Academic literature on the topic 'Nuclear run-off analysis; Termination'
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Journal articles on the topic "Nuclear run-off analysis; Termination"
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Kerppola, T. K., and C. M. Kane. "Intrinsic sites of transcription termination and pausing in the c-myc gene." Molecular and Cellular Biology 8, no. 10 (October 1988): 4389–94. http://dx.doi.org/10.1128/mcb.8.10.4389.
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We have studied transcription elongation and termination in the human c-myc gene. Transcription of c-myc gene sequences with purified mammalian RNA polymerase II revealed several sites of transcription termination and pausing in the vicinity of the exon 1-intron 1 junction. This region previously has been shown to block transcription elongation in vivo by nuclear run-on analysis (D. Bentley and M. Groudine, Nature [London] 321:702-706, 1986). These sites were recognized by purified RNA polymerase II, and we therefore designated them intrinsic sites of termination and pausing. Two of these sites cause termination of RNA polymerase III transcription as well. RNA polymerase II terminated transcription in a cluster of seven consecutive T residues in the nontranscribed strand and paused during transcription at three additional sites in this region. The intrinsic sites of transcription termination and pausing described here correspond closely to the 3' ends of transcripts synthesized in Xenopus oocytes injected with plasmids containing the c-myc termination region (D. Bentley and M. Groudine, Cell 53:245-256, 1988). This correspondence suggests that the intrinsic recognition of these termination and pause sites by purified RNA polymerase II may play a role in the transcription elongation block observed in vivo.
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Kerppola, T. K., and C. M. Kane. "Intrinsic sites of transcription termination and pausing in the c-myc gene." Molecular and Cellular Biology 8, no. 10 (October 1988): 4389–94. http://dx.doi.org/10.1128/mcb.8.10.4389-4394.1988.
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We have studied transcription elongation and termination in the human c-myc gene. Transcription of c-myc gene sequences with purified mammalian RNA polymerase II revealed several sites of transcription termination and pausing in the vicinity of the exon 1-intron 1 junction. This region previously has been shown to block transcription elongation in vivo by nuclear run-on analysis (D. Bentley and M. Groudine, Nature [London] 321:702-706, 1986). These sites were recognized by purified RNA polymerase II, and we therefore designated them intrinsic sites of termination and pausing. Two of these sites cause termination of RNA polymerase III transcription as well. RNA polymerase II terminated transcription in a cluster of seven consecutive T residues in the nontranscribed strand and paused during transcription at three additional sites in this region. The intrinsic sites of transcription termination and pausing described here correspond closely to the 3' ends of transcripts synthesized in Xenopus oocytes injected with plasmids containing the c-myc termination region (D. Bentley and M. Groudine, Cell 53:245-256, 1988). This correspondence suggests that the intrinsic recognition of these termination and pause sites by purified RNA polymerase II may play a role in the transcription elongation block observed in vivo.
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Birkenheuer, Claire H., Charles G. Danko, and Joel D. Baines. "Herpes Simplex Virus 1 Dramatically Alters Loading and Positioning of RNA Polymerase II on Host Genes Early in Infection." Journal of Virology 92, no. 8 (February 7, 2018): e02184-17. http://dx.doi.org/10.1128/jvi.02184-17.
