330 Int. J. Critical Infrastructures, Vol. 1, No. 4, 2005 A future for nuclear energy: pebble bed reactors Andrew C. Kadak Department of Nuclear Engineering 24-202, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA E-mail:
[email protected] Abstract: Pebble Bed Reactors could allow nuclear plants to support the goal of reducing global climate change in an energy hungry world. They are small, modular, inherently safe, use a demonstrated nuclear technology and can be competitive with fossil fuels. Pebble bed reactors are helium cooled reactors that use small tennis ball size fuel balls consisting of only 9 grams of uranium per pebble to provide a low power density reactor. The low power density and large graphite core provide inherent safety features such that the peak temperature reached even under the complete loss of coolant accident without any active emergency core cooling system is significantly below the temperature that the fuel melts. This feature should enhance public confidence in this nuclear technology. With advanced modularity principles, it is expected that this type of design and assembly could lower the cost of new nuclear plants removing a major impediment to deployment. Keywords: pebble bed reactor; safety; economics; modularity; PBMR. Reference to this paper should be made as follows: Kadak, A.C. (2005) ‘A future for nuclear energy: pebble bed reactors’, Int. J. Critical Infrastructures, Vol. 1, No. 4, pp.330–345. Biographical notes: Dr. Kadak is presently Professor of the Practice in the Nuclear Engineering Department at MIT. He is the former President and CEO of Yankee Atomic Electric Company, a nuclear plant operator and provider of nuclear engineering and environmental services to nuclear plants.