material structure elucidation methods -...

Ionising radiation inindustry

Anita Csordás

E-mail: [email protected]

Tel:+36-88/624-924

Material structure elucidation methods

2018/2019. 1. semester

University of Pannonia

Institute of Radiochemistry and Radioecology

• Radioactive isotopes (chemical materials)

• Usually gamma-emitter (Co-60, Ir-192, Cs-137)

• Sometimes beta or neutron emitters (in special cases)

• Radiation is prepared by electrical equipment – radiationgenerators

• No chemical materials

• For example: X-ray equipment

Radiation sources

Pannon Egyetem, Radiokémiai és Radioökológiai Intézet, Veszprém

Types of the radioactive isotope source


SEALED Many radioactive sources are sealed,meaning they are permanently eithercompletely contained in a capsule orfirmly bonded solid to a surface. Theuse of sealed sources removesalmost all risk of dispersion ofradioactive material into theenvironment due to mishandling, butthe container is not intended toattenuate radiation, so furthershielding is required for radiationprotection.

UNSEALEDUnsealed sources are sources that arenot in a permanently sealedcontainer, and are used extensively formedical purposes. They are used whenthe source needs to be dissolved in aliquid for injection into a patient oringestion by the patient. Unsealedsources are also used in industry in asimilar manner for leak detection as aRadioactive tracer. During theapplication the radioactive materialcan go to the body (external exposure)

• Reactor

• Research reactor (KFKI, Budapest) –mainly industrial application

• Research reactor (BME, Budapest) – forresearch and education

• Accelerator

• Debrecen (cyclotron) – medicalapplication

• Portable neutron source with isotopes

Tools of the isotope production


9Be(α,n)12C10B(α,n)13N11B(α,n)14N

Neutrons

Alpha-source Berilium

• Physical and chemical form of the required isotope

• Determination of the irradiation’s parameters (time, typeof radiation, etc.)

• Irradiation – nuclear reactions

• Removal of the pollutants (decay or chemical separationprocess)

• Cleaning process, concentration measurements

Preparation of unsealed source


• The same process like in case of the unsealed source + 1 more step

• Source encapsulation and welding

• Used material: steel

Preparation of sealed source


• 1895. Wilhelm Conrad Röntgen

• 1901. first Nobel prize in Physics

X-ray


X-ray tube


The heart of an X-ray machine

is an electrode pair -- a

cathode and an anode -- that

sits inside a glass vacuum

tube. The cathode is a heated

filament, like you might find in

an older fluorescent lamp. The

machine passes current

through the filament, heating it

up. The heat sputters electrons

off of the filament surface. The

positively-charged anode, a flat

disc made of tungsten, draws

the electrons across the tube.

The voltage difference between the cathode and anode is extremely

high, so the electrons fly through the tube with a great deal of force.

When a speeding electron collides with a tungsten atom, it knocks loose

an electron in one of the atom's lower orbitals. An electron in a higher

orbital immediately falls to the lower energy level, releasing its extra

energy in the form of a photon. It's a big drop, so the photon has a high

energy level -- it is an X-ray photon.

https://science.howstuffworks.com/fluorescent-lamp.htm

Isotopes vs. X-ray machine


ISOTOPES

• Smaller size, easier transport

• Independent on the elecricalsystem (field measurements)

• Places, which difficult toaccess

• Higher penetrating (because of the higher energy)

• Panorama images

X-RAY MACHINE

• Intensity of radiation does notchange in time (no half-life)

• Shorter exposure time

• It can be switched off(radiation protection)

• Controlled energy level

1. Radioactive label or radioactive tracer

2. Nuclear industrial equipment

3. Nuclear logging methods (geology)

4. Radiography és autoradiography

5. Irradiation processes

Application in industry


A radioactive tracer, or radioactive label, is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products.

1. Radioactive tracer


Hevesy György(1885-1966)

• Isotopes of a chemical element differ only in the mass number. For example, the isotopes of hydrogen can be written as 1H, 2H and 3H, with the mass number at top left. When the atomic nucleus of an isotope is unstable, compounds containing this isotope are radioactive. Tritium is an example of a radioactive isotope.

