First OSI activity at the former Nevada Test Site
The U.S. contributions to the OSI effort have been substantial, not only by recently hosting us in Nevada, but throughout the history of our organization. U.S. experience with nuclear explosive testing allows U.S. experts to pass along their knowledge to the inspectors who will be ready to find evidence of a nuclear explosion once the Treaty enters into force. We need to make sure these international experts are as well qualified and trained as possible, and coming to Nevada to see the effects from real nuclear explosions in a variety of geologies has been a tremendous experience for our surrogate inspectors. We thank the United States for its many contributions to advance the readiness of the OSI system.
Participants test personal dosimeters during the health and safety briefing before departing for NNSS.

Visit to the Pahute Mesa area at the former Nevada Test Site where nuclear explosive tests were conducted in welded tuff. Here participants observe how geology can affect what features are present at a given site.
The Nevada Familiarization Activity was an unprecedented opportunity for OSI surrogate inspectors to learn from, examine and analyse the remnants of legacy nuclear explosive testing first hand. This experience can be considered as one of the most significant in the history of OSI surrogate inspector activities as there is no substitute for the education the surrogate inspectors received at the Nevada National Security Site from a team of dedicated U.S. national experts.
Participating in the Nevada Familiarization Activity has opened my eyes to the size and scale of experiments and nuclear explosive tests at the NNSS. This important knowledge will help me to have a deeper insight when planning geophysical surveys during OSI training activities and exercises as well as during future potential inspections after entry into force of the Treaty. Understanding the geological conditions of the site was an important aspect of understanding UNE signatures as the surrounding geology can greatly control or influence the manifestation of observables after a test. This is an experience that every surrogate inspector and trainee should have.
United States and the CTBT
The United States was the very first country to sign the CTBT on 24 September 1996, the day it opened for signature. It is one of eight countries that still must ratify the Treaty so that it can enter into force.
The United States hosts 37 International Monitoring System facilities (map), more than any other country. In addition to being the largest single regular contributor to the CTBTO’s budget, the United States also makes significant voluntary contributions to the organization’s work. See country profile for more information.
For NNSA, hosting the Familiarization Activity gave us the opportunity to explore how working on a former test site can enhance the training and capabilities of future CTBTO inspectors. The visit took surrogate inspectors out of the classroom and into an environment where they were experiencing the full range of challenges that they might experience in a real OSI. We were also able to demonstrate how we have transformed the Nevada National Security Site from a test site to a test bed for a broad range of activities supporting out nonproliferation and arms control missions.
23 May 2016