Sodium leak and combustion experiment-II report; Evaluation result of damage of mild steel liner

Aoto, Kazumi ; not registered; Hirakawa, Yasushi 

Several material analyses on damage of the floor liner made of a mild steel which was in the test cell of the second sodium leak and combustion experiment (Test-2) performed in OEC/PNC on June 7 in 1996 were carried out to clarify the following issues. (1)Difference of the corrosion mechanism of Test-2 liner to that of the first sodium leak and combustion experiment(Test-1) liner. (2)The vital factor which can desides corrosion mechanism and damage location. The following analyses were accomplished. (a)Microstructure observation (b)EPMA for cross-section of vicinity of corroded area (c)X-ray diffraction(XRD) for the interface between corrosion product-liner(mild steel) The differences between the corrosion mechanism of Test-1 liner which is seemed to be the same that of "MONJU" liner and that of Test-2 liner is discussed based on the results of these material analyses. As the result, the Na-Fe double oxidization with mechanical/chemical removal of reaction product can be occurred on the Test-1 and "MONJU" liner. On the other hand, a hot-corrosion, taht is the molten salt type corrosion is subject to be thinning of the Test-2 liner. All failures of Test-2 liner surround at the halfway up a convex. Considering the above corrosion mechanism, that fact leads that significant damage is occurred at the molten salt level.