Tuloksenjärjestelyn vaikutus lakisääteiseen yrityssaneeraukseen

Tuloksenjärjestelyllä yrityksen johto voi vaikuttaa taloudellisen raportoinnin tulokseen. Tutkielman tavoitteena on tuoda esiin erilaisia tuloksenjärjestelykeinoja, sekä taloudellisissa vaikeuksissa olevien yritysten tuloksenjärjestelyn vaikutusta mahdollisuuteen tulla hyväksytyksi yrityssaneerausmenettelyyn. Tutkielmassa tarkastellaan harkinnanvaraisten jaksotusten sekä liiketoimien manipuloinnin avulla toteutettavien tuloksenjärjestelykeinojen tarkoitusta. Lisäksi tarkastellaan yritysten erilaisia motiiveja pyrkiä vaikuttamaan taloudellisen raportoinnin tuloksiin. Tuloksenjärjestelyn ja taloudellisen raportoinnin esittelyn yhteydessä esitellään myös eettistä näkökulmaa aiheeseen liittyen. Tutkielmassa tarkastellaan myös lakiperusteiseen saneerausmenettelyyn hyväksymiseen liittyviä edellytyksiä, sekä käydään läpi menettelystä hylkäämiseen liittyvän likvidaatiokonkurssin seurauksia. Tutkielmassa esitellään myös aikaisempia tutkimuksia taloudellisessa ahdingossa olleiden yritysten tuloksenohjauksen käyttöön ja saneerausmenettelyyn liittyen. Tutkielman empiirisessä osassa testataan liiketoimien organisointiin perustuvan tuloksenjärjestelyn esiintymistä saneerauksesta hylättyjen ja menettelyyn hyväksyttyjen yritysten ja terveiden vertailuryhmien välillä. Tutkimustulokset osoittavat molempien saneerausmenettelyyn pyrkineiden yritysten järjestelleen tulostaan vertailuryhmiään enemmän.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Sorption and matrix diffusion in crystalline rocks : In-situ and laboratory approach

