Of course, everyone knows about this type of test as an underground nuclear explosion, but I did not quite understand the specifics of this option. How? What for? Why is this test option more profitable and better? For what purpose?
In 1947, the Council of Ministers of the USSR approved a resolution on the beginning of the construction of a test site for testing the first Soviet atomic bomb. Construction was completed on July 26, 1949. Polygon area of 18,540 sq. km was located 170 km from Semipalatinsk. Subsequently, it turned out that the choice of the site for the test site was made successfully: the terrain made it possible to conduct underground nuclear tests in adits and wells.
In total, 122 atmospheric and 456 underground nuclear tests were carried out at the Semipalatinsk test site in the period from 1949 to 1989.
This is the technology for conducting an underground nuclear explosion …
First - USA
The first ever underground nuclear explosion was carried out by the United States, codenamed "Uncle", at the Nevada Test Site on November 19, 1951. An explosion on the release of soil with a capacity of 1.2 kilotons was carried out at a shallow depth (5.5 m), exclusively in the interests of the Ministry of Defense to check the damaging factors. The first "full" underground nuclear test "Rainier" took place at the Nevada test site, Rainier Mesa, on September 19, 1957.
Promotional video:
Rainier Nuclear Test Scheme.
A 1.7 kiloton nuclear device was detonated in a mountain tunnel at a depth of 275 m.
It was conducted to perfect the methodology for testing nuclear charges in underground conditions, as well as to test methods and means of early detection of underground explosions. This test laid the foundations for the technology for conducting underground nuclear tests, which became especially relevant after the signing of the 1963 Moscow Treaty banning nuclear tests in the atmosphere, outer space and under water.
Dust clouds raised by the shockwave of the Rainier explosion.
In total, before the first Soviet underground explosion, the US government conducted 21 underground nuclear tests during operations.
Test preparation
The adit for the first Soviet underground nuclear explosion 380 m long was dug inside the rock mass of the landfill at a depth of 125 m. After the adit was converted into an explosion chamber, a container with a nuclear charge of 1 kt in TNT equivalent was fed on rails on a special trolley.
During an explosion inside the chamber, the pressure could reach several million atmospheres, so the adit was equipped with three driving sections. This was done to prevent the ingress of radioactive explosion products outside.
The first driving section, 40 m long, had a reinforced concrete wall and consisted of gravel backfill. A pipe passed through the blockage to output the neutron and gamma radiation flux to the sensors of the devices, which recorded the development of a chain reaction. The second section, which consisted of reinforced concrete wedges, had a length of 30 m. The third driving section, 10 meters long, was constructed at a distance of 200 m from the blast chamber. There were three instrument boxes with measuring equipment. Other measuring devices were also placed throughout the adit.
The epicenter was marked by a red flag, located on the surface of the mountain, directly above the explosion chamber. The detonation of the charge was carried out automatically from the control panel, located at a distance of 5 km from the adit mouth. It also housed seismic equipment and equipment for recording electromagnetic radiation from the explosion.
Test
On the appointed day, a radio signal was sent from the control panel, which included hundreds of devices of various types, and also ensured the detonation of the nuclear charge itself.
As a result, a dust cloud was formed at the site of the explosion, caused by rockfall, and the surface of the mountain above the epicenter rose by 4 m.
No release of radioactive products to the outside was observed. After the explosion, the dosimetrists and workers who entered the adit found that the section of the adit from the mouth to the third blockage and instrument boxes were not destroyed. No radioactive contamination was also recorded.
On November 6, 1971, on the uninhabited island of Amchitka (Aleutian Islands, Alaska), a 5-megaton Cannikin thermonuclear charge was detonated - the most powerful in the history of underground explosions. The test was conducted by the United States to study seismic effects.
The explosion resulted in an earthquake of 6.8 on the Richter scale, which caused the soil to rise to a height of about 5 meters, large collapses on the coastline and shifts in earth layers throughout the island with an area of 308.6 km.
Peaceful explosions
From 1965 to 1988, the USSR had a program of peaceful nuclear explosions. Within the framework of the secret "Program No. 7" 124 "peaceful" nuclear explosions were carried out, 117 of them were carried out outside the boundaries of atomic test sites, and with the help of detonating nuclear charges, scientists solved only national economic problems. Thus, the closest nuclear explosion to Moscow was carried out in the Ivanovo region.
Here we discussed in more detail peaceful nuclear explosions.
It was assumed that with the help of underground peaceful nuclear explosions it would be possible to intensify oil and gas production, create harbors, canals and reservoirs, as well as develop minerals in poor fields.