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Attempts to Confirm the Existence of the 10-Minute Isotope of102

Description: In many score of experiments conducted in various ways over a period of many months they find that they are unable to confirm the element 102 discovery work of Fields et al. reported in 1957. These experimenters ascribed to an isotope of element 102 an alpha particle activity having an energy of 8.5 {+-} 0.1 Mev and a half-life of approximately 10 minutes. It was reported to be produced by bombardments of a 1 mg/cm{sup 2} curium target with 0.03-0.10 mter-microamperes of C{sup 13} ions of about 90 Mev energy in the internal beam of the Nobel Institute 225 cm cyclotron. Our attempts to reproduce this activity were made with the monoenergetic ion beam available from the Berkeley heavy ion linear accelerator (HILAC). Curium with a similar isotopic composition was used, except that instead of one target they used six separate electroplated targets, four with 0.4 mg/cm{sup 2} curium and two with 0.1 mg/cm{sup 2} curium. These were mounted in vacuum so that the heavy ion beam could pass through and knock the transmutation recoils into 0.9 mg/cm{sup 2} palladium foils. After a suitable bombardment the six catcher foils were dissolved in a few drops of concentrated aqua regia and an actinide element fraction quickly separated from palladium by elution with 2M HCl from a column packed with Dowex-1 anion exchange resin. It was possible to examine a trans-plutonium fraction within 8 minutes from the end of bombardment. A wide range of energies (60-100 Mev) of both C{sup 12} and C{sup 13} projectiles and (+6) ion currents up to 0.2 microamperes were used. In order to compare these bombardments with those which were reported to have produced the 8.5 Mev alpha activity one can compare the amounts of the other alpha particle activities that are produced in such bombardments. The ...
Date: June 4, 1958
Creator: Ghiorso, A.; Sikkeland, T.; Walton, J.R. & Seaborg, G.T.
Partner: UNT Libraries Government Documents Department

Breeding 10{sup 10}/s Radioactive Nuclei in a Compact Plasma Focus Device

Description: In the early 90's, it was discovered that a Plasma Focus (PF) system self-creates a plasma-tarp in which high energy-threshold nuclear-reactions occur at high reaction rates. Short life radioisotopes (SLR)s such as {sup 18}F, {sup 17}F, {sup 15}O, {sup 14}O, {sup 13}N have been generated (10{sup 6} - 10{sup 8} per pulse) with a PF-machine using 7 kJ energy storage to produce the plasmas. {beta}{sup -} radioactivity from the SLRs is measured with rugged, Geiger counters inserted into the PF-chamber, and a specific SLR is identified by its half-life. The PF chamber (before discharge) is filled with a mixture of gases that constitutes the latter plasma-target--beam system, e.g., the elements required to produce specific SLRs through nuclear reactions. In this paper, arguments are presented showing that a modest sized PF-machine, using a 50-75 kJ fast capacitor-bank, when operated at pulse frequencies of 1-10 Hz can produce {ge} 10{sup 9} SLRs/pulse. This paper reports the result s of testing a PF as a breeder of SLRs with dual applications for: (1) Secondary Radioactive Nuclear Beams ion-sources (Z < 35), and (2) as a breeder of radioisotopes for biomedicine (Z {le} 10) and/or PET imaging.
Date: July 27, 2001
Creator: Brzosko, JANS.
Partner: UNT Libraries Government Documents Department

Alumina column Rb-82 generator

Description: The use of an alumina column for the adsorption of radioactive Sr for the generator production of 75-sec /sup 82/Rb was evaluated in both batches and column experiments using /sup 85/Sr and cyclotron-produced /sup 82/Sr. Comparisons of alumina, Bio-Rex 70 and Chelex 100 ion exchangers were made to determine Sr adsorption, /sup 82/Rb elution yield and Sr breakthrough. The adsorption of Sr is similar for alumina and Chelex 100 but different for Bio-Rex 70. Alumina and Chelex 100 exhibit a small fraction of poorly bound Sr which appears as higher breakthrough in the early elution volumes. The remaining Sr activity is strongly bound to these ion exchangers and the breakthrough remains stable at a lower breakthrough value through a large number of elutions. Bio-Rex 70 on the other hand does not exhibit the poorly bound Sr fraction and the breakthrough of Sr remains the lowest of the three ion exchangers through a moderate number of elutions and then the Sr breakthrough gradually increases with each additional elution.
Date: October 1, 1977
Creator: Yano, Y. & Roth, E.P.
Partner: UNT Libraries Government Documents Department

