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Initial multi-national study of future energy systems and impacts of some evolving technologies

Description: Participants from thirteen member nations of the International Energy Agency and the Commission of European Communities have been conducting cooperative energy systems analyses, the goal of which is to evaluate the possible impacts of new and conservation technologies. Such studies are intended to provide analytical bases to aid future decisions on cooperative research and development projects. In the initial studies, a quantitative description of the 1974 energy system has been prepared for each participating nation. The nations accounted for approximately half of the world energy consumption in 1974. They imported more than 30 percent of their primary energy requirements from other nations of the world. Oil and natural gas supplied almost /sup 3///sub 4/ of the energy. Reference projections were made for the years 1985 and 2000 to provide base cases for studies of the impacts of new and conservation technologies. Although these projections are not intended to be forecasts, taken together they indicate an increasing gap between the demand for energy and foreseeable domestic supplies, thus underscoring the urgency for the vigorous introduction of new energy technologies as well as the need for strong efforts in energy conservation. Some preliminary evaluations of selected technologies were made as a function of current development plans. None of these technologies taken individually appear capable of balancing the demand-supply equation.
Date: March 25, 1977
Partner: UNT Libraries Government Documents Department

Comparison of the characteristics of graphites irradiated at 600 and 900/sup 0/C

Description: Graphite for the reflector in the pebble-bed High-Temperature Reactor in the Federal Republic of Germany (FRG) requires exceptional irradiation resistance for economic viability. The candidate graphites are being irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge to assess their irradiation life expectancy. This assessment is based upon dimensional stability, elastic constants from sonic testing, electrical resistivity from eddy-current testing, coefficient of thermal expansion, and brittle-ring fracture testing. To date 13 FRG grades have been irradiated and compared with four graphites made in the United States and one from the United Kingdom. The irradiation temperatures were 620, 715, and 900/sup 0/C.
Date: January 1, 1983
Creator: Kennedy, C.R.; Eatherly, W.P. & Minderman, D.
Partner: UNT Libraries Government Documents Department

Status of the intense pulsed neutron source

Description: Fortunately in spite of some premature reports of its impending demise, IPNS has passed the fourth anniversary of the first delivery of protons to the targets (May 5, 1981) and is approaching the fourth anniversary of its operation as a scattering facility (August 4, 1981). On June 10, 1984, the RCS delivered its one billionth pulse to the IPNS target - the total number of protons delivered to the targets amounted then to 75 stp cm/sup 3/ of H/sub 2/ gas. Since startup IPNS has improved steadily in terms of the performance of the Rapid Cycling Synchrotron, the source and its moderators and the scattering instruments, and a substantial and productive user program has evolved. This report summarizes the current status of the Intense Pulsed Neutron Source at Argonne National Laboratory. We include reference to recent accelerator operating experience, neutron facility operating experience, improvements to these systems, design work on the ASPUN high-current facility, booster target design, the new solid methane moderator, characterization of the room temperature moderators, and provide some examples of recent results from several of the spectrometers.
Date: January 1, 1985
Creator: Carpenter, J.M.; Brown, B.S.; Kustom, R.L.; Lander, G.H.; Potts, C.W.; Schulke, A.W. et al.
Partner: UNT Libraries Government Documents Department

The passive safety characteristics of modular high temperature gas-cooled reactor fuel elements

Description: High-Temperature Gas-Cooled Reactors (HTGR) in both the US and West Germany use an all-ceramic, coated fuel particle to retain fission products. Data from irradiation, postirradiation examinations and postirradiation heating experiments are used to study the performance capabilities of the fuel particles. The experimental results from fission product release tests with HTGR fuel are discussed. These data are used for development of predictive fuel performance models for purposes of design, licensing, and risk analyses. During off normal events, where temperatures may reach up to 1600/degree/C, the data show that no significant radionuclide releases from the fuel will occur.
Date: January 1, 1988
Creator: Goodin, D.T.; Kania, M.J.; Nabielek, H.; Schenk, W. & Verfondern, K.
Partner: UNT Libraries Government Documents Department

Property changes in graphite irradiated at changing irradiation temperature. [Neutrons]

