nuclear fission and fusion.

Question 1

what is nuclear fission?

Answer 1

splitting of a large unstable nucleus ( normally uranium or plutonium.)

Question 2

when will nuclear fission occur?

Answer 2

by itself. usually the unstable nucleus must absorb a neutron first.

Question 3

what happens to the nucleus during fission?

Answer 3

splits into 2 smaller nuclei of roughly equal size.
emits 2 or 3 neutrons, gamma rays and energy.

Question 4

what do all the products of fission have?
( in terms of energy.)

Answer 4

kinetic energy.

Question 5

what happens to the emitted neutrons in fission?

Answer 5

start a chain reaction by being absorbed by other large, unstable nuclei.

Question 6

what is nuclear fusion?

Answer 6

it can be thought of as the opposite to nuclear fission.

Question 7

what happens during fussion?

Answer 7

2 light nuclei join together to form a heavier nucleus.
some of the mass is converted into energy and some of this energy may be emitted as radiation.

Question 8

why does nuclear fusion require very high temperatures and pressures?

Answer 8

to overcome the electrostatic repulsion.
bring the positive nuclei close enough together for fusion to take place.

Question 9

what is the 1 stage of nuclear fission?

Answer 9

neutron is absorbed by the uranium nucleus.

Question 10

what is the 2 stage of nuclear fission?

Answer 10

forms a larger unstable nucleus.

Question 11

what is the 3 stage of nuclear fission?

Answer 11

this larger nucleus from stage 2 splits into 2 smaller daughter nuclei.

Question 12

what is the 4 stage of nuclear fission?

Answer 12

2 or 3 neutrons and products are also released along with gamma rays.
( in my book where it says neutrons it wasn’t ticked and the rest were so if it’s wrong let me know :) )

Question 13

what is the 5 stage of nuclear fission?

Answer 13

although the fission product has kinetic energy most of it is carried by the neutrons.
( in my book where it says energy it wasn’t ticked and the rest were so if it’s wrong let me know :) )

Question 14

what is a chain reaction?

Answer 14

a nuclear chain reaction occurs when an unstable nucleus undergoes fission and 2 or more neutrons are released which in turn go on and cause more fission reactions.

Question 15

how can you control fission/ maintain a constant rate of energy?

Answer 15

release only 1 neutron from each fission reaction can go on to split another nucleus.

Question 16

what happens if there is an uncontrolled chain reaction?

Answer 16

results in melt down or the explosion caused by a nuclear weapon.

Question 17

key parts of a fission based power station: moderator- what is it?

Answer 17

slows neutrons down, moderates their velocity. fast neurons do not cause fission of U-235 and hence will not maintain the chain reaction.

Question 18

key parts of a fission based power station: control rods - what is it?

Answer 18

absorbs surplus neutrons to keep chain reaction under control. the depth that the control rods are immersed in the core is adjusted to keep a steady rate of fission.

Question 19

key parts of a fission based power station: coolant - what is it?

Answer 19

molecules gain kinetic energy from neutrons and fuel rods. heat is extracted using a heat exchanger and used to produce steam to turn the turbine.

Question 20

key parts of a fission based power station: thick concrete shield - what is it?

Answer 20

absorbs any radiation that does escape through the walls of the steel vessel, i.e. neutrons, as these are hazardous to humans.