Investigation of Aerosol Mass and Number Deposition Velocity in a Closed Chamber

Abstract

In the event of a core disruptive accident in a sodium cooled fast reactor, the Reactor Containment Building (RCB) is bottled-up with coolant (sodium), fuel and fission product aerosols. The aerosols suspended in the closed environment undergo coagulation and gravitational settling. Sodium aerosols are generated by combustion, while fission product aerosols are generated by vaporization and condensation, with the resulting particles having two flow regimes. It is expected that the mass concentration of sodium aerosols is relatively high, on the order of a few g/m 3 , while that of the fuel and fission products is only a few mg/m 3 . Taking into account the concentration criteria, experiments are carried out by generating sodium aerosols (mono dispersed) with the concentration of 3.0 g/m 3 , and the deposition velocity over time is determined by mass measurements (concentration and flux). Similarly, non-radioactive species of SrO 2 aerosols are generated (mono dispersed) with a number concentration of 10 6 /cm 3 , and their deposition velocity over time is determined by number measurements (concentration and flux). The mass deposition velocity of sodium aerosols was found to be more than two orders of magnitude greater than the number deposition velocity of SrO 2 aerosols. As the SrO 2 aerosols are generated in the free molecular regime, the depletion pattern of the number concentration of suspended aerosols follows a process of simultaneous coagulation and settling. A theoretical formulation for the rate of depletion of the number concentration is developed, and the rate coefficients of coagulation and deposition velocity are determined from the theoretically fitted equation. The experimental and theoretical results are compared and found to be nearly same. The deposition velocity of sodium aerosols is used to predict the deposition time for the suspended aerosol mass concentration inside the RCB. The mass and number deposition velocities are determined by using a state of art Turn Table Instrument fabricated in our lab.

Study on characterization of SrO Aerosols Generated by Optimized Thermal Plasma Torch Aerosol Generator

“…The initial GSD increases due to various aerosol processes, viz., source accumulation, coagulation, and agglomeration.At a later period, with the progress of time, as the concentration began to reduce one order less (after 25 min), it remained almost constant due to negligible agglomeration. The number concentration and initial size distribution of aerosols generated by PTAGS are in agreement with values measured by other works(Misra et al, 2013;Subramanian et al, 2009).The experiments were repeated a few times to check the results reproducibility and data presented in Table5. The total aerosol concentration measured using SMPS ranges from 4-6*106 cm-3 with an average value of 4.8*10 6 cm − 3 .…”

Characterisation of Sodium Aerosol in Cover Gas Region of SILVERINA Loop

“…The sampling of sodium aerosols is accomplished by (i) drawing aerosols from the cover gas region, (ii) trap them in a suitable medium without exposing them to the atmosphere, and (iii) analyze the trapped aerosols for its characteristics (Amit et al, 2014). The technique has been qualified in Aerosol Test Facility (Baskaran et al, 2004;Misra et al, 2012) and validated in SILVERINA loop facility.…”

Development and Validation of a Methodology for Characterization of Sodium Aerosols in Cover Gas Region

“…The methodology for characterization of sodium aerosols is developed in Aerosol Test Facility (ATF) (Baskaran et al, 2007;Misra et al, 2012). The methodology involves: (i) aerosols are drawn from the region above sodium pool and allowed to get trapped in liquid paraffin oil medium without exposing them to atmosphere, (ii) determination of mass concentration by using conductivity measurement technique and (iii) determination of size distribution by using Malvern Mastersizer.…”