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A Geant4 simulation package has been developed to investigate and test detector configurations for lung counting applications. The objective of this study was to measure radiation emitted from the human body and to make a qualitative comparison of the results of the simulation with an experiment. Experimental data were measured from a plastic phantom with a set of lungs containing 241Am activity. For comparison, simulations in which 241Am activity was uniformly distributed inside the lungs of the ICRP adult reference computational phantom were made. The attenuation of photons by the chest wall was simulated and from this photopeak ef-ficiency and photon transmission were calculated as a function of photon energy. The transmission of 59.5 keV gamma rays, characteristic of the decay of 241Am, was determined from the computational phantom as a function of the angular position of the detector. It was found that the simulated detector response corresponds well with that from an experiment. The simulated count rate below 100 keV was 10.0(7) % greater compared to the experimental measurement. It was observed that 58.3(4) % of photons are attenuated for energies below 100 keV by the chest wall. In the simulation, the transmission of 59.5 keV gamma rays varied from 13.8(2) % to 38.0(4) % as a function of the angular position of the detector. The results obtained from the simulations show a satisfactory agreement with experimental data and the package can be used in the development of future body counting applications and enables optimization of the detection geometry.

Nuclear astrophysics aims to understand the origin of elements and the role of nuclear processes in astrophysical events. Nuclear reactions and reaction rates depend strongly on nuclear properties and on the astrophysical environment. Nuclear inputs for stellar reaction rates involve a variety of nuclear properties, theoretical models, and experimental data. Experiments providing data for nuclear astrophysics range from stable ion beam direct measurements to radioactive beam experiments employing inverse kinematics or indirect methods. Many properties relevant for astrophysical calculations, such as nuclear masses and β-decays, have also been intensively studied. This contribution shortly introduces selected astrophysical processes, discusses the related nuclear data needs, and gives examples of recent experimental and theoretical efforts in the field. peerReviewed

This paper provides a brief introduction to the Arctic atmospheric radioactivity monitoring network. A decade of monitoring results have shown the 137Cs background levels in Arctic air range from 0.05 to 1.50 μBq/m3. The monitoring stations have sufficient sensitivity to detect 137Cs brought to the atmosphere due to resuspension in local soil and reemissions from biomass burning in a daily temporal resolution. These observations can be used as tracers for atmospheric processes. The 133Xe measurements obtained at Yellowknife, Resolute and Spitsbergen could support other research into how air pollution problems arise across intercontinental distances. It will help develop and improve models capable of predicting the long-distance transport and deposition of trace gases in the Arctic. Rainwater monitoring data collected in Finnish Lapland since the 1960’s indicate that 3H radioactivity concentrations reached natural background levels in early 2000s, typically around 1–2 Bq/L monthly, with an annual seasonal variation cycle consistent with the observed of other cosmogenic radionuclides.

This work deals with transport of radionuclides in the geosphere. The subject is investigated through characterisation of water conducting fractures, determining of rock transport properties and development of new methods for characterising geological samples. Here, as is often the case, radionuclide transport is investigated indirectly by characterising the structures, where the transport takes place, and directly by measuring transport properties in the gas phase. First water conducting fractures of three different types and the rock matrix surrounding them were analysed through rock samples from Olkiluoto. The analysis was done using X-ray tomography, the 14C-PMMA autoradiography technique and petrographical methods. The rock properties around the fractures were found to be highly heterogeneous, but some combining features were found. This experiment also showed the strength of combining different analysis methods. Second, a method for converting local porosities obtained through the 14C-PMMA autoradiography technique to fracture apertures was developed by analysing the radiation emitted from the 14CPMMA filled fracture by Monte Carlo simulations and comparing them to fracture apertures. A connection was found and the method was validated by manufacturing artificial glass plate samples with fractures of known apertures, and analysing the autoradiographic images obtained from them. The method needs further development before it can be used on real rock samples, but it was shown to be extremely promising in the studies conducted. Last, the transport properties of Olkiluoto rock samples were measured directly using argon pycnometry and through diffusion, permeability and advection - matrix diffusion measurements in the gas phase. The gas phase methods exclude sorption and other chemical and water-based processes and thus only give information about diffusion. They are, however, over 10 000 times faster, making them excellent for planning of water phase experiments and giving preliminary results. Gas phase methods are also very powerful tools when investigating the long term transport behaviour, as it would take far too long to run water phase experiments to the late part of the breakthrough curves. Correlations between porosity, diffusion coefficient and permeability were investigated and found to exist only between the latter two parameters. The mathematical model and measurement setup for advection - matrix diffusion measurements were vastly improved during these studies and are now effective tools for such a measurement. Overall this work managed to produce usable parameters for the safety assessment of the upcoming nuclear repository. The methods used were found to be suitable for the experiments, and they were developed further during the experiments.

Lähes puolessa Suomen yksityisistä porakaivoista radonpitoisuudet ylittävät vesilaitosvesille annetun annosrajan. Radon on radioaktiivinen kaasu, joka lisää syöpäriskiä sekä veden mukana juotuna että hengitettynä sen vapautuessa vedestä ilmaan. Suomen ympäristökeskus, Säteilyturvakeskus ja Teknillinen korkeakoulu ovat yhteistyössä elokuusta 1995 lähtien tutkineet ilmastusta ja aktiivihiilisuodatusta radonin poistamiseksi porakaivovedestä. Molemmat menetelmät poistavat radonia tehokkaasti (yli 99 % poisto on mahdollista). Riippuen raakaveden radonpitoisuudesta ja käytetyistä vesimääristä ainakin toista näistä menetelmistä voidaan aina käyttää radonin poistoon. Ilmastuksessa mitoituksen lähtökohtana on ilma-vesi -suhde, joka tutkimuksessa on selvitetty eri raakaveden radonpitoisuuksille ja vedenkorkeuksille. Aktiivihiilisuodatuksen mitoittaminen perustuu adsorptio-hajoamisvakioon, jolle tutkimuksessa on etsitty arvoja. Vakio riippuu aktiivihiililaadusta ja veden radonpitoisuudesta. Tutkimuksessa on saatu paljon arvokasta tietoa menetelmien käyttöönottoa ja laitteistojen kehittämistä varten. Myös veden uraanipitoisuudet voivat paikoitellen nousta liian korkeiksi. Tutkimuksessa selvitettiinkin anioininvaihtosuotimen toimivuutta käytännön uraaninpoistossa ja suotimen regenerointia. Tutkittiin myös uraanipitoisen veden vaikutusta aktiivihiilen tukkeutumiseen sekä muita veden laatuominaisuuksia ja niiden vaikutusta radonin ja uraanin poistoon.

Artikkelin ensimmäisessä osassa selvitetään radioaktiivisuutta yleisesti, käsitellen radioaktiiviset aineet sekä radioaktiivisen aineen määrän ja säteilyvoimakkuuden ajallista riippuvuutta matemaattisten laskelmien avulla. Toisessa luvussa, "Sotilaalliseen käyttöön kysymykseen tulevat radioaktiiviset aineet", asetetaan perusvaatimuksiksi riittävän suuri tuotanto, riittävän hyvät varastointimahdollisuudet ja riittävän suuri teho. Luvussa tarkastellaan tarkemmin näitä vaatimuksia eri näkökulmista. Kolmas luku käsittelee yleisiä saastuttamisperiaatteita, ottaen ensiksi esille saastutuksen tarkoituksen ja siihen käytettäviä aineita sekä levittämistekniikkaa. Viimeisessä luvussa tarkastellaan suojatoimenpiteitä, joita ovat säteilytiedustelu ja varsinaiset suojatoimet.