NSE - Nuclear Science & Engineering at MIT


Accident tolerant fuel development for LWRs

Within the core of a PWR, uranium fuel is configured in about 50,000 pins. Each pin consists of short, stacked pellets of UO2, encapsulated in a 4 meter long, 1 cm in diameter tubular cladding. The cladding is the first safety/pressure boundary containing the radioactive nuclear elements and conducting heat from the fuel to the primary coolant. The nuclear properties of zirconium alloys make them good cladding materials during normal operation, but Zr reacts with water producing hydrogen gas. Above 1200°C, this reaction is exothermic and autocatalytic. Safety and economic features of alternative cladding options are being assessed, such as ceramic composites of SiC and surface modifications of Zr tubes. Effects of irradiations of candidate options in the MIT reactor as well as kinetics of their reactions with water and high temperatures steam are being examined. It has been confirmed that the kinetics of reactions with water and steam up to 1500°C are 3 orders of magnitude smaller than zircalloys.


  1. David Carpenter, Gordon Kohse and Mujid Kazimi, An Assessment of Silicon Carbide as a Cladding Material for Light Water Reactors, MIT-ANP-TR-132, November 2010.
  2. J. P. Dobisesky, D. Carpenter, E. Pilat, and M. S. Kazimi, "PWR Cores with Silicon Carbide Cladding," Advances in Reactor Physics (PHYSOR), Knoxville, Tennessee, April 2012.
  3. X. Sheng and M. S. Kazimi, "Assessment of Different Fuel Design Options with SiC Cladding for Light Water Reactors," the International Congress on Advances in Nuclear Power Plants (ICAPP 2012), Chicago, Illinois, June 2012.
  4. Y. Lee, C. Yue, R. P. Arnold, T. J. McKrell, and M. S. Kazimi, "Oxidation of SiC Under Loss of Coolant Accident (LOCA) Conditions in LWRs," the International Congress on Advances in Nuclear Power Plants (ICAPP 2012), Chicago, Illinois, June 2012.
  5. John D. Stempien, David M. Carpenter, Gordon Kohse, and Mujid S. Kazimi, “Characteristics of Composite Silicon Carbide Fuel Cladding After Irradiation Under Simulated PWR Conditions”, Nuclear Technology, to appear July 2013.

Department of Nuclear Science & Engineering

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