| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1728685 | Annals of Nuclear Energy | 2013 | 14 Pages |
Numerical studies were performed to examine the effects of flow velocities of opposing streams on the flow pattern and turbulent mixing characteristics in a three-dimensional chimney structure using CFD code PHOENICS. This chimney structure facilitates guiding of the radioactive water from the reactor core (i.e., core flow) towards the side outlet nozzles and simultaneously drawing out water from the reactor pool through the chimney top. The radioactive water flows upward and has a tendency to reach to the pool top through the chimney top which is open for fuel and isotope handling. The chimney design allows drawing out a part of the pool water in the downward direction to suppress the upward flowing radioactive water jet. This downward flow through the chimney is compensated by providing additional core bypass flow to the pool. Analyses were carried out on 1:1 chimney structure and also on 1/6th scaled down chimney model to understand the similarity of behaviour of the model and the prototype. Mass flow rate of upward flowing water (i.e. core flow) is considered to be 750 kg/s and core bypass flow is varied from 0% to 15% that of the core flow. In the model study, mass flow rate was varied from 8.33 to 25 kg/s and core bypass flow was considered to vary from 0% to 15%. Flow mixing pattern inside the chimney and the non-dimensional stagnation depth was predicted for the model and the prototype. It was observed that there is a good similarity in behaviour of the prototype and model.
► Turbulent mixing of two opposing flows inside a chimney structure was studied. ► Numerical simulation was done for full scale prototype and 1/6th scaled down model. ► Increase in upward flow decreases the stagnation depth. ► Increase in downward flow increases the stagnation depth. ► Temperature difference between flows has marginal effect on stagnation depth.
