Application research of improved 235U enrichment meter

International Nuclear Information System (INIS)

Liu Daming; Wu Xin; Lu Zhao; Tang Peijia; Lu Feng; Wang Yunmei

1998-01-01

A prototype 235 U enrichment meter based on NaI(Tl) γ spectroscopy is improved and it works under the principle of that the enrichment of 235 U is proportional to the radioactivity of 185 keV γ-ray when the sample is thick infinitely. The data of radioactivity from 235 U can be collected by a notebook computer and the interface control software is written using C++ language. The meter was tested and calibrated using standard fuel rods in fuel fabrication plant. For single fuel rod, the measured value of 235 U enrichment is agreeable with declared value within-1.0%-2.8%

Decay scheme of the U{sup 2}35; Esquema de desintegracion del U-235

Energy Technology Data Exchange (ETDEWEB)

Gaeta, R

1965-07-01

A study of the Th{sup 2}31 excited levels from the alpha decay of the U{sup 2}35, is carried out. The alpha particle spectrum was measured by means of a semiconductor counter spectrometer with an effective resolution of 18 keV. Nineteen new lines were identified. The gamma-ray spectrum was measured with thin samples of U{sup 2}35, free from decay products, and in such geometrical conditions, that most of the interference effects were eliminated. The gamma-gamma coincidence spectra have made easier a better knowledge of the transition between the several levels. (Author) 110 refs.

Monte Carlo simulation for fragment mass and kinetic energy distributions from the neutron-induced fission of 235U

International Nuclear Information System (INIS)

Montoya, M.; Rojas, J.; Saettone, E.

2007-01-01

The mass and kinetic energy distribution of nuclear fragments from the thermal neutron-induced fission of 235 U have been studied using a Monte Carlo simulation. Besides reproducing the pronounced broadening on the standard deviation of the final fragment kinetic energy distribution (σ e (m)) around the mass number m = 109, our simulation also produces a second broadening around m = 125 that is in agreement with the experimental data obtained by Belhafaf et al. These results are a consequence of the characteristics of the neutron emission, the variation in the primary fragment mean kinetic energy, and the yield as a function of the mass. (Author)

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

International Nuclear Information System (INIS)

Russ III, G.P.

1997-01-01

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

Uranium contents and {sup 235}U/{sup 238}U atom ratios in soil and earthworms in western Kosovo after the 1999 war

Energy Technology Data Exchange (ETDEWEB)

Di Lella, L.A.; Nannoni, F.; Protano, G.; Riccobono, F. [Dipartimento di Scienze Ambientali ' G. Sarfatti' -Sezione di Geochimica Ambientale, University of Siena, Via del Laterino 8, I-53100, Siena (Italy)

2005-01-20

The uranium content and {sup 235}U/{sup 238}U atom ratio were determined in soils and earthworms of an area of Kosovo (Djakovica garrison), heavily shelled with depleted uranium (DU) ammunition during the 1999 war. The aim of the study was to reconstruct the small-scale distribution of uranium and assess the influence of the DU added to the surface environment. The total uranium concentration and the {sup 235}U/{sup 238}U ratio of topsoils showed great variability and were inversely correlated. The highest uranium levels (up to 31.47 mg kg{sup -1}) and lowest {sup 235}U/{sup 238}U ratios (minimum 0.002147) were measured in topsoils collected inside, or very close to, the clusters of DU penetrator holes. Regarding the fractionation of uranium in the surface soils, the uranium concentrations in the soluble and exchangeable fractions increased as the total uranium concentration of the topsoils increased. High and rather uniform percentage contents of uranium (24-36%) were associated with the poorly crystalline iron oxide phases of soils. In the U-enriched soils the elevated levels of the element were probably due to the presence of very small, unevenly distributed oxidized DU particles. The total uranium concentration in earthworms was in the range 0.142-0.656 mg kg{sup -1}, with the highest concentrations in Lumbricus terrestris. The juveniles of all three studied species seemed to accumulate uranium more than adults, probably due to age-related differences in metabolism. The {sup 235}U/{sup 238}U ratio in the earthworms was variable (0.005241-0.007266) and independent of both the total uranium contents in soils and the absolute uranium levels in the animals. Bioconcentration was greater at lower U concentrations in soil, probably due to an increasing rate of elimination of uranium by the earthworms as the soil contents of the element increase. The results of this study clearly indicate that DU was added to the soil of the study area. Nevertheless, the phenomenon was

Monte Carlo simulation for fragment mass and kinetic energy distributions from the neutron-induced fission of {sup 235}U

Energy Technology Data Exchange (ETDEWEB)

Montoya, M.; Rojas, J. [Instituto Peruano de Energia Nuclear, Av. Canada 1470, Lima 41 (Peru); Saettone, E. [Facultad de Ciencias, Universidad Nacional de lngenieria, Av. Tupac Amaru 210, Apartado 31-139, Lima (Peru)

2007-07-01

The mass and kinetic energy distribution of nuclear fragments from the thermal neutron-induced fission of {sup 235}U have been studied using a Monte Carlo simulation. Besides reproducing the pronounced broadening on the standard deviation of the final fragment kinetic energy distribution ({sigma}{sub e}(m)) around the mass number m = 109, our simulation also produces a second broadening around m = 125 that is in agreement with the experimental data obtained by Belhafaf et al. These results are a consequence of the characteristics of the neutron emission, the variation in the primary fragment mean kinetic energy, and the yield as a function of the mass. (Author)

Multipole components of 235U photofission

International Nuclear Information System (INIS)

Carvalheiro, Z.

1985-01-01

The absolute electrofission cross section for 235 U has been experimentally obtained in the energy range 5.8 - 18.0 MeV, using the electron beam of the Linear Accelerator of Institute of Physics of the University of Sao Paulo. From a combined analysis of this cross section and a previously measured photofission cross section, using virtual photon spectra calculated in the Distorted Wave Born Approximation (DWBA), the '' non electric dipole photofission'' cross section σ NDE γ,f (ω) has been obtained, which contains all multipolarities allowed by the reaction Kinematics, except El. This cross section presents a resonant shape, probably associated with the Giant Quadrupole Resonance (GQR). Once the fission channel exhausts a great amount of the Energy Weighted Sum Rule (EWSR), it is therefore the major decay mode of the GQR. All these aspects agree with the ones verified for the other Uranium isotopes previously analysed in this Laboratory. (author) [pt

The 235U Prompt Fission Neutron Spectrum in the BR1 Reactor at SCK•CEN

Science.gov (United States)

Wagemans, Jan; Malambu, Edouard; Borms, Luc; Fiorito, Luca

2016-02-01

The BR1 research reactor at SCK•CEN has a spherical cavity in the graphite above the reactor core. In this cavity an accurately characterised Maxwellian thermal neutron field is present. Different converters can be loaded in the cavity in order to obtain other types of neutron (and gamma) irradiation fields. Inside the so-called MARK III converter a fast 235U(n,f) prompt fission neutron field can be obtained. With the support of MCNP calculations, irradiations in MARK III can be directly related to the pure 235U(n,f) prompt fission neutron spectrum. For this purpose MARK III spectrum averaged cross sections for the most relevant fluence dosimetry reactions have been determined. A calibration factor for absolute measurements has been determined applying activation dosimetry following ISO/IEC 17025 standards.

The 235U Prompt Fission Neutron Spectrum in the BR1 Reactor at SCK•CEN

Directory of Open Access Journals (Sweden)

Wagemans Jan

2016-01-01

Full Text Available The BR1 research reactor at SCK•CEN has a spherical cavity in the graphite above the reactor core. In this cavity an accurately characterised Maxwellian thermal neutron field is present. Different converters can be loaded in the cavity in order to obtain other types of neutron (and gamma irradiation fields. Inside the so-called MARK III converter a fast 235U(n,f prompt fission neutron field can be obtained. With the support of MCNP calculations, irradiations in MARK III can be directly related to the pure 235U(n,f prompt fission neutron spectrum. For this purpose MARK III spectrum averaged cross sections for the most relevant fluence dosimetry reactions have been determined. A calibration factor for absolute measurements has been determined applying activation dosimetry following ISO/IEC 17025 standards.

Adjustment of the 235U Fission Spectrum

International Nuclear Information System (INIS)

GRIFFIN, PATRICK J.; WILLIAMS, J.G.

1999-01-01

The latest nuclear data are used to examine the sensitivity of the least squares adjustment of the 235 U fission spectrum to the measured reaction rates, dosimetry cross sections, and prior spectrum covariance matrix. All of these parameters were found to be very important in the spectrum adjustment. The most significant deficiency in the nuclear data is the absence of a good prior covariance matrix. Covariance matrices generated from analytic models of the fission spectra have been used in the past. This analysis reveals some unusual features in the covariance matrix produced with this approach. Specific needs are identified for improved nuclear data to better determine the 235 U spectrum. An improved 235 U covariance matrix and adjusted spectrum are recommended for use in radiation transport sensitivity analyses

235U NMR study of the itinerant antiferromagnet USb2

International Nuclear Information System (INIS)

Kato, Harukazu; Sakai, Hironori; Ikushima, Kenji; Kambe, Shinsaku; Tokunaga, Yo; Aoki, Dai; Haga, Yoshinori; O-bar nuki, Yoshichika; Yasuoka, Hiroshi; Walstedt, Russell E.

2005-01-01

We have succeeded in resolving a 235 U antiferromagnetic nuclear magnetic resonance (AFNMR) signal using 235 U-enriched samples of USb 2 . The uranium hyperfine field and coupling constant estimated for this compound are consistent with those from other experiments. This is the first reported observation of 235 U NMR in conducting host material

Fission Product Yields for 14 MeV Neutrons on 235U, 238U and 239Pu

International Nuclear Information System (INIS)

Mac Innes, M.; Chadwick, M.B.; Kawano, T.

2011-01-01

We report cumulative fission product yields (FPY) measured at Los Alamos for 14 MeV neutrons on 235 U, 238 U and 239 Pu. The results are from historical measurements made in the 1950s–1970s, not previously available in the peer reviewed literature, although an early version of the data was reported in the Ford and Norris review. The results are compared with other measurements and with the ENDF/B-VI England and Rider evaluation. Compared to the Laurec (CEA) data and to ENDF/B-VI evaluation, good agreement is seen for 235 U and 238 U, but our FPYs are generally higher for 239 Pu. The reason for the higher plutonium FPYs compared to earlier Los Alamos assessments reported by Ford and Norris is that we update the measured values to use modern nuclear data, and in particular the 14 MeV 239 Pu fission cross section is now known to be 15–20% lower than the value assumed in the 1950s, and therefore our assessed number of fissions in the plutonium sample is correspondingly lower. Our results are in excellent agreement with absolute FPY measurements by Nethaway (1971), although Nethaway later renormalized his data down by 9% having hypothesized that he had a normalization error. The new ENDF/B-VII.1 14 MeV FPY evaluation is in good agreement with our data.

Should we ignore U-235 series contribution to dose?

International Nuclear Information System (INIS)

Beaugelin-Seiller, Karine; Goulet, Richard; Mihok, Steve; Beresford, Nicholas A.

2016-01-01

Environmental Risk Assessment (ERA) methodology for radioactive substances is an important regulatory tool for assessing the safety of licensed nuclear facilities for wildlife, and the environment as a whole. ERAs are therefore expected to be both fit for purpose and conservative. When uranium isotopes are assessed, there are many radioactive decay products which could be considered. However, risk assessors usually assume 235 U and its daughters contribute negligibly to radiological dose. The validity of this assumption has not been tested: what might the 235 U family contribution be and how does the estimate depend on the assumptions applied? In this paper we address this question by considering aquatic wildlife in Canadian lakes exposed to historic uranium mining practices. A full theoretical approach was used, in parallel to a more realistic assessment based on measurements of several elements of the U decay chains. The 235 U family contribution varied between about 4% and 75% of the total dose rate depending on the assumptions of the equilibrium state of the decay chains. Hence, ignoring the 235 U series will not result in conservative dose assessments for wildlife. These arguments provide a strong case for more in situ measurements of the important members of the 235 U chain and for its consideration in dose assessments. - Highlights: • Realistic ecological risk assessment infers a complete inventory of radionuclides. • U-235 family may not be minor when assessing total dose rates experienced by biota. • There is a need to investigate the real state of equilibrium decay of U chains. • There is a need to improve the capacity to measure all elements of the U decay chains.

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

International Nuclear Information System (INIS)

McCulloch, M.T.

1999-01-01

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

ABSOLUTE NEUTRINO MASSES

DEFF Research Database (Denmark)

Schechter, J.; Shahid, M. N.

2012-01-01

We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos.......We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos....

Transition Probabilities in the 1/2+(631) Band in {sup 235}U

Energy Technology Data Exchange (ETDEWEB)

Hoejeberg, M; Malmskog, S G

1969-09-15

Measurements of absolute transition probabilities in the rotational band built on the 1/2{sup +}(631) single particle state in {sup 235}U have been performed using delayed coincidence technique. The following half-lives were obtained: T{sub 1/2} (13.0 keV level) = (0.50 {+-} 0.03) nsec. T{sub 1/2} (51.7 k e V level) = (0.20 {+-} 0.02) nsec. From the deduced B(E2) and B(M1) values magnetic and electric parameters were determined which could be compared with predictions from the Nilsson model.

Analysis of 235U enrichment by chemical exchange in U(IV) - U(VI) system on anionite

International Nuclear Information System (INIS)

Raica, Paula; Axente, Damian

2007-01-01

Full text: A theoretical study about the 235 U enrichment by chemical exchange method in U(IV)-U(VI) system on anion-exchange resins is presented. The 235 U isotope concentration profiles along the band were numerically calculated using an accurate mathematical model and simulations were carried out for the situation of product and waste withdrawal and feed supply. By means of numerical simulation, an estimation of the migration time, necessary for a desired enrichment degree, was obtained. The required migration distance, the production of uranium 3 at.% 235 U per year and the plant configuration are calculated for different operating conditions. An analysis of the process scale for various experimental conditions is also presented. (authors)

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

Energy Technology Data Exchange (ETDEWEB)

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

2000-02-01

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

Resonance structure in the fission of ( sup 235 U+n)

Energy Technology Data Exchange (ETDEWEB)

Moore, M.S. (Los Alamos National Lab. (LANL), NM (USA). Physics Div.); Leal, L.C.; De Saussure, G.; Perez, R.B.; Larson, N.M. (Oak Ridge National Lab., TN (USA))

1989-10-09

A new multilevel reduced R-matrix analysis of the neutron-induced resonance cross sections of {sup 235}U has been carried out. We used as a constraint in the analysis the angular anisotropy measurements of Pattenden and Postma, obtaining a Bohr-channel (or J, K channel) representation of the resonances in a two-fission vector space for each spin state. Hambsch et al., have reported definitive measurements of the mass- and kinetic-energy distributions of fission fragments of ({sup 235}U+n) in the resonance region and analyzed their results according to the fission-channel representation of Brosa et al., extracting relative contributions of the two asymmetric and one symmetric Brosa fission channels. We have explored the connection between Bohr-channel and asymmetric Brosa-channel representations. The results suggest that a simple rotation of coordinates in channel space may be the only transformation required; the multilevel fit to the total and partial cross sections is invariant to such a transformation. (orig.).

Effects of Neutron Emission on Fragment Mass and Kinetic Energy Distribution from Thermal Neutron-Induced Fission of 235U

International Nuclear Information System (INIS)

Montoya, M.; Rojas, J.; Saetone, E.

2007-01-01

The mass and kinetic energy distribution of nuclear fragments from thermal neutron-induced fission of 235 U(n th ,f) have been studied using a Monte-Carlo simulation. Besides reproducing the pronounced broadening in the standard deviation of the kinetic energy at the final fragment mass number around m = 109, our simulation also produces a second broadening around m = 125. These results are in good agreement with the experimental data obtained by Belhafaf et al. and other results on yield of mass. We conclude that the obtained results are a consequence of the characteristics of the neutron emission, the sharp variation in the primary fragment kinetic energy and mass yield curves. We show that because neutron emission is hazardous to make any conclusion on primary quantities distribution of fragments from experimental results on final quantities distributions

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

Science.gov (United States)

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

2018-02-01

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

Prompt Gamma Radiation from Fragments in the Thermal Fission of 235U

International Nuclear Information System (INIS)

Albinsson, H.; Lindow, L.

1970-06-01

Measurements were made on the gamma radiation emitted from fission fragments in slow neutron induced fission of 235 U. The fragments were detected with solid state detectors of the surface barrier type and the gamma radiation with a Nal(Tl) scintillator. Mass selection was used so that the gamma radiation could be measured as a function of fragment mass. Time discrimination between the fission gammas and the prompt neutrons released in the fission process was employed to reduce the background. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fission fragments. In this way a decay curve was obtained from which the life-time of one of the gamma-emitting states could be estimated. The relative yield of the gamma-rays was determined as a function of mass for different gamma-ray energy portions and two specific time intervals after the fission events. Comparisons were made with data obtained from 252 Cf-fission. Attention is drawn to some features which seem to be the same in 235 U and 252 Cf-fission

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

International Nuclear Information System (INIS)

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

2014-01-01

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

A new method to measure the U-235 content in fresh LWR fuel assemblies via fast-neutron passive self-interrogation

Science.gov (United States)

Menlove, Howard; Belian, Anthony; Geist, William; Rael, Carlos

2018-01-01

The purpose of this paper is to provide a solution to a decades old safeguards problem in the verification of the fissile concentration in fresh light water reactor (LWR) fuel assemblies. The problem is that the burnable poison (e.g. Gd2O3) addition to the fuel rods decreases the active neutron assay for the fuel assemblies. This paper presents a new innovative method for the verification of the 235U linear mass density in fresh LEU fuel assemblies that is insensitive to the burnable poison content. The technique makes use of the 238U atoms in the fuel rods to self-interrogate the 235U mass. The innovation for the new approach is that the 238U spontaneous fission (SF) neutrons from the rods induces fission reactions (IF) in the 235U that are time correlated with the SF source neutrons. Thus, the coincidence gate counting rate benefits from both the nu-bar of the 238U SF (2.07) and the 235U IF (2.44) for a fraction of the IF reactions. Whereas, the 238U SF background has no time-correlation boost. The higher the detection efficiency, the higher the correlated boost because background neutron counts from the SF are being converted to signal doubles. This time-correlation in the IF signal increases signal/background ratio that provides a good precision for the net signal from the 235U mass. The hard neutron energy spectrum makes the technique insensitive to the burnable poison loading where a Cd or Gd liner on the detector walls is used to prevent thermal-neutron reflection back into the fuel assembly from the detector. We have named the system the fast-neutron passive collar (FNPC).

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

Energy Technology Data Exchange (ETDEWEB)

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

1999-11-01

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

Laboratory studies of 235U enrichment by chemical separation methods

International Nuclear Information System (INIS)

Daloisi, P.J.; Orlett, M.J.; Tracy, J.W.; Saraceno, A.J.

1976-01-01

Laboratory experiments on 235 U enrichment processes based on column redox ion exchange, electrodialysis, and gas exchange chromatography performed from August 1972 to September 1974 are summarized. Effluent from a 50 to 50 weight mixture of U +4 and U +6 (as UO 2 2+ ), at a total uranium concentration of 5 mg U per ml in 0.25N H 2 SO 4 -0.03N NaF solution, passing through a 100 cm length cation exchange column at 0.5 ml/min flow rates, was enriched in 235 U by 1.00090 +- .00012. The enriched fraction was mostly in the +6 valence form while the depleted fraction was U +4 retained on the resin. At flow rates of 2 ml/min, the enrichment factor decreases to 1.00033 +- .00003. In the electrodialysis experiments, the fraction of uranium diffusing through the membranes (mostly as +6 valence state) in 4.2 hours is enriched in 235 U by 1.00096 +- .00012. Gas exchange chromatography tests involved dynamic and static exposure of UF 6 over NaF. In dynamic tests, no significant change in isotopic abundance occurred in the initial one-half weight cut of UF 6 . The measured relative 235 U/ 238 U mole ratios were 1.00004 +- .00004 for these runs. In static runs, enrichment became evident. For the NaF(UF 6 )/sub x/-UF 6 system, there is 235 U depletion in the gas phase, with a single-stage factor of 1.00033 at 100 0 C and 1.00025 at 25 0 C after 10 days of equilibration. The single-stage or unit holdup time is impractically long for all three chemical processes

Dispersion of the Neutron Emission in U{sup 235} Fission

Science.gov (United States)

Feynman, R. P.; de Hoffmann, F.; Serber, R.

1955-01-01

Equations are developed which allow the calculation of the average number of neutrons per U{sup235} fission from experimental measurements. Experimental methods are described, the results of which give a value of (7.8 + 0.6){sup ½} neutrons per U{sup 235} thermal fission.

Prompt Gamma Radiation from Fragments in the Thermal Fission of {sup 235}U

Energy Technology Data Exchange (ETDEWEB)

Albinsson, H [Chalmers Univ. of Technology, Goteborg (Sweden); Lindow, L [AB Atomenergi, Nykoeping (Sweden)

1970-06-15

Measurements were made on the gamma radiation emitted from fission fragments in slow neutron induced fission of {sup 235}U. The fragments were detected with solid state detectors of the surface barrier type and the gamma radiation with a Nal(Tl) scintillator. Mass selection was used so that the gamma radiation could be measured as a function of fragment mass. Time discrimination between the fission gammas and the prompt neutrons released in the fission process was employed to reduce the background. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fission fragments. In this way a decay curve was obtained from which the life-time of one of the gamma-emitting states could be estimated. The relative yield of the gamma-rays was determined as a function of mass for different gamma-ray energy portions and two specific time intervals after the fission events. Comparisons were made with data obtained from {sup 252} Cf-fission. Attention is drawn to some features which seem to be the same in {sup 235}U and {sup 252} Cf-fission.

Determination of the axial 235U distribution in target fuel rods

International Nuclear Information System (INIS)

Huettig, G.; Bernhard, G.; Niese, U.

1989-01-01

The homogenity of the axial 235 U distribution in target fuel rods is an important quality criterion for the production of 99 Mo. The 235 U distribution has been analyzed automatically and nondestructively by measuring the 235 U gamma ray peak at 285.7 keV. For the quantitative assessment a calibration curve was prepared by the help of X-ray fluorescence analysis, colorimetry, and photometric titration. The accuracy of the method is ≤ 1.5% uranium per centimeter of the fuel rod

Neutron-fragment angular correlations in /sup 235/U(n/sub th/,f)

International Nuclear Information System (INIS)

Franklyn, C.B.

1985-01-01

Neutron-fragment angular correlations in /sup 235/U(n/sub th/,f) as a function of neutron energy and fragment mass are presented. The results obtained in this experiment, together with data for neutron-neutron angular correlations, are compared with a Monte Carlo simulation of the fission process incorporating both a scission neutron component and an anisotropic neutron emission component

Critical mass analysis for 235U and 239Pu systems moderated and reflected by D2O

International Nuclear Information System (INIS)

Loaiza, D.; Stratton, W.

1998-01-01

Criticality dimensions for highly enriched 235 U (93.5) and 239 Pu (95.5) systems mixed with D 2 O were studied. The objective of this work is to investigate the minimum critical mass and concentration of uranium and plutonium systems in a reflector-moderated arrangement. The present work demonstrates the critical instability of some of these systems that are reflected by D 2 O and expands from previously published and unpublished work. These calculations were performed in a spherical geometry with the DANTSYS codes using the Hansen-Roach cross-section library. Densities examined ranged from normal to very small and are assumed to be uniform throughout the core. These spherical systems are reflected by 100 cm of D 2 O

Distinct 238U/235U ratios and REE patterns in plutonic and volcanic angrites: Geochronologic implications and evidence for U isotope fractionation during magmatic processes

Science.gov (United States)

Tissot, François L. H.; Dauphas, Nicolas; Grove, Timothy L.

2017-09-01

Angrites are differentiated meteorites that formed between 4 and 11 Myr after Solar System formation, when several short-lived nuclides (e.g., 26Al-26Mg, 53Mn-53Cr, 182Hf-182W) were still alive. As such, angrites are prime anchors to tie the relative chronology inferred from these short-lived radionuclides to the absolute Pb-Pb clock. The discovery of variable U isotopic composition (at the sub-permil level) calls for a revision of Pb-Pb ages calculated using an ;assumed; constant 238U/235U ratio (i.e., Pb-Pb ages published before 2009-2010). In this paper, we report high-precision U isotope measurement for six angrite samples (NWA 4590, NWA 4801, NWA 6291, Angra dos Reis, D'Orbigny, and Sahara 99555) using multi-collector inductively coupled plasma mass-spectrometry and the IRMM-3636 U double-spike. The age corrections range from -0.17 to -1.20 Myr depending on the samples. After correction, concordance between the revised Pb-Pb and Hf-W and Mn-Cr ages of plutonic and quenched angrites is good, and the initial (53Mn/55Mn)0 ratio in the Early Solar System (ESS) is recalculated as being (7 ± 1) × 10-6 at the formation of the Solar System (the error bar incorporates uncertainty in the absolute age of Calcium, Aluminum-rich inclusions - CAIs). An uncertainty remains as to whether the Al-Mg and Pb-Pb systems agree in large part due to uncertainties in the Pb-Pb age of CAIs. A systematic difference is found in the U isotopic compositions of quenched and plutonic angrites of +0.17‰. A difference is also found between the rare earth element (REE) patterns of these two angrite subgroups. The δ238U values are consistent with fractionation during magmatic evolution of the angrite parent melt. Stable U isotope fractionation due to a change in the coordination environment of U during incorporation into pyroxene could be responsible for such a fractionation. In this context, Pb-Pb ages derived from pyroxenes fraction should be corrected using the U isotope composition

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

International Nuclear Information System (INIS)

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

1982-01-01

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

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

International Nuclear Information System (INIS)

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

1981-12-01

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

Evaluation of the U-Pu residual mass from spent fuel assemblies with passive and active neutronic methods

International Nuclear Information System (INIS)

Bignan, G.; Martin-Deidier, L.

1991-01-01

The interpretation of passive and active neutronic measurements to evaluate the U-Pu residual mass in spent fuel assemblies is presented as follows: passive neutron measurements are well correlated to the plutonium mass, active neutron measurements give information linked to the fissile mass content of the assembly ( 235 U + 239 Pu + 241 Pu) and, using the passive neutron measurement, lead to the 235 U mass content of the assemblies

Proposal of new 235U nuclear data to improve keff biases on 235U enrichment and temperature for low enriched uranium fueled lattices moderated by light water

International Nuclear Information System (INIS)

Wu, Haicheng; Okumura, Keisuke; Shibata, Keiichi

2005-06-01

The under prediction of k eff depending on 235 U enrichment in low enriched uranium fueled systems, which had been a long-standing puzzle especially for slightly enriched ones, was studied in this report. Benchmark testing was carried out with several evaluated nuclear data files, including the new uranium evaluations from preliminary ENDF/B-VII and CENDL-3.1. Another problem reviewed here was k eff underestimation vs. temperature increase, which was observed in the sightly enriched system with recent JENDL and ENDF/B uranium evaluations. Through the substitute analysis of nuclear data of 235 U and 238 U, we propose a new evaluation of 235 U data to solve both of the problems. The new evaluation was tested for various uranium fueled systems including low or highly enriched metal and solution benchmarks in the ICSBEP handbook. As a result, it was found that the combination of the new evaluation of 235 U and the 238 U data from the preliminary ENDF/B-VII gives quite good results for most of benchmark problems. (author)

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

International Nuclear Information System (INIS)

Iturbe G, J.L.

1990-02-01

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

Isotopic analysis of uranium hexafluoride highly enriched in U-235; Analyse isotopique de l'hexafluorure d'uranium fortement enrichi en U 235

Energy Technology Data Exchange (ETDEWEB)

Chaussy, L; Boyer, R [Commissariat a l' Energie Atomique, Pierrelatte (France). Centre d' Etudes Nucleaires

1968-07-01

Isotopic analysis of uranium in the form of the hexafluoride by mass-spectrometry gives gross results which are not very accurate. Using a linear interpolation method applied to two standards it is possible to correct for this inaccuracy as long as the isotopic concentrations are less than about 10 per cent in U-235. Above this level, the interpolations formula overestimates the results, especially if the enrichment of the analyzed samples is higher than 1.3 with respect to the standards. A formula is proposed for correcting the interpolation equation and for the extending its field of application to high values of the enrichment ({approx_equal}2) and of the concentration. It is shown that by using this correction the results obtained have an accuracy which depends practically only on that of the standards, taking into account the dispersion in the measurements. (authors) [French] L'analyse isotopique de l'uranium sous forme d'hexafluorure, par spectrometrie de masse, fournit des resultats bruts entaches d'inexactitude. Une methode d'interpolation lineaire entre deux etalons permet de corriger cette inexactitude, tant que les concentrations isotopiques sont inferieures a 10 pour cent en U-235 environ. Au-dessus de cette valeur, la formule d'interpolation surestime les resultats, notamment si l'enrichissement des echantillons analyses par rapport aux etalons est superieur a 1,3. On propose une formule de correction de l'equation d'interpolation qui etend son domaine d'application jusqu'a des valeurs elevees d'enrichissement ({approx_equal}2) et de concentration. On montre experimentalement que par cette correction, les resultats atteignent, a la precision des mesures, une exactitude qui ne depend pratiquement plus que de celles des etalons. (auteurs)

Theoretical studies aiming at the IEA-R1 reactor core conversion from high U-235 enrichment to low U-235 enrichment

International Nuclear Information System (INIS)

Frajndlich, R.

1982-01-01

The research reactors, of which the fuel elements are of MTR type, functions presently, almost in their majority with high U-235 enrichment. The fear that those fuel elements might generate a considerabLe proliferation of nuclear weapons rendered almost mandatory the conversion of highly enriched fuel elements to a low U-235 enrichment. As the IEA-R1 reactor of IPEN is operating with highly enriched fuel elements a study aiming at this conversion was done. The problems related to the conversion and the results obtained, demonstrated the technical viabilty for its realization. (E.G.) [pt

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

International Nuclear Information System (INIS)

Montoya, Modesto

2013-01-01

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

Fission Product Yield Study of 235U, 238U and 239Pu Using Dual-Fission Ionization Chambers

Science.gov (United States)

Bhatia, C.; Fallin, B.; Howell, C.; Tornow, W.; Gooden, M.; Kelley, J.; Arnold, C.; Bond, E.; Bredeweg, T.; Fowler, M.; Moody, W.; Rundberg, R.; Rusev, G.; Vieira, D.; Wilhelmy, J.; Becker, J.; Macri, R.; Ryan, C.; Sheets, S.; Stoyer, M.; Tonchev, A.

2014-05-01

To resolve long-standing differences between LANL and LLNL regarding the correct fission basis for analysis of nuclear test data [M.B. Chadwick et al., Nucl. Data Sheets 111, 2891 (2010); H. Selby et al., Nucl. Data Sheets 111, 2891 (2010)], a collaboration between TUNL/LANL/LLNL has been established to perform high-precision measurements of neutron induced fission product yields. The main goal is to make a definitive statement about the energy dependence of the fission yields to an accuracy better than 2-3% between 1 and 15 MeV, where experimental data are very scarce. At TUNL, we have completed the design, fabrication and testing of three dual-fission chambers dedicated to 235U, 238U, and 239Pu. The dual-fission chambers were used to make measurements of the fission product activity relative to the total fission rate, as well as for high-precision absolute fission yield measurements. The activation method was employed, utilizing the mono-energetic neutron beams available at TUNL. Neutrons of 4.6, 9.0, and 14.5 MeV were produced via the 2H(d,n)3He reaction, and for neutrons at 14.8 MeV, the 3H(d,n)4He reaction was used. After activation, the induced γ-ray activity of the fission products was measured for two months using high-resolution HPGe detectors in a low-background environment. Results for the yield of seven fission fragments of 235U, 238U, and 239Pu and a comparison to available data at other energies are reported. For the first time results are available for neutron energies between 2 and 14 MeV.

Ternary Fission of U235 by Resonance Neutrons

International Nuclear Information System (INIS)

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

1965-01-01

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

Neutron methods for measuring 235U content in UF6 gas

International Nuclear Information System (INIS)

Stromswold, D.C.; Peurrung, A.J.; Reeder, P.L.; Pappas, R.A.; Sunberg, D.S.

1996-10-01

In the United States and Russia, UF 6 gas streams of highly enriched uranium and lower enrichment uranium am being blended to reduce the stockpile of the highly enriched material. The resultant uranium is no longer useful for weapons, but is suitable as fuel for nuclear reactors. A method to verify the blending of high- and low-enrichment uranium was developed at Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy, Office of Research and Development (NN-20). In the United States, blending occurs at the U.S. Department of Energy's Portsmouth Gaseous Diffusion Plant located near Portsmouth, Ohio. In Russia, the blending takes place at Novouralsk. The United States is purchasing the blended product produced in Russia in a program to reduce the availability of enriched uranium that can be used for weapons production. Monitoring the 235 U mass flux of the input stream having the highly enriched uranium will provide confidence that high-enrichment uranium is being consumed in the blending process, and monitoring the output stream will provide an on-line measure of the 235 U in the mixed product. The Portsmouth plant is a potential test facility for non-destructive technology to monitor blending. In addition, monitoring the blending at Portsmouth can support International Atomic Energy Agency activities on controlling and reducing enriched uranium stockpiles

Study of 235U very asymmetric thermal fission

International Nuclear Information System (INIS)

Sida, J.L.

1989-12-01

The fission fragment separator Lohengrin of the Institut Laue-Langevin in Grenoble was used to determine the yields of the very asymmetric light fission products (A=84-69) as a function of A, Z, and the kinetic energy E. The proton pairing effect causes fine structures in the mass distribution, in the mean nuclear charge anti Z and its variance σ z , and in the mean kinetic energies of the elements. The neutron pairing effect in the production yields is found for the first time of the same order of magnitude than the proton pairing effect. In the mass region investigated both are the largest observed in fission of 235 U. A decrease in the mean kinetic energy for the isotopes of Ni and Cu was observed. It points to a large deformation at scission. Our results support the view that very asymmetric low-energy fission is a weakly dissipative process. The highly deformed transient system breaks by a slow necking-in process [fr

Fission product yields from 6 to 9 MeV neutron induced fission of 235U and 238U

International Nuclear Information System (INIS)

Chapman, T.C.

1978-01-01

The yields of 28 mass chains have been measured for fission of 235 U and 238 U induced by neutrons at four different energies from 6.0 to 9.1 MeV. This is the first experimental measurement where sufficient energy resolution was obtained to observe the effect of the onset of second-chance fission in the case of symmetric fission. The 111 Ag results are compared with measurements at other neutron energies and with previous theoretical predictions. Several of the nuclide results are presented in graphical form, and all nuclide results are presented in tabular form, as a function of neutron energy. The mass chains measured range from 84 to 156, and their half-lives range from 18 minutes to 30 years

Determination of U-235 quantity in fresh fuel elements by neutron coincidence collar technique

International Nuclear Information System (INIS)

Almeida, M.C.M. de; Almeida, S.G. de; Marzo, M.A.S.; Moita, L.P.M.

1990-01-01

The U-235 quantity per lenght of fresh fuel assemblies of the Angra-I first recharge was determined by Neutron Coincidence Collar technique (N.C.C.). This technique is well-founded in fresh fuel assemblies activation by thermal neutrons from AmLi source to generate U-235 fission neutrons. These neutrons are detected by coincidence method in polyethylene structure where 18 He-3 detectors were placed. The coincidence counting results, in active mode (AmLi), showed 0,7% to standard deviation and equal to 1,49% to mass in 1000s of counting. The accuracies of different calibration methods were evaluated and compared. The results showed that the operator declared values are consistent. This evaluation was part of technical-exchange program between Safeguards Laboratory from C.N.E.N. and Los Alamos National Lab., United States. (author)

Effect of cycloheximide and actinomycin D on radionuclide 235U-induced apoptosis

International Nuclear Information System (INIS)

Fu Qiang; Zhang Lansheng; Zhu Shoupeng

1999-01-01

Objective: The mechanism of apoptosis induced by radionuclide 235 U was studied. Methods: MTT and JAM assay were used to analyse the cell viability and quantification of fragmented DNA. Results: The inhibitor of protein cycloheximide (CHX), and the inhibitor of RNA synthesis, actinomycin D. cannot inhibit the apoptosis induced by 235 U, but CHX can partly inhibit apoptotic cells DNA fragmentation. Conclusion: The pathway of apoptosis induced by radionuclide 235 U is different from X-and γ-ray external irradiation, protein synthesis is not essential for it, but synthetic endonuclease is necessary for DNA fragmentation of apoptotic cells

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

International Nuclear Information System (INIS)

Wohlfarth, H.

1977-01-01

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

Computer program FPIP-REV calculates fission product inventory for U-235 fission

Science.gov (United States)

Brown, W. S.; Call, D. W.

1967-01-01

Computer program calculates fission product inventories and source strengths associated with the operation of U-235 fueled nuclear power reactor. It utilizes a fission-product nuclide library of 254 nuclides, and calculates the time dependent behavior of the fission product nuclides formed by fissioning of U-235.

Standard test method for analysis of urine for uranium-235 and uranium-238 isotopes by inductively coupled plasma-mass spectrometry

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This test method covers the determination of the concentration of uranium-235 and uranium-238 in urine using Inductively Coupled Plasma-Mass Spectrometry. This test method can be used to support uranium facility bioassay programs. 1.2 This method detection limits for 235U and 238U are 6 ng/L. To meet the requirements of ANSI N13.30, the minimum detectable activity (MDA) of each radionuclide measured must be at least 0.1 pCi/L (0.0037 Bq/L). The MDA translates to 47 ng/L for 235U and 300 ng/L for 238U. Uranium– 234 cannot be determined at the MDA with this test method because of its low mass concentration level equivalent to 0.1 pCi/L. 1.3 The digestion and anion separation of urine may not be necessary when uranium concentrations of more than 100 ng/L are present. 1.4 Units—The values stated in picoCurie per liter units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1....

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

Energy Technology Data Exchange (ETDEWEB)

Iturbe G, J L

1990-02-15

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

Absolute measurements of the alpha-gamma emitters activities by a sum-coincidence method

International Nuclear Information System (INIS)

Tobias, C.C.B.

1982-01-01

The absolute activity of U-235 contained in a UO 2 sample, using a sum-coincidence circuit which selected only the alpha particles which were simultaneous with the well known 184 Kev gamma radiation from Th-231. The alpha particles were detected by ZnS(Ag) scintillator specially designed to show its maximun efficiency for U-235 alpha particles, whereas the gamma radiation was detected by NaI(Tl) scintillation detector. The values obtained for the half-life of U-235 was compared with data from various observers using different experimental techniques. (Author) [pt

Use of integral experiments for the assessment of a new 235U IRSN-CEA evaluation

Directory of Open Access Journals (Sweden)

Ichou Raphaëlle

2017-01-01

Full Text Available The Working Party on International Nuclear Data Evaluation Co-operation (WPEC subgroup 29 (SG 29 was established to investigate an issue with the 235U capture cross-section in the energy range from 0.1 to 2.25 keV, due to a possible overestimation of 10% or more. To improve the 235U capture crosssection, a new 235U evaluation has been proposed by the Institut de Radioprotection et de Sûreté Nucléaire (IRSN and the CEA, mainly based on new time-of-flight 235U capture cross-section measurements and recent fission cross-section measurements performed at the n_TOF facility from CERN. IRSN and CEA Cadarache were in charge of the thermal to 2.25 keV energy range, whereas the CEA DIF was responsible of the high energy region. Integral experiments showing a strong 235U sensitivity are used to assess the new evaluation, using Monte-Carlo methods. The keff calculations were performed with the 5.D.1 beta version of the MORET 5 code, using the JEFF-3.2 library and the new 235U evaluation, as well as the JEFF-3.3T1 library in which the new 235U has been included. The benchmark selection allowed highlighting a significant improvement on keff due to the new 235U evaluation. The results of this data testing are presented here.

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

CERN Document Server

American Society for Testing and Materials. Philadelphia

2005-01-01

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

48 CFR 252.235-7001 - Indemnification under 10 U.S.C. 2354-cost reimbursement.

Science.gov (United States)

2010-10-01

....S.C. 2354-cost reimbursement. 252.235-7001 Section 252.235-7001 Federal Acquisition Regulations.... 2354—cost reimbursement. As prescribed in 235.070-3, use the following clause: Indemnification Under 10 U.S.C. 2354—Cost Reimbursement (DEC 1991) (a) This clause provides for indemnification under 10 U.S...

Activation Doppler Measurements on U 238 and U 235 in Some Fast Reactor Spectra

Energy Technology Data Exchange (ETDEWEB)

Tiren, L I; Gustafsson, I

1968-03-15

Measurements of the Doppler effect in U-238 capture and U-235 fission have been made by means of the activation technique in three different neutron spectra in the fast critical assembly FR0. The experiments involved the irradiation of thin uranium metal foils or oxide disks, which were heated in a small oven located at the core centre. The measurements on U-238 were extended to 1780 deg K and on U-235 to 1470 deg K. A core region surrounding the oven was homogenized in order to facilitate the interpretation of results. The reaction rates in the uranium samples were detected by gamma counting. The experimental method was checked with regard to systematic errors by irradiations in a thermal spectrum. The data obtained for U-238 capture were corrected for the effect of neutron collisions in the oven wall, and were extrapolated to zero sample thickness. In the softest spectrum (core 5) a Doppler effect (relative increase in capture rate) of 0.260 {+-} 0.018 was obtained on heating from 343 to 1780 deg K, and in the hardest spectrum (core 3) the corresponding value was 0.030 {+-} 0.003. An appreciable Doppler effect in U-235 fission was obtained only in the softest spectrum, in which the measured increase in fission rate on heating from 320 to 1470 deg K was 0.007 {+-} 0.003.

Determination of the isotopic abundance of 235U in rocks in search for an Oklo phenomenon in Brazil by activation analysis

International Nuclear Information System (INIS)

Vasconcellos, M.B.A.; Armelin, M.J.A.; Lima, F.W. de; Fulfaro, R.

1981-09-01

Isotopic analyses of uranium are generally carried out by mass spectrometry, with a precision better than 1%. In nuclear laboratories it is often necessary to perform rapid determinations of 235 U isotopic abundances. Thermal neutron activation analysis by delayed neutron counting or by high resolution gamma-ray spectrometry can be applied for this purpose, although with less precision than by mass spectrometry. In this work, delayed neutron counting and gamma-ray spectrometry are used for the determination of the isotopic abundance of 235 U in rocks from the Northeastern region of Brazil. In the case of the application of delayed neutron counting, the rocks are analyzed non-destructively. When high resolution gamma-ray spectrometry is applied, a pre-irradiation chemical separation had to be performed, by extraction of uranium with tributylphosphate. By both methods employed the results for the isotopic abundance of 235 U can be considered as equal to the natural value of 0.702%, for the rocks under study. The precision attained by gamma-ray spectrometry is better than that by delayed neutron couting. (Author) [pt

Absolute calibration of the neutron yield measurement on JT-60 Upgrade

International Nuclear Information System (INIS)

Nishitani, Takeo; Takeuchi, Hiroshi; Barnes, C.W.

1991-10-01

Absolutely calibrated measurements of the neutron yield are important for the evaluation of the plasma performance such as the fusion gain Q in DD operating tokamaks. Total neutron yield is measured with 235 U and 238 U fission chambers and 3 He proportional counters in JT-60 Upgrade. The in situ calibration was performed by moving the 252 Cf neutron source toroidally through the JT-60 vacuum vessel. Detection efficiencies of three 235 U and two 3 He detectors were measured for 92 locations of the neutron point source in toroidal scans at two different major radii. The total detection efficiency for the torus neutron source was obtained by averaging the point efficiencies over the whole toroidal angle. The uncertainty of the resulting absolute plasma neutron source calibration is estimated to be ± 10%. (author)

Non-electric-dipole photofission of 235U

International Nuclear Information System (INIS)

Arruda Neto, J.D.T.; Herdade, S.B.; Carvalheiro, Z.; Simionatto, S.

1984-01-01

The electrofission cross section for 235 U has been measured from 5.8 to 22 MeV. From a combined analysis of it and the previously measured photofission cross section, using the virtual-photon formalism, the photofission cross section for excitations other than E1 has been determined. (Author) [pt

Fission cross section ratios for 233,234,236U relative to 235U from 0.5 to 400 MeV

International Nuclear Information System (INIS)

Lisowski, P.W.; Gavron, A.; Parker, W.E.; Balestrini, S.J.; Carlson, A.D.; Wasson, O.A.; Hill, N.W.

1991-01-01

Neutron-induced fission cross section ratios from 0.5 to 400 MeV for samples of 233, 234, 236 U relative to 235 U have been measured at the WNR neutron Source at Los Alamos. The fission reaction rate was determined using a fast parallel plate ionization chamber at a 20-m flight path. Cross sections over most the energy range were also extracted using the neutron fluence determined with three different proton telescope arrangements. Those data provided the shape of the 235 U(n,f) cross section relative to the hydrogen scattering cross section. That shape was then normalized to the very accurately known value for 235 U(n,f) at 14.1 MeV to allow us to obtain cross section section values from the ratio data and our values for 235 U(n,f). 6 refs., 1 fig

Fission cross section ratios for 233,234,236U relative to 235U from 0.5 to 400 MeV

International Nuclear Information System (INIS)

Lisowski, P.W.; Gavron, A.; Parker, W.E.; Balestrini, S.J.; Carlson, A.D.; Wasson, O.A.; Hill, N.W.

