General terms in nuclear safety and security sphere. nuclear fuel cycle (nfc) приложение 1

General terms in nuclear safety and security sphere.

Nuclear fuel cycle (NFC)

Ekaterina Sviridova

Purpose and objectivesDevelopment of YOUR ability to use English in YOUR professional sphere.

You will:• obtain information from foreign resources;• use computer in scientific research; • work in team;• analyze problems and risks in professional sphere;• ready to make a decision in difficult situation;• fluently discuss in English.

Define following terms:

•Proton•Attractive force•Half-life

Define following terms:

•Nuclei•Binding energy•Activity

Define following terms:

•Neutron• Isotope•Absorption

The history of nuclear physics

It can be divided into three periods:• The first begins with the discovery radioactivity of the nucleus

and ends in 1939 with the discovery of fission.• The second period from 1947 to 1969 saw the development

of nuclear spectroscopy and of nuclear models. • The third period from 1970 to nowadays.

The main stages of this first period of nuclear physics are the following:

• 1868 Mendeleev’s periodic classification of the elements.• 1895 Discovery of X-rays by Roentgen.• 1896 Discovery of radioactivity by Becquerel.• 1897 Identification of the electron by J.J. Thomson.• 1898 Separation of the elements polonium and radium by

Pierre and Marie Curie.• 1908 Measurement of the charge +2 of the α particle by

Geiger and Rutherford.• 1911 Discovery of the nucleus by Rutherford; “planetary”

model of the atom.

• 1913 Theory of atomic spectra by Niels Bohr.• 1914 Measurement of the mass of the α particle by Robinson

and Rutherford.• 1924–1928 Quantum theory (de Broglie, Schr¨odinger,

Heisenberg, Born, Dirac).• 1928 Theory of barrier penetration by quantum tunneling,

application to α radioactivity, by Gamow, Gurney and Condon.• 1929–1932 First nuclear reactions with the electrostatic

accelerator of Cockcroft and Walton and the cyclotron of Lawrence.• 1930–1933 Neutrino proposed by Pauli and named by Fermi in

his theory of beta decay.• 1932 Identification of the neutron by Chadwick.

• 1934 Discovery of artificial radioactivity by F. and I. Joliot-Curie.• 1934 Discovery of neutron capture by Fermi. • 1935 Liquid-drop model and compound-nucleus model of N.

Bohr. • 1935 Semi-empirical mass formula of Bethe and Weizsacker.• 1938 Discovery of fission by Hahn and Strassman.• 1938 Bethe and Weizsacker propose that stellar energy

comes from thermonuclear fusion reactions.• 1939 Theoretical interpretation of fission by Meitner, Bohr and

Wheeler.• 1946 Gamow develops the theory of cosmological

nucleosynthesis.

The main stages of the second period of nuclear physics are the following:

• 1953 Salpeter discovers the fundamental solar fusion reaction of two protons into deuteron.• 1957 Theory of stellar nucleosynthesis by Burbidge, Burbidge,

Fowler and Hoyle. • 1960– Detection of solar neutrinos

Remember some nuclear discoveries that take place in the third period

Half-life (t1⁄2)

is the amount of time required for the amount of something to fall to half its initial value. The term is very commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay, but it is also used more generally for discussing any type of exponential decay.

The original term, dating to Ernest Rutherford's discovery of the principle in 1907, was "half-life period", which was shortened to "half-life" in the early 1950s.

Half-life (t1⁄2)

Half-life is used to describe a quantity undergoing exponential decay, and is constant over the lifetime of the decaying quantity. It is a characteristic unit for the exponential decay equation. The term "half-life" may generically be used to refer to any period of time in which a quantity falls by half, even if the decay is not exponential. The table on the right shows the reduction of a quantity in the number of half-lives elapsed.

Half-life (t1⁄2)

• An exponential decay process can be described by any of the following three equivalent formulas:

• The three parameters are all directly related in the following way:

Half-life (t1⁄2) • By plugging in and manipulating these relationships, we get

all of the following equivalent descriptions of exponential decay, in terms of the half-life:

Half-life (t1⁄2)

Half-life (t1⁄2)

Simulation of many identical atoms undergoing radioactive decay, starting with either 4 atoms per box (left) or 400 (right). The number at the top is how many half-lives have elapsed. Note the consequence of the law of large numbers: with more atoms, the overall decay is more regular and more predictable.

For any radioactive material, its half-life…

a. …first decreases and then increases.b. …first increases and then decreases.c. …increases with time.d. …decreases with time.e. …stays the same.

After 6 seconds, the mass of a sample of radioactive material has reduced

from 100 grams to 25 grams.

• Its half-life must be ….?

Define the following stages of NFC. Describe physical and chemical processes that take place in YOUR process. Tell about

facilities that perform YOUR stage in Russian Federation.

•Exploration;•Mining;•Milling;•Conversion;•Enrichment;•Fabrication;

•Power Plant;•Spent fuel storage;•Final disposal;•Reprocessing;•Vitrification;•Recycle.

Work in groups to find the most nuclear theft attackable stage of NFC

Let your groups discuss between each othertrying tern to your opinion about the most nuclear theft

attackable stage of NFC

Give a description of the following isotope:

•Pu236; •U233; •Am241; •Th232

A certain radioactive material has a half-life of 8 minutes. Suppose you have a large sample of this

material, containing 1025 atoms.

• a. How many atoms decay in the first 8 minutes?• b. Does this strike you as a dangerous release of radiation? Explain.• c. How many atoms decay in the second 8 minutes?• d. What is the ratio of the number of atoms that decay in the first 8

minutes to the number of atoms that decay in the second 8 minutes?• e. How long would you have to wait until the decay rate drops to 1%

of its value in the first 8 minutes?

Homework assignment

Find a way to thieve nuclear material on the one of the NFC stage.

Thank you for your attention!