Архив "ядрени оръжия"; дискусии

[Joro-01]

 

 

 

 

 

[nik1]

Преди 54 минъти, Joro-01 said:

Я да пуснем няколко видеа

 

 

 

 

 

 

 

В първото видео , в  частта за плутониевата бомбата , с имплозивния метод:

 Инициаторът ("тригерът") на fission-процеса е Po-210/Be-9 сфера.

Po-210 e силен алфа-емитер,  а необходимите за инициирането на процеса неутрони се създават при сблъсъците на алфа-частиците с Be-9

Be-9 + Hе-4  -->Be-8 + n + He-4

Реакцията протича при 0,08 процента от сблъсъците; но тъй като Po-210 е силен емитер на алфа-частици (в разл. случаи се емитират от 100 до 1000 милиарда алфа-частици в секунда), получените неутрони (неутронен поток) са достатъчни за да инциират  процеса на верижно разпадане при /след имплозивното свиване и съответно уплътняване на плутония..

 

[Du6ko]

Интересна и сериозна тема. Малко страшна. Не знам разрешено ли и малко хумор и веселба ? Помня освен съветите за бели мокри чаршафи, замазване на прозорците със вар и една песничка, посветена на ядрената война.

Медленно ракеты уплывают вдаль,
Встречи с ними ты уже не жди.
И, хотя А..... немного жаль,
Родина прикажет - кнопку жми !

Скатертью, скатертью хлорциан стелется 
И забирается под противогаз.
Каждому, каждому в лучшее верится. 
Но разрывается ядерный фугас.

Может мы обидели кого-то зря,
Сбросив пару лишних мегатонн ?
Плавится земля горит бетон
Здесь недавно правил Пентагон !

Ядерный фугас летит, вращается,
Скоро будет город В*тон.
Ну а то, что от него останется,
Мы погрузим в голубой вагон.

Над Е*ой тучи поднимаются
Очень рада вся моя страна
Ядерный запас у нас кончается
Но зато по мире тишина.

 

 

 

[nik1]

ПС

това пък е водородната бомба Teller-Ulam конструкция

 

Components of the Teller-Ulam design:

• External Casing (made of structural material: steel, aluminum, plastic, etc.)
• Primary (fission trigger)
• Radiation Shield (high-Z material: uranium or tungsten; this may also contain boron-10 as a neutron absorber)
• Hohlraum or Radiation Case (high-Z material: uranium, lead, or tungsten, etc.)
• Radiation Channel (gap between the casing and the fusion pusher tamper; basically empty, often filled with plastic foam)
• Fusion Pusher/Tamper (high-Z material: natural/depleted uranium, HEU, tungsten, lead, etc.)
• Fusion Fuel (usually Li-6 deuteride; also natural lithium deuteride, liquid deuerium, etc.)
• Spark Plug (fissionable rod of HEU or plutonium)

When the trigger explodes, the X-rays escaping from the fission trigger fill the radiation channel, the space between the bomb casing and the fusion capsule, with a photon gas. This space is filled with plastic foam, essentially just carbon and hydrogen, which becomes completely ionized and transparent as the x-rays penetrate. The inner casing and outer capsule surfaces are heated to very high temperatures. The uranium shield between the trigger and the fusion capsule, and capsule pusher/tamper, prevents the fusion fuel from becoming heated prematurely.

Thermal equilibrium is established extremely rapidly, so that the temperature and energy density is uniform throughout the radiation channel. As the surface of the tamper becomes heated, it expands and ablates (blows off the fuel capsule surface). This ablation process, essentially a rocket turned inside out, generates tremendous pressure on the fuel capsule and causes an accelerating implosion. Thermal equilibrium assures that the implosion pressure is very uniformly distributed. The transparent carbon-hydrogen plasma retards the early expansion of the tamper and casing plasmas, keeping the radiation channel from being blocked by these opaque high-Z materials until equilibrium is fully established.

The force that compresses and accelerates the fusion fuel inward is provided solely by the ablation pressure. The other two possible sources of pressure - plasma pressure (pressure generated by the thermal motion of the plasma confined between the casing and the fuel capsule) and radiation pressure (pressure generated by thermal X-ray photons) do not directly influence the process.

The pressure exerted by the plasma causes cylindrical (or spherical) implosion of the fusion capsule, consisting of the pusher/tamper, fuel, and the axial fissionable rod. The capsule is compressed to perhaps 1/30 of its original diameter for cylindrical compression (1/10 for spherical compression), and thus reaches or exceeds 1000 times its original density. It is noteworthy that at this point the explosive force released by the trigger, an amount of energy sufficient to destroy a small city, is being used simply to squeeze several kilograms of fuel!

It is unlikely that the fissionable rod reaches such extreme compression however. Located at the center, it will experience an extremely violent shock wave that will heat it to high temperatures but compress it only modestly, increasing its density by a factor of 4 or so. This is sufficient to make the rod super-critical. Depending on the degree of symmetry, and the physics of the particular capsule collapse process higher densities are possible. Thermalized neutrons trapped in the fusion fuel, which are left over from the intense fission neutron flux, initiate a chain reaction as soon as the rod becomes critical. The rod fissions at an accelerating rate as it, and the rest of the fuel capsule continue to implode and acts as the fusion "spark plug". Combined with the high temperatures generated by the convergent shock wave, this raises the temperature of the fusion fuel around the rod high enough to initiate the fusion reaction. Self-supporting fusion burning then spreads outward. The fusion tamper prevents the escape of thermal radiation from the fuel. As the temperature rises the fusion reactions accelerate, enhancing the burn efficiency considerably. The temperatures generated by fusion burning can exceed 300 million K, considerably more than that produced by fission.

The fuel in the fusion capsule consists of lithium deuteride that may be enriched in the Li-6 isotope (which makes up 7.5% of natural lithium). Natural lithium has been used with success in fusion bomb designs, but modern light weight designs seem to use lithium enriched in Li-6.

