The Organisation for Economic Co-operation and Development (OECD)/Nuclear Energy Agency (NEA) Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF), which started in ...2012 and continued until 2018, was one of the earliest responses to the accident at Fukushima Daiichi. The project, divided into two phases, addressed the investigation of the accident at Units 1, 2, and 3 by severe accident (SA) codes until 500 h, focusing on thermal hydraulics, core relocation, molten corium concrete interaction (MCCI), and fission product release and transport. The objectives of the BSAF were to make up plausible scenarios based primarily on SA forensic analysis, support the decommissioning, and inform SA code modeling. The analysis and comparison among the institutes have brought up vital insights regarding the accident progression, identifying periods of core meltdown and relocation and reactor pressure vessel (RPV) and primary containment vessel (PCV) leakage/failure through the comparison of pressure, water level, and containment atmosphere monitoring system (CAMS) signatures. The combination of code results and inspections (muon radiography, PCV inspection) has provided a picture of the current status of the debris distribution and plant status. All units present a large relocation of core materials and all of them present ex-vessel debris with Unit 1 and Unit 3 showing evidence of undergoing MCCI. Uncertainties have been identified, in particular on the time and magnitude of events such as corium relocation in the RPV and into the cavity floor and RPV and PCV rupture events. Main uncertainties resulting from the project are the large and continuous MCCI progression predicted by basically all the SA codes and the leak pathways from the RPV to the PCV and the PCV to the reactor building and environment. The BSAF project represents a pioneering exercise that has set the basis and provided lessons learned not only for code improvement but also for the development of new related projects to investigate in detail further aspects of the Fukushima Daiichi accident.
•OECD/NEA project “Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Plant (BSAF), phase 2.•Severe accident analyses for Unit 2 of Fukushima Daiichi.•Fukushima Daiichi Unit 2 ...specific aspects will be highlighted, Unit 1 and 3 aspects are presented separately.•Special focus is on reactor pressure vessel status, melt release and fission product behavior and release.
This is the second paper in a series of 3 in which results of severe accident analyses for Unit 2 of Fukushima Daiichi are presented, gained in phase 2 of the OECD/NEA project “Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Plant (BSAF)”. Nine organizations of six countries (CNL Canada; CRIEPI, IAE, JAEA and NRA Japan; IRSN France; KAERI Korea; NRC/DOE/SNL U.S. and VTT Finland) submitted results of their calculated severe accident scenarios for Unit 2 of Fukushima Daiichi using different severe accident codes (ASTEC, MAAP, MELCOR, SAMPSON, THALES-KICHE).
The present paper describes the findings of the comparison of the participants’ results for Unit 2 against each other and against plant data, the evaluation of the accident progression and the final status inside the reactors. Special focus is on reactor pressure vessel status, melt release and fission product behavior and release. Unit 2 specific aspects will be highlighted and points of consensus as well as remaining uncertainties and data needs will be summarized.
Zoonotic strains of hepatitis E virus (HEV) in Europe have been reported to belong to genotypes 3 and 4. In 2012 and 2013, 57 pig farms in Northern Italy that had previously resulted seropositive for ...HEV were surveyed for the presence of the virus, with positive samples subsequently genotyped. Hepatitis E RNA was identified in 17/57 (29·8%) seropositive farms. Phylogenetic analysis demonstrated that distinct subtypes of genotype 3 were circulating in the north-east of Italy; as well, for the first time in the Italian swine population, genotype 4 was identified and attributed to subtype d.
Streptococcus pneumoniae is not only a commensal of the nasopharyngeal epithelium, but may also cause life-threatening diseases. Immune-electron microscopy studies revealed that the bacterial ...glycolytic enzyme, phosphoglycerate kinase (PGK), is localised on the pneumococcal surface of both capsulated and non-capsulated strains and colocalises with plasminogen. Since pneumococci may concentrate host plasminogen (PLG) together with its activators on the bacterial cell surface to facilitate the formation of plasmin, the involvement of PGK in this process was studied. Specific binding of human or murine PLG to strain-independent PGK was documented, and surface plasmon resonance analyses indicated a high affinity interaction with the kringle domains 1-4 of PLG. Crystal structure determination of pneumococcal PGK together with peptide array analysis revealed localisation of PLG-binding site in the N-terminal region and provided structural motifs for the interaction with PLG. Based on structural analysis data, a potential interaction of PGK with tissue plasminogen activator (tPA) was proposed and experimentally confirmed by binding studies, plasmin activity assays and thrombus degradation analyses.
In biology, it is easy to understand how a damaged functional system may generate wrong signals, but why this should happen when the system is disconnected is less clear. For this reason, among other ...pain syndromes, neuropathic pain (NP) following spinal cord injury (SCI) leaves most questions unanswered.
