Basic Nuc Physics

AIM

TO ACQUAINT YOU WITH BASIC NUC BASIC NUCPHYSICSPHYSICS

PHASESPHASE 1 STRUCTURE OF ATOM

PHASE 2 BINDING ENERGY AND MASS

DEFECT

PHASE 3 NATURAL RADIOACTIVITY,

ARTIFICIAL RADIOACTIVITY &

NEUTRON BOMBARDMENT.

PHASE 4 FISSION AND FUSION.

PHASE 5 CHAIN REACTION,CRITICAL

MASS AND REFLECTORS.

SCOPETO FAMILIARISE YOU WITH THE STRUCTURE OF ATOM, BINDING ENERGY AND MASS DEFECT, NATURAL AND ARTIFICIAL RADIO ACTIVITY,FISSION, FUSION, CHAIN REACTION, CRITICAL MASS AND REFLECTORS.

MATTER

ELEMENT

AN ELEMENT IS A SUBSTANCE WHICH CANNOT BE SPLIT UP INTO TWO OR MORE SIMPLER SUBSTANCES BY THE USUAL CHEM METHODS OF APPLYING HEAT, LT OR ELECTRIC ENERGY. AN ELEMENT IS MADE UP OF ATOMS, ALL HAVING SAME ATOMIC NUMBER.

A MOLECULE IS THE SMALLEST PARTICLE OF A SUBSTANCE ( ELEMENT OR COMPOUND) WHICH HAS THE PROPERTIES OF THAT SUBSTANCE AND CAN EXIST IN FREE STATE.

MOLECULE

STRUCTURE OF STRUCTURE OFATOMATOM

•DEFINITION OF ATOM

•STRUCTURE OF HYDROGEN AND HELIUM ATOM

•ATOMIC AND MASS NUMBER

•UNITS OF ATOMIC MASS (M.U.)

•EINSTEIN`S MASS ENERGY RELATIONSHIP

•ISOTOPES

ATOM• AN ATOM CAN BE DEFINED AS

THE SMALLEST QUANTITY OF AN ELEMENT WHICH CAN ENTER INTO A CHEMICAL REACTION. ALL ATOMS OF A PARTICULAR ELEMENT ARE CHEMICALLY ALIKE BUT THEY DIFFER FROM THE ATOMS OF OTHER ELEMENTS.

STRUCTURE OF ATOM

NUCLEUSPROTONS

NEUTRONS

MASS CHARGENEUTRON 1.00898 m.u NO CHARGE

PROTON 1.00759 m.u + VE CHARGE

ELECTRON 0.000548 m.u - Ve CHARGE

STRUCTURE OF HYDROGEN ATOM

EMPTY SPACE SHELL

ELECTRON

10,000 IN(APPROX 1/6 MILE)

ATOM OF HYDROGEN MAGNIFIED 2.5 X 1012 TIMES

140 YD

1”

HELIUM ATOM

NEUTRON

ELECTRON

PROTON

EMPTY SPACE

EVOULUTION OF STRUCTURE OF ATOM

STRUCTURE OF HELIUM ATOM

EMPTY SPACE SHELL

NEUTRONS

PROTONS

NUCLEUS

ATOMIC AND MASS NUMBER

• ATOMIC NO (Z) = NUMBER OF UNIT

POSITIVE CHARGES

= NO OF PROTONS = NO

OF ELECTRONS• MASS NO (A) = NUMBER OF PROTONS

PLUS NEUTRONS • NO OF NEUTRONS = A -Z

• SYMBOLIC REPRESENTATION- 2 He 4 ( Z He A )

UNIT OF ATOMIC MASS

UNIT OF ATOMIC MASS OR ATOMIC MASS UNIT (AM U) IS DEFINED AS 1/16 OF THE MASS OF OXYGEN ATOM AND IS EQUAL TO 1.66X10-24 GRAMS

CHARGE AND MASS OF ELECTRON, PROTON AND

NEUTRONPARTICLE SYMBOL AMU MASS CHARGE

GRAMS UNITS COLOUMBS

ELECTRON e- 0.000548 9.1 X 10 –28 -1 -1.60 X 10 -19

PROTON P+ 1.00759 1.672 X 10 -24 +1 + 1.60 X 10 -19

NEUTRON n 1.00898 1.674 x 10 -24 0 0

ISOTOPES• MTRLS HAVING SAME ATOMIC No BUT

DIFFERENT ATOMIC MASS No.

