To see the other types of publications on this topic, follow the link: Decommissioning.
Dissertations / Theses on the topic 'Decommissioning'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Decommissioning.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Hicks, David Ian. "Design for decommissioning." Thesis, University of Bath, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425861.
Full text
2
Ayoade, Adedayo. "Addressing the decommissioning problem : towards a theory of 'sustainable decommissioning' for disused offshore installations/pipelines." Thesis, University of Dundee, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398311.
Full text
3
Herbas, Mélodie. "Ion exchange to cope with decommissioning." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/ion-exchange-to-cope-with-decommissioning(fd150782-5021-4243-8d30-f3dcfec9abec).html.
Full textAbstract:
This PhD project studied the caesium and strontium removal capacities of six nanoporous materials. Indeed, it was linked in with the SIXEP plant present at Sellafield site, UK, which is currently using natural clinoptilolite, originally mined from the Mojave Desert, to remove radioactive caesium and strontium ions from wastewater effluents. At the moment the feeds entering the SIXEP plant correspond to the best working conditions for clinoptilolite. As the feeds are moving toward more acidic pH and complex solutions and as clinoptilolite works at neutral pH, new nanoporous materials are required. This project had been divided into sub-projects, which all had the same purpose of finding the best material for caesium and strontium removal under complex solutions. The first part of the PhD focused on the synthesis of CST, SNT, ETS-4 and ETS-10 materials following literature reviews. The two last materials studied were provided by Fortum Power and Heat Oy for CsTreat material and by Sellafield Ltd for clinoptilolite material. The second part of the PhD consisted in studying the exchange capacities for caesium and strontium ions for each material studied under batch conditions using several water compositions relevant to Sellafield Ltd. Each water composition had different competing ions or pH and were used to classify the materials between them. From that it was found that Clinoptilolite stays the best materials for caesium and strontium removal. The third part of the project was the gamma irradiation of the materials. This irradiation had an aim to check the stability of the structure of the studied materials under gamma irradiation. The materials were exposed to four different gamma doses which were 0.5; 1; 3 and 6 MGy, the last one corresponding to the maximum dose were structural changes could happen. This revealed that all the materials, except ETS-4 material, were stable under gamma irradiation and that no structural changes were observable. The fourth part of the project was an extension of the third part in which the materials were Cs exchanged before being gamma irradiated to a dose of 6 MGy. This showed that the caesium exchange process is not affected by radiation. Finally, the unexchanged materials were alpha irradiated using a 15 MeV He2+ beam at the Dalton Cumbria Facility. Two irradiations were performed on CsTreat, CST, ETS-4, ETS-10 and clinoptilolite material. It was found that all the materials were damaged by alpha irradiation and displayed amorphous framework To resume, it appeared that clinoptilolite still stays one of the best materials for the removal of caesium and strontium ions in a wide range of wastewater composition. Additionally, it was discovered that ETS-10 material could be a good alternative to clinoptilolite material as its structure is stable under gamma irradiation and it displayed good exchange capacities when competing ions were present in the feeds. CST could also be a substitute as it shows good ion exchange properties under a broad range of pH. SNT material was great for strontium removal while CsTreat was working well for caesium removal. Even though ETS- 4 revealed good ion exchange capacities they were lower than clinoptilolite, ETS- 10 or CST materials.
4
Kim, Dae Ji. "Tritium speciation in nuclear decommissioning materials." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/72145/.
Full textAbstract:
Tritium is a by-product of civil nuclear reactors, military nuclear applications, fusion programmes and radiopharmaceutical production. It commonly occurs, though not exclusively, as tritiated water (HTO) or organically-bound tritium (OBT) in the environment but may exist as other forms in nuclear-related construction and fabrication materials. During the lifetime of nuclear sites (especially those involving heavy water) tritium becomes variably incorporated into the fabric of the buildings. When nuclear decommissioning works and environmental assessments are undertaken it is necessary to accurately evaluate tritium activities in a wide range of materials prior to any waste sentencing. Of the various materials comprising UK radioactive wastes, concrete and metal account for approximately 20% of the total weight of low level waste (LLW) and 12% and 35% of the total weight of intermediate level waste (ILW). Proper sampling and storage of samples are significant factors in achieving accurate tritium activities. The degree of loss of 3H and cross-contamination can be significantly reduced by storing samples in an air/water tight container in a freezer (-18°C). The potential for tritium contamination is dependent on the 3H form. Most 3H loss originates from tritiated water which is easily exchanged with atmospheric hydrogen in the form of water vapour at room temperature. However, the loss of more strongly bound 3H, produced in-situ in materials by neutron activation, is not significant even at room temperature. Such tritium is tightly retained in materials and does not readily exchange with water or diffuse. In nuclear reactor environments tritium may be produced via several neutron-induced reactions, 2H(n,g)3H, 6Li(n,a)3H, 10B(n,2a)3H and ternary fission (fission yield <0.01%). It may also exist as tritiated water (HTO) that is able to migrate readily and can adsorb onto various construction materials such as structural concrete. In such locations it exists as a weakly-bound form that can be lost at ambient temperatures. Bioshield concretes present a special case and systematic analysis of a sequence of sub-samples taken from a bioshield core (from UKAEA Winfrith) has identified a strongly-bound form of 3H in addition to the weakly bound form. The strongly bound 3H in concrete is held more strongly in mineral lattices and requires a temperature of >850°C to achieve quantitative recovery. This more strongly retained tritium originates from neutron capture of trace lithium (6Li and potentially 10B) distributed throughout minerals in the concrete. The highest proportion of strongly bound 3H was observed in the core sections closest to the core. Weakly bound tritium is associated with water loss from hydrated mineral components. Tritium is retained in metals by absorption by free water, hydrated surface oxidation layer, H ingress into bulk metal and also as lattice-bound tritium produced via in-situ neutron activation. Away from the possible influence of neutrons, the main 3H contamination to metals arises from absorption and diffusion via atmospheric exposure to the HTO. Here contamination is mainly confined to the metal surface layer. The tritium penetration rate into metal surfaces is controlled by the metal type and its surface condition. Where metals are exposed to a significant neutron flux and contain 6Li, 7Li and 10B then in situ 3H production will occur which may propagate beyond the surface layer. In such cases tritium may exist in two forms namely a weakly bound HTO form and a non-HTO strongly bound form. The HTO form is readily lost at moderate temperatures (~120°C) whereas the non-HTO requires up to 850°C for complete extraction.
5
Breidablikk, Line Småge. "Heavy Lift Methods in Decommissioning of Installations." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11456.
Full textAbstract:
In this report decommissioning of offshore petroleum platforms have been investigated. It treats decommissioning in general, the process of a typical project. A variety of suitable lifting vessels have been presented, and some concepts of removal have been evaluated. Decommissioning is important to go through with because of the environment and the use of the area after the petroleum activities ceases. Other ocean users benefit from the decommissioning because the area can be utilized when it is opened for ordinary traffic. The environment will benefit from the cessation of production because of fewer spills to sea or risk of it and being restored to a state as close to possible to original. Sometimes it is found acceptable to leave facilities behind, partially or wholly, and the marine life in the area can actually benefit from this in some cases. A decommissioning project consists of the elements planning and approval, topside and jacket preparatory work, topside removal, jacket removal, transport, and onshore dismantling and recycling. There are two main concepts of removal, reverse installation and single lift. The elements of the project are the same whichever of the concepts are used. The vessels to be used need large lifting capacities in either concept. Especially designs that lift topsides and jacket in single lifts can improve the efficiency in the projects. Several lifting vessels have been presented and a few concepts were reviewed regarding future requirements. The concepts were platform removal using only a traditional HLV, topside removal using HLV and jacket removal using buoyancy tanks, and removal using the new lifting vessel design Pieter Schelte. It is found that all the concepts can remove fixed platforms, but Pieter Schelte was especially well-suited. When Pieter Schelte is used, personnel will be exposed to less risk because more work is done onshore. Onshore work is in general more inexpensive, faster, cleaner, and safer. This gives a better HSE profile to the project as well as being more cost-efficient. On the downside, the vessel is not available before 2013. In the meantime the alternative with the HLV and buoyancy tanks can gain some more experience. This alternative scored the same as removal with reverse installation and is therefore not so successful in this comparison. There are however uncertainties involved and the solution with the buoyancy tanks are still interesting. The challenges in decommissioning are to make it less expensive, less time-consuming, and safer than today as well as keeping the environmental issues satisfactory. This can probably be reached by making the process more standardised to some extent, making use of new technologies like new vessels, doing less work at the offshore site, carrying out less lifts offshore, and do a lot of the dismantling work onshore. Pieter Schelte can to a great extent be the solution to these challenges.
