The purpose of this study is to develop a new BWR fuel with high critical power and low pressure drop performance. In this report, the spacer which has a significant effect on thermal hydraulic performance, has been improved and the performance has been measured. The improved high performance spacer is a ferrule type spacer with twisted tape and improved flow tab. This spacer is called CYCLONE spacer.
The test bundle consists of electrically heated rods in a 4×4 array configuration. The axial power shape is cosine. Two test assemblies with different radial power distribution have been used. One test assembly has the maximum power rods at the center of the test assembly and the other has the maximum power rods near the channel wall.
The results show that the critical power performance of the bundle with CYCLONE spacers is 10 to 22% higher than that of the current bundle with ferrule spacers at BWR rated flow rate, while the pressure drop is about 3% higher at BWR rated conditions (quality 15%).