Our purpose is to review current knowledge on NP after SCI, focusing on the mechanisms, assessment and management of the syndrome.
The mechanisms responsible for NP following SCI are poorly understood: NP is classically considered a "central pain syndrome" but recent evidence from experimental models reveals a possible "peripheral sensitization". Assessment of NP following SCI is well-established: in addition to clinical evaluation and self-reported scales, many neurophysiological, radiological and microscopic investigations may be performed. The management of NP following SCI is very difficult: evidence of effective drugs is lacking and alternative new treatment approaches yield different outcomes.
Recently clinical and instrumental tools have increased our knowledge on NP, suggesting that the discovery of new treatment agents will depend on an explanation of what changes after SCI: future research must point in this direction.
► Lattice cell and core physics for actinide based fuels. ► Existing heavy water moderated reactor designs. ► Actinide fuels at high burnup to improve economics of transmutation. ► Instantaneous and ...long term core averaged core physics analysis. ► Feasibility of destroying a majority of long lived actinides in spent fuel.
The reprocessing actinide materials extracted from spent fuel for use in mixed oxide fuels is a key component in maximizing the spent fuel repository utility. While fast spectrum reactor technologies are being considered in order to close the fuel cycle, and transmute these actinides, there is potential to utilize existing pressurized heavy water reactors such as the CANDU
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CANDU is a trademark of Atomic Energy of Canada Limited.
design to meet these goals. The use of current thermal reactors as an intermediary step which can burn actinide based fuels can significantly reduce the fast reactor infrastructure needed. This paper examines the features of actinide mixed oxide fuel, TRUMOX, in a typical CANDU nuclear reactor. The actinide concentrations used were based on extraction from 30 year cooled spent fuel and mixed with natural uranium in 4.75% actinide MOX fuel. The WIMS-AECL model of the fuel lattice was created and the two neutron group properties were transferred to RFSP in order to create a 3 dimensional time average full core model. The model was created with typical CANDU limits on bundle and channel powers and a burnup target of 45
MWd/kgHE. The TRUMOX fuel design achieved its goals and performed well under normal operations simulations. This effort demonstrated the feasibility of using the current fleet of CANDU reactors as an intermediary step in burning reprocessed spent fuel and reducing actinide burdens within the end repository. The recycling, reprocessing and reuse of spent fuels produces a much more sustainable and efficient nuclear fuel cycle using existing and proven reactor technologies.
Many of the investments decisions facing with uncertainty can be characterized as real options problems. There is evidence of deviation from the predictions derived using such normative models. The ...proposed research sheds light on the importance of integrating normative models with experimental methods in order to predict and explain such cognitive limitations, in the particular context of R&D alliances. The focus is on appropriate validation of such models on experimental data. We propose a simple design starting from a real options model dealing with alliance timing decisions. We present the decision makers with risky choices formulated as abstract gambling decisions in order to assess their risk propensity and to validate the normative predictions of the model. This paper introduces the basic principles of the use of fuzzy grouping variables in economic analysis. On the survey data gathered to validate the predictive power of the presented model we show that fuzzy sets can be effectively used to partition the experimental data into fuzzy subsets for model verification (e.g. when subgroups cannot be defined in a crisp way). We compare the validation of the model on a full data set with a "refocused" validation on a fuzzy subset of the original sample.
Collaborative play, an educational tool for children on the Autism Spectrum Disorder (ASD) spectrum, has been demonstrated as having potential for increasing the engagement of children with ASD. ...Researchers in China and the USA have assessed three approaches for accessible interface design and learning by students with ASD. With the use of known tools and appropriate occupational therapy interventions, an educational protocol was designed to evaluate the two selected applications and a commercially available application. The pilot studies, including experimental design and outcomes, are presented in this paper in the context of prior ASD intervention research, correlated with child development studies, and provide a solid foundation for comparative usability assessment of mid-air finger gesture interaction as well as hand gesture interaction for the wider population of users. Early results in China are promising, based on experiences in the USA.
Discharge studies in micromegas detectors in a 150 GeV/c pion beam Procureur, S; Aune, S; Ball, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Letnik:
659, Številka:
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Journal Article
Recenzirano
A detailed study of several Micromegas detectors prototyped for the COMPASS and CLAS12 experiments is presented. Using a 150 GeV/c pion beam, the discharge probability was measured for several ...detector variants including bulk and non-bulk Micromegas. A detector equipped with an additional GEM foil as pre-amplification stage was also tested. A resistive coating of the readout strips was found to reduce the amplitude of the discharge by at least two orders of magnitude which was below the detection limit of the experimental setup. The effects of the micro-mesh type and material were investigated as well as the influence of the drift gap. Response in the presence of a 1.5 T transverse magnetic field was also studied. The measurements presented were performed during a RD51 beam test period.
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