WASHINGTON (Realist English). On 30 September, the US National Nuclear Security Administration announced the successful conduct of an “underground non-nuclear chemical explosive experiment” in Tunnel P of Area 12 at the Nevada National Security Site.
The experiment used chemical explosives and radioactive tracers to enhance the US ability to detect low-yield nuclear explosions.
NNSA Administrator Brandon Williams stated: “Detecting nuclear activity requires nuclear expertise, and such experiments ensure that the US maintains an unparalleled position in this field. The Trump administration has made it clear that the US will lead from a position of strength. American innovation cannot be circumvented. With this experiment, we are sending a clear signal: under the current administration, the US will never be surpassed.”
Focus on “Decoupled Explosions”: Technology for Reducing Seismic Signals
The key goal of the experiment is to enhance the US ability to detect “decoupled explosions.” In conventional underground nuclear tests, the device is placed deep underground in close contact with rock, and most of the shock wave is transmitted to sensors.
In a decoupled explosion, the device detonates in an underground cavity, and the seismic signal is significantly weakened, making a powerful explosion appear as a low-yield event in monitoring systems.
The US previously accused China of conducting such decoupled tests in June 2020 at the Lop Nur nuclear test site to reduce the effectiveness of seismic monitoring.
Earlier this year, Washington renewed this accusation and called for a broader new arms control treaty. China responded at the time that the US accusations were “completely baseless” and constituted a “fabricated pretext for resuming American nuclear testing.”
Multisensor Integration: From Seismic Waves to Radioactive Tracers
During the experiment, researchers used various advanced sensors, including accelerometers, seismometers, infrasound sensors, electromagnetic sensors, samplers for chemical and radioactive tracers, as well as meteorological sensors. These data will help scientists better understand the characteristic signals of underground explosions and strengthen the US ability to detect and characterize nuclear explosion-related events.
The Nevada National Security Site was the location of hundreds of nuclear tests during the Cold War. The current experiment became the site’s latest activity in the field of nuclear non-proliferation.
Key Parameters
| Parameter | Content |
| Experiment date | 30 September 2026 |
| Location | Nevada National Security Site, Area 12, Tunnel P |
| Experiment type | Underground non-nuclear chemical explosion |
| Main materials | Chemical explosives, radioactive tracers |
| Key goal | Detection of “decoupled explosions” — low-yield nuclear tests |
| Sensor types | Accelerometers, seismometers, infrasound, electromagnetic, chemical samplers, meteorological |
| Data use | Validation of scientific models, optimization of detection algorithms |
