The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of decay to an array of thermoelectric elements. The GPHS is fabricated using an iridium-alloy to contain the fuel pellet. GPHS capsules will be utilized in the upcoming Cassini mission to explore Saturn and its moons. The physical integrity of the girth weld is important to mission safety and performance. Because past experience had revealed a potential for initiation of small cracks in the girth weld overlap zone, a nondestructive inspection of each capsule weld is required. An ultrasonic method was used to inspect the welds of capsules fabricated for the Galileo mission. The instrument, transducer, and method used were state of the art at the time (early 1980s). The ultrasonic instrumentation and methods used to inspect the Cassini GPHSs was significantly upgraded from those used for the Galileo mission. GPHSs that had ultrasonic reflectors in excess of the reject specification level were subsequently inspected with radiography to provide additional engineering data used to accept/reject the heat source. This paper describes the Galileo-era ultrasonic instrumentation and methods and the subsequent upgrades made to support testing of Cassini GPHSs. Also discussed is the data obtained from radiographic examination and correlation to ultrasonic examination results.
Nondestructive inspection of General Purpose Heat Source (GPHS) fueled clad girth welds
Space technology and applications international forum - 1998 ; 1998 ; Albuquerque,New Mexico (USA)
AIP Conference Proceedings ; 420 , 1 ; 1429-1434
1998-01-15
6 pages
Conference paper
Electronic Resource
English
Nondestructive Inspection of General Purpose Heat Source (GPHS) Fueled Clad Girth Welds
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