Comparison study of environmental radiation dose due to ⁴¹Ar plume recorded in argon fluence monitor and autonomous gamma dose logger

Environmental radiation monitoring programme has been carried out in 24 x 7 basis by Radiological Safety Division, for more than a decade using instruments like Gamma Tracer, Online-EGDL (Environmental Gamma Dose Loggers), Autonomous Gamma Dose Loggers (AGDL), deployed at field locations within the fenced complex of Kalpakkam site covering 9 wind direction sectors each of 22.5° on the land side of Emergency Planning Zone (EPZ) of Madras Atomic Power Station (MAPS). The data obtained from these instruments are periodically compiled and monthly reports are documented. The dose rate observed in Gamma Tracer, AGDL and Online-EGDL is further analyzed by correlating with the meteorological parameters of Kalpakkam site, in particular with wind direction, which is used to corroborate the contribution of sky shine dose due to ⁴¹Ar plume which is routinely released from MAPS stack. The time dependent data is used for calculating the source term for online nuclear emergency response system (ONERS). In order to ascertain the excess dose contribution by ⁴¹Ar plume, a study had been conducted by deploying Argon Fluence Monitor and AGDL at WSCD for a period of four months Sept-Dec, 2014 and dose rates were recorded. The analysis of dose rate is presented in this report