Nuclear Energy Revision Sheet

Question I

Identify the NPP parts by writing the number of the correct power plant part

in the blank. Select your answers from the list provided below.

1 Reactor 2 Steam

generator

3 Primary

water loop

4 Control

rods

5 Turbine–

generator

6 Secondary

water loop

7 Cooling

water

8 Transmission

lines

9 Nuclear

fuel

10 Cooling

tower

1

1

Condenser 1

2

Pressurizer 1

3

Containment

building

Question II [29 marks]

1) Fill in the table below with the required information:

Nuclear Reactor Fuel used Moderator Coolant

Boiling water reactors (BWR)

Enriched UO2

Water

Water

Pressurized

water reactors (PWR) Enriched UO2

Water

Water

Pressurized

heavy water

reactors (PHWR)-CANDU

Natural UO2

Heavy water

Light or heavy water

Advanced power reactors

(APR1400). Enriched U-235

Water

Water

Gas-cooled

reactor (GCR) Natural U/

Enriched UO2

Graphite

CO2 or Helium

2) What are the three grades of enriched Uranium and where they are used?

1. Slightly enriched uranium: has a U-235 concentration of 0.9% to 2%

Usage: is used in some heavy water reactors.

2. Low enriched uranium: has a lower than 20% concentration of U-235

Usage: For use in commercial light water reactors

3. Highly enriched uranium: has a greater than 20% concentration of U-

235.

Usage: Weapon grade uranium

3) Match the nuclear reactor or the power plant type in column (A) with the correct figure in column (B). Write your answer in the answer box provided

Column A 1 2 3 4 5 6 7 8

Column B B C A E G H D F

No Column (A) Letter Column ( B )

1

Boiling water reactors (BWR)

A

2

Pressurized water reactors

(PWR)

B

3

Pressurized heavy water

reactors (PHWR)-CANDU.

C

4

Advanced power reactors (APR1400).

D

5

Gas-cooled reactor (GCR)

E

6

Advanced Gas-cooled Reactor

(AGR)

F

7

Fast breeder reactor (FBR)

G

8

Steam power plant

H

Question III

The figure shown below for the pressurized water reactor, name the

indicated parts. Select your answers from the list provided below.

Condenser Primary loop Secondary loop

Tertiary loop

Steam Generator

Reactor coolant

pump

Reactor Pressure

Vessel

Condenser coolant pump

Turbine Electricity Generator

Fill in the indicated parts. Write

your answers in the table below.

Number Name (select from the list)

1 Reactor Pressure Vessel

2 Steam Generator

3 Primary loop

4 Turbine

5 Electricity Generator

6 Tertiary loop

7 Condenser coolant pump

8 Condenser

9 Primary loop

10 Reactor coolant pump

Question IV

1) Nuclear reactors can be classified according to their types, moderators and use.

Classify the nuclear reactors according to their usage and give examples for each one

as specified below.

Nuclear reactor usage Examples

Electricity production I. Boiling water nuclear reactor.

II. Pressurized water nuclear reactor.

Propulsion I. Nuclear marine propulsion.

II. Various proposed forms of rocket propulsion.

Heat production reactors Any two of the following:

I. Desalination plants.

II. Heat for domestic use and industrial heating.

III. Hydrogen production for use of hydrogen

economy.

Research Reactors I. Research and training material testing.

II. Production of radio isotopes for medicine and

industry.

Nuclear Fuel Production

Reactors I. The breeder reactors

II. Reactors used to produce weapon grade

plutonium

2) Differentiate between the function of the neutron poisons and the function

of neutrons moderators.

Neutron Poisons

( Absorbers)

Using neutron poisons (neutron absorbers) which absorb

excess neutrons to control the nuclear reaction.

Neutron Moderators

Using neutron moderators, which reduce the velocity of

fast neutrons, thereby turning them into thermal neutrons

which are more likely to be absorbed by other nuclei.

3) Referring to the figure shown below, describe how the steam pressure

could be reduced during accidents which cause reactor coolant leakage.

Answer:

During accidents the reactor coolant

converts to steam in the drywell and

pressure builds up quickly.

Vent pipes or tubes from the drywell

Direct the steam below the water level

in the wetwell.

This condenses the steam and reduces

the pressure

Question V

Answer the following questions:

A. For a pressurized water reactor, the containment building encloses

the following components: marks each)

I. The steam generator.

II. The entire reactor building.

III. The pressurizer.

B. There are three different containment building designs based on their

shapes, these are:

I. Can design

II. Spherical Design

III. Combined design( Can and Spherical)

C. Control rods are used to control the chain reaction in the nuclear reactor, beside that, the control system includes a number of devices

,these are:

I. Sensing elements that measure the number of neutrons.

II. Other devices to regulate the position of the control rods.

Question VI

1) Given the following reaction:

a) State the type of the above reaction.

Nuclear Fusion

Describe the reaction.

Nuclear fusion involves two atomic nuclei (Deuterium and Tritium) joining To make a large nucleus (Helium).

Energy and fast neutrons are released when this happens.

b) State two disadvantages of utilizing the heat generated by this

reaction in electrical power generation.

Any two of the following:

1. Fusion reactions can produce fast neutrons, a highly energetic and

dangerous form of nuclear reaction.

2. This requires replacing the shielding material periodically which

makes

the operation of the fusion power plant expensive and impractical.

3. Lithium can be used to slowdown these neutrons, but lithium is

chemically reactive and rare so its use is not practical. 2) In many countries, the fuel assemblies, after being in the reactor for 3 to

6 years, are stored underwater for 10 to 20 years. Suggest two reasons for using water as storage medium for spent fuel.

A. It serves as a shield to reduce the radiation levels that people

working above may be exposed to.

B. It cools the fuel assemblies that continue to produce heat (called

decay heat) for some time after removal.

3) Match the nuclear reactor or the power plant type in column (A) with the

correct figure in column (B). Write your answer in the answer box provided

Column A 1 2 3 4 5 6 7 8

Column B B C A E G H D F

No Column (A) Letter Column ( B )

1

Boiling water reactors (BWR)

A

2

Pressurized water reactors (PWR)

B

3

Pressurized heavy water reactors (PHWR)-CANDU.

C

4

Advanced power reactors

(APR1400).

D

5

Gas-cooled reactor (GCR)

E

6

Advanced Gas-cooled Reactor

(AGR)

F

7

Fast breeder reactor (FBR)

G

8

Steam power plant

H