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Journal articles on the topic "Am7 .m35 1996"
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Allen, Charles T., Marwan S. Kharboutli, and Noel P. Tugwell. "HELIOTHINES AND DAMAGE ON SELECTED BOLLGARD COTTON CULTIVARS, 1996 AND 1998." Arthropod Management Tests 25, no. 1 (January 1, 2000). http://dx.doi.org/10.1093/amt/25.1.m15.
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Jackson, D. Michael, J. R. Bohac, and J. D. Mueller. "EVALUATION OF REGIONAL SWEET POTATO ENTRIES FOR RESISTANCE TO SOIL INSECT PESTS, 1996." Arthropod Management Tests 27, no. 1 (January 1, 2002). http://dx.doi.org/10.1093/amt/27.1.m15.
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Davydov, Alexander A., Stefano Marcugini, and Fernanda Pambianco. "On the weight distribution of the cosets of MDS codes." Advances in Mathematics of Communications, 2021, 0. http://dx.doi.org/10.3934/amc.2021042.
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<p style='text-indent:20px;'>The weight distribution of the cosets of maximum distance separable (MDS) codes is considered. In 1990, P.G. Bonneau proposed a relation to obtain the full weight distribution of a coset of an MDS code with minimum distance <inline-formula><tex-math id="M1">\begin{document}$ d $\end{document}</tex-math></inline-formula> using the known numbers of vectors of weights <inline-formula><tex-math id="M2">\begin{document}$ \le d-2 $\end{document}</tex-math></inline-formula> in this coset. In this paper, the Bonneau formula is transformed into a more structured and convenient form. The new version of the formula allows to consider effectively cosets of distinct weights <inline-formula><tex-math id="M3">\begin{document}$ W $\end{document}</tex-math></inline-formula>. (The weight <inline-formula><tex-math id="M4">\begin{document}$ W $\end{document}</tex-math></inline-formula> of a coset is the smallest Hamming weight of any vector in the coset.) For each of the considered <inline-formula><tex-math id="M5">\begin{document}$ W $\end{document}</tex-math></inline-formula> or regions of <inline-formula><tex-math id="M6">\begin{document}$ W $\end{document}</tex-math></inline-formula>, special relations more simple than the general ones are obtained. For the MDS code cosets of weight <inline-formula><tex-math id="M7">\begin{document}$ W = 1 $\end{document}</tex-math></inline-formula> and weight <inline-formula><tex-math id="M8">\begin{document}$ W = d-1 $\end{document}</tex-math></inline-formula> we obtain formulas of the weight distributions depending only on the code parameters. This proves that all the cosets of weight <inline-formula><tex-math id="M9">\begin{document}$ W = 1 $\end{document}</tex-math></inline-formula> (as well as <inline-formula><tex-math id="M10">\begin{document}$ W = d-1 $\end{document}</tex-math></inline-formula>) have the same weight distribution. The cosets of weight <inline-formula><tex-math id="M11">\begin{document}$ W = 2 $\end{document}</tex-math></inline-formula> or <inline-formula><tex-math id="M12">\begin{document}$ W = d-2 $\end{document}</tex-math></inline-formula> may have different weight distributions; in this case, we proved that the distributions are symmetrical in some sense. The weight distributions of the cosets of MDS codes corresponding to arcs in the projective plane <inline-formula><tex-math id="M13">\begin{document}$ \mathrm{PG}(2,q) $\end{document}</tex-math></inline-formula> are also considered. For MDS codes of covering radius <inline-formula><tex-math id="M14">\begin{document}$ R = d-1 $\end{document}</tex-math></inline-formula> we obtain the number of the weight <inline-formula><tex-math id="M15">\begin{document}$ W = d-1 $\end{document}</tex-math></inline-formula> cosets and their weight distribution that gives rise to a certain classification of the so-called deep holes. We show that any MDS code of covering radius <inline-formula><tex-math id="M16">\begin{document}$ R = d-1 $\end{document}</tex-math></inline-formula> is an almost perfect multiple covering of the farthest-off points (deep holes); moreover, it corresponds to an optimal multiple saturating set in the projective space <inline-formula><tex-math id="M17">\begin{document}$ \mathrm{PG}(N,q) $\end{document}</tex-math></inline-formula>.</p>
Books on the topic "Am7 .m35 1996"
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Making Histories in Museums. Bloomsbury Publishing Plc, 2005.
