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Rosensvärd, Markus, and David Danneker. "Flexural strength of zirconia after grinding, using diamond burrs, silicon carbide burr and water-cooling." Thesis, Malmö universitet, Odontologiska fakulteten (OD), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-19863.
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SyfteSyftet med föreliggande studie är att undersöka om slipning av zirkonia med silikatkarbid, diamant, vattenkylning, höghastighetsturbin och låghastighetshandstycke påverkar böjhållfastheten hos zirkonia.Material och metodFemtio provkroppar av yttriumoxidstabiliserad tetragonal zirkonia framställdes med CAD/CAM. Provkropparna delades in i 5 grupper med 10 i varje; polerad med låghastighetshandstycke (P), vattenkylning med finkornig diamantfräs (HDW), höghastighetsturbinshandstycke utan vattenkylning med finkornig diamantfräs (HDD), låghastighetshandstycke med finkornig diamantfräs (LD) och låghastighetshandstycke med kiselkarbidfräs (LC). Efter slipningen polerades alla provkropparna med låghastighetshandstycke och polertrissa. Artificiell åldring genomfördes med cyklisk dynamisk förbelastning och termocykling. Provkropparna testades med ett biaxialt böjhållfasthetstest i en universaltestmaskin. Resultaten analyserades med hjälp av en One-way ANOVA, Tukey’s test. Signifikansnivån sattes till α = 0,05.ResultatResultatet visade ingen signifikant skillnad mellan de olika grupperna. MPa medelvärde för varje grupp och standardavvikelser; P 1061(±82), HDW 1023(±92), HDD 1002(±127), LD 812(±228) and LS 984(±83).SlutsatsInom begränsningarna för föreliggande studie kan slutsatsen dras att böjhållfastheten hos zirkonia inte signifikant påverkas efter användning av följande slipningsprocesser:Höghastighetstubin med fin diamant och vattenkylning eller med höghastighetsturbin med fin diamant och utan vattenkylning eller med låghastighetshandstycke med fin diamant eller kiselkarbidfräs när zirkoniaytan är polerad.<br>AimThe purpose of this study is to investigate whether grinding zirconia with silicon carbide, diamond, water cooling, high speed turbine and low speed handpiece affects the flexural strength of zirconia.Material and methodFifty specimens of yttrium oxide stabilized tetragonal zirconia were produced using CAD/CAM. The specimens were divided into 5 groups with 10 in each; polished with low speed handpiece (P), high speed turbine with water cooling using a fine diamond burr (HW), high speed turbine without cooling using a fine diamond burr (H), low speed handpiece with a fine diamond burr (LD) and low speed handpiece with silicon carbide burr (LC). After grinding all specimens were polished with a slow speed handpiece and a polishing wheel. Artificial aging was performed using cyclic dynamic loading and thermocycling. The specimens were then tested in a biaxial flexural strength test using a universal testing machine. The results were analysed using One-way ANOVA, Tukey’s test. Level of significance was set at α = 0.05.ResultsThe results showed no significant differences between the groups. MPa means for each group and SD; P 1061(±82), HDW 1023(±92), HDD 1002(±127), LD 812(±228) and LS 984(±83).ConclusionWithin the limitations of this study it can be concluded that flexural strength of zirconia is not significantly affected using the following grinding processes: High-speed turbine with fine diamond and water cooling or with fine diamond without water cooling, low-speed handpiece with fine diamond or with silicon carbide burr when the zirconia has been polished.
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Stewart, Christopher L. "Antineutrino-based safeguards for ultra-high burnup fast reactors." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/55024.
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Since the first observation of antineutrinos from beta decay of the fission products inside a nuclear reactor in 1956, the design and operating experience of antineutrino detectors near reactors has increased to the point where monitoring the reactor's power level and progression through its burnup cycle has become possible. With the expected increase in world nuclear energy capacity, including the dissemination of reactor technologies to non-nuclear states, the need for safeguards measures which are able to provide continuous, near-real-time information about the state of the core, including its isotopic composition, in a tamper- and spoof-resistant manner is evident. Near-field (~20 m from the core) antineutrino detectors are able to fulfill this demand without perturbing normal reactor operation, without requiring instrumentation which penetrates the reactor vessel, and without displacing other plant structures.
Two sodium-cooled long-life fast reactors that are characteristic of next-generation reactors which are attractive for installation in non-nuclear states, one large and one small power rating, have been modeled throughout their reference burnup cycles using MCC-3 and DIF3D/REBUS. Various diversions of fissile material from the core designed to obtain weapons-usable material for the purpose of nuclear proliferation were studied as perturbed core states. The difference in detector event rates between the reference and perturbed states was used to determine the probability that a particular diversionary activity would be apparent before the material could be converted into a weapon. These data indicate which types of diversion antineutrino safeguards are particularly strong against and how the technology might be implemented in current and future international policies concerning nuclear proliferation.
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Reese, Drew A. (Drew Amelia). "Dependence of transuranic content in spent fuel on fuel burnup." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41692.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.<br>Includes bibliographical references (p. 33).<br>As the increasing demand for nuclear energy results in larger spent fuel volume, implementation of longer fuel cycles incorporating higher burnup are becoming common. Understanding the effect of higher burnup on the spent fuel composition and radioactive properties is essential to ensure that spent fuel receives proper cooling in storage before it is sent to a disposal site or proper treatment and reprocessing if its useful content is to be extracted prior to disposal. Using CASMO-4, a standard Westinghouse 4-loop pressurized water reactor model was created and simulated with a three batch fuel cycle. U-235 enrichment was adjusted to achieve fuel burnups of 30, 50, 70 and 100 MWD per kg of initial uranium. These burnups demanded reload enrichments of 3.15%, 4.63%, 6.26% and 9.01% U-235 w/o respectively. The resultant spent fuel transuranic isotopic compositions were then provided as input into ORIGEN to study the decay behavior of the spent fuel. It was found that when burnup increased from 30 MWD/kg to 100 MWD/kg, the activity more than doubled due to the decreased Pu-241 content and the increased Np-239 presence. More importantly, the activity per MWD significantly decreased despite absolute increases in unit mass. The net result is that the half-life of high burnup fuels is greatly increased in comparison to low burnup fuels for the first decade of life. Beginning from day 14 after shutdown and until 10 years later, the 100 MWD/kg fuel has a half-life of 129 days while the 30 MWD/kg spent fuel has a half life of 5 days. Previous work has suggested that different trends dominate decay behavior from years 10 to 100 years following discharge.<br>by Drew A. Reese.<br>S.B.
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Kersting, Alyssa (Alyssa Rae). "Fluence-limited burnup as a function of fast reactor core parameters." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76938.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 39).<br>The limiting factor in current designs for fast reactors is not only the reactivity, but also the maximum permissible fast-neutron fluence in the cladding, especially for reduced uranium enrichment cores using high-albedo MgO reflectors. The intent of this thesis was to determine the best design parameters - fuel type, fuel compound, fuel arrangement, and coolant - while observing these limitations. The ERANOS code was used to determine the flux values for each design option. A curve was fitted to the fluxes taken at beginning of life, middle of life, and end of life. This curve was then integrated progressively until the clad fluence limit of 4 x 1023 fast neutrons/cm 2 was reached. The different design options were compared with emphasis on minimizing enrichment and maximizing burnup. Sodium was chosen as a coolant because of its extensive experience based compared to the other options, as well as its heat transfer properties. Inverted fuel was found to be better neutronically, in both clad lifetime and burnup than conventional pin-type fuel, but the requirement of fuel venting may discourage use of this option. Uranium carbide was found to be superior to nitride, oxide or metal fuel in its clad lifetime, especially if pin cell fuel is used. If inverted fuel is used, uranium oxide is also a valid choice from a burnup and cost perspective, especially should re-cladding not be feasible or desired, since the reactivity and clad fluence lifetimes of oxide fuel are similar to each other.<br>by Alyssa Kersting.<br>S.B.
