Peace through practical, proved civil defence for credible war deterrence
  • Please see our post on the need to deter not only direct threats from nuclear attacks but also conventional wars and invasions that can escalate into nuclear wars (as proved by the use of nuclear weapons in WWII, for example, after they were developed during the war itself and did not trigger or provoke the war), linked here and here, and the true scaling law equivalence between a few thousand nuclear weapons and the several million tons of small conventional weapons in a non-nuclear world war as proved by our post summarising key points in Herman Kahn's much-abused call for credible deterrence, On Thermonuclear War, linked here.

  • Hiroshima's air raid shelters were unoccupied because Japanese Army officers were having breakfast when B29s were detected far away, says Yoshie Oka, the operator of the Hiroshima air raid sirens on 6 August 1945...

  • In 1,881 burns cases in Hiroshima, only 17 (or 0.9 percent) were due to ignited clothing and 15 (or 0.7%) were due to the firestorm flames...

  • Dr Harold L. Brode’s new book, Nuclear Weapons in ...

  • 800 war migrants drowned on 22 April by EU policy:...

  • Photographed fireball shielding by cloud cover in ...

  • Nuclear weapons effects "firestorm" and "nuclear w...

  • Proved 97.5% survival in completely demolished houses ...

  • Sunday, August 02, 2009

    Glasstone and Dolan nuclear crater sizes exaggeration


    ABOVE: The 1956 Australian-British Maralinga cratering nuclear surface burst, Buffalo-2, prepared for firing at Marcoo site.  The middle of the weapon is carefully aligned to the height of the ground surface.  Notice however that the weapon, despite of a low yield of just 1.4 kt, is a massive implosion device with a diameter of 5 feet.  The heavy weight of the implosion system and carrying cradle added mass for the "case shock" of the weapon as opposed to percentage of energy released as the X-ray emission; the altered partition of energy between bomb case kinetic energy and X-ray fireball energy dramatically increase the cratering and ground shock effects.  X-rays outside of the bomb have only a trivial effect on the ground, ablating a thin surface layer of the ground and heating up the air.  The downward portion of the dense case shock, on the other hand, embeds itself into the ground, coupling about half of the case shock kinetic energy into the surface and producing essentially of the crater and close-in ground shock energy.  Air-slap from the blast produces on a trivial effect on the crater and ground shock because of its relatively low density (the transfer of energy from an air shock wave into the ground is trivial because of the mismatch of acoustic impedance due to the fact that the ground is much denser than the air shock wave). Heavy weapons with a relatively small yield to mass ratio are thus far more effective at cratering than modern lightweight designs.  (This bomb design effect on cratering was proved by H. L. Brode and R. L. Bjork in their 1960 RAND Corporation report RM-2600, Cratering from a Megaton Surface Burst, but was never even mentioned in Glasstone's Effects of Nuclear Weapons.)


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    Above: Google satellite photograph of Runit Island in Eniwetok Atoll, showing two nuclear weapon test craters. The 105 m diameter, 11 m deep crater from the 18 kt Hardtack-Cactus surface burst nuclear test crater on Runit Island was used as a convenient nuclear waste dump during the decontamination of the Atoll in 1979, and was topped with a concrete dome, which is visible in the Google satellite photograph (click on image controls to zoom in or out). The 120 m diameter, 17 m deep water-filled crater in the reef seen in the photo above just beside Ruinit Island was formed by the 40 kt Redwing-Lacrosse nuclear test 17 feet over the reef on 5 May 1956.

    The 15 megaton Castle-Bravo test of 1 March 1954 and a later smaller test produced the two large overlapping craters shown below in the reef near Namu Island to the North-West of Bikini Atoll:


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    Above: the world’s first nuclear explosion-created freshwater lake, Lake Chagan. It was produced on 15 January 1965 at the edge of the Semipalatinsk Test Site in Kazakhstan using a 140 kt (96% fusion, 4% fission) thermonuclear weapon, detonated 178 m underground in saturated siltstone (12% water), employing a 6 kt fission primary stage. About 80% of the radioactivity was trapped underground and only 20% escaped into the atmosphere. The crater is 408 m in diameter and 100 m deep. The dose rate on the crater lip at 30 years after detonation was reported as 2.6 mR/hr, i.e. about 260 times the Earth’s average natural background radiation level of 0.010 mR/hr, with the lake water in the crater containing just 300 pCi/litre. On the 10 October 1965, they detonated a 1.1 kt nuclear bomb at 48 m depth in weak siltstone rock under the dry clay bed of the Sary-Uzen stream. The crater produced was initially 107 m in diameter and 31 m deep, but when flooded it slumped to 20 m depth and 124 m diameter. Some 96.5% of the fission products were trapped underground, and the crater lip had a dose rate of only about 2.5 R/hr at 5 days after detonation, decaying to 0.050 mR/hr (including natural background) at 30 years later. (Data source: Milo D. Nordyke, The Soviet Program for Peaceful Uses of Nuclear Explosions, Lawrence Livermore National Lab., UCRL-ID-124410, July 1996, pp. 13-15.)




    There are three reports now available online which throw light on the replacement to the Glasstone and Dolan Effects of Nuclear Weapons and its secret supplement Capabilities of Nuclear Weapons, Effects Manual EM-1:

    1. Kenneth E. Gould, A Guide to Nuclear Weapons Phenomena and Effects Literature, Kaman Tempo, Santa Barbara, CA., Technical Report ADB094426, DASIAC Special Report DASIAC-SR-206, 31 October 1984 which usefully states on page 5:

    'Capabilities of Nuclear Weapons, DNA EM-1 (Reference C-2), is the best single comprehensive reference on all aspects of nuclear weapon phenomena and effects. This classified two-volume set both complements and supplements The Effects of Nuclear Weapons. Volume 1 focuses on nuclear weapon phenomenology and Volume 2 covers nuclear weapon effects that are primarily of military interest. This major DNA handbook, often referred to by its report number "EM-1," was last published in 1972 (with minor revisions through 1981), but it is presently being completely revised. When updated, EM-1 will again serve its important role as a basic source document for the preparation of nuclear operational and employment manuals by the military services.'

    2. John R. Murphy, et al., Nuclear Effects Data Management and Analysis System (NEDMAS), DSWA-TR-96-94, Defense Special Weapons Agency, 1997, which gives some details of the new computer database for the effects of tests, and

    3. Ernest Bauer, Variabilities in the Natural and Nuclear Endoatmospheric Environment, Institute for Defense Analyses, Virginia, IDA Document D-1085, April 1992.