Supralinearity of peak 5 and peak 6 in TLD-700

Description: Track Theory has been applied to an earlier suggestion, that the supralinearity of TLD's at high gamma-ray doses is due to pre-existing 1-hit and 2-hit trap structures, to calculate high-LET response. Measured /sup 60/Co responses for peaks 5 and 6 in LiF(TLD-700) were decomposed to yield parameters characterizing each peak as a 2-component c-hit mixture. One value of trap radius was assigned to each 2-component representation, different for peak 5 and for peak 6, to calculate their responses for H, He, C, O, and Ne bombardments. Calculations reproduce experimental features of the heavy-ion response of TLD-700, and provide means of connecting the gamma and high-LET responses in thermoluminescent dosimeters.
Date: January 1, 1980
Creator: Waligorski, M P.R. & Katz, R
Partner: UNT Libraries Government Documents Department

Analysis of homogeneous U233 and U235 critical assemblies with ENDF/B-IV data (AWBA development program)

Description: Thirty-two U233 and U235 homogeneous aqueous critical experiments were analyzed with ENDF/B-IV data. Calculated eigenvalues for both fuel types increased by nearly 2 percent over the range of hydrogen/uranium atomic ratio covered (from 2106 to 27.1). This is attributed mostly to an underprediction of fast leakage, with some contribution from the fission and capture resonance integrals of ENDF/B-IV U235. Eigenvalue sensitivities to several nuclear data changes were examined. Values of the thermal criticality parameter constraint K2 for U233 and U235 were derived from the Gwin-Magnuson critical experiments at the zero leakage limit.
Date: October 1, 1977
Creator: Ullo, J.J. & Hardy, J. Jr.
Partner: UNT Libraries Government Documents Department

Atomic vapor laser isotope separation using resonance ionization

Description: Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power-reactor fuel has been under development for over 10 years. In June 1985, the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for enriched uranium. Resonance photoionization is the heart of the AVLIS process. We discuss those fundamental atomic parameters that are necessary for describing isotope-selective resonant multistep photoionization along with the measurement techniques that we use. We illustrate the methodology adopted with examples of other elements that are under study in our program.
Date: September 1, 1986
Creator: Comaskey, B.; Crane, J.; Erbert, G.; Haynam, C.; Johnson, M.; Morris, J. et al.
Partner: UNT Libraries Government Documents Department

Higher superdeformed band members in sup 190 Hg: Evidence for a band interaction

Description: The superdeformed band of {sup 190}Hg has been traced up to a frequency {Dirac h} {ge} 0.4 MeV by combining data from several experiments. A distinct change in the slope of the dynamic moment of inertia J{sup 2} vs {Dirac h} is observed at {Dirac h} = 0.32 MeV. This result is interpreted as evidence for a band interaction at the highest frequencies. Possible interpretations are reviewed.
Date: January 1, 1992
Creator: Bearden, I.G.; Daly, P.J. (Purdue Univ., Lafayette, IN (United States)); Janssens, R.V.F.; Carpenter, M.P.; Ahmad, I.; Khoo, T.L. et al.
Partner: UNT Libraries Government Documents Department

Critical dimensions of systems containing /sup 235/U, /sup 239/Pu, and /sup 233/U: 1986 Revision

Description: This report is primarily a compilation of critical data obtained from experiments performed in a number of laboratories during the period of 1945 through 1985. It supplements the Nuclear Safety Guide (Report TID-7016 (Rev. 2)) in presenting critical data on which recommendations of the Guide are based. It must be emphasized that this report gives critical data without safety factors, so it is no substitute for the Guide or for the related document, The American National Standard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors. Critical measurements with materials of interest in desired configurations yield information of greatest usefulness and accuracy. Where it is not feasible to obtain the desired critical data, for example, as a result of safety restrictions, subcritical data may be directly applicable, and in some cases may be extrapolated to approximate critical conditions. Critical conditions also may be approximated from the distribution of neutrons introduced into a subcritical assembly. These ''exponential experiments'' may be the only alternative where the quantity of material required is too great for a critical experiment. Calculated extensions of experimental data are included to show the nature of trends, not to substitute for results of experiments. They should be used with caution. A fundamental aim of this document is to illustrate relationships among critical data. The compilation and correlation of data for this purpose, from many measurements in a number of laboratories, require a certain amount of normalization or reduction to common terms. Frequently, for example, the effects of variations in geometry or density must be removed to show trends in data. The manner in which these alterations may be made is discussed in the early section Relations for Conversion to Standard Conditions. 195 refs.
Date: July 1, 1987
Creator: Paxton, H.C. & Pruvost, N.L.
Partner: UNT Libraries Government Documents Department