1992-01-01

Neutron-induced fission cross section ratios from 0.5 to 400 MeV for samples of 233,234,236 U relative to 235 U have been measured at the WNR neutron Source at Los Alamos. The fission reaction rate was determined using a fast parallel plate ionization chamber at a 20-m flight path. Cross sections over most of the energy range were also extracted using the neutron fluence determined with three different proton telescope arrangements. Those data provided the shape of the 235 U(n, f) cross section relative to the hydrogen scattering cross section. That shape was then normalized to the very accurately known value for 235 U(n, f) at 14.1 MeV which will allow us to obtain cross section values from the ratio data and our values for 235 U(n, f). (orig.)

Determination of U235 enrichment from nuclear fuel by neutronic activation

International Nuclear Information System (INIS)

Almeida, M.C.M. de.

1988-01-01

The enrichment of 235 U in UO 2 pellets samples through the instrumental neutron activation analysis method (I.N.A.A.) was determined. By high resolution gamma-ray spectrometry (H.R.G.S.), from analysis of isotopic ratios between fission products peaks from 235 U and 239 Np different energies peaks from 238 U, the enrichment was achieved. The 'Boatstrap' statistics technique for the analytical results, which is based in shaping results of an unknown distribution to the Gaussian distribution by B replications in interested statistics such as: the mean and its standard error, was introduced. (M.J.C.) [pt

Uranium isotope ratios of Muonionalusta troilite and complications for the absolute age of the IVA iron meteorite core

Science.gov (United States)

Brennecka, Gregory A.; Amelin, Yuri; Kleine, Thorsten

2018-05-01

The crystallization ages of planetary crustal material (given by basaltic meteorites) and planetary cores (given by iron meteorites) provide fiducial marks for the progress of planetary formation, and thus, the absolute ages of these objects fundamentally direct our knowledge and understanding of planet formation and evolution. The lone precise absolute age of planetary core material was previously obtained on troilite inclusions from the IVA iron meteorite Muonionalusta. This previously reported Pb-Pb age of 4565.3 ± 0.1 Ma-assuming a 238U/235U =137.88-only post-dated the start of the Solar System by approximately 2-3 million years, and mandated fast cooling of planetary core material. Since an accurate Pb-Pb age requires a known 238U/235U of the sample, we have measured both 238U/235U and Pb isotopic compositions of troilite inclusions from Muonionalusta. The measured 238U/235U of the samples range from ∼137.84 to as low as ∼137.22, however based on Pb and U systematics, terrestrial contamination appears pervasive and has affected samples to various extents for Pb and U. The cause of the relative 235U excess in one sample does not appear to be from terrestrial contamination or the decay of short-lived 247Cm, but is more likely from fractionation of U isotopes during metal-silicate separation during core formation, exacerbated by the extreme U depletion in the planetary core. Due to limited Pb isotopic variation and terrestrial disturbance, no samples of this study produced useful age information; however the clear divergence from the previously assumed 238U/235U of any troilite in Muonionalusta introduces substantial uncertainty to the previously reported absolute age of the sample without knowledge of the 238U/235U of the sample. Uncertainties associated with U isotope heterogeneity do not allow for definition of a robust age of solidification and cooling for the IVA core. However, one sample of this work-paired with previous work using short

Ground water contamination with (238)U, (234)U, (235)U, (226)Ra and (210)Pb from past uranium mining: cove wash, Arizona.

Science.gov (United States)

Dias da Cunha, Kenya Moore; Henderson, Helenes; Thomson, Bruce M; Hecht, Adam A

2014-06-01

The objectives of the study are to present a critical review of the (238)U, (234)U, (235)U, (226)Ra and (210)Pb levels in water samples from the EPA studies (U.S. EPA in Abandoned uranium mines and the Navajo Nation: Red Valley chapter screening assessment report. Region 9 Superfund Program, San Francisco, 2004, Abandoned uranium mines and the Navajo Nation: Northern aum region screening assessment report. Region 9 Superfund Program, San Francisco, 2006, Health and environmental impacts of uranium contamination, 5-year plan. Region 9 Superfund Program, San Franciso, 2008) and the dose assessment for the population due to ingestion of water containing (238)U and (234)U. The water quality data were taken from Sect. "Data analysis" of the published report, titled Abandoned Uranium Mines Project Arizona, New Mexico, Utah-Navajo Lands 1994-2000, Project Atlas. Total uranium concentration was above the maximum concentration level for drinking water (7.410-1 Bq/L) in 19 % of the water samples, while (238)U and (234)U concentrations were above in 14 and 17 % of the water samples, respectively. (226)Ra and (210)Pb concentrations in water samples were in the range of 3.7 × 10(-1) to 5.55 × 102 Bq/L and 1.11 to 4.33 × 102 Bq/L, respectively. For only two samples, the (226)Ra concentrations exceeded the MCL for total Ra for drinking water (0.185 Bq/L). However, the (210)Pb/(226)Ra ratios varied from 0.11 to 47.00, and ratios above 1.00 were observed in 71 % of the samples. Secular equilibrium of the natural uranium series was not observed in the data record for most of the water samples. Moreover, the (235)U/(total)U mass ratios ranged from 0.06 to 5.9 %, and the natural mass ratio of (235)U to (total)U (0.72 %) was observed in only 16 % of the water samples, ratios above or below the natural ratio could not be explained based on data reported by U.S. EPA. In addition, statistical evaluations showed no correlations among the distribution of the radionuclide concentrations

Independent yields of Rb and Cs isotopes from thermal-neutron induced fission of 235U

International Nuclear Information System (INIS)

Balestrini, S.J.; Decker, R.; Wollnik, H.; Wuensch, K.D.; Jung, G.; Koglin, E.; Siegert, G.

1979-01-01

The relative yields of Rb and Cs isotopes from thermal-neutron fission of 235 U have been redetermined using the mass separator OSTIS, on-line at a neutron guide of the High-Flux Beam Reactor at the Institut Laue-Langevin, Grenoble, France. The separator ion source was a hot oven containing 235 U in a graphite matrix. The neutron beam was pulsed. Alkali fission products diffused out of the graphite and were ionized, thus producing a stepwise increase in the analyzed ion beam proportional to the independent fission yield. The ion beam and the fissions in the source were monitored simultaneously. The diffusion of Rb and Cs from the source was exponential in time with half-lives ranging from 2.8 to 18 sec, depending upon the element and source temperature. The independent fission yields of Rb and Cs are normalized by equating their element yields to each other and to a value computed from the charge distributions observed with the recoil separator LOHENGRIN and well established mass yields. Fractional independent yields are deduced from the independent fission yields, and these compare very well with the EOZ model described by Wahl

Identification of high-spin states in 235U

International Nuclear Information System (INIS)

Lorenz, A.; Makarenko, V.E.; Chukreev, F.E.

1994-02-01

The results of a 235 U high spin states study are analysed. A new way to assign newly observed gamma ray transitions is proposed. Such assignments deals with low spin parts of the level scheme without introducing high spin level states. (author)

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

International Nuclear Information System (INIS)

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

1989-01-01

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

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

Science.gov (United States)

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

2017-12-01

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

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

International Nuclear Information System (INIS)

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

2008-01-01

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

R-matrix analyses of the 235U and 239Pu neutron cross sections

International Nuclear Information System (INIS)

Derrien, H.; de Saussure, G.; Larson, N.M.; Leal, L.C.; Perez, R.B.

1988-01-01

The resonance parameter analysis code SAMMY was used to perform consistent resonance analyses of several 235 U and 239 Pu fission and capture cross section and transmission measurements up to 110 eV for 235 U and up to 1 keV for 239 Pu. The method of analysis, the measurement selection and the results are briefly outlined in this paper

DEVELOPMENT OF ENRICHMENT VERIFICATION ASSAY BASED ON THE AGE AND 235U AND 238U ACTIVITIES OF THE SAMPLES

International Nuclear Information System (INIS)

AL-YAMAHI, H.; EL-MONGY, S.A.

2008-01-01

Development of the enrichment verification methods is the backbone of the nuclear materials safeguards skeleton. In this study, the 235U percentage of depleted , natural and very slightly enriched uranium samples were estimated based on the sample age and the measured activity of 235U and 238U. The HpGe and NaI spectrometry were used for samples assay. A developed equation was derived to correlate the sample age and 235U and 238U activities with the enrichment percentage (E%). The results of the calculated E% by the deduced equation and the target E% values were found to be similar and within 0.58 -1.75% bias in the case of HpGe measurements. The correlation between them was found to be very sharp. The activity was also calculated based on the measured sample count rate and the efficiency at the gamma energies of interest. The correlation between the E% and the 235U activity was estimated and found to be linearly sharp. The results obtained by NaI was found to be less accurate than these obtained by HpGe. The bias in the case of NaI assay was in the range from 6.398% to 22.8% for E% verification

Independent yields of Rb and Cs isotopes from thermal-neutron induced fission of /sup 235/U

Energy Technology Data Exchange (ETDEWEB)

Balestrini, S.J.; Decker, R.; Wollnik, H.; Wuensch, K.D.; Jung, G.; Koglin, E.; Siegert, G.

1979-12-01

The relative yields of Rb and Cs isotopes from thermal-neutron fission of /sup 235/U have been redetermined using the mass separator OSTIS, on-line at a neutron guide of the High-Flux Beam Reactor at the Institut Laue-Langevin, Grenoble, France. The separator ion source was a hot oven containing /sup 235/U in a graphite matrix. The neutron beam was pulsed. Alkali fission products diffused out of the graphite and were ionized, thus producing a stepwise increase in the analyzed ion beam proportional to the independent fission yield. The ion beam and the fissions in the source were monitored simultaneously. The diffusion of Rb and Cs from the source was exponential in time with half-lives ranging from 2.8 to 18 sec, depending upon the element and source temperature. The independent fission yields of Rb and Cs are normalized by equating their element yields to each other and to a value computed from the charge distributions observed with the recoil separator LOHENGRIN and well established mass yields. Fractional independent yields are deduced from the independent fission yields, and these compare very well with the EOZ model described by Wahl.

$\\gamma$-ray energy spectra and multiplicities from the neutron-induced fission of $^{235}$U using STEFF

CERN Document Server

An experiment is proposed to use the STEFF spectrometer at n_TOF to study fragment $\\gamma$-correlations following the neutron-induced fission of $^{235}$U. The STEFF array of 12 NaI detectors will allow measurements of the single $\\gamma$-energy, the $\\gamma$ multiplicity, and the summed $\\gamma$energy distributions as a function of the mass and charge split, and deduced excitation energy in the fission event. These data will be used to study the origin of fission-fragment angular momenta, examining angular distribution eects as a function of incident neutron energy. The principal application of this work is in meeting the NEA high-priority request for improved $\\gamma$ray data from $^{235}$U(n; F). To improve the detection rate and expand the range of detection angles, STEFF will be modied to include two new ssion-fragment detectors each at 45 to the beam direction.

Using 238U/235U ratios to understand the formation and oxidation of reduced uranium solids in naturally reduced zones

Science.gov (United States)

Jemison, N.; Johnson, T. M.; Druhan, J. L.; Davis, J. A.

2016-12-01

Uranium occurs in groundwater primarily as soluble and mobile U(VI), which can be reduced to immobile U(IV), often observed in sediments as uraninite. Numerous U(VI)-contaminated sites, such as the DOE field site in Rifle, CO, contain naturally reduced zones (NRZ's) that have relatively high concentrations of organic matter. Reduction of heavy metals occurs within NRZ's, producing elevated concentrations of iron sulfides and U(IV). Slow, natural oxidation of U(IV) from NRZ's may prolong U(VI) contamination of groundwater. The reduction of U(VI) produces U(IV) with a higher 238U/235U ratio. Samples from two NRZ sediment cores recovered from the Rifle site revealed that the outer fringes of the NRZ contain U(IV) with a high 238U/235U ratio, while lower values are observed in the center . We suggest that as aqueous U(VI) was reduced in the NRZ, it was driven to lower 238U/235U values, such that U(IV) formed in the core of the NRZ reflects a lower 238U/235U. Two oxidation experiments were conducted by injecting groundwater containing between 14.9 and 21.2 mg/L dissolved O2 as an oxidant into the NRZ. The oxidation of U(IV) from this NRZ increased aqueous U(VI) concentrations and caused a shift to higher 238U/235U in groundwater as U(IV) was oxidized primarily on the outer fringes of the NRZ. In total these observations suggest that the stability of solid phase uranium is governed by coupled reaction and transport processes. To better understand various reactive transport scenarios we developed a model for the formation and oxidation of NRZ's utilizing the reactive transport software CrunchTope. These simulations suggest that the development of isotopically heterogeneous U(IV) within NRZ's is largely controlled by permeability of the NRZ and the U(VI) reduction rate. Oxidation of U(IV) from the NRZ's is constrained by the oxidation rate of U(IV) as well as iron sulfides, which can prevent oxidation of U(IV) by scavenging dissolved oxygen.

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

Science.gov (United States)

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

2010-12-01

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

Impact of the 235U Covariance Data in Benchmark Calculations

International Nuclear Information System (INIS)

Leal, Luiz C.; Mueller, D.; Arbanas, G.; Wiarda, D.; Derrien, H.

2008-01-01

The error estimation for calculated quantities relies on nuclear data uncertainty information available in the basic nuclear data libraries such as the U.S. Evaluated Nuclear Data File (ENDF/B). The uncertainty files (covariance matrices) in the ENDF/B library are generally obtained from analysis of experimental data. In the resonance region, the computer code SAMMY is used for analyses of experimental data and generation of resonance parameters. In addition to resonance parameters evaluation, SAMMY also generates resonance parameter covariance matrices (RPCM). SAMMY uses the generalized least-squares formalism (Bayes method) together with the resonance formalism (R-matrix theory) for analysis of experimental data. Two approaches are available for creation of resonance-parameter covariance data. (1) During the data-evaluation process, SAMMY generates both a set of resonance parameters that fit the experimental data and the associated resonance-parameter covariance matrix. (2) For existing resonance-parameter evaluations for which no resonance-parameter covariance data are available, SAMMY can retroactively create a resonance-parameter covariance matrix. The retroactive method was used to generate covariance data for 235U. The resulting 235U covariance matrix was then used as input to the PUFF-IV code, which processed the covariance data into multigroup form, and to the TSUNAMI code, which calculated the uncertainty in the multiplication factor due to uncertainty in the experimental cross sections. The objective of this work is to demonstrate the use of the 235U covariance data in calculations of critical benchmark systems

Impact of the 235U covariance data in benchmark calculations

International Nuclear Information System (INIS)

Leal, Luiz; Mueller, Don; Arbanas, Goran; Wiarda, Dorothea; Derrien, Herve

2008-01-01

The error estimation for calculated quantities relies on nuclear data uncertainty information available in the basic nuclear data libraries such as the U.S. Evaluated Nuclear Data File (ENDF/B). The uncertainty files (covariance matrices) in the ENDF/B library are generally obtained from analysis of experimental data. In the resonance region, the computer code SAMMY is used for analyses of experimental data and generation of resonance parameters. In addition to resonance parameters evaluation, SAMMY also generates resonance parameter covariance matrices (RPCM). SAMMY uses the generalized least-squares formalism (Bayes' method) together with the resonance formalism (R-matrix theory) for analysis of experimental data. Two approaches are available for creation of resonance-parameter covariance data. (1) During the data-evaluation process, SAMMY generates both a set of resonance parameters that fit the experimental data and the associated resonance-parameter covariance matrix. (2) For existing resonance-parameter evaluations for which no resonance-parameter covariance data are available, SAMMY can retroactively create a resonance-parameter covariance matrix. The retroactive method was used to generate covariance data for 235 U. The resulting 235 U covariance matrix was then used as input to the PUFF-IV code, which processed the covariance data into multigroup form, and to the TSUNAMI code, which calculated the uncertainty in the multiplication factor due to uncertainty in the experimental cross sections. The objective of this work is to demonstrate the use of the 235 U covariance data in calculations of critical benchmark systems. (authors)

Fission cross section ratios for sup 233,234,236 U relative to sup 235 U from 0. 5 to 400 MeV

Energy Technology Data Exchange (ETDEWEB)

Lisowski, P.W.; Gavron, A.; Parker, W.E.; Balestrini, S.J. (Los Alamos National Lab., NM (USA)); Carlson, A.D.; Wasson, O.A. (National Inst. of Standards and Technology, Gaithersburg, MD (USA)); Hill, N.W. (Oak Ridge National Lab., TN (USA))

1991-01-01

Neutron-induced fission cross section ratios from 0.5 to 400 MeV for samples of {sup 233, 234, 236}U relative to {sup 235}U have been measured at the WNR neutron Source at Los Alamos. The fission reaction rate was determined using a fast parallel plate ionization chamber at a 20-m flight path. Cross sections over most the energy range were also extracted using the neutron fluence determined with three different proton telescope arrangements. Those data provided the shape of the {sup 235}U(n,f) cross section relative to the hydrogen scattering cross section. That shape was then normalized to the very accurately known value for {sup 235}U(n,f) at 14.1 MeV to allow us to obtain cross section section values from the ratio data and our values for {sup 235}U(n,f). 6 refs., 1 fig.

Study of fission fragments produced by 14N + 235U reaction

International Nuclear Information System (INIS)

Yalcinkaya, M.; Erduran, M.N.; Ganioglu, E.; Akkus, B.; Bostan, M.; Gurdal, G.; Erturk, S.; Balabanski, D.; Minkova, A.; Danchev, M.

2005-01-01

This work was performed to understand the structure of neutron rich fission fragments around ∼ 130 region. A thin metallic 235 U target was bombarded by 14 N beam with 10 MeV/A from the Separated Sector Cyclotron at the National Accelerator Centre, Cape Town, South Africa. The main goal to detect and identify fission fragments and to obtain their mass distribution was achieved by using Solar Cell detectors in the AFRODITE (African Omnipurpose Detector for Innovative Techniques and Experiments) spectrometer. The X-rays emitted from fission fragments were detected by LEP detectors and γ rays emitted from excited states of the fission fragments were detected by CLOVER detectors in the spectrometer. (author)

Theoretical Model for Volume Fraction of UC, 235U Enrichment, and Effective Density of Final U 10Mo Alloy

Energy Technology Data Exchange (ETDEWEB)

Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); McGarrah, Eric J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)

2016-04-12

The purpose of this document is to provide a theoretical framework for (1) estimating uranium carbide (UC) volume fraction in a final alloy of uranium with 10 weight percent molybdenum (U-10Mo) as a function of final alloy carbon concentration, and (2) estimating effective ²³⁵U enrichment in the U-10Mo matrix after accounting for loss of ²³⁵U in forming UC. This report will also serve as a theoretical baseline for effective density of as-cast low-enriched U-10Mo alloy. Therefore, this report will serve as the baseline for quality control of final alloy carbon content

Decay heat measurement of U-235

International Nuclear Information System (INIS)

Baumung, K.

1976-01-01

The calorimeter and the transport mechanism for the fuel samples was designed and is under construction now. Calculations of the heat-source distributions for different 235U-contents led to an optimal enrichment of the UO 2 -samples which minimizes the effects of the bad heat conductivity of the oxide on temperature measurement. Monte-Carlo-calculations of the γ-leakage-spectra yielded data which allow, from the γ-energy-flow measurements, to calculate the total γ-energy loss as well as the portions of the β- and γ-heating. (orig.) [de

Use of integral experiments for the assessment of the 235U capture cross section within the CIELO Project

Directory of Open Access Journals (Sweden)

Ichou Raphaelle

2016-01-01

Full Text Available A new 235U capture cross-section evaluation, evaluated by ORNL and the CEA Bruyères-le-Châtel (BRC has been proposed within the CIELO project. IRSN, who participates in the CIELO project, contributes with data testing and has carried out benchmark calculations using few benchmarks, extracted from the ICSBEP database, for testing the new 235U evaluation. The benchmarks have been selected by privileging the experiments showing small experimental uncertainties and a significant sensitivity to 235U capture cross-section. The keff calculations were performed with both the MCNP 6 code and the 5.C.1 release of the MORET 5 code, using the ENDF/B-VII.1 library for all isotopes except 235U, for which both the ENDF/B-VII.1 and the new 235U evaluation was used. The benchmark selection allowed highlighting a significant effect on keff of the new 235U capture cross-section. The results of this data testing, provided as input for the evaluators, are presented here.

Symmetry of neutron-induced 235U fission at individual resonances. III

Energy Technology Data Exchange (ETDEWEB)

Cowan, G A; Bayhurst, B P; Prestwood, R J; Gilmore, J S; Knobeloch, G W [Los Alamos Scientific Laboratory, University of California, Los Alamos, NM (United States)

1970-05-15

A number of experiments have been described in recent years which document variations in the yields of symmetric or near-symmetric fission products at resonances in 235-U and 239-Pu neutron-induced fission. In the case of 239-Pu fission it has been demonstrated in a statistically significant sample of s-wave neutron resonances (J{sup {pi}} = 0{sup +} or 1{sup +}) that the 0{sup +} levels have a characteristic 115Cd yield which is a factor of four higher than the yield at 1{sup +} levels. The fission widths of the J = 0 levels are larger than the J = 1 levels by a factor of ten. The populations of the two groups are in reasonable agreement with the expected (2J + 1) distributions. Previous efforts to obtain equally detailed data in 235-U fission and 233-U fission by the 'wheel' technique have not been entirely successful due in large part to the high level densities in the epithermal excitation functions of these nuclides and the consequent difficulty in characterizing fission yields in a sufficiently large and well-resolved sample of levels. In a recent 'wheel' experiment (late summer, 1969) vith a 235-U target the energy resolution was sufficiently improved in the region 20 eV-60 eV to allow characterization of a sample of 38 reasonably well-resolved levels by their relative symmetry of fission. (author)

Study of correcting the effect of daughter age on determining 235U enrichment of fuel rods

International Nuclear Information System (INIS)

Deng Jingshan; Zhou Chengfang; Luo Minxuan; Liu Yun

1997-01-01

Gamma-ray passive technique is a very effective method to assay and determine 235 U enrichment of nuclear power plant fuel rods. There is a weakness in this passive method, i.e. only after the uranium isotope daughters of UO 2 pellets have reached to equilibrium with uranium parent, then the 235 U enrichment can be determined. This weakness greatly restricts the application of the method. A new two-peak and two-window technique is developed that can overcome the interference of uranium daughter decay in determining 235 U enrichment of nuclear fuel rods, and the results are very satisfactory. The new technique will play an important role in the gamma-ray passive technique for determining 235 U enrichment of fuel rods. This new technique also makes the gamma-ray passive method perfectly. (11 figs., 6 tabs.)

Measurement of the uranium-235 fission cross section over the neutron energy range 1 to 6 MeV

International Nuclear Information System (INIS)

Barton, D.M.; Diven, B.C.; Hansen, G.E.; Jarvis, G.A.; Koontz, P.G.; Smith, R.K.

1976-01-01

The ratio of the fission cross section of 235 U to the scattering cross section of 1 H was measured in the 1- to 6-MeV range using monoenergetic neutrons from a pulsed 3 H(p,n) 3 He source. In this measurement, solid-state detectors determined fission fragment and recoil proton emissions from back-to-back U(99.7%) and polyethylene disks. Timing permitted discrimination against room-scattered neutron backgrounds. Absolute values for 235 U(n,f) are obtained using the Hopkins-Breit evaluation of the hydrogen-scattering cross section

Quantification of 235U and 238U activity concentrations for undeclared nuclear materials by a digital gamma-gamma coincidence spectroscopy.

Science.gov (United States)

Zhang, Weihua; Yi, Jing; Mekarski, Pawel; Ungar, Kurt; Hauck, Barry; Kramer, Gary H

2011-06-01

The purpose of this study is to investigate the possibility of verifying depleted uranium (DU), natural uranium (NU), low enriched uranium (LEU) and high enriched uranium (HEU) by a developed digital gamma-gamma coincidence spectroscopy. The spectroscopy consists of two NaI(Tl) scintillators and XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The results demonstrate that the spectroscopy provides an effective method of (235)U and (238)U quantification based on the count rate of their gamma-gamma coincidence counting signatures. The main advantages of this approach over the conventional gamma spectrometry include the facts of low background continuum near coincident signatures of (235)U and (238)U, less interference from other radionuclides by the gamma-gamma coincidence counting, and region-of-interest (ROI) imagine analysis for uranium enrichment determination. Compared to conventional gamma spectrometry, the method offers additional advantage of requiring minimal calibrations for (235)U and (238)U quantification at different sample geometries. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Analysis of the 235U neutron cross sections in the resolved resonance range

International Nuclear Information System (INIS)

Leal, L.C.; de Saussure, G.; Perez, R.B.

1989-01-01

Using recent high-resolution measurements of the neutron transmission of 235 U and the spin-separated fission cross-section data of Moore et al., a multilevel analysis of the 235 U neutron cross sections was performed up to 300 eV. The Dyson Metha Δ 3 statistics were used to help locate small levels above 100 eV where resonances are not clearly resolved even in the best resolution measurements available. The statistical properties of the resonance parameters are discussed

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

Science.gov (United States)

Li, Shengjie

1997-09-01

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

Isotopic analysis of uranium hexafluoride highly enriched in U-235

International Nuclear Information System (INIS)

Chaussy, L.; Boyer, R.

1968-01-01

Isotopic analysis of uranium in the form of the hexafluoride by mass-spectrometry gives gross results which are not very accurate. Using a linear interpolation method applied to two standards it is possible to correct for this inaccuracy as long as the isotopic concentrations are less than about 10 per cent in U-235. Above this level, the interpolations formula overestimates the results, especially if the enrichment of the analyzed samples is higher than 1.3 with respect to the standards. A formula is proposed for correcting the interpolation equation and for the extending its field of application to high values of the enrichment (≅2) and of the concentration. It is shown that by using this correction the results obtained have an accuracy which depends practically only on that of the standards, taking into account the dispersion in the measurements. (authors) [fr

The application of the Harwell neutron absorptiometer to the analysis of U-235 in nuclear fuel components

International Nuclear Information System (INIS)

Jones, T.L.; Watson, J.; Taylor, T.A.H.

1979-05-01

This paper describes the application of the Harwell Neutron Absorptiometer to routine analysis of the U-235 content of fuel element inserts manufactured at the Dounreay Nuclear Power Development Establishment for the use in Materials Testing Reactors. The instrument response, which is principally dependent on the 235 U closely follows a logarithmic relationship. Neutron attenuation due to the aluminium matrix and the presence of 238 U is less than 2% of the total attenuation. The absorptiometer can be used to estimate the weight of 235 U in a single insert with a total error in the range 1 to 1.6%. (author)

Analysis of the 235U neutron cross sections in the resolved resonance range

International Nuclear Information System (INIS)

Leal, L.C.; de Saussure, G.; Perez, R.B.

1989-01-01

Using recent high-resolution measurements of the neutron transmission of 235 U and the spin-separated fission cross-section data of Moore et al., a multilevel analysis of the 235 U neutron cross sections was performed up to 300 eV. The Dyson Metha Δ 3 statistics were used to help locate small levels above 100 eV where resonances are not clearly resolved even in the best resolution measurements available. The statistical properties of the resonance parameters are discussed. 13 refs., 8 figs., 1 tab

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Photon-induced Fission Product Yield Measurements on 235U, 238U, and 239Pu

Science.gov (United States)

Krishichayan, Fnu; Bhike, M.; Tonchev, A. P.; Tornow, W.

2015-10-01

During the past three years, a TUNL-LANL-LLNL collaboration has provided data on the fission product yields (FPYs) from quasi-monoenergetic neutron-induced fission of 235U, 238U, and 239Pu at TUNL in the 0.5 to 15 MeV energy range. Recently, we have extended these experiments to photo-fission. We measured the yields of fission fragments ranging from 85Kr to 147Nd from the photo-fission of 235U, 238U, and 239Pu using 13-MeV mono-energetic photon beams at the HIGS facility at TUNL. First of its kind, this measurement will provide a unique platform to explore the effect of the incoming probe on the FPYs, i.e., photons vs. neutrons. A dual-fission ionization chamber was used to determine the number of fissions in the targets and these samples (along with Au monitor foils) were gamma-ray counted in the low-background counting facility at TUNL. Details of the experimental set-up and results will be presented and compared to the FPYs obtained from neutron-induced fission at the same excitation energy of the compound nucleus. Work supported in part by the NNSA-SSAA Grant No. DE-NA0001838.

Experimental study of the thermal fission of uranium 235 in the region of symmetrical masses; Contribution a l'etude experimentale de la fission thermique de l'uranium 235 dans la region des masses symetriques

Energy Technology Data Exchange (ETDEWEB)

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

1967-03-15

Energy correlation experiments with fission fragments are strongly perturbed, in the symmetric region, by the detection of spurious events caused by the apparatus. We show that the measurement of an additional parameter, namely the difference in time-of-flight between the fragments, enables us to eliminate these difficulties. In this work we show also an original method of calibration of the time-of-flight set-up. For thermal fission of {sup 235}U, values of mass yields in the symmetric region are found to agree quantitatively with radiochemical values. Moreover, the average total kinetic energy distribution as a function of the pre-neutron emission masses of the fragments has been calculated. This curve presents in the symmetric region a large dip, the value of which takes on the value 21.2 {+-} 0.8 MeV. This value is smaller than previously published results. (author) [French] Les mesures correlees des energies cinetiques des fragments de fission sont fortement perturbees, dans la region symetrique, par la detection d'evenements aberrants d'origine instrumentale. Nous montrons que la mesure d'un parametre supplementaire, a savoir, la difference des temps de vol des deux fragments, nous permet d'eliminer ces difficultes. Dans ce travail, nous indiquons egalement une methode originale de calibration du dispositif de mesure des temps de vol. Dans le cas de la fission thermique de {sup 235}U, nous avons trouve, dans la region symetrique, une courbe de rendement des masses, en accord quantitatif avec les donnees radiochimiques. De plus, nous avons calcule la distribution de l'energie cinetique totale moyenne en fonction de la masse des fragments, avant emission neutronique. Cette courbe presente, dans la region symetrique, un creux important, dont la valeur atteint 21,2 {+-} 0,8 MeV. Cette valeur est inferieure aux resultats precedemment publies. (auteur)

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

International Nuclear Information System (INIS)

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

1995-01-01

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

235U isotope enrichment in the metastable levels of UI

International Nuclear Information System (INIS)

Gagne, J.M.; Demers, Y.; Dreze, C.; Pianarosa, P.

1983-01-01

We have used optical pumping to produce a substantial 235 U enrichment in the metastable levels of UI in the discharge afterglow of a hollow-cathode vapor generator. The measured isotope-enrichment factor for the level at 3800 cm -1 is approximately 20

Computer simulation of the natural U 238 and U 235 radioactive series decay

International Nuclear Information System (INIS)

Barna, A.; Oncescu, M.

1980-01-01

The principles of the computer simulation of a radionuclide decay - its decay scheme adoption and codification -, and the adoption principle of a radionuclide chain in a series are applied to the natural U 238 and U 235 series radionuclide decay computer simulation. Using the computer simulation data of these two series adopted chains, the decay characteristic quantities of the series radionuclides, the gamma spectra and the basic characteristics of each of these series are determined and compared with the experimental values given in the literature. (author)

Measurement of 235U fission spectrum-averaged cross sections and neutron spectrum adjusted with the activation data

International Nuclear Information System (INIS)

Kobayashi, Katsuhei; Kobayashi, Tooru

1992-01-01

The 235 U fission spectrum-averaged cross sections for 13 threshold reactions were measured with the fission plate (27 cm in diameter and 1.1 cm thick) at the heavy water thermal neutron facility of the Kyoto University Reactor. The Monte Carlo code MCNP was applied to check the deviation from the 235 U fission neutron spectrum due to the room-scattered neutrons, and it was found that the resultant spectrum was close to that of 235 U fission neutrons. Supplementally, the relations to derive the absorbed dose rates with the fission plate were also given using the calculated neutron spectra and the neutron Kerma factors. Finally, the present values of the fission spectrum-averaged cross sections were employed to adjust the 235 U fission neutron spectrum with the NEUPAC code. The adjusted spectrum showed a good agreement with the Watt-type fission neutron spectrum. (author)

Pulsed reactivity measurements of large 235U--Al castings in H2O

International Nuclear Information System (INIS)

Pellarin, D.J.; Jarriel, J.L.

1977-01-01

The safe storage and handling of large 235 U-Al castings at the Savannah River Plant are assured by limiting the number of fuel pieces and their spacing such that the k/sub eff/ calculated by KENO-IV with Hansen-Roach cross sections does not exceed some conservative limit with complete, accidental water immersion. For economic reasons, the conservative limit on the calculated k/sub eff/ is generally chosen as high as possible consistent with an accurate knowledge of the margin of error in the k/sub eff/ calculation. The margin of error for arrays of large, hollow cylinders of highly enriched 235 U-Al alloy fuel in H 2 O is presented. The subcritical reactivities were derived from pulsed neutron measurements. The measurements are extended to castings with 17.39 kg 235 U/m, the pulsed experiments are more accurately analyzed by the αv -1 method, and measurements for both 7-assembly hexagonal and 2 x 3 square pitch lattices are compared with KENO-IV calculations

Comparative studies for determining U-235/U-238 relation in solutions of natural and depleted uranium using gamma spectrometry and neutron activation analysis

International Nuclear Information System (INIS)

Cassorla F, V.; Valle M, L.; Pena V, L.

1988-01-01

Two experimental methods were developed for determining U-235/U-238 ratio in uranium solutions. The isotopic was measured by high resolution ratio gamma-ray spectrometry (G.S.) and neutron activation analysis (N.A.A.). The precision obtained was similar for both methods, but better sensitivity was obtained by N.A.A. The accuracy in both cases was stablished by comparison with samples previously analyzed by mass spectrometry, the results were satisfactory for both techniques. Studies involving the influence of the nitric acid concentration on the isotopic ratio measurement, also were done. In addition, computer programs for faster data reduction were developped, in the case of N.A.A. (author)

Comparison of 235U fission cross sections in JENDL-3.3 and ENDF/B-VI

International Nuclear Information System (INIS)

Kawano, Toshihiko; Carlson, Allan D.; Matsunobu, Hiroyuki; Nakagawa, Tsuneo; Shibata, Keiichi

2002-01-01

Comparisons of evaluated fission cross sections for 235 U in JENDL-3.3 and ENDF/B-VI are carried out. The comparisons are made for both the differential and integral data. The fission cross sections as well as the fission ratios are compared with the experimental data in detail. Spectrum averaged cross sections are calculated and compared with the measurements. The employed spectra are the 235 U prompt fission neutron spectrum, the 252 Cf spontaneous fission neutron spectrum, and the neutron spectrum produced by a 9 Be(d, xn) reaction. For 235 U prompt fission neutron spectrum, the ENDF/B-VI evaluation reproduces experimental averaged cross sections. For 252 Cf and 9 Be(d, xn) neutron spectra, the JENDL-3.3 evaluation gives better results than ENDF/B-VI. (author)

Towards absolute neutrino masses

Energy Technology Data Exchange (ETDEWEB)

Vogel, Petr [Kellogg Radiation Laboratory 106-38, Caltech, Pasadena, CA 91125 (United States)

2007-06-15

Various ways of determining the absolute neutrino masses are briefly reviewed and their sensitivities compared. The apparent tension between the announced but unconfirmed observation of the 0{nu}{beta}{beta} decay and the neutrino mass upper limit based on observational cosmology is used as an example of what could happen eventually. The possibility of a 'nonstandard' mechanism of the 0{nu}{beta}{beta} decay is stressed and the ways of deciding which of the possible mechanisms is actually operational are described. The importance of the 0{nu}{beta}{beta} nuclear matrix elements is discussed and their uncertainty estimated.

R-matrix analysis of the 235U neutron cross sections

International Nuclear Information System (INIS)

Leal, L.C.; de Saussure, G.; Perez, R.B.

1988-01-01

The ENDFB-V representation of the 235 U neutron cross sections in the resolved resonance region is unsatisfactory: below 1 eV the cross sections are given by ''smooth files'' (file 3) rather than by resonance parameters; above 1 eV the single-level formalism used by ENDFB-V necessitates a structured file 3 contribution consisting of more than 1300 energy points; furthermore, information on level-spins has not been included. Indeed the ENDFB-V 235 U resonance region is based on an analysis done in 1970 for ENDFB-III and therefore does not include the results of high quality measurements done in the past 18 years. The present paper presents the result of an R-matrix multilevel analysis of recent measurements as well as older data. The analysis also extends the resolved resonance region from its ENDFB-V upper limit of 81 eV to 110 eV. 13 refs., 2 figs., 1 tab

Fission fragment yields and total kinetic energy release in neutron-induced fission of235,238U,and239Pu

Science.gov (United States)

Tovesson, F.; Duke, D.; Geppert-Kleinrath, V.; Manning, B.; Mayorov, D.; Mosby, S.; Schmitt, K.

2018-03-01

Different aspects of the nuclear fission process have been studied at Los Alamos Neutron Science Center (LANSCE) using various instruments and experimental techniques. Properties of the fragments emitted in fission have been investigated using Frisch-grid ionization chambers, a Time Projection Chamber (TPC), and the SPIDER instrument which employs the 2v-2E method. These instruments and experimental techniques have been used to determine fission product mass yields, the energy dependent total kinetic energy (TKE) release, and anisotropy in neutron-induced fission of U-235, U-238 and Pu-239.

Distribution of nanomole quantities of 235U in young and adult Japanese quail and in the F1 generation. Comparison with 153Gd

International Nuclear Information System (INIS)

Robinson, G.A.

1988-01-01

Enriched uranium, 93.16% for 235 U, served as a tracer of uranium deposition in an avian species, the Japanese quail. A second label, 153 Gd, provided for monitoring of procedures and for estimation of the 235 U content of live eggs. Depositions of 235 U were greater than for 153 Gd in all tissues except the yolk sac and the liver. Skeletal levels for 235 U were age- and sex-dependent. Feathers contained only 0.11% of the 235 U tracer in contrast to 50% of the endogenous uranium. The results show that 235 U provides for tracing uranium metabolism in small animals, since in quail the tracer increased the uranium burden of the body by only 1-8%. (author)

Application of the 226Ra-230Th-234U and 227Ac-231Pa-235U radiochronometers to uranium certified reference materials

International Nuclear Information System (INIS)

Rolison, J.M.; Treinen, K.C.; McHugh, K.C.; Gaffney, A.M.; Williams, R.W.

2017-01-01

Uranium certified reference materials (CRM) issued by New Brunswick Laboratory were subjected to dating using four independent uranium-series radiochronometers. In all cases, there was acceptable agreement between the model ages calculated using the 231 Pa- 235 U, 230 Th- 234 U, 227 Ac- 235 U or 226 Ra- 234 U radiochronometers and either the certified 230 Th- 234 U model date (CRM 125-A and CRM U630), or the known purification date (CRM U050 and CRM U100). The agreement between the four independent radiochronometers establishes these uranium certified reference materials as ideal informal standards for validating dating techniques utilized in nuclear forensic investigations in the absence of standards with certified model ages for multiple radiochronometers. (author)

Criticality Data for Spherical 235U, 239Pu, and 237Np Systems Reflector-Moderated by Low Capturing-Moderator Materials

International Nuclear Information System (INIS)

Loaiza, David J.; Stratton, William

2004-01-01

The critical dimensions of spherical systems moderated and reflected by low-capturing materials such as D 2 O, BeO, Be, and C were investigated. A parametric study of the critical mass of enriched uranium, plutonium, and neptunium is examined and tabulated. The results obtained expand on the understanding of reflector-moderated critical systems, and they show regions of unstable criticality for 235 U and 239 Pu reflected cores at intermediate densities. This instability is illustrated by calculations of the positive reactivity coefficient of volume expansion. The coefficient is positive, not negative, in the intermediate density region for 235 U and 239 Pu systems. For 237 Np cores reflected by the same moderator, the effect is negligible. The critical dimensions were calculated with the DANTSYS codes using the Hansen-Roach cross-section libraries. This study is both a summary of mostly unpublished calculations and new calculations. Experimental data for these configurations are extremely limited. These are examined in the text when applicable

Measurement of gamma-ray multiplicity spectra and the alpha value for {sup 235}U resonances

Energy Technology Data Exchange (ETDEWEB)

Grigor` ev, Yu V [Institute of Physics and Power Engineering, Obninsk (Russian Federation); Georgiev, G P; Stanchik, Kh [Joint Inst. for Nuclear Research, Dubna (Russian Federation)

1997-06-01

Gamma spectra from 1 to 12 multiplicity were measured on th 500 m flight path of the IBR-30 reactor using a 16-section 32 L NaI(Tl) crystal scintillation detector able to hold 2 metallic samples of 90% {sup 235}U and 10% {sup 238}U 0.00137 atoms/b and 0.00411 atoms/b thick. Multiplicity spectra were obtained for resolved resonances in the E = 1-150 eV energy region. They were used to determine the value of {alpha} = {sigma}{sub {gamma}}/{sigma}{sub f} for 165 resonances of {sup 235}U. (author). 6 refs, 7 figs, 1 tab.

Resonance analysis and evaluation of the 235U neutron induced cross sections

International Nuclear Information System (INIS)

Leal, L.C.

1990-06-01

Neutron cross sections of fissile nuclei are of considerable interest for the understanding of parameters such as resonance absorption, resonance escape probability, resonance self-shielding,and the dependence of the reactivity on temperature. In the present study, new techniques for the evaluation of the 235 U neutron cross sections are described. The Reich-Moore formalism of the Bayesian computer code SAMMY was used to perform consistent R-matrix multilevel analyses of the selected neutron cross-section data. The Δ 3 -statistics of Dyson and Mehta, along with high-resolution data and the spin-separated fission cross-section data, have provided the possibility of developing a new methodology for the analysis and evaluation of neutron-nucleus cross sections. The results of the analysis consists of a set of resonance parameters which describe the 235 U neutron cross sections up to 500 eV. The set of resonance parameters obtained through a R-matrix analysis are expected to satisfy statistical properties which lead to information on the nuclear structure. The resonance parameters were tested and showed good agreement with the theory. It is expected that the parametrization of the 235 U neutron cross sections obtained in this dissertation represents the current state of art in data as well as in theory and, therefore, can be of direct use in reactor calculations. 44 refs., 21 figs., 8 tabs

Delayed β ray spectrum of 235U fission fragments

International Nuclear Information System (INIS)

Pascholati, P.R.

1973-01-01

The time-dependent electron spectra of fission fragments from the thermal-neutron-induced fission of 235 U are calculated. The Gross theory of nuclear beta decay is used to obtain the decay constant and individual electron spectra. The mean energy per fission carried by the electrons and the number of electrons per fission are also calculated. Comparison of these calculated spectra to experimental ones shows good agreements. (Author) [pt

Measurement of the fission cross-section of {sup 235}U and {sup 239}Pu for thermal neutrons; Mesures des sections de fission de {sup 235}U et de {sup 239}Pu en neutrons thermiques

Energy Technology Data Exchange (ETDEWEB)

Fraysse, G; Prosdocimi, A; Netter, F; Samour, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

Improved techniques of fast detection have been applied for determining the fission cross-sections of {sup 235}U and {sup 239}Pu with reference to the absorption cross-section of Boron. Monochromatic neutron beams of 0.0322 eV, 0.0626 eV and 0.275 eV have been employed. Use has been made of a Xe-filled gaseous scintillator and of a low-geometry solid state ion chamber. Both measured alpha and fission rates. The results at the reference energy of 0.0253 eV are: ({sigma}{sub F}){sub 0} {sup 235}U = 588 {+-} 10 barns ({sigma}{sub F}){sub 0} {sup 239}Pu = 738 {+-} 7 barns. (authors) [French] Des techniques avancees de comptage rapide ont ete mise en oeuvre pour determiner la section efficace de fission de {sup 235}U et de {sup 239}Pu par rapport a celle d'absorption du bore. Des faisceaux de neutrons monochromatiques de 0,0322 eV, 0,0626 eV et 0,275 eV ont ete employes. Les detecteurs utilises sont un scintillateur gazeux rempli de xenon et une chambre d'ionisation a etat solide a basse geometrie. Les deux ont mesure les taux des desintegrations alpha et des fissions. Les resultats a l'energie de reference de 0,0253 eV sont: ({sigma}{sub F}){sub 0} {sup 235}U = 588 {+-} 10 barns ({sigma}{sub F}){sub 0} {sup 239}Pu = 738 {+-} 7 barns. (auteurs)

Comparison of {sup 235}U fission cross sections in JENDL-3.3 and ENDF/B-VI

Energy Technology Data Exchange (ETDEWEB)

Kawano, Toshihiko [Kyushu Univ., Fukuoka (Japan); Carlson, Allan D. [National Institute of Standards and Technology (United States); Matsunobu, Hiroyuki [Data Engineering, Inc., Fujisawa, Kanagawa (Japan); Nakagawa, Tsuneo; Shibata, Keiichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Talou, Patrick; Young, Philip G.; Chadwick, Mark B. [Los Alamos National Laboratory, Los Alamos, NM (United States)

2002-01-01

Comparisons of evaluated fission cross sections for {sup 235}U in JENDL-3.3 and ENDF/B-VI are carried out. The comparisons are made for both the differential and integral data. The fission cross sections as well as the fission ratios are compared with the experimental data in detail. Spectrum averaged cross sections are calculated and compared with the measurements. The employed spectra are the {sup 235}U prompt fission neutron spectrum, the {sup 252}Cf spontaneous fission neutron spectrum, and the neutron spectrum produced by a {sup 9}Be(d, xn) reaction. For {sup 235}U prompt fission neutron spectrum, the ENDF/B-VI evaluation reproduces experimental averaged cross sections. For {sup 252}Cf and {sup 9}Be(d, xn) neutron spectra, the JENDL-3.3 evaluation gives better results than ENDF/B-VI. (author)

Preparation of 235U target by electrodeposition

International Nuclear Information System (INIS)

Chen Qiping; Zhong Wenbin; Li Yougen

2004-12-01

A target for the production of fission 99 Mo in a nuclear reactor is composed of an enclosed, cylindrical vessel. Preferable vessel is comprised of stainless steel, having a thin, continuous, uniform layer of 235 U integrally bonded to its inner walls. Two processes are introduced for electrodepositing uranium on to the inner walls of the vessel. One processes is electrodepositing UO 2 from UO 2 (NO 3 ) 2 -(NH 4 ) 2 CO 4 ·H 2 O solution; the other is electrodepositing pure uranium metal from molten salt. Its plating efficiency and plating quantity from a molten bath is higher than UO 2 from the aqueous system. (authors)

Proposal for an absolute, atomic definition of mass

International Nuclear Information System (INIS)

Wignall, J.W.G.

