Disposal of spent nuclear fuel and high-level waste: design and technical/economic analysis

An economic model for the back end of the nuclear fuel cycle was developed for a once-through cycle, a standard reprocessing cycle, and a reprocessing cycle with fractionation of cesium and strontium. The development of the model was performed under the expected political constraints and scenario for the first nuclear waste repository. Technical issues concerning the repository design were analyzed, in particular the thermal design. A parametric thermal analysis was performed for waste emplaced in five different geologic formations: salt, granite, basalt, shallow tuff, and deep tuff. The results of the thermal analysis, in the form of maximum permissible loadings, were incorporated into the economic model. The economic analysis was performed for a variety of situations in order to compare the five possible repository host rocks, the three different back end cycles, and different locations of the Monitored Retrievable Storage Facility (MRS). A sensitivity analysis was also performed for evaluating the effect of variations in some parameters in the final cost of the system;The results of the thermal analysis indicated that the maximum permissible thermal loadings in granite and tuff were relatively high, whereas for basalt the thermal loadings are very restricted for both spent fuel and reprocessed waste and for salt the loadings are very restricted for spent fuel only. The results of the economic analysis showed that a repository in basalt always resulted in higher costs than in any other rock; the other repository media yield comparable costs, except in the case of spent fuel disposal in salt, where the costs are higher. Co-location of the MRS with the repository results in a lower system cost than locating it away from the repository. The regular reprocessing cycle presents the lower storage plus disposal costs among the three cycles studied, and disposal of spent fuel has the highest costs associated. The model proved to be very sensitive to variations of the discount rate, the storage facility capital cost, and the delay of repository backfilling after waste emplacement. Lower waste storage plus disposal costs can be obtained by delaying disposal in the fractionation waste cycle in any rock or disposal of any waste form in basalt. In the other cases, aging the waste before disposal does not reduce, in general, the total cost

Constraints on Supersymmetric Dark Matter for Heavy Scalar Superpartners

We study the constraints on neutralino dark matter in minimal low energy supersymmetry models and the case of heavy lepton and quark scalar superpartners. For values of the Higgsino and gaugino mass parameters of the order of the weak scale, direct detection experiments are already putting strong bounds on models in which the dominant interactions between the dark matter candidates and nuclei are governed by Higgs boson exchange processes, particularly for positive values of the Higgsino mass parameter mu. For negative values of mu, there can be destructive interference between the amplitudes associated with the exchange of the standard CP-even Higgs boson and the exchange of the non-standard one. This leads to specific regions of parameter space which are consistent with the current experimental constraints and a thermal origin of the observed relic density. In this article we study the current experimental constraints on these scenarios, as well as the future experimental probes, using a combination of direct and indirect dark matter detection and heavy Higgs and electroweakino searches at hadron colliders.Comment: 32 pages, 13 figure

Models animals per a l'estudi de la diabetis

La diabetis mellitus (DM) s'origina per mancança dels efectes de la insulina, bé perquè el pàncrees és incapaç de produir-ne, bé perquè els seus òrgans diana no responen adequadament, o per una combinació d'ambdues situacions, amb l'aparició d'hiperglucèmia, poliúria i polidípsia. En absència total de la insulina (DM tipus 1) hi ha metabolisme accelerat de proteïna muscular i greix, que pot acabar en cetoacidosi metabòlica i mort. Amb activitat insulínica residual (DM tipus 2), la malaltia es cronifica, amb obesitat, micro i macroangiopaties, i les seves manifestacions clíniques (insuficiència renal, alteracions retinals, neuropaties, infart de miocardi, etc.). La DM és un problema sanitari de primer ordre i, en ser una malaltia complexa, en la qual intervenen factors genètics i adquirits, no hi ha un model animal perfecte per estudiar-la que reprodueixi totes les característiques de la malaltia humana. La majoria de models utilitzen rosegadors, per una sèrie d'avantatges: petita grandària, facilitat d'obtenció, ràpid recanvi generacional i facilitat de manipulació genètica. En aquesta revisió parlarem de models induïts, en els quals reproduïm la malaltia mitjançant una manipulació determinada, models espontanis, consistents en soques d'animals que s'han seleccionat genèticament al llarg de successives generacions per tal que manifestin la malaltia, i models obtinguts per modificació genètica.Animal experimental models for the study of diabetes. Diabetes mellitus (DM) originates from a lack of insulin effects, due to a deficit of pancreatic production, or to an inadequate response of target organs, or a combination of both situations, ensuing hyperglycaemia, polyuria and polydipsia. When insulin is totally absent (Type 1 DM), there is an increased metabolism of muscular protein and fat, ending in metabolic ketoacidosis and death. With a residual insulin activity (Type 2 DM), diabetes becomes chronic, with obesity, micro- and macroangiopathies and their corresponding clinical manifestations (renal failure, retinal alterations, neuropathies, myocardial infarct, etc.). DM is a serious health problem and, as it is a complex illness, in which participate genetic and acquired factors, there is not a single perfect animal model for its study, able to reproduce all the characteristics of the human malady. The great majority of models use rodents, given their advantages: small size, easy access, fast reproduction rate, and a feasible genetic manipulation. We will discuss about induced models, in which the illness is reproduced by means of a specific manipulation, spontaneous models, comprised by animal breeds genetically selected along successive generations in order to them to develop the malady, and genetically engineered models

