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Quantifying the Sensitivity of Condition Incidence Parameters in the Evidence Library

One approach to quantifying spaceflight risk at NASA makes use event driven probabilistic techniques. The Medical Extensible Dynamic Probabilistic Risk Assessment Tool (MEDPRAT) is such a tool that estimates medical risk metrics via simulation and enables optimization of medical resources subject to mission constraints [1]. Previous analyses have informed medical set composition, exercise countermeasures, and water intake, where each analysis quantifies the risk associated with proposed variations in system design. As future mission profiles extend beyond Low-Earth Orbit (LEO) and lengthen in duration, understanding these risks and contributing factors is critical. MEDPRAT employs Monte Carlo sampling techniques to simulate missions and track the occurrence of medical events. These events follow fault-tree-like progressions through levels of severity and mitigation via medical treatment to many possible outcomes and these are reported throughout the mission. Making this possible, are the medical databases that contain evidence gathered by the Human Research Program (HRP). Quantifying the impact of uncertainty or variability in the input data is an important step in evaluating the credibility of modeling and simulation results. In this work, we investigate the sensitivity of medical risk metrics with respect to the condition incidence parameters within the Evidence Library (EL) [2] as the medical database input for MEDPRAT. The medical conditions, contained in the EL, are equipped with incidence rates that describe the likelihood that the condition will occur. These incidence rates reflect historical spaceflight data or when appropriate, terrestrial data. In this presentation, we will explore how uncertainty in these rates propagate to the medical risk described by MEDPRAT. These results identify the conditions and parameters with the largest contribution to medical risks.

Ian Lim↗

DOE OSTI2011

FPC conditioning cart at BNL

The 703 MHz superconducting gun for the BNL Energy Recovery Linac (ERL) prototype has two fundamental power couplers (FPCs), and each of them will deliver up to 500 kW of CW RF power. In order to prepare the couplers for high power RF service and process multipacting, the FPCs should be conditioned prior to installation into the gun cryomodule. A conditioning cart based test stand, which includes a vacuum pumping system, controllable bake-out system, diagnostics, interlocks and data log system has been designed, constructed and commissioned by collaboration of BNL and AES. This paper presents FPC conditioning cart systems and the conditioning process.

43 PARTICLE ACCELERATORS↗

DOE OSTI2012

Design, simulation and conditioning of the fundamental power couplers for BNL SRF gun

The 704 MHz SRF gun for the BNL Energy Recovery Linac (ERL) prototype uses two fundamental power couplers (FPCs) to deliver up to 1 MW of CW RF power to the half-cell cavity. To prepare the couplers for high-power RF service and process multipacting, the FPCs should be conditioned prior to installation into the gun cryomodule. A room-temperature test stand was configured for conditioning FPCs in full reflection regime with varied phase of the reflecting wave. The FPCs have been conditioned up to 250 kW in pulse mode and 125 kW in CW mode. The multipacting simulations were carried out with Track3P code developed at SLAC. The simulations matched the experimental results very well. This paper presents the FPC RF and thermal design, multipacting simulations and conditioning of the BNL gun FPCs.

43 PARTICLE ACCELERATORS↗

DOE OSTI2013

Understanding Sulfur Poisoning and Regeneration of Nickel Biomass Conditioning Catalysts using X-Ray Absorption Spectroscopy

The production of biofuels can proceed via a biomass gasification to produce syngas, which can then undergo catalytic conditioning and reforming reactions prior to being sent to a fuel synthesis reactor. Catalysts used for biomass conditioning are plagued by short lifetimes which are a result of, among other things, poisoning. Syngas produced from biomass gasification may contain between 30-300 ppm H2S, depending on the feedstock and gasification conditions, and H2S is a key catalyst poison. In order to overcome catalyst poisoning, either an H2S-tolerant catalyst or an efficient regeneration protocol should be employed. In this study, sulfur K-edge X-ray absorption near edge spectroscopy (XANES) was used to monitor sulfur species on spent catalyst samples and the transformation of these species from sulfides to sulfates during steam and air regeneration on a Ni/Mg/K/Al2O3 catalyst used to condition biomass-derived syngas. Additionally, nickel K-edge EXAFS and XANES are used to examine the state of nickel species on the catalysts. Post-reaction samples showed the presence of sulfides on the H2S-poisoned nickel catalyst and although some gaseous sulfur species were observed to leave the catalyst bed during regeneration, sulfur remained on the catalyst and a transformation from sulfides to sulfates was observed. The subsequent H2 reduction led to a partial reduction of sulfates back to sulfides. A proposed reaction sequence is presented and recommended regeneration strategies are discussed.

