Volume 2 [2000]

The vertical migration velocity of radionuclides and the ability of soils components to immobilise them,
as the most important parameters of natural-restoration, was studied. The Dose Equivalent Rate
(DER) reduction of external ã-radiation was studied in order to assess its impact on human health. The
vertical migration velocities of 137Cs and 90Sr in typical soils of contaminated regions in Ukraine
(Chernobyl 30-km zone) and Belarus (Gomel region) have been evaluated annually during the last 8
or 10 years since the accident. In most of these soils the migration rate of 90Sr was found to be higher
than this of 137Cs and ranged from 0.71 to 1.54 cm year-1 and 0 to 1.16 cm year-1 respectively. At present
the main part of radionuclides is located in the upper 10 cm soil layer. The ability of the soil components
to immobilise the radionuclides was also investigated from 1989 to 1994 and was found that
approximately 57% of 137Cs was converted in fixed forms. It is expected that this percentage will
increase to 80% in the next years. Finally, we studied how the DER of ã-radiation, which changes with
the migration of radionuclides in the soil, affects the human health. In comparison with 1986, when
100% of 137Cs was distributed on the soil surface, a significant reduction of DER occurred in the studied
areas and about ten years after the Chernobyl accident, it ranges from 17.5% to 45%, depending
mainly on the level of initial contamination of soils and its migration velocity.

A multi-layered three-dimensional hydrodynamic model has been developed to provide flow fields and
water level changes in Hamilton Harbour. The field data collected in Hamilton Harbour during 1990
& 1991 field seasons was used for model verification. The simulated currents were compared with current
meter data. Results from the trajectory model are in good agreement with the drogue experimental
data. A quantitative criterion to evaluate the trajectory comparison was established with the help of
the trajectory model using the random-walk approach. By using the water level changes in the
Burlington Ship Canal, the model predictions were validated with the measurements at three water
level stations in the Harbour. These comparisons demonstrate that the models can simulate the major
features of the water current and level changes in Hamilton Harbour.

The present studies aimed to obtain clean fuel combustion and get detailed information about the
processes that determine the electric field effect on NOx formation in flame channel flows. The experimental
studies demonstrate that the interaction between the radial electric field and the flame initiates
the field-forced drift motion of positive radical ions in a field direction. The energy exchange
between ions and gas particles produces interrelated heat and mass transfer to the negatively biased
channel walls. Hence, by varying the applied voltage, a field-enhanced reducing of a flame temperature
is obtained, thereby lowering thermal NOx formation during the fuel combustion up to 30-80%.

The aim of this paper is to identify the factors that have influenced changes in the amount of carbon
dioxide (CO2) emitted from the Greek manufacturing sector as a whole and from three representative
subsectors. By means of an algebraic decomposition method the changes recorded during the period
1985-95 are analysed into four distinct factors: output level, energy intensity, fuel mix and structural
change. The results show that the observed reduction of industrial CO2 emissions is not only due to the
decrease of industrial energy intensity but also to the recession of the Greek manufacturing sector. The
two other factors, namely sectoral and fuel shifts were driving emissions upward, primarily because of
the increasing share of electricity - intensive sectors and the growing dependence of electricity generation
from lignite. It is concluded that for the reduction of industrial CO2 emissions in the long term,
policy measures should aim at further promoting energy saving technologies and encouraging the use
of natural gas and renewable energies.