Radiation Safety Considerations for Design of the Spear3 Storage Ring*

The SPEAR3 storage ring at the Stanford Synchrotron Radiation Laboratory (SSRL) is an upgrade of the existing SPEAR2 ring to a 3-generation storage ring with beam parameters of 3 GeV of electron beam energy, 18 nm-radian emittance and up to 500 mA of circulating current. While the existing injector will not be changed, the 234-m-circumference SPEAR2 ring components will be completely replaced with new components including C-shaped dipoles. The concrete shielding walls are to remain unchanged. This restriction, when considered in conjunction with the significant increase in the current and loss of self-shielding in the dipole magnets, requires careful study of the SPEAR3 shielding. This paper describes the methodology used for calculating the required shielding in a generic method. The criteria used for the design of shielding and beam loss estimates for various modes of beam operation are also presented. FLUKA Monte Carlo code was used extensively in generating source term data (dose rate as a function of angle for photons and neutrons) for both thin and thick targets. Attenuation profiles of neutrons and photons in concrete and lead shield materials are also presented. These data are being used to evaluate the shielding requirements for the lateral and ratchet walls. The current status of this approach will be discussed. Other issues presented include the use of active devices that are part of the radiation safety systems for the SPEAR3. Presented at the 2nd International Workshop on Radiation Safety at Synchrotron Radiation Sources, Grenoble, France, October 17-18 (2002). *Work supported by Department of Energy contract DE-AC03-76SF00515. Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309, USA