Things that have been in close proximity to radioactive sources, and therefore have a high level of contamination, are often classified as HLW. It is too radioactive to be regarded as LLW, but doesn’t produce enough heat to be regarded as HLW. ILW (Intermediate Level Waste) makes up about 7% of all nuclear waste, and 4% of the total radioactivity. Most of the nuclear waste produced (around 90% by volume) is low level waste, but only 1% of the total radioactivity of all radioactive waste. Waste is regarded as LLW if it has no more than 4 GBq per tonne (4 Billion decays per second per tonne of the object) of alpha activity or no more than 12 GBq per tonne of beta or gamma activity. These waste types are disposed of in different ways, based on the hazard posed by their radioactivity. Waste is typically split up into three different categories, which correspond to its radioactivity: Low Level Waste (LLW), Intermediate Level Waste (ILW) and High Level Waste (HLW). These and many other isotopes are found in radioactive waste. They are both highly radioactive and are the principal sources of radiation in the Chernobyl exclusion zone. Caesium-137 is easily spread in nature due to caesium compounds’ solubility, while strontium-90 is less easily spread but is incorporated into bones and bone marrow if ingested by organisms. They pose issues if released into the environment. Strontium-90 and caesium-137 both have an intermediate half-life of around 30 years. Isotopes with a half-life of longer than 30 years are called long-lived, and ones with a half-life of less than 30 years are short-lived. The longer the half-life, the longer it the radioactive isotope sticks around. This is the time it takes for the number of the nuclei in a given sample of the isotope to decrease by half. The uranium-235 nuclei are unstable when neutrons are fired at them inside the nuclear reactor, they split into smaller nuclei, including strontium-90 and caesium-137.Īll radioactive isotopes have a property called a half-life. This means that 3% to 5% of its mass is uranium-235. Nuclear fuel is typically made of 3% to 5% enriched uranium. Opponents of nuclear power point to high-profile accidents, such as those at Chernobyl and Fukushima, and the issue of the radioactive waste nuclear facilities produce. With the ongoing climate crisis, there is a strong desire to find alternative power sources to carbon-heavy fossil fuels. Here, Matthew Harris explains some of the storage solutions and puts the problem in perspective. Nuclear power is an oft-mentioned alternative to fossil fuels but comes with the associated problem of nuclear waste. While currently, we’re somewhat preoccupied with a different crisis, the climate crisis remains a pressing concern.
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