Brody Brett Tahmid Questions Fusion and Fission [24 marks]
1. [Maximum mark: 1] SPM.1A.SL.TZ0.24
Three statements about a nuclear fission reactor are:
I. The heat exchanger transfers energy from the fuel rods to the
moderator.
II. The control rods must be good absorbers of neutrons.
III. The moderator must slow neutrons down.
Which statements about the reactor are correct?
A. I and II only
B. I and III only
C. II and III only
D. I, II and III [1]
Markscheme
C
2. [Maximum mark: 1] SPM.1A.HL.TZ0.36
Three statements about a nuclear fission reactor are:
I. The heat exchanger transfers energy from the fuel rods to the
moderator.
II. The control rods must be good absorbers of neutrons.
III. The moderator must slow neutrons down.
Which statements about the reactor are correct?
A. I and II only
B. I and III only
C. II and III only
D. I, II and III [1]
Markscheme
C
3. [Maximum mark: 1] EXE.1A.SL.TZ0.19
Fuel rods in a nuclear fission reactor contain uranium isotopes U-235
and U-238. Which process taking place in the reactor contributes most
significantly to the formation of radioactive waste products?
A. alpha decay of U-235
B. alpha decay of U-238
C. neutron-induced fission of U-235
D. neutron-induced transmutation of U-238 to plutonium-239 [1]
Markscheme
C
4. [Maximum mark: 1] EXE.1A.SL.TZ0.20
Three statements about the products of nuclear fission are:
I. some of them are chemically toxic
II. they have a wide range of half-lives
III. they release additional energy when removed from the reactor
Which statements are correct?
A. I and II only
B. I and III only
C. II and III only
D. I, II and III [1]
Markscheme
D
5. [Maximum mark: 1] EXE.1A.SL.TZ0.21
When removed from a nuclear reactor, used nuclear fuel rods are often
stored for several years in a tank of liquid.
Three possible reasons for this are
I. to shield workers from radiation emitted from the fuel rods
II. to dissolve the unused fuel from the rods
III. to cool the rods
Which statements are correct?
A. I and II only
B. I and III only
C. II and III only
D. I II and III [1]
Markscheme
B
6. [Maximum mark: 1] EXE.1A.SL.TZ0.22
Used fuel rods are stored in water after removal from a nuclear reactor.
The reason for this is that the water
A. absorbs the gamma radiation which is emitted by the used fuel
B. cools the used fuel which is still transferring energy
C. boils to steam which can then rotate a turbine
D. reacts chemically with the fuel which reduces the activity [1]
Markscheme
B
7. [Maximum mark: 1] 22N.1A.SL.TZ0.25
A fusion reaction of one nucleus of hydrogen-2 and one nucleus of
hydrogen-3 converts 0.019 u to energy. A fission reaction of one
nucleus of uranium-235 converts a mass of 0.190 u to energy.
specif ic energy of this f usion of hydrogen
What is the ratio specif ic energy of this f ission of uranium
?
A. 0.1
B. 0.2
C. 5
D. 10 [1]
Markscheme
C
8. [Maximum mark: 1] 22M.1A.SL.TZ2.24
A neutron is absorbed by a nucleus of uranium-235(23592
U). One
possible outcome is the production of two nuclides, barium-144
Ba) and krypton-89( Kr).
144 89
(
56 36
How many neutrons are released in this reaction?
A. 0
B. 1
C. 2
D. 3 [1]
Markscheme
D
9. [Maximum mark: 1] 21M.1A.SL.TZ2.22
During the nuclear fission of nucleus X into nucleus Y and nucleus Z,
energy is released. The binding energies per nucleon of X, Y and Z are
BX , BY and BZ respectively. What is true about the binding energy
per nucleon of X, Y and Z?
A. BY > BX and BZ > BX
B. BX = BY and BX = BZ
C. BX > BY and BX > BZ
D. BX = BY + BZ [1]
Markscheme
10. [Maximum mark: 1] 20N.1A.SL.TZ0.24
What are the principal roles of a moderator and of a control rod in a
thermal nuclear reactor?
[1]
Markscheme
C
11. [Maximum mark: 1] 19N.1A.SL.TZ0.29
What is the function of the moderator in a thermal nuclear fission
reactor?
A. To decrease the kinetic energy of neutrons emitted from fission
reactions
B. To increase the kinetic energy of neutrons emitted from fission
reactions
C. To decrease the overall number of neutrons available for fission
D. To increase the overall number of neutrons available for fission [1]
Markscheme
A
12. [Maximum mark: 1] 19M.1A.SL.TZ2.28
A neutron collides head-on with a stationary atom in the moderator of
a nuclear power station. The kinetic energy of the neutron changes as a
result. There is also a change in the probability that this neutron can
cause nuclear fission.
What are these changes?
[1]
Markscheme
B
13. [Maximum mark: 7] EXE.2.SL.TZ0.19
(a) Compare and contrast spontaneous and neutron-induced
nuclear fission. [2]
Markscheme
Spontaneous fission occurs with no external influence, neutron-induced
fission requires an interaction with a neutron «of appropriate energy» ✓
Both result in the release of energy
OR
both have a large number of possible pairs of products ✓
(b) Every neutron-induced fission reaction of uranium-235 releases
an energy of about 200 MeV. A nuclear power station transfers
an energy of about 2.4 GJ per second.
Determine the mass of uranium-235 that undergoes fission in
one day in this power station. [3]
Markscheme
9
2.4×10 ×60×60×24
Fissions per day = 6 −19
«= 24
6. 5 × 10 »✓
200×10 ×1.6×10
24
6.5×10
Mass of uranium = 23
× 0. 235 ✓
6.05×10
2.5 «kg» ✓
(c) State two properties of the products of nuclear fission due to
which the spent nuclear fuel needs to be kept safe. [2]
Markscheme
Have relatively short half-lives / high activity ✓
Their decay products are «usually» also radioactive ✓
Volatile / chemically active ✓
Biologically active / easily absorbed by living matter ✓
14. [Maximum mark: 5] EXE.2.SL.TZ0.20
(a) State one source of the radioactive waste products from nuclear
fission reactions. [1]
Markscheme
Fission fragments from the fuel rods
OR activated materials in (e.g.) fuel rod casings
OR nuclei formed by neutron activation from U-235
OR stated products, e.g. Pu, U-236 etc. ✓
(b) Outline how this waste is treated after it has been removed
from the fission reactor. [4]
Markscheme
Waste (fuel rod) is placed in cooling ponds for a number of years ✓
After most active products have decayed the uranium is separated to be
recycled/reprocessed ✓
The remaining highly active waste is vitrified / made into a solid form ✓
And stored (deep) underground ✓
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