Retrofit of radioactive waste capability to an operating nuclear power station. Indian experience

Initial years of operation of BWR type of Tarapur Nuclear Power Reactor indicated a need for a review of radwaste scheme originally provided because of the large liquid volumes generated and with a view of decreasing the discharge to the environment. 200,000 gallon additional capacity tanks, two in number followed by a two stage chemical treatment plant of 60 M3/day capacity had to be provided about 1 km. away from the power station complex, because of the constraints of space and the existing support facility in the station complex. The two stage chemical treatment plant now operational since the last four years has brought down the total discharges from the station especially for Cs137 and Co60 to a value well within the technical specifications of the station. The Tarapur reactors utilising non-regenerative demineraliser resins for the clean up circuits pick up very high levels of radioactivity. The original scheme had to be modified to by-pass a centrifuge and pump the resin slurry directly to underground, stainless steel lined, concrete vaults. The change over has considerably reduced the manrem expenditure and very high radiation fields in the centrifuge area. Increased volumes and the activity of the solid wastes, particularly filter sludges and the incore components stored in fuel pool necessitated construction of engineered containers, special shielding casks and disposal facilities. The paper presents details of these retrofit measures. (author)