrons produced by the same fission and received by two different groups of counters allow the determination of a relationship between the root mean square and the average of neutron number produced by fission. The variation of the mean number of neutrons emitted by fission of 239 Pu is studied when we change from a thermal spectra of neutrons to a fission spectra of incident neutrons. Finally, when separating in two different part the fission chamber, it is possible to measure the mean number of neutrons emitted from fission of two different sources. It compared the mean number of neutrons emitted by fission of 239 Pu and 233 U. (M.P.)

Ternary particles with extreme N/Z ratios from neutron-induced fission

International Nuclear Information System (INIS)

Koster, U.; Faust, H.; Friedrichs, T.; Oberstedt, S.; Fioni, G.; Grob, M.; Ahmad, I. J.; Devlin, M.; Heinz, A.; Kondev, F. G.; Lauritsen, T.; Sarantites, D. G.; Siem, S.; Sobotka, L. G.; Sonzogni, A.

2000-01-01

The existing ternary fission models can well reproduce the yields of the most abundant light charged particles. However, these models tend to significantly overestimate the yields of ternary particles with an extreme N/Z ratio: 3 He, 11 Li, 14 Be, etc. The experimental yields of these isotopes were investigated with the recoil separator LOHENGRIN down to a level of 10 -10 per fission. Results from the fissioning systems 233 U (n th , f), 235 U(n th ,f), 239 Pu(n th ,f) 241 Pu(n th ,f) and 245 Cm(n th ,f) are presented and the implications for the ternary fission models are discussed

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

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.

Calibration of a special neutron dosemeter based on solid-state track detectors and fission radiators in various neutron fields

International Nuclear Information System (INIS)

Doerschel, B.; Krusche, M.; Schuricht, V.

1980-01-01

The calibration of a personnel neutron dosemeter in different neutron fields is described. The badge-like dosemeter contains 5 detectors: polycarbonate foil (10 μm, Makrofol KG), 232 Th, natural uranium, natural uranium with boron, and natural uranium with cadmium. Detector sensitivity and calibration factors have been calculated and measured in radiation fields of 252 Cf fission neutrons, WWR-S reactor neutrons with and without Cd and Fe shielding, 3-MeV (d,t) generator neutrons, and 238 PuBe neutrons. Measurement range and achievable accuracy are discussed from the point of view of applying the dosemeter in routine and emergency uses

The fission cross section ratios and error analysis for ten thorium, uranium, neptunium and plutonium isotopes at 14. 74 MeV neutron energy

Energy Technology Data Exchange (ETDEWEB)

Meadows, J.W.

1987-03-01

The error information from the recent measurements of the fission cross section ratios of nine isotopes, /sup 230/Th, /sup 232/Th, /sup 233/U, /sup 234/U, /sup 236/U, /sup 238/U, /sup 237/Np, /sup 239/Pu, and /sup 242/Pu, relative to /sup 235/U at 14.74 MeV neutron energy was used to calculate their correlations. The remaining 36 non-trivial and non-reciprocal cross section ratios and their errors were determined and compared to evaluated (ENDF/B-V) values. There are serious differences but it was concluded that the reduction of three of the evaluated cross sections would remove most of them. The cross sections to be reduced are /sup 230/Th - 13%, /sup 237/Np - 9.6% and /sup 239/Pu - 7.6%. 5 refs., 6 tabs.

Assessment of environmental 226Ra, 232Th and 40K concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia

International Nuclear Information System (INIS)

Saleh, Muneer Aziz; Ramli, Ahmad Termizi; Alajerami, Yasser; Aliyu, Abubakar Sadiq

2013-01-01

Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h −1 and 1.169 mSv y −1 , respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of 232 Th, 226 Ra and 40 K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg −1 for 232 Th, 12 ± 1 to 968 ± 27 Bq kg −1 for 226 Ra, and 12 ± 2 to 2450 ± 86 Bq kg −1 for 40 K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg −1 and 70 ± 20 to 4690 ± 90 Bq kg −1 , respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000. -- Highlights: • Assessment of the activities in region of elevated radiation in Segamat District. • The average dose rate found to be six times higher than the world average. • The activity of 232 Th is six times world average. • The activity of 226 Ra is four times and 40 K is lower than world average. • A digital map plotted for isodose

Actualizing of calibration curves of {sup 14}C/C, {sup 90}Sr/Ca, {sup 228}Th/{sup 232}Th in ivory for the determination of the post mortal interval of elephants and consequences of the radiation protection of non-human species; Aktualisierung von Kalibierkurven von {sup 14}C/C, {sup 90}Sr/Ca und {sup 228}Th/{sup 232}Th in Elefantenelfenbein zum Zwecke der Alterbestimmung und die Konsequenzen fuer den Strahlenschutz nicht-menschlicher Arten

Energy Technology Data Exchange (ETDEWEB)

Schupfner, R. [Regensburg Univ. (Germany). ZRN-URA Lab.

2016-07-01

The determination of the activity concentration of the radionuclides {sup 14}C/C and {sup 90}Sr/Ca and {sup 228}Th/{sup 232}Th applying combined radionuclide analyses methods has been proved to be a suitable tool for the purpose of an unambiguous age determination of elephant ivory [1, 2, 3, 10, 11, 12, 13]. Analysing representative and independently dated samples (N = 28) of ivory the curves fitting the post mortal interval (PMI) versus the activity concentration of the radionuclides mentioned above produced the data base enabling a more unambiguous age determination. Data from these studies origin [1, 2, 3, 10, 11, 12, 13] in analyses of ivory samples which were available up to the 2012. During the last five years there was a gap in information of the future trend of {sup 14}C/C and {sup 90}Sr/Ca. Up to this study it was not possible to assess whether the future level of {sup 14}C/C as well as {sup 90}Sr/Ca can analytically be distinguished from the level before 1954. At about 1954 the activity concentration of radionuclides from the atmospheric nuclear explosion, as {sup 14}C and {sup 90}Sr, increased in ivory significantly. This study aims in closing this information gap. The results of analyses of {sup 14}C/C, {sup 90}Sr/Ca, {sup 228}Th/{sup 232}Th in ivory with PMI values ranging from 1 to 5 years are presented and interpreted. These data enable an actualization of the calibration curves of PMI versus specific activities. This is necessary for a better understanding of the effect of blindness of {sup 14}C/C dating and its prevention. On the base of all available results form independent dated ivory sample available up to 2015 a suitable analytical procedure is suggested which aims in a more precise and reliable age determination of elephant tusks. Results of determining of radionuclides {sup 14}C/C and {sup 90}Sr/Ca and {sup 228}Th/{sup 232}Th in ivory are shown from before 1950 to 2015. These results are discussed with respect the purposes of dating as well

4π-spectrometer technique for measurements of secondary neutron average number in nuclear fission by 252Cf neutrons

International Nuclear Information System (INIS)

Vasil'ev, Yu.A.; Barashkov, Yu.A.; Golovanov, O.A.; Sidorov, L.V.

1977-01-01

A method for determining the average number of secondary neutrons anti ν produced in nuclear fission by the neutrons of the 252 Cf fission spectra by means of a 4π time-of-flight spectrometer is described. Layers of 252 Cf and an isotope studied are placed close to each other; if the isotope layer density is 1 mg/cm 2 probability of its fission is about 10 -5 per one spontaneous fission of californium. Fission fragments of 252 Cf and the isotope investigated have been detected by two surface-barrier counters with an efficiency close to 100%. The layers and the counters are situated in a measuring chamber placed in the center of the 4π time-of-flight spectrometer. The latter is utilized as a neutron counter because of its fast response. The method has been verified by carrying out measurements for 235 U and 239 Pu. A comparison of the experimental and calculated results shows that the method suggested can apply to determine the number of secondary neutrons in fission of isotopes that have not been investigated yet

Vertical Profiles Of 226Ra, 232Th And 40K Activities In Rocks From The Irati Formation Of The Paraná Sedimentary Basin, Southern Brazil

Science.gov (United States)

Ferreira, Ademar de O.; Bastos, Rodrigo O.; Appoloni, Carlos R.

2008-08-01

Naturally occurring radioisotopes are present in different concentrations in sedimentary rocks, reflecting the origin of the sediments, the depositional environment, and more recent events such as weathering and erosion. Using a high-resolution γ-ray spectrometry methodology, sedimentary rocks were measured to assess the concentration activities of the natural radioisotopes. The surveyed rocks are from the Irati formation in the Paraná sedimentary basin, which are exposed by an abandoned, open-pit limestone mine, in the city of Sapopema, southern Brazil. The exposed vertical profile is 5 m, and its stratigraphy is represented by an alternation of limestone and bituminous shale (layers being a few decimeters thick), and some millimeter rhythm layers with limestone and bituminous shale laminas. Eleven samples were collected along this profile, each of them dried in the open air during 48 hours, sieved through 4 mm mesh and sealed in cylindrical recipients. Measurements were accomplished using a 66% relative efficiency HPGE detector connected to a standard gamma ray spectrometry electronic chain. The detector efficiency in the range of 60 to 1800 keV was carried out with the certified IAEA-385 sediment sample. The Lower Limit of Detection (LLD) to the system is 2.40 Bqṡkg-1 for 226Ra, 1.84 Bqṡkg-1 for 232Th and 4.20 Bqṡkg-1 for 40K. Activity concentrations were determined for 226Ra (from 16.22 to 151.55 Bqṡkg-1), 232Th (from 2.93 to 56.12 Bqṡkg-1) and 40K (from 38.45 to 644.63 Bqṡkg-1). The layers enriched with organic matter presented the higher values of activity. The measured concentrations of the natural radioisotopes were lower for limestone samples (average values and respective deviations were 22.81±0.22 Bqṡkg-1 for 226Ra, 4.21±0.07 Bqṡkg-1 for 232Th, and 50.11±0.82 Bqṡkg-1 for 40K). Higher concentrations were measured for the bituminous shale samples (average values and respective deviations were 108.10±12.17 Bqṡkg-1 for 226Ra, 43.69�

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.)

Calibration of a low background gas-flow proportional counter to estimate "2"3"4Th activity in coastal waters

International Nuclear Information System (INIS)

Cuesta, E.; Lozano, R.L.; Miguel, E.G. San; Casas-Ruiz, M.; Bolívar, J.P.

2016-01-01

This paper relates the calibration of a low background gas-flow proportional counter. This calibration has been used to determine low activity of "2"3"4Th in coastal water samples. Two methods were used to prepare calibration samples: Evaporation and Electrodeposition. First method was rejected due to the lack of reproducibility because the different geometry adopted by the drops of tracer once dried on the disk. On the contrary, through the second method, similar efficiencies were obtained in all detectors with an average of 0.401±0.004. In this paper, the whole procedure to obtain "2"3"4Th activity in dissolution as well as in particulate matter has been detailed, and all the algorithms needed to calculate activities and efficiencies are shown. Finally, two experiments have been designed in order to validate the calibration of the beta counter and the method to determine "2"3"4Th in coastal waters with high concentration of particulate matter. - Highlights: • This paper shows a Home-made calibration using two methods to prepare calibration samples. • The algorithms needed to obtain Th-234 activity concentrations are described in full detail. • This is the first time Th-234 has been determined in water samples from Huelva Estuary.

Neutron detector for detecting rare events of spontaneous fission

International Nuclear Information System (INIS)

Ter-Akop'yan, G.M.; Popeko, A.G.; Sokol, E.A.; Chelnokov, L.P.; Smirnov, V.I.; Gorshkov, V.A.

1981-01-01

The neutron detector for registering rare events of spontaneous fission by detecting multiple neutron emission is described. The detector represents a block of plexiglas of 550 mm diameter and 700 mm height in the centre of which there is a through 160 mm diameter channel for the sample under investigation. The detector comprises 56 3 He filled counters (up to 7 atm pressure) with 1% CO 2 addition. The counters have a 500 mm length and a 32 mm diameter. The sampling of fission events is realized by an electron system which allows determining the number of detected neutrons, numbers of operated counters, signal amplitude and time for fission event detecting. A block diagram of a neutron detector electron system is presented and its operation principle is considered. For protection against cosmic radiation the detector is surronded by a system of plastic scintillators and placed behind the concrete shield of 6 m thickness. The results of measurements of background radiation are given. It has been found that the background radiation of single neutron constitutes about 150 counts per hour, the detecting efficiency of single neutron equals 0.483 +- 0.005, for a 10l detector sensitive volume. By means of the detector described the parameters of multiplicity distribution of prompt neutrons for 256 Fm spontaneous fission are measured. The average multiplicity equals 3.59+-0.06 the dispersion being 2.30+-0.65

Ternary particles with extreme N/Z ratios from neutron-induced fission

Energy Technology Data Exchange (ETDEWEB)

Koster, U.; Faust, H.; Friedrichs, T.; Oberstedt, S.; Fioni, G.; Grob, M.; Ahmad, I. J.; Devlin, M.; Heinz, A.; Kondev, F. G.; Lauritsen, T.; Sarantites, D. G.; Siem, S.; Sobotka, L. G.; Sonzogni, A.

2000-05-16

The existing ternary fission models can well reproduce the yields of the most abundant light charged particles. However, these models tend to significantly overestimate the yields of ternary particles with an extreme N/Z ratio: {sup 3}He, {sup 11}Li, {sup 14}Be, etc. The experimental yields of these isotopes were investigated with the recoil separator LOHENGRIN down to a level of 10{sup {minus}10} per fission. Results from the fissioning systems {sup 233}U (n{sub th}, f), {sup 235}U(n{sub th},f), {sup 239}Pu(n{sub th},f) {sup 241}Pu(n{sub th},f) and {sup 245}Cm(n{sub th},f) are presented and the implications for the ternary fission models are discussed.

Vertical Profiles Of 226Ra, 232Th And 40K Activities In Rocks From The Irati Formation Of The Parana Sedimentary Basin, Southern Brazil

International Nuclear Information System (INIS)

Ferreira, Ademar de O.; Bastos, Rodrigo O.; Appoloni, Carlos R.