ISOTOPES OF HYDROGEN

1H1 - 99.985% - NATURAL HYDROGEN – LT

1H2 - 0.015% - DEUTERIUM (D) – HY

1H3 - VIRTUALLY MAN MADE -TRITIUM (T)

– 92U 238 - 99.3 % - NOT READILY

FISSIONABLE

– 92U 235 - 0.7 % - READILY

FISSIONABLE

– 92U 233 - ARTIFICIALLY MADE READILY FISSIONABLE

– ISOTOPE OF SILVER = 106.948 M.U

– TOTAL WT OF

• 47 PROTONS• 60 NEUTRONS = 107.944 MU

• 47 ELECTRONS

– MASS DEFECT = 0.996M.U.

BASICS OF NUC ENERGY• ALBERT EINSTEIN PROPOUNDED MASS AND

ENERGY ARE CONVERTIBLE AND EST THE FORMULA : E = mc2

WHERE, E = energy in ergs, m = mass in grams,

c = velocity of lt (3 x 1010 cm\sec) • NEUTRONS BEING ELECTRICALLY NEUTRAL,

CAN PENETRATE UPTO NUCLEUS OF AN ATOM AND LIKELY TO CAUSE BREAKING UP OF NUCLEUS.

• IN BEAKING UP OF AN ATOM, THERE IS CHANGE IN TOTAL MASS AND THE ENERGY THUS RELEASED IS ENORMOUS.

EINSTEIN'S MASS ENERGY RELATIONSHIP

E = MC 2

E = ENERGY IN ERGS – (10 7 ERGS = 1 JOULE )

M = MASS IN GRAMS

C = VELOCITY OF LIGHT = 3 x 10 10 CM/SEC

ERG - WORK DONE BY A FORCE OF 1 DYNE WHEN ITS POINT OF APPLICATION MOVES BY ONE CM IN THE DIRECTION OF THE FORCE.

COULOMB’S LAW

• LIKE CHARGES REPEL UNLIKE CHARGES ATTRACTS IN AN INVERSE SQUARE RELATIONSHIP

F = q1X q2

d2

WHERE, q1 AND q2 ARE TWO ELECTRICAL CHARGES MEASURED IN e.s.u. ; d THERE DIST APART IN cms AND F THE RESULTANT REPULSIVE OR ATTRACTIVE FORCE IN DYNES

BINDING ENERGY AND MASS DEFECT

• FORCES IN AN ATOM : COULOMB’S LAWF = q1 x q2 F = FORCE IN DYNES.

d2 q1 AND q2 = ELECTRIC CHARGES IN ESU.

d = DISTANCE IN CM.• MASS DEFECT

ATOMIC WEIGHT OF SINGLE PURE ISOTOPE IS LESS THAN SUM OF WEIGHTS OF INDIVIDUAL PROTONS, NEUTRONS AND ELECTRONS.– ISOTOPE OF SILVER - 106.948 M.U

(MASS NO - 107)

Contd…

– ISOTOPE OF SILVER = 106.948 M.U

– TOTAL WT OF

• 47 PROTONS• 60 NEUTRONS = 107.944 MU

• 47 ELECTRONS

– MASS DEFECT = 0.996M.U.

CONSIDER THE EXAMPLE OF FLOURINE( 9F 19)

– THE ISOTOPE HAS 9 PROTONS, 9 ELECTRONS AND 10 NEUTRONS.

• 9 PROTONS(9X1.00759) = 9.06831 amu

• 9 ELECTRONS(9X0.00055) = 0.00495 amu

• 10 NEUTRONS(10X1.00899)= 10.08990 amu

TOTAL = 19.16316 amu– KNOWN MASS OF THIS NUCLIDE IS 19.00445

amu.– DIFF BETWEEN KNOWN MASS AND THE

MASSES OF PARTICLES IS 0.15871 amu.– THE LOST MASS IS CONVERTED INTO

ENERGY AND IS CALLED MASS DEFECT.