1991-11-01

It is proposed that the mass of a particle be defined absolutely as its de Broglie frequency, measured as the mean de Broglie wavelength of the particle when it has a mean speed (v) and Lorentz factor γ; the masses of systems too large to have a measurable de Broglie wavelength mean are then to be derived by specifying the usual inertial and additive properties of mass. This definition avoids the use of an arbitrary macroscopic standard such as the prototype kilogram, and, if present theory is correct, does not even require the choice of a specific particle as a mass standard. Suggestions are made as to how this absolute mass can be realized and measured at the macroscopic level and, finally, some comments are made on the effect of the new definition on the form of the equations of physics. 19 refs

Consistent Data Assimilation of Actinide Isotopes: 235U and 239Pu

International Nuclear Information System (INIS)

Palmiottti, G.; Hiruta, H.; Salvatores, M.

2011-01-01

In this annual report we illustrate the methodology of the consistent data assimilation that allows to use the information coming from integral experiments for improving the basic nuclear parameters used in cross section evaluation. A series of integral experiments were analyzed using the EMPIRE evaluated files for 235 U, 238 U, and 239 Pu. Inmost cases the results have shown quite large worse results with respect to the corresponding existing evaluations available for ENDF/B-VII. The observed discrepancies between calculated and experimental results were used in conjunction with the computed sensitivity coefficients and covariance matrix for nuclear parameters in a consistent data assimilation. Only the GODIVA and JEZEBEL experimental results were used, in order to exploit information relative to the isotope of interest that are, in this particular case: 235 U and 239 Pu. The results obtained by the consistent data assimilation indicate that with reasonable modifications (mostly within the initial standard deviation) it is possible to eliminate the original large discrepancies on the K eff of the two critical configurations. However, some residual discrepancy remains for a few fission spectral indices that are, most likely, to be attributed to the detector cross sections.

Short Lived Fission Product Yield Measurements in 235U, 238U and 239Pu

Science.gov (United States)

Silano, Jack; Tonchev, Anton; Tornow, Werner; Krishichayan, Fnu; Finch, Sean; Gooden, Matthew; Wilhelmy, Jerry

2017-09-01

Yields of short lived fission products (FPYs) with half lives of a few minutes to an hour contain a wealth of information about the fission process. Knowledge of short lived FPYs would contribute to existing data on longer lived FPY mass and charge distributions. Of particular interest are the relative yields between the ground states and isomeric states of FPYs since these isomeric ratios can be used to determine the angular momentum of the fragments. Over the past five years, a LLNL-TUNL-LANL collaboration has made precision measurements of FPYs from quasi-monoenergetic neutron induced fission of 235U, 238U and 239Pu. These efforts focused on longer lived FPYs, using a well characterized dual fission chamber and several days of neutron beam exposure. For the first time, this established technique will be applied to measuring short lived FPYs, with half lives of minutes to less than an hour. A feasibility study will be performed using irradiation times of < 1 hour, improving the sensitivity to short lived FPYs by limiting the buildup of long lived isotopes. Results from this exploratory study will be presented, and the implications for isomeric ratio measurements will be discussed. This work was performed under the auspices of US DOE by LLNL under Contract DE-AC52-07NA27344.

The measurement of tripartition alpha particle low energy spectrum in 235U fission induced by thermal neutrons

International Nuclear Information System (INIS)

El Hage Sleiman, F.

1980-01-01

The energy spectrum of the α particles emitted in the thermal neutron induced fission of 235 U was measured from 11.5 MeV down to 2 MeV using the parabola mass spectrometer Lohengrin at the ILL high flux reactor. A Monte Carlo program, that simulates the α particle motion to the spectrometer, has been developed. Numerical results of Monte Carlo calculations for differents values of parameter are reported. The overall energy spectrum is slightly asymmetric at low energy. The possible reasons for the existence of this asymmetry are discussed [fr

Cross sections and neutron yields for U233, U235 and Pu239 at 2200 m/sec

International Nuclear Information System (INIS)

Sjoestrand, N.G.; Story, J.S.

1960-04-01

The experimental information on the 2200 m/sec values for σ abs , σ f , α, ν and η for 233 U , 235 U and 23 been collected and discussed. The values will later be used in an evaluation of a 'best' set of data. In appendix the isotopic abundances of the uranium isotopes are discussed and also the alpha activities of the uranium isotopes and Pu-239

Evaluation of Uranium-235 Measurement Techniques

Energy Technology Data Exchange (ETDEWEB)

Kaspar, Tiffany C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dibert, Mark W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-05-23

Monolithic U-Mo fuel plates are rolled to final fuel element form from the original cast ingot, and thus any inhomogeneities in ²³⁵U distribution present in the cast ingot are maintained, and potentially exaggerated, in the final fuel foil. The tolerance for inhomogeneities in the ²³⁵U concentration in the final fuel element foil is very low. A near-real-time, nondestructive technique to evaluate the ²³⁵U distribution in the cast ingot is required in order to provide feedback to the casting process. Based on the technical analysis herein, gamma spectroscopy has been recommended to provide a near-real-time measure of the ²³⁵U distribution in U-Mo cast plates.

14.2 MeV neutron induced U-235 fission cross section measurement

International Nuclear Information System (INIS)

Li Jingwen; Shen Guanren; Ye Zongyuan; Li Anli; Zhou Shuhua; Sun Zhongfan; Wu Jingxia; Huang Tanzi

1986-01-01

The cross section of U-235 fission induced by 14.2 MeV neutrons was measured by the time correlated associated particle method. The result obtained is (2.078+-0.040) barn. Comparison with other author's is also given. (author)

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

International Nuclear Information System (INIS)

Meadows, J.W.

1986-12-01

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

On uncertainties and fluctuations of averaged neutron cross sections in unresolved resonance energy region for 235U, 238U, 239Pu

International Nuclear Information System (INIS)

Van'kov, A.A.; Blokhin, A.I.; Manokhin, V.N.; Kravchenko, I.V.

1985-01-01

This paper analyses the reasons for the differences which exist between group-averaged evaluated cross-section data from different evaluated data files for U235, U238 and Pu239 in the unresolved resonance energy region. (author)

Simultaneous measurement of fission fragments and prompt neutrons for thermal neutron-induced fission of U-235

Energy Technology Data Exchange (ETDEWEB)

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

1997-03-01

Simultaneous measurement of fission fragments and prompt neutrons following the thermal neutron induced fission of U-235 has been performed in order to obtain the neutron multiplicity (v) and its emission energy ({eta}) against the specified mass (m{sup *}) and the total kinetic energy (TKE). The obtained value of -dv/dTKE(m{sup *}) showed a saw-tooth distribution. The average neutron energy <{eta}>(m{sup *}) had a distribution with a reflection symmetry around the half mass division. The measurement also gave the level density parameters of the specified fragment, a(m{sup *}), and this parameters showed a saw-tooth trend too. The analysis by a phenomenological description of this parameters including the shell and collective effects suggested the existence of a collective motion of the fission fragments. (author)

Reimiep 87. An interlaboratory U-235 enrichment determination by gamma measurement on solid UF6 sample

International Nuclear Information System (INIS)

Aparo, M.; Cresti, P.

1988-01-01

Gamma spectroscopy technique, based on the measurement of U 235 186 KeV flux, is now currently used for the determination of Uranium enrichment in different material of nuclear fuel cycle, namely: Uranium metallic, UO 2 pellets, UF 6 liquid or solid. The present paper describes the use of such a technique and the obtained results in determining the U 235 /U atomic isotopic abundance on a certified UF 6 solid sample. The measurements have been carried out in the frame work of the partecipation to the ''UF 6 Interlaboratory Measurements Evaluation Programme'' organized by CBNM/Geel with the support of the ESARDA (European Safeguards Research and Development Association)

Fuel cycle cost comparison of choices in U-235 recycle in the HTGR

International Nuclear Information System (INIS)

Rothstein, M.P.

1976-07-01

An analysis of alternative options for the recycle of discharged makeup U-235 (''residual'' makeup) in HTGRs shows that the three-particle system which has been the reference plan remains optimal. This result considers both the resource utilization and the handling costs attendant to the alternative strategies (primarily in the recycle facility and in waste disposal). Furthermore, this result appears to be true under all forseeable economic conditions. A simple risk assessment indicates that recycle cost (including reprocessing, refabrication, and related waste disposal) would have to double or triple in order for the alternative U-235 recycle schemes to become attractive. This induces some degree of confidence in the choice of staying with the reference cycle in spite of the large degree of uncertainty over recycle and its costs

Neutron Energy Spectra from Neutron Induced Fission of 235U at 0.95 MeV and of 238U at 1.35 and 2.02 MeV

Energy Technology Data Exchange (ETDEWEB)

Almen, E; Holmqvist, B; Wiedling, T

1971-09-15

The shapes of fission neutron spectra are of interest for power reactor calculations. Recently it has been suggested that the neutron induced fission spectrum of 235U may be harder than was earlier assumed. For this reason measurements of the neutron spectra of some fissile isotopes are in progress at our laboratory. This report will present results from studies of the energy spectra of the neutrons emitted in the neutron induced fission of 235U and 238U. The measurements were performed at an incident neutron energy of 0.95 MeV for 235U and at energies of 1.35 and 2.02 MeV for 238U using time-of-flight techniques. The time-of-flight spectra were only analysed at energies higher than those of the incident neutrons and up to about 10 MeV. Corrections for neutron attenuation in the uranium samples were calculated using a Monte Carlo program. The corrected fission neutron spectra were fitted to Maxwellian temperature distributions. For 235U a temperature of 1.27 +- 0.01 MeV gives the best fit to the experimental data and for 238U the corresponding values are 1.29 +- 0.03 MeV at 1.35 MeV and 1.29 +- 0.02 MeV at 2.02 MeV

Cross sections and neutron yields for U-233, U-235 and Pu-239 at 2200 m/sec

Energy Technology Data Exchange (ETDEWEB)

Sjoestrand, N G; Story, J S

1960-04-15

The experimental information on the 2200 m/sec values for {sigma}{sub abs}, {sigma}{sub f}, {alpha}, {nu} and {eta} for {sup 233}U , {sup 235}U and {sup 23} been collected and discussed. The values will later be used in an evaluation of a 'best' set of data. In appendix the isotopic abundances of the uranium isotopes are discussed and also the alpha activities of the uranium isotopes and Pu-239.

Evaluation of the neutron cross sections of 235U in the thermal energy region. Final report

International Nuclear Information System (INIS)

Leonard, B.R. Jr.; Kottwitz, D.A.; Thompson, J.K.

1976-02-01

The objective of this work has been to improve the knowledge of the thermal cross sections of the fissile nuclei as a step toward providing a standard data base for the nuclear industry. The methodology uses a form of the Adler-Adler multilevel-fission theory and Breit-Wigner multilevel-scattering theory. It incorporates these theories in a general nonlinear least-squares (LSQ) fitting program SIGLEARNThe analysis methodology in this work was applied to the thermal data on 235 U. A reference data file has been developed which includes most of the known data of interest. The first important result of this work is the assessment of the shape uncertainties of the partial cross sections. The results of our studies lead to the following values and error estimates for 235 U g factors in a thermal (20.44 0 C) energy spectrum: g/sub f/ = 0.97751 (+-0.11%); g/sub γ/ = 0.98230 (+-0.14%). A second important result of this study is the development of a recommended set of 2200 m/s (0.0253 eV) values of the parameters and the probable range of further adjustment which might be made. The analysis also provides the result of a common interpretation of energy-dependent absolute cross-section data of different measurements to yield a consistent set of experimental 0.0253 eV values with rigorous error estimates. It also provides normalization factors for relative fission and capture cross sections on a common basis with rigorous error estimates. The results of these analyses provide a basis for deciding what new measurements would be most beneficial. The most important of these would be improved direct capture data in the thermal region

Benchmark experiments at ASTRA facility on definition of space distribution of 235U fission reaction rate

International Nuclear Information System (INIS)

Bobrov, A. A.; Boyarinov, V. F.; Glushkov, A. E.; Glushkov, E. S.; Kompaniets, G. V.; Moroz, N. P.; Nevinitsa, V. A.; Nosov, V. I.; Smirnov, O. N.; Fomichenko, P. A.; Zimin, A. A.

2012-01-01

Results of critical experiments performed at five ASTRA facility configurations modeling the high-temperature helium-cooled graphite-moderated reactors are presented. Results of experiments on definition of space distribution of 235 U fission reaction rate performed at four from these five configurations are presented more detail. Analysis of available information showed that all experiments on criticality at these five configurations are acceptable for use them as critical benchmark experiments. All experiments on definition of space distribution of 235 U fission reaction rate are acceptable for use them as physical benchmark experiments. (authors)

Alecto - results obtained with homogeneous critical experiments on plutonium 239, uranium 235 and uranium 233; Alecto - resultats des experiences critiques homogenes realisees sur le plutonium 239, l'uranium 235 et l'uranium 233

Energy Technology Data Exchange (ETDEWEB)

Bruna, J G; Brunet, J P; Caizegues, R; Clouet d' Orval, Ch; Kremser, J; Tellier, H; Verriere, Ph [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

In this report are given the results of the homogeneous critical experiments ALECTO, made on plutonium 239, uranium 235 and uranium 233. After a brief description of the equipment, the critical masses for cylinders of diameters varying from 25 to 42 cm, are given and compared with other values (foreign results, criticality guide). With respect to the specific conditions of neutron reflection in the ALECTO experiments the minimal values of critical masses are: Pu239 M{sub c} = 910 {+-} 10 g, U235 M{sub c} = 1180 {+-} 12 g and U233 M{sub c} = 960 {+-} 10 g. Experiments relating to cross sections and constants to be used on these materials are presented. Lastly, kinetic experiments allow to compare pulsed neutron methods to fluctuation methods. [French] On presente dans ce rapport les resultats des experiences critiques homogenes ALECTO, effectuees sur le plutonium 239, l'uranium 235 et l'uranium 233. Apres avoir rappele la description des installations, on donne les masses critiques pour des cylindres de diametres variant entre 25 et 42 cm, qui sont comparees avec d'autres chiffres (resultats etrangers, guide de criticite). Dans les gammes des diametres etudies pour des cuves a fond plat reflechies lateralement, la valeur minimale des masses critiques est la suivante: Pu239 M{sub c} = 910 {+-} 10 g, U235 M{sub c} = 1180 {+-} 12 g et U233 M{sub c} 960 {+-} 10 g. Des experiences portant sur les sections efficaces et les constantes a utiliser sur ces milieux sont ensuite presentees. Enfin des experiences de cinetique permettent une comparaison entre la methode des neutrons pulses et la methode des fluctuations. (auteur)

Isotopic separation of 235U and 238U in an atomic beam with selective two-step photo-ionisation

International Nuclear Information System (INIS)

Boehm, H.D.V.

1977-01-01

The present work gives a report on investigations on isotope separation of 235 U and 238 U by means of selective two-stage photo-ionization on atomic uranium. An atomic beam of sufficient particle density was produced by dissociation of URe 2 in an electron beam heated tungsten furnace at a temperature of 2.500 k. A continuously operated rhodamin-69 dye laser with a maximum output of 120 mW and about 50 mHz band width in one-made operation was used for selective excitation from the ground state. From this state of excitation, ionization resulted achieving a light power of 1.8 W below 3030 A in the reaction volume. The measured separation factors show that the laser method enables the enrichment of uranium to the required valve of three or more percent 235 U for light water reactors in a single separation step. The hyperfine structure could be considerably better resolved compared to earlier investigations, so that it was possible for the first time to identify and measure hitherto unobserved weak components. (orig.) [de

Energy dependence of fission product yields from 235U, 238U, and 239Pu with monoenergetic neutrons between thermal and 14.8 MeV

Science.gov (United States)

Gooden, Matthew; Arnold, Charles; Bhike, Megha; Bredeweg, Todd; Fowler, Malcolm; Krishichayan; Tonchev, Anton; Tornow, Werner; Stoyer, Mark; Vieira, David; Wilhelmy, Jerry

2017-09-01

Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements has been performed. The energy dependence of a number of cumulative fission product yields (FPY) have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of fission counting using specially designed dual-fission chambers and γ-ray counting. Each dual-fission chamber is a back-to-back ionization chamber encasing an activation target in the center with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the total number of fissions in the activation target with no reference to the fission cross-section, thus reducing uncertainties. γ-ray counting of the activation target was performed on well-shielded HPGe detectors over a period of two months post irradiation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 3.6, 4.6, 5.5, 7.5, 8.9 and 14.8 MeV. Preliminary results from thermal irradiations at the MIT research reactor will also be presented and compared to present data and evaluations. This work was performed under the auspices of the U.S. Department of Energy by Los Alamos National Security, LLC under contract DE-AC52-06NA25396, Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and by Duke University and Triangle Universities Nuclear Laboratory through NNSA Stewardship Science Academic Alliance grant No. DE-FG52-09NA29465, DE-FG52-09NA29448 and Office of Nuclear Physics Grant No. DE-FG02-97ER41033.

Energy dependence of fission product yields from 235U, 238U, and 239Pu with monoenergetic neutrons between thermal and 14.8 MeV

Directory of Open Access Journals (Sweden)

Gooden Matthew

2017-01-01

Full Text Available Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements has been performed. The energy dependence of a number of cumulative fission product yields (FPY have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of fission counting using specially designed dual-fission chambers and γ-ray counting. Each dual-fission chamber is a back-to-back ionization chamber encasing an activation target in the center with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the total number of fissions in the activation target with no reference to the fission cross-section, thus reducing uncertainties. γ-ray counting of the activation target was performed on well-shielded HPGe detectors over a period of two months post irradiation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 3.6, 4.6, 5.5, 7.5, 8.9 and 14.8 MeV. Preliminary results from thermal irradiations at the MIT research reactor will also be presented and compared to present data and evaluations. This work was performed under the auspices of the U.S. Department of Energy by Los Alamos National Security, LLC under contract DE-AC52-06NA25396, Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and by Duke University and Triangle Universities Nuclear Laboratory through NNSA Stewardship Science Academic Alliance grant No. DE-FG52-09NA29465, DE-FG52-09NA29448 and Office of Nuclear Physics Grant No. DE-FG02-97ER41033.

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

International Nuclear Information System (INIS)

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

2000-01-01

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

Investigating Uranium Mobility Using Stable Isotope Partitioning of 238U/235U and a Reactive Transport Model

Science.gov (United States)

Bizjack, M.; Johnson, T. M.; Druhan, J. L.; Shiel, A. E.

2015-12-01

We report a numerical reactive transport model which explicitly incorporates the effectively stable isotopes of uranium (U) and the factors that influence their partitioning in bioactive systems. The model reproduces trends observed in U isotope ratios and concentration measurements from a field experiment, thereby improving interpretations of U isotope ratios as a tracer for U reactive transport. A major factor contributing to U storage and transport is its redox state, which is commonly influenced by the availability of organic carbon to support metal-reducing microbial communities. Both laboratory and field experiments have demonstrated that biogenic reduction of U(VI) fractionates the stable isotope ratio 238U/235U, producing an isotopically heavy solid U(IV) product. It has also been shown that other common reactive transport processes involving U do not fractionate isotopes to a consistently measurable level, which suggests the capacity to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U ratios. A recent study of a U bioremediation experiment at the Rifle IFRC site (Colorado, USA) applied Rayleigh distillation models to quantify U stable isotope fractionation observed during acetate amendment. The application of these simplified models were fit to the observations only by invoking a "memory-effect," or a constant source of low-concentration, unfractionated U(VI). In order to more accurately interpret the measured U isotope ratios, we present a multi-component reactive transport model using the CrunchTope software. This approach is capable of quantifying the cycling and partitioning of individual U isotopes through a realistic network of transport and reaction pathways including reduction, oxidation, and microbial growth. The model incorporates physical heterogeneity of the aquifer sediments through zones of decreased permeability, which replicate the observed bromide tracer, major ion chemistry, U concentration, and U

Measurement of the ^235mU Production Cross Section Using a Critical Assembly*

Science.gov (United States)

Macri, Robert; Authier, Nicolas; Becker, John; Belier, Gilbert; Bond, Evelyn; Bredeweg, Todd; Glover, S.; Meot, Vincent; Rundberg, Robert; Vieira, David; Wilhelmy, Jerry

2006-10-01

Measurements of the creation and destruction cross sections for actinide nuclei constitute an important experimental effort in support of Stockpile Stewardship. In this talk I will give a progress report on the effort to measure the production cross section of the ^235mU isomer integrated over a fission neutron spectrum. This ongoing experiment is fielded at CEA in Valduc, France, taking advantage of the CALIBAN critical assembly. This effort is performed in collaboration with LANL, LLNL, Bruyeres le Chatel, and Valduc staff. This experiment utilizes a technique to measure internal conversion electrons from the ^235mU isomer with the French BIII detector (Bruyeres le Chatel), and involves a substantial chemistry effort (LANL) to prepare targets for irradiation and counting, as well as to remove fission fragments after irradiation. Experimental techniques will be discussed and preliminary data presented. *Work performed under the auspices of the U.S. Department of Energy by Los Alamos National Laboratory (W-7405-ENG-36) and Lawrence Livermore National Laboratory (W-7405-ENG-48), and CEA-DAM under CEA-DAM NNSA-DOE agreement.

On monitoring anthropogenic airborne uranium concentrations and 235U/238U isotopic ratio by Lichen - bio-indicator technique

International Nuclear Information System (INIS)

Golubev, A.V.; Golubeva, V.N.; Krylov, N.G.; Kuznetsova, V.F.; Mavrin, S.V.; Aleinikov, A.Yu.; Hoppes, W.G.; Surano, K.A.

2005-01-01

Lichens are widely used to assess the atmospheric pollution by heavy metals and radionuclides. However, few studies are available in publications on using lichens to qualitatively assess the atmospheric pollution levels. The paper presents research results applying epiphytic lichens as bio-monitors of quantitative atmospheric contamination with uranium. The observations were conducted during 2.5 years in the natural environment. Two experimental sites were used: one in the vicinity of a uranium contamination source, the other one - at a sufficient distance away to represent the background conditions. Air and lichens were sampled at both sites monthly. Epiphytic lichens Hypogimnia physodes were used as bio-indicators. Lichen samples were taken from various trees at about 1.5m from the ground. Air was sampled with filters at sampling stations. The uranium content in lichen and air samples as well as isotopic mass ratios 235 U/ 238 U were measured by mass-spectrometer technique after uranium pre-extraction. Measured content of uranium were 1.45mgkg -1 in lichen at 2.09E-04μgm -3 in air and 0.106mgkg -1 in lichen at 1.13E-05μgm -3 in air. The relationship of the uranium content in atmosphere and that in lichens was determined, C AIR =exp(1.1xC LICHEN -12). The possibility of separate identification of natural and man-made uranium in lichens was demonstrated in principle

Evaluation of 235U(n,f) between 100 keV and 20 MeV

International Nuclear Information System (INIS)

Poenitz, W.P.

1979-07-01

The 235 U(n,f) cross section is evaluated in the energy range from 100 keV to 20 MeV. Experimental data are included up to the 1978 Harwell Conference on Neutron Physics. The evaluation methodology is discussed in detail. The shape and the normalization of the cross section are evalutated in separate steps. An extensive comparison of the evaluation result with experimental data sets is made. The shape of the cross section obtained in a preliminary version of the present evaluation and a normalization factor extracted from data provided within the framework of this evaluation were used by the Subcommittee on Standards and Normalizations of the Cross Sections Evaluation Working Group to establish 235 U(n,f) for ENDF/B-V above 100 keV. 20 figures, 6 tables

Reactive transport of uranium in a groundwater bioreduction study: Insights from high-temporal resolution 238U/235U data

Science.gov (United States)

Shiel, A. E.; Johnson, T. M.; Lundstrom, C. C.; Laubach, P. G.; Long, P. E.; Williams, K. H.

2016-08-01

We conducted a detailed investigation of U isotopes in conjunction with a broad geochemical investigation during field-scale biostimulation and desorption experiments. This investigation was carried out in the uranium-contaminated alluvial aquifer of the Rifle field research site. In this well-characterized setting, a more comprehensive understanding of U isotope geochemistry is possible. Our results indicate that U isotope fractionation is consistently observed across multiple experiments at the Rifle site. Microbially-mediated reduction is suggested to account for most or all of the observed fractionation as abiotic reduction has been demonstrated to impart much smaller, often near-zero, isotopic fractionation or isotopic fractionation in the opposite direction. Data from some time intervals are consistent with a simple model for transport and U(VI) reduction, where the fractionation factor (ε = +0.65‰ to +0.85‰) is consistent with experimental studies. However, during other time intervals the observed patterns in our data indicate the importance of other processes in governing U concentrations and 238U/235U ratios. For instance, we demonstrate that departures from Rayleigh behavior in groundwater systems arise from the presence of adsorbed species. We also show that isotope data are sensitive to the onset of oxidation after biostimulation ends, even in the case where reduction continues to remove contaminant uranium downstream. Our study and the described conceptual model support the use of 238U/235U ratios as a tool for evaluating the efficacy of biostimulation and potentially other remedial strategies employed at Rifle and other uranium-contaminated sites.

Calculation of 235U(n,n') cross sections for ENDF/B-VI

International Nuclear Information System (INIS)

Young, P.G.; Arthur, E.D.

1988-01-01

Cross sections for neutron-induced reactions on 235 U between 0.01 and 20 MeV have been calculated in a preliminary analysis for the ENDF/B-VI evaluation with particular emphasis on neutron inelastic scattering. A deformed optical model potential that fits total, elastic, inelastic, and low-energy average resonance data is used to calculate direct (n,n') cross sections and transmission coefficients for a Hauser-Feshbach statistical theory analysis using a multiple fission barrier representation. Direct cross sections for higher-lying vibrational states are provided from DWBA calculations, normalized using B(E/ital l/) values determined from (d,d') and Coulomb excitation data. Initial fission barrier parameters and transition state density enhancements appropriate to the compound systems involved were obtained from previous analyses, especially fits to charged-particle fission probability data. Further modifications to fit 235 U(n,f) data were small, and the final fission parameters are generally consistent with published values. The results from this preliminary analysis are compared with the ENDF/B-V evaluation as well as with experimental data. 26 refs., 5 figs., 3 tabs

Energy Dependence of Fission Product Yields from 235U, 238U and 239Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV

Science.gov (United States)

Gooden, Matthew; Bredeweg, Todd; Fowler, Malcolm; Vieira, David; Wilhelmy, Jerry; Tonchev, Anton; Stoyer, Mark; Bhike, Megha; Finch, Sean; Krishichayan, Fnu; Tornow, Werner

2017-09-01

The energy dependence of a number of cumulative fission product yields (FPY) have been measured using quasi- monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combi- nation of fission counting using specially designed dual-fission chambers and -ray counting. Each dual-fission chamber is a back-to-back ioniza- tion chamber encasing an activation target in the center with thin de- posits of the same target isotope in each chamber. This method allows for the direct measurement of the total number of fissions in the activa- tion target with no reference to the fission cross-section, thus reducing uncertainties. γ-ray counting of the activation target was performed on well-shielded HPGe detectors over a period of 2 months post irradiation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 3.6, 4.6 and 14.8 MeV. New data in the second chance fission region of 5.5 - 9 MeV are included. Work performed for the U.S. Department of Energy by Los Alamos National Security, LLC under Contract DE-AC52-06NA25396.

Recommended reactor coolant water chemistry requirements for WWER-1000 units with 235U higher enriched fuel

International Nuclear Information System (INIS)

Dobrevski, I.; Zaharieva, N.

2011-01-01

The last decade worldwide experience of PWRs and WWERs confirms the trends for the improvement of the nuclear power industry electricity production through the implementation of high burn-up or high fuel duty, which are usually accompanied with the usage of UO 2 fuel with higher content of 235 U - 4.0% - 4.5% (5.0%). It was concluded that the onset of sub-cooled nucleate boiling (SNB) on the fuel cladding surfaces and the initial excess reactivity of the core are the primary and basic factors accompanying the implementation of uranium fuel with higher 235 U content, aiming extended fuel cycles and higher burn-up of the fuel in Pressurized Water Reactors. As main consequences of the presence of these factors the modifications of chemical / electrochemical environments of nuclear fuel cladding- and reactor coolant system- surfaces are evaluated. These conclusions are the reason for: 1) The determination of the choices of the type of fuel cladding materials in respect with their enough corrosion resistance to the specific fuel cladding environment, created by the presence of SNB; 2) The development and implementation of primary circuit water chemistry guidelines ensuring the necessary low corrosion rates of primary circuit materials and limitation of cladding deposition and out-of-core radioactivity buildup; 3) Implementation of additional neutron absorbers which allow enough decrease of the initial concentration of H 3 BO 3 in coolant, so that its neutralization will be possible with the permitted alkalising agent concentrations. In this paper the specific features of WWER-1000 units in Bulgarian Nuclear Power Plant; use of 235 U higher enriched fuel in the WWER-1000 reactors in the Kozloduy NPP; coolant water chemistry and radiochemistry plant data during the power operation period of the Kozloduy NPP Unit 5, 15 th fuel cycle; evaluation of the approaches and results by the conversion of the WWER-1000 Units at the Kozloduy NPP to the uranium fuel with 4.3% 235 U as

Changes in Absolute Sea Level Along U.S. Coasts

Data.gov (United States)

U.S. Environmental Protection Agency — This map shows changes in absolute sea level from 1960 to 2016 based on satellite measurements. Data were adjusted by applying an inverted barometer (air pressure)...

Determination of uranium isotopes (235U, 238U) and trace elements (Cd, Pb, Cu and As) in bottled drinking water by Icp-SFMS

International Nuclear Information System (INIS)

Lara A, N.; Hernandez M, H.; Romero G, E. T.; Kuri de la C, A.; Perez B, M. A.

2016-09-01

In the present work we propose an optimized method for the quantification of uranium isotopes ( 235 U, 2 38 U) and the elements Cd, Pb, Cu and As in bottled water for drinking at trace levels of concentration. Based on the multi-element detection capability, the high sensitivity and resolution that the Mass Spectrometry with Magnetic Sector with Inductively Coupled Plasma Source (Icp-SFMS) technique offers; the high, medium and low resolution analysis conditions for the elements under study were established and optimized using and Element 2/Xr equipment and the 23 multi-elemental Certified Reference Material (CRM). The analysis method was validated using the standard reference material Nist 1643d and CRM mono-elemental s as external standards for the quantification of the analytes. Samples, targets and CRM were acidified with 2% of HNO 3 and analyzed without pretreatment under the established analysis conditions. The results obtained show concentrations of 235 U, 238 U, 111 Cd, 208 Pb, 63 Cu and 75 As in the range of μg L -1 , the linearity obtained from the calibration curves for each element has correlation coefficients < 0.99 in all cases, the accuracy of the method in terms of percent relative standard deviation (RSD %) was less than 5%, the mean recovery rate of Nist 1643d ranged from 96.46% to 101.12%. The optimization of the method guarantees the stability and calibration of the equipment throughout the analysis, as well as the ability to resolve interferences. In conclusion, the method proposed using Icp-SFMS offers the advantages of being fast and simple for the multi-elemental analysis in water at trace levels, with low limits of quantification and detection, with good linearity, accuracy, precision and reproducibility to a degree of reliability of 95%. (Author)

Trace element distribution and 235U/238U ratios in Euphrates waters and in soils and tree barks of Dhi Qar province (southern Iraq)

International Nuclear Information System (INIS)

Riccobono, Francesco; Perra, Guido; Pisani, Anastasia; Protano, Giuseppe

2011-01-01

To assess the quality of the environment in southern Iraq after the Gulf War II, a geochemical survey was carried out. The survey provided data on the chemistry of Euphrates waters, as well as the trace element contents, U and Pb isotopic composition, and PAH levels in soil and tree bark samples. The trace element concentrations and the 235 U/ 238 U ratio values in the Euphrates waters were within the usual natural range, except for the high contents of Sr due to a widespread presence of gypsum in soils of this area. The trace element contents in soils agreed with the common geochemistry of soils from floodplain sediments. Some exceptions were the high contents of Co, Cr and Ni, which had a natural origin related to ophiolitic outcrops in the upper sector of the Euphrates basin. The high concentrations of S and Sr were linked to the abundance of gypsum in soils. A marked geochemical homogeneity of soil samples was suggested by the similar distribution pattern of rare earth elements, while the 235 U/ 238 U ratio was also fairly homogeneous and within the natural range. The chemistry of the tree bark samples closely reflected that of the soils, with some notable exceptions. Unlike the soils, some tree bark samples had anomalous values of the 235 U/ 238 U ratio due to mixing of depleted uranium (DU) with the natural uranium pool. Moreover, the distribution of some trace elements (such as REEs, Th and Zr) and the isotopic composition of Pb in barks clearly differed from those of the nearby soils. The overall results suggested that significant external inputs occurred implying that once formed the DU-enriched particles could travel over long distances. The polycyclic aromatic hydrocarbon concentrations in tree bark samples showed that phenanthrene, fluoranthene and pyrene were the most abundant components, indicating an important role of automotive traffic. - Highlights: → This is a contribution to the knowledge of the Iraqi environment after Gulf War II. → In

Measurements of the neutron-induced fission cross sections of 240Pu and 242Pu relative to 235U

International Nuclear Information System (INIS)

Behrens, J.W.; Browne, J.C.; Carlson, G.W.

1976-01-01

A continuation is given of the fission-cross-section ratio measurements in progress at the Lawrence Livermore Laboratory. Preliminary results are provided for the 240 Pu/ 235 U and 242 Pu/ 235 U ratios from 0.02 to 30 MeV and 0.1 to 30 MeV, respectively. Using the threshold-cross-section method, the ratios were normalized to the values 1.368 +- 0.030 and 1.116 +- 0.025, respectively, from 1.75 to 4.00 MeV

Determination of uranium isotopes ({sup 235}U, {sup 238}U) and trace elements (Cd, Pb, Cu and As) in bottled drinking water by Icp-SFMS; Determinacion de isotopos de uranio ({sup 235}U, {sup 238}U) y elementos traza (Cd, Pb, Cu y As) en agua embotellada para beber por ICP-SFMS

Energy Technology Data Exchange (ETDEWEB)

Lara A, N.; Hernandez M, H.; Romero G, E. T.; Kuri de la C, A.; Perez B, M. A., E-mail: nancy.lara@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2016-09-15

In the present work we propose an optimized method for the quantification of uranium isotopes ({sup 235}U, 2{sup 38}U) and the elements Cd, Pb, Cu and As in bottled water for drinking at trace levels of concentration. Based on the multi-element detection capability, the high sensitivity and resolution that the Mass Spectrometry with Magnetic Sector with Inductively Coupled Plasma Source (Icp-SFMS) technique offers; the high, medium and low resolution analysis conditions for the elements under study were established and optimized using and Element 2/Xr equipment and the 23 multi-elemental Certified Reference Material (CRM). The analysis method was validated using the standard reference material Nist 1643d and CRM mono-elemental s as external standards for the quantification of the analytes. Samples, targets and CRM were acidified with 2% of HNO{sub 3} and analyzed without pretreatment under the established analysis conditions. The results obtained show concentrations of {sup 235}U, {sup 238}U, {sup 111}Cd, {sup 208}Pb, {sup 63}Cu and {sup 75}As in the range of μg L{sup -1}, the linearity obtained from the calibration curves for each element has correlation coefficients < 0.99 in all cases, the accuracy of the method in terms of percent relative standard deviation (RSD %) was less than 5%, the mean recovery rate of Nist 1643d ranged from 96.46% to 101.12%. The optimization of the method guarantees the stability and calibration of the equipment throughout the analysis, as well as the ability to resolve interferences. In conclusion, the method proposed using Icp-SFMS offers the advantages of being fast and simple for the multi-elemental analysis in water at trace levels, with low limits of quantification and detection, with good linearity, accuracy, precision and reproducibility to a degree of reliability of 95%. (Author)

Reich-Moore and Adler-Adler representations of the 235U cross sections in the resolved resonance region

International Nuclear Information System (INIS)

Saussure, G. de; Leal, L.C.; Perez, R.B.

1990-01-01

In the first part of this paper, a reevaluation of the low-energy neutron cross sections of 235 U is described. This reevaluation was motivated by the discrepancy between the measured and computed temperature coefficients of reactivity and is based on recent measurements of the fission cross section and of η in the thermal and subthermal neutron energy regions. In the second part of the paper, we discuss the conversion of the Reich-Moore resonance parameters, describing the neutron cross sections of 235 U in the resolved resonance region, into equivalent Adler-Adler resonance parameters and into equivalent momentum space multipole resonance parameters

Quantum Zeno paradox and decay of the 235m U isomer in matter

International Nuclear Information System (INIS)

Panov, A.D.

1995-01-01

The known quantum Zeno paradox is considered from microscopic viewpoint as applied to observation of nuclear decay. It is shown that some phenomena, related with this paradox can produce sufficient effect on the constant of 235m U isomer decay during its implantation in metallic matrices. 43 refs., 3 figs

Absolute values of neutrino masses: status and prospects

International Nuclear Information System (INIS)

Bilenky, S.M.; Giunti, C.; Grifols, J.A.; Masso, E.

2003-01-01

Compelling evidences in favor of neutrino masses and mixing obtained in the last years in Super-Kamiokande, SNO, KamLAND and other neutrino experiments made the physics of massive and mixed neutrinos a frontier field of research in particle physics and astrophysics. There are many open problems in this new field. In this review we consider the problem of the absolute values of neutrino masses, which apparently is the most difficult one from the experimental point of view. We discuss the present limits and the future prospects of β-decay neutrino mass measurements and neutrinoless double-β decay. We consider the important problem of the calculation of nuclear matrix elements of neutrinoless double-β decay and discuss the possibility to check the results of different model calculations of the nuclear matrix elements through their comparison with the experimental data. We discuss the upper bound of the total mass of neutrinos that was obtained recently from the data of the 2dF Galaxy Redshift Survey and other cosmological data and we discuss future prospects of the cosmological measurements of the total mass of neutrinos. We discuss also the possibility to obtain information on neutrino masses from the observation of the ultra high-energy cosmic rays (beyond the GZK cutoff). Finally, we review the main aspects of the physics of core-collapse supernovae, the limits on the absolute values of neutrino masses from the observation of SN1987A neutrinos and the future prospects of supernova neutrino detection

Candidate processes for diluting the 235U isotope in weapons-capable highly enriched uranium

International Nuclear Information System (INIS)

Snider, J.D.

1996-02-01

The United States Department of Energy (DOE) is evaluating options for rendering its surplus inventories of highly enriched uranium (HEU) incapable of being used to produce nuclear weapons. Weapons-capable HEU was earlier produced by enriching uranium in the fissile 235 U isotope from its natural occurring 0.71 percent isotopic concentration to at least 20 percent isotopic concentration. Now, by diluting its concentration of the fissile 235 U isotope in a uranium blending process, the weapons capability of HEU can be eliminated in a manner that is reversible only through isotope enrichment, and therefore, highly resistant to proliferation. To the extent that can be economically and technically justified, the down-blended uranium product will be made suitable for use as commercial reactor fuel. Such down-blended uranium product can also be disposed of as waste if chemical or isotopic impurities preclude its use as reactor fuel

Multilevel fitting of 235U resonance data sensitive to Bohr-and Brosa-fission channels

International Nuclear Information System (INIS)

Moore, M.S.

1995-01-01

The recent determination of the K, J dependence of the neutron induced fission cross section of 235 U by the Dubna group has led to a renewed interest in the mechanism of fission from saddle to scission. The K quantum numbers designate the so-called Bohr fission channels, which describe the fission properties at the saddle point. Certain other fission properties, e.g., the fragment mass and kinetic-energy distribution, are related to the properties of the scission point. The neutron energy dependence of the fragment kinetic energies has been measured by Hambsch et al., who analyzed their data according to a channel description of Brosa et al. How these two channel descriptions, the saddle-point Bohr channels and the scission-point Brosa channels, relate to one another is an open question, and is the subject matter of the present paper. We use the correlation coefficient between various data sets, in which variations are reported from resonance to resonance, as a measure of both-the statistical reliability of the data and of the degree to which different scission variables relate to different Bohr channels. We have carried out an adjustment of the ENDF/B-VI multilevel evaluation of the fission cross section of 235 U, one that provides a reasonably good fit to the energy dependence of the fission, capture, and total cross sections below 100 eV, and to the Bohr-channel structure deduced from an earlier measurement by Pattenden and Postma. We have also further explored the possibility of describing the data of Hambsch et al. in the Brosa-channel framework with the same set of fission-width vectors, only in a different reference system. While this approach shows promise, it is clear that better data are also needed for the neutron energy variation of the scission-point variables

Analysis of the angular distributions of elastically scattered neutrons for 235U

International Nuclear Information System (INIS)

Sukhovitskij, E.Sh.; Benderskij, A.R.; Konshin, V.A.

1976-01-01

Experimental data on the angular distributions of 0.5-15 MeV neutrons elastically scattered by 235 U nuclei are analysed on the basis of Bessel functions and Legendre polynomial expansions. The advantages of the method are that there are no negative cross-sections and relatively few expansion coefficients and that experimental data on scattering at 0 0 and 180 0 are not needed. (author)

Reich-Moore and Adler-Adler representations of the 235U cross sections in the resolved resonance region

International Nuclear Information System (INIS)

de Saussure, G.; Leal, L.C.; Perez, R.B.

1990-01-01

In the first part of this paper, a reevaluation of the low-energy neutron cross sections of 235 U is described. This reevaluation was motivated by the discrepancy between the measured and computed temperature coefficients of reactivity and is based on recent measurements of the fission cross section and of η in the thermal and subthermal neutron energy regions. In the second part of the paper, we discuss the conversion of the Reich-Moore resonance parameters, describing the neutron cross sections of 235 U in the resolved resonance region, into equivalent Adler-Adler resonance parameters and into equivalent momentum space multipole resonance parameters. 25 refs., 4 figs., 5 tabs

Prompt neutron decay constant for the Oak Ridge Research Reactor with 20 wt % 235U enriched fuel

International Nuclear Information System (INIS)

Ragan, G.E.; Mihalczo, J.T.

1986-01-01

This paper describes measurements of the prompt neutron decay constant at delayed criticality for the Oak Ridge Research Reactor (ORR) using 20 wt % 235 U enriched fuel and compares these measurements with similar measurements using 93.2 wt % 235 U enriched fuel. This reactor parameter is of interest because it affects the transient behavior of the reactor in prompt criticality accident situations. This experiment is part of a program to investigate the differences in the performance of research reactors fueled with highly enriched and low enriched uranium. The prompt neutron decay constants were obtained using noise analysis measurement techniques for a core with newly fabricated, unirradiated fuel elements

Development and evaluation of a collection apparatus for recoil products for study of the deexcitation process of "2"3"5"mU

International Nuclear Information System (INIS)

Shigekawa, Y.; Kasamatsu, Y.; Shinohara, A.

2016-01-01

The nucleus "2"3"5"mU is an isomer with extremely low excitation energy (76.8 eV) and decays dominantly through the internal conversion (IC) process. Because outer-shell electrons are involved in the IC process, the decay constant of "2"3"5"mU depends on its chemical environment. We plan to study the deexcitation process of "2"3"5"mU by measuring the energy spectra of IC electrons in addition to the decay constants for various chemical forms. In this paper, the preparation method of "2"3"5"mU samples from "2"3"9Pu by using alpha-recoil energy is reported. A Collection Apparatus for Recoil Products was fabricated, and then collection efficiencies under various conditions were determined by collecting "2"2"4Ra recoiling out of "2"2"8Th electrodeposited and precipitated sources. The pressure in the apparatus (vacuum or 1 atm of N_2 gas) affected the variations of the collection efficiencies depending on the negative voltage applied to the collector. The maximum values of the collection efficiencies were mainly affected by the thickness of the "2"2"8Th sources. From these results, the suitable conditions of the "2"3"9Pu sources for preparation of "2"3"5"mU were determined. In addition, dissolution efficiencies were determined by washing collected "2"2"4Ra with solutions. When "2"2"4Ra was collected in 1 atm of N_2 gas and dissolved with polar solutions such as water, the dissolution efficiencies were nearly 100%. The method of rapid dissolution of recoil products would be applicable to rapid preparation of short-lived "2"3"5"mU samples for various chemical forms.

