R. Tinti

Shielding calculations for a 250 MeV hospital-based proton accelerator

Abstract The accelerator shields (250 MeV protons, 400 MeV/u 16 O 8+ ions) and treatment rooms of the Hadrontherapy Centre, a hospital-based facility under design in Italy, were determined by means of Monte Carlo calculations. The LCS and FLUKA codes were employed, together with analytical estimates carried out by making use of empirical formulas from the literature, and the results compared. In the case of 250 MeV protons a 250 cm thick concrete wall ensures and annual dose equivalent lower than 2 mSv in the environments adjacent to the accelerator room. The best ceiling thickness was found to be 200 cm for a unitary occupancy factor. The photon dose equivalent beyond the concrete shield was also estimated using the LCS code. In the case of ions the shield thickness was calculated using empirical formulas from the literature; the concrete thicknesses calculated for protons should ensure the required dose equivalent when some local shields are added. Monte Carlo calculations of the treatment room shielding were also carried out using the FLUKA code.

Estimation of Clearance Potential Index and Hazard Factors of CANDU Fuel Bundle and Its Validation Based on the Measurements of Radioisotopes Inventories From Pickering Reactor Fuel

This paper is related to the clearance potential levels, ingestion and inhalation hazard factors of the spent nuclear fuel and radioactive wastes. This study required a complex activity that consisted of more steps such as: the acquisition, setting up, validation and application of procedures, codes and libraries. The paper reflects the validation stage of this study. Its objective was to compare the measured inventories of selected actinide and fission products radionuclides in an element from the Pickering CANDU reactor with the inventories predicted using a recent version of the SCALE 5\ORIGEN-ARP code coupled with the time dependent cross sections library for the CANDU 28 reactor (produced by the sequence SCALE4.4a\SAS2H and SCALE4.4a\ORIGEN-S). In this way, the procedures, the codes and the libraries for the characterization of radioactive material in terms of radioactive inventories, clearance, and biological hazard factors could be qualified and validated, in support of the safety management of the radioactive wastes.Copyright

Feasibility study of BNCT of skin melanoma with an accelerator-based neutron source

The feasibility of an accelerator-driven thermal neuron source for Boron Neutron Capture Therapy (BNCT) of skin melanoma is discussed, based on the design of an analogous source for BNCT of the explanted liver. Monte Carlo simulations were performed by introducing some variations in the moderator geometry of that source. Neutrons are generated by 7 MeV deuterons impinging on a thick beryllium target. The neutron moderator consists of a nuclear graphite structure containing a heavy water tank in turn enclosing the beryllium target. The moderator materials were chosen in order to minimize the production of prompt gamma rays. THe requested neutron fluence can be achieved in three hours with a deuteron current in the range of 3-8 mA.