Investigation on the sodium leak accident of Monju; Research report on the thermocouple well at the inlet of the IHX

Aoto, Kazumi ; not registered; not registered; not registered; not registered; Hirakawa, Yasushi 

This report describes the check of the thermocouple well at the inlet of the intermediate heat exchanger (IHX) of C-loop of the secondary heat tansfer system of the prototype fast breeder reactor Monju, regarding the sodium leak accident of the thermocouple well at the outlet of the IHX of the same loop of the secondary heat transfer system of the same plant Monju. Various tests and inspections were performed to check damages at the part with rapid diameter change of the thermocouple well where stress concentration may occur, and to get the information about the integrity of the welded part between the thermocouple well and the attachment. The thermocouple well, the rapid diameter change part, larger and smaller part, respectively, of the thermocouple well, and welded part between the thermocouple well and the attachments were examined as written below. (1)Accurate measurement of the dimension. (2)Vibration test by tapping the thermocouple well. (3)Non destructive testing at some points. (4)Chemical composition analysis. (5)Microscopic observation of metalogical structure. (6)Detailed observation around the rapid diameter change part. (7)Hardness test. (8)Research on corrosion at the clearance. (9)Structure strength test of the thermocouple well. (10)Bending test of the thermocouple's sheath at high temperature.