Auto-guiding Performance from IGRINS Test Observations (Immersion GRating INfrared Spectrograph)

Hye-In Lee,Soojong Pak,Huynh Anh N.Le,Wonseok Kang,Gregory Mace,Michael Pavel,Daniel T.Jaffe,Jae-Joon Lee,Ueejeong Jeong,Michael Pavel,Daniel T.Jaffe,Jae-Joon Lee,Ueejeong Jeong,Moo-Young Chun,Chan Pa 한국천문학회 2014 天文學會報 Vol.39 No.2

TerraPower, LLC Traveling Wave Reactor Development Program Overview

PAVEL HEJZLAR,Rovert Petroski,Jesse Cheatham,Nick Touran,Michael Cohen,Bao Truong,Ryan Latta,Mark Werner,Tom Burke,Jay Tandy,Mike Gattett,Brian Johnson,Tyler Ellis,Jon Mcwhirter,Ash Odedra,Pat Schweig 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.6

Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energy supplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given the desire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technology options available for baseload electricity generation. Further complicating this issue is the desire for energy sources to be sustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its current form meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed the Traveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. With advanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuel from LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areas covered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selected information on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safety performance. Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energysupplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given thedesire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technologyoptions available for baseload electricity generation. Further complicating this issue is the desire for energy sources to besustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its currentform meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed theTraveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalablefor the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared toconventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowestcost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferationconcerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generationinfrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need tobe built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costsand 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. Withadvanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuelfrom LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areascovered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selectedinformation on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safetyperformance.

Matrix Transformation in Boron Containing High-Temperature Co–Re–Cr Alloys

Pavel Strunz,Debashis Mukherji,Přemysl Beran,Ralph Gilles,Lukas Karge,Michael Hofmann,Markus Hoelzel,Joachim Rösler,Gergely Farkas 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5

An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect ofboron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr 2 Re 3 type) phases were measuredat ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diff raction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobaltand to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that thetransformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperaturedid not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm ofboron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which bindshcp-stabilizing elements (Cr and Re). Moreover, borides were identifi ed in alloys with high boron content.

Reactor Physics Challenges in GEN-IV Reactor Design

MICHAEL J. DRISCOLL,PAVEL HEJZLAR 한국원자력학회 2005 Nuclear Engineering and Technology Vol.37 No.1

An overview of the reactor physics aspects of Generation Four(GEN-IV) advanced reactors is presented, emphasizing how their special requirements for enhanced sustainability, safety and ecoomics motivates consideration of features not thoroughly analyzed in the past. The resulting concept-specific requirements for better data and methods are surveyed, and some approaches and initiatives are suggested to meet the challenges faced by the international reactor physics community. No unresolvable impediments to successful development of any of the six major types of proposed reactors are identified, given appropriate and timely devotion of resources.

Autoimmune Diseases Are Linked to Type IIb Autoimmune Chronic Spontaneous Urticaria

Kolkhir Pavel,Altrichter Sabine,Asero Riccardo,Daschner Alvaro,Ferrer Marta,Giménez-Arnau Ana,Hawro Tomasz,Jakob Thilo,Kinaciyan Tamar,Kromminga Arno,Konstantinou George N,Makris Michael,Metz Martin,S 대한천식알레르기학회 2021 Allergy, Asthma & Immunology Research Vol.13 No.4

Purpose Patients with chronic spontaneous urticaria (CSU) have an increased risk for comorbid autoimmune diseases. In this retrospective multicenter study of CSU patients, we evaluated clinical and laboratory features of CSU associated with a higher risk of comorbid autoimmune diseases. Methods We analyzed records of CSU patients (n = 1,199) for a history or presence of autoimmune diseases. Patients were diagnosed with type IIb autoimmune CSU (aiCSU) if all 3 tests were positive: autologous serum skin test (ASST), basophil histamine release assay (BHRA) and/or basophil activation test (BAT), and IgG autoantibodies against FcεRIα/IgE detected by immunoassay. Results Twenty-eight percent of CSU patients had at least 1 autoimmune disease. The most prevalent autoimmune diseases were Hashimoto's thyroiditis (HT) (≥ 21%) and vitiligo (2%). Two percent of CSU patients had ≥ 2 autoimmune diseases, most frequently HT plus vitiligo. Comorbid autoimmune diseases, in patients with CSU, were associated with female sex, a family history of autoimmune diseases, and higher rates of hypothyroidism and hyperthyroidism (P < 0.001). Presence of autoimmune diseases was linked to aiCSU (P = 0.02). The risks of having autoimmune diseases were 1.7, 2.9 and 3.3 times higher for CSU patients with a positive ASST, BHRA and BAT, respectively. In CSU patients, markers for autoimmune diseases, antinuclear antibodies and/or IgG anti-thyroid antibodies were associated with non-response to omalizumab treatment (P = 0.013). Conclusions In CSU, autoimmune diseases are common and linked to type IIb autoimmune CSU. Our results suggest that physicians assess and monitor all adult patients with CSU for signs and symptoms of common autoimmune diseases, especially HT and vitiligo.