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Xu, Zhiwen 1975. "Design strategies for optimizing high burnup fuel in pressurized water reactors." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/16603.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.<br>Includes bibliographical references (p. 254-264).<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>This work is focused on the strategy for utilizing high-burnup fuel in pressurized water reactors (PWR) with special emphasis on the full array of neutronic considerations. The historical increase in batch-averaged discharge fuel burnup, from ~30 MWd/kg in the 1970s to ~50 MWd/kg today, was achieved mainly by increasing the reload fuel enrichment to allow longer fuel cycles: from an average of 12 months to about 18 months. This also reduced operating costs by improving the plant capacity factor. Recently, because of limited spent fuel storage capacity, increased core power output and the search for increased proliferation resistance, achieving burnup in the 70 to 100 MWd/kg range has attracted considerable attention. However the implications of this initiative have not been fully explored; hence this work defines the practical issues for high-burnup PWR fuels based on neutronic, thermal hydraulic and economic considerations as well as spent fuel characteristics. In order to evaluate the various high burnup fuel design options, an improved MCNP-ORIGEN depletion program called MCODE was developed. A standard burnup predictor-corrector algorithm is implemented, which distinguishes MCODE from other MCNP-ORIGEN linkage codes. Using MCODE, the effect of lattice design (moderation effect) on core design and spent fuel characteristics is explored. Characterized by the hydrogen-to-heavy-metal ratio (H/HM), the neutron spectrum effect in UO2/H2O lattices is investigated for a wide range of moderation, from fast spectra to over-thermalized spectra. It is shown that either wetter or very dry lattices are preferable in terms of achievable burnup potential to those having an epithermal spectrum. Wet lattices are the preferred high burnup approach due to improved proliferation resistance. The constraint of negative moderator temperature coefficient (MTC) requires that H/HM values (now at 3.4) remain below ~6.0 for PWR lattices. Alternative fuel choices, including the conventional solid pellets, central-voided annular pellets, Internally- & eXternally-cooled Annular Fuel (IXAF), and different fuel forms are analyzed to achieve a wetter lattice. Although a wetter lattice has higher burnup potential than the reference PWR lattice, the requirement of a fixed target cycle energy production necessitates higher initial fuel enrichments to compensate for the loss of fuel mass in a wetter lattice. Practical issues and constraints for the high burnup fuel include neutronic reactivity control, heat transfer margin, and fission gas release. Overall the IXAF design appears to be the most promising approach to realization of high burnup fuel. High-burnup spent fuel characteristics are compared to the reference spent fuel of 33 MWd/kg, representative of most of the spent fuel inventory. Although an increase of decay power and radioactivity per unit mass of initial heavy metal is immediately observed, the heat load (integration of decay power over time) per unit electricity generation decreases as the fuel discharge burnup increases. The magnitude of changes depends on the time after discharge. For the same electricity production, not only the mass and volume of the spent fuel are reduced, but also, to a lesser extent, the total heat load of the spent fuel. Since the heat load in the first several hundred years roughly determines the capital cost of the repository, a high burnup strategy coupled with adequate cooling time, may provide a cost-reduction approach to the repository. High burnup is beneficial to enhancing the proliferation resistance. The plutonium vector in the high-burnup spent fuel is degraded, hence less attractive for weapons. For example, the ratio of Pu-238 to Pu-239 increases with burnup to the 2.5 power. However, the economic benefits are uncertain. Under the current economic conditions, the PWR fuel burnup appears to have a shallow optimum discharge burnup between 50 and 80 MWd/kg. The actual minimum is influenced by the financing costs as well as the cost of refueling shutdowns. Since the fuel cycle back-end benefits will accrue to the federal government, the current economic framework, such as the waste fee based on the electricity produced rather than volume or actinide content, does not create an incentive for utilities to increase burnup. Different schemes exist for fuel management of high burnup PWR cores. For the conventional core design, a generalized enrichment-burnup correlation (applicable between 3 w/o and 20 w/o) was produced based on CASMO/SIMULATE PWR core calculations. Among retrofit cores, increasing the number of fuel batches is preferred over increasing the cycle length due to nuclear fuel cycle economic imperatives. For future core designs, a higher power-density core is a very attractive option to cut down the busbar cost. The IXAF concept possesses key design characteristics that provide the necessary thermal margins at high core power densities. In this regard, the IXAF fuel deserves further investigation to fully exploit its high burnup capability.<br>by Zhiwen Xu.<br>Ph.D.
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Liu, Wenfeng Ph D. Massachusetts Institute of Technology. "Assessment of high-burnup LWR fuel response to reactivity-initiated accidents." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/44786.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.<br>Includes bibliographical references (p. 263-273).<br>The economic advantages of longer fuel cycle, improved fuel utilization and reduced spent fuel storage have been driving the nuclear industry to pursue higher discharge burnup of Light Water Reactor (LWR) fuel. A design basis accident, the Reactivity Initiated Accident (RIA), became a concern for further increase of burnup as simulated RIA tests revealed lower enthalpy threshold for fuel failure associated with fuel dispersal, which may compromise the core coolability and/or cause radiological release should this happened in LWRs. Valuable information on the behavior of high burnup fuel during RIA are provided by the simulation tests. However atypical design and operating conditions in simulated tests limited the application of experimental data directly to evaluate the failure potential of LWR fuels. To better interpret the experimental results and improve the capability of the fuel performance codes to predict high burnup fuel behavior, this thesis developed mechanistic models of high burnup fuel during an RIA and implemented models in a transient fuel performance code FRAPTRAN 1.3. Fission gas release (FGR) and swelling were systematically modeled to quantify gaseous loading effects. The grain boundary fission gas inventory is simulated prior to the transient using a diffusion model in FRAPCON 3.3 code. The restructuring of high burnup fuel in rim region is described in terms of porosity, pore size distribution, fission gas concentration, and pore overpressure. The model assumes the fragmentation of fuel upon the separation of grain boundary or when a threshold temperature is exceeded in the rim region. The fission gas in fragmented fuel is assumed to release instantaneously to the free volume when the fuel expansion and swelling creates sufficient pellet-clad gap.<br>(cont.) The relaxation of rim pore at rapid temperature increase and the thermal expansion of fission gas in fragmented fuel are considered as additional loads on the cladding besides the contact force due to fuel thermal expansion. An analytical approximation is made to calculate the clad radial displacement subjected to fission gas expansion accounting for the constraint of the cladding on the fission gas which would otherwise be neglected in a rigid pellet model FRACAS-I in the FRAPTRAN code. In comparison to the measured FGR from CABRI, NSRR and BIGR test facilities, this mechanistic model can reasonably predict fission gas release fraction for most of the test cases covering a burnup range of 26-64 MWd/kgU and enthalpy deposit of 37-200 cal/g. It reveals the effects of burnup and enthalpy deposit on the fission gas release: burnup is an important parameter affecting fission gas inventory and fuel micro-structure evolution during base irradiation; enthalpy deposit is directly connected to the availability of fission gas release via the grain boundary separation by the intergranular bubble over-pressurization. Analysis of the fission gas radial profile is made with the aid of the neutronic code MCODE to validate the fission gas release from the rim of UO2 fuel. The analysis indicates fission gas release is partly from the rim region and the majority of fission gas release is from grain boundaries for burnup up to 50 MWd/kgU. Fission gas induced hoop strain is predicted to be less than 0.3% in the early phase of RIA with peak fuel enthalpy less than 145 cal/g. Given the fact that the concerned failure mode is the PCMI failure at low energy deposit, the pellet thermal expansion is still considered as effective in analyzing the PCMI failure. However at high level of enthalpy deposit, when clad yield strength is decreased at escalated temperature due to film boiling, the fission gas either released into the plenum or retained in the fuel pellet might strain more the cladding.<br>(cont.) This is observed in the large deformation of the cladding in some test cases in NSRR and BIGR due to pressure load. A new set of heat transfer correlations were selected and implemented in the FRAPTRAN code to model the cladding-coolant heat transfer of high burnup fuel at room temperature and atmospheric pressure condition. This new set of correlations addressed the effects of subcooling and oxiation on the heat transfer characteristics at pool boiling conditions. They reflect the increase of rewetting temperature and increase of Critical Heat Flux (CHF) due to subcooling. They account for oxidation effects on the transition and film boiling regime and heat conduction through thick oxide as the oxidation is considered as a prominent feature of surface condition change of high burnup fuel. In addition to high burnup fuels tested in NSRR, several fresh fuel tests with different degree of subcooling and a few separate-effects RIA tests are also included to validate the applicabilty of this set of correlations. For fuel enthalpy up to 190 cal/g and oxidation up to 25 micron, the predicted peak cladding temperature (PCT) and duration of DNB achieves generally good agreement with the experimental data. The analysis of high burnup fuel heat transfer reveals that the surface oxidation could cause an early rewetting of high burnup fuel or suppression of DNB. Surface oxidation can delay the heat conducting to the surface while keeping the surface heat transfer in the effective nucleate boiling regime. It also raises the miniumum stable film boiling temperature by lowering the interface temperature during liquid-solid contact resulting from vapor breaking down. Also modeled was Pellet-Cladding Mechanical Interaction (PCMI) failure of irradiated and hydrided cladding. The hydride rim accumulated at outer clad is assumed to cause the crack initiation. The fracture toughness of irradiated and hydrided cladding is obtained by fitting experimental data at different temperature range.<br>(cont.) The model sets forth a simple criterion for failure associated with crack growth based on the J integral approach. The simplification is that for the thin clad, failure is assumed to occur at the onset of crack tip growth. In comparison to CABRI and NSRR test results and other failure models, the model shows a good capability to separate the failure cases from non-failure cases. These models have been applied to LWR conditions to determine the failure potential of high burnup fuel. It shows that, at high burnup (and therefore high hydride levels in the cladding), the failure enthalpy is smaller than at low burnup. The pulse width is an important parameter in the burnup up to 50 MWd/kg, but starts to become less important for higher burnup with highly corroded cladding.<br>by Wenfeng Liu.<br>Ph.D.
