GEORGIA STATE UNIVERSITY. Peter Farina 404-651-4866. Radioactivity & Waste. Structure of the Atom. Nucleus. Neutrons. +. +. +. Protons. Electrons (Electron Clouds). Radioactivity. Definition Any spontaneous change in the state of the nucleus accompanied by the release of energy.
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GEORGIA STATE UNIVERSITY
Radioactivity & Waste
Any spontaneous change in the state of the nucleus accompanied by the release of energy.
alpha () particle emission (decay)
beta () particle emission (-), positron emission (+) and orbital electron capture (ec)
gamma () decay including internal conversion
Definition - Any type of radiation possessing enough
energy to eject an electron from an atom,
thus producing an ion.
Major Types of Ionizing Radiation Alpha, Beta, Gamma
Large Mass (nuclei) – Helium
Atom with a +2 charge
Small Mass - Electron
238U 4He + 234Th
has a discrete energy that can be measured and related to the parent. The neutron to proton ratio is to low !
Ejected from Nucleus
Most of the energy
This is radioactive!!
3 products share energy – therefore beta has a continuous range of energies
Either too many neutrons or too many protons
Change a neutron into a proton
take away - charge
Change a proton into a neutron
take away + charge
Change proton into neutron
amount of charge produced anywhere in air by the complete stoppage of all electrons liberated by photons in an incremental volume of air per unit mass of air in that volume.
Standard International (SI) unit: Coulomb/kilogram (C/kg)
Traditional unit: roentgen ( R ) 1 R = 2.58x10-4 C/kg
Exposure definition applies only to photons of energy less than or equal to 3 MeV interacting in air.
is the energy deposited by any type of ionizing radiation in a volume element of mass.
SI unit: gray (Gy)
Traditional unit: rad 1Gy = 100 rad
Absorbed dose definition applies to all forms of ionizing radiation in any material.
Biological effect of 250 kVp x-rays at dose X
Both produce the same biological effect.
Relative Biological Effectiveness and Quality Factor
Relative Biological Effectiveness (RBE)
Quality factor (Q)
proton, neutron 10
Shoulder of curve indicates
cell repair at low doses
No shoulder - no cell repair
Same Biological Effect
Different Dose from 2 types of radiation
Dose equivalent: allows the description of the biological effect of an absorbed dose of a particular type of radiation or mixed radiations for the Human Body.
Dose Equivalent (DE) in Rem = Dose in Rads x Q
SI unit: sievert (Sv)
traditional unit: rem 1 Sv = 100 rem
For photons: 1 R 1 rad = 1 rem
AVOIDING UNNECESSARY RADIATION EXPOSURE
Definition: Exposure of the body from radiation originating outside of the body
Level 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)
We will discuss -
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)
Most low level wastes come from Government and Utilities. These consist of contaminated solids from nuclear reactor usage and weapon construction.Radioactive 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.
The true politics of Hazardous Waste
Did North Carolina, by not opening up a waste site, better protect it’s citizens?
Because there is currently no high level radioactive waste disposal facility, HLRW is held On-Site in water pools
Once these Pools are full, Waste is transferred to casks which are also held on-site
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
YOUR THOUGHTS AND DISCUSSION