radioactive waste management ppt
TRANSCRIPT
ASSIGNMENT-1 ASSIGNMENT-1 This ppt is presented by:-This ppt is presented by:-
ADITYA KUMAR SAHUROLL NO:-411PH5082
INTEGRATED MSc. IN PHYSICSNIT,ROURKELA
Nuclear Waste…Why?Nuclear Waste…Why?
•Recently nuclear power has entered many discussions as
world energy needs rise and oil reserves diminish.
•Most opponents of nuclear power point to two main
arguments: meltdowns and nuclear waste.
•Nuclear waste is any form of byproduct or end product that
releases radioactivity.
•How to safely dispose of nuclear waste is pivotal for the
continued operation of nuclear power plants, safety of people
living around dump sites, and prevention of proliferation of
nuclear materials to non-nuclear states
Nuclear Fuel Cycle
Most nuclear waste comes from the byproducts of the nuclear fuel cycle. The cycle typically is split into three sections: front end, service period, and back end. There can be intermediate stages that include the reprocessing of nuclear waste elements.
Radioactive WasteRadioactive Waste
We will discuss -Low Level Radioactive WasteHigh Level Radioactive WasteMining Tailings
ClassificationsClassificationsNuclear waste is segregated into several
classifications.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 is any waste that could be from a high activity area.
90% volume of wasteIt does not necessarily carry any
radioactivity.Split into four catagories: A, B, C, and
GTCC.
Low Level WasteLow Level WasteLLWLLW
Intermediate Level WasteIntermediate Level WasteILWILW
Intermediate level waste requires shielding when being handled.
7% volume of wasteDependent on the amount of activity it can
be buried in shallow repositories. Not recognized in the United States.
High Level WasteHigh Level WasteHLWHLW
High level waste has a large amount of radioactive activity and is thermally hot.
3% volume of waste95% of radioactivityCurrent 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 WasteTransuranic WasteTRUWTRUW
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.
Only recognized in the United States.
Creation of Nuclear WasteCreation 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 WasteFront 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/m3).– Mix with uranium to form reactor fuel
Service Period WasteService 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 WasteBack 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-241are found in back end waste.
Spent nuclear fuel in a cooling pond in NorthKorea.
Low Level Radioactive WasteLow Level Radioactive Waste
Low Level Radioactive waste consists of microcurie, millicurie and at times curie activity waste.
(A Curie is a unit of nuclear transformations. 1 Curie is 3.7 x1010 transformations per second)
Low Level Radioactive WasteLow Level Radioactive Waste
Low level radioactive waste consists of:– Contaminated solids– liquids– animal carcasses– small sealed sources
There are several options available for the disposal of LLW due to its lack of radioactivity.
Waste Isolation Pilot Plant
On-site disposal
Waste Management (LLW)Waste Management (LLW)
Map of WIPP Facility
Radioactive WasteRadioactive Waste
Low level radioactive liquids are either:– Incinerated– Deep well injected (not as frequent anymore)– Solidified– Sewer Disposed (Regulations allow curie levels
of some isotopes to be sewer disposed of if dilution is large enough)
Radioactive WasteRadioactive Waste
Radioactive animal carcasses are either incinerated or buried onsite.
Radioactive WasteRadioactive Waste
Small sealed sources are “Stabilized” in concrete and buried. Stabilized concrete is concrete that is certified to resist wear for a certain time period.
Radioactive WasteRadioactive Waste
Low level contaminated solid wastes are buried. GSU has it’s solid waste “Supercompacted” at 30,000 psi to reduce the volume to be buried
Radioactive WasteRadioactive Waste
Most low level wastes come from Government and Utilities. These consist of contaminated solids from nuclear reactor usage and weapon construction.
Radioactive WasteRadioactive Waste
Colleges, research and medical applications account for less than 25% of the low level Radioactive wastes created
Radioactive WasteRadioactive Waste
Class A low-level radioactive waste is the least hazardous, containing mostly short-lived radionuclides that will be reduced in radioactivity (decay) in a relatively short time. It contains only small amounts of radionuclides that take a relatively short time to decay. Class A waste will be disposed of in concrete canisters that will maintain their shape and strength for hundreds of years.
Radioactive WasteRadioactive Waste
Class B low-level radioactive waste is more hazardous than Class A waste. Most of it comes from nuclear reactors. It must be in a stable form for disposal and will also be disposed of in concrete canisters. Stabilization can be accomplished by solidifying liquid waste, compacting solid waste, or placing the low-level radioactive waste in a container that will be stable for many years. Class B low-level radioactive waste makes up only a small percent of the waste volume generated; but along with Class C waste, it contains the largest portion of the total radioactivity.