BINDING ENERGY

BINDING ENERGY IS THAT AMT OF ENERGY WHICH WOULD NEED TO BE APPLIED TO A NUCLEUS TO BREAK IT DOWN INTO ITS CONSTITUENT NUCLEONS “STABILITY OF NUCLEUS CAN BE ASSESSED FROM THE VALUE OF ITS BINDING ENERGY PER NUCLEON. GREATER THE ENERGY PER NUCLEON, GREATER IS THE STABILITY”

20 40 60 80 100 120 140 160 180 200 220 240

BINDING ENERGIES PER NUCLEON

9

8

7

6

5

4

3

2

1

0

U 235

2H

1

2H

1

6L1

3

10B

5

MAX 8.7MEV

E

N

E

R

G

Y

(MeV)

MASS NO

UNITS OF ENERGY• ELECTRON VOLT(EV). KE GAINED BY A

PARTICLE CARRYING UNIT ELECTRICAL CHARGE,(e) WHEN ACCELERATED THROUGH A POTENTIAL DIFFERENCE OF ONE VOLT.

• UNIT ELECTRICAL CHARGE = 4.8 x 10 -10 E.S.U

• KILO ELECTRON VOLT - KeV 103

• MILLION ELECTRON VOLT - MeV 106

• BILLION ELECTRON VOLT - BeV (GeV) 109

IONISATION• IF AN ORBITING ELECTRON IS

PULLED OR FORCED AWAY FROM AN ATOM, THE ATOM, NOW POSITIVELY CHARGED, IS CALLED A POSITIVE ION AND THE PROCESS IS KNOWN AS IONISATION.THE DETACHED ELECTRON OFTEN ATTACHES ITSELF TEMPORARILY TO ANOTHER ATOM WHICH IS THEN A NEGATIVE ION.

NATURAL RADIOACTIVITY

• PROTON - NEUTRON RATIO

• TYPES OF RADIATION

• PENETRATING POWER OF

RADIATIONS

•RADIOACTIVE TRANSFORMATION

•RADIOACTIVE DECAY

NEUTRON-PROTON RATIOS OF STABLE NUCLEI140

120

100

80

60

40

20

0 20 40 60 80 100 120 140

NUMBER OF PROTONS (P)

NU

MB

ER

OF

NE

UT

RO

NS

(N

)

β EMISSION-EMISSION

STABILITY BELT

n/p = 1

DEFLECTION OF RADN FROM RADIATION SOURCE

++

++

++

+

I I I I I I α(+)β(-)

.ץ

LEAD BLOCKRADN SOURCE

RELATIVE COMPARATIVE PENETRATING POWER OF RADIATIONS

PAPERLEADALLUMINIUM

γα β α α β β γ γ

PROPERTIES OF ∝ PARTICLES

• HELIUM NUCLEUS - +Ve CHARGE

•POSSESS GREAT ENERGY - 5.3 MeV

•HIGH INITIAL VELOCITY

•CAUSE INTENSE IONISATION

•SHORT RANGE – 4-5 CM

PROPERTIES OF β PARTICLES• AN ELECTRON

• HIGH SPEED

• SMALL MASS - EASILY DEFLECTED

• HAS HALF THE CHARGE OF α PARTICLE

• LESS ABILITY TO IONISE

• COMPARATIVELY LONGER RANGES. – 60” (AIR), 4 MM (AL)

Gamma rays, or high energy photons, are emitted from the nucleus of an atom when it undergoes radioactive decay. The energy of the gamma ray accounts for the difference in energy between the original nucleus and the decay products. Gamma rays typically can have about the same energy as a high energy X ray. Each radioactive isotope has a characteristic gamma-ray energy.

