This is analysis of past underground nuclear tests which did contain all of the radiation for the initial tests. There is a question about how well the radiation has been contained in the decades since, but the leakage is to the Ocean and is not increasing the health risk to people. The largest underground nuclear tests were 4-10 Megatons in size and were performed as late as 1973. (H/T to Joseph Friedlander for research and joint brainstorming and Dr Bolonkin for his large dome and other work)
10 Megatons of TNT, equal to 4.185×10^16 Joules (1 ton of TNT = 4.185×10^9 Joules, One Joule is one kilogram/M^2/S^2 )The average power produced during the entire fission-fusion process, lasting around 39 nanoseconds, was about 1.1×10^24 watts or 1.1 yottawatts. Configuring a nuclear device the way project Orion had planned would direct 85% if the energy at the pusher plate.
so 3.5*10^16 Joules towards kinetic energy.
Kinetic Energy =1/2*Mass*Velocity^2
Escape velocity=11186 M/S
EV ^ 2 = 125 million (m^2/s^2)
2.8*10^8 kg or 280,000 tons. Say 140,000 tons to double escape velocity if we wanted to be pretty sure that the projectile cargo could go the moon if we aimed it right.
Currently the worlds cheapest rocket is the Russian Dnepr which costs about $2500/kg to low earth orbit (2006 prices) and $6000-9000/kg to Geosynchronous orbit. Chemical rocket cargo delivered to the moon is about ten times more expensive ($50,000/kg).
So 100,000 tons of cargo delivered to the moon would be worth $5 trillion at the best prices today. 200,000 tons delivered to orbit would be worth $1 trillion @$5000/kg. If this could be done at one tenth the cost it is still worth $100 billion to orbit and $500 billion to the moon. Getting to one tenth of current costs is an optimistic ten years away and billions in development. The cost is to find a location like another remote island to sacrifice the underground area for nuclear launch similar to the areas sacrificed for underground nuclear testing. However, with proper preparation and a dome with a door and charges to speed the collapse of the shaft, there would be no radiation into the atmosphere. Other industries like oil, gas and coal regularly contaminate salt domes and underground and above ground locations. This would be safer and cleaner than those continuing operations. We would use nuclear bombs that are costing money to be maintained in storage and have a risk non-peaceful use. There is no risk of damaging EMP because damaging EMP occurs when a nuclear device is exploded at high altitude.
* So no fallout into the atmosphere
* No EMP
* Use existing nuclear device or dismantle several devices and reconfigure for optimum directing of energy
* Use an underground area – how much is the value of a few cubic miles of salt ?
* Almost no one includes the cost of the salt dome for strategic petroleum storage
* Make a large metal shell projectile and place ablative oil on the bottom
* Create the appropriate shaft to the launch chamber.
* The only applicable treaty that has currently been ratified by the USA is the Threshold Test treaty which limits underground nuclear tests to 150 kilotons or less. The comprehensive test ban treaty has not been ratified.
There was also tests where an underground nuclear test launched a multi-ton object. This was not an intentional launch.
The Pascal A nuclear test “launched” a blast door at six times earth escape velocity.
The asteroid and meteor FAQ explains how atmospheric resistance is a problem for small objects. If an object (round object like a meteor) is less than 8 tons then it loses all of its momentum and gets mostly destroyed trying to pass through the atmosphere at high speed. On the very large end of the scale, a meteoroid of 1000 tons (9 x 10^5 kg) would retain about 70% of its cosmic velocity. A 100,000 ton object passes through the atmosphere like it is not there.
Objects can only be propelled to very high velocities by a nuclear explosion if they are located close to the burst point. Once a nuclear fireball has grown to a radius that is similar in size to the radius of a quantity of high explosive of similar yield, its energy density is about the same and very high velocities would not be produced. This radius for a 300 ton explosion is 3.5 meters.
The steel plate at the top of the shaft was over 150 m from the nuclear device, much too far for it to be propelled to extreme velocity directly by the explosion. The feature of Pascal-B that made this possible was the placement of the collimator close to the device. The mass of the collimator cylinder was at least 2 tonnes (if solid) and would have been vaporized by the explosion, turning it into a mass of superheated gas that expanded and accelerated up the shaft, turning it into a giant gun. It was the hypersonic expanding column of vaporized concrete striking the cover plate that propelled it off the shaft at high velocity.
So we should try to size at that range for a nuclear launched projectile. Shaping the projectile like a bullet or rocket would also help.
90pct containment was proved by Pascal A dome, which did not get direct blast exposure but instead needs a rapid closing mechanism after projectile exit.
10pct blown into air should be 99pct contained within dome which sees NO direct heat radiation. There would be considerable secondary from the muzzle blast. So 99.9+ percent containment. 10 megaton blast say 15 kilograms tritium output all but 15 grams contained, if 5 kt fission (design a device with less fission and more fusion) then all but 5 tons of fission products contained! (fraction of 1 gram by weight)
There could be conventional explosives in the shaft to collapse the shaft after the launch projectile has passed.
Underground Nuclear Testing
The effects of an underground nuclear test may vary according to factors including the depth and yield of the explosion, as well as the nature of the surrounding rock. If the test is conducted at sufficient depth, the test is said to be contained, with no venting of gases or other contaminants to the environment. In contrast, if the device is buried at insufficient depth (“underburied”), then rock may be expelled by the explosion, forming a crater surrounded by ejecta, and releasing high-pressure gases to the atmosphere (the resulting crater is usually conical in profile, circular, and may range between tens to hundreds of metres in diameter and depth). One figure used in determining how deeply the device should be buried is the scaled depth of burial, or -burst. This figure is calculated as the burial depth in metres divided by the cube root of the yield in kilotons.
