As reflected in these wide ranges in cost estimates, large cost uncertainties remain. For instance, if the cancelled Yucca Mountain repository project is reactivated, it is designed to hold less than half of the total currently projected spent fuel to be generated in the United States at a total cost of $113 billion.
Significant uncertainties surround prolonged storage of high-burnup spent nuclear fuel. This fuel generally contains a higher percentage of uranium 235, allowing reactor operators to effectively double the amount of time the fuel can be used. Once it is used, high burnup significantly boosts the radioactivity in spent fuel and its commensurate decay heat. Of concern is the damage that high-burnup fuel may have on the cladding of the fuel. The Nuclear Regulatory Commission (NRC) and the nuclear industry do not have the necessary information to determine if prolonged storage of high-burnup fuel may damage fuel cladding and create leakage.
Dry cask storage systems currently deployed are not licensed for disposal and were chosen primarily as an economical means of surface storage. Existing large canisters can place a major burden on a geological repository, such as: handling, emplacement and post closure of cumbersome packages with higher heat loads, radioactivity and fissile materials. “Waste package sizes for the geologic media under consideration …are significantly smaller than the canisters being used for on-site dry storage by the nuclear utilities,” Energy Department researchers conclude. Technical advisors to the DOE find that, “repackaging the SNF may be a lengthy process and could impact operational schedules at the utility sites, at a consolidated storage facility, or at the repository, depending on where repackaging is performed.”
The estimated concentration of long-lived radionuclides in spent power reactor fuel at CGS is approximately 170 percent greater than stored in Hanford’s radioactive waste tanks from decades of plutonium production for weapons.
Dry cask storage systems are either single purpose (storage only) or dual purpose (storage and transportation). None are currently licensed for disposal. “Direct disposal of the large canisters currently used by the commercial nuclear power industry is beyond the current experience base globally,” a 2013 DOE study observes, “and represents significant engineering and scientific challenges.”
In 2012, Energy Department researchers concluded that “waste package sizes for the geologic media under consideration …are significantly smaller than the canisters being used for on-site dry storage by the nuclear utilities.”16 A nuclear industry study concluded in 2014 that “ casks and canisters being used by the power utilities will be at least partially, and maybe largely, incompatible with future transport and repository requirements, meaning that some if not all, of the [used nuclear fuel] that is moved to dry storage by the utilities will ultimately need to be repackaged.”
According to DOE research the costs of repackaging at a centralized storage site are large.19 The estimates in this study are based on a small (9 assemblies), medium (32 assemblies) and large (44 assemblies) standardized transportation and disposal canister (STAD) for a boiling water reactor. When applied to the Columbia Generating Station, assuming it will operate until 2043, this could involve cutting open 120 dry casks and repacking approximately 8,160 spent fuel assemblies into casks suitable for disposal
In its most recent analysis in 2014, the NRC estimates that a spent fuel pool fire in the United States could release 100 times more Cesium-137 than from the Fukushima accident, but asserts that the probability of such a fire is very low. Such a fire, depending upon the location of the reactor and its spent fuel pool, and the direction of fallout from it, could displace millions of people and render an area uninhabitable that more than 20 times larger than that the exclusionary zone created by the 1986 Chernobyl nuclear reactor meltdown in Ukraine.
Because the proposed Yucca Mountain nuclear waste repository was cancelled by the Obama administration and is by no means assured of revival in the coming years, and all other storage plans remain speculative, these wastes may remain in interim storage at the reactor sites for the indefinite future.
In recognition of major uncertainties, the agency also states that “extended storage, for periods of up to 300 years, is being considered within the U.S.”
Heat from the radioactive decay in spent nuclear fuel is also a principal safety concern. Several hours after a full reactor core is offloaded, it can initially give off enough heat from radioactive decay to match the energy capacity of a steel mill furnace. This is hot enough to melt and ignite the fuel’s reactive zirconium cladding unless cooled by water. Over time, even after decades of cooling, the excess heat remains a danger to destabilize a geological disposal site it is placed in. By 100 years, decay heat and radioactivity drop substantially but remain dangerous. For these reasons, the US Government Accountability Office (GAO) informed the Congress in 2013 that spent nuclear fuel is “considered one of the most hazardous substances on Earth.”
|Title||UPDATE REPORT ON SPENT NUCLEAR FUEL MANAGEMENT AND CLOSURE DATE COST COMPARISON AT THE COLUMBIA GENERATING STATION|
|Publisher||Institute For Policy Studies|
|Related Keywords||Helms Proposal, Nuclear Energy, Stop Nuke Dump|
|Media Type||Article, PDF|
|Media Group||News, Research|
|Author Name Sortable|