Radiation Safety Analysis for the TPS Accelerators

Taiwan Photon Source (TPS) will be a 3 GeV light source with a circumference of 518.4 m and operating fully at 400 mA in top-up mode, aiming to provide synchrotron light with extremely high brilliance and low emittance. Significant amount of radiation will be produced due to the loss of such high-energy electrons and result in radiation safety concerns. The design objective of radiation safety system is to minimize the possible radiation hazards due to the TPS operation. Figure 1 is a portion of the TPS layout showing the main accelerator components and its bulk shielding configuration. Its basic structure consists of a ratchet style shielding for the outer wall of the storage ring and shielded labyrinths in the inner shielding wall for mainly personnel access. The 150-MeV LINAC will be housed in an independent room with 1 m thick concrete shielding. Both the storage ring and concentric booster will be installed in a shared tunnel made of 1 m thick concrete walls and removable roof. The shielding in the injection area and ratchet end walls will be at least 1.2 m thick concrete. The regulatory dose limits in Taiwan are 20 mSv/y for radiation workers and 1 mSv/y for both non-radiation workers and the general public off site. To comply with ALARA principle and recommendations from similar facilities, NSRRC has decided to accept a more challenging dose limits for the TPS of 1 mSv/y for all staff and users who are working 2000 hours a year and an environmental dose of 0.5 mSv/y at site boundaries for operating 6000 hours a year. These design limits guide shielding requirements and the design of radiation safety systems and program.