CFD analysis to ascertain the effect of DG exhaust on AHX performance of PFBR

During post shutdown and/or with the loss of normal heat sink, the core decay heat is removed by Safety Grade Decay Heat Removal System (SGDHRS) in Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, India. SGDHRS removes decay heat from the core and dissipates it into the environment with the help of two types of Air Heat Exchangers (AHXs). The total four AHXs are placed at four corner of Reactor Control Building, on the roof of Steam Generator Building. A tall stack provides the driving force for the natural convection of air flow through the AHX. The AHXs are surrounded by various reactor utility buildings along with four DG sets, with two DG sets on each corner of the reactor control building. One of the concerns for licensing of PFBR is that flue gases coming out of DG exhaust chimneys may affect the heat removal performance of AHX. In the present paper, a CFD analysis was carried using CFD-ACE+ out to evaluate the effect of DG set exhaust on heat removal capacity of AHXs. Two most acute wind conditions (north-west corner and northeast corner) of wind with respect to PFBR location (analysis domain) were considered for this analysis. It was observed that the exhaust flue gases from the proposed location of DG sets have very negligible effect on performance of AHXs. (author)