REACTOR PHYSICS CHALLENGES IN GEN-IV REACTOR DESIGN

DRISCOLL MICHAEL J.,HEJZLAR PAVEL Korean Nuclear Society 2005 Nuclear Engineering and Technology Vol.37 No.1

An overview of the reactor physics aspects of Generation Four(GEN-IV) advanced reactors is presented, emphasizing how their special requirements for enhanced sustainability, safety and ecoomics motivates consideration of features not thoroughly analyzed in the past. The resulting concept-specific requirements for better data and methods are surveyed, and some approaches and initiatives are suggested to meet the challenges faced by the international reactor physics community. No unresolvable impediments to successful development of any of the six major types of proposed reactors are identified, given appropriate and timely devotion of resources.

TERRAPOWER, LLC TRAVELING WAVE REACTOR DEVELOPMENT PROGRAM OVERVIEW

Hejzlar, Pavel,Petroski, Robert,Cheatham, Jesse,Touran, Nick,Cohen, Michael,Truong, Bao,Latta, Ryan,Werner, Mark,Burke, Tom,Tandy, Jay,Garrett, Mike,Johnson, Brian,Ellis, Tyler,Mcwhirter, Jon,Odedra, Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.6

Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energy supplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given the desire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technology options available for baseload electricity generation. Further complicating this issue is the desire for energy sources to be sustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its current form meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed the Traveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. With advanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuel from LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areas covered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selected information on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safety performance.

Conversion of methane to ethylene using an Ir complex and phosphorus ylide as a methylene transfer reagent

Zatsepin, Pavel,Ahn, Seihwan,Pudasaini, Bimal,Gau, Michael R.,Baik, Mu-Hyun,Mindiola, Daniel J. The Royal Society of Chemistry 2019 Chemical communications Vol.55 No.13

<P>Cp*(Me3P)Ir(CH3)(OTf), a complex known to reversibly activate CH4 and other hydrocarbons under mild conditions, reacts with the phosphorus ylide H2CPPh3 in THF to afford two major species [Cp*(Me3P)(Ph3P)Ir(CH2CH3)][OTf] and [Cp*(Me3P)Ir(H)(η<SUP>2</SUP>-CH2CH2)][OTf]. Insertion of the ylide methylene group can also occur with Cp*(Me3P)Ir(Ph)(OTf) to afford the benzyl [Cp*(Me3P)(Ph3P)Ir(CH2Ph)][OTf]. Theoretical studies suggest the intermediacy of an Ir(iii)CH2 species.</P>

Effect of Composition on the Matrix Transformation of the Co-Re-Cr-Ta-C Alloys

Přemysl Beran,Debashis Mukherji,Pavel Strunz,Ralph Gilles,Michael Hofmann,Lukas Karge,Oleksandr Dolotko,Joachim Rösler 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.4

Neutron diffraction measurement was performed in-situ at high temperatures on Co-Re-Ta-C alloys with and without Cr addition. This included alloys containing different C content with the C/Ta ratio varying between 0.5 and 1.0. The Co-Re-solid solution matrix of the experimental alloys is polymorphic (like in pure cobalt) and transformed from low temperature hexagonal ε phase to high temperature cubic γ phase on heating. This transformation is reversible and show hysteresis. The main alloying addition, Re, stabilizes the ε Co-phase and increases the transformation temperature to above 1273 K. The onset of the ε γ transformation during heating and cooling was found to differ depending on the alloy composition. In alloys without Cr addition the transformation was not completed on cooling and the high temperature γ phase was partly retained at room temperature in metastable state with the amount depending on the cooling rate from high temperature. The diffraction and microstructural results showed that Cr is ε stabilizer (similar as Re) but the role of Ta is not clear. The C/Ta ratio has no direct effect on the matrix phase transformation. Nevertheless, it influences indirectly by determining the amount of Ta which is freely available in the matrix.

The Large Magellanic Cloud Polarization Source Catalog : Verification for quality of the catalog

Jaeyeong Kim,Soojong Pak,Minho Choi,Michael D. Pavel,Chaekyung Sim 한국천문학회 2013 天文學會報 Vol.38 No.1