NRC proposes fuel ruletechnolog
The Nuclear Regulatory Commission (NRC) may soon require university reactors to remove all unused high enrichment uranium (HEU) fuel, according to the August issue of Nuclear News. The commission is concerned that terrorists could steal enough of the fuel to make a bomb.
In July of 1984, the NRC issued a Proposed Rule in the Federal Register requiring research reactors to convert to low enrichment uranium (LEU) fuel "unless there is a demonstration that the facility's unique purpose cannot be accomplished without the use of HEU." The NRC has asked its staff to prepare a final order on the issue.
A group formed by the NRC to study the issue decided that "it may be possible that a nuclear explosive could be made using LEU fuel. This appears, however, to be very difficult."
A conversion to LEU could, however, harm US research in nuclear engineering, according to the NRC group.
It is unclear when the NRC will make a final decision or how that decision will affect MIT. If the NRC required conversion, it would shut down the MIT reactor, said Lincoln Clark Jr. '63, assistant director of the reactor.
Because of its design, the MIT reactor cannot use LEU, he said.
Clark called the terrorist threat a "non-problem." Current NRC rules allow university reactors to store no more than 29 kilograms of HEU, only five of which can be unused.
"It's generally said that you'd need at least l5 kilograms of unirradiated [unused] HEU to make a bomb. I don't think we have anywhere near 5 kilograms on hand at one time .... The amount that terrorists could steal might be enough to make a small mess in your neighborhood, but not a weapon," Clark added.
Irradiated fuel must be reprocessed before it can be used to make a bomb. It is also highly radioactive and dangerous. "People would be foolhardy to steal irradiated fuel," Clark said.
Clark would not describe the measures taken to guard unirradiated fuel elements for security reasons. But he did say that they are stored "from a few days to several weeks," and that the NRC has approved MIT's security measures.
Neil Todreas '66, head of the Department of Nuclear Engineering, did not believe that conversion would reduce the risk of nuclear proliferation. "There's not much HEU stored and available. It's in the reactors," he said.
"You'd have to hit a lot of reactors at once to try to get the amount [needed] for a weapon," Todreas explained. "On the practical side I don't think the conversion makes any difference."
Institute Professor Philip Morrison commented that "it's probably much easier to steal a ready-made bomb from an arsenal" than to steal the HEU and make one.
The NRC order may only mean that MIT should remove all unnecessary HEU fuel elements because the reactor could not function with LEU. "I read the Nuclear News report to mean that we will be allowed to store three unirradiated HEU fuel elements. That's not a problem," Clark said.
Todreas said that if the NRC requires all university reactors to convert, regardless of monetary or technical feasibility, "it'll switch research from university reactors to national labs."
The cost of conversion would be too great for most universities to bear. Some reactors, such as MIT's, are not designed to use LEU and the conversion would disrupt research programs, Todreas said.
MIT spent $3 million in the late l960s and early l970s to redesign the reactor specifically for HEU use. HEU is enriched with Uranium 235, which produces a greater neutron flux than LEU.
Spectrometry and radiation effects studies at MIT require the high neutron flux produced by HEU, Todreas said.
Government reactors use 90 percent of all HEU fuel in the United States. If the NRC were to require universities to convert, "you're affecting less than ten percent of the HEU, so you're solving less than ten percent of the problem," Clark said.
Clark was a member of the LEU Study Group, which the NRC created to assess how conversion would affect universities. The group found that the MIT and Missouri-Columbia reactors are so designed that they cannot convert to LEU with existing technology.
The Department of Energy (DOE) is trying to develop low enrichment fuels that would provide the high neutron flux necessary for MIT and Missouri-Columbia. "By l989, the DOE may have developed a fuel that would make it possible to convert. If that happened, MIT would have no objections to converting," Clark said.
Clark said it was reasonable for the NRC to ask universities to minimize stored HEU. "To me that makes sense to get the inventories down to low levels to prevent anyone from trying to swipe it," Clark said.
The LEU Study Group warned that requiring all universities to convert might harm the United States standing in the field of nuclear research.
The group recommended that the federal government pay for the conversion because the costs would be so high that many university reactors would otherwise be shut down. "If you're going to put a highway through someone's backyard, then you ought to pay for it," Clark said.
The NRC has been studying the terrorist threat since l982, when it issued a Policy Statement in the Federal Register encouraging research reactors to convert from HEU to low enrichment uranium (LEU) fuel.
Meanwhile, the LEU Study Group recommended that MIT and Missouri-Columbia use medium enrichment uranium (MEU) fuel and decrease HEU traffic.