Description: Design data for irradiated graphite are usually presented as families of isothermal curves showing the change in physical property as a function of fast neutron fluence. In this report, procedures for combining isothermal curves to predict behavior under changing irradiation temperatures are compared with experimental data on irradiation-induced changes in dimensions, Young's modulus, thermal conductivity, and thermal expansivity. The suggested procedure fits the data quite well and is physically realistic.
Date: July 1, 1979
Creator: Price, R.J. & Haag, G.
Partner: UNT Libraries Government Documents Department

Prediction of irradiation behavior of HTGR fuel particle coatings by structural characterization of LTI pyrocarbons

Description: In order to retain the fission products within the coated fuel particles, the coatings which act as fission product barrier have to remain mechanically intact during irradiation. As the mechanical stability of well designed pyrocarbon (PyC) coatings is mainly governed by their microstructure, this paper discusses the influence of PyC microstructure on the irradiation performance of the coatings.
Date: January 1, 1978
Creator: Krautwasser, P.; Wallura, E. & Long, E.L.
Partner: UNT Libraries Government Documents Department

Critical magnetic scattering from the Heisenberg ferromagnet EuS

Description: The paramagnetic scattering from the insulating, isotropic ferromagnet EuS is investigated at T/sub c/ along the (111) direction by means of inelastic neutron scattering. The energy width of the quasielastic scattering is proportional to q/sup z/ with z = 2.54 +- 0.10, in good agreement with the predictions of dynamical scaling theory (z = 2.5). z is, however, significantly larger than the value deduced from measurements along the (100) direction (z = 2.2). Near the zone boundary the magnetic scattering exhibits shoulders the shapes of which deviate from theoretical predictions based on the Heisenberg model. 19 refs., 3 figs.
Date: January 1, 1986
Creator: Boeni, P.; Shirane, G.; Bohn, H.G. & Zinn, W.
Partner: UNT Libraries Government Documents Department

Effect of implanted helium on the microstructure and creep properties of ordered (Fe/sub 0/ /sub 49/Ni/sub 0/ /sub 51/)/sub 3/V alloys

Description: A series of long-range ordered alloys with base composition (Fe/sub 0/ /sub 49/Ni/sub 0/ /sub 51/)/sub 3/V were homogeneously injected with approx. 100 appm helium at 600/sup 0/C using the cyclotron at the Institut fuer Festkoerperforschung (IFF), KFA Juelich, West Germany. Post-implantation creep testing at 600/sup 0/C revealed that the time to rupture as well as the total creep strain was reduced drastically compared to unimplanted material. Transmission electron microscopy (TEM) revealed that while the material retained its long range order after implantation, the microstructure in the as-implanted material was characterized by a high density of faulted interstitial dislocation loops as well as a high density of cavities 2.5 to 5.0 nm in diameter. Most of the cavities were preferentially located on the faulted loops or on grain boundaries. The high angle grain boundaries also contained a large number of small vanadium carbide precipitates. It was observed that cavities on grain boundaries were smaller when associated with these precipitates. In addition a number of larger, 7 to 10 nm diameter, faceted cavities were found to be associated with antiphase domain boundaries (APBs) in the ordered microstructure. TEM was also used to investigate the details of the microstructure which developed during creep. The results indicate that the embrittlement is most likely due to the combined effect of helium at the grain boundaries and the increased resistance to deformation in the hardened matrix material.
Date: January 1, 1983
Creator: Sklad, P.S. & Schroeder, H.
Partner: UNT Libraries Government Documents Department

Influence of radiation-induced segregation on ductility of a nickel-silicon alloy

Description: Flat tensile specimens 60 ..mu..m thick of Ni-8 at. % Si were irradiated to bulk damage levels of 0.1 to 0.3 dpa with either 7 MeV protons or 28 MeV alpha particles at 750 K. The alpha bombarded specimens incurred 750 at. ppM He per 0.1 dpa in the course of their damage-generating irradiation. Radiation-induced silicon segregation gave rise to Ni/sub 3/Si layers at internal and external surfaces. Postirradiation tensile tests conducted either at 300 K or 720 K revealed fully ductile (chisel-edged) transgranular fracture profiles. There were no significant differences between the proton-bombarded specimens and the unbombarded controls, both exhibiting >25% total elongations, while the alpha-bombarded specimens showed ductile fractures with somewhat lower (17 to 18%) elongation values probably due to hardening caused by small helium bubbles. Certain specimens that were preimplanted with 250 to 1000 at. ppM He at 970 K to encourage intergranular failure and expose grain boundaries did fail intergranularly. It is concluded that radiation-induced silicon segregation does not cause intrinsic embrittlement.
Date: January 1, 1986
Creator: Packan, N.H.; Schroeder, H. & Kesternich, W.
Partner: UNT Libraries Government Documents Department

