L. Tommasino

Radon monitoring by alpha track detection

Abstract Passive radon monitoring devices based on damage track detectors are very attractive for the assessment of long-term radon exposures. These devices can be divided into two broad categories, formed respectively by diffusion and permeation samplers. A permeation-type device based on a heat-sealed polyethylene bag is used in Italy. For short-term (one week or less) radon measurements, damage track detectors are not considered to be sufficiently sensitive. This paper illustrates how simple it is to measure short-term radon exposures in dwellings by spark-counting large detector areas of cellulose nitrate foils.

Assessment of natural and man-made alpha emitting radionuclides

Abstract Damage track detectors have unique capabilities for measuring low concentrations of natural and man-made alpha emitters in biological and environmental samples. With electronic devices such as surface-barrier detectors, zinc-sulphide screen counters and large area grid ionization chambers, the detection sensitivity is limited by the duration of exposure or the stability of electronic counting systems. Damage track detectors can be used for sufficiently long exposure periods so that the intrinsic background of the detector material can be ignored. In particular, the applications of damage track detectors, described in this paper, refer to the assessment of low concentrations of Uranium, Plutonium and radon, using the registration of alpha-particle and fission- fragment tracks. The sensitivity and the simplicity of track counting can be greatly enhanced by using the spark counter.

Radiocaesium contents of meat in Italy after the Chernobyl accident and their changes during the cooking process

Abstract Levels of radioactive contamination in meat have been studied, along with ways of decreasing them. Specifically, radiocaesium concentrations in a range of samples of different types of meat collected throughout Italy since April 1986 are presented here. The samples are of beef, lamb, pork, chicken, turkey and rabbit. It was found that the radiocaesium content of lamb is higher than that in any of the other meat types considered here. Studies of the decrease in the radiocaesium content of meat during cooking showed that, when the meat is cooked in salt water (1%), the activity decreases by as much as 80% relative to uncooked samples.

Radon monitoring for short term exposures in indoor air

Abstract For screening survey of indoor radon, an exposure period as low as one week is required. For these measurements, damage track detectors are considered not sufficiently sensitive and the diffusion barrier charcoal adsorption collector, DBCA, is used in spite of its response highly dependent on temperature and humidity. This paper illustrates how simple it is to measure short-term radon exposures by spark counting large detector areas.

Concentrations of radiocaesium in Italian durum wheat and its products after the Chernobyl accident

Abstract The radiocaesium concentrations of over 400 samples of durum wheat (Triticum durum) collected throughout Italy after the Chernobyl accident have been measured here to study the implications of contamination of this specific type of wheat used primarily in making alimentary pasta. The transfer of radiocaesium from the wheat sample of highest activity into the human food chain was studied systematically by measuring radiocaesium levels in the outer layers of the grain and in semolina, pasta and bread produced from this wheat. The effect of cooking on the nuclide content of pasta was also studied, the results showing that most of the radiocaesium is removed into the water in which the pasta is boiled.

Calculation of the individual effective dose equivalent in Italy following the chernobyl accident

Abstract Estimates are presented here for the individual effective dose equivalents (EDE) from dietary intake of radiocaesium-contaminated food by the average Italian consumer in different age groups. Food items of consumption rate greater than 50 kg/y were included in the food basket studies. In view of the pattern of food consumption in Italy, the radiocaesium concentrations of foodstuffs such as milk, milk products, bread, pasta, meat, fruit, vegetables and babyfoods were measured between January 1987 and December 1988 inclusive. These measurements were carried out mainly by the environmental radioactivity laboratories in three administrative districts of Italy. The results show that the total individual EDE values received in 1987 from foodstuffs were around 175, 110 and 70 μSv/year for adults, children (up to 10 years old) and infants (up to one year old), respectively. The corresponding values for 1988 are about 15, 10 and 20 μSv/year, respectively. The EDE committed in the latter half relative to the first half of 1987 was a factor of 2.5 and 3 less for adults and children, respectively, and a factor of about 2 for infants. In 1988, no significant change was observed in EDE values during the year.

Further investigation on electrochemically etched CR-39 neutron detectors

Abstract The most important characteristic of the electrochemically etching processes is the ability to control the etching procedures with an external apparatus to obtain any desired neutron detector response. This paper describes the results of the track size distributions for the samples obtained from the Joint European/USA/Canadian irradiations organised by EURADOS-CENDOS.

Unique characteristics of thin film electrochemical etching

Abstract The spark counter makes it possible to scan large detector areas and to measure neutron fluences and radon exposures with unique sensitivity. For neutron-induced recoils and for short-etchable tracks (such as alpha-particle tracks in polycarbonate) the spark counter is no more useful. In this case the electrochemical etching process is very often used to facilitate the track counting, in spite of its limitations of high-voltage requirements. In this paper, it will be illustrated how simple is to overcome these shortcomings by thin-film electrochemical etching.