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Sample records for 171er 181hf 233pa

  1. Neutron data evaluation of 233Pa

    Consistent evaluation of 233 Pa 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 calculated, using fission cross section data description as a major constraint. The direct excitation of ground state band levels is calculated within rigid rotator model. Average resonance parameters are provided, which reproduce evaluated cross sections in the range of 16.5-70.9 keV. This work is performed under the Project Agreement B-404 with the International Science and Technology Center (Moscow). The Financing Party for the Project is Japan. (author)

  2. 232 Th - 233 Pa separation by extraction chromatography

    Thorium and protactinium behavior in extraction chromatography systems is presented, aiming its separation by selective retention of the micro constituent on the column. TBP/alumina, TBP/voltalef UF 300, TOA/alumina and TOA/voltalef UF 300 systems were verified. Column preparation as well the 233 Pa removal conditions were settled. The best 232 Th separation from its irradiation product, 233 Pa, has been achieved by using TBP/voltalef UF 300 system. 233 Pa was selectively retained on column from 10 M HCl solutions and eluted with 3 M HCl. (author)

  3. Atomic 'After Effects' Following 181Hfβ--Decay

    Strong evidence of atomic 'after effects' following β--decay of 181Hf was observed from perturbed angular correlation (PAC) studies in different viscous and non-viscous molecular solutions and in ionic as well as non-ionic solutions. In non-viscous acetone and H2O solutions, the PAC spectra have been found to be completely different to what was expected considering molecular motions in these media. Similarly, in the glycerol-H2O system, PAC spectra remain significantly unchanged with the change of viscosity indicating that molecular motions are not reflected in these media. Rather, perturbations from the interaction of the nucleus-excited atomic state, which was so far considered to be absent for 181Hf β--decay, have been found to be dominant. The atomic shell recovery times inmolecular liquids have been found to be in the range 50-150 nsec. In insulating solid HfCl4 medium, however, the PAC spectrum indicates that the atomic shell following 181Hf β--decay remains unchanged within the lifetime of the intermediate state. The lifetime for the 615 keV level has been remeasured and a value of T1/2=12.1±0.1 nsec only has been obtained. This value, although in strong disagreement with the earlier reported value (17.83 μsec), helps explain atomic 'after effects' in 181Hf β--decay.

  4. The 233Pa fission cross-section measurement and evaluation

    233Pa is a conspicuous example of strongly discrepant data in the accepted nuclear data evaluations. The precise knowledge of the neutron-induced reaction cross-section of this highly β-active nuclide (T1/2 = 27.0 d) is essential for the successful implementation of the thorium-based fuel cycle in advanced nuclear applications. The reactions involving 233Pa are responsible for the balance of nuclei as well as the average number of prompt fission neutrons in a contemplated reactor scenario. In an IAEA report, it is stated that there is a need to know the 233Pa(n, f) cross-section with an accuracy of 20%. The different evaluated neutron data libraries show, however, a difference of a factor of two for this cross-section. It has previously been deemed not feasible to measure this reaction directly due to its short half-life, high radioactivity and the in-growth of the daughter product 233U. Hence, the entries in the neutron libraries are based on theoretical predictions, which explains the large discrepancies. As reported recently the neutron-induced fission cross-section of 233Pa has been measured for the first time directly with mono-energetic neutrons from 1.0 to 3.0 MeV at the Van-de-Graaff facility of the IRMM. In the meantime, during two further measurement campaigns, the energy range has been extended up to 8.5 MeV. The experimental results will be presented together with recent model calculations of the fission cross-section applying the statistical model code STATIS, which improve the cross-section evaluation up to the second chance fission threshold. (authors)

  5. Study on the adsorption of 233Pa in glass

    It is intended to examine the adsorption of protactinium on glass in relation to pH, presence of complexing agents concentration and type of electrolytes. The study was made by using carrier-free 233Pa solution and Pyrex glass tube was selected as adsorbent glass material surface. The adsorption curve of protactinium on glass surface as a function of the pH of the tracer solution showed the existence of two pronounced adsorption regions. It was found that this adsorption can be reduced by using electrolytes or complexing agents. Desorption of protactinium previously adsorbed on the Pyrex glass tube was also studied. Hidrochloric, oxalic and hydrofluoric acid solutions were used for the desorption experiments. (Author)

  6. 231Pa and 233Pa neutron-induced fission up to 20 MeV

    Consistency of neutron-induced fission cross section data of 231Pa and 233Pa and data extracted from transfer reactions is investigated. Present estimate of 233Pa(n,f) fission cross section is supported by smooth level density parameter systematic, validated in case of 231Pa(n,f) data description up to En=20 MeV. The fission probabilities of Pa, fissioning in 231,233Pa(n,nf) reactions, are defined by fitting (3He,d) or (3He,t) transfer reaction data

  7. Calculation of the neutron-induced fission cross section of 233Pa

    Since very recently, experimental data for the energy dependence of the 233Pa(n,f) cross section are finally available. This has stimulated a new, self-consistent cross section evaluation for the system n+233Pa in the incident neutron energy range 0.01-6 MeV. The results are quite different compared to earlier evaluation attempts. Since 233Pa is an important intermediary in the thorium based fuel cycle, its neutron reaction cross sections are key parameters in the modeling of future advanced reactor concepts

  8. 231Pa and 233Pa Neutron-Induced Fission Data Analysis

    The 231Pa and 233Pa neutron-induced fission cross-section database is analyzed within the Hauser-Feshbach approach. The consistency of neutron-induced fission cross-section data and data extracted from transfer reactions is investigated. The fission probabilities of Pa, fissioning in 231,233Pa(n,nf) reactions, are defined by fitting (3He,d) or (3He,t) transfer-reaction data. The present estimate of the 233Pa(n,f) fission cross section above the emissive fission threshold is supported by smooth level-density parameter systematics, validated in the case of the 231Pa(n,f) data description up to En =20 MeV

  9. 233Pa(2nth, f) cross-section determination using a fission track technique

    The 233Pa(2nth, f) cross-section has been experimentally determined for the first time using a fission track technique. It was found to be 4834 ± 57 b, which is significantly high and thus is very important for 232Th-233U-based fuel in advanced heavy-water reactors (AHWR) and accelerator-driven sub-critical systems (ADSs). This is because the 233Pa is an important intermediary in the thorium-based fuel cycle and thus its fission cross-section is a key parameter in the modeling of AHWR and ADSs. The 233Pa(2nth, f) cross-section was calculated theoretically using the TALYS computer code and found to be in good agreement with the experimental value after normalization with respect to 241Am(2nth, f). (orig.)

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

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

  11. Study of the excited levels of 233Pa by the 237Np alpha decay

    The excited levels in 233Pa following the 237Np alpha decay have been studied, by performing different experiences to complete available data and supply new information. Thus, two direct alpha spectrum measurement, one alpha-gamma bidimensional coincidence experiment, three gamma-gamma and gamma-X ray coincidences and some other measurements of the gamma spectrum, direct and coincident with alpha-particles have been made. These last experiences have allowed to obviate usual radiochemical separation methods, the 233Pa radioactive descendent interferences being eliminated by means of the coincidence technic. As a result, a primary decay scheme has been elaborated, including 15 new gamma transitions and two new levels, not observed in the most recent works. (Author) 60 refs

  12. 233Pa(n, f) cross section up to En=8.5 MeV

    The energy dependence of the neutron-induced fission cross section of 233Pa has been measured directly for the first time from the fission threshold up to En=8.5 MeV. This reaction plays an important role in the thorium-uranium fuel cycle, and is thus of interest for the design and modeling of advanced reactor and transmutation facilities. The existing information in the ENDF/B-VI and JENDL-3.3 evaluated nuclear data files differ by a factor of two for the 233Pa(n, f) cross section values and show different fission threshold energies. Our new experimental data give lower cross section values than both evaluations and resolves the question about the threshold energy. In addition to the experimental investigation, also a new theoretical calculation of the reaction cross section has been performed with the statistical model code STATIS, showing a good agreement with the experimental data

  13. 232Th, 233Pa, and 234U capture cross-section measurements in moderated neutron flux

    The Th-U cycle was studied through the evolution of a 100 μg 232Th sample irradiated in a moderated neutron flux of 8.01014 n/cm2/s, intensity close to that of a thermal molten salt reactor. After 43 days of irradiation and 6 months of cooling, a precise mass spectrometric analysis, using both TIMS and MC-ICP-MS techniques, was performed, according to a rigorous methodology. The measured thorium and uranium isotopic ratios in the final irradiated sample were then compared with integral simulations based on evaluated data; an overall good agreement was seen. Four important thermal neutron-capture cross-sections were also extracted from the measurements, 232Th (7.34±0.21 b), 233Pa (38.34±1.78 b), 234U (106.12±3.34 b), and 235U (98.15±11.24 b). Our 232Th and 235U results confirmed existing values whereas the cross-sections of 233Pa and 234U (both key parameters) have been redefined

  14. Comparison of 233Pa(2nth, f) cross-section determined by fission track technique with TALYS 1.2

    In the last decade, an appreciable amount of work has been done in the new concepts of advanced heavy-water reactors (AHWR) and accelerator-driven sub-critical systems (ADSs) in the field of nuclear energy. In AHWR, 232Th - 233U is the primary fuel for power generation in AHWR and ADS. In the 232Th - 233U cycle, the fissile nucleus 233U is generated by two successive β-decays after a neutron capture of the fertile nucleus 232Th. The isotope 233Pa (T1/2 = 26.9 days) governs the production of 233U. Therefore, the neutron induced fission reaction with 233Pa greatly influences the production of 233U. The present work is carried out with the objective to study the 233Pa(2nth, f) reaction cross-section using the well known fission track-technique. The fission cross section has been experimentally found to be 4834 ± 57 barns, which is significantly high and thus is very important for 232Th-233U based fuel in advanced heavy water reactors (AHWR) and accelerator driven sub-critical systems (ADSs). In the present work, the 233Pa(2nth, f) cross-section has also been calculated theoretically using nuclear reaction model based computer code TALYS 1.2. The theoretically calculated 233Pa(2nth, f) cross-section found to be in good agreement with the experimental value after normalization with respect to 241Am(2nth, f). (author)

  15. Update of 233U, 229-232Th and 230-233Pa Fission Data

    The influence of the 235U(n,f) and 239Pu(n,f) prompt fission neutron spectra (PFNS) on modeling of integral benchmarks was estimated to be significant. For 233U(n,f) PFNS similar sensitivities could be envisaged. For the variety of Th/U fuels and systems, ranging from metal fast to deep thermal solutions, large positive/negative swings in calculated Keff can be expected. Th/U fuelled core criticality calculations would be sensitive to the modelled soft tail of fission neutrons or deficiency of hard tail fission neutrons, as revealed for U and Pu fuels. The deficiency of the 233U(nth,f) PFNS, adopted for the ENDF/B-VII.0. could be traced back to the 'propagation' of calculated 235U(nth,f) PFNS shape at En= 0.5 MeV. At higher energies, average energies of PFNS coincide only at ∼5 MeV, at other En the average energies and spectra shapes are drastically different. However, it might be argued that the response of the criticality benchmark calculations for the 233U thermal and fast systems would be similar to that observed for the PFNS of 239Pu. Our approach allowed to solve the longstanding problem of inconsistency of 235U integral data testing and differential prompt fission neutron spectra data, a similar approach may hold for 233U. Using modified PFNS, we may avoid arbitrary tweaking of neutron cross sections or neutron multiplicities for Th/U fuel-cycle related nuclides (233U, 229,230,231,232Th and 230,231,232,233Pa) to compensate the ill-defined shape of 233U PFNS. For metal fast benchmarks much would depend on the inelastic scattering cross section of 233U, which should be considered rather uncertain at the moment. The unrealistic evaluations of poorly investigated cross sections related to the Th/U fuel cycle could be excluded by consistent analysis of the available fission data base. The evaluation of 229,230,231,232Th(n,f) and 230,231,232,233Pa(n,f) cross sections could be supplemented by description of surrogate and ratio surrogate fission data, coming from

  16. Measurement and calculation of the 233Pa fission cross-section for advanced fuel cycles

    The energy dependence of the neutron-induced fission cross-section of 233Pa has been measured directly for the first time from the fission threshold up to 8.5 MeV. This fission cross-section is a key ingredient in feasibility studies on fast reactors and accelerator driven systems based on the Th-U fuel cycle. The results are at strong variance with the existing evaluations. The new experimental data give lower cross-section values and resolve the question about the threshold energy. Additionally a new theoretical calculation of the reaction cross-section has been performed with the statistical model code STATIS, showing a very good agreement with the experimental data. (authors)

  17. Calculation of the neutron induced fission cross-section of 233Pa up to 20 MeV

    Since very recently, direct measurements of the 233Pa(n,f) cross-section are available in the energy range from 1.0 to 8.5 MeV. This has stimulated a new, self-consistent, neutron cross-section evaluation for the n+233Pa system, in the incident neutron energy range 0.01-20 MeV. Since higher fission chances are involved also the lighter Pa-isotopes had to be re-evaluated in a consistent manner. The results are quite different compared to earlier evaluation attempts. Since 233Pa is a key isotope in the thorium based fuel cycle the quality of its reaction cross-sections is important for the modeling of future advanced fuel and reactor concepts. The present status of the evaluated libraries is that they differ by a factor of two in the absolute fission cross-section and also in the threshold energy value

  18. The study of 233Pa having the effect on reactivity swings during reactors start up and shutdown

    233Pa is an important nuclide in the Th-U conversion chain with a long half-life (27.4 d) and has large neutron absorption cross section, which influence the Th-U conversion ratio fuel and the operation of a Th-U fuelled reactor. On the basis of transport diffusion module and burn up module of the Dragon package, which gets the direct ratio relation- ship between 233Th, 233Pa and 233U concentration and the neutron flux levels, and gets the 233Pa having the effect on re activity swings during reactors start up and shutdown. The higher the neutron flux levels, the greater the loss of reactivity after reactors start up and the more significant increase of reactivity after reactors shutdown. Through the study of the 233Pa having the effect on reactivity swings during reactors start up and shutdown, it provides reference data for reactors using Th-U fuel with safe operation when reactors start up and shutdown. (authors)

  19. Determination of the 233Pa(n,f) reaction cross-section for thorium-fuelled reactors

    A direct measurement of the energy-dependent neutron-induced fission cross-section of 233Pa has been performed for the first time. The 233Pa isotope plays a key role in the thorium fuel cycle, serving as an intermediate isotope in the formation of the uranium fuel material. Since fission is one of the reactions determining the balance of nuclei at a given time, the cross-section is of vital importance for any calculation of a thorium-fuel-based nuclear-power device. In a first measurement series, four energies between 1.0 and 3.0 MeV were measured. The resulting average above-threshold cross-section found is lower than all literature values. (authors)

  20. Neutron-induced fission cross section of 233Pa between 1.0 and 3.0 MeV.

    Tovesson, F; Hambsch, F J; Oberstedt, A; Fogelberg, B; Ramström, E; Oberstedt, S

    2002-02-11

    The energy dependent neutron-induced fission cross section of 233Pa has for the first time been measured directly with monoenergetic neutrons. This nuclide is an important intermediary in a thorium based fuel cycle, and its fission cross section is a key parameter in the modeling of future advanced fuel and reactor concepts. A first experiment resulted in four cross section values between 1.0 and 3.0 MeV, establishing a fission threshold in excess of 1 MeV. Significant discrepancies were found with a previous indirect experimental determination and with model estimates. PMID:11863801

  1. Emission probabilities of the KX-rays following the decay of 237 Np in equilibrium with 233 Pa

    Following participation in the international EUROMET project No. 416 and after our recent paper, concerning the measurement of the emission probability values of the main gamma-rays of 237 Np in equilibrium with 233 Pa, a complementary work has been done in the frame of the collaboration LNHB-VNIIM-KRI-IFIN (with the support of 'Ministere des Affaires Etrangeres' of France). The purpose was to determine the photon emission probabilities for the KX-rays following the decay of these two nuclides. Two different analysis methods have been used. At first, the KX-rays region was analyzed by fitting Voigt functions according to a least squares procedure, included in 'COLEGRAM' deconvolution code. In the second case, the analysis was performed by using full response functions. Thus, the work allowed the determination of the photon emission probabilities with a relative uncertainty of about 2%. This accurate set of data is useful in calculations related to the atomic level scheme of 237 Np/233 Pa and in X-ray spectrometry based applications. (authors)

  2. Electric-quadrupole interaction at 181Hf/181Ta in Hf doped MgB2 and HfB2: a perturbed angular correlation study

    Hyperfine interaction of the 181Hf/181Ta is studied in HfB2 and Hf doped MgB2 by perturbed angular correlation spectroscopy. Nuclear quadrupole constants and attenuation factors were extracted from the data. Quadrupole coupling constant shows that Hf goes to three inequivalent sites in MgB2. There is sign of HfB2 formation at high temperature. (author)

  3. New calculation for the neutron-induced fission cross section of 233Pa between 1.0 and 3.0 MeV

    The 233Pa(n,f) cross section, a key ingredient for fast reactors and accelerators driven systems, was measured recently with relatively good accuracy [F. Tovesson et al., Phys. Rev. Lett. 88, 062502 (2002)]. The results are at strong variance with accepted evaluations and an existing indirect experiment. This circumstance led us to perform a quite detailed and complete evaluation of the 233Pa(n,f) cross section between 1.0 and 3.0 MeV, where use of our newly developed routines for the parametrization of the nuclear surface and the calculation of deformation parameters and level densities (including low-energy discrete levels) were made. The results show good quantitative and excellent qualitative agreement with the experimental direct data obtained by Tovesson et al. [F. Tovesson et al., Phys. Rev. Lett. 88, 062502 (2002)]. Additionally, our methodology opens new possibilities for the analysis of subthreshold fission and above threshold second-chance fission for both 233Pa and its decay product 233U, as well as other strategically important fissionable nuclides

  4. Determination of the 233Pa(n, f) reaction cross section from 0.5 to 10 MeV neutron energy using the transfer reaction 232Th(3He, p)234Pa

    The fission probability distributions of 232,233,234Pa and 231Th have been measured up to an excitation energy of 15 MeV, using the transfer reactions 232Th(3He, t)232Pa, 232Th(3He, d)233Pa, 232Th(3He, p)234Pa and 232Th(3He, 4He)231Th. From these measurements, the neutron induced fission cross sections of 231Pa, 233Pa and 230Th have been determined from the product of the fission probabilities of 232Pa, 233Pa and 231Th respectively with the calculated compound nucleus formation cross sections in the 231Pa+n, 233Pa+n and 230Th+n reactions. The validity of the applied method has been successfully tested with the existing neutron induced fission cross sections of 230Th and 231Pa. Special emphasis is put on the 233Pa(n, f) reaction which is of importance for thorium fueled nuclear reactors. Based on a statistical model analysis of the neutron induced fission cross section as a function of neutron energy, it has been possible to determine the barrier parameters of the 234Pa fissioning nucleus. Cross sections for the compound nucleus inelastic scattering 233Pa(n, n') and radiative capture 233Pa(n, γ) reactions have also been calculated and compared with recent evaluations

  5. Correlation of ibuprofen bioavailability with gastrointestinal transit by scintigraphic monitoring of 171Er-labeled sustained-release tablets

    External gamma scintigraphy was used to monitor the gastrointestinal (GI) transit of radiolabeled sustained-release tablets containing 800 mg ibuprofen in eight fasted healthy volunteers. Ibuprofen serum concentrations were determined from blood samples drawn sequentially over a 24-hr period. Serum concentrations and related parameters were correlated to the position of the dosage form in the GI tract from the scintiphotos. The sustained-release tablets were radiolabeled intact utilizing a neutron activation procedure, by incorporating 0.18% of 170Er2O3 (enriched to greater than 96% 170Er) into the bulk formulation. After manufacture of the final dosage forms, the tablets were irradiated in a neutron flux (4.4 x 10(13) n/cm2.sec) for 2 min, converting the stable 170Er to radioactive 171Er (t1/2 = 7.5 hr). Each tablet contained 50 microCi of 171Er at the time of administration. The scintigraphy studies suggested that the greatest proportion of ibuprofen was absorbed from this dosage form while the tablet was in the large bowel. The dosage forms eroded slowly in the small bowel and appeared to lose their integrity in the large bowel. In vitro studies showed only minimal effects of the neutron irradiation procedure on the dosage form performance

  6. Fission barrier formula and its application to thorium based fuel cycle: calculation of fission cross sections for 233Pa (n, f) reaction

    Recently, direct measurements of fission cross-sections for 233Pa (n, f) reaction are available which stimulated the calculation of fission cross-sections for this reaction. For this calculation we have derived an analytical barrier formula based on microscopic-macroscopic description by fitting the actinide fission barrier data for the double humped barrier. Pairing effects have also been taken into account. The cross sections calculated for using the analytical barrier formula with the code EMPIRE 2.19 give better agreement with the available measurements. (author)

  7. TDPAC studies of the metal-binding sites in serum transferrin: comparison between /sup 181/Hf-labeled human- and rat-serum transferrin

    Appel, H.; Duffield, J.; Taylor, D.M.; Then, G.M.; Thies, W.G.

    1987-12-01

    The binding of hafnium to human serum transferrin was studied using the time differential perturbed angular correlation (TDPAC-) technique. The samples were prepared in vitro by adding /sup 181/Hf-NTA solution to human serum. Two specific electric quadrupole interactions were observed, which correspond to two well-defined binding configurations. Their relative intensities depend on the pH, salt- and hafnium-concentrations, and on the incubation time. The present data may be compared with the results of a previous rat serum study, where the hafnium binding to transferrin behaved rather similarly. Small but significant differences, however, can be deduced from the TDPAC-parameters for these human and rat transferrin species. For either binding configuration, the electric field gradient (EFG) is slightly higher in the case of rat transferrin. The most characteristic difference, however, concerns the asymmetry parameter eta 2 of the second binding configuration, which is about 10% smaller for rat serum transferrin. The TDPAC-technique might be used as a sensitive and reliable analytical method to study the metal-binding sites of different transferrin species.

