Uranium biological half-life

Some 20% is assumed to enter the blood compartment. The ICRP biokinetic model for radium has the same general structure as that for strontium and uranium (see Figure 26.2-2). Bone is the critical organ with a biological half-life for radium in the range of 20 years. Since the decay of radium leads to the noble gas radon with a physical half-life of 3.8 days, most of the radioactivity of the decay product escapes from the body before further decays occur. 

Ten mg U has been collected in the kidneys. Considering the biological half-life of uranium and assuming only one a-emission in decay, calculate the dose On Sv) received by the organ if the uranium is evenly distributed. The weight of a kidney is 150 g. 

Type S 0.1% absorbed with a biological half-life of 10 min and 99.9% with a biological half-life of 7000 d. There is little absorption from ET, BB or bb, and about 10% of the deposit in AI eventually reaches body fluids by absorption. Insoluble compounds of uranium and plutonium... 

Storage of spent nuclear fuel poses a major problem because the fission products are extremely radioactive. It is estimated that 20 half-lives are required for their radioactivity to reach levels acceptable for biological exposure. Based on the 28.8-yr half-life of strontium-90, one of the longer-lived and most dangerous of the products, the wastes must be stored for 600 years. Plutonium-239 is one of the by-products present in spent fuel elements. It is formed by absorption of a neutron by uranium-238, followed by two successive beta emissions. (Remember that most of the uranium in the fuel elements is uranium-238.) If the elements are reprocessed, the plutonium-239 is largely recovered because it can be used as a nuclear fiieL However, if the plutonium is not removed, spent elements must be stored for a very long time because plutonium-239 has a half-life of24,000 yr. 

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