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ABSTRACTHerpes simplex virus 1 (HSV-1) transcription is mediated by cellular RNA polymerase II (Pol II). Recent studies investigating how Pol II transcription of host genes is altered after HSV-1 are conflicting. Chromatin immunoprecipitation sequencing (ChIP-seq) studies suggest that Pol II is almost completely removed from host genes at 4 h postinfection (hpi), while 4-thiouridine (4SU) labeling experiments show that host transcription termination is extended at 7 hpi, implying that a significant amount of Pol II remains associated with host genes in infected cells. To address this discrepancy, we used precision nuclear run-on analysis (PRO-seq) to determine the location of Pol II to single-base-pair resolution in combination with quantitative reverse transcription-PCR (qRT-PCR) analysis at 3 hpi. HSV-1 decreased Pol II on approximately two-thirds of cellular genes but increased Pol II on others. For more than 85% of genes for which transcriptional termination could be statistically assessed, Pol II was displaced to positions downstream of the normal termination zone, suggesting extensive termination defects. Pol II amounts at the promoter, promoter-proximal pause site, and gene body were also modulated in a gene-specific manner. qRT-PCR of selected RNAs showed that HSV-1-induced extension of the termination zone strongly correlated with decreased RNA and mRNA accumulation. However, HSV-1-induced increases of Pol II occupancy on genes without termination zone extension correlated with increased cytoplasmic mRNA. Functional grouping of genes with increased Pol II occupancy suggested an upregulation of exosome secretion and downregulation of apoptosis, both of which are potentially beneficial to virus production.IMPORTANCEThis study provides a map of RNA polymerase II location on host genes after infection with HSV-1 with greater detail than previous ChIP-seq studies and rectifies discrepancies between ChIP-seq data and 4SU labeling experiments with HSV-1. The data show the effects that a given change in RNA Pol II location on host genes has on the abundance of different RNA types, including nuclear, polyadenylated mRNA and cytoplasmic, polyadenylated mRNA. It gives a clearer understanding of how HSV-1 augments host transcription of some genes to provide an environment favorable to HSV-1 replication.
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Miller, H., C. Asselin, D. Dufort, J. Q. Yang, K. Gupta, K. B. Marcu, and A. Nepveu. "A cis-acting element in the promoter region of the murine c-myc gene is necessary for transcriptional block." Molecular and Cellular Biology 9, no. 12 (December 1989): 5340–49. http://dx.doi.org/10.1128/mcb.9.12.5340.
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A block to elongation of transcription has been shown to occur within the first exon of the human and murine c-myc genes. The extent of this block was found to vary with the physiological state of cells, indicating that modulation of the transcriptional block can serve to control the expression of this gene. To determine which sequences are required in cis for the transcriptional block, we generated a series of constructs containing various portions of murine c-myc 5'-flanking and exon 1 sequences. We established populations of HeLa and CV-1 cells stably transfected with these constructs. The transcription start sites were determined by S1 nuclease mapping analysis, and the extent of transcriptional block was measured by nuclear run-on transcription assays. Our results demonstrate that at least two cis-acting elements are necessary for the transcriptional block. A 3' element was found to be located in the region where transcription stopped and showed features reminiscent of some termination sites found in procaryotes. A 5' element was positioned between the P1 and P2 (C. Asselin, A. Nepveu, and K. B. Marcu, Oncogene 4:549-558, 1989). Removal of the more 3' binding site abolished the transcriptional block.
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Miller, H., C. Asselin, D. Dufort, J. Q. Yang, K. Gupta, K. B. Marcu, and A. Nepveu. "A cis-acting element in the promoter region of the murine c-myc gene is necessary for transcriptional block." Molecular and Cellular Biology 9, no. 12 (December 1989): 5340–49. http://dx.doi.org/10.1128/mcb.9.12.5340-5349.1989.
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A block to elongation of transcription has been shown to occur within the first exon of the human and murine c-myc genes. The extent of this block was found to vary with the physiological state of cells, indicating that modulation of the transcriptional block can serve to control the expression of this gene. To determine which sequences are required in cis for the transcriptional block, we generated a series of constructs containing various portions of murine c-myc 5'-flanking and exon 1 sequences. We established populations of HeLa and CV-1 cells stably transfected with these constructs. The transcription start sites were determined by S1 nuclease mapping analysis, and the extent of transcriptional block was measured by nuclear run-on transcription assays. Our results demonstrate that at least two cis-acting elements are necessary for the transcriptional block. A 3' element was found to be located in the region where transcription stopped and showed features reminiscent of some termination sites found in procaryotes. A 5' element was positioned between the P1 and P2 (C. Asselin, A. Nepveu, and K. B. Marcu, Oncogene 4:549-558, 1989). Removal of the more 3' binding site abolished the transcriptional block.