Ion beam mixing of marker layers in Al and Si. [300 keV Ar ions]

Description: Ion beam mixing experiments on thin Pt, Au, and Ni markers in Al and Si have performed at 17, 85, and 300 K. After irradiation with 300-keV Ar ions the broadening and relative shifts of the markers have been determined by RBS measurements. The marker broadenings are more pronounced in Si than in Al; in both matrices the broadenings decrease in the following order: Au, Pt, and Ni. No dependence of mixing on irradiation temperature was observed between 17 and 300 K. The shifts of the heavy Au and Pt markers relative to the Ni markers are approximately equal to the experimental accuracy. However, a shift of the Ni marker toward the surface relative to the heavier Au and Pt markers was consistently observed. 13 references, 2 figures.
Date: July 1, 1984
Creator: Mantl, S.; Rehn, L.E.; Averback, R.S. & Thompson, L.J. Jr.
Partner: UNT Libraries Government Documents Department

Crystal-field splitting in Pr dideuteride

Description: From inelastic neutron scattering experiments, it is concluded that the crystal-field splitting in PrD/sub 1.95/ is 41 meV. Because of this high value, the antiferromagnetic ordering below T/sub N/ = 2.3 K is ascribed to a magnetic ground state, probably GAMMA/sub 5/, of the Pr/sup 3 +/ ions.
Date: August 1, 1985
Creator: Arons, R.R.; Cable, J.W. & Nicklow, R.M.
Partner: UNT Libraries Government Documents Department

Test of the electronic structure of Fe(100) by absorbed current spectroscopy

Description: The absorbed electron current for a clean Fe(100) surface as a function of energy rises step-like at the vacuum-energy cutoff with an absorption close to 1. The smooth decrease of absorbed current at higher electron energy due to secondary electron emission is superimposed by a considerable amount of fine structure, the amplitude of which decreases with increasing energy. These features are found in good agreement with the results of a calculation of the elastic part of the electron reflection coefficient. Further, they are compared with the ferromagnetic electronic bulk bandstructure calculated above the vacuum energy. From the comparison with the experimental data, the energy dependence of the real and imaginary parts of the inner potential is determined.
Date: October 1, 1984
Creator: Kisker, E.; Kirby, R.E.; Garwin, E.L. & King, F.K.
Partner: UNT Libraries Government Documents Department

Radiation-induced segregation in light-ion bombarded Ni-8% Si

Description: Tensile specimens 60 ..mu..m thick of Ni-8 at. % Si have been bombarded at 475/sup 0/C to doses of 0.1 to 0.3 dpa with either 7 MeV proton or 28 MeV alpha particle beams. Deliberate embrittlement by high temperature (700/sup 0/C) preimplantation of helium was required to produce intergranular fracture. Depth profile sputtering and analysis in a Scanning Auger Microprobe was then used to study radiation-induced segregation of silicon both at the external surfaces and at internal interfaces. The external surfaces exhibited a strongly silicon-enriched zone for the first 10 to 20 nm followed by a broad (approx.200 nm), shallow silicon-depleted region. Segregation of silicon to grain boundaries varied from interface to interface and possibly from region to region on a given interface. In general, however, depth profiles of silicon content with distance from internal boundaries showed no noticeable depletion zone and a more gradual fall-off compared to the profiles from external surfaces. The variations of RIS among boundaries and with type of interface probably reflect, at least in part, intrinsic differences in sink efficiency.
Date: January 1, 1986
Creator: Packan, N.H.; Heatherly, L.; Kesternich, W. & Schroeder, H.
Partner: UNT Libraries Government Documents Department

Diffuse x-ray scattering studies of n and e/sup -/-irradiated Ni and dilute Ni alloys

