EAGLE project: experimental study for advanced safety of fast reactors; Progress on the out-of-pile experiments and results of the melt discharge experiment

Kamiyama, Kenji  ; Kubo, Shigenobu ; Sato, Ikkenn 

The objective of the EAGLE project is to confirm a possible scenario in the postulated core disruptive accident of sodium cooled fast reactors, in which the molten fuel discharging from the core region in the early stage of the accident with its inherent mechanisms would prevent energetic re-criticalities. In order to obtain necessary experimental data, in-pile and out-of-pile experiments utilizing facilities of National Nuclear Center in the Republic of Kazakhstan were planed and are currently carried out. This document reports progress and results of the out-of-pile experiments which consist of a part of the EAGLE program. In the out-of-pile program so far, a series of experiments has been carried out aiming at establishment of basic necessary technology which consists of melting of the fuel-simulating material using the induction heating, transferring it into the test section and measuring the related phenomena during the experiments. Following knowledge and results have been obtained so far: - Using uranium dioxide and alumina as candidate materials for fuel simulant, basic experimental technology has been established, and fundamental data of molten material discharge were obtained under the condition without sodium. - With uranium dioxide, certain efforts, such as providing carbonized metal coating on the crucible inner surface, have been made to prevent chemical reaction between uranium dioxide and the graphite crucible so as to obtain molten uranium dioxide without a great deal of unfavorable impurities which prevent reasonable simulation of the real fuel behavior. It was concluded, however, that present techniques did not allow molten uranium dioxide with sufficient grade. - Alumina, which has well-known thermophysical properties, was evaluated to have adequate characteristics in terms of simulating real molten fuel behavior. Through implementation of the experiments, it was confirmed that molten alumina with sufficient purity and characteristics could be g