NUCLEAR WASTE: NUCLEAR WASTE: STORAGE AND STORAGE AND

DISPOSALDISPOSALSanta Rosa Junior CollegeSanta Rosa Junior College

Physics 4D, Spring 2006Physics 4D, Spring 2006

Presented by : Philip Mutunga and Michael SeremPresented by : Philip Mutunga and Michael Serem

Date: May 11, 2006Date: May 11, 2006

SOURCES OF NUCLEAR SOURCES OF NUCLEAR WASTEWASTE

• The increasing amount of excess military plutonium The increasing amount of excess military plutonium worldwide (as warheads are dismantled, plutonium worldwide (as warheads are dismantled, plutonium is a left over).is a left over).

• The increasing amount of civilian plutonium from The increasing amount of civilian plutonium from nuclear power plants.nuclear power plants.

• The increasing amount of separated plutonium The increasing amount of separated plutonium from the reprocessing of spent nuclear fuel.from the reprocessing of spent nuclear fuel.

• Material left from nuclear research reactors.Material left from nuclear research reactors.

CATEGORIES OF NUCLEAR CATEGORIES OF NUCLEAR WASTEWASTE

• Very Low Level Waste (VLLW)Very Low Level Waste (VLLW) -Covers wastes with very low concentrations of radioactivity. -Covers wastes with very low concentrations of radioactivity.

-Sources including hospitals and industry in general. Because-Sources including hospitals and industry in general. Because

-VLLW contains little total radioactivity, it can be disposed of safely -VLLW contains little total radioactivity, it can be disposed of safely with domestic refuse either directly at landfill sites or indirectly with domestic refuse either directly at landfill sites or indirectly after incineration. after incineration.

• Low Level Waste (LLW)Low Level Waste (LLW)--Includes metals, soil, building rubble and organic materials which Includes metals, soil, building rubble and organic materials which arise principally as lightly contaminated miscellaneous scrap.arise principally as lightly contaminated miscellaneous scrap.

• - Organic materials are mainly in the form of paper towels, clothing - Organic materials are mainly in the form of paper towels, clothing and laboratory equipment that have been used in areas where and laboratory equipment that have been used in areas where radioactive materials are used - such as hospitals, research radioactive materials are used - such as hospitals, research

establishments and industryestablishments and industry..

CATEGORIES OF NUCLEAR CATEGORIES OF NUCLEAR WASTEWASTE• Intermediate Level Waste (ILW)Intermediate Level Waste (ILW)

--This is waste with radioactivity levels exceeding the upper This is waste with radioactivity levels exceeding the upper boundaries for LLW but which does not need heating to be boundaries for LLW but which does not need heating to be taken into account in the design of storage or disposal taken into account in the design of storage or disposal facilities.facilities.

-ILW arises mainly from the reprocessing of spent fuel, and -ILW arises mainly from the reprocessing of spent fuel, and from general operations and maintenance of radioactive plant.from general operations and maintenance of radioactive plant.

-The major components of ILW are metals and organic -The major components of ILW are metals and organic materials, with smaller quantities of cement, graphite, glass materials, with smaller quantities of cement, graphite, glass and ceramics.and ceramics.

• High Level Waste (HLW)High Level Waste (HLW)--High level Waste (HLW) is heat generating waste that has High level Waste (HLW) is heat generating waste that has accumulated since the early 1950s primarily from the accumulated since the early 1950s primarily from the reprocessing of spent nuclear fuel.reprocessing of spent nuclear fuel.

-The temperature in HLW may rise significantly, so this factor -The temperature in HLW may rise significantly, so this factor has to be taken into account in designing storage or disposal has to be taken into account in designing storage or disposal facilities. As with ILW, facilities. As with ILW, there is currently no final management there is currently no final management

strategy for HLWstrategy for HLW..

STORAGE METHODS.STORAGE METHODS.

1.1. Above Ground Above Ground Storage.Storage.

• ILW ILW • Advantage –easy Advantage –easy

access to future access to future generations.generations.

Disadvantages:Disadvantages:• -radiological burden -radiological burden

to future to future generations.generations.

• -space consumption. -space consumption.

  

A dry-cask storage apparatus.

STORAGE METHODS.STORAGE METHODS.

2.2.Disposal at SeaDisposal at Sea..