Description: Pure Ni and dilute NiSi and NiGe alloys were irradiated at 6 K with either fast neutrons or 3 MeV electrons. The resulting defect structures were studied using diffuse x-ray scattering methods after different annealing treatments. For both types of irradiation of pure Ni, large interstitial and vacancy dislocation loops developed on annealing. In contrast, interstitial agglomerates in a NiSi/sub .01/ alloy contained no more than approx. =10 interstitials, and few vacancy loops were observed. Complete recovery was observed at lower temperatures in the alloy. Similar results were found for NiGe/sub .01/, although larger interstitial clusters were observed. The results are discussed within the model for the trapping reactions developed previously to explain the results of e/sup -/ irradiation of these same alloys.
Date: August 1, 1986
Creator: Averback, R.S. & Ehrhart, P.
Partner: UNT Libraries Government Documents Department

Hyperon-nucleon interaction and meson exchange

Description: We present first results of our general program which is to construct meson-exchange potentials for hadronic systems involving stange particles, i.e. for KN and AN. We proceed along the same guidelines which have been successfully applied in deriving the (latest version of the) Bonn NN potential, namely to keep the important recoil and nonlocal structure and to use a comprehensive set of diagrams without introducing any fictitious contribution. For KN we show that single vector-meson (..omega..,p) exchange already provides a fair description of the data except for the isospin-1 P/sub 3/2/ wave. This partial wave is remarkably improved by adding a specific higher-order process involving ..delta..K intermediate states. For the ..lambda..N system we demonstrate the inadequacy of a nonrelativistic treatment of the ..lambda..N interaction and point to the strong interplay between K and K*-exchange in the tensor channel, which is even stronger than for ..pi..- and p-exchange in the NN system.
Date: January 1, 1985
Creator: Buttgen, R.; Holinde, K.; Holzenkamp, B. & Speth, J.
Partner: UNT Libraries Government Documents Department

Observation of standing spinwaves in thin Fe-films by means of Raman spectroscopy

Description: We report on the first observation of standing spinwaves in thin evaporated Fe-films by means of Raman scattering (RS). In earlier investigations using Brillouin scattering (BS) these modes could only be observed down to a thickness dapprox. = 200 A. We were now able to extend this range down to d approx. = 120 A using BS and to a range of 40 to 80 A using RS. We find that for values of d comparable to the penetration depth of the light the scattering intensity decreases together with d. This is explained by the assumption that the scattering intensity is determined by the net magnetic moment resulting within the probing depth of the light. The mode frequencies observed by Raman scattering follow very well a D/sub ex/* d/sup -2/ relationship from which the value of the exchange parameter D/sub ex/ has been determined. With decreasing d we also observe an increasing linewidth of the standing spinwaves. This can be attributed to the increased importance of surface roughness on the damping of these modes. 8 references, 4 figures.
Date: September 1, 1984
Creator: Blumenroeder, S.; Zirngiebl, E.; Gruenberg, P. & Guentherodt, G. II
Partner: UNT Libraries Government Documents Department

Mechanism and kinetics of radiation-induced segregation in Ni-Si alloys

Description: Rutherford-backscattering and Auger chemical-depth-profiling measurements show that films of the ..gamma..'-Ni/sub 3/Si phase produced on the ion-bombarded surfaces of Ni-Si alloys obey simple parabolic growth kinetics. At low temperatures the film growth-rate constant exhibits Arrhenius behavior and varies with the fourth root of the dose rate. The apparent activation energy in this low-temperature region is approx. 0.3 eV. At high temperatures the growth constant is independent of the dose rate. The results are consistent with a diffusion-controlled growth model, which assumes Si atoms migrate in the form of a fast-diffusing Si-interstitial complex.
Date: November 1, 1981
Creator: Okamoto, P.R.; Rehn, L.E.; Averback, R.S.; Robrock, K.H. & Wiedersich, H.
Partner: UNT Libraries Government Documents Department

Nuclear structure approach to the calculation of the imaginary alpha-nucleus optical potential. [31 and 100 MeV]

