The ERHRAC computer code is a special computer code developed by Nuclear Power Institute of China (NPIC).

ERHRAC can be used to analyze and calculate the following natural circulation flow characteristics of ERHR system for AC600/1000 PWR:

— The steady state and transient thermal hydraulic behaviour of primary coolant loop, secondary side cycle of SG and air cycle;

— Start-up mode research of triggering natural circulation flow, specially for secondary side cycle of SG;

— The conditions for establishing natural circulation flow and residual heat removal ability.

Emergency residual heat removal (ERHR) system of China advanced AC600/1000 PWR NPP China consists of a tandem three-loop system including primary loop, secondary side cycle of SG and air cycle. After accident such as station black out, the decay heat of reactor core can be removed to atmosphere by natural circulation flow through the mentioned three cycles.

PCCAC-2D, 3D are special two and three dimension computer codes developed by NPIC.

The containment of AC600/1000 is a two-shell structure. Between inner steel shell and outer reinforced cylindrical concrete shell, there is a baffle to form an annular wind channel. In the top of containment, there is a large water storage tank that can meet the requirement of 72 hours water spraying on the steel shell after LOCA.

PCCAC-2D, 3D can be used to predict the pressure and temperature of mixing gas in the containment after the accident of primary pipe rupture or main steam line rupture. The heat removal characteristics from inside containment to atmosphere through the water film on the out surface of steel shell and natural circulation flow of air can be also simulated and calculated by PCCAC-2D or PCCAC-3D.

ERHRAC and PCCAC computer codes will be verified and improved through use of experiments done in NPIC facilities.