ENERGY CHALLENGES: nuclear power in France
“Nuclear power is the primary source of electricity in France. The first French power plant was opened in 1965. In
2004, 425.8 TWh out of the country's total production of 540.6 TWh of electricity was from nuclear power (78.8%),
the highest percentage in the world. France's nuclear power industry has been called "a success story" that has put the
nation "ahead of the world" in terms of providing cheap, clean energy. While fusion power is not expected to be feasible
for many more decades, France has shown promise to be a forerunner in the technology by winning the bid to host the
ITER reactor in Cadarache. The ITER should start actual fusion around 2018. However, ITER does not plan to generate
any commercially available energy.”
Source: Wikipedia - http://en.wikipedia.org/wiki/Nuclear_power_in_France
QUESTIONS
1/Using the graph, describe the evolution of electricity production in France from 1980 to 2010.
2/ Describe and explain the location of the nuclear power plants on the French map.
3/ Explain what is a nuclear reaction, what is the difference between a chemical and a nuclear reaction, and how nuclear
reactions can produce so much energy.
4/ Explain briefly how a nuclear power plant works.
5/Give examples of nuclear reactions you know. Describe those reactions.
6/“ (…) total production of 540.6 TWh (...) ” : explain what TWh means. How many years can we heat a house with 540
TWh assuming that we are using four 2.5kW heaters?
7/ Why is nuclear power so important to France?
1/Using the graph, describe the evolution of electricity production in France from 1980 to 2010.
The graph presented shows the French electricity production from 1980 to 2010. We can see the different processes
used to produce electricity. We can notice that the total electricity produced has increased drastically in the last 30
years. The share of fossil and hydroelectric energy has remained approximately constant whereas the share of nuclear
energy has increased a lot. This is due to the nuclear policy of France. We can also notice that if the share of renewable
energy is growing, it is however very small: only a few percent. This is very small compared to other countries (in the
world, the share of renewable in electricity generation is around 18%).
2/ Describe and explain the location of the nuclear power plants on the French map.
We can see that nuclear plants are located close to big rivers or close to the sea. This is necessary to cool the power
plant. Discharging large amounts of hot water may raise the temperature of the river or lake to an unacceptable level for
the local ecosystem. Elevated water temperatures can kill aquatic organisms (thermal pollution).
3/ Explain what is a nuclear reaction. What is the difference between a chemical and a nuclear reaction? How can nuclear
reactions produce so much energy?

A nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different
from the initial particles. While the transformation is spontaneous in the case of radioactive decay, it is
initiated by a particle in the case of a nuclear reaction.

In the case of a chemical reaction, only electrons are involved.

The amount of energy released can be determined using Einstein's mass-energy equivalence formula (1905):
E = mc². As c is the speed of light in a vacuum, c = 3x108 m/s, c² =9x1016 m²/s²: a very small mass defect will
be associated to a very big energy.
Remind that 1 u (the atomic mass unit (u) is one twelfth of the mass of an atom of carbon-12) = 931.46 MeV/c².
4/ Explain briefly how a nuclear power plant works.
To turn nuclear fission into electrical energy, the first step is to be able to control the energy given off by the enriched
uranium. The uranium bundle acts as an extremely high-energy source of heat. It heats the water and turns it to steam.
The steam drives a turbine, which spins a generator to produce power. Water acts as a coolant and is necessary to
condensate the steam used to drive the turbine into water. In the turbine, electricity is generated by the movement of a
loop of wire, or disc of copper between the poles of a magnet. To prevent overheating, control rods made of a material
that absorbs neutrons produced by the nuclear reaction are inserted into the uranium bundle using a mechanism that can
raise or lower the control rods. Raising and lowering the control rods allow operators to control the rate of the nuclear
reaction.
5/Give examples of nuclear reactions you know. Describe those reactions.
A nuclear reaction can be usually written as: Target nucleus + projectile -> Final nucleus + ejected particles + Q.
Q represents the reaction energy (positive value for exothermal reactions and a negative one for endothermic
reactions).
In a nuclear reaction, mass number (A = protons + neutrons) and charge number (Z = atomic number) don’t change.
To illustrate this, we can give the example of Uranium 235 fission:
In “Terminale S”, we study three different nuclear reactions:
A
X 

Alpha radioactivity, where a helium nuclei is released: Z

β - or β+ radioactivity, where an electron or a positron is released:
A
Z

X 
X' 
A
Z 1
0
1
e
A
Z
X 
A 4
Z 2
X '  24He
X '  10e
A
Z 1
Gamma radioactivity: it involves the emission of electromagnetic energy (similar to light energy) from an atom's
nucleus. No particles are emitted during gamma radiation. These radiations are highly energetic (high
frequency).
6/ “ (…) total production of 540.6 TWh (...) ” : explain what TWh means. How many years can we heat a house with 540
TWh assuming that we are using four 2.5kW heaters?

TWh means “Tera Watts hour”. This is a unit for the energy. Using SI units, we have:
1 TWh = 1012 Wh = 1012 x 1W x 3600s = 3.6x1015 J.

540 TWh = 540 x1012 Wh = 5.40x1014 Wh = 5.40x1011 kWh.
We can heat a house during 5.40x1011/(4x2.5) = 5.40x1010 hours ≈ 6 million years!
7/Why is nuclear power so important to France?
Nuclear power is so important to France because we don’t have any oil reserves. Producing electricity from nuclear
reactions permits our country to be more independent from the Arab states.