1.Radioactivity & Waste

2. For more help contact meMuhammad Umair Bukhari Engr.umair.bukhari@gmail.comwww.bzuiam.webs.com 03136050151 3. Structure of the AtomNucleusNeutrons+ ++ProtonsElectrons(Electron Clouds) 4. Radioactivity DefinitionAny spontaneous change in the state of the nucleusaccompanied by the release of energy. Major Typesalpha ( ) particle emission (decay)beta ( ) particle emission ( -), positronemission ( +) and orbital electron capture(ec)gamma ( ) decay including internalconversion 5. Ionizing Radiation Definition - Any type of radiation possessing enoughenergy to eject an electron from an atom,thus producing an ion.Major Types of Ionizing Radiation Alpha, Beta, Gamma Alpha ParticleLarge Mass (nuclei) Helium + +Atom with a +2 charge Beta Particle Small Mass - Electron (subatomic particle) Gamma Photon No Mass(Electromagneticand X-Rays Radiation) 6. Decayhas a discrete energy that can be measured andrelated to the parent. The neutron to proton ratio is tolow !+ 4He Nucleus + Ejected from Nucleus+++ + + +2++This is radioactive!!Most of the energyassociated with(monoenergetic) 238U 4He + 234Th 7. Decay Either too many neutrons or too many protonsneutrinoChange a neutroninto a protontake away - charge+-+Electron (negatron) + +++++ anti-neutrino Change a proton+ into a neutron +take away + charge(positron)3 products share energy therefore beta has a continuous range of energies 8. Electron Capture X-rayChange proton into neutron X-ray 9. Decay Emission of a photon from the nucleus Most often occurs after or emission when nucleus is left in an excitedstate Given off with discrete energies Can measure photon energy and possibly identify parent + +Gamma Photon+++ + + + + or+2 -neutrino 10. Radiation Dosimetry Units Exposure, X: amount of charge produced anywhere in air by thecomplete stoppage of all electrons liberated by photons in an incremental volume of air per unit mass of air inthat volume.Standard International (SI) unit:Coulomb/kilogram (C/kg)Traditional unit: roentgen ( R )1 R = 2.58x10-4 C/kgExposure definition applies only to photons of energy less than or equal to 3 MeV interacting in air. 11. Radiation Dosimetry UnitsAbsorbed dose: RADis the energy deposited by any type of ionizing radiation in a volume element of mass. SI unit:gray (Gy) Traditional unit: rad 1Gy = 100 radAbsorbed dose definition applies to all forms of ionizingradiation in any material. 12. Relative Biological Effectiveness andQuality Factor Relative Biological Effectiveness (RBE) (Biological effect of radiation Y at dose XBiological effect of 250 kVp x-rays at dose X ) Both produce the same biological effect. Quality factor (Q)radiation Qphoton, 1proton, neutron 10alpha 20 13. Relative Biological EffectivenessLn (S) Shoulder of curve indicates cell repair at low doses No shoulder - no cell repairEffectSame Biological Effect Dn DDifferent Dose from 2types of radiationDose 14. Radiation Dosimetry Units Dose EquivalentDose equivalent: allows the description of the biologicaleffect of an absorbed dose of a particular type of radiation ormixed radiations for the Human Body. Dose Equivalent (DE) in Rem = Dose in Rads x Q SI unit:sievert (Sv) traditional unit:rem1 Sv = 100 rem milliremFor photons: 1 R 1 rad = 1 rem 15. PRECAUTIONSFORAVOIDING UNNECESSARY RADIATION EXPOSURE 16. External Radiation Exposure Definition: Exposure of the body from radiation originating outside of the bodyLevel of Hazard and Control Depend Upon:1. Type of Radiation (Alpha, Beta Gamma)2. Energy of the Radiation (Low or high energy)3. Dose Rate (Low or high dose rate) 17. Reducing External RadiationExposureTime: reduce time spent in radiation areaDistance: stay as far away from the radiation source as possibleShielding:interpose appropriate materials between the source andthe body 18. Radioactive WasteWe will discuss - Low Level Radioactive Waste High Level Radioactive Waste Mining Tailings 19. Radioactive WasteLow 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 persecond) 20. Radioactive Waste Low level radioactive waste consists of: Contaminated solids liquids animal carcasses small sealed sources 21. Radioactive Waste Low level radioactive liquids are either: Incinerated Deep well injected (not as frequent anymore) Solidified Sewer Disposed (Regulations allow curie levelsof some isotopes to be sewer disposed of ifdilution is large enough) 22. Radioactive Waste Radioactive animal carcasses are eitherincinerated or buried onsite. 