WASHINGTON - Hanford's Fast Flux Test Facility won't be used to make tritium for nuclear weapons, but the Department of Energy is continuing to consider a role for the reactor.

The department will decide in April whether there are enough other missions to justify keeping FFTF open, Energy Secretary Bill Richardson announced Tuesday. That could include making medical isotopes to treat cancer and other diseases.

Richardson selected the Tennessee Valley Authority's Watts Bar reactor, with its Sequoyah reactor as a backup, to meet the nation's tritium needs. They would produce the radioactive gas, used to boost the power of nuclear weapons, in addition to producing electricity.

It was the cheapest alternative, Richardson said.

Under the plan, the FFTF would not be needed as an interim or backup source of tritium for the TVA's reactors.

"After looking at all the options, I have decided FFTF will not play a role in producing tritium," Richardson said at a news conference. "I will decide on any civilian missions for FFTF by spring." Supporters of restarting the FFTF for a tritium mission in combination with a medical isotope or other mission said they were disappointed Tuesday.

U.S. Rep. Doc Hastings, R-Wash., said he hoped the decision would make "a small group of people on the fringes" consider how the reactor could be used to save lives with a mission of producing medical isotopes.

"This opens the door to use of the FFTF for the production of medical isotopes without complicating it with the mission of weapons material (production),"said Dave Jones, co-chairman of the Nuclear Medicine Research Council.

"Technically, it could be done, but there seemed to be a lot of political opposition," he said.

The next step for restarting the FFTF, now on standby, would be a decision this spring to prepare an environmental impact statement.

Among the possibilities for its future are producing plutonium 238, which would be used to power the engines of spacecraft, and producing medical isotopes used to diagnose and treat some diseases. FFTF also could play a research role in the development of fusion reactors, next-generation light water reactors and space reactors.

But first, the department wants to look at how all its existing facilities and infrastructure will match up with DOE's science and technology programs over the next 20 years.

Richardson said FFTF will be included in a study on that currently under way by a task force headed by William D. Magwood IV, director of the department's Office of Nuclear Energy, Science and Technology.

"We are developing a road map," Magwood said after Richardson's news conference.

Magwood said FFTF has been used for research in the past and it would be appropriate to consider it for a future research role.

When the FFTF was put on standby in 1993, DOE said it had enough existing and planned research reactors to meet its needs. Since that time, however, the department has closed two research reactors in Idaho and abandoned planned development of a third at Oak Ridge, Tenn.

"FFTF has proven it can fulfill the type of research operation the secretary has talked about," Magwood said. "The only question is whether DOE has a need for a facility of that size.

"The secretary very easily could have made a decision to deactivate it," Magwood said. "The people in the Tri-Cities should be reassured we are on a clear decision-making path." Richardson said he picked the two TVA light water reactors because they would provide flexibility in supplying tritium, they rely on a proven technology and their production costs would be less.

"It's the only option that doesn't require a large capital expenditure,"he said. "If our goal of reaching further arms reduction agreements is reached, we may not need to exercise this option for many years, and we will pay for tritium only when it is needed." Although there has been criticism of mixing civilian and mili tary use in the reactors, Richardson said, "The TVA is well-suited for this work because meeting national security needs is part of its statutory charter and its reactors are government facilities." Also under consideration was building a new linear accelerator at Savannah River, with the FFTF possibly playing an interim production role. Although the accelerator may have used more advanced technology, Richardson said the cost of building one is prohibitive.

Richardson declined to say exactly how much the various options would cost but added the TVA reactors were "by far the cheapest." The department will continue to fund research and development of an accelerator as a backup to the tritium-producing reactors, but there are no plans to actually build one, he said.