Description: A microscopic calculation of the second-order imaginary optical potential for /sup 40/(Ca(..cap alpha..,..cap alpha..) is made for incident energies of 31 and 100 MeV using RPA transition densities for intermediate excited states. The projectile is treated as an elementary particle, and the alpha-nucleon interaction is normalized by fitting 3/sup -/ inelastic cross sections with a folded M3Y potential. The use of an optical Green's function for the intermediate propagator is found to be important. Equivalent local potentials are obtained and used to calculate elastic scattering cross sections. Agreement with low-angle experimental data is fair at 31 MeV, but at 100 MeV the calculated cross sections indicate much too little absorption. 9 figures, 1 table.
Date: January 1, 1981
Creator: Dermawan, H.; Osterfeld, F. & Madsen, V.A.
Partner: UNT Libraries Government Documents Department

The LANSCE (Los Alamos Neutron Scattering Center) target system

Description: During the summer of 1985, we replaced the WNR T-shaped target/moderator scheme with the LANSCE split-target/flux-trap-moderator design. The intent of this 'LANSCE upgrade' was to increase (to 12) the number of neutron beam lines serviced simultaneously, and to enhance the target area shielding and target system to accept 200 ..mu..A of 800-MeV protons. The four LANSCE moderators consist of three (chilled) water moderators, and a liquid hydrogen (20 K) moderator. The LANSCE target is machinable tungsten.
Date: September 22, 1986
Creator: Russell, G.J.; Robinson, H.; Legate, G.L.; Woods, R.; Whitaker, E.R.; Bridge, A. et al.
Partner: UNT Libraries Government Documents Department

Neutron scattering studies of magnetic correlations in reentrant spin glasses. [Eu/sub x/Sr/sub 1-x/S; Fe-Al]

Description: We review neutron scattering measurements performed on two disparate reentrant spin glass systems: the magnetic insulator Eu/sub x/Sr/sub 1-x/S and the metallic alloy Fe/sub 1-x/Al/sub x/. We show that the magnetic behavior in the two is very similar and can be explained in terms of random field effects which arise when ferromagnetic and spin glass order parameters are coupled together.
Date: January 1, 1985
Creator: Shapiro, S.M.; Aeppli, G.; Maletta, H. & Motoya, K.
Partner: UNT Libraries Government Documents Department

ALT-I pump limiter experiments with ICRF heating on TEXTOR

Description: The ALT-I (Advanced Limiter Test-I) was installed on TEXTOR to benchmark the ability of a pump limiter as an efficient particle collector and to determine the physics of pump limiter operation. Experiments continue to show its capability of removing particles from the plasma edge under different operating conditions. In this paper we report first experimental results using ALT-I in conjunction with high power ICRF heating. The particle removal rate increases as the edge flux and density increase during the ICRF pulse. For a head geometry that collects flux from both electron and ion drift sides, the plasma temperature rise is asymmetric with electron temperature on the electron side increasing more than on the ion side during the ICRF pulse. When ALT-I is the major limiter, the particle fluxes on both sides increase by about the same factor and the particle flux on the ion side is always larger, by a factor of 1.5 to 2 than on the electron side during both ohmic and ICRF periods. The degradation of particle confinement inferred from Langmuir probe measurement is more than a factor of two at a maximum achieved power of 2 MW.
Date: May 1, 1986
Creator: Leung, W.K.; Goebel, D.M.; Conn, R.W.; Dippel, K.H.; Finken, K.H. & Thomas, G.J.
Partner: UNT Libraries Government Documents Department

