Assessing Hubbard-corrected AM05+U and PBEsol+U density functionals for strongly correlated oxides CeO_2 and Ce_2O_3

International Nuclear Information System (INIS)

Weck, Philippe F.; Kim, Eunja

2016-01-01

The structure–property relationships of bulk CeO_2 and Ce_2O_3 have been investigated using AM05 and PBEsol exchange–correlation functionals within the frameworks of Hubbard-corrected density functional theory (DFT+U) and density functional perturbation theory (DFPT+U). Compared with conventional PBE+U, RPBE+U, PW91+U and LDA+U functionals, AM05+U and PBEsol+U describe experimental crystalline parameters and properties of CeO_2 and Ce_2O_3 with superior accuracy, especially when +U is chosen close to its value derived by the linear-response approach. Lastly, the present findings call for a reexamination of some of the problematic oxide materials featuring strong f- and d-electron correlation using AM05+U and PBEsol+U.

Thermal and x-ray studies on Tl2U(MoO4)3 and Tl4U(MoO4)4

International Nuclear Information System (INIS)

Dahale, N.D.; Keskar, Meera; Kulkarni, N.K.; Singh Mudher, K.D.

2006-01-01

In the quaternary Tl-U(IV)-Mo-O system, two new compounds namely Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 were prepared and characterized by powder X-ray diffraction and thermal methods. These compounds were prepared by solid state reactions of Tl 2 MoO 4 , UMoO 5 and MoO 3 in the required stoichiometric ratio at 500 deg C in evacuated sealed quartz ampoule. The XRD data of Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 were indexed on orthorhombic cell. TG curves of Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 did not show any weight change up to 700 deg C in an inert atmosphere. During heating in an inert atmosphere, Tl 2 U(MoO 4 ) 3 and Tl 4 U(MoO 4 ) 4 showed endothermic Dta peaks due to melting of the compounds at 519 and 565 deg C, respectively. (author)

Diffraction study on the nonstoichiometric α-U2N3+x phase

International Nuclear Information System (INIS)

Serizawa, H.; Fukuda, K.; Ishii, Y.; Funahashi, S.; Katsura, M.

1993-01-01

X-ray and neutron diffraction studies were performed on nonstoichiometric α-U 2 N 3+ x having a composition range 1.68 2 N 3+x in this composition range was distorted Mn 2 O 3 -type. Structure parameters of U and N atoms were determined. The results showed that positions of U atoms varied continuously with nitrogen content. No evidence of the modification from bcc to fcc could be obtained. Interatomic distances of U-U and U-N were determined. The position parameter of N atoms showed that N atoms were slightly deviated from the tetrahedral site. (author)

Microstructure of the irradiated U 3Si 2/Al silicide dispersion fuel

Science.gov (United States)

Gan, J.; Keiser, D. D.; Miller, B. D.; Jue, J.-F.; Robinson, A. B.; Madden, J. W.; Medvedev, P. G.; Wachs, D. M.

2011-12-01

The silicide dispersion fuel of U 3Si 2/Al is recognized as the best performance fuel for many nuclear research and test reactors with up to 4.8 gU/cm 3 fuel loading. An irradiated U 3Si 2/Al dispersion fuel ( 235U ˜ 75%) from the high-flux side of a fuel plate (U0R040) from the Reduced Enrichment for Research and Test Reactors (RERTR)-8 test was characterized using transmission electron microscopy (TEM). The fuel was irradiated in the Advanced Test Reactor (ATR) for 105 days. The average irradiation temperature and fission density of the U 3Si 2 fuel particles for the TEM sample are estimated to be approximately 110 °C and 5.4 × 10 27 f/m 3. The characterization was performed using a 200-kV TEM. The U/Si ratio for the fuel particle and (Si + Al)/U for the fuel-matrix-interaction layer are approximately 1.1 and 4-10, respectively. The estimated average diameter, number density and volume fraction for small bubbles (<1 μm) in the fuel particle are ˜94 nm, 1.05 × 10 20 m -3 and ˜11%, respectively. The results and their implication on the performance of the U 3Si 2/Al silicide dispersion fuel are discussed.

Redox equilibrium of U4+/U3+ in molten NaCl-2CsCl by UV-Vis spectrophotometry and cyclic voltammetry

International Nuclear Information System (INIS)

Nagai, Takayuki; Uehara, Akihiro; Fujii, Toshiyuki; Shirai, Osamu; Yamana, Hajimu; Sato, Nobuaki

2005-01-01

In order to investigate the redox equilibrium of uranium ions in molten NaCl-2CsCl, UV-Vis absorption spectro-photometry measurements were performed for U 4+ and U 3+ in molten NaCl-2CsCl at 923 K under simultaneous electrolytic control of their ratio. Prominent absorption bands at 480 and 570 nm were assigned to U 3+ , and their molar absorptivities were determined to be 1,260±42 and 963±32 mol -1 ·l·cm -1 respectively. From the dependence of the rest potential of the melt on the spectrophotometrically determined ratio of [U 4+ ]/[U 3+ ], the standard redox potential of the couple U 4+ /U 3+ at 923 K was determined to be -1.481±0.004 V vs. Cl 2 /Cl - . Cyclic voltammetry measurements were carried out for the couple U 4+ /U 3+ , and the results agreed well with this standard redox potential value. By the results of cyclic voltammetry, a temperature dependence of the standard redox potential was found to be -2.094+6.639 x 10 -4 T (T=823-923K). (author)

Positron attachment to the H2(A 3Σu) state

International Nuclear Information System (INIS)

Mitroy, J.; Zhang, J. Y.

2011-01-01

The stochastic variational method is used to compute the binding energy for positrons attached to the repulsive H 2 (A 3 Σ u ) state. Attachment occurs for internuclear separations between 1.616 a 0 and 1.818 a 0 . At these distances the vertical ionization potential for the H 2 (A 3 Σ u ) state is close to the positronium binding energy of 0.250 a.u. The maximum attachment energy occurs at 1.67 a 0 and is 0.003532 a.u.

The Recovery of Uranium From The Rejected Fuel Plate Dispersion Type of U3O8-Al and U3Si2Al by NaOH

International Nuclear Information System (INIS)

Widodo, G; Aji, D

1998-01-01

The recovery of uranium from the rejected fuel plate dispersion type of U 3 O 8 -AI And U 3 Si 2 -AI with a dissolution has been performed.Each of 5 fragment of fuel plate dispersion of U 3 O 8 -AI or U 3 Si 2 Al of 1x4 cm size was put in the distilled glass content of 250 ml NaOH solution whit The concentration variation 10,15,20,25,and 30%,and than was heated at temperature of 102 o C and was stirred constantly by magnetic stirred.Uranium in the form of U 3 O 8 or U 3 Si 2 was separated by filtration and Either residu and filtrate was analyzed by potentiometry using modified Devies Gray method. From the experiment data it was found in the residu that presentation of uranium was 83.99-84.05% and 84.67-86.556% while in filtrate it was found 53.90 ppm and 69.3 ppm

Properties of U3Si2-Al dispersion fuel element and its application

International Nuclear Information System (INIS)

Yin Changgeng

2001-01-01

The properties of U 3 Si 2 fuel and U 3 Si 2 -Al dispersion fuel element are introduced, which include U-loading; the banding quality, U-homogeneity and 'dog-bone' phenomenon, the minimum thickness of cladding and the corrosion performances. The fabrication technique of fuel elements, NDT for fuel plates, assemble technique of fuel elements and the application of U 3 Si 2 -Al dispersion fuel elements in the world are introduced

Nightglow vibrational distributions in the A3Σu+ and A'3Δu states of O2 derived from astronomical sky spectra

Directory of Open Access Journals (Sweden)

T. G. Slanger

2004-09-01

Full Text Available Astronomical sky spectra from the Keck I telescope on Mauna Kea have been used to obtain vibrational distributions in the O2A3Σu+ and O2(A'3Δu states from rotationally-resolved Herzberg I and Chamberlain band emissions in the terrestrial nightglow. The A3Σu+ distribution is similar to that presented in earlier publications, with the exception that there is significant population in the previously undiscerned v=0 level. The vibrational distributions of the A'3Δu and A3Σu+ states are essentially the same when comparison is made in terms of the level energies. The intensity of Chamberlain band emission at the peak of the distribution is about one-fourth that of the Herzberg I emission, as previously shown, and may be related primarily to radiative efficiency. The peaks in both population distributions are about 0.25eV below the O(3P+O(3P dissociation limit. We compare these Herzberg state distributions with that of the O2(b1Σg+ state, concurring with others that the intense nightglow emission associated with b1Σg+(v=0 is a reflection of direct transfer from the Herzberg states. This process takes place following O2 collisions, with simultaneous production of very high a1Δg and b1Σg+ vibrational levels.

Reduction of U3O8 to U by a metallic reductant, Li

International Nuclear Information System (INIS)

Jin-Mok Hur; Sun-Seok Hong; Hansoo Lee

2010-01-01

Reduction of U 3 O 8 was investigated for the recycling of spent oxide fuel from a commercial nuclear power plant. The possible reduction methods were proposed and compared. Based on the thermodynamic analysis, Li metal was selected as a reductant. The optimum reaction temperature for the reduction of U 3 O 8 was investigated at the wider reaction temperature range. The adverse oxidation of U metal by Li 2 O at 1,000 deg C was experimentally verified. Ellingham diagram was constructed to investigate the extent of the uranium oxides reduction when the reaction was carried out above melting point of U metal. (author)

The U(3) principle as base of a microscopical U(3) model for the clarification of the phenomenon of nuclear molecules

International Nuclear Information System (INIS)

Bader, R.

1985-01-01

The tenor of this thesis is the regarding of the U(3) symmetry in the study of nuclear reactions. By the description of the two colliding fragments and their relative motion by means of U(3) quantum numbers U(3) channels and U(3) channel sets are defined. It is shown that in certain collisions the U(3) symmetry of U(3) channels is incompatible with the U(3) symmetry of the compound nucleus. For these U(3) channels the formation of the compound nucleus is forbidden. In this framework a microscopical U(3) model for the phenomenon of the nuclear molecule resonances is developed. U(3) barriers which play an important role in this model are responsible for the repulsion between the two fragments. By microscopical calculations it is confirmed that by the U(3) channels allowed above the U(3) barriers an attraction between the two fragments arises. This interchange of attraction and repulsion leads to the formation of nuclear molecules. Furthermore it is shown that this incompatibility and by this the phenomenon of nuclear molecule resonances can be reduced to an U(3) principle in which the Pauli principle is contained. Basing on this U(3) principle selection rules are formulated which predict candidates for nuclear molecule resonances. This explains why only some binary systems tend to the molecule formation. (orig./HSI) [de

Comparison of U(VI) adsorption onto nanoscale zero-valent iron and red soil in the presence of U(VI)–CO_3/Ca–U(VI)–CO_3 complexes

International Nuclear Information System (INIS)

Zhang, Zhibin; Liu, Jun; Cao, Xiaohong; Luo, Xuanping; Hua, Rong; Liu, Yan; Yu, Xiaofeng; He, Likai

2015-01-01

Highlights: • NZVI can be used for adsorbing U(VI)–CO_3 complexes. • Use of NZVI is feasible for remediation of uranium-contaminated soils. • The mechanism of U(VI)–CO_3 complexes adsorbing onto NZVI has been explained. - Abstract: The influence of U(VI)–CO_3 and Ca–U(VI)–CO_3 complexes on U(VI) adsorption onto red soil and nanoscale zero-valent iron (NZVI) was investigated using batch adsorption and fixed-bed column experiments to simulate the feasibility of NZVI as the reactive medium in permeable- reactive barriers (PRB) for in situ remediation of uranium-contaminated red soils. The adsorption capacity (q_e) and distribution constant (K_d) of NZVI and red soil decreased with increasing pH, dissolved carbonate and calcium concentrations, but the q_e and K_d values of NZVI were 5–10 times higher than those of red soil. The breakthrough pore volume (PV) values increased with the decrease of pH, dissolved carbonate and calcium concentration; however, the breakthrough PV values of the PRB column filled with 5% NZVI were 2.0–3.5 times higher than the 100% red soil column. The U(VI)–CO_3 complexes adsorbed onto the surface of red soil/NZVI (≡SOH) to form SO–UO_2CO_3"− or SO–UO_2 (CO_3)_2"3"−. XPS and XRD analysis further confirmed the reduction of U(VI) to U(IV) and the formation of FeOOH on NZVI surfaces. The findings of this study are significant to the remediation of uranium-contaminated red soils and the consideration of practical U(VI) species in the natural environment.

Grain Size and Phase Purity Characterization of U3Si2 Pellet Fuel

Energy Technology Data Exchange (ETDEWEB)

Hoggan, Rita E. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Tolman, Kevin R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cappia, Fabiola [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wagner, Adrian R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Harp, Jason M. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2018-05-01

Characterization of U3Si2 fresh fuel pellets is important for quality assurance and validation of the finished product. Grain size measurement methods, phase identification methods using scanning electron microscopes equipped with energy dispersive spectroscopy and x-ray diffraction, and phase quantification methods via image analysis have been developed and implemented on U3Si2 pellet samples. A wide variety of samples have been characterized including representative pellets from an initial irradiation experiment, and samples produced using optimized methods to enhance phase purity from an extended fabrication effort. The average grain size for initial pellets was between 16 and 18 µm. The typical average grain size for pellets from the extended fabrication was between 20 and 30 µm with some samples exhibiting irregular grain growth. Pellets from the latter half of extended fabrication had a bimodal grain size distribution consisting of coarsened grains (>80 µm) surrounded by the typical (20-30 µm) grain structure around the surface. Phases identified in initial uranium silicide pellets included: U3Si2 as the main phase composing about 80 vol. %, Si rich phases (USi and U5Si4) composing about 13 vol. %, and UO2 composing about 5 vol. %. Initial batches from the extended U3Si2 pellet fabrication had similar phases and phase quantities. The latter half of the extended fabrication pellet batches did not contain Si rich phases, and had between 1-5% UO2: achieving U3Si2 phase purity between 95 vol. % and 98 vol. % U3Si2. The amount of UO2 in sintered U3Si2 pellets is correlated to the length of time between U3Si2 powder fabrication and pellet formation. These measurements provide information necessary to optimize fabrication efforts and a baseline for future work on this fuel compound.

Comparison of U(VI) adsorption onto nanoscale zero-valent iron and red soil in the presence of U(VI)–CO{sub 3}/Ca–U(VI)–CO{sub 3} complexes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhibin [Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, East China Institute of Technology, Nanchang 330013 (China); State Key Laboratory Breeding Base of Nuclear Resources and Environment (East China Institute of Technology), Ministry of Education, Nanchang 330013 (China); Chemistry, Biological and Materials Sciences Department, East China Institute of Technology, Nanchang 330013 (China); Liu, Jun [State Key Laboratory Breeding Base of Nuclear Resources and Environment (East China Institute of Technology), Ministry of Education, Nanchang 330013 (China); Cao, Xiaohong, E-mail: xhcao@ecit.cn [Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, East China Institute of Technology, Nanchang 330013 (China); State Key Laboratory Breeding Base of Nuclear Resources and Environment (East China Institute of Technology), Ministry of Education, Nanchang 330013 (China); Chemistry, Biological and Materials Sciences Department, East China Institute of Technology, Nanchang 330013 (China); Luo, Xuanping [Chemistry, Biological and Materials Sciences Department, East China Institute of Technology, Nanchang 330013 (China); Hua, Rong; Liu, Yan [Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, East China Institute of Technology, Nanchang 330013 (China); State Key Laboratory Breeding Base of Nuclear Resources and Environment (East China Institute of Technology), Ministry of Education, Nanchang 330013 (China); Chemistry, Biological and Materials Sciences Department, East China Institute of Technology, Nanchang 330013 (China); Yu, Xiaofeng; He, Likai [Chemistry, Biological and Materials Sciences Department, East China Institute of Technology, Nanchang 330013 (China); and others

2015-12-30

Highlights: • NZVI can be used for adsorbing U(VI)–CO{sub 3} complexes. • Use of NZVI is feasible for remediation of uranium-contaminated soils. • The mechanism of U(VI)–CO{sub 3} complexes adsorbing onto NZVI has been explained. - Abstract: The influence of U(VI)–CO{sub 3} and Ca–U(VI)–CO{sub 3} complexes on U(VI) adsorption onto red soil and nanoscale zero-valent iron (NZVI) was investigated using batch adsorption and fixed-bed column experiments to simulate the feasibility of NZVI as the reactive medium in permeable- reactive barriers (PRB) for in situ remediation of uranium-contaminated red soils. The adsorption capacity (q{sub e}) and distribution constant (K{sub d}) of NZVI and red soil decreased with increasing pH, dissolved carbonate and calcium concentrations, but the q{sub e} and K{sub d} values of NZVI were 5–10 times higher than those of red soil. The breakthrough pore volume (PV) values increased with the decrease of pH, dissolved carbonate and calcium concentration; however, the breakthrough PV values of the PRB column filled with 5% NZVI were 2.0–3.5 times higher than the 100% red soil column. The U(VI)–CO{sub 3} complexes adsorbed onto the surface of red soil/NZVI (≡SOH) to form SO–UO{sub 2}CO{sub 3}{sup −} or SO–UO{sub 2} (CO{sub 3}){sub 2}{sup 3−}. XPS and XRD analysis further confirmed the reduction of U(VI) to U(IV) and the formation of FeOOH on NZVI surfaces. The findings of this study are significant to the remediation of uranium-contaminated red soils and the consideration of practical U(VI) species in the natural environment.

Hydrogen absorption in U{sub 3}Si{sub 2} and its impact on electronic properties

Energy Technology Data Exchange (ETDEWEB)

Mašková, Silvie, E-mail: maskova@mag.mff.cuni.cz [Department of Condensed Matter Physics, Charles University, Prague 2, The Czech Republic (Czech Republic); Miliyanchuk, Khrystyna [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Lviv (Ukraine); Havela, Ladislav [Department of Condensed Matter Physics, Charles University, Prague 2, The Czech Republic (Czech Republic)

2017-04-15

U{sub 3}Si{sub 2} reversibly absorbs hydrogen at very low H{sub 2} pressures (kPa range), yielding U{sub 3}Si{sub 2}H{sub 1.8}. One characteristic desorption temperature implies that there is only one type of H sites. U{sub 3}Si{sub 2} is a weak Pauli paramagnet (χ < 2·10{sup −8} m{sup 3}/mol U) with the shortest inter-uranium distances between the U atoms in different sheets (d{sub U-U} = 332 pm). The volume-expanded (10%) hydride is a spin fluctuator with temperature dependent magnetic susceptibility and a weak ferromagnetic component gradually arising below T = 100 K. The location of U{sub 3}Si{sub 2}H{sub 1.8} at the verge of magnetic ordering is evidenced by the low temperature specific heat with an upturn in C/T and a dramatic enhancement of the Sommerfeld coefficient of electronic specific heat γ, which reaches 500 mJ/mol f.u. K{sup 2}. - Highlights: •U{sub 3}Si{sub 2} can be hydrogenated at very low H{sub 2} pressure, yielding U{sub 3}Si{sub 2}H{sub 1.8}. •The H absorption to a single H-site is reversible. •Hydrogenation leads to the expansion of the unit cell by 10%. •U{sub 3}Si{sub 2} is a weak Pauli paramagnet. •The hydride is a spin fluctuator with temperature dependent magnetic susceptibility.

Structure and Lamb shift of 2s1/2-2p3/2 levels in lithiumlike U89+ through neonlike U82+

International Nuclear Information System (INIS)

Beiersdorfer, P.; Knapp, D.; Marrs, R.E.; Elliott, S.R.; Chen, M.H.

1993-01-01

The first Doppler-shift-free crystal-spectrometer measurement of stationary highly stripped uranium ions from a high-energy electron beam ion trap is presented. Thirteen 2s 1/2- 2p 3/2 transitions in eight ionization states bteween Li-like U 89+ and Ne-like U 82+ are identified and measured with an accuracy as high as 37 ppm, providing benchmarks for testing relativistic correlation and quantum electrodynamic effects in highly charged multielectron ions. A value of 47.39±0.35 eV is found for the 2s 1/2 Lamb shift in Li-like U 89+ , in excellent agreement with theory

Structure and lamb shift of 2s1/2-2p3/2 levels in lithiumlike U89+ through neonlike U82+

International Nuclear Information System (INIS)

Beiersdorfer, P.; Knapp, D.; Marrs, R.E.; Elliott, S.; Chen, M.H.

1993-01-01

The first Doppler-shift-free crystal- spectrometer measurements from stationary highly stripped uranium ions are presented. Eleven 2s 1/2 -2p 3/2 transitions in eight ionization stages between Li-like U 89+ and Ne-like U 82+ are identified and measured with an accuracy as high as 45 ppm, providing benchmarks for testing relativistic correlation and quantum electrodynamical effects in highly charged multi-electron ions. A value of 47.38 ± 0.35 eV is found for the 2s 1/2 Lamb shift in Li-like U 89+ , in excellent agreement with the theoretical value of 47.58 eV

Atomization of U3Si2 for research reactor fuel

International Nuclear Information System (INIS)

Kim, C.K.; Kim, K.H.; Lee, C.T.; Kuk, I.H.

1995-01-01

Rotating disk atomization technique is applied to KMRR (Korea Multi-purpose Research Reactor) fuel fabrication. A rotating disk atomizer is designed and manufactured locally and U-4.0 wt. % Si alloy powders are produced. The atomized powders are heat-treated to transform into U 3 Si and the mixture of U 3 Si and Al are extruded to fuel meat. Most of the atomized powders are spherical in shape. The microstructure of the powder is fine due to the rapid solidification. The time required for peritectoid reaction is reduced due to the fine microstructures and the resultant U 3 Si grain size is finer than ever obtained from ingot process. The mechanical properties of the fuel meat are improved: yield strength about 30 %, tensile strength 10% and elongation 250 % increased. (author)

Synthesis of (R)-5-(Di[2,3-3H2]propylamino)-5,6-dihydro-4H-imidazo[4,5,1-ij]quinolin-2(1H)-one-([3H]U-86170) and (R)-5-([2,3-3H2]propylamino)-5,6-dihydro-4H-imidazo(4,5,1-ij) quinolin-2(1H)-one ([3H]U-91356)

International Nuclear Information System (INIS)

Moon, M.W.; Hsi, R.S.P.

1992-01-01

(R)-5-(diallylamino)-5,6-dihydro-4H-imidazo[4,5,1-ij]quinolin-2(1H)-one (12b) was prepared in 9% overall yield from 3-aminoquinoline. Reaction of 12b in ethyl acetate with tritium gas in presence of a 5% platinum on carbon catalyst afforded a mixture of (R)-5-(di[2,3- 3 H 2 ]propylamino)-5,6-dihydro-4H-imidazo[4,5,1-ij]-quinolin-2(1H)-one ([ 3 H]U-86170, 69 Ci/mmol) and (R)-5-([2,3- 3 H 2 ]-propylamino)5,6-dihydro-4H-imidazo-[4,5,1-ij]quinolin-2(1H)-one ( [ 3 H]U-91356, 34 Ci/mmol) which was separated by preparative reverse-phase chromatography. U-86170 and U-91356 are potent dopamine D2 agonists. The labelled compounds are useful for drug disposition studies. [ 3 H]U-86170 is also useful as a dopamine D2 agonist radioligand for receptor binding studies. (author)

Proportioning of U3O8 powder

International Nuclear Information System (INIS)

Cermak, V.; Markvart, M.; Novy, P.; Vanka, M.

1989-01-01

The tests are briefly described or proportioning U 3 O 8 powder of a granulometric grain size range of 0-160 μm using a vertical screw, a horizontal dual screw and a vibration dispenser with a view to proportioning very fine U 3 O 8 powder fractions produced in the oxidation of UO 2 fuel pellets. In the tests, the evenness of proportioning was assessed by the percentage value of the proportioning rate spread measured at one-minute intervals at a proportioning rate of 1-3 kg/h. In feeding the U 3 O 3 in a flame fluorator, it is advantageous to monitor the continuity of the powder column being proportioned and to assess it radiometrically by the value of the proportioning rate spread at very short intervals (0.1 s). (author). 10 figs., 1 tab., 12 refs

Transuranium element incorporation into the β-U3O8 uranyl sheet

International Nuclear Information System (INIS)

Miller, M.L.; Burns, P.C.; Ewing, R.C.; Finch, R.J.

1997-01-01

Spent nuclear fuel (SNF) is unstable under oxidizing conditions. Although recent studies have determined the paragenetic sequence for uranium phases that result from the corrosion of SNF, there are only limited data on the potential of alteration phases for the incorporation of transuranium elements. The crystal chemical characteristics of transuranic elements (TUE) are to a certain extent similar to uranium; thus TUE incorporation into the sheets of uranyl oxide hydrate structures can be assessed by examination of the structural details of the β-U 3 O 8 sheet type. The sheets of uranyl polyhedra observed in the crystal structure of β-U 3 O 8 also occur in the mineral billietite, where they alternate with α-U 3 O 8 type sheets. Preliminary crystal structure determinations for the minerals ianthinite, and wyartite, indicate that these phases also contain β-U 3 O 8 type sheets. The β-U 3 O 8 sheet anion topology contains triangular, rhombic, and pentagonal sites in the proportions 2:1:2. In all structures containing β-U 3 O 8 type sheets, the triangular sites are vacant. The pentagonal sites are filled with U 6+ O 2 forming pentagonal bipyramids. The rhombic dipyramids filling the rhombic sites contain U 6+ O 2 in billietite, U 4+ O 2 in β-U 3 O 8 , U 4+ (H 2 O) 2 in ianthinite, and U 4+ O 3 in wyartite-II. Interlayer species include: H 2 O (billietite, wyartite II, and ianthinite), Ba 2+ (billietite) Ca 2+ wyartite II, and Co 3 2- wyartite II; there is no interlayer in β-U 3 O 8 . The similarity of known TUE coordination polyhedra with those of U suggests that the β-U 3 O 8 sheet will accommodate TUE substitution coupled with variations in apical anion configuration and interlayer population providing the required charge balance

U3Si2 Fabrication and Testing for Implementation into the BISON Fuel Performance Code

Energy Technology Data Exchange (ETDEWEB)

Knight, Travis W.

2018-04-23

A creep test stand was designed and constructed for compressive creep testing of U3Si2 pellets. This is described in Chapter 3.

• Creep testing of U3Si2 pellets was completed. In total, 13 compressive creep tests of U3Si2 pellets was successfully completed. This is reported in Chapter 3.
• Secondary creep model of U3Si2 was developed and implemented in BISON. This is described in Chapter 4.
• Properties of U3Si2 were implemented in BISON. This is described in Chapter 4.
• A resonant frequency and damping analyzer (RFDA) using impulse excitation technique (IET) was setup, tested, and used to analyze U3Si2 samples to measure Young’s and Shear Moduli which were then used to calculate the Poisson ratio for U3Si2. This is described in Chapter 5.
• Characterization of U3Si2 samples was completed. Samples were prepared and analyzed by XRD, SEM, and optical microscopy. Grain size analysis was conducted on images.

Contribution to the U$_2$C$_3$ formation by the synthetic reaction and by the decomposition of UC$_2$; Beitrag zur U$_2$C$_3$-bildung nach der synthetischen reaktion und durch zerfall von UC$_2$

Energy Technology Data Exchange (ETDEWEB)

Buschinelli, A. J.A.

1974-06-01

This work is a contribution to the study of the mechanism and of the kinetics of the U$_2$C$_3$ formation by the synthetic reaction. The influences of a mechanical and a thermical pre-treatment of the samples on the reaction kinetics were investigated and discussed taking into account other information from the literature. The relative increasing of the U$_2$C$_3$ nucleation rate due to the pulverization corresponds approximately to the surface enlargement of the pulverized material. The activation energy for the synthetic reaction in powder was found to be 94 +- 7 kcal/mol. The negative influence of nitrogen, oxygen and tungsten on the U$_2$C$_3$ formation was reported. In the decomposition of UC$_2$ to U$_2$C$_3$ and graphite, the influences of the morphology of the graphite precipitate and the fast neutron irradiation on the beginning of the U$_2$C$_3$ formation were also investigated.

Neutronic Analysis of the RSG-GAS Compact Core without CIP Silicide 3.55 g U/cc and 4.8 g U/cc

International Nuclear Information System (INIS)

Jati S; Lily S; Tukiran S

2004-01-01

Fuel conversion from U 3 O 8 -Al to U 3 Si 2 -Al 2.96 g U/cc density in the RSG-GAS core had done successfully step by step since 36 th core until 44 th core. So that, since the 45 th core until now (48 th core) had been using full of silicide 2.96 g U/cc. Even though utilization program of silicide fuel with high density (3.55 g U/cc and 4.8 g U/cc) and optimize operation of RSG-GAS core under research. Optimalitation of core with increasing operation cycle have been analyzing about compact core. The mean of compact core is the RSG-GAS core with decrease number of IP or CIP position irradiation. In this research, the neutronic calculation to cover RSG-GAS core and RSG-GAS core without CIP that are using U 3 Si 2 -Al 2.96 g U/cc, 3.55 g U/cc and 4.8 g U/cc had done. Two core calculation done at 15 MW power using SRAC-ASMBURN code. The calculation result show that fuel conversion from 2.96 g U/cc density to 3.55 g U/cc and 4.8 g U/cc will increasing cycle length for both RSG-GAS core and RSG-GAS compact core without CIP. However, increasing of excess reactivity exceeded from nominal value of first design that 9.2%. Change of power peaking factor is not show significant value and still less than 1.4. Core fuelled with U 3 Si 2 -Al 4.8 g U/cc density have maximum discharge burn-up which exceeded from licensing value (70%). RSG-GAS compact core without CIP fuelled U 3 Si 2 -Al 2.96 g U/cc have longer cycle operation then RSG-GAS core and fulfil limitation neutronic parameter at the first design value. (author)

Irradiation behaviour of solid and hollow U{sub 3}Si fuel elements: results to 15,000 MWd/tonne U

Energy Technology Data Exchange (ETDEWEB)

Feraday, M A; Chalder, G H; Cotnam, K D

1969-06-15

U{sub 3}Si fuel elements clad in zirconium alloy sheaths have been irradiated to burnups close to 15,000 MWd/tonne U in pressurized water at 220{sup o}C, 98 bars. The results show that the external swelling can be controlled by incorporating free volume in the element. The dimensional stability of such elements is adequate to permit their use in power reactor fuel bundles. A diameter increase of 1.2% had occurred in an element initially containing 12.8% total free volume, after a burnup of 14,700 MWd/tonne U. There was no change in diameter between burnups of 5200 and 14,700 MWd/tonne U. Elements containing 3% total free volume had increased in diameter about 2.5% at 2000 MWd/tonne U compared to 0.2% at 9500 MWd/tonne U for elements containing 22% total free volume. The observed swelling in the U{sub 3}Si is discussed in terms of possible mechanisms. (author)

Determination of U{sub 3}O{sub 8} in UO{sub 2} by infrared spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Silva, Liliane Aparecida; Lameiras, Fernando Soares; Santos, Ana Maria Matildes dos; Ferraz, Wilmar Barbosa; Barbosa, Joao Batista Santos, E-mail: lasfisica@gmail.com, E-mail: sl@cdtn.br, E-mail: amms@cdtn.br, E-mail: ferrazw@cdtn.br, E-mail: jbsb@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN), Belo Horizonte, MG (Brazil)

2017-01-15

The oxygen-uranium (O-U) system has various oxides, such as UO{sub 2}, U{sub 4}O{sub 9}, U{sub 3}O{sub 8}, and UO{sub 3}. Uranium dioxide is the most important one because it is used as nuclear fuel in nuclear power plants. UO{sub 2} can have a wide stoichiometric variation due to excess or deficiency of oxygen in its crystal lattice, which can cause significant modifications of its proprieties. O/U relation determination by gravimetry cannot differentiate a stoichiometric deviation from contents of other uranium oxides in UO{sub 2}. The presence of other oxides in the manufacturing of UO{sub 2} powder or sintered pellets is a critical factor. Fourier Transform Infrared Spectroscopy (FTIR) was used to identify U{sub 3}O{sub 8} in samples of UO{sub 2} powder. UO{sub 2} can be identified by bands at 340 cm{sup -1} and 470 cm{sup -1}, and U{sub 3}O{sub 8} and UO{sub 3} by bands at 735 cm{sup -1}, 910 cm{sup -1}, respectively. The methodology for sample preparation for FTIR spectra acquisition is presented, as well as the calibration for quantitative measurement of U{sub 3}O{sub 8} in UO{sub 2}. The content of U{sub 3}O{sub 8} in partially calcined samples of UO{sub 2} powder was measured by FTIR with good agreement with X-rays diffractometry (XRD). (author)

Progress in the development of uranium silicide (U3Si2) fuel at BATAN

International Nuclear Information System (INIS)

Suripto, A.; Soentono, S.

1995-01-01

After successful fabrication of two full-size prototype fuel elements containing ∼3.0 gU/cm 3 in the form of U 3 Si 2 -Al dispersion now undergoing irradiation in the Reaktor Serba Guna G.A. Siwabessy (RSG-GAS) core since 1990, further development in U 3 Si 2 -A2 dispersion fuel element manufacturing has been pursued, whose progress in discussed in this paper, with a special attention on the use of much higher-loading aimed at obtaining a better understanding on the influence of higher-loading on fuel core and plate manufacturing and quality. At present, high-loading U 3 Si 2 -AI dispersion miniplates are being manufactured for preparing some mini-fuel elements to be test-irradiated in the new MTR in-pile loop of the RSG-GAS. (author)

The effect of U3O-8 addition on the UO2 pellet

International Nuclear Information System (INIS)

Indrati, Y.T.; Syarif, D. G.; Handayani, A.

1998-01-01

The purpose of varied U 3 O 8 addition on the UO 2 pellet fabrication is to from 1-3 mu pores. The green pellets, compacted with 3 ton/cm 2 , are a mixture powder of UO 2 , TiO 2 (0.1% weight) and varied U 3 O 8 (0-12.5% weight). The green pellets were presintered by H2 atmosphere. The presintered pellets were put on the ceramic crucibles and than those were put on the SS 316 tube with argon atmosphere. The 1400 o C sintering was hold with the soaking time 3 hr and the same rate of heating and cooling 150 o C/hr. The UO 2 pellet with 5% (weight) U 3 O 8 addition has 95.17% of theoretic density and 548.4 ±6.57 VH. Based on the identification of microstructure of pellet, it is not acceptable for nuclear fuel although pellet has 10.02 mu on grain size and 1.3 mu on closed pore size. By the diffractometer X-ray, crystal structure of pellet is face centered cubic (FCC) with the O/U ratio is 2.08

State diagram of U-Al-Si as a basis for analysis of the processes in nuclear fuel compositions based on U(Al, Si)3 and U3Si compounds

International Nuclear Information System (INIS)

Chebotarev, N.T.; Konovalov, L.N.; Zhmak, V.A.; Chebotarev, Ya.N.