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Napp, Adriane E., Torsten Diekhoff, Olf Stoiber, Judith Enders, Gerd Diederichs, Peter Martus, and Marc Dewey. "Audio-guided self-hypnosis for reduction of claustrophobia during MR imaging: results of an observational 2-group study." European Radiology 31, no. 7 (April 15, 2021): 4483–91. http://dx.doi.org/10.1007/s00330-021-07887-w.
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Abstract Objectives To evaluate the influence of audio-guided self-hypnosis on claustrophobia in a high-risk cohort undergoing magnetic resonance (MR) imaging. Methods In this prospective observational 2-group study, 55 patients (69% female, mean age 53.6 ± 13.9) used self-hypnosis directly before imaging. Claustrophobia included premature termination, sedation, and coping actions. The claustrophobia questionnaire (CLQ) was completed before self-hypnosis and after MR imaging. Results were compared to a control cohort of 89 patients examined on the same open MR scanner using logistic regression for multivariate analysis. Furthermore, patients were asked about their preferences for future imaging. Results There was significantly fewer claustrophobia in the self-hypnosis group (16%; 9/55), compared with the control group (43%; 38/89; odds ratio .14; p = .001). Self-hypnosis patients also needed less sedation (2% vs 16%; 1/55 vs 14/89; odds ratio .1; p = .008) and non-sedation coping actions (13% vs 28%; 7/55 vs 25/89; odds ratio .3; p = .02). Self-hypnosis did not influence the CLQ results measured before and after MR imaging (p = .79). Self-hypnosis reduced the frequency of claustrophobia in the subgroup of patients above an established CLQ cut-off of .33 from 47% (37/78) to 18% (9/49; p = .002). In the subgroup below the CLQ cut-off of 0.33, there were no significant differences (0% vs 9%, 0/6 vs 1/11; p = 1.0). Most patients (67%; 35/52) preferred self-hypnosis for future MR examinations. Conclusions Self-hypnosis reduced claustrophobia in high-risk patients undergoing imaging in an open MR scanner and might reduce the need for sedation and non-sedation coping actions. Key Points • Forty percent of the patients at high risk for claustrophobia may also experience a claustrophobic event in an open MR scanner. • Self-hypnosis while listening to an audio in the waiting room before the examination may reduce claustrophobic events in over 50% of patients with high risk for claustrophobia. • Self-hypnosis may also reduce the need for sedation and other time-consuming non-sedation coping actions and is preferred by high-risk patients for future examinations.
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Wu, Yanping, Jennifer H. McQuiston, Andrew Cox, Todd D. Pack, and Thomas J. Inzana. "Molecular Cloning and Mutagenesis of a DNA Locus Involved in Lipooligosaccharide Biosynthesis in Haemophilus somnus." Infection and Immunity 68, no. 1 (January 1, 2000): 310–19. http://dx.doi.org/10.1128/iai.68.1.310-319.2000.
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ABSTRACT Haemophilus somnus undergoes antigenic and structural phase variation in its lipooligosaccharide (LOS). A gene (lob-1) containing repetitive 5′-CAAT-3′ sequences that may, in part, contribute to phase variation was cloned and sequenced (T. J. Inzana et al., Infect. Immun. 65:4675–4681, 1997). We have now identified another putative gene (lob-2A) immediately upstream from lob-1. Lob-2A contained homology to several LOS biosynthesis proteins of the family Pasteurellaceae and the LgtB and LgtE galactosyltransferases of Neisseria meningitidis and N. gonorrhoeae. Unlikelob-1, lob-2A contained 18 to 20 5′-GA-3′ repeats 141 bp upstream of the termination codon as determined by PCR amplification of DNA from individual colonies. Twenty repeats were most common, but when 19 5′-GA-3′ repeats were present a stop codon would occur 1 bp after the last 5′-GA-3′ repeat. A 630-bpSalI-BsgI fragment within lob-2Awas deleted, and a kanamycin resistance (Kmr) gene was inserted into this site to create pCAATΔlob2A. Following electroporation of pCAATΔlob2A into H. somnus 738, several allelic exchange mutants were isolated. The LOS electrophoretic profile of one mutant, strain 738-lob2A1::Km, was altered, and the phase variation rate was reduced but phase variation was not eliminated. A variant with 19 5′-GA-3′ repeats in lob-2Ahad an LOS profile similar to that of 738-lob2A1::Km, suggesting that lob-2A was turned off in this phase. Nanoelectrospray mass spectrometry (nES-MS) and nuclear magnetic resonance spectroscopy showed that 738-lob2A1::Km was deficient in the terminal βGal(1-3)βGlcNAc residue present in parent strain 738. Mutant 738-lob2A1::Km was significantly more sensitive to the bactericidal action of normal bovine serum and was less virulent in mice than was parent strain 738. When H. somnus 129Pt was electrotransformed with shuttle vector pLS88 containing lob-2A, its LOS electrophoretic profile was modified and additional N-acetylhexosamine residues were present, as determined by nES-MS analysis. These results indicated thatlob-2A may be an N-acetylglucosamine transferase involved in LOS biosynthesis and phase variation and that LOS structure is important to H. somnus virulence.
