Showing posts with label heavy water. Show all posts
Showing posts with label heavy water. Show all posts

PHYSICS DICTIONARY

 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z


<Prev>                   <Next> 

Hadrons

Kaons, Pions together with Baryons are placed in group of strongly interacting particles called Hadrons.


Half Life

Term used in nuclear physics. It represents the time it takes for a radioactive isotope for decaying its activity to half of its present value.


Half Wave Plate

Plate of uniaxial double refracting crystals such as quartz and calcite with optic axis parallel to their refracting surface, the thickness of which is such that it produces a path difference of λ/2 or a phase difference Π in between ordinary and extra ordinary waves.


Half-Wave Rectifier

Device which conducts current only during the positive half cycles of input ac supply. The negative half cycles of ac supply are suppressed i.e. during negative half cycles, no current is conducted and hence no voltage appears across load. Therefore, current always flows in one direction (DC) through load after every half cycle. 


Hall Effect

When a piece of semiconductor carrying a current is placed in a transverse magnetic field, an electric field is produced inside the conductor in a direction normal to both current and magnetic field.


Hall Mobility

Mobility of charge carriers under Hall Effect defined as product of hall coefficient and conductivity.


Hall Probe

Hall probe is a magnetic field sensor that passes electric current when the sensor is perpendicular to magnetic field. The stranger the magnetic field the more the current is converted to voltage. They are used for proximity switching, positioning etc.


Hamilton’s Principle

If a particle moves from one point to other in time interval t1 t t2, then the actual path it follows is the one for which action assume stationary value.


Hamiltonian Principle

The path actually traversed by a conservative, holonomic dynamical system from time t1 to t2 is one over which the integral of the lagrangian between limits t1 and t2 is stationary i.e., the time integral of lagrangian is extremum.


Hard Radiation

The term attributed to high energetic X-rays or gamma rays having high penetration power into almost all materials. 


Hardness

Mechanical property which is a measure of materials resistance to localized plastic deformation.


Harmonic Motion

 See simple harmonic motion.


Health Physics

It is branch of physics which deals with radiation protection of occupational workers in nuclear reactors and other radiation material handling centers.

 

Heat Capacity

The quantity of heat required to raise the temperature of the whole body there 1oC or 1oK is called heat capacity of body.


Heat Engine Law

Conversion of total heat energy into work is impossible.


Heat Engine

It is cyclic process in which heat is continuously converted into mechanical work. It has 3 main parts: source, sink and working substance. i) Source of heat at constant temperature to drive heat; ii) Sink at constant temperature, heat can be supplied without change in temperature. iii) Working substance: absorbs heat from source, converts part of the heat into mechanical work & rejects remaining heat to sink.


Heat

It is a form of energy (kinetic energy of molecules constituting the body) which produces sensation of warmth.

                                      (or)

It is energy that is transferred between a system and its environment because of a temperature difference that exists between them.


Heavy Water

Also referred as Deuterium oxide, is a type of water in which Deuterium (an isotope of Hydrogen) substitutes Hydrogen i.e. D2O. It has importance for having properties like Neutron moderation, high boiling point etc.


Heisenberg Forces

Type of nuclear force in which there is exchange of both spin and position coordinates.


Heisenberg’s Uncertainty Principle

Based on wave nature of matter, Heisenberg proposed a principle according to which, macroscopically it is possible to exactly measure position of moving particle and momentum associated with it but microscopically it is not possible. According to this principle, product of uncertainties in the measurement of position and momentum is of order of h/2π; where ‘h’ is Planck’s constant.


Helicity

Lee and yang suggested that the violation of parity in beta decay was direct consequence of longitudinal polarization of emitted electrons and Neutrons. The state and degree of longitudinal polarization of particles is represented by the term Helicity.


Heliocentric Theory

The theory proposed by Nicolas Copernicus, a polish astronomer. Heliocentric system first appeared in his book “De revolutionibus orbium coelestium”, “on the revolutions of heavenly bodies” which appeared in 1543. “Helios” in Greek means “sun”. Heliocentric means that the sun is at the center. As per this theory, sun remains at center and all the planets revolve round it. The moon is only celestial sphere in the system that revolves round the earth and together around sun. 

What is CANDU?



CANDU stands for "CANada Deuterium Uranium". 

It's a Canadian-designed power reactor of PHWR type (Pressurized Heavy Water Reactor) that uses heavy water (deuterium oxide) for moderator and coolant, and natural uranium for fuel.
CANDU-features and advantages
  • CANDU is the most efficient of all reactors in using uranium: it uses about 15% less uranium than a pressurized water reactor for each megawatt of electricity produced
  • Use of natural uranium widens the source of supply and makes fuel fabrication easier. Most countries can manufacture the relatively inexpensive fuel
  • There is no need for uranium enrichment facility
  • Fuel reprocessing is not needed, so costs, facilities and waste disposal associated with reprocessing are avoided
  • CANDU reactors can be fuelled with a number of other low-fissile content fuels, including spent fuel from light water reactors. This reduces dependency on uranium in the event of future supply shortages and price increase.
  • Heavy water (deuterium oxide) is highly efficient because of its low neutron absorption and affords the highest neutron economy of all commercial reactor systems. As a result chain reaction in the reactor is possible with natural uranium fuel
  • Heavy water used in CANDU reactors is readily available. It can be produced locally, using proven technology. Heavy water lasts beyond the life of the plant and can be re-used.
  • Reactor core comprising small diameter fuel channels rather that one large pressure vessel
  • Allows on-power refueling - extremely high capability factors are possible
  • The moveable fuel bundles in the pressure tubes allow maximum burn-up of all the fuel in the reactor core
  • Extends life expectancy of the reactor because major core components like fuel channels are accessible for repairs when needed.  
Courtesy: https://canteach.candu.org/

What is Heavy water?

Normal water is made of two Hydrogen atoms and one Oxygen atom. Hydrogen atom and Oxygen atoms are covalently bonded together. Normal water is designated by H2O.













Heavy water also has same molecular structure but Hydrogen atoms are replaced by isotopes of Hydrogen called 'Deuterium'. Standard hydrogen has one Proton in its nucleus (Relative Molecular Mass = 1), Deuterium has one Proton and  one Neutron in it nucleus, (Relative Molecular Mass = 2). Hence it is 'heavier' than normal hydrogen. This leads to the water being heavier.