More than three years ago, I wrote about the Yucca Mountain project, telling you that I thought that the entire concept was stupid because it was based on flawed assumptions. (See Yucca Mountain: Right Answer; Wrong Question) I also promised that I would discuss a better solution in a future article. The future is now, even though I have not been able to arrange for my company to profit from the concept.
What is “Spent Nuclear Fuel”?
Nuclear power plant operators have a slowly developing problem. Their power stations, as currently designed, need a certain amount of new fuel every 12-24 months. Though uranium is incredibly energy dense, it gradually gets consumed during the process of producing massive quantities of electricty. In order to fit fresh fuel into densely packed reactor cores, the oldest fuel in the reactor has to be removed, even though it still contains a large portion of the initial potential energy of new fuel. Most people are shocked when I tell them that this so called “spent” fuel contains 95% of its initial potential energy.
This carefully engineered, corrosion resistant, solid material is still fully capable of remaining intact while generating huge quantities of energy at extremely high temperatures in a rather aggressive chemical environment. When it is displaced by fresh fuel, must be put somewhere outside of the reactor core.
How are utilities storing “spent nuclear fuel” now?
When the slightly used nuclear fuel leaves the reactor it is placed into a carefully monitored pool full of chemically treated water. This clear, deep pool is necessary because the used fuel has become quite active and produces both an intense field of radioactive emissions and a significant quantity of heat from the decay of radioactive materials.
The water provides both radiation shielding and heat removal. It allows people with long handled tools and underwater sensing devices to maneuver the fuel into precisely designed storage racks where the radioactive materials produced by splitting uranium gradually decay into less active materials. In typical nuclear engineering fashion, the pools are about three times as deep as they really need to be to provide adequate worker protection. The extra depth provides a large reaction time margin in the highly unlikely event that the steel lined concrete vault with no installed drainage systems springs a leak.
The quantity of used fuel that needs to be added to the pool each year is not very large. Most plants replace approximately one third of their cores every 12-24 months. After refining the rack designs in their used fuel pools, most plants have the ability to store the equivalent of about 3-5 complete core loads in their pool. After 15-25 years of operation, the fuel pool storage gets close to being filled up.
What happens when the used fuel storage pool is full?
The good news is that after 6 years or so in the pool, the intensity of the radiation and the heat generated by the decay of the fission products has dropped by several orders of magnitude and is low enough to allow the fuel assemblies to be moved out of the pool and into dry storage containers. There are a dozen or more different container designs that have passed an extensive testing and license review process and are fully qualified to store used fuel assemblies.
Remember, these fuel assemblies are the same ones that were fully capable of maintaining their integrity in the intense radiation and aggressive chemical environment of an operating reactor. They have spent at least 6 and often 15-20 years in a pool of water with a chemical environment that has been carefully designed to prevent corrosion. I have seen clear, magnified pictures of the fuel assemblies that are being moved out of pools and into storage, they look almost brand new.
Once the fuel assemblies are loaded in to the dry storage containers, the container is filled with an inert gas and slightly pressurized. The pressurized gas allows a very simple and reliable method of automatically sensing the integrity of the container; if the pressure drops, a sensor will detect that drop and provide an alarm.
The dry storage containers are large, carefully engineered structures of concrete, lead and steel. They are about 15 feet tall and when they are loaded with fuel assemblies they weigh 100 tons or more. Though the designs vary, most of them are too heavy to transport on US roads without special equipment. At the power plants where I have seen the dry storage systems, the containers are moved with special equipment to a well protected area on the site of the plant where they either stand up in an area that closely resembles a fenced parking lot, or where they are loaded horizontally into a concrete bunker system. Natural air flows around the containers is sufficient to keep them cool, even in the hottest climates.
About three containers are needed to store the quantity of fuel that is removed each 12-24 months; the space taken up by even a 60 year plant life is less than is needed for a Wal-Mart even without any efforts to efficiently stack the containers. All of the plants in the US have dozens to hundreds of acres of available free space. The size of the work force needed to monitor this storage area is rather small; they provide security and occasional inspections of the containers but have few additional duties.
I have a difficult time imagining any reason why the system cannot work for decades to centuries while smart people work on ways to make better use of the incredibly energy dense resource that is only slightly used at the time that it is removed from the plant. There are no liquids to leak, all of the stored materials from commercial nuclear plants are solid, high temperature materials that have less chance of harming the environment than do the silver dollars that I store in my closet.
Why are the utilities so adamant about the need for a government solution?
