Electricity generation at nuclear power plants produces a large amount of high-level radioactive waste (HLW) every year, which has long-term detrimental effects on humans and the environment. Other applications of nuclear technology (e.g., medicine, research, nuclear weapons, industry) also produce radioactive waste (e.g., low-level radioactive waste, LLW, Intermediate-level waste, ILW). The potential of deep geological repositories (DGRs) as an option for disposal of radioactive waste (HLW, ILW, LLW) has been examined in several countries, including Bulgaria, Canada, China, Finland, France, Germany, India, Japan, Russia, Spain, Sweden, Switzerland, Ukraine and the United Kingdom and are still under discussion. In Ontario, Canada, DGRs with a multi-barrier system comprised of a sedimentary rock formation (i.e., a natural barrier) and an engineered barrier system (EBS) are currently under consideration. An EBS consists of various components, such as waste containers, buffer, backfill, and tunnel sealing materials, intended to prevent the release of radionuclides. Several engineered barrier materials, including a mixture of bentonite and sand, are currently being considered for use in DGRs for nuclear waste in Ontario. Bentonite has some advantageous physical and chemical properties, such as low permeability, high plasticity, and high swelling potential, which provide it with a good sealing ability and thus make it an effective barrier. However, interaction between the compacted bentonite–sand mixture and underground water chemistry fluids (chemical factor) in the DGR could significantly alter the favourable properties of bentonite (e.g., swelling potential), thus influencing its performance when used in an EBS and eventually jeopardizing the overall safety of DGRs. In addition, other parameters, such as the clay content, initial dry density and moisture content of the compacted barrier (physical factors), as well as the presence of salts in groundwater may affect the physical and physiochemical properties of barrier materials. Moreover, during the lifetime of a DGR for used spent fuel, the bentonite–based barrier material will not only be exposed to a broad range of groundwaters with different chemical compositions, but also to high temperatures (heat generated by the nuclear wastes) (thermal factor). Thus, the interaction between the compacted bentonite–sand mixture, the surrounding groundwater and the heat from the nuclear waste material could jeopardize the favourable properties of the bentonite-based (bentonite-sand) barrier material. Properties of a bentonite-sand barrier is an important characteristic to study while designing and constructing an EBS for a DGR. Thus, to understand and assess the operations of DGRs in Ontario, comprehensive studies must be performed on engineering properties like swelling behaviour, permeability, and thermal conductivity. The goal of this research study is to experimentally investigate the physical, chemical and thermal factors that influencing the engineering properties of a barrier material made up of bentonite-sand composite used in DGRs for nuclear waste in Ontario. Compacted samples are subjected to one-dimensional free swell test to understand the swelling behaviour of the material. Hydraulic conductivity was investigated using a flexible wall permeability test. Thermal conductivity and diffusivity were tested using Decangon KD2 Pro with TR-1 and and KS-1 sensors. The specimens contain different bentonite–sand mixture ratios (20:80, 30:70, 50:50, and 70:30 dry mass), and they are tested under conditions with differing bentonite content, dry density, groundwater chemistry, and temperature. Additional tests were conducted to investigate the microstructure of the specimens. These tests include X-ray diffraction (XRD) analysis, mercury intrusion porosimetry (MIP), and thermogravimetric analyses (TG/DTG). The results reveal that the time and strain required to achieve maximum swelling of compacted bentonite–sand specimens increase with the increase of initial dry density. The simulated saline solutions of Guelph and Trenton groundwater are found to suppress the swelling of the bentonite–sand specimens. This in turn leads to the increase of hydraulic conductivity and decrease of thermal properties of the barrier material. However, the impact of the salinity is significantly reduced by increasing the dry densities and sand content of the compacted material. Moreover, the coupled effect of salinity and temperature decreases the swelling potential of the bentonite-sand mixture. Also, some transformation of Na-montmorillonite into Ca-Montmorillonite was observed. The results also indicate that some montmorillonites might have been transformed into illites, thereby further decreasing the swelling potential of the bentonite-based barrier.

