The probabilistic risk analysis of external hazards of an interim storage for spent nuclear fuel

Tässä diplomityössä tehtiin Olkiluodon ydinvoimalaitoksella sijaitsevan käytetyn ydinpolttoaineen allasvarastointiin perustuvan välivaraston todennäköisyysperustainen ulkoisten uhkien riskianalyysi. Todennäköisyysperustainen riskianalyysi (PRA) on yleisesti käytetty riskien tunnistus- ja lähestymistapa ydinvoimalaitoksella. Työn tarkoituksena oli laatia täysin uusi ulkoisten uhkien PRA-analyysi, koska Suomessa ei ole aiemmin tehty vastaavanlaisia tämän tutkimusalueen riskitarkasteluja. Riskitarkastelun motiivina ovat myös maailmalla tapahtuneiden luonnonkatastrofien vuoksi korostunut ulkoisten uhkien rooli käytetyn ydinpolttoaineen välivarastoinnin turvallisuudessa. PRA analyysin rakenne pohjautui tutkimuksen alussa luotuun metodologiaan. Analyysi perustuu mahdollisten ulkoisten uhkien tunnistamiseen pois lukien ihmisen aikaansaamat tahalliset vahingot. Tunnistettujen ulkoisten uhkien esiintymistaajuuksien ja vahingoittamispotentiaalin perusteella ulkoiset uhat joko karsittiin pois tutkimuksessa määriteltyjen karsintakriteerien avulla tai analysoitiin tarkemmin. Tutkimustulosten perusteella voitiin todeta, että tiedot hyvin harvoin tapahtuvista ulkoisista uhista ovat epätäydellisiä. Suurinta osaa näistä hyvin harvoin tapahtuvista ulkoisista uhista ei ole koskaan esiintynyt eikä todennäköisesti koskaan tule esiintymään Olkiluodon vaikutusalueella tai edes Suomessa. Esimerkiksi salaman iskujen ja öljyaltistuksen roolit ja vaikutukset erilaisten komponenttien käytettävyyteen ovat epävarmasti tunnettuja. Tutkimuksen tuloksia voidaan pitää kokonaisuudessaan merkittävinä, koska niiden perusteella voidaan osoittaa ne ulkoiset uhat, joiden vaikutuksia olisi syytä tutkia tarkemmin. Yksityiskohtaisempi tietoisuus hyvin harvoin esiintyvistä ulkoisista uhista tarkentaisi alkutapahtumataajuuksien estimaatteja.

Spin-Dynamics in Cold Gases of 87Rb and Atomic Hydrogen. The spins they are a-changin’

In this thesis the dynamics of cold gaseous atoms is studied. Two different atomic species and two different experimental techniques have been used. In the first part of the thesis experiments with Bose-Einstein condensates of Rb-87 are presented. In these experiments the methods of laser cooling and magnetic trapping of atoms were utilized. An atom chip was used as the experimental technique for implementation of magnetic trapping. The atom chip is a small integrated instrument allowing accurate and detailed manipulation of the atoms. The experiments with Rb-87 probed the behaviour of a falling beam of atoms outcoupled from the Bose-Einstein condensate by electromagnetic field induced spin flips. In the experiments a correspondence between the phases of the outcoupling radio frequency field and the falling beam of atoms was found. In the second part of the thesis experiments of spin dynamics in cold atomic hydrogen gas are discussed. The experiments with atomic hydrogen are conducted in a cryostat using a dilution refrigerator as the cooling method. These experiments concentrated on explaining and quantifying modulations in the electron spin resonance spectra of doubly polarized atomic hydrogen. The modifications to the previous experimental setup are described and the observation of electron spin waves is presented. The observed spin wave modes were caused by the identical spin rotation effect. These modes have a strong dependence on the spatial profile of the polarizing magnetic field. We also demonstrated confinement of these modes in regions of strong magnetic field and manipulated their spatial distribution by changing the position of the field maximum.

Evaluation of skin sensitivity in dogs bearing allergic dermatitis to standardized allergenic extract of house dust and storage mites

The objective of the study was to evaluate whether allergenic extracts of five house dust and storage mite species standardized for humans might be used for the diagnosis of canine atopic dermatitis (CAD). Extracts of Dermatophagoides pteronyssinus (Pyroglyphidae), D. farinae (Pyroglyphidae), Blomia tropicalis (Glycyphagidae), Lepidoglyphus destructor (Glycyphagidae) and Tyrophagus putrescentiae (Acaridae) were evaluated by intradermal testing in 20 healthy dogs (control) and 25 dogs with allergic dermatitis. A significant difference in the response was observed between the two groups (p<0.05). Only one dog (5%) in the control group reacted to the intradermal test, whereas 14 dogs (56%) in the allergic group were positive for at least one extract (odds ratio = 24.2). Most of the positive reactions observed in the allergic group occurred against the extracts of T. putrescentiae or L. destructor, each inducing reactions in 10 dogs (40%). D. farinae, D. pteronyssinus e B. tropicalis extracts induced reactions in 7 (28%), 3 (12%) and 3 (12%) dogs, respectively. The allergenic extracts standardized for humans evaluated in the present study may be used as a tool to complement the diagnosis of the disease, as well as to select potential allergen candidates for allergen-specific immunotherapy.

Histochemical study of the oviducal gland and analysis of the sperm storage tubules of Mustelus schmitti Springer, 1939 (Chondrichthyes, Triakidae)

Abstract: The paired oviducal glands of immature and mature females of Mustelus schmitti were examined macro and microscopically. Findings indicate that these glands possessed the same zonation as in most chondrichthyans from anterior to posterior: club, papillary, baffle and terminal zones. The whole gland is composed by simple tubular glands that connect with transverse grooves all along the organ. The club zone presents a typical indian club shape with a simple columnar and ciliated epithelium including secretory cells PAS (+) and AB (+). The papillary zone is characterized by lamella forming small and long cones in numbers of three. The epithelium of this zone contains ciliated cells with apical nuclei and secretory cells with basal nuclei that stain AB (+)The baffle zone consists of apically flattened lamellae alternating with spinnerets which are small projections disposed by both sides of the plateau. This whole structure is present in number of 8 or 9 units. A simple columnar ciliated epithelium covers the plateau and spinnerets and no AB or PAS staining is observed. The epithelium of the terminal zone is PAS (-) and AB (+), and elongated tubules, that run adjacent to the baffle zone are the site where groups of spermatozoa are clearly observed in the lumen. The epithelium of the sperm storage tubules do not stain with any of the dyes tested. Sperm was also observed in the baffle zone, presumably in its way to the fecundation in the oviduct because it displays no aggregation pattern and was between the folds of the epithelium. By scanning electron microscopy sperm was observed in the club and baffle zones in a gland which belonged to a pregnant female.

Parameter optimization of AC rectangular wave outputs for aluminum cold wire GTAW

The objective of this work was to optimize the parameter setup for GTAW of aluminum using an AC rectangular wave output and continuous feeding. A series of welds was carried-out in an industrial joint, with variation of the negative and positive current amplitude, the negative and positive duration time, the travel speed and the feeding speed. Another series was carried out to investigate the isolate effect of the negative duration time and travel speed. Bead geometry aspects were assessed, such as reinforcement, penetration, incomplete fusion and joint wall bridging. The results showed that currents at both polarities are remarkably more significant than the respective duration times. It was also shown that there is a straight relationship between welding speed and feeding speed and this relationship must be followed for obtaining sound beads. A very short positive duration time is enough for arc stability achievement and when the negative duration time is longer than 5 ms its effect on geometry appears. The possibility of optimizing the parameter selection, despite the high inter-correlation amongst them, was demonstrate through a computer program. An approach to reduce the number of variables in this process is also presented.