The file of evaluated decay data in ENDF/B

Description: One important application of nuclear decay data is the Evaluated Nuclear Data File/B, the base of evaluated nuclear data used in reactor research and technology activities within the US. This report discusses the decay data file.
Date: January 1, 1991
Creator: Reich, C.W. (Idaho National Engineering Lab., Idaho Falls, ID (USA)) & England, T.R. (Los Alamos National Lab., NM (USA))
Partner: UNT Libraries Government Documents Department

Experimental criticality specifications, update through 1979. Informal report

Description: A table of contents for LA-7170-MS is provided, and publications of criticality specifications that appeared in 1978 and 1979 are listed. The table was omitted from the original document. An abstract of the original report appeared in Energy Research Abstracts, Volume 3: 43410.
Date: February 1, 1980
Creator: Paxton, H.C. (comp.)
Partner: UNT Libraries Government Documents Department

Application of evaluated fission-product delayed-neutron precursor data in reactor kinetics calculations

Description: Evaluated fission-product yield and decay data have been used to describe 105 delayed neutron precursors explicitly in point reactor kinetics calculations. Results calculated for /sup 235/U thermal fission show that rod-drop reactivity values obtained from kinetics calculations with 6-group precursor data are considerably higher than those calculated with explicit delayed-neutron precursor data. The calculated kinetics associated with positive reactivity steps are significantly different.
Date: January 1, 1985
Creator: Perry, R.T.; Wilson, W.B.; England, T.R. & Brady, M.C.
Partner: UNT Libraries Government Documents Department

Nuclear transitions induced by atomic excitations

Description: In the two-step pumping scheme for a gamma-ray laser, an essential step is that of exciting the nucleus from a long-lived storage isomer to a nearby short-lived state that then decays to the upper lasing level. An experiment is in progress to induce this transfer by first exciting the atomic electrons with uv photons. The incident photons couple well to the electrons, which then couple via a virtual photon to the nucleus. As a test case, excitation of the /sup 235/U nucleus is being sought, using a high-brightness uv laser. The excited nuclear state, having a 26-minute half-life, decays by internal converison, resulting in emission of an atomic electron. A pulsed infrared laser produces an atomic beam of /sup 235/U which is then bombarded by the uv laser beam. Ions are collected, and conversion electrons are detected by a channel elctron multiplier. In preliminary experiments, an upper limit of 7 x 10/sup -5/ has been obtained for the probability of exciting a /sup 235/U atom in the uv beam for one picosecond at an intensity of about 10/sup 15/W/cm/sup 2/. Experiments with higher sensitivities and at higher uv beam intensities are underway. 6 refs., 1 fig.
Date: January 1, 1988
Creator: Dyer, P.L.; Bounds, J.A.; Haight, R.C. & Luk, T.S.
Partner: UNT Libraries Government Documents Department

Nuclear fission and nuclear safeguards: Common technologies and challenges

Description: Nuclear fission and nuclear safeguards have much in common, including the basic physical phenomena and technologies involved as well as the commitments and challenges posed by expanding nuclear programs in many countries around the world. The unique characteristics of the fission process -- such as prompt and delayed neutron and gamma ray emission -- not only provide the means of sustaining and controlling the fission chain reaction, but also provide unique ''signatures'' that are essential to quantitative measurement and effective safeguarding of key nuclear materials (notably /sup 239/Pu and /sup 235/U) against theft, loss, or diversion. In this paper, we trace briefly the historical emergence of safeguards as an essential component of the expansion of the nuclear enterprise worldwide. We then survey the major categories of passive and active nondestructive assay techniques that are currently in use or under development for rapid, accurate measurement and verification of safe-guarded nuclear materials in the many forms in which they occur throughout the nuclear fuel cycle. 23 refs., 14 figs.
Date: January 1, 1989
Creator: Keepin, G.R.
Partner: UNT Libraries Government Documents Department

