In the Swedish concept for final disposal of spent nuclear fuel, referred to as KBS-3, a three-layered protection system is used. The system consists of a copper canister holding the spent nuclear fuel deposited 500 meters in a repository built in groundwater saturated granitic rock. The copper canisters are placed in deposition holes, buffered and backfilled by bentonite clay. One of the challenges associated with this system is the long-term exposure of the engineered barriers i.e. the canister including the spent fuel and the cast iron insert as well as the bentonite buffer to ionizing radiation. The possible effects of radiation on the materials in the engineered barriers have been studied not only by the Swedish Nuclear Fuel and Waste Co (SKB), but also by academia nationally and internationally. In this work, literature studies have been carried out to investigate whether all possible/potential effects of ionizing radiation from the spent nuclear fuel on the engineered barriers have been considered by SKB. Apart from a general summary of the relevant issues in chapter one, regions within the KBS-3 design where enhanced radiation may occur have been identified and the related radiation induced processes have been summarized in chapter two. These issues include effects of water-radiolysis on the spent fuel, the cast-iron insert and other ferrous materials, the copper shell and the bentonite buffer. Three types of possible damages have been identified: the microstructural defects in the ferrous materials by direct radiation, the radiation-induced microstructural alterations of the spent fuel and the bentonite and radiation-induced oxidation i.e. dissolution of the fuel and corrosion of the ferrous metals and the copper. The relevant SKB documents have been identified (in chapter 3) to be the SR-Site main report, the underlying Process reports and reports of FUD-programs. Apart from these documents, other SKB technical reports and open literature are used as basis for assessing whether all the issues mentioned in chapter two of this study have been considered by SKB.  According to the assessment, most of the significant issues mentioned in chapter two have been mentioned and discussed in the identified SKB documents. In the main safety assessment, i.e. the SR-Site project, the significance of most of the radiation processes has been based on dose levels expected at the different regions within the KBS-3 design. Irrespective of the assessments in SR-Site though, the current understanding of the relevant issues and plans for future research efforts summarized in FUD-programs reflect the research developments. However, the recent developments in understanding of radiation-induced effects on montmorillonite and the corrosion of copper in argon atmosphere need to be given due importance in coming FUD-programs. A separate investigation of radiation effects on FSW-joints may contribute to removal of the remaining uncertainties. In addition, mechanism involved in radiation-induced fuel dissolution and copper corrosion may require more research efforts than those planned. / Det svenska konceptet för slutförvar av använt kärnbränsle, KBS-3, består av tre barriärer som är tänkt att skydda omgivningen mot joniserande strålning från använt kärnbränsle. Systemet består av specialtillverkade kopparkapslar som innehåller det använda kärnbränslet. Kapslarna förvaras i deponeringshål 500 meter ner i berggrunden och är inneslutna i bentonitlera. En av frågeställningarna associerade med djupt geologiskt förvar av kärnbränsle är hur de konstruerade barriärna, alltså kopparhöljen som omsluter gjutjärninsatsen och det använda kärnbränslet samt bentonitleran, kan påverkas av joniserande strålning från det använda kärnbränslet. Möjliga strålningseffekter på de skyddande barriärna har studerats nationellt och internationellt. Syftet med denna studie var att utvärdera huruvida SKB har i sina säkerhetsanalyser av slutförvaret tagit tillräcklig hänsyn till effekter av joniserande strålning på de konstruerade barriärna. Studien består av tre kapitel där kapitel 1 utgör en generell sammanfattning av frågeställningar kopplade till KBS-3 barriärer. I kapitel 2 har områden i och omkring de konstruerade barriärna där joniserande strålning från använt kärnbränsle kan förekomma identifierats och möjliga strålningsinducerade processer i dessa områden sammanfattats. Tre typer av möjliga strålningsinducerade skador har identifierats: 1) strålningsinducerade mikrostrukturella defekter i metaller som förekommer i systemet, 2) strålningsinducerade mikrostrukturella förändringar i använt kärnbränsle och i bentonitleran samt 3) strålningsinducerad oxidation, dvs. upplösning av det använda kärnbränslet och korrosion av metaller som förekommer i systemet. SKB-dokumenten som identifierats (i kapital 3) som relevanta för utvärderingen i denna studie är följande: Säkerhetsanalysen (SR-Site), tekniska rapporter som ligger till grund för SR-Site och FUD-programmen. Enligt bedömningen i denna studie har SKB tagit hänsyn till de flesta relevanta frågeställningarna kopplade till strålningsinducerade effekterna på de