Experimental study on thermo-chemical phenomena during interaction of limestone concrete with liquid sodium under inert atmosphere

Sodium leak in fast breeder reactor, either from pipe in inert equipment cells or inside the reactor cavity may come in contact with the limestone sacrificial layer on structural concrete. Experimental studies are carried out to investigate thermal and chemical impact of sodium on the limestone concrete under different test conditions. Sodium pool is maintained at different temperature on the test blocks placed in leak tight test chamber. The temperatures at different locations, pressure, release of hydrogen and oxygen gas are monitored online during the experiments. On-set time and residence period for energetic thermal transients (ETT) along with peak and average heat generation rates are evaluated. Chemical parameters such as rate and extent of water release from concrete, sodium consumption, sodium hydroxide production and sodium emission into argon atmosphere are also elucidated. Preliminary analysis of test results revealed that when hot sodium at 500 °C reacts on cold concrete block, it monotonically cools down with low degree of interaction. However, supply of external heat to sodium pool triggers considerable reaction with or without occurrence of ETT phase.