1996-01-01

Results of studies into the Al-UAl 3 -USi 3 -Si of the U-Al-Si ternary system are presented. It is established that phase equilibrium between the intermetallic compound U(Al, Si) 3 and the aluminium-silicon alloys may be presented in form of conodes on the isothermal cross-section of the state diagram. It is shown that the U(Al, Si) 3 intermetallic compound, containing up to 6.5 at.% silicon, interacts both with liquid and solid aluminium with the U(Al, Si) 4 phase formation [ru

A survey of the mechanical properties of uranium alloys U-5Mo-3Nb wt.% and U-3Mo-3Nb wt.%

Energy Technology Data Exchange (ETDEWEB)

Dupont, G.

1969-04-15

In a continuing program on the development of soft and ductile uranium alloys for armament applications, two compositions were studied. These gamma extruded uranium alloys were U-5Mo-3Nb wt.% and U-3Mo-3Nb wt.%. This study was carried out to determine the influence of tempering heat treatments associated with extrusion on the ductility of these uranium alloys. The mechanical properties of both alloys were measured in the extruded condition, in the extruded and annealed condition and in the quenched and tempered condition. A maximum elongation of 13.7% in tension with a low amount of work hardening was obtained for the U-3Mo-3Nb wt.% alloy after 1 1/2 hours anneal at 1200 deg F (650 deg C) followed by a rapid cooling in water at 70 deg F (21 deg C). A maximum elongation of 17.3% with a large amount of work hardening was obtained for alloy U-5Mo-3Nb wt.% after vacuum annealing, normalizing, gamma phase solubilizing at 1500 deg F (815 deg C) and quenching in water at 700 deg F (210 deg C). The maximum ductility achieved in these two alloys by our approaches is low compared with the ductility of Armco Iron employed for the same applications in the field of ballistics.

U(1) x U(1) x U(1) symmetry of the Kimura 3ST model and phylogenetic branching processes

International Nuclear Information System (INIS)

Bashford, J D; Jarvis, P D; Sumner, J G; Steel, M A

2004-01-01

An analysis of the Kimura 3ST model of DNA sequence evolution is given on the basis of its continuous Lie symmetries. The rate matrix commutes with a U(1) x U(1) x U(1) phase subgroup of the group GL(4) of 4 x 4 invertible complex matrices acting on a linear space spanned by the four nucleic acid base letters. The diagonal 'branching operator' representing speciation is defined, and shown to intertwine the U(1) x U(1) x U(1) action. Using the intertwining property, a general formula for the probability density on the leaves of a binary tree under the Kimura model is derived, which is shown to be equivalent to established phylogenetic spectral transform methods. (letter to the editor)

Investigation for thermal stability of U3Si2 and protection methods

International Nuclear Information System (INIS)

Zhang Huiying; Sun Jichang; Sun Rongxian

1994-08-01

The thermal stability of U 3 Si 2 in Ar, N 2 and air, and the interaction between U 3 Si 2 and Al, Zr have been investigated by thermal analysis method. According to the results of thermal analysis, protection measures for various procedures have been improved. From the practice, it shows that the protection measures can ensure the safety of production and raise the product quality as well as reduce the cost effectively

Radiation-induced grain subdivision and bubble formation in U3Si2 at LWR temperature

Science.gov (United States)

Yao, Tiankai; Gong, Bowen; He, Lingfeng; Harp, Jason; Tonks, Michael; Lian, Jie

2018-01-01

U3Si2, an advanced fuel form proposed for light water reactors (LWRs), has excellent thermal conductivity and a high fissile element density. However, limited understanding of the radiation performance and fission gas behavior of U3Si2 is available at LWR conditions. This study explores the irradiation behavior of U3Si2 by 300 keV Xe+ ion beam bombardment combining with in-situ transmission electron microscopy (TEM) observation. The crystal structure of U3Si2 is stable against radiation-induced amorphization at 350 °C even up to a very high dose of 64 displacements per atom (dpa). Grain subdivision of U3Si2 occurs at a relatively low dose of 0.8 dpa and continues to above 48 dpa, leading to the formation of high-density nanoparticles. Nano-sized Xe gas bubbles prevail at a dose of 24 dpa, and Xe bubble coalescence was identified with the increase of irradiation dose. The volumetric swelling resulting from Xe gas bubble formation and coalescence was estimated with respect to radiation dose, and a 2.2% volumetric swelling was observed for U3Si2 irradiated at 64 dpa. Due to extremely high susceptibility to oxidation, the nano-sized U3Si2 grains upon radiation-induced grain subdivision were oxidized to nanocrystalline UO2 in a high vacuum chamber for TEM observation, eventually leading to the formation of UO2 nanocrystallites stable up to 80 dpa.

U3Si2 behavior in H2O: Part I, flowing steam and the effect of hydrogen

Science.gov (United States)

Wood, E. Sooby; White, J. T.; Grote, C. J.; Nelson, A. T.

2018-04-01

Recent interest in U3Si2 as an advanced light water reactor fuel has driven assessment of numerous properties, but characterization of its response to H2O environments is absent from the literature. The behavior of U3Si2 in H2O containing atmospheres is investigated and presented in a two-part series of articles aimed to understand the degradation mechanism of U3Si2 in H2O. Reported here are thermogravimetric data for U3Si2 exposed to flowing steam at 250-470 °C. Additionally the response of U3Si2 to flowing Ar-6% H2 from 350 to 400 °C is presented. Microstructural degradation is observed following hours of exposure at 350 °C in steam. U3Si2 undergoes pulverization on the timescale of minutes when temperatures are increased above 400 °C. This mechanism is accelerated in flowing Ar-H2 at the same temperatures.

Analysis of transuranic isotopes in irradiated U3Si2-Al fuel by alpha spectrometry

International Nuclear Information System (INIS)

Dian Anggraini; Aslina B Ginting; Arif Nugroho

2011-01-01

Separation and analysis of transuranic isotopes (uranium and plutonium) in irradiated U 3 Si 2 -Al plate has been done. The analysis experiment includes sample preparation (i.e. cutting, dissolving, filtering, dilution), fission products separation from heavy elements, and analysis of transuranic isotopes content with alpha spectrometer. The separation of transuranic isotopes (U, Pu) was done by two methods, i.e. direct method and ion exchanger method with zeolite. Measurement of standard transuranic isotope (AMR 43) and standard U 3 O 8 was done in advance in order to determine percentage of 235 U recovery and detector efficiency. Recovery of 235 U isotope was obtained as much as 92,58%, which fulfills validation requirement, and the detector efficiency was 0.314. Based on the measured recovery and detector efficiency, the separation was done by direct electrodeposition method of 250 µL irradiated U 3 Si 2 -Al solution. The deposited sample was subsequently analyzed with alpha spectrometer. The separation with ion exchanger was done by mixing and shaking of 300 µL irradiated U 3 Si 2 -Al solution and 0.5 gram zeolite to separate the liquid phase from the solid phase. The liquid phase was electrodeposited and analyzed with alpha spectrometer. The analysis of transuranic isotopes (U, Pu) by both methods shows different results. Heavy element ( 238 U, 236 U, 234 U, 239 Pu) content obtained by direct method was 0.0525 g/g and 235 U= 0.0076 g/g, while the separation using zeolite ion exchanger resulted in Heavy element = 0.0253 g/g and 235 U = 0.0092 g/g. (author)

Irradiation mixing of Al into U3Si

International Nuclear Information System (INIS)

Birtcher, R.C.; Ding, F.R.; Kestel, B.J.; Baldo, P.M.; Zaluzec, N.J.

1995-11-01

Thermal and irradiation induced intermixing of uranium silicide reactor fuels with the aluminum cladding is an important consideration in understanding their fission gas and fuel swelling behavior. The authors have used Rutherford backscattering to follow the behavior of an Al thin film on U 3 Si and U 3 Si 2 during 1.5 MeV Kr ion irradiation at temperatures of 30 and 350 C. After an initial dose during which no intermixing occurs, the Al mixes quickly into U 3 Si. The threshold dose is believed to be associated with an oxide layer between the Al and the uranium silicide. At 300 C and doses greater than threshold, rates of mixing and aluminide phase growth are extracted

U3O8 microspheres sintering kinetics

International Nuclear Information System (INIS)

Godoy, A.L.E.

1986-01-01

U 3 O 8 microspheres sintering kinetics was determined using a hot-stage optical microscopy apparatus, able to reach temperature up to 1350 0 C in controlled atmospheres. The sintered material had its microstructure analysed by optical and electron microscopy. The microspheres were characterized initialy utilizing X-ray diffractometry and thermogravimetry. The equation which describes the microspheres shrinkage in function of the time was obtained using finite difference analysis X-ray diffractometry indicated hexagonal structure for the microspheres main starting material, ammonium diuranate thermogravimetric analysis showed reduction of this material to U 3 O 8 at 600 0 C. Ceramography results showed 5 hours sintered microspheres grain sizes G vary with the temperature. Sintered U 3 O 8 micrographs compared with published results for UO 2 , indicate similar homogeneity microstructural characteristics and suggest the processed micorspheres to be potentially useful as nuclear fuels. (Author) [pt

Low silicon U(Al,Si)3 stabilization by Zr addition

International Nuclear Information System (INIS)

Pizarro, L.M.; Alonso, P.R.; Rubiolo, G.H.

2009-01-01

Previous knowledge states that (U,Zr)Al 3 and U(Al,Si) 3 phases with Zr and Si content higher than 6 at.% (7.7 wt%) and 4 at.% (1.4 wt%), respectively, does not partially transform to UAl 4 at 600 o C. In this work, four alloys within the quaternary system U-Al-Si-Zr were made with a fixed nominal 0.18 at.% (0.1 wt%) Si content in order to assess the synergetic effect of both Zr and Si alloying elements to the thermodynamic stability of the (U,Zr)(Al,Si) 3 phase. Heat treatments at 600 deg. C were undertaken and samples were analyzed by means of XRD, EPMA and EDS techniques. A remarkable conclusion is that addition of 0.3 at.% Si in the (U,Zr)(Al,Si) 3 phase reduces in 2.7 at.% the necessary Zr content to inhibit its transformation to U(Al,Si) 4 .

Algebraic formulas for some nontrivial U/sub n/ 6j symbols and U/sub m/n contains U/sub m/ x U/sub n/ 3jm symbols

International Nuclear Information System (INIS)

Haase, R.W.; Butler, P.H.

1985-01-01

We give tables of algebraic formulas for some nontrivial 6j symbols and 3jm symbols of the unitary groups. The tables demonstrate that the building-up method can be used successfully to obtain the rank dependence of unitary group j and jm symbols. To emphasize the rank-dependent nature of this calculation, we have employed the composite Young tableaux notation (or back-to-back notation) to label the unitary group irreps. In using this notation, the transpose conjugate symmetry of the corresponding composite Young diagram leads to a new symmetry of the unitary group 6j and 3jm symbols. The transposition of the groups U/sub m/ and U/sub n/ gives rise to a further symmetry of the 3jm symbols of U/sub m/n contains U/sub m/ x U/sub n/

On some factors affecting the nonstoichiometry in U 3O 8

Science.gov (United States)

Fujino, Takeo; Tagawa, Hiroaki; Adachi, Takeo

1981-03-01

The nonstoichiometry of U 3O 8 was studied under various conditions. The {O}/{U} atom ratios obtained by the oxidation of uranium metal in air followed by cooling with moderate rates (method 1) are 2.67 ± 0.01 in the temperature range 700 900°C and 2.662 ± 0.005 at 1000°C and are generally larger than the ratio by thermogravimetry. If the oxidation was carried out in a crucible with a lid, a compositional peak was observed at 900 950°C, which did not appear for the U 3O 8 samples from UO 2. The U 3O 8 made from UO 2 by method 1 have {O}/{U} ratios 2.655 ± 0.005 (700° C), 2.653 ± 0.004 (800° C), 2.648 ± 0.004 (900° C) and 2.645 ± 0.003 (1000° C). Differences were observed in the O/U ratios of heating and cooling series. X-ray diffraction analysis showed several additional peaks other than those of α-U 3O 8 for the samples which exhibited the compositional peak.

Tank 241-U-103, grab samples 3U-99-1, 3u-99-2 and 3U-99-3

Energy Technology Data Exchange (ETDEWEB)

STEEN, F.H.

1999-08-25

This document is the final report for tank 241-U-103 grab samples. Three grab samples were collected from riser 13 on March 12, 1999 and received by the 222-S laboratory on March 15, 1999. Analyses were performed in accordance with the Compatibility Grab Sampling and Analysis Plan for Fiscal year 1999 (TSAP) and the Data Quality Objectives for Tank Farms Waste Compatibility Program (DQO). The analytical results are presented in the data summary report. None of the subsamples submitted for differential scanning calorimetry (DSC), total organic carbon (TOC) and plutonium 239 (Pu239) analyses exceeded the notification limits as stated in TSAP.

The determination of molar volumes of uranous nitrate and nitric acid in systems of U(NO3)4-HNO3-H2O and U(NO3)4-HNO3-30% TBP kerosene

International Nuclear Information System (INIS)

Tao Chengying

1986-01-01

The data of molar volumes of uranous nitrate and nitric acid are necessary for the calculation of the changes in phase volume during the extraction in U(NO 3 ) 4 -HNO 3 /30%TBP-kerosene system. However, the data of the partial molar volume of U(NO 3 ) 4 are not available in literature. In the present work, the molar volumes of U(NO 3 ) 4 and HNO 3 are calculated by linear fitting of the experimental data. The result of the molar volume of HNO 3 is consistent with those in literature

Fabrication and thermophysical property characterization of UN/U3Si2 composite fuel forms

Science.gov (United States)

White, J. T.; Travis, A. W.; Dunwoody, J. T.; Nelson, A. T.

2017-11-01

High uranium density composite fuels composed of UN and U3Si2 have been fabricated using a liquid phase sintering route at temperatures between 1873 K and 1973 K and spanning compositions of 10 vol% to 40 vol% U3Si2. Microstructural analysis and phase characterization revealed the formation of an U-Si-N phase of unknown structure. Microcracking was observed in the U-Si portion of the composite microstructure that likely originates from the mismatched coefficient of thermal expansion between the UN and U3Si2 leading to stresses on heating and cooling of the composite. Thermal expansion coefficient, thermal diffusivity, and thermal conductivity were characterized for each of the compositions as a function of temperature to 1673 K. Hysteresis is observed in the thermal diffusivity for the 20 vol% through 40 vol% specimens between room temperature and 1273 K, which is attributed to the microcracking in the U-Si phase. Thermal conductivity of the composites was modeled using the MOOSE framework based on the collected microstructure data. The impact of irradiation on thermal conductivity was also simulated for this class of composite materials.

The qualification of U3O8 as research reactor fuel

International Nuclear Information System (INIS)

Krull, W.

1983-01-01

This report summarizes the today knowledge of the qualification status of U 3 O 8 as low enriched ( 3 O 8 is so far qualified to start testing of ten (10) fuel elements with an U-density of 3.1 g U/cc in the FRG-2 research reactor. (orig.) [de

HYDROGEOLOGIC CHARACTERIZATION OF THE U-3bl COLLAPSE ZONE

International Nuclear Information System (INIS)

Bechtel Nevada and National Security Technologies, LLC

2006-01-01

The U-3bl collapse crater was formed by an underground nuclear test in August 1962. This crater and the adjoining U-3ax crater were subsequently developed and used as a bulk low-level radioactive waste disposal cell (U-3ax/bl), which is part of the Area 3 Radioactive Waste Management Site at the Nevada Test Site (NTS). Various investigations have been conducted to assess the hydrogeologic characteristics and properties in the vicinity of the U-3ax/bl waste disposal cell. This report presents data from one of these investigations, conducted in 1996. Also included in this report is a review of pertinent nuclear testing records, which shows that the testing operations and hydrogeologic setting of the U-3ax/bl site were typical for the period and location of testing

Synthesis of [3-14C]- and [phenyl-U-14C] olaquindox

International Nuclear Information System (INIS)

Maul, W.; Scherling, D.; Seng, F.

1981-01-01

Olaquindox is a new feed additive. [ 14 C]Olaquindox, labelled in different positions, was needed for tracer-studies of pharmacokinetics, biotransformation and residues in several species of animals. 2-[N-(2-hydroxethyl)-carbamoyl]-3-methyl-[3- 14 C]quinoxaline-1,4-dioxide([3- 14 C]Olaquindox) was synthesized from barium[ 14 C]carbonate (22 mmoles; 1.15 Ci) via [1- 14 C]acetic acid, sodium[1- 14 C]acetate, [1- 14 C]acetylchloride, ethyl[3- 14 C]acetoacetate and 2-carbethoxy-3-methyl-[3- 14 C]quinoxaline-1,4-dioxide with an overall yield of 10%, based on barium[ 14 C]carbonate. The radiochemical purity was better than 98% (tlc). The specific activities of three preparations were 10.5, 8.4 and 5.45 μCi/mg respectively. [phenyl-U- 14 C]Olaquindox was synthesized starting from [U- 14 C]aniline (19.8 mmoles; 284.4 mCi). Intermediate products were N-acetyl[U- 14 C]aniline, 2-nitro-N-acetyl[U- 14 C]aniline, 2-nitro[U- 14 C]aniline and [U- 14 C]benzofurazanoxide. The total yield was 50% as calculated for [U- 14 C]aniline. At calibration samples of two preparations showed specific activities of 49.5 and 11.1 μCi/mg respectively. The radiochemical purity was checked by tlc and exceeded 98%. (author)

First-principles investigations on the electronic structures of U{sub 3}Si{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Wang, Tong [College of Information & Communication, Harbin Engineering University, Harbin, 150001 (China); Qiu, Nianxiang [Engineering Laboratory of Specialty Fibers and Nuclear Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, 315201 (China); Wen, Xiaodong [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi, 030001 (China); Synfuels China, 100195 (China); Tian, Yonghui [College of Life Science, Sichuan University, Chengdu, Sichuan, 610064 (China); He, Jian [Center for Translational Medicine, Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023 (China); Luo, Kan; Zha, Xianhu; Zhou, Yuhong; Huang, Qing; Lang, Jiajian [Engineering Laboratory of Specialty Fibers and Nuclear Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, 315201 (China); Du, Shiyu, E-mail: dushiyu@nimte.ac.cn [Engineering Laboratory of Specialty Fibers and Nuclear Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, 315201 (China)

2016-02-15

U{sub 3}Si{sub 2} has been widely utilized as a high-power uranium fuel for research reactors due to its high density of uranium. However, theoretical investigations on this material are still scarce up to now. For this reason, the computational study via density functional theory (DFT) is performed on the U{sub 3}Si{sub 2} compound in this work. The properties of U{sub 3}Si{sub 2}, such as stable crystalline structures, density of states, charge distributions, formation energy of defects, as well as the mechanical properties are explored. The calculation results show that the U{sub 3}Si{sub 2} material is metallic and brittle, which is in good agreement with the previous experimental observations. The formation energy of uranium vacancy defect is predicted to be the lowest, similar with that of UN. The theoretical investigation of this work is expected to provide new insight of uranium silicide fuels.

Thermal expansion studies on UMoO5, UMoO6, Na2U(MoO4)3 and Na4U(MoO4)4

International Nuclear Information System (INIS)

Keskar, Meera; Dahale, N.D.; Krishnan, K.

2009-01-01

In the present work, thermal expansion behavior of lower valent sodium uranium molybdates, i.e., Na 2 U(MoO 4 ) 3 and Na 4 U(MoO 4 ) 4 were studied under vacuum in the temperature range of 298-873 K using high temperature X-ray diffractometry (HTXRD). Expansion behaviors of UMoO 5 and UMoO 6 were also studied in vacuum from 298 to 873 K and 773 K, respectively. UMoO 5 was synthesized by reacting UO 2 with MoO 3 in equi-molar proportion in evacuated sealed quartz ampoule at 1173 K for 14 h. Na 2 U(MoO 4 ) 3 and Na 4 U(MoO 4 ) 4 were prepared by reacting UMoO 5 and MoO 3 with 1 and 2 moles of Na 2 MoO 4 , respectively, at 873 K in evacuated sealed quartz ampoule. XRD data of UMoO 5 and UMoO 6 were indexed on orthorhombic and monoclinic systems, respectively, whereas, the data of Na 2 U(MoO 4 ) 3 and Na 4 U(MoO 4 ) 4 were indexed on tetragonal system. The lattice parameters and cell volume of all the four compounds, fit into polynomial expression with respect to temperature, showed positive thermal expansion (PTE) up to 873 K.

Examinations of the irradiation behaviour of U3Si2 test fuel plates with low enrichment

International Nuclear Information System (INIS)

Muellauer, J.

1989-01-01

Five low-enriched (19.7% 235 U), high-density (4.7 gU/cm/ 3 ) U 3 Si 2 -test fuel plates (miniplates) with different fine grain contents have been qualified under irradiation. During the course of irradiation up to burnup of 63% 235 U depletion, no released fractions of gaseous or solid fission products from the fuel plate to the rig coolant were detected. The measured swelling rate of the fuel zone (meat) is less than 0.45% ΔV/10 20 fissions/cm 3 the blister-threshold temperature of the fuel plates is above 520 0 C. The favourable irradiation behavior of the U 3 Si 2 fuel plates was not influenced by using higher amounts of fine grained particles (40% [de

Determination of interstitial oxygen atom position in U2N3+xOy by near edge structure study

Science.gov (United States)

Jiang, A. K.; Zhao, Y. W.; Long, Z.; Hu, Y.; Wang, X. F.; Yang, R. L.; Bao, H. L.; Zeng, R. G.; Liu, K. Z.

2018-06-01

The determination of interstitial oxygen atom site in U2N3+xOy film could facilitate the understanding of the oxidation mechanism of α-U2N3 and the effect of U2N3+xOy on anti-oxidation. By comparing the similarities and variances between N K edge and O K edge electron energy loss spectra (EELS) for oxidized α-U2N3 and UO2, the present work looks at the local structure of nitrogen and oxygen atoms in U2N3+xOy film, identifying the most possible position of interstitial O atom.

SU(3)_C× SU(2)_L× U(1)_Y( × U(1)_X ) as a symmetry of division algebraic ladder operators

Science.gov (United States)

Furey, C.

2018-05-01

We demonstrate a model which captures certain attractive features of SU(5) theory, while providing a possible escape from proton decay. In this paper we show how ladder operators arise from the division algebras R, C, H, and O. From the SU( n) symmetry of these ladder operators, we then demonstrate a model which has much structural similarity to Georgi and Glashow's SU(5) grand unified theory. However, in this case, the transitions leading to proton decay are expected to be blocked, given that they coincide with presumably forbidden transformations which would incorrectly mix distinct algebraic actions. As a result, we find that we are left with G_{sm} = SU(3)_C× SU(2)_L× U(1)_Y / Z_6. Finally, we point out that if U( n) ladder symmetries are used in place of SU( n), it may then be possible to find this same G_{sm}=SU(3)_C× SU(2)_L× U(1)_Y / Z_6, together with an extra U(1)_X symmetry, related to B-L.

Reaction kinetics aspect of U3O8 kernel with gas H2 on the characteristics of activation energy, reaction rate constant and O/U ratio of UO2 kernel

International Nuclear Information System (INIS)

Damunir

2007-01-01

The reaction kinetics aspect of U 3 O 8 kernel with gas H 2 on the characteristics of activation energy, reaction rate constant and O/U ratio of UO 2 kernel had been studied. U 3 O 8 kernel was reacted with gas H 2 in a reduction furnace at varied reaction time and temperature. The reaction temperature was varied at 600, 700, 750 and 850 °C with a pressure of 50 mmHg for 3 hours in gas N 2 atmosphere. The reation time was varied at 1, 2, 3 and 4 hours at a temperature of 750 °C using similar conditions. The reaction product was UO 2 kernel. The reaction kinetic aspect between U 3 O 8 and gas H 2 comprised the minimum activation energy (ΔE), the reaction rate constant and the O/U ratio of UO 2 kernel. The minimum activation energy was determined from a straight line slope of equation ln [{D b . R o {(1 - (1 - X b ) ⅓ } / (b.t.Cg)] = -3.9406 x 10 3 / T + 4.044. By multiplying with the straight line slope -3.9406 x 10 3 , the ideal gas constant (R) 1.985 cal/mol and the molarity difference of reaction coefficient 2, a minimum activation energy of 15.644 kcal/mol was obtained. The reaction rate constant was determined from first-order chemical reaction control and Arrhenius equation. The O/U ratio of UO 2 kernel was obtained using gravimetric method. The analysis result of reaction rate constant with chemical reaction control equation yielded reaction rate constants of 0.745 - 1.671 s -1 and the Arrhenius equation at temperatures of 650 - 850 °C yielded reaction rate constants of 0.637 - 2.914 s -1 . The O/U ratios of UO 2 kernel at the respective reaction rate constants were 2.013 - 2.014 and the O/U ratios at reaction time 1 - 4 hours were 2.04 - 2.011. The experiment results indicated that the minimum activation energy influenced the rate constant of first-order reaction and the O/U ratio of UO 2 kernel. The optimum condition was obtained at reaction rate constant of 1.43 s -1 , O/U ratio of UO 2 kernel of 2.01 at temperature of 750 °C and reaction time of 3

U.S. phosphate industry as a source of U3O8 to the year 2000

International Nuclear Information System (INIS)

Borg, I.Y.

1976-01-01

U 3 O 8 recovered as a by-product of the phosphate fertilizer industry may equal 3600-5200 tons by 1985 and represent 7-10 percent of the anticipated annual U.S. demand. If the enormous U.S. phosphate reserves and resources are mined primarily for their uranium content they appear sufficient to fill more than twice the projected cumulative U.S. demand to the year 2000

Post-irradiation examination of prototype Al-64 wt% U3Si2 fuel rods from NRU

International Nuclear Information System (INIS)

Sears, D.F.; Primeau, M.F.; Buchanan, C.; Rose, D.

1997-01-01

Three prototype fuel rods containing Al-64 wt% U 3 Si 2 (3.15 gU/cm 3 ) have been irradiated to their design burnup in the NRU reactor without incident. The fuel was fabricated using production-scale equipment and processes previously developed for Al-U 3 Si fuel fabrication at Chalk River Laboratories, and special equipment developed for U 3 Si 2 powder production and handling. The rods were irradiated in NRU up to 87 at% U-235 burnup under typical driver fuel conditions; i.e., nominal coolant inlet temperature 37 degrees C, inlet pressure 654 kPa, mass flow 12.4 L/s, and element linear power ratings up to 73 kW/m. Post-irradiation examinations showed that the fuel elements survived the irradiation without defects. Fuel core diametral increases and volumetric swelling were significantly lower than that of Al-61 wt% U 3 Si fuel irradiated under similar conditions. This irradiation demonstrated that the fabrication techniques are adequate for full-scale fuel manufacture, and qualified the fuel for use in AECL's research reactors

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)

Thermal Characteristic Of AIMg2 Cladding And Fuel Plates Of U3Si2-Al With Various Uranium Loading

International Nuclear Information System (INIS)

Aslina, Br. G.; Suparjo; Aggraini, D.; Hasbullah, N.

1998-01-01

Thermal characteristic analyzed in this paper included linear expansion value, coefficient expansion, and enthalpy of cladding material fuel core and fuel plate of U 3 Si 2 -AI. Before analyzing, the fresh cladding of AIMg2 (without treatment) and the rolled AIMg2 were annealed at temperature of 425 o C for 1 hour, and the fuel plates of U 3 Si 2 -AI was prepared for various uranium loading of 0.9 - 3.6 - 4.2 - 4.8 and 5.2 g/cm 3 . Linear expansion nominal value and expansion coefficient were analyzed by using Dilatometer whereas enthalpy determination used Differential Thermal Analysis (DTA). The linear expansion and expansion coefficient analysis was performed to study the dimension cladding and of fuel plates during their stay in the reactor core, whereas determination of enthalpy was carried out to estimate the energy absorbed and released by fuel meat of U 3 Si 2 -AI to the cooling water through AlMg2 as a cladding. The result showed that the linear expansion and expansion coefficient of fresh AIMg2 cladding, rolled AIMg2 and fuel plates of U 3 Si 2 -AI are increased with the increase of temperature as well as the increase of uranium loading. The enthalpy measure showed that the enthalpy of fresh AIMg2 is smaller than that of rolled AIMg2 but melting temperature of fresh AIMg2 is greater than that of rolled AIMg2. The enthalpy of fuel plates and meat of U 3 Si 2 -AI is less than that of plates of U 3 Si 2 -AI. The enthalpy of fuel platers and meat of U 3 Si 2 -AI decrease with the increase of uranium loading. It is concluded that the fuel meat more reactive than fuel plates of U 3 Si 2 -AI

Mechanical behaviour of U3O8-Al cermets

International Nuclear Information System (INIS)

Figueredo, A.M. de; Ferreira, I.

1981-01-01

Homogeneous, high density U 3 O 8 -Al cermets, containing between 5 W% and 55 Wt% of U 3 ω 8 were fabricated using hot swaging and powder metallurgy technics. Tensile tests were performed at room temperature on specimens obtained from the cermets fabricated. The results show that the ultimate tensile strength (UTS) and elongation to fracture decrease with increasing U 3 O 8 in the cermet. The UTS is shown to be proportional to the minimum matrix load bearing cross-sectional area. The main influence of an increase in the content of U 3 O 8 in the cermet appears to be the decrease in the minimum matrix, load bearing cross-section. (Author) [pt

7 CFR 51.3053 - U.S. No. 3.

Science.gov (United States)

2010-01-01

... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... Standards for Florida Avocados Grades § 51.3053 U.S. No. 3. “U.S. No. 3” consists of avocados of similar...

Preparation and melting of uranium from U3O8

International Nuclear Information System (INIS)

Hur, Jin-Mok; Choi, In-Kyu; Cho, Soo-Haeng; Jeong, Sang-Mun; Seo, Chung-Seok

2008-01-01

In this paper, we report on the preparation and melting of uranium in association with a spent nuclear fuel conditioning process. U 3 O 8 powder was electrochemically reduced in a mixture of molten LiCl-Li 2 O (∼3 wt.% of Li 2 O in LiCl) at 650 deg. C resulting in the formation of uranium and Li 2 O with a yield of >99%. When the powder of uranium with a residual LiCl-Li 2 O salt was heated in order to melt the metal, the uranium oxidation to UO 2 due to the reaction with Li 2 O was observed. We were able to synthesize FeU 6 by using a Fe based cathode during the U 3 O 8 reduction procedure. FeU 6 could be melted to below the temperatures where the oxidation of uranium by Li 2 O occurred. The idea of compound formation and melting is applicable to the melting and casting of a spent nuclear fuel which contains oxidative residual salts due to its conditioning in a molten salt

Ugonin U stimulates NLRP3 inflammasome activation and enhances inflammasome-mediated pathogen clearance

Directory of Open Access Journals (Sweden)

Chun-Yu Chen

2017-04-01

Full Text Available The NOD-like receptor pyrin domain 3 (NLRP3 inflammasome contains Nod-like receptors, a subclass of pattern recognition receptors, suggesting that this complex has a prominent role in host defenses. Various structurally diverse stimulators activate the NLRP3 inflammasome through different signaling pathways. We previously reported that ugonin U (UgU, a natural flavonoid isolated from Helminthostachys zeylanica (L Hook, directly stimulates phospholipase C (PLC and triggers superoxide release in human neutrophils. In the present study, we showed that UgU induced NLRP3 inflammasome assembly and subsequent caspase-1 and interleukin (IL-1β processing in lipopolysaccharide-primed human monocytes. Moreover, UgU elicited mitochondrial superoxide generation in a dose-dependent manner, and a specific scavenger of mitochondrial reactive oxygen species (ROS diminished UgU-induced IL-1β and caspase-1 activation. UgU induced Ca2+ mobilization, which was inhibited by treatment with inhibitors of PLC or inositol triphosphate receptor (IP3R. Blocking Ca2+ mobilization, PLC, or IP3R diminished UgU-induced IL-1β release, caspase-1 activation, and mitochondrial ROS generation. These data demonstrated that UgU activated the NLPR3 inflammasome activation through Ca2+ mobilization and the production of mitochondrial ROS. We also demonstrated that UgU-dependent NLRP3 inflammasome activation enhanced the bactericidal function of human monocytes. The ability of UgU to stimulate human neutrophils and monocytes, both of which are professional phagocytes, and its capacity to activate the NLRP3 inflammasome, which is a promising molecular target for developing anti-infective medicine, indicate that UgU treatment should be considered as a possible novel therapy for treating infectious diseases.

Structure of tris(trimethylsilylcyclopentadienyl)uranium(III), [(CH3)3SiC5H43U

International Nuclear Information System (INIS)

Brennan, J.; Andersen, R.A.; Zalkin, A.

1986-02-01

Crystals of [(CH 3 ) 3 SiC 5 H 4 ] 3 U are orthorhombic, Pbca, with a = 22.630(8), b = 29.177(10) and c = 8.428(3) A at 23 0 C. For Z = 8 the calculated density is 1.551 g/cm 3 . The structure was refined by full-matrix least-squares to a conventional R factor of 0.041 [2251 data, F 2 > 2 sigma(F 2 )]. The uranium atom is bonded to the three cyclopentadienyl rings in a pentahapto fashion and is in the plane of the ring centroids. The U to ring distances are 2.54, 2.47 and 2.51 A, and the average U-C distance is 2.78 +- 0.04 A. 7 refs., 1 fig., 3 tabs

Drosophila SMN complex proteins Gemin2, Gemin3, and Gemin5 are components of U bodies

International Nuclear Information System (INIS)

Cauchi, Ruben J.; Sanchez-Pulido, Luis; Liu, Ji-Long

2010-01-01

Uridine-rich small nuclear ribonucleoproteins (U snRNPs) play key roles in pre-mRNA processing in the nucleus. The assembly of most U snRNPs takes place in the cytoplasm and is facilitated by the survival motor neuron (SMN) complex. Discrete cytoplasmic RNA granules called U bodies have been proposed to be specific sites for snRNP assembly because they contain U snRNPs and SMN. U bodies invariably associate with P bodies, which are involved in mRNA decay and translational control. However, it remains unknown whether other SMN complex proteins also localise to U bodies. In Drosophila there are four SMN complex proteins, namely SMN, Gemin2/CG10419, Gemin3 and Gemin5/Rigor mortis. Drosophila Gemin3 was originally identified as the Drosophila orthologue of human and yeast Dhh1, a component of P bodies. Through an in silico analysis of the DEAD-box RNA helicases we confirmed that Gemin3 is the bona fide Drosophila orthologue of vertebrate Gemin3 whereas the Drosophila orthologue of Dhh1 is Me31B. We then made use of the Drosophila egg chamber as a model system to study the subcellular distribution of the Gemin proteins as well as Me31B. Our cytological investigations show that Gemin2, Gemin3 and Gemin5 colocalise with SMN in U bodies. Although they are excluded from P bodies, as components of U bodies, Gemin2, Gemin3 and Gemin5 are consistently found associated with P bodies, wherein Me31B resides. In addition to a role in snRNP biogenesis, SMN complexes residing in U bodies may also be involved in mRNP assembly and/or transport.

