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The
atomic bomb |
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The atomic bomb (to fission) is based on the fact that if a neutron hits the nucleus
of a last heavy atom this fraziona in two parts, in freest one two electrons that
maintain to the above all free chain reaction and an enormous energy. In uranio
that it is found in nature the this reaction it happens naturally but it comes
refrained of the fact that, being the uranio not completely pure, the firm reaction
immediately and little atoms are only transformed in energy. Then ce to consider
the fact that many electrons succeed to escape from the piece of uranio (This
reaction from the radioactivity).
In the outbreak of bomb of this type the energy that free from the complete fission
of a kilogram of uranio is equal to that one produced from the combustion of 2450
tons of coal.
When the mass of our radioactive material knows them enough to assure an equilibrium
between the happened reactions and those failed says that the mass is critical,
that is that can provoke one able chain reaction to make to explode the object.
For I prime it of the chain reaction from neutron part is necessary that the mass
that endures the fission is rendered critical only at once of the outbreak, This
last condition can be realized with 2 arranges:
The first system, used also in the bomb used on Hiroshima
was that one to inside divide the critical mass in two or more subcritical parts
than a cylinder, and at intentional moment joined by means of it loads normally
with conventional explosive (c4).(vedi foto sopra)
When the c4 the two explode parts come joined to large volocita forming
one critical or ipercritica mass that instantaneously give origin to the chain
reaction and therefore to the outbreak. This system of I prime can be used single
with uranio235 in how much the this last one can fissionarsi with neutrons of
whichever speed.
According to system of I prime is a complicated P2o more
but it allows than to use like material the uranio238 or the plutonio, this system
is used for the bomb on Nagasaki.
According to method it is based on the fact that a subcritical mass, if
strongly compressed, can transform in one critical or ipercritica mass. This type
of bomb is of spherical shape, in the center of it is the fissibile material,
All around an explosive of chemical type is found that once primed compresses
with one greatest force the subcritical mass, transforming it in ipercritica and
therefore making to explode it. A method in order to reduce the mass is to make
use of a reflector or commonly said “tamper”, than it is not other
that a layer of a material that reflects electrons so as to to limit the escapes.
A composed bomb nuclear from uranio 235 and 238 without reflector is of 48kg of
weight, instead, with the reflector, the mass is lowered until catching up the
21kg. This system is called to “implosion”.
Unit of measure of the power
The explosive power of a bomb nuclear rapportandola
measure to how much trito it would be necessary to make to explode in order to
free the same amount of energy. E' a measure partially scorretta, because the
trito one it, also with the same explosive power, it does not provoke cancellations,
neither radioactive rains, etc…. In any case 1 Kiloton = 1,000 tons of trito
it. That is a bomb from 1 Kiloton has one explosive power equivalent to a heavy
device of 1.000 tons of trito it. While, analogous, 1 Megaton = 1.000.000 of tons
of trito it. For giving an idea, the most large bombs of airplane never constructed
carry little less than one ton than trito it. The bomb exploded to Hiroshima was
of 12 Kiloton, equivalent that is to the simultaneous outbreak of 12.000 of these
bombs. The bomb of Hiroshima was relatively small. The power of the modern bombs
measure in Megaton, from 0,1 to 10 Megaton approximately.
And when it explodes?
The outbreak of an atomic bomb produces the strongest light
that can instantaneously render Czechs, of continuation forms an incandescent
compressed gas mass, dictates fire ball whose temperature catches up the miglioni
of temperature degrees c, all the one which is found inside of this ball comes
at once vaporizzato. The largeness of the fire ball depends on the power of the
device, one bomb of 10 kiloton forms one ball with diameter of approximately 300
m; for an outbreak from 10 megaton the diameter catches up instead i 5 km.
From the fire ball it comes emitted a shock wave of thermal cancellation that
an immense area catches up, even though with intensity that decreases in constant
way. The amount of received thermal energy to one determined distance from ground
zero depends on the power of the bomb and the state of the atmosphere: if the
visibility is insufficient and the outbreak happens to of over of clouds, as an
example, the effectiveness of the lightning bolt of thermal cancellation that
turns out some considerably is diminished.
In order to give to greater destructive effect the bomb it comes made to explode
to one determined altitude rapportata to its power, in this way the direct shock
wave comes amplified with which it reflects on the ground.
The residual nuclear cancellations from the crescent continuous fire ball to catch
up the ground. But after 3 second (or 11, to second of the bomb) the fire ball,
although it is still a lot hot, it begins to cool off itself with a such extension
that the thermal cancellation does not have more importance. The hot fire ball
raises a lot quickly. As soon as it rises, ago so that the air is pushed towards
the bottom and the high, just like the traction in on a fireplace. That produces
to forts airflows moderately more bottoms: these twenty will raise detritus of
the land surface in order to form the stem of that it will be the characteristic
shape of fungus.
The thermal cancellation can provoke the fire development of combustible material
that extends if the conditions are favorable. The collected data as a result of
the atomic outbreaks on the two Japanese cities revealed that many fires, especially
in the area around ground zero, were provoke to you from secondary causes, like
short circuits, breaches of the ducts of the gas, breach of the furnaces and the
boilers of industrial systems. The shock wave produced detritus that contributed
to feeding flames and to hinder the job of who it tried to tame them.
In particular conditions, which were taken place to Hiroshima and not to Nakasaki,
many single fires can be arranged to produce one great fire storm. The heat of
the fire cause one strongly upward airflow, which in its turn recalls strong twenty
towards the center of the interested area; these twenty feed flames and in the
area all that that exists of inflammable comes quickly divorato from the fire.
