Calculations on the alpha-decay half-lives of heavy nuclei are performed through Fermi gas model. The Wood Saxon potential is employed to calculate half-lives through a Coulomb barrier. The present study is initially restricted to even-even nuclei in the heavy mass region with N > 126. Then the study is extended to the heaviest nuclei including super heavy elements. The main consideration in this model is V(0)b(2) . = 100 MeV, where b is the force range between two nucleons which represents the attractive well, and -V-0 is depth. The calculated alpha-decay half lives are found to be in good agreement with the experimental data for heavy nuclei with approximately spherical shape. The results are independent from deformation parameters for super heavy nuclei.

Radon gas with chemical symbol Rn222 is the heaviest element radioactivity, colorless, odorless, tasteless, heavy and noble. Radon naturally in rocks and soils and waters is available and because there is no affinity to plead easily by soil and water molecules into the air and is moving. Radon enters the body with breathing, eating and drinking. Alpha, which is emitted from radon and other nuclear radiations, sent by its daughters nucleus, serious damage to human respiratory and gastrointestinal system brings, so after smoking, the second risk factor in lung cancer is radon radiation. Radon gas density varies due to factors such as temperature, air pressure, humidity and changes in ground layers. As a result, radon gas densities in the seasons are different. In this research, water radon concentration of 10 point Shandiz area in different seasons of the year with the help PRASSI system is measured. Fortunately, the results show that only two samples of drinking water are higher than normal density Bq / l 11.1 in the fall.

In the present work, radon concentrations in drinking water samples of Mashhad city with about 4 millions population has been measurement by PRASSI system. Water samples were collected from various places and supplies of public used water in Mashhad, and then radon concentration has been measured tree times for each sample. Result shows about 75% of water samples have radon concentration gather than 10Bq/lit which advised EPA as a normal level. According the measuring data, water used by people in most of regions is not low enough and below the EPA proposed limits. Since a main section of radon come in body is due to drinking and household water, and for improvement of the social health level, we suggest using the low radon level water source, or public water supplies authority reducing the radon in the drinkable water before public using.

Environmental monitoring and indoor radon measurement are important for health life to give advises to the people in order to reduce the cancer risk of respiratory system. In the present resarch, radon concentration in the air has been measured at indoor of 40 apartments in Mashhad city with PRASSI system. Most of people close the doors and windows during the cold days in winter and use natural gas as fuel and other household usage. So, the radon concentration level increases as we expect. The result demonstrates about 35% of apartments have radon level low than the normal level (48 Bq/m3) and more than 65% have high radon concentration. We suggest reducing radon level at homes by suitable simple ventilation systems.