The federal government currently has a contract in place that requires it to provide a service to utilities that own nuclear power plants. According to the Nuclear Waste Policy Act (NWPA) of 1982 as amended in 1987, the Department of Energy has been directed to build a deep geologic repository for spent nuclear fuel. This facility is intended to be a permanent repository for the material. The law’s basic assumption is that the long term future for used nuclear fuel is to store it deep underground, essentially forever. According to the law, the facility was scheduled to begin accepting waste by 1998; the current schedule indicates that this date of initial acceptance might be closer to 2010 or 2015.
The NWPA requires utilities to collect a 0.1 cent per kilowatt-hour fee from their customers and pay that fee to the federal government as part of the cost for providing this used fuel removal service. That may not sound like much money, but there are enough nuclear kilowatt-hours produced each year in the US to make the total annual fee from commercial nuclear plants almost $750 million dollars. Cummulative receipts into the fund are in excess of $24 Billion as of early 2005.
The federal government has frittered away more than $7 billion dollars (that is enough money to provide a $70,000 check for every attendee at last year’s Rose Bowl) drilling holes into the volcanic tuff at Yucca Mountain. However, it has not removed any fuel from any nuclear power plant site and it does not look like it is going to any time soon. Though the burdens on the utilities are not onerous, they are in a position where they are shouldering unnecessary costs and paying twice for the same service.
Nuclear utilities pay between $500,000 and $1 million per dry storage container. The also spent a lot of time and money designing new rack arrangements for their pools and in getting their storage arrangements approved by the Nuclear Regulatory Commission. Building the three foot thick concrete pad and associated fences for an on site storage area can cost a few tens of millions of dollars, much of which is used to pay lawyers and accountants to prepare the rate cases necessary to pass those costs on to utility customers.
At least one large utility company owning one of the largest fleets of reactors has successfully sued the Department of Energy for the costs associated with storing used fuel at a time when the long promised repository should have been accepting shipments. Though the details of the settlement were not made public, the DOE apparently agreed to allow the utility to retain as much as $600 million from its nuclear waste fund payments over a ten year period.
The costs of storing used fuel at existing power stations is a considerable quantity of money, but it pales in comparison to the cost of fossil fuel. A 1000 MWe coal fired power plant pays at least $250,000 per day for fuel; one heated by natural gas or oil consumes fuel costing well over $1 million per day.
I learned something new during my research for this article. I was under the impression that there were some severe limits placed by the Nuclear Waste Policy Act on the ability of any private enterprise solution to the above situation. However, as the Nuclear Regulatory Commission has made abundantly clear in its memorandum on the subject of Private Fuel Storage L. L. C. nothing in the act stops the NRC from licensing a private fuel storage facility.
The NRC has explicit authority under the Atomic Energy Act of 1954 to regulate the constituent materials in used nuclear fuels and has licensed at least three private away from reactor (AFR) storage sites already. It is reviewing the Private Fuel Storage L. L. C. application to store up to 40,000 tons of material on the reservation of the Skull Valley Band of Goshute Indians in Utah. This effort has been going on for some time, and has generated a lot of controversy, but it is not because the NRC has any real reluctance to allow private solutions to the problem of interim used fuel storage.
The Skull Valley location, however, seems to have been chosen using some of the same faulted assumptions that led to the selection of Yucca Mountain. It is on the sacred ground of an Indian reservation partially because the assumption in the nuclear industry is that no state would want a used fuel storage facility. As sovereign entities, Indian reservations seem to offer the organizers of the effort the opportunity to avoid some of the politics associated with used nuclear fuel. The Skull Valley site is in a remote area far from existing transportation nodes and operating nuclear power plants based on the assumption that the material is so dangerous that it needs the isolation provided by empty miles.
A far more cost effective solution would be to find regional sites in areas with good transportation, a willing, technically trained work force, and some proximity to existing nuclear power stations. There are plenty of places full of people that are willing to do challenging work in return for adequate job compensation and security. There is no reason for extreme remoteness – that just adds cost and makes it harder to attract the dedicated people required to safely receive and monitor used fuel.
In a country where bidding wars can break out between communities hoping for a state prison to be located nearby, there should not be any real difficulty in finding one willing to host a multimillion – potentially billion – dollar facility that will host monitored containers full of material that may someday be extremely valuable. There are known ways of making use of much of the stored energy that remains in the slightly used fuel and those ways become more economically attractive as time moves on.
Let the bidding wars for private used fuel storage sites begin.