  8. Contribution have the survey of the transformation {sup 181}Hf {yields} {sup 181}Ta (17 {mu}s) {yields} {sup 181}Ta; Contribution a l'etude de la transformation {sup 181}Hf {yields} {sup 181}Ta (17 {mu}s) {yields} {sup 181}Ta

    Baullini, R.; Chaminade, R.; Desneiges, P.; Grjebine, T.; Quidort, J.; Wahl, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1953-07-01

    The metastable state of Ta, whose period is around 20 microseconds, has been discovered by De BENEDETTI and Mc GOWAM who done measurements of deferred coincidences between the particles beta and the electrons of conversion given out by the hafnium radiated by thermal neutrons. We measured the period of {sup 181}Ta{sup *} by measures of deferred coincidences {beta}-e{sup -} and {beta}-{gamma}. A method of survey of the specter of photons amplitudes emitted by {sup 181}Ta{sup *} has been fit. This method permitted to solve the presence of {gamma} in the radiation emitted in synchronism with the deexcitation of {sup 181}Ta{sup *}. Finally in a last chapter, we propose a method of dosage of the {sup 181}Hf in presence of other radioelements. (M.B.) [French] L'etat metastable de Ta, dont la periode est voisine de 20 microsecondes, a ete decouvert par DE BENEDETTI et Mc GOWAM qui effectuaient des mesures de coincidences differees entre les particules beta et les electrons de conversion emis par du hafnium irradie par des neutrons thermiques. Nous avons mesure la periode de {sup 181}Ta{sup *} par des mesures de coincidences differees {beta}-e{sup -} et {beta}-{gamma}. Une methode d'etude du spectre d'amplitudes des photons emis par {sup 181}Ta{sup *} a ete mise au point. Cette methode a permis d'eclaircir la presence de {gamma} dans le rayonnement emis en synchronisme avec la desexcitation de {sup 181}Ta{sup *}. Enfin dans un dernier chapitre, on proposera une methode de dosage du {sup 181}Hf en presence d'autres radioelements. (M.B.)

  9. Molecular level characterization of diatom-associated biopolymers that bind 234Th, 233Pa, 210Pb, and 7Be in seawater: A case study with Phaeodactylum tricornutum

    Chuang, Chia-Ying; Santschi, Peter H.; Xu, Chen; Jiang, Yuelu; Ho, Yi-Fang; Quigg, Antonietta; Guo, Laodong; Hatcher, Patrick G.; Ayranov, Marin; Schumann, Dorothea

    2015-09-01

    In order to investigate the importance of biogenic silica associated biopolymers on the scavenging of radionuclides, the diatom Phaeodactylum tricornutum was incubated together with the radionuclides 234Th, 233Pa, 210Pb, and 7Be during their growth phase. Normalized affinity coefficients were determined for the radionuclides bound with different organic compound classes (i.e., proteins, total carbohydrates, uronic acids) in extracellular (nonattached and attached exopolymeric substances), intracellular (ethylene diamine tetraacetic acid and sodium dodecyl sulfate extractable), and frustule embedded biopolymeric fractions (BF). Results indicated that radionuclides were mostly concentrated in frustule BF. Among three measured organic components, Uronic acids showed the strongest affinities to all tested radionuclides. Confirmed by spectrophotometry and two-dimensional heteronuclear single quantum coherence-nuclear magnetic resonance analyses, the frustule BF were mainly composed of carboxyl-rich, aliphatic-phosphoproteins, which were likely responsible for the strong binding of many of the radionuclides. Results from this study provide evidence for selective absorption of radionuclides with different kinds of diatom-associated biopolymers acting in concert rather than as a single compound. This clearly indicates the importance of these diatom-related biopolymers, especially frustule biopolymers, in the scavenging and fractionation of radionuclides used as particle tracers in the ocean.

  10. Emission probabilities of gamma rays from the decay of 233Pa and 238Np, and the thermal neutron capture cross section of 237Np

    In order to determine the thermal neutron capture cross section of 237Np, the relevant γ emission probabilities of the 312-keV γ-ray from the decay of 233Pa and the 984-keV γ-ray from the decay of 238Np are deduced from the ratio of the emission rate to the activity. The emission rate and activity are measured with a Ge detector and a Si detector, respectively. The measured emission probability for 312-keV γ-ray is 41.6±0.9% and that for 984-keV γ-ray is 25.2±0.5%. The emission probabilities are used to correct the thermal neutron capture cross section of 237Np reported previously, and gives 168±6b. The neutron capture cross section is also determined as 169±6b by α-ray spectroscopic method. The measured emission probabilities and capture cross section are compared with others from references. By averaging these values deduced by different methods, the value of 169±4b is recommended as the thermal neutron capture cross section of 237Np for 2,200 m/s neutrons. (author)

  11. Determination of the 233Pa(n, f) reaction cross-section from 10.5 to 16.5 MeV neutron energy by surrogate ratio method

    In the present work, we have employed surrogate ratio method to derive 233Pa(n,f) cross sections from the measurement of the ratio of the fission decay probabilities of 234Pa and 236U compound systems at same excitation energy over the excitation energy range of 16.0 MeV to 22.0 MeV, that are formed in 232Th(6Li, α)-234Pa and 232Th(6Li, d)-236U transfer reactions

  12. Determination of the 233Pa(n,f) reaction cross section from 11.5 to 16.5 MeV neutron energy by the hybrid surrogate ratio approach

    A new hybrid surrogate ratio approach has been employed to determine neutron-induced fission cross sections of 233Pa in the energy range of 11.5 to 16.5 MeV for the first time. The fission probability of 234Pa and 236U compound nuclei produced in 232Th(6Li, α)234Pa and 232Th(6Li, d)236U transfer reaction channels has been measured at Elab=38.0 MeV in the excitation energy range of 17.0 to 22.0 MeV within the framework of the absolute surrogate method. The 233Pa(n,f) cross sections are then deduced from the measured fission decay probability ratios of 234Pa and 236U compound nuclei using the surrogate ratio method. The 233Pa(n,f) cross section data from the present experiment along with the data from the literature, covering the neutron energy range of 1.0 to 16.5 MeV have been compared with the predictions of statistical model code EMPIRE-2.19. While the present data are consistent with the model predictions, there is a discrepancy between the earlier experimental data and EMPIRE-2.19 predictions in the neutron energy range of 7.0 to 10.0 MeV

  13. Determination of the neutron fission cross-section for 233Pa from 0.5 to 10 MeV using the transfer reaction 232Th(3He,pf)234Pa

    Neutron induced fission cross-section of 233Pa in the fast neutron energy range from 0.5 to 10 MeV was determined for the first time as a two term product of the fission probability of 234Pa nucleus and the same compound nucleus formation cross-section. The first term was measured with the transfer reaction 232Th(3He,p) 234Pa while the second one was calculated. The tendency of the resulting data to agree with the existing evaluated one, is a proof for the validity of the utilised method. (author)

  14. Determination of the 233Pa(n, γ) capture cross section up to neutron energies of 1 MeV using the transfer reaction 232Th(3He, p)234Pa*

    The γ-ray emission probability distribution of 234Pa* has been measured between 5.2 and 6.2 MeV excitation energy using the transfer reaction 232Th(3He, p)234Pa* at an incident 3He energy of 24 MeV. The experimental set-up is made of four liquid scintillator C6D6 detectors and four Si telescopes arranged to detect γ rays and charged particles in coincidence. In order to determine the total number of γ-ray cascades in a given nucleus, the raw experimental detected gamma-ray events have to be corrected by the weighting function technique. This weighting requires complete knowledge of the efficiency and response functions for the C6D6 detector set-up and surroundings. These have been determined experimentally using gamma-ray sources, inelastic scattering reactions and transfer reactions on light nuclei. Simulations which reproduce successfully the detector response and efficiency are presented. From these measurements, the (n, γ) capture cross section of 233Pa, in the neutron energy range 0 to 1 MeV, has been deduced via the product of the measured γ emission probability of 234Pa* with the calculated compound nucleus formation cross section of the reaction 233Pa + n. A comparison between existing data bases or recent predictions and the present results is also made

  15. Study of cation-localisation in apatite and orthophosphate structures using 181Hf/181Ta probe

    Nuclear quadrupole interaction study using Time Differential Perturbed Angular Correlation technique has been carried out to identify the sites where hafnium can reside in hydroxyapatite in order to mimic the behavior of plutonium adsorption on hydroxyapatite. Hf(IV) has been found to occupy three sites with the quadrupole interaction frequency (ωQ) and its asymmetry (η): (i) ωQ = 136.7(5) Mrad/s, η = 0.54(1); (ii) ωQ 300.1(9) Mrad/s, η = 0.35(2); (iii) ωQ = 124.6(5), η = 0.0(1). Narrow frequency distributions indicate the sites are well-defined. This study has been extended to barium orthophosphate to confirm our inference for the apatite structure. (author)

  16. Neutron-induced fission cross section of 233Pa between 1.0 and 3.0 MeV

    The energy dependent neutron-induced fission cross section of P233a has for the first time been measured directly with monoenergetic neutrons. This nuclide is an important intermediary in a thorium based fuel cycle, and its fission cross section is a key parameter in the modeling of future advanced fuel and reactor concepts. A first experiment resulted in four cross section values between 1.0 and 3.0 MeV, establishing a fission threshold in excess of 1 MeV. Significant discrepancies were found with a previous indirect experimental determination and with model estimates

  17. 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

    The Thorium cycle Th232/U233 may face brilliant perspectives through advanced concepts like molten salt reactors or accelerator driven systems but it lacks accurate nuclear data concerning some nuclei. Pa233 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 Th232(He3,p)Pa234* in which the Pa234 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 (C6D6) 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 Pa231 for a 110 keV neutron: σ(n,γ) 2.00 ± 0.14 barn. (A.C.)

  18. Feasibility of the instrumental neutron activation analysis of entire archaeological pottery. Part 1: Precision of the results and radiological safety of the process

    The feasibility of the instrumental neutron activation analysis of entire pieces of archaeological pottery, using low thermal neutron fluxes, is examined. The study takes into account the chemical elements relevant for archaeological investigations, as well as the degree of accuracy required for such kind of research. It is shown that after irradiation of a typical pottery sample of about 1 kg during 45 minutes, at a thermal flux of about 109 n.cm-2.s-1, analytical signals are obtained, by gamma spectrometry, with counting statistics better than 1%, for 76As, 131Ba, 141Ce, 60Co, 134Cs, 181Hf, 140La, 24Na, 122Sb, 46Sc, 153Sm and 233Pa, whereas 51Cr, 152Eu, 42K, 86Rb, 175Yb and 65Zn can be detected with counting statistics within 1% and 2%. On the other hand, the statistics of measurement are relatively poor (orders of 3% - 10%) for 177Lu, 147Nd, 239Np, 160Tb and 181Ta. The feasibility of accomplishment reliable quantitative determinations, taking into account the complexity of the analysis of entire pieces of archaeological pottery is discussed, which involves factors such as high masses, as well as asymmetric and variable shapes. (orig.)

  19. Neutron measurements for innovative fuel cycle and transmutation performed at the CEN Bordeaux-Gradignan : transfer techniques applied to the protactinium case

    Transfer reaction techniques have been used to determine neutron induced fission cross section (σn,f) of the short lived 233Pa nucleus, which is of importance for the Th-U fuel cycle for innovative reactors. The σn,f of 233Pa has been determined from the product of the fission probability of 234Pa measured in transfer reaction 232Th(3He,p) with the calculated compound nucleus formation cross section in the 233Pa+n reaction. The validity of this method has been tested with the existing data for direct neutron experiments on long-lived target nuclei 231Pa and 230Th. Transfer reaction techniques have been used too for the determination of capture cross section (σn,y) of 233Pa. This method will be extended to other highly radioactive actinides (such as 242-245Cm isotopes). (author)

  20. Hafnium binding to rat serum transferrin

    Then, G.; Appel, H.; Thies, W.G.; Duffield, J.; Taylor, D.M. (Kernforschungszentrum Karlsruhe G.m.b.H. (Germany, F.R.). Inst. fuer Genetik und Toxikologie von Spaltstoffen); Zell, I. (Karlsruhe Univ. (T.H.) (Germany, F.R.). Inst. fuer Experimentelle Kernphysik)

    1983-12-01

    Using the TDPAC-technique binding parameters for Hf were determined after in vivo uptake of /sup 181/Hf in rat plasma. As much as 98.5% of the metal ions proved to be bound to protein, essentially to transferrin. The main fraction of the /sup 181/Hf ions experiences a well defined electric quadrupole perturbation frequency (..gamma..sub(Q1) = (1516 +- 15)MHz, deltasub(1) = (5.3 +- 0.8)%) connected with a marked relaxation damping (lambda = (46 +- 8)MHz). The remaining Hf nuclei are subject to a fairly broad distribution of electric field gradients (..gamma..sub(Q2) = (1014 +- 37)MHz, deltasub(2) = (16 +- 3)%). The results are compared with data obtained with in vitro /sup 181/Hf-labeled human transferrin.

  1. Application of perturbed angular correlation spectroscopy in IgG immunoglobulins

    Silva, A.S.; Amaral, A.A.; Lapolli, A.L.; Carbonari, A.W. [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)], e-mail: asilva@usp.br

    2009-07-01

    In the present work, the technique of perturbed angular correlation (PAC) spectroscopy was used to measure the electric hyperfine field at IgG immunoglobulins using {sup 111}In {yields}{sup 111}Cd and {sup 181}Hf {yields} {sup 181}Ta probe nuclei. The biological materials studied in this work were originating from the immunological response of different mice lineages infected by the Y strain of T. cruzi. The samples were measured at room temperature (295K) and at liquid nitrogen temperature (77K). The PAC results showed that, samples measured with {sup 111}In obtained better results when they were compared with samples measured with {sup 181}Hf. (author)

  2. A chromatographic separation of neptunium and protactinium using 1-octanol impregnated onto a solid phase support

    We have developed a new chromatographic method to efficiently separate and isolate neptunium (Np) and protactinium (Pa), based on the selective extraction of protactinium by primary alcohols. The effectiveness of the new technology is demonstrated by efficient separation of 233Pa from parent radionuclide 237Np, using a hydrochloric acid mobile-phase medium. Our new approach reproducibly isolated 233Pa tracer with a yield of 99 ± 1 % (n = 3; radiochemical purity 100 %) and enabled chemical recovery of 237Np parent material of 92 ± 3 % (radiochemical [99 %) for future 233Pa tracer preparations. Compared to previous methods, the new approach reduces radioactive inorganic and organic waste; simplifies the separation process by eliminating cumbersome liquid-liquid extractions; and allows isolation of radiochemically-pure fractions in less than 1 h. (author)

  3. Assessment of U and Th Content in River Sediment of Code Yogyakarta

    The determination of thorium has been done using neutron activation analysis (NAA) method in Code river sediment samples. For AAN method Th was determined as 232Th(n,γ) 233Pa. Thorium was identified from peak energy 312 and 300 keV of 233Pa. From t test method for statistic calculation was shown that there were not significant differences between sampling location with the concentration of 232Th were (2.07 6.75) mg/kg, at the confident level test of 95 %. (author)

  4. Selective population of high-j orbitals in Er nuclei by heavy-ion--induced transfer

    Selective population of high-j and high-K states in /sup 167,169,171/Er nuclei has been observed in heavy-ion--induced single-neutron-transfer reactions. Gamma rays in coincidence with outgoing particles have been used to aid in level assignments and several previously unobserved high-j states have been identified

  5. Flotation separation of hafnium(IV) from aqueous solutions

    A simple, rapid method for the separation of hafnium from aqueous solutions was investigated using sup(175+181)Hf tracer. Cationic hafnium complex ions were floated from dilute acid solutions with sodium lauryl sulfate (SLS) and anionic hafnium complexes were floated from basic and oxalic acid solutions with hexadecyltrimethyl ammonium bromide (HTMAB). The conditions necessary for quantitative recovery of the metal and mechanisms of flotation are described. (author)

  6. Study of dynamic behavior of EDTA molecule in solution using perturbed gamma-gamma angular correlation spectroscopy

    In this work, PAC spectroscopy has been used to obtain the hyperfine parameters in EDTA molecules in solutions with pH 4.3 and pH 10.5 both measured at 77 K and 295 K using 181Hf(181Ta) as probe nuclei. Both dynamic and static interactions were measured in aqueous solution, crystallized and re-hydrated samples in order to examine the motion and structure of EDTA-molecules. The hyperfine parameters, quadrupole interaction frequency (νQ), asymmetry (η), and the dynamic interaction frequency (λ) were obtained. The outcomes show that the rotational correlation time (τCR) is larger than the half-life of the intermediate state of probe nuclei. For samples with pH 4.3 and pH 10.5, it was observed an increase in νQ when the temperature decreases, as expected, and also a variation of η, which is an evidence of a change in the EDTA molecule structure. 181Hf is bound only to a single molecule site when the pH was 4.3, differently from the results for pH 10.5 sample, which showed two fractions with different νQ indicating the possibility of 181Hf being bonded to two different sites of the molecule. Measurements of the dehydrated sample presented different results leading us to conclude that the preparation procedure can causes alterations in the chemical bounds. Concluding, these results showed a systematic behavior of the 181Hf-EDTA, with the variation of pH from 4 to approximately 11, and they are important to the knowledge of the dynamic behavior of this molecule. (author)

  7. High-Performance γ spectrometry Using Ge(Li) Detectors

    This report describes a high resolution gamma spectrometer design which use Ge-Li detectors, a cooled field effect transistor preamplifier, and a spectrum stabiliser. The obtained resolution and the 122 keV gamma ray of the 57Co is 0.96 keV, and 239Pu, 233Pa and 95Zr + 95Nb spectra are shown for the example. (authors)

  8. A new hybrid surrogate ratio method for neutron-induced fission cross section measurements of short-lived actinides

    We will present a brief review of various surrogate methods employed for compound nuclear cross-section measurements along with our recent results using the hybrid surrogate ratio approach for determination of neutron induced fission cross sections of 233Pa and 234Pa isotopes

  9. In vivo and in vitro studies of hafnium-binding to rat serum transferrin

    Then, G.M.; Appel, H.; Duffield, J.; Taylor, D.M.; Thies, W.G.

    1986-08-01

    The binding of hafnium to rat serum transferrin was studied using the time differential perturbed angular correlation (TDPAC) technique. Hafnium is interesting as a toxic metal binding to transferrin because it behaves metabolically similarly to plutonium. The isotope 181Hf offers favorable access to the TDPAC-method. Samples were prepared in vivo by intravenous injection of Hf-NTA, Hf-citrate, and Hf-oxalate solutions, respectively, into Sprague-Dawley rats and in vitro by adding Hf-NTA solution to fresh rat serum. In both cases two specific electric quadrupole interactions were observed, which correspond to two well-defined binding configurations. They may be attributed to the N-terminal and the C-terminal binding site in the transferrin molecule. The 181Hf-distribution between these two binding states depends on pH, salt and hafnium concentrations, temperature, and incubation time. With a fast TDPAC-setup of four BaF2-detectors a time resolution of about 600 ps could be achieved. The specific binding configurations of 181Hf and the comparatively slow relaxation times lead to spectra of considerable accuracy.

  10. Comparative evaluation of two methods for 172Tm production in nuclear reactors

    A comparative evaluation of two methods for the production of 172Tm in nuclear reactors is carried out. They are respectively based on two chains of double neutron capture reactions, 170Er(n,γ)171Er(n,γ)172Er(β-)172Tm and 170Er(n,γ)171Er(β-)171Tm(n,γ)172Tm, and a chain of triple neutron capture: 169Tm(n,γ)170Tm(n,γ)71Tm(n,γ)172Tm. Theoretical considerations with respect to both ways of production are formulated and the mathematical equation are solved. Experiments of irradiation of Er2O3 and Tm2O3 were performed. Advantages and drawbacks of both methods are discussed. (author)

  11. Production of heavy nuclei radiochemically pure preparations for nuclear-spectroscopic investigations

    Extraction-chromatographic and extraction techniques of extraction and purification of 233Pa, 237U, 238Np and 239Np radionuclides in different systems are investigated. It is established that for 233Pa extraction from a thorium target irradiated by neutrons extraction-chromatographic tributyl phosphate 0.5 MHCl+5% H2C2O4 system is most perspective. To produce 237U radiopreparation the method of two-stage extraction in the diethyl ether Al(NO3)3 system is used. When extracting radiometrically pure preparations 238Np and 239Np HDEHP-HNO3 extraction chromatograpg hic system is used. Radiochemical pure of radiopreparations is estimated using their γ-spectra resultant on γ-spectrometer with germanium-lethium semiconductor detector

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

    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 232Th, 231,233Pa (later adopted for the ENDF/B-VII.0 library) and improvements to existing evaluations for 232,233,234,236U. Available nuclear data evaluations for 230-232Th, 231,233Pa and 232,233,234U 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 232Th and 233U were also discussed. (author)

  13. An experimental test of Dirac-Fock versus Dirac. Hartree-Slater L x-ray intensity ratios

    K X-ray L X-ray coincidence experiments were performed using two radioactive sources, 233Pa, which decays to 2+3+U, and 157Tb, which decays to 157Gd. The K X-ray spectra were recorded using an Aptec HpGe detector, while the L X-ray spectra were recorded a Link Analytical plc Si(Li) detector. With the 233Pa source, twelve coincidence measurements were performed at 10 angles in the range 900 - 1800. In addition, singles K and L X-ray spectra were also recorded to high intensities. These careful measurements support L3, the DF predictions for relative X-ray line intensities. These intensities should be used inappropriate data bases rather than the earlier DHS values. (N.T.) 6 refs

  14. The Pa-233 fission cross section

    The energy dependent neutron-induced fission cross section of 233Pa has for the first time been measured directly with mono-energetic neutrons. This isotope is produced in the thorium fuel cycle and serves as an intermediate step between the 232Th source material and the 233U fuel material. Four neutron energies between 1.0 and 3.0 MeV have been measured in a first campaign. Some preliminary results are presented and compared to literature. (author)

  15. Semi-empirical approach for predicting neutron-induced fission cross-sections in the energy range 1-18 MeV

    A semi-empirical formula is described to calculate neutron-induced fission cross-sections. calculations based on this formula are presented here for several trans-actinide nuclei up to the third fission-plateau. On the whole, the calculated fission cross-sections agree within 10% with the experimental values. For 233Th and 233Pa, where no experimental results exist, predicted cross-sections based on the present expression are also presented. (author)

  16. Rare earths in GaN and ZnO studied with the PAC method; Seltene Erden in GaN und ZnO untersucht mit der PAC-Methode

    Nedelec, R.

