Transcript Application of nuclear and subnuclear physics

Application of nuclear and subnuclear physics
Energetic application
1) Radionuclide sources
2) Classical nuclear reactors
3) Fast (breeder) reactors
4) Accelerator driven transmutors?
5) Thermonuclear reactors?
Medical application
1) Diagnostics – using of signed atom method
2) Positron emission tomography
3) Radiation therapy
4) Irradiation using particles or nuclei
Nuclear power station Darlington
Industrial application and application in other science disciplines
1) Activation analysis
2) Surface studies
3) Implantation atoms
4) Radioactive dating
5) Conservation by irradiation
Radiation safety
1) Natural and artificial radiation sources
2) Radioactive waste handling
Radiation department of
clinic at Heidelberg
Radionuclide sources
Principle: Decay of radioactive nuclei  heat is produced (for
example isotopes with suitable decay times 90Sr – 28.8 y,
137Cs – 30.1 y, 210Po – 0.38 y and 238Pu – 87.7 y)
Thermoelectric cell transforms heat to electricity
( Sebeck phenomena - U  T, efficiency 5 – 10%)
Pioneer 10
Advantages:
Independent on sun light – possibility to use in every place
Long and stable function also in hard conditions of
vacuum and strong electric and magnetic fields
Simplicity  reliability
Disadvantage:
Possibility of ecology danger during probe accident
Casini probe working near Saturn is supplied
by radionuclide sources
Radionuclide cells of Nimbus
B-1 probe on see ground after
accident of booster rocket
(1968)
Probe accidents (without danger):
up to year 1964 – construction ensure of
source burning down at atmosphere
after year 1964 – construction ensure of source
impact in compact form (PuO2 – ceramic
material, graphite and iridium cover) Nimbus
B-1, SNAP-27 Apollo 13, Mars 8 (1996)
Used by outer planet probes, landing modules
working long time without sun light
Launch of Ulysses probe from space shuttle deck
Installation of SNAP-27
Classical nuclear reactors
Fission reactions – nuclear fission spontaneous or after energy obtaining
- usually energy of neutron capture is delivered
- accompanied by production of neutrons with energy in MeV range
( 2 - 3 neutrons per fission)
Fission chain reaction:
Fission of 235U and 239Pu nuclides
by neutron capture
235U:
85 % - fission
15 % - photon emission
Nuclear power station Indian point (USA)
Very high values of cross sections of small neutron energies (10-2 eV)
Necessity of neutron moderation - moderator
Fission – creation of fission products
production
Capture  photon emission  beta decay – transuranium
Delayed neutrons – emitted by fission products (neutron excess) - mean lifetime 8.8 s
Multiplication factor k – number of neutrons of future generation produced per one neutron of
present generation
k < 1 subcritical system
k = 1 critical system
k > 1 supercritical system
Nuclear reactor
Reactor inside during fuel exchange
Power station Diablo Canyon USA
Reactor regulation:
Compensation rods - worsening of neutron balance during operation is compensated by their
gradual removal
Control rods – regulation of immediate changes of output
Safety shut-down rods - fast reactor stopping
Fuel: 1) natural uranium – consisted of 238U and only 0.72 % of 235U
2) enriched uranium – increasing of 235U content on 3-4% (clas.reactor)
mostly in the form of UO2
Important is heat removal (water)
Year 2006 (MAAE source):
435 energetic reactors, power 370 GWe → production of 16 % of electricity
total operating experience: > 10 000 reactoryears
Fast (breeder) reactors
Nonmoderated neutrons → necessity of high enrichment of uranium
20 - 50 % of 235U (or 239Pu)
Production of 239Pu: 238U + n → 239U(β-) + γ → 239Ne (β-)→239Pu
More neutrons from 239Pu (3 per one fission) → production of more plutonium than is burned up
(breeding zone)
High enrichment → high heat production → necessity of powerful cooling → molten natrium
(temperature of 550 oC)
Lifetime of fast neutron generation is very short → bigger role of delayed neutrons during regulation
Fast breeder reactor at Monju
(Japan) - 280 MWe
Power stations Phenix - 250 MWe
and
Superphenix 1200 MWe
(France)
Accelerator driven nuclear transmutor
It consists of:
1) Proton accelerator - energies in the range 100 - 1000 MeV
2) Target - lead, tungsten …
3) Vessel containing system of nuclear waste, moderator
Necessity of separation of stable and shortlived isotopes
Basic properties:
1) Usage of spallation reactions
2) Very high neutron density → effective transmutation
3) Subcritical behavior
4) Production of neutrons with very wide energy range
Conception scheme of accelerator
driven nuclear transmutor
Concrete proposition of nuclear transmutor
Proton accelerator: E = 100 MeV - 2 GeV
I = 20 - 100 mA
Problems: necessity of stable trouble-free operation during very long time.
