ORNL to produce plutonium-238 for space program

February 18, 2001

By Frank Munger, Knoxville News-Sentinel senior writer

OAK RIDGE -- Oak Ridge National Laboratory has been tabbed for a new role in the U.S. space program -- producing and processing plutonium-238 for power-generating systems aboard spacecraft -- but there's still the question of funding.

In one of his last acts before leaving office last month, Energy Secretary Bill Richardson signed the record of decision for the program to re-establish a domestic source of the nuclear material for space exploration. The notice was published in the Jan. 26 Federal Register.

For the past decade, the United States has supplied its needs by purchasing plutonium-238 from Russia. The current contract expires next year, and the existing U.S. inventory is expected to run out in 2005.

Based on plans approved by the U.S. Department of Energy, ORNL's High Flux Isotope Reactor would share the role of producing the plutonium -- along with a DOE reactor in Idaho -- and other Oak Ridge facilities would be used to extract and purify the plutonium-238 after it comes out of the reactors.

ORNL facilities also would be used to prepare the targets of neptunium-237, which are irradiated in reactors to create the plutonium isotopes.

"We're very anxious and very enthused," said Bob Wham, program manager at ORNL's Radiochemical Engineering Development Center, where the plutonium processing would be conducted.

Before that work can be done, however, the Oak Ridge lab must prepare two unused "hot cells" -- heavily shielded enclosures -- at REDC, which is adjacent to the High Flux Isotope Reactor.

The project to equip and configure the facilities for the plutonium work is expected to cost up to $40 million, and that money has not yet been approved by Congress. In fact, it's not clear at this point whether any money for the project will be included in the Bush administration's initial budget proposal for fiscal 2002. That budget is to be submitted to Congress in early April.

"We're crossing our fingers," Wham said. "There's a general sense that it will get support."

No timetable for plutonium production has yet been set, but if the United States wants to have a domestic supply available in 2006, or thereabouts, then preparations would need to begin in the near future.

Plutonium-238 is different from its highly fissionable nuclear sister, plutonium-239, which is used in nuclear weapons, but the two isotopes share the same dangers if ingested or, particularly, if inhaled. The radioactive material must be handled in sealed quarters to protect workers.

Oak Ridge workers will use remote manipulators to process and purify the plutonium in the hot cells, which have concrete walls 41/2 feet thick.

"The containment system is formidable," Gordon Michaels, the lab's nuclear technology chief, said recently.

Plutonium-238, which has a half-life of 87.7 years, is the isotope of choice for space missions because of its heat-producing capabilities. Some configurations can reach temperatures of 1,000 degrees Celsius, according to a DOE information sheet.

The plutonium role is expected to mean long-term work for about 70 people at ORNL.

Michaels said it would help solidify the lab's nuclear mission and provide "an interesting and challenging scientific operation" for the staff.

The plutonium work will not compete with existing research operations at the High Flux Isotope Reactor or interfere with other lab activities, officials said.

After Oak Ridge workers have extracted and purified the plutonium, the nuclear material will be shipped to Los Alamos National Laboratory in New Mexico -- where it will be formed into pellets used in the space power systems.

The iridium cladding for the fuel pellets also is made at ORNL. That cladding is designed to protect the plutonium and keep it intact under almost any conditions, including a major explosion.

Frank Munger may be reached at 865-482-9213 or twig1@knoxnews.infi.net.



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