MKSSSs Cummins College of Engineering for Women Pune

MKSSS’s Cummins College of Engineering for Women, Pune Management of Radioactive Waste P. S. Chaware .

Definition of radioactive waste • Radioactive waste is any material that is either radioactive itself or is contaminated by radioactivity, for which no further use is envisaged

Categories of Radioactive Waste • The term ‘radioactive waste’ covers a wide variety of material, ranging from wastes that can be put safely into a dustbin to items that need remote handling, heavy shielding and cooling to be managed safely. To be clear, radioactive waste is considered in different categories. – Low Level – Intermediate Level – High Level

Categories of Radioactive Waste • Low level waste is not dangerous but sometimes requires shielding during handling. • Intermediate level waste typically is chemical sludge and other products from reactors. • High level waste consists of fissionable elements from reactor cores and transuranic wastes. • Transuranic waste is any waste with transuranic alpha emitting radionuclides that have half-lives longer than 20 years.

Low Level Waste (LLW) • Low level waste is any waste that could be from a high activity area. • 90% volume of waste • It does not necessarily carry any radioactivity. • Split into four catagories: A, B, C, and GTCC.

Intermediate Level Waste (ILW) • Intermediate level waste requires shielding when being handled. • 7% volume of waste • Dependent on the amount of activity it can be buried in shallow repositories.

High Level Waste (HLW) • High level waste has a large amount of radioactive activity and is thermally hot. • 95% of radioactivity • Current levels of HLW are increasing about 12, 000 metric tons per year. • Most HLW consists of Pu-238, 239, 240, 241, 242, Np-237, U-236

Transuranic Waste (TRUW) • Transuranic waste consists of all waste that has radionuclides above uranium. • TRUWs typically have longer half-lives than other forms of waste. • Typically a byproduct of weapons manufacturing.

Creation of Nuclear Waste • Nuclear waste is generated at all points of the fuel cycle. • Front end waste consists primarily of low level alpha emission waste. • Service period waste typically includes LLW and ILW such as contaminated reactor housings and waste from daily operation. • Back end waste normally is the most radioactive and includes spent fuel rods and reactor cores.

Front End Waste • Front end waste consists mostly of LLW and ILW. • The primary front end waste is depleted uranium and radium. – DU has several uses due to its high density (19, 050 kg/m 3). – Mix with uranium to form reactor fuel

Service Period Waste • Consists of mostly ILW. • Mostly waste produced at the plant during normal operation. • Spent fuel rods are the most dangerous waste produced during the service period.

Back End Waste • Nuclear waste developed during the back end of the fuel cycle is the most dangerous and includes most of the HLW produced. • Most back end waste emits both gamma and beta particles. • Also uranium-234, neptunium-237, plutonium-238 and americium-241 are found in back end waste. Spent nuclear fuel in a cooling pond in North Korea.

• Once created, radioactive waste will undergo some of the following stages depending on the type of waste and the strategy for its management • Pretreatment – is the initial step that occurs just after waste generation. It may involve collection, segregation, chemical adjustment and decontamination and may also include a period of interim storage. The aim of this step is to segregate waste into streams that will be managed in similar ways, and to isolate non-radioactive wastes or those materials that can be recycled.

• Treatment – involves changing the characteristics of the waste by volume reduction, radionuclide removal or change of composition. Typical treatment operations include: – Compaction of dry solid waste or incineration of solid or organic liquid wastes (volume reduction); – Ciltration or ion exchange of liquid waste (radionuclide removal); and – Precipitation or flocculation of chemical species (change of composition).

• Conditioning – Involves transforming radioactive waste into a form that is suitable for handling, transportation, storage and disposal.

• Storage – Waste might be stored for many years before it undergoes further processing and disposal. Some storage facilities are located within a nuclear power plant or a licensed disposal facility, others are separate facilities.

Methods of Disposal • N- Waste can be disposed of following ways – – Deep Geological Disposal Reprocessing Transmutation Space Disposal

Deep Geological Disposal • The process of geological disposal centers on burrowing nuclear waste into the ground to the point where it is out of human reach. • Concerns; – Material leak – Contamination of water table – Terrorism

Reprocessing • Involves taking waste and separating the useful components from those that aren’t as useful. • Involves taking the fissionable material out from the irradiated nuclear fuel. • Concerns; – Nuclear Proliferation – How much easier re-processing would allow fissionable material to spread.

Transmutation • Transmutation – Involves converting a chemical element into another less harmful one – Common conversions include going from Chlorine to Argon or from Potassium to Argon

Space Disposal • Putting nuclear waste on a space shuttle and launching the shuttle into space. • Concerns; – Amount of nuclear waste that could be shipped on a single shuttle would be extremely small compared to the total amount of waste that would need to be dealt with. – Possibility of the shuttle exploding en route to space could only make the matter worse