• -Used in the past but no longer legal. -Used in the past but no longer legal.

3.3.Sub-Seabed DisposalSub-Seabed Disposal..

• -Disposal in empty off shore oil and gas fields.-Disposal in empty off shore oil and gas fields.

• -Usually used for disposal of HLW-Usually used for disposal of HLW

STORAGE METHODS.STORAGE METHODS.

4. 4. Outer SpaceOuter Space

• -Too many rocket launches required-not -Too many rocket launches required-not economically feasible.economically feasible.

• -Potential for catastrophic launch failure.-Potential for catastrophic launch failure.

5. 5. Ice sheetsIce sheets

• For disposal of HLW.For disposal of HLW.

• Considered unacceptable because of lack of Considered unacceptable because of lack of confidence in these wastes.confidence in these wastes.

STORAGE METHODS.STORAGE METHODS.6.6. Partitioning and Transmutation (P&T) Partitioning and Transmutation (P&T) • -Partitioning is the separation of long lived radio nuclides -Partitioning is the separation of long lived radio nuclides

from waste into short lived nuclides.(by chemical means)from waste into short lived nuclides.(by chemical means)• -Transmutation is the transformation of -Transmutation is the transformation of thesethese nuclides into nuclides into

shorter lives or stable nuclides. (in a reactor or particle shorter lives or stable nuclides. (in a reactor or particle acc.)acc.)

Practical DifficultiesPractical Difficulties: : • -Requires re-handling of waste and thus further exposure -Requires re-handling of waste and thus further exposure

to workers to radioactivity.to workers to radioactivity.• -Requires building of additional activities close to source of -Requires building of additional activities close to source of

waste –added expense.waste –added expense.• -Works only for certain short lived particles.-Works only for certain short lived particles.• Technology still under-developedTechnology still under-developed

STORAGE METHODS.STORAGE METHODS.

77..Subduction Zones.Subduction Zones.• Most viable storage Most viable storage

method proposed.method proposed.• -Subduction zones are -Subduction zones are

areas both above land areas both above land and beneath ocean floors and beneath ocean floors

• Subduction refers to a Subduction refers to a process in which one process in which one tectonic plate slides tectonic plate slides beneath another at rate beneath another at rate of about 6 cm annually, of about 6 cm annually, while being reabsorbed while being reabsorbed into the Earth's mantle. into the Earth's mantle.

STORAGE METHODS.STORAGE METHODS.

• The idea is that the waste is removed from The idea is that the waste is removed from the biosphere faster than it can return.  the biosphere faster than it can return.     

• As the plate is reabsorbed, the waste will As the plate is reabsorbed, the waste will be absorbed along with the plate where it be absorbed along with the plate where it will be dispersed through the mantle. will be dispersed through the mantle. 

• The plate moves slowly so that any The plate moves slowly so that any fractures over a repository would be sealed fractures over a repository would be sealed at the contact point between the at the contact point between the overriding plate and the subducting plate.overriding plate and the subducting plate.

STORAGE METHODS.STORAGE METHODS.•     Once the waste is carried into the Once the waste is carried into the

interior of the Earth, it would take interior of the Earth, it would take many millions of years "for the waste many millions of years "for the waste to circulate through the Earth's to circulate through the Earth's mantle.mantle.

• It could re-emerge in a diluted, It could re-emerge in a diluted, chemically and physically altered chemically and physically altered form at an oceanic ridge.form at an oceanic ridge.

8. 8. Underground Underground Storage.Storage.

• Nuclear material Nuclear material buried in dried buried in dried stable geological stable geological formation (eg salt formation (eg salt mines)mines)

• 1500 feet below 1500 feet below ground level.ground level.

STORAGE METHODS.STORAGE METHODS.

STORAGE METHODS.STORAGE METHODS.Layers Of Protection.Layers Of Protection.The principal barriers are: The principal barriers are: • Locate deep underground in a stable rock Locate deep underground in a stable rock

structure.structure.• Immobilise waste in an insoluble matrix, eg Immobilise waste in an insoluble matrix, eg

borosilicate glass, Synroc (or leave them as borosilicate glass, Synroc (or leave them as uranium oxide fuel pellets - a ceramic) uranium oxide fuel pellets - a ceramic)

• Seal inside a corrosion-resistant container, eg Seal inside a corrosion-resistant container, eg stainless steel stainless steel

• In wet rock: surround containers with bentonite In wet rock: surround containers with bentonite clay to inhibit groundwater movement clay to inhibit groundwater movement

STORAGE METHODS.STORAGE METHODS.