GAMMA RAYS

PROPERTIES OF γ RAYS• FORM OF ELECTRO MAGNETIC RADIATIONS

(WAVE LENGTH 10-8 cms) • SIMILAR TO X - RAYS.• ORIGIN OF γ RAYS -NUCLEUS.• EMITTED DURING TRANSITION FROM

MORE EXCITED STATE TO A LESS EXCITED STATE

• HIGHLY PENETRATING.• MAY CAUSE

– PHOTO - ELECTRIC EFFECT– COMPTON EFFECT– PAIR PRODUCTION

PHOTO ELECTRIC EFFECT• The emission of electrons from matter by

EM radn of certain energies. The energy of the incident radn is tfr in discrete amts (photons) each of magnitude hy. Each photon absorbed will eject an electron provided that the photon energy exceeds a certain value φ -- the wk function. The max KE of the electrons E is then given by E = hv –φ . This is known as Einstein’s Photo electric theory.

PHOTO ELECTRIC EFFECT• A γ PHOTON STRIKES AN ORBITAL ELECTRON

AND KNOCKS THE ELECTRON OUT OF ITS POSN IN THE ATOM.

• ALL OF THE ENERGY IN THE INCIDENT PHOTON IS USED IN REMOVING THE ELECTRON FROM THE ATTRACTION OF THE NUCLEUS AND IN IMPARTING KE TO THE ELECTRON.

• THE PHOTON IS ANNHILIATED BY TFR OF ALL ITS ENRGY TO THE ELECTRON. THE FREED ELECTRON BEHAVES AS A β PARTICLE AND IONISATION PRODUCED BY IT ARE CALLED SECY IONISATIONS.

PHOTO ELECTRIC EFFECT

NUCLEUS

(Photon)E=h f

ELECTRON

COMPTON EFFECT• INCOMING PHOTON MAY NOT GIVE UP ITS

COMPLETE ENERGY IN THE COLLISION WITH THE ELECTRON.

• AS A RESULT A LOWER ENERGY PHOTON REMAINS AFTER THE COLLISION, WHICH MAY INTERACT WITH OTHER ELECTRONS AND LOSE ENERGY AFTER EACH COLLISION.

• BUT THE LAST INTERACTION RESULTING FROM IT MUST RESULT IN PHOTOELECTRIC EFFECT.

• USUALLY WITH PHOTONS OF SUFFICIENTLY HIGH ENERGIES (0.1 – 1.0 MeV).

COMPTON EFFECT

NUCLEUS

ELECTRON

ORGINAL MOTION PATH OF PHOTON

SCATTERED PHOTON PATH ץ PHOTON e = hy

PAIR PRODUCTION

• WHEN THE ENERGY OF γ RADIATION BECOMES > 1.02 MeV, PAIR PRODUCTION IS POSSIBLE.

• IF A HIGH ENERGY PHOTON PASSES CLOSE TO A NUCLEUS, IT CAN BE CONVERTED INTO TWO PARTICLES (ELECTRON AND POSITRON) AT THE SAME INSTANT.

• TAKES PLACE AT A POINT EXTEREMLY CLOSE TO THE NUCLEUS OF A HY ATOM.

• THE PHOTON IS ANHHILIATED IN THE PROCESS AND ALL ENERGY CONVERTS TO THE MASSOF THE PARTICLES + KE.

• ELECTRON AND POSITRON ARE CAPABLE OF PRODUCING IONISATION IN THEIR PATH.

PAIR PRODUCTION

NUCLEUS

γ photon

ELECTRON

POSITRON

NEUTRON BOMBARDMENT• Neutral• Successive elastic or inelastic

collisions. Scattering. Very eff by hydrogenous mtrl. Good moderation.

• Slow Nu - <100 eV.• Nu Decay – Free space for about 10 –

15 mins then decay to a Proton and Electron.

• A Nu addition increase energy in hy mtrl by 8 MeV.

DISINTEGRATION BY NEUTRON

• NEUTRON CAPTURE CREATES FISSION ( N F).• NEUTRON ENERGY EXCITES UNSTABLE

NUCLEUS– SPLIT IT INTO FAIRLY TWO EQUAL PARTS,EJECTS FREE NU AND RELEASE HUGE ENERGY.235 1 144 90 1

U + N ----- Ba + Kr + 2N +ENERGY

92 0 56 36 0

RADIOACTIVE TRANSFORMATION

226 222 4

• Ra Rn + He

88 86 2

222 218 4

• Rn Po + He

86 84 2

218 214 4

• Po Pb + He

84 82 2

214 214 0

• Pb Bi + e

82 83 1

226 222 4

NOTE. Ra Rn + He+ γ(0.19 MeV

88 86 2

HALF - LIFEThe time taken by half of the atoms of a RA element to disintegrate is called its half life. After half life, the radioactivity of an element also becomes half of the original value.The half life of Ra is about 1600 yrs, which means that a given sample of Ra will disintegrate half in 1600 yrs. Eg, if we start with 1 gm of Ra today, then half gm of it will disintegrate in 1600 yrs. After another 1600 yrs half of remains will have disintegrated and so on.

