Diapositive 1

1
Rouanet Maxime.The confining matrice how to
protect the world to radiations of high-activity
radioactive waste
2
INTRODUCTION
Confining matrices are materials that trap
radionuclides (cesium, strontium, actinides ...)
by incorporation and long-term stability in their
structure. The objective is to effectively
isolate these radionuclides from the biosphere
for many tens of thousands of years until their
decay. Our concern in particular radionuclides
from reprocessing of spent nuclear fuel (final
waste) .
3
SUMMARY
Introduction I/ Some definitions about the
radionuclides 1/Different kind of
radiation 2/High-activity radioactive waste II/
Confining Matrice 1/ Definition of a
confining matrice 2/Utilisation of glass
as confining matrice 3/Utilisation of
ceramic as confining matrice Conclusion
4
Some definitions about the radionuclides
-A radionuclide is an atom with an unstable
nucleus, which is a nucleus characterized by
excess energy which is available to be imparted
either to a newly-created radiation particle
within the nucleus, or else to an atomic electron
(see internal conversion). Radionuclides may
occur naturally, but can also be artificially
produced.
5
Some definitions about the radionuclides
- Alpha and beta radiation consist of tiny
particles, much smaller than an atom. They move
incredibly fast, perhaps thousands of kilometres
per second. - Gamma radiation is a sort of
invisible, very high-energy light. What are the
impact of this radiations on the human body ? -
Alpha particles cause lots of ionization in a
short distance - Beta goes further than alpha
but is less damaging - Gamma rays can pass
through lead but aren't very damaging ?
Ionization is very dangerous for the human body
so we have to isolate the nuclides even after
their utilisation.
6
Some definitions about the radionuclides
- High-activity radioactive waste - From the
power industry, they are the radioactive elements
not recoverable from the reprocessing of spent
fuel. - 2 kinds of product - The fission
products are body chemicals produced by the
fission of an element that stabilizes the form of
new atoms. These are the "ashes" of the nuclear
reaction, which constitute the ultimate nuclear
waste. ? Radiation gamma mainly. - During
irradiation in the reactor, the uranium atoms of
fuel can capture a neutron without undergoing
fission. He then forms minor actinides (neptunium
- Americium - Curium). The rating reflects the
minor fact that these elements are present in
much less than major actinides uranium and
plutonium. --gt Radiation alpha which is very
dangerous.
7
Confining Matrice
- What is a confining matrice ? - As we say in
the introduction, confining matrices are
materials that trap radionuclides (cesium,
strontium, actinides ...) by incorporation and
long-term stability in their structure. - It can
be considered to contain all final waste in
glasses (40 elements), or some radionuclides
individuals (those long-lived) from an enhanced
separation in glass-ceramic or ceramic matrix
specific more durable than glasses.
8
Confining Matrice
Utilisation of glass as confining matrice - Due
to a share of the coercion of long range order
and the multiplicity of possible reception sites
in their structure and secondly to their ease of
manufacture (casting merger), the oxide glasses
appear to be the best type of matrix for
containing nuclear waste is not separated.
9
Confining Matrice
Utilisation of ceramic as confining matrice In
the case of actinide wastes not separated or
separated but containing high amounts of
actinides, ceramic matrices are also prepared and
studied in the laboratory. Such matrices are
obtained by controlled heat treatment of glass
leading to the crystallization of actinide host
phases highly durable (zirconolite, apatite) in
the glass. In this case, the radionuclides
trapped in the crystal structure have a double
barrier containment by both the crystal and the
glass surrounding the crystals. This also allows,
because of its flexible structure, to accommodate
impurities or other elements present in the waste.
10
Conclusion
11
Thank you for your attention