Atomic Insights April 1995

One of the main reasons for publishing this letter is to add a healthy dose of reality to the mythology that has surrounded the atomic energy field. There are so many of these myths that this column will be a regular feature of the Atomic Energy Insights.

One of the most prevalent myths is that nuclear fission produces large quantities of waste that will be dangerous for thousands of years. This is simply not true.

• The longest lived fission products will become stable elements within just a few hundred years.
• The longest lived fission product has a half life of about 30 years.
• The total amount of waste material is extremely small.
• All of the high level waste produced in the United States in the last 30 years could fit onto a single footbal field in a single layer of licensed storage containers.

Where, then, did the prevailing myth originate? Most myths have some basis in the real world of facts and observations.

The Longevity Issue

First, let’s address the longevity issue. While all isotopes that are produced when uranium splits are relatively short lived, some of the uranium atoms do not fission with the first neutron impact. Instead, they absorb the neutron and become a more massive isotope.

Some of the heavier isotopes will fission when hit by the next neutron, others will absorb the next neutron and become even heavier. The process does not go on forever. Eventually, if enough neutrons hit the heavy nucleus that was originally uranium the nucleus will split. These heavy isotopes are known as transuranics or actinides.

Transuranics vs. Fission Products

Some transuranics, notably plutonium-239, have long half lives. Although these materials form a small portion of spent nuclear fuel, they are what most of the fuss is about. Although some transuranics are produced in fission reactors, they are not fission products. Making the distinction between transuranics and fission products is not hair splitting or semantics.

Fission products are no longer useable for fuel (though they may have other uses). Transuranics, on the other hand, can be recycled into new reactor fuels rather easily. At the now cancelled Integral Fast Reactor, all actinides would have been reformed into new fuel elements. Because of the large difference in density between transuranics and fission products, they can be readily separated.

Recycle, Reuse

It is the stated policy of the U.S. government to discourage the recycle of actinides into new fuel elements. The ostensible reason for this policy is to make it harder for someone to turn the transuranics into bomb material. Most other countries with a sizable nuclear power industry disagree with our wasteful position and currently recycle at least some of their spent fuel.

The only known way to permanently destroy transuranics is to expose them to enough neutrons to split their nuclei. The cheapest source of neutrons that we have ever devised is a fission reactor. When actinides are destroyed in a fission power plant, they produce a large amount of useful energy.

Controlled Storage

Now let’s address the issue of just how much material needs controlled storage. Most nuclear power plants were not built with sufficient facilities to store all of the waste that they would generate over their whole operating lives.

Providing the required engineered storage space at the beginning of the plant life would have been wasteful. It would have been analogous to a city deciding to build a school big enough for thirty years worth of growth. In the early years, most of the classrooms would be empty but the bills for building them would still be due.

It is a good thing that facilities were not built large enough to handle the spent fuel projected to be discharged over the life of the plant at the time the plants were built. There has been a significant reduction in the volume of waste produced through the use of advanced fuel cycles. Using the school analogy again, some of the expensive classrooms would never have been filled.

When the plants were built, the owners were told that the federal government would take the waste from them. In fact, they were told that they did not own the waste and could not turn it over to anyone other than the federal government. That is still the case today.

Waste: Who’s Responsible?

The federal government has not met its contractual obligations to permanently take possession of the waste.

Some of the older nuclear power stations are slowly starting to run out of space, even though they have reorganized their facilities to provide as much space as possible.

The process is a slow one because most plants only discharge about fifty fuel assemblies every 18 to 24 months. For comparison, a 1000 MW coal fired power plant must find a storage location for about 1500 tons of coal ash (enough to fill 33 train cars) every single day.

All nuclear utilities have contributed to a fund established in the early 1980s for waste storage facilities. The fund”s assets are now over $8 billion even though not a single fuel assembly has been accepted for storage.

Nuclear sites are allowed by law to build independent spent fuel storage facilities with sufficient space for a lifetime of spent fuel, but few utilities have chosen this route.

The facilities cost about $12 – $15 million each, and there is often legal opposition to construction, despite the general license that the NRC has already granted. (As a reminder of the scale of electric utility numbers, $15 million would buy less that a three week supply of fossil fuel to replace the electricity generated by a 1000 MW nuclear station.)

The Bottom Line

The utilities and their trade group, the Nuclear Energy Institute, have chosen to attempt to force the government to live up to its commitment to take the fuel. This choice, while a prudent short term business decision, has helped to fuel the myth that there is a huge amount of material for which no feasible storage solution exists.

The bottom line when it comes to “spent” nuclear fuel: All the long lived material can be recycled. Even without recycling, the volume of material needed to be stored is rather small and easy to handle.