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  1. MSR Transient Simulation and MSRE Transient Benchmark with SAM and SPECTRA

    Fei, Tingzhou ; Stempniewicz, Marek ; Bertocchi, Fulvio ; ... - Nuclear Technology
    In recent years, there has been renewed interest in molten salt reactors (MSRs) for their potential advantages compared to reactors that rely on solid fuel. In response to such interest, many methods and codes have been developed to capture the unique features of MSRs. Among them, SPECTRA and SAM are two system analysis codes that have been enhanced to include MSR-specific modeling capabilities, including delayed neutron precursor drift and modified point kinetics equations.This paper discusses the efforts taken to verify and validate these features. A standard MSR system test problem was developed to verify and demonstrate the capability of SPECTRAmore » and SAM on the MSR transient simulation. Sixteen transients were simulated. Further, the results obtained from SPECTRA and SAM show good agreement. The Molten Salt Reactor Experiment transient experiments were reviewed and selected to validate the SPECTRA and SAM codes. The experiments included pump startup and coastdown tests at zero power, reactivity insertion tests at different power levels, frequency tests, and a natural convection test. The simulation results from SPECTRA and SAM show good agreement with the experimental data.« less

  2. Intrinsic torque reversals induced by magnetic shear effects on the turbulence spectrum in tokamak plasmas

    Lu, Z. X. ; Wang, W. X. ; Diamond, P. H. ; ... - Physics of Plasmas
    We report that intrinsic torque, which can be generated by turbulent stresses, can induce toroidal rotation in a tokamak plasma at rest without direct momentum injection. Reversals in intrinsic torque have been inferred from the observation of toroidal velocity changes in recent lower hybrid current drive (LHCD) experiments. Here we focus on understanding the cause of LHCD-induced intrinsic torque reversal using gyrokinetic simulations and theoretical analyses. A new mechanism for the intrinsic torque reversal linked to magnetic shear (sˆ) effects on the turbulence spectrum is identified. This reversal is a consequence of the ballooning structure at weak sˆ . Basedmore » on realistic profiles from the Alcator C-Mod LHCD experiments, simulations demonstrate that the intrinsic torque reverses for weak sˆ discharges and that the value of sˆ crit is consistent with the experimental results sˆ expcrit [Rice et al., Phys. Rev. Lett. 111, 125003 (2013)]. In conclusion, the consideration of this intrinsic torque feature in our work is important for the understanding of rotation profile generation at weak and its consequent impact on macro-instability stabilization and micro-turbulence reduction, which is crucial for ITER. It is also relevant to internal transport barrier formation at negative or weakly positive sˆ .« less

  3. Future Challenges for Nuclear Data Research in Fission

    Chadwick, Mark B. - Journal of the Korean Physical Society
    I describe some high priority research areas in nuclear fission, where applications in nuclear reactor technologies and in modeling criticality in general are demanding higher accuracies in our databases. Here, we focus on fission cross sections, fission neutron spectra, and fission product data.

  4. Ambient betatron motion and its excitation by ``ghost lines'' in Tevatron

    Shiltsev, Vladimir ; Stancari, Giulio ; Valishev, Alexander - Journal of Instrumentation
    Transverse betatron motion of the Tevatron proton beam is measured and analysed. It is shown that the motion is coherent and excited by external sources of unknown origins. The observations of the time varying “ghost lines“ in the betatron spectra are reported.

  5. Shielding experiments by the JASMIN Collaboration at Fermilab (II) - radioactivity measurement induced by secondary particles from the anti-proton production target

    Hiroshi, Yashima ; Norihiro, Matsuda ; Yoshimi, Kasugai ; ... - Journal of the Korean Physical Society
    The JASMIN Collaboration has performed an experiment to conduct measurements of nuclear reaction rates around the anti-proton production (Pbar) target at the Fermi National Accelerator Laboratory (FNAL). At the Pbar target station, the target, consisting of an Inconel 600 cylinder, was irradiated by a 120 GeV/c proton beam from the FNAL Main Injector. The beam intensity was 3.6 x 1012 protons per second. The samples of Al, Nb, Cu, and Au were placed near the target to investigate the spatial and energy distribution of secondary particles emitted from it. After irradiation, the induced activities of the samples were measured bymore » studying their gamma ray spectra using HPGe detectors. The production rates of 30 nuclides induced in Al, Nb, Cu, Au samples were obtained. These rates increase for samples placed in a forward (small angle) position relative to the target. The angular dependence of these reaction rates becomes larger for increasing threshold energy. These experimental results are compared with Monte Carlo calculations. The calculated results generally agree with the experimental results to within a factor of 2 to 3.« less