    2007-07-01

    The present thesis deals with the implantation and annealing behaviour of two examples of large-band-gap semiconductors GaN and ZnO. The studies begin with the annealing behaviour of GaN after the implantation of {sup 172}Lu. For GaN the annealing process begins at low temperatures with the decreasing of the damping of the lattice frequency. At essentially higher temperatures finally the substitunial contribution increases. This behaviour is also observed for other probe nuclei in GaN. For ZnO the behaviour at low temperature is different. Both for {sup 172}Lu and for {sup 181}Hf the damping is already after the implantation very low. The increasement of the substitutional contribution occurs like in GaN at higher temperatures. Thereafter for GaN and ZnO PAC spectra were token up at different measurement temperatures between 25 and 873 K. For {sup 172}Lu in GaN and in ZnO a strong temperature dependence of the lattice field gradient was observed. Also for {sup 181}Hf in ZnO a strong temperature dependence is observed. For {sup 172}Lu by means of a model for the interaction of quadrupole moments of electronic shells with the nucleus a lattice field gradient of {+-}5.9.10{sup 15} Vcm{sup -2} could be determined. For {sup 172}Lu in ZnO the model yields at 293 K a lattice field gradient of +14.10{sup 15} Vcm{sup -2} respectively -13.10{sup 15} Vcm{sup -2}. The corrsponding measurement with {sup 181}Hf yields a lattice field gradient of {+-}5.7.10{sup 15} Vcm{sup -2}.

  17. Separation of lutetium from large amount of hafnium

    A method has been developed for the separation of Lu from large amount of Hf. Radioactive tracers of 181Hf and 177Lu were used to standardised the procedure. Extraction chromatography using Di-(2-ethyl hexyl)-phosphoric acid as the extractant and chromosorb as the inert support were used to separate Lu from Hf. The method finds its application in the milking of 172Lu, a nuclear probe used in perturbed angular correlation studies, from 172Hf produced by Yb(α, Xn) reaction. (author). 6 refs., 1 tab

  18. Neutron reaction cross section data for advanced nuclear applications

    Full text of publication follows: Worldwide major research efforts are currently being carried out in order to develop a new concept of nuclear power generation, so-called accelerator driven systems (ADS) for energy production and transmutation of radioactive nuclear waste. A suggested approach is the energy amplifier (EA), which is a sub-critical reactor using a powerful proton accelerator and a spallation reaction as neutron source. Since the EA is based on the thorium-uranium fuel cycle, where the natural resources of the main fuel thorium are estimated to last for hundred thousands of years, it is considered to provide clean and almost inexhaustible nuclear energy. Apart from necessary new technical developments, the realization of these concepts depends strongly on the availability of accurate nuclear reaction data. In particular, precise knowledge about cross sections for fission, neutron capture and scattering is required for the nuclides involved in the Th-U fuel cycle. Among the first priority isotopes the IAEA had pointed out 231Pa and 233Pa. The latter one, 233Pa, is of specific interest, since it plays an important role as an intermediate nucleus in the formation of the fissile 233U from the fertile 232Th. With its half life of 27.0 days for β-decay, 233Pa is not a 'long-lived' nucleus, but it still requires careful attention in the design and operation of thorium-fueled reactors. When a thorium-fueled reactor is stopped, the present amount of 233Pa will continue to decay into 233U, leading to an increase in reactivity, which may even cause criticality. This mechanism is known as 'protactinium effect' and is proportional to the power level of the reactor. Also the precise knowledge of the fission cross section of 231Pa (above 1 b for fast neutrons) is essential for simulations of the balance of nuclei in and, thus, the reactivity behavior of the reactor. We present recent cross section data from direct, energy resolved measurements of the neutron

  19. Electric field gradient at the Nb3M(M = Al, In, Si, Ge, Sn) and T3Al (T = Ti, Zr, Hf, V, Nb, Ta) alloys by perturbed angular correlation method

    The electric field gradient (efg) at the Nb site in the intermetallic compounds Nb3 M (M = Al, Si, Ge, Sn) and at the T site in the intermetallic compounds T3Al (T = Ti, Zr, Hf, V, Nb, Ta) was measured by Perturbed Angular Correlation (PAC) method using the well known gamma-gamma cascade of 133-482 keV in 181Ta from the β- decay of 181Hf. The compounds were prepared by arc melting the constituent elements under argon atmosphere along with radioactive 181Hf substituting approximately 0.1 atomic percent of Nb and T elements. The PAC measurements were carried out at 295 K for all compounds and the efg was obtained for each alloy. The results for the efg in the T3Al compounds showed a strong correlation with the number of conduction electrons, while for the Nbs M compounds the efg behavior is influenced mainly by the p electrons of the M elements. The so-called universal correlation between the electronic and lattice contribution for the efg in metals was not verified in this work for all studied compounds. Measurements of the quadrupole frequency in the range of 100 to 1210 K for the Nb3Al compound showed a linear behaviour with the temperature. Superconducting properties of this alloys may probably be related with this observed behaviour. The efg results are compared to those reported for other binary alloys and discussed with the help of ab-initio methods. (author)

  20. Recoil induced room temperature stable Frenkel pairs in α-hafnium upon thermal neutron capture

    Ultrapure hafnium metal (110 ppm zirconium) was neutron activated with a thermal neutron flux of 6.6 . 1012cm-2s-1 in order to obtain 181Hf for subsequent time differential perturbed angular correlation (TDPAC) experiments using the nuclear probe 181Hf(β-)181Ta. Apart from the expected nuclear quadrupole interaction (NQI) signal for a hexagonal close-packed (hcp) metal, three further discrete NQIs were observed with a few percent fraction each. The TDPAC spectra were recorded for up to 11 half lives with extreme statistical accuracy. The fitted parameters vary slightly within the temperature range between 248 K and 373 K. The signals corresponding to the three additional sites completely disappear after 'annealing' at 453 K for one minute. Based on the symmetry of the additional NQIs and their temperature dependencies, they are tentatively attributed to Frenkel pairs produced by recoil due to the emission of a prompt 5.694 MeV γ-ray following thermal neutron capture and reported by the nuclear probe in three different positions. These Frenkel pairs are stable up to at least 373 K. (orig.)

  1. Ionic exchange and the local structure in the HfO2/Ho2O3 system studied by PAC spectroscopy

    Highlights: • Suitability of PAC spectroscopy to study inter-diffusion processes. • High level of ionic exchange obtained by ball-milling and thermal treatments. • EFG characterization of 181Ta impurities at defect-free cation sites of Ho2O3. • Excellent agreement with other EFG results in bixbyites and ab initio calculations. • A new Ho-doped m-HfO2 phase was characterized. - Abstract: The ionic exchange of Hf and Ho atoms in the HfO2/Ho2O3 system was studied at the atomic level applying the nuclear solid-state Time-Differential γ–γ Perturbed-Angular-Correlation (PAC) spectroscopy. This exchange was promoted by a ball-milling-assisted solid-state reaction between Ho2O3 and m-HfO2 initial powders. In order to follow and to elucidate the effect of different variables (milling time, temperature, pressure) on the exchange process and the appearance of new phases, 181Hf(→181Ta) ions were used as local probes in the PAC experiments. The measured hyperfine interactions enabled the electric-field gradient tensor (EFG) characterization at Hf sites at each step of the process. At the final stages of the solid-state reaction, 75–90% Hf-doping at both substitutional defect-free cation sites of Ho2O3 was achieved, being the EFG measured at these sites in excellent agreement with those determined in 181Hf-implanted Ho2O3 samples and to those predicted by the EFG systematics established in rare-earth bixbyites doped by ion-implantation of 181Hf(→181Ta) ions. Ab initio electronic structure calculations of the EFG at Ta impurities localized at both cation sites in Ho2O3 also confirm the 181Hf cationic substitution in both PAC experiments. Additional ab initio calculations at Hf impurity sites in Ho2O3 and Tm2O3 were performed to study the relative Hf preference for the symmetric site of the structure. We showed that high-energy milling plus high temperature treatments are both necessary to achieve a high degree of Hf substitution in the cation sublattice of the

  2. Medical and Health Sciences Division research report 1975--1976

    Progress is reported on studies on the effects of irradiation and carcinogenic chemical environmental pollutants on the immune system of mammals; fundamental studies of membrane properties and lipid metabolism in neoplasms and respiratory diseases induced by chemical irritants, carcinogens, and mutagens; the development and testing of radiopharmaceuticals labeled with 11C, 67Ga, 157Dy, or 171Er as tumor-localizing agents; and the completion of a radiation emergency assistance center and training program. A list is included of 60 publications during the period covered by this report that give details of the studies

  3. Development of simple method to incorporate out-of-core cooling effect on thorium conversion in multi-pass fueled reactor and investigation on characteristics of the effect

    Highlights: • I proposed simple method based on analytical approach. • I applied this method to MVP-BURN calculations without a code modification. • I estimated conversion efficiencies based on this method. • I compared the conversion efficiencies of MSBR and PBMR. - Abstract: Development of a simple method to incorporate the out-of-core cooling effect on the thorium conversion in multi-pass fueled reactors and investigation on characteristics of the effect have been undertaken. For multi-pass fueled reactors, such as Molten Salt Breeder Reactor (MSBR) and Pebble-Bed Modular Reactor (PBMR), fuel moves in the core and exits from the core. The produced nuclides also decay out of the core, which should be considered for core characteristics when needed. In the present study, 233Pa is selected to evaluate the thorium conversion accurately. To take the effect into account, in the present study, an effective decay constant is proposed to make equilibrium concentration of 233Pa without out-of-core cooling equal to that with out-of-core cooling. With the effective decay constant, the out-of-core cooling effect can be incorporated even with the code system using macroscopic cross sections generated by cell burn-up calculations without any code modification. In addition, the characteristics of out-of-core cooling effect for the thorium conversion are evaluated for thorium fueled reactors MSBR and PBMR. It is concluded that the out-of-core cooling effect is suitable for MSBR to enhance thorium conversion because of the fast flow rate of fuel salt. On the other hand, the effect is neither important nor realistic to employ for PBMR because the in-core residence time of approximately 100 days is longer than the half-life of 233Pa of 27.0 days, and the effect cannot improve the conversion ratio significantly

  4. Neutron-induced fission cross-section of 231 Pa

    Beside the importance of 231 Pa for basic fission studies it is also of interest in the field of future reactor design based on the thorium-uranium fuel cycle. The 232 Th/233 U breeder cycle, where the natural resources of the main fuel thorium are estimated to last for hundred thousands of years, is contemplated to provide 'clean' and almost inexhaustible nuclear energy. Among the first priority isotopes the IAEA had pointed out 231 Pa and 233 Pa. Both are of special interest being intermediate nuclei in the formation of the fissile 233 U from the fertile 232 Th. The latter has been investigated in the recent past in great detail. In particular, 231 Pa carry a similar risk as 239 Pu does in the standard uranium-plutonium cycle due to its comparable half-life and radio-toxicity. Despite the wealth of existing experimental data important discrepancies exist, a scenario, which holds for the existing evaluated data files ENDF/B-VI and JENDL-3.3, too. Presently, the neutron-induced fission cross-section of 231 Pa is under investigation at the VdG neutron source at IRMM for incident neutron energies up to 20 MeV. The obtained cross-sections, representing the 3rd and higher chance fission in 233 Pa(n,f) will serve as precise input for the validation of the reaction cross-section calculations performed on 233 Pa up to 20 MeV and the envisaged extension up to 50 MeV. (authors)

  5. Determination of thorium in human urine by neutron activation

    A routine procedure for the determination of thorium in urine of workers has been developed by the neutron activation method. The technique suggested by Dang, et. al. has been modified in order to reduce the cost involved and the sample processing time. The samples were irradiated in the MIT (Massachusetts Institute of Technology-Boston) reactor, in a thermal neutron flux of 8 x 10 12n.cm-2.s-1 for 3,5 hours. Thorium-232 was determined by counting 233Pa. (author) 6 refs.; 2 tabs

  6. Differential tumor necrosis factor receptor 2-mediated editing of virus-specific CD8+ effector T cells

    Turner, Stephen J.; La Gruta, Nicole L.; Stambas, John; Diaz, Gabriela; Doherty, Peter C.

    2004-01-01

    Much of the CD8+ T cell response in H2b mice with influenza pneumonia is directed at the nucleoprotein366-374 (NP366) and acid polymerase224-233 (PA224) peptides presented by the H2Db MHC class I glycoprotein. These DbNP366- and DbPA224-specific T cell populations are readily analyzed by staining with tetrameric complexes of MHC+ peptide (tetramers) or by cytokine production subsequent to in vitro stimulation with the cognate peptides. The DbPA224-specific CD8+ effector T cells make more tumo...

  7. Protactinium neutron-induced fission up to 200 MeV

    Maslov V.

    2010-01-01

    The theoretical evaluation of 230-233Pa(n,F) cross sections is based on direct data, 230-234Pa fission probabilities and ratios of fission probabilities in first-chance and emissive fission domains, surrogate for neutroninduced fission. First chance fission cross sections trends of Pa are based on consistent description of 232Th(n,F), 232Th(n,2n) and 238U(n,F), 238U(n,xn) data, supported by the ratio surrogate data by Burke et al., 2006, for the 237U(n,F) reaction. Ratio surrogate data ...

  8. Neutron-induced fission cross-section of 231Pa

    A first series of fission cross-section measurements for incident neutron energies between 0.6 and 3.4 MeV has confirmed a first chance threshold value around 1b. In contrast to our findings for the fission cross-section in 233Pa, both the direct and the surrogate cross-section data lead to the same result. This seems to support the assumption, that only in cases, where ingoing and outgoing particle are similar, particle-transfer reactions give results that are in agreement with those obtained from direct compound nuclear reactions

  9. The effect of food on gastrointestinal (GI) transit of sustained-release ibuprofen tablets as evaluated by gamma scintigraphy

    The GI transit of radiolabeled sustained-release ibuprofen 800-mg tablets in eight healthy, fed volunteers was monitored using external gamma scintigraphy. Ibuprofen serum concentrations were determined from blood samples drawn over 36 hr following dosing. Sustained-release ibuprofen tablets containing 0.18% of 170Er2O3 (greater than 96% 170Er) in the bulk formulation were manufactured under pilot-scale conditions and were radiolabeled utilizing a neutron activation procedure which converted stable 170Er to radioactive 171Er (t1/2 = 7.5 hr). At the time of dosing, each tablet contained 50 mu Ci of 171Er. Dosage form position were reported at various time intervals. In five subjects the sustained-release tablet remained in the stomach and eroded slowly over 7-12 hr, resulting in gradual increases in small bowel radioactivity. In the remaining three subjects, the intact tablet was ejected from the stomach and a gastric residence time of approximately 4 hr was measured. This is in marked contrast to a previous study conducted in fasted volunteers in which gastric retention time ranged from 10 to 60 min. Differences in GI transit between fed and fasted volunteers had little effect on ibuprofen bioavailability. AUC and Tmax were unaltered and Cmax was increased by 24%, which is in agreement with results from a previous, crossover-design food effect study

  10. Complexos de hidrogénio com oxigénio (ou azoto) em metais, estudados por correlações angulares perturbadas

    Mendes, Paulo Jorge Baeta

    1987-01-01

    Utilizando o método das correlações angulares perturbadas usando como sonda radioactiva o 181 Hf, realizaram-se estudos da interação de hidrogénio e deutério como as impurezas intersticiais oxigénio e azoto nos metais tântalo e nióbio. Foram identificadas as interacções devidas ao oxigénio e azoto nestes metais a caracterizada a sua evolução com a temperatura. Para as baixas concentrações estudadas não se observou a formação de complexos de mais do que um atómo de oxigénio quer no ...

  11. Studies on the conditioning methods of spent tri-butyl phosphate/kerosene and its degradation product in different matrices

    The destruction of spent TBP/Kerosene (odourless kerosene (OK)) with potassium permanganate has been investigated. Comparative studies on the immobilization of spent TBP/Kerosene and its degradation product into different matrices have been carried out. The matrices used include, ordinary portland cement, silica fume, treated fly ash, epoxy resin and cement mixed with epoxy resin. The different factors affecting solidified waste forms, such as compressive strength, water resistance, thermal stability, chemical resistance, radiological stability and leachability, have been investigated. It was found that epoxy resin and cement mixed with 5, 10, 20, and 50% of epoxy resin enhance the compressive strength of the solidified waste forms with spent TBP/OK more than that obtained from degradation products. The leaching rates of 152,154Eu and 181Hf from waste forms containing TBP/OK was found lower than that with degradation product. (author)

  12. Studies on the Conditioning Methods of Spent Tri-butyl Phosphate/Kerosene and its Degradation Product in Different Matrices

    The destruction of spent TBP/Kerosene (odourless Kerosene (OK)) with potassium permanganate have been investigated. Comparative studies on the immobilization of spent TBP/Kerosene and its degradation product into different matrices have been carried out. The matrices used include, ordinary Portland cement, silica fume, treated fly ash, epoxy resin and cement mixed with epoxy resin.The different factors affecting solidified waste forms such as, compressive strength, water resistance, thermal stability, chemical resistance, radiological stability and leachability have been investigated. It was found that, epoxy resin and cement mixed with 5,10,20, and 50% of epoxy resin enhance the compressive strength of the solidified waste forms with spent TBP/OK more than that obtained from degradation products. The leaching rates of 152 and 154 Eu and 181Hf from waste forms containing TBP/OK was found lower than that with degradation product

  13. Investigation of electric quadrupole interaction in TiO2 by means of perturbed gamma-gamma angular correlation spectroscopy

    TiO2 has called attention in both basic research and technological applications as an energy converter in solar cells, photo catalyst for water purification, sunscreen material, drug detection, and other applications. In addition TiO2 is a candidate for use in medical devices, food preparation surfaces, air conditioning filters and sanitary ware surfaces.TiO2 has two crystalline phases: anatase and rutile. The structural properties and hyperfine interactions in TiO2 were investigated by perturbed gamma-gamma angular correlation (PAC) spectroscopy using 111 In and 181 Hf as probe nuclei. The PAC spectroscopy provides information on crystalline and electronic structure at an atomic scale. In the present work, PAC measurements on TiO2 were focused on the development of a methodology to prepare bulk samples, which have been characterized by conventional techniques such as x-ray diffraction, (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The samples were prepared by the sol gel Pechini method. The resulting powders were annealed at different temperatures in a tubular furnace under nitrogen atmosphere. The PAC measurements were carried out at room temperature in air. The occupation fraction of the probe nuclei reached 50% when the sample was annealed at 1373K and after measured at room temperature.In this case the frequency measured in site 1 is in agreement with that found in literature for substitutional titanium site in rutile structure when 111In were used as probe nuclei. It was measured a frequency more closely to that was found in literature[7] for the case in which 181Hf were used as probe nuclei when the sample annealed at 1373 K and measured at 973 K. (author)

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

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

  15. Mass distribution in 19F induced fission of 232Th

    Formation cross sections of several fission products have been determined using the recoil catcher technique followed by γ-ray spectrometry in 19F induced fission of 232Th at Elab=95 and 112 MeV. The data show significant admixture of fission from compound nuclei formed by complete fusion as well as targetlike nuclei formed by transfer reactions. Mass distributions for both the fissioning systems have been obtained using the systematics of charge distribution in low and medium energy fission. Mass distribution for complete fusion fission is broad Gaussian whereas it is asymmetric for transfer induced fission. At 95 MeV the transfer fission constitutes about 28% of total fission cross section while at 112 MeV it is about 14%, showing that the transfer fission fraction decreases with increasing projectile energy across the barrier. The evaporation residue cross sections of the targetlike nucleus formed in the 232Th (19F, 18O) 233Pa reaction were also measured. The evaporation residue cross sections and the calculated decay probabilities of the targetlike nucleus 233Pa by PACE2 have been used to estimate the fraction of proton and α transfer fission in the total transfer fission cross section. copyright 1996 The American Physical Society

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

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

  17. Fission investigations and evaluation activities at IRMM

    The IRMM has a longstanding tradition in the field of neutron induced fission physics studies. It is especially well equipped with world-class facilities as the high resolution neutron time-of-flight spectrometer GELINA and the 7 MV Van de Graaff accelerator for the quasi-monoenergetic neutron production. During the past decade several neutron induced fission reactions have been studied in the energy range from eV up to 6 MeV and spontaneous fission. The isotopes under investigation were 235,238 U(n,f), 239 Pu(n,f), 237 Np(n,f), 252 Cf(SF) and 233 Pa(n,f). For all isotopes but 233 Pa, the fission fragment mass-yield and total kinetic energy distributions were measured. 233 Pa was only investigated for the fission cross-section. The results have been described within the multi-modal fission model. The three most dominant fission modes, the two asymmetric standard I (S1) and standard II (S2) as well as the the symmetric superlong mode were used for all the isotopes but 252 Cf. For this isotope at least one other fission mode had to be taken into account, the so--called standard III (S3) mode. Since the theoretical interpretation of experimental results was rather successful also an attempt was made to improve the evaluation of the respective fission cross-section as well as their neutron multiplicities and spectra. Here, the statistical model for fission cross-section evaluation was extended by including the multi-modality concept for fission. Based on the underlying model, separate outer fission barriers have been considered for each mode, while the inner barriers and isomeric wells are assumed to be the same. The self-consistent calculations of the fission cross-section as well as total, capture, elastic and inelastic cross-sections were in good agreement with the experimental data and evaluated nuclear data libraries. As a side product, also fission fragment mass yield distributions have been deduced at incident neutron energies hitherto unaccessible. Very

  18. Protactinium neutron-induced fission up to 200 MeV

    The theoretical evaluation of 230-233Pa(n,F) cross sections is based on direct data, 230-234Pa fission probabilities and ratios of fission probabilities in first-chance and emissive fission domains, surrogate for neutron-induced fission. First chance fission cross sections trends of Pa are based on consistent description of 232Th(n,F), 232Th(n,2n) and 238U(n,F), 238U(n,xn) data, supported by the ratio surrogate data by Burke et al., 2006, for the 237U(n,F) reaction. Ratio surrogate data on fission probabilities of 232Th(6Li,4He)234Pa and 232Th(6Li,d)236U by Nayak et al., 2008, support the predicted 233Pa(n,F) cross section at En=11.5-16.5 MeV. The predicted trends of 230-232Pa(n,F) cross section up to En=20 MeV, are consistent with fissile properties of Pa nuclides, extracted by 232Th(p,F) (Isaev et al., 2008) and 232Th(p,3n) (Morgenstern et al., 2008) data analysis. The excitation energy and nucleon composition dependence of the transition from asymmetric to symmetric scission for fission observables of Pa nuclei is defined by analysis of p-induced fission of 232Th at Ep=1-200 MeV. Predominantly symmetric fission in 232Th(p,F) at En(p)=200 MeV as revealed by experimental branching ratios (Dujvestijn et al., 1999) is reproduced. Steep transition from asymmetric to symmetric fission with increase of nucleon incident energy is due to fission of neutron-deficient Pa (A≤229) nuclei. A structure of the potential energy surface (a drop of symmetric and asymmetric fission barriers difference (Ef(SYM) - Ef(ASYM)) from about 3.5 MeV to 1 MeV) of N-deficient Pa nuclides (A≤226) and available phase space at outer fission saddles, are shown to be responsible for the sharp increase with En(p) of the symmetric fission component contribution for 232Th(p,F) and 230-233Pa(n,F) reactions. That is a strong evidence of emissive fission nature of moderately excited Pa nuclides, reliably quantified only up to En(p) about 20(30) MeV. Predicted fission cross section of 232Pa

  19. Protactinium neutron-induced fission up to 200 MeV

    Maslov V.

