Deck 7: Energy From Nuclear Fusion

Question 1

Using appropriate masses from Appendix II, show that the energy released
from equation (7.7) is 26.7 MeV.

Answer 1

For the process

Question 2

The sun generates energy through nuclear fusion, which converts mass into

Answer 2

The change in mass is given by Einstein's relation as

Question 3

If all of the world energy needs were provided by d-t fusion, how much
lithium per year would be utilized to produce tritium? Consider the total energy associated
with fusion as being equivalent to the world's current primary energy use.

Answer 3

From the Preface the world's total primary energy use is energy per d-t fusion is given by equation (7.6) as 17.6 MeV. An additional 4.8 MeV is
released in the breeding reaction given in equation (7.10) for a total of (17.6+4.8) MeV =
22.4 MeV. This is converted into joules to yield

Question 4

The age of the sun has been estimated at 4.6 billion years. If it has radiated

Question 5

Verify the energy release given for the process in equation (7.3).

Question 6

What is the number density of tritons in a 50% d/50% t plasma that has the
same mass density as air at STP

Question 7

Confirm that the total energy released by the process in equation (7.6) is
17.6 MeV.

Question 8

energy.

Question 9

What is the kinetic energy of a particle in a plasma at a temperature of
200 MK?

Question 10

At the current worldwide rate of primary energy use, determine the potential
longevity of d-t fusion as a sole power source for society, based on the availability of
lithium. Current estimates of viable lithium resources worldwide are about 1.7×1010 kg.
Compare this result with the calculation in Example 7.3.

Question 11

Compare the energy produced per kg of fuel for the combustion of coal, d-d
fusion and d-t fusion.

Question 12

The physical radius of a nucleus in units of fm is often approximated by the

Question 13

(a)

Question 14

A 1 m diameter sphere of d-t plasma in a magnetic confinement fusion
reactor just satisfies the Lawson criterion and is at the breakeven point without particle
injection. If the sphere of plasma radiates as a black body, calculate the total power
radiated from its surface.

Question 15

Tritium-tritium fusion is given by the reaction

Question 16

Consider a body of water in area and 100 m deep. The center of mass

Question 17

Consider a d-t fusion reactor that produces an output of 1000 MWe at a

Question 18

Question 19

The total power output of the sun is produced within a radius of 175,000 km of its center. If we were able to reproduce the
sun's conditions for p-p fusion in a fusion reactor with an active volume of 10×10×10 m3,
what would be the reactor's power output? Is p-p fusion a reasonable approach to take for a
power reactor?

Question 20

The ITER is designed to have a magnetic field pulse duration of up to 480
seconds. What corresponding plasma particle density is needed to achieve the Lawson
criterion?