Study on Escapes Probability of Gas Bubble in Surge Tank Using Water Model Experiment

There is chance of presence of argon bubbles in the secondary sodium circuit of sodium cooled fast reactor (SFR). The source of these argon bubbles can be from the locked up gas inside the secondary sodium loop during filling. When the gas bubbles reach the surge tank, these bubbles may escape in to the cover gas plenum depending on the buoyancy and inertia forces acting on these bubbles inside surge tank. The escape probability of gas bubble is also a function of surge tank geometry. Therefore, if the escape probability of gas bubble through surge tank is sufficiently high, then over time, the secondary sodium loop will be free from re-circulating gas bubbles. In order to quantify the escape probability of circulating gas volume in the secondary sodium circuit to the surge tank cover gas plenum in prototype fast breeder reactor (PFBR), an experimental study is carried out using a 5/8 scale size geometrically similar water model of surge tank in PFBR. The transportation of argon bubbles in sodium has been simulated by injecting air bubble to water through inlet lines of surge tank. The variation of bubble escape probability inside surge tank with (i) water flow rate, (ii) with air injection rate, and (iii) bubble size are estimated.