[Joro-01]

Много ми е интересно на тактически / военен БГ "spark plug" свещ ли ще се превежда. Това може на руски да се види, термнологията ни е предимно от там.

Аз скоро ще се ориентирам към технологията на правене, включваща и добива обогатяването и технологията / решенията, доколкото за последните има инфо. И доколкото е законно, да не вземат ДАНС да направят проблеми на форума / сайта.

Сещам се че например центрофугите са големи и трудно се крият от самолет / сателит. В тази връзка може смятам, че може да се познае какво има Северна корея (дано не залитнем към политика) и какво няма.

Преводи и/или терминини съкращения да добавяме ли? За някой трети примерно? Май няма нужда, но..

- High-Z материал - с голям пореден номер в периодичната система, сиреч тежък, с много протони..

- HEU - би трябвало да е високообогатен уран.

 

[nik1]

В монографията има доста написано за технологиите и дизайна на оръжията..

Авторът и е учен от Кейптаун..Доколкото разбрах от това което пише той, специфичната информация, която публикува, е декласифицирана и общодостъпна.  (общата такава - физика,процеси, формули, изчисления, не би следвало да е проблемна).

Забележка: Не съм срещнал това написано и декларирано в прав текст, но за един от случаите, за който авторът  не представи конкретна информация, той беше написал че тя е класифицирана, и независмо от това може да се намери в някои сайтове

Все още нямаме Закон за тероризма, или "Патриотичен акт", но да ДАНС хипотетично биха да направят "проблеми" на форума, ако решат да печелят дивиденти и точки .. Представете си си как звучи заглавие в някой от вестниците или медиите "ДАНС затвори сайт, в които са се обсъждали подробности по правенето на оръжия, включително ядрени. Следствието уточнява дали е  имало умисъл, а организаторите се разследват за връзки  с терористични организации"

 

[Joro-01]

Да, де, това имам предвид. Винаги може да се позоват на нещо за да изкарат, че сме заплаха за сигурността. Не е гот.

Добре де, можем да се придържаме към монографията. Какво пък повече можем да дадем...

 

[nik1]

Те ДАНС могат да направят проблеми и при дискусиите на всеки друг вид оръжие, какво да го мислим , имаме си раздел, той е за това..

Та, мисля, че няма проблеми да се вкарат и други публикации с научен профил,и не представляват класифицирана информация.

(Ако с клиповете, се създаваха проблеми за нацинаолните сигурности, то мисля щеше да се чуе досега)

====================

Някои неща от монографията, които дискутирахме вчера:

(в последната част от цитата Sources of Radiation се обяснява по детайлно наличието/възникването на гама-радиацията)

5.0 Effects of Nuclear Explosions

Nuclear explosions produce both immediate and delayed destructive effects. Immediate effects (blast, thermal radiation, prompt ionizing radiation) are produced and cause significant destruction within seconds or minutes of a nuclear detonation. The delayed effects (radioactive fallout and other possible environmental effects) inflict damage over an extended period ranging from hours to centuries, and can cause adverse effects in locations very distant from the site of the detonation. These two classes of effects are treated in separate subsections.

The distribution of energy released in the first minute after detonation among the three damage causing effects is:

                      Low Yield (<100 kt)   High Yield (>1 Mt)
Thermal Radiation        35%                      45%
Blast Wave               60%                      50%
Ionizing Radiation        5%                       5%
(80% gamma, 20% neutrons)

The radioactive decay of fallout releases an additional 5-10% over time.

• 5.1 Overview of Immediate Effects
• 5.2 Overview of Delayed Effects
• 5.3 Physics of Nuclear Weapon Effects
• 5.4 Air Bursts and Surface Bursts
• 5.5 Electromagnetic Effects
• 5.6 Mechanisms of Damage and Injury

5.1 Overview of Immediate Effects

The three categories of immediate effects are: blast, thermal radiation (heat), and prompt ionizing or nuclear radiation. Their relative importance varies with the yield of the bomb. At low yields, all three can be significant sources of injury. With an explosive yield of about 2.5 kt, the three effects are roughly equal. All are capable of inflicting fatal injuries at a range of 1 km.

The equations below provide approximate scaling laws for relating the destructive radius of each effect with yield:

 

r_thermal = Y^0.41 * constant_th
r_blast = Y^0.33 * constant_bl
r_radiation = Y^0.19 * constant_rad

If Y is in multiples (or fractions) of 2.5 kt, then the result is in km (and all the constants equal one). This is based on thermal radiation just sufficient to cause 3rd degree burns (8 calories/cm^2); a 4.6 psi blast overpressure (and optimum burst height); and a 500 rem radiation dose.

The underlying principles behind these scaling laws are easy to explain. The fraction of a bomb's yield emitted as thermal radiation, blast, and ionizing radiation are essentially constant for all yields, but the way the different forms of energy interact with air and targets vary dramatically.

Air is essentially transparent to thermal radiation. The thermal radiation affects exposed surfaces, producing damage by rapid heating. A bomb that is 100 times larger can produce equal thermal radiation intensities over areas 100 times larger. The area of an (imaginary) sphere centered on the explosion increases with the square of the radius. Thus the destructive radius increases with the square root of the yield (this is the familiar inverse square law of electromagnetic radiation). Actually the rate of increase is somewhat less, partly due to the fact that larger bombs emit heat more slowly which reduces the damage produced by each calorie of heat. It is important to note that the area subjected to damage by thermal radiation increases almost linearly with yield.

Blast effect is a volume effect. The blast wave deposits energy in the material it passes through, including air. When the blast wave passes through solid material, the energy left behind causes damage. When it passes through air it simply grows weaker. The more matter the energy travels through, the smaller the effect. The amount of matter increases with the volume of the imaginary sphere centered on the explosion. Blast effects thus scale with the inverse cube law which relates radius to volume.

