There are two main types of nuclear reactors: thermal (slow) reactors and fast reactors. Thermal reactors have a large, heavy core and use moderators like graphite or water to slow neutrons, making them easier to control. Fast reactors have a smaller, more compact size and can breed fuel. Nuclear fuel can be natural uranium, which contains the fissile U-235, or artificial fuel produced from fertile materials like U-238 or Th-232. Reactors are classified as burners, converters, or breeders depending on whether they only produce heat or can convert or breed more fuel. Breeder reactors are able to produce more fuel than they consume. Reactors require effective

1. CLASSIFICATION OF NUCLEAR
REACTORS
TYPES OF FISSION
• SLOW REACTORS OR THERMAL
REACTORS
– REACTOR CORE IS LARGE AND
HEAVIER
– THEY HAVE LONG NEUTRON
LIFE AND LOW POWER DENSITY
SO CONTROL IS EASIER
– LOW FUEL LOADING
– IT IS IMPOSSIBLE TO BREED
– LOW COOLING PROBLEMS
• FAST REACTORS
– FISSION CAUSED BY FAST
NEUTRON BUT THEIR SPEED
REDUCED BY MODERATOR
– HIGH FISSION RATE AND HIGH
BREEDING
– SMALL IN SIZE AND COMPACT
– EASIER TO SHIELD
– HIGH POWER DENSITY (
KW/m3)RESULTS IN COOLING
AND HT PROBLEMS

3. TYPES OF FUEL
• NATURAL URANIUM –
FISSIONABLE U 235 AND
FERTILE U 238. SO PU 239 IS
PRODUCED AND U 233
FROM THORIUM 232 ARE
PRODUCED ARTIFICALLY
FROM A FERTILE MATERIAL
BY NEUTRON REACTION.
FUEL CYCLES
• BURNER REACTOR - ONLY
HEAT IS PRODUCED
WITHOUT CONVERSION
• CONVERTOR REACTOR –
MATERIAL CONVERTED BY
PUTTING FERTILE MATERIAL
IN CORE U 238 TO PU 239.
• BREEDER REACTOR – PU
239 IS THE FUEL AND U 238
CONVERTED TO PU

5. Breeder reactor
• r= no of fuel atoms formed/
no of original fuel atoms
consumed in fission ; r<1
convertor if r > 1 then
breeder ( 7 to 15 yrs to
produce fuel for another
reactor)
• Breeder generated energy
and also produces fuel than
it consumes.

8. STATE OF FUEL
• SOLID OR LIQUID- MOSTLY
SOLID BUT MAY BE MIXED
WITH URANIUM OXIDE TO
FORM SLURRY IN WATER OR
LIQUID METAL. SO ITS CALLED
LIQUID METAL FUELED
REACTOR( LMFR)-SGR –
PERMITS HIGH TEMP,
PRESSURIZATION SOLVED.
• POSITION OF FERTILE AND
FISSILE MATERIAL
RELATIVE POSITION TO EACH
OTHER IN REACTOR CORE.

9. CHOICE OF MODERATOR
• TYPES OF MODERATOR ;
GRAPHITE , NATURAL
WATER AND HEAVY WATER .
GRAPHITE HAS HIGHER
ATOMIC WEIGHT THAN
WATER SO THEY ARE BULKY.
NATURAL WATER GIVES A
SMALL AND COMPACT
REACTOR.
CORE COMPOSITION

10. METHOD OF COOLING
• DIRECT COOLING AND
INDIRECT COOLING
• ORDINARY WATER IS USED
WITH ENRICHED URANIUM
AND HEAVY WATER WITH
ORDINARY URANIUM DUE
TO THEIR NEUTRON
ABSORPTION CAPABILITY
• LOW NEUTRON
ABSORPTION

11. GAS COOLED REACTOR
• GAS IS CIRCULATED
THROUGH REACTOR
CORE TO COOL THE
REACTOR.AIR ,HE
,HYDROGEN OR CO2.
• POOR HEAT TRANSFER OF
GASES REQUIRE HIGH
PUMPING POWER.
• CORROSION PROBLEMS
RESOLVED
• POWER DENSITY IS LOW

12. WATER COOLED REACTOR
• LIGHT WATER REACTOR-
HAS GOOD THERMAL
PROPERTIES, CHEAP
COOLANT, BUT IT HAS
CORROSION ISSUES
AND DUE TO NEUTRON
ABSORPTION MAY
INTERRUPT CRITICALITY.
• BWR-BOILING WATER
REACTOR

13. • WATER CONVERTS TO
STEM AND DIRECTLY
IMPINGES ON TURBINE
• STEAM LEAVING
REACTOR MAY BE
RADIOACTIVE AND
PIPING AND STEAM
TURBINE

14. PRESSURIZED WATER REACTOR
• WATER IS PRESSURIZED
TO PREVENT BULK
BOILING AT 150 ATM.
• HOT WATER FROM
REACTOR FLOWS TO
STEAM GENERATOR
(HX)WHERE ITS HEAT IS
TRANSFERRED TO FEED
WATER TO GENERATE
STEAM.

15. • STEAM IS PRODUCED AT
7.5 TO 8 Mpa AND 320 C.
• PWR ARE STABLE.
• TURBINE LOOP SEPARATE
THAN PRIMARY SO LESS
CHANCES OF
RADIOACTIVE.
• THE LIQUID SHOULD BE
HIGHLY PRESSURIZED TO
REMAIN LIQUID AT HIGH
TEMP.SO HIGH COST PIPE

16. COOLANT
• COOLANT PICKS UP HEAT AND KEEP FUEL
ASSEMBLIES AT SAFE TEMP TO AVOID
DESTRUCTION AND MELTING.
• AIR,HELIUM,WATER,CO2,H2,NA ,K,
• IT SHOULD HAVE REALISTIC FLUIDITY FOR HT.
• LOW ABSORTION OF NEUTRON
• IF COMPOUND,STABILITY FROM DISASSOCIATION
• SPECIFIC HEAT ANG K SHOULD BE HIGH TO HT.
• NON CORROSIVE
• THERMAL STABILITY

17. NEW TRENDS
• ORGANIC SUBSTANCE COOLED REACTORS
,OIL,PETROLEUM
• CAN OPERTAE AT HIGH TEMP WITH MODERATE
PRESSURE.SO LIGHTER EQUP,DEVICES ,PIPES(
ORDINARY STEEL ) AND REDUCED COST.
• LESS CORROSIVE THAN WATER
• H2 CONTENTS MAKES THEM ACCEPTABLE AS
MODERATORS
• THESE DON’T BECOME RADIOACTIVE AS NEUTRON
BOMBARDMENT.
• DON’T FREEZE AT LOW TEMP SO GOOD FOR USE IN
COLD REGIONS

18. FUEL CYCLE

19. GASES DIFFUSION

20. CENTRIFUGAL/ THERMAL DIFFUSION

21. ELECTROMAGNETIC DIFFUSION