Sunday, December 27, 2009

Types of radioactive waste (radwaste) / Waste management

Exempt waste contains such a low con­centration of activity that it does not need to be treated differently from ordinary non-radioactive waste;

Low-level Waste is generated from hospitals, laboratories and industry, as well as the nuclear fuel cycle. It comprises paper, rags, tools, clothing, filters etc. which contain small amounts of mostly short-lived radioactivity. It is not dangerous to handle, but must be disposed of more carefully than normal garbage. Usually it is buried in shallow landfill sites. To reduce its volume, it is often compacted or incinerated (in a closed container) before disposal. Worldwide it comprises 90% of the volume but only 1% of the radioactivity of all radwaste.

Intermediate-level Waste contains higher amounts of radioactivity and may require special shielding. It typically comprises resins, chemical sludges and reactor components, as well as contaminated materials from reactor decommissioning. Worldwide it makes up 7% of the volume and has 4% of the radioactivity of all radwaste. It may be solidified in concrete or bitumen for disposal. Generally short-lived waste (mainly from reactors) is buried, but long-lived waste (from reprocessing nuclear fuel) will be disposed of deep underground.



Typical sources

Type of waste

Normal municipal refuse disposal facilities

Can be treated as normal refuse

Contains very limited amounts of radionuclides

Exempt waste

Mine tailings dams- return high grade tailings underground

Huge volumes

Mine tailings

Mining waste

Mine tailings for low grades, on surface storage for higher grades

Enhanced levels of naturally occurring radionuclides

Waste from minerals processing scale from pipes or equipment

NORM waste

Shorter lived in near surface disposal facilities or intermediate _ depth mined caverns (from around 60 to100 m depth)

Longer lived stored pending development of deeper disposal facilities

Limited heat generation

Contaminated paper, clothing, laboratory equipment, contaminated soil and building materials

Ion exchange materials from treatment of effluents sludges from cooling ponds

Low/ intermediate level waste

Geological disposal, consideration being given to intermediate depth storage (tens of metres)

Treated as a special category in some countries

As Iow/intermediate level waste, but with alpha (especially plutonium) contamination

Alpha waste

Geological disposal (a few hundred metres deep in stable geological formations)

Need heavy shielding and cooling

Spent fuel (when treated as waste)

Highly active liquor from reprocessing

High level waste

Table (15): Radioactive waste classification

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