We have come to the last major subject in the concern about nuclear energy. Nuclear waste may be the end of our list but the big problem is that some of it does not end for millions of years. Waste is generated at every stage of nuclear energy as well as nuclear weapons production. There are high level nuclear wastes that will kill with direct exposure and lower level wastes that may lead to poisoning and cancer. The half life of the radioactive isotopes in nuclear waste can vary from hours to more than a million years with some types of wastes being dangerous for hundreds of thousands or millions of years. It is estimated that there are currently around 250,000 tons of nuclear waste around the world.
First, there is the problem of the waste tailings left after uranium has been removed for processing. This waste product is almost as radioactive as the uranium that has been removed. We have already mentioned this under uranium mining. If not properly dealt with it can pollute the air, water and soil posing a threat to human and animal health.
Processing separates isotopes in order to create a higher ratio around twenty percent of the highly radioactive U-235 to the U-238 which constitutes most of the naturally occurring uranium. This enrichment process produces U-238 as waste which is radioactive and must be disposed of properly. Nuclear weapons production has to raise the ratio of U-235 to U-238 as high as ninety percent which produces a great deal of waste U-238.
After the nuclear fuel rods are depleted, they are removed from the reactors and temporarily stored in the spent fuel pool at the reactor. These pools are often outside the containment vessel and more vulnerable to accidents or terrorists. If the coolant in these pools drops below the level of the rods, they can burst into flame spontaneously spewing radioactive particulates into the atmosphere.
The spent fuel pools in the United States are going to be full in five years. The intent was to have a permanent nuclear waste disposal site built to take spent fuel rods by 1999. Since the cancellation of the Yucca Mountain Nuclear Repository, there is not even a plan for a U.S. waste repository. The fuel rods will have to be stored onsite or offsite in temporary storage casks. These should be safe storage for decades but may still be threatened by accidents or terrorists.
Most plans for permanent waste disposal focus on digging a deep hole or using an existing hole like a mine. Searches go on for extremely stable geological formation with little movement of groundwater and no fault lines that may cause earthquakes. There are ten waste depositories around the world. Yucca Mountain in the U.S. turned out not to be so safe after reconsideration. Germany had to shut down a waste depository because there was unexpected leach of waste products by groundwater. If a waste depository is opened, then nuclear waste must be transported by truck, rail and/or ship which will increase the risk of accidents that will spill radioactive materials into the environment.
Other methods have been suggested for disposing of waste such are processing in reactors, shooting into space, drilling extremely deep wells and other schemes. All of these ideas are untried and will be expensive and difficult to test and verify.
Nuclear waste is a threat to humanity and a good reason to end the use of nuclear energy for power.
