Revision of discharge limit of gross beta activity to the aquatic environment based on public dose estimation

Abstract

Low-level liquid effluents generated from Regional Centre, Board of Radiation, and Isotope Technology (BRIT), Delhi, are generally discharged to the aquatic environment after suitable treatment (delay, decay, and dilution for short-lived radionuclides) conforming the regulatory compliance as authorized by Atomic Energy Regulatory Board, Mumbai. The Regional Center, BRIT-Delhi is generating the liquid effluents containing short-lived radionuclides 99Mo (T1/2−66.7 h) and 99mTc (T1/2−6.02 h) and also long-lived radionuclide 99Tc (T1/2−2.13 × 105 years) from the production of ready to use 99mTc-radiopharmaceuticals as human injectable product. This liquid waste generated during the washing of radioactive contaminated glassware is inorganic in nature and is stored in 02 number of sump tanks (capacity 50 m3 each) for delay and decay of short-lived radionuclides. The center has also planned to produce and supply 68Ga radiopharmaceuticals in future. There is a possibility that some of these radionuclides may reach the drinking water by various natural pathways. The presence of radionuclides in the drinking water above certain level may result in radiation dose to the public through the ingestion pathways. The observance of prescribed radionuclide concentration in waste water, total activity limits, and other basic safety requirements stipulated by the regulatory body help to minimize the public radiation dose. This article is an effort to derive the annual discharge limit for gross β activity at Regional Center, BRIT-Delhi to the aquatic environment of an inland site based on the drinking water standard limits prescribed by the World Health Organization. This article also discusses the effective dose received by the actual discharge of radioactive liquid effluent from the Regional Center, BRIT-Delhi.