41. Which one of the following fuels is used by the slow thermal nuclear reactors for power generation?
(a) U235
(b) U238
(c) Th232
(d) PU239
Answer: (a) U235
42. Consider the following statements regarding the nuclear power plants:
- A thermal reactor needs a moderator material.
- In a nuclear reactor, multiplication factor is kept almost equal to one. 3. Nuclear power plants are used as peak load plants only.
Which of the statements given above are correct?
(a) 1, 2 and 3.
(b) 1 and 2 only.
(c) 2 and 3 only.
(d) 1 and 3 only.
Answer: (b) 1 and 2 only.
43. In a thermal nuclear reactor
- the purpose of moderator is to slowdown fast neutrons produced due to fission.
- the moderator material must have low molecular weight.
- ordinary water can be used as moderator with natural uranium as fuel.
- the multiplication factor is kept slightly greater than unity during its normal functioning.
Of these statements
(a) 1 and 3 are correct.
(b) 3 and 4 are correct.
(c) 1, 2 and 3 are correct.
(d) 1, 2 and 4 are correct.
Answer: (d) 1, 2 and 4 are correct.
44. A heavy water reactor
(a) has higher neutron flux which can be produced at a given power level.
(b) requires less time to shutdown than in the case of graphite because of photo-neutron production.
(c) is not stable.
(d) cannot use natural uranium as fuel.
Answer: (a) has higher neutron flux which can be produced at a given power level.
45. The conversion ratio of a breeder reactor is
(a) less than unity.
(b) more than unity.
(c) equal to unity.
(d) none of the above.
Answer: (b) more than unity.
46. Fast breed reactors are best suited for India owing to
(a) large thorium deposits.
(b) large plutonium deposits.
(c) large uranium deposits.
(d) none of the above.
Answer: (a) large thorium deposits.
47. Gas cooled reactor
(a) uses CO2 or helium as coolant and graphite as the moderator.
(b) uses coolant at pressure of 14 – 28 kg/cm2 and at temperature of 700 – 800°C.
(c) uses heavy water as coolant as well as moderator.
(d) both (a) and (b).
Answer: (d) both (a) and (b).
48. A sodium graphite reactor uses
(a) sodium as moderator and graphite as coolant.
(b) sodium as coolant and graphite as moderator.
(c) a mixture of sodium and graphite as coolant.
(d) a mixture of sodium and graphite as moderator.
Answer: (b) sodium as coolant and graphite as moderator.
49. The economic prospects of nuclear power generation in India to a great extent depends on successful development of
(a) fast reactors using enriched uranium as the fuel thus avoiding import of heavy water.
(b) thermal reactors using natural uranium as the fuel and avoiding import of enriched uranium.
(c) breeder reactors using thorium as blanket material and U233 as the fuel.
(d) reactor using plutonium as the fuel, natural uranium as blanket and liquid sodium as the coolant.
Answer: (c) breeder reactors using thorium as blanket material and U233 as the fuel.
50. Compared to steam engines, the internal combustion engines have
(a) much higher thermal efficiency.
(b) almost same thermal efficiency as that of steam engines.
(c) much lower thermal efficiency.
(d) can have lower or higher thermal efficiency.
Answer: (a) much higher thermal efficiency.
51. The lubrication cost in a diesel power plant is
(a) high.
(b) moderate.
(c) low.
Answer: (a) high.
52. Which of the following statements is True ?
(a) Diesel power plants employ only four stroke engines.
(b) Space requirement for diesel power plants in more than that for a conventional steam power plant.
(c) A two stroke engine develops more power for the same speed and piston displacement.
(d) The specific fuel consumption of a diesel power plant decreases with the decrease in load.
Answer: (c) A two stroke engine develops more power for the same speed and piston displacement.
53. The diesel engines are available in sizes from
(a) 0 – 5 kW
(b) 5 – 50 kW
(c) 75 – 3,750 kW
(d) above 10,000 kW
Answer: (c) 75 – 3,750 kW
54. The compression ratio in diesel engine may be in the range of
(a) 15 – 20
(b) 10 – 15
(c) 5 – 10
(d) 3 – 5
Answer: (a) 15 – 20
55. Air standard efficiency of a diesel engine depends upon
(a) expansion ratio.
(b) compression ratio.
(c) fuel used.
(d) none of the above.
Answer: (b) compression ratio.
56. In case of diesel engines, the thermal efficiency is in the range of
(a) 10 – 20 percent.
(b) 20 – 30 percent.
(c) 30 – 40 percent.
(d) 40 – 50 percent.
Answer: (c) 30 – 40 percent.
57. In ideal diesel cycle the working substance is
(a) air.
(b) diesel.
(c) mixture of air and diesel.
(d) any combustible gas.
Answer: (a) air.
58. Air-fuel ratio required for combustion in diesel engine is around
(a) 20 : 1
(b) 15 : 1
(c) 10 : 1
(d) 5 : 1
Answer: (b) 15 : 1
59. In a diesel engine fuel is injected at a pressure of
(a) 20 – 25 kg/cm2
(b) 50 – 75 kg/cm2
(c) 90 – 130 kg/cm2
(d) 130 – 160 kg/cm2
Answer: (c) 90 – 130 kg/cm2
60. Maximum temperature developed in a diesel engine cylinder is in the range of
(a) 2,000 – 2,500°C
(b) 1,500 – 2,000°C
(c) 1,000 – 1,500°C
(d) 800 – 1,000°C
Answer: (a) 2,000 – 2,500°C
61. In a diesel engine, the heat lost to the cooling water is about
(a) 50%
(b) 30%
(c) 20%
(d) 15%
Answer: (b) 30%