Gediminas Adlys

Levels of 14C in the Terrestrial Environment in the Vicinity of Two European Nuclear Power Plants

Radiocarbon is produced in all types of nuclear reactors. Most of the C-14 released into the environment is in the form of gaseous emissions. Recent data on the C-14 concentration found in terrestrial samples taken in the vicinity of nuclear power plants in Romania and Lithuania are presented. We found increased C-14 levels in the surroundings of both power plants. At the Romanian power plant Cernavoda, we found excess levels of C-14 in grass within a distance of about 1000 in, the highest C-14 specific activity being 311 Bq/kg C (approximately 28% above the contemporary C-14 background) found at a distance of 200 in from the point of release (nearest sampling location). At the Lithuanian power plant Ignalina, samples of willow, pine, and spruce showed a C-14 excess of similar magnitude, while significantly higher values were found in moss samples. The samples were analyzed at the accelerator mass spectrometry facility in Lund, Sweden. (Less)

The resulting skin dose in two-view mammography examinations.

The entrance surface dose (ESD) (skin dose) and its variation due to overlapping radiation fields at mammography have been experimentally investigated on patients during two-view mammography screening examinations of both breasts and on phantoms of silicon gel. Measurements were done using multiple thermoluminescence dosemeters for mapping the variations in absorbed dose at the surface of the breast phantoms. It was found that the total resulting skin dose at the reference point on the breast surface, described in the European Protocol [Zoetelief, Fitzgerald, Leitz and Sabel (European protocol on dosimetry in mammography. EUR 16263 (Luxemburg: EC), 1996)] after multiple exposure of patients breasts during two-view, four exposures mammography screening examinations is approximately 50 % higher as compared with the skin dose at the same point measured during one single (CC) exposure. The dose distributions on the breast phantom surface were non-uniform and indicated areas of higher doses, which were related to the regions of the superimposed fields on the surface during the examinations. The dosimetric importance of the superposition of X-ray fields on the ESD is discussed.