The geological disposal of spent nuclear fuel may represent a good solution after a thorough risk assessment. In Finland and Sweden, the host rock for geological disposal is crystalline rock and the repository is based on the Swedish KBS-3 multi-barrier design. When radionuclides from spent nuclear fuel are potentially released into the bedrock, they are then transported by advection along water-conducting fractures. The retardation of radionuclides can occur via molecular diffusion into stagnant pore water and/or via chemical retardation onto mineral surfaces in the rock matrix. When assessing the risk of spent nuclear fuel deposition, it is important to understand the transport behaviour of radionuclides in the bedrock, that is, at the rock–groundwater interface. Most parameters, such as the diffusion coefficient, the distribution coefficient and the rock porosity, associated with radionuclide migration in the rock are obtained from laboratory scale experiments. In order to apply results from laboratory experiments to the full-scale nuclear fuel deposition, in-situ experiments are performed. For example, the Swiss National Cooperative for the Disposal of Radioactive Waste (Nagra) have been conducting extensive in-situ experiments at the Grimsel Test Site (GTS). During the first in-situ test, tritiated water (HTO), 22Na, 134Cs and 131I, as well as non-radioactive isotopes 127I and 23Na, were circulated in a borehole interval isolated by packers 70 cm apart from each other. The second ongoing Long Term Diffusion (LTD) experiment primarily uses the same radionuclides as well as the non-radioactive element selenium. This thesis presents the laboratory analysis of HTO and iodine from an in-situ diffusion experiment and supporting laboratory studies aimed at determining the sorption and diffusion of caesium and selenium on Grimsel granodiorite (GG). Caesium sorption was studied through batch sorption experiments using crushed rock, while selenium diffusion and sorption relied on batch and block scale experiments using Kuru grey granite (KGG) and GG rock blocks. HTO and iodine diffusion was modelled using the time domain diffusion (TDD) method among in in-situ rock blocks as well as selenium in a laboratory using rock blocks. The outleaching method proved successful for analysing non-sorbing radionuclides from the connected pore network of the GG. TDD modelling of the results lead to an apparent diffusion coefficient of 3 × 10-10 m2/s for both HTO and iodine. No significant difference between the in-situ and laboratory diffusion coefficient was detected. Caesium sorption stood at 0.107 ± 0.003 m3/kg on GG at a 10−8 M Cs concentration. Sorption was highest on biotite at Kd = 0.304 ± 0.005 m3/kg, explaining the in-situ diffusion results of caesium which followed the biotite veins in GG. The sorption of selenium was significantly overestimated when the determination was conducted on crushed rock using the batch sorption method compared to studies conducted on intact rock. The outleaching method proved successful in the analysis of non-sorbing radionuclides, while flexible TDD modelling proved to be a quite useful tool in handling measured data from both block scale experiments and in-situ experiments of weakly and non-sorbing tracers.Geologinen loppusijoittaminen tarjoaa hyvän vaihtoehdon käytetyn ydinpolttoaineen hävittämiselle, kun perinpohjainen riskinarviointi on suoritettu. Suomessa ja Ruotsissa geologinen loppusijoitus perustuu ruotsalaiseen KBS3 moniestemalliin ja isäntäkivenä toimii kiteinen kivi. Jos radionuklidit vapautuvat käytetystä ydinpolttoaineesta peruskallioon, ne kulkeutuvat advektiolla vettä johtavia rakoja pitkin. Radionuklidien pidättyminen voi tapahtua diffuusiolla seisovaan huokosveteen tai/ja kemiallisella pidättymisellä kivien mineraalipinnoille. Kun arvioidaan ydinjätteiden loppusijoituksen riskejä, on tärkeää ymmärtää radionuklidien kulkeutuminen peruskalliossa eli kivi-pohjavesi rajapinnalla. Useimmat radionuklidien kulkeutumiseen kivessä liittyvät parametrit, kuten diffuusiokerroin, jakautumiskerroin ja kiven huokoisuus, on saatu laboratoriokokeista. In-situ kokeita tehdään, jotta näitä tuloksia voitaisiin soveltaa täyden mittakaavan ydinjätteidenloppusijoituksessa. Esimerkiksi Sveitsiläinen Nagra (National Cooperative of Radioactive Waste) on suorittanut kattavia in-situ kokeita Grimselin vuorilaboratoriossa. Ensimmäisessä in-situ kokeessa merkkiaineita, tritioitu vesi (HTO), 22Na, 134Cs ja 131I sekä stabiileja isotooppeja 127I ja 23Na, kierrätettiin 70 cm pitkällä eristetyllä alueella kairanreiässä. Toisessa kokeessa käytetään myös näitä samoja nuklideja ja sen lisäksi ei radioaktiivista seleeniä. Tässä väitöskirjassa esitetään HTO:n ja jodin laboratoriomääritykset in-situ diffuusiokokeesta ja kesiumin ja seleenin sorptiota ja diffuusiota Grimselin granodioriitissä (GG) tutkivat tukevat laboratoriokokeet. Kesiumin sorptiota tutkittiin kivimurskeilla tehdyillä sarjakokeilla. Seleeni sorptiota ja diffuusiota tutkittiin Kurun harmaassa graniitissa (KGG) ja GG:ssä sekä kivimurskeilla, että kivilohkareissa tehdyillä diffuusiokokeilla. HTO:n, jodin ja seleenin diffuusiota mallinnettiin TDD (time domain diffusion) menetelmällä. Ulosuutto osoittautui toimivaksi menetelmäksi ei-sorboituvien radionuklidien määrittämiseksi GG:n yhtenäisestä huokosverkostosta. Tulosten TDD mallinnuksen perusteella näennäiseksi diffuusiokertoimeksi saatiin 3 × 10-10 m2/s sekä HTO:lle että jodille. In-situ ja laboratorio diffuusiokertoimien välillä ei havaittu merkittävää eroa. Kesiumin jakaantumiskerroin oli 0.107 ± 0.003 m3/kg GG:ssä Cs pitoisuuden ollessa 10−8 M. Sorptio oli suurinta biotiittin Kd = 0.304 ± 0.005 m3/kg. Tämä selittää in-situ tulokset, jossa kesiumin diffuusio seuraa biotiittijuonteita. Seleenin sorptio oli huomattavasti yliarvioitu kun se määritettiin sarjakokeilla kivimurskeeseen verrattuna kokonaisella kivellä tehdyillä kokeilla saatuihin arvoihin. Ulosuutto osoittautui toimivaksi menetelmäksi ei-sorboituvien radionuklidien määrittämisessä. Myös TDD mallinnus osoittautui hyödylliseksi työkaluksi sekä lohkare että in-situ kokeista saatujen mittaustulosten käsittelyssä heikosti- ja ei-sorboituville radionuklideille

Seasonal variability in ecosystem functions: quantifying the contribution of invasive species to nutrient cycling in coastal ecosystems

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A process for designing algorithm-based personalized gamification

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Through diffusion experiments to study the diffusion and sorption of HTO, 36Cl, 133Ba and 134Cs in crystalline rock

The spent nuclear fuel in Finland will be deposited in crystalline granitic rock in Olkiluoto, Finland. As a part of the safety assessment of the repository, series of extensive in-situ sorption and diffusion experiments and supplementary laboratory work has been done in the Olkiluoto site. Through Diffusion Experiment in a laboratory (TDElab) aims to provide applicable data for the ongoing in-situ experiment in Olkiluoto. This laboratory scale experiment resembles the in-situ experiment and aims to gain information on possible effects in values of distribution coefficients, effective diffusion coefficient and porosity that are caused by differences in laboratory and in-situ conditions. The through diffusion and sorption of tracer solution with known activities of HTO, 36Cl, 133Ba and 134Cs were studied in a decimeter scale sample of veined gneiss, which is one of the main rock types in Olkiluoto. The measured breakthrough curves were modeled taking into account the porosity of the rock and diffusion and sorption of the radionuclides using Time-Domain Random Walk (TDRW) simulations. The porosities of 0.7–0.8% were determined for the rock and effective diffusion coefficients of (3.5 ± 1.0) × 10−13 m2/s and (3.0 ± 1.0) × 10−13 m2/s were determined for HTO and 36Cl, respectively. The porosity and effective diffusion coefficients were found to be in agreement with previous results for veined gneiss. Furthermore, distribution coefficients of (1.0 ± 0.3) × 10−4 m3/kg and (2.0 ± 0.5) × 10−3 m3/kg were determined for 133Ba and 134Cs, respectively, using information about the effective diffusion coefficient determined for HTO. The distribution coefficients were found to be significantly smaller than the ones determined for crushed rock in previous studies and slightly smaller than the ones from previous in-diffusion experiments.Peer reviewe