A different approach to evaluating health effects from radiation exposure

Description: Absorbed dose D is shown to be a composite variable, the product of the fraction of cells hit (I/sub H/) and the mean /open quotes/dose/close quotes/ (hit size) /ovr z/ to those cells. D is suitable for use with high level (HLE) to radiation and its resulting acute organ effects because, since I/sub H/ = 1.0, D approximates closely enough the mean energy density in the cell as well as in the organ. However, with low-level exposure (LLE) to radiation and its consequent probability of cancer induction from a single cell, stochastic delivery of energy to cells results in a wide distribution of hit sizes z, and the expected mean value, /ovr z/, is constant with exposure. Thus, with LLE, only I/sub H/ varies with D so that the apparent proportionality between /open quotes/dose/close quotes/ and the fraction of cells transformed is misleading. This proportionality therefore does not mean that any (cell) dose, no matter how small, can be lethal. Rather, it means that, in the exposure of a population of individual organisms consisting of the constituent relevant cells, there is a small probabililty of particle-cell interactions which transfer energy. The probability of a cell transforming and initiating a cancer can only be greater than zero if the hit size (/open quotes/dose of energy/close quotes/) to the cell is large enough. Otherwise stated, if the /open quotes/dose/close quotes/ is defined at the proper level of biological organization, namely, the cell and not the organ, only a large dose z to that cell is effective. The above precepts are utilized to develop a drastically different approach to evaluation oif risk from LLE, that holds promise of obviating any requirement for the components of the present system: absorbed organ dose, LET, a standard radiation, REB(Q), dose equivalent and rem. 12 refs., 11 ...
Date: January 1, 1988
Creator: Bond, V.P.; Sondhaus, C.A. & Feinendegen, L.E.
Partner: UNT Libraries Government Documents Department

Neutron spin echo study of the reentrant spin glass Eu/sub x/Sr/sub 1-x/S

Description: Neutron spin echo (NSE) experiments were performed on polycrystalline samples of Eu/sub x/Sr/sub 1-x/S for x = 0.4 and 0.54 in the temperature range of 1.2 < T < 10K and for 0.036 < Q < .18 A/sup -1/. The x = 0.4 sample exhibits a paramagnetic (PM) to spin glass (SG) transition near T/sub f/ approx. 2K. In the x = 0.54 sample, large ferromagnetic correlations develop below 5K and a spin-glass state appears at lower temperatures. In the NSE experiment, the spin-spin correlation function, S(Q,t), is measured directly for times between .03 < t < 5 ns. At low temperatures both materials exhibit a weak Q dependence in the dynamics and the spins are essentially frozen over the time range explored. On heating the x = 0.4 sample the spins start to fluctuate more rapidly, but no dramatic change occurs around T/sub f/. On heating the x = 0.54 sample, S (Q,t) decreases rapidly with time. Near the 5K, S(Q,t) is exponential (e/sup -GAMMA t/) with GAMMA being strongly Q dependent. Measurements of the depolarization of the scattered beam confirms the absence of true long range ferromagnetic order below T/sub c/.
Date: January 1, 1984
Creator: Shapiro, S.M.; Maletta, H. & Mezei, F.
Partner: UNT Libraries Government Documents Department

Langmuir probe measurements in the TEXTOR tokamak during ALT-I pump limiter experiments

Description: Langmuir probes have been used to characterize the edge plasma of the TEXTOR tokamak and measure the parameters of the plasma incident on the ALT-I pump limiter during ohmic and ICRH heating. Probes mounted directly on the ALT limiter, and a scanning probe located 90/sup 0/ toroidally from the limiter, provide data for the evaluation of pump limiter performance and its effect on the edge plasma. The edge plasma is characterized by density and flux e-folding lengths of about 1.8cm when ALT is the main limiter. These scrape-off lengths do not vary significantly as ALT is moved between the normal 42-46cm minor radii, but increase to over 2.2cm when ALT is inserted to 40cm. The flux to probes at a fixed position in the limiter shadow varies by less than 25% for core density changes of a factor of five. This suggests that the global particle confinement time tau/sub p/, scales as the core density. Estimates from the probes indicate that tau/sub p/ is on the order of the energy confinement time, tau/sub E/. The edge electron temperature, T/sub e/, typically decreases by a factor of two when the core density is raised from 1 to 4 x 10/sup 13/ cm/sup -3/. The T/sub e/ profile is essentially flat in the limiter shadow, with values of 10-25 eV depending on the core plasma density and ICRH power. ICRH heating increases the electron temperature and flux in proportion to the coupled power. With ALT as the primary limiter and no direct shadowing, the ion side receives 2 to 3 times the flux of the electron side during both ohmic and ICRH heating. The edge plasma is not directly modified by pump limiter operation, but changes with the core plasma density as particle removal lowers the recycling of neutrals in the boundary.
Date: April 1, 1986
Creator: Goebel, D.M.; Campbell, G.A.; Conn, R.W.; Leung, W.K.; Dippel, K.H.; Finken, K.H. et al.
Partner: UNT Libraries Government Documents Department