News Archives

• Dissertation Defense: Composite Nuclear Fuel Fabrication Methodology for Gas Fast Reactors, Gokul Vasudevamurthy
  Tuesday, November 27, 2007, 9 am, Room 1A20 - Swearingen Bldg.
  
  Dissertation Director: Dr. Travis W. Knight
  Members : Dr. Jamil Khan, Dr. Anthony Reynolds, Dr. Elwyn Roberts
  External Member: Dr. Thad Adams (SRNL)
  Graduate Studies Representative: Dr. Jeff Morehouse
  
  Abstract
  An advanced fuel form for use in Gas Fast Reactors (GFR) was investigated. Criteria for the fuel includes operation at high temperature (~1400∞C) and high burnup (~150 MWD/MTHM) while retaining fission products even during transient with temperatures in excess of 1600∞C and contain up to 20% of heavy metal content as transuranics for a closed fuel cycle. Earlier evaluations of reference fuels for the GFR have included ceramic-ceramic (cercer) composite fuels of mixed carbide or nitride microspheres coated with SiC in a SiC matrix. The present work investigated natural uranium carbide microspheres in a ZrC matrix due to its potential for very high temperature operations exceeding that of SiC.
  
  Known issues of minor actinide volatility during traditional fabrication procedures necessitated the investigation of still high temperature but more rapid fabrication techniques to minimize these anticipated losses. Fabrication of the ZrC matrix by combustion synthesis from zirconium and graphite powders was studied. Criteria were established to obtain sufficient matrix density with UC microsphere volume fractions up to 30%. Using similar techniques, UC compacts were studied to fabricate electrodes for use in a rotating atomization procedure to create microspheres of UC. Tests involving production of microspheres by spark erosion method (similar to electrodischarge machining) showed that this method was not suitable for UC microspheres in the desired range of 300 to 1200 mm. A rotating electrode device was developed using a minimum current of 80A and rotating at speeds up to 1500 rpm to fabricate microspheres between 45 and 1200 mm. Fabrication of the cercer composite form was studied using microsphere volume fractions of 10%, 20%, and 30%. The microstructure of the composite and individual components at various stages was characterized to understand the required fabrication techniques and meet the necessary GFR fuel characteristics.
Seminar: The Roll of the Young Professional in the Nuclear Renaissance, John Hosmer, Sr. Vice President, UniStar Nuclear Operations
October 18, 2007, Green Quad Rooms 102/103, 12:30 to 2 pm

Pizza and soft drinks served.