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Forecasting: Principles and practice. OTexts, 2018.
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Sabat, Lovely, Binaya Kumar Panigrahi, Arundaya Sabat, and Minakshi Mishra. "EFFECT OF RECYCLED AGGREGATE ON NORMAL STRENGTH CONCRETE." In Futuristic Trends in Construction Materials & Civil Engineering Volume 3 Book 2, 1–11. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bice2p1ch1.
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Recycled coarse aggregate (RCA) concrete construction technique can be called as ‘green concrete’, as it minimizes the environmental hazard of the concrete waste disposal. Coarse aggregate plays a vital role for formation of concrete as the amount is more than that of fine aggregate. In the present experimental study is carried out to determine the strength characteristic of recycled aggregate in structural concrete as an alternative material for coarse aggregates. For a particular mix design, coarse aggregate is replaced with recycled bricks by 0%, 10% and 20%. A mix of M35 grade concrete was designed. Firstly the casting and testing of specimens for M35 grade concrete was carried out. In Phase-II, the test results are compared with different code values. Fresh concrete was tested for its workability properties through slump test, compaction factor test and Vee-Bee test. Compressive, flexural and split tensile strength test for recycled coarse aggregate concrete was carried out for hardened concrete. Results of the present study are compared with similar results available in literature associated with normal coarse aggregate. The obtained values of strength were compared with the IS-456- 2000, ACI-1985, ACI-1992 and ACI-1995 results. Compressive strength, flexural strength and split tensile strength reduces with increase in percentage of recycled aggregate but the reduction is not prominent up to 20%. The experimental results were well in agreement with IS-456-2000 predicted results. ACI-1985 and ACI-1992 overestimates while predicted values by ACI- 1995 underestimates.
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Rana, Pooja, Jeganathan Chockalingam, and Arvind Chandra Pandey. "Space-Time Integrated Landslide Hazard Zonation near Tehri Dam in Uttarakhand, India." In Advances in Geospatial Technologies, 122–46. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-1814-3.ch007.
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The study aims to predict landslide hazard zones near Tehri Dam in Uttarakhand State located in the Western Himalayas in India. Four different models were analysed: Weight Factor Model (M1), Multiple Factor Model (M2), Statistical Bivariate model (M3) and Analytical Hierarchical Processes (AHP) model (M4). Five different combination of reference landslides were used for deriving weights of the classes in the factor maps: all the landslides from 1990, 2002 & 2010 (C1); landslides from 2010 (C2); landslides from 1990 & 2002 (C3); landslides located within 500m from roads (C4); landslides located beyond 500m from roads (C5). The accuracy resulted from each model in each combination was [Mn:C1, C2…Cn]: M1: 60,44,46,38,66%; M2:70,76,79,73,71%; M3:45,37,23,36,85%; M4:64,51,51,64,36%. Multiple Factor Model (M2) resulted in a consistently high accuracy in all the combinations. Finally, the 20 different model outputs were integrated to derive unified hazard zonation maps based on: (a) mean (85% accuracy), (b) penalisation (57% accuracy) and (c) k-means cluster (80% accuracy) approaches.
Conference papers on the topic "Am7 .m35 1996"
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Gubaidullin, A. A., and B. R. Sehgal. "Simeco Tests in a Melt Stratified Pool." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22709.