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Long, Yun 1972. "Modeling the performance of high burnup thoria and urania PWR fuel." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/30000.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2002.<br>Includes bibliographical references (p. 157-171).<br>Fuel performance models have been developed to assess the performance of ThO₂-UO₂ fuels that can be operated to a high burnup up to 80-100MWd/kgHM in current and future Light Water Reactors (LWRs). Among the various issues raised in high burnup fuel applications, the pellet rim effect, fission gas release (FGR), and response to reactivity initiated accidents (RIA) were of special interest in this work. These phenomena were modeled by modifying the NRC licensing codes FRAPCON-3 for normal operation and FRAP-T6 for transient conditions. These models were verified and compared to the results of previous thorium fuel studies and high burnup uranium fuel evaluations. The buildup of plutonium in the outer rim of LWR UO2 pellets has been observed to create a region of high fuel burnup, fission gas buildup and high porosity at the fuel rim. The power distribution of the thoria and urania fuel was calculated using a neutronics code MOCUP. Due to the lower build-up of Pu-239 (less U-238 in ThO₂-UO₂ fuel) and flatter distribution of U-233 (less resonance capture in Th-232), thoria fuel experiences a much flatter power distribution and thus has a less severe rim effect than UO₂ fuel. To model this effect properly, a new model, THUPS (Thoria-Urania Power Shape), was developed, benchmarked with MOCUP and adapted into FRAPCON-3. Additionally a porosity model for the rim region was introduced at high burnup to account for the larger fuel swelling and degradation of the thermal conductivity. The mechanisms of fission gas release in ThO₂-UO₂ fuel have been found similar to those of U0₂ fuel. Therefore, the general formulations of the existing fission gas release models in FRAPCON-3 were retained.<br>(cont.) However, the gas diffusion coefficient in thoria was adjusted to a lower level to account for the smaller observed gas release fraction in the thoria-based fuel. To model accelerated fission gas release at high burnup properly, a new athermal fission gas release model was developed. Other modifications include the thoria fuel properties, fission gas production rate, and the corrosion model to treat advanced cladding materials. The modified version of FRAPCON-3 was calibrated using the measured fission gas release data from the Light Water Breeder Reactor (LWBR) program. Using the new model to calculate the gas release in typical PWR hot pins gives data that indicate that the ThO₂-UO₂ fuel will have considerably lower fission gas release beyond a burnup of 50 MWd/kgHM. Investigation of the fuel response to an RIA included: (1) reviewing industry simulation tests to understand the mechanisms involved, (2) modifying FRAP-T6 code to simulate the RIA tests and investigate the key contributors to fuel failure (thermal expansion, gaseous swelling, cladding burst stress), and (3) assessing thoria and urania performance during RIA event in typical LWR situations. ThO₂-UO₂ fuel has been found to have better performance than U0₂ fuel under RIA event conditions due to its lower thermal expansion and a flatter power distribution in the fuel pellet (less power and less fission gas in the rim region). Overall, thoria has been found to have better performance than urania in both normal and off-normal conditions. However, calculations using the modified FRAPCON-3 ...<br>by Yun Long.<br>Ph.D.
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Wright, Amy G. "Drivers of burrow symbiont distribution in a softsediment system: host abundance or burrow trophic environment?" Bachelor's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/7634.
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The Langebaan Lagoon sandflats are dominated by the burrowing activities of thalassinid shrimps. Their burrows are home to various burrow symbionts including a commensal shrimp (Betaeus jucundus), a six-legged crab (Spiroplax spiralis) and a scaleworm (Antinoe lactea). Little work has been conducted on these burrow symbionts, and the mechanisms influencing their abundance and distribution are unknown. To test whether host abundance or the burrow trophic environment (i.e. food availability) is the dominant force shaping patterns of burrow symbiont distribution, samples of host and symbiont abundances as well as chlorophyll-a and extracellular polymeric substance (EPS) measurements were taken from three sites in Langebaan Lagoon over spring and autumn. Clear signals emerged in contradiction of the hypothesis that burrow symbiont abundances peak in areas associated with high abundances of hosts. Host abundances peaked at Bottelary (10.18 counts/site ± 1.02 SE), a site where recreational activities and thalassinid shrimp bait collection are prohibited. In contrast, peak B. jucundus abundance (6.56 counts/site ± 0.37 SE) occurred at Oesterval during September – the muddy sediment of the site resulted in high sedimentary food retention and the September spring phytoplankton bloom resulted in peak chlorophylla (234.12 mg chl-a/g sediment ± 42.74 SE) and EPS (0.13 mg EPS/g sediment ± 0.008 SE) concentrations. Regression analyses confirmed that food availability was the best explanation of the patterns observed in B. jucundus distributions, over and above that of host distributions. S. spiralis and A. lactea did not show this pattern, the result of the low counts of these species in the collected samples or their reliance on food sources different to those depended on by B. jucundus. These results are of consequence in changing the way we think about symbiont distributions relative to that of the hosts, in that the two may not be linked directly, but rather influenced by larger scale trophic changes such as the availability of food within the burrow.
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Larson, Kyle Blake. "Nest habitat selection of burrowing owls in relation to soils, burrow availability, and burrow temperature." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Summer2009/K_Larson_072409.pdf.
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Thesis (M.S. in environmental science)--Washington State University, August 2009.<br>Title from PDF title page (viewed on Sept. 17, 2009). "School of Earth and Environmental Sciences." Includes bibliographical references (p. 35-42).
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Björkholm, Peter, and Anna Dyring. "A study of a high rate gamma-spectrometer system for burnup measurements." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 1990. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-260034.
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Tucek, Kamil. "Neutronic and burnup studies of accelerator-driven systems dedicated to nuclear waste transmutation." Doctoral thesis, KTH, Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-66.
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<p>Partitioning and transmutation of plutonium, americium, and curium is inevitable if the radiotoxic inventory of spent nuclear fuel is to be reduced by more than a factor of 100. But, admixing minor actinides into the fuel severely degrades system safety parameters, particularly coolant void reactivity, Doppler effect, and (effective) delayed neutron fractions. The incineration process is therefore envisioned to be carried out in dedicated, accelerator-driven sub-critical reactors (ADS). However, ADS cores operating in concert with light-water reactors (two-component scenario) also exhibit high burnup reactivity swing with penalty on the system performance/economy. </p><p>In the frame of this design work, we attempted, by choice of coolant and optimisation of fuel concept and core design, to achieve favourable neutronic, burnup and safety characteristics of the transuranium ADS burner. Key thermal hydraulic and material-related constraints were respected. </p><p>A novel fuel matrix material, hafnium nitride, was identified as an attractive diluent option for highly reactive transuranics. (TRU,Hf)N fuels appeared to have a good combination of neutronic, burnup and thermal characteristics: maintaining hard neutron spectra, yielding acceptable values of coolant void reactivity and source efficiency, and providing small burnup reactivity loss. A conceptual design of a (TRU,Hf)N fuelled, lead/bismuth eutectic cooled ADS was developed. The average discharge burnup of 20% fissions per initial metal atom could be reached even without fuel reshuffling. The fission fraction ratios of even-neutron number americium nuclides are increased by a factor of two in comparison to burners with inert matrix based fuels. Hence, thanks to the reduced production of higher actinides and helium, fuel cycle economy is improved. </p><p>The coolant void worth proved to be a strong function of the fuel composition - reactor cores with high content of fertile material or minor actinides in fuel exhibit larger void reactivities than systems with plutonium-rich, inert matrix fuels. In reactor systems cooled by lead/bismuth eutectic, a radial steel pin reflector significantly lowered coolant void reactivity. For transuranic fuel, fertile and strongly absorbing matrices exhibited increasing void worth with increasing pitch, while the opposite was valid for the coolant void worth of inert matrix fuels. Large pitches also appeared to be beneficial for limiting the reactivity worth of the cladding material and improving source efficiency. </p><p>The economy of the source neutrons was investigated as a function of core and target design. An incentive to design the core with as low target radius as allowable by the thermal constraints posed by the ability to dissipate accelerator beam power was identified.</p>
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Tuček, Kamil. "Neutronic and burnup studies of accelerator-driven systems dedicated to nuclear waste transmutation /." Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-66.
