by Karen Smith
First appeared in Nuclear Guardianship Forum, #1, Spring 1992.
Can we reduce the biological hazard of radioactive waste and thereby improve our chances for guarding the biosphere from contamination by using yet another form of atomic technology? In this interview, nuclear engineer Ed Fuller, a long time member of the Nuclear Guardianship Project, discusses some of the pros and cons of transmutation.
KS: As a nuclear safety engineer who has worked in the industry for over 25 years, what for you is the goal of nuclear safety?
EF: Keeping the radioactive materials out of the biosphere. From the time mining begins there is contamination of the environment: radon escapes during the mining and milling processes, chemicals used to fabricate the fuel are themselves hazardous. My field, nuclear safety, is mainly concerned with preventing accidents in the reactors themselves, accidents in which fission products are released out of the fuel matrix, such as occurred at Three Mile Island and Chernobyl, or at reprocessing facilities like Sellafield in England and Chelyabinsk in the Urals. Nuclear reactor safety means diligence has to be maintained until the reactor is safely shut down, and is particularly concerned about possible meltdowns once the ability keep the fuel cool is lost. Later on, after the fuel is removed from the reactor, it is still necessary to assure that it does not overheat. Finally, when reprocessing takes place, assurance must be given that it be done safely, or large quantities of fission products can escape.
KS: How long must diligence be maintained after the fuel is removed from a reactor?
EF: As long as the quantity of radionuclides is such that the radioactivity being emitted from them is greater than would be emitted from a similar quantity of natural unmined uranium in the ground. (The term radionuclides refers to fission products, plutonium and minor actinides like neptunium or americium.) Some of these set off further reactions in their decay cycles, creating other radioactive products. Some take days, months, decades, before they are stable again, while others have half-lives of thousands and thousands of years. It is difficult to imagine how we can insure the safety of hundreds and thousands of years. It is difficult to imagine how we can insure the safety of hundreds of generations who will be left with this kind of contamination.
SK: The one thing everybody seems to agree on is that the contamination is here to stay. Some citizens' groups have advocated storing the poison radioactive wastes in such a way that they can be monitored and contained over the millennia to protect future life on Earth. As a scientist, how far ahead do you think we can protect future generations?
EF: The best we can do for future generations is to make sure the fission products stay out of the air and out of the water. If we minimize new production of radionuclides and set up appropriate structures to protect the biosphere from this contamination, I believe we can keep future generations safe from it for three or four hundred years at the most. I find it difficult to conceive of keeping it safe for longer than that.
Retrievable monitored waste storage is already being tried, for example, at Carolina Power and Light's H.B. Robinson plant, at Duke Power's Oconee plant (both in South Carolina), and at Ontario Hydro in Canada. At Rancho Seco, California, they are in the process of designing and building dry cask storage that is transportable. In other words, they are keeping their options open. But for the long-lived fission products, like Technicium-90 and Iodine-129 with half lives of 200,000 and 16 million years, respectively, this will be an enormous, perhaps impossible, undertaking.
What interests me now is transmutation, the process in which the longer-lived fission products and actinides are changed into products with much shorter half-lives. These products could then be guarded, along with the vast majority of fission products so far generated, for several centuries, until the products are again stable and could safely be returned to the earth they came from.
KS: Will the burning of actinides in order to transmute them into something less dangerous have its own dangers?
EF: You do make new fission products when you transmute actinides, but these products can be controlled, and the resulting material does have a much shorter half-life. At Los Alamos they are already researching the feasibility of using the accelerators to transmute plutonium and other actinides, as well as the long-lived fission products.
KS: Won't transmutation provide yet another source of fuel, and thereby possibly prolong the use of the very process that produces the contamination?
EF: The danger of transmutation is in allowing it to be used to produce electricity. The Los Alamos model includes the possibility of generating electricity or other sources of revenue. Some of the other transmutation models now being proposed, for example, breeder reactors, would be even more amenable to electricity generation since the actinide-burning reactors are already in place. As conceived, the actinide-burning reactors would be even less safe than existing breeder reactors and would have to be extremely carefully designed and operated. They will be expensive, and the temptation will be great to try to recover some of the costs, or even make a profit, by combining the transmutation process with electricity generation.
The other danger of using transmutation to make electricity is that it could lead to more mining, including Thorium-232. (Even more abundant than uranium, Thorium generally can't be fissioned, but can be bombarded with a neutron to bump it up to uranium and used as fuel.)
Preventing these things from happening means going way beyond short-term economic considerations. In the short run, transmutation without electricity means less radioactive waste to bury, but high overhead and no immediate return, that is, no electricity. But over the next few thousand years the savings (in safety, maintenance and health) would be incalculable.
KS: Do you see a danger that transmutation, with its promise of less contaminated material, could be used as an argument for continuing to use nuclear-generated electricity?
EF: The worst thing that could happen with transmutation would be people getting on the bandwagon and using this possibility to promote a renaissance of nuclear power, which is waning now because the contamination issue is not answerable. I think the industry, at least in the west, realizes it has made a big mistake. There will always be accidents, and the so-called low- level waste will be with us forever.
What transmutation COULD accomplish is to engender a commitment to get rid of the long-lived actinides and fission products, and by logical extenuation, a commitment to get rid of the nuclear option.
By transmuting plutonium into shorter-lived materials we could begin to plan realistically for the care and maintenance of the contaminated products, as well as to return the no longer dangerous uranium (Uranium-238) back into the earth. Transmutation technology could be on line by about 2020, in time to clean up some of the mess we have made. It will take diligence and vigilance to make sure that scientists are held accountable, so that this time an informed democratic process can be brought to bear on deciding the future.
Karen Smith is a concerned citizen who has been engaged in social change projects for the past 25 years, most recently in promoting the Guardianship-inspired Nuclear Care Concept in Switzerland.
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