konstruerade barriärna. I SR-Site har de flesta bedömningar relaterade till och om signifikansen hos de strålningsinducerade processerna baserats på doser och dosrater som förväntas förekomma i och omkring de konstruerade barriärna. Oavsett bedömningarna i SR-Site har dock de mest relevanta frågeställningarna tagits upp i FUD-programmen och framtida forskningsinsatser i enlighet med det som av SKB har uttryckts som behov av en utökad processförståelse. Dessa frågeställningar reflekterar väl de mest signifikanta utvecklingarna som rapporterats i öppna vetenskapliga studier om strålningsinducerade processer som kan förekomma i ett djupt geologiskt förvar för använt kärnbränsle. De senaste rapporterade observationerna om strålningseffekter på montmorillonit och kopperkorrosion i argonatmosfär måste dock tas upp och diskuteras i de kommande FUD-programmen. Separata studier av strålningseffekter på koppardelar som har behandlats med FSW-teknik rekommenderas. För att uppnå en bättre och djupare förståelse för de förekommande mekanismerna i strålningsinducerad upplösning av använt kärnbränsle krävs sannolikt mera forskningsinsatser än de planerade.

This dissertation presents a computational multiscale framework for predicting behavioral tendencies related to human addiction. The research encompasses three main contributions. The first contribution presents a formal, heuristic, and exploratory framework to conduct interdisciplinary investigations about the neuropsychological, cognitive, behavioral, and recovery constituents of addiction. The second contribution proposes a computational framework to account for real-life recoveries that are not dependent on pharmaceutical, clinical, and counseling support. This exploration relies upon a combination of current biological beliefs together with unorthodox rehabilitation practices, such as meditation, and proposes a conjecture regarding possible cognitive mechanisms involved in the recovery process. Further elaboration of this investigation leads on to the third contribution, which introduces a computational hypothesis for exploring the allostatic theory of addiction. A person engaging in drug consumption is likely to encounter mood deterioration and eventually to suffer the loss of a reasonable functional state (e.g., experience depression). The allostatic theory describes how the consumption of abusive substances modifies the brain's reward system by means of two mechanisms which aim to viably maintain the functional state of an addict. The first mechanism is initiated in the reward system itself, whereas the second might originate in the endocrine system or elsewhere. The proposed computational hypothesis indicates that the first mechanism can explain the functional stabilization of the addict, whereas the second mechanism is a candidate for a source of possible recovery. The formal arguments presented in this dissertation are illustrated by simulations which delineate archetypal patterns of human behavior toward drug consumption: escalation of use and influence of conventional and alternative rehabilitation treatments. Results obtained from this computational framework encourage an integrative approach to drug rehabilitation therapies which combine conventional therapies with alternative practices to achieve higher rates of consumption cessation and lower rates of relapse.

This work modifies Shamir’s algorithm by sharing a random key that is used to lock up the secret data; as against sharing the data itself. This is significant in cloud computing, especially with homomorphic encryption. Using web design, the resultant scheme practically globalises secret sharing with authentications and inherent secondary applications. The work aims at improving cybersecurity via a joint exploitation of human factors and technology; a human-centred cybersecurity design as opposed to technology-centred. The completed functional scheme is tagged CDRSAS. The literature on secret sharing schemes is reviewed together with the concepts of human factors, trust, cyberspace/cryptology and an analysis on a 3-factor security assessment process. This is followed by the relevance of passwords within the context of human factors. The main research design/implementation and system performance are analysed, together with a proposal for a new antidote against 419 fraudsters. Two twin equations were invented in the investigation process; a pair each for secret sharing and a risk-centred security assessment technique. The building blocks/software used for the CDRSAS include Shamir’s algorithm, MD5, HTML5, PHP, Java, Servlets, JSP, Javascript, MySQL, JQuery, CSS, MATLAB, MS Excel, MS Visio, and Photoshop. The codes are developed in Eclipse IDE, and the Java-based system runs on Tomcat and Apache, using XAMPP Server. Its code units have passed JUnit tests. The system compares favourably with SSSS. Defeating socio-cryptanalysis in cyberspace requires strategies that are centred on human trust, trust-related human attributes, and technology. The PhD research is completed but there is scope for future work. / Petroleum Technology Development Fund (PTDF), Abuja, Nigeria.