09 BIOMASS FUELS↗

DOE OSTI2015

Conditioning biomass for microbial growth

The present invention relates to methods for improving the yield of microbial processes that use lignocellulose biomass as a nutrient source. The methods comprise conditioning a composition comprising lignocellulose biomass with an enzyme composition that comprises a phenol oxidizing enzyme. The conditioned composition can support a higher rate of growth of microorganisms in a process. In one embodiment, a laccase composition is used to condition lignocellulose biomass derived from non-woody plants, such as corn and sugar cane. The invention also encompasses methods for culturing microorganisms that are sensitive to inhibitory compounds in lignocellulose biomass. The invention further provides methods of making a product by culturing the production microorganisms in conditioned lignocellulose biomass.

09 BIOMASS FUELS↗

DOE OSTI2015

Store operation with conditional push of a tag value to a queue

According to one embodiment, a method for a store operation with a conditional push of a tag value to a queue is provided. The method includes configuring a queue that is accessible by an application, setting a value at an address in a memory device including a memory and a controller, receiving a request for an operation using the value at the address and performing the operation. The method also includes the controller writing a result of the operation to the address, thus changing the value at the address, the controller determining if the result of the operation meets a condition and the controller pushing a tag value to the queue based on the condition being met, where the tag value in the queue indicates to the application that the condition is met.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2015

Method for characterization of the redox condition of cementitious materials

Disclosed are methods for determining the redox condition of cementitious materials. The methods are leaching methods that utilize an in situ redox indicator that is present in the cementitious materials as formed. The in situ redox indicator leaches from cementitious material and, when the leaching process is carried out under anaerobic conditions can be utilized to determine the redox condition of the material. The in situ redox indicator can exhibit distinct characteristics in the leachate depending upon the redox condition of the indicator.

36 MATERIALS SCIENCE↗

DOE OSTI2015

RF Conditioning of the Photo-Cathode RF Gun at the Advanced Photon Source - NWA RF Measurements

A new S-band Photo-cathode (PC) gun was recently installed and RF conditioned at the Advanced Photon Source (APS) Injector Test-stand (ITS) at Argonne National Lab (ANL). The APS PC gun is a LCLS type gun fabricated at SLAC [1]. The PC gun was delivered to the APS in October 2013 and installed in the APS ITS in December 2013. At ANL, we developed a new method of fast detection and mitigation of the guns internal arcs during the RF conditioning process to protect the gun from arc damage and to RF condition more efficiently. Here, we report the results of RF measurements for the PC gun and an Auto-Restart method for high power RF conditioning.