• The principle behind the use of radioactive tracers is that an atom in a chemical compound is replaced by another atom, of the same chemical element. The substituting atom, however, is a radioactive isotope. This process is often called radioactive labeling. The power of the technique is due to the fact that radioactive decay is much more energetic than chemical reactions. Therefore, the radioactive isotope can be present in low concentration and its presence detected by sensitive radiation detectors such as Geiger counters and scintillation counters.

Methodology


https://en.wikipedia.org/wiki/Isotope

https://en.wikipedia.org/wiki/Chemical_element

https://en.wikipedia.org/wiki/Hydrogen

https://en.wikipedia.org/wiki/Hydrogen

https://en.wikipedia.org/wiki/Deuterium

https://en.wikipedia.org/wiki/Tritium

https://en.wikipedia.org/wiki/Atomic_nucleus

https://en.wikipedia.org/wiki/Radioactive

https://en.wikipedia.org/wiki/Tritium

https://en.wikipedia.org/wiki/Atom

https://en.wikipedia.org/wiki/Chemical_compound

https://en.wikipedia.org/wiki/Radiation_detector

https://en.wikipedia.org/wiki/Geiger_counter

https://en.wikipedia.org/wiki/Scintillation_counter

There are two main ways in which radioactive tracers are used

• When a labeled chemical compound undergoes chemical reactions one or more of the products will contain the radioactive label. Analysis of what happens to the radioactive isotope provides detailed information on the mechanism of the chemical reaction.

• A radioactive compound is introduced into a living organism and the radio-isotope provides a means to construct an image showing the way in which that compound and its reaction products are distributed around the organism.


Example for the applications



Tracing underground leaks in pipes

A radioactive tracer can be added to a fluid.Where a leak occurs will be shown by an increase in thecount rate detected.

• Determination of the time-intensity function

• Advantages:

• Small concentration– huge sensitivity

• No disturbing instruments in the flow

• Fast and quickly reproducible

• Disadvantage:

• Radiation protection (workers, environment)Pannon Egyetem, Radiokémiai és Radioökológiai Intézet, Veszprém

Measurement of flow rate

• Waters and aqueous solutions

• Na-24 (T= 14,9 hours)

• Br-82 (T=1,5 days)

• Organic materials (oils)

• Cu-64 (T=12,8 hours)

• Ba-140 (T=12,8 days)

Examples for the using isotopes


Isotope dilution analysis is a method of determining the quantity of chemical substances. In its most simple conception, the method of isotope dilution comprises the addition of known amounts of isotopically-enriched substance to the analyzed sample. Mixing of the isotopic standard with the sample effectively "dilutes" the isotopic enrichment of the standard and this forms the basis for the isotope dilution method.


• In the most cases sealed sources (perhaps X-ray machine)

• Investigation without damage of the sample

• Advantages

• Contact is not necessary (between the source and sample)

• Change of the radiation’s intensity is independent on theenvironmental parameters (pressure, temperature)

• Fast results

• Investigation of moving and not moving medium

• Disadvantages

• Radiation protection

• Legislation

• High investmen cost

2. Nuclear industrial equipment



Measurement and control of the liquidlevel

• Nuclear type devices work on the principle thatprocess material absorbs (attenuates) radiation.

• On the outside of the one wall of the vessel, an installed nuclear source emits radiation. A nucleardetector is installed on the outside of the oppositevessel wall.

• As the radiation beams from source to detector, theprocess material absorbs some of the gamma-rays.

• The amount of the absorption is based upon theprocess material’s density and the current processmaterial volume within the vessel.

• As the liquid level rises, the liquid absorbs more of theradiation than the gas or air above the liquid and thedetected intensity decreases.

Because the amount of radiation absorbed by a material is proportional to its thickness, radiation can be used to control the thickness of plastic film, tin foil, or paper. As shown, a beta emitter is placed on one side of the material being produced and a detector on the other. An increase in the amount of radiation that reaches the detector indicates a decrease in the thickness of the material and vice versa. The output of the detector can thus be used to control the thickness of the material.


Measurement and control of thethickness

Moisture measurement


A neutron moisture meter is a moisture meter utilizing neutron scattering. The meters are most frequently used to measure the water content in soil or rock. The technique is non-destructive, and is sensitive to moisture in the bulk of the target material, not just at the surface.