Target: tungsten? liquid lead? uranium and transuranium?
Neutron density: ~1020 m-2s-1 (reactor ~1017 - 1018 m-2s-1)
Problems: removal of great amount of heat
Subcritical blanket:
Problems: necessity of continuous separation, efficient transport and neutron moderation
Scheme of concrete accelerator
driven transmutation system:
Energy production as at classical
nuclear power station, its part supplies
accelerator
Thermonuclear reactors?
Fusion of light nuclei  energy production
Practical use: 2H + 3H  4He + n + 17.58 MeV
High temperature (107 - 109 K) nuclear reactions  thermonuclear reactions
Lawson criterion – necessary condition for production of more thermonuclear energy than it is
consumed for fuel heating:
For DT reaction:
τρ ≥ 3∙1020 s∙m-3 Temperature 108 - 109 K
τ – time of hot plasma maintenance, ρ – density of plasma nuclei
Experimental "thermonuclear reactors" of Tokamak type:
Ring chamber - ring magnetic field
(chamber height 2 - 4 m, B = 2 - 5 T, currents 2∙106 A):
Important - high vacuum and strong magnetic field  plasma maintenance
TFTR (Tokamak
Fusion Test Reactor),
Princeton (USA):
TFTR at Princeton worked
between years 1987 -97,
maximal power was 10 MW,
general view and inside view
on ring
JET (Joint European Torus), Culham near Oxford, Great Britain
Up to 16 MW in pulls and 4 MW during 5 s, 65% usage of delivered energy
Experimental device JET at Culhamu (height 12 m, diameter 15 m)
JT-60 (JAERI Tokamak 60), Naka, Japan
ITER - international thermonuclear
experimental reactor:
Neutron and gamma ray shielding, created
helium off take
Lithium envelope – tritium production:
6Li(n,)3H 7Li(n,n)3H
Precursor of JT-60 device was JTF-2M device
Goal: Building of future thermonuclear reactor prototype
Diagnostics – usage of labeled atom method
Stable isotopes in compounds should be changed by radioactive ones:
( 197Au  198Au, 12C  11C, 127I  123I)
Advantage is very short lifetime → radioactivity quickly vanishes
1) Investigation of function and states of different organs and tissues
2) Localization of malignancies
Radiopharmaceutics – labeled compounds at medicine – wide assortment of compounds for
different organs investigation is very important
Preparation of radiopharmaceutics, lead glass protection
(company Radiopharmacy, Inc. – Indiana, USA)
Examples of other used radionuclides:
Record of radioactivity distribution in
investigated organs - scintigrams
32P, 57Co, 58Co, 51Cr, 18F, 67Ga, 75Se, 89Sr, 99mTc,
111In, 133Xe, 153Sm, 197Hg, 201Th, 203Hg
Detection of radiation by system of gamma detectors (NaI(Tl) is mainly used) ↔ organ scintigrams
Metabolism of different elements and compounds is studied
Labeled compounds are used in many further fields: ecology, hydrology, chemistry, biology,
and industry
Positron emission tomography
Radioactive isotopes with positron decay → positron annihilation in rest → creation of two photons
(gamma ray quanta) flying in opposite directions → their detection and annihilation position
determination
Used radioisotopes: 11C, 13N, 15O, 18F
Insertion of radioactive isotope to compound subsides at studied organ (accurate diagnostics and
medical research):
1) Determination of position and sizes of cancer tumor
2) Efficiency of irradiation using heavy ions (10C, 11C)
3) Identification well and bad perfused parts
4) Identification of intensively working brain parts
Heart damaged by heart attack
Healthy heart
Very good spatial resolution ( 2 mm ), still new chemical compounds for PET chambers (systems of
Positron Emission Tomography)
Typical PET chamber and
commercial cyclotron IBA cyklone 10/3
Radiation therapy
Cancer cells are more sensitive to radiation → radiation is used for destruction of cancer cells and
elimination of tumors
External radiation therapy:
Irradiation by external radiation source – mostly X or gamma rays - cobalt or cesium emitters use
60Co and 137Cs
Internal radiation therapy:
1) Small capsule with emitter (for example iridium
thin wires for treatment of skin cancer) is
transported to proximity of tumor inside body
2) Radioactive compound is injected inside body
and it is concentrated in organ affected by
tumor
Boron neutron capture therapy
Cobalt emitter of Faculty Hospital at Ostrava
Compound containing 10B is injected to body → it is cumulated in cancer cells, healthy cells
do not drop boron inside → irradiation by thermal and epithermal neutrons from reactor
→ energy from reaction 10B(n,α)7Li destroys cancer cells
Heavy ion irradiation
Usage of ionization energy losses dependency on charged particle velocity.
