http://physics.colorado.edu/phys3070Enriched uranium reactorEvolution of the fuel rodWhat to do with the fuel rod?What to do with the fuel rod?Reprocessing/Storage dilemmaClicker questionClicker questionUS decision (1970s)Storage sitesYucca MountainThe storage problemHigh-temperature gas reactorGraphite Breeder ReactorNormal Radioactive OutputJudah Levine, 3070L23 1http://physics.colorado.edu/phys3070http://physics.colorado.edu/phys3070Judah LevineJudah LevineJILA SJILA [email protected]@colorado.edu303 492303 492--7785 (27785 (2--7785)7785)M,F 11M,F 11--Noon, W 1Noon, W 1--3 pm3 pmalso by appointmentalso by appointmentPower point files for all lectures Power point files for all lectures now on the course web pagenow on the course web pageJudah Levine, 3070L23 2Enriched uranium reactorEnriched uranium reactorTotal mass of fuel: 200,000 kg3% 235Fuel rodModeratorWater, graphite, …ControlRodsJudah Levine, 3070L23 3Evolution of the fuel rodEvolution of the fuel rodQQUranium 235 depleted, eventually Uranium 235 depleted, eventually decreases to < 1% or less after 3 yearsdecreases to < 1% or less after 3 years––Converted to lots of stuff Converted to lots of stuff ––not destroyednot destroyed••Neutron Neutron ““poisoningpoisoning””QQUranium 238 converted to plutoniumUranium 238 converted to plutonium––0.5% after 3 years: 0.5% after 3 years: ••200,000 kg of U238 = 1000 kg of plutonium200,000 kg of U238 = 1000 kg of plutonium––90+% Uranium 238 unmodified 90+% Uranium 238 unmodifiedJudah Levine, 3070L23 4What to do with the fuel rod?What to do with the fuel rod?QQReRe--processprocess––Remove radioactive junkRemove radioactive junk••Chemical separation produces terrible soupChemical separation produces terrible soup••Storage problemStorage problem––Produce new fuel and recycleProduce new fuel and recycle••Makes much better use of the fuelMakes much better use of the fuel––Most of the fuel volume is Uranium 238Most of the fuel volume is Uranium 238––Extracts uranium 235 and plutoniumExtracts uranium 235 and plutonium••Using this stuff could extend lifetime 50Using this stuff could extend lifetime 50××or moreor more••PlutoniumPlutonium--only reactors only reactors ––““plutonium economyplutonium economy””••Plutonium is hard to steal Plutonium is hard to steal ––poisonous, corrosive, and poisonous, corrosive, and radioactiveradioactiveJudah Levine, 3070L23 5What to do with the fuel rod?What to do with the fuel rod?QQStore and disposeStore and dispose––Increased volume of required storageIncreased volume of required storage••Where do we put the stuff?Where do we put the stuff?––Bomb material remains in the rodsBomb material remains in the rods••Making bombs becomes more difficultMaking bombs becomes more difficult––Most of the energy content in the uranium Most of the energy content in the uranium is not usedis not usedJudah Levine, 3070L23 6Reprocessing/Storage dilemmaReprocessing/Storage dilemmaQQReprocessing extends the life of uranium by a Reprocessing extends the life of uranium by a large factorlarge factor––Could provide energy needs for centuriesCould provide energy needs for centuries––Not a longNot a long--term option otherwiseterm option otherwise••Will not last as long as coalWill not last as long as coalQQReprocessing extracts plutonium that is hard Reprocessing extracts plutonium that is hard to control and protectto control and protect––Yes, but the bad guys will always find a wayYes, but the bad guys will always find a wayQQReprocessing produces lots of highly Reprocessing produces lots of highly radioactive and chemically dangerous stuffradioactive and chemically dangerous stuff––Look at the mess at Hanford, WashingtonLook at the mess at Hanford, WashingtonJudah Levine, 3070L23 7Clicker questionClicker questionWould you allow reprocessing?A: YesB: NoC: Don’t knowD: Yes, and I will tell you whyE: No, and I will tell you whyAll answers are correctJudah Levine, 3070L23 8Clicker questionClicker questionWould you allow reprocessing?A: Yes before, yes nowB: No before, no nowC: Don’t knowD: Yes before, no nowE: No before, yes nowAll answers are correctJudah Levine, 3070L23 9US decision (1970s)US decision (1970s)QQNo reprocessingNo reprocessing––Uranium was/is cheap and availableUranium was/is cheap and available––Nuclear proliferation is a serious threatNuclear proliferation is a serious threatQQStore fuel rods at power plantsStore fuel rods at power plantsQQ““temporarytemporary””solutionsolutionQQBegin search for permanent siteBegin search for permanent site––Still looking 25+ years laterStill looking 25+ years laterJudah Levine, 3070L23 10Storage sitesStorage sitesQQAt least 1000 years for highAt least 1000 years for high--level stufflevel stuff––Some isotopes will need up to 10Some isotopes will need up to 10××longerlongerQQHanford, WashingtonHanford, Washington––Currently being Currently being ““cleaned upcleaned up””QQSavannah River, South CarolinaSavannah River, South CarolinaQQWaste Isolation Pilot Plant (WIPP)Waste Isolation Pilot Plant (WIPP)––Carlsbad, New MexicoCarlsbad, New MexicoQQAll above limited to Defense DepartmentAll above limited to Defense DepartmentQQYucca Mountain, NevadaYucca Mountain, NevadaJudah Levine, 3070L23 11Yucca MountainYucca MountainQQStable geology, far from current level of Stable geology, far from current level of water tablewater tableQQMany studies of suitability for longMany studies of suitability for long--term storageterm storage––Models involve assumptions about Models involve assumptions about unknownsunknownsQQState of Nevada officially opposed to State of Nevada officially opposed to current use as current use as ““permanentpermanent””sitesiteQQWould be full by 2030/2040 anywayWould be full by 2030/2040 anywayJudah Levine, 3070L23 12The storage problemThe storage problemQQStorage sites at power plants are almost Storage sites at power plants are almost fullfullQQYucca Mountain ?Yucca Mountain ?QQOther sites ?Other sites ?––Deep ocean trenchesDeep ocean trenchesQQWhat do we do next ?What do we do next ?––Design reactors to burn waste productsDesign reactors to burn waste productsQQThoriumThorium--Uranium 233 cycleUranium 233 cycle––Easier storage problemsEasier storage
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