This is a translation of the introductory material, and Documents 12 and 13, contained in the article On the Origins of the Soviet Atomic Project: Role of the Intelligence Service 1941 - 1946 edited by V. P. Visgin, published in the Russian-language journal Voprosy Istorii Estestvoznaniia i Tekhniki (Problems in the History of Science and Technology, commonly abbreviated VIET), Issue No.3, 1992, pgs. 97-134.
I am grateful to the translator who wishes to remain anonymous.
Last changed 15 April 1998
From the editorial staff:
At the invitation of Editor-in-Chief V.I. Kozlov, A.A. Yatskov, veteran of the intelligence service, KGB of the USSR, and who as assistant to the resident Soviet spy in the USA took part in providing a channel of communication between Los Alamos, where the American atomic bomb was developed, and the Kurchatov Laboratory No. 2, where the Soviet atomic project was started in early 1943, visited the editorial office of the journal at the beginning of 1992. Anatolii Antonovich brought his article on the role of the Soviet intelligence service in the solution of the 'uranium problem' in the USSR and copies of unique documents attesting to the importance of this role.
Just at this time a programme for the study of the history of the Soviet atomic project was set up at the Institute of the History of Science and Technology in the Russian Academy of Sciences. A group of workers at this Institute and at the Russian Science Centre 'Kurchatov Institute' (formerly the Institute of Atomic Energy) formed the core of the research staff, which sat before it the task of studying the history of the atomic project in the USSR. Below we publish a preliminary version of the research programme, 'Atomic Project in the USSR' with the aim of drawing the attention of all interested persons and organizations to it.
At one of the meetings of this group in 1992, A.A. Yatskov gave a report on the contribution of the intelligence service to the creation of the Soviet nuclear weapon and acquainted the audience with the above-mentioned documents, which remained sealed just yesterday. The lecture and these unique documents aroused lively interest among all those present at the meeting.
It should be noted that sketches (mainly in the style of science journalism) on similar themes and even publications of fragments of selected documents including from those which A.A. Yatskov showed us have now appeared. But there is not yet a sufficiently complete publication of documents confirming the effectiveness and scientific value of the information on the 'uranium problem' from the Soviet intelligence service.
With the present publication we want to rectify this omission to some extent. we preface the set of documents with a brief description, which does not pretend to be a detailed historico-scientific analysis. Both the description and the very terse commentary facilitate understanding these archival materials. A.A. Yatskov's article 'The Atom and the Intelligence Services' also serves this purpose. We would like to draw the reader's attention to the following distinctive features of this article. First, as already noted, the author was a participant in the described events, and in the article some are superficial and inadequate but still are vivid testimony to this. Secondly, a majority of the published documents are mentioned in it and thereby the article seems to supplement our commentary. Thirdly, although the author is a veteran of the intelligence service and his article and documents enable one to value highly the contribution of the intelligence service to the solution of the 'uranium problem,' one is not inclined to belittle the achievements of the scientists and engineers who developed the nuclear shield of the country. The editorial staff of the journal express profound gratitude to A.A. Yatskov for graciously giving us these valuable materials from the archives of the Russian Foreign Intelligence Service.
The archival materials concerning the initial stage of the thermonuclear project will be published in one of the following issues of the journal.
The principal aim is the collection of archival, memoir-type and other materials on the atomic project in the USSR and its realization, and on this basis the recovery of the history of the development of the nuclear potential of the country: namely the nuclear weapon, nuclear reactors, the first nuclear power-plants.
The timeliness of the programme, its cultural and practical value
Nuclear weapons and energetics radically changed the whole world. At the end of the 1940s and the beginning of the 1950s, almost simultaneously with the USA, the USSR solved the most complex scientific and technical problems and became a nuclear power. Today the Chernobyl disaster, the problems of ecology, nuclear disarmament, and control over the potential of the Commonwealth of Independent States, questions of converting the military-industrial complex make the task of producing a documented and analytic history of the atomic project in the USSR very timely.
(Pages 98-125 of the article have been omitted)
The conducting of the first explosion of the atomic bomb is expected in July of this year.
