Nuclear waste in space?
The issue of safety has two components. One is the actual engineering of safe operations. This is demonstrable and testable. The other, equally important, part is the public perception of safety. As University of Missouri nuclear engineering professor William H. Miller, a specialist on nuclear fuel cycle and fuel management, noted, “The obvious problem is public perception. No matter how far you go to show that it is safe, there will always be someone to say ‘what if’.” John W. Poston, a Texas A&M nuclear engineering professor with a forty-six year career in nuclear health physics, agrees, considering convincing people of the safety of space-based disposal as challenging, if not more so, than the actual technical questions.
Safety should appropriately dominate public discussion of this proposal. To succeed, space disposal must demonstrate lower risk and uncertainty than underground disposal. This project must be completely safe technically, but nonetheless will not succeed unless potential supporters and opponents are thoroughly convinced about its safety and efficiency.
Assuring safety is possible. The two major concerns are launching the capsule and ensuring the integrity of the capsule. Laser launching is safer and more reliable than rockets. The absence of rocket propellants and its accompanying propulsion systems eliminates the possibility of an explosion. The major problem would be if the laser failed before the capsule reached escape velocity. Because the capsule will be bullet-shaped, its ballistic characteristics are well known. Thus, if a launch failure occurred, the capsule would land only in known recovery zones. Launch trajectories would be designed to avoid populated areas.
One advantage of a laser launch system is that the safe return from these aborted missions can be demonstrated by testing with inert capsules. Scores of launches could test every conceivable scenario, the equivalent of firing a new rifle to understand all its characteristics. This could not be done with a rocket. If another layer of safety is desired, placing the launch system on an island in the Pacific Ocean will further decrease the chance of an aborted flight landing in a populated area. Such isolation would also improve security.
The capsule itself must protect its radioactive cargo not only from the demands of a normal launch with its severe atmospheric heating and aerodynamic loading, but also from potential accidents ranging from reentry into the atmosphere to a seriously flawed launch that would send the capsule into the high pressures of the ocean’s depths or into land. Summing up the engineering challenges, Bob Carpenter, the program manager for Orbital Sciences’ space nuclear power program, cautioned, “I’m not saying they are insurmountable, but they are major technical issues to be solved.”
Jordin Kare, now an independent aerospace consultant, was more optimistic. The laser can accelerate the capsule slowly in the lower atmosphere, reducing heating. Furthermore, noted NASA nuclear engineer Dr. Robert C. Singleterry, the same aerobraking analyses and technologies that use a planet’s atmosphere to slow down a visiting spacecraft as the Mars Global Surveyor demonstrated in 1997 can ensure the control of a capsule leaving the earth’s atmosphere.
The integrity of a capsule can be demonstrated too. The aerospace industry has accumulated decades of research and experience on how to contain radioactive material in containers that can maintain their integrity despite atmospheric re-entry, accidents, explosions, and other potential catastrophes. They are called nuclear warheads. Designing containers for space disposal is well within the state of the art. Dr. Rowland E. Burns, the engineer who led a NASA study in the mid-1970s on this issue, stated it is feasible to design and construct containers that can safely withstand the demands of even a catastrophic explosion, claiming, “I won’t say you would have to nuke the container to break it, but it would take something like that.”
Materials technology has improved since the 1970s, making even tougher capsules possible. Because launch costs will be relatively inexpensive, engineers can overdesign for safety instead of trying to create the lightest possible container. Fail-proof capsules can be built, though the ratio of waste to shielding will be low.
Ensuring safety must have an inclusionary component. A broadly based panel of stakeholders, including skeptics and opponents, should determine the criteria for tests and scenarios that proponents must pass. Computer simulations and controlled tests, however, will not be enough. Convincing demonstrations such as aborting launches with a mock payload and sending test capsules to reenter the atmosphere will be necessary to calm fears and prove the veracity of safety calculations. Minimum danger must be demonstrated, not assumed. Those opponents who unilaterally reject space-based disposal should be asked to propose an alternative. Nuclear waste will not go away on its own volition.
Expensive and inexpensive
What about the economics? Let’s be honest and upfront in our accounting: Space disposal will ultimately cost tens of billions of dollars, but the federal government has already spent $8 billion researching underground disposal and expects the total cost will be $60 billion. The difference is that future generations will not have to worry about the waste and they will have an infrastructure for reaching space. While technologically impressive, developments in tunnel boring have far less potential. Disposal in any form will be expensive. Space disposal at least offers a major spinoff, inexpensive access to space. Putting a small surcharge—a fraction of a cent per kilowatt-hour of electricity—on power generated by nuclear reactors would handle the operational costs.
How can a system be both expensive and inexpensive? Judging by the costs of other high technology projects such as the Airbus 380 and Boston’s Big Dig, developing a laser launch system will require at least $5–10 billion. This is a lot of money, but historically space technologies are expensive: The Apollo program cost over $150 billion in contemporary dollars. Constructing the actual launch system will require a few billion dollars and operations will consume billions more. And even if the price of a pound to escape velocity is only $100, 5000 tons is $1 billion.
We owe the future as well as ourselves the opportunity to determine whether space-based disposal is the best way to handle nuclear waste. Accordingly, over the next few years, NASA and the Department of Energy should establish three research programs. The first will determine the criteria and acceptance for a demonstration program. The second program will design safe capsules and the third program will test the ground-launched system. For the price of a new hotel in Las Vegas or a day or two of the defense budget, we will have enough information to decide whether to commit large resources to space-based disposal.
Space disposal may not appear the obvious solution to the high-level nuclear waste problem. Nor is disposing of nuclear waste the obvious answer to the question of how to reduce the cost of reaching space. But the immense magnitude of nuclear wastes provides the incentive to develop launch systems that will drastically cut the cost of space exploitation. The result will be lower operating costs, more infrastructure, and more skilled personnel able to develop other areas of space.
The development of the computer may offer a good analogy. Government funding, mostly from the military, intelligence community, and NASA, greatly accelerated research, development, and diffusion of computers since the 1940s. The federal government did this to conduct projects of national significance such as the census, Social Security, weapons research (especially nuclear explosions), cryptoanalysis, and space exploration. Not until the 1970s did the civilian market grow large enough to seize the technological initiative.
Space disposal may prove a similar opportunity. Once a ground launcher is developed and built, constructing additional launchers will be far less costly and risky. The dream of affordable access to space may then come true, opening up the final frontier in ways that we have not dreamed of since the 1960s. As important, we will be acting ethically, providing our children a safer earth and inexpensive access to space for people as well as plutonium.