Drosophila SMN complex proteins Gemin2, Gemin3, and Gemin5 are components of U bodies

Energy Technology Data Exchange (ETDEWEB)

Cauchi, Ruben J.; Sanchez-Pulido, Luis [MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX (United Kingdom); Liu, Ji-Long, E-mail: jilong.liu@dpag.ox.ac.uk [MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX (United Kingdom)

2010-08-15

Uridine-rich small nuclear ribonucleoproteins (U snRNPs) play key roles in pre-mRNA processing in the nucleus. The assembly of most U snRNPs takes place in the cytoplasm and is facilitated by the survival motor neuron (SMN) complex. Discrete cytoplasmic RNA granules called U bodies have been proposed to be specific sites for snRNP assembly because they contain U snRNPs and SMN. U bodies invariably associate with P bodies, which are involved in mRNA decay and translational control. However, it remains unknown whether other SMN complex proteins also localise to U bodies. In Drosophila there are four SMN complex proteins, namely SMN, Gemin2/CG10419, Gemin3 and Gemin5/Rigor mortis. Drosophila Gemin3 was originally identified as the Drosophila orthologue of human and yeast Dhh1, a component of P bodies. Through an in silico analysis of the DEAD-box RNA helicases we confirmed that Gemin3 is the bona fide Drosophila orthologue of vertebrate Gemin3 whereas the Drosophila orthologue of Dhh1 is Me31B. We then made use of the Drosophila egg chamber as a model system to study the subcellular distribution of the Gemin proteins as well as Me31B. Our cytological investigations show that Gemin2, Gemin3 and Gemin5 colocalise with SMN in U bodies. Although they are excluded from P bodies, as components of U bodies, Gemin2, Gemin3 and Gemin5 are consistently found associated with P bodies, wherein Me31B resides. In addition to a role in snRNP biogenesis, SMN complexes residing in U bodies may also be involved in mRNP assembly and/or transport.

Scalar mesons and glueballs in a chiral U(3)xU(3) quark model with 't Hooft interaction

International Nuclear Information System (INIS)

Nagy, M.; Volkov, M.K.; Yudichev, V.L.

2000-01-01

In a U(3)xU(3) quark chiral model of the Nambu-Jona-Lasino (NJL) type with the 't Hooft interaction, the ground scalar isoscalar mesons and a scalar glueball are described. The glueball (dilaton) is introduced into the effective meson Lagrangian written in a chirally symmetric form on the basis of scale invariance. The singlet-octet mixing of scalar isoscalar mesons and their mixing with the glueball are taken into account. Mass spectra of the scalar mesons and glueball and their strong decays are described

Spectroscopy and electrochemistry of U(IV/III) in basic AlCl3-EMIC

International Nuclear Information System (INIS)

Anderson, C.J.; Deakin, M.R.; Choppin, G.R.; Heerman, L.; D'Olieslager, W.; Pruett, D.J.

1990-01-01

The electrochemistry of U(IV) has been investigated in the solvent AlCl 3 -1-ethyl-3-methyl imidazolium chloride (EMIC), a room temperature ionic liquid. In basic solutions ( 3 ) the reduction of U(IV) to U(III) on glassy carbon electrodes is reversible. Spectroscopic data as well as measurements of the formal potential for U(IV)/U(III) as a function of the basic melt composition indicate that U(IV) and U(III) are both hexachloro anions. Diffusion coefficients for these species have been measured by two methods. The values are comparable to those of transition metal hexachloro complexes in the same solvent, supporting the assignment of UCl 6 2- and UCl 6 3-

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)

U3Si2 behavior in H2O environments: Part II, pressurized water with controlled redox chemistry

Science.gov (United States)

Nelson, A. T.; Migdisov, A.; Wood, E. Sooby; Grote, C. J.

2018-03-01

Recent interest in U3Si2 as an advanced light water reactor fuel has driven assessment of numerous properties, but characterization of its response to H2O environments is sparse in available literature. The behavior of U3Si2 in H2O containing atmospheres is investigated and presented in a two-part series of articles. This work examines the behavior of U3Si2 following exposure to pressurized H2O at temperatures from 300 to 350 °C. Testing was performed using two autoclave configurations and multiple redox conditions. Use of solid state buffers to attain a controlled water chemistry is also presented as a means to test actinide-bearing systems. Buffers were used to vary the hydrogen concentration between 1 and 30 parts per million H2. Testing included UN, U3Si5, and UO2. Both UN and U3Si5 were found to rapidly pulverize in less than 50 h at 300 °C. Uranium dioxide was included as a control for the autoclave system, and was found to be minimally impacted by exposure to pressurized water at the conditions tested for extended time periods. Testing of U3Si2 at 300 °C found reasonable stability through 30 days in 1-5 ppm H2. However, pulverization was observed following 35 days. The redox condition of testing strongly affected pulverization. Characterization of the resulting microstructures suggests that the mechanism responsible for pulverization under more strongly reducing conditions differs from that previously identified. Hydride formation is hypothesized to drive this transition. Testing performed at 350 °C resulted in rapid pulverization of U3Si2 in under 50 h.

Influence of Fuel Meat Porosity on Heat Capacities of Fuel Element Plate U3Si2-Al

International Nuclear Information System (INIS)

Ginting, Aslina Br.; Supardjo; Sutri Indaryati

2007-01-01

Analyze of heat capacities of Al powder, AIMg 2 cladding, U 3 Si 2 powder and PEB U 3 Si 2 -Al with the meat porosity of 4.9; 5.53 ; 6.25 ; 6.95 %; 7.90; 8.66% have been done. Analysis was conducted by using Differential Scanning Calorimeter (DSC) at temperature 30℃ to 450℃ with heating rate 1℃ /minute in Argon gas media. The purpose of analyze is to know the influence of increasing of fuel meat porosity on heat capacities because increasing of percentage of meat porosity will cause degradation the of heat capacities of PEB U 3 Si 2 -Al. Result of analysis showed that the heat capacities of Al powder, AIMg 2 cladding increase by temperature, while heat capacities of U 3 Si 2 powder was stable with increasing of temperature up to 450℃. Analysis of heat capacities toward PEB U 3 Si 2 -Al indicate that increasing of fuel meat porosity of caused degradation of the heat capacities of PEB U 3 Si 2 -Al. Data obtained were expected to serve the purpose of input to fabricator of research reactor fuel in for design of fuel element type silicide with high loading. (author)

Spark plasma sintering and microstructural analysis of pure and Mo doped U3Si2 pellets

Science.gov (United States)

Lopes, Denise Adorno; Benarosch, Anna; Middleburgh, Simon; Johnson, Kyle D.

2017-12-01

U3Si2 has been considered as an alternative fuel for Light Water Reactors (LWRs) within the Accident Tolerant Fuels (ATF) initiative, begun after the Fukushima-Daiichi Nuclear accidents. Its main advantages are high thermal conductivity and high heavy metal density. Despite these benefits, U3Si2 presents an anisotropic crystallographic structure and low solubility of fission products, which can result in undesirable effects under irradiation conditions. In this paper, spark plasma sintering (SPS) of U3Si2 pellets is studied, with evaluation of the resulting microstructure. Additionally, exploiting the short sintering time in SPS, a molybdenum doped pellet was produced to investigate the early stages of the Mo-U3Si2 interaction, and analyze how this fission product is accommodated in the fuel matrix. The results show that pellets of U3Si2 with high density (>95% TD) can be obtained with SPS in the temperature range of 1200°C-1300 °C. Moreover, the short time employed in this technique was found to generate a unique microstructure for this fuel, composed mainly of closed nano-pores (uranium with small quantities of dissolved Si and Mo at the front of the reaction.

Synthesis, crystal structure and optical properties of the catena-metaphosphates Ce(PO3)4 and U(PO3)4

International Nuclear Information System (INIS)

Hoeppe, Henning A.; Daub, Michi

2012-01-01

The catena-metaphosphates of tetravalent cerium and tetravalent uranium were obtained as phase pure crystalline powders by reaction of the respective dioxides with phosphoric acid at 500 C. Ce(PO 3 ) 4 and U(PO 3 ) 4 crystallise in space group C2/c (Z = 16, a Ce = 13.7696(3) Aa, b Ce = 29.7120(7) Aa, c Ce = 8.9269(2) Aa, β Ce = 90.00(1) Aa 3 and a U = 13.786(3) Aa, b U = 29.843(6) Aa, c U = 8.9720(18) Aa, β U = 90.01(3) Aa 3 ). The vibrational and optical spectra of pale yellow Ce(PO 3 ) 4 and emerald-greenish U(PO 3 ) 4 are also reported. (orig.)

Solid state reactions of MoO3 and Na2MoO4 with (U.85,Ce.15)O2x

International Nuclear Information System (INIS)

Dahale, N.D.; Keskar, Meera; Singh Mudher, K.D.; Chawla, K.L.

1999-01-01

(U .85 ,Ce .15 )MoO 6-x was prepared by the solid state reactions of (U .85 ,Ce .15 )O 2±x with MoO 3 in air at 600 deg C. Solid state reactions of Na 2 MoO 4 with (U .85 ,Ce .15 )MoO 6.x up to 550 deg C in air led to the formation of Na 2 (U .85 ,Ce .15 )Mo 2 O 10-x and Na 2 (U .85 , Ce .15 ) 2 Mo 3 O 16-x . These compounds were characterised by x-ray and thermal methods. The x-ray powder data of (U .85 , Ce .15 ) MoO 6-x were indexed on monoclinic system whereas, data of Na 2 (U .85 ,Ce .15 ) Mo 2 O 10-x and Na 2 (U .85 ,Ce .15 ) 2 Mo 3 O 16-x were indexed on orthorhombic and monoclinic system respectively. (author)

238U, 234U and 232Th in seawater

International Nuclear Information System (INIS)

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

1986-01-01

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

Preparation methods of U3O8 powder for MTR fuel elements

International Nuclear Information System (INIS)

Leal Neto, R.M.; Riella, H.G.

1990-01-01

Three preparation methods of U 3 O 8 powder have been studied with the aim of finding a simple and economic processing route: grinding of sintered U 3 O 8 pellets (Method-1); sintering of U 3 O 8 calcined granules (Method-2); and sintering of ammonium diuranate (ADU) granules (Method-3). Granulometric yield, powder characteristics and processing steps and difficulties have been taken into account for comparison purposes. Method-2 have been found to give the best results. Method-3 gives also good results, but there were some difficulties with ADU handling. (author) [pt

The Influence of Oxidation on the Quality of U3O8 Kernels

International Nuclear Information System (INIS)

Damunir; Sukarsono; Indra Suryawan

2002-01-01

The influence of oxidation on quality of U 3 O 8 kernels have been studied. The investigated the influence was changed of time and temperature oxidation of Uranyl-4(ammonia)-2(polyvinyl alcohol) gel on surface area, pore radius, pore volume, porosity and diameter size of U 3 O 8 kernel. The spherical of uranyl-4(ammonia)-2(polyvinyl alcohol) containing 150g U/l were oxidized at 200-800 o C temperature for 2-24 hours, formed U 3 O 8 kernel. After that, the quality of U 3 O 8 kernel were measured by their physical properties i.e. the surface area and pore radius using Surface areameter with N 2 gas as absorbent. The pore volume and porosity using pycnometer with aquabidest of water as a solvent, diameter size using a optical microscope. The experiment results, showed that the time and temperature oxidation of uranyl-4(ammonia)-2(polyvinyl alcohol) grain the influence to quality of U 3 O 8 in formed the surface area of specific, pore radius, pore volume of specific, porosity, and diameter size of U 3 O 8 kernel. The best accurred at 600-800 o C oxidation temperature and oxidation time was 2-5 hours. The resulted quality of U 3 O 8 kernel i.e surface area of specific was 10.84 - 5.99 m 2 /g, pore volume of specific was 10.35x10 -2 - 3.23x10 -2 cc/g, pore radius was 21.05 - 24.62 Angstrom, diameter size was 1264 - 1456 μm and porosity was 49.49 - 21.36 % Vol with Cumulative analysis error was 8.55 % Vol. (author)

195Pt and 119Sn Knight shifts of U3Pt3Sn4

International Nuclear Information System (INIS)

Kojima, K.; Takabatake, T.; Harada, A.; Hihara, T.

1995-01-01

The 195 Pt and 119 Sn Knight shifts in U 3 Pt 3 Sn 4 have been measured in the temperature range 4.2-298K. They exhibit Curie-Weiss like behaviors above about 50K and remain constant below about 10K. This suggests that the deviation of χ(T) from the modified Curie-Weiss law is an intrinsic property of U 3 Pt 3 Sn 4 . ((orig.))

Hydrogeologic Characterization of the U-3bl Collapse Zone

International Nuclear Information System (INIS)

NSTec Geotechnical Services

2006-01-01

The U-3bl collapse crater was formed by an underground nuclear test in August 1962. This crater and the adjoining U-3ax crater were subsequently developed and used as a bulk low-level radioactive waste disposal cell (U-3ax/bl), which is part of the Area 3 Radioactive Waste Management Site at the Nevada Test Site (NTS). Various investigations have been conducted to assess the hydrogeologic characteristics and properties in the vicinity of the U-3ax/bl waste disposal cell. This report presents data from one of these investigations, conducted in 1996. Also included in this report is a review of pertinent nuclear testing records, which shows that the testing operations and hydrogeologic setting of the U-3ax/bl site were typical for the period and location of testing. Borehole U-3bl-D2 is a 45-degree-angle hole drilled from the edge of the crater under the waste cell to intercept the U-3bl collapse zone, the disturbed alluvium between the crater (surface collapse sink) and the nuclear test cavity. A casing-advance system with an air percussion hammer was used to drill the borehole, and air was used as the drilling fluid. Properties of the U-3bl crater collapse zone were determined from cores collected within the interval, 42.1 to 96.6 meters (138 to 317 feet) below the ground surface. Selected core samples were analyzed for particle density, particle size, bulk density, water retention, hydraulic conductivity, water content, water potential, chloride, carbonate, stable isotopes, and tritium. Physical and hydraulic properties were typical of alluvial valley sediments at the NTS. No visual evidence of preferential pathways for water transport was observed in the core samples. Soil parameters showed no trends with depth. Volumetric water content values ranged from 0.08 to 0.20 cubic meters per cubic meter, and tended to increase with depth. Water-retention relations were typical for soils of similar texture. Water potentials ranged from -1.9 MegaPascals at a depth of 42

Irradiation damage in U{sub 3}Si

Energy Technology Data Exchange (ETDEWEB)

MacEwan, J R; Bethune, B

1969-04-15

The ordered body-centered tetragonal structure of U{sub 3}S1 transforms allotropically or by irradiation damage to ordered and disordered face -centered cubic structures respectively. An exposure of about 6 x 10{sup 16} fissions/cm{sup 3} at 100{sup o}C produced X-ray diffraction patterns of the cubic form with a 0.6% decrease in X-ray density. However, immersion density measurements showed a volume increase of 2.3% at a similar exposure. Further irradiation removed all but two peaks from the diffraction pattern indicating a trend to an amorphous structure. Electrical resistivity measurements showed that U{sub 3}Si is an electronic conductor with a large positive temperature coefficient. Measurements made below the irradiation temperature of 100{sup o}C showed that the temperature coefficient decreased with irradiation and approached zero at high exposure, Amorphous materials have a negligible temperature coefficient, so the result confirms the trend observed by X-ray analyses. (author)

Convergence of exterior solutions to radial Cauchy solutions for $\\partial_t^2U-c^2\\Delta U=0$

Directory of Open Access Journals (Sweden)

Helge Kristian Jenssen

2016-09-01

Full Text Available Consider the Cauchy problem for the 3-D linear wave equation $\\partial_t^2U-c^2\\Delta U=0$ with radial initial data $U(0,x=\\Phi(x=\\varphi(|x|$, $U_t(0,x=\\Psi(x=\\psi(|x|$. A standard result states that $U$ belongs to $C([0,T];H^s(\\mathbb{R}^3$ whenever $(\\Phi,\\Psi\\in H^s\\times H^{s-1}(\\mathbb{R}^3$. In this article we are interested in the question of how U can be realized as a limit of solutions to initial-boundary value problems on the exterior of vanishing balls $B_\\varepsilon$ about the origin. We note that, as the solutions we compare are defined on different domains, the answer is not an immediate consequence of $H^s$ well-posedness for the wave equation.

Oxidation of uraninite: does tetragonal U3O7 occur in nature?

International Nuclear Information System (INIS)

Janeczek, J.; Ewing, R.C.; Thomas, L.E.

1993-01-01

Samples of uraninite and pitchblende annealed at 1200 C in H 2 , and untreated pitchblende were sequentially oxidized in air at 180-190 C, 230 C, and 300 C. Uraninite and untreated pitchblende oxidized to the U 4 O 9 -type oxide, and their X-ray symmetry remained isometric up to 300 C. Reduced pitchblende after oxidation to UO 2+x and U 4 O 9 -type oxides transformed into α-U 3 O 8 at 300 C. Two major mechanisms control uraninite and untreated pitchblende stability during oxidation: (1) Th and/or REE maintain charge balance and block oxygen interstitials near impurity cations; (2) the uraninite structure saturates with respect to excess oxygen and radiation-induced oxygen interstitials. Untreated pitchblende during oxidation behaved similarly to irradiated UO 2 in spent nuclear fuel; whereas, reduced pitchblende resembled nonirradiated UO 2 . An analysis of the data in the literature, as well as our own efforts to identify U 3 O 7 in samples from Cigar Lake, Canada, failed to provide conclusive evidence of the natural occurrence of tetragonal α-U 3 O 7 . Most probably, reported occurrences of U 3 O 7 are mixtures of isometric uraninites of slightly different compositions. (orig.)

Application of bias correction methods to improve U3Si2 sample preparation for quantitative analysis by WDXRF

International Nuclear Information System (INIS)

Scapin, Marcos A.; Guilhen, Sabine N.; Azevedo, Luciana C. de; Cotrim, Marycel E.B.; Pires, Maria Ap. F.

2017-01-01

The determination of silicon (Si), total uranium (U) and impurities in uranium-silicide (U 3 Si 2 ) samples by wavelength dispersion X-ray fluorescence technique (WDXRF) has been already validated and is currently implemented at IPEN's X-Ray Fluorescence Laboratory (IPEN-CNEN/SP) in São Paulo, Brazil. Sample preparation requires the use of approximately 3 g of H 3 BO 3 as sample holder and 1.8 g of U 3 Si 2 . However, because boron is a neutron absorber, this procedure precludes U 3 Si 2 sample's recovery, which, in time, considering routinely analysis, may account for significant unusable uranium waste. An estimated average of 15 samples per month are expected to be analyzed by WDXRF, resulting in approx. 320 g of U 3 Si 2 that would not return to the nuclear fuel cycle. This not only impacts in production losses, but generates another problem: radioactive waste management. The purpose of this paper is to present the mathematical models that may be applied for the correction of systematic errors when H 3 BO 3 sample holder is substituted by cellulose-acetate {[C 6 H 7 O 2 (OH) 3-m (OOCCH 3 )m], m = 0∼3}, thus enabling U 3 Si 2 sample’s recovery. The results demonstrate that the adopted mathematical model is statistically satisfactory, allowing the optimization of the procedure. (author)

The [U{sub 2}F{sub 12}]{sup 2-} anion of Sr[U{sub 2}F{sub 12}

Energy Technology Data Exchange (ETDEWEB)

Scheibe, Benjamin; Pietzonka, Clemens; Conrad, Matthias; Kraus, Florian [Fachbereich Chemie, Philipps-Universitaet Marburg (Germany); Mustonen, Otto; Karppinen, Maarit; Karttunen, Antti J. [Department of Chemistry, Aalto University (Finland); Atanasov, Mihail; Neese, Frank [Max-Planck Institute for Chemical Energy Conversion, Muelheim an der Ruhr (Germany)

2018-03-05

The D{sub 2h}-symmetric dinuclear complex anion [U{sub 2}F{sub 12}]{sup 2-} of pastel green Sr[U{sub 2}F{sub 12}] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge-linked monocapped trigonal prisms, the U{sup V} atoms are therefore seven-coordinated. This leads to a U-U distance of 3.8913(6) Aa. A weak U{sup V}-U{sup V} interaction is observed for the dinuclear [U{sub 2}F{sub 12}]{sup 2-} complex and described by the antiferromagnetic exchange J{sub exp} of circa -29.9 cm{sup -1}. The crystalline compound can be easily prepared from SrF{sub 2} and β-UF{sub 5} in anhydrous hydrogen fluoride (aHF) at room temperature. It was studied by means of single crystal X-ray diffraction, IR, Raman and UV/VIS spectroscopy, magnetic measurements, and by molecular as well as by solid-state quantum chemical calculations. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Photochemistry of U(BH4)4 and U(BD4)4

International Nuclear Information System (INIS)

Paine, R.T.; Schonberg, P.R.; Light, R.W.; Danen, W.C.; Freund, S.M.

1979-01-01

U(BH 4 ) 4 and U(BD 4 ) 4 are observed to undergo complex degradation reactions promoted by broadband UV radiation. The primary products of these reactions appear to be U(BH 4 ) 3 , B 2 H 6 , H 2 , U(BD 4 ) 3 , B 2 D 6 and D 2 . Further, U(BD 4 ) 4 undergoes a related decomposition reaction under the influence of CO 2 laser irradiation at 924.97 cm -1 . (author)

Thermal properties of KUO3(s) and K2U2O7 - by high temperature Calvet calorimeter

International Nuclear Information System (INIS)

Jayanthi, K.; Iyer, V.S.; Venugopal, V.

1998-01-01

The thermal properties of KUO 3 (s) and K 2 U 2 O 7 (s) were determined using a high temperature Calvet calorimeter by drop method. The enthalpy increments, (H T o - H 298.15 0 ), in kJ/mol for KUO 3 (s) and K 2 U 2 O 7 (s) can be represented by, H T o - H 298.15 0 KUO 3 (s) kJ/mol ± 0.7 = -39.15 + 0.129T + 0.1005x10 -4 T 2 (369-714K) and H T o -H 298.15 0 K 2 U 2 O 7 (s) kJ/mol ± 0.7 = -52.99 + 0.1361T + 0.146x10 -3 T 2 (391 - 683K). (author)

12 CFR 211.3 - Foreign branches of U.S. banking organizations.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 2 2010-01-01 2010-01-01 false Foreign branches of U.S. banking organizations. 211.3 Section 211.3 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM INTERNATIONAL BANKING OPERATIONS (REGULATION K) International Operations of U.S. Banking...

Oxidation behaviour of plutonium rich (U, Pu)C and (U, Pu)O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Sali, S.K., E-mail: sksali@barc.gov.in [Fuel Chemistry Division (India); Kulkarni, N.K.; Phatak, Rohan [Fuel Chemistry Division (India); Agarwal, Renu [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2016-10-15

Oxidation behaviour of (U{sub 0.3}Pu{sub 0.7})C{sub 1.06} was investigated in air by heating samples up to 1073 K and 1273 K. Thermogravimetry (TG) of the samples and X-ray powder diffraction (XRD) of the intermediate products were used to understand the phenomenon taking place during this process. Theoretical calculations were carried out to understand the multiple phase changes taking place during oxidation of carbide. Theoretical results were validated by XRD analysis of the products obtained at different stages of oxidation. The final oxidized products were found to be a single FCC phase with O/M = 2.15 (M = U + Pu). Oxidation kinetic studies of (U{sub 0.3}Pu{sub 0.7})O{sub 2} and (U{sub 0.47}Pu{sub 0.53})O{sub 2} were carried out in dry air, using thermogravimetry, under non-isothermal conditions. The activation energy of oxidation was found to be 49 and 70 kJ/mol, respectively. Lattice parameter dependence on Pu/M and O/M of plutonium rich mixed oxide (MOX) was established using combined results of XRD and TG analysis of (U{sub 0.3}Pu{sub 0.7})O{sub 2+x} and (U{sub 0.47}Pu{sub 0.53})O{sub 2+x}.

U3O8 powder from uranyl-loaded cation exchange resin

International Nuclear Information System (INIS)

Mosley, W.C.

1985-01-01

Large batches of U 3 O 8 , suitable for powder metallurgy fabrication of Al-U 3 O 8 cores for reactor fuel tubes, have been produced by deep-bed calcination of granular uranyl-loaded macroporous sulfonate cation exchange resin at 900 to 950 0 C in air. Deep-bed calcination is the backup process for the reference process of rotary calcination and sintering. These processes are to be used for recycling uranium, and to produce U 3 O 8 in the Fuel Production Facility to be built at the Savannah River Plant. 2 refs., 6 figs

Structural stability and fission product behaviour in U{sub 3}Si

Energy Technology Data Exchange (ETDEWEB)

Middleburgh, S.C., E-mail: simon.middleburgh@hotmail.co.uk [IME, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales (Australia); Westinghouse Electric Sweden AB, SE-72163 Västerås (Sweden); Burr, P.A. [Department of Materials, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); King, D.J.M.; Edwards, L.; Lumpkin, G.R. [IME, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales (Australia); Grimes, R.W. [Department of Materials, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom)

2015-11-15

The crystalline and amorphous structures of U{sub 3}Si have been investigated using density functional theory techniques for the first time. The effects of disorder and the impact of fission products has been separated to understand the swelling characteristics of U{sub 3}Si in both crystalline and amorphous U{sub 3}Si. Initially, the stability of the three experimentally observed polymorphs of U{sub 3}Si were explored. Subsequently, we modelled the amorphous U{sub 3}Si system and conclude that initial increase in volume observed experimentally at low temperature corresponds well with the volume change that occurs with the observed amorphisation of the material. The solubility of Xe and Zr into both the crystalline and amorphous systems was subsequently investigated.

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

A review of microstructural analysis on U3Si2-Al plate-type fuel

International Nuclear Information System (INIS)

Ti Zhongxin; Guo Yibai

1995-12-01

The microstructure of U 3 Si 2 -Al plate-type fuel, that is the microstructure of fuel particles, compatibility of the fuel particles and Al matrix, fuel particles distribution, dogbone area morphology, clad and meat thickness, bone quality of clad/frame and clad/fuel core, and the effect of these factors on products quality were comprehensively investigated and analyzed by means of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDX), image processing technique, etc.. The main results are as following: U-7.7%Si alloy contains two phases: primary U 3 Si 2 and small amount of USi (about 12%), free-uranium was not detected in fuel particles; the dogbone area is the key factor affecting fuel plate quality (1 ref., 16 figs., 4 tabs.)

Thermophysical properties of U3Si to 1150 K

International Nuclear Information System (INIS)

White, J.T.; Nelson, A.T.; Byler, D.D.; Valdez, J.A.; McClellan, K.J.

2014-01-01

U 3 Si has the highest uranium density of the U–Si compounds, making it an attractive option for specialized reactor applications. Although the compound has been used in research and test reactors for nearly six decades, little data has been published in the literature which characterizes the thermophysical properties at elevated temperatures. A systematic study was conducted on U 3 Si to characterize thermal expansion, heat capacity, thermal diffusivity, and thermal conductivity as a function of temperature to 1150 K. Thermophysical properties were also tabulated for the high temperature δ ′ -U 3 Si phase as a function of temperature, which has not been reported previously

The herpes simplex virus 1 U{sub S}3 regulates phospholipid synthesis

Energy Technology Data Exchange (ETDEWEB)

Wild, Peter, E-mail: pewild@access.uzh.ch [Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Institute of Virology, University of Zuerich (Switzerland); Oliveira, Anna Paula de [Institute of Virology, University of Zuerich (Switzerland); Sonda, Sabrina [Institute for Parasitology, University of Zuerich (Switzerland); Schraner, Elisabeth M. [Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Institute of Virology, University of Zuerich (Switzerland); Ackermann, Mathias; Tobler, Kurt [Institute of Virology, University of Zuerich (Switzerland)

2012-10-25

Herpes simplex virus type 1 capsids bud at nuclear and Golgi membranes for envelopment by phospholipid bilayers. In the absence of U{sub S}3, nuclear membranes form multiple folds harboring virions that suggests disturbance in membrane turnover. Therefore, we investigated phospholipid metabolism in cells infected with the U{sub S}3 deletion mutant R7041({Delta}U{sub S}3), and quantified membranes involved in viral envelopment. We report that (i) [{sup 3}H]-choline incorporation into nuclear membranes and cytoplasmic membranes was enhanced peaking at 12 or 20 h post inoculation with wild type HSV-1 and R7041({Delta}U{sub S}3), respectively, (ii) the surface area of nuclear membranes increased until 24 h of R7041({Delta}U{sub S}3) infection forming folds that equaled {approx}45% of the nuclear surface, (iii) the surface area of viral envelopes between nuclear membranes equaled {approx}2400 R7041({Delta}U{sub S}3) virions per cell, and (iv) during R7041({Delta}U{sub S}3) infection, the Golgi complex expanded dramatically. The data indicate that U{sub S}3 plays a significant role in regulation of membrane biosynthesis.

Short Communication on "In-situ TEM ion irradiation investigations on U3Si2 at LWR temperatures"

Science.gov (United States)

Miao, Yinbin; Harp, Jason; Mo, Kun; Bhattacharya, Sumit; Baldo, Peter; Yacout, Abdellatif M.

2017-02-01

The radiation-induced amorphization of U3Si2 was investigated by in-situ transmission electron microscopy using 1 MeV Kr ion irradiation. Both arc-melted and sintered U3Si2 specimens were irradiated at room temperature to confirm the similarity in their responses to radiation. The sintered specimens were then irradiated at 350 °C and 550 °C up to 7.2 × 1015 ions/cm2 to examine their amorphization behavior under light water reactor (LWR) conditions. U3Si2 remains crystalline under irradiation at LWR temperatures. Oxidation of the material was observed at high irradiation doses.

Tensile mechanical properties of U3Si2-Al fuel plate

International Nuclear Information System (INIS)

Xu Yong; Hu Huawei; Zhuang Hongquan; Wang Xishu

2003-01-01

The fuel plate made of fuel meat, with the U 3 Si 2 -Al dispersion fuel center, and 6061 Al alloy cladding, is a new kind of fuel used in research reactors. The mechanical property data of the fuel meat is the basic data in the design of fuel group, but the mechanical property of this fuel meat has not been studied all over the world till now. In this paper, the mechanical properties of U 3 Si 2 -Al fuel meats of different sizes used in research reactors are investigated and analyzed, and at the same time the carrying capacity of tensile in different directions are also compared. In order to get more knowledge about the mechanical properties of the fuel meat, the tensile experiment has been carried out repeatedly. Considering the lower ratio of elongation and the brittleness, the microscope has been used to examine the zone of fracture after tensile test. (authors)

High-pressure U3O8 with the fluorite-type structure

International Nuclear Information System (INIS)

Zhang, F.X.; Lang, M.; Wang, J.W.; Li, W.X.; Sun, K.; Prakapenka, V.; Ewing, R.C.

2014-01-01

A new high-pressure phase of U 3 O 8 , which has a fluorite-type structure, forms at pressures greater than ∼8.1 GPa that was confirmed by in situ x-ray diffraction (XRD) measurements. The fluorite-type U 3 O 8 is stable at pressures at least up to ∼40 GPa and temperatures to 1700 K, and quenchable to ambient conditions. Based on the XRD analysis, there is a huge volume collapse (>20%) for U 3 O 8 during the phase transition and the quenched high-pressure phase is 28% denser than the initial orthorhombic phase at ambient conditions. The high-pressure phase has a very low compressibility comparing with the starting orthorhombic phase. - Graphical abstract: α-U 3 O 8 is in a layered structure with orthorhombic symmetry, at high pressures, it transformed to a fluorite-type cubic structure. There are a lot of defects in the cubic structure, and it is a new kind of hyperstoichiometric uranium oxide, which is stable at ambient conditions. - Highlights: • A new fluorite-type high-pressure phase was found in hyperstoichometric UO 2 +x (x∼0.8). • The new high-pressure structure is quenchable to ambient conditions. • Pressure driven phase transition in orthorhombic U 3 O 8 was first found

Microstructure studies of interdiffusion behavior of U{sub 3}Si{sub 2}/Zircaloy-4 at 800 and 1000 °C

Energy Technology Data Exchange (ETDEWEB)

He, Lingfeng, E-mail: Lingfeng.He@inl.gov; Harp, Jason M., E-mail: Jason.Harp@inl.gov; Hoggan, Rita E.; Wagner, Adrian R.

2017-04-01

Fuel swelling during normal reactor operations could lead to unfavorable chemical interactions when in contact with its cladding. As new fuel types are developed, it is crucial to understand the interaction behavior between fuel and its cladding. Diffusion experiments between U{sub 3}Si{sub 2} and Zricaloy-4 (Zry-4) were conducted at 800 and 1000 °C up to 100 h. The microstructure of pristine U{sub 3}Si{sub 2} and U{sub 3}Si{sub 2}/Zry-4 interdiffusion products were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) equipped with an energy dispersive X-ray spectroscopy (EDS) system. The primary interdiffusion product observed at 800 °C is ZrSi{sub 2}, with secondary phases of U-Zr in the Zry-4, and Fe-Cr-W-Zr-Si phases at Zry-4/ZrSi{sub 2} interface and Fe-Cr-U-Si phases at ZrSi{sub 2}/U-Si interface. The primary interdiffusion products at 1000 °C were Zr{sub 2}Si, U-Zr-Fe-Ni, U, U-Zr, and a low melting point phase U{sub 6}Fe.

Post-irradiation examination of prototype Al-64 wt% U{sub 3}Si{sub 2} fuel rods from NRU

Energy Technology Data Exchange (ETDEWEB)

Sears, D.F.; Primeau, M.F.; Buchanan, C.; Rose, D. [Chalk River Labs., Ontario (Canada)

1997-08-01

Three prototype fuel rods containing Al-64 wt% U{sub 3}Si{sub 2} (3.15 gU/cm{sup 3}) have been irradiated to their design burnup in the NRU reactor without incident. The fuel was fabricated using production-scale equipment and processes previously developed for Al-U{sub 3}Si fuel fabrication at Chalk River Laboratories, and special equipment developed for U{sub 3}Si{sub 2} powder production and handling. The rods were irradiated in NRU up to 87 at% U-235 burnup under typical driver fuel conditions; i.e., nominal coolant inlet temperature 37{degrees}C, inlet pressure 654 kPa, mass flow 12.4 L/s, and element linear power ratings up to 73 kW/m. Post-irradiation examinations showed that the fuel elements survived the irradiation without defects. Fuel core diametral increases and volumetric swelling were significantly lower than that of Al-61 wt% U{sub 3}Si fuel irradiated under similar conditions. This irradiation demonstrated that the fabrication techniques are adequate for full-scale fuel manufacture, and qualified the fuel for use in AECL`s research reactors.

Optical properties of LiYF4:U3+. Infrared laser use

International Nuclear Information System (INIS)

Louis, M.

