61. The size of the reactor is said to be critical when
(a) chain reaction can be initiated
(b) it becomes uncontrollable
(c) it explodes
(d) it produces no power
(e) it produces tremendous power
Ans: a
62. When a reactor becomes critical, then the production of neutrons is
(a) infinite
(b) zero
(c) exactly balanced by the loss of neutrons through leakage
(d) initiated
(e) stopped
Ans: c
63. In the breeder reactors the generation of new fissionable atom is
(a) at the lower rate than the consumption
(b) at a higher rate than the constuption
(c) at an equal rate of the consumption
(d) depends on other considerations
(e) unpredictable
Ans: b
64. The energy produced by a thermal reactor of same size as a breeder reactor is
(a) almost same
(b) slightly more
(c) slightly less
(d) much less
(e) much more
Ans: d
65. Reactors designed for propulsion applications are designed for
(a) natural uranium
(b) enriched uranium
(c) pure uranium
(d) any type of uranium
(e) none of the above
Ans: b
66. Superheated steam is generated in following reactor
(a) boiling water
(b) gas cooled
(c) pressurized water
(d) all of the above
(e) none of the above
Ans: b
67. Solid- fuel for nuclear reactions may be fabricated into various small shapes such as
(a) plates
(b) pallets
(c) pins
(d) any one of the above
(e) none of the above
Ans: d
68. Which of the following is more appropriate for a moderator. One which
(a) does not absorb neutrons
(b) absorbs neutrons
(c) accelerates neutrons
(d) eats up neutrons
(e) regenerates neutrons
Ans: a
69. A fission chain reaction in uranium can be developed by
(a) slowing down fast neutrons so that Uz fission continues by slow motion neutrons
(b) accelerating fast neutrons
(c) absorbing all neutrons
(d) using moderator
(e) enriching U235
Ans: a
70. In triggering fission, the following types of neutrons are desirable
(a) fast moving
(b) slow moving
(c) critical neutrons
(d) neutrons at rest
(e) none of the above
Ans: b
71. Effective moderators are those materials which contain
(a) light weight atoms
(b) heavy weight atoms
(c) critical atoms
(d) zero weight atoms
(e) there is no such criterion
Ans: a
72. In a fission process, maximum %age of energy is released as
(a) kinetic energy of neutrons
(b) kinetic energy of fission products
(c) instantaneous release of gamma rays
(d) gradual radioactive decay of fission products
(e) none of the above
Ans: b
73. The following present serious difficulty in designing reactor shield
(a) alpha particles
(b) beta particles
(c) thermal neutrons
(d) fast neutrons and gamma rays
(e) none of the above
Ans: d
74. In nuclear fission
(a) the original elements change into completely different elements
(b) the electrons of the element change
(c) the molecules rearrange themselves to form other molecules
(d) none of the above
Ans: a
75. In order to have constant claim reaction to produce a constant rate of heat output, the value of ratio of the number of neutrons in one generation to the number of neutrons in the immediately preceding generation must be
(a) greater than 1.0
(b) less than 1.0
(c) equal to zero
(c) equal to 1.0
(e) equal to infinity
Ans: d
75. Each fission of U235 produces following number of fast neutrons per fission
(a) 1 neutron
(b) 1 neutrons
(c) 1 2 neutrons
(d) 2 neutrons
(e) infinite
Ans: d
76. A fast breeder reactor uses following as fuel
(a) enriched uranium
(b) plutonium
(c) thorium
(d) U235
(e) natural uranium
Ans: d
77. A boiling water reactor uses following as fuel
(a) enriched uranium
(b) plutonium
(c) thorium
(d) U
(e) natural uranium
Ans: a
78. A fast breeder reactor
(a) uses graphite rods as moderator
(b) has powerful moderator
(c) has no moderator
(d) uses ferrite material as moderator
(e) uses pressurized water as moderator
Ans: c
79. Artificial radioactive isotopes find application in
(a) power generation
(b) nucleonic devices
(c) nuclear fission
(d) nuclear fusion
(e) medical field
Ans: e
80. A fast breeder reactor uses
(a) 90% U-235
(b) U-238
(c) U-235
(d) Pu-239
(e) U-239
Ans: a
81. Half life of a radioactive isotope corresponds to the time required for half of the following to decay
(a) electrons
(b) protons
(c) neutrons
(d) nulceus
(e) atom
Ans: e
82. Pressurized water reactor is designed
(a) for boiling pi water in the core
(b) to use liquid sodium metal as coolant
(c) to use intermediate coolant
(d) to prevent the water coolant from boiling in the core
(e) to eliminate the coolant loop of the pressurized water
Ans: d
83. The coolant used in boiling water reactor is
(a) C02
(b) pressurized water
(c) mixture of water and steam
(d) liquid metal
(e) mercury
Ans: c
84. In boiling water reactor, moderator is
(a) coolant itself
(b) ferrite rod
(c) graphite rod
(d) liquid sodium metal
(e) blanket of thorium
Ans: a
85. The most practical fuel for a thermonuclear reactor, both from economical and nuclear consideration is
(a) plutonium
(b) uranium
(c) deuterium
(d) thorium
(e) lithium
Ans: c
86. The efficiency of a nuclear power plant in comparison to conventional and nuclear consideration is
(a) higher cost of nuclear fuel
(b) high initial cost
(c) high heat rejection in condenser
(d) lower temperature and pressure conditions
(e) nuclear hazard risk
Ans: d
87. The presence of reflector in nuclear power plants results in
(a) increased production of neutrons
(b) complete absorption of neutrons
(c) controlled production of neutrons
(d) decreased leakage of neutrons
(e) decrease of speed of neutrons
Ans: d
88. The fuel needed, with reflector in nuclear power plant, in order to generate sufficient neutrons to sustain a chain reaction, would be
(a) more
(b) less
(c) same
(d) zero
(e) negative, i.e. fuel would be generated
Ans: b