Alecto - results obtained with homogeneous critical experiments on plutonium 239, uranium 235 and uranium 233

International Nuclear Information System (INIS)

Bruna, J.G.; Brunet, J.P.; Caizegues, R.; Clouet d'Orval, Ch.; Kremser, J.; Tellier, H.; Verriere, Ph.

1965-01-01

In this report are given the results of the homogeneous critical experiments ALECTO, made on plutonium 239, uranium 235 and uranium 233. After a brief description of the equipment, the critical masses for cylinders of diameters varying from 25 to 42 cm, are given and compared with other values (foreign results, criticality guide). With respect to the specific conditions of neutron reflection in the ALECTO experiments the minimal values of critical masses are: Pu239 M c = 910 ± 10 g, U235 M c = 1180 ± 12 g and U233 M c = 960 ± 10 g. Experiments relating to cross sections and constants to be used on these materials are presented. Lastly, kinetic experiments allow to compare pulsed neutron methods to fluctuation methods [fr

Exploratory study of fission product yields of neutron-induced fission of 235U , 238U , and 239Pu at 8.9 MeV

Science.gov (United States)

Bhatia, C.; Fallin, B. F.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; Arnold, C. W.; Bond, E.; Bredeweg, T. A.; Fowler, M. M.; Moody, W.; Rundberg, R. S.; Rusev, G. Y.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

2015-06-01

Using dual-fission chambers each loaded with a thick (200 -400 -mg /c m2) actinide target of 235 ,238U or 239Pu and two thin (˜10 -100 -μ g /c m2) reference foils of the same actinide, the cumulative yields of fission products ranging from 92Sr to 147Nd have been measured at En= 8.9 MeV . The 2H(d ,n ) 3He reaction provided the quasimonoenergetic neutron beam. The experimental setup and methods used to determine the fission product yield (FPY) are described, and results for typically eight high-yield fission products are presented. Our FPYs for 235U(n ,f ) , 238U(n ,f ) , and 239Pu(n ,f ) at 8.9 MeV are compared with the existing data below 8 MeV from Glendenin et al. [Phys. Rev. C 24, 2600 (1981), 10.1103/PhysRevC.24.2600], Nagy et al. [Phys. Rev. C 17, 163 (1978), 10.1103/PhysRevC.17.163], Gindler et al. [Phys. Rev. C 27, 2058 (1983), 10.1103/PhysRevC.27.2058], and those of Mac Innes et al. [Nucl. Data Sheets 112, 3135 (2011), 10.1016/j.nds.2011.11.009] and Laurec et al. [Nucl. Data Sheets 111, 2965 (2010), 10.1016/j.nds.2010.11.004] at 14.5 and 14.7 MeV, respectively. This comparison indicates a negative slope for the energy dependence of most fission product yields obtained from 235U and 239Pu , whereas for 238U the slope issue remains unsettled.

Beta and gamma decay heat evaluation for the thermal fission of 235U

International Nuclear Information System (INIS)

Schenter, G.K.; Schmittroth, F.

1979-01-01

Beta and gamma fission product decay heat curves are evaluated for the thermal fission of 235 U. Experimental data that include beta, gamma, and total measurements are combined with summation calculations based on ENDF/B in a consistent evaluation. Least-squares methods are used that take proper account of data uncertainties and correlations. 4 figures, 2 tables

Criticality study of the storage of radioactive waste containing 235U

International Nuclear Information System (INIS)

Couasnon, O.

1999-01-01

The purpose of this study is to define the conditions of storage of nuclear waste drums containing 350 g of 235 U (per drum). This study is valid for a square pitch stacking of cylindrical drums whose height/diameter ratio does not exceed 3. The reflector effect of concrete is taken into account. This study defines a conservative case that can be used under any hypothesis of moderation, of radiation coupling between drums and of fissile material density. (A.C.)

(e,e'f) coincidence experiments for fission decay of giant resonances in 235,238U

International Nuclear Information System (INIS)

Weber, T.; Heil, R.D.; Kneissl, U.; Pecho, W.; Wilke, W.; Emrich, H.J.; Kihm, T.; Knoepfle, K.T.

1988-01-01

Extending previous work on 238 U, 235 U(e,e'f) coincidence data were taken at 4 momentum transfers yielding both E1, E2/E0 and E3 form factors and the respective multipole strength distributions in the giant resonance region of 238 U (4 x x /Γ a is obtained as a function of excitation energy for separated multipoles. The giant E2 resonance exhibits an increased symmetric fission contribution compared to E1 and E3 resonances. (orig.)

Minimum critical masses for uranium at the Portsmouth Gaseous Diffusion Plant

International Nuclear Information System (INIS)

Tayloe, R.W. Jr.; Davis, T.C.

1994-06-01

This report presents a tabulation of safe masses and minimum critical masses for uranium (U). These minimum critical mass and safe mass tables were obtained by interpolating between the values reported in the literature to obtain values as a function of enrichment within the 1.5 percent to 100 percent range. Equivalent mass values for uranium-235 (U 235 ), uranium hexafluoride (UF 6 ), and uranyl fluoride (UO 2 F 2 ) have been generated from the safe mass and minimum critical masses for uranium

Effect of U-238 and U-235 cross sections on nuclear characteristics of fast and thermal reactors

Energy Technology Data Exchange (ETDEWEB)

Akie, Hiroshi; Takano, Hideki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kaneko, Kunio

1997-03-01

Benchmark calculation has been made for fast and thermal reactors by using ENDF/B-VI release 2(ENDF/B-VI.2) and JENDL-3.2 nuclear data. Effective multiplication factors (k{sub eff}s) calculated for fast reactors calculated with ENDF/B-VI.2 becomes about 1% larger than the results with JENDL-3.2. The difference in k{sub eff} is caused mainly from the difference in inelastic scattering cross section of U-238. In all thermal benchmark cores, ENDF/B-VI.2 gives smaller multiplication factors than JENDL-3.2. In U-235 cores, the difference is about 0.3%dk and it becomes about 0.6% in TCA U cores. The difference in U-238 data is also important in thermal reactors, while there are found 0.1-0.3% different v values of U isotopes in thermal energy between ENDF/B-VI.2 and JENDL-3.2. (author)

Thallium, uranium, and 235U/238U ratios in the digestive gland of American lobster (Homarus americanus) from an industrialized harbor

International Nuclear Information System (INIS)

Chou, C.L.; Uthe, J.F.

1995-01-01

Only a few studies have concentrated on elements such as thallium (TI). Uranium (U) has been studied as a radionuclide of concern in food and the environment. Foodstuffs contain 10-100 ng U· -1 with vegetables and cereals contributing most heavily to the daily intake of ca 1.5 ug U. Between 10-30% of ingested U is absorbed, with most being stored in bone. Rainbow trout (onchorynchus mykiss) and longnose sucker (Catostomus catostomus) from a lake with naturally high radioactivity contained -1 in the flesh. Trout bone contained 40 ng U·g -1 . Higher tissue U concentrations occurred in fish from areas receiving U mining wastes. Bioconcentration factors for bone and flesh were estimated to be low, 118 and 14.7, respectively. This paper describes the Inductively coupled plasma-mass spectrometry (ICP-MS) determination of Tl and U in digestive gland tissue from lobsters captured in the vicinity of Belledune Harbor, New Brunswick, Canada. The harbor is the site of a lead smelter, a fertilizer plant, and a coal-fired power station (the latter due to enter production in late 1993) and thus has the potential of adding significant amounts of Tl to the local marine environment. The accumulation of Tl from water by marine shellfish is low, at least for bivalves, and the accumulated Tl is eliminated in a number of days when the animals are transferred to clean water. Bioconcentration factors for U in finfish ranged from 0.4-17 for larger species. However, because of the high concentrations of various trace elements in lobster digestive gland, its desirability as a foodstuff, and its relatively large size (approximately 20% of the edible tissue yield), we have investigated Tl and U concentrations and 235U / 238U ratios in it. 15 refs., 1 fig., 3 tabs

Dicty_cDB: AFF235 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available AF (Link to library) AFF235 (Link to dictyBase) - - - - AFF235F (Link to Original s...ite) AFF235F 602 - - - - - - Show AFF235 Library AF (Link to library) Clone ID AFF235 (Link to dictyBase) Atlas ID - NBRP ID - dict...yBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/...date 2001.11.24 Homology vs DNA Score E Sequences producing significant alignments: (bits) Value N U36937 |U36937.1 Dict... 3 CK420742 |CK420742.1 AUF_IpTrk_27_j08 Trunk kidney cDNA library Ictalurus punctatus cDNA 5' similar to ER

Evaluation of covariances for resolved resonance parameters of 235U, 238U, and 239Pu in JENDL-3.2

International Nuclear Information System (INIS)

Kawano, Toshihiko; Shibata, Keiichi

2003-02-01

Evaluation of covariances for resolved resonance parameters of 235 U, 238 U, and 239 Pu was carried out. Although a large number of resolved resonances are observed for major actinides, uncertainties in averaged cross sections are more important than those in resonance parameters in reactor calculations. We developed a simple method which derives a covariance matrix for the resolved resonance parameters from uncertainties in the averaged cross sections. The method was adopted to evaluate the covariance data for some important actinides, and the results were compiled in the JENDL-3.2 covariance file. (author)

Proposal for Analysis of the Safeguarded Nuclear Materials 235U and 239Pu by Delayed Neutrons Technique

International Nuclear Information System (INIS)

El-Mongy, S.A.

2000-01-01

This paper introduces, describes and initiates a very sensitive and rapid non-destructive technique to be used for analysis of the safeguarded nuclear materials 235 U and 239 Pu. The technique is based on fission of the nuclear material by neutrons and then measuring the delayed neutrons produced from the neutron rich fission products. By this technique, fissile isotope content ( 235 U) can be determined in the presence of the other fissile (e.g. 239 Pu) or fertile isotopes (e.g. 238 U) in fresh and spent fuel. The time consumed for analysis of bulk materials by this technique is only 4 minutes. The method is also used for analysis of uranium in rock, sediment, soil, meteorites, lunar, biological, urine, archaeological, zircon sand and seawater samples. The method enables uranium in a sample to be measured without respect to its oxidation state, organic and inorganic elements

Energy dependence of average half-life of delayed neutron precursors in fast neutron induced fission of 235U and 236U

International Nuclear Information System (INIS)

Isaev, S.G.; Piksaikin, L.E.; Kazakov, L.E.; Tarasko, M.Z.

2000-01-01

The measurements of relative abundances and periods of delayed neutrons from fast neutron induced fission of 235 U and 236 U have been made at the electrostatic accelerator CG-2.5 at IPPE. The preliminary results were obtained and discussed in the frame of the systematics of the average half-life of delayed neutron precursors. It was shown that the average half-life value in both reactions depends on the energy of primary neutrons [ru

Fission cross sections of {sup 235,238}U and {sup 209}Bi at incident proton energies above 70 MeV

Energy Technology Data Exchange (ETDEWEB)

Obukhov, A I; Rimskij-Korsakov, A A; Eismont, V P [V.G. Khlopin Radium Inst., St. Petersburg (Russian Federation)

1997-06-01

The proton fission cross-section data of {sup 235,238}U and Bi were measured in the V.G. Khlopin Radium Institute over a wide proton energy range. The experimental and calculated data were also compared with experimental neutron values. The proton cross-section of {sup 235,238}U increased up to 60-70 MeV and then decreased. The bismuth proton fission cross-section increased in line with the rise in proton energy up to 1 GeV. (author). 21 refs, 6 figs.

Spectral Irradiance Calibration in the Infrared. XIV: the Absolute Calibration of 2MASS

OpenAIRE

Cohen, Martin; Wheaton, Wm. A.; Megeath, S. T.

2003-01-01

Element-by-element we have combined the optical components in the three 2MASS cameras, and incorporated detector quantum efficiency curves and site-specific atmospheric transmissions, to create three relative spectral response curves (RSRs). We provide absolute 2MASS attributes associated with "zero magnitude" in the JHKs bands so that these RSRs may be used for synthetic photometry. The RSRs tie 2MASS to the Cohen-Walker-Witteborn framework of absolute photometry and spectra for the purpose ...

Use of proportional gas scintillator in absolute measurements of alpha-gamma emitter activities

International Nuclear Information System (INIS)

Tobias, C.C.B.

1987-01-01

The absolute activity of U-235 contained in a U 3 O 8 sample was measured utilizing a sum-coincidence circuit which selects only the alpha particles which are simultaneous with the 143 KeV and 186 KeV gamma radiations from the Th-231 (product nucleus). The alpha particles were detected by means of a new type of a gas scintillating chamber, in which the light emitted by excitation of the gas atoms, due to the passage of a charged incoming particle, has its intensity increased by the action of an applied electric field. The gamma radiations were detected by means of a NaI(Tl) 1'' x 1 1/2'' scintillation detector. The value obtained for the half-life of U-235 was compared with the data available from various observers which used different experimental techniques. It is shown tht the results, are in excellent agreement with the best international data available on the subject and that, therefore, the sum-coincidence technique constitutes an important method for such measurements. (Author) [pt

Fission cross section of 235U from 1 to 6 MeV

International Nuclear Information System (INIS)

Barton, D.M.; Diven, B.C.; Hansen, G.E.; Jarvis, G.A.; Koontz, P.G.; Smith, R.K.

1976-01-01

The ratio of the neutron-induced fission cross section of 235 U to the neutron-proton scattering cross section was measured in the neutron energy region from 1 to 6 MeV. The neutron source was the T(p,n) reaction produced by a pulsed Van de Graaff proton beam on a thin tritium gas target. The use of monoenergetic neutrons allowed time-of-flight methods to be used to study carefully backgrounds and source characteristics

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

International Nuclear Information System (INIS)

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

1980-09-01

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

Contribution to the study of the thermal fission process for uranium 235 (1964); Contribution a l'etude du processus de la fission thermique de l'uranium 235 (1964)

Energy Technology Data Exchange (ETDEWEB)

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

1963-12-15

This report deals with the study of the distribution of the masses of the fragments produced by the disintegration of the U-236 nucleus, formed when a U-235 nucleus captures a thermal neutron. The experimental method chosen consists in the simultaneous measurement using p-n silicon junction detectors of the energies of the two fragments emitted in coincidence. This measurement is first made by a conditioned analysis of the energy of one of the fragments and then by a two dimensional analysis of the energies of the two fragments. Systematic results, are obtained concerning the distribution of the masses for different values of the total kinetic energy. The five structures appearing both for the mass distributions and for the energies of the fragments are studied and discussed. Generally speaking, our results are in agreement with those obtained by the time-of-flight method. (author) [French] Le present rapport a pour objet t'etude de la distribution des masses des fragments emis lors de la fission du noyau U-236, forme par capture d'un neutron thermique par un noyau d'U-235. La methode experimentale choisie consiste en la mesure simultanee - a l'aide de detecteurs a jonction p-n au silicium des energies des deux fragments emis en coincidence. Cette mesure est d'abord effectuee par analyse conditionnee de l'energie de l'un des fragments puis par analyse bidimensionnelle des energies des deux fragments. Des resultats systematiques sont obtenus sur les distributions des masses pour differentes valeurs de l'energie cinetique totale. Les 'structures fines' apparaissant tant sur les distributions des masses que sur celles des energies des fragments sont egalement etudiees et discutees. D'une facon generale, nos resultats sont en accord avec ceux obtenus par la methode du temps de vol. (auteur)

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

Science.gov (United States)

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

2017-07-01

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

n+235U resonance parameters and neutron multiplicities in the energy region below 100 eV

Directory of Open Access Journals (Sweden)

Pigni Marco T.

2017-01-01

Full Text Available In August 2016, following the recent effort within the Collaborative International Evaluated Library Organization (CIELO pilot project to improve the neutron cross sections of 235U, Oak Ridge National Laboratory (ORNL collaborated with the International Atomic Energy Agency (IAEA to release a resonance parameter evaluation. This evaluation restores the performance of the evaluated cross sections for the thermal- and above-thermal-solution benchmarks on the basis of newly evaluated thermal neutron constants (TNCs and thermal prompt fission neutron spectra (PFNS. Performed with support from the US Nuclear Criticality Safety Program (NCSP in an effort to provide the highest fidelity general purpose nuclear database for nuclear criticality applications, the resonance parameter evaluation was submitted as an ENDF-compatible file to be part of the next release of the ENDF/B-VIII.0 nuclear data library. The resonance parameter evaluation methodology used the Reich-Moore approximation of the R-matrix formalism implemented in the code SAMMY to fit the available time-of-flight (TOF measured data for the thermal induced cross section of n+235U up to 100 eV. While maintaining reasonably good agreement with the experimental data, the validation analysis focused on restoring the benchmark performance for 235U solutions by combining changes to the resonance parameters and to the prompt resonance v̅ below 100 eV.

Quantification of 235 U and 226 Ra in soil samples by means of Gamma spectroscopy

International Nuclear Information System (INIS)

Quintero P, E.; Rojas M, V.P.; Montes M, F.R.; Gaso P, M.I.; Cervantes N, M.L.

2000-01-01

In this work it is presented the Gamma Spectroscopy method which is realized in the Environmental Radiological Surveillance Laboratory using the option of deconvolution of a commercial software for the quantification of 235 U and 226 Ra; also is presented the method for the 226 Ra correction activity. (Author)

Masses and K-line absolute magnitudes of γ Leonis and 35 Comae

International Nuclear Information System (INIS)

Deming, D.; Dykton, M.

1979-01-01

The visual binary system γ Leonis consists of two K giants whose total mass was found by Wilson to be less than 0.6M/sub sun/ when a distance was obtained from K-line absolute magnitudes of both components. Since the orbital period of the system is of order 600 years, the orbital solution has usually been regarded as the most likely explanation of the anomalous mass. We have investigated the uniqueness of the orbital solution. We find that the individual orbital elements are only poorly determined, but that a 3 /P 2 is known to within +- 10%. The anomalous mass of this binary system implies either extensive mass-loss or the need for revisions in the K-line absolute magnitudes. We also investigate the binary system 35 Comae. Wilson has noted that in this system the K-line absolute magnitude of the G8 III primary component implies a total mass of 8 M/sub sun/. However the A component of 35 Comae is not sufficiently luminous to justify such a large total mass. The system has a period of order 700 years, and the uniqueness of the orbital solution is therefore suspect. However, in this case also we have investigated the uniqueness of the orbital solution and find that individual orbital elements are poorly determined, but that a 3 /P 2 is known to within +- 17%. We point out that 35 Comae is known to be very metal rich, in contrast to γ Leonis which is metal poor. We conclude that a composition-dependent correction to the K-line absolute magnitudes provides the simplest explanation of these mass anomalies. Such a correction would also give better agreement with the trigonometric parallaxes of these binary systems

The fission cross sections of /sup 230/Th, /sup 232/Th, /sup 233/U, /sup 234/U, /sup 236/U, /sup 238/U, /sup 237/Np, /sup 239/Pu and /sup 242/Pu relative /sup 235/U at 14. 74 MeV neutron energy

Energy Technology Data Exchange (ETDEWEB)

Meadows, J.W.

1986-12-01

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

Beta and gamma decay heat measurements between 0.1s--50,000s for neutron fission of 235U, 238U and 239Pu

International Nuclear Information System (INIS)

Schier, W.A.; Couchell, G.P.

1993-01-01

A helium-jet/tape-transport system is employed in the study of beta-particle and gamma-ray energy spectra of aggregate fission products as a function of time after fission. During the initial nine months of this project we have investigated the following areas: Design, assembly and characterization of a beta-particle spectrometer; Measurement of 235 U(n th ff) beta spectra for delay times 0.2 s to 12,000 s; Assembly and characterization of a 5 x 5 Nal(Tl) gamma-ray spectrometer; Measurement of 235 U(n th ff) gamma-ray spectra for delay times 0.2s to 1 5,500s; Assembly and characterization of HPGe gamma-ray spectrometer with a Nal(Tl) Compton-and-background-suppression annulus; Measurement of 235 U(n th ,ff) high-resolution gamma-ray spectra for delay times 0.6 s to over 100,000 s; Comparison of individual gamma-line intensities with ENDF/B-VI; Adaptation to our computer of unfolding program FERDO for beta and gamma aggregate fission-product energy spectra and development of a spectrum-stripping program for analysis of HPGe gamma-ray spectra; Study of the helium-jet fission-fragment elemental transfer efficiency. This work has resulted in the publication of twelve BAPS abstracts of presentations at scientific meetings. There are currently four Ph.D. and two M.S. candidates working on dissertations associated with the project

Measurement of 235U enrichment with a LaBr3 scintillation detector

International Nuclear Information System (INIS)

Mortreau, P.; Berndt, R.

2010-01-01

This paper describes the performance of a 1.5 in.x1.5 in. LaBr 3 gamma radiation detector for determining 235 U enrichment by non-destructive analysis. The spectrometric properties of the detector, brought to market under the trade name BrillanCe-380 , were first evaluated. Enrichment measurements were subsequently carried out in different experimental conditions on certified uranium samples with enrichment ranging from 0.31% to 60% and on UF 6 containers of the type 30B and 48Y.

Measurement of 235U content and flow of UF6 using delayed neutrons or gamma rays following induced fission

International Nuclear Information System (INIS)

Stromswold, D.C.; Peurrung, A.J.; Reeder, P.L.; Perkins, R.W.

1996-06-01

Feasibility experiments conducted at Pacific Northwest National Laboratory demonstrate that either delayed neutrons or energetic gamma rays from short-lived fission products can be used to monitor the blending of UF 6 gas streams. A 252 Cf neutron source was used to induce 235 U fission in a sample, and delayed neutrons and gamma rays were measured after the sample moved open-quotes down-stream.close quotes The experiments used a UO 2 powder that was transported down the pipe to simulate the flowing UF 6 gas. Computer modeling and analytic calculation extended the test results to a flowing UF 6 gas system. Neutron or gamma-ray measurements made at two downstream positions can be used to indicate both the 235 U content and UF 6 flow rate. Both the neutron and gamma-ray techniques have the benefits of simplicity and long-term reliability, combined with adequate sensitivity for low-intrusion monitoring of the blending process. Alternatively, measuring the neutron emission rate from (a, n) reactions in the UF 6 provides an approximate measure of the 235 U content without using a neutron source to induce fission

Beta and gamma decay heat measurements between 0.1s--50,000s for neutron fission of 235U, 238U and 239Pu. Final report, June 1, 1992--December 31, 1996

International Nuclear Information System (INIS)

Schier, W.A.; Couchell, G.P.

1996-01-01

This is a final reporting on the composition of separate beta and gamma decay heat measurements following neutron fission of 235 U and 238 U and 239 Pu and on cumulative and independent yield measurements of fission products of 235 U and 238 U. What made these studies unique was the very short time of 0.1 s after fission that could be achieved by incorporating the helium jet and tape transport system as the technique for transporting fission fragments from the neutron environment of the fission chamber to the low-background environment of the counting area. This capability allowed for the first time decay heat measurements to extend nearly two decades lower on the logarithmic delay time scale, a region where no comprehensive aggregate decay heat measurements had extended to. This short delay time capability also allowed the measurement of individual fission products with half lives as short as 0.2s. The purpose of such studies was to provide tests both at the aggregate level and at the individual nuclide level of the nation's evaluated nuclear data file associated with fission, ENDF/B-VI. The results of these tests are in general quite encouraging indicating this data base generally predicts correctly the aggregate beta and aggregate gamma decay heat as a function of delay time for 235 U, 238 U and 239 Pu. Agreement with the measured individual nuclide cumulative and independent yields for fission products of 235 U and 238 U was also quite good although the present measurements suggest needed improvements in several individual cases

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

Energy Technology Data Exchange (ETDEWEB)

Meadows, J W

1983-10-01

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

Decay heat of 235U fission products by beta- and gamma-ray spectrometry

International Nuclear Information System (INIS)

Dickens, J.K.; Love, T.A.; McConnell, J.W.; Peelle, R.W.

1976-09-01

The fast-rabbit facilities of the ORRR were used to irradiate 1- to 10-μg samples of 235 U for 1, 10, and 100 s. Released power is observed using nuclear spectroscopy to permit separate observations of emitted β and γ spectra in successive time intervals. The spectra were integrated over energy to obtain total decay heat and the β- and γ-ray results are summed together. 10 fig, 2 tables

Quantification of {sup 235} U and {sup 226} Ra in soil samples by means of Gamma spectroscopy; Cuantificacion de {sup 235} U y {sup 226} Ra en muestras de suelo por medio de espectrometria gamma

Energy Technology Data Exchange (ETDEWEB)

Quintero P, E.; Rojas M, V.P.; Montes M, F.R.; Gaso P, M.I.; Cervantes N, M.L. [Gerencia de Innovacion Tecnologica, A.P. 18-1027, C.P. 11801 Mexico D.F. (Mexico)

2000-07-01

In this work it is presented the Gamma Spectroscopy method which is realized in the Environmental Radiological Surveillance Laboratory using the option of deconvolution of a commercial software for the quantification of {sup 235} U and {sup 226} Ra; also is presented the method for the {sup 226} Ra correction activity. (Author)

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

Energy Technology Data Exchange (ETDEWEB)

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

1998-11-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1955-07-01

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

48 CFR 252.235-7002 - Animal welfare.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Animal welfare. 252.235... Clauses 252.235-7002 Animal welfare. As prescribed in 235.072(a), use the following clause: Animal Welfare... animals only from dealers licensed by the Secretary of Agriculture under 7 U.S.C. 2133 and 9 CFR subpart A...

Development of a rapid radiochemical procedure for the separation of /sup 235m/U from 239Pu

International Nuclear Information System (INIS)

Attrep, M. Jr.; Efurd, D.W.; Roensch, F.R.

1987-01-01

We have developed a rapid radiochemical procedure for the isolation and purification of /sup 235m/U (t/sub 1/2/ = 26 minutes) from 239 Pu samples up to 250 mg. Purpose of developing the procedure was to measure the thermal neutron fission cross section of the isomeric meta state of 235 U. We used rapid small-scale anion exchange columns that absorbed uranium in concentrated HBr but did not absorb plutonium. Uranium was easily eluted with very dilute HF. The separation time required 25 to 35 minutes. We were able to attain a separation factor of uranium from plutonium of approximately 1 x 10 10 with samples ranging from 1 x 10 10 to 3 x 10 11 . The ratio of the fission cross sections for the meta to ground state was measured to be 1.42. 4 figs., 1 tab

Fission-fragment angular distributions and total kinetic energies for 235U(n,f) from .18 to 8.83 MeV

International Nuclear Information System (INIS)

Meadows, J.W.; Budtz-Joergensen, C.

1982-01-01

A gridded ion chamber was used to measure the fission fragment angular distribution and total kinetic energy for the 235 U(n,f) reaction from 0.18 to 8.81 MeV neutron energy. The anisotropies are in generally good agreement with earlier measurements. The average total kinetic energy is approx. 0.2 MeV greater than the thermal value at neutron energies < 2 MeV and shows a sudden decrease of approx. 0.8 MeV between 4 and 5 MeV neutron energy, well below the (n, n'f) threshold. Possible causes of this decrease are a change in the mass distribution or decreased shell effects in the heavy fragment

Uranium ((234)U, (235)U and (238)U) contamination of the environment surrounding phosphogypsum waste heap in Wiślinka (northern Poland).

Science.gov (United States)

Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

2015-08-01

The aim of this work was to determine the uranium concentration ((234)U, (235)U and (238)U) and values of the activity ratio (234)U/(238)U in soil samples collected near phosphogypsum waste heap in Wiślinka (northern Poland). On the basis of the studies it was found that the values of the (234)U/(238)U activity ratio in the analyzed soils collected in the vicinity of phosphogypsum dump in Wiślinka are in most cases close to one and indicate the phosphogypsum origin of the analyzed nuclides. The obtained results of uranium concentrations are however much lower than in previous years before closing of the phosphogypsum stockpile. After this process and covering the phosphogypsum stockpile in Wiślinka with sewage sludge, phosphogypsum particles are successfully immobilized. In the light of the results the use of phosphate fertilizers seems to be a major problem. Prolonged and heavy rains can cause leaching accumulated uranium isotopes in the phosphogypsum stockpile, which will be washed into the Martwa Wisła and on the fields in the immediate vicinity of this storage. Copyright © 2015 Elsevier Ltd. All rights reserved.

Derivation of decay heat benchmarks for U235 and Pu239 by a least squares fit to measured data

International Nuclear Information System (INIS)

Tobias, A.

1989-05-01

A least squares technique used by previous authors has been applied to an extended set of available decay heat measurements for both U235 and Pu239 to yield simultaneous fits to the corresponding beta, gamma and total decay heat. The analysis takes account of both systematic and statistical uncertainties, including correlations, via calculations which use covariance matrices constructed for the measured data. The results of the analysis are given in the form of beta, gamma and total decay heat estimates following fission pulses and a range of irradiation times in both U235 and Pu239. These decay heat estimates are considered to form a consistent set of benchmarks for use in the assessment of summation calculations. (author)

235U enrichment determination on UF6 cylinders with CZT detectors

Science.gov (United States)

Berndt, Reinhard; Mortreau, Patricia

2018-04-01

Measurements of uranium enrichment in UF6 transit cylinders are an important nuclear safeguards verification task, which is performed using a non-destructive assay method, the traditional enrichment meter, which involves measuring the count rate of the 186 keV gamma ray. This provides a direct measure of the 235U enrichment. Measurements are typically performed using either high-resolution detectors (Germanium) with e-cooling and battery operation, or portable devices equipped with low resolution detectors (NaI). Despite good results being achieved when measuring Low Enriched Uranium in 30B type cylinders and natural uranium in 48Y type containers using both detector systems, there are situations, which preclude the use of one or both of these systems. The focus of this work is to address some of the recognized limitations in relation to the current use of the above detector systems by considering the feasibility of an inspection instrument for 235U enrichment measurements on UF6 cylinders using the compact and light Cadmium Zinc Telluride (CZT) detectors. In the present work, test measurements were carried out, under field conditions and on full-size objects, with different CZT detectors, in particular for situations where existing systems cannot be used e.g. for stacks of 48Y type containers with depleted uranium. The main result of this study shows that the CZT detectors, actually a cluster of four μCZT1500 micro spectrometers provide as good results as the germanium detector in the ORTEC Micro-trans SPEC HPGe Portable spectrometer, and most importantly in particular for natural and depleted uranium in 48Y cylinders.

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

International Nuclear Information System (INIS)

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

1989-11-01

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

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

International Nuclear Information System (INIS)

Kromphorn, G.

1996-02-01

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

High accuracy measurement of the $^{235}$U(n,f) reaction cross-section in the 10-30 keV neutron energy range

CERN Multimedia

The analysis of the neutron flux of n_TOF (in EAR1) revealed an anomaly in the 10-30 keV neutron energy range. While the flux extracted on the basis of the $^{6}$Li(n,t)$^{4}$He and $^{10}$B(n,$\\alpha$)$^{7}$Li reactions mostly agreed with each other and with the results of FLUKA simulations of the neutron beam, the one based on the $^{235}$U(n,f) reaction was found to be systematically lower, independently of the detection system used. A possible explanation is that the $^{235}$U(n,f) crosssection in that energy region, where in principle should be known with an uncertainty of 1%, may be systematically overestimated. Such a finding, which has a negligible influence on thermal reactors, would be important for future fast critical or subcritical reactors. Furthermore, its interest is more general, since the $^{235}$U(n,f) reaction is often used at that energy to determine the neutron flux, or as reference in measurements of fission cross section of other actinides. We propose to perform a high-accuracy, high-r...

Energies and Yields of Prompt Gamma Rays from Fragments in Slow-Neutron Induced Fission of 235U

Energy Technology Data Exchange (ETDEWEB)

Albinsson, H [Chalmers Univ. of Technology, Goeteborg (SE)

1971-04-15

Measurements were made on the gamma radiation emitted from fission fragments in slow-neutron induced fission of 235U. The fragments were detected with solid state detectors of the surface barrier type and the gamma radiation with a Nal(Tl) scintillator. Mass selection was used so that the gamma radiation could be measured as a function of fragment mass. Time discrimination between the fission gammas and the prompt neutrons released in the fission process was employed to reduce the background. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fission fragments. In this way it was possible to select various collimator settings and let gamma radiation of different half-lives be enhanced. Gamma-ray energy spectra from these time components were then recorded as function of mass. The spectrum shape differed greatly depending on the half-life of the radiation and the fragment from which it was emitted. The results of the present measurements were discussed in the light of existing fission models, and comparisons were made with prompt gamma-ray and neutron data from other fission experiments

Energies and Yields of Prompt Gamma Rays from Fragments in Slow-Neutron Induced Fission of 235U

International Nuclear Information System (INIS)

Albinsson, H.

1971-04-01

Measurements were made on the gamma radiation emitted from fission fragments in slow-neutron induced fission of 235 U. The fragments were detected with solid state detectors of the surface barrier type and the gamma radiation with a Nal(Tl) scintillator. Mass selection was used so that the gamma radiation could be measured as a function of fragment mass. Time discrimination between the fission gammas and the prompt neutrons released in the fission process was employed to reduce the background. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fission fragments. In this way it was possible to select various collimator settings and let gamma radiation of different half-lives be enhanced. Gamma-ray energy spectra from these time components were then recorded as function of mass. The spectrum shape differed greatly depending on the half-life of the radiation and the fragment from which it was emitted. The results of the present measurements were discussed in the light of existing fission models, and comparisons were made with prompt gamma-ray and neutron data from other fission experiments

Determination of uranium-235 by differential gamma spectrometry

International Nuclear Information System (INIS)

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

1974-12-01

A method for the determination of U-235 contained in solutions of uranium, by gamma spectrometry with Ge(Li) detector is described. Ra-226 is coprecipitated in BaSO 4 . The activity at 186 keV is measured, substracted by the corresponding of a standard. The detection limit is 1% of increment of U-235 over the standard. (author)

Current Status and Open Issues of the 235U Evaluation. Summary Report of an IAEA Consultants’ Meeting

International Nuclear Information System (INIS)

Noguere, Gilles; Trkov, Andrej

2016-08-01

The objective of this consultancy meeting was to discuss the status of the 235 U neutron cross sections from the thermal to MeV energy ranges, to identify the main difficulties and to propose recommendations for improving the current experimental and evaluation works

Estimation of covariances of 16O, 23Na, Fe, 235U, 238U and 239Pu neutron nuclear data in JENDL-3.2

International Nuclear Information System (INIS)

Shibata, Keiichi; Nakajima, Yutaka; Kawano, Toshihiko; Oh, Soo-Youl; Matsunobu, Hiroyuki; Murata, Toru.

1997-10-01

Covariances of nuclear data have been estimated for 6 nuclides contained in JENDL-3.2. The nuclides considered are 16 O, 23 Na, Fe, 235 U, 238 U, and 239 Pu, which are regarded as important for the nuclear design study of fast reactors. The physical quantities for which covariances are deduced are cross sections, resolved and unresolved resonance parameters, and the first order Legendre-polynomial coefficient for the angular distribution of elastically scattered neutrons. As for 235 U, covariances were obtained also for the average number of neutrons emitted in fission. The covariances were estimated by using the same methodology that had been used in the JENDL-3.2 evaluation in order to keep a consistency between mean values and their covariances. The least-squares fitting code GMA was used in estimating covariances for reactions of which JENDL-3.2 cross sections had been evaluated by taking account of measurements. In nuclear model calculations, the covariances were calculated by the KALMAN system. The covariance data obtained were compiled in the ENDF-6 format, and will be put into the JENDL-3.2 Covariance File which is one of JENDL special purpose files. (author). 193 refs

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

Energy Technology Data Exchange (ETDEWEB)

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

2009-07-01

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

Photofission cross-section ratio measurement of 235U/238U using monoenergetic photons in the energy range of 9.0-16.6 MeV

Science.gov (United States)

Krishichayan; Bhike, Megha; Finch, S. W.; Howell, C. R.; Tonchev, A. P.; Tornow, W.

2017-05-01

Photofission cross-section ratios of 235U and 238U have been measured using monoenergetic photon beams at the HIγS facility of TUNL. These measurements have been performed in small energy steps between 9.0 and 16.6 MeV using a dual-fission ionization chamber. Measured cross-section ratios are compared with the previous experimental data as well as with the recent evaluated nuclear data library ENDF.

Thermal-neutron fission cross section of 26. 1-min /sup 235/U/sup m/

Energy Technology Data Exchange (ETDEWEB)

Talbert W.L. Jr.; Starner, J.W.; Estep, R.J.; Balestrini, S.J.; Attrep M. Jr.; Efurd, D.W.; Roensch, F.R.

1987-11-01

The thermal-neutron fission cross section of /sup 235/U/sup m/ has been measured relative to the ground-state cross section. A rapid radiochemical separation procedure was developed to provide sizeable (10/sup 10/ to 10/sup 11/ atom) samples that were reasonably free of the parent /sup 239/Pu. From a series of eight measurements, the value of 1.42 +- 0.04 was obtained for the ratio sigma/sub m//sigma/sub g/.

Thermal-neutron fission cross section of 26.1-min /sup 235/U/sup m/

International Nuclear Information System (INIS)

Talbert, W.L. Jr.; Starner, J.W.; Estep, R.J.; Balestrini, S.J.; Attrep, M. Jr.; Efurd, D.W.; Roensch, F.R.

1987-01-01

The thermal-neutron fission cross section of /sup 235/U/sup m/ has been measured relative to the ground-state cross section. A rapid radiochemical separation procedure was developed to provide sizeable (10/sup 10/ to 10/sup 11/ atom) samples that were reasonably free of the parent /sup 239/Pu. From a series of eight measurements, the value of 1.42 +- 0.04 was obtained for the ratio σ/sub m//σ/sub g/

Average values of 235U resonance parameters up to 500 eV

International Nuclear Information System (INIS)

Leal, L.C.

1991-01-01

An R-matrix analysis of 235 U neutron cross sections was recently completed. The analysis was performed with the multilevel-multichannel Reich-Moore computer code SAMMY and extended the resolved resonance region up to 500 eV. Several high resolution measurements namely, transmission, fission and capture data as well as spin separated fission data were analyzed in a consistent manner and a very accurate parametrization up to 500 eV of these data were obtained. The aim of this paper is to present the results of average values of the resonance parameters. 9 refs., 1 tab

Ternary Fission of U{sup 235} by Resonance Neutrons; Fission Ternaire de {sup 235}U par des Neutrons de Resonance; 0422 0420 041e 0419 041d 041e 0415 0414 0415 041b 0415 041d 0418 0415 0423 0420 0410 041d 0410 -235 041d 0410 0420 0415 0417 041e 041d 0410 041d 0421 041d 042b 0425 041d 0415 0419 0422 0420 041e 041d 0410 0425 ; Fision Ternaria del {sup 235}U por Neutrones de Resonancia

Energy Technology Data Exchange (ETDEWEB)

Kvitek, I.; Popov, Ju. P.; Rjabov, Ju. V. [Ob' edinennyj Institut Jadernyh Issledovanij, Dubna, SSSR (Russian Federation)

1965-07-15

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

Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of 235U

International Nuclear Information System (INIS)

Modesto, Montoya

2014-01-01

The Coulomb effects hypothesis is used to interpret even-odd effects of maximum total kinetic energy as a function of mass and charge of fragments from thermal neutron induced fission of 235 U. Assuming spherical fragments at scission, the Coulomb interaction energy between fragments (C sph ) is higher than the Q-value, the available energy. Therefore at scission the fragments must be deformed, so that the Coulomb interaction energy does not exceed the Q-value. The fact that the even-odd effects in the maximum total kinetic energy as a function of the charge and mass, respectively, are lower than the even-odd effects of Q is consistent with the assumption that odd mass fragments are softer than the even-even fragments. Even-odd effects of charge distribution in super asymmetric fragmentation also are interpreted with the Coulomb effect hypothesis. Because the difference between C sph and Q increases with asymmetry, fragmentations require higher total deformation energy to occur. Higher deformation energy of the fragments implies lower free energy to break pairs of nucleons. This explains why in the asymmetric fragmentation region, the even-odd effects of the distribution of proton number and neutron number increases with asymmetry. (author).

Fingerprints of flower absolutes using supercritical fluid chromatography hyphenated with high resolution mass spectrometry.

Science.gov (United States)

Santerre, Cyrille; Vallet, Nadine; Touboul, David

2018-06-02

Supercritical fluid chromatography hyphenated with high resolution mass spectrometry (SFC-HRMS) was developed for fingerprint analysis of different flower absolutes commonly used in cosmetics field, especially in perfumes. Supercritical fluid chromatography-atmospheric pressure photoionization-high resolution mass spectrometry (SFC-APPI-HRMS) technique was employed to identify the components of the fingerprint. The samples were separated with a porous graphitic carbon (PGC) Hypercarb™ column (100 mm × 2.1 mm, 3 μm) by gradient elution using supercritical CO 2 and ethanol (0.0-20.0 min (2-30% B), 20.0-25.0 min (30% B), 25.0-26.0 min (30-2% B) and 26.0-30.0 min (2% B)) as mobile phase at a flow rate of 1.5 mL/min. In order to compare the SFC fingerprints between five different flower absolutes: Jasminum grandiflorum absolutes, Jasminum sambac absolutes, Narcissus jonquilla absolutes, Narcissus poeticus absolutes, Lavandula angustifolia absolutes from different suppliers and batches, the chemometric procedure including principal component analysis (PCA) was applied to classify the samples according to their genus and their species. Consistent results were obtained to show that samples could be successfully discriminated. Copyright © 2018 Elsevier B.V. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-09-15

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

Recent status of development and irradiation performance for plate type fuel elements with reduced 235U enrichment at NUKEM

International Nuclear Information System (INIS)

Hrovat, M.F.; Hassel, H.W.

1984-01-01

According to the present state of development full size test fuel elements with the maximum uranium densities of 2,2 g U/cm 3 meat for UAlsub(x), 3,2 g U/cm 3 meat for U 3 O 8 and 4,8 g U/cm 3 meat for U 3 Si 2 can be fabricated at NUKEM in production scale. Special chemical procedures for the uranium recovery were developed ensuring an economic fuel fabrication process. The post irradiation examinations (PIE) of 12 UAlsub(x) (U density 2,2 g U/cm 3 meat) and U 3 O 8 (up to 3,1 g U/cm 3 meat) test plates irradiated in the ORR, Oak Ridge research reactor, were terminated. All 12 test plates show unobjectionable irradiation behavior. Extensive irradiation tests on full size fuel elements were performed. All inserted elements show perfect irradiation behavior. The PIE of the first HFR Petten U 3 O 8 fuel elements are in progress. The full size ORR U 3 Si 2 fuel elements with so far highest uranium density of 4,76 g U/cm 3 meat achieved a burnup of 50 % loss of 235 U up to May 1983. One element was withdrawn from the reactor for PIE, the second will be irradiated to a burnup of 75 % loss of 235 U. The further development is concentrated on Usub(x)Sisub(y) fuel with highest uranium density. U 3 Si miniplates with up to 6,1 g U/cm 3 meat are supplied meeting the required specification, U 3 Si miniplates with 6,7 g U/cm 3 are in fabrication. (author)

Polarized BRDF measurement of steel E235B in the near-infrared region: Based on a self-designed instrument with absolute measuring method

Science.gov (United States)

Liu, Yanlei; Yu, Kun; Liu, Zilong; Zhao, Yuejin; Liu, Yufang

2018-06-01

The spectral bidirectional reflectance distribution (BRDF) offers a complete description of the optical properties of the opaque material. Numerous studies on BRDF have been conducted for its important role in scientific research and industrial production. However, most of these studies focus on the visible region and unpolarized BRDF, and the spectral polarized BRDF in the near-infrared region is rarely reported. In this letter, we propose an absolute method to measure the spectral BRDF in the near-infrared region, and the detailed derivation is presented. A self-designed instrument is set up for the absolute measurement of BRDF. The reliability of this method is verified by comparing the experimental data of the three metal (aluminum, silver and gold) mirrors with the reference data. The in-plane polarized BRDF of steel E235B are measured, and the influence of incident angle and roughness on the BRDF are discussed. The degree of linear polarization (DOLP) are determined based on the polarized BRDF. The results indicate that both the roughness and incident angle have distinct influence on the BRDF and DOLP.

Moderation control in low enriched 235U uranium hexafluoride packaging operations and transportation

International Nuclear Information System (INIS)

Dyer, R.H.; Kovac, F.M.; Pryor, W.A.

1993-01-01

Moderation control is the basic parameter for ensuring nuclear criticality safety during the packaging and transport of low 235 U enriched uranium hexafluoride before its conversion to nuclear power reactor fuel. Moderation control has permitted the shipment of bulk quantities in large cylinders instead of in many smaller cylinders and, therefore, has resulted in economies without compromising safety. Overall safety and uranium accountability have been enhanced through the use of the moderation control. This paper discusses moderation control and the operating procedures to ensure that moderation control is maintained during packaging operations and transportation

On the Relative Signs of "ROT-Effects" in Ternary and Binary Fission of 233U and 235U Nuclei Induced by Polarized Cold Neutrons

Science.gov (United States)

Danilyan, G. V.