The intensity of nuclear radiation decreases with the inverse square law like thermal radiation. However nuclear radiation is also strongly absorbed by the air it travels through, which causes the intensity to drop off much more rapidly.

These scaling laws show that the effects of thermal radiation grow rapidly with yield (relative to blast), while those of radiation rapidly decline.

In the Hiroshima attack (bomb yield approx. 15 kt) casualties (including fatalities) were seen from all three causes. Burns (including those caused by the ensuing fire storm) were the most prevalent serious injury (two thirds of those who died the first day were burned), and occurred at the greatest range. Blast and burn injuries were both found in 60-70% of all survivors. People close enough to suffer significant radiation illness were well inside the lethal effects radius for blast and flash burns, as a result only 30% of injured survivors showed radiation illness. Many of these people were sheltered from burns and blast and thus escaped their main effects. Even so, most victims with radiation illness also had blast injuries or burns as well.

With yields in the range of hundreds of kilotons or greater (typical for strategic warheads) immediate radiation injury becomes insignificant. Dangerous radiation levels only exist so close to the explosion that surviving the blast is impossible. On the other hand, fatal burns can be inflicted well beyond the range of substantial blast damage. A 20 megaton bomb can cause potentially fatal third degree burns at a range of 40 km, where the blast can do little more than break windows and cause superficial cuts.

It should be noted that the atomic bombings of Hiroshima and Nagasaki caused fatality rates were ONE TO TWO ORDERS OF MAGNITUDE higher than the rates in conventional fire raids on other Japanese cities. Eventually on the order of 200,000 fatalities, which is about one-quarter of all Japanese bombing deaths, occurred in these two cities with a combined population of less than 500,000. This is due to the fact that the bombs inflicted damage on people and buildings virtually instantaneously and without warning, and did so with the combined effects of flash, blast, and radiation. Widespread fatal injuries were thus inflicted instantly, and the many more people were incapacitated and thus unable to escape the rapidly developing fires in the suddenly ruined cities. Fire raids in comparison, inflicted few immediate or direct casualties; and a couple of hours elapsed from the raid's beginning to the time when conflagrations became general, during which time the population could flee.

A convenient rule of thumb for estimating the short-term fatalities from all causes due to a nuclear attack is to count everyone inside the 5 psi blast overpressure contour around the hypocenter as a fatality. In reality, substantial numbers of people inside the contour will survive and substantial numbers outside the contour will die, but the assumption is that these two groups will be roughly equal in size and balance out. This completely ignores any possible fallout effects.

---

============

============

5.3.1 Fireball Physics

The fireball is the hot ball of gas created when a nuclear explosion heats the bomb itself, and the immediate surrounding environment, to very high temperatures. As this incandescent ball of hot gas expands, it radiates part of its energy away as thermal radiation (including visible and ultraviolet light), part of its energy also goes into creating a shock wave or blast wave in the surrounding environment. The generation of these two destructive effects are thus closely linked by the physics of the fireball. In the discussion below I assume the fireball is forming in open air, unless stated otherwise.

5.3.1.1 The Early Fireball

Immediately after the energy-producing nuclear reactions in the weapon are completed, the energy is concentrated in the nuclear fuels themselves. The energy is stored as (in order of importance): thermal radiation or photons; as kinetic energy of the ionized atoms and the electrons (mostly as electron kinetic energy since free electrons outnumber the atoms); and as excited atoms, which are partially or completely stripped of electrons (partially for heavy elements, completely for light ones).

Thermal (also called blackbody) radiation is emitted by all matter. The intensity and most prevalent wavelength is a function of the temperature, both increasing as temperature increases. The intensity of thermal radiation increases very rapidly - as the fourth power of the temperature. Thus at the 60-100 million degrees C of a nuclear explosion, which is some 10,000 times hotter than the surface of the sun, the brightness (per unit area) is some 10 quadrillion (10^16) times greater! Consequently about 80% of the energy in a nuclear explosion exists as photons. At these temperatures the photons are soft x-rays with energies in the range of 10-200 KeV.

The first energy to escape from the bomb are the gamma rays produced by the nuclear reactions. They have energies in the MeV range, and a significant number of them penetrate through the tampers and bomb casing and escape into the outside world at the speed of light. The gamma rays strike and ionize the surrounding air molecules, causing chemical reactions that form a dense layer of "smog" tens of meters deep around the bomb. This smog is composed primarily of ozone, and nitric and nitrous oxides.

X-rays, particularly the ones at the upper end of the energy range, have substantial penetrating power and can travel significant distances through matter at the speed of light before being absorbed. Atoms become excited when they absorb x-rays, and after a time they re-emit part of the energy as a new lower energy x-ray. By a chain of emissions and absorptions, the x-rays carry energy out of the hot center of the bomb, a process called radiative transport. Since each absorption/re-emission event takes a certain amount of time, and the direction of re-emission is random (as likely back toward the center of the bomb as away from it), the net rate of radiative transport is considerably slower than the speed of light. It is however initially much faster than the expansion of the plasma (ionized gas) making up the fireball or the velocity of the neutrons.

An expanding bubble of very high temperatures is thus formed called the "iso-thermal sphere". It is a sphere were everything has been heated by x-rays to a nearly uniform temperature, initially in the tens of millions of degrees. As soon as the sphere expands beyond the bomb casing it begins radiating light away through the air (unless the bomb is buried or underwater). Due to the still enormous temperatures, it is incredibly brilliant (surface brightness trillions of times more intense than the sun). Most of the energy being radiated is in the x-ray and far ultraviolet range to which air is not transparent. Even at the wavelengths of the near ultraviolet and visible light, the "smog" layer absorbs much of the energy. Then too, at this stage the fireball is only a few meters across. Thus the apparent surface brightness at a distance, and the output power (total brightness) is not nearly as intense as the fourth-power law would indicate.

