Sodium Fire Test at Broad Ranges of Temperature and Oxygen Concentration (IV); Low Temperature Sodium Spray Fire Tests

Kawada, Koji; Matsuki, Takuo*; Miyahara, Shinya  

Sodium spray fire tests at the initial sodium temperature of 250 deg-C were conducted under the atmospheric conditions of air and 3% oxygen containing nitrogen to determine the sodium burning rate and the aerosol release fraction and compare them with the test results at the initial sodium temperature of 500 deg-C in air atmosphere.In the tests, sodium was supplied using a commercial spray nozzle into a stainless steel vessel of 100 m volume (SOLFA-2). The sodium burning rate was calculated from two independent methods : the consumption rate of oxygen in the vessel and the enthalpy change of vessel components during the test. The aerosol release fraction was determined from the comparison between the measured aerosol concentrations and the calculated ones by the ABC-INTG code. The main conclusions were as follows, (1) In air atmosphere, (a) sodium droplets ignited instantaneously and the spray fire was observed, (b) the sodium burning rate was about 440 g-Na/s and the fraction of supplied sodium was about 70%. (2) In 3% oxygen containing nitrogen, (a) ignition of sodium droplets was not observed, and (b) the sodium burning rate was about 44 g-Na/s and the fraction of supplied sodium was less than 10%.