2008-01-01

Naturally occurring radioisotopes are present in different concentrations in sedimentary rocks, reflecting the origin of the sediments, the depositional environment, and more recent events such as weathering and erosion. Using a high-resolution γ-ray spectrometry methodology, sedimentary rocks were measured to assess the concentration activities of the natural radioisotopes. The surveyed rocks are from the Irati formation in the Parana sedimentary basin, which are exposed by an abandoned, open-pit limestone mine, in the city of Sapopema, southern Brazil. The exposed vertical profile is 5 m, and its stratigraphy is represented by an alternation of limestone and bituminous shale (layers being a few decimeters thick), and some millimeter rhythm layers with limestone and bituminous shale laminas. Eleven samples were collected along this profile, each of them dried in the open air during 48 hours, sieved through 4 mm mesh and sealed in cylindrical recipients. Measurements were accomplished using a 66% relative efficiency HPGE detector connected to a standard gamma ray spectrometry electronic chain. The detector efficiency in the range of 60 to 1800 keV was carried out with the certified IAEA-385 sediment sample. The Lower Limit of Detection (LLD) to the system is 2.40 Bq·kg -1 for 226 Ra, 1.84 Bq·kg -1 for 232 Th and 4.20 Bq·kg -1 for 40 K. Activity concentrations were determined for 226 Ra (from 16.22 to 151.55 Bq·kg -1 ), 232 Th (from 2.93 to 56.12 Bq·kg -1 ) and 40 K (from 38.45 to 644.63 Bq·kg -1 ). The layers enriched with organic matter presented the higher values of activity. The measured concentrations of the natural radioisotopes were lower for limestone samples (average values and respective deviations were 22.81±0.22 Bq·kg -1 for 226 Ra, 4.21±0.07 Bq·kg -1 for 232 Th, and 50.11±0.82 Bq·kg -1 for 40 K). Higher concentrations were measured for the bituminous shale samples (average values and respective deviations were 108.10±12.17 Bq·kg -1 for

Energy and angular distributions of neutrons from 252Cf spontaneous fission

International Nuclear Information System (INIS)

Vasil'ev, Yu.A.; Sidorov, L.V.; Vasil'eva, N.K.

1982-01-01

Some results from a first series of measurements of energy and angular distributions of neutrons from 252 Cf spontaneous fission using a spectrometer with high neutron detection efficiency, i.e. a 4π neutron time-of-flight spectrometer, were already presented. Subsequently, a second series of measurements was performed using a more sophisticated technique. For this second series, we used a more intense 252 Cf layer (25,000 spontaneous fissions per second). The angular resolution was improved by a factor of 2-3 by combining the hexahedral counter modules, placed at the same angle with respect to the direction of motion of the fragments, in new panoramic counters. The neutron counters were calibrated against the average 252 Cf neutron spectrum at several positions of the axis of the fragment detector with respect to the neutron counters. In the spectrum measurements and calibration work, the scattered neutron background was not determined theoretically, as in the first series of measurements, but experimentally using four extra scintillation counters with scatter cones; the counters were set up at 60 deg., 80 deg., 100 deg., and 120 deg. to the direction of separation of the fragments

Experiments on iron shield transmission of quasi-monoenergetic neutrons generated by 43- and 68-MeV protons via the 7Li(p,n) reaction

International Nuclear Information System (INIS)

Nakashima, Hiroshi; Tanaka, Shun-ichi; Nakao, Noriaki

1996-03-01

In order to provide benchmark data of neutrons transmitted through iron shields in the intermediate-energy region, spatial distributions of neutron energy spectra and reaction rates behind and inside the iron shields of thickness up to 130 cm were measured for 43- and 68-MeVp- 7 Li neutrons using a quasi-monoenergetic neutron beam source at the 90-MV AVF cyclotron facility of the TLARA facility in JAERI. The measured data by five kinds of detectors: the BC501A detector, the Bonner ball counter, 238 U and 232 Th fission counters, 7 LiF and nat LiF TLDs and solid state nuclear track detector, are numerically provided in this report in the energy region between 10 -4 eV and the energy of peak neutrons generated by the 7 Li(p,n) reaction. (author)

Measurement of the 232Th capture cross section in the energy region 5 keV-150 keV

International Nuclear Information System (INIS)

Lobo, G.; Schillebeeckx, P.; Brusegan, A.; Borella, A.; Corvi, F.; Janeva, N.; Volev, K.

2003-01-01

The 232 Th(n,γ) neutron capture cross-section is of great importance for accelerator driven reactor (ADS) systems based on the Thorium-Uranium fuel cycle. An analysis of the required nuclear data, reveals that the status of the 232 Th capture data is far from the requested 2 % uncertainty level. Recently 232 Th average capture measurements, between 5-200 keV neutron energy, were performed at the FzK Karlsruhe (DE). A comparison of the measured averaged capture cross section with the evaluated data files shows a reasonable agreement in the neutron energy range above 15 keV. However, discrepancies of up to 40 % at lower neutron energies are observed. The same order of discrepancies is observed when comparing their results with the results obtained by Macklin et al. at ORELA. To clarify these discrepancies we measured at IRMM the average capture cross-section at the GEel LINear Accelerator (GELINA). The measurements were performed at a 14.37 m flight-path using the Time-Of-Flight (TOF) method. The gamma rays, originating from the 232 Th(n,γ) reaction, were detected by a pair of C 6 D 6 -based liquid scintillators applying a pulse-height weighting method. The neutron flux was measured with an ionisation chamber placed at 80 cm before the Thorium sample. This chamber has a cathode loaded with two back-to-back layers of about 40 μg/cm 2 10 B. The sample consisted of a metallic natural thorium disc of 8 cm diameter and 0.5 mm thick, corresponding to a thickness of 1.588 10 -3 at/b. The background for the capture measurements consists of a time independent and time dependent component. The former, mainly produced by the radioactive decay of the sample, was deduced from measurements with a closed beam. The latter was measured by replacing the thorium sample with a 0.5 mm thick 208 Pb sample of the same size. Such a Pb sample has practically the same scattering probability as the thorium sample and has a negligible capture yield. Therefore, the 208 Pb run provides a good

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)

Measurement of mass and isotopic fission yields for heavy fission products with the LOHENGRIN mass spectrometer

International Nuclear Information System (INIS)

Bail, A.

2009-05-01

In spite of the huge amount of fission yield data available in different libraries, more accurate values are still needed for nuclear energy applications and to improve our understanding of the fission process. Thus measurements of fission yields were performed at the mass spectrometer Lohengrin at the Institut Laue-Langevin in Grenoble, France. The mass separator Lohengrin is situated at the research reactor of the institute and permits the placement of an actinide layer in a high thermal neutron flux. It separates fragments according to their atomic mass, kinetic energy and ionic charge state by the action of magnetic and electric fields. Coupled to a high resolution ionization chamber the experiment was used to investigate the mass and isotopic yields of the light mass region. Almost all fission yields of isotopes from Th to Cf have been measured at Lohengrin with this method. To complete and improve the nuclear data libraries, these measurements have been extended in this work to the heavy mass region for the reactions 235 U(n th ,f), 239 Pu(n th ,f) and 241 Pu(n th ,f). For these higher masses an isotopic separation is no longer possible. So, a new method was undertaken with the reaction 239 Pu(n th ,f) to determine the isotopic yields by spectrometry. These experiments have allowed to reduce considerably the uncertainties. Moreover the ionic charge state and kinetic energy distributions were specifically studied and have shown, among others, nanosecond isomers for some masses. (author)

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

Analysis of 226Ra, 232Th 40К and 137Cs in samples of soil from some areas of Republic of Macedonia by using gamma spectrometry

Directory of Open Access Journals (Sweden)

Todorovik Aleksandra

2012-01-01

Full Text Available Taking into consideration the importance of the distribution and transfer of radio nuclides in soil, an attempt was made in this work to determine the concentration of 226Ra, 232Th 40К and 137Cs in the same. The concentrations of activity in the gamma-absorbed dose rates of the terrestrial naturally occurring radio nuclides, as follows, 226Ra, 232Th and 40K were determined in samples of soil collected from some parts of Republic of Macedonia, i.e. from three major cities in the Republic of Macedonia. The samples are taken by means of a special dosage dispenser which enables sampling of samples at a depth of 0-5 cm, 5-10cm and 10-15cm, thus disabling the sampling above these layers of soil. An identification of radio nuclides and assessment of their activity has been performed by applying gamma spectrometry. The time of counting for each sample was 65000 s. in order to obtain statistically small mistake. The spectrums were analyzed by a commercially available software GENIE-2000 received from Canberra, Austria. The activity of soil had wide range of values: 20.3 to 82.9 Bq kg-1for 226Ra, 16.1 to 82.5 Bq kg-1 for 232Th, 325 to 799.0 Bq kg-1for 40К and 9.1 to 24.3 Bq kg-1for 137Cs, respectively. The concentrations of these radio nuclides have been compared with the available data from the other countries. Natural environmental radioactivity and the associated external exposure due to gamma radiation depend primarily on the geological and geographical conditions. Namely, the specific levels of terrestrial environmental radiation are related to the type of rocks from which the soils originate. The obtained data indicate that the average value of activity of 232Th is about higher than the one of 226Ra The concentration of activity of 40К in the soil has greater value than 32Th and 226Ra in all soils. The causes for the existence of 137Cs in these soils are the nuclear explosions, waste radioactive materials and other incidents. It reaches the

Preliminary assessment of a symbiotic fusion--fission power system using the TH/U refresh fuel cycle

International Nuclear Information System (INIS)

Bender, D.J.; Lee, J.D.; Moir, R.W.

1977-10-01

Studies of the mirror hybrid reactor by LLL/GA have concluded that the most promising role for this reactor concept is that of a producer of fissile fuel for fission reactors. Studies to date have examined primarily the U/Pu fuel cycle with light-water reactors serving as the consumers of the hybrid-bred fissile fuel; the specific scenarios examined required reprocessing and refabrication of the bred fuel before introduction into the fission reactor. This combination of technologies was chosen to illustrate the manner in which the hybrid reactor concept could serve the needs of, and use the technology of, the fission reactor industry as it now exists (and as it was thought it would evolve). However, the current U.S. Administration has expressed strong concerns about proliferation of nuclear weapons capability and terrorist diversion of weapons-grade nuclear materials. These concerns are based on the projected technology for the light-water reactor/fast breeder reactor using the U/Pu fuel cycle and extensive reprocessing/refabrication. A symbiotic nuclear power generation concept (hybrid fissile producer plus fission burner reactors) is described which eliminates those aspects of the present nuclear fuel cycle that (may) represent significant proliferation/diversion risks. Specifically, the proposed concept incorporates the following features: (1)Th/U 233 fuel cycle, (2) no reprocessing or fabrication of fissile material, and (3) no fissile material in a weapons-grade state

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}.

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.)

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)

40 years of nuclear fission

International Nuclear Information System (INIS)

Koch, H.

1979-01-01

On the occasion of both the 100th birthday of the discoverer of nuclear fission, Otto Hahn, and the 40th anniversary of this outstanding scientific discovery the historical development is described, which led to nuclear fission. Aspects of scientific life in Berlin and in the whole world at that time are presented, and relations between scientists are characterized by quotations. In particular, stress is laid on the life and activities of Otto Hahn as a human being and as a scientist, and his outstanding scientific achievements are appreciated. (author)

Solid state track recorder measurements in the poolside critical assembly

International Nuclear Information System (INIS)

Ruddy, F.H.; Gold, R.; Roberts, J.H.

1979-01-01

Fission rate measurements using solid state track recorders (SSTR) have been performed at the PCA. A schematic representation of a cross-section of the PCA is shown. Fission rates were measured in the pressure vessel simulator at the T/4, T/2 and 3T/4 positions and in the void box (VB). SSTR measurements were carried out with 232 Th, 235 U (bare and cadmium covered), 238 U and 237 Np fissionable deposits. Midplane only measurements were carried out for 235 U and 237 Np, while 5 axial locations at 1/4T and 1/2T and 3 axial locations at 3/4T and in the VB were sampled for 232 Th and 238 U. The HEDL SSTR fission rate measurements reported herein for both configurations together with NBS and CEN/SCK fission chamber measurements will be used to establish absolute and relative fission reaction rates, and ratios for the PCA pressure vessel Benchmark Facility

Coupling of mass and charge distributions for low excited nuclear fission

International Nuclear Information System (INIS)

Salamatin, V.S.; )

2000-01-01

The simple model for calculation of charge distributions of fission fragments for low exited nuclear fission from experimental mass distributions is offered. The model contains two parameters, determining amplitude of even-odd effect of charge distributions and its dependence on excitation energy. Results for reactions 233 U(n th ,f), 235 U(n th ,f), 229 Th(n th ,f), 249 Cf(n th ,f) are spent [ru

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)

Investigation of exotic fission modes

International Nuclear Information System (INIS)

Poenaru, D. N.; Gherghescu, R. A.; Greiner, W.; Nagame, Y.; Hamilton, J. H.; Ramayya, A. V.

2002-01-01

Fission approach to the cluster radioactivities and α-decay has been systematically developed during the last two decades. A more complex process, the ternary fission, was observed since 1946 both in neutron-induced and spontaneous fission. We obtained interesting results concerning the binary fission saddle-point reflection asymmetric nuclear shapes, and we can explain how a possible nuclear quasimolecular state is formed during the 10 Be accompanied cold fission of 252 Cf. The equilibrium nuclear shapes in fission theory are usually determined by minimizing the deformation energy for a given surface equation. We developed a method allowing to obtain a very general saddle-point shape as a solution of a differential equation without an a priori introduction of a shape parametrization. In the approach based on a liquid drop model (LDM), saddle-point shapes are always reflection symmetric: the deformation energy increases with the mass-asymmetry parameter η = (A 1 - A 2 )/(A 1 + A 2 ). By adding the shell corrections to the LDM deformation energy, we obtained minima at a finite mass asymmetry for parent nuclei 238 U, 232,228 Th in agreement with experiments. This correction was calculated phenomenologically. A technique based on the fragment identification by using triple γ coincidences in the large arrays of Ge-detectors, like GAMMASPHERE, was employed at Vanderbilt University to discover new characteristics of the fission process, and new decay modes. The possibility of a whole family of new decay modes, the multicluster accompanied fission, was envisaged. Besides the fission into two or three fragments, a heavy or superheavy nucleus spontaneously breaks into four, five or six nuclei of which two are asymmetric or symmetric heavy fragments and the others are light clusters, e.g. α-particles, 10 Be, 14 C, or combinations of them. Examples were presented for the two-, three- and four cluster accompanied cold fission of 252 Cf and 262 Rf, in which the emitted

Retention of fission products in air filters

International Nuclear Information System (INIS)

Sobnack, R.