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Sukjai, Yanin. "Fuel performance modeling of high burnup mixed oxide fuel for hard spectrum LWRs." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119036.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2018.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 408-431).<br>According to the future of the nuclear fuel cycle study at MIT, a reactor with a conversion ratio around one can achieve desired objectives in the long-term sustainability of uranium and reduction of transuranic wastes. This finding relaxes the need for sodium fast reactors (SFR) in a closed-loop nuclear fuel cycle and enables high-conversion light water reactors (HC-LWR) to be used as an alternative. HC-LWRs have two major advantages over SFRs. First, apart from the reactor core, the remaining reactor system can be based on existing LWR technology. Second, extensive operating experience and a proven record of high reliability of LWRs would ease licensing and commercialization processes. Therefore, operating HC-LWRs instead of SFRs may be more economically and technically viable with lower capital and development cost for the near term. This type of reactor is being developed by Hitachi Ltd. under the name of resource-renewable boiling water reactor (RBWR). This study focuses on RBWR-TB2, transuranic burning version of RBWR. To demonstrate that the RBWR-TB2 can operate safely within design constraints and regulatory limits, the thermomechanical behavior of this reactor has been analyzed through fuel performance modeling. Due to its unique design characteristics, several physical phenomena at high temperature and high burnup typically ignored in most LWR fuel performance codes can potentially become active under RBWR's operating conditions. These phenomena involve migration of fuel constituents and fission products, the evolution of O/M ratio with burnup, high burnup structure (HBS) formation, accelerated corrosion, hot pressing, gaseous fuel swelling, hydride precipitation and hydrogen migration in the cladding. Semi-empirical models describing porosity and cesium migration behaviors have been replaced with mechanistic models. All of these phenomena have been successfully implemented in a modified version of FRAPCON-3.5 known as FRAPCON-3.5 EP where EP stands for enhanced performance. The fuel performance comparison between RBWR-TB2 and ABWR fuel rods suggest that because of high axial peaking factors and relatively flat power history, fuel temperature is significantly higher in fissile zones of the RBWR-TB2 leading to various undesirable effects such as excessive fission gas release and cladding deformation. Local fuel burnup in fissile zones of RBWR-TB2 is multiple times higher than that of ABWR leading to excessive fuel swelling, accelerated cladding oxidation, and PCMI at fissile-blanket interfaces. Even if the RBWR-TB2 has to operate under such demanding conditions with a small margin to fuel melting, a steady-state fuel performance analysis still shows that this reactor can operate safely with an acceptable thermo-mechanical performance. In the future optimization of RBWR-TB2 performance, several fuel design strategies are recommended based on a series of sensitivity studies. The sensitivity study on key design parameters indicates that using annular fuel geometry and more hypostoichiometric fuel (lower O/M ratio) could reduce fuel temperature at high burnup. For better resistance to cladding corrosion and PCMI, it is recommended to increase cladding thickness and decrease fuel density.<br>by Yanin Sukjai.<br>Ph. D.
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Abell, Lesley. "Burra and its townships /." Title page, contents and introduction only, 1990. http://web4.library.adelaide.edu.au/theses/09AR/09ara141.pdf.
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BASSO, LUANA S. "Estudo da emissão de metano da Bacia Amazônica utilizando perfis verticais com avião." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10000.
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BASSO, LUANA S. "Determinação da emissão de metano da bacia amazônica." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23500.
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Submitted by Maria Eneide de Souza Araujo (mearaujo@ipen.br) on 2015-02-25T13:31:17Z
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Kaya, Esin Özkul Metin. "Sağlık kurumlarında örgüt kültürü (Burdur-Isparta örneği) /." Isparta : Süleyman Demirel Üniversitesi Sosyal Bilimler Enstitüsü, 2007. http://tez.sdu.edu.tr/Tezler/TS00597.pdf.
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Delhey, Norbert. "Apollinaris Sidonius, Carm. 22 : Burgus Pontii Leontii /." Berlin : W. de Gruyter, 1993. http://catalogue.bnf.fr/ark:/12148/cb355732250.
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Vielma, Mansilla André Nicolás. "Factores que facilitan el daño ocasionado por burros ferales (Equus asinus) a cultivos de la precordillera de la Región de Tarapacá." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/143023.
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Memoria para optar al Título Profesional de Médico Veterinario<br>La resolución de conflictos entre fauna silvestre y humanos es un tema clave en el manejo
de los recursos naturales, donde el daño de cultivos de interés humano es un problema
complejo y extendido a nivel global. Estos conflictos son particularmente intensos en
localidades cuya economía se basa en la agricultura y ganadería de subsistencia. En los
Andes del norte de Chile, en la región de Tarapacá, habitan burros ferales (Equus asinus),
con una población estimada en al menos 1.600 individuos, los que ocasionan pérdidas
productivas muy altas por herbivoría en zonas cultivadas. En los poblados de Poroma y
Coscaya, en la zona precordillerana, se estudió este conflicto desde la aproximación de la
ecología espacial, con el objetivo de analizar los factores que facilitan el daño de los
cultivos de alfalfa y maíz a escala predial. Se evaluaron las características del cultivo y su
entorno que determinan la presencia e intensidad del daño, se determinó el patrón horario
de ingreso a los cultivos, y se caracterizaron las rutas de acceso utilizadas.
Para la evaluación del daño se analizaron 16 potreros, y para la evaluación de los patrones
de ingreso se estudiaron 18 sitios, en ambos poblados. El ingreso de los burros a los
cultivos ocurre durante la noche. El principal componente espacial que determina la
presencia e intensidad del daño es la cercanía de los cultivos al camino vehicular, lo que
permite la conectividad, esto es, el tránsito expedito de los animales entre sus zonas de
refugio ubicadas en los cerros y quebradas aledaños a los poblados, y la zona donde se
ubican los potreros cultivados. Además, se destaca la baja densidad de habitantes y la
presencia de medidas de control rústicas como un facilitador del conflicto. Es posible que el
daño a los cultivos sea ocasionado principalmente por algunos burros machos adultos
problemáticos.
La solución a corto plazo, debe enfocarse en el control de la conectividad, para lo que se
propone la instalación de cercos junto con un programa de monitoreo y mantención de
éstos, involucrando a la comunidad. Como medida de solución a mediano y largo plazo se
discute la posibilidad de implementar un programa de control letal, considerando un
potencial aprovechamiento cárnico.<br>The resolution of conflicts between wildlife and human communities is a key component of
natural resource management. Crop raiding is a complex problem of global dimensions,
which reach particularly intense magnitudes in localities with subsistence agriculture based
economies. At Tarapacá district in the Andes mountain range in northernmost Chile
inhabits a population of feral donkeys (Equus asinus) of at least 1.600 individuals. These
animals feed on croplands generating high production losses. This conflict was studied
from the perspective of spatial ecology in Poroma and Coscaya localities at the Andes
foothills. The objective was to analyze the factors that facilitate the herbivory over alfalfa
and maize crops at a local scale. We evaluated the crop features determining damage
presence and intensity, searched for temporal patterns of crop raiding, and characterized
access routes.
Sixteen paddocks were evaluated for crop damage analysis, and eighteen sites were studied
for exploring crop raiding patterns. The crop raiding occurs during the night. The main
spatial component determining damage presence and intensity is the proximity of crops to
the road, thus allowing for connectivity, namely, efficient transit of the animals between
their place of refuge located over the hills, and the area with croplands. Moreover, low
habitant densities and rustic control measures facilitate conflict existence. It is possible that
crop raiding is carried out mainly by some problematic adult male donkeys.
For resolving the conflict in the short term the solution ought to focus on controlling
connectivity, for which it is proposed the installation of fences along with the development
of a program of monitoring and maintenance involving the community. As a long term
solution we discuss the possibility of implementing a lethal control program, including a
potential use of donkey’s meat.<br>Financiamiento Proyecto "Diagnóstico de la Ecología Poblacional de la vicuña, taruka y guanaco, y medidas de solución al conflicto silvoagropecuario ? ungulados silvestres de la región de Tarapacá?, SAG" - Ministerio de Agricultura, Gobierno de Chile
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Tekin, Ayşe Özkul Metin. "Sağlık-hastalık olgusu ve toplumsal kökenleri (Burdur örneği) /." Isparta : Süleyman Demirel Üniversitesi Sosyal Bilimler Enstitüsü, 2007. http://tez.sdu.edu.tr/Tezler/TS00573.pdf.
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Barros, Nelci Moreira de. "Conversa de quiosque :: os burros perderam o emprego ! /." Florianópolis, SC, 1999. http://repositorio.ufsc.br/xmlui/handle/123456789/80662.
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Dissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Educação.<br>Made available in DSpace on 2012-10-18T17:23:53Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-09T02:29:38Z : No. of bitstreams: 1
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YORIYAZ, HELIO. "Implementacao de queima espacial modificando o programa nodal baseado no metodo de elementos finitos e matriz resposta." reponame:Repositório Institucional do IPEN, 1986. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9855.
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Peakman, Aiden. "Development of a long-life core for commercial marine propulsion." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-longlife-core-for-commercial-marine-propulsion(7876d516-1a94-449c-a1b5-1b6d011a2d8d).html.
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If international agreements regarding the need to significantly reduce greenhouse gas emissions are to be met then there is a high probability that the shipping industry will have to reduce its greenhouse gas emissions. For emission reductions from ships greater than around 40% then alternatives to fossil fuels - such as nuclear energy - will very likely be required. Whilst nuclear powered ships have successfully operated at sea for a number of decades, these have been primarily naval systems (or derivatives of naval systems such as icebreakers) and a few demonstration projects using reactors with low power outputs. The operational requirement for large civilian vessels (for example high capacity factors and limited personnel) mean the naval and past demonstration reactor systems are ill-suited for use in the current fleet of commercial container ships. There have been relatively few studies performed addressing the likely requirements upon core design a marine reactor would have to meet. This study addresses those issues and also implements a Pressurised Water Reactor core design capable of achieving these requirements. Furthermore, in order to simplify reactor operation for a limited number of personnel on board, the chemical reactivity control system has been eliminated during power operation. This has resulted in a novel low power density core that does not require refuelling for 15 years. The neutronic and fuel performance behaviour of this system has been studied with conventional UO2 fuel and thorium-uranium oxide ((Th,U)O2) fuel. With respect to (Th,U)O2 fuel there has been limited analysis comparing the performance of key fuel characteristics, such as fission gas release and thermal conductivity, as a function of uranium content in (Th,U)O2 fuel and their impact on fuel behaviour. Furthermore, the performance of neutronic codes for modelling Th-232 and U-233 from a variety of experiments using modern nuclear data libraries (post 1990) is lacking. Both of these issues are addressed in this study. Whilst it is frequently stated that thorium-based oxide fuel is superior to UO2 fuel it was found that due to the sensitivity of thermal conductivity on temperature and uranium content this was not true for the core designed in this study. The (Th,U)O2 core showed no net economic benefits with respect to the UO2 core and it was found that the fuel performance of (Th,U)O2 fuel was worse than the UO2 fuel in the reactor designed here. The UO2 core design, however, was able to satisfactorily meet the majority of requirements placed upon the system.
