Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session CC: Applications I |
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Chair: Anton Tonchev, Livermore National Laboratory Room: Hilton Kohala 2 |
Wednesday, October 24, 2018 7:00PM - 7:15PM |
CC.00001: Fission fragment angular distributions measured with the fissionTPC David Hensle, Uwe Greife The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has built a fission time projection chamber (fissionTPC) to study the fission process in a novel way by reconstructing full three-dimensional tracks of fission fragments and other ionizing radiation. While the ultimate goal of the fissionTPC is to measure fission cross section ratios to unprecedented precision, other physics can be studied concurrently with the cross section measurements. Taking advantage of the fissionTPC's tracking ability, fission fragment angular distributions can be measured which is an important experimental observable for understanding the quantum mechanical state of the fissioning nucleus and a parameter required to determine detection efficiency for cross section measurements. Additionally, the amount of linear momentum imparted to the fissioning nucleus by the incident neutron can be inferred by measuring the opening angle between the fission fragments. Preliminary results for $^{235}$U fission fragment angular anisotropy and neutron linear momentum transfer on fissioning $^{235}$U and $^{238}$U as a function of neutron energies in the range $130$~keV$ - 250$~MeV will be presented. |
Wednesday, October 24, 2018 7:15PM - 7:30PM |
CC.00002: Neutron-neutron Correlations in Spontaneous Fission of 252Cf Madison Theresa Andrews, John Paul Lestone Fission neutrons are correlated because the majority of the neutrons are evaporated from fully accelerated fission fragments. This causes neutrons emitted from the same fragment to have a preference to be emitted in the same direction, while neutrons emitted from different fragments have a preference to be emitted in opposite directions. Several options are available in MCNP for generating correlated neutron events. These options are tested by a comparison to 252Cf neutron-neutron correlation data recently collected at Los Alamos. |
Wednesday, October 24, 2018 7:30PM - 7:45PM |
CC.00003: Nuclear reaction study for long-lived fission products in nuclear waste: Proton- and deuteron-induced reactions on 107Pd and 93Zr at 20 - 30 MeV/u Masanori Dozono, Nobuaki Imai, Shin'ichiro Michimasa, Susumu Shimoura, Shinsuke Ota, Toshiyuki Sumikama, Nobuyuki Chiga, Hideaki Otsu, Kotaro Iribe, for ImPACT-RIBF collaboration The nuclear transmutation of long-lived fission products (LLFPs), which are produced in nuclear reactors, is one of the candidate techniques for the reduction and/or reuse of LLFPs. To design optimum pathways of the transmutation process, several nuclear reactions have been studied using LLFPs as secondary beams. The studies indicate that proton- and/or deuteron-induced spallation reactions at intermediate energy (100 - 200 MeV/u) are effective for the LLFP transmutation. For a systematic study, we performed an experiment for the proton- and deuteron-induced reactions on 107Pd and 93Zr at 20 − 30 MeV/u. In this energy region, the fusion evaporation process is dominant. Thus, the reaction-mechanism dependence can be studied by comparison with the high-energy spallation data. The experiment was performed at RIKEN RIBF. The degraded RI beams at 20 - 30 MeV/u were produced by a newly developed beam line, OEDO. To induce the reactions, the high-pressure cooled gas targets (H2 and D2) were used. Reaction residues were analyzed by the SHARAQ spectrometer. In this talk, we will present the details of the experiments and the obtained results. |
Wednesday, October 24, 2018 7:45PM - 8:00PM |
CC.00004: Parameter Optimization of FREYA for Spontaneous Fission Ramona Vogt, Jackson Van Dyke, Lee Allen Bernstein The fast event-by-event fission code FREYA (Fission Reaction Event Yield Algorithm generates large samples of complete fission events. FREYA employs only a few physics-based parameters. We discuss recent results on optimization of these parameters and compare results with the optimized parameters to available data on prompt neutron and photon emission. |
Wednesday, October 24, 2018 8:00PM - 8:15PM |
CC.00005: NEXT: Advanced Fission Reactor Research at an Undergraduate Institution Rusty Towell As the discovery of nuclear fission turns 80 years old, it is unfortunate that this tremendous energy source remains largely unused globally to address the need for abundant, safe, carbon-free energy on demand. This regrettable situation can be rectified with the development of advanced reactors that are capable of meeting the world’s energy needs without the risk of proliferation. To address this challenge, the Nuclear Energy eXperimental Testing (NEXT) Lab has been launched at Abilene Christian University. The NEXT Lab mission is to provide global solutions to the world's needs for energy that is less expensive and safer, water that is pure and abundant, and medical isotopes used to diagnose and treat cancer by advancing the technology of molten salt reactors while educating the next generation of leaders in nuclear science and engineering. The NEXT Collaboration is focusing on advancing the technical readiness level of molten salt as a coolant in liquid fueled molten salt reactor. Our interdisciplinary team of undergraduate students and faculty members is currently commissioning a molten salt test loop that will allow for the testing of new sensors. The current status of NEXT will be presented including the breath of research across many disciplines. |
Wednesday, October 24, 2018 8:15PM - 8:30PM |