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Martínez-Calvillo, Santiago, Dan Nguyen, Kenneth Stuart, and Peter J. Myler. "Transcription Initiation and Termination on Leishmania major Chromosome 3." Eukaryotic Cell 3, no. 2 (April 2004): 506–17. http://dx.doi.org/10.1128/ec.3.2.506-517.2004.
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ABSTRACT Genome projects involving Leishmania and other trypanosomatids have revealed that most genes in these organisms are organized into large clusters of genes on the same DNA strand. We have previously shown that transcription of the entire Leishmania major Friedlin (LmjF) chromosome 1 (chr1) initiates bidirectionally between two divergent gene clusters. Here, we analyze transcription of LmjF chr3, which contains two convergent clusters of 67 and 30 genes, separated by a tRNA gene, with a single divergent protein-coding gene located close to the “left” telomere. Nuclear run-on analyses indicate that specific transcription of chr3 initiates bidirectionally between the single subtelomeric gene and the adjacent 67-gene cluster, close to the “right” telomere upstream of the 30-gene cluster, and upstream of the tRNA gene. Transcription on both strands terminates within the tRNA-gene region. Transient-transfection studies support the role of the tRNA-gene region as a transcription terminator for RNA polymerase II (Pol II) and Pol III, and also for Pol I.
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Shiota, Chiyo, Kazuhiro Ikenaka, and Katsuhiko Mikoshiba. "Developmental Expression of Myelin Protein Genes in Dysmyelinating Mutant Mice: Analysis by Nuclear Run-Off Transcription Assay, In Situ Hybridization, and Immunohistochemistry." Journal of Neurochemistry 56, no. 3 (March 1991): 818–26. http://dx.doi.org/10.1111/j.1471-4159.1991.tb01997.x.
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Falk, G., and J. E. Walker. "Transcription of Rhodospirillum rubrum atp operon." Biochemical Journal 229, no. 3 (August 1, 1985): 663–68. http://dx.doi.org/10.1042/bj2290663.
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The photosynthetic non-sulphur bacterium Rhodospirillum rubrum contains a cluster of five genes encoding the subunits of F1-ATPase [Falk, Hampe & Walker (1985) Biochem. J. 228, 391-407]. Transcription of these genes has been studied by two methods, transcriptional mapping with S1 nuclease and primer extension analysis. Thereby a 5'-end in RNA derived from this region has been demonstrated at a guanine residue 236 bases before the initiation codon of the gene for the delta-subunit, the first in this cluster. DNA sequences on the 5' side of this nucleotide show some similarity to promoters in Escherichia coli, but are not apparently related to sequences upstream of the Rhodopseudomonas blastica atp operon. A 3'-end in RNA derived from this gene cluster has been demonstrated by S1-nuclease mapping. This is found before a run of thymidylate residues in the DNA, on the 3' side of a region of dyad symmetry. In E. coli these features are characteristic of rho-independent transcriptional termination signals. It appears from these studies and from the organization of the genes that the five genes in the atp cluster may be co-transcribed from this promoter and that transcripts terminate at the region of dyad symmetry.
