Nuclear Science


Irradiation Experiment Development and Execution

Small format "rabbit" irradiation capsule containing test specimens to support the fusion energy program

Because materials and nuclear fuel properties change as they undergo neutron irradiation, quantification of these changes under prototypic conditions is critical for assuring the safety of operating fission reactors, for developing advanced fission reactor concepts, and for designing fusion devices. Research reactors such as ORNL's High Flux Isotope Reactor allow material and fuel samples to be studied under prototypic temperatures and neutron spectrum while greatly accelerating the material changes due to their high neutron flux. Irradiation Engineering is the science and technology of designing, fabricating and operating experiments that characterize the property changes of materials and fuels under irradiation conditions.

Oak Ridge National Laboratory maintains multiple laboratories and a staff of highly skilled specialists  supporting this specialization. The experimental design process utilizes state-of-the-art software such as Pro-Engineer, ANSYS and RELAP5 to develop the mechanical design of the experiments, assures that experimental operating goals are met, and confirms that the experiment can be safely irradiated in the research reactor.

Technicians fabricating irradiation capsules.

Supporting facilities include the Capsule Assembly Laboratory, where the experiments are fabricated and assembled under stringent QA requirements, and the Materials Irradiation Facility (MIF), where instrumented capsules can be monitored and controlled real time during irradiation. Three typical experimental formats are used: the smallest rabbits have an experimental test specimen volume of about 4 cm³, target capsules have a volume of about 51 cm³, and reflector capsules have an available volume of about 480 cm³. The latter two formats can be instrumented and coupled to the MIF to measure and control various experimental conditions.

For more information, contact:

Group Leader, Thermal Hydraulics and Irradiation Engineering
Grady Yoder

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