Study on performance evaluation of self-actuated shutdown system for sodium-cooled fast reactor; Measurement of flow field around temperature sensing part

Hiyama, Tomoyuki ; Aizawa, Kosuke ; Kobayashi, Jun ; Kurihara, Akikazu ; Nagasawa, Kazuyoshi*; Onuma, Hideyoshi*

The self-actuated shutdown system (SASS) is a device that passively detach the control rod in response to a temperature rise at the reactor core outlet by utilizing the property that the magnetism of a temperature sensing part disappears as the temperature rises. It is adopted in the advanced sodium-cooled fast reactor designed in Japan. In order to function the SASS effectively, it is important to efficiently guide high temperature fluid from the fuel assembly to the temperature sensing part, so the circumstance of temperature sensing part has a complicated shape such as fins. In order to improve the SASS performance evaluation method, we plan to carry out the full-scale experiment to understand phenomena and acquire data for code validation. In this report, the water experiment was performed on the full-scale model that simulates from the outlets of the fuel assemblies to the SASS flow collector, and flow phenomena around the temperature sensing part was analyzed from the data obtained by PIV measurement.