Radiation shielding evaluation for 3 MeV proton linac at RRCAT, Indore

A 3 MeV front end linac is being developed to install as a pre-injector to 1 GeV proton accelerator for Spallation Neutron Source applications at RRCAT. It consists of an ion source, Low Energy Beam Transport (LEBT) system, Radio Frequency Quadrupole (RFQ) and a beam dump. A shielded cell is designed for housing the accelerator. Dose rate due to photons and neutrons are estimated at reference points outside the cell and at the roof for estimating the shielding thickness. Based on the calculation, local shielding around beam dump is decided to reduce the dose rate at the reference points to permissible limit. The paper describes the beam loss assumptions used for evaluating the source term and the shield evaluation. The total dose rate at all locations outside the cell work out to be less than 1 μSv/h with 30 cm and 60 cm thick concrete wall, 30 cm thick roof and local shielding at beam dump. The radiation streaming through sliding door is also evaluated. (author)