- •Radioactivity, nuclear fuel cycle, radioactive wastes management
- •Radioactivity
- •Activity
- •Ionizing radiation
- •Izotope:
- •Absorbed dose
- •Equivalent dose
- •Effective dose
- •Nuclear fuel cycle
- •Methodology of minimal price
- •Economic model of given system (project) – main rules for creation
- •Basic principles of economic effectiveness of projects – methodology of npv
- •Radioactive waste – three main related economic task
Radioactivity, nuclear fuel cycle, radioactive wastes management
From history
1895: H. Becquerel - discovery of radiation
1896: W.C. Roentgen – X rays
1898: M. Curie-Sklodowska - discovery of radium (natural radioactivity)
1934: J. Curie – preparation of first artificial radioactive element
1942: E. Fermi – 1. controlled fission reaction
1954: Obninsk – 1. nuclear power plant
Radioactivity
Feature of atoms (of given elements) to decay to other elements
Activity
Amount of radioactive changes per time unit: 1 Becquerel (Bq)= 1 decay per second
Ionizing radiation
Released by radioactive elements
X rays
Cosmic rays
Half time:
Time period, one half of nuclei decay (from fraction of second up to bil. of years)
Izotope:
Element is defined by number of protons, might differ by number of neutrons
How to detect and measure radioactivity (ionising radiation)
We cannot use chemical procedures, but physical effects
Vaporous chamber
Geiger-muller
Photographs
Optical features of some matter
Changes in features of semiconductors
Thermoluminescence
Utilization of radioactive elements in practice
Neutron activation analysis (detection of unknown elements with very low concentration – 10-12 g/g
Marked compounds – monitoring of chemical reactions, technological processes (e.g. blending), observation of metabolism
radiopharmaceuticals – direct irradiation of cancer tumours
spas
sterilization and disinfection (e.g. old wooden objects)
leak tests
test of material quality
material modification – e.g. colour of glass, polymers production
fire alarms, and many other
Radioactivity and ionising radiation – health and other effects
Absorbed dose
absorbed energy per unit weight in J/kg (1 Gray = 1J/kg), DT,R
effect differ with intensity and type of radiation
Equivalent dose
respects “quality” of radiation – radiation weighting factor wR
photons, all energies incl. gamma and X rays: 1
electrons, all energies: 1
neutrons: <10 keV 5
<100 keV 10
<2 MeV 20
<20 MeV 5
protons: 5
alpha particles, fission fragments, heavy nuclei 20
Effective dose
respects type of organ affected, wT
gonads 0.2
bone marrow 0.12
lung 0.12
…
skin 0.01
bone surface 0.01
Collective dose
exposure of group of people or population (average dose times number of individuals affected)
Sources of radiation
cosmic rays (magnetic field of Earth, absorption in atmosphere),
radioactive background of Earth, differs according to location, typically 1-5 mSv
nuclear test
artificial sources (e.g. X ray apparatus, irradiation during cancer therapy, etc.)
Nuclear fuel cycle
Uranium mining
Classical way
Chemical way with use of sulphur acid – possible long term impact on underground water – Czech case
Chemical processing – “yellow cake” preparation (concentration)
Uranium enrichment (natural uranium consist of only 0.3% of U235 izotope)
Conversion into gas UF6, physical methods (slight differences in specific weight, or speed of diffusion)
Conversion into U3O8
Fabrication of fuel cells
Nuclear power plant – e.g. 2x1000 MW, 30 years, 1826 tonnes of spent fuel
Temporary storage (app. 40-50 years)
Final disposal