Shielding and activation analyses for BTF facility at SNS

The beam test facility (BTF), which simulates front end of the Spallation Neutron Source (SNS), has been built at the SNS, and is preparing for commissioning. The BTF has been assembled and will operate in one of service buildings at the site. The 2.5 MeV proton beam, produced in the facility, will be stopped in the beam dump (made of TZM alloy). In order to support BTF project from radiation protection site, neutron transport simulations and activation analyses were performed to evaluate the necessary shielding around the facility and radionuclide inventory of the beam dump. Normal beam operations and accidental situations have been taken into account. According to the plan of the BTF beam dump, shielding analyses of the dose rates were performed and suggestions for additional shielding in order to reduce dose rates to below 0.25 mrem/h were made. Isotope inventory for TZM beam dump after 100 hours of operation spread over 10 years was analyzed for decay times for up to 10 years. The nuclide of highest long-term activation (up to 10 years) is V⁴⁹, and those contributing most at short decay times (up to 1 day) are Tc⁹⁵ and Tc⁹⁶