Quantitative Evaluation of Radioactivity in Concrete at PET Cyclotron Facility with Simple and Non-destructive Measurement

Accelerator operations often generate neutrons that may activate concrete in the accelerator room. When accelerators are decommissioned, the concrete will remain as radioactive waste. Not all of concrete in the room will be radioactive wastes, but at place with large amount of neutrons will be radioactive wastes. Therefore, it is very important to determine where and how many neutrons are generated during accelerator operation. We used gold foils to obtain this information in positron emission tomography (PET) cyclotron facilities. We obtained concrete core samples from a PET cyclotron to determine the amount of radioactivity contained in concrete. We obtained the operational parameters (particle, radioactive product, current, and operation time) of the PET cyclotron facility and estimated the radioactivity generated in concrete using the operational parameters and gold foil results. A comparison of the estimated and core sampling measurement results showed good agreement.