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In the last phase of the core degradation, an oxidic melt pool of mainly UO2, ZrO2, and unoxidized Zircaloy and stain-less steel will form in the lower head of the RPV (Theofanous et al., 1996). A molten metal layer (composed mainly of Fe and Zr) will rest on the top of the crust of the oxidic pool. A thin oxidic crust layer of frozen core material is formed on the vessel’s inside wall. In this bounding configuration, thermal loads to the RPV walls are determined by natural convection heat transfer driven by internal heat sources. Decay heat from fission products is assumed to be generated uniformly within the oxidic pool and generally no heat generation is considered in the upper metallic layer. For example, in a hypothetical severe accident scenario for an AP600-like reactor, the following values can be expected: volumetric heat generation Qv ∼ 1 MW/m3, volume of the oxidic pool V ∼ 10 m3, radius R = 2 m, temperatures in the oxidic pool T ∼ 2700°C, temperatures in the metal layer T ∼ 2000°C, maximum depth ratio of the metal layer to the oxidic pool L12 ∼ 0:3, properties of the oxidic pool, depending on melt composition, as characterized by the Prandtl number, Pr ∼ 0:6, properties of the metallic layer Pr < 0:1, the intensity of convective motion, as characterized by the Rayleigh number, Ra ∼ 1015–1016 (Theofanous et al., 1996). The time scale of core melt pool formation is estimated as 1/2 to 1 hour (Sehgal, 1999). Indeed, these estimates could vary, depending very much on the accident scenario and the type of reactor.
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Triay, Inés R., Mark L. Matthews, Leif G. Eriksson, and Frank D. Hansen. "The Waste Isolation Pilot Plant: A Global Opportunity for Partnerships With a Purpose." In ASME 2001 8th International Conference on Radioactive Waste Management and Environmental Remediation. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/icem2001-1146.
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Abstract On March 26, 1999, the United States (U.S.) Department of Energy (DOE) Carlsbad Field Office (CBFO) opened the Waste Isolation Pilot Plant (WIPP) in New Mexico, United States of America (USA), for safe deep geological disposal of up to 175,584 cubic meters (m3) of long-lived radioactive wastes/materials (LLRMs). Twenty-four years of intensive, iterative interactions with scientific, environmental, public, institutional, political, and regulatory interest groups resolved all regulatory and legal challenges involved in bringing a deep geological repository for LLRMs to adequate scientific, technical, institutional, political, and public acceptance and fruition. International strategic partnerships and research and development (R&D) collaborations are cornerstones in both past and current strategies designed to timely, cost-effectively, and safely accomplish the CBFO mission. The primary objectives of the CBFO’s international programs are to: 1. Acquire information supporting the CBFO mission. 2. Present and share CBFO mission information, expertise, and facilities of potential interest and/or value to other radioactive waste management and disposal programs, including using the WIPP underground research laboratory (URL) for joint R&D and training.
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ALMEIDA, ANTONIO THIAGO SOARES DE, EDUARDO DE SOUZA MAFRA, GUSTAVO HENRIQUE FERREIRA MAIA, JOSEMAR DA SILVA XAVIER, NOEME DA COSTA SANTOS, RICARDO CEZAR DOS SANTOS MARQUES, SANDERLEIA OLIVEIRA DOS SANTOS, and VICTOR FASSINA BROCCO. "DETERMINAÇÃO DA DENSIDADE BÁSICA E TEOR DE EXTRATIVOS DE SETE ESPÉCIES FLORESTAIS COMERCIALIZADAS NAS SERRARIAS DE ITACOATIARA-AM." In Brazilian Congress. brazco, 2020. http://dx.doi.org/10.51162/brc.dev2020-00015.
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O objetivo do estudo foi realizar a identificacao cientifica e determinar a densidade basica e teor de extrativos de residuos madeireiros provenientes de sete especies comercializadas nas serrarias de Itacoatiara - AM. Para a determinacao da densidade basica foi utilizada a Norma Brasileira - NBR 7190 (ABNT, 1997), e para o teor de extrativos tomou-se como base a norma ABTCP M3 / 69 (ABTCP, 1974). As madeiras de muiracatiara, tanibuca e muirapiranga sao consideradas de alta densidade e as madeiras de macacauba, angelim-rajado, violeta e sucupira-vermelha consideradas como de media densidade. O teor de extrativos totais, obteve maiores indices para as especies muirapiranga, muiracatiara e tanibuca, enquanto que macacauba obteve o menor valor. A densidade basica encontra-se dentro do esperado para as especies tropicais. De modo geral, tem-se a necessidade de realizar analise qualitativa dos constituintes quimicos desses residuos, a fim de identificar possiveis aplicacoes tecnologicas e industriais.,
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Neubauer, Josef. "Treatment and Conditioning of Low- and Intermediate Level Radioactive Waste at the Austrian Research Centers Seibersdorf (ARCS)." In ASME 2001 8th International Conference on Radioactive Waste Management and Environmental Remediation. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/icem2001-1154.
