* One example from a large collection of analyses formerly on this website:
An underground nuclear test at the Nevada National Security Site can happen any day now - by accident. An anonymous letter sent allegedly by a group of DOE and EPA scientists to the State of Nevada Agency for Nuclear Projects in 1998 implied that one of the radiological 'situations' at the Nevada Test Site (NTS) that a DOE-gutted environmental program would largely fail to 'mitigate' included nuclear "devices [that] have failed to detonate partially or completely." To date, the only NTS nuclear devices disclosed by the DOE to the public that fully failed to detonate were affiliated with the 'Transom' (May 10, 1978) and 'Peninsula' (October 23, 1975) underground nuclear tests. While Transom's device never detonated, the Peninsula test wasn't even conducted. The device fell 40 feet during emplacement and was damaged. Eleven test site workers were injured during the accident.

On September 6, 1979, the DOE carried out shot 'Hearts,' a 140-kiloton underground nuclear blast intended to create a shock environment to 'destroy' those two unexploded devices, both located in nearby underground test shafts. 'Hearts' was not intended to explode the devices but rather somehow render them safe, or safer. Hearts was 'successful' at destroying 'Transom,' but it took another nuclear blast dubbed 'Azul' on December 14, 1979 to 'destroy' the Peninsula device. (Azul's yield was 'less than 20 kt'.)

It is very difficult to believe that the DOE has 'closed the case' on these two unexploded nuclear bomb devices, or even other partially unexploded nuclear bombs underneath the Nevada floor. After the Transom device failed to produce any nuclear yield, the DOE announced to the Associated Press in 1978 that there was 'no possibility of any additional explosion.' So, what was the reason for 'Hearts'? And how does the DOE definitively know that that the unexploded bombs were 'terminated'? Transom was estimated to produce a 20 to 150 kiloton yield and Peninsula would have produced a blast less than 20 kilotons.

Could these devices or other unexploded masses of atomic device material - sometimes called nuclear UXO, or unexploded ordnance - blow up beneath the Nevada desert? There is some debate regarding unexploded nuclear bombs - i.e., one off the coast of Georgia, another off the seabed near Thule, Greenland - over whether or not supercriticality, the condition that's ripe for a runaway, explosive chain reaction, could occur. Supercriticality is the mushroom-cloud, nuclear-explosive result of a runaway chain reaction of atomic disintegrations in a critical mass of fissionable material resulting from an extraordinarily rich environment of neutrons. Even if supercriticality isn't reached in a nuclear 'pile,' fission can occur at a slower rate (than a nuclear explosion) and produce quantities of radioactive products of basically the same concentrations. So, at least it is possible that unexploded critical masses of nuclear bomb material located below the Earth's surface can emit radioactive gasses that that could seep up to the ocean or ground surface and the resulting impacts on human health and our food chain from these gasses could be damaging.
- Excerpt from source: 'Nuclear Weapons Complex's Toxic Releases, Nevada National Security Site - the former Nevada Test Site,' by Andrew Kishner. Retrieved 2014, from http://www.nuclearcrimes.org/4-5.php. No longer available online.