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Projekt Wolke
The use of radioactive markers by the Stasi

Wolke (English: cloud) was the codename of a secret project, run from the late 1960s onwards, by Abteilung 32 (department 32) of the Ministerium für Staatssicherheit (MfS) — the repressive State Security Service of the former DDR (East Germany), also known as Stasi — to invisibly mark objects, documents and persons, with radioactive compounds so that they could be traced. The program was continued throughout the 1970s and 80s, and was only referred to by its codename Wolke and related project numbers of substances, equipment and instructions (e.g. 47100-670).

In the 1970s, at the hight of the project, the Stasi carried out some 100 Wolke-operations each year, whilst in the 1980s, this was reduced to about 30 to 50 operations per year [3]. At some point, probably in the early 1980s, the name 'Wolke' disappeared. It is possible that by that time, the project name had become known to too many people outside the Stasi, or that the Stasi was afraid that the name had come to the attention of Western intelligence services. From then on, the equipment was only referred to by project-numbers and the substances by key-numbers.

Confusingly, or perhaps deliberately, Stasi department HA III used the codename 'Wolke' again in 1983, when — together with Polish counterintelligence — they mounted an operation against the US Embassy in Warsaw to detect US SIGINT operations in Poland [4]. That is a different operation.

THIS PAGE IS A STUB — This page currently acts as a placeholder for background information about the secret Stasi project 'Wolke'. In due course, we hope to be able to give a more complete overview of the aspects of this project and the equipment that was involved. If you have information or equipment that might be related to this operation, and that can help us to expand this page, please contact us.
Related equipment on this website
Radiation detector

Although the use of radioactive markers is one of the most invasive and harmful methods of intelligence gathering, the Stasi appeared to be very imaginative when it came to finding ways in which the technology could be exploited. Below are a few examples of its modus operandi:

Tracking and tracing people
Special equipment was developed for tracing the whereabout of dissidents, journalist, politicians, suspected foreign agents, etc. Most of this equipment consisted of a Geiger-counter that had been expanded for automated use, enabling the Stasi to do active as well as passive detection:

  1. Active detection
    This application allows, for example, to invisibly count people walking throug a corridor. By placing a fixed radioactive source behind one wall of the corridor and aiming it as the Geiger detector which is located behind the opposite wall, anyone walking through the corridor will momentarily interrupt the 'beam' and cause the relay to generate a pulse.

  2. Passive detection
    In the same vain it was possible to detect people or objects that were marked with a radioactive substance. By placing the detector at a stategic place, the relay will generate a pulse as soon as the marked person or object passes its probe.

Methods were in place for placing the marker on a person. A special foil had been developed that could be attached invisibly to a person's cloating, and needles were developed — radiated at the Rossendorf nuclear plant — to enable an operative to place a marker on a passing person [1].

This was not without risk for the subject. For example, when using Scandium-46 — a popular Stasi marker — the subject could be exposed to as much as 150 mSv per case, which is as much as 3 × the maximum allowed dose for one year for a nuclear worker in the US [5]. It is also known that a dose of 100 mSv or more is clearly linked to an increased risk of cancer [5].

Discover who has been present at a meeting
The Stasi used radioactive markers to contaminate the floor of a room in which dissidents would meet, so that each individual visitor could be traced afterwards. The Stasi-operative who followed the nuclear trace, would keep sufficient distance to stay under the limit of 1 mSv per week [2]. This may not seem much, but 1 mSv is equivalent to staying in the Fukushima Exclusion Zone — immediately after the 2011 nuclear disaster — for two weeks [5].

Tracing of hand-written documents
The Stasi released ballpoints in which the ink was mixed with a radioactive isotope. The aim was to place these ballpoints in the hands of dissidents, who might then use it for writing (potentially compromising) documents. Once they were sent in the mail, or handed over to other dissidents or journalists, the Stasi was able to trace the documents and anyone who had handled them.

Radioactive markers
Below is a list of the radioactive compounds that are known to be used by Stasi as markers on people, floors, documents, money, vehicles and other objects, as part of Project Wolke. It is an abstract of the list compiled in 2002 by the authors of Projectbericht Strahlen [1 p.131-132].