Terahertz radiation detection with a cantilever-based photoacoustic sensor

We report the photoacoustic (PA) response in the terahertz (THz) range by employing a detection process actuated with a silicon cantilever pressure sensor and a carbon-based radiation absorber. The detection relies on the mechanical response of the cantilever, when the volume of the carrier gas inside the PA cell expands with the heat produced by the radiation absorber. The detector interferometrically monitors the movement of the cantilever sensor to generate the PA signal. We selected the absorber material with the highest THz responsivity for detailed studies at 1.4 THz (214 pm wavelength). The observed responsivities of two different radiation absorbers are nearly the same at 1.4 THz and agree within 10% with responsivity values at 0.633 pm wavelength. The results demonstrate the potential of covering with a single PA detector a broad spectral range with approximately constant responsivity, large dynamic range, and high damage threshold. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License.Peer reviewe

Multi-site surface complexation modelling of Se(IV) sorption on biotite

A surface complexation model of Se(IV) sorption on biotite with one type of strong sorption sites and two types of weak sorption sites were developed based on experimental data obtained from titration, sorption edge and sorption isotherm experiments. Titration data was collected using a batch-wise manner together with back-titration to calibrate the effect of mineral dissolution in 0.01 M KClO4 background electrolytes from pH 3 to 11 in an inert atmosphere glovebox. Further calibrations of the titration curve include proton exchange and cation exchange in which the calculations of cation occupancies on biotite surfaces were taken into account. The sorption edge measurements were determined by measuring the sorption of 10(-9) M total Se with a radioactive Se-75 tracer on converted biotite in 0.01 M KClO4 solution from pH 3 to 11. Se sorption was observed to be strongly dependent on pH. Surface complexation modelling was performed by deriving a set of optimized parameters that can fit titration, sorption edge and sorption isotherm (at pH similar to 7.7) experimental data. A CASTEP code implemented into Materials Studio was used to calculate the site densities and site types on the biotite surfaces. Weak sorption sites with site densities of 3.2 sites/nm(2) and 1.4 sites/nm(2) were derived from the codes and used in the sorption model. A computer code that coupled PHREEQC with Python was developed for the fitting and optimizing processes. The model was validated by sorption data at pH similar to 9.5. The results show that the model can provide quantitative predicts of Se(IV) sorption in groundwater conditions of a deep geological repository and help improve the performance assessments by giving more convincing estimates of the release of radionuclides towards aquifers and biosphere.Peer reviewe

The sorption and diffusion of 133Ba in crushed and intact granitic rocks from the Olkiluoto and Grimsel in-situ test sites

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Sorption of Se species on mineral surfaces, part I : Batch sorption and multi-site modelling

The sorption behavior of Se(IV) on Grimsel granodiorite and its main minerals, plagioclase, K-feldspar, quartz and biotite, were investigated in Grimsel groundwater simulant in a large Se concentration range (from 1.66 x 10(-10) M to 1 x 10(-3) M). Experimental results show that the distribution coefficients (K-d values) of Se (IV) on the rock and mineral samples increased with the decreasing of Se(IV) concentration. The sorption of Se (IV) on biotite has the largest K-d value in low concentration area (<10(-7) M) stabilizing between 0.0595 +/- 0.0097 m(3)/Kg and 0.0713 +/- 0.0164 m(3)/Kg. The Kd value of Se(IV) on K-feldspar was the second largest (0.0154 +/- 0.0019 m(3)/Kg in 10(-9) M) while the sorption on quartz was negligible. The sorption behavior of Se(IV) on Grimsel granodiorite followed the same trend as plagioclase, the most abundant mineral in Grimsel granodiorite, with K-d values of 0.0078 +/- 0.0010 m(3)/Kg for Grimsel granodiorite and 0.0085 +/- 0.0016 m(3)/Kg for plagioclase, when Se(IV) concentration was 10(-9) M. HPLC-ICP-MS results show that all the Se(IV) remained in + IV oxidation state after more than 1 month experimental time and speciation modelling proved that the main species in Grimsel groundwater simulant were HSeO3- and SeO32-. Multi-site surface complexation modelling was performed by PHREEQC with the help of molecular modelling techniques which was performed with the CASTEP code implemented into Materials Studio. The modelling results predict that there are three kinds of sorption sites on the surface of biotite mineral, with sorption site densities differing in three magnitudes.Peer reviewe