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Background: Rewriting the approach to automotive software development, AU-TOSAR introduces a standardized structure that enhances adaptability, facilitatescollaboration among multiple stakeholders, and optimizes the development process. However, the complexity introduced by AUTOSAR's modular structure also presentschallenges, particularly in understanding the evolution of the software over time. Asautomotive software projects evolve, tracking changes in software repositories basedon AUTOSAR becomes crucial for comprehending the impact on various systemfeatures and ensuring the overall integrity of the software. In response to these chal-lenges, there is a need to provide a systematic and efficient technique for analyzingthe evolution of the software based on AUTOSAR, offering insights into code modi-fications, and their impact on both software and repository evolution. Objectives: The primary objective of this thesis is to develop and evaluate AR-MINE, a specialized tool for automating the mining of software repositories basedon AUTOSAR. By doing so, the thesis aims to provide a comprehensive solution forunderstanding the evolution of automotive software built on the AUTOSAR archi-tecture. Methods: The research employs a design science research methodology, involv-ing the design, development, and evaluation of the AR-MINE tool. The iterativeprocess includes understanding the challenges faced in software repository miningbuilt on AUTOSAR architecture, designing a solution to address these challenges, implementing the tool, and evaluating its effectiveness in a real-world context. Results: The results of this research showcase the effectiveness and utility of AR-MINE in understanding evolution of software built upon AUTOSAR and how it could potentially benefit various people involved in the software development life-cycle. The feedback survey provided valuable insights into the tool's usefulness andfeasibility. Conclusions: The findings and insights derived from the development and eval-uation of AR-MINE, showcase the challenges and opportunities in understandingthe evolution of automotive software built upon the AUTOSAR architecture. By analyzing ARXML files and offering an intuitive interface, the tool could be an ef-fective sidekick in reducing the complexities involved in understanding the softwarebased on AUTOSAR. The tool's industrial validation confirmed its capabilities andpracticality, making the tool a valuable asset. Enhancing AR-MINE by adding morefeatures that are relevant and applicable to a much larger scale and improving itsefficiency by incorporating third party plugins in extracting and analyzing data fromsoftware repositories, are key steps towards its refinement.

The objective of this project was the study of basic interaction processes in the systems actinide - clay organics - aquifer and actinide - natural clay - clay organics - aquifer. Thus, complexation, redox, sorption and diffusion studies were performed. To evaluate the influence of nitrogen, phosphorus and sulfur containing functional groups of humic acid (HA) on the complexation of actinides in comparison to carboxylic groups, the Am(III) and U(VI) complexation by model ligands was studied by UV-Vis spectroscopy and TRLFS. The results show that Am(III) is mainly coordinated via carboxylic groups, however, probably stabilized by nitrogen groups. The U(VI) complexation is dominated by carboxylic groups, whereas nitrogen and sulfur containing groups play a minor role. Phosphorus containing groups may contribute to the U(VI) complexation by HA, however, due to their low concentration in HA they play only a subordinate role compared to carboxylic groups. Applying synthetic HA with varying sulfur contents (0 to 6.9 wt.%), the role of sulfur functionalities of HA for the U(VI) complexation and Np(V) reduction was studied. The results have shown that sulfur functionalities can be involved in U(VI) humate complexation and act as redox-active sites in HA for the Np(V) reduction. However, due to the low content of sulfur in natural HA, its influence is less pronounced. In the presence of carbonate, the U(VI) complexation by HA was studied in the alkaline pH range by means of cryo-TRLFS (-120°C) and ATR FT-IR spectroscopy. The formation of the ternary UO2(CO3)2HA(II)4− complex was detected. The complex formation constant was determined with log β0.1 M = 24.57 ± 0.17. For aqueous U(VI) citrate and oxalate species, luminescence emission properties were determined by cryo-TRLFS and used to determine stability constants. The existing data base could be validated. The U(VI) complexation by lactate, studied in the temperature range 7 to 65°C, was