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Abstract The Austrian Research Centers Seibersdorf (ARCS) serve as the country’s centralised facilitiy for the treatment, conditioning and interim storage of low- and intermediate level radioactive waste (Radwaste). All Radwaste originating in Austria is transferred to ARCS and comes from one or several sources: The former operation of a research reactor, the application of radioactive materials in medicine, R&D, industry, IAEA Laboratories at Seibersdorf, and technically enhanced natural radioactive materials, such as by-product at industrial metallurgical processes and other processes, is transferred to ARCS for treatment, conditioning and interim storage. Dependent on the waste category, the relevant treatment technology is applied. In total more then 6900 m3 of low and intermediate level radioactive solid wastes originating from Austria were treated in the period 1976 to 2000. The aim of treatment and conditioning is the safe enclosure of the Radwaste by the use of barriers to surround and isolate the waste and transform it to an insoluble form. At the same time it is important to reduce the volume of the raw waste by applying appropriate treatment technologies, in order to save space in the storage facilities and thereby achieving a cost savings.
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Warren, David L., and Paul O. Hedman. "Differential Mass and Energy Balances in the Flame Zone From a Practical Fuel Injector in a Technology Combustor." In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-112.
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This paper presents further analysis of experimental results from an Air Force program conducted by researchers at Brigham Young University (BYU) Wright-Patterson Air Force Base (WPAFB), and Pratt and Whitney Aircraft Co. (P&W) (Hedman, et al., 1994a and 1994b). These earlier investigations of the combustion of propane in a practical burner installed in a technology combustor used: 1) digitized images from video and still film photographs to document observed flame behavior as fuel equivalence ratio was varied, 2) sets of LDA data to quantify the velocity flow fields existing in the burner, 3) CARS measurements of gas temperature to determine the temperature field in the combustion zone, and to evaluate the magnitude of peak temperature, and 4) two-dimensional PLIF images of OH radical concentrations to document the instantaneous location of the flame reaction zones. This study has used the in situ velocity and temperature measurements from the earlier study, suitably interpolated, to determine local mass and energy balances on differential volume elements throughout the flame zone. The differential mass balance was generally within about ± 10% with some notable exceptions near regions of very high shear and mixing. The local differential energy balance has qualitatively identified the regions of the flame where the major heat release is occurring, and has provided quantitative values on the rate of energy release (up to −400 kJ/m3s). The velocity field data have also been used to determine Lagrangian pathlines through the flame zone. The local velocity and temperature along selected pathlines have allowed temperature timelines to be determined. The temperature generally achieves its peak value, often near the adiabatic flame temperature, within about 10 ms. These temperature timelines, along with the quantitative heat release data may provide a basis for evaluating kinetic combustion models.
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Kelsall, G. J., M. A. Smith, and M. F. Cannon. "Low Emissions Combustor Development for an Industrial Gas Turbine to Utilise LCV Fuel Gas." In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-413.