    2010-03-01

    Full Text Available The theoretical evaluation of 230-233Pa(n,F cross sections is based on direct data, 230-234Pa fission probabilities and ratios of fission probabilities in first-chance and emissive fission domains, surrogate for neutroninduced fission. First chance fission cross sections trends of Pa are based on consistent description of 232Th(n,F, 232Th(n,2n and 238U(n,F, 238U(n,xn data, supported by the ratio surrogate data by Burke et al., 2006, for the 237U(n,F reaction. Ratio surrogate data on fission probabilities of 232Th(6 Li,4 He234Pa and 232 Th(6 Li,d236U by Nayak et al., 2008, support the predicted 233Pa(n, F cross section at En=11.5-16.5 MeV. The predicted trends of 230-232Pa(n, F cross section up to En=20 MeV, are consistent with fissilities of Pa nuclides, extracted by 232Th(p,F (Isaev et al., 2008 and 232Th(p,3n (Morgenstern et al., 2008 data analysis. The excitation energy and nucleon composition dependence of the transition from asymmetric to symmetric scission for fission observables of Pa nuclei is defined by analysis of p-induced fission of 232Th at Ep=1-200 MeV. Predominantly symmetric fission in 232Th(p,F at En( p=200 MeV as revealed by experimental branching ratios (Dujvestijn et al., 1999 is reproduced. Steep transition from asymmetric to symmetric fission with increase of nucleon incident energy is due to fission of neutron-deficient Pa (A≤229 nuclei. A structure of the potential energy surface (a drop of f f symmetric and asymmetric fission barriers difierence (EfSYM - EfASYM from ~3.5 MeV to ~1 MeV of N-deficient Pa nuclides (A≤226 and available phase space at outer fission saddles, are shown to be responsible for the sharp increase with En( p of the symmetric fission component contribution for 232Th(p,F and 230-233 Pa(n, F reactions. That is a strong evidence of emissive fission nature of moderately excited Pa nuclides, reliably quantified only up to En( p~20(30 MeV. Predicted fission cross section of 232Pa(n,F coincides with

  20. Radiochemical neutron activation analysis of trace impurities in high purity aluminum

    Rapid radiochemical neutron activation analysis (RNAA) procedures were developed and employed for the determination of 32 trace impurities in high purity aluminum thin foils. Anion exchange column chromatography was developed for the sequential group chemical separation of various elements which helped in reducing the spectral interferences and improving the sensitivity of the method. The procedure is simple and requires a very short time to separate the elements in three groups for radiometric assay. To determine very low contents of uranium and thorium, 239Np and 233Pa as activation products were separated using anion exchange and coprecipitation methods. The impurity contents were found to be low, therefore, their adverse effects on microelectronic devices would be negligible. Our data could partially be compared with the data reported in literature. (author)

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

    Radiochemical neutron activation analysis (RNAA) is an excellent method for determining uranium and thorium; it offers unique possibilities for their ultratrace analysis using selective radiochemical separations. Regarding the favourably sensitive nuclear characteristics of uranium and of thorium with respect to RNAA, but the different half-lives of their induced nuclides, two different approaches were used. In the first approach uranium and thorium were determined separately via 239U, 239Np and 233Pa. In the second approach these elements were 239239233 determined simultaneously in a single sample using U and/or Np and Pa. Isolation of induced nuclides was based on separation by extraction and/or anion exchange chromatography. Chemical yields were measured in each sample aliquot using added 235U, 238Np and 231Pa radioisotopic tracers. (author)

  2. The Separation and Measurement of Np( Ⅴ, Ⅵ) and Its Daughter 237Pa

    2001-01-01

    By means of liquid scintillation measurement of the Np sample solution which reaches 237Np-233Pa equilibrium with its daughter Pa, the detection efficiency of low energy y spectrum at 28.54, 86.59 and 311.98 keV are obtained. Using these data, the separation of different valence of Np from its daughter Pa is studied. The initial valence of Np is Np(Ⅴ) in solution. In order to compare the separation results, H2O2 is used to prepare Np( Ⅴ). Np(Ⅵ) is prepared by K2Cr2O7 and concentrated HNO3, respectively. TTA and/or TOPO and the back-extraction of them are used to separate Np and Pa. It indicates that initial Np( Ⅴ ) can be separated by TTA or TOPO, and the Np

  3. Primary fragment mass-yield distributions for asymmetric fission path of heavy nuclei

    The primary fragment mass-yield distribution for the asymmetric fission path in heavy nuclei, 233Pa, 239Np, 245Am and 249Bk at the excitation energy of ∼20 MeV are experimentally constructed based on the intensities of total kinetic energies for individual mass splits. The results revealed an interesting phenomenon: in all the studied fissioning systems, the inner wings of the mass-yield distributions in the asymmetric fission path appear along the same mass-wall of A = 130 fragment mass. The asymmetric mass-yield distribution indicates the strong effect of structural shells in fragments on the final mass division process of the asymmetric fission path. (author)

  4. Specific processes in solvent extractiotn of radionuclide complexes

    The doctoral thesis discusses the consequences of the radioactive beta transformation in systems liquid-liquid and liquid-ion exchanger, and the effect of the chemical composition of liquid-liquid systems on the distribution of radionuclide traces. A model is derived of radiolysis in two-phase liquid-liquid systems used in nuclear chemical technology. The obtained results are used to suggest the processing of radioactive wastes using the Purex process. For solvent extraction the following radionuclides were used: 59Fe, 95Zr-95Nb, 99Mo, sup(99m)Tc, 99Tc, 103Pd, 137Cs, 141Ce, 144Ce-144Pr, 234Th, and 233Pa. Extraction was carried out at laboratory temperature. 60Co was used as the radiation source. Mainly scintillation spectrometry equipment was used for radiometric analysis. (E.S.)

  5. Determination of neodymium and gadolinium in geologic samples by neutron activation analysis

    The determination of Nd and Gd present in rocks by neutron activation analysis is aimed at. A separation procedure for the rare earth group of elements is presented. The method is based on the retention of 233Pa, 182Ta and 46Sc by hydrated antimony pentoxide (HAP) in a 6M HClO4 medium. Those radioisotopes are interferences in the gamma-ray spectrum of 153Gd and 147Nd. The reliability of the method was tested by means of the geological standards BCR-1 and G-2 from the U.S. Geological Survey. The limitations of the instrumental neutron activation analysis and the advantages of the chemical separation are discussed for the special case of the Nd and Gd determinations. (Author)

  6. Nuclear data evaluation for Pa-233

    In this report the evaluation of main neutron nuclear data for 233Pa, namely neutron cross sections (total, elastic, inelastic, radiative capture, fission, (n,2n), (n,3n)), as well as the elastic and inelastic angular distributions, and energy distributions of secondary neutrons from inelastic scattering, (n,2n), (n,3n) and fission reactions, is described. In the same time, radioactive decay data and average number of neutrons per fission are given. For the resolved and unresolved resonance energy range, the Breit-Wigner single level parameters have been estimated. The data cover the energy range between 10-5eV and 20MeV. The final set of evaluated data is given in ENDF/B format and have been checked against physical consistency and format correctness. Many of the data have been calculated using theoretical models. (author)

  7. Metal incorporation by benthic fauna: relationships to sediment inventory

    A radionuclide addition experiment was conducted in a large-scale experimental mesocosm to study the behaviour and fate of trace metals in a coastal marine environment. Twelve radionuclides (7Be, 109Cd, 134Cs, 58Co, 60Co, 51Cr, 59Fe, 54Mn, 203Hg, 233Pa, 113Sn, and 65Zn) were added and their concentrations in benthic organisms and sediments were measured during the following nine months. The ability of benthic organisms to concentrate radionuclides was related to the vertical distribution and feeding behaviour of the organisms. Surface living fauna incorporated more radionuclides than deeper fauna. Calculations of total annual radionuclide incorporation by benthic fauna indicated that meiofauna incorporated a similar amount of the labelled metals as the macrofauna, even though the latter have a larger standing stock biomass. These calculations suggest that benthic metazoan fauna can annually cycle from 1% (Sn) to nearly 50% (Cd) of the amount of added radionuclides measured in sediments. (author)

  8. Determination of the 234Pa(n, f) reaction cross section by hybrid surrogate ratio method

    In an earlier work, we employed a new hybrid surrogate ratio approach to determine the 233Pa(n, f) cross sections for the first time in the equivalent neutron energy range of 11.5 MeV to 16.5 MeV using 6Li + 232Th transfer-fission correlation measurements. The 234Pa isotope produced in thorium-uranium fuel cycle is having half-life of 6.8 hrs. There is no neutron induced fission cross section data available in the literature for this system. We report first time results on 243Pa(n, f) cross sections in the equivalent neutron energy range of 10.5 MeV to 15.5 MeV using 7Li + 232Th transfer-fission correlation measurements with in the framework of hybrid surrogate method

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

    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 233Pa, a key nucleus in the 232Th - 233U fuel cycle. A recent experiment using this technique has been performed to determine the neutron-induced fission cross sections of 242,243,244Cm and 241Am 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)

  10. Determination of fission cross-section and absolute fission yields using track-cum gamma-ray spectrometric technique

    The fission cross-section of 233Pa(2nth, f) using fission track technique has been determined for the first time using thermal neutron flux of the reactor APSARA. This is important from the point of view of advance heavy water reactor (AHWR), which is to be described. On the other hand, the yields of fission products in the fast neutron induced fission of minor actinides are important from the point accelerator driven sub critical system (ADSS). In view of that, absolute yields of fission products in the fast neutron induced fission of 238U, 237Np, 238,240Pu, 243Am and 244Cm have been determined using the fission track-cum gamma-ray spectrometric technique. The total number of fission occurring in the target was estimated by track technique, whereas the activities of the fission products have been determined using gamma-ray spectrometric technique. Detailed procedure and its importance are to be discussed. (author)

  11. Studying nuclear level densities of {sup 238}U in the nuclear reactions within the macroscopic nuclear models

    Razavi, Rohallah; Aghajani, Maghsood; Khooy, Asghar [Imam Hossein Comprehensive Univ., Tehran (Iran, Islamic Republic of). Dept. of Physics; Rahmatinejad, Azam; Taheri, Fariba [Univ. of Zanjan (Iran, Islamic Republic of). Dept. of Physics; Kakavand, Tayeb [Imam Khomeini International Univ., Qazvin (Iran, Islamic Republic of). Dept. of Physics

    2016-05-01

    In this work the nuclear level density parameters of {sup 238}U have been extracted in the back-shifted Fermi gas model (BSFGM), as well as the constant temperature model (CTM), through fitting with the recent experimental data on nuclear level densities measured by the Oslo group. The excitation functions for {sup 238}U(p,2nα){sup 233}Pa, and {sup 238}U(p,4n){sup 235}Np reactions and the fragment yields for the fragments of the {sup 238}U(p,f) reaction have been calculated using obtained level density parameters. The results are compared to their corresponding experimental values. It was found that the extracted excitation functions and the fragment yields in the CTM coincide well with the experimental values in the low-energy region. This finding is according to the claim made by the Oslo group that the extracted level densities of {sup 238}U show a constant temperature behaviour.

  12. Studying nuclear level densities of 238U in the nuclear reactions within the macroscopic nuclear models

    In this work the nuclear level density parameters of 238U have been extracted in the back-shifted Fermi gas model (BSFGM), as well as the constant temperature model (CTM), through fitting with the recent experimental data on nuclear level densities measured by the Oslo group. The excitation functions for 238U(p,2nα)233Pa, and 238U(p,4n)235Np reactions and the fragment yields for the fragments of the 238U(p,f) reaction have been calculated using obtained level density parameters. The results are compared to their corresponding experimental values. It was found that the extracted excitation functions and the fragment yields in the CTM coincide well with the experimental values in the low-energy region. This finding is according to the claim made by the Oslo group that the extracted level densities of 238U show a constant temperature behaviour.

  13. Physical concept on the nuclear reactor with constellation type fissile fuels

    Under a prolong time neutron irradiation of 232Th by a strong constant neutron flux, a part of 232Th atoms will be converted into a series other nuclides as a result of successive neutron interaction. These neutron born daughter nuclides of 232Th consist of fissile nuclides such as 233U, 235U, 239Pu, 241Pu, ... and fertile nuclides, such as 233Pa, 2'34U, 236U, 237Np, 238Pu etc. As a rule the concentration of each daughter nuclide starts from zero and then increases gradually as the irradiation proceeds until reaching a saturated value and then decreases at a similar rate as the decreasing rate of 232Th. A reactor fueled with thorium and its whole family of neutron born daughter nuclides, with each daughter nuclide at its own saturated concentration, may possess some interesting properties. A preliminary study of the feasibility of such constellation type fissile fuels reactor is presented

  14. Neutron-induced capture cross sections of short-lived actinides with the surrogate reaction method

    The determination of neutron-capture cross sections of short-lived nuclei is opening the way to understand and clarify the properties of many nuclei of interest for nuclear structure physics, nuclear astrophysics and particularly for transmutation of nuclear wastes. The surrogate approach is well-recognized as a potentially very useful method to extract neutron cross sections for low-energy compound-nuclear reactions and to overcome the difficulties related to the target radioactivity. In this work we will assess where we stand on these neutron-capture cross section measurements and how we can achieve the short-lived Minor Actinides nuclei involved in the nuclear fuel cycle. The CENBG collaboration applied the surrogate method to determine the neutron-capture cross section of 233Pa (T1/2=27 d). The 233Pa(n,γ) cross section is then deduced from the measured gamma decay probability of 234Pa compound nucleus formed via the surrogate 232Th(3He,p) reaction channel. The obtained cross section data, covering the neutron energy range 0.1 to 1 MeV, have been compared with the predictions of the Hauser-Feshbach statistical model. The importance of establishing benchmarks is stressed for the minor actinides region. However, the lack of desired targets led us to propose recently the 174Yb (3He,pγ) reaction as a surrogate reaction for the (n,γ) predetermined benchmark cross section of 175Lu. An overview of the experimental setup combining gamma ray detectors such as Ge and C6D6 in coincidence with light charged particles ΔE-E Telescopes will be presented and preliminary results will be discussed. (authors)

  15. Neutron-induced capture cross sections of short-lived actinides with the surrogate reaction method

    Gunsing F.

    2010-03-01

    Full Text Available Determination of neutron-capture cross sections of short-lived nuclei is opening the way to understand and clarify the properties of many nuclei of interest for nuclear structure physics, nuclear astrophysics and particularly for transmutation of nuclear wastes. The surrogate approach is well-recognized as a potentially very useful method to extract neutron cross sections for low-energy compound-nuclear reactions and to overcome the difficulties related to the target radioactivity. In this work we will assess where we stand on these neutron-capture cross section measurements and how we can achieve the short-lived Minor Actinides nuclei involved in the nuclear fuel cycle. The CENBG collaboration applied the surrogate method to determine the neutron-capture cross section of 233Pa (T1/2 = 27 d. The 233Pa (n,γ cross section is then deduced from the measured gamma decay probability of 234Pa compound nucleus formed via the surrogate 232Th(3He,p reaction channel. The obtained cross section data, covering the neutron energy range 0.1 to 1 MeV, have been compared with the predictions of the Hauser-Feshbach statistical model. The importance of establishing benchmarks is stressed for the minor actinides region. However, the lack of desired targets led us to propose recently the 174Yb (3He,pγ reaction as a surrogate reaction for the (n,γ predetermined benchmark cross section of 175Lu. An overview of the experimental setup combining gamma ray detectors such as Ge and C6D6 in coincidence with light charged particles ΔE-E Telescopes will be presented and preliminary results will be discussed.

  16. Neutron-induced fission cross sections of short-lived actinides with the surrogate reaction method

    We present a review of the fission cross section measurements made by the CENBG collaboration over the last years using the surrogate reaction method. For example the neutron-induced fission cross sections of 233Pa (T1/2=27 d), 242Cm (T1/2=162.8 d) and 243Cm (T1/2=29.1 y) have been obtained by our group with this technique. The advantages and the difficulties of the surrogate method are discussed. Special attention is paid to the comparison between cross sections measured with the surrogate method and those obtained directly with neutrons at low energies. This comparison provides information on possible differences between the spin-parity distributions achieved in the two methods. We measured for the first time the fission cross section of 233Pa. Our results for 231Pa(n,f) revealed that the existing neutron-induced data overestimated the fission cross section above 1.5 MeV. The deduced 241Am(n,f) and 242Cm(n,f) cross sections agree with the available data obtained via neutron-induced reactions. The good agreement observed at the lowest neutron energies between the present results and the neutron-induced data for 242Cm(n,f) and 243Cm(n,f) indicates that the population of excited states generated by the transfer reactions used in this work is similar to the distribution fed in neutron induced reactions. This agreement illustrates the potential of the surrogate reaction method to provide neutron-induced fission cross sections for short-lived nuclei

  17. Measurement of the Thermal Neutron Capture Cross section of 237Np for the Study of Nuclear Transmutation

    Full text of publication follows: Accurate nuclear data of minor actinides are required for the study of nuclear transmutation of radioactive wastes. The 237Np is one of the most important minor actinides for this study because of its relatively large abundance in irradiated fuels. However, there are apparent discrepancies between the reported neutron capture cross sections of the 237Np for thermal neutrons. History on the measurements of the neutron capture cross section of 237Np for thermal neutrons is briefly presented first. Recent three data measured by a γ ray spectroscopic method are much smaller than those measured by other methods. To deduce the neutron capture cross section by an activation method with γ ray spectroscopy, the relevant γ-ray emission probabilities are used. These decay data could be an origin of the discrepancies on the neutron capture cross section of 237Np. To examine the hypothesis, we measured the relevant γ-ray emission probabilities of 233Pa and 238Np from the ratio of the emission rate to the activity. The obtained emission probabilities are used to correct the thermal neutron capture cross section of 237Np reported previously. The cross section is also independently determined by irradiating 237Np sample in the research reactor of Kyoto University and counting α rays emitted from 237Np and 238Pu with a Si detector. The measured emission probabilities of 233Pa and 238Np, and the neutron capture cross section of 237Np are compared with others from references. The results of the precise decay data explain the discrepancy on the neutron capture cross section of 237Np. Details of the experiments and results will be presented. (authors)

  18. Chromatographic purification of neutron capture molybdenum-99 from cross-contaminant radionuclides

    Technetium-99m is called the work horse, for many reasons, in nuclear medicine diagnostic purposes. It is produced as the β-decay of 99Mo radionuclide. Molybdenum-99 gel type generators are considered as a suitable alternative of the conventional chromatographic alumina columns loaded with fission molybdenum-99. 99Mo neutron-capture is cross-contaminated with radionuclides originated from activation of chemical impurities in the Mo target such 60C0, 65Zn, 95Zr, 175Hf, 181Hf, 86Rb, 134Cs, 141Ce, 152Eu, 140La,51Cr, 124Sb,46Sc, 54Mn, 59Fe and / or fast neutrons interactions with the stable isotopes of molybdenum such as 92mNb, 95Nb and 95Zr. To prevent contamination of the eluted 99mTc, successive purification methods were made. After complete dissolution of the irradiated target wrapped with thin Al foil in 5 M NaOH solution, hydrogen peroxide was added to start precipitation of Fe(OH)3. The formed Fe (III) minerals allow complete elimination of some radio contaminants from the molybdate solute such as 152Eu, 140La,141Ce, 45Mn and 92mNb in addition to partial elimination of 46Sc, 60Co and 59Fe radionuclides. The remaining supernatant was acidified by concentrated nitric acid to ph 9.5 for precipitation of Al(OH)3 with complete elimination of radio contaminants such as 95Zr 175Hf, 181Hf, 65Zn, 124Sb, 51Cr, 46Sc, 60Co and 59Fe. 134Cs and 86Rb radionuclides were not affected by precipitation of Fe(OH)3 or Al(OH)3. Chromatographic column of potassium nickel hexacyanoferrate (II) (KNHCF) has high affinity towards elimination of 134Cs and 86Rb radionuclides. Highly pure molybdate-99Mo solution was processed for preparation of zirconium molybdate gel generator with 99mTc eluate of high radionuclidic, radiochemical and chemical purity suitable for use in medical purposes.