2018-02-01

Signs of the ROT-effects in ternary fission of 233U and 235U experimentally defined by PNPI group are the same, whereas in binary fission defined by ITEP group are opposite. This contradiction cannot be explained by the errors in the experiments of both groups, since such instrumental effects would be too large not to be noticed. Therefore, it is necessary to find the answer to this problem in the differences of the ternary and binary fission mechanisms.

Calculating the mass distribution of heavy nucleus fission product by neutrons

International Nuclear Information System (INIS)

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

1981-01-01

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

235U Holdup Measurement Program in support of facility shutdown

International Nuclear Information System (INIS)

Thomason, R.S.; Griffin, J.C.; Lien, O.G.; McElroy, R.D.

1991-01-01

In 1989, the Department of Energy directed shutdown of an enriched uranium processing facility at Savannah River Site. As part of the shutdown requirements, deinventory and cleanout of process equipment and nondestructive measurement of the remaining 235 U holdup were required. The holdup measurements had safeguards, accountability, and nuclear criticality safety significance; therefore, a technically defensible and well-documented holdup measurement program was needed. Appropriate standards were fabricated, measurement techniques were selected, and an aggressive schedule was followed. Early in the program, offsite experts reviewed the measurement program, and their recommendations were adopted. Contact and far-field methods were used for most measurements, but some process equipment required special attention. All holdup measurements were documented, and each report was subjected to internal peer review. Some measured values were checked against values obtained by other methods; agreement was generally good

Absolute quantification of norovirus capsid protein in food, water, and soil using synthetic peptides with electrospray and MALDI mass spectrometry

International Nuclear Information System (INIS)

Hartmann, Erica M.; Colquhoun, David R.; Schwab, Kellogg J.; Halden, Rolf U.

2015-01-01

Highlights: • Mass spectrometry-based methods for norovirus quantification are developed. • Absolute quantification is achieved using internal heavy isotope-labeled standards. • A single labeled peptide serves in two distinct detection strategies. • These methods are validated for food, water, and soil analysis. • MS-based detection limits are lowered by two orders of magnitude. - Abstract: Norovirus infections are one of the most prominent public health problems of microbial origin in the U.S. and other industrialized countries. Surveillance is necessary to prevent secondary infection, confirm successful cleanup after outbreaks, and track the causative agent. Quantitative mass spectrometry, based on absolute quantitation with stable-isotope labeled peptides, is a promising tool for norovirus monitoring because of its speed, sensitivity, and robustness in the face of environmental inhibitors. In the current study, we present two new methods for the detection of the norovirus genogroup I capsid protein using electrospray and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The peptide TLDPIEVPLEDVR was used to quantify norovirus-like particles down to 500 attomoles with electrospray and 100 attomoles with MALDI. With MALDI, we also demonstrate a detection limit of 1 femtomole and a quantitative dynamic range of 5 orders of magnitude in the presence of an environmental matrix effect. Due to the rapid processing time and applicability to a wide range of environmental sample types (bacterial lysate, produce, milk, soil, and groundwater), mass spectrometry-based absolute quantitation has a strong potential for use in public health and environmental sciences

Absolute quantification of norovirus capsid protein in food, water, and soil using synthetic peptides with electrospray and MALDI mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Hartmann, Erica M. [Center for Environmental Security and Security Defense Systems Initiative, The Biodesign Institute, Arizona State University, 781 E. Terrace Mall, Tempe, AZ 85287-5904 (United States); Colquhoun, David R.; Schwab, Kellogg J. [Department of Environmental Health Sciences, The Johns Hopkins University, Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205 (United States); Halden, Rolf U., E-mail: halden@asu.edu [Center for Environmental Security and Security Defense Systems Initiative, The Biodesign Institute, Arizona State University, 781 E. Terrace Mall, Tempe, AZ 85287-5904 (United States); Department of Environmental Health Sciences, The Johns Hopkins University, Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205 (United States)

2015-04-09

Highlights: • Mass spectrometry-based methods for norovirus quantification are developed. • Absolute quantification is achieved using internal heavy isotope-labeled standards. • A single labeled peptide serves in two distinct detection strategies. • These methods are validated for food, water, and soil analysis. • MS-based detection limits are lowered by two orders of magnitude. - Abstract: Norovirus infections are one of the most prominent public health problems of microbial origin in the U.S. and other industrialized countries. Surveillance is necessary to prevent secondary infection, confirm successful cleanup after outbreaks, and track the causative agent. Quantitative mass spectrometry, based on absolute quantitation with stable-isotope labeled peptides, is a promising tool for norovirus monitoring because of its speed, sensitivity, and robustness in the face of environmental inhibitors. In the current study, we present two new methods for the detection of the norovirus genogroup I capsid protein using electrospray and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The peptide TLDPIEVPLEDVR was used to quantify norovirus-like particles down to 500 attomoles with electrospray and 100 attomoles with MALDI. With MALDI, we also demonstrate a detection limit of 1 femtomole and a quantitative dynamic range of 5 orders of magnitude in the presence of an environmental matrix effect. Due to the rapid processing time and applicability to a wide range of environmental sample types (bacterial lysate, produce, milk, soil, and groundwater), mass spectrometry-based absolute quantitation has a strong potential for use in public health and environmental sciences.

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

International Nuclear Information System (INIS)

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

1955-01-01

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

Are 0.1%-accurate gamma-ray assays possible for 235U solutions

International Nuclear Information System (INIS)

Parker, J.L.

1983-01-01

The factors influencing the accuracy of passive gamma-ray assay of uniform, homogeneous solution samples have been studied in some detail, particularly for the assay of 235 U in uranium solutions. Factors considered are the overall long-term electronic stability, the information losses caused by the rate-related electronic processes of pulse pileup and dead-time, and the self-attenuation of gamma rays within the samples. Both experimental and computational studies indicate that gamma-ray assay procedures for solution samples of moderate size (from approx. 10 to perhaps a few hundred milliliters) are now capable of accuracies approaching 0.1% in many practical cases

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-11-15

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

Automation of a thermal ionisation mass spectrometer

International Nuclear Information System (INIS)

Pamula, A.; Leuca, M.; Albert, S.; Benta, Adriana

2001-01-01

A thermal ionization mass spectrometer was upgraded in order to be monitored by a PC. A PC-LMP-16 National Instruments data acquisition board was used for the ion current channel and the Hall signal channel. A dedicated interface was built to allow commands from the computer to the current supply of the analyzing magnet and to the high voltage unit of the mass spectrometer. A software application was worked out to perform the adjustment of the spectrometer, magnetic scanning and mass spectra acquisition, data processing and isotope ratio determination. The apparatus is used for isotope ratio 235 U/ 238 U determination near the natural abundance. A peak jumping technique is applied to choose between the 235 U and 238 U signal, by switching the high voltage applied to the ion source between two preset values. This avoids the delay between the acquisition of the peaks of interest, a delay that would appear in the case of a 'pure' magnetic scanning. Corrections are applied for the mass discrimination effects and a statistical treatment of the data is achieved. (authors)

Monte Carlo cross section testing for thermal and intermediate 235U/238U critical assemblies, ENDF/B-V vs ENDF/B-VI

International Nuclear Information System (INIS)

Weinman, J.P.

1997-06-01

The purpose of this study is to investigate the eigenvalue sensitivity to changes in ENDF/B-V and ENDF/B-VI cross section data sets by comparing RACER vectorized Monte Carlo calculations for several thermal and intermediate spectrum critical experiments. Nineteen Oak Ridge and Rocky Flats thermal solution benchmark critical assemblies that span a range of hydrogen-to- 235 U (H/U) concentrations (2052 to 27.1) and above-thermal neutron leakage fractions (0.555 to 0.011) were analyzed. In addition, three intermediate spectrum critical assemblies (UH3-UR, UH3-NI, and HISS-HUG) were studied

Separation of uranium and plutonium isotopes for measurement by multi collector inductively coupled plasma mass spectroscopy

International Nuclear Information System (INIS)

Martinelli, R.E.; Hamilton, T.F.; Kehl, S.R.; Williams, R.W.

2009-01-01

Uranium (U) and plutonium (Pu) isotopes in coral soils, contaminated by nuclear weapons testing in the northern Marshall Islands, were isolated by ion-exchange chromatography and analyzed by mass spectrometry. The soil samples were spiked with 233 U and 242 Pu tracers, dissolved in minerals acids, and U and Pu isotopes isolated and purified on commercially available ion-exchange columns. The ion-exchange technique employed a TEVA R column coupled to a UTEVA R column. U and Pu isotope fractions were then further isolated using separate elution schemes, and the purified fractions containing U and Pu isotopes analyzed sequentially using multi-collector inductively coupled plasma mass spectrometer (MCICP-MS). High precision measurements of 234 U/ 235 U, 238 U/ 235 U, 236 U/ 235 U, and 240 Pu/ 239 Pu in soil samples were attained using the described methodology and instrumentation, and provide a basis for conducting more detailed assessments of the behavior and transfer of uranium and plutonium in the environment. (author)

Coulex fission of 234U, 235U, 237Np, and 238Np studied within the SOFIA experimental program

International Nuclear Information System (INIS)

Martin, Julie-Fiona

2014-01-01

SOFIA (Studies On FIssion with Aladin) is an experimental project which aims at systematically measuring the fission fragments' isotopic yields as well as their total kinetic energy, for a wide variety of fissioning nuclei. The PhD work presented in this dissertation takes part in the SOFIA project, and covers the fission of nuclei in the region of the actinides: 234 U, 235 U, 237 Np and 238 Np. The experiment is led at the heavy-ion accelerator GSI in Darmstadt, Germany. This facility provides intense relativistic primary beam of 238 U. A fragmentation reaction of the primary beam permits to create a secondary beam of radioactive ions, some of which the fission is studied. The ions of the secondary beam are sorted and identified through the FR-S (Fragment Separator), a high resolution recoil spectrometer which is tuned to select the ions of interest.The selected - fissile - ions then fly further to Cave-C, an experimental area where the fission experiment itself takes place. At the entrance of the cave, the secondary beam is excited by Coulomb interaction when flying through an target; the de-excitation process involves low-energy fission. Both fission fragments fly forward in the laboratory frame, due to the relativistic boost inferred from the fissioning nucleus.A complete recoil spectrometer has been designed and built by the SOFIA collaboration in the path of the fission fragments, around the existing ALADIN magnet. The identification of the fragments is performed by means of energy loss, time of flight and deviation in the magnet measurements. Both fission fragments are fully (in mass and charge) and simultaneously identified.This document reports on the analysis performed for (1) the identification of the fissioning system, (2) the identification of both fission fragments, on an event-by-event basis, and (3) the extraction of fission observables: yields, TKE, total prompt neutron multiplicity. These results, concerning the actinides, are discussed, and

Photo-fission Product Yield Measurements at Eγ=13 MeV on 235U, 238U, and 239Pu

Science.gov (United States)

Tornow, W.; Bhike, M.; Finch, S. W.; Krishichayan, Fnu; Tonchev, A. P.

2016-09-01

We have measured Fission Product Yields (FPYs) in photo-fission of 235U, 238U, and 239Pu at TUNL's High-Intensity Gamma-ray Source (HI γS) using mono-energetic photons of Eγ = 13 MeV. Details of the experimental setup and analysis procedures will be discussed. Yields for approximately 20 fission products were determined. They are compared to neutron-induced FPYs of the same actinides at the equivalent excitation energies of the compound nuclear systems. In the future photo-fission data will be taken at Eγ = 8 . 0 and 10.5 MeV to find out whether photo-fission exhibits the same so far unexplained dependence of certain FPYs on the energy of the incident probe, as recently observed in neutron-induced fission, for example, for the important fission product 147Nd. Work supported by the U. S. Dept. of Energy, under Grant No. DE-FG02-97ER41033, and by the NNSA, Stewardship Science Academic Alliances Program, Grant No. DE-NA0001838 and the Lawrence Livermore, National Security, LLC under Contract No. DE-AC52-07NA27344.

Effective cross sections of U-235 and Au in a TRIGA-type reactor core

International Nuclear Information System (INIS)

Harasawa, S.; Auu, G.A.

1992-01-01

The dependence of effective cross sections of gold and uranium for neutron spectrum in Rikkyo University Reactor (TRIGA Mark- II, RUR) fuel cell was studied using computer calculations. The dependence of thermal neutron spectrum with temperature was also investigated. The effective cross section of gold in water of the fuel cell at 32degC was 90.3 barn and the fission cross section of U-235, 483 barn. These two values are similar to the cross sections for neutron energy of 0.034 eV. (author)

8-group relative delayed neutron yields for epithermal neutron induced fission of 235U and 239Pu

International Nuclear Information System (INIS)

Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Korolev, G.G.; Roshchenko, V.A.; Tertychnyj, R.G

2002-01-01

An 8-group representation of relative delayed neutron yields was obtained for epithermal neutron induced fission of 235 U and 239 Pu. These data were compared with ENDF/B-VI data in terms of the average half- life of the delayed neutron precursors and on the basis of the dependence of reactivity on the asymptotic period. (author)

Measurements of Pu239:U235 fission ratio using foils at temperatures up to 400 deg. C

Energy Technology Data Exchange (ETDEWEB)

Carter, D H; Puckett, B J; Richards, A E [General Reactor Physics Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

1964-05-15

The paper describes the use of activation foils for the measurement of Pu239:U235 fission ratios in subcritical lattices at temperatures up to 390 deg C. Counting techniques and the method of analysis of the results are described in detail and the results are compared with fission chamber measurements. (author) 4 refs., 6 figs., 7 tabs.

Integral parameters for the Godiva benchmark calculated by using theoretical and adjusted fission spectra of 235U

International Nuclear Information System (INIS)

Caldeira, A.D.

1987-05-01

The theoretical and adjusted Watt spectrum representations for 235 U are used as weighting functions to calculate K eff and θ f 28 /θ f 25 for the benchmark Godiva. The results obtained show that the values of K eff and θ f 28 /θ f 25 are not affected by spectrum form change. (author) [pt

Calculated critical parameters in simple geometries for oxide and nitrate water mixtures of U-233, U-235 and Pu-239 with thorium. Final report

International Nuclear Information System (INIS)

Converse, W.E.; Bierman, S.R.

1979-11-01

Calculations have been performed on water mixtures of oxides and nitrates of 233 U, 235 U, and 239 Pu with chemically similar thorium compounds to determine critical dimensions for simple geometries (sphere, cylinder, and slab). Uranium enrichments calculated were 100%, 20%, 10%, and 5%; plutonium calculations assumed 100% 239 Pu. Thorium to uranium or plutonium weight ratios (Th: U or Pu) calculated were 0, 1, 4, and 8. Both bare and full water reflection conditions were calculated. The results of the calculations are plotted showing a critical dimension versus the uranium or plutonium concentration. Plots of K-infinity and material buckling for each material type are also shown

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

International Nuclear Information System (INIS)

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

2017-01-01

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Measurement of the fission cross-section ratio for 237Np/235U around 14 MeV neutron energies

International Nuclear Information System (INIS)

Desdin, L.; Szegedy, S.; Csikai, J.

1989-01-01

Fission cross-section ratio was determined for 237 Np/ 235 U around 14 MeV neutron energies with a back-to-back ionization chamber. Neutrons were produced by a 180 KV accelerator using T(d,n) 4 He reaction. No significant energy dependence was found in the cross section ratio

Measurements of the prompt neutron spectra in 233U, 235U, 239Pu thermal neutron fission in the energy range of 0.01-5 MeV and in 252Cf spontaneous fission in the energy range of 0.01-10 MeV

International Nuclear Information System (INIS)

Starostov, B.I.; Semenov, A.F.; Nefedov, V.N.

1978-01-01

The measurement results on the prompt neutron spectra in 233 U, 235 U, 239 Pu thermal neutron fission in the energy range of 0.01-5 MeV and in 252 Cf spontaneous fission in the energy range of 0.01-10 MeV are presented. The time-of-flight method was used. The exceeding of the spectra over the Maxwell distributions is observed at E 252 Cf neutron fission spectra. The spectra analysis was performed after normalization of the spectra and corresponding Maxwell distributions for one and the same area. In the range of 0.05-0.22 MeV the yield of 235 U + nsub(t) fission neutrons is approximately 8 and approximately 15 % greater than the yield of 252 Cf and 239 Pu + nsub(t) fission neutrons, respectively. In the range of 0.3-1.2 MeV the yield of 235 U + nsub(t) fission neutrons is 8 % greater than the fission neutron yield in case of 239 Pu + nsub(t) fission. The 235 U + nsub(t) and 233 U + nsub(t) fission neutron spectra do not differ from one another in the 0.05-0.6 MeV range

Yield of Prompt Gamma Radiation in Slow-Neutron Induced Fission of 235U as a Function of the Total Fragment Kinetic Energy

Energy Technology Data Exchange (ETDEWEB)

Albinsson, H [Chalmers Univ. of Technology, Goeteborg (SE)

1971-07-01

Fission gamma radiation yields as functions of the total fragment kinetic energy were obtained for 235U thermal-neutron induced fission. The fragments were detected with silicon surface-barrier detectors and the gamma radiation with a Nal(Tl) scintillator. In some of the measurements mass selection was used so that the gamma radiation could also be measured as a function of fragment mass. Time discrimination between the fission gammas and the prompt neutrons released in the fission process was employed to reduce the background. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fission fragments. Fission-neutron and gamma-ray data of previous experiments were used for comparisons of the yields, and estimates were made of the variation of the prompt gamma-ray energy with the total fragment kinetic energy

Development a recovery method of 13I from the 23'5U fission products

International Nuclear Information System (INIS)

Bignardi, Aline M.T.; Osso Junior, Joao Alberto

2013-01-01

13I is a iodine radioisotope widely used in nuclear medicine that can be used either for diagnostic or for treatment due to its physical decay by β- and its high emission of rays-γ. It is produced at IPEN through the irradiation of TeO 2 targets in the IEA-R1 nuclear reactor. There is also the possibility produced it by the fission of 235 U. The aim of this work is to develop a recovery method of 13I in the production process of 99 Mo through the route of acid dissolution of 235 U targets, with the quality to be used in Nuclear Medicine. 13I finds itself in two stages of the process, either in the gaseous produced in the acid dissolution of metallic U targets and the smallest part in solution. In this work was studied the recovery of 131 in these two stages. Several materials were used for the capture and recovery of 13I at the two phases of the process. Anionic cartridges, Ag cartridges, anion exchange resin, activated charcoal columns and AgI precipitation were tested. Solutions with 13 '1I in 0.1 mol.L -1 NaOH were percolated through the materials and the eluted solutions were analyzed in a dose calibrator. Among all the tests that were executed, at first, the anion exchange resin and AgI precipitation have showed the best retention result (100%). The results of elution have varied according to the material, the activated charcoal presented a elution yield between 70% and 82% At first, it is possible to conclude that anion exchange resin and AgI precipitation show better results for 13I retention and the column and activated charcoal have a great potential for the elution of 131 in the right chemical state. (author)

The Prompt Fission Neutron Spectrum of 235U for Einc 0.7-5.0 MeV

Energy Technology Data Exchange (ETDEWEB)

Gomez, Jaime A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devlin, Matthew James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haight, Robert Cameron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); O' Donnell, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lee, Hye Young [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mosby, Shea Morgan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Taddeucci, Terry Nicholas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kelly, Keegan John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fotiadis, Nikolaos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Neudecker, Denise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); White, Morgan Curtis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Talou, Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Solomon, Clell Jeffrey Jr. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wu, Ching-Yen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bucher, Brian Michael [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buckner, Matthew Quinn [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Henderson, Roger Alan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-03-23

The Chi-Nu experiment aims to accurately measure the prompt fission neutron spectrum (PFNS) for the major actinides. At the Los Alamos Neutron Science Center (LANSCE), fission can be induced using the white neutron source. Using a two arm time of flight (T.O.F) technique; Chi-Nu presents a preliminary result of the low energy component of the 235U PFNS measured using an array of 22-Lithium glass scintillators.

Photofission cross-section ratio measurement of {sup 235}U/{sup 238}U using monoenergetic photons in the energy range of 9.0–16.6 MeV

Energy Technology Data Exchange (ETDEWEB)

Krishichayan, E-mail: krishi@tunl.duke.edu [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Bhike, Megha; Finch, S.W.; Howell, C.R. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Tonchev, A.P. [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Tornow, W. [Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States)

2017-05-11

Photofission cross-section ratios of {sup 235}U and {sup 238}U have been measured using monoenergetic photon beams at the HIγS facility of TUNL. These measurements have been performed in small energy steps between 9.0 and 16.6 MeV using a dual-fission ionization chamber. Measured cross-section ratios are compared with the previous experimental data as well as with the recent evaluated nuclear data library ENDF.

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

Energy Technology Data Exchange (ETDEWEB)

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

1988-01-01

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

Decay heat from products of 235U thermal fission by fast-response boil-off calorimetry

International Nuclear Information System (INIS)

Yarnell, J.L.; Bendt, P.J.

1977-09-01

A cryogenic boil-off calorimeter was used to measure the decay heat from the products of thermal-neutron-induced fission of 235 U. Data are presented for cooling times between 10 and 10 5 s following a 2 x 10 4 s irradiation at constant thermal-neutron flux. The experimental uncertainty (1 sigma) in these measurements was approximately 2 percent, except at the shortest cooling times where it rose to approximately 4 percent. The beta and gamma energy from an irradiated 235 U sample was absorbed in a thermally isolated 52-kg copper block that was held at 4 K by an internal liquid helium reservoir. The absorbed energy evaporated liquid helium from the reservoir and a hot-film anemometer flowmeter recorded the evolution rate of the boil-off gas. The decay heat was calculated from the gas-flow rate using the heat of vaporization of helium. The calorimeter had a thermal time constant of 0.85 s. The energy loss caused by gamma leakage from the absorber was less than or equal to 3 percent; a correction was made by Monte Carlo calculations based on experimentally determined gamma spectra. The data agree within the combined uncertainties with summation calculations using the ENDF/B-IV data base. The experimental data were combined with summation calculations to give the decay heat for infinite (10 13 s) irradiation

Fission Fragment Mass Distributions and Total Kinetic Energy Release of 235-Uranium and 238-Uranium in Neutron-Induced Fission at Intermediate and Fast Neutron Energies

Energy Technology Data Exchange (ETDEWEB)

Duke, Dana Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-12

This Ph.D. dissertation describes a measurement of the change in mass distributions and average total kinetic energy (TKE) release with increasing incident neutron energy for fission of ²³⁵U and ²³⁸U. Although fission was discovered over seventy-five years ago, open questions remain about the physics of the fission process. The energy of the incident neutron, En, changes the division of energy release in the resulting fission fragments, however, the details of energy partitioning remain ambiguous because the nucleus is a many-body quantum system. Creating a full theoretical model is difficult and experimental data to validate existing models are lacking. Additional fission measurements will lead to higher-quality models of the fission process, therefore improving applications such as the development of next-generation nuclear reactors and defense. This work also paves the way for precision experiments such as the Time Projection Chamber (TPC) for fission cross section measurements and the Spectrometer for Ion Determination in Fission (SPIDER) for precision mass yields.

Studies of the Fission Integrals of U-{sup 235} and Pu-{sup 239} with Cadmium and Filters

Energy Technology Data Exchange (ETDEWEB)

Hellstrand, E

1965-04-15

The resonance fissions in U{sup 235} and Pu{sup 239} have been studied using cadmium and boron filters. Fission chambers were used as detectors and the experiments were performed in beam geometry. The neutron energy distribution in the beams transmitted through the different filters was determined with a fast chopper. From the cadmium filter, measurements the fission resonance integrals were determined. The values obtained were 278{+-}9 b for U{sup 235} and 301{+-}10 b for Pu{sup 239}; 0.5 eV < E < 1 MeV. Complementary Pu{sup 239} measurements were made in which the fission events were detected from the fission product activity in irradiated foils. Contrary to what has been reported elsewhere the value of the Pu{sup 239} resonance integral, found in this way, agreed well with that obtained from the fission chamber measurement. The experiments with the boron filters yielded results which, for the thin filter, agreed well with those calculated from the cross section data given in the Karlsruhe compilation. The discrepancy was larger for the thick filter but the values did not disagree outside the common limits of error.

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

International Nuclear Information System (INIS)

Alnour, I.A.

2014-01-01

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

Measurements of the {sup 235}U(n,f) cross section in the 3 to 30 MeV neutron energy region

Energy Technology Data Exchange (ETDEWEB)

Carlson, A.D.; Wasson, O.A. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Lisowski, P.W. [Los Alamos National Lab., NM (United States)] [and others

1991-12-31

To improve the accuracy of the {sup 235}U(n,f) cross section, measurements have been made of this standard cross section at the target 4 facility at Los Alamos National Laboratory (LANL). The data were obtained at the 20-meter flight path of that facility. The fission reaction rate was determined with a fast parallel plate ionization chamber and the neutron fluence was measured with an annular proton recoil telescope. The measurements provide the shape of the {sup 235}U(n,f) cross section relative to the hydrogen scattering cross section for neutron energies from about 3 to 30 MeV neutron energy. The data have been normalized to the very accurately known value near 14 MeV. The results are in good agreement with the ENDF/B-VI evaluation up to about 15 MeV neutron energy. Above this energy differences as large as 5% are observed.

Inelastic scattering of 1-2.5 MeV neutrons by 235U and 238U nuclei

International Nuclear Information System (INIS)

Kornilov, N.V.; Kagalenko, A.B.; Baryba, V.Ya.; Balitskij, A.V.; Androsenko, A.A.; Androsenko, P.A.

1993-07-01

The inelastic scattering cross-sections of 1-2.5 MeV neutrons for 235 U and 238 0 nuclei were measured. A detailed description is given of the data processing procedures used, and the methods for determining the neutron flux in the sample. The Monte Carlo method was used to calculate the corrections for multiple neutron scattering and neutron flux attenuation in the sample. Pursuant to an analysis of the fission neutron spectra, we concluded that the systematic error level of the results is ± 3.27%. The results of these cross-section and spectrum measurements for inelastically scattered neutrons are compared with results from other sources and existing evaluations, the possible causes of the divergences for neutrons with an energy level of less than 1 MeV are analysed, and suggestions are put forward for future research work. (author)

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

International Nuclear Information System (INIS)

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

2016-09-01

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

Accurate measurement of the first excited nuclear state in 235U

Science.gov (United States)

Ponce, F.; Swanberg, E.; Burke, J.; Henderson, R.; Friedrich, S.

2018-05-01

We have used superconducting high-resolution radiation detectors to measure the energy level of metastable Um235 as 76.737 ± 0.018 eV. The Um235 isomer is created from the α decay of 239Pu and embedded directly into the detector. When the Um235 subsequently decays, the energy is fully contained within the detector and is independent of the decay mode or the chemical state of the uranium. The detector is calibrated using an energy comb from a pulsed UV laser. A comparable measurement of the metastable Thm229 nucleus would enable a laser search for the exact transition energy in 229Th-Thm229 as a step towards developing the first ever nuclear (baryonic) clock.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-08-01

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

Routine Isotopic Analysis of 235U by Emission Spectrometry. 1. Interferometry using electrode-less discharge lamps 2. determination of the 235U/238U ratio using a spectrograph and electrode-less lamps

International Nuclear Information System (INIS)

Capitini, R.; Ceccaldi, M.; Leicknam, J.P.; Rabec, J.

1968-01-01

I. A 'HYPEAC' interferometric apparatus has been used for routine determination of uranium 235. In order to facilitate the examination of non-metallic samples and to reduce the time required for analysis it has been necessary to replace the hollow-cathode light sources usually used by electrode-less discharge lamps. The preparation outside the apparatus of such lamps containing uranium tetrachloride is described; the process is simple and rapid: about ninety minutes for each, and several lamps can be built simultaneously, thus reducing still further the total time required for each analysis. The amount of sample required is about a few milligrams. In order to counteract any spontaneous optical dis-adjustment which could prevent the application of the usual isotopic abundance method, it is necessary to compare the sample spectra with those of standards, all these spectra being recorded successively and alternately. A series of examples of determinations involving over 150 measurements is presented and discussed. For samples with abundances similar to that of natural uranium and up to 5 per cent of the 235 isotope., the reproducibility is of the order of 2 per cent, the relative accuracy being ± 2 to 3 per cent; for samples enriched in uranium 235 (5 to 93 per cent) the relative accuracy can attain ± 0.5 per cent. II. In spite of the large amount of research into the improvement of the accuracy of uranium isotope analyses using optical methods, it has not been possible up to the present to develop a method as good as mass spectrometry. When it is not necessary to have a high accuracy, however, emission spectroscopy which has no memory effect can constitute a complementary method of analysis if it is sufficiently fast and economical; for this to happen it seems to us that it should be possible to apply such a method in laboratories equipped with all the usual spectrochemical analysis equipment. In the present work we have therefore set out to obtain an acceptable

Evaluation of the 235U fission cross-section from 100 eV to 20 MeV

International Nuclear Information System (INIS)

Bhat, M.R.

1976-01-01

The evaluation of the 235 U fission cross section from 100 eV to 20 MeV for ENDF/B-V is described. The evaluated average cross sections from 100 eV to 200 keV are given, and it is proposed to include structure in the cross section in this energy region. Above 200 keV, the cross section is given as a smooth curve, and is recommended as a standard. Preliminary error estimates in the cross section are also given

A nondestructive testing device for determining 235U enrichment in power reactor fuel elements

International Nuclear Information System (INIS)

Liu Lanhua; Liu Nangai

1990-07-01

The development and application of a nondestructive testing device are presented, which is used for determining the 235 U enrichment in the mixed fuel of fuel elements with UO 2 pellets. The testing efficiency is improved because the passive gamma ray method and a hole-bored NaI crystal and four channel multichannel analyzer are used. The false discrimination rate is reduced as the average comparing method is taken. This device is simple in structure and easy in operation. It has provided a new testing tool for the fuel elements production in China. This device has successfully been used in Qinshan Nuclear Power Plant in testing its fuel elements

Uranium analysis in urine by inductively coupled plasma dynamic reaction cell mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Ejnik, John W. [Northern Michigan University, Chemistry Department, Marquette, MI (United States); Todorov, Todor I.; Mullick, Florabel G.; Centeno, Jose A. [Armed Forces Institute of Pathology (AFIP), Division of Biophysical Toxicology, Washington, DC (United States); Squibb, Katherine; McDiarmid, Melissa A. [University of Maryland, School of Medicine, Baltimore, MD (United States)

2005-05-01

Urine uranium concentrations are the best biological indicator for identifying exposure to depleted uranium (DU). Internal exposure to DU causes an increased amount of urine uranium and a decreased ratio of {sup 235}U/{sup 238}U in urine samples, resulting in measurements that vary between 0.00725 and 0.002 (i.e., natural and depleted uranium's {sup 235}U/{sup 238}U ratios, respectively). A method based on inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) was utilized to identify DU in urine by measuring the quantity of total U and the {sup 235}U/{sup 238}U ratio. The quantitative analysis was achieved using {sup 233}U as an internal standard. The analysis was performed both with and without the reaction gas oxygen. The reaction gas converted ionized {sup 235}U{sup +} and {sup 238}U{sup +} into {sup 235}UO{sub 2}{sup +} (m/z=267) and {sup 238}UO{sub 2}{sup +} (m/z=270). This conversion was determined to be over 90% efficient. A polyatomic interference at m/z 234.8 was successfully removed from the {sup 235}U signal under either DRC operating conditions (with or without oxygen as a reaction gas). The method was validated with 15 urine samples of known uranium compositions. The method detection limit for quantification was determined to be 0.1 pg U mL{sup -1} urine and an average coefficient of variation (CV) of 1-2% within the sample measurements. The method detection limit for determining {sup 235}U/{sup 238}U ratio was 3.0 pg U mL{sup -1} urine. An additional 21 patient samples were analyzed with no information about medical history. The measured {sup 235}U/{sup 238}U ratio within the urine samples correctly identified the presence or absence of internal DU exposure in all 21 patients. (orig.)

Measurement of fission yields far from the center of isotopic distributions in the thermal neutron fission of 235U

International Nuclear Information System (INIS)

Shmid, M.

1979-08-01

The main purpose of this work was to measure independent yields, in the thermal neutron fission of 235 U, of fission products which lie far from the centers of the isotopic and isobaric yield distributions. These measurements were used to test the predictions of semi-empirical systematics of fission yields and theoretical fission models. Delay times were measured as a function of temperature in the range 1200-2000degC. The very low delay times achieved in the present work permitted expanding the measurable region to the isotopes 147 , 148 Cs and 99 Rb which are of special interest in the present work. The delay times of Sr and Ba isotopes achieved were more than two orders of magnitude lower than values reported in the literature and thus short-lived isotopes of these elements could be separated for the first time by mass spectrometry. The half-lives of 147 Ba, 148 Ba, 149 La and 149 Ce were measured for the first time. The isotopic distributions of fission yields were measured for the elements Rb, Sr, Cs and Ba in the thermal neutron fission of 235 U, those of 99 Rb, 147 Cs and 148 Cs having been measured for the first time. A comparison of the experimental yields with the predictions of the currently accepted semi-empirical systematics of fission yields, which is the odd-even effect systematics, shows that the systematics succeeds in accounting for the strong odd-even proton effect and the weaker odd-even neutron effect and also in predicting the shape of the distributions in the central region. It is shown that prompt neutron emission broadens the distribution only slightly in the wing of heavy isotopes and more significantly in the wing of light isotopes. But the effect of prompt neutron emission cannot explain the large discrepancies existing between the predictions of fission models and the experimentally measured fission yield in the wings of the isotopic distributions. (B.G.)

Primary Distributions of Nuclear Charge for Fission-Fragment Masses 132, 134, 136 and 137 from Thermal Fission of U{sup 235}; Repartition Primaire de la Charge Nucleaire pour les Fragments de Masse 132, 134, 136 et 137, Provenant de la Fission de {sup 235}U par Neutrons Thermiques; 041f 0415 0420 0414 ; Distribuciones Primarias de las Cargas Nucleares de los Fragmentos de Masa 132, 134, 136 y 137, Resultantes de la Fision del {sup 235}U por Neutrones Termicos

Energy Technology Data Exchange (ETDEWEB)

Konecny, E.; Opower, H.; Guenther, H.; Goebel, H. [Physik-Department der Technischen Hochschule Muenchen, Munich and II. Physikalisches Institut der Justus Liebig-Universitaet Giessen, Federal Republic of Germany (Germany)

1965-07-15

By a mass spectrometer fission fragments from thermal fission of U{sup 235} are exactly separated with respect to mass and kinetic energy within a time of 10{sup -6} s after fission. The separated fragments are caught in a {beta}-sensitive Ilford G 5 emulsion that is located in the focal plane of the spectrometer. Development of the irradiated emulsions is carried out, if possible, after a time long compared with the longest half-life of the regarded decay chain. Half-lives of days or longer are not taken into account, but corrections can be easily made for them. After development of the emulsions all beta tracks emerging from the end of every fission-fragment track can be seen under the microscope. The possibility of correlating every single {beta}-track with a particular fission-fragment track allows the evaluation of the number n(x) of fission fragments possessing x {beta}-tracks, thus giving not only the mean chain length but also the {beta}-particle distribution. As the stable end product of each decay chain is known, this {beta}-distribution is an exact image of the primary nuclear charge distribution. In the measurements done up to now only {beta}-particles emitted into the half solid angle formed by the emulsion plate were registered, buta simple statistical calculation enables the desired 4{pi}-distribution to be evaluated. By this method {beta}-distributions at fixed kinetic energies near the mean kinetic energy of each fragment mass are given for the masses 132, 134, 136 and 137. For the lower masses 132 and 134 the neutron shell N = 82 is responsible for the most probable primary charges near 50 and 52 respectively. For M = 136 and 137 the primary charge is about 53 and 53.2. Additional approximative corrections in respect of conversion electrons (by omitting very short {beta}-tracks corresponding to very low {beta}-energies) and to delayed neutrons (for mass 137) were not very large. Similar measurements carried out directly in 4{pi}-geometry to avoid

Quantities of uranium-235 buried in disposal boxes, 1985--1991

International Nuclear Information System (INIS)

Cook, J.R.

1991-01-01

IWT was asked by J. R. Schornhorst of NPSR to determine the distribution of the quantity of enriched uranium per disposal box (B-25) of the years 1985--1991 to provide input to an uptake of the E Area Safety Analysis. This information was considered important since the issue of criticality is an important concern in safety analyses. Information found in the COBRA data base shows no disposal containers exceeded 100 grams of U-235. The COBRA data base was queried in a two-step process. First a short program in the NATURAL language was used to retrieve all records beginning with January 1983 having a Burial Code of less than 4, indicating low-level waste disposed in trenches. These records were then passed to a temporary storage file and read into a program written in Statistical Analysis System (SAS) language. SAS was used to eliminate waste from the Naval Fuel Facility, which will not operate in the future, and to sort the records in order of increasing amounts of U-235. The SAS procedure FREQ was then used to produce a cumulative frequency distribution of grams of U-235. A total of 53,198 packages were disposed of during this time period, 277 of which contained U-235. The programs used and resulting output are attached as Appendix I

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-09-15

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

Measurement of the average number of prompt neutrons emitted per fission of 235U relative to 252Cf for the energy region 500 eV to 10 MeV

International Nuclear Information System (INIS)

Gwin, R.; Spencer, R.R.; Ingle, R.W.; Todd, J.H.; Weaver, H.

1980-01-01

The average number of prompt neutrons emitted per fission ν/sub p/-bar(E), was measured for 235 U relative to ν/sub p/-bar for the spontaneous fission of 252 Cf over the neutron energy range from 500 eV to 10 MeV. The samples of 235 U and 252 Cf were contained in fission chambers located in the center of a large liquid scintillator. Fission neutrons were detected by the large liquid scintillator. The present values of ν/sub p/-bar(E) for 235 U are about 0.8% larger than those measured by Boldeman. In earlier work with the present system, it was noted that Boldeman's value of ν/sub p/-bar(E) for thermal energy neutrons was about 0.8% lower than obtained at ORELA. It is suggested that the thickness of the fission foil used in Boldeman's experiment may cause some of the discrepancy between his and the present values of ν/sub p/-bar(E). For the energy region up to 700 keV, the present values of ν/sub p/-bar(E) for 235 U agree, within the uncertainty, with those given in ENDF/B-V. Above 1 MeV the present results for ν/sub p/-bar(E) range about the ENDF/B-V values with differences up to 1.3%. 6 figures, 1 table

The 235U prompt fission neutron spectrum measured by the Chi-Nu project at LANSCE

Directory of Open Access Journals (Sweden)

Gomez J.A.

2017-01-01

Full Text Available The Chi-Nu experiment aims to accurately measure the prompt fission neutron spectrum for the major actinides. At the Los Alamos Neutron Science Center (LANSCE, fission can be induced with neutrons ranging from 0.7 MeV and above. Using a two arm time-of-flight (TOF technique, the fission neutrons are measured in one of two arrays: a 22-6Li glass array for lower energies, or a 54-liquid scintillator array for outgoing energies of 0.5 MeV and greater. Presented here are the collaboration's preliminary efforts at measuring the 235U PFNS.

Absolute analysis of uranium isotopic concentrations with a gas ion source mass spectrometer; Analyses absolues des concentrations isotopiques de l'uranium par spectrometre de masse equipe d'une source a gaz

Energy Technology Data Exchange (ETDEWEB)

Chaussy, L.; Boyer, R. [Commissariat a l' Energie Atomique, Pierrelatte (France)

1969-07-01

Mass spectrometer with electronic bombardment ions source for routine uranium isotopic analysis are used like relative measurements apparatus. We show that such mass spectrometers can be used for absolute measurements with a very high sensitivity and precision which are ten times better than theses of thermo-ionic ions source mass spectrometer. We examine the causes of systematic errors and we give experimental data. In particular natural uranium sample used as reference give: U{sub 5} = 0.7202 {+-} 0.0005 atoms per cent; U{sub 4} = 0.00552 {+-} 0.0003 atoms per cent. The use of this method is justified for standards control. (authors) [French] Les spectrometres de masse a source par bombardement electronique pour l'analyse de l'uranium sous forme d'hexafluorure, sont utilises en routine comme des appareils de mesure relative. On montre que l'on peut utiliser de tels appareils pour effectuer des mesures absolues avec une excellente sensibilite et reproductibilite, dix fois superieure a celle des spectrometres a source thermoionique. On examine en detail les causes d'erreurs systematiques et on donne des resultats experimentaux. En particulier, l'analyse d'un echantillon d'uranium naturel donne: U{sub 5} = 0.7202 {+-} 0.0005 atomes pour cent; U{sub 4} = 0.00552 {+-} 0.0003 atomes pour cent. La technique de mesure est utile pour le controle d'etalons isotopiques. (auteurs)

Estimation of covariances of {sup 16}O, {sup 23}Na, Fe, {sup 235}U, {sup 238}U and {sup 239}Pu neutron nuclear data in JENDL-3.2

Energy Technology Data Exchange (ETDEWEB)

Shibata, Keiichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Nakajima, Yutaka; Kawano, Toshihiko; Oh, Soo-Youl; Matsunobu, Hiroyuki; Murata, Toru

1997-10-01

Covariances of nuclear data have been estimated for 6 nuclides contained in JENDL-3.2. The nuclides considered are {sup 16}O, {sup 23}Na, Fe, {sup 235}U, {sup 238}U, and {sup 239}Pu, which are regarded as important for the nuclear design study of fast reactors. The physical quantities for which covariances are deduced are cross sections, resolved and unresolved resonance parameters, and the first order Legendre-polynomial coefficient for the angular distribution of elastically scattered neutrons. As for {sup 235}U, covariances were obtained also for the average number of neutrons emitted in fission. The covariances were estimated by using the same methodology that had been used in the JENDL-3.2 evaluation in order to keep a consistency between mean values and their covariances. The least-squares fitting code GMA was used in estimating covariances for reactions of which JENDL-3.2 cross sections had been evaluated by taking account of measurements. In nuclear model calculations, the covariances were calculated by the KALMAN system. The covariance data obtained were compiled in the ENDF-6 format, and will be put into the JENDL-3.2 Covariance File which is one of JENDL special purpose files. (author). 193 refs.

Determination of uranium isotopic composition and 236U content of soil samples and hot particles using inductively coupled plasma mass spectrometry.

Science.gov (United States)

Boulyga, S F; Becker, J S

2001-07-01

As a result of the accident at the Chernobyl nuclear power plant (NPP) the environment was contaminated with spent nuclear fuel. The 236U isotope was used in this study to monitor the spent uranium from nuclear fallout in soil samples collected in the vicinity of the Chernobyl NPP. Nuclear track radiography was applied for the identification and extraction of hot radioactive particles from soil samples. A rapid and sensitive analytical procedure was developed for uranium isotopic ratio measurement in environmental samples based on double-focusing inductively coupled plasma mass spectrometry (DF-ICP-MS) with a MicroMist nebulizer and a direct injection high-efficiency nebulizer (DIHEN). The performance of the DF-ICP-MS with a quartz DIHEN and plasma shielded torch was studied. Overall detection efficiencies of 4 x 10(-4) and 10(-3) counts per atom were achieved for 238U in DF-ICP-QMS with the MicroMist nebulizer and DIHEN, respectively. The rate of formation of uranium hydride ions UH+/U+ was 1.2 x 10(-4) and 1.4 x 10(-4), respectively. The precision of short-term measurements of uranium isotopic ratios (n = 5) in 1 microg L(-1) NBS U-020 standard solution was 0.11% (238U/235U) and 1.4% (236U/238U) using a MicroMist nebulizer and 0.25% (235U/238U) and 1.9% (236U/P38U) using a DIHEN. The isotopic composition of all investigated Chernobyl soil samples differed from those of natural uranium; i.e. in these samples the 236U/238U ratio ranged from 10(-5) to 10(-3). Results obtained with ICP-MS, alpha- and gamma-spectrometry showed differences in the migration properties of spent uranium, plutonium, and americium. The isotopic ratio of uranium was also measured in hot particles extracted from soil samples.

Determination of uranium isotopic composition and 236U content of soil samples and hot particles using inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Boulyga, S.F.; Becker, J.S.

2001-01-01

As a result of the accident at the Chernobyl nuclear power plant (NPP) the environment was contaminated with spent nuclear fuel. The 236 U isotope was used in this study to monitor the spent uranium from nuclear fallout in soil samples collected in the vicinity of the Chernobyl NPP. Nuclear track radiography was applied for the identification and extraction of hot radioactive particles from soil samples. A rapid and sensitive analytical procedure was developed for uranium isotopic ratio measurement in environmental samples based on double-focusing inductively coupled plasma mass spectrometry (DF-ICP-MS) with a MicroMist nebulizer and a direct injection high-efficiency nebulizer (DIHEN). The performance of the DF-ICP-MS with a quartz DIHEN and plasma shielded torch was studied. Overall detection efficiencies of 4 x 10 -4 and 10 -3 counts per atom were achieved for 238 U in DF-ICP-QMS with the MicroMist nebulizer and DIHEN, respectively. The rate of formation of uranium hydride ions UH + /U + was 1.2 x 10 -4 and 1.4 x 10 -4 , respectively. The precision of short-term measurements of uranium isotopic ratios (n = 5) in 1 μg L -1 NBS U-020 standard solution was 0.11% ( 238 U/ 235 U) and 1.4% ( 236 U/ 238 U) using a MicroMist nebulizer and 0.25% ( 235 U/ 238 U) and 1.9% ( 236 U/ 238 U) using a DIHEN. The isotopic composition of all investigated Chernobyl soil samples differed from those of natural uranium; i.e. in these samples the 236 U/ 238 U ratio ranged from 10 -5 to 10 -3 . Results obtained with ICP-MS, α- and γ-spectrometry showed differences in the migration properties of spent uranium, plutonium, and americium. The isotopic ratio of uranium was also measured in hot particles extracted from soil samples. (orig.)