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Advanced coal based power generation systems such as the British Coal Topping Cycle offer the potential for high efficiency electricity generation with minimum environmental impact. An important component of the Topping Cycle programme is the gas turbine, for which development of a combustion system to burn low calorific value coal derived fuel gas, at a turbine inlet temperature of 1260°C (2300 F), with minimum pollutant emissions, is a key R&D issue. A phased combustor development programme is underway burning low calorific value fuel gas (3.6–4.1 MJ/m3) with low emissions, particularly NOx derived from fuel bound nitrogen. The first phase of the combustor development programme has now been completed using a generic tubo-annular, prototype combustor design. Tests were carried out at combustor loading and mach numbers considerably greater than the initial design values. Combustor performance at these conditions was encouraging. The second phase of the programme is currently in progress. This will assess, initially, an improved variant of the prototype combustor operating at conditions selected to represent a particular medium sized industrial gas turbine. This combustor will also be capable of operating using natural gas as an auxiliary fuel, to suit the start-up procedure for the Topping Cycle. The paper presents the Phase 1 test programme results for the prototype combustor. Design of the modified combustor for Phase 2 of the development programme is discussed, together with preliminary combustion performance results.
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Schreyer, Donald, Arnold Manaker, and Scot Pritchard. "Implementation of SCR Systems for Three Boilers at the TVA Paradise Fossil Site." In 2002 International Joint Power Generation Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ijpgc2002-26084.
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In 1998, TVA undertook the implementation of Selective Catalytic Reduction systems at the Paradise Generating Station. The station has three fossil-fired cyclone boilers totaling 2515 Mw of power generation which have been online since the early 1960s for Paradise Units 1 and 2, and since 1970 for Unit 3. Design efforts started late 1998 with Paradise Unit 2, a 704 Mw cyclone-fired unit that went into operation for the May 2000 ozone season. This was followed by Paradise Unit 1, an identical 704 Mw unit that went into operation for the May 2001 ozone season. Paradise Unit 3, an 1107 Mw unit, is currently in manufacture and erection for placement into service for the 2003 ozone season. The Paradise Units 1 & 2 SCR modules are among the largest single modules in service for treating the entire flue gas path. The system design considered the operation of the boiler without overfire air NOx control, where the emission of NOx would be 688.5 g/GJ (1.6 lb/MMBtu) and with overfire air NOx emission of 370 g/GJ (0.86 lb/MMBtu). Paradise Units 1 & 2 are fitted with scrubbers and burn a high sulfur fuel. Paradise 3, not currently fitted with a scrubber, fires a blend of PRB and Utah bituminous coal. The SCR is configured with two modules. The SCR project guarantees are 90% NOx reduction, 2-ppm ammonia slip and a catalyst life of 20,000 hours. Each of the cyclone units retained their tubular air heaters. Each unit required the erection of either temporary or new ductwork from the air heater to the downstream equipment to allow the demolition of equipment that had been part of the gas path but is no longer in service. The old equipment had to be removed to permit the building of the SCRs. Each SCR unit is equipped with a full flow bypass and man-safe dampers. These man-safe dampers permitted the construction and maintenance of the SCR while the boiler was in operation. Paradise Unit 2’s SCR was fitted with steam soot blowers. Sonic horns were tested on a section of Unit 2 and based on the results, Paradise Unit 1 was fitted only with sonic horns for catalyst cleaning. The anhydrous ammonia unloading and storage facility is more than a mile from the ammonia vaporizers that are located at grade adjacent to their respective SCR unit. The monthly ammonia consumption under full power conditions for Paradise Units 1 & 2 and 90% NOx reduction is 1,703.3 m3 (450,000 gallons) per month with the overfire air system in service. This paper addresses the issues and decisions related to integration of the SCR systems and the experiences of manufacturing and erecting each of the SCR units.
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Woerner, Joerg, Sonja Margraf, and Walter Hackel. "Remediation of a Uranium-Contamination in Ground Water." In The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7270.
