Material Matters
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To Mark, or Not to Marie What Really is the Virginia M. Oversby Introduction
The use of nuclear fission to generate power results in waste materials that can be hazardous to people and to other life forms, particularly in the first few hundred years after the wastes are created. There is a worldwide consensus that the management of these wastes must not place undue burdens on future generations. In some countries, the opinion is openly stated that those who enjoyed the benefits of the power that produced the wastes must be responsible for taking care of the wastes. Opinions diverge when discussion turns to the question of whether the wastes will always be a liability or eventually become an asset. Another point of consensus is that at least some of the radioactive wastes should be disposed of by a method that securely isolates them from the accessible environment of plant, animal, and human life until the radioactivity levels have decayed to levels similar to those found in natural environments. Different countries take different positions on the details of what the activity level might be that constitutes the end of moral responsibility for the wastes, but the general position is basically the same worldwide. I explore some concerns about how disposal containers and waste repositories might be marked with suitable identification. In particular, I examine whether the message to be conveyed by the markings needs to change with time and with the entity examining the objects, and whether we can design markers that will convey this potentially variable message. Spent Nuclear Fuel: A Liability or an Asset?
Spent fuel as it comes out of a nuclear reactor is clearly a liability in the short term, even if it is destined to be reprocessed to recover usable materials. If the country in which the spent fuel was generated has chosen to operate a "once through" fuel cycle that does not include separation of useful materials prior to
waste disposal, the spent fuel must be viewed from the standpoint of that country at that time as a long-term liability. But now let us transport ourselves 400 years into the future. Perhaps fusion energy has become an outstanding success and the potential for virtually unlimited energy has been realized. Then again, perhaps fusion has not been so successful, fossil fuels have been exhausted, and the natural uranium ores have been consumed. At this point, the residual 235U and ^ P u content of the spent fuel might be considered to be valuable assets to be used in immediate energy production, and the 238U might be viewed as a valuable breeding material to produce additional fissile materials for much larger amounts of energy. We do not know what the energy requirements of society will be 400 years from now and we are in no position to judge how those requirements might best be met. In order not to place undue burdens on future generations, I believe that we must not only protect them from unseen dangers, but we must also assist them in finding resources that might be vital to their well-being. If
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