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On-Site Inspection Workshop-25, Online or In-Person

Workshop-25 will consist of two interconnected segments, an on-line preparation session and an in-person session.

On-line Session:   Selected dates between 3-21 October
In-person Session:   7-11 November 2022, in Vienna.

The working language will be English


The First Comprehensive Draft List of Equipment for Use during OSIs (“the List”) contains proposed specifications relating to the core equipment for the inspection activities and techniques specified in the Protocol to the Comprehensive Nuclear-Test-Ban Treaty, Part II, paragraph 69, with the exception of drilling (para.69(h)). Following the proposal of the List by the PTS in February 2021, which was compiled in accordance with guidance contained in Task Leader Paper CTBT/WGB/TL-4/47 and as advised by States Signatories during the Fifty-Fourth Session of Working Group B, the objectives of the Workshop-25 are:

  • Conduct in-depth technical discussions on the basis of the List with a view to its review and further development;
  • Identify recommendations for the finalization of the List and its ultimate consideration by WGB.

The outcome of the Workshop will be included in the report of OSI Workshop-25 and is expected to comprise updated specifications of equipment, suggestions on common and specific software requirements, as well as recommendations for further development of the List and its review mechanism before EIF.

A detailed programme will be provided to confirmed participants in due course.


The Workshop will consist of plenary meetings and in-depth discussions in expert groups. The topics for the plenary session would include:

  • General observations on the List
  • Software issues
  • Review mechanism for the List
  • Recommendations for the finalization of the List (including drilling and auxiliary equipment)

To cover all the items on the List, the expert group discussions will be broken down into the following groups according to techniques. The tasks for each group would include revision of the listed specifications of the items and consideration of the general and specific software requirements.

  • Group A: Position finding, visual observation, video and still photography and multispectral imaging, including infrared measurements;
  • Group B: Radionuclide/noble gas techniques (including gamma radiation monitoring, energy resolution analysis, environmental sampling and analysis);
  • Group C: Geophysical techniques (including passive seismological monitoring, resonance seismometry, active seismic surveys, magnetic and gravitational field mapping, ground penetrating radar, electrical conductivity measurements);
  • Group D: Data and information management.

Technique-specific aspects of overflights will be considered by the respective groups, but cross-cutting issues relating to overflights will be addressed by relevant experts from Groups A, B and C in an additional combined session.

At the discretion of group leaders, a group may be divided into subgroups as required to facilitate discussion.

Participant Profile

Approximately 50 OSI experts external to the PTS are expected to participate.

The PTS wishes to note that it will only be able to provide financial assistance to a number of experts for the in-person session, based on the individuals’ experience and area of expertise, with due regard to geographical representation, diversity and gender, and subject to availability of funding.

Application Procedure

States Signatories are invited to nominate experts who wish to contribute to the discussions of the Workshop through their respective Permanent Mission. Nominations are to be submitted officially to the OSI Division (see Points of Contact) as soon as possible but no later than 30 June 2022.

Nominations should include names of experts, their current position, postal and e-mail address, area of expertise and the possible topic of presentation. The Provisional Technical Secretariat (PTS) may also identify and invite OSI experts from States Signatories and the PTS to the event.

Once confirmed, participants will be given access through email to the relevant PTS platforms, where registration information, the programme and supporting documents will be uploaded.

Further administrative information will be forwarded to confirmed participants in due course.

Magnetometers are used to identify anomalies in the underground geological structures.

Point of Contact

Ms. Rui Zuo
Chief, Documentation Section, OSI Division
Provisional Technical Secretariat
CTBTO Preparatory Commission
Tel.: +43 1 26030 6172
Fax: +43 1 26030 5926
Email: [email protected]

Mr. James Cooke
Documentation Officer, Documentation Section, OSI Division
Provisional Technical Secretariat
CTBTO Preparatory Commission
Tel.: +43 1 26030 6186
Fax: +43 1 26030 5926
Email: [email protected]