One post presents the basic idea of the one pulse cannon and
works out more details of the underground launch and the configuration and how it relates to historical nuclear test.
Briefly Reviewing the One Underground Pulse Nuclear Launch Cannon
I have an analysis of using a one pulse Orion like configuration to launch 100,000 to 200,000 tons of cargo to Orbit or the moon using one 10 megaton explosion. 150 kilotons which is allowed under the Threshold test ban could probably launch 500-1000 tons. Chemical rockets would take $1-5 trillion to launch that much cargo into space. Even assuming super-high volume chemical rocket costs could be reduce by ten times, this would still be a $100 billion to 500 billion value. (fuel, water, metals and
any other gravity hardened material.)
It is a modification of the old underground nuclear tests. Repeating the old 5-10 megaton tests, but reconfigure to optimize conversion to kinetic energy as per the
Project Orion, Pascal-A/B, Thunderwell and Casaba-Howitzer work. Radiation containment for underground tests is a known problem and demonstrated by actual US and Russian tests.
This chart of space velocities corrects some previous information that I had for the nuclear cannon
Sacrifice one salt dome or an area under an island. Salt dome is easier to make a large diameter shaft for the projectile. Using natural geological feature mostly reduces cost of containment and has been demonstrated historically.
Actual out of pocket cost could be less than one billion dollars. Can be done within 2 years. Supercomputer modeling would be needed to get everything to work properly.
Very limited technical risk for the launch. Nuclear bombs work. Leverages the trillions spent on the arms race for good. (sunk costs)
Need to get some support from notable people who already support Project Orion.
Can we get George Dyson, Freeman Dyson or other old-timers to look at this idea and
see if they like it ? How much support if there is no airbursts, no dangerous EMP, and no atmospheric radiation but just vastly superior unmanned space launch capability. Negotiate for the exception to the comprehensive test ban. 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.
Underground Nuclear Explosions
Underground nuclear explosions can have all radiation contained. The underground explosion for a nuclear launch would need to have different containment for a larger initially open shaft. The shaft is open to allow the projectile to launch. Shaft sections can be collapsed as soon as the projectile is passing (so long as the collapse does not interfere with the launch. There can be initially fully contained underground tests. A 1 kiloton or 10 kiloton sideways launching into the ground to confirm the nuclear to kinetic energy conversion. A 100 kiloton launching could be performed before scaling to 1 megaton or 10 megatons. Before any live tests the supercomputer modelling and other tests could be performed.
At the top there can either be some kind of dome structure with a massive door or mechanical closure as shown in one of the pictures below or there could be a dam holding back piled earth. The dam would be blown up as the projectile is launched to release the more material to block the shaft.
Underground tests after 1971 had no radiation leakage or very little. The previously described 5 megaton Amchitka Island test had no leakage.
There is an 85 page pdf on Underground Nuclear Tests.