Validation of aggregate delayed neutron spectra calculated from precursor data

Description: An extensive reference library of delayed neutron data has been compiled which contains fission yields and branchings, delayed neutron emission probabilities, and spectra for 271 precursors. These data have been used to calculate the aggregate behavior of delayed neutrons following a fission event in 43 fissioning systems. Least-squares techniques were used to produce fitted decay constants and abundances in the conventional six-group formalism from these calculated activity curves. A consistent set of six-group spectra have also been calculated for each of the fissioning systems. Recent measurements at the University of Lowell have produced measured energy spectra for delayed neutrons following the thermal fission (T) of {sup 235}U and {sup 239}Pu, and the fast fission (F) of {sup 238}U. These measured spectra provide data that may be used to validate the precursor data base and the fitted six-group data. This summary presents results of this validation effort. Both the individual precursor data and the six-group data have been used to calculate aggregate equilibrium spectra for {sup 235}U(T), {sup 238}U(F), and {sup 239}Pu(T) via summation techniques. The important precursors in each case are identified, and the status of their data reviewed. 8 refs., 3 figs., 3 tabs.
Date: January 1, 1989
Creator: Brady, M. C.; England, T. R. & ,
Partner: UNT Libraries Government Documents Department

Real-time fluid flow model for control of solidification

Description: The Atomic Vapor Laser Isotope Separation (AVLIS) process is an advanced uranium enrichment technology being developed by the Lawrence Livermore National Laboratory. This process is designed to increase the concentration of /sup 235/U in uranium from 0.7% as found in nature to approximately 3% as required for light water nuclear reactor fuel. Separation is accomplished by vaporizing uranium, selectively ionizing /sup 235/U atoms and electromagnetically collecting these ions. The electromagnetic collector system utilizes resistance heaters to maintain a temperature range defined by the melting point of the metal product and tails collected and the materials compatibility limits between the liquid metal and the structure. If temperatures are not within these bounds, metal freezing or structural damage may occur which disrupts the process. Additionally, inappropriate heater usage could result in heater burn-out or overheating.
Date: July 1, 1985
Creator: Kraftick, K. & Sholl, P.
Partner: UNT Libraries Government Documents Department

Investigaton of the beta strength function at high energy: gamma-ray spectroscopy of the decay of 5. 3-s /sup 84/As to /sup 84/Se

Description: The beta strength function up to approximately 8.6 MeV for the system /sup 84/As(..beta../sup -/)/sup 84/Se was investigated. It was found that it is not possible to satisfactorily describe S/sub ..beta../ by a statistical model. From the /sup 84/As decay scheme an experimental beta strength function was deduced. Additional information on the beta transition intensity is obtained from the gross coincidence spectra of individual gamma rays. In total these data suggest that the experimental beta strength function above 6.8 MeV is significantly lower than that calculated using a statistical model. Features in the gross coincidence spectra also suggest that a significant bump appears in the experimental beta strength function at approximately 6.5 MeV.
Date: June 1, 1981
Creator: Henry, E.A; Lien, O.G. III & Meyer, R.A.
Partner: UNT Libraries Government Documents Department

Nuclear excitation via the motion of electrons in a strong laser field

Description: A method of switching from a nuclear isomeric state to a lasing state is examined. A semi-classical model of laser-electron-nuclear coupling is developed. In it the electrons are treated as free in the external field of the laser, but with initial conditions corresponding to their atomic orbits. Application is made to testing this model in /sup 235/U and to the design criteria of a gamma-ray laser. 14 refs., 2 tabs.
Date: December 1, 1987
Creator: Berger, J.F.; Gogny, D. & Weiss, M.S.
Partner: UNT Libraries Government Documents Department

AVLIS: a technical and economic forecast

Description: The AVLIS process has intrinsically large isotopic selectivity and hence high separative capacity per module. The critical components essential to achieving the high production rates represent a small fraction (approx.10%) of the total capital cost of a production facility, and the reference production designs are based on frequent replacement of these components. The specifications for replacement frequencies in a plant are conservative with respect to our expectations; it is reasonable to expect that, as the plant is operated, the specifications will be exceeded and production costs will continue to fall. Major improvements in separator production rates and laser system efficiencies (approx.power) are expected to occur as a natural evolution in component improvements. With respect to the reference design, such improvements have only marginal economic value, but given the exigencies of moving from engineering demonstration to production operations, we continue to pursue these improvements in order to offset any unforeseen cost increases. Thus, our technical and economic forecasts for the AVLIS process remain very positive. The near-term challenge is to obtain stable funding and a commitment to bring the process to full production conditions within the next five years. If the funding and commitment are not maintained, the team will disperse and the know-how will be lost before it can be translated into production operations. The motivation to preserve the option for low-cost AVLIS SWU production is integrally tied to the motivation to maintain a competitive nuclear option. The US industry can certainly survive without AVLIS, but our tradition as technology leader in the industry will certainly be lost.
Date: January 1, 1986
Creator: Davis, J.I. & Spaeth, M.L.
Partner: UNT Libraries Government Documents Department