found to be endothermic and entropy-driven. In contrast, the complex stability constants determined for U(VI) humate complexation at 20 and 40°C are comparable, however, decrease at 60°C. For aqueous U(IV) citrate, succinate, mandelate and glycolate species stability constants were determined. These ligands, especially citrate, increase solubility and mobility of U(IV) in solution due to complexation. The U(VI) sorption onto crushed Opalinus Clay (OPA, Mont Terri, Switzerland) was studied in the absence and presence of HA or low molecular weight organic acids, in dependence on temperature and CO2 presence using OPA pore water as background electrolyte. Distribution coefficients (Kd) were determined for the sorption of U(VI) and HA onto OPA with (0.0222 ± 0.0004) m3/kg and (0.129 ± 0.006) m3/kg, respectively. The U(VI) sorption is not influenced by HA (50 mg/L), however, decreased by low molecular weight organic acids (> 1×10-5 M), especially by citrate and tartrate. With increasing temperature, the U(VI) sorption increases both in the absence and in the presence of clay organics. The U(VI) diffusion in compacted OPA is not influenced by HA at 25 and 60°C. Predictions of the U(VI) diffusion show that an increase of the temperature to 60°C does not accelerate the migration of U(VI). With regard to uranium-containing waste, it is concluded that OPA is suitable as host rock for a future nuclear waste repository since OPA has a good retardation potential for U(VI).

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It is a generally agreed internationally that high level nuclear wastes containing long-lived radioactive wastes should be disposed in deep and stable geological formations that are 500-1000 m below ground level. Deep geological disposal is based on the concept of multiple barriers to prevent deep ground-waters, present in almost all rock formations, from rapidly leaching the wastes and transporting radioactivity away from the repository. The multiple barrier system comprises of ‘engineered barriers’ that are constructed in the repository and ‘natural barriers’ in the surrounding geological environment. The engineered barrier components comprise of the vitrified solid waste, canister (to contain the vitrified waste), and a buffer or backfill material (clay or cement) that fills the annular space between the canister and the walls of the hole drilled in the floor of host-rock. The natural barrier is provided by the rocks and soils between the repository and earth’s surface. The canisters containing the hig level waste (HLW) upon placement in DGR need protection against tectonic activities and chemical attack by dissolved elements and from microbes. Densely compacted bentonite is identified suitable for this purpose owing to its large swell potential, low permeability, sufficient bearing capacity and high cation adsorption capacity. In the deep geological repository (DGR) for disposal of high level nuclear wastes, iodine-129 is one of the significant nuclides, owing to its long half-life (half life = 16 million years) and tendency to easily migrate out of the geological repository into the biosphere caused by its high solubility and poor sorption onto most geologic media. Bentonite buffer by virtue of negatively charged basal surface has negligible affinity for retention of iodide anions. Attempts have been made to improve the iodide retention capacity of bentonite by treating the clay with cationic polymers, this however occurs at the cost of reduced swelling ability of bentonite clay. The compacted bentonite employed in deep geological repositories must possess large swell potential to enable it to close fissures and cracks that form on drying of the expansive clay by the heat arising from the high level nuclear waste and thereby close pathways for migration of radionuclides (from breached canister) to the geo-environment. Therefore, it becomes important to identify an additive that enhances the iodide retention ability of the mix without significantly impairing its swelling ability. Based on the strong affinity of silver for iodide ions, the feasibility of mixing silver-kaolinite (termed AgK) clay with bentonite to improve the latter’s iodide sorption capacity and the impact of mixing AgK clay with bentonite on swelling ability of the mix forms one of the the focus of this thesis. Silver-kaolinite clay was prepared by heating 80% kaolinite + 20% silver nitrate mix at 400°C for 30 min, followed by washing (to remove unreacted silver nitrate) and oven-drying the resultant AgK clay. Physical mixing of AgK and bentonite was considered a viable proposition as small additions (10% to 20% on dry mass basis) besides imparting iodide sorption ability was