5.3.1.2 Blast Wave Development and Thermal Radiation Emission

As the fireball expands, it cools and the wavelength of the photons transporting energy drops. Longer wavelength photons do not penetrate as far before being absorbed, so the speed of energy transport also drops. When the isothermal sphere cools to about 300,000 degrees C (and the surface brightness has dropped to being a mere 10 million times brighter than the sun), the rate of radiative growth is about equal to the speed of sound in the fireball plasma. At this point a shock wave forms at the surface of the fireball as the kinetic energy of the fast moving ions starts transferring energy to the surrounding air. This phenomenon, known as "hydrodynamic separation", occurs for a 20 kt explosion about 100 microseconds after the explosion, when the fireball is some 13 meters across. A shock wave internal to the fireball caused by the rapidly expanding bomb debris may overtake and reinforce the fireball surface shock wave a few hundred microseconds later.

The shock wave initially moves at some 30 km/sec, a hundred times the speed of sound in normal air. This compresses and heats the air enormously, up to 30,000 degrees C (some five times the sun's surface temperature). At this temperature the air becomes ionized and incandescent. Ionized gas is opaque to visible radiation, so the glowing shell created by the shock front hides the much hotter isothermal sphere inside. The shock front is many times brighter than the sun, but since it is much dimmer than the isothermal sphere it acts as an optical shutter, causing the fireball's thermal power to drop rapidly.

The fireball is at its most brilliant just as hydrodynamic separation occurs, the great intensity compensating for the small size of the fireball. The rapid drop in temperature causes the thermal power to drop ten-fold, reaching a minimum in about 10 milliseconds for a 20 kt bomb (100 milliseconds for 1 Mt bomb). This "first pulse" contains only about 1 percent of the bomb's total emitted thermal radiation. At this minimum, the fireball of a 20 kt bomb is 180 meters across.

As the shock wave expands and cools to around 3000 degrees, it stops glowing and gradually also becomes transparent. This is called "breakaway" and occurs at about 15 milliseconds for a 20 kt bomb, when the shock front has expanded to 220 meters and is travelling at 4 km/second. The isothermal sphere, at a still very luminous 8000 degrees, now becomes visible and both the apparent surface temperature and brightness of the fireball climb to form the "second pulse". The isothermal sphere has grown considerably in size and now consists almost entirely of light at wavelengths to which air is transparent, so it regains much of the total luminosity of the first peak despite its lower temperature. This second peak occurs at 150 milliseconds for a 20 kt bomb, at 900 milliseconds for a 1 Mt bomb. After breakaway, the shock (blast) wave and the fireball do not interact further.

A firm cutoff for this second pulse is impossible to provide because the emission rate gradually declines over an extended period. Some rough guidelines are that by 300 milliseconds for a 20 kt bomb (1.8 seconds for a 1 Mt) 50% of the total thermal radiation has been emitted, and the rate has dropped to 40% of the second peak. These figures become 75% total emitted and 10% peak rate by 750 milliseconds (20 kt) and 4.5 second (1 Mt). The emission time scales roughly as the 0.45 power of yield (Y^0.45).

Although this pulse never gets as bright as the first, it emits about 99% of the thermal radiation because it is so much longer.

5.3.2 Ionizing Radiation Physics

There are four types of ionizing radiation produced by nuclear explosions that can cause significant injury: neutrons, gamma rays, beta particles, and alpha particles. Gamma rays are energetic (short wavelength) photons (as are X-rays), beta particles are energetic (fast moving) electrons, and alpha particles are energetic helium nuclei. Neutrons are damaging whether they are energetic or not, although the faster they are, the worse their effects.

They all share the same basic mechanism for causing injury though: the creation of chemically reactive compounds called "free radicals" that disrupt the normal chemistry of living cells. These radicals are produced when the energetic radiation strikes a molecule in the living issue, and breaks it into ionized (electrically charged) fragments. Fast neutrons can do this also, but all neutrons can also transmute ordinary atoms into radioactive isotopes, creating even more ionizing radiation in the body.

The different types of radiation present different risks however. Neutrons and gamma rays are very penetrating types of radiation. They are the hardest to stop with shielding. They can travel through hundreds of meters of air and the walls of ordinary houses. They can thus deliver deadly radiation doses even if an organism is not in immediate contact with the source. Beta particles are less penetrating, they can travel through several meters of air, but not walls, and can cause serious injury to organisms that are near to the source. Alpha particles have a range of only a few centimeters in air, and cannot even penetrate skin. Alphas can only cause injury if the emitting isotope is ingested.

The shielding effect of various materials to radiation is usually expressed in half-value thickness, or tenth-value thickness: in other words, the thickness of material required to reduce the intensity of radiation by one-half or one-tenth. Successive layers of shielding each reduce the intensity by the same proportion, so three tenth-value thickness reduce the intensity to one-thousandth (a tenth-value thickness is about 3.3 half-value thicknesses). Some example tenth-value thicknesses for gamma rays are: steel 8.4-11 cm, concrete 28-41 cm, earth 41-61 cm, water 61-100 cm, and wood 100-160 cm. The thickness ranges indicate the varying shielding effect for different gamma ray energies.

Even light clothing provides substantial shielding to beta rays.

5.3.2.1 Sources of Radiation

5.3.2.1.1 Prompt Radiation 
Radiation is produced directly by the nuclear reactions that generate the explosion, and by the decay of radioactive products left over (either fission debris, or induced radioactivity from captured neutrons).