1986-01-01

The plume from the Chernobyl nuclear reactor reached London in the morning of 1st May. Less than two weeks later, the Physics Department, University of Surrey, reported a measurable level of radioactivity in air filters. On 15th May air filters from within the air conditioning plant of the Radioisotope Department at the London Hospital were removed for radiation checks. Crude tests with a geiger counter gave readings of 5-10 times higher than background levels. Gamma-ray spectroscopy of the departmental air filters (AF1) using a 127 mm NaI detector revealed a pattern characteristic of emissions of fission products from a nuclear reactor. Another air filter (AF2), from the home of a member of staff, was much less active. Because of the complexity of the gamma-ray spectrum and the relatively high level of emission from the departmental air filter, a thorough investigation was carried out using a high purity germanium detector. (author)

Experiments on iron shield transmission of quasi-monoenergetic neutrons generated by 43- and 68-MeV protons via the {sup 7}Li(p,n) reaction

Energy Technology Data Exchange (ETDEWEB)

Nakashima, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Tanaka, Shun-ichi; Nakao, Noriaki [and others

1996-03-01

In order to provide benchmark data of neutrons transmitted through iron shields in the intermediate-energy region, spatial distributions of neutron energy spectra and reaction rates behind and inside the iron shields of thickness up to 130 cm were measured for 43- and 68-MeVp-{sup 7}Li neutrons using a quasi-monoenergetic neutron beam source at the 90-MV AVF cyclotron facility of the TLARA facility in JAERI. The measured data by five kinds of detectors: the BC501A detector, the Bonner ball counter, {sup 238}U and {sup 232}Th fission counters, {sup 7}LiF and {sup nat}LiF TLDs and solid state nuclear track detector, are numerically provided in this report in the energy region between 10{sup -4} eV and the energy of peak neutrons generated by the {sup 7}Li(p,n) reaction. (author).

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.

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)

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)

Measurement and Analysis of Specific Activities of Natural Radionuclides (40K, 226Ra and 232Th) in Beach Sand Samples from Talo Kapo Beach of Yaring District in Pattani Province using Gamma Ray Spectrometry

Science.gov (United States)

Daoh, M.; Masae, R. N.; Po-oh, S.; Boonkrongcheep; Kessaratikoon, P.

2017-09-01

The Specific Activities of 40K, 226Ra and 232Th were studied and determinate for 30 beach sand samples collected from Talo Kapo beach of Yaring district in Pattani province. Experimental results were obtained by using a high-purity germanium (HPGe) detector and gamma spectrometry analysis system. The IAEA-SOIL-6 reference materials obtained from the International Atomic Energy Agency were also used to analyze and compute the 40K, 226Ra and 232Th specific activity in all 30 beach sand samples. The measuring time of each sample is 10,000 seconds. It was found that specific activity range from 1805.37 - 3323.05, 40.96 - 2137.36 38.63 - 4329.28 Bq/kg for with mean values of 2242.79 ± 117.40, 250.18 ± 8.21 and 458.42 ± 7.68 Bq/kg for 40K, 226Ra and 232Th, respectively. Moreover, the results were also compared with research data in the south of Thailand, the Office of Atoms for Peace (OAP) annual report data and the recommended values which were proposed by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR,)

Bases for calibration of whole body counters using anthropomorphic physical simulators

International Nuclear Information System (INIS)

Dantas, Bernardo Maranhao

1998-01-01

The quantification of radionuclides in the human body can be carried out through in vivo measurements performed in facilities generically called whole body counters. The calibration of such units is usually done by using physical anthropomorphic phantoms, which can be defined as artificial structures with geometrical characteristics and attenuation properties similar to the living tissues. This work presents the development of the phantoms necessary to the monitoring of the internal contamination by the radionuclides manipulated in Brazil. It also presents the procedures for the calibration of the detectors used for the in vivo measurements. The developed phantoms are applied in the determination of radionuclides deposited in specific organs, such as Th-232 and Am-241 in the lungs and skull, isotopes of iodine in the thyroid and photon emitters in the energy range from 100 to 3000 keV in the whole body. (author)

Neutron scattering studies in the actinide region

International Nuclear Information System (INIS)

Beghian, L.E.; Kegel, G.H.R.

1991-08-01

During the report period we have investigated the following areas: Neutron elastic and inelastic scattering measurements on 14 N, 181 Ta, 232 Th, 238 U and 239 Pu; Prompt fission spectra for 232 Th, 235 U, 238 U and 239 Pu; Theoretical studies of neutron scattering; Neutron filters; New detector systems; and Upgrading of neutron target assembly, data acquisition system, and accelerator/beam-line apparatus

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

Fission product behaviour in severe accidents

International Nuclear Information System (INIS)

Jokiniemi, J.; Auvinen, A.; Maekynen, J.; Valmari, T.

1998-01-01

The understanding of fission product (FP) behaviour in severe accidents is important for source term assessment and accident mitigation measures. For example in accident management the operator needs to know the effect of different actions on the behaviour and release of fission products. At VTT fission product behaviour have been studied in different national and international projects. In this presentation the results of projects in EU funded 4th framework programme Nuclear Fission Safety 1994-1998 are reported. The projects are: fission product vapour/aerosol chemistry in the primary circuit (FI4SCT960020), aerosol physics in containment (FI4SCT950016), revaporisation of test samples from Phebus fission products (FI4SCT960019) and assessment of models for fission product revaporisation (FI4SCT960044). Also results from the national project 'aerosol experiments in the Victoria facility' funded by IVO PE and VTT Energy are reported

Comparison of 252Cf time correlated induced fission with AmLi induced fission on fresh MTR reserach reactor fuel

Energy Technology Data Exchange (ETDEWEB)

Joshi, Jay Prakash [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-05-01

The objectives of this project are to calibrate the Advanced Experimental Fuel Counter (AEFC), benchmark MCNP simulations using experimental results, investigate the effects of change in fuel assembly geometry, and finally to show the boost in doubles count rates with 252Cf active soruces due to the time correlated induced fission (TCIF) effect.

Investigations by gamma spectrometry and histoaudiography of the biokinetics of colloidal 232ThO2 ('Thorotrast')

International Nuclear Information System (INIS)

Foell, U.

1978-01-01

Experiments were carried out in mice in order to determine activity ratios and distribution kinetics of ThO 2 and its decay products. The data will be used as a basic for dose calculations. In supplementary investigations, the microdistribution, localisation, and quantitative enrichment of thorotrast were determined in order to provide a basis for microdosimetric evaluation of late thorotrast lesions. The radioactive colloid was injected intravenously into the tail vein of the animals (25 to 250 μl). Whole-body activity was measured at regular intervals. The animals were killed at different times after incorporation, and their livers, spleens, and skeleton without bone marrow were investigated by gammy spectrometry and histoautoradiography. With the findings obtained for the macroscopic distribution of colloid 232 ThO 2 and its decay products on the cellular level as a function of the duration of thorotrast storage, the mean radiation exposure of RHS organs can be determined and at least the order of magnitude of the local dose can be estimated. It will require long-term animal experiments to determine the biological effects of thorotrast incorporation and correlate them with the results of these dose calculations on the basis of the studies on thorotrast biokinetics. (orig./MG) [de

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...

Energy partition in nuclear fission

International Nuclear Information System (INIS)

Ruben, A.; Maerten, H.; Seeliger, D.

1990-01-01

A scission point model (two spheroid model TSM) including semi-empirical temperature-dependent shell correction energies for deformed fragments at scission is presented. It has been used to describe the mass-asymmetry-dependent partition of the total energy release on both fragments from spontaneous and induced fission. Characteristic trends of experimental fragment energy and neutron multiplicity data as function of incidence energy in the Th-Cf region of fissioning nuclei are well reproduced. Based on model applications, information on the energy dissipated during the descent from second saddle of fission barrier to scission point have been deduced. (author). 39 refs, 13 figs

Some aspects of the use of proton recoil proportional counters for fast neutron personnel dosimeters

International Nuclear Information System (INIS)

Yule, T.J.; Bennett, E.F.

1984-01-01

Gas-filled proton recoil proportional counters have been used extensively for the measurement of neutron spectra in degraded fission-spectrum environments. Some considerations relating to the use of these counters for personnel dosimetry are here described. High sensitivity and good accuracy in the determination of dose-equivalent can be obtained if relatively high pressure hydrogen-filled proportional counters are used as the active element in a dosimeter system

Fission yield measurements at IGISOL

Science.gov (United States)

Lantz, M.; Al-Adili, A.; Gorelov, D.; Jokinen, A.; Kolhinen, V. S.; Mattera, A.; Moore, I.; Penttilä, H.; Pomp, S.; Prokofiev, A. V.; Rakopoulos, V.; Rinta-Antila, S.; Simutkin, V.; Solders, A.

2016-06-01

The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL) technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure relative independent fission yields. In some cases it is even possible to resolve isomeric states from the ground state, permitting measurements of isomeric yield ratios. So far the reactions U(p,f) and Th(p,f) have been studied using the IGISOL-JYFLTRAP facility. Recently, a neutron converter target has been developed utilizing the Be(p,xn) reaction. We here present the IGISOL-technique for fission yield measurements and some of the results from the measurements on proton induced fission. We also present the development of the neutron converter target, the characterization of the neutron field and the first tests with neutron-induced fission.

Fission yield measurements at IGISOL

Directory of Open Access Journals (Sweden)

Lantz M.

2016-01-01

Full Text Available The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure relative independent fission yields. In some cases it is even possible to resolve isomeric states from the ground state, permitting measurements of isomeric yield ratios. So far the reactions U(p,f and Th(p,f have been studied using the IGISOL-JYFLTRAP facility. Recently, a neutron converter target has been developed utilizing the Be(p,xn reaction. We here present the IGISOL-technique for fission yield measurements and some of the results from the measurements on proton induced fission. We also present the development of the neutron converter target, the characterization of the neutron field and the first tests with neutron-induced fission.

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)

Intermediate energy nuclear fission

International Nuclear Information System (INIS)

Hylten, G.

1982-01-01

Nuclear fission has been investigated with the double-kinetic-energy method using silicon surface barrier detectors. Fragment energy correlation measurements have been made for U, Th and Bi with bremsstrahlung of 600 MeV maximum energy. Distributions of kinetic energy as a function of fragment mass are presented. The results are compared with earlier photofission data and in the case of bismuth, with calculations based on the liquid drop model. The binary fission process in U, Yb, Tb, Ce, La, Sb, Ag and Y induced by 600 MeV protons has been investigated yielding fission cross sections, fragment kinetic energies, angular correlations and mass distributions. Fission-spallation competition calculations are used to deduce values of macroscopic fission barrier heights and nuclear level density parameter values at deformations corresponding to the saddle point shapes. We find macroscopic fission barriers lower than those predicted by macroscopic theories. No indication is found of the Businaro Gallone limit expected to occur somewhere in the mass range A = 100 to A = 140. For Ce and La asymmetric mass distributions similar to those in the actinide region are found. A method is described for the analysis of angular correlations between complementary fission products. The description is mainly concerned with fission induced by medium-energy protons but is applicable also to other projectiles and energies. It is shown that the momentum and excitation energy distributions of cascade residuals leading to fission can be extracted. (Author)

Progress in fission product nuclear data. No. 14

International Nuclear Information System (INIS)

Lammer, M.

1994-06-01

This is the 14th issue of a report series on Fission Product Nuclear Data published by the Nuclear Data Section of the IAEA. The types of activities included are measurements, compilations and evaluations of fission product yields, neutron reaction cross sections of fission products, data related to the radioactive decay of fission products, delayed neutron data from neutron induced and spontaneous fission, lumped fission product data. The first part of the report consists of unaltered original contributions which the authors have sent to IAEA/NDS. The second part contains some recent references relative to fission product nuclear data, which were not covered by the contributions submitted, and selected papers from conferences. The third part contains requirements for further measurements

Progress in fission product nuclear data. No. 13

International Nuclear Information System (INIS)

Lammer, M.

1990-11-01

This is the 13th issue of a report series published by the Nuclear Data Section of the IAEA. The types of activities included are measurements, compilations and evaluations of: Fission product yields (neutron induced and spontaneous fission), neutron reaction cross-sections of fission products, data related to the radioactive decay of fission products, delayed neutron data of fission products and bumped fission product data (decay heat, absorption, etc.). The first part of the report consists of unaltered original data which the authors have sent to IAEA/NDS. The second part contains some recent references relative to fission product nuclear data, which were not covered by the contributions submitted, and selected papers from conferences. Part 3 contains requirements for further measurements

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

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)

Actualizing of calibration curves of "1"4C/C, "9"0Sr/Ca, "2"2"8Th/"2"3"2Th in ivory for the determination of the post mortal interval of elephants and consequences of the radiation protection of non-human species

International Nuclear Information System (INIS)

Schupfner, R.

2016-01-01

The determination of the activity concentration of the radionuclides "1"4C/C and "9"0Sr/Ca and "2"2"8Th/"2"3"2Th applying combined radionuclide analyses methods has been proved to be a suitable tool for the purpose of an unambiguous age determination of elephant ivory [1, 2, 3, 10, 11, 12, 13]. Analysing representative and independently dated samples (N = 28) of ivory the curves fitting the post mortal interval (PMI) versus the activity concentration of the radionuclides mentioned above produced the data base enabling a more unambiguous age determination. Data from these studies origin [1, 2, 3, 10, 11, 12, 13] in analyses of ivory samples which were available up to the 2012. During the last five years there was a gap in information of the future trend of "1"4C/C and "9"0Sr/Ca. Up to this study it was not possible to assess whether the future level of "1"4C/C as well as "9"0Sr/Ca can analytically be distinguished from the level before 1954. At about 1954 the activity concentration of radionuclides from the atmospheric nuclear explosion, as "1"4C and "9"0Sr, increased in ivory significantly. This study aims in closing this information gap. The results of analyses of "1"4C/C, "9"0Sr/Ca, "2"2"8Th/"2"3"2Th in ivory with PMI values ranging from 1 to 5 years are presented and interpreted. These data enable an actualization of the calibration curves of PMI versus specific activities. This is necessary for a better understanding of the effect of blindness of "1"4C/C dating and its prevention. On the base of all available results form independent dated ivory sample available up to 2015 a suitable analytical procedure is suggested which aims in a more precise and reliable age determination of elephant tusks. Results of determining of radionuclides "1"4C/C and "9"0Sr/Ca and "2"2"8Th/"2"3"2Th in ivory are shown from before 1950 to 2015. These results are discussed with respect the purposes of dating as well as their significance to the radiation protection of nonhuman species.