Radioactive WasteRadioactive Waste
Class C low-level radioactive waste is the most hazardous and must be handled accordingly. It also must be disposed of in a stable form.
Radioactive WasteRadioactive Waste
The compact system was set up by NRC to have all states share in the responsibility of disposal of radioactive waste and to limit waste transport distance. Georgia is in the Southeast compact.
Until 1992, all states within the SE compact (excluding Florida) would host a LLRW landfill on a 20-25 year revolving timetable.
Radioactive WasteRadioactive Waste
Kentucky was the first (Maxie Flats), then South Carolina (Barnwell). In 1995, North Carolina was to open a site but the citizens protested and sued. The State legislature refused.
North Carolina was then “kicked out” of the S.E. compact and left with no place to dispose of waste. Other States followed N.C.’s lead and refused
This lead to the collapse of the traditional compact system and the
Radioactive WasteRadioactive Waste
In the past, many Universities and companies were allowed to bury their radioactive wastes onsite. Some were allowed to deep well inject liquid radioactive waste.
Radioactive WasteRadioactive Waste
N.I.M.B.Y.
Not
In
My
Back
Yard
The true politics of Hazardous Waste
Fear of radiation because they don’t understand it
Concern that the waste facility willrelease long-term contamination
Worry that property values will be reducedwith construction of a waste facility
Belief that power companies are the ones responsible for storing their own waste
People don’t want dumped on by otherpeoples’ waste
Belief that nuclear power should just goaway and be replaced by other energyresources
Environmental concerns
NIMBY: Not In My Back YardNIMBY: Not In My Back Yard
Typical Low-Level Waste Typical Low-Level Waste Disposal SiteDisposal Site
Hanford (Nuclear News, November 2004)
Treatment (LLW)Treatment (LLW)
FiltrationIon ExchangeEvaporationIncinerationCompactionSolidification
Typical LLW treatment facility.
Waste Management (HLW)Waste Management (HLW)
Most common utilized option are reactor pools and dry cask storage.
Other Options for waste management include:– Deep Geologoical
Storage– Transmutation– Reuse– Launching it into space
Locations of storage sites for nuclear waste in the U.S.
High-Level Radioactive WasteHigh-Level Radioactive Waste
High-Level Radioactive Waste is: the irradiated fuel from the cores of nuclear reactors, the liquid and sludge wastes that are left over after irradiated fuel has been reprocessed (a procedure used to extract uranium and plutonium), the solid that would result from efforts to solidify that liquid and sludge from reprocessing.
Radioactive WasteRadioactive Waste
Because there is currently no high level radioactive waste disposal facility, HLRW is held On-Site in water pools
Radioactive WasteRadioactive WasteOnce these
Pools are full, Waste is transferred to casks which are also held on-site
Radioactive WasteRadioactive Waste
A HLRW repository is being constructed at Yucca Mountain in Nevada to hold all this waste. NIMBY again is playing a role in the opening
TreatmentTreatment
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.
Treatment (Cont.)Treatment (Cont.)
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.
Deep Geological RepositoryDeep Geological Repository
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
Transmutation of Nuclear Transmutation of Nuclear WasteWaste
Reduces transuranic waste. Integral Fast ReactorBanned 1977-1981 (U.S.)MOX Fuel
– Behaves as low-enriched uranium
Research now in subcritical reactors.Fusion also being researched.
Reuse of Nuclear WasteReuse of Nuclear 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.
Launch it into SpaceLaunch it into Space
Near infinite storage space
Completely removes waste from biosphere
Technical risks and problems
Political entanglements
Yucca MountainYucca Mountain
For more information, http://www.ocrwm.doe.gov/ymp/index.shtml
Yucca Mountain• Technically sound
• 1,000’ below
ground
• Repository in block
of solid rock
• 1,000’ above water
table
• Remote location on Nevada
Test Range
It is better to have used nuclear fuel in one location
Built forBuilt for300 years of retrieval300 years of retrieval
10,000 years of storage10,000 years of storage
Waste IsolationWaste IsolationPilot PlantPilot Plant
Opened March 26, 1999 Storage of transuranic
waste leftover from research an production of nuclear weapons
http://www.wipp.energy.gov/
http://www.radiochemistry.org/wipp_tour/index.html
Private Fuel StoragePrivate Fuel Storage(Skull Valley, Utah)(Skull Valley, Utah)
Temporary storage of spent nuclear fuel until Yucca Mountain is operational
Goshute Indian Skull Valley Band
3-ft thick concrete storage pads
http://www.privatefuelstorage.com/ http://www.kued.org/skullvalley/
ConclusionsConclusions
HLW is most dangerous byproduct of nuclear power.
Borosilicate glass most common storage.
Several venues being researched for the safe disposal of HLW.