Performance of dry electrostatic precipitator for the removal of CsI aerosol particles under simulated severe nuclear accident conditions

• ESP removed over 90 % of CsI aerosols in severe accident scenarios. • Hydrogen did not impact the ESP performance or the collection efficiency. • Filtration efficiency remained constant despite changes in humidity and temperature. • Industrial ESP unexpectedly increased the ultrafine particle number concentration. The performance of electrostatic precipitators (ESPs) in reducing the emission of radioactive aerosols and hydrogen was investigated under varying experimental conditions to improve the safety features of nuclear power plants (NPPs). The effects of gaseous atmosphere, humidity, flow rate, and temperature on particle properties and filtration efficiency were evaluated using caesium iodide as a model aerosol. The results indicate that the ESP achieved a maximum particle mass filtration efficiency of over 90 % for the lab-scale ESP and more than 99.5 % for the industrial ESP. However, the particle number concentration varied with the industrial ESP, highlighting effective removal of larger particles that acted as a condensation sink, allowing higher concentrations of newly formed ultrafine particles to persist in the system. Hydrogen mitigation experiments revealed no measurable impact of ESPs on hydrogen concentrations under typical operating conditions, confirming their safety within current NPP protocols. The study highlights the crucial role of particle properties, carrier gas composition, and ESP design in determining filtration efficiency, emphasising the need for further research on reactor-specific conditions to optimise ESP performance and enhance source term reduction strategies.