Dissertations / Theses on the topic "Nuclear run-off analysis; Termination"
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White, Hilary Louise. "Transcription in the human #beta# globin locus." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337833.
Full textBook chapters on the topic "Nuclear run-off analysis; Termination"
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George, Laurent, and Pierre Courbin. "Reconfiguration of Uniprocessor Sporadic Real-Time Systems." In Reconfigurable Embedded Control Systems, 167–89. IGI Global, 2011. http://dx.doi.org/10.4018/978-1-60960-086-0.ch007.
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In this chapter the authors focus on the problem of reconfiguring embedded real-time systems. Such reconfiguration can be decided either off-line to determine if a given application can be run on a different platform, while preserving the timeliness constraints imposed by the application, or on-line, where a reconfiguration should be done to adapt the system to the context of execution or to handle hardware or software faults. The task model considered in this chapter is the classical sporadic task model defined by a Worst Case Execution Time (WCET), a minimum inter-arrival time (also denoted the minimum Period) and a late termination deadline. The authors consider two preemptive scheduling strategies: Fixed Priority highest priority first (FP) and Earliest Deadline First (EDF). They propose a sensitivity analysis to handle reconfiguration issues. Sensitivity analysis aims at determining acceptable deviations from the specifications of a problem due to evolutions in system characteristics (reconfiguration or performance tuning). They present a state of the art for sensitivity analysis in the case of WCETs, Periods and Deadlines reconfigurations and study to what extent sensitivity analysis can be used to decide on the possibility of reconfiguring a system.
Conference papers on the topic "Nuclear run-off analysis; Termination"
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Leung, W. H. "On the MEGAPIE Target Thermal Hydraulics: A RELAP5 Analysis." In 12th International Conference on Nuclear Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/icone12-49378.
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A new type of liquid-metal target is designed for the Spallation Neutron Source in PSI. LBE is selected to be the target material and the primary coolant as well. RELAP5/MOD 3.2 is used to analyze the system thermal hydraulics. The nominal conditions are chosen based on temperature constraints from the design assessments. The steady state results are in the proximity of the design specifications and the heat removal capacity is adequately deployed. The normal thermal hydraulic transients, namely the proton beam and beam interrupt, are studied. A basic PID (Proportional, Integral, Derivative) control is implemented in the RELAP5 for regulating the target temperature. It is found that the control chain works very well for the beam trip in limiting the temperature fluctuations. In a beam interrupt, the proton beam is completely turned off without recovering. The transition from full power to hot-standby is quite smooth, but it becomes oscillatory in the long run due to the timelags in the cooling loops’ responses. An off normal case of target main coolant trip has also been studied. Without the main pump, the target can still be operated in the natural circulation mode, and the control can cope with the normal beam transients and restarting the target from hot standby.
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Duan, Tianying, Peide Zhou, Bin Long, Yun Hu, Yizhe Liu, Chen Huang, Huajin Yu, et al. "Preliminary Research and Design in the Nuclear Island Systems of 1500MWt Standing-Wave Reactor." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16134.
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As one kind of fast reactor, the Traveling-Wave Reactor (TWR) utilizes depleted uranium with a small amount of enriched uranium/ plutonium which is used to kick off the chain reaction. The TWR can run for decades without refueling or removing any used fuel from the reactor. The most challenging issues on TWR are fuel design, structural material for fuel cladding, core physics process analysis and core physics design. Based on the present technology of fuel and structural material, a new concept named Standing-Wave Reactor (SWR) which is the preliminary stage of the TWR is proposed. The wave of fission would move through the depleted uranium core by fuel transfer in SWR. According to the concept of SWR and the published data of fuel and material, the R&D works on 1500MWt SWR have been performed, which cover the reactor core, reactor structure, process system et.al. The preliminary results confirm the feasibility of SWR. Meanwhile, the design of reactor core and the main systems which is based on the technologies of available pool sodium-cooled fast reactor has been accomplished.