HALF LIVES OF VARIOUSELEMENTS

• URANIUM 238 - 4.55 X 10 9 YRS

• POLONIUM 210 - 140 DAYS

• POLONIUM 212 - 3 X 10 -7 SECS

DECAY CURVE OF A TYPICAL RADIO ACTIVE SUBSTANCE

100

90

80

70

60

50

40

30

20

10

00 T 2T 3T 4T 5T 6T 7T 8T 9T 4 8 12 16 20 24 28 32 36

HALF LIVES HOURS

TIME

RA

DIO

AC

TIV

E I

NT

EN

SIT

Y

BETA DECAY

ARTIFICIAL RADIOACTIVITY

27 4 30 1 • Al + He P + n13 2 15 0

30 30 0• P Si + e15 14 + 1

NOTE EVERY ELEMENT TODAY HAS ISOTOPES AND SOME 800 HAVE BEEN OBTAINED BY VARIOUS TRANSMUTATION PROCESSES.

Nu INDUCED RADIO ACTIVITY

• PRODUCT OF Nu CAPTURE ARE RADIO- ACTIVE.

• AIR – Oxygen and Nitrogen little or no significance.

• SOIL– Na 24- half life about 15 hrs, emits Beta and Gamma of nearly 3 MeV. Mn essential for plant growth capture and produce Mn 56 , half life 2.6 hrs, emits Beta and gamma. Silicon and Al produce silicon 31 (2.6 hrs) and Al 28 (2.5 mins). Although contribute to the imdt activity, would be of no significance of after an hr or so.

Contd

• WATER – Hydrogen from non radio active D2. Cl forms cl 38 and emits Beta and hy energy Gamma ( 4-5Hrs ).

• STRUCTRE MTRL. – Source for induced activity for a short while Cu, Zn and Mn are imp in this case.

FISSION AND FUSION

• THE RELEASE OF NUC ENERGY IN AMTS SUFFICIENT TO CAUSE AN EXPLOSION, REQUIRES THAT THE REACTION SHOULD BE ABLE TO REPRODUCE ITSELF WHEN STARTED.

• TWO TYPES OF NUC INTERACTIONS CAN SATISFY THE CONDITIONS FOR THE PRODUCTION OF LARGE AMTS OF ENERGY IN A SHORT TIME.

• THESE ARE KNOWN AS FISSION AND FUSION.

FISSION• DEFINITION.

• FISSION FRAGMENTS.

• TYPES OF FISSION.

• CRITICAL ENERGY FOR FISSION.

• ENERGY RELEASED.

NUCLEAR FISSION

FISSION

IS A PROCESS,THE REACTING NUCLEUS SPLITS INTO PARTS OF ROUGHLY EQUAL MASS, BOTH OF WHICH HAVE MUCH LOWER ATOMIC NOS AND MASS NOS THAN THE ORIGINAL NUCLEUS. THE REACTION IS ACCOMPANIED BY THE RELEASE OF ENORMOUS QTY OF ENERGY AND VERY IMP, THE EXPULSION OF ONE OR MORE NEUTRONS.

TYPE OF FISSION• THERMAL NEUTRON FISSION (>0.03 eV)

Example-U235

• FAST NEUTRON FISSION (> 1MeV ). U238 UNDERGO FISSION BY FAST NEUTRONS ONLY.

CRITICAL ENERGY FOR FISSION

• ENERGY REQUIRED TO CAUSE SEVERE DEFORMATION OF THE NUCLEUS – CRTICAL DEFORMATION ENERGY (CDE).

