Nuclear Science


Heavy Actinides

Exploded view of a capsule used to ship 252Cf source material to encapsulators.

ORNL entered into the production of heavy actinides with the construction and commissioning of the High Flux Isotope Reactor (HFIR) and Radiochemical Engineering Development Center (REDC) in 1965 and 1966, respectively.  These facilities were conceived by Glenn T. Seaborg for the irradiation and production of substantial weighable quantities of heavy actinides.  The HFIR and REDC have been operated around the clock since their commissioning.  Various radioisotopes are used in the fabrication of targets at the REDC for irradiation in HFIR and the production of heavy actinides such as 238Pu, 237U, 248Cm, 249Bk, 251Cf, 252Cf, 253Es, 254Es, and 257Fm.  The REDC includes glove box laboratories, chemical laboratories, counting facilities, analytical laboratories, high bays, and heavily shielded hot cell facilities for the production of targets and processing and purification of highly irradiated materials.

ORNL has been selected as the lead site for restart of production of 238Pu in the United States.  This isotope is used to fuel the Radioisotope Thermoelectric Generators (RTGs) that provide electrical power for the equipment used in NASA’s deep space missions, such as the Mars Science Laboratory, Curiosity.

ORNL also produces ~70% of the world’s supply of 252Cf.  This unique isotope is an intense neutron source that is provided to commercial encapsulators for use in numerous applications ranging from reactor start-up sources to mineral analyzers.

Research is currently underway to investigate novel production methods for 253/254Es and 257Fm to facilitate research on these rare isotopes. This work will use various isotopes as “neutron filters” to modify the local neutron spectrum in HFIR to maximize the production of the isotope of interest. We anticipate that this technique will be applicable to the production of a number of unique isotopes.

For more information, contact:
Nuclear Security and Isotope Technology Division


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