Nuclear Fission

Question 1

what is nuclear fission industrially

Answer 1

• a type of nuclear reaction that is used to release energy from uranium
• a lot of energy can be released this way by using a chain reaction

Question 2

how does the fission of a uranium nucleus happen

Answer 2

• a slow moving neutron is fired at a large unstable nucleus (uranium-235)
• the neutron is absorbed by the nucleus
• making the atom more unstable and causing it to split

Question 3

what is fission

Answer 3

splitting apart

Question 4

what is the result of uranium 235 being split into two forms of new lighter elements

Answer 4

a lot of energy is released

Question 5

what are the new lighter elements that are created when a nucleus has been split into two called

Answer 5

daughter nuclei

Question 6

what are all the type of nuclei that U 235 spit into have to be and what are some examples of daughter nuclei it can split into

Answer 6

• it can split into krypton-91 and barium-143

- and all of these nuclei have to be radioactive

Question 7

how does a chain reaction occur during the fission of a U 235 atom

Answer 7

• each time a uranium atom splits up
• it also spits out two or three neutrons
• which can hit other uranium nuclei and be absorbed
• causing them to split also and so on

Question 8

why do nuclear fission reactions accelerate the longer they are carried out

Answer 8

• as each uranium nuclei spits out two or three neutrons
• they will be absorbed by two or three uranium atoms
• and the number of stray neutrons will increase each time
• causing more uranium atoms to absorb the higher number of neutrons and it will only continue to accelerate

Question 9

what does the neutron have to do in order to cause nuclear fissions

Answer 9

they have to be moving slowly enough to be captured by the uranium nuclei in the fuel rods

Question 10

what are slow moving neutrons called

Answer 10

thermal neutrons

Question 11

as the neutrons released by fission reactions have a lot of energy and are moving fast, what is done to slow down the neutrons

Answer 11

• uranium fuel rods containing uranium
• are placed in a moderator such as graphite
• to slow down the fast moving neutrons

Question 12

what are control rods made of and what do they do

Answer 12

• they are usually made up of boron

- they limit the rate of fission by absorbing excess neutrons

Question 13

what is done if a fission reaction become to vigorous

Answer 13

• control rods are placed in between the fuel rods

- and are raised and lowered into the reactor to control the chain reaction by absorbing the neutrons

Question 14

what is the effect of control rods being slid in between fuel rods

Answer 14

• it creates a steady rate of nuclear fission

- where one new neutron produces another fission

Question 15

what could happen if the chain reaction in a nuclear reactor is left to continue and is unchecked

Answer 15

• large amounts of energy are released in a very short amount of time
• many new fissions will follow each fission
• causing a runaway reaction which could lead to an explosion

Question 16

what are nuclear power stations powered by

Answer 16

nuclear reactors that create comntrolled reactions

Question 17

how is the energy from a reactor used to create steam

Answer 17

• energy released from the fission is transferred to the thermal energy stores of the moderator
• this is then transferred to the thermal energy stores of the coolant
• and then to the thermal energy store of the cold water passing through the boiler
• this causes the water to boil and energy to be transferred tot he kinetic energy store of the steam

Question 18

how is the steam induced from the energy of the reactor used to make electricity

Answer 18

• the kinetic energy from the steam is transferred to the kinetic energy store of the turbine
• and then to the kinetic energy store of the generator
• this energy is then transferred away from the generator electrically