1995-01-01

In this study are proposed a complete interpretation of the optical spectra of trivalent uranium in LiYF 4 (LYF). Single crystals of uranium doped LYF were grown by Czochralski method with different concentration (0.05%-0.20%). The obtained crystals have pale green color, characteristic of tetravalent uranium. The absorption spectra show that effectively only U 4+ is present in this crystal. In order to reduce the oxidation state of the U 4+ , the pale green crystal containing 0.07% of U 4+ was exposed to gamma irradiation. The sample becomes orange brown and the absorption spectrum is characteristic of U 3+ . The irradiation technology is an efficient method to convert 100% of U 4+ in U 3+ . From the analysis of the polarized optical absorption and emission spectra the spectroscopic parameters have been determined. The Judd-Ofelt theory was applied in order to simulate the intensity of the 5 f 3 →5 f 3 transitions between Stark levels of U 3+ in LYF. Because of the large crystal field splitting of the J multiplet in the actinides a set of phenomenological intensity parameters is introduced to describe the transition probabilities between crystal field sublevels. A continuous laser emission of an actinide ion at ambient temperature has been revealed. In the last part of this thesis the fundamental aspect of the energy transfer process that takes place in laser crystal LYF codoped with an 4 f element Nd 3+ and an 5 f one U 3+ has been investigated. (author). 111 refs., 69 figs., 19 tabs

Residual Z{sub 2} symmetries and leptonic mixing patterns from finite discrete subgroups of U(3)

Energy Technology Data Exchange (ETDEWEB)

Joshipura, Anjan S. [Physical Research Laboratory,Navarangpura, Ahmedabad 380 009 (India); Patel, Ketan M. [Indian Institute of Science Education and Research, Mohali,Knowledge City, Sector 81, S A S Nagar, Manauli 140 306 (India)

2017-01-30

We study embedding of non-commuting Z{sub 2} and Z{sub m}, m≥3 symmetries in discrete subgroups (DSG) of U(3) and analytically work out the mixing patterns implied by the assumption that Z{sub 2} and Z{sub m} describe the residual symmetries of the neutrino and the charged lepton mass matrices respectively. Both Z{sub 2} and Z{sub m} are assumed to be subgroups of a larger discrete symmetry group G{sub f} possessing three dimensional faithful irreducible representation. The residual symmetries predict the magnitude of a column of the leptonic mixing matrix U{sub PMNS} which are studied here assuming G{sub f} as the DSG of SU(3) designated as type C and D and large number of DSG of U(3) which are not in SU(3). These include the known group series Σ(3n{sup 3}), T{sub n}(m), Δ(3n{sup 2},m), Δ(6n{sup 2},m) and Δ{sup ′}(6n{sup 2},j,k). It is shown that the predictions for a column of |U{sub PMNS}| in these group series and the C and D types of groups are all contained in the predictions of the Δ(6N{sup 2}) groups for some integer N. The Δ(6N{sup 2}) groups therefore represent a sufficient set of G{sub f} to obtain predictions of the residual symmetries Z{sub 2} and Z{sub m}.

Supersymmetric U boson and the old U(1) problem

International Nuclear Information System (INIS)

Kim, B.R.

1983-01-01

In the supersymmetric SU(3)xSU(2)xU(1)xUsup(')(1) model the new gauge group Usup(')(1) enforces the introduction of mirror fermions. In this note we address the inverse question. If one starts with SU(3)xSU(2)xU(1) including mirror fermions, what physical arguments other than the supersymmetric require the introduction of a new gauge group Usup(')(1). It turns out that the old U(1) problem is closely related with this question. Further we give an estimate for the upper bound for the parameter of the supersymmetric U boson r and x. (orig.)

Estimation of build up of dose rate on U3O8 product drum

International Nuclear Information System (INIS)

Pandey, J.P.N.; Shinde, A.M.; Deshpande, M.D.

2008-01-01

In fuel reprocessing plant, plutonium oxide and uranium oxide (U 3 O 8 ) are products. Approximately 180 kg U 3 O 8 is filled in SS drum and sealed firmly before storage. In PHWR natural uranium (UO 2 ) is used as fuel. In natural uranium, thorium-232 is present as an impurity at few tens of ppm level. During irradiation in power reactors, due to nuclear reaction formation of 232 U from 232 Th takes place. Natural decay of 232 U leads to the formation of 208 Tl. As time passes, there is buildup of 208 Tl and hence increase in dose rate on the drum containing U 3 O 8 . It is essential to estimate the buildup of dose rate considering the external radiological hazards involved during U 3 O 8 drum handling, transportation and fuel fabrication. This paper describes the calculation of dose rate on drum in future years using MCNP code. For dose rate calculation decay of fission product activity which remains as contamination in product and build up of '2 08 Tl from 232 U is considered. Some measured values of dose rate on U 3 O 8 drum are given for the comparisons with estimated dose rate based on MCNP code. (author)

Simulation of accident-tolerant U3Si2 fuel using FRAPCON code

International Nuclear Information System (INIS)

Gomes, Daniel S.; Silva, Antonio T.; Abe, Alfredo Y.; Muniz, Rafael O.R.; Giovedi, Claudia

2017-01-01

The research on accident-tolerant fuels (ATFs) increased after the Fukushima event. This benefited risk management in nuclear operations. In this investigation, the physical properties of the materials being developed for the ATF program were compared with those of the standard UO 2 - Zr fuel system. The research efforts in innovative fuel design include rigorous characterization of thermal, mechanical, and chemical assessment, with the objectives of making the burnup cycle longer, increasing power density, and improving safety performance. Fuels must reach a high uranium density - above that supported by UO 2 - and possess coating that exhibits better oxidation resistance than Zircaloy. The uranium density and thermal conductivity of ATFs, such as U 3 Si 2 , UN, and UC, is higher than that of UO 2 ; their combination with advanced cladding provides possible fuel - cladding options. An ideal combination of fuel and cladding must increase fuel performance in loss-of-coolant scenarios. The disadvantages of U 3 Si 2 , UN, and UC are their swelling rates, which are higher than that of UO 2 . The thermal conductivities of ATFs are approximately four times higher than that of UO2. To prevent the generation of hydrogen due to oxidation of zirconium-based alloys in contact with steam, cladding options, such as ferritic alloys, were studied. It was verified that FeCrAl alloys and SiC provide better response under severe conditions because of their thermophysical properties. The findings of this study indicate that U 3 Si 2 and the FeCrAl fuel cladding concept should replace UO 2 - Zr as the fuel system of choice. (author)

Rate theory scenarios study on fission gas behavior of U 3 Si 2 under LOCA conditions in LWRs

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin; Gamble, Kyle A.; Andersson, David; Mei, Zhi-Gang; Yacout, Abdellatif M.

2018-01-01

Fission gas behavior of U3Si2 under various loss-of-coolant accident (LOCA) conditions in light water reactors (LWRs) was simulated using rate theory. A rate theory model for U3Si2 that covers both steady-state operation and power transients was developed for the GRASS-SST code based on existing research reactor/ion irradiation experimental data and theoretical predictions of density functional theory (DFT) calculations. The steady-state and LOCA condition parameters were either directly provided or inspired by BISON simulations. Due to the absence of in-pile experiment data for U3Si2's fuel performance under LWR conditions at this stage of accident tolerant fuel (ATF) development, a variety of LOCA scenarios were taken into consideration to comprehensively and conservatively evaluate the fission gas behavior of U3Si2 during a LOCA.

Status of U3Si2-Al fuel development in China

International Nuclear Information System (INIS)

Sun Rongxian; Huang Dechen; Yin Changgeng; Zhang Qindi; He Fengqi; Li Shuhua; Xiang Xingbi; Zhang Zhiyi; Wang Zhaoyue

1995-01-01

On the basis of the research and development work, a production line of U 3 Si 2 -Al dispersion fuel elements has been established and tens of the fuel elements have been produced. A lot of technical improvements and reliable inspection system ensure that all technical performance of the fuel elements meet International standards. (author)

Tank 241-U-103, grab samples 3U-99-1, 3u-99-2 and 3U-99-3 analytical results for the final report

International Nuclear Information System (INIS)

STEEN, F.H.

1999-01-01

This document is the final report for tank 241-U-103 grab samples. Three grab samples were collected from riser 13 on March 12, 1999 and received by the 222-S laboratory on March 15, 1999. Analyses were performed in accordance with the Compatibility Grab Sampling and Analysis Plan for Fiscal Year 1999 (TSAP) (Sasaki, 1999) and the Data Quality Objectives for Tank Farms Waste Compatibility Program (DQO). The analytical results are presented in the data summary report. None of the subsamples submitted for differential scanning calorimetry (DSC), total organic carbon (TOC) and plutonium 239 (Pu239) analyses exceeded the notification limits as stated in TSAP

U3O8 obtained from metallic uranium

International Nuclear Information System (INIS)

Lopez, Marisol; Gonzalez, Alfredo; Pasqualini, Enrique E.

2003-01-01

Enriched uranium oxide, U 3 O 8 , used as nuclear powder in MTR's, can be obtained by direct oxidation of metallic uranium at 800 C degrees. Maximum density, 8.2 gr/cm 3 , is achieved after grinding and a high temperature treatment at 1400 C degrees. All the process is highly controllable and performed in dry environments. (author)

U enrichment and Th/U fractionation in Archean boninites: Implications for paleo-ocean oxygenation and U cycling at juvenile subduction zones

Science.gov (United States)

Manikyamba, C.; Said, Nuru; Santosh, M.; Saha, Abhishek; Ganguly, Sohini; Subramanyam, K. S. V.

2018-05-01

Phanerozoic boninites record enrichments of U over Th, giving Th/U: 0.5-1.6, relative to intraoceanic island arc tholeiites (IAT) where Th/U averages 2.6. Uranium enrichment is attributed to incorporation of shallow, oxidized fluids, U-rich but Th-poor, from the slab into the melt column of boninites which form in near-trench to forearc settings of suprasubduction zone ophiolites. Well preserved Archean komatiite-tholeiite, plume-derived, oceanic volcanic sequences have primary magmatic Th/U ratios of 4.4-3.6, and Archean convergent margin IAT volcanic sequences, having REE and HFSE compositions similar to Phanerozoic IAT equivalents, preserve primary Th/U of 4-3.6. The best preserved Archean boninites of the 3.0 Ga Olondo and 2.7 Ga Gadwal greenstone belts, hosted in convergent margin ophiolite sequences, also show relative enrichments of U over Th, with low average Th/U ∼3 relative to coeval IAT, and Phanerozoic counterparts which are devoid of crustal contamination and therefore erupted in an intraoceanic setting, with minimal contemporaneous submarine hydrothermal alteration. Later enrichment of U is unlikely as Th-U-Nb-LREE patterns are coherent in these boninites whereas secondary effects induce dispersion of Th/U ratios. The variation in Th/U ratios from Archean to Phanerozoic boninites of greenstone belts to ophiolitic sequences reflect on genesis of boninitic lavas at different tectono-thermal regimes. Consequently, if the explanation for U enrichment in Phanerozoic boninites also applies to Archean examples, the implication is that U was soluble in oxygenated Archean marine water up to 600 Ma before the proposed great oxygenation event (GOE) at ∼2.4 Ga. This interpretation is consistent with large Ce anomalies in some hydrothermally altered Archean volcanic sequences aged 3.0-2.7 Ga.

Vector coherent state representations of SO5 contains SU2 + SU2 contains U1 + U1 and SO5 contains U1 + U1

International Nuclear Information System (INIS)

Pan Feng

1991-01-01

VCS representations of SO 5 contains SU 2 + SU 2 contains U 1 + U 1 and SO 5 contains U 1 + U 1 are discussed. Reduced matrix elements for SO 5 contains SU 2 + SU 2 are derived. The multiplicity of a weight for SO 5 is determined by using the K-matrix technique

DFT+U study of polaronic conduction in Li2O2 and Li2CO3

DEFF Research Database (Denmark)

García Lastra, Juan Maria; Myrdal, J.S.G.; Christensen, Rune

2013-01-01

The main discharge products formed at the cathode of nonaqueous Li-air batteries are known to be Li2O2 and residual Li2CO3. Recent experiments indicate that the charge transport through these materials is the main limiting factor for the battery performance. It has been also shown...... that the performance of the battery decreases drastically when the amount of Li2CO3 at the cathode increases with respect to Li2O2. In this work, we study the formation and transport of hole and electron polarons in Li2O2 and Li2CO3 using density functional theory (DFT) within the PBE+U approximation. For both...... materials, we find that the formation of polarons (both hole and electron) is stabilized with respect to the delocalized states for all physically relevant values of U. We find a much higher mobility for hole polarons than for the electron polarons, and we show that the poor charge transport in Li2CO3...

Thermal expansion anomaly and thermal conductivity of U3O8

International Nuclear Information System (INIS)

Schulz, B.

1975-01-01

The anomaly in the thermal expansion of U 3 O 8 and results of the thermal conductivity of this compound are described. U 3 O 8 powder heat treated at 1,223 K was consolidated by pressing and sintering in air at 1,223 and 1,373 K to a density of 66% and 80.8% TD. The O/U ratio was 2.67 and 2.63 respectively, the crystal structure being orthorhombic in both cases. For UOsub(2.63) the thermal linear expansion was measured in the temperature range 293 K-1,063 K in pressing direction and normal to it, while for UOsub(2.67) measurements were done parallel to the pressing direction. The curves of the linear thermal expansion from 373 K up to 623 K show negative values and above positive for the three curves. The results are related to known data of phase-transition-temperatures of the orthorhombic U 3 O 8 . Measurements of the thermal conductivity were done on UOsub(2.67). Because of the high porosity of the samples, known relationships for the porosity correction of the thermal conductivity were proved on alumina with 34 % porosity. The values of the thermal conductivity of UOsub(2.67) (corrected to zero porosity) show a very slight temperature dependence, they are about three times lower than those of the stoichiometric uranium dioxide in the same temperature range

Uncertainty measurement evaluation of WDXRF and EDXRF techniques for the Si and U{sub total} determination in U{sub 3}Si{sub 2} used as nuclear fuel material

Energy Technology Data Exchange (ETDEWEB)

Scapin, Marcos A.; Salvador, Vera L.R.; Cotrim, Marycel E.B.; Pires, Maria Ap. F.; Sato, Ivone M., E-mail: mascapin@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP) Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente

2009-07-01

Uranium silicide (U{sub 3}Si{sub 2}), 20% {sup 235}U enriched powder, is an intermetallic compound used as nuclear fuel material; that is the state-of-the-art among nuclear fuel materials used in modern research reactors. It is produced by IPEN and used as nuclear fuel of the IEA-R1 reactor (IPEN/CNEN, Sao Paulo, Brazil); U{sub 3}Si{sub 2} has 92.3%wtU and 7.7%wtSi. The qualification of this material requires chemical and physical tests such as Si and U{sub total} content, isotope ratio, impurities, density, specific surface area and particle size determination. The Si and U{sub total} determination were made by gravimetric and volumetric procedures at the Environment Chemistry Center (CQMA-IPEN/CNEN). Usually, these classical methods require a long time for analyses and are expensive. The objective of this study was to establish a fast and efficient analytical method to meet ISO/IEC 17025:2005 requirements in the Si and U{sub total} determination. The X-ray fluorescence techniques (XRF) were chosen to allow a direct and non-destructive testing, what is a principal advantage faced to other instrumental techniques, since previous chemical treatments are not necessary. In this study, the performance of the wavelength dispersive (WDXRF) and energy dispersive (EDXRF) X- ray fluorescence techniques was evaluated. Furthermore, two different sample preparation procedures, plain powdered and pressed powdered were evaluated. Statistical tools were used to evaluate the results and a comparison between these results and the conventional methods was done. (author)

Walls of massive K\\"ahler sigma models on SO(2N)/U(N) and Sp(N)/U(N)

OpenAIRE

Arai, Masato; Shin, Sunyoung

2011-01-01

We study the Bogomol'nyi-Prasad-Sommerfield wall solutions in massive K\\"ahler nonlinear sigma models on SO(2N)/U(N) and Sp(N)/U(N) in three-dimensional spacetime. We show that SO(2N)/U(N) and Sp(N)/U(N) models have 2^{N-1} and 2^N discrete vacua, respectively. We explicitly construct the exact BPS multiwall solutions for N\\le 3.

Application of bias correction methods to improve U{sub 3}Si{sub 2} sample preparation for quantitative analysis by WDXRF

Energy Technology Data Exchange (ETDEWEB)

Scapin, Marcos A.; Guilhen, Sabine N.; Azevedo, Luciana C. de; Cotrim, Marycel E.B.; Pires, Maria Ap. F., E-mail: mascapin@ipen.br, E-mail: snguilhen@ipen.br, E-mail: lvsantana@ipen.br, E-mail: mecotrim@ipen.br, E-mail: mapires@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2017-07-01

The determination of silicon (Si), total uranium (U) and impurities in uranium-silicide (U{sub 3}Si{sub 2}) samples by wavelength dispersion X-ray fluorescence technique (WDXRF) has been already validated and is currently implemented at IPEN's X-Ray Fluorescence Laboratory (IPEN-CNEN/SP) in São Paulo, Brazil. Sample preparation requires the use of approximately 3 g of H{sub 3}BO{sub 3} as sample holder and 1.8 g of U{sub 3}Si{sub 2}. However, because boron is a neutron absorber, this procedure precludes U{sub 3}Si{sub 2} sample's recovery, which, in time, considering routinely analysis, may account for significant unusable uranium waste. An estimated average of 15 samples per month are expected to be analyzed by WDXRF, resulting in approx. 320 g of U{sub 3}Si{sub 2} that would not return to the nuclear fuel cycle. This not only impacts in production losses, but generates another problem: radioactive waste management. The purpose of this paper is to present the mathematical models that may be applied for the correction of systematic errors when H{sub 3}BO{sub 3} sample holder is substituted by cellulose-acetate {[C_6H_7O_2(OH)_3_-_m(OOCCH_3)m], m = 0∼3}, thus enabling U{sub 3}Si{sub 2} sample’s recovery. The results demonstrate that the adopted mathematical model is statistically satisfactory, allowing the optimization of the procedure. (author)

Analysis of hydrogen, carbon, sulfur and volatile compounds in (U3Si2 - Al) nuclear fuel

International Nuclear Information System (INIS)

Moura, Sergio C.; Redigolo, Marcelo M.; Amaral, Priscila O.; Leao, Claudio; Oliveira, Glaucia A.C. de; Bustillos, Oscar V.

2015-01-01

Uranium silicide U 3 Si 2 is used as nuclear fuel in the research nuclear reactor IEA-R1 at IPEN/CNEN, Sao Paulo, Brazil. The U 3 Si 2 is dispersed in aluminum reaching high densities of uranium in the nucleus of the fuel, up to 4.8 gU cm -3 . This nuclear fuel must comply with a quality control, which includes analysis of hydrogen, carbon and sulfur for the U 3 Si 2 and volatile compound for the aluminum. Hydrogen, carbon and sulfur are analyzed by the method of Radio Frequency gas extraction combustion coupled with Infrared detector. Volatile compounds are analyzed by the method of heated gas extraction coupled with gravimetric measurement. These methods are recommended by the American Society for Testing Materials (ASTM) for nuclear materials. The average carbon and sulfur measurements are 30 μg g -1 and 3 μg g -1 , respectively, and 40 μg g -1 for volatile compounds. The hydrogen analyzer is a TCHEN 600 LECO, carbon and sulfur analyzer is a CS 244 LECO and the volatile compounds analyzer is a home-made apparatus that use a resistant furnace, a gas pipe measurement and a glove-box with controlled atmosphere where an analytical balance has been installed, this analyzer was made at IPEN laboratory. (author)

Biochemical function of typical and variant Arabidopsis thaliana U-box E3 ubiquitin-protein ligases

DEFF Research Database (Denmark)

Wiborg, Jakob; O'Shea, Charlotte; Skriver, Karen

2008-01-01

of the distant U-box protein, AtPUB49, representing a large family of eukaryotic proteins containing a U-box linked to a cyclophilin-like peptidyl-prolyl cis-trans isomerase domain, was characterized biochemically. AtPUB49 functioned both as a prolyl isomerase and a chaperone by catalysing cis......The variance of the U-box domain in 64 Arabidopsis thaliana (thale cress) E3s (ubiquitin-protein ligases) was used to examine the interactions between E3s and E2s (ubiquitin-conjugating enzymes). E2s and E3s are components of the ubiquitin protein degradation pathway. Seven U-box proteins were...... analysed for their ability to ubiquitinate proteins in vitro in co-operation with different E2s. All U-box domains exhibited ubiquitination activity and interacted productively with UBC4/5-type E2s. Three and four of the U-box domains mediated ubiquitin addition in the presence of UBC13 and UBC7 E2s...

Global S U (3 )C×S U (2 )L×U (1 )Y linear sigma model: Axial-vector Ward-Takahashi identities and decoupling of certain heavy BSM particles due to the Goldstone theorem

Science.gov (United States)

Lynn, Bryan W.; Starkman, Glenn D.

2017-09-01

In the S U (2 )L×S U (2 )R linear sigma model with partially conserved axial-vector currents, a tower of Ward-Takahashi identities (WTI) have long been known to give relations among 1-scalar-particle-irreducible (1 -ϕ -I ) Green's functions, and among I-scalar-particle-reducible (1 -ϕ -R ) transition-matrix (T-matrix) elements for external scalars [i.e. the Brout-Englert-Higgs (BEH) scalar H , and three pseudoscalars π →]. In this paper, we extend these WTI and the resulting relations to the S U (3 )C×S U (2 )L×U (1 )Y linear sigma model including the heaviest generation of Standard Model (SM) fermions—the ungauged (i.e. global) Standard Model SMtb τ ντ G —supplemented with the minimum necessary neutrino content—right-handed neutrinos and Yukawa-coupling-induced Dirac neutrino mass—to obtain the charge-parity (C P )-conserving νDSMtb τ ντ G , and extract powerful constraints on the effective Lagrangian: e.g. showing that they make separate tadpole renormalization unnecessary, and guarantee infrared finiteness. The crucial observation is that ultraviolet quadratic divergences (UVQD), and all other relevant operators, contribute only to mπ2, a pseudo-Nambu-Goldstone boson (NGB) mass-squared, which appears in intermediate steps of calculations. A WTI between T-matrix elements (or, in this global theory equivalently the Goldstone theorem) then enforces mπ2=0 exactly for the true NGB in the spontaneous symmetry breaking (SSB) mode of the theory. The Goldstone theorem thus causes all relevant operator contributions, originating to all-loop-orders from virtual scalars H ,π → , quarks qLc;tRc;bRc and leptons lL;ντR;τR with (c =r , w , b ), to vanish identically. We show that our regularization-scheme-independent, WTI-driven results are unchanged by the addition of certain S U (3 )C×S U (2 )L×U (1 )Y heavy (MHeavy2≫|q2|,mWeak2 ) C P -conserving matter, such as originate in certain beyond the SM (BSM) models. The global axial-vector WTI

Making of U3O8 Microsphere as a Preliminary Material for Manufacturing UO2 Kernel of HTR

International Nuclear Information System (INIS)

Hidayati; Triyono; Endang Nawangsih

2007-01-01

The making of U 3 O 8 microsphere as a preliminary material for manufacturing UO 2 kernel of HTR on various feed solution with internal gelation method use of paraffin gelation medium has been done. The aim of this research is to make U 3 O 8 microsphere as preliminary material for making UO 2 kernel which has good characteristic and for knowing to some extent the feed solution influence on U 3 O 8 microsphere. Uranyl nitrate solution was used as a feed solution with acidity 1 M and some various of ADUN solution. ADUN solution was made by adding various of ammonia solution on the solution of uranyl nitrate. Each of the feed solution was added urea + HMTA solution and then it was dropped to a column containing hot paraffin solution at the temperature 95°Celsius in order to get UO 3 gel. UO 3 gel was dipped and washed with NH 4 OH, dried and calcined at the temperature of 800°Celsius . The obtained product was analyzed its surface area, radius of pore, total volume of pore and distribution of pore size of Surface Area Analyzer NOVA-1000. The density was analyzed with pycnometer and the form of microsphere was analyzed with SEM. The obtained product shows that U 3 O 8 microsphere with less ammonium nitrate gave U 3 O 8 much better and vice versa. The best U 3 O 8 obtained from the with ratio mole nitrate/uranium = 1.9, namely uranyl nitrate solution with the feed acidity of 1 N which was added by the lest amount of NH 4 OH. U 3 O 8 microsphere has density 7.06 g/cc (85.62% theoretical density), specific surface area = 6.77 m 2 /g, mean pore radius 20.52 Å, and also total pore volume 6.91x10 -3 cc/g. (author)

Comparison of thermal compatibility between atomized and comminuted U3Si dispersion fuels

International Nuclear Information System (INIS)

Ryu, Woo-Seog; Park, Jong-Man; Kim, Chang-Kyu; Kuk, II-Hyun

1997-01-01

Thermal compatibility of atomized U 3 Si dispersion fuels were evaluated up to 2600 hours in the temperature range from 250 to 500 degrees C, and compared with that of comminuted U 3 Si. Atomized U 3 Si showed better performance in terms of volume expansion of fuel meats. The reaction zone of U 3 Si and Al occurred along the grain boundaries and deformation bands in U 3 Si particles. Pores around fuel particles appeared at high temperature or after long-term annealing tests to remain diffusion paths over the trench of the pores. The constraint effects of cladding on fuel rod suppressed the fuel meat, and reduced the volume expansion

2. Interferometry and polarimetry. 2.3. Polarimetry on JT-60U

International Nuclear Information System (INIS)

Kawano, Yasunori

2000-01-01

In order to establish an electron density measurement method with high reliability and stability for magnetic-confinement fusion devices, studies on infrared polarimetry have been carried out in JT-60U. Electron density measurement based on tangential Faraday rotation has been verified using a CO 2 laser polarimeter developed for JT-60U. In this article, basic ideas of studies, results from polarimetry experiments, and suggestions for future devices are presented. (author)

CERCA's 25 years experience in U3Si2 fuel manufacturing

International Nuclear Information System (INIS)

Durand, JP.; Duban, B.; Lavastre, Y.; Perthuis, S. de

2003-01-01

This paper documents the experience gained at CERCA in manufacturing, testing, and inspecting U 3 Si 2 fuel elements for various Material Test Reactors (MTR) since the beginning of the RERTR Program in 1978, up to now. It emphasises how the company controls the product to insure compliance with the fuel-related safety parameters. Finally, those statements are considered in the UMo fuel production perspective. (author)

Application of multivariate calibration for simultaneous determination of major and minor constituents in U3Si2 by X-ray fluorescence

International Nuclear Information System (INIS)

Scapin, Marcos A.; Silva, Clayton P.; Cotrim, Marycel E.B.; Pires, Maria Aparecida F.

2013-01-01

The aim of this work is to establish and validate a methodology for a nondestructive quantitative chemical analysis method for simultaneous determination of the major constituents (U total and Si) and impurities (B, Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd,etc.) present in U 3 Si 2 . The method must also meet the needs of nuclear reactors for the nuclear fuel qualification type,MTR, with low cost and analysis time, while also minimizing waste generation. For this purpose, an X-ray fluorescence technique will be applied. The technique is nondestructive,aside from sample preparation procedures that do not require previous chemical treatments (dissolving, digesting), and allows for fast chemical analysis. The fundamental parameters (FP) method was applied to corrections for spectral and matrix effects. The calibration model was obtained via principal component analysis using orthogonal decomposition by the singular value decomposition method (SVD) in U 3 O 8 and U 3 Si 2 samples. The results were compared by means of statistical tests in accordance with ISO 17025 on CRMs of U 3 O 8 from New Brunswick Laboratory (NBL) and 16 U 3 Si 2 samples provided by CCN of IPEN/CNEN-SP. Multivariate calibration is a promising method for determination of major and minor constituents inU 3 Si 2 and U 3 O 8 nuclear fuel, because the precision and accuracy are statistically equivalent to volumetric analysis (U total determination), gravimetric analysis (Si determination), and ICP-OES methods (impurities determination). (author)

Corrosion of MTR type fuel plates containing U3O8-Al cermet cores

International Nuclear Information System (INIS)

Durazzo, M.

1985-01-01

The fuel plate samples containing U 3 O 8 -Al cermet cores with concentrations from 10 to 90% of U 3 O 8 weight were fabricated. Samples with 58% of U 3 O 8 eight were fabricated using compacts with densities from 75 to 95% of theoretical density. The influences of U 3 O 8 concentration and porosity of compacted core on porosity and uniformity of core thickness are discussed. The U 3 O 8 -Al cores were submitted to corrosion tests and exposed to deionized water at temperatures of 30, 50, 70 and 90 0 C by cladding deffect produced artificially. The results shown that core corrosion is accompanied by hydrogen release. The total volum of released hydrogen and the time interval to observe the initiation of hydrogen releasing (incubation time) are depending on core pososity and absolute temperature. A mechanism for U 3 O 8 -Al core corrosion process is proposed and discussed. The cladding of fuel plate samples was submitted to corrosion tests under similar conditons of the IAE-R1 reactor operating at 2, 5 and 10 MW. (Author) [pt

States characterized by the irreducible single row representations of the U(3) is contained in SO(3) and U(4) is contained in Dsup(3/2)[SO(3)] chains of groups

International Nuclear Information System (INIS)

Dumitrescu, T.S.

1977-01-01

A new method is applied in order to obtain the irreducible single row representations of the groups under study. For the case U(3) contained in SO(3) also an explicit realization is constructed. The method has the advantage of being simpler than the previously used ones. (author)

U(3)-flavor nonet scalar as an origin of the flavor mass spectra

International Nuclear Information System (INIS)

Koide, Yoshio

2008-01-01

According to an idea that the quark and lepton mass spectra originate in a VEV structure of a U(3)-flavor nonet scalar Φ, the mass spectra of the down-quarks and charged leptons are investigated. The U(3) flavor symmetry is spontaneously and completely broken by non-zero and non-degenerated VEVs of Φ, without passing any subgroup of U(3). The ratios (m e +m μ +m τ )/(√(m e )+√(m μ )+√(m τ )) 2 and √(m e m μ m τ )/(√(m e )+√(m μ )+√(m τ )) 3 are investigated based on a toy model

Biochemical function of typical and variant Arabidopsis thaliana U-box E3 ubiquitin-protein ligases.

Science.gov (United States)

Wiborg, Jakob; O'Shea, Charlotte; Skriver, Karen

2008-08-01

The variance of the U-box domain in 64 Arabidopsis thaliana (thale cress) E3s (ubiquitin-protein ligases) was used to examine the interactions between E3s and E2s (ubiquitin-conjugating enzymes). E2s and E3s are components of the ubiquitin protein degradation pathway. Seven U-box proteins were analysed for their ability to ubiquitinate proteins in vitro in co-operation with different E2s. All U-box domains exhibited ubiquitination activity and interacted productively with UBC4/5-type E2s. Three and four of the U-box domains mediated ubiquitin addition in the presence of UBC13 and UBC7 E2s respectively, but no productive interaction was observed with the UBC15 E2 tested. The activity of AtPUB54 [Arabidopsis thaliana (thale cress) plant U-box 54 protein] was dependent on Trp(266) in the E2-binding cleft, and the E2 selectivity was changed by substitution of this position. The function of the distant U-box protein, AtPUB49, representing a large family of eukaryotic proteins containing a U-box linked to a cyclophilin-like peptidyl-prolyl cis-trans isomerase domain, was characterized biochemically. AtPUB49 functioned both as a prolyl isomerase and a chaperone by catalysing cis-trans isomerization of peptidyl-prolyl bonds and dissolving protein aggregates. In conclusion, both typical and atypical Arabidopsis U-box proteins were active E3s. The overlap in the E3/E2 selectivity suggests that in vivo specificity is not determined only by the E3-E2 interactions, but also by other parameters, e.g. co-existence or interactions with additional domains. The biochemical functions of AtPUB49 suggest that the protein can be involved in folding or degradation of protein substrates. Similar functions can also be retained within a protein complex with separate chaperone and U-box proteins.

Single crystal structures and theoretical calculations of uranium endohedral metallofullerenes (U@C2n , 2n = 74, 82) show cage isomer dependent oxidation states for U.

Science.gov (United States)

Cai, Wenting; Morales-Martínez, Roser; Zhang, Xingxing; Najera, Daniel; Romero, Elkin L; Metta-Magaña, Alejandro; Rodríguez-Fortea, Antonio; Fortier, Skye; Chen, Ning; Poblet, Josep M; Echegoyen, Luis

2017-08-01

Charge transfer is a general phenomenon observed for all endohedral mono-metallofullerenes. Since the detection of the first endohedral metallofullerene (EMF), La@C 82 , in 1991, it has always been observed that the oxidation state of a given encapsulated metal is always the same, regardless of the cage size. No crystallographic data exist for any early actinide endohedrals and little is known about the oxidation states for the few compounds that have been reported. Here we report the X-ray structures of three uranium metallofullerenes, U@ D 3h -C 74 , U@ C 2 (5)-C 82 and U@ C 2v (9)-C 82 , and provide theoretical evidence for cage isomer dependent charge transfer states for U. Results from DFT calculations show that U@ D 3h -C 74 and U@ C 2 (5)-C 82 have tetravalent electronic configurations corresponding to U 4+ @ D 3h -C 74 4- and U 4+ @ C 2 (5)-C 82 4- . Surprisingly, the isomeric U@ C 2v (9)-C 82 has a trivalent electronic configuration corresponding to U 3+ @ C 2v (9)-C 82 3- . These are the first X-ray crystallographic structures of uranium EMFs and this is first observation of metal oxidation state dependence on carbon cage isomerism for mono-EMFs.

Effect of temperature on the expansion and microstructure Of U3 Si2-AI mini plate fuel of 3.6 g/cm3 uranium loading

International Nuclear Information System (INIS)

Ginting, A. Br.; Samosir, N.; Suparjo; Nasution, H.

2000-01-01

Expansion analysis has been conducted to 50 x 20-mm U 3 Si 2 -AI mini plate of 3.6 g/cm 3 uranium loading using dilatometer. The analysis was carried out at various temperatures of 170 o C, 350 o C and 550 o C in Argon medium with delay time 4 days. The result showed that the fuel plate was relatively stable with increasing of heating time but underwent significant expansion. Heating at 170 o C, 350 o C and 550 o C resulted in the expansion of the U 3 Si 2 -AI fuel plate of to 83-212 mum, 333-475 mum, and 433-724 mum with coefficient expansion of 24.2x10 -6 / o C - 24.3x10 -6 / o C, 25.5x10 -6 / o C - 26.2x10 -6 /'oC and 26.6 x 10 -6 / o C - 28.2 x 10 -6 / o C respectively. Microanalysis of the U 3 Si 2 -AI mini plate fuel with SEM-EDS upon heating at those temperature variation showed that microstructure change didn't occur at 170 o C, mean while interaction between AIMg2 cladding and the fuel meat appeared to take place at 350 o C and 550 o C. Data on the expansion and microstructure change of U 3 Si 2 -AI fuel plate upon heating are of great important for the manufacture/fabrication of research fuel plate to produce silicide fuel element for higher uranium loading. (author)

Optical spectroscopy and crystal-field analysis of U3+: Ba2YCl7

International Nuclear Information System (INIS)

Karbowiak, M.; Mech, A.; Drozdzyndki, J.; Gajek, Z.; Edelstein, N.M.