Construction of the bomb. The element 94 without any uranium-235 is the active material of this bomb.The so-called initiator, namely a beryllium-polonium source of alpha particles, is inserted into the centre of a ball of plutonium. (The plutonium is surrounded by 50 pounds of tube-alloy,* which is the 'tamper.') All this is placed in an aluminum shell of thickness 11 cm. This aluminum shell in turn is surrounded by a layer of the explosive 'pentalit' or Composition C (Composition B according to other information) with wall thickness 46 cm. The casing of the bomb into which this explosive is inserted has an inner diameter of 140 cm. The total weight of the bomb including the pentalit, the casing, etc. is about 3 tonnes. It is anticipated that the force of the bomb explosion will be equal to the explosive force of 5000 tonnes of TNT. (The efficiency is 5-6%.) The fission count equals 75 x 10exp24.
Stocks of active material
a) Uranium-235. In April of this year it was 25 kilograms of uranium-235. Its output at present is 7.5 kg per month.
Plutonium (element 94). There are 6.5 kg of plutonium in Camp-2. Its preparation is well organized, production plan is over-fulfilled.
* Tube-alloy is the code name for uranium (commercial radium tube-alloy) [added by hand below the world 'uranium' -- ed. note]. It is not known of which type: natural 235 or enriched in a diffusion plant.
The explosion is tentatively expected on 10 July of this year
[Written by hand] Note: Information was put together for oral briefing of Academician Kurchatov.
Herewith I send a report on the construction of the atomic bomb, designed on the basis of secret-service materials received from the National KGB of the USSR.
Enclosure in 7 pages
Make 4 copies (V.N. Merkulov)
1. Comrade Beria
2. National KGB of the USSR
3-4...
In outer appearance the atomic bomb is a pear-shaped missile with maximum diameter of 127 cm and length of 325 cm including the stabilizer (fins). Total weight is 4500 kg. The bomb consists of the following component parts:
All the above-specified parts of the bomb with the exception of the stabilizer, the detonating device and the outer steel shell are spherical shells inserted one into the other. Thus, for instance, the active material is prepared in the shape of a spherical shell into whose center the initiator is inserted. The ball of active material itself is inserted into the interior of the tamper (moderator), which is itself a spherical shell. The tamper ball is inserted into the interior of another spherical shell made of aluminum, which is surrounded with a spherical layer of explosive.
After the layer of explosive, into which the lenses are inserted, there is a duralumin shell to which the detonating device is attached and on top of which is the bomb's outer casing made from armor steel.
1. Initiator
An initiator of the 'Urchin' type is used in the bomb. It consists of a hollow beryllium sperule on whose inner surface are wedge-shaped grooves. The planes of all the grooves are parallel to one another. The surface of the grooves is covered with a layer of gold of thickness 0.1 mm and a layer of polonium. Inside this spherule is inserted a solid beryllium spherule whose surface is also covered with a layer of gold and polonium.
| Dimensions of the 'Urchin' | |
|---|---|
| Outer radius of the hollow beryllium spherule | 1.0 cm |
| Radius of base of wedge-shaped groove | 0.40 cm |
| Radius of apex of wedge-shaped groove | 0.609 cm |
| Radius of the solid beryllium spherule | 0.40 cm |
| Number of wedge-shaped grooves | 15 |
| Amount of polonium on the surface of all grooves | 30 curies |
| Amount of polonium on solid spherule | 20 curies |
The hollow spherule is made of two halves, which are made in a nickel-carbonyl atmosphere, as a result of which a nickel coating is formed on the surface of hte spherule. This coating prevents or at least inhibits the spontaneous decay of polonium.
The initiator works as follows. The shock, directed towards the center, from the explosion of the outer layer of explosive is transmitted through the aluminum layer and tamper, throgugh the layer of active material onto the surface of the hollow beryllium spherule of the initiator. The resulting stresses fracture this spherule along the planes passing through the apex of the wedge-shaped grooves, thus exposing the beryllium of the hollow spherule to the action of the alpha-particles emerging from the polonium coating on the central spherule of the initiator. This produces a neutron flux. The adjacent surfaces of the grooves collide, as a result of which the 'Munroe jet' is generated, which penetrates through the thin layer of polonium and gold into the central spherule, thus putting in contact the polonium on the inner surface of the hollow beryllium spherule with the beryllium of the solid one. This also produces a neutron flux.