The main conditions ensured problemless implementation of 235U high enriched fuel in Kozloduy NPP (Bulgaria) - WWER-1000 Units

International Nuclear Information System (INIS)

Dobrevski, I.; Zaharieva, N.; Minkova, K.; Michaylov, G.; Penev, P.; Gerchev, N.

2009-01-01

The collected water chemistry and radiochemistry data during the operation of the Kozloduy NPP Unit 5 for the period 2006-2009 (12-th, 13-th 14-th and 15-th fuel cycles) undoubtedly indicate for WWER-1000 Units (whose specific features are: Steam generators with austenitic stainless steel 08Cr18N10T tubing; Steam generators are with horizontal straight tubing and Fuel elements cladding material is Zr-1%Nb (Zr1Nb) alloy), that one realistic way for problemless implementation of 235 U high enriched fuel have been found. The main feature characteristics of this way are: Implementation of solid neutron burnable absorbers together with the dissolved in coolant neutron absorber - natural boric acid; Application of fuel cladding materials with enough corrosion resistance by the specific fuel cladding environment created by presence of SNB; Keeping of suitable coolant water chemistry which ensures low corrosion rates of core- and out-of-core- materials and limits in core (cladding) depositions and restricts out-of-core radioactivity buildup. The realization of this way in WWER-1000 Units in Kozloduy NPP was practically carried out through: 1) Implementation of Russian fuel assemblies TVSA which have as fuel cladding material E-110 alloy (Zr1Nb) with enough high corrosion resistance by presence of sub-cooled nucleate boiling (SNB) and use burnable absorber (Gd) integrated in the uranium-gadolinium (U-Gd 2 O 3 ) fuel (fuel rod with 5.0% Gd 2 O 3 ); 2) Development and implementation of water chemistry primary circuit guidelines, which require the relation between boric acid concentration and total alkalising agent concentrations to ensure coolant pH 300 = 7.0 - 7.2 values during the whole operation period. The above mentioned conditions by the passing of WWER-1000 Units in NPP Kozloduy to uranium fuel with 4.4% 235 U (TVSA fuel assemblies) practically ensured avoidance of the creation of the necessary conditions for AOA onset. The operational experience (2006-2009) of the

Feasibility study of {sup 235}U and {sup 239}Pu characterization in radioactive waste drums using neutron-induced fission delayed gamma rays

Energy Technology Data Exchange (ETDEWEB)

Nicol, T. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); FZJ, Institute of Energy and Climate Research – Nuclear Waste Management and Reactor Safety, Wilhelm-Johnen-Straße, d-52425 Jülich (Germany); Pérot, B., E-mail: bertrand.perot@cea.fr [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Carasco, C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Brackx, E. [CEA, DEN, Marcoule, Metallography and Chemical Analysis Laboratory, F-30207 Bagnols-sur-Cèze (France); Mariani, A.; Passard, C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Mauerhofer, E. [FZJ, Institute of Energy and Climate Research – Nuclear Waste Management and Reactor Safety, Wilhelm-Johnen-Straße, d-52425 Jülich (Germany); Collot, J. [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble Alpes, CNRS/IN2P3 Grenoble (France)

2016-10-01

This paper reports a feasibility study of {sup 235}U and {sup 239}Pu characterization in 225 L bituminized waste drums or 200 L concrete waste drums, by detecting delayed fission gamma rays between the pulses of a deuterium-tritium neutron generator. The delayed gamma yields were first measured with bare samples of {sup 235}U and {sup 239}Pu in REGAIN, a facility dedicated to the assay of 118 L waste drums by Prompt Gamma Neutron Activation Analysis (PGNAA) at CEA Cadarache, France. Detectability in the waste drums is then assessed using the MCNPX model of MEDINA (Multi Element Detection based on Instrumental Neutron Activation), another PGNAA cell dedicated to 200 L drums at FZJ, Germany. For the bituminized waste drum, performances are severely hampered by the high gamma background due to {sup 137}Cs, which requires the use of collimator and shield to avoid electronics saturation, these elements being very penalizing for the detection of the weak delayed gamma signal. However, for lower activity concrete drums, detection limits range from 10 to 290 g of {sup 235}U or {sup 239}Pu, depending on the delayed gamma rays of interest. These detection limits have been determined by using MCNPX to calculate the delayed gamma useful signal, and by measuring the experimental gamma background in MEDINA with a 200 L concrete drum mock-up. The performances could be significantly improved by using a higher interrogating neutron emission and an optimized experimental setup, which would allow characterizing nuclear materials in a wide range of low and medium activity waste packages.

Recent improvements of ISOLTRAP Absolute mass measurements of exotic nuclides at $10^{-8}$ precision

CERN Document Server

Kellerbauer, A G

2003-01-01

In the past three years, the sensitivity and the performance of the Penning trap mass spectrometer ISOLTRAP have been enhanced significantly. These improvements, which range from technical developments to systematic studies of the various factors contributing to the uncertainty of the final mass result, now allow mass measurements of short-lived radionuclides with half-lives of less than 100 ms and with a precision of better than 10$^{-8}$. Using a newly developed carbon cluster ion source, ISOLTRAP can perform absolute mass measurements relative to the microscopic mass standard $^{12}$C. These developments are reviewed as pertaining to the extension of ISOLTRAP mass measurements to higher precision and shorter half-lives and to molecular mass measurements.

8 CFR 235.10 - U.S. Citizen Identification Card.

Science.gov (United States)

2010-01-01

... Section 235.10 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS INSPECTION... demands an opportunity to see and rebut the adverse evidence. Any rebuttal, explanation, or evidence... whom it was issued admits in a statement signed before an immigration officer that he or she is an...

Application of the MGAU code for measuring 235U enrichment at the Brazilian Safeguards Laboratory

International Nuclear Information System (INIS)

Grund, Marcos S.; Dias, Fabio C.

2009-01-01

MGAU is a software tool for conducting uranium enrichment measurements based on high-resolution gamma ray spectroscopy. The code is capable of analyzing spectra (90 - 120 KeV region) collected from a wide variety of sample geometries and compositions. The main advantage of the code is its ability to perform spectra evaluation without a requirement for calibration with representative standards. However, it does require that the daughter isotopes be in activity equilibrium with the 235 U and 238 U parent isotopes. In order for the code to be more versatile in overcoming its limitations, a modified version of the traditional 'enrichment meter' method has been also added. In order to perform confirmatory uranium enrichment measurements for safeguards purposes at a laboratory environment, the Brazilian Safeguards Laboratory is investigating the performance of a nondestructive technique based on the use of the MGAU code for analyzing of gamma-ray spectra collected from pure uranium samples (primarily natural and low enriched powders and pellets). Several new good practice procedures were implemented in order to optimize the performance of the method at the best achievable level. This includes positioning of both the high-purity germanium detector and the sample inside a lead chamber for reducing background influence, collection of replicate measurements, and application of robust statistical treatment of data to reduce random contributions from counting statistics to the final uncertainty. Also, temperature and humidity inside the laboratory were monitored so that significant influences in results could be observed. Based on the results arising from analysis of certified reference materials, this paper discusses the performance of the MGAU code version 4.0 with focus on the uncertainties related to sample-dependent effects (mass, density, matrix composition and enrichment level). The reliability of the MGAU predicted uncertainty for single measurements and the occurrence

Determination of extremely low 236U/238U isotope ratios in environmental samples by sector-field inductively coupled plasma mass spectrometry using high-efficiency sample introduction

International Nuclear Information System (INIS)

Boulyga, Sergei F.; Heumann, Klaus G.

2006-01-01

A method by inductively coupled plasma mass spectrometry (Icp-Ms) was developed which allows the measurement of 236 U at concentration ranges down to 3 x 10 -14 g g -1 and extremely low 236 U/ 238 U isotope ratios in soil samples of 10 -7 . By using the high-efficiency solution introduction system APEX in connection with a sector-field ICP-MS a sensitivity of more than 5000 counts fg -1 uranium was achieved. The use of an aerosol desolvating unit reduced the formation rate of uranium hydride ions UH + /U + down to a level of 10 -6 . An abundance sensitivity of 3 x 10 -7 was observed for 236 U/ 238 U isotope ratio measurements at mass resolution 4000. The detection limit for 236 U and the lowest detectable 236 U/ 238 U isotope ratio were improved by more than two orders of magnitude compared with corresponding values by alpha spectrometry. Determination of uranium in soil samples collected in the vicinity of Chernobyl nuclear power plant (NPP) resulted in that the 236 U/ 238 U isotope ratio is a much more sensitive and accurate marker for environmental contamination by spent uranium in comparison to the 235 U/ 238 U isotope ratio. The ICP-MS technique allowed for the first time detection of irradiated uranium in soil samples even at distances more than 200 km to the north of Chernobyl NPP (Mogilev region). The concentration of 236 U in the upper 0-10 cm soil layers varied from 2 x 10 -9 g g -1 within radioactive spots close to the Chernobyl NPP to 3 x 10 -13 g g -1 on a sampling site located by >200 km from Chernobyl

Determination of extremely low (236)U/(238)U isotope ratios in environmental samples by sector-field inductively coupled plasma mass spectrometry using high-efficiency sample introduction.

Science.gov (United States)

Boulyga, Sergei F; Heumann, Klaus G

2006-01-01

A method by inductively coupled plasma mass spectrometry (ICP-MS) was developed which allows the measurement of (236)U at concentration ranges down to 3 x 10(-14)g g(-1) and extremely low (236)U/(238)U isotope ratios in soil samples of 10(-7). By using the high-efficiency solution introduction system APEX in connection with a sector-field ICP-MS a sensitivity of more than 5,000 counts fg(-1) uranium was achieved. The use of an aerosol desolvating unit reduced the formation rate of uranium hydride ions UH(+)/U(+) down to a level of 10(-6). An abundance sensitivity of 3 x 10(-7) was observed for (236)U/(238)U isotope ratio measurements at mass resolution 4000. The detection limit for (236)U and the lowest detectable (236)U/(238)U isotope ratio were improved by more than two orders of magnitude compared with corresponding values by alpha spectrometry. Determination of uranium in soil samples collected in the vicinity of Chernobyl nuclear power plant (NPP) resulted in that the (236)U/(238)U isotope ratio is a much more sensitive and accurate marker for environmental contamination by spent uranium in comparison to the (235)U/(238)U isotope ratio. The ICP-MS technique allowed for the first time detection of irradiated uranium in soil samples even at distances more than 200 km to the north of Chernobyl NPP (Mogilev region). The concentration of (236)U in the upper 0-10 cm soil layers varied from 2 x 10(-9)g g(-1) within radioactive spots close to the Chernobyl NPP to 3 x 10(-13)g g(-1) on a sampling site located by >200 km from Chernobyl.

The orbit of Phi Cygni measured with long-baseline optical interferometry - Component masses and absolute magnitudes

Science.gov (United States)

Armstrong, J. T.; Hummel, C. A.; Quirrenbach, A.; Buscher, D. F.; Mozurkewich, D.; Vivekanand, M.; Simon, R. S.; Denison, C. S.; Johnston, K. J.; Pan, X.-P.

1992-01-01

The orbit of the double-lined spectroscopic binary Phi Cygni, the distance to the system, and the masses and absolute magnitudes of its components are presented via measurements with the Mar III Optical Interferometer. On the basis of a reexamination of the spectroscopic data of Rach & Herbig (1961), the values and uncertainties are adopted for the period and the projected semimajor axes from the present fit to the spectroscopic data and the values of the remaining elements from the present fit to the Mark III data. The elements of the true orbit are derived, and the masses and absolute magnitudes of the components, and the distance to the system are calculated.

Anomalous isotope effects in the U(IV)-U(VI) exchange system

International Nuclear Information System (INIS)

Fujii, Yasuhiko; Nomura, Masao; Okamoto, Makoto; Onitsuka, Hatsuki; Nakanishi, Takashi.

1992-01-01

In previous papers, the enrichment of 236 U in the U(IV) - U(VI) chemical exchange system was found to be significantly smaller than the value estimated by the normal mass dependence enrichment of 235 U. Further experiments have been carried out in the present work to confirm the strange phenomenon of the isotopic anomaly in uranium enrichment. The results have indicated that the separation coefficient of 236 U is the same value as one previously reported. To confirm the anomaly of uranium isotope separation, α-ray spectrometry was implemented to check the enrichment behavior of 234 U. Although no theoretical explanation is given for the isotopic anomaly, this is favorable phenomenon for the re-enrichment of recycled uranium which contains isotopes 232 U and 236 U. (author)

Measurement of the neutron-induced fission cross section of 237Np relative to 235U from 0.02 to 30 MeV

International Nuclear Information System (INIS)

Behrens, J.W.; Magana, J.W.; Browne, J.C.

1977-01-01

The 237 Np/ 235 U fission cross section ratio has been measured from 0.02 to 30 MeV. Using the threshold method, a value of 1.294 +- 0.019 is obtained for the average cross section ratio in the interval from 1.75 to 4.00 MeV

{sup 5}He ternary fission yields of {sup 252}Cf and {sup 235}U(n,f)

Energy Technology Data Exchange (ETDEWEB)

Hwang, J. K. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Ramayya, A. V. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Hamilton, J. H. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Beyer, C. J. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Kormicki, J. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Zhang, X. Q. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Rodin, A. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Russia (Russian Federation); Formichev, A. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Russia (Russian Federation); Kliman, J. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Russia (Russian Federation); Krupa, L. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Russia (Russian Federation)] (and others)

2000-04-01

The relative {sup 4}He and {sup 5}He ternary fission yields were determined from a careful analysis of the energy distribution of {alpha} spectra from a new measurement with a {sup 252}Cf source and from published data on {sup 252}Cf and {sup 235}U(n,f). The kinetic energies of the {sup 5}He and {sup 4}He ternary particles were found to be approximately 11 and 16 MeV, respectively. {sup 5}He particles contribute 10-20 % to the total alpha yield with the remainder originating from {sup 4}He accompanied fission. (c) 2000 The American Physical Society.

Experiments to determine the rate of beta energy release following fission of Pu239 andU235 in a fast reactor

International Nuclear Information System (INIS)

Murphy, M.F.; Taylor, W.H.; Sweet, D.W.; March, M.R.

1979-02-01

Measurements have been made of the rate of beta energy release from Pu239 and U235 fission fragments over a period of 107 seconds following a 105 second irradiation in the zero-power fast reactor Zebra. Results are compared with predictions using the UKFPDD-1 decay data file and two different sets of fission product yield data. (author)

Efficiency of the low energy detection system for the measurement of {sup 235} U in lung of the Nuclear Regulatory Authority; Eficiencia del sistema de deteccion de baja energia para la medicion de {sup 235} U en pulmon de la Autoridad Regulatoria Nuclear

Energy Technology Data Exchange (ETDEWEB)

Spinella, M.R.; Krimer, M.; Gregori, B.N.; Rojo, A.M. [Autoridad Regulatoria Nuclear, Av. Del Libertador 8250 (C1429BNP), Buenos Aires (Argentina)]. e-mail: mspinell@cae.arn.gov.ar

2006-07-01

This work presents the results of the calibration process of the detection system of {sup 235} U in lung of the Nuclear Regulatory Authority. The phantom used in the calibration is the denominated Lawrence Livermore Realistic Phantom, provided of lungs and active nodules and of 4 thoracic covers that its simulate muscular tissue with thickness that vary between 1.638 and 3.871 cm. The spectra are acquired by four detecting of denominated LEGe ACTII Canberra marks, each one with an active area of 3800 mm{sup 2}, a diameter of 70 mm and a thickness of 20 mm, the sign is processed by a SYSTEM100 multichannel and the spectra are analyzed with the GENIE2K program. The detectors are suspended by mobile structures that allow to vary the position with regard to a horizontal stretcher that defines the measurement geometry. The whole system is located in the interior of an armored enclosure of 200 x 150 x 200 cm{sup 3} of steel of 15 cm thickness, inside recovered with layers of 0.5 cm lead and 0.05 cm cadmium. The total weight of the enclosure is 40 ton. For the described system the efficiency curves versus muscular thoracic tissue thickness (ETM) corresponding to the energy of 143.76, 163.358 and 185.72 keV of the {sup 235} U radioisotope were obtained. Its were also practiced displacements of those detectors of approximately 1 cm with respect to the reference position and its were analyzed the corresponding changes of magnitude in the efficiencies. The obtained variations oscillate, for vertical displacements, between 5% and 7.8% for the smallest value in ETM (1.638 cm) and between 4.2% to 6.7% for the ETM 3.871 cm. While for the practiced lateral displacements, the variations go from 4% to 15%. The detection limits corresponding to each energy and thickness were determined. The results showed for the photopeak of 185.72 keV, the more outstanding in the evaluations that saying limit it oscillates between 3.7 and 6.4 Bq {sup 235} U inside the considered thickness range

A new time of flight mass spectrometer for absolute dissociative electron attachment cross-section measurements in gas phase

Science.gov (United States)

Chakraborty, Dipayan; Nag, Pamir; Nandi, Dhananjay

2018-02-01

A new time of flight mass spectrometer (TOFMS) has been developed to study the absolute dissociative electron attachment (DEA) cross section using a relative flow technique of a wide variety of molecules in gas phase, ranging from simple diatomic to complex biomolecules. Unlike the Wiley-McLaren type TOFMS, here the total ion collection condition has been achieved without compromising the mass resolution by introducing a field free drift region after the lensing arrangement. The field free interaction region is provided for low energy electron molecule collision studies. The spectrometer can be used to study a wide range of masses (H- ion to few hundreds atomic mass unit). The mass resolution capability of the spectrometer has been checked experimentally by measuring the mass spectra of fragment anions arising from DEA to methanol. Overall performance of the spectrometer has been tested by measuring the absolute DEA cross section of the ground state SO2 molecule, and the results are satisfactory.

Determination of extremely low {sup 236}U/{sup 238}U isotope ratios in environmental samples by sector-field inductively coupled plasma mass spectrometry using high-efficiency sample introduction

Energy Technology Data Exchange (ETDEWEB)

Boulyga, Sergei F. [Institute of Inorganic Chemistry and Analytical Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55099 Mainz (Germany)]. E-mail: sergei.boulyga@univie.ac.at; Heumann, Klaus G. [Institute of Inorganic Chemistry and Analytical Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55099 Mainz (Germany)

2006-07-01

A method by inductively coupled plasma mass spectrometry (Icp-Ms) was developed which allows the measurement of {sup 236}U at concentration ranges down to 3 x 10{sup -14} g g{sup -1} and extremely low {sup 236}U/{sup 238}U isotope ratios in soil samples of 10{sup -7}. By using the high-efficiency solution introduction system APEX in connection with a sector-field ICP-MS a sensitivity of more than 5000 counts fg{sup -1} uranium was achieved. The use of an aerosol desolvating unit reduced the formation rate of uranium hydride ions UH{sup +}/U{sup +} down to a level of 10{sup -6}. An abundance sensitivity of 3 x 10{sup -7} was observed for {sup 236}U/{sup 238}U isotope ratio measurements at mass resolution 4000. The detection limit for {sup 236}U and the lowest detectable {sup 236}U/{sup 238}U isotope ratio were improved by more than two orders of magnitude compared with corresponding values by alpha spectrometry. Determination of uranium in soil samples collected in the vicinity of Chernobyl nuclear power plant (NPP) resulted in that the {sup 236}U/{sup 238}U isotope ratio is a much more sensitive and accurate marker for environmental contamination by spent uranium in comparison to the {sup 235}U/{sup 238}U isotope ratio. The ICP-MS technique allowed for the first time detection of irradiated uranium in soil samples even at distances more than 200 km to the north of Chernobyl NPP (Mogilev region). The concentration of {sup 236}U in the upper 0-10 cm soil layers varied from 2 x 10{sup -9} g g{sup -1} within radioactive spots close to the Chernobyl NPP to 3 x 10{sup -13} g g{sup -1} on a sampling site located by >200 km from Chernobyl.

Estimation of uranium and cobalt-60 distribution coefficients and uranium-235 enrichment at the Combustion Engineering Company site in Windsor, Connecticut

International Nuclear Information System (INIS)

Wang, Y.; Orlandini, K.A.; Yu, C.

1996-05-01

Site-specific distribution coefficients for uranium isotopes and cobalt-60 (Co-60) and the fraction of uranium-235 (U-235) enrichment by mass were estimated for environmental samples collected from the Combustion Engineering Company site in Windsor, CT. This site has been identified for remedial action under the US Department of Energy's (DOE) Formerly Utilized Sites Remedial Action Program. The authority of DOE at the Combustion Engineering site is limited to (1) Building 3; (2) other activities or areas associated exclusively with Building 3 (such as sewer lines); or (3) contamination that is exclusively highly enriched uranium. In this study, 16 samples were collected from the Combustion Engineering site, including 8 soil, 4 sediment, 3 water, and 1 water plus sludge sample. These samples were analyzed for isotopic uranium by alpha spectrometry and for Co-60 by gamma spectrometry. The site-specific distribution coefficient for each isotope was estimated as the ratio of extractable radionuclide activity in the solid phase to the activity in the contact solution following a 19-day equilibration. The uranium activity measurements indicate that uranium-234 (U-234) and uranium-238 (U-238) were in secular equilibrium in two soil samples and that soil and sediment samples collected from other sampling locations had higher U-234 activity than U-238 activity in both the solid and solution phases. The site-specific distribution coefficient (Kd) ranged from 82 to 44,600 mL/g for U-238 and from 102 to 65,900 mL/g for U-234. Calculation of U-235 enrichment by mass indicated that four soil samples had values greater than 0.20; these values were 0.37, 0.38, 0.46, and 0.68. Cobalt-60 activity was detected in only three sediment samples. The measured Co-60 activity in the solid phase ranged from 0.15 to 0.45 pCi/g and that in the water phase of all three samples combined was 4 pCi/L. The Kd value for Co-60 in the site brook sediment was calculated to be 70 mL/g

Absolute quantitation of proteins by Acid hydrolysis combined with amino Acid detection by mass spectrometry

DEFF Research Database (Denmark)

Mirgorodskaya, Olga A; Körner, Roman; Kozmin, Yuri P

2012-01-01

Amino acid analysis is among the most accurate methods for absolute quantification of proteins and peptides. Here, we combine acid hydrolysis with the addition of isotopically labeled standard amino acids and analysis by mass spectrometry for accurate and sensitive protein quantitation...

Use of delayed gamma rays for active non-destructive assay of {sup 235}U irradiated by pulsed neutron source (plasma focus)

Energy Technology Data Exchange (ETDEWEB)

Andola, Sanjay; Niranjan, Ram [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kaushik, T.C., E-mail: tckk@barc.gov.in [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rout, R.K. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Ashwani; Paranjape, D.B.; Kumar, Pradeep; Tomar, B.S.; Ramakumar, K.L. [Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Gupta, S.C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2014-07-01

A pulsed neutron source based on plasma focus device has been used for active interrogation and assay of {sup 235}U by monitoring its delayed high energy γ-rays. The method involves irradiation of fissile material by thermal neutrons obtained after moderation of a burst of neutrons emitted upon fusion of deuterium in plasma focus (PF) device. The delayed gamma rays emitted from the fissile material as a consequence of induced fission were detected by a large volume sodium iodide (NaI(Tl)) detector. The detector is coupled to a data acquisition system of 2k input size with 2k ADC conversion gain. Counting was carried out in pulse height analysis mode for time integrated counts up to 100 s while the temporal profile of delayed gamma has been obtained by counting in multichannel scaling mode with dwell time of 50 ms. To avoid the effect of passive (natural) and active (from surrounding materials) backgrounds, counts have been acquired for gamma energy between 3 and 10 MeV. The lower limit of detection of {sup 235}U in the oxide samples with this set-up is estimated to be 14 mg.

U.S. Geological Survey experience with the residual absolutes method

Directory of Open Access Journals (Sweden)

E. W. Worthington

2017-10-01

Full Text Available The U.S. Geological Survey (USGS Geomagnetism Program has developed and tested the residual method of absolutes, with the assistance of the Danish Technical University's (DTU Geomagnetism Program. Three years of testing were performed at College Magnetic Observatory (CMO, Fairbanks, Alaska, to compare the residual method with the null method. Results show that the two methods compare very well with each other and both sets of baseline data were used to process the 2015 definitive data. The residual method will be implemented at the other USGS high-latitude geomagnetic observatories in the summer of 2017 and 2018.

Critical experiments with 4.31 wt % 235U-enriched UO2 rods in highly borated water lattices

International Nuclear Information System (INIS)

Durst, B.M.; Bierman, S.R.; Clayton, E.D.

1982-08-01

A series of critical experiments were performed with 4.31 wt % 235 U enriched UO 2 fuel rods immersed in water containing various concentrations of boron ranging up to 2.55 g/l. The boron was added in the form of boric acid (H 3 BO 3 ). Critical experimental data were obtained for two different lattice pitches wherein the water-to-uranium oxide volume ratios were 1.59 and 1.09. The experiments provide benchmarks on heavily borated systems for use in validating calculational techniques employed in analyzing fuel shipping casks and spent fuel storage systems that may utilize boron for criticality control

Routine Isotopic Analysis of {sup 235}U by Emission Spectrometry. 1. Interferometry using electrode-less discharge lamps 2. determination of the {sup 235}U/{sup 238}U ratio using a spectrograph and electrode-less lamps; Contribution a l'analyse isotopique de routine de l'uranium 235 par spectrometrie d'emission. 1. interferometrie avec des lampes a decharge sans electrode. 2. determination du rapport {sup 235}U/{sup 238}U a l'aide d'un spectrographe et avec des lampes sans electrodes

Energy Technology Data Exchange (ETDEWEB)

Capitini, R; Ceccaldi, M; Leicknam, J P; Rabec, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1970-07-01

I. A 'HYPEAC' interferometric apparatus has been used for routine determination of uranium 235. In order to facilitate the examination of non-metallic samples and to reduce the time required for analysis it has been necessary to replace the hollow-cathode light sources usually used by electrode-less discharge lamps. The preparation outside the apparatus of such lamps containing uranium tetrachloride is described; the process is simple and rapid: about ninety minutes for each, and several lamps can be built simultaneously, thus reducing still further the total time required for each analysis. The amount of sample required is about a few milligrams. In order to counteract any spontaneous optical dis-adjustment which could prevent the application of the usual isotopic abundance method, it is necessary to compare the sample spectra with those of standards, all these spectra being recorded successively and alternately. A series of examples of determinations involving over 150 measurements is presented and discussed. For samples with abundances similar to that of natural uranium and up to 5 per cent of the 235 isotope., the reproducibility is of the order of 2 per cent, the relative accuracy being {+-} 2 to 3 per cent; for samples enriched in uranium 235 (5 to 93 per cent) the relative accuracy can attain {+-} 0.5 per cent. II. In spite of the large amount of research into the improvement of the accuracy of uranium isotope analyses using optical methods, it has not been possible up to the present to develop a method as good as mass spectrometry. When it is not necessary to have a high accuracy, however, emission spectroscopy which has no memory effect can constitute a complementary method of analysis if it is sufficiently fast and economical; for this to happen it seems to us that it should be possible to apply such a method in laboratories equipped with all the usual spectrochemical analysis equipment. In the present work we have therefore set out to obtain an

Fission-product energy release for times following thermal-neutron fission of 235U between 2 and 14000 seconds

International Nuclear Information System (INIS)

Dickens, J.K.; Emery, J.F.; Love, T.A.; McConnell, J.W.; Northcutt, K.J.; Peelle, R.W.; Weaver, H.

1977-10-01

Fission-product decay energy-releases rates were measured for thermal-neutron fission of 235 U. Samples of mass 1 to 10 μg were irradiated for 1 to 100 sec by use of the fast pneumatic-tube facility at the Oak Ridge Research Reactor. The resulting beta- and gamma-ray emissions were counted for times-after-fission between 2 and 14,000 seconds. The data were obtained for beta and gamma rays separately as spectral distributions, N(E/sub γ/) vs E/sub γ/ and N(E/sub beta/) vs E/sub β/. For the gamma-ray data the spectra were obtained by using a NaI detector, while for the beta-ray data the spectra were obtained by using an NE-110 detector with an anticoincidence mantle. The raw data were unfolded to provide spectral distributions of modest resolution. These were integrated over E/sub γ/ and E/sub β/ to provide total yield and energy integrals as a function of time after fission. Results are low compared to the present 1973 ANS Decay-heat standard. A complete description of the experimental apparatus and data-reduction techniques is presented. The final integral data are given in tabular and graphical form and are compared with published data. 41 figures, 13 tables

Fuel cycle cost, reactor physics and fuel manufacturing considerations for Erbia-bearing PWR fuel with > 5 wt% U-235 content

Energy Technology Data Exchange (ETDEWEB)

Franceschini, F.; Lahoda, E. J.; Kucukboyaci, V. N. [Westinghouse Electric Co. LLC, 1000 Westinghouse Drive, Cranberry Township, PA 16066 (United States)

2012-07-01

The efforts to reduce fuel cycle cost have driven LWR fuel close to the licensed limit in fuel fissile content, 5.0 wt% U-235 enrichment, and the acceptable duty on current Zr-based cladding. An increase in the fuel enrichment beyond the 5 wt% limit, while certainly possible, entails costly investment in infrastructure and licensing. As a possible way to offset some of these costs, the addition of small amounts of Erbia to the UO{sub 2} powder with >5 wt% U-235 has been proposed, so that its initial reactivity is reduced to that of licensed fuel and most modifications to the existing facilities and equipment could be avoided. This paper discusses the potentialities of such a fuel on the US market from a vendor's perspective. An analysis of the in-core behavior and fuel cycle performance of a typical 4-loop PWR with 18 and 24-month operating cycles has been conducted, with the aim of quantifying the potential economic advantage and other operational benefits of this concept. Subsequently, the implications on fuel manufacturing and storage are discussed. While this concept has certainly good potential, a compelling case for its short-term introduction as PWR fuel for the US market could not be determined. (authors)

Standard specification for uranium hexafluoride enriched to less than 5 % 235U

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This specification covers nuclear grade uranium hexafluoride (UF6) that either has been processed through an enrichment plant, or has been produced by the blending of Highly Enriched Uranium with other uranium to obtain uranium of any 235U concentration below 5 % and that is intended for fuel fabrication. The objectives of this specification are twofold: (1) To define the impurity and uranium isotope limits for Enriched Commercial Grade UF6 so that, with respect to fuel design and manufacture, it is essentially equivalent to enriched uranium made from natural UF6; and (2) To define limits for Enriched Reprocessed UF6 to be expected if Reprocessed UF6 is to be enriched without dilution with Commercial Natural UF6. For such UF6, special provisions, not defined herein, may be needed to ensure fuel performance and to protect the work force, process equipment, and the environment. 1.2 This specification is intended to provide the nuclear industry with a standard for enriched UF6 that is to be used in the pro...

Measurement of 235U enrichment in UF6 by passive gamma spectrometry

International Nuclear Information System (INIS)

Sawai, Hideo; Ochiai, Ken-ichi; Kaya, Akira

1979-01-01

For the assay of UF 6 , a single-channel analyzer (SCA) system of a passive gamma spectrometer has been developed. Basic measuring conditions were studied: such as the effects of sample density and heterogeneity and the effects of cylinder material and wall thickness. Called ''enrichment analyzer'', the system is operated to carry out the measurement and calculation of 235 U enrichment by a directive of the program in a calculator. The resulting data are available in real time output. Measurements were carried out in two modes: ''all way'' mode which measured in the rotation of the cylinder and the up-and-down motion of the detector, and ''spot'' mode which measured at one point on the cylinder. The average accuracy was about 1.8% in case of the former, and 3.2% in case of the latter. It was shown that the ''all way'' mode is preferable, but the ''spot'' mode is also necessary for the assay of large cylinders such as 30 A type. (J.P.N.)

Energy dependence of the neutron multiplicity P/sub nu/ in fast neutron induced fission of /sup 235,238/U and 239Pu

International Nuclear Information System (INIS)

Zucker, M.S.; Holden, N.E.

1986-01-01

Certain applications require knowledge of the higher moments of the neutron multiplicity probability. It can be shown that the second factorial moment is proportional to the fission rate in the sample, and that the third factorial moment can be of use in disentangling spontaneous fission from induced fission. Using a source of unpublished work in which neutron multiplicities were derived for the fast neutron induced fission of U-235, U-238, and Pu-239, the multiplicity probability has been calculated as a function of neutron energy for the energy range 0 to 10 MeV

Chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade mixed oxides [(U,Pu)O2

International Nuclear Information System (INIS)

Anon.

1981-01-01

Mixed oxide, a mixture of uranium and plutonium oxides, is used as a nuclear-reactor fuel in the form of pellets. The plutonium content may be up to 10 wt %, and the diluent uranium may be of any U-235 enrichment. In order to be suitable for use as a nuclear fuel, the material must meet certain criteria for combined uranium and plutonium content, effective fissile content, and impurity content. Analytical procedures used to determine if mixed oxides comply with specifications are: uranium by controlled-potential coulometry; plutonium by controlled-potential coulometry; plutonium by amperometric titration with iron (II); nitrogen by distillation spectrophotometry using Nessler reagent; carbon (total) by direct combustion-thermal-conductivity; total chlorine and fluorine by pyrohydrolysis; sulfur by distillation-spectrophotometry; moisture by the coulometric, electrolytic moisture analyzer; isotopic composition by mass spectrometry; rare earths by copper spark spectroscopy; trace impurities by carrier distillation spectroscopy; impurities by spark-source mass spectrography; total gas in reactor-grade mixed dioxide pellets; tungsten by dithiol-spectrophotometry; rare earth elements by spectroscopy; plutonium-238 isotopic abundance by alpha spectrometry; uranium and plutonium isotopic analysis by mass spectrometry; oxygen-to-metal atom ratio by gravimetry

Determination of uranium isotopic composition and {sup 236}U content of soil samples and hot particles using inductively coupled plasma mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Boulyga, S.F. [Radiation Physics and Chemistry Problems Inst., Minsk (Belarus); Becker, J.S. [Central Department for Analytical Chemistry, Research Centre Juelich (Germany)

2001-07-01

As a result of the accident at the Chernobyl nuclear power plant (NPP) the environment was contaminated with spent nuclear fuel. The {sup 236}U isotope was used in this study to monitor the spent uranium from nuclear fallout in soil samples collected in the vicinity of the Chernobyl NPP. Nuclear track radiography was applied for the identification and extraction of hot radioactive particles from soil samples. A rapid and sensitive analytical procedure was developed for uranium isotopic ratio measurement in environmental samples based on double-focusing inductively coupled plasma mass spectrometry (DF-ICP-MS) with a MicroMist nebulizer and a direct injection high-efficiency nebulizer (DIHEN). The performance of the DF-ICP-MS with a quartz DIHEN and plasma shielded torch was studied. Overall detection efficiencies of 4 x 10{sup -4} and 10{sup -3} counts per atom were achieved for {sup 238}U in DF-ICP-QMS with the MicroMist nebulizer and DIHEN, respectively. The rate of formation of uranium hydride ions UH{sup +}/U{sup +} was 1.2 x 10{sup -4} and 1.4 x 10{sup -4}, respectively. The precision of short-term measurements of uranium isotopic ratios (n = 5) in 1 {mu}g L{sup -1} NBS U-020 standard solution was 0.11% ({sup 238}U/{sup 235}U) and 1.4% ({sup 236}U/{sup 238}U) using a MicroMist nebulizer and 0.25% ({sup 235}U/{sup 238}U) and 1.9% ({sup 236}U/{sup 238}U) using a DIHEN. The isotopic composition of all investigated Chernobyl soil samples differed from those of natural uranium; i.e. in these samples the {sup 236}U/{sup 238}U ratio ranged from 10{sup -5} to 10{sup -3}. Results obtained with ICP-MS, {alpha}- and {gamma}-spectrometry showed differences in the migration properties of spent uranium, plutonium, and americium. The isotopic ratio of uranium was also measured in hot particles extracted from soil samples. (orig.)

Measurement of the ROT effect in the neutron induced fission of 235U in the 0.3 eV resonance at a hot source of polarized neutrons

Science.gov (United States)

Kopatch, Yuri; Novitsky, Vadim; Ahmadov, Gadir; Gagarsky, Alexei; Berikov, Daniyar; Danilyan, Gevorg; Hutanu, Vladimir; Klenke, Jens; Masalovich, Sergey

2018-03-01

The TRI and ROT asymmetries in fission of heavy nuclei have been extensively studied during more than a decade. The effects were first discovered in the ternary fission in a series of experiments performed at the ILL reactor (Grenoble) by a collaboration of Russian and European institutes, and were carefully measured for a number of fissioning nuclei. Later on, the ROT effect has been observed in the emission of prompt gamma rays and neutrons in fission of 235U and 233U, although its value was an order of magnitude smaller than in the α-particle emission from ternary fission. All experiments performed so far are done with cold polarized neutrons, what assumes a mixture of several spin states, the weights of these states being not well known. The present paper describes the first attempt to get "clean" data by performing the measurement of gamma and neutron asymmetries in an isolated resonance of 235U at the POLI instrument of the FRM2 reactor in Garching.

Efficiency of the low energy detection system for the measurement of 235 U in lung of the Nuclear Regulatory Authority

International Nuclear Information System (INIS)

Spinella, M.R.; Krimer, M.; Gregori, B.N.; Rojo, A.M.

2006-01-01

This work presents the results of the calibration process of the detection system of 235 U in lung of the Nuclear Regulatory Authority. The phantom used in the calibration is the denominated Lawrence Livermore Realistic Phantom, provided of lungs and active nodules and of 4 thoracic covers that its simulate muscular tissue with thickness that vary between 1.638 and 3.871 cm. The spectra are acquired by four detecting of denominated LEGe ACTII Canberra marks, each one with an active area of 3800 mm 2 , a diameter of 70 mm and a thickness of 20 mm, the sign is processed by a SYSTEM100 multichannel and the spectra are analyzed with the GENIE2K program. The detectors are suspended by mobile structures that allow to vary the position with regard to a horizontal stretcher that defines the measurement geometry. The whole system is located in the interior of an armored enclosure of 200 x 150 x 200 cm 3 of steel of 15 cm thickness, inside recovered with layers of 0.5 cm lead and 0.05 cm cadmium. The total weight of the enclosure is 40 ton. For the described system the efficiency curves versus muscular thoracic tissue thickness (ETM) corresponding to the energy of 143.76, 163.358 and 185.72 keV of the 235 U radioisotope were obtained. Its were also practiced displacements of those detectors of approximately 1 cm with respect to the reference position and its were analyzed the corresponding changes of magnitude in the efficiencies. The obtained variations oscillate, for vertical displacements, between 5% and 7.8% for the smallest value in ETM (1.638 cm) and between 4.2% to 6.7% for the ETM 3.871 cm. While for the practiced lateral displacements, the variations go from 4% to 15%. The detection limits corresponding to each energy and thickness were determined. The results showed for the photopeak of 185.72 keV, the more outstanding in the evaluations that saying limit it oscillates between 3.7 and 6.4 Bq 235 U inside the considered thickness range. (Author)

Improved Technique for the Determination of Uranium Minor Isotopes Concentrations in Microparticles by Using Secondary Ion Mass-Spectrometer in Multicollection Mode

International Nuclear Information System (INIS)

Aleshin, M.; Elantyev, I.; Stebelkov, Y.

2015-01-01

Traditional method of the analysis implies simultaneous measuring of secondary ion currents of isotopes 234U + , 235U + , 238U + , ions with mass 236 amu (236U + and 235UH + ) and hydride ions 238UH + by using mass-spectrometer Cameca IMS1280 in multicollection mode. Calculating of uranium isotopic composition is performed using the results of 40 successive measurements of those currents (cycles). Duration of each measurement is 8 s. Small amounts of uranium minor isotopes are limitation for precise determination of their concentrations. To prevent the damage of the secondary ions detector the intensity of ion current should be no more than 5 x 10 5 s -1 . This limitation does not allow setting a higher primary ion current for the increasing of minor uranium isotopes ions emission because of the signal of ions 238U + gets too high. New technique is developed to improve the accuracy of determination of uranium minor isotopes concentrations. Process of measurement is divided on two steps. First step is a measurement of ion currents during 20 cycles by five detectors. The second step implies the elimination of ions 238U + hitting to the detector and 10 times increasing of primary ion current. The ratio 235U/238U is calculated from the first step results, so uncertainty of determination of this value is 1.4 times bigger than with duration of 40 cycles of the measurement. The ratios 234U/235U and 236U/235U are calculated during the second step. This technique allows to determine content of 234U and 236U with 3 and 5 times less uncertainties respectively, but with different degree of the sputtering particles. Moreover the duration of each cycle was set less (1 second) to use data more efficient. The technique accordingly with every second counting provides uncertainty of determination 236U concentration 4 times less than traditional method at the same degree of sputtering particles. (author)

HEU age determination by the activity ratio {sup 227}Th/{sup 235}U

Energy Technology Data Exchange (ETDEWEB)

Li, Junjie; Zeng, Lina; Wu, Jian; Zheng, Chun; Li, Jiansheng, E-mail: lastljj@hotmail.com

2014-02-15

It is important to measure the age of a highly enriched uranium (HEU) assembly for authentication of the material in the frame of arms control inspections. A new non-destructive gamma spectrometric method for HEU age-dating is reported. This method relies on measuring the daughter/parent activity ratio {sup 227}Th/{sup 235}U by high-resolution gamma spectrometry. Only a narrow gamma range of energy of uranium from 230 keV to 242 keV will be used for analysis. The relative efficiency of every characteristic gamma ray changes in a small range because it has a near energy, which makes the results more accurate in theory. It provides a quick and reliable method for HEU age determination. Several gamma spectra of the same HEU assembly have been measured with different conditions (gain settings, distance and measurement time). When a branching ratio of 12.6% was chosen for the 235.96 keV line of {sup 227}Th, we obtained the activity ratios of (5.61 ± 0.40) × 10{sup −4}, (5.17 ± 0.39) × 10{sup −4}, (5.26 ± 0.39) × 10{sup −4}, (5.10 ± 0.35) × 10{sup −4}, (5.50 ± 0.44) × 10{sup −4} and (5.47 ± 0.42) × 10{sup −4}, respectively. These ratios correspond to ages of 52.2 ± 2.4 years, 49.7 ± 2.3 years, 50.1 ± 2.3 years, 49.3 ± 2.2 years, 51.6 ± 2.5 years and 51.5 ± 2.4 years, respectively, which are consistent with the known age of this material and the results of the U–Bi method.

Critical and subcritical mass calculations of fissionable nuclides based on JENDL-3.2+

International Nuclear Information System (INIS)

Okuno, H.

2002-01-01

We calculated critical and subcritical masses of 10 fissionable actinides ( 233 U, 235 U, 238 Pu, 239 Pu, 241 Pu, 242m Am, 243 Cm, 244 Cm, 249 Cf and 251 Cf) in metal and in metal-water mixtures (except 238 Pu and 244 Cm). The calculation was made with a combination of a continuous energy Monte Carlo neutron transport code, MCNP-4B2, and the latest released version of the Japanese Evaluated Nuclear Data Library, JENDL-3.2. Other evaluated nuclear data files, ENDF/B-VI, JEF-2.2, and JENDL-3.3 in its preliminary version were also applied to find differences in results originated from different nuclear data files. For the so-called big three fissiles ( 233 U, 235 U and 239 Pu), analyzing the criticality experiments cited in ICSBEP Handbook validated the code-library combination, and calculation errors were consequently evaluated. Estimated critical and lower limit critical masses of the big three in a sphere with/without a water or SS-304 reflector were supplied, and they were compared with the subcritical mass limits of ANS-8.1. (author)

Evaluation of precision in measurements of uranium isotope ratio by thermionic mass spectrometry

International Nuclear Information System (INIS)

Moraes, N.M.P. de; Rodrigues, C.

1977-01-01

The parameters which affect the precision and accuracy of uranium isotopic ratios measurements by thermionic mass spectrometry are discussed. A statistical designed program for the analysis of the internal and external variances are presented. It was done an application of this statistical methods, in order to get mass discrimination factor, and its standard mean deviation, by using some results already published for 235 U/ 238 U ratio in NBS uranium samples, and natural uranium [pt

R-matrix analysis of 235U neutron transmission and cross sections in the energy range 0 to 2.25 keV

International Nuclear Information System (INIS)

Leal, L.C.; Derrien, H.; Larson, N.M.; Wright, R.Q.

