(a)(i)One roentgen is defined as the quantity of radioactive substance which produces a charge of `2.58xx10^(-4)`coulomb in 1 kg of air under standard conditions of pressure, temperature and humidity.
(ii)A Nuclear reactor is a device in which the nuclear fission reaction takes place in a self-sustained and controlled manner to produce electricity.
Components of a Nuclear Reactor
The essential components of a nuclear reactor are (i) fuel (ii) moderator (iii) control rod (iv) coolant and (v) protection wall.
(i) Fuel: A fissile material is used as the fuel. The commonly used fuel material is uranium
(ii) Moderator: A moderator is used to slow down the high energy neutrons to provide slow neutrons. Graphite and heavy water are the commonly used moderators.
(iii)Control rod: Control rods are used to control the number of neutrons in order to have sustained chain reaction. Mostly boron or cadmium rods are used as control rods. They absorb the neutrons.
(iv)Coolant: A coolant is used to remove the heat produced in the reactor core, to produce steam. This steam is used to run a turbine in order to produce electricity. Water, air and helium are some of the coolants.
(v)Protection wall: A thick concrete lead wall is built around the nuclear reactor in order to prevent the harmful radiations from escaping into the environment.