• THE ENERGY GAINED UPON ENTRY OF THE NEUTRON AND BINDING ENERGY. BOTH ARE IMPORTANT IN DETERMINING THE EASE OF FISSION.

• CDE DEPENDS UPON THE RELATIONSHIP BETWEEN THE MASS NO AND THE ATOMIC NO OF THE NUCLEUS.

C- ENERGY FOR FISSION

• CRITICAL DEFORMATION ENERGY (CDE) - DEPENDS ON ATOMIC AND MAS NUMBERS

CDE REQURIED KE REQUIRED

FOR FISSION FOR FISSION

U 238 6.5 MEV HIGH ENERGY 1.0 MEV

U 235 6.1 MEV

THERMALNEUTRONS

(0.03 EV)

U 233 6 MEV THERMAL NEUTRONS

ENERGY RELEASED - FISSION

• AVG ENERGY PER FISSION = 200 MEV

• MASS DEFECT METHOD.

92U235 + 0N 1 42Mo95 + 57La139 + 2 0N1

• MASS OF 92 U235 = 235.124 MU

• MASS OF 0N1 = 1.009 MU

• TOTAL =236.133 MU

• MASS OF 42 Mo 95 = 94.946 MU

• MASS OF 57 LA 139 = 138.955 MU

• MASS OF 2 X 0N1 = 2.018 MU• TOTAL 235.919 MU• MASS DEFECT = 236.133 - 235.919 = 0.214 MU.

ENERGY RELEASED = 0.214 X 931 = 200 MEV PER FISSION. (931 IS THE CONVERSION

FACTOR)

CHAIN REACTIONIT IS THE PROCESS IN WHICH THE NUMBER OF NEUTRONS KEEP ON MULTIPLYING RAPIDLY (IN A GEOMETRIC PROGRESSION) DURING FISSION TILL THE ENTIRE FISSIONABLE MATERIAL IS EXHAUSTED

U 235 CHAIN REACTION• WHEN A U235 NUCLEI IS BOMBARDED BY A

NEUTRON, TWO OR MORE NEUTRONS ARE RELEASED WHICH FURTHER BOMBARD OTHER NUCLEI.

• IT TAKES MINIMUM OF 80 CYCLES FOR ONE KG OF U235 TO BREAK DOWN INTO ITS CONSTITUENT NUCLEONS.

• THEREFORE 280 REACTIONS TAKES PLACE.

• AVG TIME TAKEN TO CAUSE SPLITTING = 10 -8 SEC.

U235 CHAIN REACTION

U235 LOST

NEUTRON

FISSION FRAG

NEUTRON

U235

U235

CRITICAL MASS•DEFINITION

QTY OF FISSILE MTRL REQD SO THAT CHAIN REACTION JUST BECOMES SELF SUSTAINING.

REPRODUCTION FACTOR HAS TO BE MORE THAN UNITY

•DEPENDS UPON:--

DENSITY.

PURITY.

SHAPE AND SIZE - SPHERICAL (MIN SURFACE AREA FOR A GIVEN VOL).

WPN DESIGN - USE OF REFLECTORS.

NEUTRON PRODUCTION AND ESCAPE RATIO

• NEUTRONS PRODUCED IS PROPOTIONAL TO THE NO OF FISSIONS, WHICH IN TURN IS PROPOTIONAL TO THE NO OF FISSILE ATOMS.(MASS OF THE FISSILE MTRL).

• FOR A SPHERE OF A PURE FISSILE MTRLOF RADIUS R,- SURFACE AREA = 4 π R2

- MASS =4/3 π R3 X DENSITY• THE RATIO OF NEUTRONS ESCAPING TO NO OF

NEUTRONS PRODUCED WILL VARY AS PER –= SURFACE AREA /MASS= 3 / R X DENSITY

NEUTRON PRODUCTION AND ESCAPE RATIO (CONTD)

HENCE , INCR IN EITHER RADIUS OR DENSITY OR BOTH WILL REDUCE THE PROPORTION OF THE ESCAPING NEUTRONS AND INCR THE LIKELYHOOD OF A CHAIN REACTION.

REFLECTION OF NEUTRONS

• REFLECTORS. USED IN WEAPONS TO REFLECT BACK THE NEUTRONS INTO THE SYSTEM. HIGH DENSITY ATOMIC MASS MTRLS – U235.

