Dosimetry in radiation processing- Indian scenario

Radiation processing is a method for producing chemical, physical, and microbiological changes in substances by exposing to ionizing radiation. Availability of high intensity cobalt-60 gamma ray sources and high power electron beam accelerators has led to a continuous growth of radiation processing industry in India. Commercial viability and safe operation of these radiation-processing plants depends on accurate dosimetry. Depending on the purpose to be achieved, a widespread dose range, from few grays to few hundred kilo grays, is encountered in radiation processing technology and this necessitates the use of different dosimetry systems. In the present paper, current status of radiation processing facilities in India has been reviewed. Various indigenously developed dosimetry systems such as Alanine/glutamine (Spectrophotometric readout), FBX and ceric-cerous (potentiometry) are being used for quality assurance and routine plant dosimetry. Fricke dosimeter is used as a reference standard for calibrating other dosimetry systems. Glutamine (Spectrophotometric read out) dosimeter, used as transfer standard for Q.A. has traceability to NPL, UK and has shown an agreement within ±2% during dose intercomparisons carried out with various international standards laboratories. Performance of these dosimeters was found to be better than ±10% during dose measurements in radiation sterilization and food irradiation plants. (author)