Subnanosecond lifetime measurements of excited states in nuclei far from stability

Description: A system was developed to measure the lifetimes of nuclear states in the range of 0.05 to 1 nanosecond in nuclei far from stability. A Gerholm magnetic lens was placed on-line with the UNISOR mass separator to observe conversion electrons in coincidence with ..gamma.. rays detected in a plastic scintillator. With this system, the half-life of the 522 keV, O/sup +/ level in /sup 186/Hg was measured to be 155 +- 70 picoseconds. Improvements in this system should make possible on-line measurements of half-lives as short as approx. = 50 picoseconds. 12 references.
Date: January 1, 1979
Creator: Nettles, W.G.; Ramayya, A.V.; Hamilton, J.H.; Avignone, F.T. III & Carter, H.K.
Partner: UNT Libraries Government Documents Department

Observation of superdeformation in sup 191 Hg

Description: The first observation of superdeformation in the A {approx equal} 190 mass region is reported. A rotational band of 12 transitions with an average energy spacing of 37 keV, an average moment of inertia of 110 {Dirac h}{sup 2} MeV{sup {minus}1}, and an average quadrupole moment of 18 {plus minus} 3 eb has been observed in {sup 191}Hg. These results are in excellent agreement with a calculation that predicts an ellipsoidal axis ratio of 1.65:1 for the superdeformed shape in this nucleus. Evidence for another discrete superdeformed band and superdeformed structures in the quasi-continuum was also found in the data. 19 refs., 6 figs.
Date: January 1, 1989
Creator: Moore, E.F.; Janssens, R.V.F.; Chasman, R.R.; Ahmad, I.; Khoo, T.L.; Wolfs, F.L.H. et al.
Partner: UNT Libraries Government Documents Department

Random numbers spring from alpha decay

Description: Congruential random number generators, which are widely used in Monte Carlo simulations, are deficient in that the number they generate are concentrated in a relatively small number of hyperplanes. While this deficiency may not be a limitation in small Monte Carlo studies involving a few variables, it introduces a significant bias in large simulations requiring high resolution. This bias was recognized and assessed during preparations for an accident analysis study of nuclear power plants. This report describes a random number device based on the radioactive decay of alpha particles from a /sup 235/U source in a high-resolution gas proportional counter. The signals were fed to a 4096-channel analyzer and for each channel the frequency of signals registered in a 20,000-microsecond interval was recorded. The parity bits of these frequency counts (0 for an even count and 1 for an odd count) were then assembled in sequence to form 31-bit binary random numbers and transcribed to a magnetic tape. This cycle was repeated as many times as were necessary to create 3 million random numbers. The frequency distribution of counts from the present device conforms to the Brockwell-Moyal distribution, which takes into account the dead time of the counter (both the dead time and decay constant of the underlying Poisson process were estimated). Analysis of the count data and tests of randomness on a sample set of the 31-bit binary numbers indicate that this random number device is a highly reliable source of truly random numbers. Its use is, therefore, recommended in Monte Carlo simulations for which the congruential pseudorandom number generators are found to be inadequate. 6 figures, 5 tables.
Date: May 1, 1980
Creator: Frigerio, N.A.; Sanathanan, L.P.; Morley, M.; Clark, N.A. & Tyler, S.A.
Partner: UNT Libraries Government Documents Department

Projection of needs for gamma radiation sources and other radioisotopes and assessment of alternatives for providing radiation sources

Description: Pacific Northwest Laboratory reviewed the projected uses and demands for a variety of nuclear byproducts. Because the major large-scale near-term demand is for gamma irradiation sources, this report concentrates on the needs for gamma sources and evaluates the options for providing the needed material. Projections of possible growth in the irradiation treatment industry indicate that there will be a need for 180 to 320 MCi of /sup 60/Co (including /sup 137/Cs equivalent) in service in the year 2000. The largest current and projected use of gamma irradiation is for the sterilization of medical devices and disposable medical supplies. Currently, 40% of US disposable medical products are treated by irradiation, and within 10 years it is expected that 90% will be treated in this manner. Irradiation treatment of food for destruction of pathogens or parasites, disinfestation, or extension of allowable storage periods is estimated to require an active inventory of 75 MCi of /sup 60/Co-equivalent gamma source in about a decade. 90 refs., 7 figs., 25 tabs.
Date: June 1, 1989
Creator: Ross, W.A.; Jensen, G.A.; Clark, L.L.; Eakin, D.E.; Jarrett, J.H.; Katayama, Y.B. et al.
Partner: UNT Libraries Government Documents Department