The explosion itself emits a very brief burst (about 100 nanoseconds) of gamma rays and neutrons, before the bomb has blown itself apart. The intensity of these emissions depends very heavily on the type of weapon and the specific design. In most designs the initial gamma ray burst is almost entirely absorbed by the bomb (tamper, casing, explosives, etc.) so it contributes little to the radiation hazard. The neutrons, being more penetrating, may escape. Both fission and fusion reactions produce neutrons. Fusion produces many more of them per kiloton of yield, and they are generally more energetic than fission neutrons. Some weapons (neutron bombs) are designed specifically to emit as much energy in the form as neutrons as possible. In heavily tamped fission bombs few if any neutrons escape. It is estimated that no significant neutron exposure occurred from Fat Man, and only 2% of the total radiation dose from Little Boy was due to neutrons.

The neutron burst itself can be a significant source of radiation, depending on weapon design. As the neutrons travel through the air they are slowed by collisions with air atoms, and are eventually captured. Even this process of neutron attenuation generates hazardous radiation. Part of the kinetic energy lost by fast neutrons as they slow is converted into gamma rays, some with very high energies (for the 14.1 MeV fusion neutrons). The duration of production for these neutron scattering gammas is about 10 microseconds. The capture of neutrons by nitrogen-14 also produces gammas, a process completed by 100 milliseconds.

Immediately after the explosion, there are substantial amounts of fission products with very short half-lifes (milliseconds to minutes). The decay of these isotopes generate correspondingly intense gamma radiation that is emitted directly from the fireball. This process is essentially complete within 10 seconds.

The relative importance of these gamma ray sources depends on the size of the explosion. Small explosions (20 kt, say) can generate up to 25% of the gamma dose from the direct gammas and neutron reactions. For large explosions (1 Mt) this contribution is essentially zero. In all cases, the bulk of the gammas are produced by the rapid decay of radioactive debris.

 

 

[Warlord]

Прекалявате с конспиративните си страхове  принципа на ядреното оръжие отдавна е обществено достояние и се обсъжда свободно навсякъде. Съмнявам се, че Ким Чен Ун се информира точно от нашия форум как да си направи водородната бомба
И да - няма закон, който да забранява такива дискусии.
А ако на костюмарите от ДАНС (кой знае утре Кой ще им го назначат за шеф) все пак им скимне подобна маркетингова щуротия би трябвало да започнат със затварянето на сайта на Института по Ядрени изследвания и Ядрена енергетика примерно (което ще е брутален гаф). А какво ли пък да кажем за форумите на Традиция или Криле, където освен за оръжие почти нищо друго не се дискутира?

Редактирано Януари 22, 2016 от Warlord

[Doris]

Преди 5 часа, Joro-01 said:

Много ми е интересно на тактически / военен БГ "spark plug" свещ ли ще се превежда. Това може на руски да се види, термнологията ни е предимно от там.

Аз скоро ще се ориентирам към технологията на правене, включваща и добива обогатяването и технологията / решенията, доколкото за последните има инфо. И доколкото е законно, да не вземат ДАНС да направят проблеми на форума / сайта.

Сещам се че например центрофугите са големи и трудно се крият от самолет / сателит. В тази връзка може смятам, че може да се познае какво има Северна корея (дано не залитнем към политика) и какво няма.

Преводи и/или терминини съкращения да добавяме ли? За някой трети примерно? Май няма нужда, но..

- High-Z материал - с голям пореден номер в периодичната система, сиреч тежък, с много протони..

- HEU - би трябвало да е високообогатен уран.

 

"Запалваща свещ" е , ама в кавички, защото иначе е кух цилиндър.

Наистина, информацията е общодостъпна, образователна.

Сещам се за онова момче с часовника в САЩ, дето го нарочиха, че е направило бомба  http://www.vesti.bg/sviat/amerika/zashto-obama-pokani-14-godishniia-ahmed-v-beliia-dom-6042659

Надявам се да няма чак такава параноя.

Мен повече ме вълнува отношението на учените, допринесли за  ядреното оръжие . Знаете, Айнщайн, Опенхаймер, Сахаров след като пуснаха духа от бутилката хукнаха да се борят за мир.

[nik1]

За обогатявянето:

Възможно ли е се направи атомно-взривно устройство с да кажем 20 % HEU (U-235)?

Критичната маса U-235 в този случай е 160 килограма , а общата маса на композита ("сплавта")  U-238/U-235 ще е 800 килограма. Това са изчисленията за сфера, и без рефлектор. 
При 10 cm Be-рефлектор, критичната маса U-235 се оценява на 49 килограма, а общата масата на материала е 245 килограма.

При тези условия може да започне верижна реакция (ако се абстрахираме от останалите зависимости и променливи за критичната маса https://en.wikipedia.org/wiki/Critical_mass), но как и с каква скорост ще протече тя (и ако за улеснение приемем, че дизайна е имплозивен)? 

Редактирано Януари 22, 2016 от nik1

[Очички]

Винаги е актуален отговора - Възможно е, но на каква цена?

[nik1]

Преди 31 минъти, Очички said:

 

Low-enriched uranium (LEU) contains between 0.7 percent and 20 percent uranium-235, and highly enriched uranium (HEU) contains 20 percent or more uranium-235. LEU is not directly usable for weapons. HEU produced for weapons ("weapon-grade" uranium) is typically enriched to 90 percent uranium-235 or greater, but all HEU can be used to make nuclear weapons. The difficulty and expense of the enrichment process has an important consequence: HEU can be diluted with natural uranium to produce LEU, effectively eliminating the risk that it could be used to make a nuclear weapon if stolen by terrorists.

However, as sophisticated enrichment technology spreads around the world, more groups will be able to overcome the technical barriers to producing HEU for weapons. For this reason, Pakistan's illicit transfer of advanced enrichment technology to Iran, Libya and North Korea is of grave concern to the international community. Moreover, the commercial enrichment facilities used to make LEU fuel for power reactors can be reconfigured to produce HEU for weapons. Without strong regulations in place, these dual-use facilities pose major risks of nuclear terrorism. In addition, the continued use of HEU for both civilian research and naval propulsion reactors increases the risk of terrorist access to this material.

