NUCLEAR CHEMISTRY“A DRIVING ENERGY SOURCE“

NUCLEAR?Even though the diameter of the nucleus is in the range of 1.75 fm (1.75×10−15 m) for hydrogen to about 15 fm for the heaviest atoms, such as uranium, it has a complex chemistry behind it.

NUCLEAR FUEL CYCLE

The chemistry associated with any part of the nuclear fuel cycle including nuclear reprocessing. The fuel cycle includes:

Mining

Ore Processing

Fuel Enrichment

‘In Pile’ Behavior(Use of fuel in reactor)

Back End

MINING

ORE PROCESSING

FUEL ENRICHMENT

‘IN PILE’ BEHAVIOUR

BACK END

NUCLEAR FUEL CYCLE

BACK END OF

NUCLEAR FUEL CYCLE

MANAGEMENT IN DRY

STORAGE

REPROCESSING OF FISSION PRODUCTS

DISPOSAL OF WASTE INTO

UNDERGROUND

REPROCESSING OF FISSION PRODUCTSReprocessing is removal of fissionable materials from products obtained from fission reactions.

PUREX CHEMISTRY

UREX CHEMISTRY

TRUEX CHEMISTRY

DIAMEX CHEMISTRY

SANEX CHEMISTRY

PUREX“Plutonium URanium EXtraction”PUREX is an acronym standing for Plutonium - URanium Extraction-standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used nuclear fuel. It is based on liquid-liquid extraction ion-exchange.

Invented by Herbert H. Anderson and Larned B. Asprey.

Solvent Extraction Process for Plutonium and Uranium.

Major reactant – TRIBUTYLPHOSPHATE

PUREX PROCESSDissolution in nitric acid

Addition of tributyl phosphate

Treating with ferrous sulphamate

Dissolution in nitric acidAddition of 7M nitric acid to irradiated fuel

Plutonium , Uranium and other soluble elements dissolve

Insoluble mass is removed as it affects further reactions by making emulsion stable

Addition of tributyl phosphateIt is done to extract uranium and plutonium from rest of the mass.

An organic solvent composed of 30% tributyl phosphate (TBP) in a hydrocarbon solvent, such as kerosene, is added .

It extracts Uranium as UO2((NO3)2·2TBP complexes, and plutonium as similar complexes, from other fission products, which remain in the aqueous phase .

The transuranium elements americium and curium also remain in the aqueous phase.

Structure of tributylphosphate

Treating with ferrous sulphamateIt is done to separate uranium and plutonium

Ferrous sulphamate in organic solvent, such as kerosene, is added

Plutonium reduces from +4 to +3 oxidation state and it passes into aqueous phase

Uranium is separated through back extraction

Ferrous sulfamate Fe(NH2SO3)2

OTHER PROCESS URanium EXtraction (UREX)

TRansUranium EXtraction (TRUEX)

DIAMide EXtraction (DIAMEX)

Selective ActiNide EXtraction (SANEX)

KEY POINTSLiquid–liquid extraction, also known as solvent extraction and partitioning, is a method to separate compounds based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent. It is an extraction of a substance from one liquid phase into another liquid phase

Back Extraction is a process where in equilibrium of the reaction is made to shift backward by decreasing the concentration of reactants.

Fusion

FUSION- „Small to Big‟The process of combining two lighter nuclei into a stable heavier nucleus with liberation of energy

“Producing power from fusion here on Earth is much more challenging than in the sun.”

Fusion reactorFusion reactor is an arrangement where in fusion of nuclei takes place with the release large amount of energy .

“Earthbound reactors cannot achieve the high pressures of the sun’s interior”, but this fact may be proved wrong after 10 years.

Many experiments have been executed , but none were fruitful.

ITER (International Thermonuclear Experimental Reactor)

This is a major demonstration of fusion’s potential which will soon be built in southern France.

Designed to reach a power level of 500 megawatts, ITER will be the first fusion experiment to produce long pulse of energy release on a significant scale.