Water, due to its hydrogen content, is an effective neutron moderator, slowing high-energy neutrons. With a source of high-energy neutrons and a detector sensitive to low-energy neutrons (thermal neutrons), the detection rate will be governed by the water content of the soil between the source and the detector. The neutron source typically contains a small amount of a radionuclide. Sources may emit neutrons during spontaneous fission, as with californium; alternatively, an alpha emitter may be mixed with a light element for a nuclear reaction yielding excess neutrons, as with americium in a beryllium matrix.

https://en.wikipedia.org/wiki/Moisture_meter

https://en.wikipedia.org/wiki/Neutron_scattering

https://en.wikipedia.org/wiki/Neutron_moderator

https://en.wikipedia.org/wiki/Thermal_neutron

https://en.wikipedia.org/wiki/Neutron_source

https://en.wikipedia.org/wiki/Radionuclide

https://en.wikipedia.org/wiki/Spontaneous_fission

https://en.wikipedia.org/wiki/Californium

https://en.wikipedia.org/wiki/Alpha_emitter

https://en.wikipedia.org/wiki/Americium

https://en.wikipedia.org/wiki/Beryllium

• Gamma ray logs

• Spectral gamma ray logs

• Density logging

• Neutron logs

• Neutron porosity logs

• Pulsed-neutron-lifetime (PNL) logs

3. Nuclear logging methods


Spectral gamma ray logs


• Measurement of the natural radionuclides (Ra-226, K-40, Th-232, etc.)

• Identification of the soil component (rock type)

Density logging


A density-logging tool sends gamma rays into a formation and detects those that are scattered back. Typical logging sonde use a Cesium-137 source.

Neutron porosity logs


It consisted of an isotopic source, most often plutonium-beryllium, and a single detector. Many variations were produced exploiting both thermal and epithermal neutrons. In most of the early tools, neutrons were not detected directly. Instead, the tools counted gamma rays emitted when hydrogen and chlorine capture thermal neutrons. Because hydrogen has by far the greatest effect on neutron transport, the borehole effects on such a tool are large.

• Non-destructive testing

• No damage on the sample

• Selection of the wrong product

• Saving materials

• To reduce the processing cots

• In the most cases X-ray or gamma-ray

• Aim: to investigate the internal structure of the material –in most cases to find the material defects

4. Radiography és autoradiography


Potential material defects


Principle of radiography


Radiography is an imaging technique using X-rays, gamma rays, or similar radiation[1] to view the internal form of an object. To create the image, a beam of X-rays or other form of electromagnetic radiation is produced by an X-ray generator and is projected toward the object. A certain amount of the X-rays or other radiation is absorbed by the object, dependent on the object's density and structural composition. The X-rays that pass through the object are captured behind the object by a detector (either photographic film or a digital detector).

https://en.wikipedia.org/wiki/Imaging_technology

https://en.wikipedia.org/wiki/X-ray

https://en.wikipedia.org/wiki/Gamma_ray

https://en.wikipedia.org/wiki/Radiography#cite_note-1

https://en.wikipedia.org/wiki/Electromagnetic_radiation

https://en.wikipedia.org/wiki/X-ray_generator

https://en.wikipedia.org/wiki/X-ray_detector

https://en.wikipedia.org/wiki/Photographic_film

• Radioactive isotopes in the investigated samples

• The sample and the film (sensitive to the radiation) incontact

• In most cases beta or alpha emitters

• Applications:

• To find the corrosion places

• Investigation about the catalyst process

Autoradiography


• Irradiation is the process by which an object is exposed to radiation. The radiation causes changes in the internalstructure of the materials, therefore some properties ofthe material change (temporarily or finally)

• Changes:

• Physical (crystal structure)

• Chemical (polymerization)

• Biological (sterilization)

5. Irradiation processes


• New, better, unique features products

• Smaller chemical need

• Smaller contamination – environmental protection

• Energy saving

• Economical technology

Advantages


• Radiation protection (workers and environment)

• Huge investment cost

• Fear of radiation

Disadvantages


Some examples for theirradiation with physical

changes


Gemstone irradiation


Changes in the crystalstructure

Glass irradiation


Color depends on the absorbed energy

Radioluminescence is the phenomenon by which light is produced in a material by bombardment with ionizing radiation such as alpha particles, beta particles, or gamma rays. Radioluminescence is used as a low level light source for night illumination of instruments or signage or other applications where light must be produced for long periods without external energy sources. Radioluminescent paint used to be used for clock hands and instrument dials, enabling them to be read in the dark.

