A very limited number of field experiments have been performed to assess the relative radiation detection sensitivities of commercially available equipment used to detect radioactive sources in recycled metal scrap. Such experiments require the cooperation and commitment of considerable resources on the part of vendors of the radiation detection systems and the cooperation of a steel mill or scrap processing facility. The results will unavoidably be specific to the equipment tested at the time, the characteristics of the scrap metal involved in the tests, and to the specific configurations of the scrap containers. Given these limitations, the use of computer simulation for this purpose would be a desirable alternative. With this in mind, this study sought to determine whether Monte Carlo simulation of photon flux energy distributions resulting from a radiation source in metal scrap would be realistic. In the present work, experimental and simulated photon flux energy distributions in the outer part of a truck due to the presence of embedded radioactive sources in the scrap metal load are compared. The experimental photon fluxes are deduced by in situ gamma spectrometry measurements with portable Ge detector and the calculated ones by Monte Carlo simulations with the MCNP code. The good agreement between simulated and measured photon flux energy distributions indicate that the results obtained by the Monte Carlo simulations are realistic.

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Indoor radon concentrations were measured in 77 schools of the prefecture of Xanthi in northern Greece. The arithmetic mean radon concentration is 231 Bq m(-3) with a range between 45 and 958 Bq m(-3). Thirty five schools have mean radon concentration above 200 Bq m(-3) and nine schools have mean radon concentration above 400 Bq m(-3). From continuous radon gas measurements in the school with a relative higher radon concentration (958 Bq m(-3)) was deduced the 'true' radon concentration, defined as the radon concentration in the school during the hours of the presence of teachers and scholars. The mean 'true' radon concentration for a time period of about 2 weeks was 104 Bq m(-3). The mean radon concentration for the same 2 weeks was seven times higher (700 Bq m(-3)). Greek and International regulations for radon in workplaces refer to only the mean annual radon concentration. It would be preferable for schools to replace the mean annual radon concentration with the 'true' radon concentration.

The profile of (137)Cs present in undisturbed soil due to the Chernobyl accident was measured repeatedly for approximately 20 y. The vertical migration of (137)Cs in soil is a very slow process. The mean vertical migration velocity is estimated at approximately 0.1-0.2 cm y(-1). A method based on in situ gamma spectrometry measurements and Monte Carlo computations, aimed at estimating the profile of (137)Cs without performing any soil sampling, is investigated.

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Radiocesiun distribution in the different parts of a Quercus conferta Kit ecosystem in Northern Greece was measured in 2005-2006, twenty years after the Chernobyl accident. The comparison between the results of this study and those previously measured (1993-1995) in the same ecosystem gives information about the long-term behavior of 137Cs in forest ecosystems. The major part of the 137Cs inventory is still in the upper layers of the soil. The radiocesium distribution in soil is fixed and has been in equilibrium at least since 1993, when the first measurements were performed. The major contamination mechanism of leaves and wood is root uptake.

The Nuclear Technology Laboratory of the Aristotle University of Thessaloniki (NTL-AUTh) and the Greek Atomic Energy Commission (GAEC) have a continuous collaboration on indoor radon measurements in Greek buildings since 1999. In the present work, the existing database was enriched with 590 indoor radon measurements in 295 houses and 76 indoor radon measurements in 38 workplaces. In total in the present work, 1948 indoor radon measurements in 974 buildings performed by the NTL-AUTh and GAEC from 1999 to 2012 in 8 of the 13 administrative regions of Greece are presented and discussed.