    Appendix A of this third report consists of a document by A. A. Fredrickson called Revision of DNA Nuclear Crater Specifications, taken from the September 1991 issue of Nuclear Survivability:

    DNA [Defense Nuclear Agency, which has since evolved into the DTRA] has recently completed an "end-to-end" cratering validation program that resulted in dramatic reduction of the crater size thought to result from the surface detonation of modem strategic weapons. Although a major field exploration and several underground nuclear tests conducted in this program occupied the spotlight, numerical simulations were in many ways more central to DNA's success. This article recounts the integrated role of the numerical simulations, re-interpretation of existing nuclear data, and additional field events in the evolution of DNA's view on nuclear cratering.

    DNA developed a crater specification methodology for its 1972 Capabilities of Nuclear Weapons - Effects Manual Number 1 (EM-1) with the acknowledgment that the nuclear database was incomplete and probably inappropriate for application to strategic yield surface burst weapons. The cratering events conducted at the Nevada Test Site (NTS) employed low yield sources suspected to produce larger craters than modern weapons of strategic interest. Data from the several high yield cratering events conducted at the Pacific Proving Grounds (PPG) were considered flawed by the atoll reef geology that was highly dissimilar to sites of interest. The 1972 EM-1 methodology was an attempt to reconcile these shortcomings.

    The strategic source surface burst crater specifications were based on high yield PPG data, calibrated to sites of interest by comparison of low yield nuclear and high explosive craters in various geologies. Figure A.1 depicts 1 Megaton crater profiles for two geology types as specified in 1972 EM-1. ...



    The numerical simulations indicated that strategic yield sources would produce craters one-third to one-fifth the scaled size produced in these events due to the relative inefficiency of the x-ray coupling process relative to hydrodynamic coupling. ...

    Today, DNA relies on numerical cratering and ground shock simulations as key integral parts of its experimental program. They are the basis for cratering specifications for near-surface bursts in EM-1, 1991. Figure A.5 compares 1991 EM-I craters on two geology types to the profiles perceived in 1972. This dramatic shift in perception is based on the compelling evidence obtained in the highly successful field program discussed in this article. The current DNA reliance on numerical simulations is a result of the recognition that they provided the motivation for this program, enabled the success of the field activities, and today provide the means to apply this test experience to specific strategic weapon and geology combinations of interest. ...


    In the earlier blog post (recently updated) on Glasstone and Dolan, I pointed out that, along with most effects, the crater predictions given by Glasstone and Dolan are massive exaggerations for high yields. There is a transition from cube-root explosive crater dimensions scaling at yields up to a few kilotons, to fourth-root gravity scaling in the megaton range. The cube-root scaling law occurs because the energy needed to heat, shock and explosively disrupt air or soil is directly proportional to the mass of that air or soil. Thus, the volume of ambient air or soil subjected to a particular shock overpressure scales in directly proportion to the energy of the explosion; which means that the radius of that volume scales in proportion to the cube-root of the explosion energy.

    For high yield surface bursts, however, there is another vitally important use of energy in order to excavate a big crater: the energy needed to do work against gravity in order to raise the mass of dirt from the hole and dump it outside to form the 'lip' and 'ejecta' region around the crater (afterwind lofted fallout dust is merely ~1% of the crater mass). This energy is simply E = mgh where m is the cratered mass raised average height h against gravitational acceleration g. Taking this into account means that for high yields h and particularly m both become very large, so that the gravitational work energy needed to form a massive crater is immense and can then exceed that of the explosive break-up of the soil. (For low yields, the gravitational work energy is trivial compared to that used to break up the soil explosively, because of the smaller mass and smaller crater depth.) If the crater diameter to depth ratio is constant, then the cratered mass m is proportional to the cube of the depth h, or m = bh3 where b is a constant, so E = mgh = bh3gh = bh4g. Rearranging, h ~ E1/4 for high yields. There are other factors involved of course, because the amount of energy used for cratering is essentially the downward-directed case-shock energy of the bomb debris (the air blast doesn't have enough density and thus enough momentum to dig out the crater, it just causes some compression). This is a limited fraction of the explosion energy, so the energy utilization in explosively heating, compressing and breaking up the crater material limits the energy available for ejecting it against gravity. This energy balance will usually be accompanied by some change in the ratio of crater diameter to depth, so the craters will not always exactly behave the fourth-power scaling law in the megaton range. Nevertheless, there is a massive exaggeration of high-yield crater sizes in the Effects of Nuclear Weapons 1977 and related documents.

    The earliest mainstream American statement made that crater dimensions theoretically scale as W1/4 for the regime in which gravity is important is by Dr Milo D. Nordyke of the Lawrence Radiation Laboratory in Cratering Experience with Chemical and Nuclear Explosives (published in Proceedings of the Third Plowshare Symposium, Engineering with Nuclear Explosives, April 21, 22, 23, 1964, U. S. Atomic Energy Commission report TID-7695, TID-4500 (UC-35), pages 51-53. Nordyke states there on page 52: "... the analysis that leads to W1/3 ignores the action of several factors such as gravity and the strength or internal frictional forces of the medium. ... one can show that their effect would be to lower the exponent and lead toward W1/4 scaling (reference: L. I. Sedov, Similarity and Dimensional Methods in Mechanics, Gostekhizdat Press, Moscow, 1954 and Academic Press, New York, 1959, page 251)."

    However, Nordyke did not identify the W1/4 as applying to the gravity regime for large megaton range explosions that excavating large masses of ejecta over large vertical distances against gravity, and the W1/3 law holds for relatively small craters in the sub-kiloton range. Instead, he argued for an interim value of the exponent between the values of 1/3 and 1/4, of about W1/3.4 ~ W0.3 from empirical data for Nevada desert alluvium. This fudge factor leads to inaccurate extrapolations from the Nevada test data.

    Further reading:

    ‘Data on the coral craters are incorporated into empirical formulas used to predict the size and shape of nuclear craters. These formulas, we now believe, greatly overestimate surface burst effectiveness in typical continental geologies ... coral is saturated, highly porous, and permeable ... When the coral is dry, it transmits shocks poorly. The crushing and collapse of its pores attenuate the shock rapidly with distance ... Pores filled with water transmit the shock better than air-filled pores, so the shock travels with less attenuation and can damage large volumes of coral far from the source.’


    – L.G. Margolin, et al., Computer Simulation of Nuclear Weapons Effects, Lawrence Livermore National Laboratory, UCRL-98438 Preprint, 25 March 1988, p. 5.

    ‘It is shown that the primary cause of cratering for such an explosion is not “airslap,” as previously suggested, but rather the direct action of the energetic bomb vapors. High-yield surface bursts are therefore less effective in cratering by that portion of the energy that escapes as [X-ray] radiation in the earliest phases of the explosion.’