  19. Hyperfine interactions studies in perovskite oxides of the type LaMO3 (M = Fe, Cr, Mn and Co)

    ABO3-type perovskite oxides have ideal cubic structure and usually show distortions to the orthorhombic or rombohedric symmetry. The A and B siteshave 12-fold and 6-fold oxygen coordination, respectively. Distortions of thecubic structure give rise to new electric, structural and magnetic propertieswhich have great technological and scientific interests. Magnetic dipole and electric quadrupole hyperfine interaction measurements were obtained using111In -> 111 Cd , 181 Hf -> 181 Ta e 140 La -> 140Ceradioactive nuclei substituting for the A or B sites via Perturbed Angulargamma-gamma Correlation technique(1-4). LaMO3 (M = Fe, Cr, Mn and Co)samples were prepared through the chemical route known as Sol-Gel techniqueand analyzed with x-ray diffraction. Both 111In and 181 Hf nuclei wereintroduced in to the sample during the chemical procedure and the 140 Lawas obtained by irradiating with neutrons in the IPEN reactor the natural Lapresent in the samples. One of the aims of this work was the analysis of theElectric Field Gradient (EFG) in the A and B sites as function oftemperature, crystal structure or the electronic characteristic of thetransition metal in the B site. The temperature range of the measurements wasabout from 4 K to 1400 K. The experimental EFG showed to be dependent of thesite occupation and the nuclear probe used in the measurements. Spintransition phenomena were also observed in LaCoO3 samples, which confirmed amodel used to interpret the spin properties in such compound.Crystallographic phase transition effects on the hyperfine parameters inperovskites where M = Fe, Cr and K4n were also analyzed. An additional aim ofthis work was to carry out measurements in the antiferromagnetic region ofthe systems with M = Fe, Cr and Mn using the three radioactive nuclei. Theresults for the magnetic interaction measurements showed a strong influenceof the substitutional sites in the supertransferred magnetic hyperfine fieldfor all the three probe nuclei. The

  20. Perturbed angular correlation investigation of the electric field gradient at 181Ta probe in the Hf2Ni7 compound

    Cekić Božidar Đ.

    2012-01-01

    Full Text Available The perturbed angular correlation method was employed to study the temperature dependence of electric field gradients at the 181Ta probe in the polycrystalline Hf2Ni7 compound. The temperature evolution of the sample content was measured using high-temperature X-ray diffraction. To check the magnetic order of the sample, magnetization measurements and additional perturbed angular correlation measurements with externally applied magnetic field were performed. All obtained spectra showed no evidence of magnetic order of the Hf2Ni7 phase. Within the experimental resolution of the apparatus, the measured electric field gradients at 181Ta probe for the two inequivalent 181Hf/181Ta sites in the Hf2Ni7 compound appeared as one in the range of 78-944 K. A single quadrupole interaction implies that the electric field gradients at the two Hf sites must be quite similar. At 293 K, the measured quadrupole interaction parameters are νQ = 433(1 MHz and η = 0.300(4. An increase of the quadrupole frequency and a gradual rising of the asymmetry parameter were observed with increasing temperature. The high-temperature X-ray diffraction indicated a build up of HfO2 above 693 K.

  1. Investigação de parâmetros hiperfinos dos óxidos semicondutores $SnO_{2}$ e $TiO_{2}$ puros e dopados com metais de transição 3d pela espectroscopia de correlação angular gama-gama perturbada

    Schell, Juliana

    This study aimed the use of nuclear technique Perturbed γ-γ Angular Correlation Spectroccopy (PAC) to measure the hyperfine interactions in thin films and powder samples of SnO2 and TiO2 pure and doped with transition metals to obtain a systematic investigation of defects and magnetism from an atomic point of view with the main motivation the application in spintronics. The work also focused on the preparation and characterization of samples by conventional techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and magnetization measurements. Pure samples of the films were measured by the systematic variation of thermal treatment and applied magnetic field. These measurements were performed in HISKP at the University of Bonn (Rheinische Friedrich-Wilhelms-Universität Bonn) using 111In(111Cd) or 181Hf (181Ta); at IPEN, in turn, these measurements were performed after the diffusion of the same probe nuclei. Another part of PAC measurements were carried out using 11...

  2. Site preference of Hf dopant in Ni3Al alloys: A perturbed angular correlation study

    Highlights: • PAC revealed that Hf atoms substitute on the Al sites in the Ni3Al alloy. • Hf dopants in Ni3Al induced two tetragonal distortions inside the L12 structure. • DFT calculations using the VASP, confirmed the site preference of Hf on the Al sites. - Abstract: Perturbed angular correlation measurements of the hyperfine interactions of the 181Ta probe in the polycrystalline intermetallic Ni3Al doped with 0.5 and 5 at.% Hf were performed in the temperature range 78-1230 K. The observed local hyperfine fields at the 181Hf/181Ta probe showed that Hf atoms are substituting on Al sites in the L12 structure of Ni3Al. The two minor electric quadrupole interactions that were found for each Ni3Al alloy are discussed taking into account the L12 cubic structure and its two tetragonal distortions: D022 and L60. The presence of two tetragonal transformations of the parent cubic L12 lattice in 0.5 at.% Hf and 5 at.% Hf doped Ni3Al was revealed by X-ray diffraction. The ab initio calculations, performed with the projector augmented wave method correctly reproduce the experimental results and enable discussion on the structural and electronic properties of the polycrystalline alloys. The experimental and theoretical investigations showed that hafnium additions prefer aluminum sites in Ni3Al

  3. Perturbed angular correlation studies of Hf binding to cyanocobalamin (vitamin B12)

    Gamma ray perturbed angular correlation (PAC) experiments have been carried out with 181Hf labeled cyanocobalamin. Evidence is presented which strongly indicates that Hf binds to vitamin B12 at the phosphate group linking the sugar residue to a side chain of the corrin ring system. Analysis of the time-differential PAC spectra for the crystalline Hf--B12 complex indicates a static electric quadrupole interaction at the Hf nucleus, corresponding to the electric field gradient generated by the chemical bonding. The magnitudes of the derived interaction parameters are similar to those found in Hf phosphate compounds. In aqueous solution, the Hf--B12 complex exhibits PAC spectra which appear to originate from two sources. Approximately 3/4 of the Hf nuclei experience a static electric quadrupole interaction with the same characteristic interaction frequency as in the solid, but with an increased asymmetry parameter. Approximately 1/4 of the Hf signal strength is attributable to a time-dependent quadrupole interaction with a relaxation constant indicative of an effective molecular entity comparable in size to the B12 molecule. This effect may be related to molecular motion in the solution. These results demonstrate the utility of the PAC experimental method for the study of macromolecular species in both the solid and solution forms, and opens possibilities for obtaining new information concerning the structure, orientation, and behavior of macromolecules

  4. Metabolism of radiohafnium in rats and hamsters: a possible analog of plutonium for metabolic studies

    The metabolism of radiohafnium (175Hf + 181Hf) was studied in male Sprague-Dawley rats and Chinese hamsters for periods of up to 168 days. The results were compared with similar data for 239Pu in the same rat strain. In rats and hamsters the radiohafnium organ distribution was skeleton > skin > muscle > liver at about 7 days postinjection. Retention of radiohafnium and plutonium was similar in plasma and liver, as were the retention time observed for other organs: Absorption of radiohafnium from the gastrointestinal tract of rats was <0.05%. Biochemical studies showed that the radiohafnium was bound mainly to the iron-transport protein, transferrin, in blood plasma and in the liver cytosol of both the rat and the hamster, as has been observed also for plutonium. The metabolic behavior of radiohafnium mimics, to a large extent, that of plutonium, and it is suggested that radiohafnium can serve as a non-α-particle-emitting analog of plutonium for metabolic, biochemical, and selected human investigations

  5. The metabolism of radiohafnium in rats and hamsters: a possible analog of plutonium for metabolic studies

    The metabolism of radiohafnium (175Hf + 181Hf) was studied in male Sprague-Dawley rats and Chinese hamsters for periods of up to 168 days. The results were compared with similar data for 239Pu in the same rat strain. In rats and hamsters the radiohafnium organ distribution was skeleton greater than skin greater than muscle greater than liver at about 7 days postinjection. Retention of radiohafnium and plutonium was similar in plasma and liver, as were the retention times observed for other organs: Absorption of radiohafnium from the gastrointestinal tract of rats was less than 0.05%. Biochemical studies showed that the radiohafnium was bound mainly to the iron-transport protein, transferrin, in blood plasma and in the liver cytosol of both the rat and the hamster, as has been observed also for plutonium. The metabolic behavior of radiohafnium mimics, to a large extent, that of plutonium, and it is suggested that radiohafnium can serve as a non-alpha-particle-emitting analog of plutonium for metabolic, biochemical, and selected human investigations

  6. Application of the perturbed angular correlation in the investigation of hyperfine interactions in compounds of hafnium, indium and cadmium with F1-, OH1- and EDTA ligands

    In this study the hyperfine parameters, including the dynamical nature, Perturbed Angular Correlation (PAC) spectroscopy was used to measure the hyperfine parameters in molecules of ligand compounds in solutions. The measurements were carried out at 295 K and 77 K using 111In → 111Cd, 181Hf → 181Ta and 111mCd →111Cd, as probe nuclei. Samples were prepared by adding a small volume of radioactive solution containing the probe nuclei in aqueous solution, buffer solution and ethylenediaminetetraacetic acid (EDTA) used as a ligand with pH 4.3 which correspond to the pH of the saturated EDTA solution and in buffer solution with pH between 9 and 10. The results made possible to understand the impact of each method for PAC measurements. Finally a comparative analysis for the several methods of inserting of the probe nuclei in the sample was made, considering chemical and nuclear aspects. The lack of measurements in this kind of samples justifies the importance of the obtained results. (author)

  7. Preparation of nuclear pure zirconium oxide from zircon

    Nuclear fuel used in the commercial nuclear reactors is cladded to confine the radioactivity. Zirconium based alloys standout as cladding materials because of their high mechanical strengh at high temperatures and pressures combined with good corrosion resistence and a low absorption cross section for thermal neutrons. However, a separation procedure to reduce the Hafnium content which occurs along with Zirconium and possesses a high neutron absorption cross section is needed. The preparation of nuclear pure Zirconium from Zircon is presented. The mineral was opened by alkali fusion at 4500C and later transformed into Zirconyl Nitrate via oxychloride and basic carbonate and purified by solvent extraction with TBP-HNO3. The solvent extraction process was developed using 95Zr and 181Hf tracers and studing process variables like acidity, nitrate and metal concentration. The extraction of Zirconium with 60% TBP in kerosene equilibrated with 5 M HNO3 increases with increasing acidity and nitrate concentration. The dependence of coefficient of distribution with acidity was of the power = 1.5 and with concentration of nitrate was of 3 sup(rd) power under the experimental conditions. The extraction of Zirconium and Hafnium reduces with increasing loading of the solvent but the separation factor remained approximately constant. (Author)

  8. Low-level gamma-ray spectrometry for analysing fusion plasma conditions

    Wieslander, J.S. Elisabeth [EU Commission - JRC - IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Department of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyvaeskylae (Finland)], E-mail: elisabeth.wieslander@gmail.com; Hult, Mikael [EU Commission - JRC - IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium)], E-mail: mikael.hult@ec.europa.eu; Bonheure, Georges [Laboratory for Plasma Physics, Association ' Euratom-Belgian State' , Royal Military Academy, Avenue de la Renaissance, 30 Kunstherlevinglaan, B-1000 Brussels (Belgium); Arnold, Dirk; Dombrowski, Harald [Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig (Germany); Gasparro, Joel [EU Commission - JRC - IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Laubenstein, Matthias [Laboratori Nazionali del Gran Sasso, S.S. 17/bis, km 18-910, I-67010 Assergi (AQ) (Italy); Marissens, Gerd [EU Commission - JRC - IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Vermaercke, Peter [SCK-CEN, Boeretang, B-2400 Mol (Belgium)

    2008-06-21

    A new method, combining activation by neutrons and charged particles with ultra low-level gamma-ray spectrometry, aimed at obtaining a better understanding and more adequate measurements of MeV particle leaks in magnetic fusion devices was studied here. A total of 36 samples containing Ti, LiF, B{sub 4}C and W were placed in a boron-nitride holder mounted on the ceiling of the JET Tokamak. The samples were activated by 63 pulses from a D-{sup 3}He plasma and were later measured using underground gamma-ray spectrometry. The radionuclides {sup 7}Be, {sup 46}Sc, {sup 54}Mn, {sup 56}Co, {sup 57}Co, {sup 58}Co, {sup 124}Sb, {sup 181}Hf, {sup 182}Ta, {sup 181}W and {sup 185}W were detected in several of the samples, with very low levels of activity of {sup 47}Sc and {sup 48}V found in a few of the samples. The various production channels for the radionuclides in question are discussed.

  9. Experimental Decomposition of the Wave-Functions of Deformed Nuclear States into their Components

    Increasing experimental and theoretical evidence for the complexity of low-lying states in deformed nuclei suggests the need for a variety of experimental approaches. The available experimental methods are summarized with particular emphasis on multi-reaction spectroscopy as a method of separating various components in the structure of deformed nuclear states. Level structures and other experimental parameters of 162Dy, 177Hf, 175Lu and 177Lu agree well with the Nilsson Model and the calculations of Soloviev as is typical of the most strongly deformed nuclei. In this paper emphasis is placed on nuclei in the transition region between spherical and deformed nuclei where experiment is expected to test the theory most severely. Experimental data on 153Sm, 155Gd, 186Re and 181Hf indicate the presence of strong coriolis coupling, of mixing of principal harmonic oscillator shells (ΔN = 2 mixing) and of complex phonon admixtures in low-lying states which probably require more sophisticated theoretical analysis. (author)

  10. Application of the perturbed angular correlation technique to the study of quadrupole coupling in solids

    The potentialities of the differential perturbed angular correlation (D. P. A. C.) technique for the study of solid state phenomena have been examined experimentally. Metallic and insulator samples of hafnium were studied, using the 181Ta 133-482 keV γ-γ cascade as a probe. The electrical field gradient coupling parameters were found to be strongly influenced by the lattice defects. In the case of hafnium metal, dislocations and impurities, mainly zirconium, increased the asymmetry parameter in the h. c. p. matrix. The static and dynamic quadrupole coupling supplied data on the structure and on the relaxation of octo-coordinated hafnium neutral complexes with tropolone, N-benzoyl-phenyl-hydroxylamine, cupferon and of the tetrapotassium tetra-kisoxalatohafniate (K4Hf(C2O4)4). The introduction of the probe 181Hf by thermal neutron capture in the two first solid compounds at low temperature (77 deg. K) has supplied new information on the site symmetries and nature of the recoil atoms. The D. P. A. C. results are compared with the parallel purely radiochemical hot atom observations in the same systems. (author)

  11. Measurement of Quadrupole Interactions in La1-xSrxCoO3 Perovskites Using TDPAC Technique

    The Perturbed Angular Correlation (PAC) technique was used to study the quadrupole interactions in the La1-xSrxCoO3 (0 ≤ x ≤ 0.08) perovskites using 111Cd and 181Ta probes. The radioactive parent nuclei 111In and 181Hf were introduced in the oxide lattice through chemical process during sample preparation and found to occupy only Co sites. The measurements cover a temperature range from 10 to 1150 K except the pure LaCoO3 for which an additional measurement was made at 4.2 K. The measured quadrupole frequencies were found to decrease linearly with increasing temperature as well as with increasing Sr concentration. Temperature dependence of quadrupole frequency in the pure LaCoO3 shows small discontinuities around 70-90 K and 500-600 K which have been atributed to thermally activated spin state transitions, from the low-spin (LS) ground state electronic configuration of Co+3 ion to the intermediate-spin (IS) state and from intermediate-spin (IS) state to high-spin (HS) state respectively, observed in some recent studies.

  12. Safety implications of reactivity variations in fast thorium ADSRs

    Highlights: ► A lumped fast reactor model is used to simulate reactivity and power variations in a fast thorium ADSR. ► Neutron flux changes produce reactivity changes due to shifts in the 233Pa and 233U populations. ► On reactor start-up, the reactivity will fall in the early part of the burn-up. ► On reactor shutdown the reactivity will increase. ► A thorium fuelled ADSR operating at keff ⩾ 0.990 is at risk from an accelerator-trip-induced post-shutdown criticality excursion. - Abstract: Nuclear power generation offers a reliable, low-impact and large-scale alternative to fossil fuels. However, concerns exist over the safety and sustainability of this method of power production, and it remains unpopular with some governments and pressure groups throughout the world. Fast thorium fuelled accelerator-driven sub-critical reactors (ADSRs) offer a possible route to providing further re-assurance regarding these concerns on account of their properties of enhanced safety through sub-critical operation combined with reduced actinide waste production from the thorium fuel source. The appropriate sub-critical margin at which these reactors should operate is the subject of continued debate. Commercial interests favour a small sub-critical margin in order to minimise the size of the accelerator needed for a given power output, whilst enhanced safety would be better satisfied through larger sub-critical margins to further minimise the possibility of a criticality excursion. Against this background, this paper examines some of the issues affecting reactor safety inherent within thorium fuel sources resulting from the essential 23290Th→23390Th→23391Pa→23392U breeding chain. Differences in the decay half-lives and fission and capture cross-sections of 233Pa and 233U can result in significant changes in the reactivity of the fuel following changes in the reactor power. Reactor operation is represented using a homogeneous lumped fast reactor model that can

  13. Use of rare-earth radionuclides and other bone-seekers in the evaluation of bone lesions in patients with multiple myeloma or solitary plasmacytoma

    Twenty-four patients with multiple myeloma and 4 with solitary plasmacytoma had total-body scans after intravenous injection of 67Ga-citrate alone (17 patients) or combined with other agents (11 patients). The latter included /sup 99m/Tc-diphosphonate (/sup 99m/Tc-DP), /sup 99m/Tc-polyphosphate (/sup 99m/Tc-PP), or /sup 99m/Tc-sulfur colloid (/sup 99m/Tc-SC) given alone or combined with 171Er, 157Dy, or 167Tm as citrate. In some patients more than one agent was compared to 67Ga and radiographic bone surveys. In general, localization of the rare-earth ''bone-seekers'' was poor except for 157Dy, which compared well with /sup 99m/Tc-PP and /sup 99m/TC-DP; 157Dy was also helpful in studies of the abdomen and pelvis because of its failure to concentrate in the gastrointestinal tract. No toxic or nonspecific effects were noted

  14. Investigation of hyperfine parameters of semiconductor oxides SnO2 and TiO2 pure and doped with 3d transition methods using spectroscopy of perturbed gamma-gamma angular correlation

    This study aimed the use of nuclear technique Perturbed γ-γ Angular Correlation Spectroscopy (PAC) to measure the hyperfine interactions in thin films and powder samples of SnO2 and TiO2 pure and doped with transition metals to obtain a systematic investigation of defects and magnetism from an atomic point of view with the main motivation the application in spintronics. The work also focused on the preparation and characterization of samples by conventional techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and magnetization measurements. Pure samples of the films were measured by the systematic variation of thermal treatment and applied magnetic field. These measurements were performed in HISKP at the University of Bonn (Rheinische Friedrich-Wilhelms-Universität Bonn) using 111In(111Cd) or 181Hf (181Ta); at IPEN, in turn, these measurements were performed after the diffusion of the same probe nuclei. Another part of PAC measurements were carried out using 111mCd(111Cd) and 117Cd (117In) in Isotope Mass Separator On-Line (ISOLDE) at Centre Européen Recherche Nucléaire (CERN). The measurements were performed from 8 K to 1173 K. After comparing results from macroscopic techniques with those from PAC, it was concluded that there is a correlation between the defects, magnetism and the mobility of charge carriers in semiconductors studied here. A step forward in the search for semiconductors, whose magnetic ordering allows its use in electronics based on spin. Some results have been published, including results obtained at the University of Bonn for the sandwich doctorate period [1-7]. (author)

  15. Investigation of hyperfine interactions in DNA and antibody of different lineages of mice infected by T. cruzi by perturbed gamma-gamma angular correlation spectroscopy

    In the present work perturbed angular correlation (PAC) spectroscopy was used to measured electric quadrupole interactions in DNA biomolecules of different mice lineages (A/J, C57BL/6, B6AF1, BXA1 e BXA2), samples of different isotypes of immunoglobulin G (IgG1, IgG2a e IgG2b) and active portions of complete and fragmented immunoglobulin responsible by the immune response. Electric quadrupole interactions were also measured in DNA nitrogenous bases (adenine, cytosine, guanine, thymine). PAC measurements were performed using 111In → 111Cd; 111mCd → 111Cd; 111Ag → 111Cd; e 181Hf → 181Ta as probe nuclei, and carried out at room temperature and liquid nitrogen temperature, in order to investigate dynamic and static hyperfine interactions, respectively. The biomolecule samples were directly marked with the radioactive parent nuclei, whose atom link to a certain site in the biomolecules. The biological materials as well as the probe nuclei were chosen to investigate the possibility to use PAC spectroscopy to measure hyperfine parameters at nuclei from metallic elements bound to biomolecules (including the use of different probe nuclei produced in the decay of parent nuclei of four different metals) and also to study the behavior of different biomolecules by means of the measured hyperfine parameters. Results show differences in the hyperfine interactions of probe nuclei bound to the studied biomolecules. Such differences were observed by variations in the hyperfine parameters, which depend on the type of biomolecule and the results also show that the probe nuclei atom bound to the molecule in some cases and in others do not. (author)

  16. Hyperfine interaction studies of the perovskite oxides of the type RCrO3 (R = Gd, Tb e Dy)

    ABO3 perovskite oxides have ideal cubic structure, however, some distortions in this type of structure may induce changes from cubic to orthorhombic or rhombroedric symmetry. The larger atoms A are located at the center of a cube, the B atoms are on 8 vertices and oxygen atoms occupy 12 positions in the middle of each side of the cube. Distortions in this structure may lead to new magnetic and electrical properties, with great scientific and technological interest. In this work RCrO3 (R = Gd, Tb, Dγ) compounds (also known as orthocromites) were studied. The samples were produced by means of sol-gel chemical procedure and analyzed by X-Ray Diffraction. The results showed a single phase with Pbnm space group. The perturbed gamma-gamma angular correlation (PAC) measurements were carried out using 181Hf(181Ta) and 111In(111Cd) nuclear probes, which substitute 'A' and 'B' positions respectively. The probe nuclei were introduced in the samples during the chemical procedures for preparation. One of the objectives of this work's was to study the hyperfine magnetic field and its variation as a function of temperature, crystallographic structure as well as the antiferromagnetic transition temperature (TN). The PAC Measurements were carried out in the temperature range of 20 to 300 K for R = Gd, Tb and 20 to 800 K in the case of R = Dγ from. Electric field gradient was also measured as a function of temperature. It was possible to observe the expected transition as well as the alignment of Cr spins, as found in literature. The Neel temperatures (TN) for investigated samples are ∼170 K, ∼164 K and ∼148 K for GdCrO3, TbCrO3 and DyCrO3 respectively. (author)

  17. Effects of Zr impurity on microscopic behavior of Hf metal

    Dey, S. K.; Dey, C. C.; Saha, S.