2002-01-01

High resolution absorption spectra of a U 3+ (0.3%): Ba 2 YCl 7 single crystal were recorded in the 4000-50 000 cm -1 range at 7 K. The observed crystal-field levels were assigned and fit to the parameters of the simplified angular overlap model (AOM) as well as a semi-empirical Hamiltonian representing the combined atomic and one-electron crystal-field interactions. The starting values of the AOM parameters were obtained from ab initio calculations. The analysis of the spectra allowed the assignment of 65 crystal-field levels with a relatively small rms deviation of 25 cm -1 and has shown that the AOM approach can predict quite well the B q k crystal-field parameters. The value determined for the crystal-field strength parameter, N v , corresponds well with those determined for U 3+ in other chloride single crystals. (authors)

Preparation of High-Density Uranium-Silicide U3Sl2-Uss: Effects of Preirradiation Heat Treatment on As-Cast Ingot Fuel Plates

International Nuclear Information System (INIS)

Suripto, A; Yuwono

1998-01-01

Heat treatment experiments upon U 3 Si 2 - U ss ingot have been cam e d out to obtain free uranium particle size improvement which is required to enhance the U-Al inter-diffusion reaction in the fuel plate meat. . Heat treatment experiments upon fuel plates containing dispersion of U 3 Si 2 - U ss in Al matrix have also been carried out to study the effect of temperature and treatment duration on the extent of inter-diffusion reaction between free uranium particle and aluminium matrix in the fuel plate meat. Both the experiments indicate that a drastic size improvement has occurred with the U 3 Si 2 as well as free uranium particles upon heat treatment at controlled temperature between the U 3 Si 2 peritectic and peritectoid temperatures and that the inter-diffusion reaction between free uranium and Al matrix occurs quite significantly at temperatures higher than that ordinarily used in the fabrication procedure

Characterization Ag/AgCl reference electrode by U/U3+ equilibrium potential measurements in LiCl-KCl eutectic melt

International Nuclear Information System (INIS)

Kobayashi, Fumiaki; Kitawaki, Shinichi; Amamoto, Ippei; Igarashi, Miyuki

1999-02-01

The Ag/ AgCl reference electrode is often used in electrochemical measurements of molten chloride system. By measuring the U/U 3+ equilibrium potential in the cell, U(s) | UCl 3 , LiCl-KCl parallel LiCl-KCl, Ag + | Ag (s), the characterization of the Ag/AgCl reference electrode was made. The behavior of two types of reference electrode having either a mullite or a Pyrex-glass membrane bridge was examined. It was confirmed that the two types of reference electrode can be regarded as almost equivalent. The reproducibility of the reading from the electrodes having the identical construction was showing to be within 0.003 V. (author)

Path integral for coherent states of the dynamical U2 group and U2/1 supergroup

International Nuclear Information System (INIS)

Kochetov, E.A.

1992-01-01

A part-integral formulation in the representation of coherent states for the unitary U 2 group and U 2/1 supergroup is introduced. U 2 and U 2/1 path integrals are shown to be defined on the coset spaces U 2 /U 1 xU 1 and U 2/1 /U 1/1 xU 1 , respectively. These coset appears as curved classical phase spaces. Partition functions are expressed as path integrals over these spaces. In the case when U 2 and U 2/1 are the dynamical groups, the corresponding path integrals are evaluated with the help of linear fractional transformations that appear as the group (supergroup) action in the coset space (superspace). Possible applications for quantum models are discussed. 9 refs

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)

U3O8 production cost analysis study

International Nuclear Information System (INIS)

1978-08-01

This report presents the User's Manual for the computer program resulting from Bechtel's uranium production cost analysis. The model incorporates engineering and financial costs of sandstone mining and milling in the western United States. It does not consider exploration costs. The model was written in Fortran V, IBM compatible. Inputs from the user are such items as: ore grades, open pit or underground mines, acid or carbonate leach, and debt/equity ratio. The user may either input the desired discounted cash flow rate of return and obtain the necessary U 3 O 8 price, or input an estimated U 3 O 8 price and obtain the resulting discounted cash flow rate of return

Self-association and domain rearrangements between complement C3 and C3u provide insight into the activation mechanism of C3.

Science.gov (United States)

Li, Keying; Gor, Jayesh; Perkins, Stephen J

2010-10-01

Component C3 is the central protein of the complement system. During complement activation, the thioester group in C3 is slowly hydrolysed to form C3u, then the presence of C3u enables the rapid conversion of C3 into functionally active C3b. C3u shows functional similarities to C3b. To clarify this mechanism, the self-association properties and solution structures of C3 and C3u were determined using analytical ultracentrifugation and X-ray scattering. Sedimentation coefficients identified two different dimerization events in both proteins. A fast dimerization was observed in 50 mM NaCl but not in 137 mM NaCl. Low amounts of a slow dimerization was observed for C3u and C3 in both buffers. The X-ray radius of gyration RG values were unchanged for both C3 and C3u in 137 mM NaCl, but depend on concentration in 50 mM NaCl. The C3 crystal structure gave good X-ray fits for C3 in 137 mM NaCl. By randomization of the TED (thioester-containing domain)/CUB (for complement protein subcomponents C1r/C1s, urchin embryonic growth factor and bone morphogenetic protein 1) domains in the C3b crystal structure, X-ray fits showed that the TED/CUB domains in C3u are extended and differ from the more compact arrangement of C3b. This TED/CUB conformation is intermediate between those of C3 and C3b. The greater exposure of the TED domain in C3u (which possesses the hydrolysed reactive thioester) accounts for the greater self-association of C3u in low-salt conditions. This conformational variability of the TED/CUB domains would facilitate their interactions with a broad range of antigenic surfaces. The second dimerization of C3 and C3u may correspond to a dimer observed in one of the crystal structures of C3b.

Wongabel Rhabdovirus Accessory Protein U3 Targets the SWI/SNF Chromatin Remodeling Complex

Science.gov (United States)

Joubert, D. Albert; Rodriguez-Andres, Julio; Monaghan, Paul; Cummins, Michelle; McKinstry, William J.; Paradkar, Prasad N.; Moseley, Gregory W.

2014-01-01

ABSTRACT Wongabel virus (WONV) is an arthropod-borne rhabdovirus that infects birds. It is one of the growing array of rhabdoviruses with complex genomes that encode multiple accessory proteins of unknown function. In addition to the five canonical rhabdovirus structural protein genes (N, P, M, G, and L), the 13.2-kb negative-sense single-stranded RNA (ssRNA) WONV genome contains five uncharacterized accessory genes, one overlapping the N gene (Nx or U4), three located between the P and M genes (U1 to U3), and a fifth one overlapping the G gene (Gx or U5). Here we show that WONV U3 is expressed during infection in insect and mammalian cells and is required for efficient viral replication. A yeast two-hybrid screen against a mosquito cell cDNA library identified that WONV U3 interacts with the 83-amino-acid (aa) C-terminal domain of SNF5, a component of the SWI/SNF chromatin remodeling complex. The interaction was confirmed by affinity chromatography, and nuclear colocalization was established by confocal microscopy. Gene expression studies showed that SNF5 transcripts are upregulated during infection of mosquito cells with WONV, as well as West Nile virus (Flaviviridae) and bovine ephemeral fever virus (Rhabdoviridae), and that SNF5 knockdown results in increased WONV replication. WONV U3 also inhibits SNF5-regulated expression of the cytokine gene CSF1. The data suggest that WONV U3 targets the SWI/SNF complex to block the host response to infection. IMPORTANCE The rhabdoviruses comprise a large family of RNA viruses infecting plants, vertebrates, and invertebrates. In addition to the major structural proteins (N, P, M, G, and L), many rhabdoviruses encode a diverse array of accessory proteins of largely unknown function. Understanding the role of these proteins may reveal much about host-pathogen interactions in infected cells. Here we examine accessory protein U3 of Wongabel virus, an arthropod-borne rhabdovirus that infects birds. We show that U3 enters the

Preparation of U-Si/U-Me (Me = Fe, Ni, Mn) aluminum-dispersion plate-type fuel (miniplates) for capsule irradiation

International Nuclear Information System (INIS)

Ugajin, Mitsuhiro; Itoh, Akinori; Akabori, Mitsuo

1993-06-01

Details of equipment installed, method adopted and final products were described on the preparation of uranium silicides and other fuels for capsule irradiation. Main emphasis was placed on the preparation of laboratory-scale aluminum-dispersion plate-type fuel (miniplates) loaded to the first and second JMTR silicide capsules. Fuels contained in the capsules are as follows: (A) uranium-silicide base alloys U 3 Si 2 , Mo- added U 3 Si 2 , U 3 Si 2 +U 3 Si, U 3 Si 2 +USi, U 3 Si, U 3 (Si 0.8 Ge 0.2 ), U 3 (Si 0.6 Ge 0.4 ) (B) U 6 Me-type alloys with higher uranium density U 6 Mn, U 6 Ni, U 6 (Fe 0.4 Ni 0.6 ), U 6 (Fe 0.6 Mn 0.4 ) The powder-metallurgical picture-frame method was adopted and laboratory-scale technique was established for the preparation of miniplates. As a result of inspection for capsule irradiation, miniplates were prepared to meet the requirements of specification. (author)

Effect of thermo-mechanical processing on microstructure and mechanical properties of U - Nb - Zr alloys: Part 2 - U - 3 wt % Nb - 9 wt % Zr and U - 9 wt% Nb - 3 wt% Zr

Science.gov (United States)

Morais, Nathanael Wagner Sales; Lopes, Denise Adorno; Schön, Cláudio Geraldo

2018-04-01

The present work is the second and final part of an extended investigation on Usbnd Nb - Zr alloys. It investigates the effect of mechanical processing routes on microstructure of alloys U - 3 wt % Nb - 9 wt % Zr and U - 9 wt% Nb - 3 wt% Zr, through X-ray diffraction and scanning electron microscopy, completing the investigation, which started with alloy U - 6 wt% Nb - 6 wt% Zr in part 1. Mechanical properties are determined using microhardness and bending tests and correlated with the developed microstructures. The results show that processing sequence, in particular the inclusion of a 1000 °C heat treatment step, affects significantly the microstructure and mechanical properties of these alloys alloy in different ways. Microstructural characterization shows that both alloys present significant volume fraction of precipitates of a body-centered cubic (BCC) γ-Nb-Zr rich phase in addition the uranium-rich matrix. Bending tests show that sample ductility does not correlate necessarily with hardness and that the key factor appears to be the amount of the γ-Nb-Zr precipitates, which controls the matrix microstructure. Samples with a monoclinic α″ cellular microstructure and/or with the tetragonally-distorted BCC phase (γ0), although not strictly ductile, showed the largest allowed strains-before-break and complete elastic recovery of the broken pieces, pointing out to the macroscopic observation of superelasticity.

Structure and physical properties of ternary uranium transition-metal antimonides U3MSb5 (M = Zr, Hf, Nb)

International Nuclear Information System (INIS)

Tkachuk, Andriy V.; Muirhead, Craig P.T.; Mar, Arthur

2006-01-01

The ternary uranium transition-metal antimonides U 3 MSb 5 (M = Zr, Hf, Nb) were prepared by arc-melting reactions followed by annealing at 800 deg. C, or by use of a Sn flux. These compounds extend the previously known series U 3 MSb 5 (M = Ti, V, Cr, Mn) and RE 3 MSb 5 (RE = La, Ce, Pr, Nd, Sm; M = Ti, Zr, Hf, Nb). The crystal structures of U 3 MSb 5 were determined by single-crystal X-ray diffraction data (Pearson symbol hP18, hexagonal, space group P6 3 /mcm, Z = 2; U 3 ZrSb 5 , a = 9.2223(3) A, c = 6.1690(2) A; U 3 HfSb 5 , a = 9.2084(4) A, c = 6.1629(3) A; U 3 NbSb 5 , a = 9.1378(4) A, c 6.0909(6) A). U 3 TaSb 5 has also been identified in microcrystalline form (a = 9.233(3) A, c = 6.142(3) A). Four-probe electrical resistivity measurements on single crystals and dc magnetic susceptibility measurements on powders indicated prominent transitions that are attributed to ferromagnetic ordering. The Curie temperatures, T C , located from ac magnetic susceptibility curves, are 135 K for U 3 ZrSb 5 , 141 K for U 3 HfSb 5 , and 107 K for U 3 NbSb 5

U{sub 3}O{sub 8} and UO{sub 2} obtained from ADU (ammonium diuranate) ultrasonically treated; Obtencion de U{sub 3}O{sub 8} y UO{sub 2} a partir de ADU (diuranato amonico) precipitado con aplicacion de ultrasonido

Energy Technology Data Exchange (ETDEWEB)

Boero, N; Sassone, A; Mendez de Leo, L; Novara, O; Ramella, J [Comision Nacional de Energia Atomica, San Martin (Argentina). Unidad de Actividad Combustibles Nucleares

1997-12-31

At present, obtention of U{sub 3}O{sub 8} used in the manufacturing of MTR plates nuclear fuels, is performed by hydrolysis of UF6 to obtain uranyl fluoride. Uranyl fluoride is precipitated with ammonium hydroxide to get ammonium polyuranate (ADU). Afterwards ADU is calcinated to U{sub 3}O{sub 8} and mechanical and thermally treated in order to obtain a powder in a determined specification. In the present work, ultrasound has been applied in the stage of precipitation of ADU and for different times in the stage of digestion in order to fasten the stages of ADU filtering and eliminate the U{sub 3}O{sub 8} milling and sieving. Experiences on UO{sub 2} have also been performed. The aspect of ADU changes considerably when they have been ultrasonically treated, its filtering rate is faster and it is easier to dry as it contains less humidity. U{sub 3}O{sub 8} obtained after 800degreeC calcination of treated ADU results in an easy to desagregate powder. Only a soft mechanical treatment is needed to be performed on it before starting thermal treatment at 1400degreeC. After thermal treatment at 1400degreeC treated U{sub 3}O{sub 8} has shown adequate characteristics of size, shape and density (8.2 g/cm{sup 3}). Regarding UO{sub 2}, the shape of the agglomerates is almost spherical, leading to a free-flowing powder, whose apparent and TAP density showed to be adequate. The characteristics of the different compounds were followed by electron scanning micrographies, X-Rays, specific area measurements and differential thermal analysis. The great advantage of ultrasound appliance is that hard mechanical treatment is avoided in the obtention of U{sub 3}O{sub 8}, saving time and effort. Furthermore, UO{sub 2} proves to be adequate to make pellets, the same precursor could be used in the obtention of both uranium oxides. (author). 5 refs., 6 figs.

The Experiment Production And Examination Of The U3Si2-AI Mini plates For Irradiation Test

International Nuclear Information System (INIS)

Supardjo; Boybul; Yowono; Susworo; Permana, S.

1998-01-01

The fuel plates containing U 3 Si 2 -AI dispersion fuel having respective loading of 3.55; 4.20; and 4.80 g/cm 3 were prepared by dispersing certain amount of U 3 Si 2 powder in the AI powder as matrix. The weight ratio of U 3 Si 2 and AI at different loading was chosen based on the 19.23 cm 3 volume basis fuel core calculation. Each fuel mixture was pressed into a fuel core having dimension of 100.20 x 60.35 x 3.15 +- (0.05) mm, which was then cut into mini fuel core having dimension of 16 x 8 x 3.15 +- (0.05) mm. The mini plates were prepared by picture and frame technique using AIMg2 as cladding material. The mini plates have been tested for blister, homogeneity, white spots, surface defects and their cladding thickness, revealing that out of 74 mini plates, they are ten (10) mini plates that have to be rejected due to blisters and white spots, thus of 64 mini plates can be further fabricated as samples for irradiation test

Photoassociation spectroscopy of 87Rb2 (5s1/2+5p1/2)0u+ long-range molecular states: Coupling with the (5s1/2+5p3/2)0u+ series analyzed using the Lu-Fano approach

International Nuclear Information System (INIS)

Jelassi, H.; Viaris de Lesegno, B.; Pruvost, L.

2006-01-01

We report on photoassociation of cold 87 Rb atoms providing the spectroscopy of (5s 1/2 +5p 1/2 )0 u + long-range molecular states, in the energy range of [-12.5, -0.7 cm -1 ] below the dissociation limit. A Lu-Fano approach coupled to the LeRoy-Bernstein formula is used to analyze the data. The Lu-Fano graph exhibits the coupling of the molecular series with the (5s 1/2 +5p 3/2 )0 u + one, which is due to spin effects in the molecule. A two-channel model involving an improved LeRoy-Bernstein formula allows us to characterize the molecular series, to localize (5s 1/2 +5p 3/2 )0 u + levels, to evaluate the coupling, and to predict the energy and width of the first predissociated level of (5s 1/2 +5p 3/2 )0 u + series. An experimental spectrum confirms the prediction

Properties measurements of (U{sub 0.7}Pu{sub 0.3})O{sub 2-x} in PO{sub 2}-controlled atmosphere

Energy Technology Data Exchange (ETDEWEB)

Kato, M.; Murakami, T.; Sunaoshi, T. [Advanced Nuclear System Research and Development Directorate, Japan Atomic Energy Agency, Muramatsu Tokai-mura Ibaraki, 319-1194 (Japan); Nelson, A.T.; McClellan, K.J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2013-07-01

The investigation of physical properties of uranium and plutonium mixed oxide (MOX) fuels is important for the development of fast reactor fuels. It is well known that MOX is a nonstoichiometric oxide, and the physical properties change drastically with the Oxygen-to-Metal (O/M) ratio. A control technique for O/M ratio was established for measurements of high temperature properties of uranium and plutonium mixed oxide fuels. Sintering behavior, thermal expansion and O/M change of (U{sub 0.7}Pu{sub 0.3})O{sub 2.00} and (U{sub 0.7}Pu{sub 0.3})O{sub 1.99} were investigated in PO{sub 2}-controlled atmosphere which was controlled by H{sub 2}/H{sub 2}O gas system. Sintering behavior changed drastically with O/M ratio, and shrinkage of (U{sub 0.7}Pu{sub 0.3})O{sub 2.00} was faster and more advanced at lower temperatures as compared with (U{sub 0.7}Pu{sub 0.3})O{sub 1.99}. Thermal expansion was observed to be slightly increased with decreasing O/M ratio. (authors)

Subjective experiences of watching stereoscopic Avatar and U2 3D in a cinema

Science.gov (United States)

Pölönen, Monika; Salmimaa, Marja; Takatalo, Jari; Häkkinen, Jukka

2012-01-01

A stereoscopic 3-D version of the film Avatar was shown to 85 people who subsequently answered questions related to sickness, visual strain, stereoscopic image quality, and sense of presence. Viewing Avatar for 165 min induced some symptoms of visual strain and sickness, but the symptom levels remained low. A comparison between Avatar and previously published results for the film U2 3D showed that sickness and visual strain levels were similar despite the films' runtimes. The genre of the film had a significant effect on the viewers' opinions and sense of presence. Avatar, which has been described as a combination of action, adventure, and sci-fi genres, was experienced as more immersive and engaging than the music documentary U2 3D. However, participants in both studies were immersed, focused, and absorbed in watching the stereoscopic 3-D (S3-D) film and were pleased with the film environments. The results also showed that previous stereoscopic 3-D experience significantly reduced the amount of reported eye strain and complaints about the weight of the viewing glasses.

Closure Report for Corrective Action Unit 110: Areas 3 RWMS U-3ax/bl Disposal Unit, Nevada Test Site, Nevada

Energy Technology Data Exchange (ETDEWEB)

J. L. Smith

2001-08-01

This Closure Report (CR) has been prepared for the Area 3 Radioactive Waste Management Site (RWMS) U-3ax/bl Disposal Unit Corrective Action Unit (CAU) 110 in accordance with the reissued (November 2000) Resource Conservation and Recovery Act (RCRA) Part B operational permit NEV HW009 (Nevada Division of Environmental Protection [NDEP], 2000) and the Federal Facility and Consent Order (FFACO) (NDEP et al., 1996). CAU 110 consists of one Corrective Action Site 03-23-04, described as the U-3ax/bl Subsidence Crater. Certifications of closure are located in Appendix A. The U-3ax/bl is a historic disposal unit within the Area 3 RWMS located on the Nevada Test Site (NTS). The unit, which was formed by excavating the area between two subsidence craters (U-3ax and U-3bl), was operationally closed in 1987. The U-3ax/bl disposal unit was closed under the RCRA, as a hazardous waste landfill. Existing records indicate that, from July 1968 to December 1987, U-3ax/bl received 2.3 x 10{sup 5} cubic meters (m{sup 3}) (8.12 x 10{sup 6} cubic feet [ft{sup 3}]) of waste. NTS atmospheric nuclear device testing generated approximately 95% of the total waste volume disposed of in U-3ax/bl; 80% of the total volume was generated from the Waste Consolidation Project. Area 3 is located in Yucca Flat, within the northeast quadrant of the NTS. The Yucca Flat watershed is a structurally closed basin encompassing an area of approximately 780 square kilometers (300 square miles). The structural geomorphology of Yucca Flat is typical of the Basin and Range Physiographic Province. Yucca Flat lies in one of the most arid regions of the country. Water balance calculations for Area 3 indicate that it is normally in a state of moisture deficit.

Nu2U

DEFF Research Database (Denmark)

Sørensen, Hans Eibe; Williamson, Trevor

Abstract In September 2014, nine months after launching a major growth opportunity, Jenny Dunne, managing director of Nu2U, called for an extraordinary status meeting with her COO and CMO. A fast-growing online retailer of refurbished household appliances, Nu2U planned to acquire market share...... by improving internal logistics and delivery services, aided by a new, fully integrated software system. The company's gross profit had been increasing steadily, but recent accounts revealed a fall in net profit margins. It became apparent that implementation of the business plan for the project...... was problematic because of loose governance and poor communication across Nu2U's different specialist functions during planning and implementation. The Nu2U case illustrates how executives' cognition and span of control/overview may be hampered in fast-growing firms and how this ...

Hydrogen isotope effect on storage behavior of U{sub 2}Ti and UZr{sub 2.3}

Energy Technology Data Exchange (ETDEWEB)

Jat, Ram Avtar; Sawant, S.G.; Rajan, M.B.; Dhanuskar, J.R. [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Kaity, Santu [Radiometallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Parida, S.C., E-mail: sureshp@barc.gov.in [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2013-11-15

U{sub 2}Ti and UZr{sub 2.3} alloys were prepared by arc melting method, vacuum annealed and characterized by XRD, SEM and EDX methods. Hydrogen isotope effect on the storage behavior of these alloys were studied by measuring the hydrogen/deuterium desorption pressure–composition–temperature (PCT) profiles in the temperature range of 573–678 K using a Sievert’s type volumetric apparatus. It was observed that, in the temperature and pressure range of investigation, all the isotherms show a single desorption plateau. The PCT data reveals that both U{sub 2}Ti and UZr{sub 2.3} alloys had normal isotope effects on hydrogen/deuterium desorption at all experimental temperatures. Thermodynamic parameters for dehydrogenation and dedeuteration reactions of the corresponding hydrides and deuterides of the above alloys were deduced from the PCT data.

Comparison of thermal compatibility between atomized and comminuted U{sub 3}Si dispersion fuels

Energy Technology Data Exchange (ETDEWEB)

Ryu, Woo-Seog; Park, Jong-Man; Kim, Chang-Kyu; Kuk, II-Hyun [Korea Atomic Research Institute, Taejon (Korea, Republic of)

1997-08-01

Thermal compatibility of atomized U{sub 3}Si dispersion fuels were evaluated up to 2600 hours in the temperature range from 250 to 500{degrees}C, and compared with that of comminuted U{sub 3}Si. Atomized U{sub 3}Si showed better performance in terms of volume expansion of fuel meats. The reaction zone of U{sub 3}Si and Al occurred along the grain boundaries and deformation bands in U{sub 3}Si particles. Pores around fuel particles appeared at high temperature or after long-term annealing tests to remain diffusion paths over the trench of the pores. The constraint effects of cladding on fuel rod suppressed the fuel meat, and reduced the volume expansion.

Photochemistry of U(BH/sub 4/)/sub 4/ and U(BD/sub 4/)/sub 4/

Energy Technology Data Exchange (ETDEWEB)

Paine, R T; Schonberg, P R; Light, R W [New Mexico Univ., Albuquerque (USA). Dept. of Chemistry; Danen, W C; Freund, S M

1979-01-01

U(BH/sub 4/)/sub 4/ and U(BD/sub 4/)/sub 4/ are observed to undergo complex degradation reactions promoted by broadband UV radiation. The primary products of these reactions appear to be U(BH/sub 4/)/sub 3/, B/sub 2/H/sub 6/, H/sub 2/, U(BD/sub 4/)/sub 3/, B/sub 2/D/sub 6/ and D/sub 2/. Further, U(BD/sub 4/)/sub 4/ undergoes a related decomposition reaction under the influence of CO/sub 2/ laser irradiation at 924.97 cm/sup -1/.

Principles and Practices of Mature-Age Education at U3As

Science.gov (United States)

Siedle, Rob

2011-01-01

A movement known as the Universities of the Third Age (U3As) provides educational, cultural and social services for mature-age people in Australia and internationally. This paper focuses on the educational courses run by U3As and discusses two basic questions: What are the expectations of learners who enrol in these classes? and How can tutors…

New N2(C 3Πu, v) collision quenching and vibrational relaxation rate constants: 2. PG emission diagnostics of high-pressure discharges

International Nuclear Information System (INIS)

Dilecce, G; Ambrico, P F; De Benedictis, S

2007-01-01

The present paper deals with the determination of discharge parameters using N 2 (C 3 Π u , v) populations deduced from 2.PG emission spectra, focusing on the influence of N 2 (C 3 Π u , v) collision rate coefficients on these determinations. In particular it is shown that the new set of quenching and vibrational relaxation rate coefficients of N 2 (C 3 Π u , v 0-4) vibronic levels recently measured by optical-optical double resonance laser induced fluorescence (LIF) have a large effect on discharge parameter determination in high-pressure discharges. In the present paper we explore this effect, evidencing the differences with respect to the old data set case, in both simulated and real cases of N 2 (C 3 Π u , v) vibrational distributions measured at high pressure in a dielectric barrier discharge. Finally we point out the improved potentiality of 2.PG spectroscopy as a diagnostic technique: with the new rate coefficients, and measurement of the N 2 (C 3 Π u , v) distribution up to at least v = 3, it is possible to have a quasi-independent evaluation of the electron temperature and of the first level vibrational temperature of the N 2 ground state

Theoretical Mn K-edge XANES for Li2MnO3: DFT + U study

International Nuclear Information System (INIS)

Tamura, Tomoyuki; Ohwaki, Tsukuru; Ito, Atsushi; Ohsawa, Yasuhiko; Kobayashi, Ryo; Ogata, Shuji

2012-01-01

Spectral features of Mn K-edge x-ray absorption near-edge structure (XANES) for Li 2 MnO 3 were calculated using the first-principles full projector augmented wave method with the general gradient approximation plus U method. We demonstrated that the U parameter affects the spectral features in the pre-edge region while it does not affect those in the major absorption region. From the comparison with the experimental spectra and those of reference compounds, we showed that the spectral features of Mn K-edge XANES and the differences in the valence state can be reproduced well. (paper)

New insights in third phase formation in the U(VI)-HNO3, TBP-alkane system

International Nuclear Information System (INIS)

Jensen, M. P.; Chiarizia, R.; Ferraro, J. R.; Borkowski, M.; Nash, K. L.; Thiyagarajan, P.; Littrell, K. C.

2001-01-01

In this work, the system U(VI)-HNO 3 -tributylphosphate (TBP)-n-dodecane has been revisited with the objective of gaining coordination chemistry and structural information on the species that are formed in the organic phase before and after third phase formation. Chemical analyses, spectroscopic and EXAFS data indicate that U(VI) is extracted as the UO 2 (NO 3 ) 2 · 2TBP adduct, while the third phase species has the composition UO 2 (NO 3 ) 2 · 2TBP · HNO 3 . Small-angle neutron scattering (SANS) data reveal the presence in the organic phase, both before and after phase splitting, of ellipsoidal aggregates whose formation seems to depend more on the extraction of HNO 3 than that of U(VI)

Sorption of U(VI) in surfaces of SrTiO{sub 3}; Sorcion de U(VI) en superficies de SrTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Ortiz O, H.B.; Ordonez R, E.; Fernandez V, S.M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2004-07-01

In this work is presented the physico chemical characterization and evaluation of those surface properties and of sorption of U on the SrTiO{sub 3} like possible candidate for contention barrier in the deep geological confinement. The made studies showed that the SrTiO{sub 3} presents maximum levels of sorption of positive nature species (mainly UO{sub 2}{sup 2+} and UO{sub 2}NO{sub 3}{sup +}). (Author)

Third phase formation revisited: the U(VI), HNO3 - TBP, n-dodecane system

International Nuclear Information System (INIS)

Chiarizia, R.; Jensen, M.P.; Borkowski, M.; Ferraro, J.R.; Thiyagarajan, P.; Littrell, K.C.

2003-01-01

In this work, the system U(VI), HNO 3 -tri-n-butylphosphate (TBP), n-dodecane has been revisited with the objective of gaining information on the coordination chemistry and structural evolution of the species formed in the organic phase before and after third phase formation. Chemical analyses, spectroscopic and EXAFS data indicate that U(VI) is extracted as the UO 2 (NO 3 ) 2 ·2TBP adduct, while the third phase species have the average composition UO 2 (NO 3 ) 2 ·2TBP·HNO 3 . Small-angle neutron scattering (SANS) measurements on TBP solutions loaded with only HNO 3 or with increasing amounts of U(VI) have revealed the presence, before phase splitting, of ellipsoidal aggregates with the major and minor axes up to about 64 and 15 A, respectively. The formation of these aggregates, very likely of the reverse micelle-type, is observed in all cases, that is, when only HNO 3 , only UO 2 (NO 3 ) 2 , or both HNO 3 and UO 2 (NO 3 ) 2 are extracted by the TBP solution. Upon third phase formation, the SANS data reveal the presence of smaller aggregates in the light organic phase, while the heavy organic phase contains pockets of diluent, each with an average of about two molecules of n-dodecane.

A gravimetric and an X-ray fluorescence method for the determination of rubidium in Rb2U(SO4)3

International Nuclear Information System (INIS)

Mudher, K.D.S.; Krishnan, K.; Jayadevan, N.C.

1993-01-01

Chemical characterization of rubidium uranium(IV) trisulfate, RB 2 U(SO 4 ) 3 , a new chemical assay standard for uranium requires accurate analysis of rubidium. A gravimetric and an X-ray fluorescence method (XRF) for the determination of rubidium in this compound are described. In the gravimetric method, rubidium is determined as Rb 2 Na[Co(NO 2 ) 6 ].H 2 O without separating uranium with a precision of the order of ±0.5%. In the XRF method, the concentration ratio of rubidium to uranium, C Rb /C U , is determined in the solid samples by the binary ratio method using calibration between intensity ratios (I Rb /I U ) and concentration ratios (C Rb /C U ). (author) 6 refs.; 2 figs.; 3 tabs

Uniqueness of Positive Solutions of Δu+f(u)=0 in N, N<=3

Science.gov (United States)

Cortázar, Carmen; Elgueta, Manuel; Felmer, Patricio

We study the uniqueness of radial ground states for the semilinear elliptic partial differential equation $Δ u+f(u)=0 {(*)}$ in N. We assume that the function f has two zeros, the origin and u0>0. Above u0 the function f is positive, is locally Lipschitz continuous and satisfies convexity and growth conditions of a superlinear nature. Below u0, f is assumed to be non-positive, non-identically zero and merely continuous. Our results are obtained through a careful analysis of the solutions of an associated initial-value problem, and the use of a monotone separation theorem. It is known that, for a large class of functions f, the ground states of (*) are radially symmetric. In these cases our result implies that (*) possesses at most one ground state.

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

International Nuclear Information System (INIS)

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

2000-01-01

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

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)

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)

Coextrusion of 60 to 80 wt % U3O8 nuclear fuel elements

International Nuclear Information System (INIS)

Peacock, H.B.

1980-01-01

Aluminum-clad billets with up to 80 wt % U 3 O 8 in U 3 O 8 -Al cores have been coextruded at SRP. However, above 70 wt % U 3 O 8 , yields are low because of core-cracking. Proper selection of materials and extrusion parameters will give process conditions for successful fabrication. Studies were begun of the effects of these parameters on the flow of metal during coextrusion. In coextruded tubes, cracks are formed in large uranium oxide particles. Cracking is caused by the high tensile deformation of these particles that occurs as the cermet material flows through the die. Lower extrusion ratios and larger die angles appear to reduce severe particle cracking and increase fabrication yields. The particle size distribution of the ceramic fuel phase also influences fabricability. Six P/M assemblies with up to 57 wt % U 3 O 8 in U 3 O 8 -Al cores were successfully irradiated to 1.6 x 10 21 fissions per cm 3 of core. No swelling or blistering of the tubes occurred

Simulation of accident-tolerant U{sub 3}Si{sub 2} fuel using FRAPCON code

Energy Technology Data Exchange (ETDEWEB)

Gomes, Daniel S.; Silva, Antonio T.; Abe, Alfredo Y.; Muniz, Rafael O.R., E-mail: dsgomes@ipen.br, E-mail: teixeira@ipen.br, E-mail: alfredo@ctmsp.mar.mil.br, E-mail: rafael.orm@gmail.com [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Giovedi, Claudia, E-mail: claudia.giovedi@ctmsp.mar.mil.br [Universidade de São Paulo (USP), São Paulo, SP (Brazil). Departamento de Engenharia Naval e Oceânica

2017-07-01

The research on accident-tolerant fuels (ATFs) increased after the Fukushima event. This benefited risk management in nuclear operations. In this investigation, the physical properties of the materials being developed for the ATF program were compared with those of the standard UO{sub 2} - Zr fuel system. The research efforts in innovative fuel design include rigorous characterization of thermal, mechanical, and chemical assessment, with the objectives of making the burnup cycle longer, increasing power density, and improving safety performance. Fuels must reach a high uranium density - above that supported by UO{sub 2} - and possess coating that exhibits better oxidation resistance than Zircaloy. The uranium density and thermal conductivity of ATFs, such as U{sub 3}Si{sub 2}, UN, and UC, is higher than that of UO{sub 2}; their combination with advanced cladding provides possible fuel - cladding options. An ideal combination of fuel and cladding must increase fuel performance in loss-of-coolant scenarios. The disadvantages of U{sub 3}Si{sub 2}, UN, and UC are their swelling rates, which are higher than that of UO{sub 2}. The thermal conductivities of ATFs are approximately four times higher than that of UO2. To prevent the generation of hydrogen due to oxidation of zirconium-based alloys in contact with steam, cladding options, such as ferritic alloys, were studied. It was verified that FeCrAl alloys and SiC provide better response under severe conditions because of their thermophysical properties. The findings of this study indicate that U{sub 3}Si{sub 2} and the FeCrAl fuel cladding concept should replace UO{sub 2} - Zr as the fuel system of choice. (author)

Preparation of neptunium and plutonium tracers in nuclear reactions of sup 2 sup 3 sup 6 U with (21-60)MeV sup 3 He ions

CERN Document Server

Aaltonen, J; Trzaska, V; Gromova, E A; Yakovlev, V A

2001-01-01

Preparation of sup 2 sup 3 sup 6 Pu, sup 2 sup 3 sup 7 Pu and sup 2 sup 3 sup 5 Np by reactions sup 2 sup 3 sup 6 U( sup 3 He, t beta sup -) sup 2 sup 3 sup 6 Pu, sup 2 sup 3 sup 6 U( sup 3 He, 2n) sup 2 sup 3 sup 7 Pu and sup 2 sup 3 sup 6 U( sup 3 He, p3n) sup 2 sup 3 sup 5 Np in sup 3 He ion beams, their energy 43 and 60 MeV, in the K-130 cyclotron at Yuvyaskyul University (Finland) was studied. Cross sections of the reactions were determined. Yield curves for thick targets were calculated. The results are discussed and compared with previously obtained data on other reactions giving rise to formation of the same products. Methods of radiochemical separation of the products and sample preparation for alpha- and gamma-spectrometry are described

Reactivity feedback coefficients of a material test research reactor fueled with high-density U{sub 3}Si{sub 2} dispersion fuels

Energy Technology Data Exchange (ETDEWEB)

Muhammad, Farhan [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)], E-mail: farhan73@hotmail.com; Majid, Asad [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)

2008-10-15

The reactivity feedback coefficients of a material test research reactor fueled with high-density U{sub 3}Si{sub 2} dispersion fuels were calculated. For this purpose, the low-density LEU fuel of an MTR was replaced with high-density U{sub 3}Si{sub 2} LEU fuels currently being developed under the RERTR program. Calculations were carried out to find the fuel temperature reactivity coefficient, moderator temperature reactivity coefficient and moderator density reactivity coefficient. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It is observed that the average values of fuel temperature reactivity feedback coefficient, moderator temperature reactivity coefficient and moderator density reactivity coefficient from 20 deg. C to 100 deg. C, at the beginning of life, followed the relationships (in units of {delta}k/k x 10{sup -5} K{sup -1}) -2.116 - 0.118 {rho}{sub U}, 0.713 - 37.309/{rho}{sub U} and -12.765 - 34.309/{rho}{sub U}, respectively for 4.0 {<=} {rho}{sub U} (g/cm{sup 3}) {<=} 6.0.