1997-11-01

This document describes a new R-matrix analysis of 235 U cross section data in the energy range from 0 to 2,250 eV. The analysis was performed with the computer code SAMMY, that has recently been updated to permit, for the first time, inclusion of both differential and integral data within the analysis process. Fourteen differential data sets and six integral quantities were used in this evaluation: two measurements of fission plus capture, one of fission plus absorption, six of fission alone, two of transmission, and one of eta, plus standard values of thermal cross sections for fission, capture, and scattering, and of K1 and the Westcott g-factors for both fission and absorption. An excellent representation was obtained for the high-resolution transmission, fission, and capture cross-section data as well as for the integral quantities. The result is a single set of resonance parameters spanning the entire range up to 2,250 eV, a decided improvement over the present ENDF/VI evaluation, in which eleven discrete resonance parameter sets are required to cover that same energy range. This new evaluation is expected to greatly improve predictability of the criticality safety margins for nuclear systems in which 235 U is present

Measurements of neutron-induced capture and fission reactions on $^{235}$ U: cross sections and ${\\alpha}$ ratios, photon strength functions and prompt ${\\gamma}$-ray from fission

CERN Multimedia

We propose to measure the neutron-induced capture cross section of the fissile isotope $^{235}$U using a fission tagging set-up. This new set-up has been tested successfully in 2010 and combines the n_TOF 4${\\pi}$ Total Absorption Calorimeter (TAC) with MicroMegas (MGAS) fission detectors. It has been proven that such a combination of detectors allows distinguishing with very good reliability the electromagnetic cascades from the capture reactions from dominant ${\\gamma}$-ray background coming from the fission reactions. The accurate discrimination of the fission background is the main challenge in the neutron capture cross section measurements of fissile isotopes. The main results from the measurement will be the associated capture cross section and ${\\alpha}$ ratio in the resolved (0.3-2250 eV) and unresolved (2.25-30 keV) resonance regions. According to the international benchmarks and as it is mentioned in the NEA High Priority Request List (HPRL), the 235U(n,${\\gamma}$) cross section is of utmost impo...

Fission profits of thorium: Distribution in charge and mass

International Nuclear Information System (INIS)

Guarnieri, A.A.

1985-01-01

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

48 CFR 235.006-70 - Manufacturing Technology Program.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Manufacturing Technology... CONTRACTING 235.006-70 Manufacturing Technology Program. In accordance with 10 U.S.C. 2521(d), for acquisitions under the Manufacturing Technology Program— (a) Award all contracts using competitive procedures...

Preliminary study for the transport of the fuel rods of U235 enriched to 1.8 per cent

International Nuclear Information System (INIS)

Cardenas, H.; Perez, A.

1998-01-01

Transport of 1,8% U235 enriched fuel rods needs both the evaluation of the radiological risk and considerations about criticality aspects. Issues as diverse production characteristics, storage facilities in the source of origin an economical aspects have to be added to the radiological and nuclear considerations. Transport of those rods through national territory must comply with the Argentine Regulatory authority's regulations, based on the Safety Series No. 6, (ed. 1985) -as amended 1990- IAEA. Safety criteria are exposed, taking into account the amount of material to be transported, container characteristics, packaging type and expedition conditions. (author)

Isotopic composition of uranium in U3O8 by neutron induced reactions utilizing thermal neutrons from critical facility and high resolution gamma-ray spectrometry

International Nuclear Information System (INIS)

Acharya, R.; Pujari, P.K.; Goel, Lokesh

2015-01-01

Uranium in oxide and metal forms is used as fuel material in nuclear power reactors. For chemical quality control, it is necessary to know the isotopic composition (IC) of uranium i.e., 235 U to 238 U atom ratio as well as 235 U atom % in addition to its total concentration. Uranium samples can be directly assayed by passive gamma ray spectrometry for obtaining IC by utilizing 185 keV (γ-ray abundance 57.2%) of 235 U and 1001 keV (γ-ray abundance 0.837%) of 234m Pa (decay product of 238 U). However, due to low abundance of 1001 keV, often it is not practiced to obtain IC by this method as it gives higher uncertainty even if higher mass of sample and counting time are used. IC of uranium can be determined using activity ratio of neutron induced fission product of 235 U to activation product of 238 U ( 239 Np). In the present work, authors have demonstrated methodologies for determination of IC of U as well as 235 U atom% in natural ( 235 U 0.715%) and low enriched uranium (LEU, 3-20 atom % of 235 U) samples of uranium oxide (U 3 O 8 ) by utilizing ratio of counts at 185 keV γ-ray or γ-rays of fission products with respect to 277 keV of 239 Np. Natural and enriched samples (about 25 mg) were neutron irradiated for 4 hours in graphite reflector position of AHWR Critical Facility (CF) using highly thermalized (>99.9% thermal component) neutron flux (∼10 7 cm -2 s -1 )

Yields and isomeric ratio of xenon and krypton isotopes from thermal neutron fission of 235U

International Nuclear Information System (INIS)

Hsu, S.S.; Lin, J.T.; Yang, C.M.; Yu, Y.W.

1981-01-01

The experimental cumulative yields of 85 Kr/sup m/, 87 Kr, 88 Kr, 133 Xe/sup g/, 135 Xe/sup m/, and 135 Xe/sup g/ and the independent isomeric yield of 133 Xe/sup m/ in the thermal neutron fission of 235 U have been measured by the gas chromatographic method. The independent yields of 133 Xe/sup g/, 135 Xe/sup m/, and 135 Xe/sup g/ were deduced with the aid of 133 I and 135 I data. The isomeric yield ratios of 133 Xe and 135 Xe have been computed and compared with theoretical values since they have the same high spin state J = 11/2 - and low spin ground state J = 3/2 + . The influence of the shell effect on the fission isomeric yield ratio is discussed. From the measured independent yield of Xe isotopes plus the reported data, the Xe-isotopic distribution curve has been constructed. The curve is compared with the isotopic distribution curves of Xe isotopes formed in 11.5 GeV proton interactions with 238 U and Cs isotopes formed in 24 GeV proton interactions with 238 U. Upon fitting the yield curves we find that only those products with N/Z> or =1.48 fit a curve typical of a binary fission process

Prompt neutrons from {sup 236}U fission fragments

Energy Technology Data Exchange (ETDEWEB)

Boldeman, J W; Musgrove, A.R. de L.; Walsch, R L

1971-03-01

Measurements were made of prompt neutron emission in the thermal neutron fission of {sup 235}U. The mean neutron emission per fragment was obtained for particular values of the fragment mass and total kinetic energy. A direct neutron counting method was employed and a comparison made with data from previous experiments of this type. (author)

Recovery of enriched Uranium (20% U-235) from wastes obtained in the preparation of fuel elements for argonaut type reactors

International Nuclear Information System (INIS)

Uriarte, A.; Ramos, L.; Estrada, J.; del Val, J. L.

1962-01-01

Results obtained with the two following installations for recovering enriched uranium (20% U-235) from wastes obtained in the preparation of fuel elements for Argonaut type reactors are presented. Ion exchange unit to recover uranium form mother liquors resulting from the precipitation ammonium diuranate (ADU) from UO 2 F 2 solutions. Uranium recovery unit from solid wastes from the process of manufacture of fuel elements, consisting of a) waste dissolution, and b) extraction with 10% (v/v) TBP. (Author) 9 refs

Recovery of enriched Uranium (20% U-235) from wastes obtained in the preparation of fuel elements for argonaut type reactors

Energy Technology Data Exchange (ETDEWEB)

Uriarte, A; Ramos, L; Estrada, J; Val, J L. del

1962-07-01

Results obtained with the two following installations for recovering enriched uranium (20% U-235) from wastes obtained in the preparation of fuel elements for Argonaut type reactors are presented. Ion exchange unit to recover uranium form mother liquors resulting from the precipitation ammonium diuranate (ADU) from UO{sub 2}F{sub 2} solutions. Uranium recovery unit from solid wastes from the process of manufacture of fuel elements, consisting of a) waste dissolution, and b) extraction with 10% (v/v) TBP. (Author) 9 refs.

Relationships between central arterial stiffness, lean body mass, and absolute and relative strength in young and older men and women.

Science.gov (United States)

Fahs, Christopher A; Thiebaud, Robert S; Rossow, Lindy M; Loenneke, Jeremy P; Bemben, Debra A; Bemben, Michael G

2017-08-16

Relationships between muscular strength and arterial stiffness as well as between muscle mass and arterial stiffness have been observed suggesting a link between the neuromuscular system and vascular health. However, the relationship between central arterial stiffness and absolute and relative strength along with muscle mass has not been investigated in both sexes across a broad age range. The purpose of this study was to examine the relationship between central arterial stiffness and absolute and relative strength as well as between central arterial stiffness and lean body mass (LBM) in men and women across a broad age range. LBM, central arterial stiffness and strength were measured on 36 men and 35 women between the ages of 18 and 75 years. Strength was measured on five machine resistance exercises and summed as one measure of overall strength (absolute strength). Relative strength was calculated as total strength divided by LBM (relative strength). Central arterial stiffness was inversely related to both absolute (r = -0·230; P = 0·029) and relative strength (r = -0·484; P LBM (r = 0·097; P = 0·213). The relationship between central arterial stiffness and relative strength was attenuated but still present when controlling for either age, per cent body fat, LBM or mean arterial pressure. These results suggest that, across a wide age range, the expression of relative muscular strength has a stronger relationship with central arterial stiffness compared to either LBM or absolute strength. This suggests that muscle function more than muscle mass may be coupled with vascular health. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

The Study of Prompt and Delayed Muon Induced Fission. I.Total kinetic energies and mass distributions

NARCIS (Netherlands)

David, P; Hartfiel, J.; Janszen, H.; Petitjean, C.; Reist, H.W.; Polikanov, S.M.; Konijn, J.; Laat, de C.T.A.M.; Taal, A.; Krogulski, T.; Johansson, T.; Tibell, G.; Achard van Enschut, d' J.F.M.

1987-01-01

Mass yield and total kinetic energy release (TKE) distributions of fragments from prompt and delayed muon induced fission, separately, have been measured for the isotopes235U,238U,237Np and242Pu. The distributions from prompt muon induced fission are compared with the corresponding distributions

Measurement of the ROT effect in the neutron induced fission of 235U in the 0.3 eV resonance at a hot source of polarized neutrons

Directory of Open Access Journals (Sweden)

Kopatch Yuri

2018-01-01

Full Text Available The TRI and ROT asymmetries in fission of heavy nuclei have been extensively studied during more than a decade. The effects were first discovered in the ternary fission in a series of experiments performed at the ILL reactor (Grenoble by a collaboration of Russian and European institutes, and were carefully measured for a number of fissioning nuclei. Later on, the ROT effect has been observed in the emission of prompt gamma rays and neutrons in fission of 235U and 233U, although its value was an order of magnitude smaller than in the α-particle emission from ternary fission. All experiments performed so far are done with cold polarized neutrons, what assumes a mixture of several spin states, the weights of these states being not well known. The present paper describes the first attempt to get “clean” data by performing the measurement of gamma and neutron asymmetries in an isolated resonance of 235U at the POLI instrument of the FRM2 reactor in Garching.

Evaluation of errors for mass-spectrometric analysis with surface-ionization type mass-spectrometer (statistical evaluation of mass-discrimination effect)

International Nuclear Information System (INIS)

Wada, Y.

1981-01-01

The surface-ionization type mass-spectrometer is widely used as an apparatus for quality assurance, accountability and safeguarding of nuclear materials, and for this analysis it has become an important factor to statistically evaluate an analytical error which consists of a random error and a systematic error. The major factor of this systematic error was the mass-discrimination effect. In this paper, various assays for evaluating the factor of variation on the mass-discrimination effect were studied and the data obtained were statistically evaluated. As a result of these analyses, it was proved that the factor of variation on the mass-discrimination effect was not attributed to the acid concentration of sample, sample size on the filament and supplied voltage for a multiplier, but mainly to the filament temperature during the mass-spectrometric analysis. The mass-discrimination effect values β which were usually calculated from the measured data of uranium, plutonium or boron isotopic standard sample were not so significant dependently of the difference of U-235, Pu-239 or B-10 isotopic abundance. Furthermore, in the case of U and Pu, measurement conditions and the mass range of these isotopes were almost similar, and these values β were not statistically significant between U and Pu. On the other hand, the value β for boron was about a third of the value β for U or Pu, but compared with the coefficient of the correction on the mass-discrimination effect for the difference of mass-number, ΔM, these coefficient values were almost the same among U, Pu, and B.As for the isotopic analysis error of U, Pu, Nd and B, it was proved that the isotopic abundance of these elements and the isotopic analysis error were in a relationship of quadratic curves on a logarithmic-logarithmic scale

Nuclear data and measurements series: Ratio of the prompt-fission-neutron spectrum of plutonium 239 to that of uranium 235

International Nuclear Information System (INIS)

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

1986-09-01

The prompt-fission-neutron spectrum resulting from 239 Pu fission induced by 0.55 MeV incident neutrons is measured from 1.0 to 10.0 MeV relative to that of 235 U fission induced by the same incident-energy neutrons. The measurements employ the time-of-flight technique. Energy-dependent ratios of the two spectra are deduced from the measured values over the energy range 1.0 to 10.0 MeV. The experimentally-derived ratio results are compared with those calculated from ENDF/B-V, revision-2, and with results of recent microscopic measurements. Using the ENDF/B-V 235 U Watt parameters for the 235 U spectrum, the experimental measurements imply a ratio of average fission-spectrum energies of 239 Pu/ 235 U = 1.045 +- 0.003, compared to the value 1.046 calculated from ENDF/B-V, revision 2. 12 refs., 2 figs., 2 tabs

Calculation and mitigation of isotopic interferences in liquid chromatography-mass spectrometry/mass spectrometry assays and its application in supporting microdose absolute bioavailability studies.

Science.gov (United States)

Gu, Huidong; Wang, Jian; Aubry, Anne-Françoise; Jiang, Hao; Zeng, Jianing; Easter, John; Wang, Jun-sheng; Dockens, Randy; Bifano, Marc; Burrell, Richard; Arnold, Mark E

2012-06-05

A methodology for the accurate calculation and mitigation of isotopic interferences in liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) assays and its application in supporting microdose absolute bioavailability studies are reported for the first time. For simplicity, this calculation methodology and the strategy to minimize the isotopic interference are demonstrated using a simple molecule entity, then applied to actual development drugs. The exact isotopic interferences calculated with this methodology were often much less than the traditionally used, overestimated isotopic interferences simply based on the molecular isotope abundance. One application of the methodology is the selection of a stable isotopically labeled internal standard (SIL-IS) for an LC-MS/MS bioanalytical assay. The second application is the selection of an SIL analogue for use in intravenous (i.v.) microdosing for the determination of absolute bioavailability. In the case of microdosing, the traditional approach of calculating isotopic interferences can result in selecting a labeling scheme that overlabels the i.v.-dosed drug or leads to incorrect conclusions on the feasibility of using an SIL drug and analysis by LC-MS/MS. The methodology presented here can guide the synthesis by accurately calculating the isotopic interferences when labeling at different positions, using different selective reaction monitoring (SRM) transitions or adding more labeling positions. This methodology has been successfully applied to the selection of the labeled i.v.-dosed drugs for use in two microdose absolute bioavailability studies, before initiating the chemical synthesis. With this methodology, significant time and cost saving can be achieved in supporting microdose absolute bioavailability studies with stable labeled drugs.

Standard test method for isotopic abundance analysis of uranium hexafluoride and uranyl nitrate solutions by multi-collector, inductively coupled plasma-mass spectrometry

CERN Document Server

American Society for Testing and Materials. Philadelphia

2014-01-01

1.1 This test method covers the isotopic abundance analysis of 234U, 235U, 236U and 238U in samples of hydrolysed uranium hexafluoride (UF6) by inductively coupled plasma source, multicollector, mass spectrometry (ICP-MC-MS). The method applies to material with 235U abundance in the range of 0.2 to 6 % mass. This test method is also described in ASTM STP 1344. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Contribution to the study of the interaction of slow neutrons with {sup 235}U using the time-of-flight method; Contribution a l'etude par la methode du temps de vol de l'interaction de neutrons lents avec l'U{sup 235}

Energy Technology Data Exchange (ETDEWEB)

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

1964-05-15

This study concerns the properties of the excited levels of uranium 236 obtained by interaction of slow neutron with uranium 235. The experiments have been carried out at the Saclay linear electron accelerator by use of the time of flight method. In the first part of this paper, we examine the technical and physical conditions which rule the experiments: compromise between resolution and counting rate, time dispersion due to the slowing down of the neutrons and crystalline binding effects. In a second part the experimental results i.e. total, fission and ternary fission cross sections are given. The third part deals with the analysis of these results: the resonance parameters determination ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), the study of their statistical distribution and of their correlations. We tried some classifications of the resonances according to their parameters and compared these classifications to each other and to other results. At least the evidence of a cross section correlation with a range smaller than 100 eV seems to be confirmed. (author) [French] Cette etude porte sur les proprietes des niveaux excites de l'Uranium-236 obtenus par l'interaction de neutrons lents avec le {sup 235}U. La technique experimentale est celle de la spectrometrie par temps de vol, les experiences ayant ete realisees aupres de l'accelerateur lineaire d'electrons de Saclay, Dans une premiere partie nous examinons les donnees techniques et physiques conditionnant les experiences: compromis entre resolution et taux de comptage, dispersion en temps due au ralentissement des neutrons, effet des liaisons cristallines. Dans une deuxieme partie sont exposes les resultats experimentaux: sections efficaces totales, de fission et de fission ternaire du {sup 235}U. Une troisieme partie porte sur l'analyse de ces resultats: determination des parametres ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), etude de leurs distributions statistiques et des correlations entre ces

Absolute mass scale calibration in the inverse problem of the physical theory of fireballs.

Science.gov (United States)

Kalenichenko, V. V.

A method of the absolute mass scale calibration is suggested for solving the inverse problem of the physical theory of fireballs. The method is based on the data on the masses of the fallen meteorites whose fireballs have been photographed in their flight. The method may be applied to those fireballs whose bodies have not experienced considerable fragmentation during their destruction in the atmosphere and have kept their form well enough. Statistical analysis of the inverse problem solution for a sufficiently representative sample makes it possible to separate a subsample of such fireballs. The data on the Lost City and Innisfree meteorites are used to obtain calibration coefficients.

Reexamining the role of the (n ,γ f ) process in the low-energy fission of 235U and 239Pu

Science.gov (United States)

Lynn, J. E.; Talou, P.; Bouland, O.

2018-06-01

The (n ,γ f ) process is reviewed in light of modern nuclear reaction calculations in both slow and fast neutron-induced fission reactions on 235U and 239Pu. Observed fluctuations of the average prompt fission neutron multiplicity and average total γ -ray energy below 100-eV incident neutron energy are interpreted in this framework. The surprisingly large contribution of the M 1 transitions to the prefission γ -ray spectrum of 239Pu is explained by the dominant fission probabilities of 0+ and 2+ transition states, which can only be accessed from compound nucleus states formed by the interaction of s -wave neutrons with the target nucleus in its ground state, and decaying through M 1 transitions. The impact of an additional low-lying M 1 scissors mode in the photon strength function is analyzed. We review experimental evidence for fission fragment mass and kinetic-energy fluctuations in the resonance region and their importance in the interpretation of experimental data on prompt neutron data in this region. Finally, calculations are extended to the fast energy range where (n ,γ f ) corrections can account for up to 3% of the total fission cross section and about 20% of the capture cross section.

Preparation of small uranium hexafluoride samples in view of mass spectrometry analysis; Preparation de petits echantillons d'hexafluorure d'uranium en vue d'analyse spectrometrique de masse

Energy Technology Data Exchange (ETDEWEB)

Severin, Michel

1958-07-01

We have studied the preparation of uranium hexafluoride for the determination of the isotopic ratio {sup 235}U/{sup 238}U by means of a mass spectrometer. UF{sub 6} should be produced from an amount of raw material (metallic uranium or oxide) that should not exceed 0,1 g. Our method has a good yield (we have studied the rate of transformation) and gives samples which present a content of impurities (HF and SiF{sub 4}) low enough to enable correct isotopic measurements. The method which seemed the best uses the cobalt trifluoride as a fluorining agent. It is now in current use in the laboratories of mass spectrometry. (author) [French] Nous avons etudie la preparation de l'hexafluorure d'uranium en vue de la determination au spectrometre de masse du rapport isotopique {sup 235}U/{sup 238}U. L'hexafluorure d'uranium devait etre produit a partir d'une quantite de matiere premiere (uranium metallique ou oxyde) ne devant pas exceder 0,1 g. Nous avons mis au point une methode de preparation presentant un rendement eleve (etude du taux de transformation) et donnant des echantillons dont le taux d'impuretes (HF et SiF{sub 4}) est suffisamment faible pour permettre des mesures isotopiques correctes. La methode ayant donne le plus de satisfaction utilise le trifluorure de cobalt comme agent fluorant. Ce procede est maintenant couramment employe dans les laboratoires de spectrometrie de masse. (auteur)

An approximate method to estimate the minimum critical mass of fissile nuclides

International Nuclear Information System (INIS)

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

1999-01-01

When evaluating systems in criticality safety, it is important to approximate the answer before any analysis is performed. There is currently interest in establishing the minimum critical parameters for fissile actinides. The purpose is to describe the OB-1 method for estimating the minimum critical mass for thermal systems based on one-group calculations and 235 U spheres fully reflected by water. The observation is made that for water-moderated, well-thermalized systems, the transport and leakage from the system are dominated by water. Under these conditions two fissile mixtures will have nearly the same critical volume provided the infinite media multiplication factor (k ∞ ) for the two systems is the same. This observation allows for very simple estimates of critical concentration and mass as a function of the hydrogen-to-fissile (H/X) moderation ratio by comparison to the known 235 U system

Mass and abundance 236U sensitivities at CIRCE

Science.gov (United States)

De Cesare, M.; De Cesare, N.; D'Onofrio, A.; Fifield, L. K.; Gialanella, L.; Terrasi, F.

2015-10-01

The actinides (e.g. 236U and xPu isotopes) are present in environmental samples at the ultra trace level since atmospheric tests of NWs (Nuclear Weapons) performed in the past, deliberate dumping of nuclear waste, nuclear fuel reprocessing, on a large scale and operation of NPPs (Nuclear Power Plants) on a small scale have led to the release of a wide range of radioactive nuclides in the environment. Their detection requires the most sensitive AMS (Accelerator Mass Spectrometry) techniques and at the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) in Caserta, Italy, an upgraded actinide AMS system, based on a 3-MV pelletron tandem accelerator, has been operated. In this paper the progress made in order to push the 236U mass sensitivity and 236U/238U isotopic ratio down to the natural levels is reported. A uranium contamination mass of about 0.05 μg and a 236U/238U isotopic ratio sensitivities at the level of 3.2 × 10-13 are presently achievable.

Delayed neutron spectra from short pulse fission of uranium-235

International Nuclear Information System (INIS)

Atwater, H.F.; Goulding, C.A.; Moss, C.E.; Pederson, R.A.; Robba, A.A.; Wimett, T.F.; Reeder, P.; Warner, R.

1986-01-01

Delayed neutron spectra from individual short pulse (∼50 μs) fission of small 235 U samples (50 mg) were measured using a small (5 cm OD x 5 cm length) NE 213 neutron spectrometer. The irradiating fast neutron flux (∼10 13 neutrons/cm 2 ) for these measurements was provided by the Godiva fast burst reactor at the Los Alamos Critical Experiment Facility (LACEF). A high speed pneumatic transfer system was used to transfer the 50 mg 235 U samples from the irradiation position near the Godiva assembly to a remote shielded counting room containing the NE 213 spectrometer and associated electronics. Data were acquired in sixty-four 0.5 s time bins and over an energy range 1 to 7 MeV. Comparisons between these measurements and a detailed model calculation performed at Los Alamos is presented

Absolute calibration of the mass scale in the inverse problem of the physical theory of fireballs

Science.gov (United States)

Kalenichenko, V. V.

1992-08-01

A method of the absolute calibration of the mass scale is proposed for solving the inverse problem of the physical theory of fireballs. The method is based on data on the masses of fallen meteorites whose fireballs have been photographed in flight. The method can be applied to fireballs whose bodies have not experienced significant fragmentation during their flight in the atmosphere and have kept their shape relatively well. Data on the Lost City and Innisfree meteorites are used to calculate the calibration coefficients.

Development and application of a detector for absolute measurement of neutron fluence rate in MeV region

International Nuclear Information System (INIS)

Silva Dias, M. da.

1988-01-01

The development and performance of the DTS (Dual Thin Scintillator) for the absolute measurement of the neutron fluence rate between 1 and 15 MeV is decribed. The DTS detector consists of a pair of organic scintillators in a dual configuration, where the incident produces a proton-recoil which is detected in a 2Π geometry therefore avoiding the effect of the escape of protons. Thin scintillators are used resulting in small multiple scattering corrections. The theoretical caluclations of detector efficiency and proton-recoil spectrum were performed by means of a Monte Carlos code - CARLO DTS. The calculated efficiency was compared to the experimental one at two neutron energies namely 2.446 MeV and 14.04 MeV applying the Time Correlated Associated Particle technique. The theoretical and experimental efficiencies agreed within the experimental uncertainties of 1.44% and 0.77%, respectively. The performance of the DTS has been verified in an absolute 235 U(n,f) cross section measurement between 1 and 6 MeV neutron energy. The cross section results were compared to those obtained replacing the DTS detector by the NBS (National Bureau of Standards, USA) Black Neutron Detector. The agreement was excellent in the overlapping energy interval of the two experiments (between 1 and 3 MeV), within the estimated uncertainly in the range of 1,0 to 1,7%. The agreement with the most recent evaluation from the ENDF/B-VI was excellent in almost all the energy range between 1 and 6 MeV. The 235 U(n,f) cross section, average over the 252 Cf fission neutron spectrum has been evaluated. The result including the cross section values of the present work was 1220 mb, in excellent agreement with the average value among the most recent measurements, 1227 +- 12 mb, and with the value 1213 mb, using the ENDF/B-VI data. (author) [pt

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

International Nuclear Information System (INIS)

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

1991-01-01

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

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

International Nuclear Information System (INIS)

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

1982-01-01

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

Coupling of mass and charge distributions for low excited nuclear fission

International Nuclear Information System (INIS)

Salamatin, V.S.; )

2000-01-01

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

Material control and accountability aspects of safeguards for the USA 233U/Th fuel recycle plant

International Nuclear Information System (INIS)

Carpenter, J.A. Jr.; McNeany, S.R.; Angelini, P.; Holder, N.D.; Abraham, L.

1978-01-01

The materials control and accountability aspects of the reprocessing and refabrication of a conceptual large-scale HTGR fuel recycle plant have been discussed. Two fuel cycles were considered. The traditional highly enriched uranium cycle uses an initial or makeup fuel element with a fissile enrichment of 93% 235 U. The more recent medium enriched uranium cycle uses initial or makeup fuel elements with a fissile enrichment less than 20% 235 U. In both cases, 233 U bred from the fertile thorium is recycled. Materials control and accountability in the plant will be by means of a real-time accountability method. Accountability data will be derived from monitoring of total material mass through the processes and a system of numerous assays, both destructive and nondestructive

Contribution to the study of the interaction of slow neutrons with {sup 235}U using the time-of-flight method; Contribution a l'etude par la methode du temps de vol de l'interaction de neutrons lents avec l'U{sup 235}

Energy Technology Data Exchange (ETDEWEB)

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

1964-05-15

This study concerns the properties of the excited levels of uranium 236 obtained by interaction of slow neutron with uranium 235. The experiments have been carried out at the Saclay linear electron accelerator by use of the time of flight method. In the first part of this paper, we examine the technical and physical conditions which rule the experiments: compromise between resolution and counting rate, time dispersion due to the slowing down of the neutrons and crystalline binding effects. In a second part the experimental results i.e. total, fission and ternary fission cross sections are given. The third part deals with the analysis of these results: the resonance parameters determination ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), the study of their statistical distribution and of their correlations. We tried some classifications of the resonances according to their parameters and compared these classifications to each other and to other results. At least the evidence of a cross section correlation with a range smaller than 100 eV seems to be confirmed. (author) [French] Cette etude porte sur les proprietes des niveaux excites de l'Uranium-236 obtenus par l'interaction de neutrons lents avec le {sup 235}U. La technique experimentale est celle de la spectrometrie par temps de vol, les experiences ayant ete realisees aupres de l'accelerateur lineaire d'electrons de Saclay, Dans une premiere partie nous examinons les donnees techniques et physiques conditionnant les experiences: compromis entre resolution et taux de comptage, dispersion en temps due au ralentissement des neutrons, effet des liaisons cristallines. Dans une deuxieme partie sont exposes les resultats experimentaux: sections efficaces totales, de fission et de fission ternaire du {sup 235}U. Une troisieme partie porte sur l'analyse de ces resultats: determination des parametres ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), etude de leurs distributions statistiques et

Effective K quantum numbers in fission of oriented 235U

International Nuclear Information System (INIS)

Dabbs, J.W.T.; Eggerman, C.; Cauvin, B.; Michaudon, A.; Sanche, M.

1969-01-01

The angular anisotropy of fission fragments produced in neutron-induced fission of aligned 235 U nuclei has been measured for neutron energies between 0.3 eV and 175 eV, using time-of-flight techniques at the pulsed 45 MeV electron linear accelerator at Saclay. The low-temperature nuclear-alignment apparatus used was a modified version of the apparatus described at the Salzburg conference, and gave an average temperature of 0.61 K for the four UO 2 Rb(NO 3 ) 3 single crystal samples during a measurement period of approximately 220 h. The flight path was 5 m and the election pulse length was 100 ns. Multilevel fits to the observed 0 deg and 90 deg fission cross-sections have been made using the Adler and Adler formalism with the aid of a program developed by G. de Saussure. The most striking result obtained in the analysis of some 16 of 100 levels or groups of levels is a strong correlation between small fission width and an effective value of K ≅ J. All 5 resonances in the group of 16 for which results are final, for which K ≅ J is deduced, have exceptionally small widths. This result suggests that the small widths are associated with a large rotational energy and consequent diminution in available deformation energy, so that these 5 resonances are effectively sub-threshold resonances; such a suggestion is quite in accord with the ideas of Bohr. The preponderance of other resonances so far analysed have effective K values of 1 or 2. An analysis of all resolvable resonances is presented. (author)

Prompt fission neutron spectra of n + 235U above the (n, nf) fission threshold

International Nuclear Information System (INIS)

Shu Nengchuan; Chen Yongjing; Liu Tingjin; Jia Min

2015-01-01

Calculations of prompt fission neutron spectra (PFNS) from the 235 U(n, f) reaction were performed with a semi-empirical method for En = 7.0 and 14.7 MeV neutron energies. The total PFNS were obtained as a superposition of (n, xnf) pre-fission neutron spectra and post-fission spectra of neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as an expression of the evaporation spectrum. The contributions of (n, xnf) fission neutron spectra on the calculated PFNS were discussed. The results show that emission of one or two neutrons in the (n, nf) or (n, 2nf) reactions influences the PFNS shape, and the neutron spectra of the (n, xnf) fission-channel are soft compared with the neutron spectra of the (n, f) fission channel. In addition, analysis of the multiple-chance fission component showed that second-chance fission dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission dominates the 7 MeV case. (authors)

Optogalvanic measurement of isotope shifts of doubly ionized uranium (U III) made using natural-U samples

International Nuclear Information System (INIS)

Piyakis, K.N.; Gagne, J.

1989-01-01

An efficient method of identifying 235 U III (in natural-U samples), with the help of the optogalvanic effect in a hollow-cathode discharge, is presented. The use of this method enabled us to carry out the measurement of isotope shifts and the preliminary investigation of hyperfine structures of U III. The 238 U-- 235 U shifts for the 591.313-, 586.045-, and 610.497-nm U III lines are found to be 921(3), 417(6), and 392(12) mK, respectively

Absolute measurement of thermal neutron fluence and its application for fission track dating

International Nuclear Information System (INIS)

Ganzawa, Yoshihiro; Honda, Teruyuki; Nozaki, Tetsuya.

1988-01-01

The absolute measurements of thermal neutron fluence for fission track dating have been developed after the proceeding results of Honda et al. (1987). The 2,200 m/sec activation cross section of 197 Au (98.8 barn) is corrected to 87.4 barn (σa) by the three factors of the neutron temperature, Maxwellian distribution of thermal neutrons and non 1/v correction factor for the above absolute measurement. The calibrated factor (B th ) of standard glasses (SRM613, SRM962a, CN-1 and CN-2) and zeta-a (ζa) values for fission track dating are determined on the basis of these experimental results. The values of B th , (7.47 ± 0.29) x 10 9 for SRM613, (7.43 ± 0.34) x 10 9 for SRM962a, (2.50 ± 0.06) x 10 9 for CN-1 and (2.74 ± 0.06) x 10 9 for CN-2 closely agree with those reported previously by Honda et al. (1987). Further, the ζa values of 392.3 ± 16.5 for SRM962a and SRM613, 131.4 ± 3.1 for CN-1 and 144.1 ± 3.3 for CN-2 calculated from B th , effective thermal neutron fission cross-section σf (497.4 barn), isotopic abundance ratio 235 U/ 239 U, I (7.2527 x 10 -3 ) and spontaneous fission decay constant of 238 U, λ f (6.85 x 10 -17 a -7 ) show close agreement with ζ b values (392.5 ± 10.0, 131.6 ± 3.3, 140.1 ± 3.5) derived from the absolute age of Fish Canyon Tuff (27.9 ± 0.7 Ma) respectively. The fission track dating of zircons separated from Oligocene-Miocene tuff distributed in Eastern Hokkaido have been carried out by the external detector method using ζ a . The obtained ages are 28.6 ± 0.7 Ma (1 - 2) and 23.3 ± 0.7 Ma (3 - 2). These results agree well with the geologic age supported from Ashoro Fossil Fauna, K-Ar ages of volcanic rocks and stratigraphy in this area. (author)

Regional and site-specific absolute humidity data for use in tritium dose calculations

International Nuclear Information System (INIS)

Etnier, E.L.

1980-01-01

Due to the potential variability in average absolute humidity over the continental U.S., and the dependence of atmospheric 3 H specific activity on absolute humidity, availability of regional absolute humidity data is of value in estimating the radiological significance of 3 H releases. Most climatological data are in the form of relative humidity, which must be converted to absolute humidity for dose calculations. Absolute humidity was calculated for 218 points across the U.S., using the 1977 annual summary of U.S. Climatological Data, and is given in a table. Mean regional values are shown on a map. (author)

235Uranium isotope abundance certified reference material for gamma spectrometry EC nuclear reference material 171 certification report

International Nuclear Information System (INIS)

De Bievre, P.; Eschbach, H.L.; Lesser, R.; Meyer, H.; Audenhove, Van J.

1986-01-01

This certification report contains the information necessary for the final certification of EC nuclear reference material 171. It is also intended to inform the user of the reference material concerned on technical/scientific details which are not given in the certificate. The report describes the reference material which consists of sets of U 3 O 8 samples with five different 235 U/U abundances, filled in cylindrical aluminium cans. The can bottom serves as window for emitted gamma radiation. The report describes how the 235 U/U abundances were characterized, how the other properties relevant for gamma measurements were determined and gives all connected results as well as those from the verification measurements. Appendix A represents the draft certificate. 32 refs

Study of Photon Strength Functions of Actinides: the case of U-235, Np-238 and Pu-241

CERN Document Server

Guerrero, C; Cano-Ott, D; Martinez, T; Mendoza, E; Villamarin, D; Colonna, N; Meaze, M H; Marrone, S; Tagliente, G; Terlizzi, R; Belloni, F; Abbondanno, U; Fujii, K; Milazzo, P M; Moreau, C; Aerts, G; Berthoumieux, E; Dridi, W; Gunsing, F; Pancin, J; Perrot, L; Plukis, A; Alvarez, H; Duran, I; Paradela, C; Andriamonje, S; Calviani, M; Chiaveri, E; Gonzalez-Romero, E; Kadi, Y; Vicente, M C; Vlachoudis, V; Andrzejewski, J; Marganiec, J; Assimakopoulos, P; Karadimos, D; Karamanis, D; Papachristodoulou, C; Patronis, N; Audouin, L; David, S; Ferrant, L; Isaev, S; Stephan, C; Tassan-Got, L; Badurek, G; Jericha, E; Leeb, H; Oberhummer, H; Pigni, M T; Baumann, P; Kerveno, M; Lukic, S; Rudolf, G; Becvar, F; Krticka, M; Calvino, F; Capote, R; Carrillo De Albornoz, A; Marques, L; Salgado, J; Tavora, L; Vaz, P; Cennini, P; Dahlfors, M; Ferrari, A; Gramegna, F; Herrera-Martinez, A; Mastinu, P; Praena, J; Sarchiapone, L; Wendler, H; Chepel, V; Ferreira-Marques, R; Goncalves, I; Lindote, A; Lopes, I; Neves, F; Cortes, G; Poch, A; Pretel, C; Couture, A; Cox, J; O'brien, S; Wiescher, M; Dillman, I; Kappeler, F; Mosconi, M; Plag, R; Voss, F; Walter, S; Wisshak, K; Dolfini, R; Rubbia, C; Domingo-Pardo, C; Tain, J L; Eleftheriadis, C; Savvidis, I; Frais-Koelbl, H; Griesmayer, E; Furman, W; Konovalov, V; Goverdovski, A; Ketlerov, V; Haas, B; Haight, R; Reifarth, R; Heil, M; Igashira, M; Koehler, P; Kossionides, E; Lampoudis, C; Lozano, M; Quesada, J; Massimi, C; Vannini, G; Mengoni, A; Oshima, M; Papadopoulos, C; Vlastou, R; Pavlik, A; Pavlopoulos, P; Plompen, A; Rullhusen, P; Rauscher, T; Rosetti, M; Ventura, A

2011-01-01

The decay from excited levels in medium and heavy nuclei can be described in a statistical approach by means of Photon Strength Functions and Level Density distributions combined with the theory of the compound. The study of electromagnetic cascades following neutron capture by means of high efficiency detectors has been shown to be well suited for probing the properties of the Photon Strength Function of heavy (high level density) and/or radioactive (high background) nuclei. In this work we have investigated for the first time the validity of the recommended PSF for actinides, in particular 235U, 238Np and 241Pu. Our study includes the search for resonance structures in the PSF below Sn and draws conclusions regarding their existence and their characteristics in terms of energy, width and electromagnetic nature.

24 CFR 235.1200 - Authority.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Authority. 235.1200 Section 235... DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES MORTGAGE... § 235.1200 Authority. In accordance with the authority contained in section 235(r) of the National...

Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC

Energy Technology Data Exchange (ETDEWEB)

Magee, R. M., E-mail: rmagee@trialphaenergy.com; Clary, R.; Korepanov, S.; Jauregui, F.; Allfrey, I.; Garate, E.; Valentine, T.; Smirnov, A. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

2016-11-15

In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 10{sup 7} n/s AmBe source. The practical issues of each method are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.

High accuracy 235U(n,f) data in the resonance energy region

International Nuclear Information System (INIS)

Paradela, C.; Duran, I.; Alvarez-Pol, H.; Tassan-Got, L.; Audouin, L.; Berthier, B.; Isaev, S.; Le Naour, C.; Stephan, C.; David, S.; Ferrant, L.; Tarrio, D.; Abbondanno, U.; Tagliente, G.; Terlizzi, R.; Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W.; Gunsing, F.; Pancin, S.J.; Perrot, L.; Plukis, A.; Alvarez-Velarde, F.; Cano-Ott, D.; Gonzalez-Romero, E.; Martinez, T.; Villamarin, D.; Andrzejewski, J.; Marganiec, J.; Badurek, G.; Jericha, E.; Lederer, C.; Leeb, H.; Baumann, P.; Kerveno, M.; Lukic, S.; Rudolf, G.; Becvar, F.; Embid-Segura, M.; Krticka, M.; Vincente, M.C.; Calvino, F.; Cortes, G.; Poch, A.; Pretel, C.; Calviani, M.; Cennini, P.; Chiaveri, E.; Dahlfors, M.; Ferrari, A.; Kadi, Y.; Rubbia, C.; Sarchiapone, L.; Vlachoudis, V.; Weiss, C.; Capote, R.; Quesada, J.; Carrapico, C.; Goncalves, I.F.; Salgado, J.; Santos, C.; Tavora, L.; Vaz, P.; Chepel, V.; Ferreira-Marques, R.; Lindote, A.; Colonna, N.; Marrone, S.; Couture, A.; Cox, J.; Wiesher, M.; Dillmann, I.; Heil, M.; Kaeppeler, F.; Mosconi, M.; Plag, R.; Voss, F.; Walter, S.; Wisshak, K.; Domingo-Pardo, C.; Tain, J.L.; Eleftheriadis, C.; Lampoudis, C.; Savvidis, I.; Fujii, K.; Milazzo, P.M.; Moreau, C.; Furman, W.; Konovalov, V.; Goverdovski, A.; Ketlerov, V.; Gramegna, F.; Mastinu, P.; Praena, J.; Guerrero, C.; Haight, R.; Koehler, P.; Reifarth, R.; Igashira, M.; Karadimos, D.; Vlastou, R.; Massimi, C.; Pavlopoulos, P.; Mengoni, A.; Plompen, A.; Rullhusen, P.; Rauscher, T.; Ventura, A.; Pavlik, A.

2016-01-01

The 235 U neutron-induced cross section is widely used as reference cross section for measuring other fission cross sections, but in the resonance region it is not considered as an IAEA standard because of the scarce experimental data covering the full region. In this work, we deal with a new analysis of the experimental data obtained with a detection setup based on parallel plate ionization chambers (PPACs) at the CERN n-TOF facility in the range from 1 eV to 10 keV. The relative cross section has been normalised to the IAEA value in the region between 7.8 and 11 eV, which is claimed as well-known. Its comparison with the last IAEA reference files and with the present version of the ENDF evaluation leads to the following conclusions: 1) there is very good agreement with the shape of the ENDF cross-section in the resolved resonance range, while showing a lower background; 2) the ENDF integral values, apart from a 2% difference in the normalisation value at 7.8-11.0 eV, show a sharp drop at the transition from the resolved to the unresolved resonance energy regions; And 3) There is a very good agreement with the IAEA integral-data set, provided that an offset of 0.09 barn is applied in the whole energy range

A three-parameter neutrino mass matrix with maximal CP violation

International Nuclear Information System (INIS)

Grimus, W.; Lavoura, L.

2009-01-01

Using the seesaw mechanism, we construct a model for the light-neutrino Majorana mass matrix which yields trimaximal lepton mixing together with maximal CP violation and maximal atmospheric-neutrino mixing. We demonstrate that, in our model, the light-neutrino mass matrix retains its form under the one-loop renormalization-group evolution. With our neutrino mass matrix, the absolute neutrino mass scale is a function of |U e3 | and of the atmospheric mass-squared difference. We study the effective mass in neutrinoless ββ decay as a function of |U e3 |, showing that it contains a fourfold ambiguity

Ranges of the fragments from thermal (slow) neutron fission of /sup 235/U in water

Energy Technology Data Exchange (ETDEWEB)

Gu, H; Chao, Z; Sheng, Z; Wang, L; Feng, X

1980-05-01

According to the principle of thick target, we used the aqueous solutions of uranyl chloride of various concentrations as thick targets and platinum plates of known surface area as absorbers immersed in the target solutions. The ranges of the U(n, f) fission fragments /sup 89/Sr, /sup 91/Y, /sup 140/Ba, /sup 141/Ce and /sup 144/Ce in the aqueous solutions of uranyl chloride of various concentrations were determined. In the concentration region of 0.16 U% - 6.2 U%, the uranium concentration had no significant effect on the measurement of the range. Therefore, the ranges of the fission fragments in diluted UO/sub 2/Cl/sub 2/ solutions are very close to those in pure water, and the mean value of the ranges in UO/sub 2/Cl/sub 2/ solutions of various concentrations was taken as the range in water. The experimental results of the ranges of these five fission fragments in water were: R/sub Sr-90/ = 2.39 +- 0.04 mgcm/sup -2/, R/sub Y-91/ = 2.35 +- 0.09 mgcm/sup -2/, R/sub Ba-140/ = 1.92 +- 0.07 mgcm/sup -2/, R/sub Ce-141/ = 1.91 +- 0.12 mgcm/sup -2/, R/sub Ce-144/ = 1.84 +- 0.10 mgcm/sup -2/. In order to estimate the effect of back scattering of fission fragments in platinum plate, we did the experiments using stainless steel plate as absorber (the aqueous solutions of uranyl chloride as thick targets). The results were similar. Thus, the effect of back scattering was not significant. This work provides a convenient means for determining the ranges of the fission fragments in a liquid.

Mass and abundance {sup 236}U sensitivities at CIRCE

Energy Technology Data Exchange (ETDEWEB)

De Cesare, M., E-mail: m.decesare@cira.it [Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, ACT 0200 Canberra (Australia); CIRCE and Dipartimento di Matematica e Fisica, Seconda Universitá di Napoli, via Vivaldi 43, 81100 Caserta (Italy); De Cesare, N.; D’Onofrio, A. [CIRCE and Dipartimento di Matematica e Fisica, Seconda Universitá di Napoli, via Vivaldi 43, 81100 Caserta (Italy); INFN Sezione di Napoli, via Cintia, Edificio G, 80126 Napoli (Italy); Fifield, L.K. [Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, ACT 0200 Canberra (Australia); Gialanella, L.; Terrasi, F. [CIRCE and Dipartimento di Matematica e Fisica, Seconda Universitá di Napoli, via Vivaldi 43, 81100 Caserta (Italy); INFN Sezione di Napoli, via Cintia, Edificio G, 80126 Napoli (Italy)

2015-10-15

The actinides (e.g. {sup 236}U and {sup x}Pu isotopes) are present in environmental samples at the ultra trace level since atmospheric tests of NWs (Nuclear Weapons) performed in the past, deliberate dumping of nuclear waste, nuclear fuel reprocessing, on a large scale and operation of NPPs (Nuclear Power Plants) on a small scale have led to the release of a wide range of radioactive nuclides in the environment. Their detection requires the most sensitive AMS (Accelerator Mass Spectrometry) techniques and at the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) in Caserta, Italy, an upgraded actinide AMS system, based on a 3-MV pelletron tandem accelerator, has been operated. In this paper the progress made in order to push the {sup 236}U mass sensitivity and {sup 236}U/{sup 238}U isotopic ratio down to the natural levels is reported. A uranium contamination mass of about 0.05 μg and a {sup 236}U/{sup 238}U isotopic ratio sensitivities at the level of 3.2 × 10{sup −13} are presently achievable.

