Laser induced separation Laser induced separation

of isotopesof isotopes

atomic structureatomic structure

•Atoms are made up of three main particles.

These are the neutron, electron, and proton.

These main parts are each made up of smaller

particles. The last picture shows the placement

of each of the main particles .

•What are?•Isotopes, Isobars , Isotones and

isomers

IsotopesIsotopes

•These are the elements having same atomic

number but different mass number. They

have the same atomic number because the

number of protons inside their nuclei

remains the same. The difference in their

mass number is due to the difference in

their number of neutrons

Examples Examples •Hydrogen Isotopes:

•Hydrogen) 1H1 (

Tritium 1H3- Deuterium) 1H2(

ISOMERSISOMERS

•molecular are compounds with the same

. structural formulasbut different formula

Isomers do not necessarily share similar

properties, unless they also have the

. There are many functional groupssame

different classes of isomers, like

stereoisomers, enantiomers, geometrical

isomers, etc

IsobarsIsobars

•Isotopes are chemically same and physically

different. But the converse is true in isobars.

That is isobars are elements, which are

chemically different but physically same. So,

isobars are atoms of different elements having

the same atomic mass but different atomic

number. Since their number of electrons is

different, their chemical properties are

different.

Examples of isobarsExamples of isobars

•Since isobars are different elements they

appear in different places in the periodic

table.

IsotonesIsotones

•Isotones are elements having the same number

of neutrons.

•Examples of isotones are :-

•Chlorine - 37 and Potassium - 39.

•Both have 20 neutrons in their nuclei.

Isotopes Separation

•Is purification specific isotope by removing

unwanted impurities .

•Most separation techniques rely on the

difference of masses of the isotope species

involved .

Deuterium has twice the mass as hydrogen and

is generally easier to purify than uranium 235

and uranium 238 .

Importance of isotopes separationImportance of isotopes separation

•scientific researches-1

•Radiochemical

•Using radioactive materials for analytical measurement purposes and radiometric .

•Radioisotopic

•Use of radionuclides to study biological , chemical , geological and physical processes in the environment .

•Medicine-2

•Nuclear Energy-3

•Nuclear Weapons-4

•

Practical methods of Practical methods of isotopesisotopes

separationseparation

•Diffusion

•Often done with gases, but also with liquids, the method relies on the fact that in thermal diffusion

equilibrium, two isotopes with the same energy will have different average velocities. The lighter atoms (or the molecules containing them) will travel more quickly and be more likely to diffuse through a membrane. The difference in speeds is proportional to the square root of the mass ratio, so the amount of separation is small and many cascaded stages are needed to obtain high purity. This method is expensive due to the work needed to push gas through a membrane and the many stages necessary.

Centrifugal effectCentrifugal effect

•. In modern times it is the main method used

throughout the world to enrich uranium and as

a result remains a fairly secretive process,

hindering a more widespread uptake of the

technology.

ElectromagneticElectromagnetic

•It uses the fact that charged particles are and the amount of magnetic fielddeflected in a

deflection depends upon the particle's mass. It is very expensive for the quantity produced, as it has an extremely low throughput, but it can allow very high purities to be achieved. This method is often used for processing small amounts of pure isotopes for research or

but is ), isotopic tracersspecific use (such as impractical for industrial use.

Chemical methodsChemical methods

•Techniques using this are most effective for

light atoms such as hydrogen. Lighter isotopes

more quickly than evaporatetend to react or

heavy isotopes, allowing them to be separated.

GravityGravity

•Isotopes of Carbon, Oxygen, and Nitrogen can

be purified by chilling these gases or

compounds nearly to their liquification

temperature in very tall columns (200 to 700

feet tall - 70 to 200 meters). The heavier

isotopes sink and the lighter isotopes rise,

where they are easily collected.

Laser isotope separation LISLaser isotope separation LIS

•Laser isotope separation is a general and

•powerful method in which a selected

•isotope is enriched or depleted, using

•remarkable properties of laser radiation.

How LIS WorksHow LIS Works

•Laser isotope separation (LIS) is based on the

fact that different isotopes of the same

element, while chemically identical, have

different electronic energies and therefore

absorb different colors of laser light. The

isotopes of most elements can be separated by

a laser-based process if they can be efficiently

vaporized as atoms.

LIS techniqueLIS technique

•In LIS enrichment, uranium metal is first vaporized in

a separator unit contained in a vacuum chamber. The

vapor stream is then illuminated with laser light tuned

precisely to a color at which 235U absorbs energy.

The generation of laser light starts with diode-

pumped, solid-state lasers providing short, high-

intensity pulses at high repetition rates. This green

light from the solid-state lasers travels via fiber-optic

cable to energize high-power dye lasers. The dye

laser absorbs green light and reemits it at a color that

can be tuned to the isotope of interest. In uranium

enrichment, the light converts to three wavelengths of

red-orange light, which is absorbed only by 235U

•Each color selectively adds enough energy to ionize or remove an electron from 235U atoms, leaving other isotopes unaffected. "The uranium atoms are subjected to a razor-sharp beam," notes Livermore physicist Steve Hargrove. "Given the several kilowatts of high average power of the dye laser beam, it's a significant achievement that the wavelengths are stable to better than 1 part in 10 million and that the beam's ability to travel long distances is nearly perfectly preserved

•Because the ionized 235U atoms are now

"tagged" with a positive charge, they are easily

collected on negatively charged surfaces inside

the separator unit. The product material is

condensed as liquid on these surfaces and then

flows to a caster where it solidifies as metal

nuggets. The unwanted isotopes, which are

unaffected by the laser beam, pass through the

product collector, condense on the tailings

collector, and are removed .