    2016-08-01

    Hf metal with ∼ 3 wt% Zr impurity has been reinvestigated by perturbed angular correlation (PAC) spectroscopy using a LaBr3(Ce)-BaF2 detector set up to understand the microscopic behavior of this metal with temperature. From present measurements, five quadrupole interaction frequencies have been found at room temperature where both pure hcp fraction (∼33%) with 12 nearest neighbor Hf surrounding the probe 181Hf atom and the probe-impurity fraction (∼33%) corresponding to 11 nearest neighbor Hf plus one dissimilar Zr atom are clearly distinguished. At room temperature, the results for quadrupole frequency and asymmetry parameter are found to be ωQ=51.6(4) Mrad/s, η=0.20(4) for the impurity fraction and ωQ=46.8(2) Mrad/s, η=0 for the pure fraction with values of frequency distribution width δ=0 for both components. At 77 K, only 1 NN Zr impurity (∼93%) and pure hcp (∼7%) components have been found with a value of δ ∼ 10% for the impurity fraction. A drastic change in microstructural configuration of Hf metal is observed at 473 K where the impurity fraction increases to ∼ 50% and the pure hcp fraction reduces to ∼ 15% with abrupt changes in quadrupole frequencies for both components. The pure fraction then increases with temperature and enhances to ∼50% at 973 K. In the temperature range 473-973 K, quadrupole frequencies for both components are found to decrease slowly with temperature. Using the Arrhenius relation, binding energy (B) for the probe-impurity pair and the entropy of formation are measured from temperature dependent fractions of probe-impurity and pure hcp in the temperature range 473-773 K. The three other minor components found at different temperatures are attributed to crystalline defects.

  18. Investigation of hyperfine parameters of semiconductor oxides SnO{sub 2} and TiO{sub 2} pure and doped with 3d transition methods using spectroscopy of perturbed gamma-gamma angular correlation; Investigacao de parametros hiperfinos dos oxidos semicondutores SnO{sub 2} and TiO{sub 2} puros e dopados com metais de transicao 3d pela espectroscopia de correlacao angular gama-gama perturbada

    Schell, Juliana

    2015-09-01

    This study aimed the use of nuclear technique Perturbed γ-γ Angular Correlation Spectroscopy (PAC) to measure the hyperfine interactions in thin films and powder samples of SnO{sub 2} and TiO{sub 2} pure and doped with transition metals to obtain a systematic investigation of defects and magnetism from an atomic point of view with the main motivation the application in spintronics. The work also focused on the preparation and characterization of samples by conventional techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and magnetization measurements. Pure samples of the films were measured by the systematic variation of thermal treatment and applied magnetic field. These measurements were performed in HISKP at the University of Bonn (Rheinische Friedrich-Wilhelms-Universität Bonn) using {sup 111}In({sup 111}Cd) or {sup 181}Hf ({sup 181}Ta); at IPEN, in turn, these measurements were performed after the diffusion of the same probe nuclei. Another part of PAC measurements were carried out using {sup 111}mCd({sup 111}Cd) and {sup 117}Cd ({sup 117}In) in Isotope Mass Separator On-Line (ISOLDE) at Centre Européen Recherche Nucléaire (CERN). The measurements were performed from 8 K to 1173 K. After comparing results from macroscopic techniques with those from PAC, it was concluded that there is a correlation between the defects, magnetism and the mobility of charge carriers in semiconductors studied here. A step forward in the search for semiconductors, whose magnetic ordering allows its use in electronics based on spin. Some results have been published, including results obtained at the University of Bonn for the sandwich doctorate period [1-7]. (author)

  19. Investigation of hyperfine interactions in DNA and antibody of different lineages of mice infected by T. cruzi by perturbed gamma-gamma angular correlation spectroscopy; Investigacao de interacoes hiperfinas em DNA e anticorpos de diferentes linhagens de camundongos frente a infeccao por T. cruzi pela epectroscopia de correlacao angular gama-gama perturbada

    Silva, Andreia dos Santos

    2012-07-01

    In the present work perturbed angular correlation (PAC) spectroscopy was used to measured electric quadrupole interactions in DNA biomolecules of different mice lineages (A/J, C57BL/6, B6AF1, BXA1 e BXA2), samples of different isotypes of immunoglobulin G (IgG1, IgG2a e IgG2b) and active portions of complete and fragmented immunoglobulin responsible by the immune response. Electric quadrupole interactions were also measured in DNA nitrogenous bases (adenine, cytosine, guanine, thymine). PAC measurements were performed using {sup 111}In {yields} {sup 111C}d; {sup 111mC}d {yields} {sup 111}Cd; {sup 111}Ag {yields} {sup 111}Cd; e {sup 181}Hf {yields} {sup 181}Ta as probe nuclei, and carried out at room temperature and liquid nitrogen temperature, in order to investigate dynamic and static hyperfine interactions, respectively. The biomolecule samples were directly marked with the radioactive parent nuclei, whose atom link to a certain site in the biomolecules. The biological materials as well as the probe nuclei were chosen to investigate the possibility to use PAC spectroscopy to measure hyperfine parameters at nuclei from metallic elements bound to biomolecules (including the use of different probe nuclei produced in the decay of parent nuclei of four different metals) and also to study the behavior of different biomolecules by means of the measured hyperfine parameters. Results show differences in the hyperfine interactions of probe nuclei bound to the studied biomolecules. Such differences were observed by variations in the hyperfine parameters, which depend on the type of biomolecule and the results also show that the probe nuclei atom bound to the molecule in some cases and in others do not. (author)

  20. Deposition of Thorium and Plutonium oxides in the respiratory tract of the mouse

    Studies are being made of the early and later effects of plutonium oxide (239PuO2) deposited in the mouse lung and of the dependence on particle size and dose. A system has been developed for preparing discrete size fractions of PuO2, by using water sedimentation, for their aerosolization and administration to mice by inhalation. Experiments were carried out, to commission the exposure system, with sized thorium oxide (ThO2) particles labeled with 233Pa (half-life, 27 days) by neutron activation. Regional depositions of particles with activity median aerodynamic diameters (AMAD's) of 1.4, 1.6, and 2.0 μm were measured. Although deposition in the respiratory tract increased with particle size, deposition in the alveolar region decreased. Alveolar-deposition data from a number of PuO2 inhalation exposure experiments are also presented. Some inconsistencies were shown between the alveolar deposition of ThO2 and of PuO2. Lobar distributions of alveolar-deposited ThO2 and PuO2 were not homogeneous. The inhomogeneities increased with particle size. Data obtained from ThO2 experiments indicated that the clearances of dust from the nasal passages, airways, gastrointestinal tract, and pelt were quite rapid. Levels of pelt contamination were soon reduced, by the animals' own preening, to levels that would be safe for personnel involved in PuO2 experiments

  1. Contribution to the study of electromagnetic transitions in deformed nuclei

    This work deals with the interaction between the nucleus and the electromagnetic field. We have adapted the Nilsson formalism to deformed uneven-uneven nuclei. We have studied the probability of gamma transitions and energy levels. In the first chapter we have recalled the improvements brought successively in nuclear models to describe electromagnetic transitions, we begin with the spherical shell model, then present the rotational model and end with the unified model. We have applied the unified model to deformed uneven-uneven nuclei in order to compute probability transitions and energy levels. We have set an experiment to compare computed values and experimental data. Our gamma spectrometry equipment is composed of NaI(Tl) crystals and EMI-1954 photomultipliers. We have tested our method by studying the gamma rays appearing during the decay reaction: 233Pa → 233U. We have measured the energy levels of 234Pa and the Nilsson formalism appears to give good results for low energy levels. We have also studied the decay reaction: 231Pa → 227Ac, we give detailed gamma spectra and a preliminary energy level scheme but the interpretation of the energy levels with the unified model is all the more complicated because of the high density of levels between 0 and 130 KeV

  2. Reactivity control capability of fuel-salt processing system in a molten-salt breeder reactor

    An evaluation is made of the reactivity control capability of the fuel processing system (FPS) in a molten-salt breeder reactor. The principal functions required of the FPS are: (a) Isolation of 233Pa from regions of high neutron flux during its decay to 233U, and (b) the removal of fission products from the system. The FPS can very usefully serve also to control the primary system reactivity by appropriately utilizing its function of extracting uranium and reconstituting the fuel contained in the salt. The principles of operation are quite similar to the chemical shim control system currently installed in PWR's whereby the core reactivity, affected by changes in the moderator temperature, fuel burnup and transient Xe, is adjusted by regulating the concentration of boric acid introducted in the moderator as neutron absorber. The present study examines the capability of the FPS to follow transient Xe as in PWR's, and proves that the FPS should effectively serve as a system for adjusting not only long-term changes in reactivity but also short-term transient variations without any accompanying difficulties foreseen in operation. (auth.)

  3. A simplified burnup calculation strategy with refueling in static molten salt reactor

    Molten Salt Reactors, by nature can be refuelled and reprocessed online. Thus, a simulation methodology has to be developed which can consider online refueling and reprocessing aspect of the reactor. To cater such needs a simplified burnup calculation strategy to account for refueling and removal of molten salt fuel at any desired burnup has been identified in static molten salt reactor in batch mode as a first step of way forward. The features of in-house code ITRAN has been explored for such calculations. The code also enables us to estimate the reactivity introduced in the system due to removal of any number of considered nuclides at any burnup. The effect of refueling fresh fuel and removal of burned fuel has been studied in batch mode with in-house code ITRAN. The effect of refueling and burnup on change in reactivity per day has been analyzed. The analysis of removal of 233Pa at a particular burnup has been carried out. The similar analysis has been performed for some other nuclides also. (author)

  4. Thorium conversion optimization in two-fluid molten-salt reactor

    Molten-Salt Reactors (MSR) are an attractive reactor system for various purposes. They can be designed to be operated in a fast neutron spectrum for spent fuel transmutation or in a thermal spectrum. Thermal MSRs provide an ideal platform for conversion of thorium to 233U. Flowing salt can be continuously reprocessed to minimize neutron losses due to neutron absorption in fission products. This study deals with a static neutronic optimization of a Two-Fluid MSR concept. Such a reactor features two separated molten-salt streams in the reactor core. One salt contains fissile material 233U, the other thorium. Separation of these streams improves the conversion capabilities of MSRs. Such a design was analysed for Molten-Salt Breeder Reactor (MSBR) development. This reactor was not realized, but it is used as a reference for this study. Monte-Carlo code MCNP5 was used to model a simplified MSBR core and for calculation of the breeding capabilities of this design. Several basic geometric parameters were selected for evaluation of their effect on characteristics of the reactor. Based on this analysis, an improved designed was prepared with shorter fissile material doubling time. The whole analysis was carried out for fresh fuel composition. It is possible to expect that on-line fuel reprocessing will limit fuel composition changes during reactor operation. Only effect of 233Pa accumulation on the thorium conversion was studied for several fuel reprocessing rates. (author)

  5. Neutronic performance of ({sup Reprocessed}U/Th)O{sub 2} fuel in CANDU 6 reactor

    Gholamzadeh, Z. [Talca Univ. (Chile). Dept. of Energy; Mirvakili, S.M. [Nuclear Science and Technology Research Institute, Reactor Research School, Tehran (Iran, Islamic Republic of); Feghhi, S.A.H. [Shahid Beheshti Univ., Dept. of Radiation Application, Tehran (Iran, Islamic Republic of)

    2015-07-15

    Utilization of thorium-based fuel in different reactors has been under investigation for several decades. In fact, excellent breeding features, rather flattened distribution of power as well as proliferation resistance of such fuel cycle draws the attention towards utilization of this type of fuel in nuclear power technology. In the present study, the neutronic performance of a typical thorium core loading is addressed. In this configuration, a mixed uranium and thorium oxide is loaded in CANDU 6 reactor. The obtained results determine a total peaking factor of 2.73 for the proposed configuration. The values obtained for the β and the β{sub eff} are 332 and 303 pcm respectively. The core reactivity coefficients were more negative comparing the CANDU 6 loaded with {sup nat}UO{sub 2}. The initial fissile material loaded in the core increased by a factor of 1.5 after 730 GWd burnup. The obtained burn-up results show the core reactivity variations were highly positive after 6 and 12 h shut down because of considerably high buildup of {sup 233}Pa after 1-year core operation at 2000 MW power.

  6. Some analytical aspects of the technologies using molten fluorides

    Analytical activities accompanying the development or a molten fluoride reactor can be divided into 3 groups: (i) Balance analyses of fissile and fertile isotopes and their isotope composition; (ii) Analytical control of the reactor process; and (iii) Special analyses and measurements for physical reactor parameters determination. The first group is formed by the precise determination of U, Pu, Th content and isotope composition. Both destructive and non-destructive methods are recommended. The suitable methods are the following: chemical methods (e.g. titrimetric methods), x-ray fluorescence and IDA with alpha- or mass-spectrometric ending. The mass-spectrometry, ICP-MS and gamma-spectrometry are preferred for the isotope analysis. The analyses important for operating reactor form the second group. There is the determination of important activation and fission products as: 233Pa, 137Cs, 90Sr, 144Ce, rare earth elements, transuranium elements, tritium etc. The methods commonly used are based on gamma-spectrometry, alpha-spectrometry, ICP-MS and LSC. In the last group the analyses used for the determination of reactor parameters or the chemical form of some elements in the melt of fluorides can be included. As an example the mass-spectrometric determination of the capture-to-fission ratio or the use of FTIR spectrometry for the determination of the chemical form of fluoride melt. The paper describes the results of measurements obtained for the systems similar to fluoride melts. The possibility of the methods application is discussed. (author)

  7. Neutron-induced capture cross sections via the surrogate reaction method

    The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. In this method, the compound nucleus is produced via an alternative (surrogate) reaction and its decay (by fission, gamma or neutron emission) is measured in coincidence with the outgoing appropriate charged particle. This technique has enabled neutron-induced cross sections to be extracted for nuclear reactions on short-lived nuclei that otherwise could not be measured. The CENBG collaboration has successfully applied this technique to determine the neutron-induced fission cross sections of several short-lived nuclei such as 233Pa, 242,243Cm and 241Am. These data are very important for the development of the Th/U cycle and for minor actinide transmutation. We currently investigate whether this powerful technique can also be used to determine the neutron-induced capture cross sections. For this purpose we will use the surrogate reaction 174Yb(3He,pγ)176Lu to infer the well known 175Lu(n,γ) cross section and compare the results with the directly measured neutron-induced data. The experimental set-up and the first results will be presented. We will also discuss our future plans to use the surrogate method for extracting actinides (n,γ) cross sections. (authors)

  8. Contribution to the study of the phosphoric complexes of U-6, Th-4 and of Cd-2 in concentrate phosphoric acid

    The behaviour study of uranium-6, thorium-4 and cadmium-2 in phosphoric and sulfophosphoric media has been carried out using liquid-liquid extraction. The chelating agent used is di-2 ethylhexylphosphoric acid. This study is effected with the radioactive tracers technique using 233-U, 230-U, 227-Th and 109-Cd. The uranium radioisotopes are obtained according to the following nuclear reactions: 232-Th (n,beta sub(-)) 239-U -> 233-Pa -> 233-U and 232-Th (p,3 n) 230-Pa -> 230-U. The 227-Th derives from beta sub(-) decay of 227-Ac and the 109-Cd is obtained with atomic pile. These different radioisotopes are purified on resin and by solvent extraction before their utilization. The distribution data exploitation has conducted, on one hand, to identify the chelates extracted in the organic phase, and on the other hand, to calculate their stability constant. The obtained results permit to describe the phosphoric media containing these impurities, particularly the industrial sulfophosphoric media and to clear up the reactivity of the cations: (UO sup 2) sub(2+), Th sub(4+) and Cd sub(2+) in a range of activity and phosphoric acid concentration never reached: 0.7<=ph<=4 and 0<=C sup[Hsup3 POsup4] <= 10 M. 22 tabs., 51 figs., 159 refs.(F.M)

  9. Investigations on production of 233U using few pin thoria in existing PHWRs

    Thorium is not a fissile material and cannot be used to either start or sustain the chain reaction. Therefore, a reactor using thorium would also need either enriched uranium or plutonium to sustain the chain reaction until enough of the thorium has converted to fissile 233U. In order to retrieve and reprocess the irradiated fuel, the bundle is designed with few thoria pins and rest SEU pins. In the present study, different pin configurations of thoria in 19 and 37 element fuel clusters of Indian PHWRs have been considered. The lattice calculations have been done using the multi-group transport theory code CLUB. The variations of k∞ versus burn up are depicted in the paper. The production of 233U (considering also the decay of 233Pa into 233U) is also shown. Average discharge burn ups of the order 20 and 17 GWd/Te can be achieved with the use of thoria pins in 19 and 37 element fuel clusters respectively with appropriate bundle shift scheme. Derating of power is required during operation because of bundle power restrictions. It is found that 1 pin thoria configuration is preferable from the point of view of fuel requirements and power reduction consideration. Since 37 element fuel cluster used in 540 MWe PHWR fuel has large margins in bundle power, the restriction in power operation is much less than 19 element fuel cluster used in 220 MWe PHWR

  10. Application of INAA complementary gamma ray photopeaks to homogeneity study of candidate reference materials

    Characterization and certification of reference materials, RMs, is a complex task involving many steps. One of them is the homogeneity testing to assure that key property values will not present variation among RM bottles. Good precision is the most important figure of merit of an analytical technique to allow it to be used in the homogeneity testing of candidate RMs. Due to its inherent characteristics, Instrumental Neutron Activation Analysis, INAA, is an analytical technique of choice for homogeneity testing. Problems with sample digestion and contamination from reagents are not an issue in INAA, as solid samples are analyzed directly. For element determination via INAA, the activity of a suitable gamma ray decay photopeak for an element is chosen and it is compared to the activity of a standard of the element. An interesting possibility is the use of complementary gamma ray photopeaks (for the elements that present them) to confirm the homogeneity test results for an element. In this study, an investigation of the use of the complementary gamma ray photopeaks of 110mAg, 82Br, 60Co, 134Cs, 152Eu, 59Fe, 140La, 233Pa (for Th determination), 46Sc and 75Se radionuclides was undertaken in the between bottle homogeneity study of a mussel candidate RM under preparation at IPEN - CNEN/SP. Although some photopeaks led to biased element content results, the use of complementary gamma ray photopeaks proved to be helpful in supporting homogeneity study conclusions of new RMs. (author)

  11. The Determination of Uranium (U) and Thorium (Th) has been done Using Active and Passive Method in Sea Sediment Samples

    The detemination of uranium (U) and thorium (Th) has been done using active and passive method in sea sediment samples. in the active method, samples were irradiated in the Research Reactor, Siwabessy BATAN, Serpong at a thermal neutron with fluxes 1013n.cm-2s-1. U and Th was determined as 238U(n,γ)239Np and 232Th(n,γ)233Pa at energies of 277,6 keV and 311,8 keV, respectively. In the Passive method, U and Th was determined from the daughters product of 214Pb and 212Pb at energies of 351.9,2 keV and 238.63 keV, respectively. Quantitative analysis was done by comparing the sample with reference materials IAEA SL-1 (active method) and IAEA-375 (passive method). Concentration of U and Th on the sea sediment sample using both methods show that the results are close with each other