Larger charge (heavier ion) → larger part of energy is
deposited on the end of trajectory
Possibility to place destructive energy to tumor without
damages of neighboring tissue
Heavy ion accelerator
Test system uses accelerator SIS at GSI
Darmstadt (100 MeV - 1 GeV)
Part of heavy ion accelerator SIS at GSI Darmstadt
Possibility of accurate setting of position (given by beam direction) and depth (ion energy)
Three-dimensional irradiation:
1) Models in water
2) Plan of irradiation and result is controlled by positron emission tomography (PET)
(radioactive ions are accelerated – positron emitter)
Suitable for brain tumor or spine tumor (incoparable smaller damage of neighboring tissue than for
surgical operation).
Higher sensitivity of cancer cells against radiation damage
Some dozens of patients were successfully irradiated at GSI from 1997 year
Model of specially projected device for hospital at Heidelberg
Radiation table at GSI Darmstadt
(perfect fixation of patient is important)
Activation analysis
X-ray-fluorescence activation analysis – irradiation by X-ray or gamma ray source → photoeffect
→ characteristic X-rays
Neutron activation analysis – sample is irradiated by known neutron flux with known energy
spectrum mostly from reactor. Radionuclides are created during irradiation → characteristic gamma
lines → their intensities are given by amount of original isotope
Advantages: 1) Very small sample is necessary
2) Very small element contents should be determined (10-12 g of element in 1g of sample)
3) Sample is not damaged – very advantageous for archeology
Wide use in ecology, biology, archeology, historiography, geology, astrophysics …
Particle flux can be determined using known material of used foils by activation analysis
(determination of neutron flux in reactor or accelerator proton flux)
Semiconductor HPGe detectors are mainly used for gamma ray measurements (example of detector at JINR
Dubna and obtained spectra)
Surface studies
Studies of composition and structure of surface layers
A) Using of neutrons (mainly from reactor):
Neutron scattering - neutron diffraction (diffraction and interferometry):
Difractometer SPN-100
NPI ASCR
Neutron interferometer
B) Using of accelerated light ion – nuclear analytical methods:
1) Rutheford backscattering (RBS):
2) X-ray emission induced by particles (PIXE)
3) Gamma ray emission induced by particles
(PIGE)
Radiation defectoscopy:
Mostly using gamma rays but also neutrons or
charged particles (many imaging methods)
Example of RBS method use for study of surface with
lubricated layer of aluminum oxide (NPI of ASCR)
Ion implantation
Use of ions accelerated on energies within the keV – MeV range implanted to materials
Modification of surface properties of different materials (metals, semiconductors)
Use mainly but not only at electronic industry – production of microchips and others
semiconductor components
Industry: surface modification – harder materials resisting against corrosion.
Crystal modification – change of atoms
Enrichment of surface by impurity
in the amount of only single atoms
Nuclear filters – ionizing traces
after passage of ionizing particle
through material → chemical
etching → very small holes → very
fine filters
Implantator TECVAC 221
Radioactive dating
Use of different radioactive nucleus decay time. We study ratio between stable and radioactive
isotopes, mother and daughter nuclei.
Archeology:
radioactive carbon 14C (T1/2 = 5730 years) produced by cosmic ray interaction at atmosphere,
organism absorbed it by breathing – death → isotope 14C is decaying. The ratio 14C/13C/12C
determines age of remnants.
Problem – background, small activities, change of production of 14C and 12C (burning of fossil
carbon and nuclear tests)
Range: 20 000 – 25 000 years
! only for organic materials !
Wider range thanks accelerator mass spectroscopy ~50000 years
Mass spectrometer for 14C dating on University at Aarhus (Sweden)
Geology and cosmogony:
Measurement of exposing time of meteorites:
39Ar
26Al
10Be
53Mn
Isotope
T1/2 [year] 269 7,4·105 1,51·106 3,74·106
Accelerator mass
spectrometer
Morávka meteorit
Potassium-argon method 40K (T1/2 = 1.28 billion years). After freezing, created 40Ar can not escape
→ age can be determined. Dating of rocks, minerals and objects created from melted material.