    - H. L. Brode and R. L. Bjork, Cratering from a Megaton Surface Burst, RAND Corp., RM-2600, 1960.

    D. E. Burton, et al., Blast induced subsidence in the craters of nuclear tests over coral, Lawrence Livermore National Lab., UCRL-91639, 1985:

    “The craters from high-yield nuclear tests at the Pacific Proving Grounds are very broad and shallow in comparison with the bowl-shaped craters formed in continental rock at the Nevada Test Site and elsewhere. Attempts to account for the differences quantitatively have been generally unsatisfactory. We have for the first time successfully modeled the Koa Event, a representative coral-atoll test. On the basis of plausible assumptions about the geology and about the constitutive relations for coral, we have shown that the size and shape of the Koa crater can be accounted for by subsidence and liquefaction phenomena. If future studies confirm these assumptions, it will mean that some scaling formulas based on data from the Pacific will have to be revised to avoid overestimating weapons effects in continental geology.”


    Another source of information on the revision of crater dimensions is pages 136-139 of the 1993 book by Bruce G. Blair, The Logic of Accidental Nuclear War, published by the Brookings Institution, online here:

    “Recently the U.S. Department of Defense reviewed the pertinent historical evidence gathered during nuclear tests and developed new models of the vulnerability of underground structures to nuclear explosions. These calculations differed substantially from those derived from earlier models. For example, the dimensions of a crater produced by a nuclear explosion were estimated to be considerably smaller than previously thought. To give a specific comparison, the radius of a crater produced by a one-megaton nuclear explosion on the surface of wet soil would be 651 feet according to the old formula, whereas the new formula estimated the radius to be 394 feet. ... Comparable differentials typically hold across the spectrum of weapon yields and soil varieties. ...

    “... Under the new formula the pertinent calculations for this location’s geological composition (dry soft rock, according to U.S. analysts) indicate a crater radius of only 180 feet for a one-megaton weapon, or 262 feet for a nine-megaton weapon.”


    Notice that an increase in crater radius from 180 to 262 feet for a yield increase from 1 to 9 megatons implies a crater scaling power law of W0.171, i.e. 180(9 Mt / 1 Mt)0.171 = 262 feet.

    Holsapple’s online crater scaling program

    Keith A. Holsapple has a very nice and useful online crater scaling program at http://keith.aa.washington.edu/craterdata/scaling/index.htm which allows you to predict crater sizes for comet and asteroid impacts, chemical explosives, and also any yield and burst conditions from two types of nuclear weapon design:

    (1) “high weight/energy ratio” inefficient low yield devices typical of early kiloton Nevada tests with a mass to yield ratio of 10 kg/kt, and

    (2) “low weight/energy ratio” efficient high yield modern thermonuclear weapons with a mass to yield ratio of 0.42 kg/kt).

    He also includes TNT, which of course has a massive weight to yield ratio of 1,000,000 kg/kt by definition. The dense explosion debris embeds itself deeply into the ground, delivering energy deeply into the ground far more efficiently than X-rays which just ablate a surface layer and cause a rapidly attenuated ground shock by the recoil from ablation. Efficient (high energy/weight ratio) nuclear weapons release most of their energy initially as X-rays not the kinetic energy of the dense debris shock wave, so they do not couple much energy deeply into the ground to cause a crater. As a result, high yield modern nuclear weapons use a much smaller proportion of their energy for cratering than inefficient low yield weapons or TNT chemical explosive.

    Holsapple gives a sketchy account of the theory in his paper Theory and equations for
    “Craters from Impacts and Explosions”
    online here: http://keith.aa.washington.edu/craterdata/scaling/theory.pdf which for nuclear craters cites:

    K. A. Holsapple and S. Peyton, The Scaling of Nuclear Weapons Effects for Near Surface Bursts, Defense Nuclear Agency report DNA 6543F (1987), and

    R. M. Schmidt, K. R. Housen and K. A. Holsapple, Gravity Effects in Cratering, Defense Nuclear Agency report DNA-TR-86-182 (1988).

    The approach Holsapple used is the scaling of experimental data through the use of dimensional analysis where the data is allowed to determine the scaling law at high yields, rather than fitting the data to determine coupling constants in a purely physical, mechanistic scaling model based on energy utilization. His equations 6 and 7 show that at low energy yields, the crater size is a stronger function of yield than at higher yields. The low yield limit is called the “strength regime” and crater sizes scale approximately as the cube-root of yield in this regime; at higher yields the scaling is in the “gravity regime” which is a weaker function of yield, closer to the fourth-root. Holsapple in equation 7 gives a “general form with those limits and that interpolates between these two regimes”.

    One problem is that he gives no derivation of the interpolative formula 7, and another problem is that the limits for the strength regime and gravity regime are not fixed theoretically as cube root and fourth root scaling in his formula, but are defined by experimental data. This is similar to modelling thermal radiation through the atmosphere by simply modifying the inverse-square law to fit the data, e.g. taking the thermal radiation to fall as say 1/R2.5, instead of adding an exponential term to allow for absorption and scattering by the atmosphere in addition to the inverse square law.

    The problem is that we know from physical energy utilization principles that the laws of nature are due to fixed mechanisms and should be fixed theoretically. Variations in the experimental data should be used not to vary the scaling laws provided by the physical mechanism, but instead to determine the physical constants. At low yields, a unit amount of cratering energy excavates a unit mass of soil or rock. If the soil or rock has fixed density, the crater volume at low yields is then directly proportional to the energy yield. By geometry, the radius of a hemisphere is proportional to the cube-root of its volume. If the crater radius-to-depth ratio is a constant, this cube-root law applies to other shapes, too.

    Hence, at low yields the cratering theory needs to be tied to the cube-root. At high yields, the influence of gravity is that most of the available cratering energy must be used up in shifting soil or rock out of the massive crater. The energy needed to lift crater mass M up to vertical distance to the lip D against the force of gravity F = Mg is simply E = FD = MgD. This is just a physical fact of nature. Since for a constant crater radius-to-depth ratio, the mass M is proportional to D3, we get E ~ D3D ~ D4, hence at high yields the energy used to overcome gravity predominates. The full equation for the utilization of energy is:

    E = AD3 + BD4,

    where the first term on the right hand side (containing D3) is the energy needed to hydrodynamically excavate the mass of the crater (this energy is directly proportional to the mass of the crater or to the cube of the crater dimensions), and the second term on the right hand side (containing D4) is the energy needed to overcome gravity and dump the excavated soil on the surrounding ground to form the crater lip and ejecta zone. So this is the simplest way to model craters: just use the experimental data to determine the values of constants A and B. Instead of this energy utilization and physical mechanism based approach, Holsapple allows the experimental data to vary the values of the powers that in fact should not be allowed to vary unless the radius-to-depth ratio of the crater varies.

    The crater scaling formula that Holsapple gives allows the excavated volume of the crater to vary linearly with bomb yield at low yields (“strength regime”), correctly giving W1/3 scaling for linear dimensions, but at high yields it gives a scaling law of W{mu}/2 where {mu} should theoretically be equal to ½ from the physical laws of nature as they are known for constant radius-to-depth ratio craters to give the W1/4 scaling law at high yields (gravity regime). By letting {mu} vary according to the explosive and impact cratering data in his database, however, Holsapple gets differing values for {mu}, from 0.41 for dry soil to 0.55 for wet soils, soft rock, hard soil and hard rock. For {mu} = 0.55, the scaling law for the high yield (gravity regime) asymptote will be W0.55/2 = W0.275 instead of the physically defensible W1/4 which is needed for energy conservation! Moreover, the data in Holsapple’s database are mainly data for the strength regime. He doesn’t have strong evidence of a departure from the natural W1/4 scaling law. So we disagree with the scaling procedure unless {mu} is taken as ½ and the experimental data is just used to constrain the values of the other variables in the scaling procedure. The dimensional analysis formula used to interpolate in the all-important transition zone (which spans the most important yield range for nuclear weapons) from strength to gravity scaling, is also suspect, and we would prefer a simple physical prediction system based on energy utilization between the hydrodynamic break up of the ground and the work against gravity in ejecting debris to form the lip and ejecta zone (as outlined in an earlier post, linked here).

    However, online calculations using Holsapple's computer program does provide some interesting updates to our information. Holsapple's computer calculation for explosion cratering works by using an equation based on dimensional analysis and data to predict crater excavation volumes for four different kinds of soil: dry soil, wet soil, hard soil/soft rock, and hard rock. The crater excavation volume is constrained to be directly proportional to bomb yield for very low, sub-kiloton yields (the "strength regime", corresponding to cube-root scaling for linear dimensions such as depth and radius) but less than directly proportion to yield for very high yields such as in the megaton range (the "gravity regime", where we argue that the energy to excavate against gravity is E = mgh ~ [volume]*[volume]1/3 ~ [volume]4/3 so that [volume] ~ E3/4, which makes linear dimensions scale as E1/4).

    For example, for TNT (not nuclear explosive) surface burst (with the charge half-buried in the ground, so that the centre of the explosion at at ground level), Holsapple's computer program shows that at TNT yields equal to or less than 100 kg, the excavated volume in dry soil is 39,570Wkt cubic metres. But if you increase the yield to 1 kt of TNT explosive, you don't get a crater of 39,570 cubic metres, but only 16,600, because gravity effects are already starting to kick in. This figure of course is bigger than for a nuclear explosion.

    Holsapple's model shows that the crater excavation volume for a low weight-to-energy ratio nuclear weapon (0.4186Wkt kg bomb mass) is actually 10 times less than for a high weight-to-energy ratio nuclear weapon (10Wkt kg bomb mass) and is 25 times smaller than the crater volume produced by 1 kt of actual TNT (1,000,000Wkt kg bomb mass).

    For example, the crater volume for a 1 kt low mass-to-energy ratio nuclear warhead surface burst on dry soil is 664 m3, compared to 6,640 for high mass-to-energy ratio nuclear warhead, and to 16,600 for actual TNT.

    The heavier the bomb mass, the more efficient is the cratering effect, because more energy is carried downwards on dense, high-momentum bomb debris that embeds itself into the ground and delivers energy efficiently, unlike the X-ray surface ablation and the blast wave reflection from the ground, which produce a ground shock but no cratering. For the low mass-to-energy ratio nuclear warhead (which produces the significant smallest cratering action) on dry soil, Holsapple's program gives the following crater excavation volumes as a function of total yield:

    1 kt: 664 m3
    10 kt: 4,680 m3
    100 kt: 32,200 m3
    1 Mt: 220,000 m3
    10 Mt: 1,490,000 m3

    Once the volume is calculated by the semi-empirical dimensional scaling equation, the program uses that volume to find the other crater parameters. Holsapple states that the density of dry soil is 1.7 grams/cm3, but calculates the mass of crater ejecta as 80% of that (1.36 grams/cm3) because not all of the crater volume is formed by ejecting material: there is also a soil compression effect below the bomb, and this accounts for the other 20% of the crater mass (which is compressed downward instead of being ejected out of the crater). This 80% figure is applied to all types of soil.

    The density of dry soil is 1.70 grams/cm3, but as stated only 80% of the crater volume is ejected so the mass of ejecta per unit volume is 0.8*1.70 = 1.36 grams/cm3. For wet soil, hard rock and soft rock, the density is 2.10 grams/cm3, and the ejected mass to volume ratio is 0.8*2.10 = 1.68 grams/cm3. For hard rock, the mass density is 3.20 grams/cm3, and the ejected mass to volume ratio is 0.8*3.20 = 2.56 grams/cm3.

    In all cases of weapon type and soil type, Holsapple's model uses the following relationships to calculate crater dimensions from the crater excavation volume V:

    Apparent crater radius, Ra = 1.10V1/3
    Rim radius, Rrim = 1.30Ra
    Apparent depth, Da = 0.60V1/3
    Average lip height, Hlip = 0.17Da
    Crater formation time, Tformation = 0.8V1/6/g1/2 where acceleration due to gravity g = 9.81 ms-2 for Earth. (Most of the crater volume is ejected within a couple of seconds for any nuclear explosion, since the time taken is a weak function of yield.)

    Information on the distribution of crater ejecta velocities is also provided. For a low mass-to-energy ratio nuclear weapon surface burst on dry soil, 50% of the ejecta exceeds 13.5 m/s for 1 kt or 30.1 m/s for 1 Mt.

    For extremely high yields, there is a transition to "complex" craters like lunar craters, having a wide shallow basin and a central peak. Complex craters have their shape because they are too large for all the excavated material to be dumped at the lip; the fallback of ejecta in the centre of the crater is then so substantial it causes a central peak in the middle of the crater.

    On the Earth, crater exceeding a rim diameter exceeding 1.77 km for dry soil would start to transition into "complex" craters. Obviously, there is a difference in this between Earth and Moon because there are no significant afterwinds in an explosion caused by an impact event on the Moon: there is a lack of atmosphere. But on the Earth, a large explosion near surface level causes a toroidal fireball to form due to air drag on the sphere, and you then get debris being sucked into the toroidal circulation via a mushroom "stem" above ground zero. On the Moon, which has only one-sixth of the surface gravity of the Earth, the transition from simple to complex cratering occurs at a rim diameter of 8.5 km. These complex craters are more relevant to impact cratering like the K-T event 65.5 million years ago, than to the relatively trivial energy releases of stockpiled nuclear explosives.



