Ryan Bratton Email & Phone Number

Los Alamos, New Mexico

I currently support programs that seek to quantify the attractiveness of nuclear materials.

Los Alamos, New Mexico

My current research involves modeling the European Power Reactor (EPR) in eighth-core geometry in MCNP and MONTEBURNS to quantify spent nuclear fuel (SNF) isotopics and dose rates at the time of discharge and up to after 150 years of storage. I will also characterize the material bred in the EPR spent fuel that the US-DOE recognizes as weapon usable; namely, reactor-grade (RG) Am, Np, and Pu. Since the EPR is capable of operating on an entire core fueled by RG-Pu, I will also simulate the recycling of all or some of the actinides produced in the EPR. Additionally I will simulate short cycling of recycled actinides and characterize the composition and dose of the short-cycled spent fuel. After being granted my clearance, I will begin training to become a member of the SPIKE team, who is currently sponsored by NA-211 and NA-82.

Saint-Paul-Lès-Durance, France

Research, develop, and optimize sodium fast reactor (SFR) assembly designs to increase core stability during unprotected transients of power (UTOP) through increased neutron moderation and flux spectrum manipulation. The aim of the COnception de COeurs Naturellement Sûrs (COCONS, English: Designing naturally safe reactor cores) safety approach is to minimize the consequences of an Unprotected Transient Of Power (UTOP) which could result in sodium voiding or fuel melting. A crucial reactivity coefficient with respect to the fuel temperature is the Doppler effect where an increase in the fuel temperature leads to a decrease in reactivity. The primary objective of the Coeur A effect DOppler Renforcé (CADOR) project is to increase core stability and safety by reinforcing the Doppler effect. One viable strategy to achieve this goal is to increase the Doppler coefficient by modifying the neutron spectrum of the sodium cooled fast reactor (SFR) core through the use of a moderating material such as Beryllium. Moderating of the neutron spectrum in a SFR core will shift the neutron energies to energies that correspond to resonance capture regions of isotopes in the nuclear fuel, primarily U-238. An increase in the fuel temperature will increase the rate of neutron absorption at these energies and thus increase the Doppler effect more significantly than when compared to a similar increase in temperature for a non-moderated system.

Oak Ridge, Tennessee, Usa

Program: Graduate Opportunities (GO!)The safe transportation and storage spent nuclear fuel (SNF) is a chief concern of the nuclear industry. Because of the lack of reprocessing in the United States (US), the safe short-, mid-, and long-term storage of SNF is especially important, with modeling and experiment playing important roles in determining the infrastructure required to ensure safe storage and transportation. The quantification of distribution of the rod internal pressure (RIP) and the cladding stress for every fuel rod of a well-defined reactor system provides insight into the portion of fuel rods that could potentially experience significant hydride reorientation or a cladding failure during the vacuum drying process. Further, any fuel rods that are identified as in danger of a cladding failure could have their operational histories and manufacturing information analyzed to determine the cause of its elevated cladding stress or RIP. In this work, the discharge RIP and cladding hoop stress (CHS) distributions are quantified for Watts Bar Nuclear Unit 1 (WBN1) fuel rods by modeling the specific operational history and fabrication data of each fuel rod in FRAPCON-3.5. A methodology is developed which tracks inter-cycle assembly movements and assembly batch fabrication information to build individual FRAPCON inputs for each considered WBN1 fuel rod. An alternate model for the amount of helium released from zirconium diboride integral fuel burnable absorber (IFBA) liners is derived and applied to FRAPCON output data to quantify the RIP and CHS for these fuel rods. SCALE/Polaris is used to quantify fuel rod-specific spectral quantities and the amount of gaseous fission products produced in the fuel for use in FRAPCON inputs.

Oak Ridge, Tennessee, Usa

Program: Nuclear Engineering Science Laboratory Synthesis (NESLS)In 2012, the GC-859 (previously known as RW-859) database format used to store the details of the U.S. UNF inventory was changed to remove some assembly design detail, e.g., assemblies formerly labeled as “Westinghouse 17x17 OFA” and “Westinghouse 17x17 LOPAR” were changed to simply “Westinghouse 17x17”. In this work, we have initiated an investigation of the uncertainty introduced by this simplification. Research presented at the 2014 NESLS poster session (poster is attached).

