Measurement of scrubbing behaviour of simulated radionuclide in a submerged venturi scrubber

Abstract

Post Fukushima accident, the societal impact of radiological leakage to the environment necessitated further exploration and robust strategy to safeguard the nuclear reactor containment. In view of this, design of Filtered Containment Venting System (FCVS) plays an important role in depressurizing the reactor and preventing release of radionuclides to the environment. In this context, a venturi scrubber submerged in alkaline solution along with demister pad housed in a scrubber tank is investigated experimentally at prototypic conditions for retention of iodine vapors in the scrubber system. The hydrodynamics and the scrubbing performance of the submerged venturi scrubber is simulated at air flow rates of 1500–3500 lpm at the submergence height of 4 m. The iodine concentration retained in the scrubber tank and its bulk decontamination is measured by ICP-OES and ICP-MS analysis respectively.It is observed that the overall pressure drop in the venturi scrubber increases with an increase in flow rate. The two phase axial pressure drop characteristics reveal an increase in the pressure drop in the converging section with increase in flow rate. The pressure drop also increases after the scrubbing liquid from the hydrostatic pool is suctioned and no recovery is found in the diverging section of the venturi scrubber. The iodine retention in the scrubber tank increases sharply with an air flow rates up to 2200 lpm after that the increase is gradual with the maximum of 95% retention at 3400 lpm. It is seen that in all the experiments the amount of iodine leaving the facility is negligible and the bulk decontamination is high. Further, effect of submergence height on the retention of iodine vapors in the scrubber tank is compared at 3 m and 4 m. It is seen that an increase in submergence height significantly increased the percentage of iodine arrested in the scrubber tank at 1700 lpm air flow but further increase in air flow rate has lesser impact on the iodine retention in the scrubber tank despite the increase in submergence height.