Nodalization studies supporting modeling of a passive heat removal system in the advanced neutron source reactor

The conceptual design of the Advance Neutron Source (ANS) reactor developed by Oak Ridge National Laboratory (ORNL) employs passive emergency heat exchangers. The emergency heat exchanger is immersed in a water pool, and the secondary side is arranged so that cold water from the pool enters at the bottom of the heat exchanger and returns to the pool via a tall chimmney at the exit of the secondary. Buoyancy forces establish the circulation necessary for the heat exchanger to remove heat to the water pool. The RELAP5/MOD3 code[sup 1] is being used to model the ANS system performance during transients and accidents.