An electrical method for the early detection of sodium leaks

The development and performance of a simple electrical method for the early detection of sodium leaks is described. The basis of the method is to wrap the pipework or vessel in sections with a current-carrying electric cable insulated from the pipework by a material pervious to sodium. The pipework is earthed and the earth leakage current is continuously monitored using a conventional earth leakage circuit breaker. In the event of a leak sodium will encounter the conductor and a current with flow to earth. The current trips the detector and operates a relay which can sound an alarm and indicate the section of the rig where the fault is located on a mimic diagram. The system, which has been in use on experimental facilities for several years, is capable of detecting a leak of 2g Na in 20 sec. The same cable can be used for trace-heating. (U.K.)