Sodium Voiding in an Annular Channel Heated by a Single Pin in Overpower Accident Simulations

摘要

In a simulation of overpower accidents affecting a fast breeder core, experiments on sodium boiling were performed in a single vertical channel of annular cross section (10.65 mm I.D.) indirectly heated by a high flux heater pin (8.65 mm O.D.). Measurements were made with a high speed acquisition system. The experimental conditions were: Pressure of cover gas: 1 kg/cm exp 2 abs, Mass Flow rate of sodium: 25 g/s, Inlet temperature: 400 exp 0 C, Steady state outlet temperature: 800 exp 0 C, Transient power supply: 90 KW up to 250 KW. For the first expulsion, the results revealed two important points: variable initial superheat with corresponding pressure pulse, and after superheat resorption, thermal conditions prevail and the boiling process followed equilibrium conditions. After heating cut off, rewetting pressure pulses were observed. (Atomindex citation 09:395523)