The spark counting of etched fission-fragment tracks in polycarbonate for a personal neutron dosimetry system

International Nuclear Information System (INIS)

Harrison, K.G.; Hancock, I.B.; Holt, P.D.; Wylie, J.W.

1977-10-01

A new type of personal neutron dosimeter, in which neutron-induced fissions in a thin 237 Np foil are detected by a polycarbonate track-detector, is under development at Harwell for use in a nuclear-fuel reprocessing plant. As part of the development programme, an experimental dosimeter, etching facility and spark counter have been used to study the spark-counting method for counting fission-fragment tracks in polycarbonate. Emphasis has been placed on developing operating procedures for the counter consistent with good overall reproducibility. Existing methods for the optimizing and testing of spark counters is briefly reviewed and a practical operational testing procedure is devised. The optimized system is found to be relatively foolproof in operation and gives good results in unskilled use as well as under carefully-controlled laboratory conditions. (author)

Conversion of highly enriched uranium in thorium-232 based oxide fuel for light water reactors: MOX-T fuel

Energy Technology Data Exchange (ETDEWEB)

Vapirev, E I; Jordanov, T; Christoskov, I [Sofia Univ. (Bulgaria). Fizicheski Fakultet

1994-12-31

The idea of conversion of highly enriched uranium (HEU) from warheads without mixing it with natural uranium as well as the utilization of plutonium as fuel component is discussed. A nuclear fuel which is a mixture of 4% {sup 235}U (HEU) as a fissile isotope and 96 % {sup 232}Th (ThO{sub 2}) as a non-fissile isotope in a mixed oxide with thorium fuel is proposed. It is assumed that plutonium can also be used in the proposed fuel in a mixture with {sup 235}U. The following advantages of the use of HEU in LWRs in mixed {sup 235}U - Th fuel are pointed out: (1) No generation of long-living plutonium and americium isotopes (in case of reprocessing the high level radioactive wastes will contain only fission fragments and uranium); (2) The high conversion ratio of Th extends the expected burnup by approximately 1/3 without higher initial enrichment (the same initial enrichment simplifies the problem for compensation of the excess reactivity in the beginning with burnable poison and boric acid); (3) The high conversion ratio of Th allows the fuel utilization with less initial enrichment (by approx. 1/3) for the same burnup; thus less excess reactivity has to be compensated after reloading; in case of fuel reprocessing all fissile materials ({sup 235}U + {sup 233}U) could be chemically extracted. Irrespectively to the optimistic expectations outlined, further work including data on optimal loading and reloading schemes, theoretical calculations of thermal properties of {sup 235}U + Th fuel rods, manufacturing of several test fuel assemblies and investigations of their operational behaviour in a reactor core is still needed. 1 fig., 7 refs.

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.

Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

Energy Technology Data Exchange (ETDEWEB)

Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio [Universidad Simón Bolívar, Nuclear Physics Laboratory, Apdo 89000, Caracas 1080A (Venezuela, Bolivarian Republic of); Davila, Jesus [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

2015-07-23

During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e’n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides {sup 232}Th, {sup 238}U and {sup 237}Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

Science.gov (United States)

Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Davila, Jesus; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio

2015-07-01

During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e'n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides 232Th, 238U and 237Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

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 nuclear fission process

International Nuclear Information System (INIS)

Wagemans, C.

1991-01-01

Fifty years after its discovery, the nuclear fission phenomenon is of recurring interest. When its fundamental physics aspects are considered, fission is viewed in a very positive way, which is reflected in the great interest generated by the meetings and large conferences organized for the 50th anniversary of its discovery. From a purely scientific and practical point of view, a new book devoted to the (low energy) nuclear fission phenomenon was highly desirable considering the tremendous amount of new results obtained since the publication of the book Nuclear Fission by Vandenbosch and Huizenga in 1973 (Academic Press). These new results could be obtained thanks to the growth of technology, which enabled the construction of powerful new neutron sources, particle and heavy ion accelerators, and very performant data-acquisition and computer systems. The re-invention of the ionization chamber, the development of large fission fragment spectrometers and sophisticated multiparameter devices, and the production of exotic isotopes also contributed significantly to an improved understanding of nuclear fission. This book is written at a level to introduce graduate students to the exciting subject of nuclear fission. The very complete list of references following each chapter also makes the book very useful for scientists, especially nuclear physicists. The book has 12 chapters covering the fission barrier and the various processes leading to fission as well as the characteristics of the various fission reaction products. In order to guarantee adequate treatment of the very specialized research fields covered, several distinguished scientists actively involved in some of these fields were invited to contribute their expertise as authors or co-authors of the different chapters

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)

Neutron inelastic scattering cross sections of 232Th obtained from (n,n/prime/sub gamma/) measurements

International Nuclear Information System (INIS)

Egan, J.J.; Menachery, J.D.; Kegel, G.H.R.; Pullen, D.J.

1980-01-01

The /sup 232/Th(n,n/prime/sub gamma/) reaction has been studied up to 2.1 MeV bombarding energy for states with excitation energies from 700 to 1700 keV. Seventy-five gamma-ray transitions from forty-three above the first excited state have been observed from a disk scatterer with a 40-cm/sup 3/ Ge(Li) detector surrounded by an anti-Compton annulus of NaI(Tl). The time-of-flight technique was employed to further reduce background. Cross sections for twenty-two states are reported here. The data have been corrected for the finite sample effects of neutron and gamma-ray attenuation, and neutron multiple scattering. The results are compared to those of McMurray et al. and to the predictions of the compound nucleus statistical model. A compound nucleus plus direct interaction calculation is also shown for the 1/sup -/ state at 714 kev. 7 refs

Environmental radioactivity in Turkey, 2007

International Nuclear Information System (INIS)

2009-01-01

In this report, the activity concentrations of natural and artificial radionuclides, gross alpha/beta activities and air gamma dose rates in the environmental and food samples provided from Turkey's seven geographical regions within the environmental radioactivity monitoring program in 2007 are presented. The activity concentrations of the natural ( 238 U, 232 Th, 2 26Ra, 4 :0K and 7 Be) and artificial ( 137 Cs, 134 Cs, 90 Sr, 238-239+240 Pu, 2 41Am) radionuclides and gross alpha/beta activities in the samples were measured by using the gamma spectrometry, the alpha spectrometry, the liquid scintillation counter and the gross alpha /beta counting system. Results show that 137 Cs and 9 0Sr radionuclides originating from the Chernobyl Nuclear Reactor accident in 1986 exist in some of samples even in low levels. The mean activity concentrations of 238 U, 232 Th, 226 Ra and 40 K in the studied surface soil samples were found as 32.1 Bq kg -1 , 35.0 Bq kg -1 , 29.0 Bq kg -1 and 446.7 Bq kg -1 , respectively, while the mean activity concentrations of the fission product 1 37Cs was found as 18.4 Bq kg -1 . While the activity concentrations of 238 U, 232 Th and 226 Ra in the analyzed food samples are lower than the minimum detectable activity (MDA), 134 Cs and 7 Be radionuclides are not observed. The mean activity concentrations of 137 Cs and 90 Sr radionuclides are 0.24 Bq L - 1 and 0.05 Bq L - 1, respectively. (Includes 4 tables and 7 figures)

Quasi-particle excitations in low energy fission

International Nuclear Information System (INIS)

Ashgar, M.; Djebara, M.; Bocquet, J.P.; Brissot, R.; Maurel, M.; Nifenecker, H.; Ristori, C.

1985-05-01

Proton odd-even effect for 229 Th(nsub(th),f) and 232 U(nsub(th),f) has been determined with a ΔE-Esub(R) gas telescope. These data indicate that the qp-particle excitation probability at the saddle point is small and most of its results, when the nucleus moves from saddle to scission and the neck ruptures into final fragments. These results are discussed in terms of the different ideas and models

Mass yields in the reaction 235U(nsub(th),f) as a function of the kinetic energy and ion charge of the fission products

International Nuclear Information System (INIS)

Wohlfarth, H.

1977-01-01

In this paper measurements of mass- and ioncharge distributions of the lower mass 235 U(nsub(th),f)-fission products, performed with the 'Lohengrin' recoil spectrometer of the Institut Lane-Langevin at Grenoble, are reported. The uranium targets used led to an energy loss of the fission fragments of only 1 to 2 MeV, so their energy was well defined. The mass abundance have been measured for the following fragment energies: E = 83.6, 88.5, 93.4, 98.3, 103.1, 108.0, 112.0 MeV. The energy integrated mass distributions were compared with recent data collections of fission yields. For nearly all masses the abundancies agree well within the limits of error. So these maesurements can be used as an independent source of data. (orig./RW) [de

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)

Assessment of environmental (226)Ra, (232)Th and (40)K concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia.

Science.gov (United States)

Saleh, Muneer Aziz; Ramli, Ahmad Termizi; Alajerami, Yasser; Aliyu, Abubakar Sadiq

2013-10-01

Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h(-1) and 1.169 mSv y(-1), respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of (232)Th, (226)Ra and (40)K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg(-1) for (232)Th, 12 ± 1 to 968 ± 27 Bq kg(-1) for (226)Ra, and 12 ± 2 to 2450 ± 86 Bq kg(-1) for (40)K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg(-1) and 70 ± 20 to 4690 ± 90 Bq kg(-1), respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000. Copyright © 2013 Elsevier Ltd. All rights reserved.

Automatic control and monitoring of the MIT fission converter beam

International Nuclear Information System (INIS)

Wilson, B.A.; Riley, K.J.; Harling, O.K.

2000-01-01

An automated control and monitoring system for the new MIT high intensity epithermal neutron irradiation facility has been designed and constructed. The neutron beam is monitored with fission counters located at the periphery of the beam near the patient position. Control of the beam is accomplished with redundant Programmable Logic Controllers (PLCs). These industrial controllers open and close the three shutters of the Fission Converter Beam. The control system uses a series of robust components to assure that the prescribed fluence is delivered. This paper discusses the design and implementation of this system. (author)

Processing Th C{sub 2} - UC{sub 2} fuel extracted from high temperature reactors HTGCR; Etude du traitement des combustibles Th C{sub 2} - UC{sub 2} issus de reacteurs a haute temperature

Energy Technology Data Exchange (ETDEWEB)

Derrien, C; Lessart, P; Pianezza, E; Verry, C; Villain, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

The object of this investigation is solubilisation head-end (from crushing and grinding phase to non included first purification phase) of pulverulent ({sup 233}U/{sup 232}Th)C{sub 2} (200 - 500 microns diameter) contained in a graphite matrix extracted from a 4.10{sup 13} n.cm{sup -2}.s{sup -1} thermalized neutrons average flux with an irradiation of 80000 MWjT{sup -1} HTGCR reactor. After having succinctly described different bibliographic processes we have chosen the burn - leach of reactor fuel and graphite matrix containing it. The technology of burner is original in nuclear field and still more by utilizing ultra-sounds to intensify burning reaction and to minimize the weight of unburnables. The mixture of ThO{sub 2}, U{sub 3}O{sub 8}, and fission products oxides is solubilized by boiling HNO{sub 3} 13 M + HF 0.05 M. This process is profit-learning in a thorium recuperation and reprocessing point of view. In the contrary-case it would be interesting to consider a dry-process which would permit to separate solid ThF{sub 4} from gaseous UF{sub 6}. (authors) [French] Cette etude a pour objet le traitement initial de mise en solution ou 'head-end' (allant de la phase broyag-concassage a la phase de premiere purification exclue) d'un combustible ({sup 233}U/{sup 232}Th)C{sub 2} pulverulent (de 200 a 500 {mu} de diametre) contenu dans une matrice de graphite issu d'un reacteur HTGCR surgenerateur a neutrons thermiques de flux moyen 4. l0{sup 13} n.cm{sup -2}.s{sup -1} et taux d'irradiation 80000 MWjT{sup -1}. Apres exposition succincte des differents procedes bibliographiques decrits, nous avons finalement choisi le traitement par combustion-attaque ('Burn-Leach') du combustible et de la matrice etanche graphite qui le contient. La technologie du bruleur est originale dans le domaine nucleaire d'autant qu'elle utilise les ultra-sons pour ameliorer le rendement de la reaction de combustion et reduire au minimum le poids des imbrules. Le melange ThO{sub 2}, U{sub 3}O

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)

Beagle: an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans

International Nuclear Information System (INIS)

Singh, N.P.; Zimmerman, C.J.; Taylor, G.N.; Wrenn, M.E.

1988-01-01

The concentrations and the organ distribution patterns of 228Th, 230Th and 232Th in two 9-y-old dogs of our beagle colony were determined. The dogs were exposed only to background environmental levels of Th isotopes through ingestion (food and water) and inhalation as are humans. The organ distribution patterns of the isotopes in the beagles were compared to the organ distribution patterns in humans to determine if it is appropriate to extrapolate the beagle organ burden data to humans. Among soft tissues, only the lungs, lymph nodes, kidney and liver, and skeleton contained measurable amounts of Th isotopes. The organ distribution pattern of Th isotopes in humans and dog are similar, the majority of Th being in the skeleton of both species. The average skeletal concentrations of 228Th in dogs were 30 to 40 times higher than the average skeletal concentrations of the parent 232Th, whereas the concentration of 228Th in human skeleton was only four to five times higher than 232Th. This suggests that dogs have a higher intake of 228Ra through food than humans. There is a similar trend in the accumulations of 232Th, 230Th and 228Th in the lungs of dog and humans. The percentages of 232Th, 230Th and 228Th in human lungs are 26, 9.7 and 4.8, respectively, compared to 4.2, 2.6 and 0.48, respectively, in dog lungs. The larger percentages of Th isotopes in human lungs may be due simply to the longer life span of humans. If the burdens of Th isotopes in human lungs are normalized to an exposure time of 9.2 y (mean age of dogs at the time of sacrifice), the percent burden of 232Th, 230Th and 228Th in human lungs are estimated to be 3.6, 1.3 and 0.66, respectively. These results suggest that the beagle may be an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans

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.

