[Exposure risk for workers and prevention measures in ordinary and emergency conditions]. / Rischio espositivo per i lavoratori e misure di prevenzione in condizioni ordinarie e di emergenza.

SUMMARY: The radiological risk assessment and the definition of the radioprotection physical surveillance program applied to a 250 kW (thermal power) research nuclear reactor operated by a large Italian public body. Useful elements for the prevention of personnel exposures, classification criteria for workers, risk reduction methods and optimization of exposures, most common criticalities in plant activities. Analysis of the main operations related to the activities of irradiation and scientific research with an eye to the needs of researchers and one to the indications of prevention. Consolidated intervention methods for ordinary activities and for emergency situations. Detailed examination of the possible unforeseen events or accidents initiators, stopping the assessment at the definition of the source terms related to emergencies inside the plant. Nuclear and conventional causes of accidents and analysis of the radiological consequences. Indications for in-depth-defense and long-term monitoring of the safety of workers, individuals of population and the environment.

[Work at the cyclotron for radioisotope production: exposure risks and prevention measures]. / Il lavoro al ciclotrone per produzione di radioisotopi: rischi espositivi e misure di prevenzione.

SUMMARY: In this article, there will be presented the main aspects of the radiation protection for a site dedicated to the production of radioisotopes by cyclotron for medical use. After analyzing the design parameters of the site for the operation from a point of view of the radiation protection of the operators, the population and the environment (shielding around the accelerator, ventilation system, chimney releases etc.), we will focus our attention to the handling of unsealed sources produced, with particular regard to the operating procedures. The final part will be dedicated to intervention in exceptional operating conditions (entring the bunker due to a machine failure, breaking of a vial during transfer from the hot cell to the transport container and accidental contamination by an operator).

Gamma residual radioactivity measurements on rats and mice irradiated in the thermal column of a TRIGA Mark II reactor for BNCT.

The current Boron Neutron Capture Therapy (BNCT) experiments performed at the University of Pavia, Italy, are focusing on the in vivo irradiations of small animals (rats and mice) in order to evaluate the effectiveness of BNCT in the treatment of diffused lung tumors. After the irradiation, the animals are manipulated, which requires an evaluation of the residual radioactivity induced by neutron activation and the relative radiological risk assessment to guarantee the radiation protection of the workers. The induced activity in the irradiated animals was measured by high-resolution open geometry gamma spectroscopy and compared with values obtained by Monte Carlo simulation. After an irradiation time of 15 min in a position where the in-air thermal flux is about 1.2 × 10(10) cm(-2) s(-1), the specific activity induced in the body of the animal is mainly due to 24Na, 38Cl, 42K, 56Mn, 27Mg and 49Ca; it is approximately 540 Bq g(-1) in the rat and around 2,050 Bq g(-1) in the mouse. During the irradiation, the animal body (except the lung region) is housed in a 95% enriched 6Li shield; the primary radioisotopes produced inside the shield by the neutron irradiation are 3H by the 6Li capture reaction and 18F by the reaction sequence 6Li(n,α)3H → 16O(t,n)18F. The specific activities of these products are 3.3 kBq g(-1) and 880 Bq g(-1), respectively.