Application of the finite element method in cold forging processes

The demand for more efficient manufacturing processes has been increasing in the last few years. The cold forging process is presented as a possible solution, because it allows the production of parts with a good surface finish and with good mechanical properties. Nevertheless, the cold forming sequence design is very empirical and it is based on the designer experience. The computational modeling of each forming process stage by the finite element method can make the sequence design faster and more efficient, decreasing the use of conventional "trial and error" methods. In this study, the application of a commercial general finite element software - ANSYS - has been applied to model a forming operation. Models have been developed to simulate the ring compression test and to simulate a basic forming operation (upsetting) that is applied in most of the cold forging parts sequences. The simulated upsetting operation is one stage of the automotive starter parts manufacturing process. Experiments have been done to obtain the stress-strain material curve, the material flow during the simulated stage, and the required forming force. These experiments provided results used as numerical model input data and as validation of model results. The comparison between experiments and numerical results confirms the developed methodology potential on die filling prediction.

Use of fiber-reinforced composite framework and thermochromic pigment in maxillofacial prostheses

The purpose of this investigation was to evaluate the possibility to enhance certain qualities of facial prostheses. Polymethyl methacrylate is still being used as base mate¬rial or clip carrier material, but it is hard and heavy, and debonding of the silicone from the acrylic base material is a frequent problem. This thesis aims to evaluate the use of fiber-reinforced composite (FRC) as framework material for maxillofacial silicone prostheses. FRC has been used as reinforcement in removable and fixed partial dentures since the 1990s. This material is lightweight and can be fabricated to compress the margins of the prosthesis slightly, to keep it tightly against the skin during jaw movements and facial expressions. Additionally, the use of a thermochromic pigment, colorless in room temperature and red in a cold environment, was studied in order to evaluate the possibility of using this color changing pigment in facial prostheses to mimic the color change of facial skin in cold weather. The tensile bond strength between pre-impregnated, unidirectional FRC and maxillofacial silicone elastomer was studied. Three different bonding agents or primers were compared. Bond strength was improved by one of the primers and by roughening the surface. The effect of a skin compressing glass fiber-reinforced composite framework on facial skin blood flow was studied by using a face mask, constructed with a compression pad corresponding to the outer margin of a glass fiber-reinforced framework beam of a facial prosthesis. The skin blood flow of ten healthy volunteers, aged 23-25 years, was measured during touch, light, and moderate compression of the skin, by using laser Doppler imaging technique. None of the compressions showed any marked effects on local skin blood flow. There were no significant differences between blood flow during compression and at baseline. Maxillofacial silicone elastomer was colored intrinsically with conventional color pigments: a control group containing only conventional pigments was compared to two test groups with 0.2 wt% and 0.6 wt% thermochromic pigment added. The color of the material was measured with a spectrophotometer in room temperature and after storage in a freezer. The color stability of the maxillofacial silicone elastomer colored with thermo¬chromic pigment was evaluated by artificial aging. The color dif¬ference of the L* (lightness) and a* values (redness), comparing color after the samples were stored at room temperature and in a freezer (-19°C), was statistically significant for both 0.2 wt% and 0.6 wt% thermo¬chromic pigment groups. The differences in the b* values (yellowness) were statistically significant for the 0.6 wt% group. Exposure to ultraviolet (UV) radiation led to visually noticeable and statistically signifi¬cant color changes (ΔE) in all color values in both test groups. The specimens containing thermochromic pigment were very sensitive to UV radiation. In conclusion, a framework of fiber-reinforced composite can successfully be bonded to maxillofacial silicone elastomer, and a framework beam, compressing the facial skin, did not remarkably alter the skin blood flow on healthy, young adults. The thermochromic pigment showed color change in maxillofacial silicone elastomer. However, artificial aging showed that it was too sensitive to UV radiation to be used, as such, in maxillofacial prostheses.