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Alshogeathri, Saqr Mofleh. "Application of the reactivity method on KSU TRIGA fuel." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34637.
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Master of Science<br>Department of Mechanical and Nuclear Engineering<br>Jeremy Roberts<br>The reactivity method is an indirect nondestructive technique to estimate integral burnup in fuel elements. In this method, the assumption is made that reactivity worth of a fuel element is a known function of burnup, often a linear relationship. When a fuel element burns, reactivity is reduced due to depletion of fissile actinides and generation of neutron-absorbing fission products. Currently, there is a lack of experimental data to verify the current composition of the KSU TRIGA (Training Research Isotopes General Atomics) fuel. Moreover, the KSU TRIGA Mark II staff method of estimating burnup is admittedly inaccurate due to its simple approximations. This work presents the positive period technique as convenient method use only the excess reactivity of the KSU core to compute reactivity via the inhour equation. Period measurements are determined via extraction and manipulation of the time dependent power data in the measurements. MCNP and Serpent modeling codes are both used extract the neutron kinetics parameters necessary in the inhour equation. Seven axial discretization of the KSU fuel was modeled, which minimizes the reactivity biases as function of burnup. Moreover, two unit cell models of the KSU TRIGA fuel were investigated. Modeled reactivity worths were computed using the KCODE in MCNP for comparative analysis. The burnup steps using two power peaking factor methods were developed to account for the biases introduced initial burnup of fuel prior to installation at KSU. By using the error distribution given by the two method to generate 200 test cases of the burnup steps can yield to reactivity worths as a function of burnup with quantifiable uncertainties. Finally, the results suggest that validation from another nondestructive technique such as gamma spectroscopy is necessary to asses the reactivity biases observed for higher burnup fuel elements due to unknown radial orientations. This work ultimately supports the production of a high-fidelity model of the KSU reactor.
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Helgesson, Petter. "UO-2 vs MOX: Propagated nuclear data uncertainty with burnup using Fast Total Monte Carlo." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-202725.
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Precise assessment of propagated nuclear data uncertainties in integral reactor quantities is necessary for the development of new reactors as well as for modified use, e.g. when replacing UO-2 fuel by MOX fuel in conventional thermal reactors. The Fast Total Monte Carlo method (Fast TMC) is a further development of Total Monte Carlo - a reliable, general and flexible way to study how uncertainties propagate from differential nuclear data to integral results. The main idea is not new or unique for the field: integral quantities of interest are computed multiple times using differential data which is randomly sampled from distributions that quantify the uncertainty of the differential data; the spread in the results is then used in the quantification of the propagated uncertainties. This text compares UO-2 fuel to two types of MOX fuel with respect to propagated nuclear data uncertainty, primarily in the neutron multiplication factor k-eff, by applying Fast TMC to a typical PWR pin cell model in the Monte Carlo transport code SERPENT, including burnup. An extensive amount of nuclear data uncertainties is taken into account, including transport and activation data for 105 isotopes, fission yields for 13 actinides and thermal scattering data for hydrogen in water. There is indeed a significant difference in propagated nuclear data uncertainty in k-eff; at 0 burnup the uncertainty is 0.6 % for UO-2 and about 1 % for the MOX fuels. The difference decreases with burnup. Uncertainties in fissile fuel isotopes and thermal scattering are the most important for the difference and the reasons for this are understood and explained. This work thus suggests that there can be an important difference between UO-2 and MOX for the determination of uncertainty margins. However, the effects of the simplified model are difficult to overview; uncertainties should be propagated in more complicated models of any considered system. Fast TMC however allows for this.
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ZHAO, ZHONGXIANG. "INVESTIGATION ON USING NEUTRON COUNTING TECHNIQUES FOR ONLINE BURNUP MONITORING OF PEBBLE BED REACTOR FUELS." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096914339.
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Kür, Hasan Tızlak Fahrettin. "210 numaralı şer'iyye siciline göre Burdur Kazası'nın idari, sosyal ve ekonomik yapısı (h.1255-1261/m.1839-1845) /." Isparta : SDÜ Sosyal Bilimler Enstitüsü, 2008. http://tez.sdu.edu.tr/Tezler/TS00657.pdf.
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Horkelová, Valentina. "Příprava společnosti na vstup na burzu." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2009. http://www.nusl.cz/ntk/nusl-222113.
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The folowing work deals with primary public issue of stocks - an external financial source of business activities. This source of finance is defined to the reader as: there are explained advantages and disadvantages of IPO Process, including supposition of succesful enter to the stock exchange. This work is concretly oriented on Pre-filing phase of a company for an enter to the stock exchange with the aim to set a procedure of IPO Process and apply it to a concrete company.
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Chambon, Amalia. "Le Crédit Burnup des combustibles REP-MOx français : méthodologie et conservatismes associés à l'évaluation JEFF-3.1.1." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00956580.
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En règle générale, les études de sûreté-criticité concernant les combustibles usés stockés, transportés ou retraités sont très conservatives et considèrent ce combustible comme neuf donc le plus réactif possible. Le " Crédit Burn-up " (CBU) est la prise en compte de l'antiréactivité du combustible irradié par rapport au combustible neuf. Une méthodologie CBU rigoureuse, développée par le CEA en collaboration avec AREVA-NC a récemment été validée et réévaluée pour les combustibles REP-UOx. Cependant, 22 réacteurs sur les 58 que compte la France utilisent également du combustible MOx. De plus en plus d'assemblages MOx irradiés doivent donc être entreposés et transportés, ce qui conduit les industriels à s'intéresser à la prise en compte du CBU pour ces applications, dans le but de pouvoir gagner des marges en terme de dimensionnement des installations. Des publications récentes et les travaux du Groupe de Travail Français sur le CBU ont souligné l'importance de la prise en compte des 15 produits de fission stables et non volatiles les plus absorbants qui sont à l'origine de la moitié de l'antiréactivité totale apportée dans les combustibles REP-MOx. C'est pourquoi, dans le but de garantir la sous-criticité de la configuration étudiée suivant les dispositions règlementaires relatives à la sûreté des installations, les biais de calcul affectant leur bilan-matière et leur effet individuel en réactivité doivent également être pris en considération dans les études de sûreté-criticité s'appuyant sur des calculs de criticité. Dans ce contexte, une revue bibliographique exhaustive a permis d'identifier les particularités des combustibles REP-MOx et une démarche rigoureuse a été suivie afin de proposer une méthodologie CBU adaptée à ces combustibles validée et physiquement représentative, permettant de prendre en compte les produits de fission et permettant d'évaluer les biais liés au bilan-matière et à l'antiréactivité des isotopes considérés. Cette démarche s'est articulée autour des études suivantes : * détermination de facteurs correctifs isotopiques permettant de garantir le conservatisme du calcul de criticité sur la base de la qualification du formulaire d'évolution DARWIN-2.3 pour les applications REP-MOx et d'une analyse des données nucléaires des produits de fission métalliques afin de déterminer l'impact des incertitudes associées sur le calcul de leur bilan matière ; * évaluation de l'antiréactivité individuelle des produits de fission sur la base des résultats d'interprétation des expériences d'oscillation des programmes CBU et MAESTRO, réalisés dans le réacteur expérimental MINERVE à Cadarache, avec le formulaire dédié PIMS développé au SPRC/LEPh avec mise à jour des schémas de calcul pour la criticité ; * élaboration de matrices de covariances réalistes associées à la capture de deux des principaux produits de fission du CBU REP-MOx : 149Sm et le 103Rh associées à l'évaluation JEFF-3.1.1 ; * détermination des biais et incertitudes " a posteriori " dus aux données nucléaires des actinides et produits de fission considérés pour deux applications industrielles (piscine d'entreposage et château de transport) par une étude de transposition réalisée avec l'outil RIB, développé au SPRC/LECy, qui a bénéficié à cette occasion de développements spécifiques et de mises à jour des données utilisées (importation des données de covariance issues de la bibliothèque COMAC V0 associée à JEFF-3.1.1 pour les isotopes 235,238U, 238,239,240,241,242Pu, 241Am et 155Gd et prise en compte des corrélations inter-réactions pour un même isotope). * évaluation de la méthodologie proposée pour deux applications industrielles (piscine d'entreposage et château de transport), démonstration de son intérêt et de sa robustesse.
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Roskoff, Nathan. "Development of a Novel Fuel Burnup Methodology and Algorithm in RAPID and its Benchmarking and Automation." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/84487.