[Joro-01]

Преди 7 часа, nik1 said:

За обогатявянето:

Възможно ли е се направи атомно-взривно устройство с да кажем 20 % HEU (U-235)?

Критичната маса U-235 в този случай е 160 килограма , а общата маса на композита ("сплавта")  U-238/U-235 ще е 800 килограма. Това са изчисленията за сфера, и без рефлектор. 
При 10 cm Be-рефлектор, критичната маса U-235 се оценява на 49 килограма, а общата масата на материала е 245 килограма.

При тези условия може да започне верижна реакция (ако се абстрахираме от останалите зависимости и променливи за критичната маса https://en.wikipedia.org/wiki/Critical_mass), но как и с каква скорост ще протече тя (и ако за улеснение приемем, че дизайна е имплозивен)? 

Няма да доведе до взривна реакция нв делене ли? Перфектна критична маса?  Ще започне да излъчва по-интензивно неутрони, но заради изразходването на енергия  ще се окаже с подкритична маса и ще истине?

[nik1]

Не мисля че реакцията ще спре, по-скоро не съм убеден, че реакцията ще протече със взрив. (и за улеснение да приемем че масата е надкритична  20% HEU , 1600 kg/320 kg)

Допускам хипотетично (но не съм сигурен, не зная), че реакцията ще е условно бавна /слаба - ще се отделя енергия с малка плътност (интензивност), а материалът само ще отделя топлина.

Допускам нещо подобно, поне физикално, на процесите в ядрените реактори (и в натуралните такива, без модератори) - там протичат, т.е. самоподдържат се верижни реакции на разпадане, /разцепване на ядрата се под действието на неутроните, с отделяне на неутрони при разцепването, които (или част от тях)  от своя страна разцепват други ядра/, но тези процеси не са взривни..

Въпросът ми по-скоро във връзка с обогатяването е "Къде, и каква  е границата между взривно протичане и невзривно (бавно) такова, има ли такава граница"?

Тук са направили някакви изчисления за натуралните реактори (геологически струпвания/находища на натурален уран, при които U-235 e с надкритична маса):

https://books.google.bg/books?id=6zDdamQYtlMC&pg=PA38&lpg=PA38&dq=critical+mass+of+uranium+at+10%25+enrichment&source=bl&ots=8DgEQvL9NV&sig=zAEwMHtCj-fckUf_xWZItPq7KLU&hl=bg&sa=X&ved=0ahUKEwiLutawob_KAhXKhSwKHQN4BmQQ6AEIUjAG#v=onepage&q=critical%20mass%20of%20uranium%20at%2010%25%20enrichment&f=false

 

Редактирано Януари 23, 2016 от nik1

[Joro-01]

Много рано ставаш. Аз те видях ама закуски, работи...

Мисля, че това се определя от отношението бързи - бавни неутрони

Prompt and delayed supercriticality[edit]

Not all neutrons are emitted as a direct product of fission; some are instead due to the radioactive decay of some of the fission fragments. The neutrons that occur directly from fission are called "prompt neutrons," and the ones that are a result of radioactive decay of fission fragments are called "delayed neutrons." The fraction of neutrons that are delayed is called β, and this fraction is typically less than 1% of all the neutrons in the chain reaction.^[10]

The delayed neutrons allow a nuclear reactor to respond several orders of magnitude more slowly than just prompt neutrons would alone.^[11] Without delayed neutrons, changes in reaction rates in nuclear reactors would occur at speeds that are too fast for humans to control.

The region of supercriticality between k = 1 and k = 1/(1-β) is known as delayed supercriticality (or delayed criticality). It is in this region that all nuclear power reactors operate. The region of supercriticality for k > 1/(1-β) is known as prompt supercriticality (or prompt criticality), which is the region in which nuclear weapons operate.

The change in k needed to go from critical to prompt critical is defined as a dollar.

https://en.wikipedia.org/wiki/Nuclear_chain_reaction

Редактирано Януари 23, 2016 от Joro-01

[Joro-01]

Тоест както разбирам - ако не се спазят условията - добавен отражател, обвивка от експозив за сферичен заряд (твоето устройство) или бързо събиране на двет или повече подкритични парчета  - да, реакцията ще протича бавно. Мисля за това е инициатора там - парчета Li и Be. Детонатор един вид.

В "конвенционалните" реактори източник на неутрони мисля няма. Има забавител и поглътител на неутрони.

Естествените реактори днес вече ги няма ако не се лъжа. Или греша?

Редактирано Януари 23, 2016 от Joro-01

[nik1]

Така де, отношение между бързи и бавни неутрони,
/мерси че го обясни ясно, то е защото закусваш сигурно, майтап де - ти си много ерудиран, и свързваш нещата бързо; аз пък не мога да се концентрирам едновременно и дори умишлено се стремя да забравям много от нещата които съм чел и срещал/.

Даже и мерна единица са му измислили https://en.wikipedia.org/wiki/Dollar_(reactivity),  ама  ми беше интересно дали с 20% HEU, и надкритична  маса може ли да се направи бомба? 

Май трябва да се ровим из нета - може да има разни модели,уравнения или по-прости обяснения и отговор, ама да не те занимавам днес (аз няма да мога да се занимавам)

=================

Не знам; Преди пет или повече години бях чел статия  за един натурален реактор в страната (някъде в Западна Африка), от която французите си доставят по-голямото количество от урана за атомните им станции.

Чао засега.

 

 

Редактирано Януари 23, 2016 от nik1

[Joro-01]

Мерси, ама не. Активен съм в няколко (под)форума само, а и справки правя бол. Тъй де, щото закусвам  

Попадне ли ми ще постна и може още днес. Tук не се товаря, но и другите неща трябва да вървят. Чао и от мене заега и хубав уикенд.

P.S. Мился че съм чел същата статия (или подобна) някъде тогава.  И само нея де, не съм се ровил...