6
McBryde, Daniel John. "Ice pigging in the nuclear decommissioning industry." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702749.
Full textAbstract:
Ice pigging is a novel technology using thick ice slurry (a two-phase mixture of ice crystals and freezing point depressant solution) to clean the internal surfaces of pipes or ducts; this mixture displays semi-solid characteristics. When pumped through a pipe, the slurry adopts plug flow, forming an 'ice pig'; slip occurs at the interface with the pipe walls generating high shear stresses; thus able to mobilise and remove sediment residing at the pipe wall. Ice pigs are able to navigate demanding topologies such as vertical falls, diameter changes, orifice plates, heat exchangers, and intrusive instrumentation; they provide a method of removing fouling without the need for dis-assembly, reducing valuable down-time, labour intensive pipe work dismantling, and subsequent manual cleaning. Many decades of nuclear activity here in the UK have produced unique and difficult challenges that require solving at Sellafield, the UK's nuclear waste reprocessing site. The drive to produce plutonium for atomic weapons during the 1950's, with very little foresight towards how the wastes and facilities would be dealt with, has brought about significant challenges. As these facilities are nearing the end of their design lives, the time has come to assess methods of treating these wastes and decommissioning the facilities in a safe, controlled, and cost-effective manner. Ice pigging is one of many technologies being assessed for such a task; this thesis details specific areas of application where experimental work has been conducted. Experimental work conducted in this thesis has: developed a method of characterising the ice pig's sediment removal performance compared to simple water flushing, assessed the ice pig's ability to remove representative sediments, assessed the ice pig's suitability for removing sediment from heat exchangers to restore thermal performance, and analysed the rate of percolation of the driving fluid through the ice pig body, such that the suitability of the ice pig for separating fluids can be established.
7
Thomas, Gisèle-Christine. "A stock decommissioning plan for a sludge lagoon." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ30039.pdf.
Full text
8
Watson, Verity. "A cost benefit analysis of decommissioning offshore installations." Thesis, University of Aberdeen, 2003. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU152080.
Full textAbstract:
As offshore installations in the North Sea near the end of their economically viable life they will be decommissioned. There is limited experience of decommissioning the structures in the Northern North Sea. When decommissioning is being considered studies are undertaken to assess each option on such criteria as: environmental impact, technical feasibility, cost, health and safety and public acceptability. This thesis aims to explore the contribution that economics can make to the debate surrounding decommissioning with the introduction of a cost benefit analysis framework within which to compare each decommissioning option. Cost Benefit Analysis (CBA) considers the economic costs and benefits from any change in resource allocation within an economy. This would provide a structured assessment of all the impacts of decommissioning in monetary terms. CBA also allows social desirability to be considered. The CBA framework involves valuing costs and benefits. Whilst estimating costs raises important questions, the identification, measurement and valuation of (dis)benefits represents one the greatest challenges facing economists. This thesis will focus on how economics can be applied to this problem to obtain monetary valuations of the benefits of decommissioning. Two methods of valuing the (dis)benefits of decommissioning are considered - Contingent Valuation Method (CVM) and Discrete Choice Experiments (DCE). These are applied to valuing of one impact of decommissioning (drill cuttings) and the value of alternative decommissioning policies. As well as addressing the issue of decommissioning, these experiments also consider methodological issues in the application of CVM (dealing with Don't Know and Protest responses) and DCE (testing for compensatory decision making). Following this the costs of decommissioning are estimated using an existing financial simulation model developed for oil industry use. Recommendations are made for policy and future methodological work.
9
Dallimore, Matthew. "Gamma ray imaging in industrial and medical applications." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246854.
Full text
10
Baumbusch, Jennifer Lyn. "Decommissioning citizenship : the organization of long-term residential care." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1714.
Full textAbstract:
Long-term residential care (LTRC) is a complex sociopolitical milieu where people from diverse backgrounds come to live and work together. In recent years health care restructuring has resulted in the closure of facilities; health care policy has narrowed the population that accesses LTRC so that only those who are the most medically and socially complex are admitted; and there has been a transformation of the work force, a workforce that is mainly comprised of Women of Colour and is among the lowest paid in health care. The purpose of this study was to critically examine the organization of care in LTRC within this context.
The theoretical perspective guiding the study was informed by postcolonialism, postcolonial feminism, intersectionalities, and Foucaudian epistemology. The method of inquiry for the study was critical ethnography, which allowed for critical analysis of `taken for granted' assumptions in the organization of care.
Over a period of ten months, I was immersed in two LTRC facilities in the Lower Mainland of British Columbia. Field work consisted of approximately 218 hours of participant observation. I conducted 51 interviews with administrators, family members, residents, and staff. I reviewed relevant provincial policies and facility-based policies and procedures. I also collected quantitative data related to resident transitions in the health care system (for example, admissions, discharges, and hospital admissions), and staffing levels.
Findings from this study were discussed in three key themes. First, a systematic decommissioning of citizenship occurred for residents and staff in this setting. Second, the impact of health care restructuring over the past decade had important consequences for relationships between residents, family, and staff. Third, relational care took place in `stolen' moments that occurred despite heavy workloads. All of these themes were underscored by intra-gender oppression, relations of power, and influenced by discourses of ageism and corporatism, which ultimately played out in day to day interactions between those who live and work there. Recommendations from this study included: addressing the entrenched hierarchies in nursing, further examination of the public-private funding model in LTRC, and the introduction of an independent ombudsperson to ensure consistent, high quality care across the LTRC sector.
11
Sublet, Jean-Christophe. "Activation considerations relevant to the decommissioning of fusion reactors." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46569.
Full text
12
Fourtakas, Georgios. "Modelling multi-phase flows in nuclear decommissioning using SPH." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/modelling-multiphase-flows-in-nuclear-decommissioning-using-sph(f5ed0b5b-ea62-431a-bb6e-a18635d396bc).html.
Full textAbstract:
This thesis presents a two-phase liquid-solid numerical model using Smoothed Particle Hydrodynamics (SPH). The scheme is developed for multi-phase flows in industrial tanks containing sediment used in the nuclear industry for decommissioning. These two-phase liquid-sediments flows feature a changing interfacial profile, large deformations and fragmentation of the interface with internal jets generating resuspension of the solid phase. SPH is a meshless Lagrangian discretization scheme whose major advantage is the absence of a mesh making the method ideal for interfacial and highly non-linear flows with fragmentation and resuspension. Emphasis has been given to the yield profile and rheological characteristics of the sediment solid phase using a yielding, shear and suspension layer which is needed to predict accurately the erosion phenomena. The numerical SPH scheme is based on the explicit treatment of both phases using Newtonian and non-Newtonian Bingham-type constitutive models. This is supplemented by a yield criterion to predict the onset of yielding of the sediment surface and a suspension model at low volumetric concentrations of sediment solid. The multi-phase model has been compared with experimental and 2-D reference numerical models for scour following a dry-bed dam break yielding satisfactory results and improvements over well-known SPH multi-phase models. A 3-D case using more than 4 million particles, that is to the author’s best knowledge one of the largest liquid-sediment SPH simulations, is presented for the first time. The numerical model is accelerated with the use of Graphic Processing Units (GPUs), with massively parallel capabilities. With the adoption of a multi-phase model the computational requirements increase due to extra arithmetic operations required to resolve both phases and the additional memory requirements for storing a second phase in the device memory. The open source weakly compressible SPH solver DualSPHysics was chosen as the platform for both CPU and GPU implementations. The implementation and optimisation of the multi-phase GPU code achieved a speed up of over 50 compared to a single thread serial code. Prior to this thesis, large resolution liquid-solid simulations were prohibitive and 3-D simulations with millions of particles were unfeasible unless variable particle resolution was employed. Finally, the thesis addresses the challenging problem of enforcing wall boundary conditions in SPH with a novel extension of an existing Modified Virtual Boundary Particle (MVBP) technique. In contrast to the MVBP method, the extended MVBP (eMVBP) boundary condition guarantees that arbitrarily complex domains can be readily discretized ensuring approximate zeroth and first order consistency for all particles whose smoothing kernel support overlaps the boundary. The 2-D eMVBP method has also been extended to 3-D using boundary surfaces discretized into sets of triangular planes to represent the solid wall. Boundary particles are then obtained by translating a full uniform stencil according to the fluid particle position and applying an efficient ray casting algorithm to select particles inside the fluid domain. No special treatment for corners and low computational cost make the method ideal for GPU parallelization. The models are validated for a number of 2-D and 3-D cases, where significantly improved behaviour is obtained in comparison with the conventional boundary techniques. Finally the capability of the numerical scheme to simulate a dam break simulation is also shown in 2-D and 3-D.
