2014 MCQ

Question 1

Name three two-phase regimes that occur in vertical two-phase flow?

Answer 1

Bubble flow
Slug flow
Annular flow

Question 2

What is the typical enrichment for a PWR fuel?

Answer 2

5%

Question 3

What would happen to a sub-critical satellite nuclear reactor after it plunges into seawater?

Answer 3

Neutron reflection by the seawater would make the reactor more reactive

Question 4

What would be the effect on the thermal efficiency of a plant if the fuel enrichment of AGR were increased?

Answer 4

Little changed

Question 5

A new rib design for an AGR increases its heat transfer coefficient. If nothing else is changed, as a result:

Answer 5

Cladding temperature will be reduced.

Question 6

Order the following in decreasing energy release of U235:

Neutron kinetic energy
Fission fragment kinetic energy
Prompt gamma rays
Fission product radiation

Answer 6

Fission fragment kinetic energy
Fission product radiation
Prompt gamma rays
Neutron kinetic energy

Question 7

Wigner energy is

Answer 7

Neutron induced strain energy in the hexagonal lattice of graphite

Question 8

What is the fuel for Magnox?

Answer 8

U-metal

Question 9

What is the moderator and coolant for AGR?

Answer 9

Graphite
CO2

Question 10

What is the moderator and coolant for Magnox?

Answer 10

Graphite
Coolant

Question 11

List the following in ascending order of CO2 release per unit of electricity:

Coal
Nuclear
Oil
Gas

Answer 11

Nuclear
Gas
Oil
Coal

Question 12

Why are delayed neutrons so important in reactor control?

Answer 12

They increase the average neutron lifetime

Question 13

What does the microscopic cross section provide?

Answer 13

The properties of an individual nucleus

Question 14

A sub-critical multiplying assembly can ________ the number of neutrons beyond the number introduced

Answer 14

increase

Question 15

Do fission neutrons have a higher or lower KE than fission fragments?

Answer 15

Lower

Question 16

What charge are fission neutrons?

Answer 16

Uncharged

Question 17

The ‘activation energy’ to permit fission comes largely from

Answer 17

the binding energy of the neutron that causes the fission

Question 18

What does the absorption cross section comprise of?

Answer 18

absorption cross section = capture cross section + fission cross section

Question 19

What is the reactivity of a sub-prompt-critical nuclear reactor?

Answer 19

N/A

Question 20

Following a period of normal full power operation, a reactor suddenly loses coolant to the extent that the fuel rod may be considered to be adiabatic, and the fission reaction ceases. As a result the fuel pellet edge temperature will

Answer 20

Rise.

Question 21

Fuel burnup in a PWR is typically first limited because:

Answer 21

Fission product production and release to the plenum threatens pin integrity

Question 22

What does the second and fourth term in the differential equation give?

Answer 22

(ii) local fission neutron production rate
(iv) local divergence of neutron current

Question 23

Name four material effects as a consequence of radiation damage?

Answer 23

embrittlement
Phase changes
creep
hardening

Question 24

Unit for neutron current?

Answer 24

neutrons per square metre per second

Question 25

What moderator is used in a gas cooled fast breeder reactor?

Answer 25

No moderator

Question 26

What coolant is used in CANDU?

Answer 26

Heavy water

Question 27

List the following in increasing order of operating pressure: CANDU AGR PWR RBMK

Answer 27

AGR RBMK CANDU PWR

Question 28

A fast reactor typically requires a fissile concentration of plutonium around ___

Answer 28

20%

Question 29

List the following in increasing coolant heat transfer coeffieicnt: Water Liquid sodium High pressure CO2 Boiling water

Answer 29

High pressure CO2 water liquid sodium boiling water

Question 30

True or false: There is a decrease in the number of Frenkel defects as a result of radiation damage.

Answer 30

False

Question 31

Which gas is used to pressurize reactor fuel pins?

Answer 31

Helium

Question 32

Why is this statement inaccurate: In a fast breeder reactor fuel is converted into energy rapidly, resulting in a shortened fuel cycle.

Answer 32

While fast breeder reactors are designed to produce energy more efficiently by using fast neutrons to convert fertile material (like uranium-238) into fissile material (like plutonium-239), they don't necessarily convert fuel into energy more rapidly.

Question 33

During a small break loss of coolant accident (LOCA) in a PWR, the core can remain uncovered for a significant time because ____

Answer 33

the reactor vessel remains pressurised and inhibits ingress of ECCS water

Question 34

As the size of nuclei increases, the neutron to proton ratio

Answer 34

increases (gets larger)