[nik1]

Има го обяснено в монографията, ама кой да се задълбава толкова:

http://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html

Quote

 

4.1.4.1.2 Delayed Criticality

When the density has increased just to the point that a neutron population in the mass is self-sustaining, the state of delayed criticality has been achieved. Although nearly all neutrons produced by fission are emitted as soon as the atom splits (within 10^-14 sec or so), a very small proportion of neutrons (0.65% for U-235, 0.25% for Pu-239) are emitted by fission fragments with delays of up to a few minutes. In delayed criticality these neutrons are required to maintain the chain reaction. These long delays mean that power level changes can only occur slowly. All nuclear reactors operate in a state of delayed criticality. Due to the slowness of neutron multiplication in this state it is of no significance in nuclear explosions, although it is important for weapon safety considerations.

4.1.4.1.3 Prompt Criticality

When reactivity increases to the point that prompt neutrons alone are sufficient to maintain the chain reaction then the state of prompt criticality has been reached. Rapid multiplication can occur after this point. In bomb design the term "criticality" usually is intended to mean "prompt criticality". For our purposes we can take the value of alpha as being zero at this point. The reactivity change required to move from delayed to prompt criticality is quite small (for plutonium the prompt and delayed critical mass difference is only 0.80%, for U-235 it is 2.4%), so in practice the distinction is unimportant. Passage through prompt criticality into the supercritical state is also termed "first criticality".

4.1.4.1.4 Supercritical Reactivity Insertion

The insertion time of a supercritical system is measured from the point of prompt criticality, when the divergent chain reaction begins. During this phase the reactivity climbs, along with the value of alpha, as the density of the core continues to increase. Any insertion system will have some maximum degree of reactivity which marks the end of the insertion phase. This phase may be terminated by reaching a plateau value, by passing the point of maximum reactivity and beginning to spontaneously deinsert, or by undergoing explosive disassembly.

4.1.4.1.5 Exponential Multiplication

This phase may overlap supercritical insertion to any degree. Any neutrons introduced into the core after prompt criticality will initiate a rapid divergent chain reaction that increases in power exponentially with time, the rate being determined by alpha. If exponential multiplication begins before maximum reactivity, and insertion is sufficiently fast, there may be significant increases in alpha during the course of the chain reaction. Throughout the exponential multiplication phase the cumulative energy released remains too small to disrupt the supercritical geometry on the time scale of the reaction. Exponential multiplication is always terminated by explosive disassembly. The elapsed time from neutron injection in the supercritical state to the beginning of explosive disassembly is called the "incubation time".

4.1.4.1.6 Explosive Disassembly

The bomb core is disassembled by a combination of internal expansion that accelerates all portions of the core outward, and the "blow-off" or escape of material from the surface, which generates a rarefaction wave propagating inward from the surface. The drop in density throughout the core, and the more rapid loss of material at the surface, cause the neutron leakage in the core to increase and the effective value of alpha to decline.

The speed of both the internal expansion and surface escape processes is proportional to the local speed of sound in the core. Thus disassembly occurs when the time it takes sound to traverse a significant fraction of the core radius becomes comparable to the time constant of the chain reaction. Since the speed of sound is determined by the energy density in the core, there is a direct relationship between the value of alpha at the time of disassembly and the amount of energy released. The faster is the chain reaction, the more efficient is the explosion.

As long as the value of alpha is positive (the core is supercritical) the fission rate continues to increase. Thus the peak power (energy production rate) occurs at the point where the core drops back to criticality (this point is called "second criticality"). Although this terminates the divergent chain reaction, and exponential increase in energy output, this does not mean that significant power output has ended. A convergent chain reaction continues the release of energy at a significant, though rapidly declining, rate for a short time afterward. 30% or more of the total energy release typically occurs after the core has become sub-critical.

 

Ако е вярно че Delay-критичната маса при U-235 се отличава само с 2,4 процента от Prompt -критичната маса, и за практиката това не от значение,то следва че може да се използва 20 % HEU за направата на атомна бомба (поне теоретично),

Пак от монографията:

http://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html#Nfaq4.1.7.1

Quote

 

4.1.7.1 Fissile Materials

In the nuclear weapons community a distinction is made between "fissile" and "fissionable". Fissile means a material that can be induced to fission by neutrons of energy - fast or slow. These materials always have fairly high average cross sections for the fission spectrum neutrons of interest in fission explosive devices. Fissionable simply means that the material can be induced to fission by neutrons of a sufficiently high energy. As examples, U-235 is fissile, but U-238 is only fissionable.

There are three principal fissile isotopes available for designing nuclear explosives: U-235, Pu-239, and U-233. There are other fissile isotopes that can be used in principle, but various factors (like cost, or half-life, or critical mass size) that prevent them from being serious candidates. Of course none of the fissile isotopes mentioned above is actually available in pure form. All actual fissile materials are a mixture of various isotopes, the proportion of different isotopes can have important consequences in weapon design.

The discussion of these materials will be limited here to the key nuclear properties of isotope mixtures commonly available for use in weapons. The reader is advised to turn to Section 6 - Nuclear Materials for more lengthy and detailed discussions of isotopes, and material properties. See also Table 4.1.2-1 for comparative nuclear properties for the three isotopes.

4.1.7.1.1 Highly Enriched Uranium (HEU)

Highly enriched uranium (HEU) is produced by processing natural uranium with isotopic separation techniques. Natural uranium consists of 99.2836% U-238, 0.7110% U-235, and 0.0054% U-234 (by mass). Enrichment processes increase the proportion of light isotopes (U-235 and U-234) to heavy ones (U-238). Enriched uranium thus contains a higher percentage of U-235 (and U-234) than natural uranium, but all three isotopes are always present in significant concentrations. The term "HEU" usually refers to uranium with a U-235 of 20% or more. Uranium known to have been used in fission weapon designs ranges in enrichment from 80-93.5%. In the US uranium with enrichment around 93.5% is sometimes called Oralloy (abbreviated Oy) for historical reasons (Oralloy, or Oak Ridge ALLOY, was a WWII codename for weapons grade HEU). As much as half of the US weapon stockpile HEU has an enrichment in the range of 20-80%. This material is probably used in thermonuclear weapon designs.