Measurement of cross-sections of fission reactions induced by neutrons on actinides from the thorium cycle at n-TOF facility; Mesures de sections efficaces de fission induite par neutrons sur des actinides du cycle du thorium a n-TOF

Energy Technology Data Exchange (ETDEWEB)

Ferrant, L

2005-09-01

In the frame of innovating energy source system studies, thorium fuel cycle reactors are considered. Neutron induced fission cross section on such cycle involved actinides play a role in scenario studies. To feed them, data bases are built with experimental results and nuclear models. For some nuclei, they are not complete or in disagreement. In order to complete these data bases, we have built an original set up, consisting in an alternation of PPACs (Parallel Plate Avalanche Chamber) and ultra - thin targets, which we installed on n-TOF facility. We describe detectors, set up, and the particular care brought to target making and characterization. Fission products in coincidence are detected with precise time measurement and localization with delay line read out method. We contributed, within the n-TOF collaboration, to the CERN brand new intense spallation neutron source characterization, based on time of flight measurement, and we describe its characteristics and performances. We were able to measure such actinide fission cross sections as {sup 232}Th, {sup 234}U, {sup 233}U, {sup 237}Np, {sup 209}Bi, and {sup nat}Pb relative to {sup 235}U et {sup 238}U standards, using an innovative acquisition system. We took advantage of the lame accessible energy field, from 0.7 eV to 1 GeV, combined with the excellent energy resolution in this field. Data treatment and analysis advancement are described to enlighten performance and limits of the obtained results. (author)

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

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.)

Plea and counter-plea

International Nuclear Information System (INIS)

1979-06-01

The bulk of papers written during the hearing 'Plea and counter-plea', the so-called 'Gorleben hearing', which was held from 28th March until 3rd April 1979, comprises ca. 4,200 pages. It consists of the written comments put forward by the critics of nuclear energy, the minutes of the hearing as well as the supplementary statements of the counter-critics. This report is trying to confront those essential objections made by the critics which put in doubt the feasibility of a fuel-cycle centre with regard to safety engineering with the facts which are considered correct from the view of the DWK. The oral and written explanations of the counter-critics are particularly referred to in this debate. (orig./HP) [de

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)

Controlled isotropic fission fragment sources on the base of nuclear-physical facilities

International Nuclear Information System (INIS)

Sevast'yanov, V.D.; Maslov, G.N.

1995-01-01

Isotropic fission fragment sources (IFFS) are developed on the base of a neutron generator and pulse fast reactor. IFFS permit to calibrate fission fragment detectors. The IFFS consist of radiators with 235 U. The radiators are placed in a thermal neutron field of the neutron generator or in the reactor core center. The fragment activity is controlled by indications of an α-particle counter or by indications of a monitor of energy release in the core. 14 refs.; 1 fig.; 1 tab

{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.

On the Th internal contamination of animals

International Nuclear Information System (INIS)

Ciubotariu, M.; Danis, A.; Dumitrescu, G.

2000-01-01

Fissionable elements (U,Th) internal contamination have been studied using the fission track method as analysis method of the U and/or Th contaminant elements and Wistar-London breed rats as experiment animals. In our previous studies on the Th internal contamination, we investigated the Th biodistribution and retention in all the vital organs of the contaminated rats. In this stage, we continued this study with the Th elimination investigation through urine and excrements. The identical aliquot parts of a solution calibrated in Th, corresponding to an Annual Limit Intake, three Wistar-London breed rats were contaminated. They were kept in normal life conditions and under permanent medical surveillance up to their sacrifice. The animals were sacrificed at different time intervals after their contamination: RAT 1 = 2 days, RAT 2 = 7 days and RAT 3 = 14 days, respectively. After the sacrifice, their vital organs were sampled, weighed, calcined, re-weighed and finally analysed by track detection using the fission track micro-mappings technique. The evacuations were sampled every 24 hours: urine, on the filter paper, and all excrements balls. The samples were weighed before and after calcination and analysed in the same way as the vital organs. The Th fission track micro-mappings technique was used in the following conditions: - mica-muscovite as track detector pre-etched for fossil tracks 18 h in HF-40 per cent at room temperature; - the neutron irradiations were performed in the nuclear reactor WWR-S Bucharest at the neutron fluences of 3·10 15 - 2·10 16 fast neutrons/cm 2 ; - the visualization of the Th induced fission tracks was obtained by chemical etching in HF-40 %, 3 h at room temperature; - the Th track micromappings obtained in track detectors were studied by optical microscopy using a stereo microscope WILD M7S for ensemble study (X6-X31) and a binocular Zeiss JENA microscope for qualitative and quantitative studies (X150). The investigation of the Th

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

Long Term Fuel Sustainable Fission Energy Perspective Relevant for Combating Climate Change

International Nuclear Information System (INIS)

Knapp, V.; Matijevic, M.; Pevec, D.; Crnobrnja, B.; Lale, D.

2016-01-01

In recent research we outlined climate relevant and immediately available proven light water nuclear strategy with a potential to contribute essentially and timely to reduction of carbon dioxide emission to the year 2065. We consider in this paper what is the perspective of fission energy after that year should its contribution be needed. Singling out two technologies with long term perspective which need no or small amounts of uranium, fast breeders and molten salt thorium reactors, we consider their main technical and safety characteristics. In both of these technologies it is essential to have starter nuclides as neither U238 nor Th232 are fissile. We investigated whether plutonium from spent fuel of light water reactors generated to the year 2065 would be present in quantities sufficient to continue operation on the same or similar level in both technologies. However in operational safety, proliferation risks, waste production, in our judgement we must give preference to thorium technology, if it would be ready in second half of the century.(author).

Measurements of fission cross-sections and of neutron production rates

International Nuclear Information System (INIS)

Billaud, P.; Clair, C.; Gaudin, M.; Genin, R.; Joly, R.; Leroy, J.L.; Michaudon, A.; Ouvry, J.; Signarbieux, C.; Vendryes, G.

1958-01-01

a) Measurements of neutron induced fission cross-sections in the low energy region. The variation of the fission cross sections of several fissile isotopes has been measured and analysed, for neutron energies below 0,025 eV. The monochromator was a crystal spectrometer used in conjunction with a mechanical velocity selector removing higher order Bragg reflections. The fissile material was laid down on the plates of a fission chamber by painting technic. An ionization chamber, having its plates coated with thin 10 B layers, was used as the neutron flux monitor. b) Measurement of the fission cross section of 235 U. We intend to measure the variation of the neutron induced fission cross section of 235 U over the neutron energy range from 1 keV by the time of flight method. The neutron source is the uranium target of a pulsed 28 MeV electron linear accelerator. The detector is a large fission chamber, with parallel plates, containing about 10 g of 235 U (20 deposits of 25 cm diameter). The relative fission data were corrected for the neutron spectrum measured with a set of BF 3 proportional counters. c) Mean number ν of neutrons emitted in neutron induced fission. We measured the value of ν for several fissile isotopes in the case of fission induced by 14 MeV neutrons. The 14 MeV neutrons were produced by D (t, n) α reaction by means of a 300 kV Cockcroft Walton generator. (author) [fr

Study of the Fission Decay of Heavy Hypernuclei

CERN Multimedia

2002-01-01

The purpose of the original experiment PS177 was to produce heavy hypernuclei using the annihilation at rest of antiprotons in heavy targets, and to measure their lifetime. \\\\ \\\\ Lambda hyperons can be produced, within a nucleus, in a 2-step process: p@*~@A~K&bar.K~+~X; &bar.KN~@A~@L@p; or in a direct 3-body interaction: @*NN~@A~K|+@L. In the first case, the kinematical conditions favour recoilless lambda with, consequently, a higher probability of attachment to the nucleus. In a heavy nucleus the lambda-hyperon decays weakly according to: @LN~@A~NN, and the &prop.170~MeV energy released induces fission.\\\\ \\\\ The identification of the hypernuclei and their lifetime measurements were performed through the detection of delayed fission using the recoil-distance-method (suitable for lifetimes in the expected region @=10|-|1|0s). The fission fragments were detected by parallel-plate avalanche counters. \\\\ \\\\ The new proposal aims at i) increasing the accuracy of the measured lifetimes, ii) having a str...

Picosecond-precision multichannel autonomous time and frequency counter

Science.gov (United States)

Szplet, R.; Kwiatkowski, P.; RóŻyc, K.; Jachna, Z.; Sondej, T.

2017-12-01

This paper presents the design, implementation, and test results of a multichannel time interval and frequency counter developed as a desktop instrument. The counter contains four main functional modules for (1) performing precise measurements, (2) controlling and fast data processing, (3) low-noise power suppling, and (4) supplying a stable reference clock (optional rubidium standard). A fundamental for the counter, the time interval measurement is based on time stamping combined with a period counting and in-period two-stage time interpolation that allows us to achieve wide measurement range (above 1 h), high precision (even better than 4.5 ps), and high measurement speed (up to 91.2 × 106 timestamps/s). The frequency is measured up to 3.0 GHz with the use of the reciprocal method. Wide functionality of the counter includes also the evaluation of frequency stability of clocks and oscillators (Allan deviation) and phase variation (time interval error, maximum time interval error, time deviation). The 8-channel measurement module is based on a field programmable gate array device, while the control unit involves a microcontroller with a high performance ARM-Cortex core. An efficient and user-friendly control of the counter is provided either locally, through the built-in keypad or/and color touch panel, or remotely, with the aid of USB, Ethernet, RS232C, or RS485 interfaces.

Design of ITER neutron monitor using micro fission chambers

International Nuclear Information System (INIS)

Nishitani, Takeo; Ebisawa, Katsuyuki; Ando, Toshiro; Kasai, Satoshi; Johnson, L.C.; Walker, C.

1998-08-01

We are designing micro fission chambers, which are pencil size gas counters with fissile material inside, to be installed in the vacuum vessel as neutron flux monitors for ITER. We found that the 238 U micro fission chambers are not suitable because the detection efficiency will increase up to 50% in the ITER life time by breading 239 Pu. We propose to install 235 U micro fission chambers on the front side of the back plate in the gap between adjacent blanket modules and behind the blankets at 10 poloidal locations. One chamber will be installed in the divertor cassette just under the dome. Employing both pulse counting mode and Campbelling mode in the electronics, we can accomplish the ITER requirement of 10 7 dynamic range with 1 ms temporal resolution, and eliminate the effect of gamma-rays. We demonstrate by neutron Monte Carlo calculation with three-dimensional modeling that we avoid those detection efficiency changes by installing micro fission chambers at several poloidal locations inside the vacuum vessel. (author)

Extraction of potential energy in charge asymmetry coordinate from experimental fission data

Energy Technology Data Exchange (ETDEWEB)

Pasca, H. [Joint Institute for Nuclear Research, Dubna (Russian Federation); ' ' Babes-Bolyai' ' Univ., Cluj-Napoca (Romania); Andreev, A.V.; Adamian, G.G. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Antonenko, N.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Tomsk Polytechnic Univ. (Russian Federation). Mathematical Physics Dept.

2016-12-15

For fissioning isotopes of Ra, Ac, Th, Pa, and U, the potential energies as a function of the charge asymmetry coordinate are extracted from the experimental charge distributions of the fission fragment and compared with the calculated scission-point driving potentials. The role of the potential energy surfaces in the description of the fission charge distribution is discussed. (orig.)

A position sensitive parallel plate avalanche counter

International Nuclear Information System (INIS)

Lombardi, M.; Tan Jilian; Potenza, R.; D'amico, V.

1986-01-01

A position sensitive parallel plate avalanche counter with a distributed constant delay-line-cathode (PSAC) is described. The strips formed on the printed board were served as the cathode and the delay line for readout of signals. The detector (PSAC) was operated in isobutane gas at the pressure range from 10 to 20 torr. The position resolution is better than 1 mm and the time resolution is about 350 ps, for 252 Cf fission-spectrum source

Burn-up determination of irradiated thoria samples by isotope dilution-thermal ionisation mass spectrometry

International Nuclear Information System (INIS)

Aggarwal, S.K.; Jaison, P.G.; Telmore, V.M.; Shah, R.V.; Sant, V.L.; Sasibhushan, K.; Parab, A.R.; Alamelu, D.

2010-03-01

Burn-up was determined experimentally using thermal ionization mass spectrometry for two samples from ThO 2 bundles irradiated in KAPS-2. This involved quantitative dissolution of the irradiated fuel samples followed by separation and determination of Th, U and a stable fission product burn-up monitor in the dissolved fuel solution. Stable fission product 148 Nd was used as a burn-up monitor for determining the number of fissions. Isotope Dilution-Thermal Ionisation Mass Spectrometry (ID-TIMS) using natural U, 229 Th and enriched 142 Nd as spikes was employed for the determination of U, Th and Nd, respectively. Atom % fission values of 1.25 ± 0.03 were obtained for both the samples. 232 U content in 233 U determined by alpha spectrometry was about 500 ppm and this was higher by a factor of 5 compared to the theoretically predicted value by ORIGEN-2 code. (author)

Contributions to the theory of fission neutron emission

International Nuclear Information System (INIS)

Seeliger, D.; Maerten, H.; Ruben, A.

1990-03-01

This report gives a compilation of recent work performed at Technical University, Dresden by D. Seeliger, H. Maerten and A. Ruben on the topic of fission neutron emission. In the first paper calculated fission neutron spectra are presented using the temperature distribution model FINESSE for fissioning actinide nuclei. In the second paper, starting from a general energy balance, Terrell's approach is generalized to describe average fragment energies as a function of incident energy; trends of fragment energy data in the Th-Pu region are well reproduced. In the third contribution, prompt fission neutron spectra and fragment characteristics for spontaneous fission of even Pu-isotopes are presented and discussed in comparison with experimental data using a phenomenological scission point model including temperature dependent shell effects. In the fourth paper, neutron multiplicities and energy spectra as well as average fragment energies for incident energies from threshold to 20 MeV (including multiple-chance fission) for U-238 are compared with traditional data representations. (author). Refs, figs and tabs

17 CFR 232.11 - Definition of terms used in part 232.

Science.gov (United States)

2010-04-01

... effect by a person executing or issuing it. If data are stored in a computer or similar device, any... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Definition of terms used in part 232. 232.11 Section 232.11 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION...