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Colón Rodríguez, José, Nor Farida Harun, Nana Zhou, Edward Sabolsky, and David Tucker. "System Analysis of a 100kW Internal Combustion Engine (ICE) Solid Oxide Fuel Cell (SOFC) Hybrid Configuration." In ASME 2020 Power Conference collocated with the 2020 International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/power2020-16620.
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Abstract Due to the intermittent nature of the renewable power plants and the rigid operation of existing plans, the need for flexible power production is eminent. Hybrid energy systems have shown potential for flexible power production capable to fulfill the power demands and maintain the efficiency. This work studies different design cases of a 100kW Internal Combustion Engine (ICE) and Solid Oxide Fuel Cell (SOFC) hybrid system. Anode off-gas from the fuel cell stack provided the chemical energy to run the ICE. Heat management of the anode exhaust was considered to attain the operational limits of the ICE in the present configuration. A turbocharger was used to deliver the necessary air flow for both the fuel cell stack and the engine. A series of 25 design cases were chosen to analyze the performance and the potential flexibility of this cycle. The 25-design points resulted from a matrix composed of the variation of fuel utilization and reformer operating temperature, ranging from 70% to 90% and 600K to 1000K, respectively. At each design point, hardware was re-sized to match the desired conditions. The cycle performance and fuel cell distributed profiles are discussed in this paper. It is discovered that the system efficiency increases as the fuel utilization increases following a nearly linear behavior. The highest efficiency attained is 62% at a reformer operating temperature of 800K and a 90% fuel utilization. The minimum external fuel required to maintain turbocharger in operation decreases with the increase on the reformer temperature. Power contribution between ICE and SOFC follows a linear behavior closely overlapping each trend at different reforming operational temperatures. The impact of external reforming and internal on-anode reforming is also discussed. It is found that there is an optimal balance between the external and internal reforming. The optimal methane content in this work is shown to be around ∼18 vol%.
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Yamamoto, Shinji, and Toshiro Kitamura. "Best Practices in Japan of Human Resource Development for NPP O&M: Roles and Lessons From Training Centers." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48137.
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The use of best practices and their lateral expansion as a benchmark is one of effective methods of “knowledge management (NK)”. Best practices of human resources development were collected (selected examples are listed below) from all 11 training centers annexed to the nuclear power plants in Japan and lessons were learned for possible lateral development for improving other stakeholders’ NK. Such best practices will provide productive information for designing their own human resources development strategies. Examples of collected good practices: • Exhibition of troubles and negative legacies: The actual machineries, equipment or components, explanatory documents or news articles of the past troubles experienced by themselves are effective to maintain and refresh the awareness and preparedness of trainees and other employees for recurrence prevention. The exhibitions are open to the visitors, too. • Experience-type training facilities: Off-normal conditions of components and systems are simulated for the staff practical training by the use of the facilities which provide an off-normal environment. Examples are: water hammers, abnormal vibrations and noises of rotating machineries, pump cavitations, pinholes, plumbing airs, etc. • Advanced simulators for operators training: Each electric company has its own simulators for training their own operating staff. These simulators are annexed to the nuclear power plants and used to train the operation staff by the experienced shift managers. The operation staff use the simulator for continually confirming the operation procedures and the plant behavior, etc. specific to their plants. Training for generic plant behavior and operators’ responses are mainly outsourced to the dedicated training centers run by the Owners’ Groups (BWR, PWR). • The SAT methods: The IAEA proposed SAT (Systematic Approach to Training) approach is applied to the training of the operating staff and the maintenance staff. It is structured in a flow of Job analysis ← Training program design ← Training material development ← Training ← Evaluation. • Training in real situations: An example is a trainee actually hung with a lifeline on a harness to learn a method of putting on the lifeline. On the other hand, the efficiency (availability) of the training facilities for maintenance work is very limited, because each electric company installs the training facilities individually. Experiences of ICONE-16 participants from other countries in improving the availability are of our interest.
