Monday, January 24, 2011

Reprocessing Nuclear Wastes

A recent article in the Seattle Times brings to light some of the main issues in the argument against the reprocessing of nuclear waste.

At Hanford, WA, the proposed vitrification process aims to solidify 53 million gallons of military liquid wastes now stored in leaky tanks. These wastes were produced many years ago from the “reprocessing” of nuclear high level fuel rods in order to extract plutonium for use in nuclear weapons. The wastes were originally dumped into single shelled tanks, which are now leaking; and the past 15 or so years have been spent building new double walled tanks to store the waste in the interim. The vitrification plant under construction would take the liquid waste, evaporate off the water, mix the resultant radioactive fission products with sand at an extremely high temperature, and fuse the materials into a glass-log like product that could then be inserted into a metal container for ultimate disposal in a geologic repository such as Yucca Mountain.

When a fuel rod is “spent”, it is removed from the nuclear reactor. It’s material composition is about 95% Uranium 238, 1% U235, 1% Plutonium, and 3% highly radioactive fission products. The concept of reprocessing is to retrieve and recycle the U238, 235, Plutonium (which is fissionable) into new fuel rods for the next generation of reactors. One strong concern is that this Plutonium could be diverted into nuclear weapons or terrorist bombs.

If we do turn to reprocessing for commercial nuclear wastes, we would eventually wind up with hundreds of millions, billions, ??? of gallons of caustic, radioactive liquid wastes that would have to be treated. How many reprocessing/vitrification plants would we need to build? Where would we build them? At what cost? A similar plant currently being built in the Savannah River, SC military nuclear site is also far behind schedule, way over budget, and faced with many of the same major technical problems.

If we did commercial reprocessing, spent fuel rods would have to be shipped from all over the US to “nuclear reservations” where the expensive reprocessing would occur. The spent fuel would have to be stored on site until it could be sent to the “separation “ facility which would process the fuel rods by dissolving them in acids; separate and extract the uranium, plutonium, and its byproducts; and then the repackage the “useful recyclable” material into new fuel. The left over liquid wastes would then need to be processed by a vitrification plant, and the “glass” cylinders would be stored on site awaiting final disposal. Would we have one, two, ??? of these facilities? Where would they be built, and how would all this material be transported in and out? Where would we store this highly concentrated radioactive material until a repository is built?

The cost for the Hanford plant has gone from a proposed $1 billion in the early 90’s, to over $12 billion in 2010, and the plant is now only half constructed. It is 20 years behind schedule and is expected to start in 2019, if ever. It will take about 25 years of operation to deal with the 53 million gallons of waste, and the operational costs to do so are currently projected to be between $15 billion to over $25 billion. The similar project being built at the Savannah River, SC nuclear site is experiencing similar cost overruns, delayed time schedules, and serious questions as to environmental, health, and safety issues.

Reprocessing is a huge technological , with huge uncontrollable dollar costs, huge investments in materials, huge amounts of energy requirements, and very long time frames. The bottom line is we don’t know if it will really work, or what the environmental impacts, and health and safety issues will be. Because we would be concentrating very highly radioactive materials into a small confined space (the cylinder), we haven’t figured out how space we would need to configure the thousands of cylinders in a repository with respect to the heat that they will emit for thousands of years, or how all the materials will age and react over time.

Reprocessing does not solve the nuclear waste problem; in reality, it makes it worse. True, that while we would be reducing the ultimate volume of radioactive materials that would have to be disposed, and reducing the time frame of radiological concern from 100,000 years to 10,000 years; we would also be creating a much larger waste mess…nasty liquids which can leak, more concentrated highly radioactive glass-log canisters, and the necessity to transportation these materials all over the US, that will be more difficult and expensive for our future generations to deal with.

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