1. Destructive Effects of Nuclear Weapons
Blast damage
Thermal damage
Radiation damage
EM-pulse
The generation of a mechanical shock
through sudden increase of pressure
causes mechanical damages
The generation of a heat wave
expanding with the shock causes
incineration
The distribution of radiation through
Short range and atmospheric fallout
causes short term and long term
radiation sickness effects
Electromagnetic shock leads to
break-down of communication systems

2. The mechanical shock pressure shock velocity: vs sound speed: cs
0.10 ms
0.24 ms
shock velocity: vs
sound speed: cs
specific heat: =1.4
peak pressure: p
air pressure: p0=15 psi
wind velocity: vw
dynamic pressure: q
0.38 ms
0.52 ms
pressure
0.66 ms
0.80 ms
0.94 ms

3. Example Depending on the peak pressure (atmospheric pressure 15 psi)
and the speed of sound (cs=330 m/s in atmospheric gas) you
receive the following values for shock and wind velocity and
dynamic pressure

4. Shock characteristics
Shock on flat surface causes
reflection which is expressed
by reflected overpressure pr!
for large dynamic pressure
for small dynamic pressure

5. Example shock front against house

6. example 250 kT blast Nevada 1953 effect on houses in different
distance from center of blast
2.65 miles
5.3 miles

7. over pressure – wind velocity
Even an over pressure of 2 psi generates hurricane like storm conditions!

8. The American Home

9. Shock expansion Shock expands radially from explosion center.
Amplitude decreases, but after time t5 the pressure
behind shock front falls below atmospheric pressure,
Under-pressure which causes the air to be sucked in.

10. Overpressure and Mach Stem

11. Pressure conditions with transversing shock
Shock hits
generates strong wind
Shock decreases
Underpressure
Wind direction changes
Normal air pressure
Wind calms down

12. Pressure induced wind effects

13. Scaling laws for blast effects
Shock/blast expands over volume ~d3, the following scaling law can be applied for estimating distance effects between different blast strengths
Normalized to a standard 1kT blast the following expression can be applied:

14. Distance Effects Scaling for blast intensities 100 kT
e.g. the effect which occurs
for a 1 kT blast at distance
d1 occurs for a 100kT blast
at distance d. d1=10,000ft
d=24,662ft.
1 kT
Peak over pressure
as function of distance
for a 1kT blast

15. Distance effects of airburst
damage comparison for
a 1000 kT and a 500 kT
bomb using the scaling law
with respect to 200 kT bomb

16. Scaling in Altitude often scaled to W1 = 1 kT
Similar scaling relation for altitude dependence of blast effects.
For altitudes less than 5000 ft (1700 m) normal atmospheric
conditions can be assumed. For higher altitude effects changes,
altitude dependence of air pressure and sound speed need to
be taken into account.

17. Peak overpressure in height & distance
Suppose you have 80 kT bomb at 860 ft height, what is the distance to
which 1000psi overpressure extends? Normalization: W1=1kT
Corresponding height for 1kT burst
(or scaled height)
Distance of 1000 psi overpressure

18. Surface burst versus airburst
Suppose you have 500 kT bomb at 1.1 mile height, what is the distance to
which 2 psi overpressure extends and compare with ground zero detonation.
Scaled height for 1 kT bomb; h1 = h/W1/3 = 0.14 miles ≈ 765 ft. This corresponds
to d1 = 3800 ft = 0.69 miles. The distance for the 2 psi overpressure on the
ground from the 500 kT blast would be d = d1·W1/3 = 0.69·5001/3 = 5.5 miles.
Surface burst: d1=2500 ft=0.45 miles, d = d1·W1/3 = 0.45·5001/3 = 3.6 miles.

19. Blast effects on humans

20. Thermal effects
Approximately 35 percent of the energy from a nuclear explosion is an intense burst of thermal radiation, i.e., heat. Thermal effects are mainly due to originated heat from blast which expands with wind velocity and incinerates
everything within expansion
radius. The thermal radiation
from a nuclear explosion can
directly ignite kindling materials.
Ignitable materials outside
the house, such as leaves, are
not surrounded by enough
combustible material to generate
a self-sustaining fire. Fires more likely to spread are those caused by thermal radiation passing through windows to ignite beds and overstuffed furniture inside houses.
Fallout
10%
Blast
50%
Thermal
35%
Initial
Radiation 5%

21. Thermal Energy Release
For a fireball with radius r the heat emitting surface is:
Total energy emitted per cm2 and second is described
by the Stefan Boltzmann law
Total thermal energy emission from fireball is therefore:
With radius r in units m and temperature T in Kelvin

22. The thermal power of the fireball changes with time.
Thermal energy release should be expressed in terms
of maximum power Pmax (scaled power) and in terms
of scaled time tmax which corresponds of time of the
maximum thermal energy release from the fireball.
Fireball power
Fraction of emitted thermal energy

23. For air bursts below 15,000 ft altitude the maximum power Pmax
& the maximum time tmax are related to the bomb yield W (in kT)
e.g. for a 500 kT burst in 5000 ft altitude:
According to the scaling laws expressed in the figure, total power and fraction of heat release can be calculated for any time; e.g. the total amount of thermal energy emitted at t=1sec is:
Fraction of thermal energy released at 1 s is 40%!