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Fuel burnup calculations provide material concentrations and intrinsic neutron and gamma source strengths as a function of irradiation and cooling time. Detailed, full-core 3D burnup calculations are critical for nuclear fuel management studies, including core design and spent fuel storage safety and safeguards analysis. For core design, specifically during refueling, full- core pin-wise, axially-dependent burnup distributions are necessary to determine assembly positioning to efficiently utilize fuel resources. In spent fuel storage criticality safety analysis, detailed burnup distributions enable best-estimate analysis which allows for more effective utilization of storage space. Additionally, detailed knowledge of neutron and gamma source distributions provide the ability to ensure nuclear material safeguards.
The need for accurate and efficient burnup calculations has become more urgent for the simulation of advanced reactors and monitoring and safeguards of spent fuel pools. To this end, the Virginia Tech Transport Theory Group (VT3G) has been working on advanced computational tools for accurate modeling and simulation of nuclear systems in real-time. These tools are based on the Multi-stage Response-function Transport (MRT) methodology. For monitoring and safety evaluation of spent fuel pools and casks, the RAPID (Real-time Analysis for Particle transport and In-situ Detection) code system has been developed.
This dissertation presents a novel methodology and algorithm for performing 3D fuel bur- nup calculations, referred to as bRAPID- Burnup with RAPID . bRAPID utilizes the existing RAPID code system for accurate calculation of 3D fission source distributions as the trans- port calculation tool to drive the 3D burnup calculation. bRAPID is capable of accurately and efficiently calculating assembly-wise axially-dependent fission source and burnup dis- tributions, and irradiated-fuel properties including material compositions, neutron source, gamma source, spontaneous fission source, and activities. bRAPID performs 3D burnup calculations in a fraction of the time required by state-of-the-art methodologies because it utilizes a pre-calculated database of response functions.
The bRAPID database pre-calculation procedure, and its automation, is presented. The ex- isting RAPID code is then benchmarked against the MCNP and Serpent Monte Carlo codes for a spent fuel pool and the U.S. Naval Academy Subcritical Reactor facility. RAPID is shown to accurately calculate eigenvalue, subcritical multiplication, and 3D fission source dis- tributions. Finally, bRAPID is compared to traditional, state-of-the art Serpent Monte Carlo burnup calculations and its performance will be evaluated. It is important to note that the automated pre-calculation proceedure is required for evaluating the performance of bRAPID. Additionally, benchmarking of the RAPID code is necessary to understand RAPID's ability to solve problems with variable burnups distributions and to asses its accuracy.<br>Ph. D.
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Price, Simon Paul. "Sedimentation and neotectonics of the Burdur region, southwest Turkey." Thesis, University of Leicester, 1989. http://hdl.handle.net/2381/34941.
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The NE-SW trending Burdur-Acig?l-Baklan basin system of southwest Turkey represents the present-day configuration of a system initiated in late Miocene / early Pliocene times. During the Pliocene a half-graben, controlled by a NW-dipping planar fault system, developed in the area around Burdur. The Burdur Formation was deposited in this half-graben. Rapid subsidence is indicated by the lack of a well-developed footwall-sourced fan system. However, larger fans developed in the relay structures between en echelon fault segments. The centre of the basin was occupied by a deep saline lake. Orbitally-driven climatic change was the dominant control on sedimentation in this lake. The scarcity of wet-sediment deformation within the Burdur Formation suggests that levels of Pliocene seismicity were lower than twentieth century levels. Towards the end of the Pliocene the fault system controlling the Burdur basin became inactive and renewed faulting took place in the hangingwall of the old system. This event gave rise to the present-day configuration of narrow basins in the study area and was due to instability of the end-Pliocene topography. Both margins of the present-day Burdur, Acig?l and Baklan basins are faulted. In each case the major throw is on the fault on the southeast margin. A ? value of 1.18 calculated for the Burdur region assumes a planar fault geometry. As a curvature of up to 40 at depth cannot be ruled out this must be considered a minimum estimate. Each of the Burdur, Acig?l and Baklan basins is extending in a NW-SE direction (compared to the N-S extension direction of the Aegean). It is proposed that the basins are within a N-S trending deforming zone between the rapidly-extending Aegean region (to the west) and the relatively stable Anatolian plateau (to the east). The model adopted explains the clockwise rotation of fault-bounded blocks in the Burdur region. The dextral motion across the deforming zone, predicted by the model, may be a result of the anticlockwise rotation of western Turkey.
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Estabrook, Tracy Starr. "Burrow selection by burrowing owls in an urban environment." Thesis, The University of Arizona, 1999. http://hdl.handle.net/10150/278687.
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I surveyed parts of Tucson, Arizona to determine numbers of burrowing owl (Speotyto cunicularia) burrows present, identify characteristics associated with burrow sites, and assess reproductive success. I measured habitat characteristics at 48 winter, 58 breeding, and 48 random burrows. Random burrows were closer to perches (P) and farther from wash banks (P) than were active burrows, and had smaller entrance dimensions (P). Winter burrows were farther from human activity than were breeding burrows (P). Active sites had less total vegetation, and less visual obscurity than did random sites. Owls may have selected open sites to facilitate detection of predators or prey. Urbanization sometimes created conditions which appeared to attract owls, but also destroyed burrows. An average of 2.31 young fledged from 116 active burrows during 1997-1998. While comparable to other studies of burrowing owls occupying urban environments, this was lower than rates typically reported for the species.
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Manalo, Kevin. "Detailed analysis of phase space effects in fuel burnup/depletion for PWR assembly & full core models using large-scale parallel computation." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50351.
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Nuclear nonproliferation research and forensics have a need for improved software solutions, particularly in the estimates of the transmutation of nuclear fuel during burnup and depletion. At the same time, parallel computers have become effectively sized to enable full core simulations using highly-detailed 3d mesh models. In this work, the capability for modeling 3d reactor models is researched with PENBURN, a burnup/depletion code that couples to the PENTRAN Parallel Sn Transport Solver and also to the Monte Carlo solver MCNP5 using the multigroup option. This research is computationally focused, but will also compare a subset of results of experimental Pressurized Water Reactor (PWR) burnup spectroscopy data available with a designated BR3 PWR burnup benchmark. Also, this research will analyze large-scale Cartesian mesh models that can be feasibly modeled for 3d burnup, as well as investigate the improvement of finite differencing schemes used in parallel discrete ordinates transport with PENTRAN, in order to optimize runtimes for full core transport simulation, and provide comparative results with Monte Carlo simulations. Also, the research will consider improvements to software that will be parallelized, further improving large model simulation using hybrid OpenMP-MPI. The core simulations that form the basis of this research, utilizing discrete ordinates methods and Monte Carlo methods to drive time and space dependent isotopic reactor production using the PENBURN code, will provide more accurate detail of fuel compositions that can benefit nuclear safety, fuel management, non-proliferation, and safeguards applications.
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Dufek, Jan. "Development of New Monte Carlo Methods in Reactor Physics : Criticality, Non-Linear Steady-State and Burnup Problems." Doctoral thesis, Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10602.
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Rowe, Mireille Anjaline. "Analysis of light water reactors including 3-D deterministic burnup of a boiling water reactor fuel assembly." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024696.
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Kılınç, Ahmet Selçuk Kişioğlu Ahmet Nesimi. "Burdur il merkezi ilköğretim okullarındaki çocuklarda bağırsak parazitlerinin görülme sıklığı/." Isparta : SDÜ Sağlık Bilimleri Enstitüsü, 2006. http://tez.sdu.edu.tr/Tezler/TT00293.pdf.
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Moyo, Ropafadzo Kelebuhile. "Ecology and behaviour of burrowing prawns and their burrow symbionts." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13257.
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Includes bibliographical references.<br>Ecosystem engineers play important roles as determinants of community dynamics by modulating resource availability for other species. Marine soft-sediment ecosystems are dominated by burrowing engineers which indirectly create biogenic structures that often attract other species, often leading to the evolution of symbiotic relationships. Engineered structures provide non-trophic (e.g. refuge) and trophic functions (e.g. food) for burrow symbionts, however, the relative importance of these functions for symbionts is poorly understood. The behavioural interactions between burrowing engineers and their burrow symbionts are also poorly understood, mainly due to the difficulty in conducting behavioural observations in situ. This study aimed to enhance our understanding of the ecological processes and behavioural interactions underlying symbiotic relationships between a dominant South African ecosystem engineer (Callianassa kraussi) and its burrow symbiont (Betaeus jucundus) in soft sediment systems in Langebaan Lagoon. The study specifically quantified the relative importance of host abundance (a proxy for non-trophic functions) and food availability (trophic functions) provided by burrows of C. kraussi in influencing the abundance and distribution of B. jucundus. The second aim was to quantify behavioural changes of C. kraussi in the presence and absence of the symbiont B. jucundus and determine if the sex of C. kraussi influences its behavioural response to B. jucundus. Results indicate that at a patch scale, trophic functions (food availability) provided by burrows was more important than non-trophic functions in determining symbiont abundance and distribution. However, at an ecosystem scale, non-trophic functions could be a very important determinant of symbiont abundance and distribution. In terms of behavioural interactions, the presence of B. jucundus elicited three distinct behavioural responses from C. kraussi: intolerance, semitolerance and tolerance. In the absence of B. jucundus, there was no difference between male and female C. kraussi behaviour but this pattern changed in the presence of B. jucundus. Overall, the study has contributed to increasing our understanding of ecological processes that determine the abundance and distribution of burrow symbionts in marine soft-sediments as well as behavioural interactions between burrowers and their symbionts.