Simple sugar intake and hepatocellular carcinoma: epidemiological and mechanistic insight

Sugar intake has dramatically increased during the last few decades. Specifically, there has been a clear trend towards higher consumption of fructose and high fructose corn syrup, which are the most common added sugars in processed food, soft drinks and other sweetened beverages. Although still controversial, this rising trend in simple sugar consumption has been positively associated with weight gain and obesity, insulin resistance and type 2 diabetes mellitus and non-alcoholic fatty liver disease. Interestingly, all of these metabolic alterations have also been related to the development of hepatocellular carcinoma. The purpose of this review is to discuss the evidence coming from epidemiological studies and data from animal models relating the consumption of simple sugars, and specifically fructose, with an increased risk of hepatocellular carcinoma and to gain insight into the putative molecular mechanisms involved

Constraints on supersymmetric dark matter for heavy scalar superpartners

We study the constraints on neutralino dark matter in minimal low energy supersymmetry models and the case of heavy lepton and quark scalar superpartners. For values of the Higgsino and gaugino mass parameters of the order of the weak scale, direct detection experiments are already putting strong bounds on models in which the dominant interactions between the dark matter candidates and nuclei are governed by Higgs boson exchange processes, particularly for positive values of the Higgsino mass parameter μ. For negative values of μ, there can be destructive interference between the amplitudes associated with the exchange of the standard CP-even Higgs boson and the exchange of the nonstandard one. This leads to specific regions of parameter space which are consistent with the current experimental constraints and a thermal origin of the observed relic density. In this article, we study the current experimental constraints on these scenarios, as well as the future experimental probes, using a combination of direct and indirect dark matter detection and heavy Higgs and electroweakino searches at hadron colliders

The EBR-II Probabilistic Risk Assessment: Results and insights

This paper summarizes the results from the recently completed EBR-II Probabilistic Risk Assessment (PRA) and provides an analysis of the source of risk of the operation of EBR-II from both internal and external initiating events. The EBR-II PRA explicitly accounts for the role of reactivity feedbacks in reducing fuel damage. The results show that the expected core damage frequency from internal initiating events at EBR-II is very low, 1. 6 10[sup [minus]6] yr[sup [minus]1], even with a wide definition of core damage (essentially that of exceeding Technical Specification limits). The probability of damage, primarily due to liquid metal fires, from externally initiated events (excluding earthquake) is 3.6 10[sup [minus]6] yr[sup [minus]1]. overall these results are considerably better than results for other research reactors and the nuclear industry in general and stem from three main sources: low likelihood of loss of coolant due to low system pressure and top entry double, vessels; low likelihood of loss of decay heat removal due to reliance on passive means; and low likelihood of power/flow mismatch due to both passive feedbacks and reliability of rod scram capability

15-Membered triolefinic macrocycles, their coordination chemistry with transition metals, and the catalytic properties of their palladium metal complexes : A review

(E,E,E)-1,6,11-Tris(arenesulfonyl)-1,6,11-triazacyclopentadeca-3,8,11-trienes, 1, are prepared from arenesulfonamides and trans-1,4-dibromo-2-butene. Macrocycles 1 coordinate palladium(0), platinum(0), and silver(I), and the palladium complexes are useful and reutilizable catalysts or precatalysts in Suzuki cross-couplings, butadiene telomerizations, hydroarylation of alkynes, and in the Heck reaction. Structurally related macrocycles are also available by similar synthetic procedures

Analysis of accident sequences and source terms at waste treatment and storage facilities for waste generated by U.S. Department of Energy Waste Management Operations, Volume 1: Sections 1-9

This report documents the methodology, computational framework, and results of facility accident analyses performed for the U.S. Department of Energy (DOE) Waste Management Programmatic Environmental Impact Statement (WM PEIS). The accident sequences potentially important to human health risk are specified, their frequencies are assessed, and the resultant radiological and chemical source terms are evaluated. A personal computer-based computational framework and database have been developed that provide these results as input to the WM PEIS for calculation of human health risk impacts. The methodology is in compliance with the most recent guidance from DOE. It considers the spectrum of accident sequences that could occur in activities covered by the WM PEIS and uses a graded approach emphasizing the risk-dominant scenarios to facilitate discrimination among the various WM PEIS alternatives. Although it allows reasonable estimates of the risk impacts associated with each alternative, the main goal of the accident analysis methodology is to allow reliable estimates of the relative risks among the alternatives. The WM PEIS addresses management of five waste streams in the DOE complex: low-level waste (LLW), hazardous waste (HW), high-level waste (HLW), low-level mixed waste (LLMW), and transuranic waste (TRUW). Currently projected waste generation rates, storage inventories, and treatment process throughputs have been calculated for each of the waste streams. This report summarizes the accident analyses and aggregates the key results for each of the waste streams. Source terms are estimated and results are presented for each of the major DOE sites and facilities by WM PEIS alternative for each waste stream. The appendices identify the potential atmospheric release of each toxic chemical or radionuclide for each accident scenario studied. They also provide discussion of specific accident analysis data and guidance used or consulted in this report