SUMMARY

The Integral Inherently Safe Light Water Reactor (I2S-LWR) is a large (2850 MW) pressurized water reactor that includes primary-to-secondary coolant heat exchangers located in the downcomer of the reactor pressure vessel. This integral configuration, which is often reserved for lower power reactors, eliminates the possibility of large line-break accidents, reduces primary coolant inventory, and does not require large external steam generators. A microchannel heat exchanger (MCHX) configuration is selected to meet the limited volume and high heat duty requirements of this design. The steady-state thermal-hydraulic performance of a liquid-liquid and liquid-boiling (steam generating) MCHX are modeled using empirical correlations from the literature and the designs are optimized to meet the I2S-LWR requirements. A test facility and a representative MCHX test section were constructed to validate the assumptions and modeling techniques used in the I2S-LWR MCHX design. Experimental heat duty and pressure drop are compared to model predictions. In addition, Nusselt numbers, friction factors, and other parameters are extracted from the data and compared with correlations from the literature when possible.