The thermal cancellation that hits the skin cause serious ustioni, in particular
an outbreak in quota from 10 kiloton can produce to ustioni of second degree on
the skin not blanket, until 2,4 km from ground zero; for a bomb from 10 megaton,
the corresponding distance is of 32 km.
Beyond to the heat and the shock wave, the outbreak of a bomb nuclear has a particular
and completely absolutely devastating effect: the instantaneous emission of neutrons
and range beams, that they are electromagnetic cancellations to high energy similar
to i beams X, on an area of very many square kilometers. It is the neutrons is
the range beams have the property to cross the matter to the solid state, so that
in order to defend itself from their action it is necessary to be shielded from
spessori consisting of material.
When it comes absorbed from the corporei woven ones, the cancellation nuclear
can cause extremely serious damages even if, for an outbreak in quota, these are
manifested inside of a smaller beam regarding that associate to a shock wave and
the thermal cancellation. In Japan, however, many individuals that had not received
lethal damages for the collision and the heat, died in according to moment because
of the cancellations.
Sonar altimeter
We have inasmuch as an atomic bomb does not come made to
explode when it touches the ground, but comes made to detonate to a sure altitude
based on the power therefore that the wave durto comes increased with the reflection
on the ground. Therefore it has had to install on the bomb an altimeter that calculated
the altitude with one sure precision in order to make it to explode to the calculate
distance.
Of usual a normal altimeter of airplane uses a type of barometer that measure
the changes of the pressure of air to different altitudes. However, the changes
in the air pressure which had to the atmospheric time can negatively influence
the readings of the altimeter. Decided therefore to use a system radar used also
in the submarines. As simple systems to pulsation, come emitted mark them from
the radar place in the bomb, which bounces on the ground comes receipts through
the reflection on the ground from the altimeter of the bomb that automatically
calculates the altidudine to second of the time that the impulse employs in order
to return to the device. The precision of these altimeters is between the meter
and means for the variable ones of the greater heights. But if this system is
cosi precise because is not adopted also on the airplanes? Simply because these
systems are mooolto expensive and therefore “not prati us” for the
civil use.
fallout
Even if what it has been said over would seem the more dangerous
effect of the bomb is not therefore, the fallout and considered the more dangerous
effect. The cancellation nuclear residual, generally famous like fallout, can
represent a risk for completely undamaged immense areas much from the other effects
of the outbreak. In the bombs that draw energy from the fission of uranio 235
or plutonio 239, for every fissile atom you produce yourselves to two radioactive
nuclei; these products of fission explain the persistent radioactivity of detritus
of the bombs, from the moment that many of atoms have half lives of days, months
or also years. Two various categories of fallout are known: premature and delayed.
If an outbreak nuclear verification close to the surface, happens the whirpool
from the same detritus surface and water, materials that go to constitute the
cloud to fungus and are contaminated with the residual ones radioatti you of the
same bomb. The contaminated material begins to fall back in the turn of little
minuteren and can continue also for 24 hours, interesting an area of migliaia
of square kilometers leeward regarding the point of the outbreak: the premature
one is this so-called fallout, that it constitutes an immediate risk for the human
beings. The outbreaks that happen to relatively high quota do not give place fallout
premature. If a bomb nuclear explodes very far from the ground, the residual ones
radioatti to you go up to high quota in the cloud to fungus, and gradually fall
back on an area much immense one.
The nature of the radioactivity and the great vastness of the areas that could
be contaminated from a single outbreak potentially render fallout radioactive
one of the deadlier effects of the nuclear outbreaks, in fact these devices do
not come use you in the wars only for the problem of the fullout today and not
for the devastating destruction that they provoke at once. Among other things
this is also the large danger of centers them electrical workers who take advantage
of the fission (see Cernobyl).
EMP effect
Effect “EMP”: This effect was uncovered in
years '60, later on to nuclear outbreaks experiences them. Acronym EMP is for
ElectroMagneticPulse that is electromagnetic impulse. We have asserted that an
outbreak nuclear provokes one great q uantità of cancellations, between
here those electromagnetic ones. This upsets for a sure every period
electronic system or electrical worker on one immense area. This effect is not,
of for himself, lethal but it does not have to forget that all the instruments
of control of the modern nuclear arsenals are electronic (even if after systems
like the fiber optic were studied that does not endure some disturbance). In a
hypothetical war nuclear, to a “first opposing blow” not only enormous
destructions, but also, a lot probably, the practical inability would correspond
to control just the arsenal. The launch bombs, lacking in every system of tracking
and control-guide, could fall in the impensati places. This effect to fact that
after the outbreak of the bomb on Hiroshima the remained
clocks intact remained firm to the hour of the outbreak.
Nuclear winter
This effect is one of the possible consequences more nuclear
outbreaks. Ognuna of they will raise a great powder amount that for months will
remain suspended in the atmosphere. E' be assumed that the powder amount such
is sufficient in order to shield the beams of the sun and to provoke, therefore,
a lowering of the medium temperature of the planet of some degree. That would
be sufficient to provoke to the passing of much species animals and vegetables.
This effect has not been, for the truth, uncovered, but only previewed on the
base of calculations, whose validity still must be tried. There is who thinks,
as an example, that minor the amount of heat arrived on the earth would be compensated
from one risen of effect greenhouse, provoked from same powders. It is not therefore
clear if the temperature would diminish, would remain invariata or, quite, it
would increase..