  12. Neutron Radiative Capture Cross Section of 232Th in the Energy Range from 0.06 to 2 MeV

    The neutron capture cross section of 232Th has been measured relative to σ(n, γ) for 197Au and σ(n,f) for 235U in the energy range from 60 keV to 2 MeV. Neutrons were produced by the 7Li(p,n) and T(p,n) reactions at the 4-MV Van de Graaff Accelerator of CEN Bordeaux-Gradignan. The activation technique was used, and the cross section was measured relative to the 197Au(n,γ) standard cross section up to 1 MeV. The characteristic gamma lines of the product nuclei 233Pa and 198Au were measured with a 40% high-purity germanium detector. Above this energy, the reaction 235U(n,f) was also used as a second standard, and the fission fragments were detected with a photovoltaic cell. The results, after applying the appropriate corrections, indicate that the cross sections are close to the JENDL-3 database values up to 800 keV and over 1.4 MeV. For energies in the intermediate range, our values are slightly lower than those from all the libraries

  13. Np Analysis in IAT-Samples Containing <10 Microgram Pu

    A method for the determination of neptunium to plutonium in safeguards samples containing less than 10 microgram Pu is presented. The chemical treatment and the optimized measurement conditions for gamma spectrometry are reported. This method is based on thermal ionization mass spectrometry (TIMS) after chemical treatment and separation and was validated with mixtures of U, Pu and Np certified reference materials and using the 237Np standard addition method, followed by separation of the waste fraction and gamma spectrometric analysis. The highest sensitivity, precision and accuracy in the determination of the Np:Pu ratio at microgram levels of Pu is achieved by evaluating 241Pu and 233Pa after measuring the adsorbent with a well-type gamma detector 3 weeks after chemical treatment. The repeatability of determining the Np:Pu ratio is estimated to be 5%, the maximum uncertainty as determined from comparing the 4 measurement modes is within ± 10% for samples containing 3 μg Pu, while being within ± 20% for 0.4 μg Pu. (authors)

  14. Ultratrace characterization of AlSiCu sputter targets for Th, U and 35 other elements by neutron activation analysis

    Instrumental and radiochemical neutron activation analysis has been applied to a comprehensive trace characterization of AlSiCu sputter targets. By instrumental neutron activation analysis via long-lived indicator radionuclides, up to 33 elements were assayed with detection limits between 0.01 and 200 ng x g-1. The high activity of 64Cu and 24Na produced from the matrix significantly limits the instrumental performance via short- and medium-lived indicator dionuclides. For this reason, a radiochemical separation was developed based on adsorption of 24Na on hydrated antimony pentoxide and extraction of 64Cu by diethylammonuim diethyldithiocarbamate from HCl medium. By this radiochemical method, As, Ga, K, La, Mn, Mo, Re, Sb, U and W could be assayed via medium-lived radionuclides and the achievable limits of detection were between 0.1 and 25 ng x g-1. Further improvement of detection limits for U and Th was achieved by a selective radiochemical separation of 239Np and 233Pa on a Dowex 1 x 8 column in HF and HF/NH4F medium providing limits of detection for U and Th of 0.06 and 0.02ng x g-1 respectively. These techniques were applied to the analysis of two AlSiCu sputter target materials. Results are compared with those of glow discharge mass spectrometry. (author). 24 refs., 4 figs., 5 tabs

  15. EXTENSION OF THE NUCLEAR REACTION MODEL CODE EMPIRE TO ACTINIDES NUCLEAR DATA EVALUATION.

    CAPOTE,R.; SIN, M.; TRKOV, A.; HERMAN, M.; CARLSON, B.V.; OBLOZINSKY, P.

    2007-04-22

    Recent extensions and improvements of the EMPIRE code system are outlined. They add new capabilities to the code, such as prompt fission neutron spectra calculations using Hauser-Feshbach plus pre-equilibrium pre-fission spectra, cross section covariance matrix calculations by Monte Carlo method, fitting of optical model parameters, extended set of optical model potentials including new dispersive coupled channel potentials, parity-dependent level densities and transmission through numerically defined fission barriers. These features, along with improved and validated ENDF formatting, exclusive/inclusive spectra, and recoils make the current EMPIRE release a complete and well validated tool for evaluation of nuclear data at incident energies above the resonance region. The current EMPIRE release has been used in evaluations of neutron induced reaction files for {sup 232}Th and {sup 231,233}Pa nuclei in the fast neutron region at IAEA. Triple-humped fission barriers and exclusive pre-fission neutron spectra were considered for the fission data evaluation. Total, fission, capture and neutron emission cross section, average resonance parameters and angular distributions of neutron scattering are in excellent agreement with the available experimental data.

  16. Calculation of fission reactions within the MM-RNR model

    In the past fission-fragment properties and cross-sections for 235,238U(n, f), 237Np(n, f), 239Pu(n, f) and 252Cf(SF) have been investigated. The interpretation of the experimental data in the frame of the multi-modal random neck-rupture (MM-RNR) model has been incorporated into the most recent evaluation exercise on neutron-induced fission cross-section and prompt-neutron emission data in the actinide region of the chart of nuclides. The three most dominant fission modes were considered, the two asymmetric standard I (S1) and standard II (S2) modes and the symmetric superlong (SL) mode, namely. Except for 252Cf, de-convoluted modal fission cross-sections as well as prompt neutron multiplicity and spectra have been calculated in the energy range from 0.01 MeV to 5.5 MeV in excellent agreement with experimental data. In addition, the obtained fission-mode branching ratios allow the calculation of fission-fragment yield and energy distributions where no experimental data exist. Most recently the first ever-direct measurement of the neutron-induced fission cross-section of 233Pa has been performed at IRMM. The subsequent evaluation suggests a radical revision of today's evaluated data files. (author)

  17. Thorium fuel cycle concept for KAERI's accelerator driven system project

    Korea Atomic Energy Research Institute (KAERI) has been carrying out accelerator driven system related research and development called HYPER for transmutation and energy production. HYPER program is aiming to develop the elemental technologies for the subcritical system by 2001 and build a small bench scale test facility (∼5MW(th)) by the year 2006. Some major features of HYPER have been developed and employed, which are on-power fueling concepts, a hollow cylinder-type metal fuel, and Pb-Bi as a coolant and spallation target material. Another fuel cycle concept for HYPER has been also studied to utilize thorium as a molten salt form to produce electricity as well as to transmute TRU elements. At the early stage of the fuel cycle, fissile plutonium isotopes in TRU will be incinerated to produce energy and to breed 233U from thorium. Preliminary calculation showed that periodic removal of fission products and small amount of TRU addition could maintain the criticality without separation of 233Pa. At the end of the fuel cycle, the composition of fissile plutonium isotopes in TRU was significantly reduced from about 60% to 18%, which is not attractive any more for the diversion of plutonium. Thorium molten salt fuel cycle may be one of the alternative fuel cycles for the transmutation of TRU. The TRU remained at the end of fuel cycle can be incinerated in HYPER having fast neutron spectrums. (author)

  18. Erbium-169 labeled hydroxyapatite particulates for use in radiation synovectomy of digital joints. A preliminary investigation

    Chakraborty, Sudipta; Das, Tapas; Chirayil, Viju; Lohar, Sharad P. [Bhabha Atomic Research Centre, Mumbai (India). Radiopharmaceuticals Div.; Sarma, Haladhar Dev [Bhabha Atomic Research Centre, Mumbai (India). Radiation Biology and Health Services Div.

    2014-07-01

    Erbium-169 [T{sub 1/2} = 9.4 d, E{sub β(max)} = 342 keV (45%) and 351 keV (55%), E{sub γ} = 110.5 KeV (0.0014%)] is the most preferred radionuclide for radiation synovectomy (RSV) of digital joints. Radiolabeled particulates of appropriate size, wherein the radionuclide is irreversibly attached to the preformed particles, offer distinct advantages as the radiopharmaceuticals for use in RSV over other radiotherapeutic agents in terms of minimal leakage of radioactivity from the joint cavity. Hyroxyapatite (HA) particles, regarded as one of the most suitable carrier moiety for radiosynoviortheses applications, have been envisaged for labeling with {sup 169}Er with an aim to developing an agent for RSV of digital joints. Erbium-169 was produced with a specific activity of 415 ± 23 MBq/mg and radionuclidic purity of 99.22 ± 0.17% (both at the end of bombardment) by thermal neutron irradiation of enriched (98.2% in {sup 168}Er) erbium target at a flux of ∝ 8 x 10{sup 13} n/cm{sup 2}s for 21 d. HA particles (1-10 μm size), synthesized in-house, were labeled with {sup 169}Er in high yield and radiochemical purity (> 99%) using 5 mg of HA particulates at pH 7.5. The radiolabeled particulates showed excellent in vitro stability in normal saline and human serum. Biodistribution and imaging studies (using {sup 171}Er-HA) carried out in normal Wistar rats following intra-articular injection of {sup 169}Er-HA particulates in the knee joint showed near-complete retention of injected radioactivity within the synovial cavity with almost no activity leaching out to the other organs/tissue. (orig.)

  19. Erbium-169 labeled hydroxyapatite particulates for use in radiation synovectomy of digital joints. A preliminary investigation

    Erbium-169 [T1/2 = 9.4 d, Eβ(max) = 342 keV (45%) and 351 keV (55%), Eγ = 110.5 KeV (0.0014%)] is the most preferred radionuclide for radiation synovectomy (RSV) of digital joints. Radiolabeled particulates of appropriate size, wherein the radionuclide is irreversibly attached to the preformed particles, offer distinct advantages as the radiopharmaceuticals for use in RSV over other radiotherapeutic agents in terms of minimal leakage of radioactivity from the joint cavity. Hyroxyapatite (HA) particles, regarded as one of the most suitable carrier moiety for radiosynoviortheses applications, have been envisaged for labeling with 169Er with an aim to developing an agent for RSV of digital joints. Erbium-169 was produced with a specific activity of 415 ± 23 MBq/mg and radionuclidic purity of 99.22 ± 0.17% (both at the end of bombardment) by thermal neutron irradiation of enriched (98.2% in 168Er) erbium target at a flux of ∝ 8 x 1013 n/cm2s for 21 d. HA particles (1-10 μm size), synthesized in-house, were labeled with 169Er in high yield and radiochemical purity (> 99%) using 5 mg of HA particulates at pH 7.5. The radiolabeled particulates showed excellent in vitro stability in normal saline and human serum. Biodistribution and imaging studies (using 171Er-HA) carried out in normal Wistar rats following intra-articular injection of 169Er-HA particulates in the knee joint showed near-complete retention of injected radioactivity within the synovial cavity with almost no activity leaching out to the other organs/tissue. (orig.)

  20. Amster: a molten-salt reactor concept generating its own 233U and incinerating transuranium elements

    In the coming century, sustainable development of atomic energy will require the development of new types of reactors able to exceed the limits of the existing reactor types, be it in terms of optimum use of natural fuel resources, reduction in the production of long-lived radioactive waste, or economic competitiveness. Of the various candidates with the potential to meet these needs, molten-salt reactors are particularly attractive, in the light of the benefits they offer, arising from two fundamental features: - A liquid fuel does away with the constraints inherent in solid fuel, leading to a drastic simplification of the fuel cycle, in particular making in possible to carry out on-line pyrochemical reprocessing; - Thorium cycle and thermal spectrum breeding. The MSBR concept proposed by ORNL in the 1970's thus gave a breeding factor of 1.06, with a doubling time of about 25 years. However, given the tight neutron balance of the thorium cycle (the η of 233U is about 2.3), MSBR performance is only possible if there are strict constraints set on the in-line reprocessing unit: all the 233Pa must be removed from the core so that it can decay on the 233U in no more than about ten days (or at least 15 tonnes of salt to be extracted from the core daily), and the absorbing fission products, in particular the rare earths, must be extracted in about fifty days. With the AMSTER MSR concept, which we initially developed for incinerating transuranium elements, we looked to reduce the mass of salt to be reprocessed in order to minimise the size and complexity of the reprocessing unit coupled to the reactor, and the quantity of transuranium elements sent for disposal, as this is directly proportional to the mass of salt reprocessed for extraction of the fission products. Given that breeding was not an absolute necessity, because the reactor can be started by incinerating the transuranium elements from the spent fuel assemblies of current reactors, or if necessary by loading

  1. Instrumental neutron activation analysis in geochemistry. Emphasis on spectral and uranium fission product interferences

    Full text: Since the advent of semiconductor detectors, several contributions to the INAA methodology allowed to resolve and analyse complex gamma ray spectra enhancing thus, the reliability of this analytical technique. Despite attainable performances, some difficulties due to spectral and fission product interferences remain affecting thus the reliability of analytical results. A typical case is that discussed by Landsberger et al. on the determination of Sm in the presence Gd, U and Th. In practice spectral interferences in INAA are resolved by allowing shorter-lived radionuclides to decay and counting the remaining long-lived radionuclides. It is also proceeded to the subtraction of contributions of interfering radionuclides using their interference free analytical photopeaks. Both of them are tedious and time consuming, particularly if radionuclides of interest have similar γray spectra, as is the case for 153Sm and 153Gd to which further interferences come from 239Np and 233Pa. On the other hand, the presence of fissionable products such as U and Th in geological samples, and particularly in high grade U and Th samples, enhances difficulties in the accuracy attainable by instrumental neutron activation analysis. They give rise, during irradiation, to identical (n,γ) products from isotopes of natural elements. The present contribution deals with 2 aspects of resolution of interferences in instrumental neutron activation analysis: 1. The application of a multicomponent method for the resolution of spectral interferences in gamma spectrometry using simultaneous equations method. Assume m elements are to be determined by INAA whose (n,γ) products interfere at their n analytical γ-rays. An overall analytical response can be assumed to consist of several additive individual responses from m interfering radionuclides. The mathematical terms can be expressed by means of the following equation: Pn=k+Σain Aiεi Pn = Photopeak area at the specific interfering n

  2. Potential advantages and drawbacks of the thorium fuel cycle in relation to current practice: A BNFL view

    Thorium could extend the availability of nuclear fuel beyond the necessarily finite reserves of uranium ore, particularly if used in a thermal breeder system with the uranium-233 formed by transmutation serving as fissile content. The cycle produces virtually no plutonium, nor the other transuranic elements that contribute substantially to anxieties about the disposal of nuclear waste. Thorium-based fuels have therefore been proposed as a substitute for uranium, both in existing power reactors and in advanced systems such as the 'energy amplified,' with a sub-critical assembly of fissile and fertile material driven by an independent neutron source. The benefits and drawbacks of thorium need careful evaluation. A self-sustaining, breeding cycle should be possible with good neutron economy, but whether existing modern reactor types meet that condition is questionable, particularly at high fuel ratings where parasitic absorption by 233Pa tends to pre-empt decay to 233U. Radiation from thallium-208, formed in the decay of by-product 232U and 228Th, complicates storage and refabrication. Public perception would favour the cycles producing no transuranic elements and its particular capacity for consuming those already stocked; however, although they contribute largely to the long-lived content of nuclear waste, fission products also do likewise, and since the amounts of these are not greatly changed, any resulting improvement to long-term safety would by no means be decisive. BNFL has recently assessed the outstanding development requirements of the Thorex process. Commercial realisation would require a huge investment with no certainty of success. So far, the potential advantages do not seem likely to justify the risk, but the position is being kept under review in case the balance should be seen to shift. (author)

  3. Testing of ENDF71x: A new ACE-formatted neutron data library based on ENDF/B-VII.1

    Gardiner, S. J.; Conlin, J. L.; Kiedrowski, B. C.; Lee, M. B.; Parsons, D. K.; White, M. C. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States)

    2013-07-01

    The ENDF71x library [1] is the most thoroughly tested set of ACE-format data tables ever released by the Nuclear Data Team at Los Alamos National Laboratory (LANL). It is based on ENDF/B-VII. 1, the most recently released set of evaluated nuclear data files produced by the US Cross Section Evaluation Working Group (CSEWG). A variety of techniques were used to test and verify the ENDF7 1x library before its public release. These include the use of automated checking codes written by members of the Nuclear Data Team, visual inspections of key neutron data, MCNP6 calculations designed to test data for every included combination of isotope and temperature as comprehensively as possible, and direct comparisons between ENDF71x and previous ACE library releases. Visual inspection of some of the most important neutron data revealed energy balance problems and unphysical discontinuities in the cross sections for some nuclides. Doppler broadening of the total cross sections with increasing temperature was found to be qualitatively correct. Test calculations performed using MCNP prompted two modifications to the MCNP6 source code and also exposed bad secondary neutron yields for {sup 231,233}Pa that are present in both ENDF/B-VII.1 and ENDF/B-VII.0. A comparison of ENDF71x with its predecessor ACE library, ENDF70, showed that dramatic changes have been made in the neutron cross section data for a number of isotopes between ENDF/B-VII.0 and ENDF/B-VII.1. Based on the results of these verification tests and the validation tests performed by Kahler, et al. [2], the ENDF71x library is recommended for use in all Monte Carlo applications. (authors)

  4. Distribution of the decay heat in various modul HTRs and influence on peak fuel temperatures

    A unique feature of modular high-temperature reactors (MODUL-HTRs) is their benign response to a Loss-Of-Coolant Accident (LOCA). The reactor inherently becomes subcritical; the decay power partly heats up the reactor and partly is removed to the environment via thermal conduction and radiation, while avoiding overheating of the fuel. Production, storage, and removal of the decay heat is studied for different MODUL-HTR concepts having annular-core designs and thermal-powers of 350 MWt. Based on use of Low-Enriched-Uranium/Thorium (LEU/Th) fuel cycles in Prismatic-Fueled Reactors (PFRs), and LEU fuel cycles in Pebble-Bed-Reactors (PBRs), the following has been determined: (1) Comparison of a PFR and a PBR having essentially the same design shows higher decay heat production in the PFR due to a higher fission-product inventory and to the decay of 233Pa bred from 232Th; comparison also shows lower heat-transport rates from the pebble-bed core during a LOCA due to the lower thermal conductivity of the core. (2) Changing the PBR design to utilize carbon bricks and an additional coolant gap in the outer regions of the reactor adds significant barriers to the transport of decay heat to the Reactor Cavity Cooling System (RCCS) which is external to the reactor vessel. (3) In HTRs for Gas-Turbine (GT) applications, the operating temperature of the reactor is higher than in Steam turbine Cycle (SC) HTRs; consequently, under LOCAs the relative heat transport to the RCCS is higher in GT-HTRs. As a result, during a LOCA the amount of heat energy stored in the GT-HTR cores was only about 50% of the amount stored in SC-HTR cores. (author). 8 refs, 9 figs, 5 tabs

  5. The effect of sample stability on the determination of radioactivity for various radionuclides by liquid scintillation counting

    For measuring a sample stored for a long period of time using liquid scintillation counting (LSC), it is necessary to study the long-term stability of the sample. The effect of sample stability on the determination of radioactivity for 241Am, 90Sr/90Y, 137Cs, 147Pm, 237Np/233Pa, and 3H by LSC has been investigated. The variation of quench level over time can be an indication of sample stability. If the variation in a sample is little, the effect of sample stability on the determination of the above radionuclides can be neglected. Otherwise, the sample stability will have impact not only on the counting efficiency (especially for low energy β emitters), but also on the results of α/β discrimination. For studying the stability of a sample, special attention should be paid to the radionuclides with chemical form apt to be adsorbed, because the quench level of a sample cannot be reflected by the quench index SQP(E) alone when significant physical quench exists. Shaking a sample stored for a long period of time and checking the LSC spectra can give the information on physical quench in the sample. In the range of this study, OptiPhase Hisafe 3 has much better quench resistance than Ultima Gold AB. - Highlights: • The variation of quench level over time can be an indication of sample stability. • The sample stability has impact on α/β discrimination as well as on the counting efficiency. • Special attention should be paid to the radionuclides with chemical form apt to be adsorbed. • Shaking a sample and checking the LSC spectra can give the information on physical quench. • Significant physical quench usually leads to a new peak in the LSC spectrum of an α emitter

  6. Hyperfine interaction studies by nuclear orientation and NMR/on on-line to an electromagnetic isotope separator-experiences with the the system FOLBIS

    /sup 82/Br was implanted into iron at T < 0.2 K and at room temperature with different doses. Low-dose samples were prepared by use of a specially developed negative surface-ionization source. In all cases nuclear magnetic resonance of oriented /sup 82/Br was observed. For low-dose room-temperature implantation, the resonance signal consists of a main line with a width of only 0.59(6) MHz at center frequency ν/sub 1/ = 201.95(3) MHz for B/sub ext/ = 81.1 mT, and a satellite of smaller amplitude and similar width at ν/sub 2/ = 201.09(6) MHz. For low-dose implantation at T < 0.2 K, a line with normal width of 1.6(2) MHz at ν/sub 1/ = 202.07(6) MHz for B/sub ext/ = 80.7 mT, and a background line of width 6.6(1.2) MHz and center ν/sub 2/ = 199.4(6) MHz were observed. Nuclear orientation data interpreted in a two-fields model indicate that the fraction of nuclei in NMR field sites is larger after implantation at T < 0.2 K than after implantation at room temperature. From nuclear orientation data of /sup 233/Pa in zinc after implantation at T < 0.2 K, an effective electric interaction frequency ν/sub Q/ = + 99(20) MHz is derived. The frequency gets smaller through annealing at 290 K

