By using a method for calculating the roof thickness for shielding a radiation source with angular distribution

the required optimized concrete roof thickness for shielding high-energy X-rays produced by L3000 9MeV electron linear accelerator was found to be 30cm. The dosimetric measurements made after the accelerater building was completed showed that the shielding design was safe and economic

and the dose equivalent rate of the skyshine radiation was close to the background value

reaching to a level as low as reasonably achievable.