Smith, T. L.↗

DOE OSTI2017

MODELING THE AMBIENT CONDITION EFFECTS OF AN AIR-COOLED NATURAL CIRCULATION SYSTEM

The Reactor Cavity Cooling System (RCCS) is a passive safety concept under consideration for the overall safety strategy of advanced reactors such as the High Temperature Gas-Cooled Reactor (HTGR). One such variant, air-cooled RCCS, uses natural convection to drive the flow of air from outside the reactor building to remove decay heat during normal operation and accident scenarios. The Natural convection Shutdown heat removal Test Facility (NSTF) at Argonne National Laboratory (“Argonne”) is a half-scale model of the primary features of one conceptual air-cooled RCCS design. The facility was constructed to carry out highly instrumented experiments to study the performance of the RCCS concept for reactor decay heat removal that relies on natural convection cooling. Parallel modeling and simulation efforts were performed to support the design, operation, and analysis of the natural convection system. Throughout the testing program, strong influences of ambient conditions were observed in the experimental data when baseline tests were repeated under the same test procedures. Thus, significant analysis efforts were devoted to gaining a better understanding of these influences and the subsequent response of the NSTF to ambient conditions. It was determined that air humidity had negligible impacts on NSTF system performance and therefore did not warrant consideration in the models. However, temperature differences between the building exterior and interior air, along with the outside wind speed, were shown to be dominant factors. Combining the stack and wind effects together, an empirical model was developed based on theoretical considerations and using experimental data to correlate zero-power system flow rates with ambient meteorological conditions. Some coefficients in the model were obtained based on best fitting the experimental data. The predictive capability of the empirical model was demonstrated by applying it to the new set of experimental data. The empirical model was also implemented in the computational models of the NSTF using both RELAP5-3D and STARCCM+ codes. Accounting for the effects of ambient conditions, simulations from both codes predicted the natural circulation flow rates very well.

Hu, Rui↗

DOE OSTI2016

FUEL PERFORMANCE MODELING OF FECRAL CLADDING FAILURE DURING LOSS OF COOLANT CONDITIONS

Accident tolerant materials are defined as those that provide significantly increased response time in the event of an accident while providing similar or improved performance as the conventional UO2/Zircaloy-4 fuel rods during normal operation. One avenue for materials to demonstrate enhanced accident tolerance is to have improved reaction (e.g., oxidation) kinetics with steam, resulting in slower hydrogen (or other combustible gases) generation rate, while maintaining acceptable thermo-mechanical properties, fuel-clad interactions, and fission product behavior. Due to their improved reaction kinetics with steam compared to Zircaloy-4, iron-chromium-aluminum (FeCrAl) alloys are being considered as an accident tolerant cladding material. In order to determine whether FeCrAl alloys are indeed accident tolerant materials, comparisons between conventional zirconium-based claddings under accident conditions is required. To this end, we have developed a burst (failure) criterion for FeCrAl using existing experimental data for first-generation alloys. This model was incorporated into the BISON fuel performance code to perform comparative studies with Zircaloy-4 cladding tubes under non-oxidizing and oxidizing LOCA conditions. The separate effects LOCA conditions considered were adopted from the PUZRY and REBEKA test series. Due to the fact that FeCrAl alloys have a larger thermal absorption cross-section and higher stiffness than Zircaloy-4, cladding thickness will be smaller for FeCrAl than for Zircaloy-4. Three different cladding thicknesses were analyzed in this work. The results indicate that for both non-oxidizing (PUZRY) and oxidizing (REBEKA) LOCA conditions, FeCrAl has similar burst behavior (i.e., time to burst and pressure at burst) as Zircaloy-4. It should be noticed that this study used data for first-generation FeCrAl alloys to develop the burst criterion. Although no burst data?currently exists for C35M (a second-generation FeCrAl alloy under development at Oak Ridge National Laboratory), improved burst behavior is anticipated. As burst data for C35M becomes available the burst criterion will be updated and the simulations revisited to determine the accident tolerance of second-generation FeCrAl alloys.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2018

Heat transfer assemblies, systems, and methods for conditioning a medium

Embodiments of the invention are directed to heat exchanger assemblies, systems, and methods for conditioning medium in an environment (e.g., in a controlled environment) to a suitable temperature. In particular, embodiments may include heat transfer assemblies and medium conditioning systems that may condition the medium in the environment by raising or lowering temperature thereof to a suitable conditioned temperature.

42 ENGINEERING↗

DOE OSTI2019

Effect of Material Condition on Stress Corrosion Crack Initiation of Cold-Worked Alloy 600 in Simulated PWR Primary Water

The effect of material condition and grain boundary (GB) carbides on stress corrosion crack (SCC) initiation was evaluated on a cold-worked Alloy 600 heat in the solution annealed and thermally treated conditions. SCC initiation response of these material conditions were investigated by constant load testing in simulated pressurized water reactor primary coolant environments. Direct current potential drop technique was used for in-situ detection of SCC initiation. With periodic examination of the specimens, evolution of precursor damage including intergranular attack and short cracks was carefully documented and compared to data previously obtained from unstressed coupons with the same material conditions and were exposed to the same environment. Results revealed a predominant role of mechanical factors in the development of precursor damage with no apparent improvement of GB carbides on SCC initiation resistance.