Use of gamma ray spectroscopy measurements for assessment of the average effective dose from the analysis of 226Ra, 232Th and 40K in soil samples

International Nuclear Information System (INIS)

Mehra, Rohit; Singh, Surinder

2008-01-01

The activity concentrations of soil samples collected from different locations of Ludhiana and Patiala districts of Punjab were determined by using HPGe detector based on high-resolution gamma spectrometry system. The range of activity concentrations of 226 Ra, 232 Th and 40 K in the soil from the studied areas varies from 23.32 Bq kg -1 to 43.64 Bq kg -1 , 104.23 Bq kg -1 to 148.21 Bq kg -1 and 289.83 Bq kg -1 to 394.41 Bq kg -1 with overall mean values of 32 Bq kg -1 , 126 Bq kg -1 and 348 Bq kg -1 respectively. The absorbed dose rate calculated from activity concentration of 226 Ra, 232 Th and 40 K ranges between 10.75 and 20.12, 64.93 and 92.33, and 11.99 and 16.32 n Gy h -1 , respectively. The total absorbed dose in the study area ranges from 91.35 n Gy h -1 to 119.76 n Gy h -1 with an average value of 107.97 n Gy h -1 . The calculated values of external hazard index (H ex ) for the soil samples of the study area range from 0.55 to 0.72. Since these values are lower than unity, therefore, according to the Radiation Protection 112 (European Commission, 1999) report, soil from these regions is safe and can be used as a construction material without posing any significant radiological threat to population. The concentration of 232 Th in soil samples of Malwa region of Punjab are higher than the world figures reported in UNSCEAR (2000). However, the concentrations for 226 Ra is very much comparable and concentration of 40 K are lower than world figures. The results obtained have shown that the indoor and outdoor effective dose due to natural radioactivity of soil samples is lower than the average national and world recommended value of 1.0 mSv.Y -1 . These values reported for radium content in soils of study area are generally low as compared to the values reported for radium concentration in soils of Himachal Pradesh. (author)

Development of fission Mo production technology

International Nuclear Information System (INIS)

Kim, B. K.; Park, K. B.; Jun, B. J.; Park, J. H.; Choung, W. M.; Lee, K. I.; Woo, M. S.; Whang, D. S.; Kim, Y. K.; Yoo, J. H.; Sohn, D. S.; Lee, Y. W.; Na, S. H.; Koo, Y. H.; Hwang, D. H.; Joo, P. K.

1997-08-01

The feasibility study is accomplished in this project for the development of fission moly production. The KAERI process proposed for development in KAERI is discussed together with those of the American Cintichem and Russian IPPE, each of which would be plausible for introduction whenever the indigenous development is not much feasible. For the conceptual design of the KAERI irradiation target, analysis method is set up and some preliminary analysis is performed accordingly for the candidate design. To establish chemical process concepts for the afore-mentioned three processes, characteristics, operation conditions, and the management of the generated wastes are investigated. Basic requirements of hotcell facilities for chemical processing and a possible way of utilizing the existing hotcells are discussed in parallel with the counter-measures for the construction of new hotcell facilities. Various conditions of target irradiation for fission moly production in Hanaro are analyzed. Plan for introduction of the relevant technology introduction and for procurement of highly enriched uranium are considered. On the basis of assuming some conditions, the economic feasibility study for fission moly production is also overviewed. (author). 22 refs., 28 tabs., 24 figs

An annular BF3 counter of large sensitive volume

International Nuclear Information System (INIS)

Janardhanan, S.; Swaminathan, N.

1975-01-01

An annular neutron counter having a large sensitive volume with inner and outer diameter 31 cms with multiple electrode system fabricated especially to measure the neutron output from fissile region of standard fast reactor fuel of length nearly equivalent to 500 cms is described. The counter efficiency is nearly 0.3% for neutron and sensitivity 0.0018 counts/neutron for (alpha, neutron) and spontaneous fission source. Its other potential applications which are indicated are : (1) quality control of fast reactor fuel pins (2) fuel inventory (3) assessing radioactivity of solid waste packets containing PuO 2 (4) uniformity of fuel loading of a reactor and (5) neutron monitoring in a fuel plant. (M.G.B.)

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)

Measurement of cross-sections of fission reactions induced by neutrons on actinides from the thorium cycle at n-TOF facility

International Nuclear Information System (INIS)

Ferrant, L.

2005-09-01

In the frame of innovating energy source system studies, thorium fuel cycle reactors are considered. Neutron induced fission cross section on such cycle involved actinides play a role in scenario studies. To feed them, data bases are built with experimental results and nuclear models. For some nuclei, they are not complete or in disagreement. In order to complete these data bases, we have built an original set up, consisting in an alternation of PPACs (Parallel Plate Avalanche Chamber) and ultra - thin targets, which we installed on n-TOF facility. We describe detectors, set up, and the particular care brought to target making and characterization. Fission products in coincidence are detected with precise time measurement and localization with delay line read out method. We contributed, within the n-TOF collaboration, to the CERN brand new intense spallation neutron source characterization, based on time of flight measurement, and we describe its characteristics and performances. We were able to measure such actinide fission cross sections as 232 Th, 234 U, 233 U, 237 Np, 209 Bi, and nat Pb relative to 235 U et 238 U standards, using an innovative acquisition system. We took advantage of the lame accessible energy field, from 0.7 eV to 1 GeV, combined with the excellent energy resolution in this field. Data treatment and analysis advancement are described to enlighten performance and limits of the obtained results. (author)

Development of Commercial-scale Fission Mo-99 Production System

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung-Kon; Lee, Suseung; Hong, Soon-Bog; Jang, Kyung-Duk; Park, Ul Jael; Lee, Jun Sig [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

These days, worldwide {sup 99} Mo supply is not only insufficient but also unstable. Because, most of the main {sup 99}Mo production reactors are more than years old and suffered from frequent and unscheduled shutdown. Therefore, movement to replace old reactors to keep stable supply is now active. Under these conditions, KAERI (Korea Atomic Energy Research Institute) is developing LEU-based fission {sup 99}Mo production process which is connected to the new research reactor (Kijang New Research Reactor, KJRR), which is being constructed in Gijang, Busan, Korea. Historically, the most fission {sup 99}Mo producers have been used highly enriched uranium (HEU) targets so far. However, to reduce the use of HEU in private sector for non-proliferation, {sup 99}Mo producers are forced to convert their HEU-based process to use low enriched uranium (LEU) targets. Economic impact of a target conversion from HEU to LEU is significant. In this study, fission {sup 99}Mo process with non-irradiated LEU targets was presented except separation and purification steps. Pre- and post-irradiation tests of the fission {sup 99}Mo target will be done in 4th quarter of 2016. For the fission Mo production process development, hot experiments with irradiated LEU targets will be done in 4th quarter of 2016. Then, verification of the production process with quality control will be followed until the commercial production of fission {sup 99}Mo scheduled in 2019.

Study of the specific activity concentrations of 40K, 226Ra, 228Ra and 232Th in vegetables and their respective covering tissues (peels)

International Nuclear Information System (INIS)

Lopes, J.M.; Garcêz, R.W.D.; Silva, A.X.

2017-01-01

This work presents an analysis of specific concentrations of 40 K, 226 Ra, 228 Ra and 232 Th in some vegetables that are part of the diet of the population of the state of Rio de Janeiro. Furthermore, was analyzed the concentrations of radionuclides in the same coating tissue that compose the vegetables. It can notice an increase of the specific concentration of 40 K in the peels of vegetables that have little or no contact with the ground. Among the samples examined, only the pumpkin showed measurable amount of 137 Cs both saves and in the skin. (author)

Distribution of Th-230 and Th-228 in food (I)

Energy Technology Data Exchange (ETDEWEB)

Kang, Hee Dong; Kim, Wan; Lim, X. J.; Choi, M. S.; Kim, C. J.; Zheng, Y. Z. [Kyungpook National Univ., Daegu (Korea, Republic of); Kim, Do Sung [Daegu Univ., Daegu (Korea, Republic of)

2003-03-15

Natural radioisotopes contained in foods can enter the human body by ingestion and contribute to internal doses to the population. It is necessary to measure the concentration of natural radioisotopes especially thorium in Korean foods and estimate the internal doses. In this study, we have established the thorium measuring process based on the thorium extraction chemical process and alpha spectroscopic method. The concentration of Th-228, Th-230 and Th-232 in Korean milk, meats(pork, beef and chicken) and grain (wheat, bean and rice) are measured and internal doses are estimated.

Fission gas release and grain growth in THO2-UO2 fuel irradiated at high temperature

International Nuclear Information System (INIS)

Goldberg, I.; Waldman, L.A.; Giovengo, J.F.; Campbell, W.R.

1979-01-01

Data are presented on fission gas release and grain growth in ThO 2 -UO 2 fuels irradiated as part of the LWBR fuel element development program. These data for rods that experienced peak linear power outputs ranging from 15 to 22 KW/ft supplement fission gas release data previously reported for 51 rods containing ThO 2 and ThO 2 -UO 2 fuel irradiated at peak linear powers predominantly below 14 KW/ft. Fission gas release was relatively high (up to 15.0 percent) for the rods operated at high power in contrast to the relatively low fission gas release (0.1 to 5.2 percent) measured for the rods operated at lower power. Metallographic examination revealed extensive equiaxed grain growth in the fuel at the high power axial locations of the three rods

Search for spontaneous fission activity in Salton Sea and Atlantis II hot brines

International Nuclear Information System (INIS)

Ter-Akopian, G.M.; Sokol, E.A.; Fam Ngoc Chuong; Ivanov, M.P.; Popeko, G.S.; Molzahn, D.; Lund, T.; Feige, G.; Brandt, R.

1984-01-01

A search for an unknown spontaneously fissioning activity, possibly due to SHE, was carried out with the Dubna 3 He-counter system. In the investigation of Salton Sea samples and Atlantis II samples no such activity could be detected with limits -12 g/g. (orig.)

Attempt to enrich of a new spontaneous fissioning nuclide by evaporation of natural brine

International Nuclear Information System (INIS)

Adamek, A.; Zhuravleva, E.L.; Constantinescu, M.; Constantinescu, o.; Chuburkov, Yu.T.

1983-01-01

The enrichment of the new spontaneous fissioning nuclide discovered in the Cheleken brine, was made by evaporation. The purpose of this work was the comparison of behaviour of the new spontaneous fissioning nuclide with that of the known elements in the formation processes of the high concentration brines. Spontaneous fission of the nuclide was measured by means of the counters for multiple emission of neutrons. It is shown that the new spontaneous fissioning nuclide was enriched as well as other trace elements (Hg, Tl, Bi and Pb) in a solution remained after the evaporation of the initial solution. The conclusion is drawn that from the sea water brines could be obtained by evaporation which are enriched in trace elements with an enrichment degree higher than the natural brines

Experimental study of fission process by fragment-neutron correlation measurement

Energy Technology Data Exchange (ETDEWEB)

Nishio, Katsuhisa; Yamamoto, Hideki; Kanno, Ikuo; Kimura, Itsuro; Nakagome, Yoshihiro [Kyoto Univ. (Japan). Faculty of Engineering

1997-07-01

Fragment-neutron correlation measurement of {sup 235}U(n{sub th}, f) was carried out. The obtained results showed more statistical accuracy than that of reported thermal neutron reaction. Experimental results and it`s analysis made clear the following facts. The minimum values of <{eta}> (m*) are shown at about 90 and 145 {mu} and <{eta}> (m*) showed the symmetrical form with an axis of symmetrical fission. This tendency is same as the distribution of {sup 252}Cf(s.f). -dV/dTKE(m*) indicates the saw-teethed distribution as same as <{nu}>(m*). The distribution seems depend on stiffness of fission fragment affected by the shell effect. The level density parameter a(m*) of fission fragment obtained from {sup 235}U(n{sub th}, f) expresses the saw-teethed distribution as same as that of {sup 252}Cf(s.f). This distribution can be explained by the empirical equation under consideration of the fission fragment depending on the shell effect and the collective motion. (S.Y.)