    Peaceful cratering: the U.S. Atomic Energy Commission’s Project PLOWSHARE

    After the fallout from the CASTLE-BRAVO 14.8 megaton Bikini Atoll hydrogen bomb produced media hysteria over the effects of thermonuclear weapons, President Eisenhower responded by ordering the development and testing at Bikini Atoll of REDWING-NAVAJO of the 95 % clean 4.5 megaton hydrogen bomb. Aside from averting collateral damage from fallout in tactical nuclear war to defend Western Europe from invasion by the massive conventional Soviet block armies, this kind of cleaner weapon was also intended for peaceful civil engineering use as a cratering explosive. The first peaceful underground PLOWSHARE test in 1957 was such a success that it convinced America to move above ground nuclear testing underground to avoid fallout radiation hazards.

    John Lindsay-Poland’s book Emperors in the jungle: the hidden history of the U.S. in Panama (2003) gives in Chapter 3, “The Nuclear Canal”, a critical but detailed example of another PLOWSHARE cratering project in the story of this peaceful use of the clean hydrogen bomb.

    This plan was to set off 275 relatively clean hydrogen bombs to cheaply (at an estimated cost of roughly one billion dollars, which was cheap compared to the cost of using conventional explosives) create a new sea-level (without any locks) Panama canal in the Darien region, near the border with Colombia. The existing Panama canal has locks and isn’t at sea-level, so it takes a long time for ships to pass through it, making it slow and expensive for ships to use to cross from the Atlantic to the Pacific Ocean.



    View Larger Map

    Above: in order to proof-test nuclear cratering for a new Panama canal, the 30 % fission, 104 kt total yield PLOWSHARE-SEDAN nuclear test was detonated at 635 feet depth (to optimize cratering efficiency and minimize fallout by trapping the radioactive case shock debris in the crater ejecta) in the dry soil of the Nevada Test Site on July 6, 1962. Although SEDAN was a success, the soil around some of the proposed Panama canal routes was not dry soil but saturated clay, which can create a wider, shallower shaped crater than dry soil. Hence, to get the depth required, higher yields than SEDAN would have been required for a new Panama canal. This would have increased the distant blast wave refraction effects (downwind of the high altitude winds), the ground shock (earthquake-type) effect, and fallout (although it is easier to reduce fission yield at very large total yields than very small ones, for instance the 50 Mt Soviet test was only 2-3 % fission). Both the distant blast and fallout effects could have been averted by postponing detonation until the winds were blowing out to sea, but ground shock effects from the large number of simultaneous high yield underground nuclear detonations required might have damaged the nearby existing Panama Canal, depending on the exact route taken, the distance, and the distribution of bomb yields used. The project was finally cancelled in 1971 due to lying propaganda about alleged low-level radiation effects in the popular media.

    OTHER SOURCES OF INFORMATION ON CRATERING:

    Patteson, A. W, Physical Characteristics of Craters from Near-Surface Nuclear Detonations, report AD0360630, 1960.

    Proceedings of the Third Plowshare Symposium Engineering with Nuclear Explosives Held in Davis California on April 21-23, 1964, University of California report ADA396463, 1964.


    24 Comments:

    At 10:18 am, Blogger nige said...

    25 January 2011:

    I have just deleted a submitted comment which began

    "In fact 1000-megaton ground bursts were studied in ca.1958. They described in The Search for New USAF Weapons, 1958-1959. (S) Arthur K. Marmor. 1961. 66 pp. But unfortunately this doc. still classified ( I have doc.that cited this). It was predicted very heavy fallout from ca.85% fission 1gt ground burst with lethal exposures in neighbour countries. What you can say about this?"

    Please don't anonymously refer to unavailable classified documents and request discussion of what you allege they say.

    However, a 1000 megaton surface burst will produce fallout that is distributed by the weather.

    The fallout is easier to see and more effectively decontaminated in large quantities like snow, than small quantities of tiny particles that are hard to see and lodge in small (quickly filled up) surface irregularities.

    There is extensive data on fallout decontamination beginning with the Jangle Sugar and Uncle nuclear tests in Nevada, 1951.

    High yield dirty bombs produce a lot of easily-shielded low gamma ray energy emitters Np-239 and U-237 due to neutron in U-238.

    You anti-civil defense guys know nothing about the effectiveness of radiation shielding of improvised cover. Just line some boxes with plastic bags, fill with water, and place on and around a table as far from the outer walls and roof of a building as possible. Arrange furniture around it for further shielding. Build a self-calibrated KFM to measure the radiation dose rate accurately while waiting for the radiation to decay to say 0.5 R/hr (which Glasstone and Dolan state is the threshold for genetic defects in female mice). Then go outside and decontaminate. Google "Dr Carl F. Miller" for more details. There are lots of U.S. Naval Radiological Defense Laboratory reports on different kinds of fallout decontamination effectiveness available now.

     
    At 11:59 am, Anonymous Anonymous said...

    It is referred to in the FOIA declassified report

    http://www.governmentattic.org/docs/Guide_USAF_Hist_Lit_1983.pdf

    "Guide to Air Force Historical Literature, 1943 – 1983,
    29 August 1983"

     
    At 1:41 pm, Anonymous Anonymous said...

    Marmor probably only give a summary of this study or even only ment. this study,since as pages about this weapon.19-21.
    Study was done by Air Staff.It was ordered in march 1958 by Gen.T.White(USAF Chief of Staff).
    You think that these people were anti-civil defense guys?

    As for clean boms-they were only a fake political propaganda .
    Clean bomb for same yield would be in 3-5 times heavier than standard bomb.So USAF was no happy with such things.They never been deployed.In fact fallout was considered only as bonus,most strikes that were planned in 1956,1957 SAC plans and SIOP-62 were ground bursts on counterforce targets.20mt was a smallest yield needed to crater runways and this was based on contemporary estimates of size of crater,that were exaggerated.So in fact at this time constraints on fallout were mostly ignored by USAF.Were studies about fallout as primary deterent of general war.But USAF was not interested in this-fallout have been considered only as BONUS EFFECT.This was changed in McNamara era ,but mostly large weapons were replaced with smaller ones or air bursts were used,this again was no place for clean bombs.
    Information about MK36Y2 or C with 6 mt yield compared to 19mt or 20mt(mod2) may be fake.

    P.S. Total numbe of DGZ in SIOP-62 was 1073,373 were cities (295-Soviet,78 -Chinese).Fatalities were predicted -54% of Soviet population and 16% of Chinese population.

