The Airborne Radioactivity Measurement Profile of Multipurpose Research Reactor G.A. Siwabessy

Multipurpose research reactor GA Siwabessy also called Reaktor Serbaguna GA Siwabessy (RSG-GAS) routinely operates at 15 MW. Several radionuclides may be released to the inside and outside of the reactor building. These radionuclides have probably resulted from the material activation and fission product released from the core. Therefore the monitoring of radionuclides release must be done to protect the workers and the environment. This study objective to evaluate the radioactivity measurement profile of the air inside the reactor building regarding to safety limit requirements. The evaluation carried out refers to the reactor operation report (ROR) year 2015-2019, the 90th-95th operating cycle. The α-β spectroscopy namely I-Cam has been used to measure airborne radioactivity. This tool can be used to gauge α-β aerosol, noble gas, iodine activity, and gross beta sources. The airborne radioactivity quantification has been done at 0.00 m, 8.00 m, and 13.00 m of reactor floor level and the stack. Air sampling and measurements were carried out at power of 0 MW (shutdown) and 15 MW (normal operation). It was known that the average gross beta at the 0.00 m level was 5.73×10-2 Bq/l (at 0 MW) and 8.49×10−2 Bq/l (at 15 MW). The average gross alpha and beta measurements at the 8.00 m level were 1.93×10−3 Bq/l (at 0 MW) and 2.73 × 10−2 Bq/l (at 15 MW). The average alpha and beta radiation monitoring at 13.00 m levels were 3.23×10-3 Bq/l (at 0 MW) and 4.54×10−3 Bq/l (at 15 MW), respectively. The stack radiation monitoring was detected at 3.63 × 101 Bq/l (at 0 MW power) and 5.96×10 1Bq/l (at 15 MW). Refer to safety analysis report, the all radiation exposure measurements have not exceeded the value of each requirement and indicates still in the under operational safety limit of 7.28×10−1 Bq/l. Since 2015, the limit value has never been exceeded and ensure the safety of workers and environment