Oak Ridge, Tennessee, Usa

Program: Nuclear Engineering Science Laboratory Synthesis (NESLS)The purpose of this study is to rigorously investigate whether a significant bias in isotopics calculations may be found for a well-defined radiochemical assay (RCA) benchmark. Biases of modeling parameters and sources of model uncertainty are estimated using comparisons to higher-fidelity models. Significant sources of uncertainty are modeled using the new Sampler module of SCALE. The isotopic measurements that are used for this study are for rod MKP109 (assembly D047) of the Calvert Cliffs Unit 1 Reactor.Research presented at 2013 NESLS poster session (poster is attached).Research presented at PHYSOR 2014 (The Role of Reactor Physics toward a Sustainable Future) in Kyoto, Japan.

Oxford, Ohio, Usa

Ring-substituted derivatives of 2-(4-aminophenyl)benzothiazole, 1a, 1b−g, are under development as antitumor agents. One derivative, 1f, has reached phase 1 clinical trials as the prodrug 2f, Phortress (NSC 710305). These amines are activated by CYP450 1A1, apparently into hydroxylamines 8a−g that are likely metabolized into esters that ionize into nitrenium ions responsible for cellular damage. Previously we showed that 9a, the acetic acid ester of 8a, generates the long-lived (530 ns) nitrenium ion 11a by hydrolysis or photolysis in water. In this study, azide trapping shows that 9b−g generate 11b−g via rate-limiting N−O heterolysis. Ion lifetimes, estimated from azide/solvent selectivities, range from 250 to 1150 ns with identical lifetimes for 11a and 11f. Differences in biological activity of the amines are likely not due to differences in the chemistry of the cations but to differences in metabolic activation/ deactivation of individual amines. Unlike the nitrenium ions, lifetimes of the esters are strongly dependent on the 3′-Me substituent. Esters containing 3′-Me (9b, 9f, 9g) have lifetimes of 5−10 s compared to 400−800 s for esters without 3′-Me (9a, 9c, 9d, 9e). This restricts 3′-Me esters to cells/tissues in which activation occurs, concentrating their effects in tumor cells if metabolism is restricted to those cells.Research published in the Journal of Organic Chemistry (DOI: 10.1021/jo400826f)

Gaithersburg, Maryland, Usa

Program: Summer Undergraduate Research Fellowship (SURF)This report outlines the determination of a reaction mechanism that can be manipulated to develop directed syntheses of gold monolayer-protected clusters (MPCs) prepared by reduction of solutions containing 1,3-bis(diphenylphosphino)propane (L³) ligand and Au(PPh₃)Cl. Nanocluster synthesis was initiated by reduction of two-coordinate phosphine-ligated [AuⁱLL'​]+ complexes (L, L'​ = PPh₃, L³), resulting in free radical complexes. The [Au⁰LL'] free radicals nucleated, forming a broad size distribution of ligated clusters. Timed UV-vis spectroscopy and electrospray ionization mass spectrometry monitored the ligated Aux, 6 ≤ x ≤ 13, clusters, which comprise reaction intermediates and final products. By employing different solvents and reducing agents, reaction conditions were varied to highlight the largest portion of the reaction mechanism. We identified several solution-phase reaction classes, including dissolution of the gold precursor, reduction, continuous nucleation/ core growth, ligand exchange, ionmolecule reactions, and etching of colloids and larger clusters. Simple theories can account for the reaction intermediates and final products. The initial distribution of the nucleation products contains mainly neutral clusters. However, the rate of reduction controls the amount of reaction overlap occurring in the system, allowing a clear distinction between reduction/nucleation and subsequent solution-phase processing. During solution-phase processing, the complexes undergo core etching and core growth reactions, including reactions that convert neutral clusters to cations, in a cyclic process that promotes formation of stable clusters of specific metal nuclearity. These processes comprise “size-selective” processing that can narrow a broad distribution into specific nuclearities, enabling development of tunable syntheses.Research published in Journal of Inorganic Chemistry C (DOI: 10.1021/ic2018506).

Doctor Of Philosophy (Ph.D.), Nuclear Engineering

Activities and Societies: Teaching Assistant• Doctoral candidacy exam passed: January 29, 2013 • Comprehensive exam passed: December 11.

Bachelor Of Science (B.S.), Physics And Biochemistry

Activities and Societies: Undergraduate Assistant & Physics Tutor (January 2018 - May 2008). Miami University Police Department (MUPD).