Abstract
The original beamline shielding of NSRRC was designed for the decay mode operation that safety shutter was closed during injection. The proposed top-up operation that opens safety shutter during top-up injection will introduce additional beam loss scenarios and radiation sources, especially when the injection efficiency needs to be improved. Careful comparison was made to differentiate the radiation doses into beamlines for both operation modes. Detailed evaluation was made to identify the possible inadequacies of the old beamline shielding and safety control procedures. Remedy actions and safety upgrades for each individual beamline were issued to ensure that dose limit of 2 mSv/yr for users can be fulfilled when running top-up operation. © 2007 Elsevier Ltd. All rights reserved.