SSC General Science & Technology Sample Paper NCERT Sample Paper-4

  • question_answer
    A nuclear unit becoming critical means

    A)  It is generating power to rated capacity

    B)  It is capable of generating much more than rated capacity.

    C)  There is danger of nuclear spread

    D)  Chain reaction that causes automatic splitting of the fuel nuclei has been established.

    Correct Answer: D

    Solution :

    [d] When the atom-splitting reactor of a nuclear power plant is operating normally it is said to be "critical" or in a state of "criticality." Using the term "criticality" may seem counter-intuitive as a way to describe normalcy. The word often describes situations with potential for disaster. Nevertheless, in the context of nuclear power, "criticality" indicates that a reactor is operating safely. Criticality is a balanced state. Nuclear reactors use uranium fuel rods to create energy through fission. Fission is the process of splitting the nuclei of uranium atoms to release neutrons that in him split more atoms, releasing more neutrons. Criticality means that a reactor is controlling a sustained fission chain reaction where each fission event releases a sufficient number of neutrons to maintain an ongoing series of reactions. In the balanced state of criticality, fuel rods inside a nuclear reactor are producing and losing a constant number of neutrons, and the nuclear energy system is stable. Fission produces a great deal of energy in the form of very high heat and radiation. That's why reactors are housed in structures sealed under thick metal-reinforced concrete domes. Power plants harness this energy and heat to produce steam to drive generators that produce electricity.

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