Measurements of fission cross-sections and of neutron production rates; Mesures de sections efficaces de fission et du nombre de neutrons prompts emis par fission

Energy Technology Data Exchange (ETDEWEB)

Billaud, P; Clair, C; Gaudin, M; Genin, R; Joly, R; Leroy, J L; Michaudon, A; Ouvry, J; Signarbieux, C; Vendryes, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

a) Measurements of neutron induced fission cross-sections in the low energy region. The variation of the fission cross sections of several fissile isotopes has been measured and analysed, for neutron energies below 0,025 eV. The monochromator was a crystal spectrometer used in conjunction with a mechanical velocity selector removing higher order Bragg reflections. The fissile material was laid down on the plates of a fission chamber by painting technic. An ionization chamber, having its plates coated with thin {sup 10}B layers, was used as the neutron flux monitor. b) Measurement of the fission cross section of {sup 235}U. We intend to measure the variation of the neutron induced fission cross section of {sup 235}U over the neutron energy range from 1 keV by the time of flight method. The neutron source is the uranium target of a pulsed 28 MeV electron linear accelerator. The detector is a large fission chamber, with parallel plates, containing about 10 g of {sup 235}U (20 deposits of 25 cm diameter). The relative fission data were corrected for the neutron spectrum measured with a set of BF{sub 3} proportional counters. c) Mean number {nu} of neutrons emitted in neutron induced fission. We measured the value of {nu} for several fissile isotopes in the case of fission induced by 14 MeV neutrons. The 14 MeV neutrons were produced by D (t, n) {alpha} reaction by means of a 300 kV Cockcroft Walton generator. (author)Fren. [French] a) Mesures de sectionficaces de fission a basse energie. Nous avons mesure et analyse la variation de la section efficace de fission de divers isotopes fissiles pour des neutrons d'energie inferieure a 0,025 eV. Le monochromateur est constitue par un spectrometre a cristal auquel est associe un selecteur mecanique destine a eliminer les diffractions de Bragg d'ordre superieur au premier. Le materiau fissile est contenu dans une chambre a fission sous forme de depots realises par peinture; une chambre d'ionisation a depots minces de B{sub 10

Assessment of sedimentation rate based on disequilibrium in the {sup 232}Th decay series in an artificial pond downstream a former uranium mine

Energy Technology Data Exchange (ETDEWEB)

Reyss, J.L. [Laboratoire des Sciences du Climat et de l' Environnement - LSCE/IPSL, Unite Mixte de Recherche 8212 CEA, CNRS, UVSQ, F-91198 Gif-sur-Yvette Cedex (France); Mangeret, A.; Courbet, C.; Saadi, Z.; Guillevic, J. [Institut de Radioprotection et de Surete Nucleaire (IRSN), BP 17, 92262 Fontenay aux Roses (France); Thouvenot, A. [LMGE, UMR CNRS 6023, Lab Microorganismes Genome et Environnement, 63 177 Aubiere (France)

2014-07-01

In rivers and lakes, sediment dynamics are very difficult to quantify by field measurements as well as by modeling studies (Olley et al. 1997 WRR 33, 1319-1326). The well-known {sup 210}Pb excess method (Appleby 2000 Limnology 59-S.1, 1-14; Perga et al. 2010 Limnol. and Ocean. 55, 803-816) cannot be used for quantifying sedimentation rates over granitic catchments as large amounts of {sup 210}Pb produced by granite weathering tend to dilute the atmospheric {sup 210}Pb. The knowledge of sedimentation rates in lakes is however very important for understanding the geochemical mechanisms involved in contaminant scavenging and remobilization at the sediment-water interface (SWI). Moreover, these measurements are crucial for developing solute transport models, especially for radionuclides and metals in pore waters and through the SWI. In order to overcome these issues, this study focuses on an artificial pound located in a granitic catchment, down-gradient from a former uranium mining site that ceased operations at the beginning of the 80's (Guillevic and Reyss 2011 ICRER 2011). Sediment sampling was carried out in this artificial lake with an UWITEC{sup R} hand corer. All the samples were dried and the activities of artificial and natural radionuclides were measured by gamma spectrometry, at the Underground Laboratory of Modane and alpha spectrometry after radiochemical purification. The profile of {sup 210}Pb activities in the sediment increased with depth in the core and did not allow to distinguish the atmospheric {sup 210}Pb from the {sup 210}Pb produced by watering processes in this uranium enriched environment. Another method for quantifying sediment accumulation rates is therefore proposed here using the disequilibrium between {sup 228}Ra (half-life of 5.75 years) and {sup 232}Th, the parent isotope. The excess of {sup 228}Ra over its respective parent {sup 232}Th has already been demonstrated by (Olley et al. 1997 WRR 33, 1319-1326) in river and lake

Th isotopes in the Santa Monica basin: temporal variation, long-term mass balance and model rate constants

International Nuclear Information System (INIS)

Huh, Chih-An

1995-01-01

Distribution and flux of 234 Th, 232 Th and 230 Th in the water column of central Santa Monica basin observed over a period of seven years show seasonal and interannual variabilities. A steady-state model is applied to the integrated data to calculate long term average flux and model rate constants of Th isotopes. Mass balance calculations show that the basin acts like a closed system for short-lived 234 Th, but not for the long-lived isotopes 230 Th and 232 Th. Most 230 Th in the basin is transported from elsewhere. Of the incoming Th, 40-55% of the 230 Th and 14-26% of the 232 Th enter the surface water in dissolved form. In the upper 100m, the residence time of dissolved Th with respect to adsorption onto suspended particulates, 70-80 days, is about one order of magnitude higher than the residence time of suspended particles with respect to aggregation into sinking particles, 7-10 days. (author)

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.

Low-pressure, multistep, multiwire proportional counter for the time-of-flight isochronous spectrometer

International Nuclear Information System (INIS)

Vieira, D.J.

1985-01-01

A low-pressure, multistep, multiwire proportional counter (MSMWPC) has been developed for the characterization and testing of the time-of-flight isochronous (TOFI) spectrometer and its associated secondary-beam transport line. This type of counter was selected because of its high sensitivity, large dynamic range, and good position (0.2 mm FWHM) and timing (180 ps FWHM) resolution. Furthermore, because the counter operates at low gas pressures (1-10 torr) and high electric-field strengths, which enable short collection times, it can be used as a transmission counter with thin gas-isolation windows and it can operate at high counting rates. Here the authors discuss the basic operating principle of the MSMWPC, describe the technical details of the detector and signal processing, and report on the performance they have measured for alpha particles and fission fragments

Spontaneous fission of 259Md

International Nuclear Information System (INIS)

Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Landrum, J.H.; Dougan, R.J.; Mustafa, M.; Ghiorso, A.; Nitschke, J.M.

1979-01-01

The mass and kinetic energy distributions of fission fragments from the spontaneous fission of th newly discovered nuclide 259 Md were obtained. 259 Md was identified as the E. C. daughter of 259 No, and was found to decay entirely (> 95%) by spontaneous fission with a 95-min half-life. From the kinetic energies measured for 397 pairs of coincident fragments, a mass distribution was derived that is symmetric with sigma = 13 amu. 259 Md, together with 258 Fm and 259 Fm, form a select group of three nuclides whose mass division in spontaneous fission is highly symmetric. Unlike the total-kinetic-energy (TKE) distributions of 258 Fm and 259 Fm, which peak at approx. = to 240 MeV, this distribution for 259 Md is broad and is 50 MeV lower in energy. Analysis of the mass and energy distributions shows that events near mass symmetry also exhibit a broad TKE distribution, with one-third of the symmetric events having TKEs less than 200 MeV. The associated of low TKEs with symmetric mass division in the fission of very heavy actinides is anomalous and inconsistent with theories based upon the emergence of fragment shells near the scission point. Either three-body fragmentation or peculiar fragment shapes are assumed as the cause for the large consumption of Coulomb energy observed for a significant fraction of symmetric fissions in 259 Md. 6 figures

Study of fission dynamics with the three-dimensional Langevin equations

Energy Technology Data Exchange (ETDEWEB)

Eslamizadeh, H. [Persian Gulf University, Department of Physics, Bushehr (Iran, Islamic Republic of)

2011-11-15

The dynamics of fission has been studied by solving one- and three-dimensional Langevin equations with dissipation generated through the chaos weighted wall and window friction formula. The average prescission neutron multiplicities, fission probabilities and the mean fission times have been calculated in a broad range of the excitation energy for compound nuclei {sup 210}Po and {sup 224}Th formed in the fusion-fission reactions {sup 4}He+{sup 206}Pb, {sup 16}O+{sup 208}Pb and results compared with the experimental data. The analysis of the results shows that the average prescission neutron multiplicities, fission probabilities and the mean fission times calculated by one- and three-dimensional Langevin equations are different from each other, and also the results obtained based on three-dimensional Langevin equations are in better agreement with the experimental data. (orig.)

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

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)

Determination of the resonance parameters for 232Th from high resolution transmission and capture measurements at GELINA

International Nuclear Information System (INIS)

Brusegan, A.; Schillebeeckx, P.; Lobo, G.; Borella, A.; Volev, K.; Janeva, N.

2003-01-01

To deduce the resonance parameters for 232 Th in the resolved resonance region, high resolution transmission and capture measurements are being performed. The measurements are performed at the Time-Of-Flight facility GELINA. A comparison of experimental data resulting from capture (top) and transmission (bottom) are shown. The transmission measurements are performed at a 50 m flight path. The neutron are detected with a 0.25' thick lithium glass (NE912) placed in an Al sphere and viewed by a 5' EMI KQB photomultiplier orthogonal to the neutron beam axis. The injection of a stabilised light pulse in the detector during the measurements provided an efficient tool to control to better than 1% the gain of the entire electronics. The experimental set-up includes a sample-changer, placed at 23 m from the neutron source, which is driven by the acquisition system. The determination of the flight path length, was based on transmission of the 6.673 eV resonance of 238 U. We summarise, for the different energy regions of interest, the scheduled measurement conditions: the operation frequency of the accelerator and the target thickness. A simultaneous analysis of the data using REFIT will result in the resonance parameters from 0 to 4 keV. We show the result of a resonance shape analysis for the resonances at 21.8 and 23.5 eV. The resulting resonance parameters are important for the energy calibration and normalisation of the capture measurements in both the resolved and unresolved resonance region. The capture measurements are completed and were performed at a 60 m flight path. The sample consisted of a metallic natural thorium disc of 8 cm diameter and 1.0 mm thick, corresponding to a thickness of 3.176 10 -3 at/b. The neutron flux was measured with an ionisation chamber loaded with three back-to-back layers of about 40 μg/cm 2 10 B. The gamma rays, originating from the 232 Th(n,γ) reaction, were detected by four C 6 D 6 -based liquid scintillators (NE230) placed

Thorium--uranium cycle ICF hybrid concept

International Nuclear Information System (INIS)

Frank, T.G.

1978-01-01

The results of preliminary studies of a laser-driven fusion-fission hybrid concept utilizing the 232 Th- 233 U breeding cycle are reported. Neutron multiplication in the breeding blanket is provided by a region containing 238 UO 2 and the equilibrium concentration of 239 PuO 2 . Established fission reactor technology is utilized to determine limits on operating conditions for high-temperature fuels and structures. The implications of nonproliferation policies for the operation of fusion-fission hybrid reactors are discussed

Irradiation experiments of 3rd, 4th and 5th fuel assemblies by an in-pile gas loop, OGL-1

International Nuclear Information System (INIS)

Fukuda, Kousaku; Kobayashi, Fumiaki; Hayashi, Kimio; Minato, Kazuo; Kikuchi, Teruo; Adachi, Mamoru; Iwamoto, Kazumi; Ikawa, Katsuichi; Itami, Hiroharu.

1986-07-01

Three irradiation experiments for 3rd, 4th and 5th fuel assemblies which had been composed of VHTR reference coated particle fuels and graphite components were carried out by an in-pile gas loop, OGL-1 during 1979 and 1982. The main purposes of these experiments were to study on bowing of the fuel rod by irradiation for the 3rd fuel assembly, to study on fuel behavior under relatively low burnup irradiation for the 4th fuel assembly, and to study on fuel behavior up to full burnup of VHTR design for the 5th fuel assembly. For understanding in-pile fuel behavior, fractional releases of fission gases from each fuel assembly were estimated by measuring the fission gas concentrations in the primary loop of OGL-1. The post-irradiation examination (PIE) was carried out extensively on the fuel block, the fuel rods and the fuel compacts in Tokai Hot Laboratory. Also, made were the measurements of metallic fission product distributions in the fuel assemblies and the fuel rods. The results in these experiments were given as follows ; bowing of the fuel rod in the 3rd fuel assembly was 0.7 mm, but integrity of the rod was kept under irradiation. Fractional release of the fission gas from the 4th fuel assembly remained in the order of 10 -7 during irradiation, suggesting that the fuel performance was excellent. The fractional release from the 5th fuel assembly, on the other hand, was in the order of 10 -5 which was the same level in the VHTR design. (author)

Investigation of tritium and 233U breeding in a fission-fusion hybrid reactor fuelling with ThO2

International Nuclear Information System (INIS)

Yildiz, K.; Sahin, S.; Sahin, H. M.; Acir, A.; Yalcin, S.; Altinok, T.; Bayrak, M.; Alkan, M.; Durukan, O.

2007-01-01

In the world, thorium reserves are three times more than natural Uranium reserves. It is planned in the near future that nuclear reactors will use thorium as a fuel. Thorium is not a fissile isotope because it doesn't make fission with thermal neutrons so it could be converted to 2 33U isotope which has very high quality fission cross-section with thermal neutrons. 2 33U isotope can be used in present LWRs as an enrichment fuel. In the fusion reactors, tritium is the most important fossil fuel. Because tritium is not natural isotope, it has to be produced in the reactor. The purpose of this work is to investigate the tritium and 2 33U breeding in a fission-fusion hybrid reactor fuelling with ThO 2 for Δt=10 days during a reactor operation period in five years. The neutronic analysis is performed on an experimental hybrid blanket geometry. In the center of the hybrid blanket, there is a line neutron source in a cylindrical cavity, which simulates the fusion plasma chamber where high energy neutrons (14.1 MeV) are produced. The conventional fusion reaction delivers the external neutron source for blankets following, 2 D + 3 T →? 4 He (3.5 MeV) + n (14.1 MeV). (1) The fuel zone made up of natural-ThO 2 fuel and it is cooled with different coolants. In this work, five different moderator materials, which are Li 2 BeF 4 , LiF-NaF-BeF 2 , Li 2 0Sn 8 0, natural Lithium and Li 1 7Pb 8 3, are used as coolants. The radial reflector, called tritium breeding zones, is made of different Lithium compounds and graphite in sandwich structure. In the work, eight different Lithium compounds were used as tritium breeders in the tritium breeding zones, which are Li 3 N, Li 2 O, Li 2 O 2 , Li 2 TiO 3 , Li 4 SiO 3 , Li 2 ZrO 3 , LiBr and LiH. Neutron transport calculations are conducted in spherical geometry with the help of SCALE4.4A SYSTEM by solving the Boltzmann transport equation with code CSAS and XSDRNPM, under consideration of unresolved and resolved resonances, in S 8 -P 3

Distribution of Th-230 and Th-228 in foods(II)

Energy Technology Data Exchange (ETDEWEB)

Kang, Hee Dong; Kim, Wan; Lim, S. K.; Lee, S. A.; Choi, M. S.; Zheng, Y. C. [Kyungpook National Univ., Daegu (Korea, Republic of); Kim, Do Sung [Daegu Univ., Daegu (Korea, Republic of)

2004-02-15

Natural radioisotopes contained in foods can enter the human body by ingestion and contribute to internal doses to the population. It is necessary to measure the concentration of natural radioisotopes especially thorium in Korean foods and estimate the internal doses. In this study, we have established the thorium measuring process based on the thorium extraction chemical process and alpha spectroscopic method. The concentration of Th-228, Th-230 and Th-232 in Korean vegetables (potato, sweet potato, radish, cabbage, hot pepper, garlic, onion and pumpkin) and fruits(apple, persimmon, orange, pear, grape) are measured and their internal doses are estimated.