The neutron flux produced in the initiator attacks the active material.
2. Active Material
The element plutonium of delta-phase with specific gravity 15.8 is the active material of the atomic bomb. It is made in the shape of a spherical shell consisting of two halves, which just like the outer spherule of the initiator, are compressed in a nickel-carbonyl atmosphere. The outer diameter of the ball is 80-90 mm. The weight of the active material including the initiator is 7.3 - 10.0 kg. Between the hemispheres is a gasket of corrugated gold of thickness 0.1 mm, which protects against penetration of the initiator by high-speed jets moving along the junction plane of the hemispheres of active material. These jets can prematurely activate the initiator.
In one of the hemispheres, there is an opening of diameter 25 mm, which is used to insert the initiator into the centre of the active material, where it is mounted on a special bracket. After inserting the initiator, the opening is closed with a plug, made also of plutonium.
3. Tamper (Moderator)
The tamper is a spherical shell with outer diameter 230 mm, made from uranium metal. There is an opening in the ball for inserting the active material into the interior. The opening is closed with a plug, also made of uranium metal.
The purpose of the tamper (moderator) is that it reduces the amount of active material necessary for making the atomic bomb.
The outer surface of the tamper is covered with a layer of boron, which moderates the thermal neutrons emanating from the radioactive materials of the system and are capable of causing premature detonation.
4. Layer of Aluminum
The aluminum layer surrounding the outer surface of the tamper forms a spherical shell with outer diameter 460 mm, made of two halves with grooves and ridges provided for joining. There is an opening in one of the hemispheres for inserting the active material into the interior of the bomb. The opening is closed with a plug made of aluminum.
The purpose of the aluminum layer is the uniform transfer, directed to the centre, of the shock produced by detonating the outer layer of explosive.
5. Layer of Explosives and Lenses
Around the aluminum layer is placed a layer of explosive, which is formed from 32 specially shaped blocks. The inner centre-facing surface of the blocks is spherical with diameter equal to the outer diameter of the aluminum layer. On the outer surface of the blocks of explosive are special grooves whose shape provides for the insertion into them of 20 hexagon-shaped lenses and 12 pentagon-shaped lenses. A 1/16 inch thick felt pad is placed between the surfaces of the explosive and the lenses perpendicular to the axis of the sphere, and the empty spaces between the radial contact surfaces are filled with blotting paper. The air gaps between the layer of explosive and the lenses should not exceed 1/32 inch, since bigger air gaps can contribute to either the slowing-down or the speeding-up of the detonation depending on the direction of these gaps. The lenses are cast in special molds made from cellulose acetate. Each lens consists of two types of explosive, one fast-detonating and the other slow-detonating. When the lenses are installed in place, the fast-detonating part of each lens touches the layer of explosive.
Each lens is provided with one detonator, which for greater guarantee of simultaneous explosion has two electric primers. There are 64 electric wires in all, partitioned into 4 quadrants with 16 wires in each. A lens is connected to two electric wires but from different quadrants.
6. Duralumin Shell
The layer of explosive and lenses is covered with a duralumin shell, to which a blasting device weighing 180 kg is attached. The inner diameter of the shell is roughly 1400 mm; the weight including the blasting device is about 700 kg.
7. Outer Casing of Armour Steel
8. Stabilizer (fins)
Assembly of Bomb
The ball of uranium is inserted into the interior of the aluminum sphere in such a way that the opening on it fits opposite the opening in the aluminum. The blocks with the lenses are stacked on the outer surface of the aluminum except for one block which is placed over the opening in the aluminum. The lenses are mounted on the duralumin shell, to which the blasting device is also fastened. In that form the bomb is ready for transportation to the place of use. Further assembly is carried out as follows. The initiator is inserted into the interior of the tamper. The plugs are put into place, after which the last block of explosive is superimposed and the openings on the duralumin and steel shells are closed.
Becasue the plutonium and the radioactive materials of the initiator are spontaneously heated to a temperature exceeding that of the surrounding region by 90 degrees Celsius, the bombs are transported to the place of final assembly in special containers equipped with a cooling system.
" " October 1945
Faithfully: Colonel (VASILEVSKII)