Key # Wolke # Form Compound Isotope Half-life Delivered Used
47100-010 101 Foil MnCl2 54Mn 297 d 6,000 970
47100-020 102 Foil ScCl3 46Sc 4 84.1 d 20,000 515
47100-030 103 Foil CoCl2 58Co 71.4 d 25,000 11,000
47100-040 104 Foil BaCl2 140Ba 12.8 d 24,000 650
47100-310 105 Needle - 59Fc 44.5 d - 850
47100-320 106 Needle - 58Co 1.4 d - 1,000
47100-330 107 Needle - 110mAg 4 252 d - 420
47100-610 108 Spray ScCl3 46Sc 4 84.1 d 20,000 690
47100-620 109 Spray CoCl2 58Co 71.4 d 25,000 1,450
47100-630 110 Spray BaCl2 140Ba 12.8 d 24,000 850
47100-640 111 Spray NaBr 82Br 35.34 h 50,000 1,720
47100-650 2 Spray NaBr 82Br 35.34 h 48 mio <3,600
47100-660 2 Spray ? 137Cs 4 30 y ? ?
47100-670 2 Spray CoCl2 58Co 71.4 d 25,000 <3,200
47100-680 2 Spray CsNO3 137Cs 4 30 y 25,000 <2,500
47101-010 2 Bullet - 110mAg 252 d 500 500
47101-310 112 Paper MnCl2 54Mn 297 d 4,000 1,040
47101-320 113 Paper ScCl3 46Sc 4 84.1 d 15,000 520
47101-340 115 Paper NaJ 131J 8.07 d 15,000 1,067
47101-350 116 Paper NaBr 82Br 35.6 d 30,000 432
47101-360 117 Paper CH3COONa 24Na 15 h 20,000 507
47101-370 121 Paper CoCl2 58Co 71.4 d 30,000 ?
47101-380 121 Paper Thiourea 14C 3 5600 y ? 120 Bq
47101-390 2 Paper CsNO3 137Cs 4 30 y 20,000 <4,300
47101-400 2 Paper C10H14O5N2 H3 3 12.3 y ? ?
47101-610 2 Ballpoint Thiourea 35S 3 87 d 5,000 >0.397 nCi
47101-620 2 Ballpoint PO4 32P 3 14.3 d 121.6 >0.074 nCi
47101-630 2 Ballpoint PrCl3 143Pr 3 13.7 d 2,000 >0.397 nCi
47102-010 122 Vehicle ScCl3 46Sc 4 84.1 d 15,000 1,500
47102-020 123 Vehicle CoCl2 58Co 71.4 d 30,000 3,300
47102-030 124 Vehicle Oxalate 95Nb 35.2 d 5,300 -
47102-040 125 Vehicle BaCl2 140Ba 12.8 d 4,000 -
  1. Quantity Delivered and Used in µCi.
  2. 'Wolke' designator unknown (or non-existent).
  3. Produces Beta radiation (β).
  4. Produces Beta and Gamma radiation (β, γ).

  1. Gebrauchsanweisung zum Gerät 'Wolke 005'
    BStU, MfS, OTS, Nr. 2247, Bl. 1-39. 1
  1. Document obtainded from BStU [6] via Detlev Vreisleben [7].

  1. Eisenfeld, Auerbach, Weber und Pflugbeil, Projectbericht 'Strahlen'
    Einsatz von Röntgenstrahlen und radioaktiven Stoffen durch das MfS gegen Oppositionelle — Fiktion oder Realität? Hg. BStU, Berlin 2002.

  2. Iris Schaper, Stasi markierte Opfer mit radioaktiven Stoffen
    Website 8 January 2001.

  3. Stefan Berg, Die Spur der Strahlen
    Der Spiegel 12/2000. pp. 30-31.

  4. Benjamin B. Fisher, Intelligence in Recent Public Literature
    Central Intelligence Agency (CIA), Library. 1999 — 2007.

  5. Wikipedia, Randall Munroe — Radiation dose chart
    Retrieved June 2019.

  6. Bundesbeauftragte für die Stasi-Unterlagen (BStU) 1
    Federal Commissioner for the Stasi-Records.

  7. Detlev Vreisleben, Personal correspondence
    June 2019.
  1. Full name: Bundesbeauftragte für die Unterlagen des Staatssicherheitsdienstes der ehemaligen Deutschen Demokratischen Republik (DDR) — Federal Commissioner for the Records of the State Security Service of the former German Democratic Republic (GDR) — officially abbreviated to BStU.

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© Crypto Museum. Created: Thursday 06 June 2019. Last changed: Thursday, 07 March 2024 - 09:14 CET.
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