Flamskyddsmedel har visat sig ha en stor påverkan på både miljö och hälsa. Den grupp flamskyddsmedel som i stor utsträckning har använts sedan slutet på 70-talet till början av 00-talet för textilier är polybromerade difenyletrar (PBDE). De är halogenerade ämnen som är svårnedbrytbara, persistenta, i vissa fall även bioackumulerande och toxcistiska. Studier har visat att dessa ämnen upptäckts i både miljö och i människokroppen. Människan exponeras av dessa ämnen, framförallt genom damm och livsmedel. I synnerhet feta fiskar eftersom PBDE drar sig till organismer och fettvävnader. I takt med att brandkraven i många länder ökar är behovet av ett substitut för bromerade flamskyddsmedel stort. Flera typer av PBDE är idag förbjudna i Europa men problemet kvarstår då det fortfarande existerar i importerade produkter. För att komma ifrån flamskyddsmedel i lös inredning, exempelvis soffor och madrasser skulle ett barriärmaterial innehållande naturligt flamskyddade material vara ett bra substitut.   För lös inredning är det viktigt med komfort, det fanns i studien ett intresse av att se hur naturligt flamskyddat material tillsammans med ull betedde sig vid en flamspridning. Ull i sig har en hög komfort och har ett naturligt flamskydd på grund av sitt höga LOI. För att uppnå ett resultat på vilken FR-fiber som skulle studeras vidare tillsammans med ull, har flamtester på Kevlar, Nomex, Protex och Flamestop utförts. De är uppbyggda med olika typer av naturligt flamskydd i form av aramider, modakryl och fosfor behandlad viskos.   Med resultatet från flamtesterna utfördes vidare tester och analyser på tre kombinationer av Flamestop/Ull, innehållande tre olika procentsatser. Testmetoder i form av antändning och flamspridning har utförts på de olika kombinationerna, för att göra det möjligt att analysera om hur de flamskyddade materialet uppförde sig tillsammans med ull. Samt om det gjorde någon skillnad vilken procentandel Flamestop kombinationen innehöll.   Resultatet av testmetod för antändning på tre spridda procentandelar Flamestop/Ull som erhölls, var att en högre procentandel Flamestop gentemot ull gjorde det möjligt för materialet av självslockna i ett tidigt stadie. I flamspridningstestet visade det sig att procentandelarna inte gjorde någon skillnad för spridningens framfart. Det gick att utläsa av testerna att proverna med flamskydd i vinkelrät riktning mot flammans riktning bildade ett skyddande skikt av förkolnad fosfor från Flamestop. Flamman och Flamestop i längsgående riktning resulterade i större skada på materialet. För att göra det möjligt att undersöka mer om riktningen på det flamskyddade materialet hade det varit intressant att studera flamspridningen med materialet i både väft och varp. / Flame-retardants have a great impact on the environment and health. Polybrominated diphenyl ethers (PBDE) are the group of flame-retardants that mainly has been used since its entrance in the late 70s until the early 00s. PBDEs consist of Organobromine compounds, different types of halogenated compounds, which are highly resistant to degradation, persistent and in some cases even bioaccumulative and toxic. It has been ensured in previously studies that PBDEs has been found in the human body and in the environment. Humans are exposed every day to these pollutants through dust, food and especially from fatty fishes, as living organisms and fatty tissues are easily attracted to PBDE. A lot of the existing PBDE are forbidden in Europe; however, the issue still exist as imported products can contain PBDE. As the fire safety regulations in many countries increases, it is necessary to find a substitute for flame-retardants. To lessen or completely remove flame-retardants in loose interiors, as couches and mattresses a barrier-material could be a good substitute.   Comfort is an important component for loose interiors; in this study there was an interest to see how a material with inherent natural flame resistance behaved with wool. Wool, that has a good comfort and a natural resistance of flame, due to its high LOI. To decide which FR-fibre that will be looked into and analysed in this essay an ignition test on Kevlar, Nomex, Protex and Flamestop were made. These materials have different structures of flame resistance, in form of aramids, modacrylic and phosphorus viscose.   Three different percentages of Flamestop/Wool were created from the results of the previous mentioned ignition test. These three percentages were weaved into a plain weave, tested and analysed. Ignition and flame spread were tested on the weaves, analysed to see how the natural flame resistant material behaved together with wool and if there were any differences when comparing the different test specimens.   The result of the ignition and flame spread tests showed that the percentages of Flamestop played a role in the ignition test; the ability to extinguish was greater with a higher percentage of Flamestop in the weave. It was not possible to see a difference in the test of flame spreading. The test specimens with the FR-fibre perpendicular to the flames direction showed a better result than the test specimens with the FR-fibre in a longitudinal direction to the flame. It would be of interest to study weaves with FR-fibres in both directions of warp and weft.