Design and analysis of a new passive residual heat removal system

• An air cooling passive residual heat removal System (PRHRs) is designed.
• Using RELAP5/MOD3.4 code to analyze the operation characteristics of the PRHRs.
• Noncondensable gas is used to simulate the hydrodynamic behavior in the air cooling tower.
• The natural circulations could respectively establish in the primary circuit and the PRHRs circuit.
• The PRHRs could remove the residual heat effectively.

The inherent safety functions will mitigate the consequences of the accidents, and it can be accomplished through the passive safety systems which employed in the typical pressurized water reactor (PWR). In this paper, a new passive residual heat removal system (PRHRS) is designed for a typical nuclear power plant. PRHRS consists of a steam generator (SG), a cooling tank with two groups of cooling pipes, an air-cooling heat exchanger (AHX), an air-cooling tower, corresponding pipes and valves. The cooling tank which works as an intermediate buffer device is used to transfer the core decay heat to the AHX, and then the core decay heat will be removed to the atmosphere finally. The RELAP5/MOD3.4 code is used to analyze the operation characteristics of PRHRS and the primary loop system. It shows PRHRS could remove the decay heat from the primary loop effectively, and the natural circulations can be established in the primary circuit and the PRHRS circuit respectively. Furthermore, the sensitivity study has also been done to research the effect of various factors on the heat removal capacity.