     
    At 3:24 pm, Blogger nige said...

    Anonymous,

    You need to press the space bar on your keyboard after typing a comma or full stop, please.

    I've read the declassified portions of SIOP-62, and you're wrong.

    USAF wanted dirty (U238 tamper) bombs because they gave the biggest total yield per ton of bomb weight for cold war deterrence against a general war.

    The SIOP-62 specifies deliberately limiting collateral damage to civilians in friendly neutral countries (maximum permitted outdoor gamma dose = 150 R, which would be reduced to a trivial amount indoors in a well-shielded inner core refuge surrounded by furnishings).

    The SIOP-62 does not specify maximizing fallout effects against civilians, which would involve waiting for favorable wind patterns and rain patterns for an attack. This is not done in the plan!

    The fallout "bonus" you refer to is fake. They aren't even trying to detonate in blue skies to maximise thermal casualties.

    All they plan to optimize are blast and cratering effects against military and key government and industrial/military weapons production factories.

    Clean bombs were developed in the shape of the 0.020 kt W-54 Davy Crockett of the 1960s (2,100 deployed to defend Europe) and the 3 kt neutron bomb of the 1980s.

    You are very badly informed about the use of clean nuclear weapons. Do you know how the local fallout falls off very rapidly with increasing height of burst? Even when the fireball touched the ground in the 1953 "Grable" canon-shot test (15 kt at 524 feet detonation altitude), only 1% of the bomb debris came down in the local fallout radiation pattern! It was a very clean shot although it was 100% fission!!!!

    Same for 1956 3.8 Mt, 50% fission Cherokee air burst at 4,350 ft detonation altitude. Triffet (weapon test report WT-1317) had ships, barges and survey aircraft in the fallout pattern downwind at various distances. Peak dose rate from fallout was just 0.2 mR/hr!!

    So don't believe a word Chuck Hansen and Howard Morland write about the inevitably devastating fallout effects of nuclear weapons. They do not write competently on nuclear effects.

     
    At 4:11 pm, Anonymous Anonymous said...

    I'm now very busy....But fallout bonus not fake,see for example:
    Letter from Captain John H. Morse, Special Assistant to the Chairman, Atomic Energy Commission, to Lewis Strauss, Chairman, Atomic Energy Commission, 14 February 1957, Secret
    Source: Dwight D. Eisenhower Library, Records of Special Assistant for National Security Affairs, NSC Series, Briefing Notes Subseries, box 17, Target Systems (1957-1961)and The Engineer studies center and army analysis. A History of the US Army Engineer Studies center 1943-1982 by William C. Baldwin" .1982 and reference therein about fallout bonus and these studies.

    For thermal casualities ,well:The second-strike capability was quite different.11 Dyna Soars and their launch vehicles would form a single unit ;10 would be unmanned and 1 manned control vehicle.Once launched into storage 100 n.m. high
    orbit,no futher communications from the ground would be strictly necessary:the 3-man crew would be capable of controling whole unit.
    Each unmanned Dyna Soar bomber had single 20 megaton (weighning 3500 pounds),a 5000 pounds thrust turbojet and 3000 pounds of fuel.On command,bomber would re-enter,drop to subsonic speed and start the turbojet ,after that it would fly the last 250 miles n.m.at low alltitude (below radar ) using terrain-mapping radar for guidance to within 400 feet of the target.

    An alternate version meant for high-altitude detonation (for taking out soft targets,i.e. cities) would delete the jet engine in favor for of a 40 megaton bomb.
    Future version (one of many) would be stricly a ORBITAL BOMB with 15000 pound device (compare to 20mt in 3500).

    "According one source a single Pluto could carry a 5500-pound payload which could be broken down like this :
    1-26megatons
    5-1.3 megatons
    9-1.1 megatons
    14-750 kilotons
    16-200 kilotons
    36-50 kilotons
    42-5 kilotons. "And this only small version larger version with Tory -III reactor could carry 15000-pound payload -or 1 weapon 15000 pounds or 26 1.1mt warheads.And Pluto itself very evil weapon without warheads.
    All these high-yield devices 20mt,26,35mt(planned Titan2 warhead),40mt,60mt and at 15000 pound weight (this unclear whether 3500 pounds -device weight ,500 pounds may be drop case weight,such were st. that 60 mt would weigh around 9000 pounds,so then 15000 pounds would have 100mt,even if 3500 and 10500 weights of 20 and 60mt,for 15000 pounds yield would be staggering.) and other belongs to new family of high-yield devices of LLNL in 1962.
    And this probably no limit in ratios.It was stated that fission contributions in these weapons decreased to few percents!

    Damned McNamara and other illuminati,they canceled all these things!

     
    At 6:12 pm, Anonymous Anonymous said...

    If you not want to publish my comm.for some reason you may say something about means to achieve such high ratios .This data from dec.docs,I'm not have them already ,but i'm have compilation and extraction from them.
    So what about 3000-3500 pound 20mt warhead with probably most. from fusion?

     
    At 9:50 pm, Blogger nige said...

    Hi Anonymous,

    Again, you need to take a look at the physics of nuclear weapons effects to see why high yield nuclear weapons are extremely ineffective:

    1. In a desert over over ocean, the area of overpressure (diffraction) damage scales as yield^(2/3), so if you increase yield 1000 times, the area damaged only increases 100 times. The crater area at very high yields scales as typically yield^(1/2), so increasing yield 1000 times only increases crater areas by 32 times.

    2. In a city, the yield scaling is an even weaker function of bomb yield, because of the cumulative loss of energy from the blast in knocking over buildings and accelerating debris. The blast can't cause destruction without energy being lost. This cumulative energy loss gets very large over large areas of buildings for big yields, so the blast loses its power sooner than over a desert or ocean in a test.

    3. In a surface burst, there is a massive reduction of thermal radiation due to the cratering and fallout particle melting effects, which uses up fireball energy.

    4. As yield increases, the total amount of fission products increases, but the cloud height also increases so that fallout takes longer to arrive near ground zero and more decay occurs in the interim. Similarly, as the downwind distance form any dose rate is increased by bigger yields, the arrival time is also increased since it depends (far downwind) on the windspeed which isn't a function of the bomb power. So the fallout takes longer to arrive, and more of the radiation decays while the fallout is in transit to the distant downwind location. People have time to evacuate if they are downwind, or to improvise good radiation shielding while awaiting fallout arrival. They might even have time to set up hose pipes and "washdown" decontamination gear to wash fallout off buildings as it landed, reducing the roof dose rate. On sloping roofs, water can sometimes be used to wash fallout off. On flat roofs, fallout can be swept off.

    Again, I think you are falling for the "sitting duck" fallacy of the 1930s era, when the military and the pacifists both agreed (wrongly!) that if British we fought a preventative war against the Nazis, it would be the worst nightmare possible, with no protection possible against gas, incendiary bombs and high explosives, and a predicted casualty toll of 1 million people in Britain every month.

    This prediction was wrong. The Nazis destroyed over a million British houses, but the casualty toll was 60,000, or under 2% of the population whose homes were destroyed. People survived under strong tables, in improvised low-cost shelters, and such like. It's very hard to kill a large percentage of the people with high explosives, gas, or nuclear weapons once they disperse and take good (but cheap and simple) countermeasures. As I blogged in another post about the exaggerations of weapons effects in history, trench shelters allowed the Confederates to stand out the Seige of Petersburg in the American Civil War, 1864-5. They were only defeated when attacked from a flank. This trenches lesson was ignored by German military in their planning for WWI, which was why WWI dragged on in trench war and they lost (they prepared for a short war using big guns for a knockout blow).

    Machine guns make soldiers quickly drop down and take cover, stalling a massed attack. They don't mean that you can shoot people who have taken cover. There are limits to all technology in war. What counts as much is having the stamina to hold out, not just hinding behind a big pile of "deterrent weapons" that are completely incredible and useless for deterrence due to political BS.

     
    At 5:59 pm, Anonymous Anonymous said...

    1000-megaton weapon also described in :Lee Bowen and Robert D.Little,History of the Air Force Atomic Energy Program(TS),(AFCHO,1959)Vol.IV pp.486-487,and Hist(TS),Dir/Plans,Jul-Dec 1958,pp.11-14.
    Dir/Plans mean Directorate (Director of Plans).
    So this device existed on paper.

    You,of course right smaller weapons more effectife for MAD,but MAD not existed at this time.
    So what would be effects of this weapon on Moscow basine and bunkers?

    And you not ask my question -Why in large devices ( with more stages than in smaller ones) ratios higher? Or better, why with adding additional stage ratio increased?

    P.S. You blog probably the best source for data on weapon effects in entire WEB.But why only nuclear ? May be effects of chemical and biological weapons would a better addition,since as they much cheaper and better accessible for terrorists.

     
    At 7:17 pm, Blogger nige said...

    Generally you'd expect efficiency to be maximized in high yield devices because the bomb reaches higher temperatures and pressures, allowing a greater percentage of the deuterium and tritium to be fused, and the neutron fluence is greater, allowing a greater proportion of the fissionable material (i.e. lithium isotopes, plutonium and uranium) to be fissioned.

    However, this increase in efficiency is obviously limited for several reasons at very high yields. Suppose a 10 kt bomb can achieve an efficiency of say 50% of its fissionable nuclei fissioned, then the maximum increase in efficiency at higher yields is only a factor of 2.

    Once efficiency gets high, it can't be increased any more.

    Secondly, at high yields you may end up with more lithium splitting into tritium which upon fusion with deuterium gives a 14.8 MeV neutron. These high-energy neutrons are very liable to undergo a (n,2n) reaction with uranium-238, which reduces the efficiency of the fission of uranium-238. You end up with neutrons being absorbed without causing fission, so the yield to weight ratio can't rise any higher.

     
    At 7:23 pm, Blogger nige said...

    Yes, I have also got the facts on the exaggeration of chemical, biological and more importantly, conventional weapons effects. All of these are exaggerated in the sense that proper improvised countermeasures and realistic weather conditions with realistic population locations and dispersion, show the effects are trivial. This is why the Japanese cult used sarin on the underground, a confined space.

    The reason I'm concentrating this blog on nuclear weapons effects exaggerations is that there is less bias against the possibility of protecting people against the other threats. Nuclear weapons are a special case of exaggerations because they really CAN DO A LOT OF DAMAGE AND CAUSE A LOT OF CASUALTIES if people are unprepared.

    Chemical, biological and conventional protective emergency improvised actions are not very different to those against nuclear weapons effects. However, I'm detailing all of the efficiency factors for different protective actions in civil defence in the new free PDF book I'm preparing.

     
    At 8:51 pm, Anonymous Anonymous said...

    Thanks.............You are proved that I'm expected.

     
    At 7:45 am, Anonymous Anonymous said...

    Close, I'm believe that this device close resembles 1000-mt Alarm clock with same dimensions and using 100mt triger( weighning around 38kpa-in fact 40mt,60mt and100mt were prepared for Hardtrack,but were canceled by Rabi ).There are some evidence that large number of such TN systems have been studied in 1950-s,but unfortunately none of them ever materialized.
    Consider a new ones.Mk-6 RV was designed to deliver a 6400 p.warhead,35 mt warhead have been designed in 1962 in that in mind,i.e. its weight would be 6125pounds,this absurd if they construct 5250pond
    .For DS-1 -its unmanned,150,000 feet detonation,payload given as 7000 pound,so 40mt weighing 7000 pounds.20mt warhead was sucessor for W-38,26mt unknown ca.4000 pound 10mt warhead,35mt for mk-53,60mt for mk-41 and etc.More amazing that 20mt warhead would be warhead of Advanced Minuteman,probbly in MK-17 RV.But I'm not understand way to achieve such ratios-12.6kt/kg."The fact that tests were conducted of designs which could lead to an entirely new class of U.S. weapons which could have relatively low weights and extremely high yields, with the fission contributions decreased to only a few percent of the total yield. (63-1) (See also V.B.5.b.)

    9. The fact that the yield-to-weight ratios of the new class of weapons would be more than twice that which can now be achieved in the design of very high yield weapons using previously developed concepts".
    One guy said :"According to Lawrence Livermore National Labs, advances were made in very high yield devices (over 25 megatons) such that in 1962, they had the capability to build a 60 megaton device with a weight of around 9000 lbs, and the device would be 95%+ fusion; just as the Tsar Bomba was".
    I'm not understand this.Without u-238?

     
    At 2:06 pm, Anonymous Anonymous said...

    Also note that CIA estimates weight of Tsar Bomb as 17500 pounds,not 26.5 tons.They believed that it can be warhead for UR-500 missile.This is caused some confuse in open sources.In reality Soviets planned 30-megaton warhead for this missile,probably weighing 7500kg.

     
    At 4:51 am, Anonymous Anonymous said...

    MK-17 vehicle described as standard RV to deliver perhaps this 20mt warhead,on Improved Minuteman.

    But Advanced Minuteman RV (As well Advanced Titan 2 RV) described as Marv,maybe this data declassified today and shelved somewhere .
    A.Titan 2 vehicle for class B warhead,this would mean ca.60mt weapon.


    More interesting project was sea-based Advanced Polaris A-4.
    Loadings roughly same as small land -based Pluto.So why 42 5kt warheads on single vehicle they considered ?To take troop formations?
    As for large Pluto .Some says that contamination from jet would be great(600MW reactor),as well sonic boom from 28m long vehicle,flying at 150m at 3.5 M.
    What you would say about Pluto?At the end of mission (with multiple warheads) Pluto would crushed to surface and reactor would be overloaded and detonated.What you would say about it?As for detonation of single warhead ? Material of the reactor also would be fissioned ?

    For large Pluto warhead was 75 megatons.

     
    At 5:55 pm, Anonymous MABUS said...

    1,000-megaton was a Livermore design.

    From the Chuck Hansen's Swords

    "In terms of extremely-high yield warheads, DOD had at this
    time a standing requirement for a 100 MT weapon within
    prescribed volume and weight limits. Even larger yields were
    believed possible: a report prepared by UCRL discussed the
    feasibility of a 1,000 MT warhead.224 (This was reminiscent of
    Dr. Edward Teller's July 1954 proposal for a 10,000 MT
    weapon.)"

    What would be area contaminated to 1000R 96-hour dose outdoors from 1000-megaton surface burst.

     
    At 6:39 pm, Blogger nige said...

    "What would be area contaminated to 1000R 96-hour dose outdoors from 1000-megaton surface burst."

    In Glasstone and Dolan, the outside 1000 R 96-hour dose contour for Castle-Bravo (15 megatons total yield, about 10 megatons of which was fission) is 160 miles long and up to 32 miles wide, covering an area of roughly (Pi/4)*160*32 = 4,000 square miles.

    However, this area for 1000 R does not scale up directly with bomb power, because it takes more and more time for fallout to arrive over the bigger downwind areas from higher yields, so more decay occurs during this extra arrival time.

    The downwind distances and widths of imaginary "1 hour reference dose rates" (which never occur for downwind locations with fallout arrival times longer than 1 hour) scale roughly as {yield}^0.5 (so that areas for imaginary 1 hour reference dose rates scale directly with yield).

    So, if the effective (median) fallout arrival time at a location is directly proportional to the downwind distance, the arrival time will also scale as {yield}^0.5.

    The 96 hour dose is D = 5{R_1}(t^{-0.2} - 96^{-0.2}), and the infinite time dose is D = 5{R_1}t^{-0.2}, where R_1 is the imaginary 1-hour reference dose rate and t is the arrival time.

    Hence, the average infinite time dose (about 60% of which is received in 96 hours for 1 hour arrival time) covering an area that is directly with yield will only increase as {yield}^(-0.5*0.2) or as {yield}^-0.1.

    So if 1000 R outdoors over 4,000 square miles for 10 mt fission is scaled to 1000 mt, you get a dose of 630 R outdoors over 400,000 square miles. However, it's easy to get a protection factor of at least 10 inside a modern building.

     
    At 3:44 pm, Anonymous Anonymous said...

    35 -megaton warhead for Titan II apparently described in the document :MEMO FOR MEMBERS, MLC, WARHEAD FOR THE TITAN II .

    Author(s): BAKER, E.E. (* AEC AND DEPARTMENT OF DEFENSE) ; LUEDECKE, A.R. (AEC-ATOMIC ENERGY COMMISSION, THE U.S.)

    Addressee: UNK; BROWN H.

    Publication Date: 1962 Sep 18 .

    OpenNet Entry Date: 1994 Aug 26 .

    I'm have plans to find its copy in closest future.

     
    At 2:15 pm, Anonymous Anonymous said...

    Only very first details about these warheads declassified.

    The main SAC requirement after Soviet 50Mt test was a 150-megaton
    warhead (25,000 pounds) i.e. Class A weapon,it cannot be delivered by bombers,so it was a military version of Titan III(1962).

    But with gelled propellant and with a solid booster named Titan-2A,that itself was a ICBM.

    I'm not find numbers for this baby that Lemay and Tommy Power wanted yet,but Tommy wanted 10 000 Minuteman ICBM.....

    It also must be pointed out,that however , traitors -JFK and Mcnamara canceled the Atmospheric development tests for devices (up to 1000MT-yes, this was a Teller,LLNL and USAF scientists's initiative) during Dominic,it was possible to test these warheads (20-150MT)
    undeground at very reduced yields ,around 1 megaton.

     
    At 12:44 am, Anonymous Anonymous said...

    Regardless of what people think of nuclear weapon capabilities, a 10 megaton thermonuclear bomb (which is several times more powerful than Fat Man and Little Boy) always vaporize everything in the ground zero leaving no remains.

     
    At 2:54 pm, Blogger nige said...

    Not if it is air burst to maximise thermal radiation effects and blast damage to wooden houses! You cannot fit a 10 megaton warhead into a MIRVed missile or any SLBM warhead anyhow. You need a missile the size of a space rocket, like the old Titan II, to deliver that size warhead. Even if you have a ground burst, only about 1% of the crater is even melted as proved by Miller's USNRDL-466 report data on fallout specific activity, and far less than that is vaporized. This is why the concrete shelters at the crater edge remained, unvaporized. The vaporization propaganda myth started with the airbrushing out of the surviving concrete buildings near ground zero, where only 0.1 mm thickness of roof tiles was ablated!

     
    At 2:11 pm, Blogger masterco93 said...

    You mentioned before that in both Koa and Seminole nuclear tests, the device was detonated in water tank to incease the cratering. I understand that the more massive the nuclear device, the more energy you get in form of kinetic energy instead of heat which equals more cratering. But why exactly water ?
    In other words, what does water do better than the few cubic meters of soil/rock in the very close proximity to the device given that both water and rock are good absorbers of X-rays ?

     
    At 11:42 am, Blogger nige said...

    Water tanks were used because water has a standard density of 1 metric ton per cubic metre, to test the theory that putting more mass around the bomb puts more energy into cratering phenomena. You can read about it in the declassified cratering and general effects reports for Operations Redwing (1956) and Hardtack (1958).

    If they had merely bulldozed coral sand around the bombs, there would have been the issue of the exact bulk density (air spaces inside the soil reduce the density, so the effective density depends on how compacted the soil is, introducing more complexity).

     
    At 1:00 am, Blogger masterco93 said...

    But regardless of the complexity of finding out the effective density, adding mass of a material with good absorption of X-rays around the bomb mean more cratering. Is that correct ?

     
    At 12:01 pm, Blogger nige said...

    Exactly: a really thick mass around the bomb can convert most of the X-ray energy into hydrodynamic energy, thus increasing the crater, throwout, and ground shock effects.

     

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