Cosmology:
Very long-life isotopes, ratio between radioactive and stable – creation
time of elements in different space regions – use of spectroscopy
Conservation by irradiation
Conservation of historical artifacts:
Use of biological effects of ionizing radiation on insect and microorganisms.
Mostly gamma rays are used, mainly 60Co source
Radiation preservative workplace at Central Bohemia museum at Roztoky
Food conservation:
Genesis – emitter for food
conservation Gray Star Company,
uses 60Co radioactive source
Elimination of danger pathogens – more healthy and durable food store
Sterilization of medical material:
Surgical and other medical material, implantats (joint substitutes …). Changes of some
polymer features are used
Advantages:
1) High efficiency
2) It does not damage and change features of conserved material
3) It can change features of some polymers positively
4) It does not leave harmful or toxic remains
Natural and artificial radiation sources
Quantities describing ionizing radiation and its biological effect:
Activity A [Bq = s-1] – number of decays
Imparted energy:
Rate [Bq = s-1] – number of detected particles
Dose D [Gy = Jkg-1] - total energy imparted to tissue or organ
Dose rate [Gy s-1]
Radiation biological effect depends on type of tissue and radiation:
Dose equivalent H = QD [Sv] ,
Q - quality factor - relative biological effect of given radiation on tissue
Equivalent dose HT = wRDT [Sv] DT – dose absorbed by tissue
Radiation weighting factor wR quality factor estimating biological risk of radiation
Every organ or tissue are differently sensitive:
Type of radiation
Photons and electrons of all energies
Effective dose – sum of equivalent doses
weighted with the respect to radiation sensitivity
Neutrons with energy 10 keV
of organs and tissues of whole human body
Neutrons with energy 10 - 100 keV
Biological effects of ionizing radiation:
Neutrons with energy 0,1 - 2 MeV
Non-stochastic – are threshold, dose is
Neutrons with energy 2 - 20 MeV
sufficient to create observable damage during
α rays
relatively short time
Stochastic effects - dose does not create observable damage during short time but it is some
probability of its later appearance
wR
1
5
10
20
10
20
Radiation sources to which population is exposed:
Radiation source
Ĥ [μSv year-1]
Fraction [%]
Cosmic rays
380
12,5
Natural radionuclide
702
22,9
Radon and its transformation products
1300
43,1
Mining industry
24
0,75
Nuclear power supply
8
0,2
Radionuclide production
0,8
0,02
Medical application
660
20,6
Ĥ - annual average equivalent dose
External irradiation – external radioactivity sources
Internal irradiation – radionuclides inside body
Radiotoxicity – degree of radionuclide harmful
effects:
Five classes of radionuclide recklessness – the
most danger is first:
(60Co, 134Cs, 137Cs, 210Pb, 226Ra, 239Pu, 241Am)
Basic limits: ordinary man
1 mSv/year
worker with radiation 50 mSv/year
20.6%
Cosmic Rays
12.5%
Natural radionuclides
0.0%
Radon
0.2%
Mining
0.7%
22.9%
Nuclear Power
Radionuclide production
Medical Aplication
43.1%
Nuclear waste – spent fuel
Composition: 96 % uranium (~1% 235U)
1 % transuranium
3 % fission products (stable, short-live, long-live)
Some long-life radioactive fission products: 99Tc (2.1105 years), 129I (1.57107 years), 135Cs
(2.3106 years)
Long-life transurans: 237Np (2.3106 years), 239Pu (2.3106 years), 240Pu (6.6103 years),
244Pu (7.6107 years), 243Am (7.95103 years)
Tests of spent fuel (Monju)
Reactor inside and fuel exchange in one from USA reactor
Year production of nuclear waste at France (75% energy):
High activity (1000 Mbq/g) :
100 m3 Mean activity (1 Mbq/g)
: 10000 m3
Temporary reposition – heat removal is very important during starting stage (water tank)
Reprocessing of spent fuel
Processing and imposition of nuclear waste
Modification and processing
of nuclear waste:
a) Cementation - mixing with cement mixture
b) Bitumenation - mixing with molten asphalt bitumen
c) Vitrification - mixing with molten glass
Manipulation with high activity waste
Different types of radioactive waste transport
Vitrification
Pictures mainly from Sweden
program of radioactive waste
handling