CC.00006: Precision β-decay branching ratio measurements for long-lived fission products Karolina Kolos, Amber Marie Hennessy, Nicholas David Scielzo, Victor Iacob, Mark Stoyer, Anton P Tonchev, John Hardy, Mary Burkey, Brian Champine, Jason A Clark, Patrick Copp, Aaron Gallant, Eric B Norman, Rodney Orford, Hyo-In Park, John Rohrer, Daniel Santiago-Gonzalez, Guy Savard, Athan J. Shaka, Shaofei Zhu One of the most straightforward and reliable ways to determine the number of fissions that occurred in a chain reaction is via detection of the characteristic γ rays emitted during the β-decay of the fission products. These γ rays are emitted in only a fraction of the decays, and this fraction must be known accurately to determine the total number of fissions. Many measurements of the β-decay of the long-lived fission products suffer from high uncertainties (even up to 20%) which contributes to the uncertainties in the determined fission yields. We have developed a novel technique to measure (<1% precision) γ-ray intensities and β-decay branching ratios. Our technique takes advantage of radioactive beams from CARIBU facility at Argonne National Lab to produce ultra-pure radioactive samples of fission products, and a nearly 100% efficient 4π β-spectrometer paired with the painstakingly calibrated γ-ray detector [1]. The results of the branching ratios of 95Zr, 144Ce, and 147Nd will be presented. [1] R. G. Helmer, J. C. Hardy, V. E. Iacob, M. Sanchez-Vega, R.G. Neilson, and J. Nelson, NIM Phys. Res., Sect. A 511, 360 (2003). |
Wednesday, October 24, 2018 8:30PM - 8:45PM |
CC.00007: Nuclear Data Requirements for Nuclear Security Applications Micah Johnson Lawrence Livermore National Laboratory (LLNL) is a top-tier US national |
Wednesday, October 24, 2018 8:45PM - 9:00PM |
CC.00008: Integral experiments at the National Ignition Facility for Nuclear Data Validation on Modeled Neutron Flux Spectra Sandra Bogetic, Charles Yeamans, Lee Allen Bernstein, Jasmina Vujic, Dawn Shaughnessy The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is a unique source of neutrons that uses laser inertial confinement to drive the deuterium-tritium fusion reaction. The reaction produces a very high flux output and a monoenergetic 14.06 MeV neutron source peak. With such a strong source, various possibilities are opening up for a list of applications by tailoring the neutron spectra. The presented research focuses on using neutrons with various energies for neutron activation studies and cross section measurements. The idea is to build optimized energy tuning assemblies to "isolate" and emphasize specific energy channels for the validation of known data weaknesses at energies below 14 MeV. UC Berkeley’s newly developed metaheuristic optimization software is used to design ETAs for a series of integral benchmarking experiments. The latter allows to investigate the impact of the nuclear data on materials of interest for NIF’s stewardship. |
Wednesday, October 24, 2018 9:00PM - 9:15PM |
CC.00009: Analysis of Autonomous Load Following (ALF) in Advanced Fast Reactors Brad Kinnamon The Autonomous Load Following (ALF) properties of fast-spectrum nuclear reactors offer great potential for increased electric grid stability, reduction in control rod mechanism wear, and less operator action for small power transients. These features can result in design simplification and enhanced safety of reactor systems. Thermal-hydraulic transients result in reactivity feedback from the coolant to curb power transients and return the reactor to a stable, critical condition. The speed of the reactivity feedback and the resulting limit of ALF controllable transient size are based to a great extent on the intrinsic properties of the coolant and their effects on the reactor kinetics. Lead, Lead Bismuth Eutectic (LBE), and Sodium are the coolants with the most promising options for advanced fast reactors under the Generation IV program. This paper reviews the properties of each coolant type and presents the reactor kinetics modeling results of analyses using the TRACE code to simulate their respective reactivity response for a simplified fast reactor design. This provides insight into a comparison of coolant types based on reactivity feedback and autonomous load following capability in future fast reactor designs. |
Wednesday, October 24, 2018 9:15PM - 9:30PM |
CC.00010: First spectral measurements of a distributed x-ray source with a Compton spectrometer Amanda Elizabeth Gehring, Michelle Anna Espy, Todd Joseph Haines, Jacob Zier Our team at Los Alamos National Laboratory has performed many successful energy-spectra |
Wednesday, October 24, 2018 9:30PM - 9:45PM |
CC.00011: Selective Photoionization of Odd-Mass Zirconium Isotope: Toward Application to Separation of Radioactive Waste Tak Fujiwara, Tohru Kobayashi, Katsumi Midorikawa Isotope separation methods are crucial to numerous scientific and industrial processes; Nuclear power plants require fuels enriched in a select isotope and separate radioactive isotopes for disposal. The odd-mass Zirconium isotopes are among fission products that show radioactive. Separation of such high-level radioactive isotopes may make a pivotal contribution to a way to dispose of waste and recycle non-radiative isotopes. We employed a laser photoionization technique that provides an alternative approach using intermediate-state alignment for isotope-selective laser excitation of atoms, in which exploits the angular momentum selection rules for the absorption of polarized light. We have demonstrated that the 91Zr in the natural substance was selectively photoionized while the photoions of the even-mass isotopes were significantly suppressed by polarized, broadband pulsed lasers. In our four-steps photoexcitation (J=2-1-1-0) scheme, high ionization efficiency with quite a high selectivity (91β >2400) has been achieved. Insights obtained and applications to advances in laser isotope separation will be presented and discussed. |
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