Development of an electrical connector for liquid sodium environment; Final report

; ; ; Miyakawa, Shunichi

PNC TN9410 98-076, 89 Pages, 1998/07

PNC-TN9410-98-076.pdf:8.52MB

The INstrumented irradiation Test Asembly (INTA) has been used to conduct precision on-line instrumented irradiation tests in the experimental fast reactor JOYO. In INTA, direct instrumentation wiring between the irradiation test section in the core and the upper structure section in the rotating plug makes INTA structurally complex and expensive. Instead of direct wiring, if an electrical connector capable of withstanding a heated liquid sodium environment could be used between the irradiation test section and the upper structure section, the upper mechanism of INTA could be reused and testing costs would be drastically reduced. Moreover, the reactor load factor would be improved because of reduced handling time for INTA. In an attempt to gain this advantage, research and development of an electric connector in a sodium environment was carried out from 1988 to 1996 at PNC. As no previous R&D had been conducted in this area, this development activity was conducted in a boot strap manner. The first test was carried out for a small model fabrication, the second was for a water partial model, and the third was for a sodium partial model. Based on those tests, a prototype design specification of the connector was determined. In the sodium partial model test, the resiliance of the electrical connector insulation to the sodium environment was investigated. However, severe cracking in the ceramic insulator caused by the high temperature sodium environment was discovered at the junction of ceramic insulator and metallic electrode. This was recognized to be a critical problem because the boundary on the structure could not be secured. To address the problem, additional sodium partial tests were performed for various material combinations of ceramic insulators, metallic electrodes, brazing materials and metallization materials. However for insulator cracking, the results of the tests were unsatisfactory. After all although the newest technology of main ceramics ...