This document provides information about heavy water, including its history, properties, production, and applications. Heavy water consists of deuterium and oxygen and was first isolated in 1931. It is produced through distillation processes that take advantage of its slightly different boiling point from regular water. Heavy water is used as a moderator in nuclear reactors, slowing neutrons so they can induce fission in uranium-238 as well as uranium-235. It also has applications as a tracer in biological and chemical reactions.

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3. Outline
 History
 Introduction
 Types of Nuclear Reactor
 Heavy Water Reactor
 Production of Heavy Water
 Properties of Heavy Water
 Purpose of Heavy Water
 Application of Heavy Water

4. History
 Who first isolated heavy water?
 Existence of Isotopes(Francis Aston in 1913)
 Rutherford suggested the existence of heavier Isotope of
hydrogen
 Harold Clayton Urey
 Found existence in 1931
 Urey succeeded in enriching samples of water in the heavier
isotope.
 The next step was to isolate pure heavy water.
 American Scientist Gilbert Newton Lewis with his student
Ronald T. MacDonald

5. So Lewis find out that heavy water had different properties to
ordinary water
H2O D2O
Freezing point (°C ) 0.00 3.81
Density of liquid (g/cm3) 0.9999 (277 K) 1.1056 (293 K)
Density of solid at m.p. 0.917 1.018
(g/cm3)
Temperature of maximum 3.98 11.2
density (°C)
pH (298K) 7.00 7.43

7. Introduction
 Heavy Water (D2O) (compound of Deuterium (D) and oxygen)
 This is also known as Deuterium Oxide.
 Deuterium (atomic mass 2) for normal hydrogen (H)
[due to presence of an extra neutron in the nucleus]
 Heavy Water resembles in its physical and chemical properties to
ordinary water. (light Water)
 But its nuclear properties makes it an extremely efficient material for
use as moderator in a nuclear reactor.

8. Types of Nuclear Reactors

9. Heavy Water Reactor
• The Heavy Water Reactor (HWR) concept allow the
use of natural uranium as a fuel without the need for its
enrichment, especially if uranium is available for mining or for
extraction as a by product of another industry such as gold mining .
• However, it needs the installation of a heavy water D2O production
capability, which is a much simpler to separate the light isotopes (D
from H) and the heavy isotopes (U235 from U238).
• HWRs have become a significant proportion of world reactor
installations, second only to the Light Water Reactors (LWRs)

10.  The HWR concept is primarily represented by the CANDU design
which is an acronym for Canada Deuterium Uranium.
 The CANDU system uses pressurized heavy water D2O as moderator
and coolant and natural uranium as fuel in the form of uranium
dioxide UO2.

12. Production of Heavy water
 The production of heavy water in significant amounts requires a
technical infrastructure, but one which has similarities to ammonia
production, alcohol distillation, and other common industrial
processes.
 It is possible to take advantage of the different boiling points of heavy
water (101.4 °C) and normal water (100 °C) or the difference in boiling
points between deuterium (-249.7 °C) and hydrogen (-252.5 °C).
 However, because of the low abundance of deuterium, an enormous
amount of water would have to be boiled to obtain useful amounts of
deuterium.
 Because of the high heat of vaporization of water, this process would
use enormous quantities of fuel or electricity.

13. Properties of Heavy Water
molecular formula 2H2O/ D2O
molar mass 20.0276 g/mol
exact mass 20.023118178 g/mol
appearance pale blue transparent liquid
odor Odorless
melting point 3.8°C
molecular weight 20.0276 g/mol
vapor pressure 16.4 mm Hg
refractive index 1.328
viscosity at 25°C 0.001095 Pa s
specific heat of fusion 0.3096 kj/g

14. Purpose of using Heavy Water in
Nuclear Reactor
 Heavy water is used as a moderator.
 It is used to slow the neutrons being directed at the fissionable
material, by means of the molecules of the moderator physically
impacting the incoming neutrons and absorbing some of the kinetic
energy they posses, thus slowing them down.
 The reason that the neutrons have to be slowed is that most fissionable
materials are more likely to absorb thermal neutrons (2.2km/s) than
fast neutrons (14,000km/s).
 This means that when heavy water is used as a moderator, enough
neutrons get through that even with very low levels of U-235 (even the
very low levels found in natural uranium), criticality can be
maintained, and power is produced.

15. Application of Heavy Water
 Heavy water is used as tracer in the study of reactions occurring in living
organisms and other chemical reactions.
 It has been used for the preparation of deuterium.
 Chemists can use D2O as a solvent for Nuclear Magnetic Resonance
spectra.