1. NUCLEAR FISSION gamma rays High speed ‘fission’ Nuclear fission
fragment
Nuclear fission
* the splitting of large nuclei into smaller fragment nuclei.
High
speed
‘fission’
neutrons
gamma rays
U - 235
There is a small loss in mass after fission has occurred.
Einstein’s equation: E = mc2 shows how much energy is released.
c = speed of light 300,000,000 m/s and c2 = 9 x !!

2. * occurs when one fission event causes further fission events .
Chain reaction
* occurs when one fission event causes further fission events .
In a nuclear bomb two pieces
of pure U 235 or Pu 239
are forced together to exceed
the critical mass of 4.5kg.
Sub critical masses lose
too many neutrons
so the chain reaction
does not take place
gamma rays
U - 235
Fission neutrons
cause
further fission
Fissionable isotopes: Only Uranium is fissionable in the nuclear reactor.
Plutonium -239 is also fissionable and is created from the more common
Uranium ( 99% of natural uranium is U 238.)

3. A PWR REACTOR A moderator slows down the fast moving neutrons
Boron/steel control rods
absorb surplus neutrons.
Their depth allows one neutron
per fission to produce
one further fission
A PWR REACTOR
Fuel rods with enriched U
having 3% U 235
instead of less than 1%
( the rest is U 238)
A moderator slows down the fast moving neutrons
to allow successful collisions with U235 nuclei

4. a nucleus of U-235 or P-239 splitsB A

5. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
E = m x c2
E = x x x 10 16
E = x J

6. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
E = m x c2
E = x x x 10 16
E = x J

7. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
% Efficiency = useful power x 100%
total power
total power = x x 100%
30%
= x W
E = m x c2
E = x x x 10 16
E = x J

8. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
% Efficiency = useful power x 100%
total power
total power = x x 100%
30%
= x W
E = m x c2
E = x x x 10 16
E = x J
Power = Energy transferred
time
time (sec) = Energy transferred = x J = x 10 4 sec
Power x W
= Mins

9. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
% Efficiency = useful power x 100%
total power
total power = x x 100%
30%
= x W
E = m x c2
E = x x x 10 16
E = x J

10. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
% Efficiency = useful power x 100%
total power
total power = x x 100%
30%
= x W
E = m x c2
E = x x x 10 16
E = x J
Power = Energy transferred
time
time (sec) = Energy transferred = x J = x 10 4 sec
Power x W
= Mins

11. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
% Efficiency = useful power x 100%
total power
total power = x x 100%
30%
= x W
E = m x c2
E = x x x 10 16
E = x J
Power = Energy transferred
time
time (sec) = Energy transferred = x J = x 10 4 sec
Power x W
= Mins

12. If all the mass in a spoonful of sugar (5g) was converted to energy
by Einstein’s equation: E = mc2
c = speed of light 300,000,000 m/s and c2 = 9 x 10 16
Q1. How much energy is released?
Q2. If the UK needs 50GW of power and power stations are 30% efficient ,
how long could a spoonful of sugar keep the UK supplied with electricity?
% Efficiency = useful power x 100%
total power
total power = x x 100%
30%
= x W
E = m x c2
E = x x x 10 16
E = x J
Power = Energy transferred
time
time (sec) = Energy transferred = x J = x 10 4 sec
Power x W
= Mins
so 1Kg bag of sugar could keep the national grid running for 6 days!

13. Nuclear Bombs
Sub critical masses

14. Nuclear Bombs
above
critical mass

15. A PWR REACTOR