Disposal of nuclear waste The hazardous waste from nuclear power plants or unused weapons is usually buried underground.The depth at which it’s buried depends on whether the aim is permanent disposal or temporary disposal until a better solution can be found. Although this is an improvement on the 1950s and 1960s when barrels of nuclear waste were often just dumped at sea, many of which are still lying at the bottom of the Irish Sea! The waste can leak from these containers and pollute the water as the containers degrade far quicker than the material becomes safe.
One interesting proposition is a process called subductive waste disposal. In involves burying the nuclear waste in the Earth’s crust.The Earth’s crust is made of tectonic plates, some of which pass under and over each other. This happens in various sites under the world’s oceans.The waste is buried in the plate that is passing under; this is called the subducting plate. The plate, along with the hazardous waste, is safely absorbed into the Earth’s mantle.
A nuclear waste barrel at a depth of 103 m in the Irish Sea
Fig 22.23: Subduction of the Earth’s crust
SAMPLE PROBLEM 22B
During the fission of a uranium-235 atom 3.1 1028 kg of mass is converted into energy. Calculate this energy in megaelectronvolts.
