The ENEA-IRP thoron calibration facility.

To check the consistency of a (220)Rn measurement, performed by passive alpha track detector (ATD), the use of an accurate (220)Rn exposure calibration facility is mandatory. The ENEA Radon Service developed a new CR-39 ATD-Tn, coupled to the radon ATD-Rn and, to assess its sensitivity, had to design a small calibration facility, which has been recently modified to improve the spatial homogeneity exposure conditions inside the chamber, to get a continuous monitoring of the (220)Rn concentration and to reduce radon contamination. A better knowledge of the circuit response allowed selecting the best-operating conditions and how to regulate the thoron concentration. The active thoron monitor has been changed to serve as a continuous sampling and measuring device rather than a grab one; particular care has been devoted to assess the (216)Po losses on the device's inner surfaces and to evaluate the chamber transit time correction factor.

How to assess the sensitivity and related uncertainty of a new solid state passive thoron measuring device.

To test the sensitivity of our CR-39 alpha-track detector thoron passive device (ATD-TnPD), a closed-circuit exposure facility, composed by a new thoron source, a small exposure chamber and a new absolute (220)Rn active monitor (TnM), was set up. (220)Rn exposure was evaluated by assessing the TnM response and its combined uncertainty. The ATD-TnPD's sensitivity was determined by three thoron exposures, tested at different etching times. A non-linear relationship on etching conditions was obtained, with values in the range 1.54-1.76 (tracks cm(2))(kBq h m(-3))(-1).

Meeting new challenges in radon measurements service with solid state alpha track analysis.

The national and international radioprotection legislation now covers exposures to the naturally occurring radioactive materials (NORM) with particular emphasis on radon in workplaces. Consequently, a number of working environments have now been brought into the realm of radiation protection monitoring with a corresponding increase in the demand for radon monitoring services. The new challenges occasioned by the increase in demands are illustrated in this paper together with the radon measurement system developed at the ENEA IRP radon Service. In particular, this paper emphasises how to control using hardware and software analysis, the distributions (diameters and areas) of the track shape, which directly affect the quality of the radon service.

A modelistic approach to evaluate the factors affecting the 137Cs transfer from mother to fetus in cattle.

The authors have analysed the relationship between 137Cs radioactivity and pregnancy in cattle with radiometric analysis of muscle, kidney and liver of 24 cattle at various stages of pregnancy, fed with fodder exposed to radioactive fall-out. Also the relative fetal muscle, kidney, liver and myocardium have been analysed. The automatic spectra analysis and the statistical one have given the following results: there is no correlation between 137Cs retention and the pregnancy stage in the cattle sampled; the absolute 137Cs concentration is always larger in the kidney than in the muscle (Km/Mm = 1.7), while it is just minor in minor in the liver (Lm/Mm = 0.8). The fetal concentration in muscle, kidney and liver is generally homogeneous, whereas the myocardium tends to retain more 137Cs in the first stages of the pregnancy as against the other tissues. In the last stage of pregnancy it presents a lower concentration. The authors have included the fetal body weight growth to get a more realistic description of the 137Cs transfer in the mother-fetus system; this approach enables to evaluate the kinetic constants so introduced.

A radiation protection device for use during percutaneous transhepatic examinations.

The authors describe a shield for the fluoroscopist to be used during percutaneous transhepatic examinations.