http://www.sciencemag.org/cgi/content/full/sci;294/5549/2093cScience 7 December 2001:
Vol. 294. no. 5549, pp. 2093 - 2094
DOI: 10.1126/science.294.5549.2093c
Letters
The Pros and Cons of Nuclear Fuel Recycling
In "plutonium and the reprocessing of spent nuclear fuel" (Policy Forum, Science's Compass, 28 Sept., p. 2397), Frank N. von Hippel reiterates the standard arguments against reprocessing in response to the National Energy Policy Development Group report that advocates a reexamination of U.S. policies on reprocessing R&D. The report also states that "the United States will continue to discourage the accumulation of separated plutonium worldwide" (1). Most of us who advocate a resumption of U.S. R&D in advanced reprocessing and remote fuel fabrication methods that avoid plutonium separation agree.
All fuel cycles must use enrichment or reprocessing, and both technologies provide routes to proliferation. There currently exists a 30% global excess of enrichment capacity, and any nation acquiring enrichment facilities today appears suspicious on economic grounds. This situation will reverse in the next two decades as U.S. gaseous diffusion enrichment plants retire and as current excess military and civilian enriched uranium supplies are consumed.
The natural trajectory for enrichment technology is toward methods that are more efficient and therefore easier to conceal; for reprocessing, it is toward methods that make the waste stream as clean as possible and the fuel quite dirty and therefore hard to steal. Thus, the emergence of a global market for new enrichment technologies and services deserves concern, particularly at the scale implied by the use of seawater uranium for the expansion of once-through reactor systems.
These concerns also relate to storage issues. Only a few long-term methods can be envisioned for managing nuclear waste. The strategy of highly dispersed and protracted surface storage may continue indefinitely. Conversely, a small number of geologic repositories might be sited to take this waste. I doubt we will site a "mega-repository" capable of holding centuries of global spent fuel, such as the proposed Pangea site in Australia, or that tens or hundreds of repositories will ever be sited worldwide. Thus, for sustainable fission energy production, the scarce resource will not be uranium, but will almost certainly be repository capacity.
Decay heat creates the fundamental limitation on repository capacity. For spent fuel, the fission products--137Cs and 90Sr with half-lives of 30 years--generate roughly half of the total repository heat load. The actinides--principally the heavy elements 241Am (458 years) and 238Pu (86 years)--provide the other half. We can actively manage the fission product heat. For example, in unsaturated media like Yucca Mountain, the simple ventilation of the drift tunnels would recover ~50% of the repository thermal capacity every 30 years. But we cannot actively manage the actinide heat, which is deposited over too long a time. This is why, in the longer term, it will likely make economic sense to recycle actinides back into reactors, and why it is correct and appropriate for the United States to develop new technologies for this purpose.
The broad adoption of the Nuclear Nonproliferation Treaty can be credited in large part to the commercial potential seen in nuclear energy. Our development of new fission-energy systems that better manage their waste streams could create new incentives for broad adoption of even more rigorous international norms: in particular, comprehensive International Atomic Energy Agency (IAEA) Safeguards Agreements that include an Additional Protocol, which, when adopted by a nation, allows IAEA inspections anywhere within that country to confirm the absence of undeclared nuclear activities (2). This creates a worthy goal for future nuclear energy R&D.
Per F. Peterson
Department of Nuclear Engineering,
University of California,
Berkeley, CA 94720-1730, USA.
E-mail:
[email protected]References and Notes
1. National Energy Policy (The White House, May 2001). Available at www.whitehouse.gov
2. Additional Protocols are now in force in 22 nations:
http://www.iaea.or.at/worldatom/Programmes/Safeguards/sg_protocol.shtml Response
Peterson's nightmare is different from my own. Mine is that the Bush Administration is undercutting the more than two-decade-old campaign to end civilian commerce in weapon-usable plutonium just when that campaign is on the verge of success. Britain, France, Russia, Japan, and India are still separating annually more than 20,000 kg of pure plutonium from spent fuel--enough for at least 2500 nuclear explosives--but, in fact, deregulated utilities are becoming more resistant to subsidizing these uneconomic programs.
Peterson worries about the challenge of siting "tens or hundreds" of deep underground respositories for spent fuel in the United States. But it would take hundreds of years for any such problem to develop. The proposed Yucca Mountain repository would hold about as much spent fuel as will be discharged over the lifetimes of the ~100 nuclear power plants in the United States. Because of a lack of utility interest, there has not been a construction permit for a new nuclear power reactor issued in the United States since 1979 (1). Worldwide nuclear capacity is ~3.5 times that of the United States' and is projected to stay about constant for the next 20 years as a result of a combination of modest growth in the developing world and decline in the industrialized world (2).
Peterson is right about the danger of the proliferation of small-scale uranium enrichment technology. Pakistan produced its weapon-grade uranium using technology acquired by A. Q. Khan while he worked in the Urenco commercial centrifuge enrichment plant in the Netherlands (3). Khan returned to Pakistan and built an enrichment plant reportedly based on Urenco designs (4). However, the fuel used in most of the world's nuclear-power reactors is low-enriched and not weapons useable. In contrast, commercial spent-fuel reprocessing technology produces pure plutonium directly useable for the production of nuclear weapons.
In short, my objections to the proposal to launch a new U.S. reprocessing R&D initiative are: (i) reprocessing is not needed within this century, and (ii) the Bush Administration proposal is being greeted by foreign reprocessing establishments as a rollback of U.S. opposition to commerce in plutonium.
Frank N. von Hippel
Department of Public and International Affairs,
Princeton University,
Princeton, NJ 08550, USA
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