Results 1 - 2 of 2
Results 1 - 2 of 2. Search took: 0.026 seconds
|Sort by: date | relevance|
[en] A significant number of nuclear power plants will have to be decommissioned over the next few years as a result of earlier and planned shut downs initiated by plant aging, political decisions and unfortunate events. The decommissioning process is challenging for all stakeholders due to uncertainties and risk associated with decisions on applied technologies, organisational changes, and management of human factors. In this study we investigated how concepts, enabled by advanced information technologies, can be applied for providing continuity between different phases of the decommissioning work process and life cycle of the installation, as well as stakeholders involved in on-going and future decommissioning projects.
[en] The human tracheobronchial system has a very complex structure including cylindrical airway ducts connected by airway bifurcation units. The deposition of the inhaled aerosols within the airways exhibits a very inhomogeneous pattern. The formation of deposition hot spots near the carinal ridge has been confirmed by experimental and computational fluid and particle dynamics (CFPD) methods. In spite of these observations, current radon lung dosimetry models apply infinitely long cylinders as models of the airway system and assume uniform deposition of the inhaled radon progenies along the airway walls. The aim of this study is to investigate the effect of airway geometry and non-uniform activity distributions within bronchial bifurcations on cellular dose distributions. In order to answer these questions, the nuclear doses of the bronchial epithelium were calculated in three different irradiation situations. (1) First, CFPD methods were applied to calculate the distribution of the deposited alpha-emitting nuclides in a numerically constructed idealized airway bifurcation. (2) Second, the deposited radionuclides were randomly distributed along the surface of the above-mentioned geometry. (3) Finally, calculations were made in cylindrical geometries corresponding to the parent and daughter branches of the bifurcation geometry assuming random nuclide activity distribution. In all three models, the same 218Po and 214Po surface activities per tissue volumes were assumed. Two conclusions can be drawn from this analysis: (i) average nuclear doses are very similar in all three cases (minor differences can be attributed to differences in the linear energy transfer (LET) spectra) and (ii) dose distributions are significantly different in all three cases, with the highest doses at the carinal ridge in case 3. (authors)