13
Zanlongo, Sebastian A. "Multi-Robot Coordination and Scheduling for Deactivation & Decommissioning." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3897.
Full textAbstract:
Large quantities of high-level radioactive waste were generated during WWII. This waste is being stored in facilities such as double-shell tanks in Washington, and the Waste Isolation Pilot Plant in New Mexico. Due to the dangerous nature of radioactive waste, these facilities must undergo periodic inspections to ensure that leaks are detected quickly. In this work, we provide a set of methodologies to aid in the monitoring and inspection of these hazardous facilities. This allows inspection of dangerous regions without a human operator, and for the inspection of locations where a person would not be physically able to enter.
First, we describe a robot equipped with sensors which uses a modified A* path-planning algorithm to navigate in a complex environment with a tether constraint. This is then augmented with an adaptive informative path planning approach that uses the assimilated sensor data within a Gaussian Process distribution model. The model's predictive outputs are used to adaptively plan the robot's path, to quickly map and localize areas from an unknown field of interest. The work was validated in extensive simulation testing and early hardware tests.
Next, we focused on how to assign tasks to a heterogeneous set of robots. Task assignment is done in a manner which allows for task-robot dependencies, prioritization of tasks, collision checking, and more realistic travel estimates among other improvements from the state-of-the-art. Simulation testing of this work shows an increase in the number of tasks which are completed ahead of a deadline.
Finally, we consider the case where robots are not able to complete planned tasks fully autonomously and require operator assistance during parts of their planned trajectory. We present a sampling-based methodology for allocating operator attention across multiple robots, or across different parts of a more sophisticated robot. This allows few operators to oversee large numbers of robots, allowing for a more scalable robotic infrastructure. This work was tested in simulation for both multi-robot deployment, and high degree-of-freedom robots, and was also tested in multi-robot hardware deployments.
The work here can allow robots to carry out complex tasks, autonomously or with operator assistance. Altogether, these three components provide a comprehensive approach towards robotic deployment within the deactivation and decommissioning tasks faced by the Department of Energy.
14
Tüzün, Dilan. "Development of uniform surface sources by functionalization for decommissioning." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP013.
Full textAbstract:
La thèse vise à développer des sources radioactives surfaciques pour améliorer la traçabilité des mesures de la contamination surfacique. En particulier, le sujet vise à fournir in fine des sources radioactives traçables et utilisables sur le terrain pour caractériser les performances des moniteurs de contamination surfacique. Les sources qui répondent aux exigences des normes internationales ont des caractéristiques très différentes des surfaces à contrôler dans le cadre des activités de l'assainissement et démantèlement (A&D). Elles sont constituées d'un substrat en aluminium rigide sur lequel l'activité est déposée en surface puis recouverte d'une couche de protection. L'approche de la thèse vise à lier chimiquement les éléments radioactifs aux substrats sélectionnés. L'étude a consisté à mettre au point des méthodes de modification de deux types de substrats, polymériques et aluminium, pour y attacher des éléments radioactifs (lanthanide et actinide trivalents). La modification des surfaces d'aluminium à l'aide d'oxydes de manganèse ou de chrome a été réalisée ainsi que leur silanisation et leur greffage avec des acides phosphoniques. Les surfaces polymériques ont quant à elles été d'abord oxydées puis fonctionnalisées avec des acides sulfoniques. Le processus se divise en plusieurs étapes : préparer la surface, la fonctionnaliser/modifier, y attacher la radioactivité et quantifier l'uniformité de la distribution radioactive. Chaque étape a fait l'objet d'optimisations et de caractérisations (MEB, RTA-IRTF, scintillation liquide et autoradiographie). Le substrat Aluminium, tout en étant flexible, permet de conserver un point de comparaison avec les normes en vigueur et le substrat polymérique peut être modifié pour s'approcher des contraintes du terrain (charge en sable, rugosité, moulage de formes complexes). Enfin, une évaluation de la conformité des sources aux normes existantes a été réalisée, même si ces normes ne permettent pas de répondre aux besoins complexes des mesures sur les chantiers d'A&D. Avec les substrats polymériques modifiés avec de l'oxyde de manganèse, il a été possible de fixer environ 100 % d'Eu-152 et d'Am-241 après quelques heures d'immersion dans des solutions radioactives. L'uniformité de la radioactivité de ces sources a atteint 90 %The thesis aims to develop radioactive surface sources to improve the traceability of surface contamination measurements carried out during dismantling operations. In particular, the ultimate aim is to provide radioactive sources that can be traceable and used in the field to characterize the performance of surface contamination monitors. The sources that meet the requirements of international standards have very different characteristics from the surfaces to be monitored during decontamination and dismantling (D&D) activities. They consist of a rigid aluminum substrate on which surface the activity is deposited and then covered with a protective layer. The study involved developing methods for modifying two types of substrates, polymeric and aluminum, to attach radioactive elements (trivalent lanthanide and actinide). For aluminum substrates, coating with manganese or chromium oxides was tested, along with silanol functionalization and phosphonic acid grafting. The surface modification of polymeric substrates was based on oxidation, followed by sulfonic acid grafting. Whatever the substrate, the study was divided into several stages: preparing the surface, functionalizing/modifying it, attaching the radioactivity and quantifying the uniformity of the radioactive distribution. Each stage was optimized and characterized using SEM, ATR-FTIR, liquid scintillation and autoradiography. The aluminum substrate, while flexible, allows to be compared with current standard sources. Additionally, the polymeric substrates can be adapted to mimic the real constraints of the D&D sites (sand load, roughness, molding of complex shapes). Finally, an assessment of the compliance of the sources with existing standards was carried out, even though these standards do not meet the complex needs of measurements on D&D sites. The polymeric substrates coated with manganese oxide could uptake close to 100% of ¹⁵²Eu and ²⁴¹Am when immersed in acidic radioactive solutions for a few hours. For these sources, the uniformity of the radionuclide distribution reached 90%
15
Fort, Emily Minatra. "A historical site assessment of the Georgia Tech Research Reactor." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17257.
Full text
16
Grabrovaz, Meaghan. "An investigation into the forecasting of skills in nuclear decommissioning." Thesis, University of Central Lancashire, 2017. http://clok.uclan.ac.uk/23759/.
Full textAbstract:
This study explores the nature of skills forecasting in nuclear decommissioning and that which makes skills forecasting information useful. The study adopts a pragmatic approach using an interpretative, qualitative case study research design and draws on aspects of a critical realist approach to uncover, deconstruct and challenge some ‘norms’ in skills forecasting. The study makes an original contribution to knowledge through the identification of nineteen factors that influence skills forecasting in the nuclear industry. It also generates a baseline of knowledge on the theory and practice of skills forecasting and management through a review of the literature on skills, forecasting, skills forecasting and workforce planning and relevant aspects of public sector management and HRM. The study documents and compares current skills forecasting practice amongst UK site licensed companies and selected supply chain companies. Such research has not previously been conducted in the nuclear decommissioning industry. This answers research questions about why, and how, different groups in the sector perform skills forecasting and how variations in approaches affect the information produced. It also answers research questions about who uses skills forecasting information, and how. Together with a review of current problems with skills information, this contributes to an understanding of what makes skills information useful. The research evidences that while the industry has some common features with other High Reliability Organisations, there are unique dimensions which make this research significant. Some ‘norms’ operating in skills forecasting were challenged including how it is being used, eg as an agent for change by some groups, and assumptions about the potential availability of skills from the supply chain. The literature review was used to construct a practical-ideal type, an approach derived from classical pragmatism offering a version of a nearly ideal process, on the understanding that this is socially constructed and subject to continual change. Existing practice is evaluated against this practical-ideal type in a unique application of this methodology in the nuclear decommissioning context.
17
Al-Sallami, Omer. "CABLES DECOMMISSIONING IN OFFSHORE WIND FARMS: ENVIRONMENTAL AND ECONOMICAL PERSPECTIVE." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448448.