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Hawila, Mohammad A., and Karen Vierow Kirkland. "RCIC Turbo-Pump Scaling Through CFD and Model Testing for the Texas A&M University NHTS Facility." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81119.
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One of the requirements for licensing a nuclear power plant in the U.S is the capability to survive and recover from a station blackout according to the U.S Nuclear Regulatory Commission (USNRC). Station blackout is the loss of all off-site and onsite power simultaneously. Therefore, experimental test facilities are being constructed and operated to test the performance of the related safety systems in a nuclear power plant. Design and construction of a test facility creates the need to perform scaling analysis to ensure proper representation of key components and phenomena of interest. One of the main outcomes of the scaling analysis is the quantitative estimation of the Similarity Level (SL), which requires derivation of dimensionless scaling parameters and prediction of appropriate input values for the scaling parameters. To study the performance of the Reactor Core Isolation Cooling (RCIC) system, the Nuclear Heat Transfer Systems (NHTS) Laboratory at Texas A&M University has constructed and is operating a RCIC test facility. This paper presents the scaling analysis with reference to a full-size RCIC system and the RCIC system turbine was used as the main component for scaling. The input parameters for dimensionless scaling parameters were obtained through experimental measurements and CFD analysis. The CFD analysis is for the ZS-1 RCIC system turbine model. The STAR-CCM+ CFD code was used in this study to create and run simulations for steady state normal and abnormal operating conditions for the NHTS-developed CAD models. The input for the dimensionless scaling parameters was estimated. Input parameters were collected both experimentally and from CFD simulations and inserted into these equations. As a result, a high degree of similarity was confirmed, with a minimum of 82% between the NHTS and full-size RCIC systems. The 82% represents the amount of transfer properties conserved between the two systems. Consequently, this high similarity level allows the NHTS RCIC system to be used to study the behavior of the full-size RCIC system under Beyond Design Bases Accident (BDBA) conditions. Future work is to study and model other components of the RCIC system such as the suppression chamber to estimate similarity levels and study their effects on behavior of the system under BDBA.
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Virgen, Matthew Miguel, and Fletcher Miller. "Analysis of a Combined Cycle Plant Using a Small Particle Receiver to Drive a Primary Brayton Cycle." In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49317.
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All current commercial CSP plants operate at relatively low thermodynamic efficiency due to lower temperatures than similar conventional plants and due to the fact that they all employ Rankine conversion cycles. We present here an investigation on the effects of adding a bottoming steam power cycle to a hybrid CSP plant based on a Small Particle Heat Exchange Receiver (SPHER) driving a gas turbine as the primary cycle. Due to the high operating temperature of the SPHER being considered (over 1000 Celsius), the exhaust air from the primary Brayton cycle still contains a tremendous amount of exergy. While in the previous analysis this fluid was only used in a recuperator to preheat the Brayton working fluid, the current analysis explores the potential power and efficiency gains from instead directing the exhaust fluid through a heat exchanger to power a Rankine steam cycle. Not only do we expect the efficiency of this model to be competitive with conventional power plants, but the water consumption per kilowatt-hour will also be reduced by nearly two thirds as compared to most existing concentrating solar thermal power plants as a benefit of having air as the primary working fluid, which eliminates the condensation step present in Rankine-cycle systems. Coupling a new steam cycle model with the gas-turbine CSP model previously developed at SDSU, a wide range of cases were run to explore options for maximizing both power and efficiency from the proposed CSP combined cycle gas turbine (CCGT) plant. Due to the generalized nature of the bottoming cycle modeling, and the varying nature of solar power, special consideration had to be given to the behavior of the heat exchanger and Rankine cycle in off-design scenarios. The trade-offs of removing the recuperator for preheating the primary fluid are compared to potential overall power and efficiency gains in the combined cycle case.
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Cumpston, J., and John D. Pye. "Optimisation of Paraboloidal Dish Fields for Direct-Steam Generation." In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49712.
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We investigate losses and costs associated with direct steam generation via parabolidal dish concentrators and steam transport to a central steam Rankine power cycle for electricity generation. This study presents a power plant model that accounts for the effects of shading, steam transport, energy conversion at the power block, and capital costs of land and pipework. The pipe network topology used was optimised using a genetic algorithm based on evolution of minimal spanning trees connecting all dishes to a central power block. Optimal pipe sizing of the network is determined by considering the trade-off of frictional losses against thermal losses and material costs. Weather data provides input for the solar resource, and shading is calculated using an established numerical model. The plant model is used to determine the collector layout for which the effective annual revenue is maximised. Results show that the optimal rectangular layout is closely spaced in the North-south direction, along which most of the pipe links run, while East-west spacing is less important. The annual thermal performance of the optimised dish field on a per-unit-area basis is then compared to simulation of a parabolic trough employed for the same purpose. A detailed breakdown of the thermal analysis used forms the basis of comparison between the collector types, giving the overall advantage and a comparison of various sources of loss. We demonstrate that dish fields can collect approximately 49% more thermal energy annually per unit collector area than a trough system employed for the same purpose.
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Iino, Kenji, Ritsuo Yoshioka, Masao Fuchigami, and Masayuki Nakao. "What Could Have Saved Fukushima From Its Severe Accident." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65069.
Full textAbstract:
The Great East Japan Earthquake on March 11, 2011 triggered huge tsunami waves that devastated the northeast region of Japan along the Pacific coastline. The Tokyo Electric Power Company (TEPCO) owned Fukushima Daiichi Nuclear Power Plant (Fukushima-1) survived the earthquake, however, not the tsunami that followed. Four of the 6 reactor units underwent Station Blackout. Unit 5 lost all its own AC power, however, it shared AC power with Unit 6. Units 1, 3, and 4 had hydrogen explosions that destroyed their reactor buildings, and even worse, 1, 2, and 3 had core meltdowns to release a large amount of radioactive material to their surroundings. The accident was rated Level 7 on the International Nuclear Event Scale, the worst level defined by International Atomic Energy Agency (IAEA). Reports and papers have been published by a number of entities including the Japanese Diet, Government, TEPCO, IAEA, and more. They give detail explanation of how the accident developed into a nuclear disaster explaining the direct and background causes and faults made after the accident broke out. Finding the accident process, i.e., how it happened, and its causes of why it happened, are the most important first steps in accident analysis. Figuring out how to prevent similar events in the future, or even if it is possible to do so, however, is equally important for our future. We started our study in 2014 to find what actions TEPCO could have taken before the accident for preventing it from growing into a catastrophe. Then in February 2015, we set the goal of our study group to find answers to the following two questions: A. Was the huge tsunami, induced by a huge earthquake, predictable at Fukushima-1? B. If it was predictable, what preparations at Fukushima-1 could have reduced the severity of the accident? In response to our invitation to experts in the nuclear field, active and retired people gathered from academia, manufacturers, utility companies, and even regulators. After a series of tense discussions, we reached the conclusions that: Aa. Tsunami of the level that hit Fukushima-1 in 2011 was well predictable, and, Ba. The accident would have been much less severe if the plant had prepared a set of equipment, and most of all, had exercised actions against such tsunami. Preparation at the plant to prevent the severe accident consisted of the following items 1 through 7, and drills in 8: 1. A number of 125Vdc and 250Vdc batteries, 2. Portable underwater pumps, 3. Portable AC generators with sufficient gasoline supply to run the pumps, and 4. High voltage AC power truck This set applied only to this specific accident. For preparing against many other situations that could have taken place at Fukushima-1, we recommend having, in addition, the following equipment and modifications. 5. Portable compressor to drive air-operated valves for venting, 6. Watertight modification to RCIC and HPCI control and instrumentation, 7. Fire engines for alternate low pressure water injection after vent (Fukushima-1 had three). Just making these preparations would not have been sufficient. Activating valves with DC batteries, for example, takes disengaging the regular power supply lines and hooking up the batteries. 8. Drills against extended loss of all electric power and seawater pump This item 8, on and off-site drills was the most important preparation that should had been made. All other necessary preparations to save the plant in such cases would have followed logically.