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Development of integrated waste management options for irradiated graphite
Alan Wareing,Liam Abrahamsen-Mills,Linda Fowler,Michael Grave,Richard Jarvis,Martin Metcalfe,Simon Norris,Anthony William Banford 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.5
The European Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste projectsought to develop best practices in the retrieval, treatment, and disposal of irradiated graphite includingother irradiated carbonaceous waste such as structural material made of graphite, nongraphitized carbonbricks, and fuel coatings. Emphasis was given on legacy irradiated graphite, as this represents a significantinventory in respective national waste management programs. This paper provides an overview ofthe characteristics of graphite irradiated during its use, primarily as a moderator material, within nuclearreactors. It describes the potential techniques applicable to the retrieval, treatment, recycling/reuse, anddisposal of these graphite wastes. Considering the lifecycle of nuclear graphite, from manufacture to finaldisposal, a number of waste management options have been developed. These options consider thetechniques and technologies required to address each stage of the lifecycle, such as segregation, treatment,recycle, and ultimate disposal in a radioactive waste repository, providing a toolbox to aid operatorsand regulators to determine the most appropriate management strategy. It is noted that nationalwaste management programs currently have, or are in the process of developing, respective approachesto irradiated graphite management. The output of the Treatment and Disposal of Irradiated Graphite andother Carbonaceous Waste project is intended to aid these considerations, rather than dictate them.
Abrahamsen-Mills, Liam,Wareing, Alan,Fowler, Linda,Jarvis, Richard,Norris, Simon,Banford, Anthony Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.4
An integrated waste management approach for irradiated graphite was developed during the European Commission project 'Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste'. This included the identification of potential options for the management of irradiated graphite, taking account of storage, retrieval, treatment and disposal methods. This paper describes how these options can be assessed using multi-criteria decision analysis (MCDA) for a case study relating to a generic power reactor. Criteria have been defined to account for safety, environmental, economic and socio-political factors, including radiological impact, resource usage, economic costs and risks. The impact of each option against each criterion has been assessed using data from the project and the wider literature. A linear additive approach has been used to convert the calculated impacts to scores. To account for the relative importance of the criteria, example weightings were allocated. This application has shown that MCDA approaches can be used to support complex decisions regarding irradiated graphite management, accounting for a wide range of criteria. Use of this approach by individual countries or organisations will need to account for the specific options, scores, weightings and constraints that apply, based on their national strategies, regulatory requirements and public acceptability.
Utilization of Putrescine by Streptococcus pneumoniae During Growth in Choline-limited Medium
Ware D.,Watt J.,Swiatlo E. The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.5
Polyamines such as putrescine are small, ubiquitous polycationic molecules that are required for optimal growth of eukaryotic and prokaryotic cells. These molecules have diverse effects on cell physiology and their intracellular content is regulated by de novo synthesis and uptake from the environment. The studies presented here examined the structure of a putative polyamine transporter (Pot) operon in Streptococcus pneumoniae (pneumococcus) and growth of pneumococci in medium containing putrescine substituted for choline. RT-PCR experiments demonstrated that the four genes encoding the Pot system are co-transcribed with murB, a gene involved in an intermediary step of peptidoglycan synthesis. Pneumococci grown in chemically-defined media (CDM) containing putrescine without choline enter logarithmic phase growth after 36-48 hs. However, culture density at stationary phase eventually reaches that of choline-containing medium. Cells grown in CDM-putrescine formed abnormally elongated chains in which the daughter cells failed to separate and the choline-binding protein PspA was no longer cell-associated. Experiments with CDM containing radiolabeled putrescine demonstrated that pneumococci concentrate this polyamine in cell walls. These data suggest that pneumococci can replicate without choline if putrescine is available and this polyamine may substitute for aminoalcohols in the cell wall teichoic acids.
Utilization of Putrescine by Streptococcus pneumoniae During Growth in Choline-limited Medium
D. Ware,J. Watt,E. Swiatlo 한국미생물학회 2005 The journal of microbiology Vol.43 No.5
Polyamines such as putrescine are small, ubiquitous polycationic molecules that are required for optimal growth of eukaryotic and prokaryotic cells. These molecules have diverse effects on cell physiology and their intracellular content is regulated by de novo synthesis and uptake from the environment. The studies presented here examined the structure of a putative polyamine transporter (Pot) operon in Streptococcus pneumoniae (pneumococcus) and growth of pneumococci in medium containing putrescine substituted for choline. RT-PCR experiments demonstrated that the four genes encoding the Pot system are co-transcribed with murB, a gene involved in an intermediary step of peptidoglycan synthesis. Pneumococci grown in hemically-defined media (CDM) containing putrescine without choline enter logarithmic phase growth after 36-48 hs. However, culture density at stationary phase eventually reaches that of choline-containing medium. Cells grown in CDM-putrescine formed abnormally elongated chains in which the daughter cells failed to separate and the choline-binding protein PspA was no longer cell-associated. Experiments with CDM containing radiolabeled putrescine demonstrated that pneumococci concentrate this polyamine in cell walls. These data suggest that pneumococci can replicate without choline if putrescine is available and this polyamine may substitute for aminoalcohols in the cell wall teichoic acids.
Evaluation of Neutron Cross Sections for Hafnium in the Resolved Resonance Range
T. Ware,D. Weaver,M. Moxon,C. Dean,R. Hiles,P. Schillebeeckx,S. Kopecky 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The international High Priority Request list notes: - "In the nuclear industry hafnium is used as neutron absorbing material to regulate the fission process. Interpretation of critical experiments with UOx fuel conducted by CEA in the AZUR zero-power reactors has shown systematic underestimation of the reactivity worth that may be attributed to an overestimated natural hafnium capture cross section in the epi-thermal energy range"To service the request for improved resonance data a PhD project has:-a) Improved REFIT R-matrix evaluation code.b) Obtained hafnium oxide samples enriched in Hf176, 177, 178, 179 isotopes.c) Gained support from NUDAME and EUFRAT projects.d) Prepared enriched and natural Hf samples.e) Performed capture and transmission Time of Flight measurements at the GELINA linear accelerator.f) Analysed the capture counts to generate yields using AGS and AGL codes.g) Used REFIT to perform least squares analysis of GELINA measurements.(Included previous ORNL, Harwell and RPI transmissions and capture yields.)h) Submitted results to EXFOR.i) Included resolved resonance parameters in JEFF evaluations taking the resolved range to over 1keV. j) Tested evaluations with suitable benchmarks.k) Passed resolved resonance data to CEA Cadarache for unresolved analysis.Resultant Hf evaluations will be included in JEFF3.2.