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Sloneker, G. Mark. "Burris Butler the man who helped save Standard Publishing Company /." Theological Research Exchange Network (TREN), 1992. http://www.tren.com.
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FERREIRA, LUIS L. H. C. "Desenvolvimento de agregados eletrofundidos para utilização em refratários para a zona de queima de fornos de cimento." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11448.
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Made available in DSpace on 2014-10-09T12:52:00Z (GMT). No. of bitstreams: 0<br>Made available in DSpace on 2014-10-09T13:57:03Z (GMT). No. of bitstreams: 0<br>Tese (Doutoramento)<br>IPEN/T<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Dias, Raphael Mejias. "Estudo de modelos para o comportamento a altas queimas de varetas combustíveis de reatores a água leve pressurizada." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85133/tde-08062016-134553/.
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Este trabalho tem como objetivo estudar as modificações introduzidas, ao longo de sucessivas versões, nos modelos empíricos do programa computacional FRAPCON utilizado para a simulação do comportamento sob irradiação de varetas combustíveis de Reatores a Água Leve Pressurizada (Pressurized Water Reactor - PWR) em regime de estado estacionário e sob condições de alta queima. No estudo, foram analisados os modelos empíricos utilizados pelo FRAPCON e que são apresentados em sua documentação oficial. Um estudo bibliográfico foi conduzido sobre os efeitos da alta queima em combustíveis nucleares visando melhorar o entendimento dos modelos utilizados pelo FRAPCON nestas condições. Foram feitas simulações do comportamento sob irradiação de uma vareta combustível típica de um reator PWR utilizando as versões 3.3, 3.4 e 3.5 do FRAPCON. Os resultados apresentados pelas diferentes versões do programa foram comparados entre si de forma a verificar as consequências das mudanças de modelo nos parâmetros de saída do programa. Foi possível observar que as modificações introduzidas trouxeram diferenças significativas nos resultados de parâmetros térmicos e mecânicos da vareta combustível, principalmente quando se evoluiu da versão FRAPCON-3.3 para a versão FRAPCON-3.5. Nessa ultima versão, obteve-se menores temperaturas na vareta combustível, menores tensões e deformações no revestimento, menor espessura da camada de oxido formada no revestimento a altas queimas na vareta combustível.<br>This work studies the modifications implemented over successive versions in the empirical models of the computer program FRAPCON used to simulate the steady state irradiation performance of Pressurized Water Reactor (PWR) fuel rods under high burnup condition. In the study, the empirical models present in FRAPCON official documentation were analyzed. A literature study was conducted on the effects of high burnup in nuclear fuels and to improve the understanding of the models used by FRAPCON program in these conditions. A steady state fuel performance analysis was conducted for a typical PWR fuel rod using FRAPCON program versions 3.3, 3.4, and 3.5. The results presented by the different versions of the program were compared in order to verify the impact of model changes in the output parameters of the program. It was observed that the changes brought significant differences in the results of the fuel rod thermal and mechanical parameters, especially when they evolved from FRAPCON-3.3 version to FRAPCON-3.5 version. Lower temperatures, lower cladding stress and strain, lower cladding oxide layer thickness were obtained in the fuel rod analyzed with the FRAPCON-3.5 version.
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Bratton, Isaac John. "Modeling and Validation of the Fuel Depletion and Burnup of the OSU Research Reactor Using MCNPX/CINDER'90." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343680610.
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Hamilton, Luana Flor Tavares. "Os usos do termo \"liberdade\" no anarquismo de Bakunin e no behaviorismo radical de Skinner." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/47/47132/tde-05102012-112802/.
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A liberdade é tema de discussões há muito tempo na humanidade. Enquanto algumas filosofias defendem essa noção de forma estrita, outras questionam sua própria existência. Duas filosofias que discutem a liberdade humana de forma aparentemente antagônica são o anarquismo e o behaviorismo. O presente trabalho teve por objetivo analisar se os conceitos de liberdade apresentado na obra de dois autores representativos dessas filosofias (Bakunin e Skinner, respectivamente) são similares entre si. Seu objetivo básico foi responder à seguinte questão: quais são as compatibilidades e as incompatibilidades entre o anarquismo e o behaviorismo radical, propostos por esses autores, no que diz respeito à concepção de liberdade do ser humano? Como método geral, foram analisadas algumas obras desses autores, com destaque para aquelas em que a discussão do conceito de liberdade se sobressai. A análise foi centrada na abordagem dessas filosofias sobre a ciência, a educação e o Estado. Como resultado, identificou-se como semelhante o fato de que ambos os autores defenderam que a natureza humana não tem qualidades intrinsecamente boas ou más, morais ou imorais. Para Bakunin, é possível conceber uma conjuntura de sociedade/cultura capaz de gerar homens com características defendidas pelos anarquistas como próprias do homem livre tais como solidariedade, cooperação e respeito às diferenças entre os indivíduos. Embora utilizando linguagem diferente, esse homem livre descrito por Bakunin não difere do suposto por Skinner ao analisar que o ambiente (ou as contingências ambientais) é que seleciona os comportamentos do indivíduo. Portanto, para ambos, o indivíduo é formado no seu contato com o ambiente. Apesar de concordantes nesse aspecto, eles se diferenciam pela maior ou menor ênfase nas ferramentas propostas para promover mudanças no comportamento e para planejar culturas que se aproximem da ideal. Skinner fornece essas ferramentas com base nas proposições de uma ciência do comportamento, enquanto Bakunin apenas descreve características das relações interpessoais em uma sociedade que a levaria a produzir homens que ele chamaria de livres, sem deixar clara a forma pela qual se estabeleceria essa cultura. Portanto, conclui-se que, a despeito do antagonismo geralmente sugerido entre ambas as filosofias, a concepção de liberdade presente na obra de Bakunin não é incompatível com a proposta por Skinner. Sugere-se que um diálogo entre as duas filosofias pode ser profícuo, obtendo-se do anarquismo os objetivos para uma sociedade mais igualitária e justa e do behaviorismo, o caminho para atingi-los<br>Freedom is the subject of long discussions in humanity. While some philosophies argue that notion in a strict way, others question their own existence. Two philosophies that argue the human freedom so seemingly antithetical are the anarchism and behaviorism. This study aimed to analyze the concept of freedom presented in the work of two authors representing those philosophies (Bakunin and Skinner, respectively) are similar. Its basic purpose was to answer the question below: What are the compatibilities and incompatibilities between anarchism and radical behaviorism, proposed by these authors, with regard to the conception of human freedom? As a general method, were analyzed some of the works of these authors, especially those in which the concept of freedom was highlighted. The analysis was centered on the approach that these philosophies have on science, education and the state. As a result, it was identified as similar to the fact that both authors have argued that human nature is not intrinsically good or bad qualities, moral or immoral. For Bakunin, it is possible to conceive of a scenario of society/culture capable of generating men with characteristics defended by anarchists themselves of a free man such as solidarity, cooperation and respect for differences among individuals. Although using different language, this free man, described by Bakunin, does not differ from the assumed by Skinner to examine the environment (or environmental contingencies) that selects the behavior of the individual. Therefore, for both, the individual consists in his contact with the environment. Although consistent in this respect, they differ by a greater or lesser emphasis on the tools proposed to promote changes in behavior and make the planning of cultures that are close to the \"ideal\". Skinner provides these tools based on the propositions of a science of behavior, while Bakunin only describes characteristics of interpersonal relationships in a society that would produce men he would call \"free\" without making clear the way to establish this culture. Therefore, we conclude that, in spite of the generally suggested antagonism between the two philosophies, the concept of freedom present in the work of Bakunin is not incompatible with the one proposed by Skinner. It is suggested that a dialogue between the two philosophies can be fruitful, having regard to the goals of anarchism to a more egalitarian and just society, while from the behaviorism can derive the path to achieve them
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Karlsson, Thomas. "Götisk kabbala och runisk alkemi : Johannes Bureus och den götiska esoterismen." Doctoral thesis, Stockholms universitet, Institutionen för etnologi, religionshistoria och genusstudier, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-37152.