expected to have minor influence on the swelling ability of the mix. As organo-bentonites are known to retain iodide ions, it was considered relevant to compare the iodide removal behaviour of AgK and organo¬bentonite clay. Hexadecylpyridinium-bentonite (termed as HDPy+B) is the organo¬bentonite examined in this thesis and is prepared by treating bentonite with hexadecylpyridinium chloride mono hydrate salt (C21H38ClN.H2O; molecular weight = 358.01). The hexadecylpyridinium chloride mono hydrate salt is a cationic quaternary ammonium compound and has been used by earlier researchers to prepare organo-bentonite for removal of iodide ions from aqueous solutions. The impact of mixing AgK and HDPy+B clays on the iodide retention and swelling behaviour of bentonite is also considered in the thesis. The mass-balance calculations, XRD analysis, X-ray photon emission survey spectrum and EPMA tests performed on kaolinite-silver nitrate mix/AgK/kaolinite specimen indicated that silver occurs as uniform coatings of AgO/Ag2O on kaolinite surface of the AgK specimen. The AgK clay has strong affinity for iodide ions reflected by the large distribution coefficients (Kd) values of 1367 and 293 mL/g at initial iodide concentrations of 750 mg/L and 1000 mg/L. Further, the sorption process was rapid, unaffected by the presence of co-ions, elevated temperature of sorption and was practically irreversible at range of pH conditions. The iodide retention by AgK is attributed to occurrence of hydrolysis and exchange reactions. On contacting the AgK with water, the AgO species hydrolyze to form AgOH; iodide ions are retained by replacing the hydroxyl group of AgOH leading to formation of AgI phase. The adsorption of HDPy+Cl- ions by bentonite occurs by replacement of the native exchangeable cations by HDPy+ ions and adsorption by van der Waals interactions between the organic cations and the clay surface. The adsorbed cationic polymer neutralize the negative charge of the clay surface. Zeta potential measurements of HDPy+B specimen indicated that adsorption of cationic polymer transforms the negatively charged clay particles into positively charged particles that favour anion adsorption. Sorption of iodide ions by HDPy+B specimen exhibits two distinct segments: 1) the iodide sorption increased rapidly at lower iodide concentration (91 mg/L to 475 mg/L) and are retained by Coulombic adsorption to the cationic groups contained in the loops and tails of the adsorbed polymer (primary adsorption sites) and 2) the relatively slower adsorption at higher iodide concentrations (larger than 475 mg/L) is attributed to exchange with chloride ions attached to HDPy+Cl-ion pair (secondary adsorption sites). The Kd values for iodide adsorption vary from 15 mL/g to 184 mL/g at initial iodide concentrations of 91 mg/L to 996 mg/L respectively. Comparing the iodide removal efficiencies of AgK and HDPy+B specimens revealed that the AgK clay exhibited larger iodide removal; further while the iodide removal by AgK specimen was almost instantaneous (complete in < 5 min), iodide removal by HDPy+B specimen was a slow process (18-24 h is needed to attain equilibrium). Likewise, the iodide retention capacity of the 50%B-50%HDPy+B mix (B = bentonite) is substantially smaller than of the 90%B-10%AgK and 80%B¬20%AgK mixes. Cation exchange capacity (CEC) measurements brought out that mixing AgK with bentonite besides imparting an iodide retention capacity essentially retains the large cation exchange capacity of the expansive clay. On the other hand mixing HDPy+B with bentonite imparts a smaller iodide retention capacity to the mix and leads to a notable reduction in the CEC of the expansive clay. Results of oedometer swell tests brought out that dilution of bentonite with 10% and 20% AgK specimen does not impact its swell potential and leads to some (10%) reduction in swell pressure, while dilution with 50% HDPy+B clay leads to notable (58%) reduction in swell potential and swell pressure (21%) underlining the superiority of AgK specimen as additive to bentonite in deep geological repositories. The swell pressure of the compacted 50%B-50%HDPy+B mix is 21% lower than that of the compacted bentonite specimen. Comparatively, dilution of bentonite with 10% and 20% AgK specimen induces 8-10% lower swell pressure in comparison to the undiluted counterpart. Swell pressure results of compacted 80%B-20%HDPy+B mix is not considered as this mix was unable to retain iodide ions. Superposing the field 129I concentration levels on I removal efficiency indicate that use of 90%B-10%AgK mix would suffice to provide 100% iodide removal efficiency and ensure that the swelling characteristics of bentonite is least affected by dilution.