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The former production site of NUKEM where nuclear fuel-elements were developed and handled from 1958 to 1988 was situated in the centre of an industrial park for various activities of the chemical and metallurgical industry. The size of the industrially used part is about 300.000m2. Regulatory routine controls showed elevated CHC (Chlorinated Hydro-Carbons) values of the ground water at the beginning of the 1990’s in an area which represented about 80.000 m2 down-gradient of locations where CHC compounds were stored and handled. Further investigations until 1998 proved that former activities on the NUKEM site, like the UF6 conversion process, were of certain relevance. The fact that several measured values were above the threshold values made the remediation of the ground water mandatory. This was addressed in the permission given by the Ministry for Nuclear Installations and Environment of Hesse according to §7 of the German atomic law in October 2000 [1]. Ground water samples taken in an area of about 5.000 m2 showed elevated values of total Uranium activity up to between 50 and 75 Bq/l in 2002. Furthermore in an area of another 20.000m2 the samples were above threshold value. In this paper results of the remediation are presented. The actual alpha-activities of the ground waters of the remediation wells show values of 3 to 9Bq/l which are dominated by 80 to 90% U-234 activity. The mass-share of total Uranium for this nuclide amounts to 0,05% on average. The authority responsible for conventional water utilisation defined target values for remediation: 20μg/l for dissolved Uranium and 10μg/l for CHC [2]. Both values have not yet been reached for an area of about 10.000 m2. The remediation process by extracting water from four remediation wells has proved its efficiency by reduction of the starting concentrations by a factor of 3 to 6. Further pumping will be necessary especially in that area of the site where the contaminations were found later during soil remediation activities. Only two wells have been in operation since July 2002 when the remediation technique was installed and an apparatus for direct gamma-spectroscopic measurement of the accumulated activities on the adsorbers was qualified. Two further remediation wells have been in operation since August 2006, when the installed remediation technique was about to be doubled from a throughput of 5 m3/h to 10 m3/h. About 20.000 m3 of ground water have been extracted since from these two wells and the decrease of their Uranium-concentrations behaves similar to that of the two other wells being extracted since the beginning of remediation. Both, total Uranium-concentrations and the weight-share of the nuclides U-234, U-235 and U-238 are measured by ICP-MS (Inductively Coupled Plasma – Mass Spectrometry) besides measurements of Uranium-Alpha-Activities in addition to the measurement of CHC components of which PCE (Perchlor-Ethene) is dominant in the contaminated area. CHC compounds are measured by GC (Gas Chromatography). Down-gradient naturally attenuated products are detected in various compositions. Overall 183.000m3 of ground water have been extracted. Using a pump & treat method 11 kg Uranium have been collected on an ion-exchange material based on cellulose, containing almost 100 MBq U-235 activity, and almost 15 kg of CHC, essentially PCE, were collected on GAC (Granules of Activated Carbon). Less than 3% of the extracted Uranium have passed the adsorber-system of the remediation plant and were adsorbed by the sewage sludge of the industrial site’s waste water treatment. The monthly monitoring of 19 monitoring wells shows that an efficient artificial barrier was built up by the water extraction. The Uranium contamination of two ground water plumes has drastically been reduced by the used technique dependent on the amounts of extracted water. The concentration of the CHC contamination has changed depending on the location of temporal pumping. Thereby maximum availability of this contaminant for the remediation process is ensured. If locations with unchanged water quality are detected electrochemical parameters of the water or hydro-geologic data of the aquifer have to be taken into further consideration to improve the process of remediation.
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Michelbacher, John A., Carl E. Baily, Daniel K. Baird, S. Paul Henslee, Collin J. Knight, and Kenneth E. Rosenberg. "Shutdown and Closure of the Experimental Breeder Reactor–II." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22462.