The techniques which have actually been used for producing HEU are gaseous diffusion, gas centrifuges, electromagnetic enrichment (Calutrons), and aerodynamic (nozzle/vortex) enrichment. Other enrichment processes have been used, some even as part of an overall enrichment system that produced weapons grade HEU, but none are suitable for the producing the highly enriched product. The original HEU production process used by the Manhattan Project relied on Calutrons, these were discontinued at the end of 1946. From that time on the dominant production process for HEU throughout the world has been gaseous diffusion. The vast majority of the HEU that has been produced to date, and nearly all that has been used in weapons, has been produced through gaseous diffusion. Although it is enormously more energy efficient, the only countries to have built or used HEU production facilities using gas centrifuges has been the Soviet Union, Pakistan, and The United Kingdom. Pakistan's production has been very small, the United Kingdom apparently has never operated there facility for HEU production.

High enrichment is important for reducing the required weapon critical mass, and for boosting the maximum alpha value for the material. The effect of enrichment on critical mass can be seen in the following table:

Figure 4.1.7.1.1. Uranium Critical Masses for Various Enrichments and Reflectors
total kg/U-235 content kg (density = 18.9)
Enrichment       Reflector
(% U-235)  None        Nat. U       Be
                       10 cm      10 cm
93.5      48.0/44.5  18.4/17.2  14.1/13.5
90.0      53.8/48.4  20.8/18.7  15.5/14.0
80.0      68. /54.4  26.5/21.2  19.3/15.4
70.0      86. /60.2  33. /23.1  24.1/16.9
60.0     120  /72.   45. /27.   32. /19.2
50.0     170  /85.   65. /33.   45. /23.
40.0     250 /100   100  /40.   70. /28.
30.0     440 /132   190  /57.  130  /39.
20.0     800 /160   370  /74   245  /49.

The total critical mass, and the critical mass of contained U-235 are both shown. The increase in critical mass with lower enrichment is of course less pronounced when calculated by U-235 content. Even with equivalent critical masses present, lower enrichment reduces yield per kg of U-235 by reducing the maximum alpha. This is due to the non-fission neutron capture cross section of U-238, and the softening of the neutron spectrum through inelastic scattering (see the discussion of U-238 as a neutron reflector below for more details about this).

U-238 has a spontaneous fission rate that is 35 times higher than U-235. It thus accounts for essentially all neutron emissions from even the most highly enriched HEU. The spontaneous fission rate in uranium (SF/kg-sec) of varying enrichment can be calculated by:

     SF Rate = (fraction U-235)*0.16 + (1 - (fraction U-235))*5.5

For 93.5% HEU this rate (0.5 n/sec-kg) is low enough that large amounts can be used in weapon designs without concern for predetonation. If used in the Little Boy design (which actually used 80% enriched uranium, however) it would produce only one neutron every 31 milliseconds on average. No problem exists for any design up to the limiting size of gun-type weapons. 50% HEU on the other hand would be difficult to use in a gun-type weapon. A beryllium reflector would minimize the mass (and thus the amount of U-238 present), but to have a reasonable amount HEU present (e.g. 2.5 critical masses) would produce one neutron every 3.2 millisecs, making predetonation a significant prospect. The rate is never high enough though to make a significant difference for implosion assembly.

 

[Doris]

Превишаване на критичната маса се е случвало многократно на практика.

http://nuclearpeace.jimdo.com/%D1%80%D0%B0%D0%B4%D0%B8%D0%BE%D0%B0%D0%BA%D1%82%D0%B8%D0%B2%D0%BD%D0%BE%D0%B5-%D0%B7%D0%B0%D1%80%D0%B0%D0%B6%D0%B5%D0%BD%D0%B8%D0%B5/%D1%8F%D0%B4%D0%B5%D1%80%D0%BD%D1%8B%D0%B5-%D0%BA%D1%80%D0%B8%D1%82%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D0%B5-%D0%B0%D0%B2%D0%B0%D1%80%D0%B8%D0%B8/

Една драматизация, в която са съчетани първите 2 инцидента, тези със сферата-демон (мой превод на "Demon Core", не претендирам, че е най-удачния) :

 

 

Редактирано Януари 23, 2016 от Doris

[Joro-01]

Супер! + За линка и филма. Само че филма по-късно е го гледам. 

[Joro-01]

А сега ще прегледам нещата дето Ник бе така добър да намерии. В тези неделни утрини :)...

От нцидентите от Дорис, най-ми "хареса" този с канадския учен в америка, който за демонстрация е приближавал две подкритични плутонивеи полусфери и вместо специалния ограничител (срещу плътен контакт) е използвал обикновен отверка, която се е изплъзнала...

Нелепо!

Което ми напомня, да напомня, че процедурите трябва да се спазват колкто и безумни да изглеждат, особено ако работите в потениално опасни условия.

 

Редактирано Януари 24, 2016 от Joro-01

[Joro-01]

И още едно интересно ядрено оръжие - споменавано е тук някъде.. Рентгенов лазер. Използва за напомпване ядрен взрив, което значи че е еднократно. Направено е да нищожава балистичните ракети по време на полет, но срещу рояк (или флотилия? Няма да е ято  ) ракети няма да е много ефективно. Нещото трябва да се изведе в орбита

https://en.wikipedia.org/wiki/Project_Excalibur

http://epizodsspace.airbase.ru/bibl/popul-meh/2009/10/ejik.html

Проветът се казва Ескалибур- картинките са повече от руски изтоници.

 

М-да, това е от неуспешните проекти

Редактирано Януари 24, 2016 от Joro-01