Preliminary Experimental Study On The Resistance Characteristics Of A Wire-wrapped Fuel Assembly

As the good physical properties for heat transfer and neutronics, Lead-Bismuth Eutectic (LBE) is a priority candidate material for the coolant and spallation target for the ADS (Accelerator Driver Sub-critical System), and the Lead-Bismuth cooled reactor has become the main development direction of the fourth generation reactors Fuel assembly is the key component of a reactor and it’s related to the safety,economy and reliability of the reactor. In order to separate the fuel rods along the radial in one fuel assembly, usually there are two general system design available to choose, that’s to use wire-wrapped or grid spacer, most of the Lead-Bismuth cooled reactor f prefer to adopt wire-wrapped fuel assembly at present, Compared with the fuel assembly of pressurized water reactor, the biggest characteristic of the wire-wrapped fuel assembly is that it use wire fixed in the walls of the fuel rods replacing the traditional way of fixed, thus leading to a difference of their resistance characteristic compared with the conventional fuel assembly. And experimental study is a very effective method to grasp the resistance characteristics of the wire-wrapped fuel assembly.Based on the current situation of the experiment research on the resistance characteristic of the fuel assembly internationally and the requirement of the thermal-hydraulic design verification of reactor, a water loop was designed and built to carry out the experiment to study the resistance characteristic of a wire-wrapped fuel assembly designed in water medium based on similarity theory with Reynolds number as the similarity number, and the flow rate in the water loop can reach130m3/h and the corresponding Reynolds number reaching to about43500. Simultaneously, the experiment was carried on the China liquid lead-bismuth thermal-hydraulic experimental loop KYLIN-Ⅱ, the flow rate in the KYLIN-Ⅱ loop can reach6.3m3/h and the corresponding Reynolds number reaching to about97000.In this paper two new friction factor correlations were come up with for the wire-wrapped fuel assembly in the water and lead-bismuth, respectively. The experimental results of water loop were compared with Rehme correlation and Novendstern correlation calculated results, the relative standard deviation between experiment results and Rehme correlation calculated result was0.014, and the relative standard deviation between the experimental results and Novendstern correlation calculated values was0.007. And the relative standard deviation between experiment results of LBE loop and Rehme correlation calculated result was0.009, the relative standard deviation between the experimental results and Novendstern correlation calculated values was0.001. The experiment results of the resistance characteristic of a wire-wrapped fuel assembly obtained in this paper can provide preliminary reference for the thermal-hydraulic design verification of reactor.