Cumulative fission yield of Ce-148 produced by thermal-neutron fission of U-235

International Nuclear Information System (INIS)

Hasan, A.A.

1984-12-01

Cumulative fission yield of 148 cesium isotopes and some other fission products produced by thermal-neutron fission of 235 uranium is determined by Germanium/Lithium spectroscopic methods. The measuremets were done at Tsing-Hua open pool reactor using 3 to 4 mg of 93.15% enriched 235 uranium samples. Gamma rays are assigned to the responsible fission products by matching gamma rays energies and half lives. Fission rate is calculated by fission track method. Cumulative fission yields of 148 cesium, 90 krypton, 130 iodine, 144 lanthanum, 89 krypton, 136 xenon, 137 xenon and 140 cesium are calculated. This values are compared with previously predicted values and showed good agreement. 21 Ref

Decay scheme of the U235

International Nuclear Information System (INIS)

Gaeta, R.

1965-01-01

A study of the Th 2 31 excited levels from the alpha decay of the U 2 35, is carried out. The alpha particle spectrum was measured by means of a semiconductor counter spectrometer with an effective resolution of 18 keV. Nineteen new lines were identified. The gamma-ray spectrum was measured with thin samples of U 2 35, free from decay products, and in such geometrical conditions, that most of the interference effects were eliminated. The gamma-gamma coincidence spectra have made easier a better knowledge of the transition between the several levels. (Author) 110 refs

Prompt fission neutron spectra from fission induced by 1 to 8 MeV neutrons on 235U and 239Pu using the double time-of-flight technique

International Nuclear Information System (INIS)

Noda, S.; Haight, R. C.; Nelson, R. O.; Devlin, M.; O'Donnell, J. M.; Chatillon, A.; Granier, T.; Belier, G.; Taieb, J.; Kawano, T.; Talou, P.

2011-01-01

Prompt fission neutron spectra from 235 U and 239 Pu were measured for incident neutron energies from 1 to 200 MeV at the Weapons Neutron Research facility (WNR) of the Los Alamos Neutron Science Center, and the experimental data were analyzed with the Los Alamos model for the incident neutron energies of 1-8 MeV. A CEA multiple-foil fission chamber containing deposits of 100 mg 235 U and 90 mg 239 Pu detected fission events. Outgoing neutrons were detected by the Fast Neutron-Induced γ-Ray Observer array of 20 liquid organic scintillators. A double time-of-flight technique was used to deduce the neutron incident energies from the spallation target and the outgoing energies from the fission chamber. These data were used for testing the Los Alamos model, and the total kinetic energy parameters were optimized to obtain a best fit to the data. The prompt fission neutron spectra were also compared with the Evaluated Nuclear Data File (ENDF/B-VII.0). We calculate average energies from both experimental and calculated fission neutron spectra.

Targeted disruption of py235ebp-1: Invasion of erythrocytes by Plasmodium yoelii using an alternative py235 erythrocyte binding protein

KAUST Repository

Ogun, Solabomi A.

2011-02-17

Plasmodium yoelii YM asexual blood stage parasites express multiple members of the py235 gene family, part of the super-family of genes including those coding for Plasmodium vivax reticulocyte binding proteins and Plasmodium falciparum RH proteins. We previously identified a Py235 erythrocyte binding protein (Py235EBP-1, encoded by the PY01365 gene) that is recognized by protective mAb 25.77. Proteins recognized by a second protective mAb 25.37 have been identified by mass spectrometry and are encoded by two genes, PY01185 and PY05995/PY03534. We deleted the PY01365 gene and examined the phenotype. The expression of the members of the py235 family in both the WT and gene deletion parasites was measured by quantitative RT-PCR and RNA-Seq. py235ebp-1 expression was undetectable in the knockout parasite, but transcription of other members of the family was essentially unaffected. The knockout parasites continued to react with mAb 25.77; and the 25.77-binding proteins in these parasites were the PY01185 and PY05995/PY03534 products. The PY01185 product was also identified as erythrocyte binding. There was no clear change in erythrocyte invasion profile suggesting that the PY01185 gene product (designated PY235EBP-2) is able to fulfill the role of EBP-1 by serving as an invasion ligand although the molecular details of its interaction with erythrocytes have not been examined. The PY01365, PY01185, and PY05995/PY03534 genes are part of a distinct subset of the py235 family. In P. falciparum, the RH protein genes are under epigenetic control and expression correlates with binding to distinct erythrocyte receptors and specific invasion pathways, whereas in P. yoelii YM all the genes are expressed and deletion of one does not result in upregulation of another. We propose that simultaneous expression of multiple Py235 ligands enables invasion of a wide range of host erythrocytes even in the presence of antibodies to one or more of the proteins and that this functional

Targeted disruption of py235ebp-1: Invasion of erythrocytes by Plasmodium yoelii using an alternative py235 erythrocyte binding protein

KAUST Repository

Ogun, Solabomi A.; Tewari, Rita; Otto, Thomas D.; Howell, Steven A.; Knuepfer, Ellen; Cunningham, Deirdre A.; Xu, Zhengyao; Pain, Arnab; Holder, Anthony A.

2011-01-01

Plasmodium yoelii YM asexual blood stage parasites express multiple members of the py235 gene family, part of the super-family of genes including those coding for Plasmodium vivax reticulocyte binding proteins and Plasmodium falciparum RH proteins. We previously identified a Py235 erythrocyte binding protein (Py235EBP-1, encoded by the PY01365 gene) that is recognized by protective mAb 25.77. Proteins recognized by a second protective mAb 25.37 have been identified by mass spectrometry and are encoded by two genes, PY01185 and PY05995/PY03534. We deleted the PY01365 gene and examined the phenotype. The expression of the members of the py235 family in both the WT and gene deletion parasites was measured by quantitative RT-PCR and RNA-Seq. py235ebp-1 expression was undetectable in the knockout parasite, but transcription of other members of the family was essentially unaffected. The knockout parasites continued to react with mAb 25.77; and the 25.77-binding proteins in these parasites were the PY01185 and PY05995/PY03534 products. The PY01185 product was also identified as erythrocyte binding. There was no clear change in erythrocyte invasion profile suggesting that the PY01185 gene product (designated PY235EBP-2) is able to fulfill the role of EBP-1 by serving as an invasion ligand although the molecular details of its interaction with erythrocytes have not been examined. The PY01365, PY01185, and PY05995/PY03534 genes are part of a distinct subset of the py235 family. In P. falciparum, the RH protein genes are under epigenetic control and expression correlates with binding to distinct erythrocyte receptors and specific invasion pathways, whereas in P. yoelii YM all the genes are expressed and deletion of one does not result in upregulation of another. We propose that simultaneous expression of multiple Py235 ligands enables invasion of a wide range of host erythrocytes even in the presence of antibodies to one or more of the proteins and that this functional

Targeted disruption of py235ebp-1: invasion of erythrocytes by Plasmodium yoelii using an alternative Py235 erythrocyte binding protein.

Directory of Open Access Journals (Sweden)

Solabomi A Ogun

2011-02-01

Full Text Available Plasmodium yoelii YM asexual blood stage parasites express multiple members of the py235 gene family, part of the super-family of genes including those coding for Plasmodium vivax reticulocyte binding proteins and Plasmodium falciparum RH proteins. We previously identified a Py235 erythrocyte binding protein (Py235EBP-1, encoded by the PY01365 gene that is recognized by protective mAb 25.77. Proteins recognized by a second protective mAb 25.37 have been identified by mass spectrometry and are encoded by two genes, PY01185 and PY05995/PY03534. We deleted the PY01365 gene and examined the phenotype. The expression of the members of the py235 family in both the WT and gene deletion parasites was measured by quantitative RT-PCR and RNA-Seq. py235ebp-1 expression was undetectable in the knockout parasite, but transcription of other members of the family was essentially unaffected. The knockout parasites continued to react with mAb 25.77; and the 25.77-binding proteins in these parasites were the PY01185 and PY05995/PY03534 products. The PY01185 product was also identified as erythrocyte binding. There was no clear change in erythrocyte invasion profile suggesting that the PY01185 gene product (designated PY235EBP-2 is able to fulfill the role of EBP-1 by serving as an invasion ligand although the molecular details of its interaction with erythrocytes have not been examined. The PY01365, PY01185, and PY05995/PY03534 genes are part of a distinct subset of the py235 family. In P. falciparum, the RH protein genes are under epigenetic control and expression correlates with binding to distinct erythrocyte receptors and specific invasion pathways, whereas in P. yoelii YM all the genes are expressed and deletion of one does not result in upregulation of another. We propose that simultaneous expression of multiple Py235 ligands enables invasion of a wide range of host erythrocytes even in the presence of antibodies to one or more of the proteins and that this

Accurate isotope ratio mass spectrometry. Some problems and possibilities

International Nuclear Information System (INIS)

Bievre, P. de

1978-01-01

The review includes reference to 190 papers, mainly published during the last 10 years. It covers the following: important factors in accurate isotope ratio measurements (precision and accuracy of isotope ratio measurements -exemplified by determinations of 235 U/ 238 U and of other elements including 239 Pu/ 240 Pu; isotope fractionation -exemplified by curves for Rb, U); applications (atomic weights); the Oklo natural nuclear reactor (discovered by UF 6 mass spectrometry at Pierrelatte); nuclear and other constants; isotope ratio measurements in nuclear geology and isotope cosmology - accurate age determination; isotope ratio measurements on very small samples - archaeometry; isotope dilution; miscellaneous applications; and future prospects. (U.K.)

Absolute dimensions and masses of eclipsing binaries. V. IQ Persei

International Nuclear Information System (INIS)

Lacy, C.H.; Frueh, M.L.; McDonald Observatory, Austin)

1985-01-01

New photometric and spectroscopic observations of the 1.7 day eclipsing binary IQ Persei (B8 + A6) have been analyzed to yield very accurate fundamental properties of the system. Reticon spectroscopic observations obtained at McDonald Observatory were used to determine accurate radial velocities of both stars in this slightly eccentric large light-ratio binary. A new set of VR light curves obtained at McDonald Observatory were analyzed by synthesis techniques, and previously published UBV light curves were reanalyzed to yield accurate photometric orbits. Orbital parameters derived from both sets of photometric observations are in excellent agreement. The absolute dimensions, masses, luminosities, and apsidal motion period (140 yr) derived from these observations agree well with the predictions of theoretical stellar evolution models. The A6 secondary is still very close to the zero-age main sequence. The B8 primary is about one-third of the way through its main-sequence evolution. 27 references

Critical experiments on low-enriched uranium oxide system with H/U=1.25

International Nuclear Information System (INIS)

Oh, I.; Rothe, R.E.; Tuck, G.

1982-01-01

Fifteen (15) critical experiments were performed on a horizontal split table machine using 4.48%-enriched sup(235)U uranium oxide(U 3 O 8 ). The oxide was compacted to a density of 4.68g/cm 3 and placed in 152 mm cubical aluminum cans. Water was added to achive an H/U of 1.25. Various arrays of oxide cans were distributed on each half of the split table, and the separation between halves reduced until criticality occurred. The critical table separation varied from 3.59 mm to 18.40 mm. Twelve (12) experiments required the addition of a high-enriched(-93 %sup(235)U) metal or solution driver to achieve criticality. These experiments were performed in a plastic, concrete, or thin steel reflector. Three additional experiments in the plastic reflector contained either 9.3-mm- or 24.3-mm-thick plastic moderator material between the oxide cans and did not require a driver to achieve criticality. Critical uranium driver masses ranged from 9.999 kg to 14.000 kg (solution driver), and from 25.378 kg to 29.278 kg (metal driver) for 5X5X5 arrays of uranium oxide cans. Always, one or four of these 125 cans had to be removed to make room for the drivers. Therefore, the uranium oxide masses used were 1823.8 kg and 1863.5 kg. For the moderated experiments, the uranium oxide mass ranged between 574.4 kg and 1210.0 kg. (Author)

Nuclear reactor for breeding 233U

International Nuclear Information System (INIS)

Bohanan, C.S.; Jones, D.H.; Raab, H.F. Jr.; Radkowsky, A.

1976-01-01

A light-water-cooled nuclear reactor capable of breeding 233 U for use in a light-water breeder reactor includes physically separated regions containing 235 U fissile material and 238 U fertile material and 232 Th fertile material and 239 Pu fissile material, if available. Preferably the 235 U fissile material and 238 U fertile material are contained in longitudinally movable seed regions and the 239 Pu fissile material and 232 Th fertile material are contained in blanket regions surrounding the seed regions. 1 claim, 5 figures

Comparison of the ENDF/B-V and SOKRATOR evaluations of 235U, 239Pu, 240Pu and 241Pu at low neutron energies

International Nuclear Information System (INIS)

de Saussure, G.; Wright, R.Q.

1981-01-01

The US and USSR's most recent evaluationsof 235 U, 239 Pu, 240 Pu and 241 Pu are compared over the thermal region and over the first few resonances. The two evaluations rest on essentially the same experimental data base and the differences reflect different approaches to the representation of the cross sections or different weightings of the experimental results. It is found that over the thermal and resolved ranges the two evaluations are very similar. Some differences in approaches are briefly discussed

The D1Πu state of HD and the mass scaling relation of its predissociation widths

Science.gov (United States)

Dickenson, G. D.; Ubachs, W.

2012-07-01

Absorption spectra of HD have been recorded in the wavelength range of 75-90 nm at 100 K using the vacuum ultraviolet Fourier transform spectrometer at the Synchrotron SOLEIL. The present wavelength resolution represents an order of magnitude improvement over that of previous studies. We present a detailed study of the D1Πu-X1Σ+g system observed up to v‧ = 18. The Q-branch transition probing levels of Π- symmetry are observed as narrow resonances limited by the Doppler width at 100 K. Line positions for these transitions are determined to an estimated absolute accuracy of 0.06 cm-1. Predissociation line widths of Π+ levels are extracted from the absorption spectra. A comparison with the recent results on a study of the D1Πu state in H2 and D2 reveals that the predissociation widths scale as μ-2J(J + 1), with μ being the reduced mass of the molecule and J the rotational angular momentum quantum number, as expected from an interaction with the B‧1Σ+u continuum causing the predissociation.

Upper bounds on Higgs and top quark masses in the flipped SU(5)xU(1) superstring model

Energy Technology Data Exchange (ETDEWEB)

Durand, L.; Lopez, J.L.

1989-02-02

In this letter, we use a simplified method to calculate high-energy unitarity constraints on grand unified broken supersymmetric models. We apply the method to the ''flipped'' SU(5)xU(1) superstring model, obtain the constraints at a grand unified mass scale M/sub G/=4x10/sup 16/ GeV, and then use the renormalization group equations to evolve the constraints to the low-energy mass scale M/sub W/. We find upper bounds on the low-energy superpotential parameters which in turn imply absolute upper bounds on the top quark mass, m/sub t/< or approx.200 GeV, and on the lightest neutral Higgs boson mass, Msub(H/sub 1//sup 0/)< or approx.155 GeV. We also obtain an upper bound on Msub(H/sub 1//sup 0/) as a function of m/sub t/ which shows that for favored values of the ratio of Higgs vacuum expectation values Msub(H/sub 1//sup 0/)< or approx.125 GeV.

Standard specification for uranium metal enriched to more than 15 % and less Than 20 % 235U

CERN Document Server

American Society for Testing and Materials. Philadelphia

2000-01-01

1.1 This specification covers nuclear grade uranium metal that has either been processed through an enrichment plant, or has been produced by the blending of highly enriched uranium with other uranium, to obtain uranium of any 235U concentration below 20 % (and greater than 15 %) and that is intended for research reactor fuel fabrication. The scope of this specification includes specifications for enriched uranium metal derived from commercial natural uranium, recovered uranium, or highly enriched uranium. Commercial natural uranium, recovered uranium and highly enriched uranium are defined in Section 3. The objectives of this specification are to define the impurity and uranium isotope limits for commercial grade enriched uranium metal. 1.2 This specification is intended to provide the nuclear industry with a standard for enriched uranium metal which is to be used in the production of research reactor fuel. In addition to this specification, the parties concerned may agree to other appropriate conditions. ...

Absolute Properties of the Pulsating Post-mass Transfer Eclipsing Binary OO Draconis

Science.gov (United States)

Lee, Jae Woo; Hong, Kyeongsoo; Koo, Jae-Rim; Park, Jang-Ho

2018-01-01

OO Dra is a short-period Algol system with a δ Sct-like pulsator. We obtained time-series spectra between 2016 February and May to derive the fundamental parameters of the binary star and to study its evolutionary scenario. The radial velocity (RV) curves for both components were presented, and the effective temperature of the hotter and more massive primary was determined to be {T}{eff,1}=8260+/- 210 K by comparing the disentangling spectrum and the Kurucz models. Our RV measurements were solved with the BV light curves of Zhang et al. using the Wilson-Devinney binary code. The absolute dimensions of each component are determined as follows: M 1 = 2.03 ± 0.06 {M}⊙ , M 2 = 0.19 ± 0.01 {M}⊙ , R 1 = 2.08 ± 0.03 {R}⊙ , R 2 = 1.20 ± 0.02 {R}⊙ , L 1 = 18 ± 2 {L}⊙ , and L 2 = 2.0 ± 0.2 {L}⊙ . Comparison with stellar evolution models indicated that the primary star resides inside the δ Sct instability strip on the main sequence, while the cool secondary component is noticeably overluminous and oversized. We demonstrated that OO Dra is an oscillating post-mass transfer R CMa-type binary; the originally more massive star became the low-mass secondary component through mass loss caused by stellar wind and mass transfer, and the gainer became the pulsating primary as the result of mass accretion. The R CMa stars, such as OO Dra, are thought to have formed by non-conservative binary evolution and ultimately to evolve into EL CVn stars.

Proserpine - plutonium 239 - Proserpine - uranium 235 - comparison of experimental results; Proserpine - plutonium 239 - proserpine - uranium 235 - comparaison de resultats experimentaux

Energy Technology Data Exchange (ETDEWEB)

Brunet, J P; Caizergues, R; Clouet D' Orval, Ch; Kremser, J; Moret-Bailly, J; Verriere, Ph [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The Proserpine homogeneous reactor is constituted by a tank, 25 cm dia, 30 cm high, surrounded by a composite reflector made of beryllium oxide and graphite. In this tank can be made critical plutonium or 90 per cent enriched uranium solutions, the fissile substances being in the form of a dissolved salt. In varying the concentration of the solution, critical masses were studied as a function of the level of the liquid in the tank. The minimum critical mass is 256 {+-} 2 grs for plutonium and 409 {+-} 3 grs for uranium 235. In the range of the critical concentrations which were studied, the neutronic properties of fissionable solutions of plutonium and enriched uranium were compared for identical geometries. (authors) [French] Proserpine est un reacteur homogene comportant une cuve de diametre 25 cm, de hauteur 30 cm, entouree d'un reflecteur composite d'oxyde de beryllium et de graphite. On y a rendu critiques des solutions de plutonium ou d'uranium enrichi a 90 pour cent, le produit fissile se trouvant sous la forme d'un sel dissous. En faisant varier la concentration de la solution, on a etudie les masses critiques en fonction de la hauteur du liquide dans la cuve. La masse- critique minimum est, pour le plutonium de 256 {+-} 2 g, pour l'uranium 235 de 409 {+-} 3 g. Dans la gamme des concentrations critiques etudiees, on a compare, dans des conditions de geometrie identique, les proprietes neutroniques des solutions fissiles de plutonium et d'uranium enrichi. (auteurs)

distributions for the thermal neutron induced fission of 234U

Directory of Open Access Journals (Sweden)

Al-Adili A.

2016-01-01

In addition, the analysis of thermal neutron induced fission of 234U(n,f will be discussed. Currently analysis of data is ongoing, originally taken at the ILL reactor. The experiment is of particular interest since no measurement exist of the mass and energy distributions for this system at thermal energies. One main problem encountered during analysis was the huge background of 235U(nth,f. Despite the negligible isotopic traces in the sample, the cross section difference is enormous. Solution to this parasitic background will be highlighted.

Economic Effect on the Plutonium Cycle of Employing {sup 235}U in Fast Reactor Start-Up; Incidence Economique du Demarrage des Reacteurs Rapides a l'Aide d'Uranium-235 sur le Cycle du Plutonium

Energy Technology Data Exchange (ETDEWEB)

Van Dievoet, J.; Egleme, M.; Hermans, L. [BELGONUCLEAIRE, Bruxelles (Belgium)

1967-09-15

Preliminary results are presented of a study carried out under an agreement concluded between Euratom and the Belgian Government to evaluate the advantages of loading fast reactors with {sup 235}U. There are several ways of starting up a fast reactor with {sup 235}U: (1) the reactor can be operated entirely with enriched uranium, the plutonium produced being used to start up and operate other reactors; in this case the uranium is recycled within the reactor and more enriched uranium is added; (2) the plutonium produced can be partly recycled within the reactor together with the uranium; in this case the reactor is transformed gradually into a plutonium reactor. These two procedures can be combined and applied simultaneously in different enrichment zones of the same reactor, enriched uranium being added, for example, to the internal zone and plutonium recycled in the external zone. The method of reprocessing the fuel is also a complicating factor, depending on whether the core and the axial breeding blankets are reprocessed together or separately. Similarly, where a reactor has several enrichment zones, these can likewise be reprocessed either together or separately. The calculations are performed with the help of a code that uses the equivalence coefficients defined by Baker and Ross for the part relating to the characteristics of successive reactors, and the discounted fuel cycle cost method for the economic part. In the first stage of this work a rough analysis was made. The reloading of each zone was assumed to be carried out in a single operation, and the time spent by the fuel elements out of pile was ignored. In a later stage, progressive reloading by batches will be considered, with allowance for fabrication and reprocessing times, etc. The most interesting results relate to variations in fuel composition (plutonium content, isotopic composition) from one cycle to another, variations in the fuel cycle characteristics (doubling time, loading and unloading

Coulomb and even-odd effects in cold and super-asymmetric fragmentation for thermal neutron induced fission of {sup 235}U

Energy Technology Data Exchange (ETDEWEB)

Montoya, M. [Universidad Nacional de Ingeniería, Av. Túpac Amaru 210, Rímac, Lima (Peru)

2016-07-07

Even-odd effects of the maximal total kinetic energy (K{sub max}) as a function of charge (Z) and mass (A) of fragments from thermal neutron induced fission of actinides are questioned by other authors. In this work, visiting old results on thermal neutron induced fission of {sup 235}U, those even-odd effects are reconfirmed. The cases seeming to contradict even-odd effects are interpreted with the Coulomb effect hypothesis. According to Coulomb effect hypothesis, K{sub max} is equal to the Coulomb interaction energy of the most compact scission configuration. As a consequence, between two isobaric charge splits with similar Q-values, the more asymmetrical one will get the more compact scission configuration and then it will reach the higher K{sub max}-value. In some cases, the more asymmetrical charge split corresponds, by coincidence, to an odd charge split; consequently its higher K{sub max}-value may be misinterpreted as anti-even-odd effect. Another experimental result reported in the literature is the increasing of even-odd effects on charge distribution on the more asymmetrical fragmentations region. In this region, the difference between K{sub max} and Q-values increases with asymmetry, which means that the corresponding scission configuration needs higher total deformation energy to occur. Higher deformation energy of the fragments implies lower free energy to break nucleon pairs. Consequently, in the asymmetric fragmentation region, the even-odd effects of the distribution of proton number and neutron number must increase with asymmetry.

46 CFR 108.235 - Construction.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Construction. 108.235 Section 108.235 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Helicopter Facilities § 108.235 Construction. (a) Each helicopter deck must be...

Critical experiments in AQUILON with fuels slightly enriched in uranium 235 or in plutonium; Experiences critiques dans aquilon portant sur des combustibles legerement enrichis en uranium 235 et en plutonium

Energy Technology Data Exchange (ETDEWEB)

Chabrillac, M; Ledanois, G; Lourme, P; Naudet, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

Reactivity comparisons have been, made in Aquilon II between geometrically identical lattices differing only by the composition of the fuel. The fuel elements consist in metallic uranium single rods with either slight differences of the isotopic composition (0.69 - 0.71 - 0.83 - 0.86 per cent of uranium 235) or slight additions of plutonium (0.043 per cent). Five lattices pitches have bean used, in order to produce a large variation of spectrum. Two additional sets of plutonium fuels are prepared to be used in the same conditions. The double comparisons: natural enriched 235 versus natural-enriched plutonium are made in such a way that a very precise interpretation is permitted. The results are perfectly consistent which seems to prove that the calculation methods are convenient. Further it can been inferred that the usual data, namely for the ratio of the {eta} of {sup 235}U and {sup 239}Pu seem reliable. (authors) [French] On a compare neutroniquement dans Aquilon II des reseaux geometriquement identiques mais comportant de petites differences de composition du combustible. EL s'agit de barres d'uranium metallique, les unes avec des teneurs differentes en isotopes 235 (0,69 - 0,71 - 0,83 - 0,86 pour cent) les autres comportant une legere addition de plutonium (0,043 pour cent). Les comparaisons ont ete faites a cinq pas differents, de maniere a mettre en jeu une assez large variation de spectre. Deux autres jeux de combustible au plutonium seront utilises ulterieurement dans les memes conditions. Les resultats des mesures se presentent sous forme de doubles comparaisons: naturel-enrichi 235/naturel-enrichi plutonium. On s'est place dans des conditions qui permettent des interpretations tres precises. Les resultats sont remarquablement coherents, ce qui semble montrer que les methodes de calcul sont bien adaptees, Ils tendent d'autre part a prouver que les valeurs numeriques admises dans la litterature, notamment pour le rapport des {eta} de l'U 235 et de Pu 239

7 CFR 235.3 - Administration.

Science.gov (United States)

2010-01-01

... 7 Agriculture 4 2010-01-01 2010-01-01 false Administration. 235.3 Section 235.3 Agriculture... CHILD NUTRITION PROGRAMS STATE ADMINISTRATIVE EXPENSE FUNDS § 235.3 Administration. (a) Within the Department, FNS shall act on behalf of the Department in the administration of the program for payment to...

Benchmark critical experiments on low-enriched uranium oxide systems with H/U = 0.77

International Nuclear Information System (INIS)

Tuck, G.; Oh, I.

1979-08-01

Ten benchmark experiments were performed at the Critical Mass Laboratory at Rockwell International's Rocky Flats Plant, Golden, Colorado, for the US Nuclear Regulatory Commission. They provide accurate criticality data for low-enriched damp uranium oxide (U 3 O 8 ) systems. The core studied consisted of 152 mm cubical aluminum cans containing an average of 15,129 g of low-enriched (4.46% 235 U) uranium oxide compacted to a density of 4.68 g/cm 3 and with an H/U atomic ratio of 0.77. One hundred twenty five (125) of these cans were arranged in an approx. 770 mm cubical array. Since the oxide alone cannot be made critical in an array of this size, an enriched (approx. 93% 235 U) metal or solution driver was used to achieve criticality. Measurements are reported for systems having the least practical reflection and for systems reflected by approx. 254-mm-thick concrete or plastic. Under the three reflection conditions, the mass of the uranium metal driver ranged from 29.87 kg to 33.54 kg for an oxide core of 1864.6 kg. For an oxide core of 1824.9 kg, the weight of the high concentration (351.2 kg U/m 3 ) solution driver varied from 14.07 kg to 16.14 kg, and the weight of the low concentration (86.4 kg U/m 3 ) solution driver from 12.4 kg to 14.0 kg

Absolute magnitudes by statistical parallaxes

International Nuclear Information System (INIS)

Heck, A.

1978-01-01

The author describes an algorithm for stellar luminosity calibrations (based on the principle of maximum likelihood) which allows the calibration of relations of the type: Msub(i)=sup(N)sub(j=1)Σqsub(j)Csub(ij), i=1,...,n, where n is the size of the sample at hand, Msub(i) are the individual absolute magnitudes, Csub(ij) are observational quantities (j=1,...,N), and qsub(j) are the coefficients to be determined. If one puts N=1 and Csub(iN)=1, one has q 1 =M(mean), the mean absolute magnitude of the sample. As additional output, the algorithm provides one also with the dispersion in magnitude of the sample sigmasub(M), the mean solar motion (U,V,W) and the corresponding velocity ellipsoid (sigmasub(u), sigmasub(v), sigmasub(w). The use of this algorithm is illustrated. (Auth.)

Experimental determination of nuclear reaction rates in 238U and 235U along of the radius of fuel pellets of the IPEN/MB-01 reactor

International Nuclear Information System (INIS)

Mura, Luis Felipe Liambos

2015-01-01

This research presents and consolidates an alternative methodology for determining nuclear reaction rates along the radial direction of the fuel pellets which does not require high neutron flux. This technique is based on irradiating a thin UO 2 disk inserted into a removable fuel rod at the IPEN/MB-01 reactor core. Several gamma spectrometry are performed after irradiation using a HPGe detector. Six lead collimators with different diameters are sequentially alternated during this process, thus, the nuclear radioactive capture which occurs in 238 U and the fissions which occur in both 235 U and 238 U are measured according to six different radial regions of the fuel disk. Geometric efficiency corrections due to the introduction of collimators in HPGe detection system are determined by MCNP-5 code. The fission rate measurements are performed using the 99 Mo. This radionuclide was studied and proved ideal for these measurements because it is formed in linear behavior in the reactor core, have a high yield fission and emits low-energy photons. Measurements were performed irradiating UO 2 disks (with 4.3% enrichment) in the central position of the IPEN/MB-01 core at 100 watts power level during one hour. Some measurements were performed using a cadmium glove wrapped in the fuel rod to determine the nuclear reaction rates in the epithermal energy range. The experimental results obtained are compared with nuclear reaction rate calculations by means of MCNP-5 with ENDF/B-VII.0 data library showing discrepancies of up to 9% in 238 U capture rates and 14% for U fission rates for epithermal energies. Uncertainties regarding the nuclear capture rates have maximum values of 4.5% and the fission rates has maximum values of 11.3%. (author)

Transformation temperatures γU → δUZr2 Y γU →αU in U-Zr-Nb alloys

International Nuclear Information System (INIS)

Komar Varela, Carolina L.; Arico, Sergio F.; Gribaudo, Luis M.; Comision Nacional de Energia Atomica, General San Martin

2009-01-01

The international RERTR program has as primary objective the development of new fuels for research and test reactors to satisfy the requirement of low enrichment in 235 U (lower than 20 %). It is known that the cubic-phase (γU) has an excellent behaviour under irradiation. In this context, in the Materials Department (GIDAT-GAEN-CNEA) U-Zr-Nb alloys are considered candidates for the development of a high-density monolithic-type nuclear fuel. It is necessary to evaluate the thermodynamic parameters that allow to obtain a range of concentrations of the U-Zr-Nb system in which this phase can be retained in the metastable condition with the required 235 U density. In this work, eight U alloys with concentrations ranging from 13.9 to 43.7 wt.% Zr and from 0 to 6.4 wt.% Nb, were fabricated. Dynamical measurements of electrical resistivity, with a cooling rate of 4 o C/min, were performed and the results were analyzed. Considering this cooling rate, a Nb concentration of at least 17.8 wt. % would inhibit the transformation γU→ δUZr 2 and a concentration of al least 23.3 wt % would inhibit the γU → αU transformation. (author)

Absolute and relative cross section measurements of 237Np(n,f and 238U(n,f at the National Physical Laboratory

Directory of Open Access Journals (Sweden)

Salvador-Castiñeira Paula

2017-01-01

Full Text Available Cross section measurements in the fast energy region are being demanded as one of the key ingredients for modelling Generation-IV nuclear power plants. However, in facilities where there are no time-of-flight possibilities or it is not convenient to use them, using the 235U(n,f cross section as a benchmark would require a careful knowledge of the room scatter in the experimental area. In this paper we present measurements of two threshold reactions, 238U(n,f and 237Np(n,f, that could become a standard between their fission threshold and 2.5 MeV, if the discrepancies shown in the evaluations and in some experimental data can be solved. The preliminary results are in agreement with the present ENDF/B-VII.1 evaluation.

45 CFR 235.110 - Fraud.

Science.gov (United States)

2010-10-01

... 45 Public Welfare 2 2010-10-01 2010-10-01 false Fraud. 235.110 Section 235.110 Public Welfare... PROGRAMS § 235.110 Fraud. State plan requirements: A State plan under title I, IV-A, X, XIV, or XVI of the Social Security Act must provide: (a) That the State agency will establish and maintain: (1) Methods and...

Standard test method for isotopic analysis of uranium hexafluoride by double standard single-collector gas mass spectrometer method

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This is a quantitative test method applicable to determining the mass percent of uranium isotopes in uranium hexafluoride (UF6) samples with 235U concentrations between 0.1 and 5.0 mass %. 1.2 This test method may be applicable for the entire range of 235U concentrations for which adequate standards are available. 1.3 This test method is for analysis by a gas magnetic sector mass spectrometer with a single collector using interpolation to determine the isotopic concentration of an unknown sample between two characterized UF6 standards. 1.4 This test method is to replace the existing test method currently published in Test Methods C761 and is used in the nuclear fuel cycle for UF6 isotopic analyses. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro...

Method of fault diagnosis in nozzle cascades for U-235 enrichment

International Nuclear Information System (INIS)

Schuette, R.; Steinhaus, H.

1978-09-01

In a separation nozzle cascade for enrichment of the light uranium isotope U-235 some 450 stages are connected in series. For optimum separation performance of such a plant the design values of the nozzle inlet pressure, of the UF 6 concentration of the UF 6 -cut and the cut of the light additional gas must be matched in all separation stages. Also the feed stream, the product stream, and the tails stream have to be controlled according to the cascade design values. Since it is not possible to measure the cuts directly, these values are calculated on the basis of the material flow balances of the cascade using the pressure values and the UF 6 concentration measurements in each stage, these data being supplemented by concentration measurements in the light and heavy fractions of selected stages. This approach requires the use of a digital computer for processing some 1500 readings to calculate the 2500 plant parameters defining the plant state. This study describes a method of diagnosing the major faults to be expected in a separation nozzle cascade. It is based on the fact that the fault profiles are characterized sufficiently well by maximum values and values to identify the cause of a fault and localize the point where it occurs by means of simple relations between these six values and of their relative positions. The performance of the method has been tested in experiments in the ten-stage pilot plant. For use in commercial separation nozzle cascades the range of performance and the special mode of implementation can be derived from the characteristics of the plant components (separation nozzles, compressors, control valves). The methodological approach in this fault diagnosis also provides the basis for computer aided control procedures to raise a separation cascade from any steady plant condition to its set point operation. (orig./HP) 891 HP [de

The D1Πu state of HD and the mass scaling relation of its predissociation widths

International Nuclear Information System (INIS)

Dickenson, G D; Ubachs, W

2012-01-01

Absorption spectra of HD have been recorded in the wavelength range of 75–90 nm at 100 K using the vacuum ultraviolet Fourier transform spectrometer at the Synchrotron SOLEIL. The present wavelength resolution represents an order of magnitude improvement over that of previous studies. We present a detailed study of the D 1 Π u –X 1 Σ + g system observed up to v′ = 18. The Q-branch transition probing levels of Π − symmetry are observed as narrow resonances limited by the Doppler width at 100 K. Line positions for these transitions are determined to an estimated absolute accuracy of 0.06 cm −1 . Predissociation line widths of Π + levels are extracted from the absorption spectra. A comparison with the recent results on a study of the D 1 Π u state in H 2 and D 2 reveals that the predissociation widths scale as μ −2 J(J + 1), with μ being the reduced mass of the molecule and J the rotational angular momentum quantum number, as expected from an interaction with the B′ 1 Σ + u continuum causing the predissociation. (paper)

Absolute isotopic abundances of Ti in meteorites

International Nuclear Information System (INIS)

Niederer, F.R.; Papanastassiou, D.A.; Wasserburg, G.J.

1985-01-01

The absolute isotope abundance of Ti has been determined in Ca-Al-rich inclusions from the Allende and Leoville meteorites and in samples of whole meteorites. The absolute Ti isotope abundances differ by a significant mass dependent isotope fractionation transformation from the previously reported abundances, which were normalized for fractionation using 46 Ti/ 48 Ti. Therefore, the absolute compositions define distinct nucleosynthetic components from those previously identified or reflect the existence of significant mass dependent isotope fractionation in nature. We provide a general formalism for determining the possible isotope compositions of the exotic Ti from the measured composition, for different values of isotope fractionation in nature and for different mixing ratios of the exotic and normal components. The absolute Ti and Ca isotopic compositions still support the correlation of 50 Ti and 48 Ca effects in the FUN inclusions and imply contributions from neutron-rich equilibrium or quasi-equilibrium nucleosynthesis. The present identification of endemic effects at 46 Ti, for the absolute composition, implies a shortfall of an explosive-oxygen component or reflects significant isotope fractionation. Additional nucleosynthetic components are required by 47 Ti and 49 Ti effects. Components are also defined in which 48 Ti is enhanced. Results are given and discussed. (author)

Study of U235 neutron fission spectrum by the knowledge of cross sections average over that spectrum

International Nuclear Information System (INIS)

Suarez, P.M.

1997-01-01

A literature search of cross sections averaged over the fission neutron spectrum confirms inconsistencies between calculated and experimental values for high threshold reactions. Since, in this case, calculated averaged cross sections are systematically lower than measured values, it is concluded that the representations used to carry out these calculations underestimate the number of neutrons in the high energy region of the spectrum. A careful measurement of the averaged cross section for the 45 Sc(n,2n) 44g Sc and 45 Sc(n,2n) 44m Sc high threshold reactions had been performed in the RA-6 Neutron Activation Analysis Laboratory after carefully checking that the neutron flux at the core position where the samples were being irradiated was indeed an undisturbed fission spectrum. The experimental values are greater than those calculated with either, Watt type representations or the one based on the Madland and Nix model for the prompt fission spectrum. In many areas of nuclear engineering, like validation of nuclear data, reactor calculations, applied nuclear physics, shielding design, etc., it is of great practical importance to have a representation for the neutron flux that can be expressed in a closed analytical form and that agrees with experimental results, specially for the most widely fissile nuclide, 235 U. The results of the calculations mentioned above lead us to propose an analytical form for the 235 U fission neutron spectrum that better agrees with experimental results in the whole energy spectrum. We propose two different forms; both are a modification of the Watt-type form that has been adopted within the ENDF/B-V files. One of the new analytical representations is defined in two regions: below 9.5 MeV it is exactly the same formula as that used within the ENDF/B-V files, above this energy the parameters of this formula are changed. The other proposed analytical representation is expressed by a single formula in the whole energy range. These two new

Determination of subjective similarity for pairs of masses and pairs of clustered microcalcifications on mammograms: Comparison of similarity ranking scores and absolute similarity ratings

International Nuclear Information System (INIS)

Muramatsu, Chisako; Li Qiang; Schmidt, Robert A.; Shiraishi, Junji; Suzuki, Kenji; Newstead, Gillian M.; Doi, Kunio

2007-01-01

The presentation of images that are similar to that of an unknown lesion seen on a mammogram may be helpful for radiologists to correctly diagnose that lesion. For similar images to be useful, they must be quite similar from the radiologists' point of view. We have been trying to quantify the radiologists' impression of similarity for pairs of lesions and to establish a ''gold standard'' for development and evaluation of a computerized scheme for selecting such similar images. However, it is considered difficult to reliably and accurately determine similarity ratings, because they are subjective. In this study, we compared the subjective similarities obtained by two different methods, an absolute rating method and a 2-alternative forced-choice (2AFC) method, to demonstrate that reliable similarity ratings can be determined by the responses of a group of radiologists. The absolute similarity ratings were previously obtained for pairs of masses and pairs of microcalcifications from five and nine radiologists, respectively. In this study, similarity ranking scores for eight pairs of masses and eight pairs of microcalcifications were determined by use of the 2AFC method. In the first session, the eight pairs of masses and eight pairs of microcalcifications were grouped and compared separately for determining the similarity ranking scores. In the second session, another similarity ranking score was determined by use of mixed pairs, i.e., by comparison of the similarity of a mass pair with that of a calcification pair. Four pairs of masses and four pairs of microcalcifications were grouped together to create two sets of eight pairs. The average absolute similarity ratings and the average similarity ranking scores showed very good correlations in the first study (Pearson's correlation coefficients: 0.94 and 0.98 for masses and microcalcifications, respectively). Moreover, in the second study, the correlations between the absolute ratings and the ranking scores were also

Absolute limit on rotation of gravitationally bound stars

Science.gov (United States)

Glendenning, N. K.

1994-03-01

The authors seek an absolute limit on the rotational period for a neutron star as a function of its mass, based on the minimal constraints imposed by Einstein's theory of relativity, Le Chatelier's principle, causality, and a low-density equation of state, uncertainties which can be evaluated as to their effect on the result. This establishes a limiting curve in the mass-period plane below which no pulsar that is a neutron star can lie. For example, the minimum possible Kepler period, which is an absolute limit on rotation below which mass-shedding would occur, is 0.33 ms for a M = 1.442 solar mass neutron star (the mass of PSR1913+16). If the limit were found to be broken by any pulsar, it would signal that the confined hadronic phase of ordinary nucleons and nuclei is only metastable.

Periodicities in the high-mass X-ray binary system RXJ0146.9+6121/LSI+61°235

Science.gov (United States)

Sarty, Gordon E.; Kiss, László L.; Huziak, Richard; Catalan, Lionel J. J.; Luciuk, Diane; Crawford, Timothy R.; Lane, David J.; Pickard, Roger D.; Grzybowski, Thomas A.; Closas, Pere; Johnston, Helen; Balam, David; Wu, Kinwah

2009-01-01

The high-mass X-ray binary RXJ0146.9+6121, with optical counterpart LSI+61°235 (V831Cas), is an intriguing system on the outskirts of the open cluster NGC663. It contains the slowest Be type X-ray pulsar known with a pulse period of around 1400s and, primarily from the study of variation in the emission line profile of Hα, it is known to have a Be decretion disc with a one-armed density wave period of approximately 1240d. Here we present the results of an extensive photometric campaign, supplemented with optical spectroscopy, aimed at measuring short time-scale periodicities. We find three significant periodicities in the photometric data at, in order of statistical significance, 0.34, 0.67 and 0.10d. We give arguments to support the interpretation that the 0.34 and 0.10d periods could be due to stellar oscillations of the B-type primary star and that the 0.67d period is the spin period of the Be star with a spin axis inclination of 23+10-8 degrees. We measured a systemic velocity of -37.0 +/- 4.3kms-1 confirming that LSI+61°235 has a high probability of membership in the young cluster NGC663 from which the system's age can be estimated as 20-25Myr. From archival RXTE All Sky Monitor (ASM) data we further find `super' X-ray outbursts roughly every 450d. If these super outbursts are caused by the alignment of the compact star with the one-armed decretion disc enhancement, then the orbital period is approximately 330d.

Development of a recovery method of 131I in the 99Mo process through the fission of 235U

International Nuclear Information System (INIS)

Bignardi, Aline Moraes Teixeira

2013-01-01

13 1 I is an iodine radioisotope widely used in nuclear medicine that can be used either for diagnostic or for treatment due to its physical decay by β - and its high emission of y-rays. It is produced at IPEN using the indirect reaction: 130 Te(n,y) 131m Te → 131 Te → 131 I where TeO 2 targets are irradiated in a Nuclear Reactor. There is also the possibility of producing 131 I by the fission of 235 U, where about 300 different elements are produced together with 131 I. The 131 I produced through this method presents high specific activity and radioactive concentration suitable for the labeling of molecules. The aim of this work was to develop a recovery method of 131 I with the required quality to be used in Nuclear Medicine in the 99 Mo production process through the route of acid dissolution of metallic 235 U targets. 131 I can appear in two phases of the process, both in the gaseous phase produced during the dissolution of metallic U targets and in the dissolution solution. This work studied the recovery of 131 I in these two phases. Several materials were used for the capture and recovery of 131 I at the two phases of the process, the gaseous one and the solution of dissolution of U targets. Columns of alumina with Cu, acid alumina with Cu, Ag microspheres, Cu microspheres, Ag nanospheres, anionic cartridges, Ag cartridges, anion exchange resin and activated charcoal columns were tested. Solutions containing 131 I in 0.1 mol.L -1 NaOH were percolated through the materials and the eluted solutions were analyzed in a dose calibrator. The precipitation of AgI was also studied wth further dissolution of this precipitate with 0.1 mol L -1 NH 4 OH and 5% Na 2 S 2 O 3 . The recovery results varied according to the material, activated charcoal showed recovery yields between 42% and 83% but the recovery yield of the alumina column with Cu ranged from 20% to 85%. Tests with Ag nanospheres showed recovery yield of 26% using 0.1 mol L -1 NaOH and 72% for Na 2 S 2 O

Measurement of 237Np fission rate ratio relative to 235U fission rate in cores with various thermal neutron spectrum at the Kyoto University Critical Assembly

International Nuclear Information System (INIS)