23. Radioactive Waste Small sealed sourcesare Stabilized inconcrete and buried.Stabilized concrete isconcrete that iscertified to resistwear for a certaintime period. 24. Radioactive Waste Low levelcontaminated solidwastes are buried.GSU has its solidwasteSupercompactedat 30,000 psi toreduce the volume tobe buried 25. Radioactive WasteMost low level wastes come from Governmentand Utilities. These consist of contaminatedsolids from nuclear reactor usage and weaponconstruction. 26. Radioactive Waste Colleges, research and medical applicationsaccount for less than 25% of the low levelRadioactive wastes created 27. Radioactive Waste Class A low-level radioactive waste is the least hazardous,containing mostly short-lived radionuclides that will bereduced in radioactivity (decay) in a relatively short time.It contains only small amounts of radionuclides that take arelatively short time to decay. Class A waste will bedisposed of in concrete canisters that will maintain theirshape and strength for hundreds of years. 28. Radioactive Waste Class B low-level radioactive waste is more hazardousthan Class A waste. Most of it comes from nuclearreactors. It must be in a stable form for disposal and willalso be disposed of in concrete canisters. Stabilization canbe accomplished by solidifying liquid waste, compactingsolid waste, or placing the low-level radioactive waste in acontainer that will be stable for many years. Class B low-level radioactive waste makes up only a small percent ofthe waste volume generated; but along with Class C waste,it contains the largest portion of the total radioactivity. 29. Radioactive Waste Class C low-level radioactive waste is themost hazardous and must be handledaccordingly. It also must be disposed of in astable form. 30. Radioactive Waste 31. Radioactive Waste There are 3LLRWBurial sites: Hanford Envirocare Barnwell 32. Radioactive Waste 33. Radioactive Waste 34. Radioactive Waste Politics of LLRW Compacts On-site burial NIMBY 35. Radioactive Waste The compact system was set up by NRC tohave all states share in the responsibility ofdisposal of radioactive waste and to limitwaste transport distance. Georgia is in theSoutheast compact. Until 1992, all states within the SE compact(excluding Florida) would host a LLRWlandfill on a 20-25 year revolving timetable. 36. Radioactive Waste Kentucky was the first (Maxie Flats), then SouthCarolina (Barnwell). In 1995, North Carolina wasto 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 ofwaste. Other States followed N.C.s lead andrefused This lead to the collapse of the traditional compactsystem and the 37. Radioactive Waste 38. Radioactive WasteIn the past, many Universities andcompanies were allowed to bury theirradioactive wastes onsite. Some wereallowed to deep well inject liquidradioactive waste. 39. Radioactive WasteN.I.M.B.Y.NotInMyBackYardThe true politics of Hazardous Waste 40. Radioactive WasteDid North Carolina, by not opening up a waste site, better protect its citizens? 41. Radioactive Waste High-Level Radioactive Waste is: theirradiated fuel from the cores of nuclearreactors, the liquid and sludge wastes thatare left over after irradiated fuel has beenreprocessed (a procedure used to extracturanium and plutonium), the solid thatwould result from efforts to solidify thatliquid and sludge from reprocessing. 42. Radioactive WasteBecause there is currently no high level radioactive waste disposal facility, HLRW is held On-Site in water pools 43. Radioactive WasteOnce these Pools are full, Waste is transferred to casks which are also held on-site 44. Radioactive Waste 45. Radioactive WasteA HLRW repository is being constructed at Yucca Mountain in Nevada to hold all this waste. NIMBY again is playing a role in the opening 46. Radioactive WasteYOUR THOUGHTS AND DISCUSSION