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Gothicism in general, and the Swedish Gothicism in particular, had a close connection to the esoteric currents that were flourishing all over Europe in the Early Modern Period. Apocalyptic predictions and prophecies useful to Gothic propaganda were derived from contemporary esoteric streams, but alongside these came Hermetic and Neo-Platonic speculations of a more individual character that emphasized man’s gradual ascension toward a higher state. The foremost representative for this union of Gothicism and Esotericism was Johannes Bureus (1568-1652). Although a pioneer of runology and Swedish grammatical studies, Bureus felt he made his greatest contributions in the sphere of mysticism. Influenced by the concept of a Philosophia Perennis, Bureus believed this eternal philosophy was not only expressed by the ancient Greeks, Egyptians, and Hebrews, but also by the ancient Norse. Bureus represents what could be termed an Esoteric Gothicism. In his work, the ideal of Gothicism melds with Esotericism in the form of Alchemy, Kabbalah, Hermeticism, Astrology, and Magic. Bureus himself called his esoteric system a Nordic Kabbalah, a “Notaricon Suethica,” or a “Kabala Upsalica.” Bureus’s Esotericism is explicated primarily in his manuscripts such as the Cabbalistica, Antiquitates Scanziana, and especially Adulruna Rediviva (the latter produced in seven versions over a forty-year period), but also in his major opus, dedicated to his pupil Queen Christina, the printed apocalyptic book Nordlanda Lejonsens Rytande. In examining Esoteric Gothicism we can discern a further tendency within Gothicism beyond the national chauvinism typically seen as exemplifying the movement. In Bureus’s work, Gothic motifs are combined with runes and Old Norse themes in an imaginative manner, but most characteristic of Bureus is how he uses the results to describe a highly individual path of initiation which leads to unity with God. Bureus’s ideas may seem eccentric to a modern reader, but properly situating them in their historical context reveals the role he played in an influential current in European intellectual and spiritual history, a current often referred to by scholars as Western Esotericism.
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Beauman, Richard L. Mendonça Mary T. "The effects of burrow collapse on the gopher tortoise (Gopherus polyphemus)." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Biological_Sciences/Thesis/Beauman_Richard_19.pdf.
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Florey, Cassidy L. "Description of burrow structure for four crayfish species (Decapoda: Astacoidea: Cambaridae)." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1555413606702675.
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Karlsson, Thomas. "Götisk kabbala och runisk alkemi Johannes Bureus och den götiska esoterismen /." Stockholm : Institutionen för etnologi, religionshistoria och genusstudier, Stockholms universitet, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-37152.
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Jones, Carleton. "Perceived and constructed landscapes in Neolithic Ireland." Thesis, University of Cambridge, 1997. https://www.repository.cam.ac.uk/handle/1810/272978.
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Younkin, Timothy R. "Piecewise prediction of nuclide densities with control blade use as a function of burnup in BWR used nuclear fuel." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53118.
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In order to improve the efficiency of dry used nuclear fuel (UNF) storage, reduced reactivity methods are being developed for various reactor types and operating conditions. Sub-criticality must be maintained in the storage configuration and conservative computer simulations are used as the primary basis for loading the storage casks. Methodologies are now being developed to reduce the amount of modeling and computation in order to make conservative assessments of how densely fuel can be packed. The SCALE/TRITON (Standardized Computer Analyses for Licensing Evaluation / Transport Rigor Implemented with Time-dependent Operation for Neutronic Depletion) code system has been used to simulate boiling water reactor (BWR) operating conditions in order to investigate nuclide densities in UNF and how the use of control rod blades affect nuclide densities found in UNF. Rodded and unrodded operating cases for a fuel assembly have been used as bounding cases and are used as reference solutions in a piecewise data approximation methodology (PDA method). A variety of control blade insertion patterns have been used with the PDA method and simulated in TRITON in order to observe trends in nuclide densities with varying control blade use. The PDA method is compared with TRITON simulated data in order to evaluate the validity and accuracy of the PDA method. The PDA method gives very accurate results for fissile nuclides but is insufficient in treating densities as a function of burnup for fission products and fertile nuclides. Predicting nuclide densities from temporally balanced control blade insertion and withdrawal patterns is also a strength of the PDA method. The PDA method, however, is not capable of properly accounting for neutron spectral shifts and the behavior in nuclide densities brought about by the spectral shift or nuclide density saturation. Observing the causes for the shortcomings in the PDA method, a more robust methodology can be developed.
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Sensi, Maria Assunta. "Alberto Burri et sa contribution au renouvellement du langage artistique de l’après-guerre." Thesis, Paris 4, 2011. http://www.theses.fr/2011PA040133.
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Ce travail examine l’œuvre de l’artiste abstrait italien Alberto Burri (Città di Castello, 1915 - Nice, 1995) et ses nouvelles contributions à partir de 1945, notamment dans l’utilisation de la matière en peinture : Goudrons, Sacs, Bois, Fers, Plastiques, jusqu’aux Cretti et Cellotex. La métamorphose de sa recherche est contemplée en faisant état des différentes phases de sa création. C’est dans le Texas, durant sa captivité au cours de la Seconde Guerre mondiale qu’elle vit le jour et continua sans cesse de prendre forme, dans chaque lieu qu’il habita : Rome, où il entra en contact et influença nombre d’artistes, et aussi Los Angeles, Beaulieu-sur-Mer. Prenant également en compte la réception critique de ses créations en Italie et ailleurs, on étudie ses spéculations par rapport à celles des Avant-gardes et à d’autres artistes travaillant avec de la matière, en France, en Italie, dans d’autres pays européens, aux États-Unis et au Japon (entre autres, Gutaï, Néo-Dada, Nouveau Réalisme, Arte Povera…) Tableaux, sculptures, grands «Cycles», œuvre gravé, livres d’artiste, décors pour le théâtre, Sculptures-Théâtre : un voyage monumental, où Burri - entre révolution et classicisme - concevant des œuvres puissantes et raffinées, à l’ «équilibre déséquilibré», renouvela complètement le langage artistique de l’après-guerre<br>This survey examines the work of the Italian abstract artist Alberto Burri (Città di Castello, 1915 - Nice, 1995) and his original contributions using a variety of materials in artistic creation since 1945: Tar, Burlap, Wood, Iron, Plastic, and finally Cretti and Cellotex. The metamorphosis of his research is evidenced through all the different phases of his activity, starting in Texas at the time of his internment during WWII and constantly continued in every place he lived: Rome, where he met and influenced many artists, Los Angeles, Beaulieu-sur-Mer. Also examining the critical reception of his work in Italy and elsewhere, his speculations have been studied in relation to those of the Avant-garde and other artists working with materials, in France, Italy, other European countries, United States and Japan (among others, Gutaï, New-Dada, Nouveau Réalisme, Arte Povera…) Paintings, sculptures, big "Cycles", graphic work, artists’ books, stage sets, Theatre-Sculptures: a monumental journey, during which Burri - between revolution and classicism - created powerful and refined works of "unbalanced balance", completely renewing the post-war artistic language
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Metz, Hillery. "The Genetic Basis of Behavior: Burrow Construction in Deer Mice (Genus Peromyscus)." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467514.
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Understanding how complex, adaptive behavior evolves is a major goal of biological research. Phenotypic differences between closely-related species often arise due to evolution by natural selection and can be a powerful resource for understanding biological diversity and its mechanistic underpinnings. In this dissertation, I capitalize on striking behavioral differences between two interfertile sister species of Peromyscus rodents. I pursue the proximate mechanisms underlying this behavioral adaptation by investigating both the ontogeny and genetics of innate differences in burrow construction behavior in Peromyscus polionotus and P. maniculatus.
In Chapter 1, I compare the ontogeny of burrow construction behavior of Peromyscus polionotus and P. maniculatus across early development. I find that P. polionotus begins burrowing precociously (as early as 17 days of age) compared to P. maniculatus (27 days of age), despite P. polionotus being physically smaller and less active in a wheel running assay. Furthermore, juvenile P. polionotus constructed long burrows complete with species-specific escape tunnels. Interspecific cross-fostering did not alter the developmental trajectory of either species, indicating that these differences are innate. Moreover, F1 hybrids followed the behavioral ontogeny of P. polionotus, indicating that precocious burrow construction segregates in a P. polionotus-dominant manner. Finally, I show that a quantitative trait locus (QTL) associated with adult tunnel length in these species is predictive of precocious digging in recombinant F2 hybrids, demonstrating that either a single pleiotropic locus or a group of tightly-linked genes control behavioral differences across life stages in P. polionotus.
In Chapter 2, I dissect the genetic architecture of this complex behavior in adult animals using an experimental cross. By introgressing the burrow architecture of P. polionotus into the genetic background of P. maniculatus, I analyze the underlying genetic architecture of differences in burrowing behavior, and show that escape tunnels are likely a threshold trait. Next, I use a novel image-based analysis to collect measurements of burrow shape and demonstrate the utility of a more rigorous measurement of extended phenotypes.
Finally, in Chapter 3, I combine two forward-genetics approaches—QTL mapping and transcriptome analysis—to nominate specific candidate genes for the differences in burrowing behavior between P. polionotus and P. maniculatus. Using a large advanced backcross mapping population (n=751), I detect five QTL contributing to differences in burrow architecture between these species: three loci for entrance tunnel length variation, and two loci for escape tunnel length. In the transcriptome study, I focus on gene expression in F1 hybrids to detect allele-specific expression (ASE), as ASE in an F1 hybrid indicates cis-regulatory differences between the parental lineages. I find widespread bias favoring expression from the P. polionotus-allele in F1 hybrid brains, which may be a molecular reflection of P. polionotus-like burrowing behavior of hybrids. Finally, I use ASE to nominate candidate genes within the detected QTL regions, and find genes related to behavioral disorders, circadian rhythms, and activity patterns; these genes represent promising candidates for future functional studies.<br>Biology, Organismic and Evolutionary