Post-accident air leakage analysis in a nuclear facility via T-method airflow simulation

This paper explains application of the T-method for calculating air leakages and pressure differentials in a nuclear facility following a Design Basis Accident (DBA). The nuclear facility ventilation systems are designed to maintain confinement of airborne radioactive material during normal operation and after a DBA. The confinement is achieved by maintaining the negative pressure below the outside atmospheric pressure. The ventilation exhaust capacity, required to maintain negative pressures in the facility during normal operation, is estimated using building components leakage data. However, following a DBA, the ventilation system equipment, ductwork, shielding windows, doors, etc. may be damaged and create new leakage paths. The system designer needs to know the exhaust airflow capacity required to maintain radioactive material confinement in the facility following a DBA. The T-method is a new computational tool for hydraulic networks optimization and simulation. Simple numerical computation in conjunction with airflows, pressures, and fan characteristics simulation for a complicated tree-network makes this method an efficient tool for studying air leakage flows and pressure in a facility following a DBA