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The Department of Energy mandated the termination of the Integral Fast Reactor (IFR) Program, effective October 1, 1994. To comply with this decision, Argonne National Laboratory-West (ANL-W) prepared a plan providing detailed requirements to maintain the Experimental Breeder Reactor-II (EBR-II) in a radiologically and industrially safe condition, including removal of all irradiated fuel assemblies from the reactor plant, and removal and stabilization of the primary and secondary sodium, a liquid metal used to transfer heat within the reactor plant. The EBR-II is a pool-type reactor. The primary system contained approximately 325 m3 (86,000 gallons) of sodium and the secondary system contained 50 m3 (13,000 gallons). In order to properly dispose of the sodium in compliance with the Resource Conservation and Recovery Act (RCRA), a facility was built to react the sodium to a solid sodium hydroxide monolith for burial as a low level waste in a land disposal facility. Deactivation of a liquid metal fast breeder reactor (LMFBR) presents unique concerns. Residual amounts of sodium remaining in circuits and components must be passivated, inerted, or removed to preclude future concerns with sodium-air reactions that could generate potentially explosive mixtures of hydrogen and leave corrosive compounds. The passivation process being implemented utilizes a moist carbon dioxide gas that generates a passive layer of sodium carbonate/sodium bicarbonate over any quantities of residual sodium. Tests being conducted will determine the maximum depths of sodium that can be reacted using this method, defining the amount that must be dealt with later to achieve RCRA clean closure. Deactivation of the EBR-II complex is on schedule for a March, 2002, completion. Each system associated with EBR-II has an associated layup plan defining the system end state, as well as instructions for achieving the layup condition. A goal of system-by-system layup is to minimize surveillance and maintenance requirements during the interim period between deactivation and decommissioning. The plans also establish document archival of not only all the closure documents, but also the key plant documents (P&IDs, design bases, characterization data, etc.) in a convenient location to assure the appropriate knowledge base is available for decommissioning, which could occur decades in the future.
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Le Duff, Jean Alain, Bruno Tacchini, Jean Michel Stephan, Regis Tampigny, Antoine Fissolo, and Ludovic Vincent. "High Cycle Thermal Fatigue Issues in RHRS Mixing Tees and Thermal Fatigue Test on a Representative 304 L Mixing Zone." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57951.
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In May 1998, a leak (30 m3 / h) occurred in the reactor heat removal system (RHRS) of the CIVAUX 1 power plant (PWR type N4 – 1400 MWe) which was then in a hot shutdown situation. A 180 mm through-wall crack was found in a 304 L austenitic stainless steel elbow in a mixing area of high and low temperature fluids [1, 2]. All mixing zones of main (␀10″) and minimum flow lines (␀4″) of the four N4 plants were affected by cracking [3]. After metallurgical examinations of these austenitic stainless steel components and an analytical damage evaluation, the major root cause for cracking was identified as high cycle thermal fatigue. The cracks were found in the mixing tees and at the roots of welds in mixing areas. The presence of ground surface finishes and geometrical discontinuities (weld roots and tapers) were identified as amplifier of fatigue damage. For the new RHRS mixing zones of N4 plants, decision was taken to suppress welds or locate them away from mixing area and to improve the surface condition (remove the weld root singularity, remove striations due to machining by polishing and reduce residual stresses). For the other 54 French PWRs (900 & 1300 MWe) with different design of RHRS mixing zones, the inspections showed that they were also all damaged by thermal fatigue with generally small cracks less than 3 mm excepted for the PWRs of Saint Alban 2 (5 mm) [4]. To reproduce the thermal fatigue phenomenon occurring in mixing zones, a representative endurance thermal fatigue test named “FATHER” was performed by CEA under an EDF, CEA and AREVA NP agreement [5, 6]. The test lasted 300 hours. It was performed on a 304L stainless steel mixing zone of 7 mm thick and 6″ diameter with a temperature difference of 160°C between cold and hot fluids. Different internal surface finishes were introduced in the test mock-up: coarse and fine grinding, industrial polishing, as extruded surfaces and as welded or flushed joints. Numerous NDE were performed during and after the endurance fatigue test like ultrasonic examinations or dye liquid penetrant inspections. They lead to the observation of many small thermal fatigue cracks located near as welded joints, on ground surfaces and on unpolished flushed welds. Cracks were not observed on industrially polished surfaces reproduced in straight piping sections or in flushed plus polished welds. After the test of 300 hours, the mock-up was axially cut in two symmetric half parts and sampling plates containing thermal fatigue cracks were machined from each of the half mock-up to perform detailed metallographic examinations. More than 50 thermal fatigue cracks with depths of 100 to 1000 μm were observed. Cracks initiate mainly on geometrical discontinuities like weld toes or grinding striations. Test results have also allowed to improve and to validate methods and tools for predicting crack initiation in mixing zones. The “FATHER” experiment can be seen as a significant contribution for preventing the risk of HCF in PWR equipment.