Characterisation of Functional Brown Adipose Tissue In Adult Humans

The white adipose tissue mainly serves the purpose of energy storage, while brown adipose tissue (BAT) has the capacity to generate heat under cold conditions in mammals and in human infants. BAT is controlled by the central nervous system, and BAT function is accompanied by increased energy expenditure. However, it was not previously certain whether adult humans also have functional BAT. The aim of this doctoral work was to identify functional BAT in adult humans and to characterise its glucose uptake and blood flow under cold and insulin stimulation conditions in lean and in obese humans, by using positron emission tomography. Further, the impact of weight loss on BAT glucose uptake was assessed. Cerebral glucose uptake was also studied in relation to BAT function and cold exposure. The results showed that healthy adult humans have functional BAT, as assessed by the intense cold-induced glucose uptake and by biopsies. BAT was also found to be a highly insulinsensitive tissue in lean humans, but the effects of insulin and cold exposure were attenuated in obese humans, although the glucose uptake capacity of cold-activated BAT might be increased by weight loss. Blood flow in the BAT of lean humans was associated with whole-body energy expenditure. The presence of cold-activated BAT was related to lower body mass index and higher insulin sensitivity. Finally, BAT activation was linked to the activity of the cerebellum, the thalamus and certain neocortical regions. The cold-induced cerebral glucose uptake was also lower in obese than in lean adult humans.

Rising to the impossible challenge: the storage of all research data, forever?

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Reserve substances and storage of Cyathea delgadii Sternb. spores

The spores used were collected from a population of trees of Cyathea delgadii Sternb. growing in a gallery forest at the Reserva Biológica e Estação Experimental de Moji Guaçu, São Paulo state, Brazil (22°18’S and 47°11’W). The germination of spores of Cyathea delgadii decreases with time when kept in closed bottles under storage at 4°C in darkness. Germination is still very high after storage for one year. Spores stored for three years do not germinate. The results also show a decrease in soluble proteins and an increase in starch after several months storage.

Analyses of the usefulness of Software Defined Storage Solutions for Web-based Digital Preservation Applications

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Light and storage on the germination of spores of Dicksonia sellowiana (Presl.) Hook., Dicksoniaceae

Spores of Dicksonia sellowiana are positively photoblastic and reach the maximum percentage of germination at 23 ± 2°C in white light after seven days of imbibition. The pre-induction phase for spores induced by white or red light for 24 hours was 72 hours. Gametophytes grown in white light were plane and bidimensional, while those grown under red light were filamentous. The higher the number of hours of light applied per day during 10 days, the higher the percentage of germination. Germination was higher for long white light treatments applied on a daily basis. The effect of different light intensities on germination was also investigated here. The lower percentages of germination were observed for spores kept under 43% and 2% of full sunlight, while those kept under 26, 19 and 4% presented higher percentages. Spores presented circa 82% of germination after 731 days of storage under refrigeration at aproximately 10°C.

Effect of storage of achenes of Bidens gardneri Baker on light sensitivity during germination

Bidens gardneri is a very common herbaceous species in the cerrados of the state of São Paulo, whose seeds become light sensitive at 25°C only. Achenes of this species were stored in refrigerator at 4°C and in cerrado soil and in forest soil. The field experiments were carried out in the cerrado at the Reserva Biológica e Estação Experimental de Moji Guaçu, in Moji Guaçu and in the forest of the Instituto de Botânica, in São Paulo, Brazil. Achenes of B. gardneri vary in size and achenes from 7 to 12 mm long were used. Achenes stored for up to 6 months at 4°C showed light sensitivity; after 9 months storage, the difference in germination between light and darkness had disappeared for the smallest and the largest achenes used. Seeds of B. gardneri germinated during the period of storage in soil; the number of germinated seeds increased over the storage time, while the number of intact achenes decreased for the same period, no matter if the experiment was being carried out in the cerrado or in the forest. Therefore, the achenes germinated in soil in darkness. Light sensitivity was lost in intact achenes that had been stored in soil for three months.

Storage substances in the androgametogenesis and mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae)

Storage substances such as starch grains, proteins and lipids were studied during the male gametogenesis and in the mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae). There are two cycles of amylogenesis and amylolyse. The first cycle lasts until the vacuolated stage when the starch is hydrolyzed and amorphous proteins are stored inside the single vacuole. The next cycle begins after mitosis with the formation of the vegetative and generative cells. At this point, the young vegetative cell stores many starch grains that are bigger than in the first cycle. During the maturation of the male gametophyte, the starch is hydrolyzed and it is absent in the mature pollen grain. Small lipid droplets surround the young generative cell after the mitosis of the androspore and are dispersed in the vegetative cytoplasm during its maturity. The relationship between the pollen storage substances and the ontogeny of the layers in the sporoderm, formation of the generative cell, and the male germ unit were discussed.