Fabrication and microstructural analysis of UN-U_3Si_2 composites for accident tolerant fuel applications

International Nuclear Information System (INIS)

Johnson, Kyle D.; Raftery, Alicia M.; Lopes, Denise Adorno; Wallenius, Janne

2016-01-01

In this study, U_3Si_2 was synthesized via the use of arc-melting and mixed with UN powders, which together were sintered using the SPS method. The study revealed a number of interesting conclusions regarding the stability of the system – namely the formation of a probable but as yet unidentified ternary phase coupled with the reduction of the stoichiometry in the nitride phase – as well as some insights into the mechanics of the sintering process itself. By milling the silicide powders and reducing its particle size ratio compared to UN, it was possible to form a high density UN-U_3Si_2 composite, with desirable microstructural characteristics for accident tolerant fuel applications. - Highlights: • U_3Si_2 fabricated from elemental uranium and silicon through arc melting. • Homogeneity of the silicides assessed through densitometry, XRD, SEM and EDS, chemical etching and optical microscopy. • UN powder fabricated using hydriding-nitriding method. • No phase transformations detected when sintering using silicide particle sizes less than UN particle size. • High density composite (98%TD) fabricated with silicide grain coating using spark plasma sintering at 1450 °C.

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

Directory of Open Access Journals (Sweden)

Bogdan Skwarzec

2010-12-01

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

Temperature effect on the retention of U(VI) by SrTiO3

International Nuclear Information System (INIS)

Garcia Rosales, G.

2007-11-01

The purpose of this research was the study of the interaction mechanisms between U(VI) ions and SrTiO 3 surfaces versus pH and temperature: 25, 50, 75 and 90 C. Firstly, a physicochemical characterization was realized (DRX, MEB, FTIR) and the surface site density was determined. The potentiometric titration data were simulated, for each temperature, using the constant capacitance model and taking into account bath protonation of the ≡Sr-OH surface sites and deprotonation of the ≡Ti-OH ones (one pK a model). Both enthalpy and entropy changes, corresponding to the surface acid-base reactions, were evaluated using the van't Hoff relation. U(VI) was sorbed onto SrTiO 3 powder in the pH range 0.5-5.0 with an U(VI) initial concentration 1.10 -4 M. By TRLIFS two U(VI) complexes were detected associated with two lifetime values (60 ± 5 and 12 ± 2 μs at 25 C). The sorption edges were simulated using FITEQL 4.0 software. The surface complexation constants of the system SrTiO 3 /U(VI) between 25 and 90 C temperature range were thus obtained with the constant capacitance model considering two reactive surface sites. It reveals that two types of surface complex, namely [(≡SrOH)(≡TiOH)UO 2 ] 2+ and [(≡TiOH)(≡TiO)UO 2+ ] 2+ , are needed to properly describe the experimental observations. By application of the van't Hoff equation, Delta R S 0 and Delta R H 0 were obtained, which indicated an endothermic sorption process. Finally, an energy transfer study was realised by TRLIFS. The energy transfer between Tb 3+ and Eu 3+ ions sorbed onto SrTiO 3 powders were investigated. The results showed that the energy transfer between Tb 3+ and Eu 3+ is a non-radiative process and follows a dipole-dipole type interaction. A formalism based on the Dexter and the Inokuti-Hirayama theories was used to calculate the distances (2,7-3,4 Angstroms between Tb 3+ and Eu 3+ onto SrTiO 3 surface. (author)

The use of U3Si2 dispersed in aluminum in plate-type fuel elements for research and test reactors

International Nuclear Information System (INIS)

Snelgrove, J.L.; Domagala, R.F.; Hofman, G.L.; Wiencek, T.C.; Copeland, G.L.; Hobbs, R.W.; Senn, R.L.

1987-10-01

A high-density fuel based on U 3 Si 2 dispersed in aluminum has been developed and tested for use in converting plate-type research and test reactors from the use of highly enriched uranium to the use of low-enriched uranium. Results of preirradiation testing and the irradiation and postirradiation examination of miniature fuel plates and full-sized fuel elements are summarized. Swelling of the U 3 Si 2 fuel particles is a linear function of the fission density in the particle to well beyond the fission density achievable in low-enriched fuels. U 3 Si 2 particle swelling rate is approximately the same as that of the commonly used UAl/sub x/ fuel particle. The presence of minor amounts of U 3 Si or uranium solid solution in the fuel result in greater, but still acceptable, fuel swelling. Blister threshold temperatures are at least as high as those of currently used fuels. An exothermic reaction occurs near the aluminum melting temperature, but the measured energy releases were low enough not to substantially worsen the consequences of an accident. U 3 Si 2 -aluminum dispersion fuel with uranium densities up to at least 4.8 Mg/m 3 is a suitable LEU fuel for typical plate-type research and test reactors. 42 refs., 28 figs., 7 tabs

All Small Nuclear RNAs (snRNAs) of the [U4/U6.U5] Tri-snRNP Localize to Nucleoli; Identification of the Nucleolar Localization Element of U6 snRNA

Science.gov (United States)

Gerbi, Susan A.; Lange, Thilo Sascha

2002-01-01

Previously, we showed that spliceosomal U6 small nuclear RNA (snRNA) transiently passes through the nucleolus. Herein, we report that all individual snRNAs of the [U4/U6.U5] tri-snRNP localize to nucleoli, demonstrated by fluorescence microscopy of nucleolar preparations after injection of fluorescein-labeled snRNA into Xenopus oocyte nuclei. Nucleolar localization of U6 is independent from [U4/U6] snRNP formation since sites of direct interaction of U6 snRNA with U4 snRNA are not nucleolar localization elements. Among all regions in U6, the only one required for nucleolar localization is its 3′ end, which associates with the La protein and subsequently during maturation of U6 is bound by Lsm proteins. This 3′-nucleolar localization element of U6 is both essential and sufficient for nucleolar localization and also required for localization to Cajal bodies. Conversion of the 3′ hydroxyl of U6 snRNA to a 3′ phosphate prevents association with the La protein but does not affect U6 localization to nucleoli or Cajal bodies. PMID:12221120

Analysis of an Organisation: A University of the Third Age (U3A), Mornington, Victoria

Science.gov (United States)

Small, Michael

2017-01-01

The purpose of this paper is two fold: to look at Mornington U3A in organisational terms and then look at U3AM as a loosely coupled system. One outcome of the study would be to undertake further analyses of U3As in Victoria to determine the levels of bureaucracy under which each operates. Questions to be asked: are U3As in Victoria operating as…

Short Communication on “In-situ TEM ion irradiation investigations on U{sub 3}Si{sub 2} at LWR temperatures”

Energy Technology Data Exchange (ETDEWEB)

Miao, Yinbin, E-mail: ymiao@anl.gov [Argonne National Laboratory, Lemont, IL 60439 (United States); Harp, Jason [Idaho National Laboratory, Idaho Fall, ID 83415 (United States); Mo, Kun [Argonne National Laboratory, Lemont, IL 60439 (United States); Bhattacharya, Sumit [Northwestern University, Evanston, IL 60208 (United States); Baldo, Peter; Yacout, Abdellatif M. [Argonne National Laboratory, Lemont, IL 60439 (United States)

2017-02-15

The radiation-induced amorphization of U{sub 3}Si{sub 2} was investigated by in-situ transmission electron microscopy using 1 MeV Kr ion irradiation. Both arc-melted and sintered U{sub 3}Si{sub 2} specimens were irradiated at room temperature to confirm the similarity in their responses to radiation. The sintered specimens were then irradiated at 350 °C and 550 °C up to 7.2 × 10{sup 15} ions/cm{sup 2} to examine their amorphization behavior under light water reactor (LWR) conditions. U{sub 3}Si{sub 2} remains crystalline under irradiation at LWR temperatures. Oxidation of the material was observed at high irradiation doses.

Hydrogen absorption properties of U6Mn and U6Ni

International Nuclear Information System (INIS)

Ito, H.; Yamawaki, M.; Yamamoto, T.

1998-01-01

The hydrogen absorption properties of U, U 6 Mn and U 6 Ni were investigated at hydrogen pressures below 10 5 Pa. The pressure-composition (P-C) isotherms of U, U 6 Mn and U 6 Ni were obtained and the amounts of absorbed hydrogen for U, U 6 Mn and U 6 Ni were determined to be 3, 16.6 and 16.0 for x in MH x , where M is U, U 6 Mn and U 6 Ni, respectively. The desorption plateau pressures at 573 K decreased in the order: U 6 Mn-H>U 6 Ni-H>U-H. In addition, the results for the amounts of absorbed hydrogen suggests the formation of ternary hydrides U 6 MnH 18 and U 6 NiH 14 . (orig.)

Nitric acid titration in the presence of UO2(NO3)2, Th(NO3)4, U(NO3)4 or Zr(NO3)4

International Nuclear Information System (INIS)

Nakashima, T.; Lieser, K.H.

1986-01-01

Procedures are described for titration of HNO 3 in presence of UO 2 2+ , Th 4+ , U 4+ and Zr 4+ without formation of interfering precipitates. In the first step the hydrolysable ions are masked by addition of complexing agents and in the second step the acid is titrated by NaOH as usual. (orig.)

Temperature effect on the retention of U(VI) by SrTiO{sub 3}; Effet de la temperature sur la retention de U(VI) par SrTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Garcia Rosales, G

2007-11-15

The purpose of this research was the study of the interaction mechanisms between U(VI) ions and SrTiO{sub 3} surfaces versus pH and temperature: 25, 50, 75 and 90 C. Firstly, a physicochemical characterization was realized (DRX, MEB, FTIR) and the surface site density was determined. The potentiometric titration data were simulated, for each temperature, using the constant capacitance model and taking into account bath protonation of the {identical_to}Sr-OH surface sites and deprotonation of the {identical_to}Ti-OH ones (one pK{sub a} model). Both enthalpy and entropy changes, corresponding to the surface acid-base reactions, were evaluated using the van't Hoff relation. U(VI) was sorbed onto SrTiO{sub 3} powder in the pH range 0.5-5.0 with an U(VI) initial concentration 1.10{sup -4} M. By TRLIFS two U(VI) complexes were detected associated with two lifetime values (60 {+-} 5 and 12 {+-} 2 {mu}s at 25 C). The sorption edges were simulated using FITEQL 4.0 software. The surface complexation constants of the system SrTiO{sub 3}/U(VI) between 25 and 90 C temperature range were thus obtained with the constant capacitance model considering two reactive surface sites. It reveals that two types of surface complex, namely [({identical_to}SrOH)({identical_to}TiOH)UO{sub 2}]{sup 2+} and [({identical_to}TiOH)({identical_to}TiO)UO{sup 2+}]{sup 2+}, are needed to properly describe the experimental observations. By application of the van't Hoff equation, Delta{sub R}S{sup 0} and Delta{sub R}H{sup 0} were obtained, which indicated an endothermic sorption process. Finally, an energy transfer study was realised by TRLIFS. The energy transfer between Tb{sup 3+} and Eu{sup 3+} ions sorbed onto SrTiO{sub 3} powders were investigated. The results showed that the energy transfer between Tb{sup 3+} and Eu{sup 3+} is a non-radiative process and follows a dipole-dipole type interaction. A formalism based on the Dexter and the Inokuti-Hirayama theories was used to calculate the

Theoretical investigation of the Omega(g,u)(+/-) states of K2 dissociating adiabatically up to K(4p 2P(3/2)) + K(4p 2P(3/2)).

Science.gov (United States)

Jraij, A; Allouche, A R; Magnier, S; Aubert-Frécon, M

2009-06-28

A theoretical investigation of the electronic structure of the K(2) molecule, including spin-orbit effects, has been performed. Potential energies have been calculated over a large range of R up to 75a(0) for the 88 Omega(g,u)(+/-) states dissociating adiabatically into the limits up to K(4p (2)P(3/2))+K(4p (2)P(3/2)). Equilibrium distances, transition energies, harmonic frequencies, as well as depths for wells and heights for barriers are reported for all of the bound Omega(g,u)(+/-) states. Present ab initio calculations are shown to be able to reproduce quite accurately the small structures (wells and barrier) displayed at very long-range (R>50a(0)) by the (2,3)1(u) and (2)0(g)(-) purely long-range states. As the present data could help experimentalists, we make available extensive tables of energy values versus internuclear distances in our database at the web address http://www-lasim.univ-lyon1.fr/spip.php?rubrique99.

Magnetic correlations in UPt3 and U/sub 1-x/Th/sub x/Pt3

International Nuclear Information System (INIS)

Aeppli, G.; Bucher, E.; Goldman, A.I.; Shirane, G.; Broholm, C.; Kjems, J.K.

1988-01-01

Neutron scattering experiments on UPt 3 and U/sub 1-x/Th/sub x/Pt 3 are reviewed. At relatively high energies (/approximately/5 MeV), the magnetic fluctuation spectrum is modulated by the structure factor derived from short-range antiferromagnetic correlations where the two U ions in each unit cell are oppositely polarized. In contrast, at low energies (≤ 1 MeV), the diffuse inelastic scattering is associated with antiferromagnetic correlations where the unit cell is doubled. Nominally pure UPt 3 exhibits magnetic order with the wavevector corresponding to this doubling and a static moment of 0.02 +- 0.01 μ/sub B/. (U/sub 1-x/Th/sub x/)Pt 3 with x ≅ 0.05 exhibits ordering of the same type, but with a much larger static moment, 0.65 +- 0.1 μ/sub B/. Neutron scattering measurements on UPt 3 with implications for superconductivity are surveyed. 23 refs., 7 figs

Thermal compatibility of U-2wt.%Mo and U-10wt.%Mo fuel prepared by centrifugal atomization for high density research reactor fuels

International Nuclear Information System (INIS)

Kim Ki Hwan; Lee Don Bae; Kim Chang Kyu; Kuk Il Hyun; Hofman, G.E.

1997-01-01

Research on the intermetallic compounds of uranium was revived in 1978 with the decision by the international research reactor community to develop proliferation-resistant fuels. The reduction of 93% 235 U (HEU) to 20% 235 U (LEU) necessitates the use of higher U-loading fuels to accommodate the addition 238 U in the LEU fuels. While the vast majority of reactors can be satisfied with U 3 Si 2 -Al dispersion fuel, several high performance reactors require high loadings of up to 8-9 g U cm -3 . Consequently, in the renewed fuel development program of the Reduced Enrichment for Research and Test Reactors (RERTR) Program, attention has shifted to high density uranium alloys. Early irradiation experiments with uranium alloys showed promise of acceptable irradiation behavior, if these alloys can be maintained in their cubic γ-U crystal structure. It has been reported that high density atomized U-Mo powders prepared by rapid cooling have metastable isotropic γ-U phase saturated with molybdenum, and good γ-U phase stability, especially in U-10wt.%Mo alloy fuel. If the alloy has good thermal compatibility with aluminium, and this metastable gamma phase can be maintained during irradiation, U-Mo alloy would be a prime candidate for dispersion fuel for research reactors. In this paper, U-2w.%Mo and U-10w.%Mo alloy powder which have high density (above 15 g-U/cm 3 ), are prepared by centrifugal atomization. The U-Mo alloy fuel meats are made into rods extruding the atomized powders. The characteristics related to the thermal compatibility of U-2w.%Mo and U-10w.%Mo alloy fuel meat at 400 o C for time up to 2000 hours are examined. (author)

Interdiffusion between U(Mo,Pt) or U(Mo,Zr) and Al or Al A356 alloy

International Nuclear Information System (INIS)

Komar Varela, C.; Mirandou, M.; Arico, S.; Balart, S.; Gribaudo, L.

2009-01-01

Solid state reactions in chemical diffusion couples U-7 wt.%Mo-0.9 wt.%Pt/Al at 580 deg. C and U-7 wt.%Mo-0.9 wt.%Pt/Al A356 alloy, U-7 wt.%Mo-1 wt.%Zr/Al and U-7 wt.%Mo-1 wt.%Zr/Al A356 alloy at 550 deg. C were characterized. Results were obtained from optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The UAl 3, UAl 4 and Al 20 Mo 2 U phases were identified in the interaction layers of γU(Mo,Pt)/Al and γU(Mo,Zr)/Al diffusion couples. Al 43 Mo 4 U 6 ternary compound was also identified in γU(Mo,Zr)/Al due to the decomposition of γU(Mo,Zr) phase. The U(Al,Si) 3 and U 3 Si 5 phases were identified in the interaction layers of γU(Mo,Pt)/Al A356 and γU(Mo,Zr)/Al A356 diffusion couples. These phases are formed due to the migration of Si to the interaction layer. In the diffusion couple U(Mo,Zr)/Al A356, Zr 5 Al 3 phase was also identified in the interaction layer. The use of synchrotron radiation at Brazilian Synchrotron Light Laboratory (LNLS, CNPq, Campinas, Brazil) was necessary to achieve a complete crystallographic characterization.

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.

3 CFR 8357 - Proclamation 8357 of April 3, 2009. Education and Sharing Day, U.S.A., 2009

Science.gov (United States)

2010-01-01

... economy and to contribute to their communities. Commemorating Education and Sharing Day, U.S.A., we... Sharing Day, U.S.A., 2009 8357 Proclamation 8357 Presidential Documents Proclamations Proclamation 8357 of April 3, 2009 Proc. 8357 Education and Sharing Day, U.S.A., 2009By the President of the United States of...

Determination of 11 trace elements in U3O8 CRMs by ICP-AES

International Nuclear Information System (INIS)

Liu Husheng

1994-01-01

The TBP extractant-containing resin and extraction chromatography technique were used to separate 11 trace elements in U 3 O 8 CRMs. The sample was separated at a flow rate of 0.5 mL/min with 3 mol/L HNO 3 as medium. A model 975 ICP direct reading spectrometer was used to determine the trace elements of Ca, Cd, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb and Sn in U 3 O 8 CRMs. The lowest quantitatively determinable concentration of impurities in U 3 O 8 CRMs are 0.02-1.6 μg/g. The RSD is less than 10%. The proposed method provides excellent and accurate analytical data for the U 3 O 8 samples prepared as certified reference materials (CRMs)

The Arabidopsis splicing factors, AtU2AF65, AtU2AF35, and AtSF1 shuttle between nuclei and cytoplasms

KAUST Repository

Park, Hyo-Young

2017-04-21

The Arabidopsis splicing factors, AtU2AF65, AtU2AF35, and AtSF1 shuttle between nuclei and cytoplasms. These proteins also move rapidly and continuously in the nuclei, and their movements are affected by ATP depletion. The U2AF65 proteins are splicing factors that interact with SF1 and U2AF35 proteins to promote U2snRNP for the recognition of the pre-mRNA 3\\' splice site during early spliceosome assembly. We have determined the subcellular localization and movement of these proteins\\' Arabidopsis homologs. It was found that Arabidopsis U2AF65 homologs, AtU2AF65a, and AtU2AF65b proteins interact with AtU2AF35a and AtU2AF35b, which are Arabidopsis U2AF35 homologs. We have examined the mobility of these proteins including AtSF1 using fluorescence recovery after photobleaching and fluorescence loss in photobleaching analyses. These proteins displayed dynamic movements in nuclei and their movements were affected by ATP depletion. We have also demonstrated that these proteins shuttle between nuclei and cytoplasms, suggesting that they may also function in cytoplasm. These results indicate that such splicing factors show very similar characteristics to their human counterparts, suggesting evolutionary conservation.

The Arabidopsis splicing factors, AtU2AF65, AtU2AF35, and AtSF1 shuttle between nuclei and cytoplasms

KAUST Repository

Park, Hyo-Young; Lee, Keh Chien; Jang, Yun Hee; Kim, SoonKap; Thu, May Phyo; Lee, Jeong Hwan; Kim, Jeong-Kook

2017-01-01

The Arabidopsis splicing factors, AtU2AF65, AtU2AF35, and AtSF1 shuttle between nuclei and cytoplasms. These proteins also move rapidly and continuously in the nuclei, and their movements are affected by ATP depletion. The U2AF65 proteins are splicing factors that interact with SF1 and U2AF35 proteins to promote U2snRNP for the recognition of the pre-mRNA 3' splice site during early spliceosome assembly. We have determined the subcellular localization and movement of these proteins' Arabidopsis homologs. It was found that Arabidopsis U2AF65 homologs, AtU2AF65a, and AtU2AF65b proteins interact with AtU2AF35a and AtU2AF35b, which are Arabidopsis U2AF35 homologs. We have examined the mobility of these proteins including AtSF1 using fluorescence recovery after photobleaching and fluorescence loss in photobleaching analyses. These proteins displayed dynamic movements in nuclei and their movements were affected by ATP depletion. We have also demonstrated that these proteins shuttle between nuclei and cytoplasms, suggesting that they may also function in cytoplasm. These results indicate that such splicing factors show very similar characteristics to their human counterparts, suggesting evolutionary conservation.

Predicted irradiation behavior of U3O8-Al dispersion fuels for production reactor applications

International Nuclear Information System (INIS)

Cronenberg, A.W.; Rest, J.

1990-01-01

Candidate fuels for the new heavy-water production reactor include uranium/aluminum alloy and U 3 O 8 -Al dispersion fuels. The U 3 O 8 -Al dispersion fuel would make possible higher uranium loadings and would facilitate uranium recycle. Research efforts on U 3 O 8 -Al fuel include in-pile irradiation studies and development of analytical tools to characterize the behavior of dispersion fuels at high-burnup. In this paper the irradiation performance of U 3 O 8 -Al is assessed using the mechanistic Dispersion Analysis Research Tool (DART) code. Predictions of fuel swelling and alteration of thermal conductivity are presented and compared with experimental data. Calculational results indicate good agreement with available data where the effects of as-fabricated porosity and U 3 O 8 -Al oxygen exchange reactions are shown to exert a controlling influence on irradiation behavior. The DART code is judged to be a useful tool for assessing U 3 O 8 -Al performance over a wide range of irradiation conditions

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

International Nuclear Information System (INIS)

Kawano, Toshihiko; Matsunobu, Hiroyuki; Murata, Toru

2000-02-01

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

Postirradiation examination of a low enriched U3Si2-Al fuel element manufactured and irradiated at Batan, Indonesia

International Nuclear Information System (INIS)

Suripto, A.; Sugondo, S.; Nasution, H.

1994-01-01

The first low-enriched U 3 Si 2 -Al dispersion plate-type fuel element produced at the Nuclear Fuel Element Center, BATAN, Indonesia, was irradiated to a peak 235 U burnup of 62%. Postirradiation examinations performed to data shows the irradiation behavior of this element to be similar to that of U 3 Si 2 -Al plate-type fuel produced and tested at other institutions. The main effect of irradiation on the fuel plates is a thickness increase of 30--40 μm (2.5-3.0%). This thickness increase is almost entirely due to the formation of a corrosion layer (Boehmite). The contribution of fuel swelling to the thickness increase is rather small (less than 10 μm) commensurate with the burnup of the fuel and the relatively moderate as-fabricated fuel volume fraction of 27% in the fuel meat

CNEA/ANL collaboration program to develop an optimized version of DART validation and assessment by means of U{sub 3}Si{sub x} and U{sub 3}O{sub 8-}Al dispersed CNEA miniplate irradiation behavior.

Energy Technology Data Exchange (ETDEWEB)

Solis, D.

1998-10-16

The DART code is based upon a thermomechanical model that can predict swelling, recrystallization, fuel-meat interdiffusion and other issues related with MTR dispersed FE behavior under irradiation. As a part of a common effort to develop an optimized version of DART, a comparison between DART predictions and CNEA miniplates irradiation experimental data was made. The irradiation took place during 1981-82 for U3O8 miniplates and 1985-86 for U{sub 3}Si{sub x} at Oak Ridge Research Reactor (ORR). The microphotographs were studied by means of IMAWIN 3.0 Image Analysis Code and different fission gas bubbles distributions were obtained. Also it was possible to find and identify different morphologic zones. In both kinds of fuels, different phases were recognized, like particle peripheral zones with evidence of Al-U reaction, internal recrystallized zones and bubbles. A very good agreement between code prediction and irradiation results was found. The few discrepancies are due to local, fabrication and irradiation uncertainties, as the presence of U{sub 3}Si phase in U{sub 3}Si{sub 2} particles and effective burnup.

Uranium ("2"3"8U)-induced ROS and cell cycle perturbations, antioxidant responses and erythrocyte nuclear abnormalities in the freshwater iridescent shark fish Pangasius sutchi

International Nuclear Information System (INIS)

Annamalai, Sathesh Kumar; Arunachalam, Kantha Deivi

2017-01-01

Highlights: • Exposure to "2"3"8U deteriorated the antioxidant defenses like SOD, CAT and LPO. • Flow cytometric analysis revealed the increase in G2/M phase and S phase. • Micronucleus frequencies increased with Increased "2"3"8U exposure and time. • Exposure to waterborne "2"3"8U induces both chemical and radiotoxicity in P. sutchi. • ROS-mediated "2"3"8U toxic mechanism and the antioxidant responses has been proposed. - Abstract: The strategic plan of this study is to analyze any possible radiological impact on aquatic organisms from forthcoming uranium mining facilities around the Nagarjuna Sagar Dam in the future. The predominantly consumed and dominant fish species Pangasius sutchi, which is available year-round at Nagarjuna Sagar Dam, was selected for the study. To comprehend the outcome and to understand the mode of action of "2"3"8U, the fish species Pangasius sutchi was exposed to ¼ and ½ of the LC_5_0 doses of waterborne "2"3"8U in a static system in duplicate for 21 days. Blood and organs, including the gills, liver, brain and muscles, were collected at different time periods—0 h, 24 h, 48 h, 72 h, 96 h, 7, days 14 days and 21 days—using ICP-MS to determine the toxic effects of uranium and the accumulation of "2"3"8U concentrations. The bioaccumulation of "2"3"8U in P. sutchi tissues was dependent on exposure time and concentration. The accumulation of uranium was, in order of magnitude, measured as gills > liver > brain > tissue, with the highest accumulation in the gills. It was observed that exposure to "2"3"8U significantly reduced antioxidant enzymes such as superoxide dismutase, catalase, and lipid peroxidase. The analysis of DNA fragmentation by comet assay and cell viability by flow cytometry was performed at different time intervals. DNA histograms by flow cytometry analysis revealed an increase in the G2/M phase and the S phase. The long-term "2"3"8U exposure studies in fish showed increasing micronucleus frequencies in

Sorption of U(VI) in surfaces of SrTiO3

International Nuclear Information System (INIS)

Ortiz O, H.B.; Ordonez R, E.; Fernandez V, S.M.

2004-01-01

In this work is presented the physico chemical characterization and evaluation of those surface properties and of sorption of U on the SrTiO 3 like possible candidate for contention barrier in the deep geological confinement. The made studies showed that the SrTiO 3 presents maximum levels of sorption of positive nature species (mainly UO 2 2+ and UO 2 NO 3 + ). (Author)

Site selective excitation spectroscopy of CsCdBr sub 3 :U sup 3 sup +

CERN Document Server

Yin Min

2002-01-01

The CsCdBr sub 3 :U sup 3 sup + crystal was grown by the Bridgman technique from the starting materials CsBr, CdBr sub 2 and UBr sub 4. X-ray check showed that the sample crystallized in the CsNiBr sub 3 structure. Under selective excitation at low temperature, the emission spectra and the fluorescence decay curve were measured and discussed

Yeast endoribonuclease stimulated by Novikoff Hepatoma small nuclear RNAS U1 and U2

International Nuclear Information System (INIS)

Stevens, A.

1982-01-01

Using [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) from yeast as a substrate, an endoribonuclease has been detected in enzyme fractions derived from a high salt wash of ribonucleoprotein particles of Saccharomyces cerevisiae. The [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) seems to be a preferred substrate since other polyribonucleotides are hydrolyzed more slowly, if at all. The enzyme is inhibited by ethidium bromide, but fully double-stranded polyribonucleotides are not hydrolyzed. The hydrolysis of [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) is stimulated about 2.5-fold by the addition of small nuclear RNAs U1 and U2 of Novikoff hepatoma cells. Results show that the stimulation involves an interaction of the labeled RNA with the small nuclear RNA

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.

28 CFR 45.3 - Disciplinary proceedings under 18 U.S.C. 207(j).

Science.gov (United States)

2010-07-01

.... 207(j). 45.3 Section 45.3 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) EMPLOYEE RESPONSIBILITIES § 45.3 Disciplinary proceedings under 18 U.S.C. 207(j). (a) Upon a determination by the Assistant... authorized by 18 U.S.C. 207(j), or subjected to other appropriate disciplinary action under that statute. The...

The effect of symmetry on the U L3 NEXAFS of octahedral coordinated uranium(vi)

Energy Technology Data Exchange (ETDEWEB)

Bagus, Paul S. [Department of Chemistry, University of North Texas, Denton, Texas 76203-5017, USA; Nelin, Connie J. [Consultant, Austin, Texas 78730, USA; Ilton, Eugene S. [Pacific Northwest National Laboratory, Richland, Washington 99352, USA

2017-03-21

We describe a detailed theoretical analysis of how distortions from ideal cubic or Oh symmetry affect the shape, in particular the width, of the U L3-edge NEXAFS for U(VI) in octahedral coordination. The full-width-half-maximum (FWHM) of the L3-edge white line decreases with increasing distortion from Oh symmetry due to the mixing of symmetry broken t2g and eg components of the excited state U(6d) orbitals. The mixing is allowed because of spin-orbit splitting of the ligand field split 6d orbitals. Especially for higher distortions, it is possible to identify a mixing between one of the t2g and one of the eg components, allowed in the double group representation when the spin-orbit interaction is taken into account. This mixing strongly reduces the ligand field splitting, which, in turn, leads to a narrowing of the U L3 white line. However, the effect of this mixing is partially offset by an increase in the covalent anti-bonding character of the highest energy spin-orbit split eg orbital. At higher distortions, mixing overwhelms the increasing anti-bonding character of this orbital which leads to an accelerated decrease in the FWHM with increasing distortion. Additional evidence for the effect of mixing of t2g and eg components is that the FWHM of the white line narrows whether the two axial U-O bond distances shorten or lengthen. Our ab initio theory uses relativistic wavefunctions for cluster models of the structures; empirical or semi-empirical parameters were not used to adjust prediction to experiment. A major advantage is that it provides a transparent approach for determining how the character and extent of the covalent mixing of the relevant U and O orbitals affect the U L3-edge white line.

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)

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)

Stabilization of He2(A(sup 3)Sigma(sub u)(+)) molecules in liquid helium by optical pumping for vacuum UV laser

Science.gov (United States)

Zmuidzinas, J. S. (Inventor)

1978-01-01

A technique is disclosed for achieving large populations of metastable spin-aligned He2(a 3 Sigma u +) molecules in superfluid helium to obtain lasing in the vacuum ultraviolet wavelength regime around 0.0800 micron m by electronically exciting liquid (superfluid) helium with a comparatively low-current electron beam and spin aligning the metastable molecules by means of optical pumping with a modestly-powered (100mW) circularly-polarized continuous wave laser operating at, for example, 0.9096 or 0.4650 micron m. Once a high concentration of spin-aligned He2 (a 3 Sigma u +) is achieved with lifetimes of a few milliseconds, a strong microwave signal destroys the spin alignment and induces a quick collisional transition of He2 (a 3 Sigma u +) molecules to the a 1 Sigma u + state and thereby a lasing transition to the X 1 Sigma g + state.

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

Corrective action baseline report for underground storage tanks 0439-U, 0440-U, 2073-U, 2074-U, and 2075-U at the East End Fuel Station, Buildings 9754 and 9754-2, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, Facility ID No. 0-010117

International Nuclear Information System (INIS)

1994-01-01

The purpose of this report is to provide baseline geochemical and hydrogeologic data relative to corrective action for underground storage tanks (USTs) 0439-U, 0440-U, 2073-U, 2074-U, and 2075-U at the East End Fuel Station, Buildings 9754 and 9754-2 at the Oak Ridge Y-12 Plant. Progress in support of corrective action at the East End Fuel Station has included monitoring well installation, tank removal, and baseline groundwater sampling and analysis. This document represents the baseline report for corrective action at the East End Fuel Station and is organized into three sections. Section 1 presents introductory information relative to the site, including the regulatory initiative, site description, and progress to date. Section 2 includes a summary of additional monitoring well installation activities, the results of baseline groundwater sampling, a summary of tank removal activities, and the results of confirmatory soil sampling performed during tank removal. Section 3 presents the baseline hydrogeology and planned zone of influence for groundwater remediation

Rare-Earth Oxide Ion (Tm3+, Ho3+, and U3+) Doped Glasses and Fibres for 1.8 to 4 Micrometer Coherent and Broadband Sources

Science.gov (United States)

2006-07-24

oxide ( TeO2 ) , fluorine- containing silicate (SiOF2) and germanate (GeOF2) glass hosts for each dopant by characterising the spectroscopic properties...Earth Oxide Ion (Tm3+, Ho3+, And U3+) Doped Glasses And Fibres For 1.8 To 4 Micrometer Coherent And Broadband Sources 5c. PROGRAM ELEMENT NUMBER 5d...Rare-earth oxide ion (Tm3+, Ho3+, and U3+) doped glasses and fibres for 1.8 to 4 micrometer coherent and broadband sources Report prepared

Study of the U3O8-Al thermite reaction and strength of reactor fuel tubes

International Nuclear Information System (INIS)

Peacock, H.B.

