Source terms, shielding calculations and soil activation for a medical cyclotron. (11th October 2016)

• Record Type: Journal Article
• Authors: Konheiser, J; Naumann, B; Ferrari, A; Brachem, C; Müller, S E
• Is Part Of: Journal of radiological protection. Volume 36:Number 4(2016:Dec.)
• Page Start: 819
• Page End: 831
• Publication Date: 2016-10-11
• Subjects: neutron source terms -- shielding calculation -- soil activation -- cyclotron; Radiation -- Safety measures -- Periodicals; Health Physics -- Periodicals; Radiation Monitoring -- Periodicals; Radiation Protection -- Periodicals; Rayonnement -- Sécurité -- Mesures -- Périodiques; Electronic journals; Fulltext; Internet Resource; Periodical; 363.179905
• DOI: 10.1088/0952-4746/36/4/819
• Languages: English
• ISSNs: 0952-4746

Abstract

Abstract: Calculations of the shielding and estimates of soil activation for a medical cyclotron are presented in this work. Based on the neutron source term from the 18 O( p, n ) 18 F reaction produced by a 28 MeV proton beam, neutron and gamma dose rates outside the building were estimated with the Monte Carlo code MCNP6 (Goorley et al 2012 Nucl. Technol .180 298–315). The neutron source term was calculated with the MCNP6 code and FLUKA (Ferrari et al 2005 INFN/TC_05/11, SLAC-R-773) code as well as with supplied data by the manufacturer. MCNP and FLUKA calculations yielded comparable results, while the neutron yield obtained using the manufacturer-supplied information is about a factor of 5 smaller. The difference is attributed to the missing channels in the manufacturer-supplied neutron source terms which considers only the 18 O( p, n ) 18 F reaction, whereas the MCNP and FLUKA calculations include additional neutron reaction channels. Soil activation was performed using the FLUKA code. The estimated dose rate based on MCNP6 calculations in the public area is about 0.035 µ Sv h −1 and thus significantly below the reference value of 0.5 µ Sv h −1 (2011 Strahlenschutzverordnung, 9 Auflage vom 01.11.2011, Bundesanzeiger Verlag). After 5 years of continuous beam operation and a subsequent decay time of 30 d, the activity concentration of the soil is about 0.34 Bq g −1 .