Full textAbstract:
Addressing the decommissioning issues is vital to ensure a sustainable and effective process of such an essential part of the project life cycle. While there is a set of good practices and regulations that govern most of the decommissioning activities, the cable decommissioning issue is still in a big debate and often left abandoned at the seabed due to environmental concerns, as justified by most developers. This paper is aiming to understand the environmental and economic consequences of cable decommissioning. The available research papers and reports that are dealing with cable decommissioning issues have been reviewed. The cables are often decommissioned using similar methods to installation. However, there are no regulatory obligations to removing the cables in most countries. Cable installation will be associated with environmental impacts, but they are considered to be negligible. Additionally, Recycling cables’ copper is beneficial in both aspects environmentally and economically as copper prices are on the rise. A comparison between the ESs and decommissioning programs in a number of OWFSs have been conducted to understand the justification used for abandoning the cables. Most of the decommissioning reports have considered cable decommissioning to cause “considerable damage to seabed ecology”. However, that contradicts what was found in the ESs, where the impact level was considered negligible and anticipated to be similar to installation. It was unclear whether the abandonment of cables was driven by environmental considerations or not. A case study has been selected to compare cable and monopile decommissioning costs and the contribution of each component to the total decommissioning cost, including possible revenue generated from recycling. It was found that the cost-benefit of cable decommissioning is incomparable to monopile decommissioning as the latter is very costly, and the possible residual value is insignificant when compared to cables. Moreover, it is possible that the total cable decommissioning cost to be largely offset by the revenue generated from copper resell. Additionally, the cable decommissioning total cost can be almost paid by recycling cables if copper prices increase in the near future.
18
Vivas, Ary de Souza. "Desenvolvimento do plano preliminar de descomissionamento do reator IPEN/MB-01." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85133/tde-22012015-164403/.
Full textAbstract:
Em todo mundo, muitas instalações nucleares foram construídas e necessitarão serem desligadas em um determinado momento por estarem próximas do seu tempo recomendado de utilização que é de aproximadamente 40 anos. A AIEA (Agência Internacional de Energia Atômica) busca orientar e recomendar uma série de diretrizes para a realização de atividades de descomissionamento de instalações nucleares, com atenção especial aos países que não possuem um quadro regulatório legal que ampare as atividades de descomissionamento. O Brasil, até o momento, não possui uma norma específica que oriente as etapas de descomissionamento de reatores de pesquisa. Entretanto, em março de 2011 foi constituída uma comissão de estudo com a atribuição principal voltada às questões de descomissionamento das instalações nucleares brasileiras, culminando na resolução 133, de 8 de novembro de 2012, um projeto de norma que dispõe sobre o Descomissionamento de Usinas Nucleoelétricas. O Instituto de Pesquisas Energéticas e Nucleares (IPEN) possui dois reatores de pesquisa sendo um deles o reator IPEN/MB-01. O objetivo dessa dissertação de mestrado é elaborar um plano preliminar de descomissionamento desse reator de pesquisa, considerando a documentação técnica da instalação (RAS-Relatório de Análise de Segurança), as normas existentes da CNEN (Comissão Nacional de Energia Nuclear), assim como as recomendações da AIEA. Em termos de procedimentos de descomissionamento para reatores de pesquisa, este trabalho se baseou no que existe de mais moderno em experiências, estratégias e lições aprendidas realizadas e documentadas nas publicações da AIEA que abrangem técnicas e tecnologias de descomissionamento. Considerando estes conhecimentos técnicos e às peculiaridades da instalação, foi selecionada a estratégia de desmantelamento imediato, que corresponde ao inicio das atividades de descomissionamento assim que a instalação for desligada, dividindo-a em setores de trabalho. Como recurso de gerenciamento e acompanhamento do projeto de descomissionamento do reator e manutenção de registros, foi desenvolvido um banco de dados utilizando o programa Microsoft Access 2007, no qual contêm todos os itens e informações referentes ao plano preliminar de descomissionamento. O trabalho aqui descrito busca atender os requisitos, critérios técnicos e institucionais, incorporando o que se tem de mais atual em procedimentos de descomissionamento, podendo servir como guia para as demais instalações brasileiras.Around the world, many nuclear plants were built and need to be turned off at a certain time because they are close to their recommended time of use is approximately 50 years. So the IAEA (International Atomic Energy Agency), seeks to guide and recommend a set of guidelines for the conduct of activities of nuclear facilities, with special attention to countries that do not have a framework regulatory Legal that sustain the activities of decommissioning. Brazil, so far, does not have a specific standard to guide the steps of the guidelines regarding decommissioning research reactors. However, in March 2011 a study committee was formed with the main task facing the issues of decommissioning of nuclear installations in Brazil, culminating in Resolution 133 of November 8, 2012, a standard project that treat about the Decommissioning of nucleoelectric plants. O Instituto de Pesquisas Energéticas e Nucleares (IPEN) has two research reactors one being the reactor IPEN/MB-01. The purpose of this master dissertation is to develop a preliminary plan for decommissioning this research reactor, considering the technical documentation of the facility (RAS-Safety Analysis Report), the existing standards of CNEN (National Nuclear Energy Commission), as well as IAEA recommendations. In terms of procedures for decommissioning research reactors, this work was based on what is most modern in experiences, strategies and lessons learned performed and documented in IAEA publications covering techniques and technologies for decommissioning. Considering these technical knowledges and due to the peculiarities of the facility, was selected to immediate dismantling strategy, which corresponds to the start of decommissioning activities once the installation is switched off, dividing it into work sectors. As a resource for monitoring and project management of reactor decommissioning and maintenance of records, we developed a database using Microsoft Access 2007, which contain all the items and information for the preliminary decommissioning plan. The work described here aims to meet the requirements, technical and institutional criteria, incorporating what is most current procedures and lessons learned of decommissioning, may serve as a guideline for the other brazilian facilities.
19
Kerkvliet, Hans. "OFFSHORE WIND FARM DECOMMISSIONING: INTRODUCING A MULTI-CRITERIA DECISION AID APPROACH." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256567.
Full textAbstract:
The objective of this Thesis is to develop a methodological framework to guide the decision maker in selecting a decommissioning method for offshore wind farms which is supported by the majority of relevant stakeholders. Initially, a literature review has been conducted to find out which methods are available to decommission an off-shore wind farm and which criteria can influence the outcome.Two methods have been found in literature, namely partial and total removal of the foundation. Furthermore, twenty one (21) criteria have been found which could influence the results. These criteria can be divided in four categories which are economical, environmental, social and technical.Subsequently, a methodological framework was developed that included four steps. First, the possible decommissioning methods should be identified. Following on that, information should be collected and stakeholders should be selected. Subsequently, criteria should be selected and as last a multi criteria decision aid method should be used. It is expected that this procedure would lead to a decommissioning method which is supported by most of the stakeholders.To validate the methodological framework, a case study in the Netherlands has been selected. For this case study, four (4) stakeholders were identified and eleven (11) criteria were assessed. The outranking multi-criteria decision aid method PROMETHEE II was selected and results were obtained. Analyzing the results, it was possible to conclude that only one stakeholder preferred the total removal method while the other three stakeholders preferred the partial removal method.
20
Gledhill, Peter L. "Cutting and deployment system development for decommissioning of underwater steel structures." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=196133.
Full textAbstract:
This thesis was stimulated by the requirement to decommission offshore steel structures in the North Sea Offshore Oil and Gas Industry, but applies worldwide, where Oil and Gas production has ceased. It initially shows the UK Government assessment of the scale of decommissioning in the UKCS where there are several hundred structures with associated pipelines, risers and wellheads that have to be cut into sub-structures and individual pieces and then removed. Factors other than cessation of production drive the sequence and timing of structural decommissioning, such as the price of oil &gas and what new development might require already installed infrastructure. The nature of decommissioning of underwater steel lattice structure of offshore oil platforms called ‘jackets’ and underwater infrastructure is briefly discussed with the focus on cutting. The comparison of the performance of different underwater cutting tools currently most used in decommissioning is investigated with respect to two new underwater cutting techniques not only in terms of speed of cut but also in terms of deployment time and infrastructure requirements. A number of mainstream cutting tools and deployment systems are briefly introduced to provide a background, showing the range of tools preceding those investigated in more detail in terms of cutting and deployment efficiency. During the initial cutting research it was considered that fibre lasers had developed sufficiently in terms of power density, size and cost to be applied to underwater cutting. They were considered to have potential benefits over other underwater cutting techniques due to the continually increasing power density at the cut and have the advantage of a small envelope due to the small size of the potential cutting head The potential footprint of the laser head was envisaged to be similar to that of the rotating electrode arc tool therefore the deployment issues investigated might apply to both. The later development There is little published information on underwater cutting by laser particularly for the Oil and Gas Industry except for application to cutting rock for drilling. Research has been biased towards the nuclear industry using manufacturing techniques for surface treatment and cooling to reduce stress cracking. Fibre lasers are expensive to buy and logistically difficult to rent therefore it was considered that 1.2 kW CO2 laser at the University of Aberdeen (UoA) could be employed in obtaining an insight into the cutting and deployment issues concerned. Thus, the author designed, built and tested an underwater laser cutting head that would interface to the CO2 laser and would work at different orientations, fully submerged underwater in a tank. The trials were designed to assess the relationship of cutting parameters and performance at three orthogonal attitudes underwater, (beam downward, horizontal and upward pointing) to represent the orthogonal approach to horizontal and vertical primary axis tubular members, that comprise a jacket’s construction. The cutting parameters and their effects were then analysed to determine trends, behaviour and technical issues. Although an underwater laser cutting system could use a fibre laser, the CO2 laser enabled preliminary tests to be carried out and the viability of a cutting head to be explored. In the conclusion the design and performance of the laser cutting head is assessed with respect to the performance of other main-stream underwater cutting tools developed earlier. Offshore deployment of the laser cutting head is also discussed. Recommendations for future research and development work, to enable the realisation of underwater laser cutting, are presented.
