A Presentation On DISPOSAL OF NUCLEAR WASTE

Introduction Nuclear Waste Sources Health Risks Requirements of Disposal Treatment Methods Conclusion References

The current methods of storage are running out of space and are not intended for long-term use. The government was required by the Nuclear Waste Policy Act of 1982 to provide long-term storage for waste

The US has more than 64,000 metric tons of nuclear waste “Enough to cover a football field about seven yards deep”. The half-life of the fuel is more than 1 million years. Legal requirements: Nuclear Waste Policy Act of

Composed of radionuclides Low, Medium, and High-level waste High-level waste produced in nuclear reactors Consists of Fission products (short-half lives) Actinides (long-half lives) Of note: 99 Tc, 129 I, 239 Pu, 240 Pu, 235 U, 238 U

Somatic Effects Cancer Genetic Effects Hereditary Genetic Damage Teratogenic Effects Birth defects Prenatal death

Design and Fabricate a System that will Last thousands of years longer than recorded human history Be robust enough to isolate highly radioactive material so that it will not threaten human health and environment for more than ten thousand years.

Isotopes with short half-lives are gone quickly, those with long half-lives will decay too little Low level wastes: 90% of all radioactive wastes 20 temporary and 6 commercial disposal sites States to take care of their low level waste High level wastes e.g., spent nuclear fuel rods Should be so disposed as to cause less than 1000 death in 10,000 years

Most common initial treatment of waste is Vitrification. Waste is first mixed with sugar and then passed through a heated tube to de-nitrite the material. This material is then fed into a furnace and mixed with glass. The molten glass mixture is poured into steel cylinders and welded shut.

Mid level active waste is commonly treated with ion exchange. Process reduces the bulk volume of radioactive material. Typically, mixed with concrete for a solid storage form.

Most common method for handling nuclear waste. Typically kept separate from actual plants and buried far below ground. First used in 1999 in the US. Current research is focusing on Yucca Mountain. Yucca Mountain Site

1982: Nuclear Waste Policy Act.  Congress charges DOE with the task  Two high level waste depository in the eastern and the western USA  Billions collected from tax on utilities. Feb 15, 2002: Pres. Bush approved Yucca Mtn as the site for high level nuclear waste respository.

Layer of compacted trash covered with a layer of earth once a day and a thicker layer when the site is full. Require impermeable barriers to stop escape of leachates: can cause problem by overflow. Gases produced by decomposing garbage needs venting. 1 acre/10,000 people: acute space problem: wastes piling up over 150 million tons/year.

Reduces transuranic waste. Integral Fast Reactor. Banned (U.S.) MOX Fuel Behaves as low-enriched uranium. Research now in subcritical reactors. Fusion also being researched.

Removes the waste from the biosphere entirely. High risk of space vehicle failure. High energy cost of space launch. Relatively limited volume per launch. High cost.

Out of sight, free of emission control norms. Contributes to ocean pollution. Can wash back on beaches, and can cause death of marine mammals. Preferred method: Incineration in open sea. Ocean Dumping Ban Act, 1988: Bans dumping of sewage sludge and industrial waste.

Research is being performed to find uses for nuclear waste. Caesium-137 and strontium-90 already used in industrial applications. Some waste can be used for radioisotope thermoelectric generators (RTGs). Overall can reduce total HLW but not eliminate it.

CONCLUSION Optimization of ion exchange.  Results in compact form of waste that will not interact with biosphere. Research and Pursuit of Deep Boreholes.  Further development of deep boreholes that are more reliable are an ideal option  Reasonable Cost  Global availability  Human Safety

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