Even with U.S. use of molybdenum-99 dropping in recent years, the nation faces a possible shortage of the crucial medical radioisotope when Canada’s National Research Universal reactor halts regular production next month, according to a new report from the National Academies of Sciences, Engineering, and Medicine.
The report also found that global efforts to minimize and ultimately end use of nuclear weapon-usable highly enriched uranium in production of Mo-99 have been somewhat halting. Observers fear terrorists would be able to breach the civilian facilities in order to obtain material to build nuclear devices.
Mo-99 decays into technetium-99m, which is employed widely in noninvasive medical imaging. About half of the global use occurs in the United States, which has not had a domestic supplier since the 1980s. A National Academies committee of experts, preparing the report under a congressional mandate, found that U.S. demand for the isotopes is down by roughly one-quarter from 2009-2010 to 2014-2015, and is unlikely to significantly rise over the next half-decade.
However, the Canadian NRU reactor from next month through March 2018 will produce Mo-99 only on an emergency basis, and then will be permanently shuttered. That leaves just six research reactors in Australia, South Africa, and Europe producing the vast majority of the isotope; five of these reactors are over 40 years old and some have already experienced unanticipated, long-term outages. The committee said there is a greater than 50 percent chance of “severe” shortages of Mo-99 and Technetium-99m after October and continuing until other suppliers carry out anticipated capacity expansions, now due in 2017.
“If all of the current producers are still in business and don’t have anything that closes them down, then we’ll be OK, because basically with the Canadian production coming offline, that takes us down just about to the level of what people need,” committee Chairman James Adelstein, a medical biophysics professor at the Harvard Medical School, said in an interview on Monday. “But if any one of the other ones go down, then we’ll be in a little bit of trouble.”
The panel recommended the United States work with Canada to ensure “an executable and well-communicated plan in place” to resume NRU production of the isotope after October if needed. It also took note of financial support from the U.S. Department of Energy’s semiautonomous National Nuclear Security Administration for development of a domestic supply of Mo-99 from five U.S. companies. Three of those – General Atomics, NorthStar Medical Radioisotopes, and SHINE Medical Technologies – are making progress toward commercial-scale output, but significant domestic supplies of Mo-99 are not likely before 2018, the report says.
All of the U.S.-based suppliers would use non-HEU methods to produce the isotopes, Adelstein noted. Four international Mo-99 suppliers, though, still use the weapon-grade material in production, and 75 percent of the global supply is manufactured using targets with uranium enriched to greater than 90 percent uranium-235. The majority of that HEU originates in the U.S., though the Obama administration has prioritized weaning U.S. and foreign reactors off weapon-grade uranium.
The four HEU-using isotope producers are making “uneven progress” toward meeting their commitment to shift away from the material, the committee found.
Ongoing availability of Mo-99 made with HEU targets is another complication, the report says. The global supply of the isotope produced with low-enriched uranium remains larger than demand.
“As long as there’s some HEU material around there’s a cost advantage of sticking with HEU,” Adelstein told Nuclear Security & Deterrence Monitor. “So I think that they’ve dragged their feet a little bit just on the basis of what the cost will be. But I don’t know directly for why they’ve been a bit slow other than that the conversion is expensive and requires a certain amount of lead time.”
The National Academies committee recommended that stakeholder governments further encourage broader use of Mo-99 and technetium-99m manufactured without HEU targets and to address the proliferation threat posed by HEU-laden waste from past isotope production.
Specifically, the U.S. Centers for Medicare & Medicaid Services should continue to offer a $10 bonus reimbursement for technetium-99m produced from non-HEU sources until there is no more HEU-made Mo-99 on the market, and quicken the pace of retrospective analysis of medical procedure expenses that use the isotope made without HEU, the committee said. It also urged the NNSA to make HEU targets unavailable commercially in order to speed the transition to LEU, potentially by repurchasing U.S.-origin HEU in raw or target form from global Mo-99 suppliers once output of LEU targets is set.