  6. Production of Pions, Kaons, and Protons in pp Collisions at $$\sqrt{s}$$ = 900 GeV with ALICE at the LHC

    Aamodt, K. ; Abel, N. ; Abeysekara, U. ; ... - European Physical Journal. C, Particles and Fields
    The production of $π^+$, $π^–$, $$\hbox{K}^+$$, $$\hbox{K}^–$$, $$p$$, and $$\overline p$$ at mid-rapidity has been measured in proton-proton collisions at $$\sqrt{s}$$ = 900 GeV with the ALICE detector. Particle identification is performed using the specific energy loss in the inner tracking silicon detector and the time projection chamber. In addition, time-of-flight information is used to identify hadrons at higher momenta. Finally, the distinctive kink topology of the weak decay of charged kaons is used for an alternative measurement of the kaon transverse momentum ($$p_t$$) spectra. Since these various particle identification tools give the best separation capabilities over different momentum ranges,more » the results are combined to extract spectra from $$p_t$$=100 MeV/c to 2.5 GeV/c. The measured spectra are further compared with QCD-inspired models which yield a poor description. The total yields and the mean $$p_t$$ are compared with previous measurements, and the trends as a function of collision energy are discussed.« less

  7. Strange particle production in proton–proton collisions at $$\sqrt{s}=0.9$$ $$\mbox {$${\rm TeV}$$}$$ with ALICE at the LHC

    Aamodt, K. ; Abrahantes Quintana, A. ; Adamová, D. ; ... - European Physical Journal. C, Particles and Fields
    The production of mesons containing strange quarks ($$K^0_S$$, Φ) and both singly and doubly strange baryons ($$Λ, \overline Λ$$, and $$\Xi^– + \overline {\Xi}^+$$) are measured at mid-rapidity in pp collisions at $$\sqrt{s}$$ = 0.9 TeV with the $$\hbox{ALICE}$$ experiment at the $$\hbox{LHC}$$. The results are obtained from the analysis of about 250 k minimum bias events recorded in 2009. Measurements of yields (d$$N$$ / d$$y$$) and transverse momentum spectra at mid-rapidity for inelastic pp collisions are presented. For mesons, we report yields ($$\langle$$ d$$N$$ / d$$y\rangle$$) of $0.184 ± 0.002(stat.) ± 0.006(syst.)$ for $$K^0_S$$ and $0.021 ± 0.004(stat.) ±more » 0.003(syst.)$ for Φ. For baryons, we find ($$\langle$$ d$$N$$ / d$$y\rangle$$) = $0.048 ± 0.001(stat.)± 0.004(syst.)$ for $$Λ$$, $0.047 ± 0.002(stat.) ± 0.005(syst.)$ for $$\overline Λ$$ and $0.0101 ± 0.0020(stat.) ± 0.0009(syst.)$ for $$\Xi^– + \overline {\Xi}^+$$. The results are also compared with predictions for identified particle spectra from $$\hbox{QCD}$$-inspired models and provide a baseline for comparisons with both future pp measurements at higher energies and heavy-ion collisions.« less

  8. A study of competitive adsorption of organic molecules onto mineral oxides using DRIFTS

    Kelley, Michael J. - Journal of Colloid and Interface Science
    In this study, analysis of DRIFTS spectra was used for a quantitative study of competitive adsorption of myristic and salicylic acids onto kaolinite or γ-alumina. Peaks unique to the ring or the chain were selected and single molecule studies used as calibration. Samples were exposed to hexane solution containing equal molecular quantities of each acid. The surface loading of salicylic acid was not influenced by the presence of myristic acid on either mineral but the maximum loading of myristic acid was decreased (46-50%) by salicylic acid. Displacement of myristic acid from {gamma}-alumina, but not kaolinite, was observed when excess salicylicmore » acid remained in solution. A 25% increase in the maximum loading was observed for kaolinite, but not for{gamma}-alumina. On {gamma}-alumina, after a loading of 1 molecule per nm2, increased exposure resulted in salicylic acid adsorption only, this value is approximately the same for salicylic acid adsorption from aqueous solution or for water washed hexane treated samples. Thus a set of sites for adsorption of either acid is indicated together with other energetically less favorable sites, which can be occupied by salicylic, but not by myristic, acid.« less

  9. X-Ray Thomson-Scattering Measurements of Density and Temperature in Shock-Compressed Beryllium

    Lee, H. J. ; Neumayer, P. ; Castor, J. ; ... - Physical Review Letters
    We present the first x-ray scattering measurements of the state of compression and heating in laser irradiated solid beryllium. The scattered spectra at two different angles show Compton and plasmon features indicating a dense Fermi-degenerate plasma state with a Fermi energy above 30 eV and with temperatures in the range of 10 eV to 15 eV. These measurements indicate compression by a factor of three in agreement with Hugoniot data and detailed radiation hydrodynamic modeling.

  10. Harmonic generation in Nd : laser-produced plasmas

    McLean, E. A. ; Stamper, J. A. ; Ripin, B. H. ; ... - Applied Physics Letters
    Herein the fundamental and second through the fifth harmonic spectral lines have been observed from the plasma produced when a 75-psec Nd : glass laser (~1016 W/cm2) is focused onto a thick planar polystyrene target. Both line profiles and relative intensities of these harmonic are given.
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