Distribution of Th-230 and Th-228 in foods(II)

International Nuclear Information System (INIS)

Kang, Hee Dong; Kim, Wan; Lim, S. K.; Lee, S. A.; Choi, M. S.; Zheng, Y. C.; Kim, Do Sung

2004-02-01

Natural radioisotopes contained in foods can enter the human body by ingestion and contribute to internal doses to the population. It is necessary to measure the concentration of natural radioisotopes especially thorium in Korean foods and estimate the internal doses. In this study, we have established the thorium measuring process based on the thorium extraction chemical process and alpha spectroscopic method. The concentration of Th-228, Th-230 and Th-232 in Korean vegetables (potato, sweet potato, radish, cabbage, hot pepper, garlic, onion and pumpkin) and fruits(apple, persimmon, orange, pear, grape) are measured and their internal doses are estimated

Spectroscopy study after quasi-elastic collision in the system 208Pb+232Th at an incident energy of 17 MeV per nucleon

International Nuclear Information System (INIS)

Happ, T.

1989-01-01

In the present thesis by means of a particle-particle-γ and particle-particle-neutron coincidence experiment γ and neutron spectroscopic studies after quasi-elastic collisions at incident energies far above the Coulomb barrier were performed. For the study of the γ decay by the necessary correction of the Doppler shift the possibility results to study excitations in the projectile and in the target. So in the case of 232 Th beside the observation of the ground state band up to the spin 14 ℎ also a very large number of transitions from vibrational side bands. From the spectra the γ emission probabilities in dependence on the distance of closest approximation were extracted. (orig./HSI) [de

Loading of mass spectrometry ion trap with Th ions by laser ablation for nuclear frequency standard application.

Science.gov (United States)

Borisyuk, Petr V; Derevyashkin, Sergey P; Khabarova, Ksenia Y; Kolachevsky, Nikolay N; Lebedinsky, Yury Y; Poteshin, Sergey S; Sysoev, Alexey A; Tkalya, Evgeny V; Tregubov, Dmitry O; Troyan, Viktor I; Vasiliev, Oleg S; Yakovlev, Valery P; Yudin, Valery I

2017-08-01

We describe an original multisectional quadrupole ion trap aimed to realize nuclear frequency standard based on the unique isomer transition in thorium nucleus. It is shown that the system effectively operates on Th + , Th 2+ and Th 3+ ions produced by laser ablation of metallic thorium-232 target. Laser intensity used for ablation is about 6 GW/cm 2 . Via applying a bias potential to every control voltage including the RF one, we are able not only to manipulate ions within the energy range as wide as 1-500 eV but to specially adjust trap potentials in order to work mainly with ions that belong to energy distribution maximum and therefore to effectively enhance the number of trapped ions. Measurement of energy distributions of 232 Th + , 232 Th 2+ , 232 Th 3+ ions obtained by laser ablation allows us to define optimal potential values for trapping process. Observed number of ions inside trap in dependence on trapping time is found to obey an unusually slow - logarithmic decay law that needs more careful study.

Variable dead time counters. 1 - theoretical responses and the effects of neutron multiplication

International Nuclear Information System (INIS)

Lees, E.W.; Hooton, B.W.

1978-10-01

A theoretical expression is derived for calculating the response of any variable dead time counter (VDC) used in the passive assay of plutonium by neutron counting of the natural spontaneous fission activity. The effects of neutron multiplication in the sample arising from interactions of the original spontaneous fission neutrons is shown to modify the linear relationship between VDC signal and Pu mass. Numerical examples are shown for the Euratom VDC and a systematic investigation of the various factors affecting neutron multiplication is reported. Limited comparisons between the calculations and experimental data indicate provisional validity of the calculations. (author)

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

{sup 235}U(n,F) prompt fission neutron spectra

Energy Technology Data Exchange (ETDEWEB)

Maslov, M.V.; Tetereva, N.A. [Joint Institute of Nuclear and Energy Research, Minsk-Sosny (Belarus); Pronyaev, V.P.; Kagalenko, A.B. [Institute of Physics and Power Engineering, Obninsk (Russian Federation); Capote, R. [International Atomic Energy Agency, Vienna (Austria); Granier, T.; Morillon, B. [CEA, Centre DAM-IIe de France, 91 - Arpajon (France); Hambsch, F.J. [EC-JRC Institute for Reference Materials and Measurements, Geel (Belgium); Sublet, J.C. [CEA Cadarache, 13 - Saint Paul lez Durance (France)

2009-07-01

The longstanding problem of inconsistency of integral thermal data testing and differential prompt fission neutron spectra data (PFNS) is mostly due to rather poor fits of differential PFNS data in major data libraries. The measured database is updated by using modern standards including Manhart's evaluation of the spontaneous fission neutron spectra of {sup 252}Cf(sf). That largely removes the inconsistency of older thermal neutron-induced PFNS measurements with newest data of JRC IRMM by Hambsch et al. (2009). A phenomenological approach, developed by Kornilov et al. (1999), for the first-chance fission and extended for the emissive fission domain by Maslov et al. (2005) is calibrated at E{sub th} to predict both the PFNS average energy and PFNS shape up to 20 MeV. The latter is extremely important, since rather close values in fact correspond to quite discrepant spectra shapes, which influences reactor neutronics strongly. The proposed phenomenological representation of the PFNS reproduces both soft and hard energy tails of {sup 235}U(n{sub th},F) PFNS at thermal incident neutron energy E{sub th}. In the first-chance and emissive fission domain evaluated PFNS are consistent with the data by Ethvignot et al. (2005). A compiled MF=5 Endf/B-formatted file of the {sup 235}U(n,F) PFNS largely removes the inconsistencies of the evaluated differential PFNS with integral data benchmarks. Almost perfect fits are attained for available differential PFNS data from E{sub th} up to E{sub n}=14.7 MeV, with few exceptions at E{sub n}=2.9 and E{sub n}=5 MeV. Fast integral critical experiment like GODIVA or Flattop benchmarks might be reproduced almost with the same accuracy as with the PFNS of the major data libraries. That reveals a rather delicate compensation effect, since present and previous PFNS shapes are drastically different from each other. Thermal assemblies benchmarking reveals positive biases in k(eff), which might be attributed to the influence of

Fission theory and actinide fission data

Energy Technology Data Exchange (ETDEWEB)

Michaudon, A.

1975-06-01

The understanding of the fission process has made great progress recently, as a result of the calculation of fission barriers, using the Strutinsky prescription. Double-humped shapes were obtained for nuclei in the actinide region. Such shapes could explain, in a coherent manner, many different phenomena: fission isomers, structure in near-threshold fission cross sections, intermediate structure in subthreshold fission cross sections and anisotropy in the emission of the fission fragments. A brief review of fission barrier calculations and relevant experimental data is presented. Calculations of fission cross sections, using double-humped barrier shapes and fission channel properties, as obtained from the data discussed previously, are given for some U and Pu isotopes. The fission channel theory of A. Bohr has greatly influenced the study of low-energy fission. However, recent investigation of the yields of prompt neutrons and γ rays emitted in the resonances of {sup 235}U and {sup 239}Pu, together with the spin determination for many resonances of these two nuclei cannot be explained purely in terms of the Bohr theory. Variation in the prompt neutron and γ-ray yields from resonance to resonance does not seem to be due to such fission channels, as was thought previously, but to the effect of the (n,γf) reaction. The number of prompt fission neutrons and the kinetic energy of the fission fragments are affected by the energy balance and damping or viscosity effects in the last stage of the fission process, from saddle point to scission. These effects are discussed for some nuclei, especially for {sup 240}Pu.

Fission gas in thoria

Energy Technology Data Exchange (ETDEWEB)

Kuganathan, Navaratnarajah, E-mail: n.kuganathan@imperial.ac.uk [Department of Materials, Faculty of Engineering, Imperial College, London, SW7 2AZ (United Kingdom); Ghosh, Partha S. [Material Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Galvin, Conor O.T. [Department of Materials, Faculty of Engineering, Imperial College, London, SW7 2AZ (United Kingdom); Arya, Ashok K. [Material Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Dutta, Bijon K. [Homi Bhabha National Institute, Trombay, Mumbai 400 094 (India); Dey, Gautam K. [Material Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Grimes, Robin W. [Department of Materials, Faculty of Engineering, Imperial College, London, SW7 2AZ (United Kingdom)

2017-03-15

The fission gases Xe and Kr, formed during normal reactor operation, are known to degrade fuel performance, particularly at high burn-up. Using first-principles density functional theory together with a dispersion correction (DFT + D), in ThO{sub 2} we calculate the energetics of neutral and charged point defects, the di-vacancy (DV), different neutral tri-vacancies (NTV), the charged tetravacancy (CTV) defect cluster geometries and their interaction with Xe and Kr. The most favourable incorporation point defect site for Xe or Kr in defective ThO{sub 2} is the fully charged thorium vacancy. The lowest energy NTV in larger supercells of ThO{sub 2} is NTV3, however, a single Xe atom is most stable when accommodated within a NTV1. The di-vacancy (DV) is a significantly less favoured incorporation site than the NTV1 but the CTV offers about the same incorporation energy. Incorporation of a second gas atom in a NTV is a high energy process and more unfavourable than accommodation within an existing Th vacancy. The bi-NTV (BNTV) cluster geometry studied will accommodate one or two gas atoms with low incorporation energies but the addition of a third gas atom incurs a high energy penalty. The tri-NTV cluster (TNTV) forms a larger space which accommodates three gas atoms but again there is a penalty to accommodate a fourth gas atom. By considering the energy to form the defect sites, solution energies were generated showing that in ThO{sub 2−x} the most favourable solution equilibrium site is the NTV1 while in ThO{sub 2} it is the DV. - Highlights: • We have considered Xe and Kr in point defects and defect clusters (neutral and charged) using Density Functional Theory (DFT) with a dispersion correction. • The most favourable charge state for a point defect (vacancy or interstitial) is that with full ionic charge and we have found that in all cases gas atoms occupy the fully charged vacancy sites. • The number of fission gas atoms accommodated in ThO{sub 2} is

Future research program on prompt γ-ray emission in nuclear fission

Science.gov (United States)

Oberstedt, S.; Billnert, R.; Hambsch, F.-J.; Lebois, M.; Oberstedt, A.; Wilson, J. N.

2015-12-01

In recent years the measurement of prompt fission γ-ray spectra (PFGS) has gained renewed interest, after about forty years since the first comprehensive studies of the reactions 235U(n th , f), 239Pu(n th ,f) and 252Cf(sf). The renaissance was initiated by requests for new values especially for γ-ray multiplicity and average total energy release per fission in neutron-induced fission of 235U and 239Pu. Both isotopes are considered the most important ones with respect to the modeling of innovative cores required for the Generation-IV reactors, the majority working with fast neutrons. During the last 5 years we have conducted a systematic study of spectral data for thermal-neutron-induced fission on 235U and 241Pu as well as for the spontaneous fission of 252Cf with unprecedented accuracy. From the new data we conclude that those reactions do not considerably contribute to the observed heat excess and suspect other reactions playing a significant role. Possible contributions may originate from fast-neutron-induced reactions on 238U, which is largely present in the fuel, or from γ-induced fission from neutron capture in the construction material. A first experiment campaign on prompt γ-ray emission from fast-neutron-induced fission on 235,238U was successfully performed in order to test our assumptions. In the following we attempt to summarize, what has been done in the field to date, and to motivate future measurement campaigns exploiting dedicated neutron and photon beams as well as upcoming highly efficient detector assemblies.

Ternary Fission of U235 by Resonance Neutrons

International Nuclear Information System (INIS)

Kvitek, I.; Popov, Ju.P.; Rjabov, Ju.V.

1965-01-01

Recently a number of papers have appeared indicating considerable variations in the ratio of the ternary-fission cross-section to the binary-fission cross-section of U 235 on transition from one neutron resonance to another. However, such variations have not been discovered in U 233 and Pu 239 . The paper reports investigations of the ternary fission of U 235 by neutrons with an energy of 0.1 to 30 eV. Unlike other investigators of the ternary fission of U 235 , we identified the ternary-fission event by the coincidence of one of the fission fragments with a light long-range particle. This made it passible to separate ternary fissions from the possible contribution of the (n, α)reaction. The measurements were performed at the fast pulsed reactor of the Joint Institute for Nuclear Research by the time-of-flight method. A flight length of 100 m was used, giving a resolution of 0.6 μs/m. Gas scintillation counters filled with xenon at a pressure of 2 atm were used to record the fission fragments and the light long-range particle. A layer of enriched U 235 ∼2 mg/cm 2 thick and ∼300 cm 2 in area was applied to an aluminium foil 20-fim thick. The scintillations from the fission fragments were recorded in the gas volume on one side of the foil and those from the light long-range particles in that on the other. In order to assess the background (e.g . coincidences of the pulse from a fragment with that from a fission gamma quantum or a proton from the (n, p) reaction in the aluminium foil), a measurement was carried out in which the volume recording the long-range particle was shielded with a supplementary aluminium filter 1-mm thick. The results obtained indicate the absence of the considerable variations in the ratio between the ternary-and binary- fission cross-sections for U 235 that have been noted by other authors. Measurements showed no irregularity in the ratio of the cross-sections in the energy range 0.1 to 0.2 eV. The paper discusses the possible effect of

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

International Nuclear Information System (INIS)

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

2000-01-01

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

PFPF canister counter for foreign plutonium (PCAS-3) hardware operations and procedures manual

International Nuclear Information System (INIS)

Menlove, H.O.; Baca, J.; Kroncke, K.E.; Miller, M.C.; Takahashi, S.; Seki, S.; Inose, S.; Yamamoto, T.

1993-01-01

A neutron coincidence counter has been designed for the measurement of plutonium powder contained in tall storage canisters. The counter was designed for installation in the Plutonium Fuel Production Facility fabrication plant. Each canister contains from one to five cans of PuO 2 . The neutron counter measures the spontaneous-fission rate from the plutonium and, when this is combined with the plutonium isotopic ratios, the plutonium mass is determined. The system can accommodate plutonium loadings up to 12 kg, with 10 kg being a typical loading. Software has been developed to permit the continuous operation of the system in an unattended mode. Authentication techniques have been developed for the system. This manual describes the system and its operation and gives performance and calibration parameters for typical applications