Zhai, Ziqing↗

DOE OSTI2020

Numerical study of heat transfer enhancement in laminar and turbulent flow in enhanced tubes with uniform and non-uniform thermal boundary conditions

Various types of tube enhancements have been proposed in order to increase heat transfer while minimizing any associated increases in pressure drop. This paper presents a numerical study of two different types of enhanced tubes: the relatively common twisted tape insert tube, and a novel tube with airfoil shaped pins on the inner surface. Each tube is studied in both the laminar and turbulent flow regime. In addition to the typical constant temperature and constant flux boundary conditions, a non-constant heat flux boundary condition is applied on one half of the tube, a situation which may be encountered when absorbing solar radiation. In general, each type of enhanced tube offers a thermal performance factor greater than unity at certain Re. In addition, the non-uniform heat flux boundary condition appears to function similarly as the uniform heat flux boundary condition.

Sandlin, Matthew J.↗

DOE OSTI2017

Fuel performance modeling of FeCrAl cladding failure during loss of coolant conditions

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2021

Effect of Cultivation Conditions on the Bioconversion of 4-Hydroxybenzoic Acid in Two White-Rot Fungi

White-rot fungi (WRF) are the most efficient organisms for lignin degradation in nature. A recent study has also shown the ability of WRF in funneling lignin-derived aromatics, including 4-hydroxybenzoic acid (4HBA) and vanillic acid, to central metabolism. However, it is unknown how the cultivation conditions affect the conversion of lignin-derived aromatic compounds. To address this, we performed multi-omic analyses and tracked the conversion of 4HBA in different cultivation conditions in two white-rot fungi: Trametes versicolor and Ceriporiopsis subvermispora. Specifically, we evaluated the effect of static and agitation cultivation conditions in the absence and the presence of antioxidants on fungal performance. We found that the comparison between static and agitation has the higher number of differentially expressed genes or protein abundances at the transcriptomic and proteomic levels, respectively, compared to the presence or the absence of antioxidants. Gene mapping on the enzymatic steps of the proposed 4HBA conversion pathway revealed that agitation causes upregulation of several oxidase genes such as aldehyde dehydrogenases, aldehyde oxidases, and hydroxylases in both fungi. Time-course experiments including 4HBA and cellobiose as carbon sources showed that T. versicolor exhibited higher 4HBA conversion levels in agitation (~110% more conversion, compared to static cultivation conditions) and in the presence of antioxidants (~10% more conversion, compared to the treatments without antioxidants). Interestingly, these trends were not found in C. subvermispora, suggesting different carbon metabolism in both species. Our findings are fundamental to better understand carbon sequestration from lignin in WRF, which will be key for future applications in the lignin valorization field.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2020

Generation IV Benchmarking of TRISO Fuel Performance Models Under Accident Conditions Final Report

The Generation IV International Forum (GIF) is a co-operative international endeavor of fourteen members organized to carry out the research and development needed to establish the feasibility and performance capabilities of the next generation nuclear energy systems. GIF selected six reactor technologies, amongst which is the Very High Temperature Reactor (VHTR) that is primarily dedicated to the cogeneration of electricity and hydrogen. The technical basis for VHTR is the tristructural isotropic (TRISO)-coated particle fuel, the graphite as the core structure, helium coolant, as well as the dedicated core layout and lower power density to removal decay heat in a natural way. At the heart of safety features of the VHTR concept lie the TRISO fuel particles that are designed to keep their structural integrity and retain fission products at temperatures up to 1600°C. As part as the design and future operation of VHTRs, a key aspect is the accurate prediction of fuel performance under irradiation and accident conditions. Modeling and simulation allow prediction of TRISO fuel behavior when subject to neutron flux and in high temperature accident scenarios. The refinement of the fuel performance models and codes is performed by comparison to in-pile and out-of-pile experimental data that reproduce the expected irradiation conditions in high temperature gas-cooled reactors (HTGRs). Historically, the International Atomic Energy Agency (IAEA) developed a benchmark dedicated to the validation of predictive methods for fuel and fission product behavior through the Coordinated Research Program CRP-2 (IAEA, 1997). CRP-2 was later updated to cover fuel fabrication, quality assurance, irradiation performance, safety testing, and spent fuel. The scope of the resulting CRP-6 benchmarks focused on HTGR fuel performance and fission product release (IAEA, 2012). Taking advantage of additional TRISO fuel fabrication, irradiation, and safety testing campaigns, GIF launched a Generation IV Benchmarking of TRISO Fuel Performance Models under Accident Conditions in late 2015. This GIF benchmark is a three-year program steered by Idaho National Laboratory (INL, USA). The other participants include the Japan Atomic Energy Agency (JAEA, Japan) and the Korea Atomic Energy Research Institute (KAERI, Korea). The objectives of the benchmark are to: follow on the IAEA CRP benchmarks, (2) model fission product release under accident conditions, (3) compare results obtained by the fuel performance modeling codes of the benchmark participants, and (4) compare these code predictions to experimental data. Safety tests chosen for modeling include the first and second experiments of the Advanced Gas Reactor program (AGR-1 and AGR-2) and the High Flux Reactor (HFR) EU1bis experiment. This report presents the results obtained by the three research institutions using their respective fuel performance modeling codes. Comparisons of the corresponding fission product release predictions are made with experimental data from AGR-1, AGR-2, and HFR-EU1bis. The benchmark results show good agreements between all participants but also show a general trend of over-prediction of the experimental release data, which is mainly attributed to the use of over-estimated diffusion coefficients.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2017

A kinetic modeling study on octane rating and fuel sensitivity under HCCI conditions

With the development of advanced compression ignition engines such as the homogeneous charge compression ignition (HCCI) and the reactivity controlled compression ignition (RCCI), the long existing research and motor octane rating for fuels, i.e., RON and MON, might be insufficient to describe the fuel reactivity and performance with these new combustion strategies due to their distinctive engine operation conditions. It is also noted that with the stringent regulation for CO2 emission, a detailed knowledge of fuel reactivity is urgently needed for the selection of novel alternative bio-fuels for transportation, and optimization of their engine performance in the future. It is therefore very important to understand the reactivity and sensitivity for general classes of fuels as a function of the operating conditions in these advanced combustion engines. In this modeling study, using validated kinetic mechanism for ignition, we have simulated the performance of different classes of fuels including hydrogen, alkanes (straight and branched), alcohols and potential bio-fuels under typical HCCI engine conditions using detailed chemical kinetics. The crank angle corresponding to 50% total heat release (CA50) is utilized as an indicator for the fuel reactivity. Iso-contours of CA50 are then plotted in the engine operating parameter coordinate, such as the intake temperature, and pressure. It is shown that CA50 value can vary significantly with different engine operating conditions, and that fuels with the same RON/MON even exhibit qualitatively different CA50 iso-contours in specific operating regimes, implying differences in the intrinsic reactivity of different classes of fuels, as well as the insufficiency of RON/MON as comprehensive metrics of fuel reactivity in advanced compression ignition (ACI) strategies. In addition, the operating regime with high and low sensitivity, as well as potential non-monotonic change in fuel reactivity, has been identified by the CA50 iso-contour map for all studied fuels.

Wu, Tong↗

DOE OSTI2012

Application and development of technologies for engine-condition-based maintenance of emergency diesel generators

The emergency diesel generator (EDG) of a nuclear power plant has the role of supplying emergency electric power to protect the reactor core system in the event of the loss of offsite power supply. Therefore, EDGs should be subject to periodic surveillance testing to verify their ability to supply specified frequencies and voltages at design power levels within a limited time. To maintain optimal reliability of EDGs, condition monitoring/diagnosis technologies must be developed. Changing from periodic disassemble maintenance to condition-based maintenance (CBM) according to predictions of equipment condition is recommended. In this paper, the development of diagnosis technology for CBM and the application of a diesel engine condition-analysis system are described. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