How are the nuclear wastes being handled?

       High-level waste 
       High-level waste mainly comes from spent fuel, which are fuel rods taken out from 
       nuclear reactors. They are either directly disposed or reprocessed. 97% of the spent
       fuel could be reused if they are reprocessed, however, most countries nowadays, 
       including USA and Canada, use the first method to treat their waste.

Direct Disposal
After the fuel rods are taken out of the reactor, 
they are temporarily stored in deep-water 
ponds for several years. This is to allow the 
short-lived radioisotopes to decay before 
further handling commenced, as well as to 
absorb the radiation and heat emitted by them.
Then they are removed from the ponds and 
stored in underwater repositories or dry vaults.

     



     

     
     
     Reprocessing
      After the fuel rods are removed from the reactor,
      they are transported in special containers 
      called flasks to the reprocessing plant. The fuel 
      rods are stored in water tanks for 5 to 10 years, 
      then they are chemically treated to isolate uranium 
      and plutonium. 

      The products are stored in sealed cans for future 
      use. The liquid waste left behind are converted
      into solid in the process of vitrification, in which 
      they are evaporated into dryness and heated 
      with crushed glass to form a glass-like material. 
      Then they are sealed into steel canisters 
      and stored in air-cooled vaults for about 50 years.


       Intermediate-level waste
       Solid wastes are sealed into metal drums, then they are embedded in concrete or in 
       specially designed resins and then in repositories. Liquid wastes like sludge, flocs 
       and evaporator concentrates are dewatered and immobilised with concrete, 
       cement or bitumen.

         Low-level waste
       Solid wastes are often compacted under high pressure and disposed in trenches at
       landfill sites, where they are covered with gravel and soil. Liquid wastes, which are
       mostly water from cooling ponds at reactor sites, are chemically treated to remove
       the radioactive material present. They are then discharged to sea after they are tested 
       to ensure that their remaining radioactivity do not exceed the permitted level.

       The following table summarizes the sources of the above 3 types of radioactive 
       wastes.

 

     Types of waste
 

    
 Sources

     High-level waste
 

    

      
Spent fuel from nuclear reactors
      
Civilian radioactive wastes from medicine,
      industry and research
    

     Intermediate-level waste
 

    

      
Wastes from dismantled nuclear reactors
      and fuel processing plants
      
Filter and ion-exchange resins from reactor
      purification systems in nuclear reactors
      
Solid wastes from reprocessing like fuel
      cladding
      
Civilian radioactive wastes from medicine,
      industry and research
    


     Low-level waste
 

    

      
Residues from mining uranium ores
      
Materials and equipment like protective
      clothing and cleaning materials used in the operation of nuclear
      facilities
      
Civilian radioactive wastes from medicine,
      industry and research
    


    How are the wastes transported?
     Wastes are transported in solid forms, which is easier to handle than liquids or gases. 
     They are transported in heavy steel casks with a neutron absorbing layer and external 
     cooling fans. So far there has not been an accident involving radioactive waste where
     a release of radioactivity has harmed people.

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