Light source


https://en.wikipedia.org/wiki/Luminescence

https://en.wikipedia.org/wiki/Ionizing_radiation

https://en.wikipedia.org/wiki/Alpha_particle

https://en.wikipedia.org/wiki/Beta_particle

https://en.wikipedia.org/wiki/Gamma_ray

• A radioisotope thermoelectric generator (RTG, RITEG) is an electrical generator that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity.

• RTGs have been used as power sources in satellites, space probes, and unmanned remote facilities such as a series of lighthouses built by the former Soviet Unioninside the Arctic Circle.

Radioisotope thermoelectric generator


small "plutonium cells" (very small 238Pu-powered RTGs) were used in implanted heart

pacemakers to ensure a very long "battery life".

https://en.wikipedia.org/wiki/Electrical_generator

https://en.wikipedia.org/wiki/Thermocouple

https://en.wikipedia.org/wiki/Decay_heat

https://en.wikipedia.org/wiki/Radioactivity

https://en.wikipedia.org/wiki/Electricity

https://en.wikipedia.org/wiki/Satellite

https://en.wikipedia.org/wiki/Space_probe

https://en.wikipedia.org/wiki/Lighthouses

https://en.wikipedia.org/wiki/Soviet_Union

https://en.wikipedia.org/wiki/Arctic_Circle

https://en.wikipedia.org/wiki/Artificial_pacemaker

Some examples for theirradiation with chemical

changes


Gamma-ray induced polimerization

Polymerization


Irradiation of the polymers:Degradation


Long polymer cutting– shorter polymer = other properties

Process of forming bonds (crosslinks) between macromolecules’ chains, which

leads to three-dimentional polymernetwork

Irradiation of the polymers:Crosslinking


Food irradiation (biologicalchanges)


• Aim: preserving in natural state

• The easiest way: heat treatment – but: physical and chemical changes – savour changes

• Irradiation – no temperature increasing – no changes – notoxic components

Food irradiation


• No added chemicals

• No temperature increasing

• No physical and chemical changes

• It is used in case of thermosensitive materials or frozenproducts

• Independent on the package (hermetically sealed or bulk)

• Low amount of energy is necessary

Advantages of irradiation


• In some cases the savour or aroma can change

• Radiation protection

• Upper limit in the radiation’s energy (to avoid the nuclearreaction)

Disadvantages of irradiation


• Radiation source (Radioactive isotope or accelerator)

• Biological protection

• Source

• Irradiation place

• Product delivery system

• Security system

• Auxiliary equipment (ventillation system, etc.)

Elements of the irradiation system


• The Codex Alimentarius represents the global standard for irradiation of food, in particular under the WTO-agreement.

• International Consultative Group on FoodIrradiation

• USA: current

• EU – permission for the spices

Regulation


The Radura symbol, as required by U.S.

Food and Drug Administration

regulations to show a food has been

treated with ionizing radiation.


Application Dose (kGy)

Low dose (up to 1 kGy)

Inhibit sprouting (potatoes, onions, yams, garlic) 0.06 - 0.2

Delay in ripening (strawberries, potatoes) 0.5 - 1.0

Prevent insect infestation (grains, cereals, coffee beans, spices, dried nuts, dried fruits, dried fish, mangoes, papayas)

0.15 - 1.0

Parasite control and inactivation (tape worm, trichina) 0.3 - 1.0

Medium dose (1 kGy to 10 kGy)

Extend shelf-life (raw and fresh fish, seafood, fresh produce, refrigerated and frozen meat products)

1.0 - 7.0

Reduce risk of pathogenic and spoilage microbes (meat, seafood, spices, and poultry)

1.0 - 7.0

Increased juice yield, reduction in cooking time of dried vegetables

3.0 - 7.0

High dose (above 10 kGy)

Enzymes (dehydrated) 10.0

Sterilization of spices, dry vegetable seasonings 30.0 max

Sterilization of packaging material 10.0 - 25.0

Sterilization of foods (NASA and hospitals) 44.0

https://en.wikipedia.org/wiki/NASA

• AGROSTER Besugárzó Rt. (Budapest)

• 500 t/year

• Food: spices, herbs

• Other products: medical devices

• Dispomedicor Zrt. (Debrecen)

• Medical devices

In Hungary


material structure elucidation methods -...

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