The shielding design of the Metrology Light Source

MLS will consist of a 100 MeV microtron and a 600 MeV electron storage ring. The investigations of the radiation types occurring at those machines dependent of the electron energy, target and shielding materials, observating angles and geometric aspects are well established, often condensed in semi-empiric formulas and in good agreement with the results of Monte Carlo codes like FLUKA for lateral shielding. But as important as the pure physical aspects of radiation are for a shielding design the operating times and modes and the considerations of possible crash scenarios. We present here an approach of considering failure operating probabilities at electron storage rings based on years of radiation and operating observations of BESSY I and BESSY II for the shielding design of MLS. Comparisons of FLUKA calculations with the used semi-empiric formulas are presented too.