21
Nancekievill, Matthew. "The radiation tolerance and development of robotic platforms for nuclear decommissioning." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/the-radiation-tolerance-and-development-of-robotic-platforms-for-nuclear-decommissioning(75451a19-57c6-4809-92dd-9b683db9b10f).html.
Full textAbstract:
There is an increasing desire to deploy low-cost robotic systems in nuclear decommissioning environments. These environments include long-standing nuclear fuel storage ponds such as those at the Sellafield site in Cumbria, UK as well as areas affected by expulsion of radioactive material from sites such as the Fukushima accident in Japan 2011. An area of concern for the successful deployment of robotic platforms in a radioactive field is their radiation tolerance. It is necessary to understand how the low-cost components used within robotic platforms react to radiation exposure in a nuclear decommissioning environment. This thesis discusses the radiation tolerance of multiple commercial-off-the-shelf (COTS) components that are commonly used within a robotic platform up to an expected yearly total dose of 5 kGy(Si). It was found that COTS voltage regulators are susceptible to gamma exposure, however, development of a discrete voltage regulator showed an increased tolerance to radiation under certain load and temperature conditions. Inertial measurement units were also investigated and found to be susceptible to a total ionising dose.
22
McCarthy, John. "WIND FARM DECOMMISSIONING: A DETAILED APPROACH TO ESTIMATE FUTURE COSTS IN SWEDEN." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256669.
Full textAbstract:
Although targets for renewable energy exist in Sweden, developing wind energy has proven to be challenging for developers. This is due in part to the demands made by authorities for monetary amounts to be set aside to take care of wind turbine dismantling and site restoration costs at the end of their lifecycle. There has been a large degree of uncertainty surrounding the amounts being demanded and the level to which sites must be restored, partially due to a lack of guidelines. Coupled with ambiguity, there has been a tendency by authorities and developers to use figures from previous high court decisions and previous permit applications to project decommissioning costs for current applications.This thesis evaluates seven different wind farm decommissioning scenarios using a model developed to estimate future costs, with the turbine model and the quantity of turbines being the parameters that vary. The model uses data from numerous sources, including real case decommissioning projects and figures from an existing model that had already been used to forecast costs in Sweden. One of the assumptions of the model developed is that scrap metals in wind turbines will have a residual value when decommissioning occurs; this was not allowed for in a recent decision made by a county administrative board following an environmental high court decision. An argument is made to justify that a minimum scrap value for wind turbines should be considered, based on the findings of the model. A further case is made to allow for the security bonds to be paid over an extended period of time, considering the initial value of wind farms.The results of the model show that the turbine model has an impact on the decommissioning costs and the potential residual value that can be obtained. In addition, the quantity of the wind turbines has a considerable effect on the decommissioning costs. These results suggest that each wind development project should be treated on a case-by-case basis using a calculation-based approach when determining the cost for a security bond. Recommendations for future research include considering wind farm location in the model.
23
Ashton, Linda. "Determination of ³⁶Cl and other long-lived radionuclides in decommissioning concrete wastes." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/14125.
Full textAbstract:
The decommissioning of nuclear power stations will lead to the production of a number of contaminated components. The materials produced will consist of process and structural wasteforms. Before this waste can be disposed it will be necessary to obtain a full inventory of those radionuclides contained in those wastes. This will be necessary to ensure that the waste is handled in a suitable manner and that full information is available so that reliable risk assessment can be carried out on the proposed disposal site. A number of radionuclides have been highlighted as significant in terms if their halflife, terrestrial mobility and predicted levels in decommissioning wastes. A selection of these radionuclides have been investigated, and methods developed for their determination in concrete. It was a requirement of this work that the methods developed were robust and that the minimum detectable amount was below that of the de minimis of O.4Bq g-1.
24
Le, Parc Samuel. "Containment during the decommissioning of nuclear power plant: calculation and approach associated." Thesis, KTH, Fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-266822.
Full text
25
LING, XIANBING. "BAYESIAN ANALYSIS FOR THE SITE-SPECIFIC DOSE MODELING IN NUCLEAR POWER PLANT DECOMMISSIONING." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010130-141644.
Full textAbstract:
Decommissioning is the process of closing down a facility. In nuclear power plant decommissioning, it must be determined that that any remaining radioactivity at a decommissioned site will not pose unacceptable risk to any member of the public after the release of the site. This is demonstrated by the use of predictive computer models for dose assessment. The objective of this thesis is to demonstrate the methodologies of site-specific dose assessment with the use of Bayesian analysis for nuclear power plant decommissioning. An actual decommissioning plant site is used as a test case for the analyses. A residential farmer scenario was used in the analysis with the two of the most common computer codes for dose assessment, i.e., DandD and RESRAD. By identifying key radionuclides and parameters of importance in dose assessment for the site conceptual model, available data on these parameters was identified (as prior information) from the existing default input data from the computer codes or the national database. The site-specific data were developed using the results of field investigations at the site, historical records at the site, regional database, and the relevant information from the literature. This new data were compared to the prior information with respect to their impacts onboth deterministic and probabilistic dose assessment. Then, the two sets of information were combined by using the method of conjugate-pair for Bayesian updating. Value of information (VOI) analysis was also performed based on the results of dose assessment for different radionuclides and parameters. The results of VOI analysis indicated that the value of site-specific information was very low regarding the decision on site release. This observation was held for both of the computer codes used. Although the value of new information was very low with regards to the decisions on site release, it was also found that the use of site-specific information is very important for the reduction of the predicted dose. This would be particularly true with the DandD code.
26
Yan, Weida. "A Study on Augmented Reality for Supporting Decommissioning Work of Nuclear Power Plants." Kyoto University, 2013. http://hdl.handle.net/2433/179338.
Full text
27
LUCIANI, FRANCESCA. "La disciplina del decommissioning degli impianti nucleari e della gestione dei rifiuti radioattivi." Doctoral thesis, Università Politecnica delle Marche, 2013. http://hdl.handle.net/11566/242567.
Full text
28
SANTOS, IVAN. "Descomissionamento de uma usina de producao de hexafluoreto de uranio." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11758.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:55:29Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:04:54Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
29
Lawal, Labaran M. "Decommissioning accountability ' expectations gap': The perceptions of stakeholders in Nigerian oil and gas industry." Thesis, University of Dundee, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493387.
Full text
30
Giovannini, Gabriele. "Wind Farm decommissioning: A perspective on regulations and cost assessment in Italy and Sweden." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-237338.
Full textAbstract:
Due to a lack of knowledge and experience the best approach to deal with wind farm decommissioning has yet to be determined. To fill this void, this paper analyzed the current status in terms of regulations and cost, regarding the decommissioning in Italy and Sweden. In order to make a comparison between these two countries, the available research papers and reports on the decommissioning cost assessment, removal methods and regulations were thoroughly investigated. Moreover, detailed estimated dismantling cost data was obtained from a wind farm in Italy. The Italian cost data were compared with data collected in Sweden and along with them, the regulations and legislations related to how these costs have to be assessed as well as what developers are required to do regarding the decommissioning in the permit issuance were included. The results of this research show that in decommissioning cost assessment both countries does not allow developers to include the possible revenues due to the scraps and to the recycling of components, although totally different methods are pursued. Some kind of security to ensure that decommissioning occurs is required, normally a bond. The bond amount is a debt investment in which an investor loans money to an entity (corporate or governmental) that borrows the funds for a defined period of time at a fixed interest rate. In Italy the bond requirements are generally high and it has to be paid completely for the permit issuance. In order to develop significant projects, this kind of approach leads to discourage small investors. On the contrary, in Sweden the current amount of 300.000 SEK per turbine according to the court precedent, the most widespread during the approval of the permit, is definitely low and represent a level playing field for every investor. Swedish regulations are also more flexible and only in the 28% of the cases studied between the years 2009 and 2012, the entire amount of the bond had to be assured before the installation. However, the malleability with regard to wind farms that do not need to provide any security, together with the low bond amount might endanger the decommissioning accomplishment.