  7. Testing of ENDF71x: A new ACE-formatted neutron data library based on ENDF/B-VII.1

    The ENDF71x library [1] is the most thoroughly tested set of ACE-format data tables ever released by the Nuclear Data Team at Los Alamos National Laboratory (LANL). It is based on ENDF/B-VII. 1, the most recently released set of evaluated nuclear data files produced by the US Cross Section Evaluation Working Group (CSEWG). A variety of techniques were used to test and verify the ENDF7 1x library before its public release. These include the use of automated checking codes written by members of the Nuclear Data Team, visual inspections of key neutron data, MCNP6 calculations designed to test data for every included combination of isotope and temperature as comprehensively as possible, and direct comparisons between ENDF71x and previous ACE library releases. Visual inspection of some of the most important neutron data revealed energy balance problems and unphysical discontinuities in the cross sections for some nuclides. Doppler broadening of the total cross sections with increasing temperature was found to be qualitatively correct. Test calculations performed using MCNP prompted two modifications to the MCNP6 source code and also exposed bad secondary neutron yields for 231,233Pa that are present in both ENDF/B-VII.1 and ENDF/B-VII.0. A comparison of ENDF71x with its predecessor ACE library, ENDF70, showed that dramatic changes have been made in the neutron cross section data for a number of isotopes between ENDF/B-VII.0 and ENDF/B-VII.1. Based on the results of these verification tests and the validation tests performed by Kahler, et al. [2], the ENDF71x library is recommended for use in all Monte Carlo applications. (authors)

  8. 232Th(d,4n)230Pa cross-section measurements at ARRONAX facility for the production of 230U

    Introduction: 226Th (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 213Bi. 226Th can be obtained via the 230U α decay. This study focuses on the 230U production using the 232Th(d,4n)230Pa(β−)230U reaction. Methods: Experimental cross sections for deuteron-induced reactions on 232Th 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. Results: Our new 230Pa cross-section values, as well as those of 232Pa and 233Pa 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 232Th. Conclusions: Using our cross-section data points from the 232Th(d,4n)230Pa reaction, we have calculated the thick-target yield of 230U, 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

  9. Thermodynamic and structural properties in complexing media

    Protactinium is experiencing a renewal of interest in the frame of long-term energy production. Modelling the behaviour of this element in the geosphere requires thermodynamic and structural data relevant to environmental conditions. Now deep clayey formation are considered for the disposal of radioactive waste and high values of natural sulphate contents have been determined in pore water in equilibrium with clay surface. Because of its tendency to polymerisation, hydrolysis and sorption on all solid supports, the equilibria constants relative to monomer species were determined at tracer scale (ca. 10 - 12 M) with 233Pa. The complexation constants of Pa(V) and sulphate ions were calculated starting from a systematic study of the apparent distribution coefficient D in the system TTA/Toluene/H2O/Na2SO4/HClO4/NaClO4 and as a function of ionic strength, temperature, free sulphate, protons and chelatant concentration. First of all, the interaction between free species H+, SO4-, Na+ leads to the formation of HSO4- and NaSO4-, for which concentrations depend upon the related thermodynamic constants. For this purpose a computer code was developed in order to determine all free species concentration. This iterative code takes into account the influence of temperature and ionic strength (SIT modelling) on thermodynamic constants. The direct measure of Pa(V) in the organic and aqueous phase by g-spectrometry had conducted to estimate the apparent distribution coefficient D as function of free sulphate ions. Complexation constants have been determined after a mathematical treatment of D. The extrapolation of these constants at zero ionic strength have been realized by SIT modelling at different temperatures. Besides, enthalpy and entropy values were calculated. Parallelly, the structural study of Pa(V) was performed using 231 Pa. XANES and EXAFS spectra show unambiguously the absence of the trans di-oxo bond that characterizes the other early actinide elements like U and Np

  10. A Pressurized Water Reactor Plutonium Incinerator Based on Thorium Fuel and Seed-Blanket Assembly Geometry

    A pressurized water reactor (PWR) fuel cycle is proposed, whose purpose is the elimination and degradation of weapons-grade plutonium. This Radkowsky thorium-fuel Pu incinerator (RTPI) cycle is based on a core and assemblies retrofittable to a Westinghouse-type PWR. The RTPI assembly, however, is a seed-blanket unit. The seed is supercritical, loaded with Pu-Zr alloy as fuel in a high moderator-to-fuel ratio configuration. The blanket is subcritical, loaded mainly with ThO2, generating and burning 233U in situ. Blankets are loaded once every 6 yr. The seed fuel management scheme is based on three batches, with one-third of the seed modules replaced every year. The core generates 1100 MW(electric). Equilibrium conditions are achieved with the second seed loading. For equilibrium conditions, the annual average of disposed (loaded) Pu is 1210 kg, of which 702 kg are completely eliminated, and 508 kg are discharged, but with significantly degraded isotopics (i.e., with a high percentage of even mass isotopes). Spontaneous fissions per second in a gram of this degraded Pu are ∼500, resulting in significantly increased proliferation resistance.Every 6 yr the blanket discharge contains 780 kg of 233U (including 233Pa) and 36 kg of 235U. However, the blankets are initially loaded with an amount of natural uranium selected such that these U fissile isotopes constitute only 12% of the total U discharge, a percentage equivalent to 20% 235U enrichment; hence, both the discharged uranium isotopics satisfy proliferation-resistant criteria.The RTPI control variables, namely, the moderator temperature coefficient, the reactivity per ppm boron, and the control rods worth, are about equal to those of a PWR. The RTPI spent-fuel stockpile ingestion toxicity over a period of ten million years is about the same as the counterpart toxicities of a regular, or a mixed-oxide (MOX), PWR. Compared with known PWR MOX variants, the RTPI is, per 1000 MW(electric) and per annum, a significantly

  11. Nuclear data for new fuel cycles and waste transmutation

    At the present rate of consumption, the known uranium resources on earth will be sufficient to continue its use as fuel for nuclear energy production for no longer then about 200 more years. Other fuels such as oil and gas probably face an even shorter life before exhaustion of known resources. At the same time the actual rate of radioactive waste production associated with this energy generation requires technical solutions that will permit the continuous support of economic growth and improved quality of life, together with a minimal impact to environment. Worldwide new research programmes for radioactive waste management have recently been undertaken. In France, at the French National Research Council (CNRS), various groups are presently working on the development of new technologies to reduce the present inventory of nuclear wastes and simultaneously on more efficient ways to use the thorium natural resources to generate nuclear energy while minimizing waste production during many centuries. At the Centre d'Etudes Nucleaires in Bordeaux we have undertaken a programme of cross-section measurements for neutron-induced reactions with energies ranging from a few meV to 6 MeV. We have in particular measured the (n, γ) and/or the (n,fission) cross-sections for three nuclei (232 Th, 233 Pa and 233 U) playing an important role for the Th-U cycle. This fuel offers a number of advantages (in particular a factor 100 less minor actinides produced) compared to the commonly used uranium fuel in light water pressurized reactors. Furthermore we have also remeasured the transmutation rate for the long-lived fission product 129 I which have a half live of 1.6x107 years. The various experiments have been performed at the 4 MV Van de Graaff accelerator in Bordeaux and at the Tandem accelerator of the Institut de Physique Nucleaire in Orsay. This work was partly supported by the CNRS programme PACE (Programme Aval du Cycle Electronucleaire) as well as by the Conseil Regional d

  12. Indian advanced heavy water reactor for thorium utilisation and nuclear data requirements and status

    BARC is embarking on thorium utilisation program in a concerted and consistent manner to achieve all round capabilities in the entire Thorium cycle under the Advanced Heavy Water Reactor (AHWR) development program. Upgrading our nuclear data capability for thorium cycle is one of the main tasks of this program. This paper gives a brief overview of the physics design features of the AHWR. The basic starting point of the analysis has been the lattice simulation of the fuel cluster employing the WIMS-D4 code package with 1986 version of 69 group library. For the analysis of thorium cycle, the present multi group version contains the three major isotopes viz., 232Th, 233U and 233Pa. To correctly evaluate the fuel cycle we require many more isotopes of the Th burnup chain. With the help of NDS, IAEA, many other isotopes of interest in AHWR, actinides in the thorium burnup chain, burnable absorbers, etc., were generated. Some of them were added to the WIMS-D4 library and the results are discussed. The WIMS-D4 library is also being updated as part of the IAEA coordinated research project on Final Stage of WLUP with international cooperation. India is also taking part in CRP. The evaluation of AHWR lattice with this new library is presented. Some comments regarding the fission product data being used in WIMS libraries are given, which are tuned to U-Pu cycles. The measurements for 233U are rather old. Measurements in high energies are also very sparse. More attention by nuclear data community is required in this regard as well. India has also begun a modest program to assess the ADS concepts, with the aim of employing thermal reactor systems, such as AHWR. A one way coupled booster reactor concept is being analysed with available code systems and nuclear data. A brief summary of this concept is also being discussed in this paper. A general survey on the quality of the evaluated nuclear data of the major and minor isotopes of thorium cycle is also given. A major

  13. Feasibility study of self sustaining capability on water cooled thorium reactors for different power reactors

    fertile and fissile nuclides with the contribution from intermediate nuclides such as 234U and 233Pa. The conversion ratio is evaluated by considering the conversion capability of the reactor to convert the fertile material into fissile material. The fissile accumulation capability for different conditions is investigated for estimating the fissile production capability during operation. The result shows the negative reactivity coefficient, and its feasibility of breeding for different MFR and burnup. The very tight lattice pin of MFR ≤ 0.3 is preferable for obtaining breeding condition for relatively higher burnup. The breeding capability of the reactor increases with increasing power output and decreasing power density. In relation to the self sustaining system, the large power output is easier to reach than the small power output

  14. Thermodynamic and structural properties in complexing media; Comportement chimique du protactinium (V) en presence d'ions sulfate

    Di Giandomenico, M.V

    2007-10-15

    Protactinium is experiencing a renewal of interest in the frame of long-term energy production. Modelling the behaviour of this element in the geosphere requires thermodynamic and structural data relevant to environmental conditions. Now deep clayey formation are considered for the disposal of radioactive waste and high values of natural sulphate contents have been determined in pore water in equilibrium with clay surface. Because of its tendency to polymerisation, hydrolysis and sorption on all solid supports, the equilibria constants relative to monomer species were determined at tracer scale (ca. 10 - 12 M) with {sup 233}Pa. The complexation constants of Pa(V) and sulphate ions were calculated starting from a systematic study of the apparent distribution coefficient D in the system TTA/Toluene/H{sub 2}O/Na{sub 2}SO{sub 4}/HClO{sub 4}/NaClO{sub 4} and as a function of ionic strength, temperature, free sulphate, protons and chelatant concentration. First of all, the interaction between free species H{sup +}, SO{sub 4}{sup -}, Na{sup +} leads to the formation of HSO{sub 4}{sup -} and NaSO{sub 4}{sup -}, for which concentrations depend upon the related thermodynamic constants. For this purpose a computer code was developed in order to determine all free species concentration. This iterative code takes into account the influence of temperature and ionic strength (SIT modelling) on thermodynamic constants. The direct measure of Pa(V) in the organic and aqueous phase by g-spectrometry had conducted to estimate the apparent distribution coefficient D as function of free sulphate ions. Complexation constants have been determined after a mathematical treatment of D. The extrapolation of these constants at zero ionic strength have been realized by SIT modelling at different temperatures. Besides, enthalpy and entropy values were calculated. Parallelly, the structural study of Pa(V) was performed using 231 Pa. XANES and EXAFS spectra show unambiguously the absence of the

  15. Impact on breeding rate of different Molten Salt reactor core structures

    Background: Molten Salt Reactor (MSR) has several advantages over the other Generation IV reactor. Referred to the French CNRS research and compared to the fast reactor, super epithermal neutron spectrum reactor type is slightly lower and beading rate reaches 1.002. Purpose: The aim is to explore the best conversion zone layout scheme in the super epithermal neutron spectrum reactor. This study can make nuclear fuel as one way to solve the energy problems of mankind in future. Methods: Firstly, SCALE program is used for molten salt reactor graphite channel, molten salt core structure, control rods, graphite reflector and layer cladding structure. And the SMART modules are used to record the important actinides isotopes and their related reaction values of each reaction channel. Secondly, the thorium-uranium conversion rate is calculated. Finally, the better molten salt reactor core optimum layout scheme is studied comparing with various beading rates. Results: Breading zone layout scheme has an important influence on the breading rate of MSR. Central graphite channels in the core can get higher neutron flux irradiation. And more 233Th can convert to 233Pa, which then undergoes beta decay to become 233U. The graphite in the breading zone gets much lower neutron flux irradiation, so the life span of this graphite can be much longer than that of others. Because neutron flux irradiation in the uranium molten salt graphite has nearly 10 times higher than the graphite in the breading zone, it has great impact on the thorium-uranium conversion rates. For the super epithermal neutron spectrum molten salt reactors, double salt design cannot get higher thorium-uranium conversion rates. The single molten salt can get the same thorium-uranium conversion rate, meanwhile it can greatly extend the life of graphite in the core. Conclusions: From the analysis of calculation results, Blanket breeding area in different locations in the core can change the breeding rates of thorium

  16. Estimation of neptunium in uranium product

    Neptunium- 237 is a long-lived (t1/2 = 2.14 x 106 years) alpha emitter, present in low concentration levels in process solutions. The oxidation state and the nature of species present in process solutions depend upon the concentration of nitrous acid, nitric acid, other redox elements, and ageing. Owing to the complicated redox behavior, 237Np is usually distributed in all streams such as highly active raffinate, plutonium product, and uranium product etc. Estimation of neptunium in various PUREX process streams is necessary for understanding the path and routing of neptunium during reprocessing of fast reactor fuels. Various methods such as neutron activation analysis (NAA), spectrophotometry and electroanalytical techniques have - been reported for quantitative estimation of neptunium in the process streams. The sample of uranium product was received from Reprocessing Group, IGCAR to estimate the concentration of neptunium in uranium product. About 1 gram of the sample was dissolved in 8 M HNO3 and evaporated to dryness. Then, the product was redissolved in 1 M HNO3, and centrifuged. The supernatant solution (1 mL) was analyzed by gamma spectrometry, alpha spectrometry and neutron activation analysis. The gamma emission of 233Pa, which was in secular equilibrium with the parent 237Np was determined for estimating of neptunium by gamma spectrometry. Analysis of the sample by alpha spectrometry showed the presence of plutonium and americium in the uranium product. These alpha emitters hindered the analysis of neptunium. Hence, Np(IV) was separated from other actinides by extraction into 1 mL of 0.5 M TTA/xylene and stripped with 10 M HNO3. An aliquot (0.1 mL) of organic phase was dried in an aluminum foil and irradiated at KAMINI reactor at the neutron flux of 1010 neutrons/cm/sec for 4 hours. The activation product, 238Np, formed was monitored by the characteristic gamma emissions at 984 keY and 1028 keY. The stripped solution was subjected to alpha spectrometry

  17. Measurement of the generation ratio of 233U and the average radiation capture cross section of 232Th with 232ThO2 irradiated by fast neutrons

    Background: Thorium-Uranium cycle plays an important role in the future's power production technology. Nuclear data involved are urgently needed for engineering design and other purposes since there are obvious differences between the existing evaluated data. Macroscopic neutron integral experiment can be used as a good tool to survey the confusion. Purpose: Macroscopic neutron integral experiment based on radioactive method was carried out to measure the generation ratio of 233U nuclide and the average radiation capture cross section of 232Th while a ThO2 sample was irradiated by fast neutrons leakage from a fast critical facility. We expect that these data can be used as a reference for the research of Th-U cycle. Methods: Radiation capture reactions of 232Th nuclides occur when the nuclides are irradiated by neutrons. 233U nuclides will be generated after two cascade decays by emitting beta rays from the activation products, which are 233Th nuclides. The ThO2 sample was prepared as a slice of 20 mm×10 mm from 0.743 36-g ThO2 powders of 99.9% enriched. The neutron flux was measured by activation method which was 4.07x109 cm-2·s-1 at the sample's irradiation position while the facility worked at the power level of 180 watts. The leakage neutrons' energy distribution was calculated by MC method and it is very close to the fission spectrum with the averaged energy of 1.42 MeV. After irradiation and then a period of cooling time the gamma rays emitted from the sample were measured by an HPGe spectrometer which had been pre-calibrated. From these data the activity of 233Pa was calculated and then the generation ratio of 233U and the average radiation capture cross section of 232Th were calculated. The measured average radiation capture cross section was compared with the cross sections calculated based on the ENDFB-VH.1, CENDL-3.1, JENDL-4.0, BROND2.2 databases. Results: The measured generation ratio of 233U was 4.01×10-12 with an uncertainty of 6

  18. Trace contamination in pure high-tech materials

    analysis (INAA) and RNAA proved to be the methods of choice for this delicate analytical challenge. Using optimized irradiation, decay and counting conditions, and owing to the fact that Si and N produce only short lived radioisotopes, up to 55 elements in several high purity Si3N4 materials could be determined quantitatively by INAA. NAA has proved to be a very suitable method for the determination of ultra-traces of Th and U via their daughter nuclides 233Pa and 239Np. Aluminium oxide and aluminium nitride, the most important raw materials for advanced ceramics used in microelectronics and bioceramic endoprotheses, must be of the highest possible purity to ensure their mechanical and insulating properties. Oxides of Cr, Fe, Mg, Na and Ti affect the electrical resistivity of ultra-pure Al2O3, whereas the oxides of Ca, Fe, Mg, Na, Si and Zr reduce the thermal stability and shock resistance. Because of the refractory character of the two materials, direct determination methods using solid samples are of great interest for their analysis. A combination of INAA and RNAA was developed for the characterization of 56 elements in raw and high purity aluminium oxide and nitride powders

  19. ZZ SINEX, 100 Neutron-Group Neutron Reaction Cross-Section Library from ENDF/B by SUPERTOG for ANISN

    , Cl, K, Ca, V, Cr, 55-Mn, Fe, 59-Co, Ni, Cu, 63-Cu, 65-Cu, Nb, Mo, 107-Ag, 109-Ag, 135-Xe, 133-Cs, 149-Sm, 151-Eu, 153-Eu, Gd, 164-Dy, 175-Lu, 176-Lu, 181-Ta, 182-Ta, 182-W, 183-W, 184-W, 186-W, 185-Re, 187-Re, 197-Au, Pb, 232-Th, 233-Pa, 234-U, 235-U, 238-U, 238-Pu, 239-Pu, 240-Pu, 241-Pu, 242-Pu, 241-Am, 243-Am, and 244-Cm. 2 - Method of solution: DLC-24 was generated by SUPERTOG from nuclear data in either point-by-point or parametric representation as specified by ENDF/B. This data is averaged over each specified group width. For the top 99 groups, the explicit assumption was made that the flux (weighting function) has the shape of a fission spectrum jointed at 0.0674 MeV by a 1/E tail. When resonance data were available, resolved and unresolved resonance contributions were calculated, using the infinite dilution approximation. For the thermal group (group 100), values for all materials except hydrogen were taken from the Maxwellian average values derived from the ENDF/B data. The values for hydrogen are more consistent for hydrogen in water. It should be noted that these thermal group values are in some cases different from values used in the latest version of DLC-2

  20. ZZ DLC-2D/100G, 100 Neutron-Group Cross-Section Library by SUPERTOG Calculation for ANISN, DOT

    1 - Nature of physical problem solved: Format: ANISN, DOT or DTF-4; Number of groups: 100; Nuclides: H, D, He, He-3, Li-6, Li-7, Be-9, B-10, B-11, C-12, N-14, O-16, Na-23, Mg, Al-27, Si, Cl, K, Ca, V, Cr, Mn-55, Fe, Co-59, Ni, Cu, Cu-63, Cu-65, Nb, Mo, Ag-107, Xe-135, Cs-133, Sm-149, Eu-151, Eu-153, Gd, Dy-164, Lu-175, Lu-176, Ta-181, Ta-182, W-182, W-183, W-184, W-186, Re-185, Re-187, Au-197, Pb, Th-232, Pa-233, U-234, U-235, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-243, and Cm-244. Origin: The nuclides in DLC-2 are those which have been released as category I ENDF/B by the National Neutron Cross Section Center, Brookhaven National Laboratory. Weighting spectrum: The explicit assumption was made that the flux has the shape of a fission spectrum joined at 0.0674 MeV by a 1/E tail. Neutron transport calculations can be performed with DLC-2 data. Since the data are intended for use in multigroup discrete-ordinates or Monte Carlo transport codes which treat anisotropic scattering, possible cross section angular expansion is limited only by the options available in the particular code used. Specifically, the retrieval program manipulates DLC-2 such that it conforms to input requirements of the ANISN, DOT, or DTF-4 codes, or any computer code using data in the ANISN or DTF-4 format. The nuclides in DLC-2 are those which have been released as category I ENDF/B by the National Neutron Cross Section Center, Brookhaven National Laboratory. The library contains data for H, D, He, 3-He, 6-Li, 7-Li, 9-Be, 10-B, 11-B, 12-C, 14-N, 16-O, 23-Na, Mg, 27-Al, Si, Cl, K, Ca, V, Cr, 55-Mn, Fe, 59-Co, Ni, Cu, 63-Cu, 65-Cu, Nb, Mo, 107-Ag, 135-Xe, 133-Cs, 149-Sm, 151-Eu, 153-Eu, Gd, 164-Dy, 175-Lu, 176-Lu, 181-Ta, 182-Ta, 182-W, 183-W, 184-W, 186-W, 185-Re, 187-Re, 197-Au, Pb, 232-Th, 233-Pa, 234-U, 235-U, 238-U, 238-Pu, 239-Pu, 240-Pu, 241-Pu, 242-Pu, 241-Am, 243-Am, and 244-Cm. 2 - Method of solution: DLC-2 was generated by SUPERTOG from nuclear data in either point