174. Pilot-scale extrusion of graphite fuel elements for HTGR

• Book ID: 102991978
• Publisher: Elsevier Science
• Year: 1965
• Tongue: English
• Weight: 134 KB
• Volume: 3
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(65)90240-x

✦ Synopsis

A method has been demonstrated for extruding graphite tubes, and other bodies with multi-hole sections, such that little or no final machining is required. Bodies 34 and 4# in. O.D. up to 4 ft long have been produced, and tubes 16 ft long have been carbonized. The critical factors in the process lie in the area of die design and alignment, extrusion temperature control, preforming the charge to a billet, and in carbonization firing. A method of adding rings that effectively increase diameter at a local area has also been developed. The rings are machined out of green stock. placed in position with a pitch interface, and carried through the carbonization step which causes the two sections to fuse together. The present stock is being made from pitch, fine graphite flour, stearic acid, and ethylcellulose, and is wet-mixed with trichlorethylene, Both pitch and resin impregnations are required to make the stock meet density, strength and permeability (<3 x 10e3 cm2/sec at 112 atm p, and R.T.) requirements.

For an application where pe~eabili~ of -5 x 10" cm'/sec is required, a fo~ulation involving a coarser graphite flour gives a stock that will require pitch impregnation only.