31
Hetherington, Andrew. "Characterisation of reactor graphite to inform strategies for the disposal of reactor decommissioning waste." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4409/.
Full textAbstract:
Graphite has been used extensively in UK reactors since the 1950s. The UK nuclear decommissioning programme will result in some 90,000 tonnes of waste graphite being removed from Magnox, AGR, research reactors and plutonium production reactors. It is necessary to understand the radiological characteristics of reactor graphite as a prerequisite for decisions about its interim management as well as final disposition. There is in particular a need to improve confidence in the disposal inventory of the long-lived radionuclides carbon-14 and chlorine-36. Models have been developed to predict the distribution of principal radionuclides for Chapelcross reactor 1 and Wylfa reactor 1, and the calculated inventory compared with published experimental measurements on active samples. The models show good agreement with experimental values for carbon-14 and cobalt-60. However, for the highly mobile and volatile radionuclides chlorine-36 and tritium agreement is poor. The models provide a crude upper limit on the inventory, but certain radionuclides may be released during irradiation. For Wylfa it is predicted that all graphite waste arisings will be ILW. For Chapelcross of the order of 16% of the graphite core may be classified as LLW after the C&M period, but levels of carbon-14 rule out disposal to the LLWR facility.
32
Meinecke, Torsten Volker. "Experimental study of underwater laser cutting of steel with a view on subsea decommissioning." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=196283.
Full text
33
Di, Nicola Felice. "Decommissioning of an offshore platform as a wind turbine support by using digital twin." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Find full textAbstract:
The aim of the research project is the decommissioning of an existing oil and gas platform located in the Adriatic Sea and the re-utilization of the three-legs jacket as wind turbine support
The project consists of two main phases.
In the first phase, the existing structure, the oil and gas platform, is examined through the structural analysis using an RB-FEA software considering the in-place loads applied. Further, the fatigue analysis is performed in order to assess the resistance of the structure respect the long terms environmental actions caused by waves.
In the second phase, the top side, hence the transition piece and the deck, is decommissioned and replaced by a wind turbine using the jacket as a basement. As already done in the first phase, the resistance of the jacket is assessed through the structural analysis and the fatigue analysis
34
Jones, Charles E. Jr, and Patrick Phillips. "An Analysis of the Propose Decommissioning of the Fossil Creek Dam, Near Strawberry, Arizona." Arizona-Nevada Academy of Science, 2001. http://hdl.handle.net/10150/296566.
Full text
35
Vichi, Sara <1987>. "Monte Carlo modelling and experimental measurement methodologies to support decommissioning plans of biomedical cyclotrons." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8609/1/AMSTESIVICHI2.pdf.
Full textAbstract:
When considering the dismantling of a PET cyclotron facility, considerable amount of low level solid radioactive waste has to be characterized and disposed of. Prediction of induced radioactivity is a challenging task since the activity produced varies considerably, depending on the type of accelerator, on its use and on the specific structure of the bunker: for this reason, each facility require its specific decommissioning strategy.
This work is aimed at developing a Monte Carlo approach to a preliminary assessment of activation, to define an ad hoc decommissioning strategy and to identify possible countermeasures to be taken during the construction phase of the facility.
In this work two main cases studies were analysed: The GE PETtrace facility of the Sant’Orsola-Malpighi Hospital (Bologna) and the IBA CYCLONE 18/9 facility of Inselspital (Bern). The Monte Carlo code FLUKA was used to model accurately the two facilities for activation assessment.
Different kinds of experimental measurements were performed to evaluate MC models reliability in terms of neutron field and neutron activation.
The main long lived radionuclides founded inside the bunkers walls were 152Eu, 154Eu, 134Cs, 54Mn, 46Sc, 57Co, 65Zn and 60Co, for both facilities. The nuclides with the highest activity concentrations were 60Co and 152Eu. The total activity concentration estimated after 20 years of cyclotron operating life was up to 4.10 Bq/g and up to 3.22 Bq/g respectively in Bologna and in Bern, exceeding in both cases the radiological exemption limit of 1 Bq/g.
Monte Carlo simulation proved to be a very powerful and feasible tool in the planning of new biomedical cyclotron installations and in the definition of an optimized decommissioning strategy.
The availability of an experimentally validated Monte Carlo model makes it possible to revise the traditional approach to activation assessment.
36
Frajndlich, Roberto. "Considerações sobre o descomissionamento do reator de pesquisa IEA-R1 e futuro de suas instalações após o seu desligamento." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-09022015-101731/.
Full textAbstract:
O Reator Nuclear de Pesquisa IEA-R1 em operação desde 1957 no Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP) é um dos reatores mais antigos do mundo em operação. Em algum momento no futuro, a exemplo de outros reatores, será desligado definitivamente. Antes de chegar este momento a organização operadora precisa planejar o futuro de suas instalações e definir o destino que pretende dar aos equipamentos e materiais radioativos e não radioativos que se encontram no interior das instalações. Estas questões devem estar contidas no chamado \"Plano de Descomissionamento Preliminar da Instalação\" que é o tema deste trabalho. O trabalho apresenta inicialmente uma visão geral sobre este tema e relaciona os objetivos gerais e específicos para sua realização, descrevendo a seguir, as diretrizes que a organização operadora deve considerar para formulação de um plano de descomissionamento. A estrutura atual do setor nuclear brasileiro enfatizando principalmente as normas utilizadas no gerenciamento do rejeito radioativo é apresentada. Uma descrição dos principais equipamentos do reator IEA-R1 que constituem o seu inventário radioativo e não radioativo é apresentada. O trabalho enfatiza também a experiência adquirida pelo corpo técnico do reator com as reformas e modificações realizadas na instalação durante sua vida útil. Esta experiência pode ser de grande valia por ocasião do descomissionamento do reator no futuro. Um experimento usando o método de espectrometria gama de alta resolução e cálculo computacional através da teoria de Monte Carlo foi realizado com o objetivo de se obter uma estimativa do volume de rejeito radioativo gerado pelo desmantelamento das paredes de concreto da piscina do reator. O custo do descomissionamento em função da estratégia escolhida é determinado utilizando o código CERREX. Por fim, é realizada uma discussão sobre as diferentes estratégias consideradas. Na base destas discussões conclui-se que a estratégia mais vantajosa a ser adotada no caso deste reator é aquela que preserva o seu prédio e instalações anexas, tendo em vista o grande volume de rejeito radioativo e custos sensivelmente maiores que resultariam com o seu desmantelamento. É sugerida a preservação de parte das equipes de operação, manutenção, proteção radiológica e física da instalação e utilização do prédio do reator e anexos para divulgação da energia nuclear através de sua transformação em um museu, uma vez que este foi o primeiro reator nuclear construído no Brasil e, desde sua inauguração, tem sido utilizado como forma de divulgação da energia nuclear no país.The IEA-R1 Nuclear Research Reactor, in operation since 1957, in the Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP), is one of the oldest research reactors in the world. However at some point in time in the future, as example of the other reactors, it will be shutdown definitively. Before that time actually arrives, the operational organization needs to plan the future of its installations and define the final destination of equipment and radioactive as well as non-radioactive material contained inside the installations. These and other questions should be addressed in the so called Preliminary decommissioning plan of the installation, which is the subject of this work. The work initially presents an over view about the theme and defines the general and specific objectives describing, in succession, the directions that the operating organization should consider for the formulation of a decommissioning plan. The present structure of the Brazilian nuclear sector emphasizing principally the norms utilized in the management of radioactive waste is also presented. A description of principle equipment of the IEA-R1 reactor which constitutes its inventory of radioactive and non-radioactive material is given. The work emphasizes the experience of the reactor technicians, acquired during several reforms and modifications of the reactor installations realized during its useful life time. This experience may be of great help for the decommissioning in the future. An experiment using the high resolution gamma spectrometric method and computer calculation using Monte Carlo teory were performed with the objective of obtaining an estimate of the radioactive waste produced from dismantling of the reactor pool walls. The cost of reactor decommissioning for different choices of strategies was determined using the CERREX code. Finally, a discussion about different strategies is presented. On the basis of these discussions it is concluded that the most advantageous strategy that can be adopted in the case of this reactor is the one which preserves its building and installations, in view of the fact that a large volume of radioactive waste which will be produced and consequently a much higher costs that will result if dismantling of the reactor is decided. It is suggested that a part of the team of the technicians of reactor operation and maintenance and radiation protection services should be retained and the reactor with its building and annexes should be used for disseminating the information about the nuclear energy by transforming it in to a museum. This has been the first nuclear reactor built in Brazil and since its inauguration, has been, constantly utilized for disseminating information about the nuclear energy in the country.