• After being buried for about 1,000 years most of After being buried for about 1,000 years most of the radioactivity will have decayed. The amount the radioactivity will have decayed. The amount of radioactivity then remaining would be similar of radioactivity then remaining would be similar to that of the naturally-occurring uranium ore to that of the naturally-occurring uranium ore from which the fuel originated, though it would from which the fuel originated, though it would be more concentrated.be more concentrated.

• Site the repository in a remote location. Site the repository in a remote location. (eg of proposed site in the US- Yucca (eg of proposed site in the US- Yucca mountain in Nevada)mountain in Nevada)

STORAGE METHODS.STORAGE METHODS.

Disadvantages of Underground StorageDisadvantages of Underground Storage::• high-level waste from nuclear reactors may may high-level waste from nuclear reactors may may

contain contain reactor-grade plutoniumreactor-grade plutonium ( a mixture of ( a mixture of 239239Pu Pu and and 240240Pu)Pu)

- - 240240Pu : an undesirable contaminant and highly Pu : an undesirable contaminant and highly radioactive radioactive - - 239239Pu: highly suitable for building weapons.Pu: highly suitable for building weapons.

• 240240Pu decays faster than the Pu decays faster than the 239239Pu, and thus the Pu, and thus the quality of the bomb material increases with time quality of the bomb material increases with time [although its quantity decreases].(Half life: [although its quantity decreases].(Half life: 240240Pu is Pu is 6,560 years and 6,560 years and 239239Pu is 24,110)Pu is 24,110)

STORAGE METHODS.STORAGE METHODS.

Disadvantages of Underground StorageDisadvantages of Underground Storage::

• These deep storage areas have the potential to become These deep storage areas have the potential to become "plutonium mines", from which material for nuclear "plutonium mines", from which material for nuclear weapons can be acquired with relatively little difficulty.weapons can be acquired with relatively little difficulty.

• Critics of the latter idea point out that the relative Critics of the latter idea point out that the relative enrichment of one isotope to the other with time occurs enrichment of one isotope to the other with time occurs with a half-life of 9,000 years.with a half-life of 9,000 years.

• That is, it takes 9000 years for the quantity of That is, it takes 9000 years for the quantity of 240240Pu in a Pu in a sample of plutonium to spontaneously decrease by half.sample of plutonium to spontaneously decrease by half.

STORAGE METHODS.STORAGE METHODS.

• This implies that "weapons grade plutonium This implies that "weapons grade plutonium mines" would be a problem for the very far mines" would be a problem for the very far future, and there yet remains a great deal of time future, and there yet remains a great deal of time for technology to advance to solve the problem, for technology to advance to solve the problem, before it becomes acute.before it becomes acute.

• One solution to this problem is to recycle the One solution to this problem is to recycle the plutonium and use it as a fuel e.g. in plutonium and use it as a fuel e.g. in fast reactorsfast reactors. In pyrometallurgical . In pyrometallurgical fast reactorsfast reactors, the waste , the waste generated is an actinide compound that cannot generated is an actinide compound that cannot be used for nuclear weapons.be used for nuclear weapons.

The End.The End.

STORAGE METHODSSTORAGE METHODSWORKS CITEDWORKS CITED

• http://en.wikipedia.org/wiki/Radioactive_waste)  http://en.wikipedia.org/wiki/Radioactive_waste) 

• http://en.wikipedia.org/wiki/integral_Fast http://en.wikipedia.org/wiki/integral_Fast _Reactor _Reactor

• http://www.dti.gov.uk/nuclearcleanup/tl/http://www.dti.gov.uk/nuclearcleanup/tl/tlnwr.htm#sourcestlnwr.htm#sources

• http://www.etsu.edu/writing/3120f99/zctb3/http://www.etsu.edu/writing/3120f99/zctb3/nuclear2.htmnuclear2.htm

• http://www.epa.gov/radiation/docs/radwaste/http://www.epa.gov/radiation/docs/radwaste/index. Htmindex. Htm

• http://www.uic.com.au/wast.htmhttp://www.uic.com.au/wast.htm