Download IDNUMBER 200811170005 PUBLICATION: The Ottawa Citizen

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200811170005
The Ottawa Citizen
2008.11.17
Early
News
A1 / FRONT
VANCOUVER
Margaret Munro
The Ottawa Citizen
713
Scientists tout alternative to Chalk River isotopes;
Intense light beams seen as key to making material for
nuclear medicine
Scientists believe they have hit on "a uniquely Canadian solution" to the world's medical isotope woes.
They say intense beams of light should be able to generate isotopes for nuclear medicine, and eliminate the security
risks associated with making the medicines with weapons-grade uranium at the aging nuclear reactor in Chalk River,
Ont.
A national task force report to be released today says creating isotopes using light beams from "photo-fission"
accelerators could also help salvage Canada's reputation in the nuclear world after several misadventures.
The 58-page report, obtained by Canwest News Service, recommends the federal government back a "strong and
focused" research program to "support proof-of-principle demonstrations."
If photo-fission works, the task force says a half-dozen accelerators, which would cost upwards of $50 million each,
could supply isotopes across North America.
Twenty-four leading physicists and nuclear medicine specialists from Canada and the U.S. sat on the task force.
They describe photo-fission as a promising alternative to the two "aging" nuclear reactors in Canada and Petten, the
Netherlands, which now generate most of the world's medical isotopes.
The radioactive molecules, which are short-lived and considered harmless because they emit low levels of radiation,
are given to about 40 million people a year, 1.5 million of them in Canada. The isotopes make it possible to "see"
inside the body to diagnose heart disease, locate tumours and follow cancer and its treatment.
The 51-year-old Chalk River reactor produces almost half the isotopes used in the world. It also generated an
international crisis a year ago when the reactor was suddenly shut down over safety concerns. Tens of thousands of
people in Canada and the U.S. had heart and cancer tests cancelled because of the resulting isotope shortage.
There was serious political fallout. The president of the Canadian Nuclear Safety Commission was fired and the
Harper government took the extraordinary step of overruling the commission to get the reactor running again.
It was short-term fix, say the scientists and nuclear medical specialists, who see photo-fission as a possible long-term
solution.
The task force also says photo-fission "eliminates" the need for highly enriched uranium, or HEU. The weaponsgrade uranium is now imported to Chalk River under tight security from labs in Oak Ridge, Tennessee. The U.S.
Nuclear Regulatory Commission licenses the exports, but is under pressure to halt the shipments because of
proliferation and terrorism concerns.
The enriched uranium is used in "targets" that are irradiated inside the Chalk River reactor to make Molybdenum-99.
Moly-99, as it is often called, is used to make radioactive tracer molecules given to patients. As they move around the
body, the molecules can reveal where tumours and cancer cells are lurking, and if organs are working properly. By
following the uptake and clearance of radioactive compounds in heart muscles, it is possible to tell if someone has
had a heart attack.
The scientists say it should also be possible to make Moly-99 through photo-fission by bombarding natural uranium
with streams of photons -- basically high-intensity light beams -- generated by an accelerator.
"We're proposing that instead of inserting a neutron (as occurs in the reactor when the uranium nucleus split to form
Moly-99), you insert a photon," said Nigel Lockyer, task force co-chair and director of Triumf, the national particle and
nuclear physics laboratory, based in Vancouver.
"We'd be able to get away from the weapons-grade uranium and use natural uranium," Mr. Lockyer said. "That's a
huge plus."
The idea of using accelerators to make Moly-99 has been around for years, but had been written off as "an interesting
curiosity," said Thomas Ruth, a senior scientist at Triumf. The machines just didn't seem capable of producing
enough photons.
But the technology has advanced rapidly. And when Mr. Lockyer, an accelerator specialist, and Mr. Ruth, a nuclear
medicine authority, got to talking, it dawned on them that the type of accelerator now being designed at Triumf to
study obscure physics and exploding stars might have significant down-to-Earth applications.
International concern over medical isotopes is mounting. The Chalk River reactor's operating licence expires in 2011.
It could be extended to 2016, but Mr. Lockyer and Mr. Ruth said the reactor cannot keep running forever. Its planned
replacements, the Maple I and Maple II reactors, were scrapped by the federal government earlier this year because
of serious technical flaws.
The world's other big Moly-99 producer, the 47-year-old HFR reactor in the Netherlands, was shut down in August
because of corrosion. It is not expected to restart until February.