Although there were early concerns about earthquakes arising as a result of underground tests, there is no evidence that this has occurred. However, fault movements and ground fractures have been reported, and explosions often precede a series of aftershocks, thought to be a result of cavity collapse and chimney formation. In a few cases, seismic energy released by fault movements has exceeded that of the explosion itself.
Large Earthquakes and volcanoes can reach multi-gigatons of energy release.
4-10 Megaton Underground Nuclear Tests Performed
Note: The ocean has Uranium and thorium and other naturally occuring radioactive material in it. A few parts per million which total to 4 billion tons of Uranium.
The W71 was the high-yield warhead developed for the Spartan ABM. The W71’s yield was too large for underground testing at the Nevada Test Site, so Amchitka Island in the Alaskan Aleutians was selected as a site. To evaluate concerns over this site, a test of 1.2 megatons was conducted at Amchitka on 2 October 1969 (Milrow). Political opposition to the W-71 test (and the Safeguard ABM system in general) included an appeal to the U.S. Supreme Court attempting to block the test on the scheduled day; the Court rejected the appeal 4-3, allowing the test to procede. On 6 November 1971 the Spartan’s warhead, the W71, was tested at full yield in shot Cannikin of Operation Grommet. At the bottom of a 1.76 km-deep shaft, the warhead’s yield was reported as “approximately” 5 mt or “less than 5 megatons”, estimated here as about 4.8 megatons.
Two high yield Soviet tests were conducted underground at the southern island of Novaya Zemlya in 1973. At least one probably exceeded 4 mt in yield. The yield of these and other Soviet underground tests were the subject of debate in the West for years, with some sources suggesting that published yield estimates were too high. Based on recent information from Russian sources, it appears if anything that the Western estimates had been too low. MINATOM has reported a total yield of 7.8 mt for the two 1973 tests at Novaya Zemlya. The first test, on 12 September, involved a salvo detonation of one device reported as 1.5 to 10 mt in yield plus two with yields between 0.15 and 1.5 mt. The total yield for this test was about 4 mt. The test on 27 October is reported by MINATOM as between 1.5 and 10 mt in yield. Western estimates have ranged from 2.8 to 4.9 mt; recent reports place the yield at 3.5 mt. If this is correct, the 12 September test yield was about 4.2 mt, of which about 3-3.5 mt was the larger device. Both tests were probably reduced yield versions of warheads for ICBMs nearing deployment.
*This is a modification of the old underground nuclear tests. Repeating the old 5-10 megaton tests. But reconfigure to optimize conversion to kinetic energy. Radiation containment for underground tests is a known problem and has proven tests.
* The Project Orion configuration and directed nuclear blasts had the Orion work and the Casaba-Howitzer work. So 85% conversion of nuclear explosion to directed propulsion is known.
* Sacrifice one salt dome or an area under an island. Using natural geological feature mostly reduces cost of containment.
* Actual out of pocket cost less than one billion. Can be done within 2 years.
* Can do some supercomputer modeling and tweaking and optimization to be sure.
* Very limited technical risk for the launch. Nuclear bombs work.
* Leverages the trillions spent on the arms race for good. (sunk costs)
* Negotiate for the exception to the test Threshold test ban and only ratify the Comprehensive test ban with an exception for space launches. Maybe allow Russia, China, UK and France and other to share the payload that is delivered or for each to be allowed to launch one.
This proposal is simpler, cheaper and safer than Project Orion. The proposal is not to build a manned space vehicle but an unmanned projectile that contains cargo. There are not two hundred atmospheric explosions but one underground explosion. the pusher plate does not need to withstand multiple explosions but survive one while not losing the cargo. The cargo is selected and designed to survive the forces that it will encounter.
There are petaflop class supercomputers now that were built for the sole purpose of modeling nuclear explosions in a precise way as an alternative to live tests. There are powerful lasers and other high energy machines created to validate the precision of the computer models.
Most of what is being proposed is the simplest conversion of heat and explosive energy into kinetic energy. This is guns and metallergy and decades of nuclear weapons research and age old newtonian mechanics.
An interesting question is what happens when you set off another nuclear bomb in fractured and crushed rock a year or so later? The ground has settled and has contamination but most of the most radioactive fallout is no longer dangerous. So long as the new charge is placed low enough so that the fallout does not escape the fractured rock then you could just keep re-contaminate the same contaminated site.
The 5 megaton underground nuclear test video. Notice things are shaking as this is like a magnitude 7 earthquake but there was no radiation venting. 85% of the energy for the nuclear cannon would go at the projectile.
Dr. Volz hand catches Eider Ducks on Amchitka Island, Aleutians, for Radionuclide Internal Dose Assessment
1989 congressional analysis of underground test safety.
A person’s total exposure would be equivalent to 32 extra minutes of normal background exposure (or the equivalent of 1/1000 of a single chest x-ray).
A worst-case scenario for a catastrophic accident at the test site would be the prompt, massive venting of a 150-kiloton test (the largest allowed under the 1974 Threshold Test Ban Treaty). The release would be in the range of 1 to 10 percent of the total radiation generated by the explosion (compared to 6 percent released
by the Baneberry test or an estimated 10 percent that would be released by a test conducted in a hole open to the surface). Such an accident would be comparable to a 15-kiloton above ground test, and would release approximately 150,000,000 Ci. Although such an accident would be considered a major catastrophe today, during the early years at the Nevada Test Site 25 above ground tests had individual yields equal to or greater than 15 kilotons.