Fuels used : Deuterium, Tritium

Equipment used : Magnetic confinement method in a device known as a Tokamak.

DEUTERIUM and TRITIUM: Main SourcesSeeing the word deuterium ,everyone assumes it to be complicated , but many don't know that it is even present in water( in small quantity).

Duetrium can be obtained through water electrolysis.

Heavy water = Deuterium oxide D2O=2H2O

Tritium, on the other hand, is radioactive and is extremely scarce in nature. That’s where lithium comes in. Simple nuclear reactions can convert lithium into the tritium

Electrolysis of Deuterium OxideElectrode : Platinum

Electrolyte : D2O( Acidified heavy water)

Anodic reaction: 20 -2 O 2+4e-

Cathodic reaction: 4D+ + 4e- 2D2

Net reaction: 4D++ O22- D2+ O2

Electrolysis

Deuterium and tritium fuel cycle

(1) 21D + 3

1T → 42He ( 3.5 MeV ) + n0 ( 14.1 MeV )

(2i) 21D + 2

1D → 31T ( 1.01 MeV ) + p+ ( 3.02 MeV )

(2ii) → 32He ( 0.82 MeV ) + n0 ( 2.45 MeV )

(3) 21D + 3

2He → 42He ( 3.6 MeV ) + p+ ( 14.7 MeV )

(4) 31T + 3

1T → 42He + 2 n0

+ 11.3 MeV

(5) 32He + 3

2He → 42He + 2 p+

+ 12.9 MeV

(6i) 32He + 3

1T → 42He + p+ + n0

+ 12.1 MeV

(6ii) → 42He ( 4.8 MeV ) + 2

1D ( 9.5 MeV )

(7i) 21D + 6

3Li → 2 42He + 22.4 MeV

(7ii) → 32He + 4

2He + n0 + 2.56 MeV

(7iii) → 73Li + p+ + 5.0 MeV

(7iv) → 74Be + n0 + 3.4 MeV

(8) p+ + 63Li → 4

2He ( 1.7 MeV ) + 32He ( 2.3 MeV )

(9) 32He + 6

3Li → 2 42He + p+

+ 16.9 MeV

(10) p+ + 115B → 3 4

2He + 8.7 MeV

Different fuel cycles

D + D → T + 1H

D + D → 3He + n

D-D fuel cycleThough more difficult to facilitate than the deuterium-tritium reaction, fusion can also be achieved through the reaction of deuterium

with itself. This reaction has two branches that occur with nearly equal probability:

D-3He fuel cycleA second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H). This reaction produces a helium-4 nucleus (4He) and a high-energy proton

3He +2H 4He

p-11B fuel cycleIf aneutronic fusion is the goal, then the most promising candidate may be the Hydrogen-1 (proton)/boron reaction:

Proton fuses with boron-11 ,to produces helium-4

1H + 11B → 3 4He

Will fusion energy be safe?It is difficult to get the fusion reaction going in the first place that it can be quickly stopped by eliminating the injection of fuel , but engineers know how to control the first generation of fusion plasmas.

Waste produced from this process is less radioactive and less harmful

ReferencesGirard, J.P., et al. 2007. ITER, safety and licensing. Fusion Engineering and Design 82(5-14): 506-510. DOI: 10.1016/j.fusengdes.2007.03.017.

Holtkamp, N. 2007. An overview of the ITER project. Fusion Engineering and Design 82(5-14): 427-434. DOI: 10.1016/j.fusengdes.2007.03.029.

Magaud, P., G. Marbach, and I. Cook. 2004. Nuclear Fusion Reactors. Pp. 365-381 in Encyclopedia of Energy, Volume 4, ed. C.J. Cleveland. Elsevier Science: Oxford, U.K. DOI: 10.1016/B0-12-176480-X/00305-3.

Wikipedia:

Link-http://en.wikipedia.org/wiki/PUREX

Thank You

Santosh M Naik 1RV12CV057 Roll no-21Vinayaka B M 1RV12CV061 Roll no-24F Section 2nd SemRVCE