37
Kiellman, Tracy Jo. "A health risk assessment for the decommissioning of the Georgia Institute of Technology Research reactor." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16698.
Full text
38
Lefevre, Baptiste. "Imaging of a nuclear reactor during its decommissioning : muography and 3D tomography for model validation." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP115.
Full textAbstract:
Cette thèse décrit les améliorations de l'analyse par imagerie muonique dans le cadre de la caractérisation du réacteur nucléaire G3 situé au CEA-Marcoule (France). En raison de la taille et de la composition du réacteur, la muographie est la seule méthode non invasive capable d'observer l'intérieur de la chambre en béton hermétique de G3. D'autres techniques, comme la tomographie par rayons X, ne sont pas suffisamment pénétrantes et présentent d'autres contraintes de déploiement, notamment radiologiques.Des muographies ont été prises sous le réacteur G3 afin d'observer ses parties internes depuis 46 points de vue différents. La collecte des données a duré un an et a utilisé 4 télescopes à muons construits au CEA/Irfu.Pour analyser ces données, de nouveaux développements ont été réalisés à plusieurs étapes de la chaîne d'analyse. Un nouveau démultiplexage a été développé pour les détecteurs de muons Micromegas, basé sur des réseaux de neurones entraînés avec des simulations de détecteurs. Les muographies obtenues ont été analysées afin d'estimer l'opacité du réacteur. Les images d'opacité ont ensuite été débruitées à l'aide d'un réseau de neurones à diffusion, ce qui a permis de réduire la durée d'acquisition.Une tomographie 3D a été calculée à partir des images d'opacité, permettant de reconstruire les parties internes du réacteur. La tomographie a subi un post-traitement par un réseau de neurones pour améliorer sa forme. Enfin, les opacités et la tomographie ont mis en évidence des différences entre le modèle du réacteur et son état actuel, principalement dans le bloc de chargement et le cœur de graphiteThis thesis describes improvements in muon imaging analysis in the scope of a characterization of the G3 nuclear reactor located at CEA-Marcoule (France). Due to the size and composition of the reactor, muography is the only non invasive method capable of observing inside G3's airtight concrete chamber. Other techniques, as X-ray tomography, are not penetrating enough and present other deployment constraints, as radiological ones.Muography images were taken under the G3 reactor in order to observe its internal parts from 46 different points of view. The data-taking lasted 1 year and used 4 muon telescopes built at CEA/Irfu.To analyze this data, new developments were made at multiple steps of the analysis pipeline. A new demultiplexing was developed for the Micromegas muon detectors, based on neural networks trained with detector simulations. The muography images obtained were analyzed in order to estimate the opacity of the reactor. The opacity images were then denoised, using a denoising diffusion neural network, which make possible to decrease the acquisition duration.A 3D tomography was computed using the opacity images and allowed reconstructing the inner parts of the reactor. The tomography underwent a post-process by a neural network to improve its shape. Finally, the opacities and the tomography highlighted differences between the reactor model and its actual status, mainly in the loading block and the graphite core
39
Metelková, Michaela. "Problematika vytváření rezerv na vyřazování jaderných zařízení." Master's thesis, Vysoká škola ekonomická v Praze, 2008. http://www.nusl.cz/ntk/nusl-11058.
Full textAbstract:
This work is focused on the issue of creation of reserves to cover the costs of decommissioning of nuclear installations. These costs arise from the need to prevent exposure to radioactivity and other pollutants that adversely affect the environment and human health. The thesis describes various systems of decommissioning of nuclear installations and the creation of reserves in selected countries - the Czech Republic, United Kingdom, Finland and France. The analytical part of the work deals with comparative analysis of the creation of reserves for decommissioning of nuclear facilities in selected countries and their subsequent evaluation. The work is a basis for optimizing the system for establishing reserves for decommissioning of nuclear facilities in the Czech Republic.
40
Ferreira, Doneivan Fernandes. "Anticipating impacts of financial assurance requirements for offshore decommissioning : a decision model for the oil industry." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287568.
Full textAbstract:
Orientador: Saul B. SuslickTese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias
Made available in DSpace on 2018-08-03T16:48:37Z (GMT). No. of bitstreams: 1 Ferreira_DoneivanFernandes_D.pdf: 10016812 bytes, checksum: 83718aff3a56b72539de08f576a25a17 (MD5) Previous issue date: 2003
Doutorado
41
VACCA, MARCO. "Gli oneri di decommissioning. Evidenze empiriche dell’informativa di bilancio e le prassi di controllo di gestione." Doctoral thesis, Università degli Studi di Cagliari, 2018. http://hdl.handle.net/11584/256001.
Full textAbstract:
The aim of this dissertation is to examine decommissioning costs from a corporate reporting as well as a management accounting perspective. Decommissioning costs are very important for companies and governments thanks to their economic, social and environmental effects. 2016 OECD report highlights that decommissioning activities are destined to grow in the future, giving rise to a considerable amount of work and creating a large and competitive market. Furthermore, these activities have a duration of several decades, involving the use of significant economic resources. This work examines the annual report of the Italian non financial companies listed on the Milan Stock Exchange in 2015 and studies the characteristics of the disclosure included in the financial statements relating the contingent liabilities of the decommissioning activities. This analysis deepens international legislation of the balance sheet’s liabilities, its objectives and its recognition and evaluation criteria. The main research method used is qualitative analysis. The work draws up indicators to quantify the information quality in order to identified best practice situations. An in-depth study of the theoretical assumptions and management control practices. An empirical case was carried out on an investment evaluation relating to decommissioning cost in order to appreciate the effects of which this erroneous quantification can lead.
This research contributes to the doctrine on financial disclosure of decommissioning cost highlighting the practice in use among corporations and the importance of certain information which, if present in financial reports, allows a considerable improvement in the quality of external information. It also shows that management control practices that are not coherent with the purposes of the discounted cash flow methodology can bring distorted financial results with negative effects on the company, on stakeholders and from an environmental prospective.
42
Nilsson, Jens, and Johan Nilsson. "Reactor disposal evaluation at Sol Voltaics." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-125478.
Full textAbstract:
The purpose of this project was to map the current method for decommissioning / disposing of the Nano-wire reactor at Sol Voltaics. Additionally, alternatives should be suggested based on the findings during the mapping processes and the subsequent analysis. The aim of the presented alternatives was to improve the current workflow for reactor decommissioning based on five identified areas; Rules and Regulations; Environmental aspects; Safety aspects; Economical aspects and Logistical aspects. The existing disposal procedure was divided into six steps. The first step involves a purging procedure to make sure no hazardous gases remain in the reactor. The second step is to dismantle and seal the reactor. The third step is to move the reactor to a loading dock. The fourth step is the transport between Active Biotech in Lund and Sydblästring AB in Malmö. The fifth step is the disassembly and cleaning process of the reactor parts, including waste management. The sixth and final step is to move the cleaned parts to SYSAV in Malmö for final disposal. Finally, Rules and Regulations as well as Safety aspects were identified as having partial improvement potential. Ideas for possible alternatives in these areas was devised and analyzed according to all five areas to make sure that the improvements in one area would not bring undesirable shortcomings in another.
43
Whitton, John. "Participant perceptions on the nature of stakeholder dialogue carried out by the UK Nuclear Decommissioning Authority (NDA)." Thesis, University of Manchester, 2010. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:213503.
Full textAbstract:
The engagement of stakeholders in a dialogue on the decommissioning of nuclear facilities and the retrieval and treatment of nuclear waste in the UK has proved challenging. The action orientated research presented here has used a mixed methodological approach to examine participants’ perceptions regarding the nature of dialogue being carried out by the NDA National Stakeholder Group (NSG), with the emancipatory aim of raising participant awareness regarding their role and the nature of the dialogue used. Exploration of the emergent theme of fairness has enabled the researcher to provide a contribution to stakeholder theory. This research adds to the theory of the deliberative institution (Reed, 2008), providing evidence for why the effective influence of stakeholders on decision making, communication about this influence, and the institutionalization of stakeholder participation is as important as the engagement itself. The work also provides an important epistemological contribution regarding the role of dialogue within the concept of social sustainability.