1983-08-01

Heating tests using 53 wt % U 3 O 8 -Al pellets show that an exothermic reaction occurs between 875 and 1000 0 C and takes 10 to 20 seconds to reach maximum temperature. The maximum temperature is a function of particle size of the U 3 O 8 with large particles exhibiting lower peak temperatures. The calculated energy release was 123 cal/g of U 3 O 8 -aluminum fuel. Tests using aluminum clad outer fuel tube sections gave lower peak temperatures than for pellets. No violent reactions occurred. The results are reasonably consistent with recent reported data indicating that the exothermic U 3 O 8 -Al reaction is not an important energy source. The compressive and tensile strengths of U 3 O 8 tubes above 660 0 C are low. In compression, sections with 2 psi average axial stress failed at 917 0 C, while sections with 7 psi failed at 669 0 C. Tubes with U-Al alloy cores failed at about 670 0 C with no applied load. The stresses in fuel tubes during a reactor transient may range up to several hundred psi and are less than 7 psi only in the upper part of the fuel tube

U and Th background contents in the Crimea rocks, Th/U ratio interpretation

International Nuclear Information System (INIS)

Gerasimov, Yu.G.; Voronova, M.A.; AN Ukrainskoj SSR, Kiev. Inst. Geologicheskikh Nauk)

1981-01-01

Radiogeochemical sampling of rocks in the Crimea is carried out. Analyses for U are made by luminescence method, while for Th by X-ray one. About 1000 samples, characterizing the whole stratigraphical cross section except Pz of crystalline rocks, have been analyzed. Low background values for U and Th are established; U content of 1.3-2.3 g/kg and Th content of 7.0-9.0 g/kg are predominant, that is lower than the clark of the earth crust. The distribution of radioelements in stepper and submontane Crimea is gradual, while in mountain part - the mosaic one. Results of Th/U ratios interpretation are presented [ru

Effect of the fabrication process on fatigue performance of U3Si2 fuel plate with sandwich structure

International Nuclear Information System (INIS)

Wang Xishu; Li Shuangshou; Wang Qingyuan; Xu Yong

2005-01-01

U 3 Si 2 -Al fuel plate is one of the dispersion fuel structure materials recently developed and widely used in research reactors. The mechanical properties of this structural material, especially the fatigue performance, are strongly dependent on its fabrication process. To investigate the effects of these processing technologies, the fatigue tests for the different specimens were carried out. The S-N curves indicate that the fabrication processing technologies of U 3 Si 2 fuel plate, such as the addition of U 3 Si 2 particles into aluminum powder to form the fuel meat, holding and rolling the processes of meat and cladding of 6061-Al alloy, plays an important role in improving the mechanical properties and fatigue performance of this fuel plate. In addition, some factors that influence the crack initiation and propagation are summarized based on the fatigue images that are in situ observations with SEM. The critical criterion for fatigue damage is proposed based on the fatigue data of the structural material, which were obtained at the different conditions

Joint U. S. --U. S. S. R. test of U. S. MHD electrode systems in U. S. S. R. U-02 MHD facility (phase I). Final report

Energy Technology Data Exchange (ETDEWEB)

Hosler, W R [ed.

1976-01-01

The first (Phase I) joint U.S.-U.S.S.R. test of U.S. electrode materials was carried out in Moscow between September 25 and October 8, 1975 in the Soviet U-02 MHD facility. The test procedure followed closely a predetermined work plan designed to test five different zirconia based materials and the cathode and anode electrode wall modules under MHD operating conditions. The materials which were selected were 88Zr0/sub 2/-12Y/sub 2/0/sub 3/, 82Zr0/sub 2/-18Ce02, 50Zr0/sub 2/-50Ce0/sub 2/, 25Zr0/sub 2/-75Ce0/sub 2/ and 20Zr0/sub 2/-78Ce0/sub 2/-2Ta/sub 2/0/sub 5/. The electrode modules were constructed by Westinghouse Research and Development Laboratory. Each of the five electrode materials had four different current densities established between the anode and cathode during the experiment which lasted a total of 127 hours. There were four main phases in the test schedule: (1) start-up of the channel over a specific heating period. No seed (K/sub 2/C0/sub 3/) introduction - 18 hours. (2) Electrical tests at operating temperature to investigate electro-physical characteristics of the channel and electrodes - 6 hours. (3) Operating life test - 94 hours. (4) Shut-down of the channel over a specific cool down period - 9 hours. All except six electrode pairs performed satisfactorily during the entire test. These were the pairs which were designated to carry maximum or near maximum current density. Five pairs failed early in the life test and the sixth pair failed in the last several hours. Failure was not due to the electrode materials, however, but due to lead-out melting caused by joule heating in the platinum wires. The U-02 facility is described and the operational parameters are given for each phase of the test. The electrode and insulating walls are described and the appropriate parameters that are used to predict the performance of the module are given.

Uranium metalla-allenes with carbene imido R_2C=U"I"V=NR' units (R=Ph_2PNSiMe_3; R'=CPh_3): alkali-metal-mediated push-pull effects with an amido auxiliary

International Nuclear Information System (INIS)

Lu, Erli; Tuna, Floriana; Kaltsoyannis, Nikolas; Liddle, Stephen T.; Lewis, William

2016-01-01

We report uranium(IV)-carbene-imido-amide metalla-allene complexes [U(BIPM"T"M"S)(NCPh_3)(NHCPh_3)(M)] (BIPM"T"M"S=C(PPh_2NSiMe_3)_2; M=Li or K) that can be described as R_2C=U=NR' push-pull metalla-allene units, as organometallic counterparts of the well-known push-pull organic allenes. The solid-state structures reveal that the R_2C=U=NR' units adopt highly unusual cis-arrangements, which are also reproduced by gas-phase theoretical studies conducted without the alkali metals to remove their potential structure-directing roles. Computational studies confirm the double-bond nature of the U=NR' and U=CR_2 interactions, the latter increasingly attenuated by potassium then lithium when compared to the hypothetical alkali-metal-free anion. Combined experimental and theoretical data show that the push-pull effect induced by the alkali metal cations and amide auxiliary gives a fundamental and tunable structural influence over the C=U"I"V=N units. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Quantification and isotope ratio measurement of boron in U3Si2 by inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Saha, Abhijit; Deb, S.B.; Nagar, B.K.; Saxena, M.K.; Samanta, Papu

2014-01-01

An analytical methodology was developed for precise quantification and isotope ratio measurement of boron in U 3 Si 2 matrix by using ICP-MS after matrix separation. The analytical technique was validated by recovery studies employing standard addition method and the accuracy in isotope ratio measurement was improved by correcting the bias factor after analyzing NIST SRM951. The quantification of B in the three U 3 Si 2 samples was found in the range of 2.32-3.90 μg g -1 with a maximum standard deviation of 3%. The 10 B/ 11 B value in the three samples was found to be 0.2455±0.0042, 0.2451±0.0036 and 0.2452±0.0041. (author)

Mianningite, (□,Pb,Ce,Na) (U"4"+,Mn,U"6"+) Fe"3"+_2(Ti,Fe"3"+)_1_8O_3_8, a new member of the crichtonite group from Maoniuping REE deposit, Mianning county, southwest Sichuan, China

International Nuclear Information System (INIS)

Ge, Xiangkun; Fan, Guang; Chen, Zhangru; Ai, Yujie; Li, Guowu

2017-01-01

Mianningite (IMA 2014-072), ideally (□,Pb,Ce,Na)(U"4"+,Mn,U"6"+) Fe"3"+_2(Ti,Fe"3"+)_1_8O_3_8, is a new member of the crichtonite group from the Maoniuping REE deposit, Mianning county, Sichuan province, China. It was found in fractures of lamprophyre veins and in the contact between lamprophyre and a later quartz-alkali feldspar syenite dyke with REE mineralization, and is named after its type locality. Associated minerals are microcline, albite, quartz, iron-rich phlogopite, augite, muscovite, calcite, baryte, fluorite, epidote, pyrite, magnetite, hematite, galena, hydroxylapatite, titanite, ilmenite, rutile, garnet-group minerals, zircon, allanite-(Ce), monazite-(Ce), bastnaesite-(Ce), parisite-(Ce), maoniupingite-(Ce), thorite, pyrochlore-group minerals and chlorite. Mianningite occurs as opaque subhedral to euhedral tabular crystals, up to 1-2 mm in size, black in color and streak, and with a submetallic luster. Mianningite is brittle, with a conchoidal fracture. Its average micro-indentation hardness is 83.8 kg/mm"2 (load 0.2 kg), which is equivalent to ∝6 on the Mohs hardness scale. Its measured and calculated densities are 4.62 (8) g/cm"3 and 4.77 g/cm"3, respectively. Under reflected light, mianningite is grayish white, with no internal reflections. It appears isotropic and exhibits neither bireflectance nor pleochroism. The empirical formula, calculated on the basis of 38 O atoms per formula unit (apfu), is [□_0_._3_2_2(Pb_0_._2_1_5Ba_0_._0_3_7Sr_0_._0_3_6Ca_0_._0_1_0)_Σ_0_._2_9_8(Ce_0_._1_2_8La_0_._0_7_7Nd_0_._0_1_2)_Σ_0_._2_1_7 (Na_0_._1_2_7K_0_._0_3_6)_Σ_0_._1_6_3]_Σ_0_1_._0_0_0(U"4"+_0_._4_4_7Mn_0_0_._2_9_3U"6 "+_0_._1_1_2Y_0_._0_9_1Zr_0_._0_2_3Th_0_._0_1_1)_Σ_0_._9_7_7(Fe"3"+_1_._2_2_4Fe"2"+_0_._2_4_3Mg_0_._0_2_3P_0_._0_0_8Si_0_._0_0_6 □_0_._4_9_6)_Σ_2_._0_0_0(Ti_1_2_._4_6_4Fe"3"+_5_._2_9_2V"5"+_0_._1_1_8Nb_0_._0_8_3Al_0_._0_2_6Cr"3"+_0_._0_1_7)_Σ_1_8_._0_0_0O_3_8. Mianningite is trigonal, belongs to the space group R anti 3, and has

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Comparing simulated and theoretical sampling distributions of the U3 person-fit statistic

NARCIS (Netherlands)

Emons, W.H.M.; Meijer, R.R.; Sijtsma, K.

2002-01-01

The accuracy with which the theoretical sampling distribution of van der Flier's person-.t statistic U3 approaches the empirical U3 sampling distribution is affected by the item discrimination. A simulation study showed that for tests with a moderate or a strong mean item discrimination, the Type I

Closure report for underground storage tank 141-R3U1 and its associated underground piping

Energy Technology Data Exchange (ETDEWEB)

Mallon, B.J.; Blake, R.G.

1994-03-01

Underground storage tank UST 141-R3U1 at Lawrence Livermore National Laboratory (LLNL), was registered with the State Water Resources Control Board on June 27, 1984. This tank system consisted of a concrete tank, lined with polyvinyl chloride, and approximately 100 feet of PVC underground piping. UST 141-R3U1 had a capacity of 450 gallons. The underground piping connected three floor drains and one sink inside Building 141 to UST 141-R3U1. The wastewater collected in UST 141-R3U1 contained organic solvents, metals, and inorganic acids. On November 30, 1987, the 141-R3U1 tank system failed a precision tank test. The 141-R3U1 tank system was subsequently emptied and removed from service pending further precision tests to determine the location of the leak within the tank system. A precision tank test on February 5, 1988, was performed to confirm the November 30, 1987 test. Four additional precision tests were performed on this tank system between February 25, 1988, and March 6, 1988. The leak was located where the inlet piping from Building 141 penetrates the concrete side of UST 141-R3U1. The volume of wastewater that entered the backfill and soil around and/or beneath UST 141-R3U1 is unknown. On December 13, 1989, the LLNL Environmental Restoration Division submitted a plan to close UST 141-R3U1 and its associated piping to the Alameda County Department of Environmental Health. UST 141-R3U1 was closed as an UST, and shall be used instead as additional secondary containment for two aboveground storage tanks.

Closure report for underground storage tank 141-R3U1 and its associated underground piping

International Nuclear Information System (INIS)

Mallon, B.J.; Blake, R.G.

1994-03-01

Underground storage tank UST 141-R3U1 at Lawrence Livermore National Laboratory (LLNL), was registered with the State Water Resources Control Board on June 27, 1984. This tank system consisted of a concrete tank, lined with polyvinyl chloride, and approximately 100 feet of PVC underground piping. UST 141-R3U1 had a capacity of 450 gallons. The underground piping connected three floor drains and one sink inside Building 141 to UST 141-R3U1. The wastewater collected in UST 141-R3U1 contained organic solvents, metals, and inorganic acids. On November 30, 1987, the 141-R3U1 tank system failed a precision tank test. The 141-R3U1 tank system was subsequently emptied and removed from service pending further precision tests to determine the location of the leak within the tank system. A precision tank test on February 5, 1988, was performed to confirm the November 30, 1987 test. Four additional precision tests were performed on this tank system between February 25, 1988, and March 6, 1988. The leak was located where the inlet piping from Building 141 penetrates the concrete side of UST 141-R3U1. The volume of wastewater that entered the backfill and soil around and/or beneath UST 141-R3U1 is unknown. On December 13, 1989, the LLNL Environmental Restoration Division submitted a plan to close UST 141-R3U1 and its associated piping to the Alameda County Department of Environmental Health. UST 141-R3U1 was closed as an UST, and shall be used instead as additional secondary containment for two aboveground storage tanks

Closure Plan for Corrective Action Unit 110: Area 3 RWMS U-3ax/bl Disposal Unit, Nevada Test Site, Nevada

International Nuclear Information System (INIS)

Fitzmaurice, T. M.

2000-01-01

This Closure Plan has been prepared for the Area 3 RWMS U-3ax/bl Disposal Unit Corrective Action Unit 110 in accordance with the Federal Facility and Consent Order (Nevada Division of Environmental Protection [NDEP] et al., 1996). The U-3ax/bl is a historic disposal unit within the Area 3 Radioactive Waste Management Site located on the Nevada Test Site (NTS). The unit, which was formed by excavating the area between two subsidence craters (U-3ax and U-3bl), was operationally closed in 1987. The U-3ax/bl disposal unit is scheduled for permanent closure under the Resource Conservation and Recovery Act as a hazardous waste landfill. Existing records indicate that, from July 1968 to December 1987, U-3ax/bl received 2.3 x 10 5 cubic meters (8.12 x 10 6 cubic feet) of waste. NTS nuclear device testing generated approximately 95 percent of the total volume disposed of in U-3ax/bl, the majority of which came from the Waste Consolidation Project (80 percent of the total volume) (Elletson and Johnejack, 1995). Area 3 is located in Yucca Flat, within the northeast quadrant of the NTS. The Yucca Flat watershed is a structurally closed basin encompassing an area of approximately 780 square kilometers (300 square miles). The structural geomorphology of Yucca Flat is typical of the Basin and Range Physiographic Province. Yucca Flat lies in one of the most arid regions of the country. Water balance calculations for Area 3 indicate that it is continuously in a state of moisture deficit. The U-3ax/bl Disposal Unit will be closed in place by installing a Resource Conservation and Recovery Act equivalent cover. Following cover construction a fence will be installed around the cover to prevent accidental damage to the cover. Post-closure monitoring will consist of site inspections to determine the condition of the engineered cover and cover performance monitoring using Time-Domain Reflectometry arrays to monitor moisture migration in the cover. Any identified maintenance and repair

Closure Plan for Corrective Action Unit 110: Area 3 RWMS U-3ax/bl Disposal Unit, Nevada Test Site, Nevada

Energy Technology Data Exchange (ETDEWEB)

T. M. Fitzmaurice

2000-08-01

This Closure Plan has been prepared for the Area 3 RWMS U-3ax/bl Disposal Unit Corrective Action Unit 110 in accordance with the Federal Facility and Consent Order (Nevada Division of Environmental Protection [NDEP] et al., 1996). The U-3ax/bl is a historic disposal unit within the Area 3 Radioactive Waste Management Site located on the Nevada Test Site (NTS). The unit, which was formed by excavating the area between two subsidence craters (U-3ax and U-3bl), was operationally closed in 1987. The U-3ax/bl disposal unit is scheduled for permanent closure under the Resource Conservation and Recovery Act as a hazardous waste landfill. Existing records indicate that, from July 1968 to December 1987, U-3ax/bl received 2.3 x 10{sup 5} cubic meters (8.12 x 10{sup 6} cubic feet) of waste. NTS nuclear device testing generated approximately 95 percent of the total volume disposed of in U-3ax/bl, the majority of which came from the Waste Consolidation Project (80 percent of the total volume) (Elletson and Johnejack, 1995). Area 3 is located in Yucca Flat, within the northeast quadrant of the NTS. The Yucca Flat watershed is a structurally closed basin encompassing an area of approximately 780 square kilometers (300 square miles). The structural geomorphology of Yucca Flat is typical of the Basin and Range Physiographic Province. Yucca Flat lies in one of the most arid regions of the country. Water balance calculations for Area 3 indicate that it is continuously in a state of moisture deficit. The U-3ax/bl Disposal Unit will be closed in place by installing a Resource Conservation and Recovery Act equivalent cover. Following cover construction a fence will be installed around the cover to prevent accidental damage to the cover. Post-closure monitoring will consist of site inspections to determine the condition of the engineered cover and cover performance monitoring using Time-Domain Reflectometry arrays to monitor moisture migration in the cover. Any identified maintenance and

Comparison of U-Pu-Mo, U-Pu-Nb, U-Pu-Ti and U-Pu-Zr alloys; Comparaison des alliages U-Pu-Mo, U-Pu-Nb, U-Pu-Ti, U-Pu-Zr

Energy Technology Data Exchange (ETDEWEB)

Boucher, R; Barthelemy, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1964-07-01

The data concerning the U-Pu, U-Pu-Mo and U-Pu-Nb are recalled. The results obtained with U-Pu-Ti and U-Pu-Zr alloys containing 15-20 per cent Pu and 10 wt. per cent ternary element are reported. The transformation temperatures, the expansion coefficients, the nature of phases, the thermal cycling behaviour have been determined. A list of the principal properties of these different alloys is presented and the possibilities of their use as fast reactor's fuel element are considered. The U-Pu-Ti alloys seem to be quite promising: easiness of fabrication, large thermal stability, excellent behaviour in air, small quantity of zeta phase, temperature of solidus superior to 1100 deg. C. (authors) [French] On rappelle brievement les connaissances acquises sur les alliages U-Pu, U-Pu-Mo et U-Pu-Nb. On presente les resultats obtenus avec les alliages U-Pu-Ti et U-Pu-Zr pour des teneurs de 15 a 20 pour cent de plutonium et 10 pour cent en poids d'element ternaire. On a determine les temperatures de transformation, les coefficients de dilatation, la nature des phases, la conductibilite thermique a 20 deg. C, la tenue au cyclage thermique et diverses autres proprietes. Un tableau resume les principales proprietes des divers alliages. On considere les possibilites d'emploi de ces alliages comme combustibles de reacteur rapide. Les alliages U-Pu-Ti paraissent particulierement interessants: facilite d'elaboration, stabilite thermique etendue, tenue dans l'air excellente, faible quantite de la phase U-Pu zeta, temperature de fusion commencante superieure a 1100 deg. C. (auteurs)

Uncertainty assessing of measure result of tungsten in U3O8 by ICP-AES

International Nuclear Information System (INIS)

Du Guirong; Nie Jie; Tang Lilei

2011-01-01

According as the determining method and the assessing criterion,the uncertainty assessing of measure result of tungsten in U 3 O 8 by ICP-AES is researched. With the assessment of each component in detail, the result shows that u rel (sc)> u rel (c)> u rel (F)> u rel (m) by uncertainty contribution. Other uncertainty is random, calculated by repetition. u rel (sc) is contributed to uncertainty mainly. So the general uncertainty is reduced with strict operation to reduce u rel (sc). (authors)

Observation of the a3Σu+-Χ1Σg+ system of calcium dimer

International Nuclear Information System (INIS)

Gondal, M.A.; Khan, M.A.; Rais, M.H.

1998-01-01

The authors report the observation of collision-induced spectra of calcium dimer in the 680-692 nm region. The spectra were recorded after resonant laser excitation of 4s4p 3 P 1 state of atomic calcium. Here the upper state a 3 Σ u + is populated through collisions. The same spectra were reproduced in a low-current glow discharge in calcium vapor. The assignment of the observed spectral lines was carried out by applying the Dunham-type analysis and the spectra were assigned to the a 3 Σ u + -Χ 1 Σ g + transition of Ca 2 . The existence of a a 3 Σ u + state with v 00 =13850±1 cm -1 and ω e ∼37.6 cm -1 is confirmed

Comparing simulated and theoretical sampling distributions of the U3 person-fit statistic

NARCIS (Netherlands)

Emons, Wilco H.M.; Meijer, R.R.; Sijtsma, Klaas

2002-01-01

The accuracy with which the theoretical sampling distribution of van der Flier’s person-fit statistic U3 approaches the empirical U3 sampling distribution is affected by the item discrimination. A simulation study showed that for tests with a moderate or a strong mean item discrimination, the Type I

Evolution of metastable state molecules N2(A3Σu+) in a nanosecond pulsed discharge: A particle-in-cell/Monte Carlo collisions simulation

International Nuclear Information System (INIS)

Gao Liang; Sun Jizhong; Feng Chunlei; Bai Jing; Ding Hongbin

2012-01-01

A particle-in-cell plus Monte Carlo collisions method has been employed to investigate the nitrogen discharge driven by a nanosecond pulse power source. To assess whether the production of the metastable state N 2 (A 3 Σ u + ) can be efficiently enhanced in a nanosecond pulsed discharge, the evolutions of metastable state N 2 (A 3 Σ u + ) density and electron energy distribution function have been examined in detail. The simulation results indicate that the ultra short pulse can modulate the electron energy effectively: during the early pulse-on time, high energy electrons give rise to quick electron avalanche and rapid growth of the metastable state N 2 (A 3 Σ u + ) density. It is estimated that for a single pulse with amplitude of -9 kV and pulse width 30 ns, the metastable state N 2 (A 3 Σ u + ) density can achieve a value in the order of 10 9 cm -3 . The N 2 (A 3 Σ u + ) density at such a value could be easily detected by laser-based experimental methods.

Evolution of metastable state molecules N2(A3 Σu+) in a nanosecond pulsed discharge: A particle-in-cell/Monte Carlo collisions simulation

Science.gov (United States)

Gao, Liang; Sun, Jizhong; Feng, Chunlei; Bai, Jing; Ding, Hongbin

2012-01-01

A particle-in-cell plus Monte Carlo collisions method has been employed to investigate the nitrogen discharge driven by a nanosecond pulse power source. To assess whether the production of the metastable state N2(A3 Σu+) can be efficiently enhanced in a nanosecond pulsed discharge, the evolutions of metastable state N2(A3 Σu+) density and electron energy distribution function have been examined in detail. The simulation results indicate that the ultra short pulse can modulate the electron energy effectively: during the early pulse-on time, high energy electrons give rise to quick electron avalanche and rapid growth of the metastable state N2(A3 Σu+) density. It is estimated that for a single pulse with amplitude of -9 kV and pulse width 30 ns, the metastable state N2(A3 Σu+) density can achieve a value in the order of 109 cm-3. The N2(A3 Σu+) density at such a value could be easily detected by laser-based experimental methods.

Stoichiometry of the U3O8 phase formed during calcination of some uranium compounds

International Nuclear Information System (INIS)

El-Fekey, S.A.; Farah, M.Y.; Rofail, N.H.

1981-01-01

Although recent work has shown U 3 O 8 phase to be the decomposition product obtained after calcining uranyl nitrate, sulphate or ammonium uranate, neither the necessary conditions for obtaining stoichiometric U 3 O 8 nor the details of the reaction have been established. Presence of sulphate or nitrate ions during preparation greatly affects the O/U of the obtained oxides and the physico-chemical properties of uranium tetrafluoride prepared afterwards from it (1-3). The aim of the present investigation was to study the effect of calcination regimes on the stoichiometry of the U 3 O 8 phase produced by the thermal decomposition of uranyl nitrate, sulphate, and ammonium uranate, which was prepared by precipitation from nuclear-pure uranyl sulphate. Stoichiometry of the U 3 O 8 phase formed during calcination of ammonium uranate precipitated from nuclear pure uranyl nitrate solution was reported before (1)

Monte Carlo analysis of the SU(2)xU(1) and U(2) lattice gauge theories at different space-time dimensionalities

International Nuclear Information System (INIS)

Baig, M.; Colet, J.

1986-01-01

Using Monte Carlo simulations the SU(2)xU(1) lattice gauge theory has been analyzed, which is equivalent for the Wilson action to a U(2) theory, at space-time dimensionalities from d=3 to 5. It has been shown that there exist first-order phase transitions for both d=4 and d=5. A monopole-condensation mechanism seems to be responsible for these phase transitions. At d=3 no phase transitions have been detected. (orig.)

Ce2Co3Ge5: a new U2Co3Si5 - type valance fluctuating compound

International Nuclear Information System (INIS)

Layek, Samar; Hossain, Zakir

2010-01-01

Poly crystalline sample of Ce 2 Co 3 Ge 5 have been prepared by arc melting and consequently annealing at 1100 deg C. Rietveld refinement of XRD shows that it crystallize in the orthorhombic U 2 Co 3 Si 5 structure (space group Ibam) with crystal parameters a= 9.802A, b= 11.777A and c= 5.941A and unit cell volume V= 684.8 A 3 The unit cell volume of Ce 2 Co 3 Ge 5 is seen clearly to deviate from that expected on the basis of lanthanide contraction. From susceptibility measurement, effective magnetic moment of this compound μ eff = 0.95 μ B which is lower than magnetic moment free for Ce 3+ ions (2.54 μB) but higher than that of non-magnetic Ce 4+ state (0 μ B ). All these results clearly indicated Ce 2 Co 3 Ge 5 to be a mixed valance compound. (author)

Determination of Uranium In UO2 And U3O8 Powder Using UV-VIS Spectrophotometry

International Nuclear Information System (INIS)

Natalia Adventini; Diah Dwiana Lestiani; Muhayatun; Endah Damastuti

2009-01-01

Lab. TAR PTNBR BATAN - Bandung has been accredited by National Accreditation Committee on May 2 nd , 2006 as a test laboratory with number LP-311-ID, has to maintain its laboratory performance by participating in a proficiency test. In this activity, the determination of uranium in 2 samples of UO 2 with A1 and A2 codes and other 2 samples of U 3 O 8 with B1 and B2 codes using UV-Vis spectrophotometry was carried out. Colouring method was used by reacting thiocyanate ion with the uranyl ion in acidic solution to develop a stable yellow colour of uranyl thiocyanate complex solution and measured at wavelength of 380 nm. The result gave that concentration of uranium in A1, A2, B1 and B2 samples were 77.95; 75.29; 64.58 and 63.69% respectively. The Z-score value for A samples was - 1.99, meanwhile for B samples the Z score value of between laboratory was −1.29 with intra laboratory was -1,09. It meant that Z-score values for both samples were in good category. From this result, it showed that UV-Vis spectrophotometry is one of the several methods that can be used to determine uranium in UO 2 and U 3 O 8 powder. The Lab. TAR’s proficiency test for determination of uranium in UO 2 and U 3 O 8 gave a good result and it was hoped to support BATAN's program in the nuclear fuel field. (author)

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

International Nuclear Information System (INIS)

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

1981-01-01

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

Comparing Simulated and Theoretical Sampling Distributions of the U3 Person-Fit Statistic.

Science.gov (United States)

Emons, Wilco H. M.; Meijer, Rob R.; Sijtsma, Klaas

2002-01-01

Studied whether the theoretical sampling distribution of the U3 person-fit statistic is in agreement with the simulated sampling distribution under different item response theory models and varying item and test characteristics. Simulation results suggest that the use of standard normal deviates for the standardized version of the U3 statistic may…

Quantum algebra U{sub qp}(u{sub 2}) and application to the rotational collective dynamics of the nuclei; Algebre quantique U{sub qp}(u{sub 2}) et application a la dynamique collective de rotation dans les noyaux

Energy Technology Data Exchange (ETDEWEB)

Barbier, R

1995-09-22

This thesis concerns some aspects of new symmetries in Nuclear Physics. It comprises three parts. The first one is devoted to the study of the quantum algebra U{sub qp}(u{sub 2}). More precisely, we develop its Hopf algebraic structure and we study its co-product structure. The bases of the representation theory of U{sub qp}(u{sub 2}) are introduced. On one hand, we construct the finite-dimensional irreducible representations of U{sub qp}(u{sub 2}). On the other hand, we calculate the Clebsch-Gordan coefficients with the projection operator method. To complete our study, we construct some deformed boson mappings of the quantum algebras U{sub qp}(u{sub 2}), U{sub q{sup 2}}(su{sub 2}) and U{sub qp}(u{sub 1,1}). The second part deals with the construction of a new phenomenological model of the non rigid rotator. This model is based on the quantum algebra U{sub qp}(u{sub 2}). The rotational energy and the E2 reduced transition probabilities are obtained. They depend on the two deformation parameters q and p of the quantum algebra. We show how the use of the two-parameter deformation of the algebra U{sub qp}(u{sub 2}) leads to a generalization of the U{sub q}(su{sub 2})-rotator model. We also introduce a new model of the anharmonic oscillator on the basis of the quantum algebra U{sub qp}(u{sub 2}). We show that the system of the U{sub q}(su{sub 2})-rotator and of the anharmonic oscillator can be coupled with the use of the deformation parameters of U{sub qp}(u{sub 2}). A ro-vibration energy formula and expansion `a la` Dunham are obtained. The aim of the last part is to apply our non rigid rotator model to the rotational collective dynamics of the superdeformed nuclei of the A{approx}130 - 150 and A{approx}190 mass regions and deformed nuclei of the actinide and rare earth series. We adjust the free parameters of our model and compare our results with those from four other models of the non rigid rotator. A comparative analysis is given in terms of transition energies.

Semidirect product gauge group [SU(3)cxSU(2)L]xU(1)Y and quantization of hypercharge

International Nuclear Information System (INIS)

Hattori, Chuichiro; Matsunaga, Mamoru; Matsuoka, Takeo

2011-01-01

In the standard model the hypercharges of quarks and leptons are not determined by the gauge group SU(3) c xSU(2) L xU(1) Y alone. We show that, if we choose the semidirect product group [SU(3) c xSU(2) L ]xU(1) Y as its gauge group, the hyperchages are settled to be n/6 mod Z(n=0,1,3,4). In addition, the conditions for gauge-anomaly cancellation give strong constraints. As a result, the ratios of the hypercharges are uniquely determined and the gravitational anomaly is automatically canceled. The standard charge assignment to quarks and leptons can be properly reproduced. For exotic matter fields their hypercharges are also discussed.

A yeast endoribonuclease stimulated by Novikoff hepatoma small nuclear RNAs U1 and U2

International Nuclear Information System (INIS)

Stevens, A.

1982-01-01

Using [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) from yeast as a substrate, an endoribonuclease has been detected in enzyme fractions derived from a high salt wash of ribonucleoprotein particles of Saccharomyces cerevisiae. The [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) seems to be a preferred substrate since other polyribonucleotides are hydrolyzed more slowly, if at all. The enzyme is inhibited by ethidium bromide, but fully double-stranded polyribonucleotides are not hydrolyzed. The hydrolysis of [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) is stimulated about 2.5-fold by the addition of small nuclear RNAs U1 and U2 of Novikoff hepatoma cells. Results show that the stimulation involves an interaction of the labeled RNA with the small nuclear RNA

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)

Ribonucleoprotein organization of eukaryotic RNA. XXXII. U2 small nuclear RNA precursors and their accurate 3' processing in vitro as ribonucleoprotein particles.

Science.gov (United States)

Wieben, E D; Nenninger, J M; Pederson, T

1985-05-05

Biosynthetic precursors of U2 small nuclear RNA have been identified in cultured human cells by hybrid-selection of pulse-labeled RNA with cloned U2 DNA. These precursor molecules are one to approximately 16 nucleotides longer than mature U2 RNA and contain 2,2,7-trimethylguanosine "caps". The U2 RNA precursors are associated with proteins that react with a monoclonal antibody for antigens characteristic of small nuclear ribonucleoprotein particles. Like previously described precursors of U1 and U4 small nuclear RNAs, the pre-U2 RNAs are recovered in cytoplasmic fractions, although it is not known if this is their location in vivo. The precursors are processed to mature-size U2 RNA when cytoplasmic extracts are incubated in vitro at 37 degrees C. Mg2+ is required but ATP is not. The ribonucleoprotein structure of the pre-U2 RNA is maintained during the processing reaction in vitro, as are the 2,2,7-trimethylguanosine caps. The ribonucleoprotein organization is of major importance, as exogenous, protein-free U2 RNA precursors are degraded rapidly in the in vitro system. Two lines of evidence indicate that the conversion of U2 precursors to mature-size U2 RNA involves a 3' processing reaction. First, the reaction is unaffected by a large excess of mature U2 small nuclear RNP, whose 5' trimethylguanosine caps would be expected to compete for a 5' processing activity. Second, when pre-U2 RNA precursors are first stoichiometrically decorated with an antibody specific for 2,2,7-trimethylguanosine, the extent of subsequent processing in vitro is unaffected. These results provide the first demonstration of a eukaryotic RNA processing reaction in vitro occurring within a ribonucleoprotein particle.

Fabrication and microstructural analysis of UN-U{sub 3}Si{sub 2} composites for accident tolerant fuel applications

Energy Technology Data Exchange (ETDEWEB)

Johnson, Kyle D., E-mail: kylej@kth.se; Raftery, Alicia M.; Lopes, Denise Adorno; Wallenius, Janne

2016-08-15

In this study, U{sub 3}Si{sub 2} was synthesized via the use of arc-melting and mixed with UN powders, which together were sintered using the SPS method. The study revealed a number of interesting conclusions regarding the stability of the system – namely the formation of a probable but as yet unidentified ternary phase coupled with the reduction of the stoichiometry in the nitride phase – as well as some insights into the mechanics of the sintering process itself. By milling the silicide powders and reducing its particle size ratio compared to UN, it was possible to form a high density UN-U{sub 3}Si{sub 2} composite, with desirable microstructural characteristics for accident tolerant fuel applications. - Highlights: • U{sub 3}Si{sub 2} fabricated from elemental uranium and silicon through arc melting. • Homogeneity of the silicides assessed through densitometry, XRD, SEM and EDS, chemical etching and optical microscopy. • UN powder fabricated using hydriding-nitriding method. • No phase transformations detected when sintering using silicide particle sizes less than UN particle size. • High density composite (98%TD) fabricated with silicide grain coating using spark plasma sintering at 1450 °C.

Electronic structure of crystalline uranium nitrides UN, U2N3 and UN2: LCAO calculations with the basis set optimization

International Nuclear Information System (INIS)

Evarestov, R A; Panin, A I; Bandura, A V; Losev, M V

2008-01-01

The results of LCAO DFT calculations of lattice parameters, cohesive energy and bulk modulus of the crystalline uranium nitrides UN, U 2 N 3 and UN 2 are presented and discussed. The LCAO computer codes Gaussian03 and Crystal06 are applied. The calculations are made with the uranium atom relativistic effective small core potential by Stuttgart-Cologne group (60 electrons in the core). The calculations include the U atom basis set optimization. Powell, Hooke-Jeeves, conjugated gradient and Box methods are implemented in the author's optimization package, being external to the codes for molecular and periodic calculations. The basis set optimization in LCAO calculations improves the agreement of the lattice parameter and bulk modulus of UN crystal with the experimental data, the change of the cohesive energy due to the optimization is small. The mixed metallic-covalent chemical bonding is found both in LCAO calculations of UN and U 2 N 3 crystals; UN 2 crystal has the semiconducting nature

Study of new U(VI) and Pu(VI) coprecipitation methods for the preparation of (U,Pu)O2

International Nuclear Information System (INIS)

Sanoit, J. de.

1990-01-01

Two U(VI) and Pu(VI) coprecipitation methods have been studied, for the definition of new processes to prepare (U,Pu)O 2 mixed oxides suitable for making MoX fuels or fast breeder reactor fuels. The first system is based on the coprecipitation of a new U(VI), Pu(VI) compound; ammonium uranoplutonate, where as a second system is related to the precipitation of uranyl plutonyl monocarbonate. Experimental conditions to optimize the precipitation and the filtration steps of these two systems have been determined. After calcination under reducing conditions, the mixed oxides obtained are characterized according to different techniques: granulometry, thermogravimetry, solubility in boiling HNO 3 solutions. The properties of such oxides are excellent. The possible processes for preparing (U, Pu)O 2 using these new routes are compared with those actually exploited [fr

Mechanism of disintegration of sup 2 sup 3 sup 8 U nuclei by relativistic projectiles

CERN Document Server

Andronenko, L N; Kravtsov, A V; Solyakin, G E

2002-01-01

The sup 2 sup 3 sup 8 U nuclei disintegration through the 16 GeV energy protons and sup 3 He 2 GeV energy nuclei are considered. The pulse mechanism compensation is proposed to explain the formation of collinear mass fragments accompanied by a large amount of charged secondaries and neutrons flying on the m sub 1 relativistic particle heavy nuclei on the account of the particle emission with the mass m sub 2 > m sub 1

Chemical shift of U L3 edges in different uranium compounds obtained by X-ray absorption spectroscopy with synchrotron radiation

International Nuclear Information System (INIS)

Joseph, D.; Jha, S.N.; Nayak, C.; Bhattacharyya, D.; Babu, P. Venu

2014-01-01

Uranium L 3 X-ray absorption edge was measured in various compounds containing uranium in U 4+ , U 5+ and U 5+ oxidation states. The measurements have been carried out at the Energy Dispersive EXAFS beamline (BL-08) at INDUS-2 synchrotron radiation source at RRCAT, Indore. Energy shifts of ∼ 2-3 eV were observed for U L 3 edge in the U-compounds compared to their value in elemental U. The different chemical shifts observed for the compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on U cation in the above compounds. (author)

Hydrogen absorption-desorption properties of U2Ti

International Nuclear Information System (INIS)

Yamamoto, Takuya; Tanaka, Satoru; Yamawaki, Michio

1990-01-01

Hydrogen absorption-desorption properties of U 2 Ti intermetallic compound was examined over the temperature range of 298 to 973 K and at hydrogen pressures below 10 5 Pa. It absorbs hydrogen up to 7.6 atoms per F.U. (formula unit) by two step reactions and hence each desorption isotherm is separated into two plateau regions. In the first plateau, a newly-found ternary hydride is formed, where the hydrogen concentration, c H , reaches 2.4 H atoms/F.U. In the second plateau, UH 3 is formed and c H reaches 7.6 H atoms/F.U. The specimen is disintegrated into fine powder in the second plateau, while in the first plateau the ternary hydride which was identified to be UTi 2 H x (x=4.8 to 6.2) showed high durability against powdering. It is predicted that UTi 2 can be suitable material for tritium storage. (orig.)

Obtaining of U-2.5Zr7.5Nb and U-3Zr-9Nb alloys by sintering process

International Nuclear Information System (INIS)

Mazzeu, Thiago de Oliveira; Paula, Joao Bosco de; Ferraz, Wilmar Barbosa; Santos, Ana Maria Matildes dos; Brina, Jose Giovanni Mascarenhas

2011-01-01

The development of metallic fuels with low enrichment to be used in research and test reactors, as well in the future pressurized water reactors, focuses on the search for uranium alloys of high density. Alloying elements such as Zr, Nb and Mo are added to uranium to improve fuel performance in reactors. In this context, the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) in Belo Horizonte is developing the U-2.5Zr-7.5Nb and U- 3Zr-9Nb (weight %) alloys by the innovative process of sintering that utilizes raw materials in the form of powders. The powders were pressed at 400MPa and then sintered under a vacuum of about 5 x 10-6 Torr at temperatures ranging from 1050 deg to 1300 deg C. The densities of the alloys were measured geometrically and by hydrostatic method using water. The microstructures of the pellets were observed by scanning electron microscopy (SEM) and the elements of alloying were identified by energy dispersive X-ray spectroscopy (SEM/EDS) analysis. The obtained results showed a small increasing density with rising sintering temperature. The highest density achieved was approximately 80% of theoretical density. It was also qualitatively observed that the superficial oxidation of the pellets increased with increasing sintering temperature thus avoiding the fusion of the alloys at higher temperatures. (author)

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

International Nuclear Information System (INIS)

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

2004-01-01

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

First results of U3Si2 production and its relevance in the power scale-up of IPEN research reactor IEA-R1m

International Nuclear Information System (INIS)

Saliba-Silva, A.M.; Souza, J.A.B.; Frajndlich, E.U.C.; Durazzo, M.; Perrotta, J.A.

1997-01-01

The own supply of LEU U 3 Si 2 is crucial for IPEN, since the whole scale-up of IPEN MTR IEA-Rlm reactor will rely on it. The Brazilian request for radioisotopes production is fully linked with the already made power scale-up from 2 to 5 MW for this reactor. IPEN now depends on fuel element material upgrading from U 3 O 8 towards LEU U 3 Si 2 . The fuel plate productive technology from the powdered material is already well established, only needing simple making of minor adjustments, but to reach the stage of producing U 3 Si 2 we need a fully settled chemical pilot plant in order to reach a LEU UF 4 productive routine. Complementing this process, it was also needed to scale down the previous practice of uranium magnesiothermic reduction to around a sub-critical safe uranium mass of approximately 3000g. To complete the metallurgical processing, it is being developed the production of U 3 Si 2 in a vacuum induction furnace. Some experiments to get this intermetallic, using natural uranium, have already been carried out in order to build up a general idea of the future process of LEU U 3 Si 2 . These experiments are described in this paper and also some of the initial characterization results, such as the qualification pattern of the ingot. It is also discussed some new features of inhomogeneity of solidified phases that may be deleterious to future production routine. (author)

Isothermal section of diagram of U-Mo-B and U-Re-B systems

International Nuclear Information System (INIS)

Val'ovka, I.P.; Kuz'ma, Yu.B.

1986-01-01

The methods of X-ray analysis are used to study the U-Mo-B and U-Re-B systems and to plot phase equilibrium diagrams at 1000 and 800 deg C, respectively. A formation of boride UMoB 4 (structure of the ThMoB 4 type) is confirmed in the U-Mo-B system and new compounds are found: U 2 MoB 6 (rhombic structure of the Y 2 ReB 6 type, a=0.9301(9), b=1.1434(11), c=0.3678(4) nm), ∼UMo 2 B 6 and ∼ UMo 4 B 4 with unknown structures. In the U-Re-B system besides previously known boride UReB 4 (the ThMoB 4 structure type), new ones are obtained: U 2 ReB 6 (Y 2 ReB 6 type, a=0.9373(9), b=1.1529(13), c0.3653(4) nm) and UReB 3 (hexagonal structure of the proper type, a=0.5083(1), c=0.5095(1) nm)

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

Alteration of the SETBP1 gene and splicing pathway genes SF3B1, U2AF1, and SRSF2 in childhood acute myeloid leukemia.

Science.gov (United States)

Choi, Hyun-Woo; Kim, Hye-Ran; Baek, Hee-Jo; Kook, Hoon; Cho, Duck; Shin, Jong-Hee; Suh, Soon-Pal; Ryang, Dong-Wook; Shin, Myung-Geun

2015-01-01

Recurrent somatic SET-binding protein 1 (SETBP1) and splicing pathway gene mutations have recently been found in atypical chronic myeloid leukemia and other hematologic malignancies. These mutations have been comprehensively analyzed in adult AML, but not in childhood AML. We investigated possible alteration of the SETBP1, splicing factor 3B subunit 1 (SF3B1), U2 small nuclear RNA auxiliary factor 1 (U2AF1), and serine/arginine-rich splicing factor 2 (SRSF2) genes in childhood AML. Cytogenetic and molecular analyses were performed to reveal chromosomal and genetic alterations. Sequence alterations in the SETBP1, SF3B1, U2AF1, and SRSF2 genes were examined by using direct sequencing in a cohort of 53 childhood AML patients. Childhood AML patients did not harbor any recurrent SETBP1 gene mutations, although our study did identify a synonymous mutation in one patient. None of the previously reported aberrations in the mutational hotspot of SF3B1, U2AF1, and SRSF2 were identified in any of the 53 patients. Alterations of the SETBP1 gene or SF3B1, U2AF1, and SRSF2 genes are not common genetic events in childhood AML, implying that the mutations are unlikely to exert a driver effect in myeloid leukemogenesis during childhood.

U-isotopes and "2"2"6Ra as tracers of hydrogeochemical processes in carbonated karst aquifers from arid areas

International Nuclear Information System (INIS)

Guerrero, José Luis; Vallejos, Ángela; Cerón, Juan Carlos; Sánchez-Martos, Francisco; Pulido-Bosch, Antonio; Bolívar, Juan Pedro

2016-01-01

Sierra de Gádor is a karst macrosystem with a highly complex geometry, located in southeastern Spain. In this arid environment, the main economic activities, agriculture and tourism, are supported by water resources from the Sierra de Gádor aquifer system. The aim of this work was to study the levels and behaviour of some of the most significant natural radionuclides in order to improve the knowledge of the hydrogeochemical processes involved in this groundwater system. For this study, 28 groundwater and 7 surface water samples were collected, and the activity concentrations of the natural U-isotopes ("2"3"8U, "2"3"5U and "2"3"4U) and "2"2"6Ra by alpha spectrometry were determined. The activity concentration of "2"3"8U presented a large variation from around 1.1 to 65 mBq L"−"1. Elevated groundwater U concentrations were the result of oxidising conditions that likely promoted U dissolution. The PHREEQC modelling code showed that dissolved U mainly existed as uranyl carbonate complexes. The "2"3"4U/"2"3"8U activity ratios were higher than unity for all samples (1.1–3.8). Additionally, these ratios were in greater disequilibrium in groundwater than surface water samples, the likely result of greater water-rock contact time. "2"2"6Ra presented a wide range of activity concentrations, (0.8 up to about 4 × 10"2 mBq L"−"1); greatest concentrations were detected in the thermal area of Alhama. Most of the samples showed "2"2"6Ra/"2"3"4U activity ratios lower than unity (median = 0.3), likely the result of the greater mobility of U than Ra in the aquifer system. The natural U-isotopes concentrations were strongly correlated with dissolution of sulphate evaporites (mainly gypsum). "2"2"6Ra had a more complex behaviour, showing a strong correlation with water salinity, which was particularly evident in locations where thermal anomalies were detected. The most saline samples showed the lowest "2"3"4U/"2"3"8U activity ratios, probably due to fast uniform bulk

Deep Keck u-Band Imaging of the Hubble Ultra Deep Field: A Catalog of z ~ 3 Lyman Break Galaxies

Science.gov (United States)

Rafelski, Marc; Wolfe, Arthur M.; Cooke, Jeff; Chen, Hsiao-Wen; Armandroff, Taft E.; Wirth, Gregory D.

2009-10-01

We present a sample of 407 z ~ 3 Lyman break galaxies (LBGs) to a limiting isophotal u-band magnitude of 27.6 mag in the Hubble Ultra Deep Field. The LBGs are selected using a combination of photometric redshifts and the u-band drop-out technique enabled by the introduction of an extremely deep u-band image obtained with the Keck I telescope and the blue channel of the Low Resolution Imaging Spectrometer. The Keck u-band image, totaling 9 hr of integration time, has a 1σ depth of 30.7 mag arcsec-2, making it one of the most sensitive u-band images ever obtained. The u-band image also substantially improves the accuracy of photometric redshift measurements of ~50% of the z ~ 3 LBGs, significantly reducing the traditional degeneracy of colors between z ~ 3 and z ~ 0.2 galaxies. This sample provides the most sensitive, high-resolution multi-filter imaging of reliably identified z ~ 3 LBGs for morphological studies of galaxy formation and evolution and the star formation efficiency of gas at high redshift.

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

International Nuclear Information System (INIS)

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

1976-01-01

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

Anti-U-like as an alloantibody in S-s-U- and S-s-U+(var) black people.

Science.gov (United States)

Peyrard, Thierry; Lam, Yin; Saison, Carole; Arnaud, Lionel; Babinet, Jérôme; Rouger, Philippe; Bierling, Philippe; Janvier, Daniel

2012-03-01

S, s, and U antigens belong to the MNS system. They are carried by glycophorin B (GPB), encoded by GYPB. Black people with the low-prevalence S-s- phenotype, either U- or U+(var), can make a clinically significant anti-U. Anti-U-like, a cold immunoglobulin G autoantibody quite commonly observed in S-s+U+ black persons, was previously described to be nonreactive with ficin-, α-chymotrypsin-, and pronase-treated red blood cells (RBCs); nonreactive or weakly reactive with papain-treated RBCs; and reactive with trypsin-treated RBCs. Here we describe, in S-s- people from different molecular backgrounds, an alloantibody to a high-prevalence GPB antigen, which presents the same pattern of reactivity with proteases as autoanti-U-like. Four S-s- patients with an alloantibody to a high-prevalence GPB antigen were investigated by serologic and molecular methods. An alloantibody was observed in two S-s-U-/Del GYPB, one S-s-U+(var)/GYPB(P2), and one S-s-U+(var)/GYPB(NY) patients. As this alloantibody showed the same pattern of reactivity with proteases as autoanti-U-like, we decided to name it "anti-U-like." Anti-U-like made by the two S-s-U- patients was reactive with the S-s-U+(var) RBCs of the two other patients. S-s-U-/Del GYPB, S-s-U+(var)/GYPB(P2), and S-s-U+(var)/GYPB(NY) patients can make an alloanti-U-like. Anti-U-like made by S-s-U- people appears reactive with GYPB(P2) and GYPB(NY) RBCs, which both express a weak and partial U-like reactivity. We recommend transfusing S-s-U- RBCs in S-s-U- patients showing alloanti-U-like. Our study contributes to a better understanding of alloimmunization to GPB in black people and confirms importance of genotyping in S-s- patients, especially those with sickle cell disease to be frequently transfused. © 2011 American Association of Blood Banks.

Irradiation tests of U3Si2-Al fuels up to very high fission densities

International Nuclear Information System (INIS)

Nuding, M.; Boening, K.

2001-01-01

The new research reactor of the Munich Technical University (TUM), the FRM-II, will have U 3 Si 2 -Al as the fuel. This fuel is considered qualified and optimally usable in the light of findings obtained in the RERTR program (Reduced Enrichment for Research and Test Reactors). The RERTR program was conducted to develop new fuel for the use of low enriched uranium (LEU) in research reactors. As the unique properties of the FRM-II in research and application are based also on achieving a very compact reactor core with highly enriched uranium (HEU), additional irradiation tests were performed on the basis of the RERTR program. They were run in close cooperation with the French Commissariat a l'Energie Atomique (CEA) in its SILOE and OSIRIS facilities, among others. After extensive evaluation, also of other studies, these tests confirm the RERTR findings about fuel swelling behavior and, consequently, the suitability of U 3 Si 2 -Al (HEU) for use in the compact core of the FRM-II. (orig.) [de

Analysis of the right-handed Majorana neutrino mass in an S U (4 )×S U (2 )L×S U (2 )R Pati-Salam model with democratic texture

Science.gov (United States)

Yang, Masaki J. S.

2017-03-01

In this paper, we attempt to build a unified model with the democratic texture, that has some unification between up-type Yukawa interactions Yν and Yu . Since the S3 L×S3 R flavor symmetry is chiral, the unified gauge group is assumed to be Pati-Salam type S U (4 )c×S U (2 )L×S U (2 )R. The breaking scheme of the flavor symmetry is considered to be S3 L×S3 R→S2 L×S2 R→0 . In this picture, the four-zero texture is desirable for realistic masses and mixings. This texture is realized by a specific representation for the second breaking of the S3 L×S3 R flavor symmetry. Assuming only renormalizable Yukawa interactions, type-I seesaw mechanism, and neglecting C P phases for simplicity, the right-handed neutrino mass matrix MR can be reconstructed from low energy input values. Numerical analysis shows that the texture of MR basically behaves like the "waterfall texture." Since MR tends to be the "cascade texture" in the democratic texture approach, a model with type-I seesaw and up-type Yukawa unification Yν≃Yu basically requires fine-tunings between parameters. Therefore, it seems to be more realistic to consider universal waterfall textures for both Yf and MR, e.g., by the radiative mass generation or the Froggatt-Nielsen mechanism. Moreover, analysis of eigenvalues shows that the lightest mass eigenvalue MR 1 is too light to achieve successful thermal leptogenesis. Although the resonant leptogenesis might be possible, it also requires fine-tunings of parameters.

Optical spectroscopy and crystal-field analysis of U{sup 3+}: Ba{sub 2}YCl{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Karbowiak, M.; Mech, A.; Drozdzyndki, J. [Wroclaw Univ., Faculty of Chemistry (Poland); Gajek, Z. [Polish Academy of Sciences, W. Trzebiatowski Institute of Low Temperature and Structure Research, Wroclaw (Poland); Edelstein, N.M. [Lawrence Berkeley National Lab., Chemical Sciences Div., CA (United States)

2002-11-01

High resolution absorption spectra of a U{sup 3+}(0.3%): Ba{sub 2}YCl{sub 7} single crystal were recorded in the 4000-50 000 cm{sup -1} range at 7 K. The observed crystal-field levels were assigned and fit to the parameters of the simplified angular overlap model (AOM) as well as a semi-empirical Hamiltonian representing the combined atomic and one-electron crystal-field interactions. The starting values of the AOM parameters were obtained from ab initio calculations. The analysis of the spectra allowed the assignment of 65 crystal-field levels with a relatively small rms deviation of 25 cm{sup -1} and has shown that the AOM approach can predict quite well the B{sub q}{sup k} crystal-field parameters. The value determined for the crystal-field strength parameter, N{sub v}, corresponds well with those determined for U{sup 3+} in other chloride single crystals. (authors)

uPA/uPAR system activation drives a glycolytic phenotype in melanoma cells.

Science.gov (United States)

Laurenzana, Anna; Chillà, Anastasia; Luciani, Cristina; Peppicelli, Silvia; Biagioni, Alessio; Bianchini, Francesca; Tenedini, Elena; Torre, Eugenio; Mocali, Alessandra; Calorini, Lido; Margheri, Francesca; Fibbi, Gabriella; Del Rosso, Mario

2017-09-15

In this manuscript, we show the involvement of the uPA/uPAR system in the regulation of aerobic glycolysis of melanoma cells. uPAR over-expression in human melanoma cells controls an invasive and glycolytic phenotype in normoxic conditions. uPAR down-regulation by siRNA or its uncoupling from integrins, and hence from integrin-linked tyrosine kinase receptors (IL-TKRs), by an antagonist peptide induced a striking inhibition of the PI3K/AKT/mTOR/HIF1α pathway, resulting into impairment of glucose uptake, decrease of several glycolytic enzymes and of PKM2, a checkpoint that controls metabolism of cancer cells. Further, binding of uPA to uPAR regulates expression of molecules that govern cell invasion, including extracellular matrix metallo-proteinases inducer (EMPPRIN) and enolase, a glycolytyc enzyme that also serves as a plasminogen receptor, thus providing a common denominator between tumor metabolism and phenotypic invasive features. Such effects depend on the α5β1-integrin-mediated uPAR connection with EGFR in melanoma cells with engagement of the PI3K-mTOR-HIFα pathway. HIF-1α trans-activates genes whose products mediate tumor invasion and glycolysis, thus providing the common denominator between melanoma metabolism and its invasive features. These findings unveil a unrecognized interaction between the invasion-related uPAR and IL-TKRs in the control of glycolysis and disclose a new pharmacological target (i.e., uPAR/IL-TKRs axis) for the therapy of melanoma. © 2017 UICC.

Crystal-field analysis of U3+ ions in K2LaX5 (X=Cl, Br or I) single crystals

Science.gov (United States)

Karbowiak, M.; Edelstein, N.; Gajek, Z.; Drożdżyński, J.

1998-11-01

An analysis of low temperature absorption spectra of U3+ ions doped in K2LaX5 (X=Cl, Br or I) single crystals is reported. The energy levels of the U3+ ion in the single crystals were assigned and fitted to a semiempirical Hamiltonian representing the combined atomic and crystal-field interactions at the Cs symmetry site. An analysis of the nephelauxetic effect and crystal-field splittings in the series of compounds is also reported.

Site Characterization Data from the U3ax/bl Exploratory Boreholes at the Nevada Test Site

International Nuclear Information System (INIS)

2005-01-01

This report provides qualitative analyses and preliminary interpretations of hydrogeologic data obtained from two 45-degree, slanted exploratory boreholes drilled within the Area 3 Radioactive Waste Management Site (RWMS) at the Nevada Test Site. Borehole UE-3bl-D1 was drilled beneath the U3ax/bl mixed waste disposal unit, and Borehole UE-3bl-U1 was drilled in undisturbed alluvium adjacent to the disposal unit. The U3ax/bl disposal unit is located within two conjoined subsidence craters, U3ax and U3bl, which were created by underground nuclear testing. Data from these boreholes were collected to support site characterization activities for the U3ax/bl disposal unit and the entire Area 3 RWMS. Site characterization at disposal units within the Area 3 RWMS must address the possibility that subsidence craters and associated disturbed alluvium of the chimneys beneath the craters might serve as pathways for contaminant migration. The two boreholes were drilled and sampled to compare hydrogeologic properties of alluvium below the waste disposal unit with those of adjacent undisturbed alluvium. Whether Borehole UE-3bl-D1 actually penetrated the chimney of the U3bl crater is uncertain. Analyses of core samples showed little difference in hydrogeologic properties between the two boreholes. Important findings of this study include the following: No hazardous or radioactive constituents of waste disposal concern were found in the samples obtained from either borehole. No significant differences in physical and hydrogeologic properties between boreholes is evident, and no evidence of significant trends with depth for any of these properties was observed. The values observed are typical of sandy materials. The alluvium is dry, with volumetric water content ranging from 5.6 to 16.2 percent. Both boreholes exhibit a slight increase in water content with depth, the only such trend observed. Water potential measurements on core samples from both boreholes show a large positive

Site Characterization Data from the U3ax/bl Exploratory Boreholes at the Nevada Test Site

Energy Technology Data Exchange (ETDEWEB)

Bechtel Nevada; U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office

2005-08-01

This report provides qualitative analyses and preliminary interpretations of hydrogeologic data obtained from two 45-degree, slanted exploratory boreholes drilled within the Area 3 Radioactive Waste Management Site (RWMS) at the Nevada Test Site. Borehole UE-3bl-D1 was drilled beneath the U3ax/bl mixed waste disposal unit, and Borehole UE-3bl-U1 was drilled in undisturbed alluvium adjacent to the disposal unit. The U3ax/bl disposal unit is located within two conjoined subsidence craters, U3ax and U3bl, which were created by underground nuclear testing. Data from these boreholes were collected to support site characterization activities for the U3ax/bl disposal unit and the entire Area 3 RWMS. Site characterization at disposal units within the Area 3 RWMS must address the possibility that subsidence craters and associated disturbed alluvium of the chimneys beneath the craters might serve as pathways for contaminant migration. The two boreholes were drilled and sampled to compare hydrogeologic properties of alluvium below the waste disposal unit with those of adjacent undisturbed alluvium. Whether Borehole UE-3bl-D1 actually penetrated the chimney of the U3bl crater is uncertain. Analyses of core samples showed little difference in hydrogeologic properties between the two boreholes. Important findings of this study include the following: No hazardous or radioactive constituents of waste disposal concern were found in the samples obtained from either borehole. No significant differences in physical and hydrogeologic properties between boreholes is evident, and no evidence of significant trends with depth for any of these properties was observed. The values observed are typical of sandy materials. The alluvium is dry, with volumetric water content ranging from 5.6 to 16.2 percent. Both boreholes exhibit a slight increase in water content with depth, the only such trend observed. Water potential measurements on core samples from both boreholes show a large positive

Prelaunch Performance of the 118 GHz Polarcube 3U Cubesat Temperature Sounding Radiometer

Science.gov (United States)

Periasamy, L.; Gasiewski, A. J.; Gallaher, D. W.; Sanders, B. T.; Belter, R.; Kraft, D.; Castillo, J.; Gordon, J. A.; Hurowitz, M.

2017-12-01

The low cost PolarCube 3U CubeSat supports a 118.75 GHz imaging spectrometer for temperature profiling of the troposphere and surface temperature. It is a demonstrator for a constellation of LEO passive microwave sensors at V-band and other frequencies using 3U/6U CubeSats. Such a satellite constellation for weather forecasting will provide data at high spatial and temporal resolution to observe rapidly evolving mesoscale weather. The satellite's payload is an eight channel, double sideband passive microwave temperature sounder with cross-track scanning and will provide 18 km surface resolution from a 400 km orbit. The radiometer implements a two-point calibration using an internal PIN switch and view of cold space. Although the instrument is based on a well established classical design, the challenges lie in developing a sensitive spectrometer that fits in a 1.5U volume, is low cost, consumes 4 W power and satisfies the CubeSat weight and envelope constraints. PolarCube is scheduled for launch on a Virgin Galactic flight in summer, 2018. The estimated radiometer sensitivity, ΔTrms varies from 0.3 to 2 K across the eight channels. The 50 MHz to 7 GHz 8-channel filter bank (designed with surface mount capacitors and inductors) fits on a 9x5 cm2 RO4350B PCB and includes 2-stage amplification and detector circuitry. The scanning reflector with an 8 cm2 main aperture uses a 3D printed corrugated feed that includes a WR8 to WC8 waveguide transition with a 17° bend. Initial performance results from the instrument using the 3D printed feed and IF/VA board obtained from airborne measurements over Antarctica on the NASA DC8 in early November 2016 indicate a well-functioning radiometer. The end-to-end characterization of the payload with the satellite bus, performance results from vibration and thermal-vacuum tests and roof-top measurements will be presented.

Hydrolysis of U(VI) and sodium uranates

International Nuclear Information System (INIS)

Pongi, N.-K.; Double, Gerard; Hurwic, Jozef

1980-01-01

The potentiometric titration curves of UO 2 (NO 3 ) 2 aqueous solutions by NaOH have been interpreted. The results we have got verify and complete those published before. From isohydric species (UO 2 ) 3 (OH) 7 - , with pH = 7,8 and the experimental molar value of the relation xsub(i) = Na/U = 2.33, the following ionic and molecular species in acid medium have been deduced: (UO 2 ) 2 (OH) 2 2+ , (UO 2 ) 3 (OH) 2 2+ , (UO 2 ) 3 (OH) 5 + and (UO 2 ) 3 (OH) 6 . The composition of the precipitates corresponding to the particular points of the potentiometric titration curves, by chemical, thermal decomposition analysis and by X-rays diffraction, have been carried out: (UO 2 ) 6 (OH) 12 .6H 2 O, Na 2 U 8 O 25 , Na 2 U 6 O 19 , Na 2 U 4 O 13 and Na 2 U 2 O 7 for xsub(i) = 1,67 and 2.00, 2.23, 2.33, 2.52, 3.00 and over, respectively. The uranyl hydroxide was obtained for first time from an aqueous solution [fr

Hyperpolarized [U-(2) H, U-(13) C]Glucose reports on glycolytic and pentose phosphate pathway activity in EL4 tumors and glycolytic activity in yeast cells.

Science.gov (United States)

Timm, Kerstin N; Hartl, Johannes; Keller, Markus A; Hu, De-En; Kettunen, Mikko I; Rodrigues, Tiago B; Ralser, Markus; Brindle, Kevin M

2015-12-01

A resonance at ∼181 ppm in the (13) C spectra of tumors injected with hyperpolarized [U-(2) H, U-(13) C]glucose was assigned to 6-phosphogluconate (6PG), as in previous studies in yeast, whereas in breast cancer cells in vitro this resonance was assigned to 3-phosphoglycerate (3PG). These peak assignments were investigated here using measurements of 6PG and 3PG (13) C-labeling using liquid chromatography tandem mass spectrometry (LC-MS/MS) METHODS: Tumor-bearing mice were injected with (13) C6 glucose and the (13) C-labeled and total 6PG and 3PG concentrations measured. (13) C MR spectra of glucose-6-phosphate dehydrogenase deficient (zwf1Δ) and wild-type yeast were acquired following addition of hyperpolarized [U-(2) H, U-(13) C]glucose and again (13) C-labeled and total 6PG and 3PG were measured by LC-MS/MS RESULTS: Tumor (13) C-6PG was more abundant than (13) C-2PG/3PG and the resonance at ∼181 ppm matched more closely that of 6PG. (13) C MR spectra of wild-type and zwf1Δ yeast cells showed a resonance at ∼181 ppm after labeling with hyperpolarized [U-(2) H, U-(13) C]glucose, however, there was no 6PG in zwf1Δ cells. In the wild-type cells 3PG was approximately four-fold more abundant than 6PG CONCLUSION: The resonance at ∼181 ppm in (13) C MR spectra following injection of hyperpolarized [U-(2) H, U-(13) C]glucose originates predominantly from 6PG in EL4 tumors and 3PG in yeast cells. © 2014 Wiley Periodicals, Inc.

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

International Nuclear Information System (INIS)

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

1982-01-01

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

Electrochemical reduction behavior of U3O8 powder in a LiCl molten salt

International Nuclear Information System (INIS)

Jeong, Sang Mun; Shin, Ho-Sup; Hong, Sun-Seok; Hur, Jin-Mok; Do, Jae Bum; Lee, Han Soo

2010-01-01

The reduction path of the U 3 O 8 powder vol-oxidized at 1200 deg. C has been determined by a series of electrochemical experiments in a 1 wt.% Li 2 O/LiCl molten salt. Various reaction intermediates are observed by during electrolysis of U 3 O 8 . The formation of the metallic uranium is caused from two different reduction paths, a direct reduction of uranium oxide and an electro-lithiothermic reduction. As the uranium oxide is converted to the metallic uranium, the lithium metal is more actively formed in the cathode basket. The reducibility of the rare earth oxides with the U 3 O 8 powder has been tested by constant voltage electrolysis. The results suggest the advanced vol-oxidation could lead to the enhancement in the reducibility of the rare earth fission products.

In-reactor behaviour of centrifugally atomized U3Si dispersion fuel irradiated at high temperature in HANARO

International Nuclear Information System (INIS)

Kim, Ki Hwan; Park, Jong Man; Yoo, Byeong Ok; Park, Dae Kyu; Lee, Choong Sung; Kim, Chang Kyu

2002-01-01

The irradiation test on full-size U 3 Si dispersion fuel elements, prepared by centrifugal atomization and conventional comminution method, has been performed up to about 77 at.% U-235 in maximum burn-up at CT hole position having the highest power condition in the HANARO reactor, in order to examine the irradiation performance of the atomized U 3 Si for the driver fuels of HANARO. The in-reactor interaction of the atomized U 3 Si dispersion fuel meats is generally assumed to be acceptable with the range of 5-15 μm in average thickness. The atomized spherical particles have more uniform and thinner reaction layer than the comminuted irregular particles. The U 3 Si particles have relatively fine and uniform size distribution of fission gas bubbles, irrespective of the powdering method. The bubble population in the atomized particles appears to be finer and more homogeneous with the characteristics of narrower bubble size distribution than that of the comminuted fuel. The atomized U 3 Si dispersion fuel elements exhibit sound swelling behaviours of 5 % in ΔV/V m even at ∼77 at.% U-235 burn-up, which meets with the safety criterion of the fuel rod, 20vol.% for HANARO. The atomized U3Si dispersion fuel elements show smaller swelling than the comminuted fuel elements

Preparation of U3O8 powder for MTR type fuel from ammonium uranyl carbonate

International Nuclear Information System (INIS)

Marcondes, G.H.; Riella, H.G.

1990-08-01

In this paper it is described the research done at IPEN-CNEN/SP on the preparation of U 3 O 8 powder from calcination of the AUC, with appropriate characteristics to be used as dispersoid for MTR type fuel. The calcination in air of the AUC leads a U 3 O 8 powder that is further processed to obtain a powder with density and particle size as especifications. The important process parameters are here discussed with the variation AUC calcination temperature and sintering time of the U 3 O 8 powder. (author) [pt

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

International Nuclear Information System (INIS)

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

1983-06-01

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

High-Uranium-Loaded U3O8-Al fuel element development program. Part 1

International Nuclear Information System (INIS)

Martin, M.M.

1993-01-01

The High-Uranium-Loaded U 3 O 8 -Al Fuel Element Development Program supports Argonne National Laboratory efforts to develop high-uranium-density research and test reactor fuel to accommodate use of low-uranium enrichment. The goal is to fuel most research and test reactors with uranium of less than 20% enrichment for the purpose of lowering the potential for diversion of highly-enriched material for nonpeaceful usages. The specific objective of the program is to develop the technological and engineering data base for U 3 O 8 -Al plate-type fuel elements of maximal uranium content to the point of vendor qualification for full scale fabrication on a production basis. A program and management plan that details the organization, supporting objectives, schedule, and budget is in place and preparation for fuel and irradiation studies is under way. The current programming envisions a program of about four years duration for an estimated cost of about two million dollars. During the decades of the fifties and sixties, developments at Oak Ridge National Laboratory led to the use of U 3 O 8 -Al plate-type fuel elements in the High Flux Isotope Reactor, Oak Ridge Research Reactor, Puerto Rico Nuclear Center Reactor, and the High Flux Beam Reactor. Most of the developmental information however applies only up to a uranium concentration of about 55 wt % (about 35 vol % U 3 O 8 ). The technical issues that must be addressed to further increase the uranium loading beyond 55 wt % U involve plate fabrication phenomena of voids and dogboning, fuel behavior under long irradiation, and potential for the thermite reaction between U 3 O 8 and aluminum

Ceramic grade (U,Pu)O2 powder fabrication

International Nuclear Information System (INIS)

Cristallini, O.A.; Villegas de Maroto, Marina; De Pino, J.I.; Osuna, H.A.

1980-01-01

Ceramic grade UO 2 powder was obtained by the homogeneous precipitation method. This procedure was afterwards applied to the fabrication of ceramic grade (U,Pu)O 2 powders, and mixed oxide powders with Pu content ranging from 0.7 to 16% were obtained. The obtainment of mixed ceramic oxides as well as the recuperation of fabrication scraps were developed in three steps: 1)study of the process of homogeneous precipitation of ammonium diuranate (ADU); 2) co-precipitation of ADU/PuO 2 .H 2 O for Pu concentrations of 0.6 and 6.8; 3) the thermal conditioning to mixed oxide (U,Pu)O 2 powders. The experimental procedure involves the following steps: preparation of the PuO 2 (NO 3 ) 4 solution; co-precipitation of the PuO 2 (NO 3 ) 2 solution with an UO 2 (NO 3 ) 2 solution; filtration and drying of the precipitate, thermal treatment and finally, mixing, pressing and sintering of the (U,Pu)O 2 and Nukem UO 2 powder with a 0. of zinc stearate. Different controls were made by means of physical, chemical and ceramographic tests. This method can be used for the fabrication of fast reactor fuels or, previous mechanical dispersion in UO 2 powder, for the fabrication of thermal reactors fuels. (M.E.L.) [es