• MODERATORS. USED IN REACTORS TO SLOW DOWN AND SCATTER BACK THE NEUTRONS INTO THE SYSTEM. LOW ATOMIC MASS ELEMENTS LIKE –CARBON, BERYLLIUM, GRAPHITE RODS.

TYPICAL FISSION PRODUCTS

92U235

40ZR97

41Nb97

42Mo97

52Te137

53 I137

54Xe137

55Cs137

56Ba137

40 PROTONS

57 NEUTRONS

41 PROTONS

56 NEUTRONS

42 PROTONS

55 NEUTRONS STABLE

52 PROTONS

85 NEUTRONS

53 PROTONS

84 NEUTRONS

54 PROTONS

83 NEUTRONS

55 PROTONS

82 NEUTRONS

56 PROTONS

81 NEUTRONSSTABLE

-β

-β

-β

-β

1 MIN

22.5 SEC

3.4 MIN

ABOUT 27 YRS

17 HRS

75 MIN

-β

-β

NEUTRON

92 PROTONS

143 NEUTRONS

Zirconium / Tellurium

Niobirium

Molydbynum

Iodine

Xenon

Cesium

Barium

NUCLEAR FUSION

NUCLEAR-FUSIONTHE COMBINATION OF VERY LIGHT

NUCLEI LOW IN MASS NUMBER INTO A HEAVY NUCLEI ALONG WITH RELEASE OF ENORMOUS ENERGY IS CALLED NUCLEAR FUSION.

FUSION THE COMBINATION OF VERY LIGHT

NUCLEI, LOW IN MASS NUMBER INTO PRODUCT NUCLEI THAT ARE NEARER THE MIDDLE OF SCALE, FORMS THE FUSION PROCESS.

(BECAUSE THE FIRST THOUGHTS IN THIS FIELD WERE DIRECTED TOWARDS THE USE OF THE LIGHTEST OF ALL NUCLEI HYDROGEN, THE EARLIEST EXPLOSIONS PRODUCTED BY THIS MEANS WERE POPULARLY TERMED HYDROGEN EXPLOSIONS)

PRACTICAL CONSIDERATIONS FOR FUSION PROCESS

• HIGH TEMP (SEVERAL MILLION DEG C) REQD TO ACCOMPLISH FUSION REACTION.

• DIFFICULT TO MAINTAIN SUCH HIGH TEMP FOR LONG DURATIONS.

• THEREFORE REQMT OF GREATEST ENERGY RELEASE IN THE LEAST TIME.

POSSIBLE MTRL FOR FUSION PROCESS

• ORIDINARY HYDROGEN IS NOT SUITABLE AS ENERGY PRODUCING REACTIONS INVOLVE SLOW NUC CHANGES.

• 1H2 AND 1H3 SHOW MORE PROMISE AS FUELS.

1H2 EXISTS IN ORDINARY WATER (0.015%), AND IS GEN USED.

• 1H3 IS MANMADE, AND VERY EXPENSIVE TO PRODUCE. ALSO IT HAS A HALF LIFE OF ONLY 12 ½ YRS .

• ALTERNATIVELY 1H3 CAN BE PRODUCED IN A NUC REACTOR BY IRRADIATION OF 3LI6.

ENERGY RELEASED - FUSION

• 1lb OF 1 H2 = 26000 TONS TNT.

• 4 KG LI 6D - POSSIBLE REACTIONS

1H3 + 1H22HE4 + 0N1 + 17.6 MeV

1H2 + 1H22HE3 + 0N1 + 3.2 MeV

1H2 + 1H2 2HE3 + 20N1 + 4.O MeV

5 x 1H2 ATOMS - ENERGY RELEASED 24.8 MeV

…contd

• 4 KG LI 6D CONTAINS 1 KG 1H 2

ENERGY RELEASE

• COMPARISON = 5.7 X 10 4 TONS TNT = 57 KT

• 1 KG URANIUM 100% EFFICIENCY = 20 KT THUS FUSION:FISSION = 57 KT : 20 KT FOR 1 KG FUEL.

PERIODIC TABLE