44
Caiafa, Alessio. "Decommissioning of a tension leg platform – possible removal options for a challenging project in the Gulf of Mexico." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
The Decommissioning is a “multidisciplinary” process by which an Oil Company goes through of deciding how best shut down the oilfield activities at the end of the field life, plugging and abandoning the well(s), making the equipment/installation safe, remove some or all the facilities (offshore structures and appurtenances e.g.: platforms, top sides, jackets etc.) and restoring the area.
Decommissioning will occur at different stages of asset lifecycle and has wide relevance in terms of reputation, so it needs to be managed properly as a dedicated business process.
Usually Oil Companies decommissioning approach is based on international Waste Hierarchy Policy (Picture 1): in other words the conceptual framework which ranks the options for dealing with waste, beginning from the reducing of their generation, listing in order of preferences, the possible approaches/actions for their management: so, re-use of the decommissioned facilities is a preferred choice to recycle and re-use in current location is preferred to re-use in new location; recycle of the decommissioned facilities is a preferred choice to disposal.
45
Grant, Ashley Stevenson. "RESTORATION OF NATIVE PLANT COMMUNITIES AFTER ROAD DECOMMISSIONING: EFFECT OF SEED MIX AND SOIL PROPERTIES ON VEGETATIVE ESTABLISHMENT." The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-05132009-123906/.
Full textAbstract:
Road decommissioning is increasingly recognized as a critical first step in the restoration of terrestrial and aquatic habitats. In the past two years alone, the United States Congress has appropriated $90 million for road removal and watershed restoration. Despite this relatively large public investment, little is known about the efficacy or ecological effects of road-removal practices. One particularly important issue is the impact of post-road-removal revegetation strategies. This study evaluated 1) short-term effects of road decommissioning on plant community composition, 2) effects of seed-mix seed origin (native vs. nonnative), species diversity, and seeding density on vegetative establishment, and 3) impact of overstory canopy and coarse woody debris on revegetation success on recently decommissioned roads. Total vegetative cover declined by 60% one-year after decommissioning, with nonnative plants showing the greatest declines (ca. 90%). Although managers often justify the use of nonnative seed mixes by the need for rapid establishment of plants on disturbed sites, we did not find significant differences in percent cover of total vegetation between plots seeded with native versus nonnative species, one year after treatment. Furthermore, cover of native species was significantly higher on plots seeded with natives compared to other treatment plots (12.3% vs. 7.8%, respectively). On treatments seeded with nonnative species, 18% of total vegetative cover was due to cover of seeded species; in comparison, seeded species accounted for 43% of total vegetative cover on native treatments. These findings suggest that native seed mixes actually may outperform nonnative ones in terms of vegetative establishment after disturbance associated with road removal.
46
King, Andrew Robert. "The analysis of ¹â°â¸'mAg, ¹â¶â¶'mHo and â¹â´Nb in decommissioning waste." Thesis, Loughborough University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418325.
Full text
47
Braidwood, David Walter. "Remediation and restoration of ocean exposed cliff-top, in the context of Dounreay (Scotland) nuclear power plant decommissioning." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237241.
Full textAbstract:
Restoration ecology continues to become ever more relevant as legislation demands we prevent biodiversity losses. Post-industrial restoration sites pose a number of additional challenges, including balancing ecological need with logistical and financial constraints. In the North of Scotland, one such site is the Dounreay Nuclear Power Plant, now undergoing decommissioning. The intention is to restore cliff-top habitat with native vegetation, blending in with its surroundings and necessitating minimal maintenance. The overall objective of this PhD research was to help develop a plan for the restoration of the site. A key challenge in this particular case was the residual low level radioactivity at depth in some areas, and a restoration layer is required to prevent contamination of bioreceptors at the surface, however, topsoil availability is limited. The cliff top site, and exposure to salt spray driven by strong winds, meant the identification of suitable vegetation communities for different areas could be crucial to its success. Vegetation and soil surveys across nine reference sites along the North coast of Scotland identified five non-peat vegetation communities suitable for Dounreay's restoration. Restoration ecology continues to become ever more relevant as legislation demands we prevent biodiversity losses. Post-industrial restoration sites pose a number of additional challenges, including balancing ecological need with logistical and financial constraints. In the North of Scotland, one such site is the Dounreay Nuclear Power Plant, now undergoing decommissioning. The intention is to restore cliff-top habitat with native vegetation, blending in with its surroundings and necessitating minimal maintenance. The overall objective of this PhD research was to help develop a plan for the restoration of the site. A key challenge in this particular case was the residual low level radioactivity at depth in some areas, and a restoration layer is required to prevent contamination of bioreceptors at the surface, however, topsoil availability is limited. The cliff top site, and exposure to salt spray driven by strong winds, meant the identification of suitable vegetation communities for different areas could be crucial to its success. Vegetation and soil surveys across nine reference sites along the North coast of Scotland identified five non-peat vegetation communities suitable for Dounreay's restoration. This prompted the development of a novel concept: that of utilising restoration sites as 'protorefuges' or 'protorefugia', i.e. restoration sites where threatened species at the leading edge of climate change can be translocated ahead of the climate changing. There, they would be joined by individuals of the wider population naturally dispersed as the climate shifts. Overall, these results enabled the development of a refined restoration plan for Dounreay, which takes into account the particular setting, constraints and timelines involved. With the decommissioning of an increasing number of nuclear sites across Britain and Europe taking place in the coming years, this research should be developed further. In particular our novel concept of protorefugia could even be put into practice, benefiting both restoration and conservation.
48
Longmire, Pamela. "Nonparametric statistical methods applied to the final status decommissioning survey of Fort St. Vrains prestressed concrete reactor vessel." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1407398430.
Full text
49
Lang, Adam. "Contamination and decontamination of steel components." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/contamination-and-decontamination-of-steel-components(32951cc3-b259-4e0b-b97e-fcc45c507bb7).html.
Full textAbstract:
Nuclear plant stainless steel can become contaminated by radionuclides during normal operation whereby the final disposition of these materials then becomes a major decommissioning challenge to address. Characterisation of the chemical and metallurgical processes that underpin contamination is essential in consideration of developing cost effective decontamination and prevention methods, as are in situ measurement techniques that allow assessment of contamination. To address these issues, contamination experiments to simulate the nitric acid-based reprocessing streams of the PUREX (Plutonium Uranium Redox Extraction) process, and alkaline spent fuel storage ponds were investigated. Solution and surface spectroscopic measurements were performed to characterise the sorption behaviour of stable analogues of two high yield fission products, Sr-90 and Cs-137, on as received and 30 % cold rolled AISI Type 304 stainless steel, respectively. In addition Laser Induced Breakdown Spectroscopy (LIBS) was also investigated as a standoff contamination assessment technique. Fission product accumulation was modelled to a second order kinetic fit that considers chemisorption, typically to a hydrous metal oxide surface, as rate controlling. This process is observed to be independent of solution composition and strain processing regime. This behaviour reflects complexation to the passivating surface chromium oxide film, and as determined by depth elemental analysis, effectively inhibits contaminant migration into the bulk material. Environment chemistry and microstructural variables that destabilise the Cr-rich passive film however reduces the passive layer capabilities to effectively inhibit fission product bulk diffusion. The importance of corrosion phenomena towards radionuclide sorption processes necessitates the consideration of metallurgical and chemical factors during the implementation of decontamination approaches to treat affected plant material at nuclear licenced sites. LIBS was found to be a satisfactory technique for measurement of Sr sorbed to steel but Cs could not be detected at the concentrations used in this experimentation. Furthermore, EDX and TOF-SIMS elemental mapping indicated ablated material may be redistributed into the crater profile during elemental analysis. This process has clear implications for the deployment of LIBS for in situ characterisation of nuclear materials as the uncontrolled redistribution of radioactive material certainly violates decommissioning principles.
50
FRAJNDLICH, ROBERTO. "Considerações sobre o descomissionamento do reator de pesquisa IEA-R1 e futuro de suas instalações após o seu desligamento." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23501.
Full textAbstract:
Submitted by Maria Eneide de Souza Araujo (mearaujo@ipen.br) on 2015-02-25T13:57:02Z
No. of bitstreams: 0Made available in DSpace on 2015-02-25T13:57:02Z (GMT). No. of bitstreams: 0
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP