Predicting Fuel Salt Composition via Linear Optimization in Molten Salt Reactors

Molten salt reactors (MSRs) are a class of nuclear reactor which uses a molten ionic liquidas either the coolant or also as the fuel. While a 8 MWth MSR was successfully operatedin the 1960s it was not until the early 2000s that MSRs gained widespread attention. Sincethen MSRs have enjoyed plentiful research support. Despite such support only one generalMSR fuel cycle analysis tool is available for use by the research community and even thisthis tool lacks features necessary for modelling a MSR, and so possibly providing answers ofa lower quality.In this work a method is proposed and implemented within the SERPENT 2 reactorphysics Monte-Carlo code. This method, named ADER - the Advanced Depletion Extensionfor Reprocessing - is a seamlessly incorporated source code modification to the SERPENT2 base code which allows the user to define arbitrary collections of elements, isotopes, andchemicals as well as relationships among them.Furthermore ADER allows the user to specify a variety of mass flows subject to theconstraints as defined through the collections of elements, isotopes, and chemicals the userhas structured. Along with support for constraints involving both corrosion and nuclearcontrol concerns, ADER allows the user to optimize the solution against a quantity of interest- e.g, total uranium fed into the system.Through these structures much of the complex chemistry, corrosion modelling, and nuclear concerns of operating a MSR can be linearized and solved against an optimizationtarget, which is necessary given the large number of constraints and variables in such aproblem space. Linearization reduces the problem complexity and eliminates concerns overlocal versus global optimization targets. Within the typically narrow operating parametersof MSRs linearization is an appropriate approximation to the higher dimensional equationsrepresenting the phenomenon involved.2This linear system and optimization target may then be passed to a linear optimizationsolver, in this work the CLP library as part of the COIN-OR package, from which an optimized system material composition and material flows solution may be found. ADER thenuses this solution to create a brand new depletion matrix which SERPENT 2 then solvesusing the CRAM approximation method.From this algorithm a more accurate modelling of MSR fuel cycles and physics maybe arrived at through the consideration of chemistry driven limitations, corrosion drivenlimitations, nuclear driven limitations, and operator driven limitations. Results from thisimplemented method indicate that ADER drives the MSR fuel cycle simulations towardsa more physically representative result. Unfortunately, as detailed later in this work, anunderlying and pernicious numerical instability issue was uncovered within the linear optimization library selected for this work. Any future work on this method must begin with theadoption of a quadruple-precision floating-point linear optimization library over the currentimplementation of CLP as used in ADER.In the following chapters an introduction to MSRs and their fuel cycle modelling isgiven. Following this the theory behind ADER and its implementation within SERPENT 2is discussed after which the results from one of the less numerically unstable simulations ispresented after which concluding remarks are given

YF-17/ADEN system study

The YF-17 aircraft was evaluated as a candidate nonaxisymmetric nozzle flight demonstrator. Configuration design modifications, control system design, flight performance assessment, and program plan and cost we are summarized. Two aircraft configurations were studied. The first was modified as required to install only the augmented deflector exhaust nozzle (ADEN). The second one added a canard installation to take advantage of the full (up to 20 deg) nozzle vectoring capability. Results indicate that: (1) the program is feasible and can be accomplished at reasonable cost and low risk; (2) installation of ADEN increases the aircraft weight by 600 kg (1325 lb); (3) the control system can be modified to accomplish direct lift, pointing capability, variable static margin and deceleration modes of operation; (4) unvectored thrust-minus-drag is similar to the baseline YF-17; and (5) vectoring does not improve maneuvering performance. However, some potential benefits in direct lift, aircraft pointing, handling at low dynamic pressure and takeoff/landing ground roll are available. A 27 month program with 12 months of flight test is envisioned, with the cost estimated to be $15.9 million for the canard equipped aircraft and$13.2 million for the version without canard. The feasiblity of adding a thrust reverser to the YF-17/ADEN was investigated

A study of the structure of jet turbulence producing jet noise

Characteristics of turbulent structure of mixing region near outlet of circular subsonic jet and production of jet nois

Quality of Condensate from Air-Handling Units

Areas with humid climates, such as Georgia, are currently experiencing a severe drought. Collecting condensate from large AHUs for on-site use is compelling, but how do you assess the quality of this water? The authors discuss how condensate from properly maintained large AHUs is high-quality water. They go on to explain how system design and maintenance affect its quality, and they give the readers guidance for how to use the condensate for on-site application

Supermetallic conductivity in bromine-intercalated graphite

Exposure of highly oriented pyrolytic graphite to bromine vapor gives rise to in-plane charge conductivities which increase monotonically with intercalation time toward values (for ~6 at% Br) that are significantly higher than Cu at temperatures down to 5 K. Magnetotransport, optical reflectivity and magnetic susceptibility measurements confirm that the Br dopes the graphene sheets with holes while simultaneously increasing the interplanar separation. The increase of mobility (~ 5E4 cm^2/Vs at T=300 K) and resistance anisotropy together with the reduced diamagnetic susceptibility of the intercalated samples suggests that the observed supermetallic conductivity derives from a parallel combination of weakly-coupled hole-doped graphene sheets.Comment: 5 pages, 4 figure

Electrodynamics near the Metal-to-Insulator Transition in V3O5

The electrodynamics near the metal-to-insulator transitions (MIT) induced, in V3O5 single crystals, by both temperature (T) and pressure (P) has been studied by infrared spectroscopy. The T- and P-dependence of the optical conductivity may be explained within a polaronic scenario. The insulating phase at ambient T and P corresponds to strongly localized small polarons. Meanwhile the T-induced metallic phase at ambient pressure is related to a liquid of polarons showing incoherent dc transport, in the P-induced metallic phase at room T strongly localized polarons coexist with partially delocalized ones. The electronic spectral weight is almost recovered, in both the T and P induced metallization processes, on an energy scale of 1 eV, thus supporting the key-role of electron-lattice interaction in the V3O5 metal-to-insulator transition.Comment: 7 pages, 5 figure

Infrared phonon dynamics of multiferroic BiFeO3 single crystal

We discuss the first infrared reflectivity measurement on a BiFeO3 single crystal between 5 K and room temperature. The 9 predicted ab-plane E phonon modes are fully and unambiguously determined. The frequencies of the 4 A1 c-axis phonons are found. These results settle issues between theory and data on ceramics. Our findings show that the softening of the lowest frequency E mode is responsible for the temperature dependence of the dielectric constant, indicating that the ferroelectric transition in BiFeO3 is soft-mode driven.Comment: 5 pages (figures included