Once the Comprehensive Nuclear-Test-Ban Treaty (CTBT) enters into force, state parties can request an On-Site Inspection (OSI) if there is suspicion that a hidden nuclear test has been conducted. Until then, the Comprehensive Nuclear-Test-Ban Organization (CTBTO) are building inspection capacity to be fully ready for when the Treaty enters into force. OSIs are one of the three components in the CTBT’s verification regime, designed to monitor compliance with the nuclear test ban.

Morten Sickel is a senior engineer at NORSAR, and in the CTBTO he is an OSI inspector specialized in radionuclide analysis and also part of a team responsible for operating the IT systems. He started his OSI training in the autumn of 2016.

A large and time constrained operation

During an OSI, the team of inspectors travel to the site where a nuclear test is suspected to have been conducted to look for physical evidence. Most of the inspectors are professionals within one of the inspection techniques, which are seismology, geophysics, radionuclide analysis or visual observations.

We inspectors can be viewed as specialized forensic technicians – we are sent to look for evidence to determine what has happened.

International inspector cooperation
Norwegian, Spanish, Thai, and Australian inspectors collaborating on conducting field measurements as part of an exercise earlier this year. Photo: CTBTO

If a vote decides that an OSI is to be performed, rules within the CTBT guides the execution. With a limited number of inspectors and a designated time frame, it is crucial to have the logistics in order.

We are 40 inspectors at the most, and normally have 60 days at our disposal – the time limit can be extended to 130, but only with good reason. Therefore, the team has to work efficient. Because an inspection in theory can be conducted anywhere, we have to be highly self-sufficient, and have equipment to build ourselves a tent base to work from.

The inspected state is only obligated to supply the inspectors with water, fuel, and vehicles, so the CTBTO are prepared to transport all other necessary equipment. This can constitute over 100 tons of cargo: from advanced equipment to conduct field work through servers, clients for data analysis and reporting, and generators and cables to tents, tables, chairs, and folding cots.

Inspectors packing up a car
Necessary equipment must be packed and transported. Here from an exercise in september 2023. Photo: CTBTO

Worst case scenario, we’re looking at 130 days sleeping in tents and eating dry food. We do, however, hope that it will be possible to set up an arrangement providing accommodation and catering for the duration of the inspection.

Training is essential

CTBTO’s team of inspectors is composed of professionals from all over the world. They regularly meet for training, as role awareness and clear division of tasks is crucial to ensure smooth executions of inspections.

checking for radioactive substances
Upon returning to base after field work, the inspectors must be checked for radioactive substances. Photo: CTBTO

In the initial phase of an inspection I, together with the other inspectors, will work on setting up our base. I must also be ready to assists others if the need for base maintenance or other logistic tasks arise. We are also ready to help each other whenever possible: if a geophysicist needs a helping hand in field work I’ll step up, and if I am ever in need of assistance when acquiring samples or performing measurements, I can for instance ask one of the seismologists to come with.

The inspectors are currently in the middle of an intense training program to prepare for an integrated field exercise that is being held in Sri Lanka in 2025. Ahead of the field exercise there will  be a three week build up exercise in Hungary starting today, Monday June 17th.

inspectors gathered
Inspectors from all over the world regularly gather for trainings and exercises. Photo: CTBTO

See Morten expand on his work as an OSI inspector: