Transuranium waste

Transururan waste is a special type of radioactive waste.

definition

In the US , transuranic waste is classified as a separate waste category. From the US Department of Energy (DOE) are defined as "waste with alpha emitters of the atomic numbers 92 and half-lives of over 20 years in concentrations above 100 n Ci / g (3,700  Bq are contaminated / g)". These are the major actinides plutonium and isotopes of the minor actinides neptunium , americium , curium , berkelium and californium .

meaning

The radionuclides mentioned are formed in the fuel of nuclear reactors , but are not fission products , but are created by neutron capture with subsequent beta decay . Transururan waste comes mainly from reprocessing and plutonium processing in the military sector. Their dangerousness lies in their particularly long half-lives , the severe radiation damage when they are absorbed into the body and the toxicity of the artificial heavy metals and their compounds. They therefore require the same long-term insulation as other high-level radioactive waste. However, dealing with them can be easier (without manipulation arms behind thick radiation protection windows) if they only emit alpha radiation and no penetrating gamma and neutron radiation . Absorption into the body must be excluded, for example through protective clothing.

Minor actinides

When a weakly enriched reactor fuel element burns down (left), the proportion of U ²³⁵ decreases and new elements are created

Minore actinides ( English minor actinides ) are the actinides in spent nuclear fuel with the exception of uranium and plutonium , which are called majore actinides. The minor actinides are Neptunium , Americium , Curium , Berkelium , Californium , Einsteinium, and Fermium . Their main isotopes in spent nuclear fuel are neptunium-237, americium-241, americium-243, curium-242 to -248, and californium-249 to -252.

Plutonium and the minor actinides are responsible for a large part of the ionizing radiation and the heat development in spent nuclear fuel over a period of 300 to 20,000 years.

To reduce radiotoxicity , research is being carried out into the possibility of removing the minor actinides from radioactive waste using suitable methods such as liquid-liquid extraction ( partitioning ). Problems are caused by the close chemical relationship with the lanthanoids, which make clean separation difficult. In a second step, the so-called transmutation , the separated minor actinides could be physically converted into shorter-lived cleavage products.

Web links

• Definition of the term transurane waste of the DoD (English, PDF, 189 KiB)

Individual evidence

1. ↑ Research in Jülich - magazine of the Jülich Research Center (PDF) fz-juelich.de. Retrieved November 1, 2009.
2. ↑ Partitioning of minor actinides from HLLW using the DIAMEX process. Part 2 - “Hot” continuous counter-current experiment . www.xolopo.de. Retrieved on November 1, 2009.  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.