Shock Wave Generator for Iran’s Nuclear Weapons Program: More than a Feasibility Study

Summary

Based on findings from the seized Iranian Nuclear Archive, this report analyzes Iran’s development and manufacturing of a multi-point initiation (MPI) shock wave generator under the ‘Amad Plan’ nuclear weapons program in the early 2000s. It details the role of key facilities such as Sanjarian, high-explosive components like PETN and Octol, and diagnostic explosive testing. The authors conclude that Iran had advanced beyond theoretical feasibility studies toward weaponization production and urge comprehensive IAEA inspections.

Executive Summary and Key Findings

A copublication of Institute for Science and International Security and Foundation for Defense of Democracies (FDD)

Shock Wave Generator for Iran’s Nuclear Weapons Program: More than a Feasibility Study By David Albright and Olli Heinonen May 7, 2019

• The Iranian Nuclear Archive reveals that under its early 2000s nuclear weapons program known as the “Amad Plan,” Iran was developing and manufacturing a key nuclear weapon subcomponent called a “shock wave generator.” The shock wave generator is a multi-point initiation (MPI) system, which has the purpose of uniformly initiating a spherical shell of high explosives, or the “main charge,” which in turn compresses the nuclear core made from weapon-grade uranium to achieve a supercritical mass for a nuclear explosion. Iran’s Nuclear Archive, a significant portion of which Israel seized in January 2018, is a curated set of highly sensitive nuclear weapons information detailing the Amad program’s effort to develop and manufacture five nuclear weapons and prepare an underground nuclear test site for possible use. • The development of the shock wave generator, also known as distributor, contributed importantly to Iran’s miniaturization of a nuclear weapons design. • A key associated Amad Plan facility was near the village of Sanjarian, called the “Sanjarian facility.” It made high explosive parts for the shock wave generator and conducted a range of tests for its development. In addition, under the Amad Plan, it was a center for the testing of exploding bridgewires (EBWs), which were necessary for the shock wave generator. Its nuclear weapon-related activities after the Amad Plan remain to be determined. • The Sanjarian building held two blast chambers, called Upper and Lower Nour-Abad, which were used in the Amad Plan, and perhaps afterwards, to test EBWs, the shock wave generator, and other subcomponents. One chamber was outfitted with a high speed camera. A full-scale, hemispherical test of the shock wave generator, using sophisticated diagnostic equipment, was conducted at the Marivan site, according to the archive information. • The archive contains considerably more information about the shock wave generator and Iran’s nuclear weapons development and testing than can be presented in this report. That information – due to proliferation reasons – cannot be made public. • The archive indicates that Iran had completed almost two thirds of the tasks associated with the “Shock Generator Project” by around 2002. With an expected completion date of July 2003, Iran may have completed the additional, approximately third of the tasks just before the Amad Plan was downsized and reoriented in the fall of 2003. The exact status of this project at that time and its evolution after the fall of 2003 remains to be determined. • Foreign assistance from at least one former member of the Soviet nuclear weapons program was key to Iran’s development of this MPI technology. • Preserving these complex nuclear weapons capabilities was a priority for Iran in the post-Amad reorientation plan. After 2003, the Shock Generator Project activities and Sanjarian facility were provided with a cover purpose of performing non-nuclear military and non-military explosive tests, and some activities were shifted to universities, such as Malek Ashtar University of Technology, and research institutes. Iran prioritized maintaining the project’s workforce. The status of these activities is unknown today, but the archive information indicates that they may continue. The Organization of Defensive Innovation and Research (SPND) is the latest known incarnation of the reoriented Amad Plan that appears to have inherited the personnel and capabilities of the Shock Generator Project. • The archive information on the shock wave generator confirms and adds considerably to previous information on this MPI system assembled over a decade ago by the International Atomic Energy Agency (IAEA). • The IAEA needs to inspect the Sanjarian site and related facilities, examine relevant equipment and materials, and interview the personnel mentioned in the archive and from the IAEA’s previous, extensive work to understand the shock wave generator project. The IAEA needs to characterize the status of the program today, its work and associated equipment, and interview any related personnel. • Iran should be urged to cooperate fully in these investigations. In particular, no information or equipment should be destroyed, and no locations altered before the IAEA has completed its investigations. Those investigations should include weapons experts with proper clearances. At the end of the inspection process, proliferation-sensitive information and equipment, where on-going possession is not in line with Iran’s undertakings under Article II of the Nuclear Non-Proliferation Treaty (NPT), should be destroyed irretrievably or removed from Iran in a verifiable manner.

Shock Wave Generator

Iran was developing and building a nuclear weapons production complex in the early 2000s under the “Amad Plan,” with the goal of manufacturing five nuclear weapons by 2004. This program had moved beyond performing feasibility and scientific studies. Iran had a nuclear weapons design small enough to fit on the Shahab-3 ballistic missile and was creating the wherewithal to develop and make the subcomponents of that design. Some of the components were innovative and complex. The primary subject of this report is one of those subcomponents, the “shock wave generator.” This component, which is represented as the green layer under the outer casing in the nuclear explosive schematic (Figure 1), contributed importantly to the miniaturization of Iran’s nuclear weapon design. Its purpose is to uniformly initiate the high explosives, or “main charge,” which in turn compress the nuclear core made from weapon-grade uranium to achieve a supercritical mass and a nuclear explosion. This component falls under the general category of a multi-point initiation (MPI) system.

Figure 1 shows a schematic of a levitated nuclear weapon design, e.g. one with an air gap and flyer plate to increase compression of the core, based on the use of weapon-grade uranium, from the Nuclear Archive and presented by Prime Minister Benjamin Netanyahu on April 30, 2018. From the bottom, and proceeding counterclockwise, the Farsi terms are: • Neutron source • Uranium 235 core • Air gap • Flyer plate • Main charge • “Detonation distributor” or shock wave generator, and • Outer casing

The Nuclear Archive contains important information about the shock wave generator which confirms and adds to previously available information, in particular, information assembled by the IAEA about a decade ago. This report also takes into consideration detailed, public reporting on the Iranian shock wave generator from the period of about 2008 to 2011.

A key development and manufacturing facility associated with the shock wave generator was located near the village of Sanjarian, also known as Sanjarion or Sanjarioun, located about 20 kilometers east of Tehran and about 15 kilometers north-northeast of the high explosive test chamber complex at the Parchin site.

Shock Wave Generator’s Place in Overall Amad Plan Organization

The development and manufacture of the shock wave generator took place under the Amad Plan, Iran’s military nuclear program in the early 2000s composed of many projects needed to make, at least initially, five nuclear weapons and prepare a nuclear test site. In particular, in the archive documents, what is called the “Shock Generator Project” was under the nuclear weaponization portion of a project codenamed Project 110, which was composed of four main technical subprojects: • Operating System Project • Midan Project • Simulation Project • Warhead Project

As can be seen in the chart (Figure 2), the Shock Generator Project is listed under the Operating System Project, which was charged with the task of creating a complex to develop and build nuclear weapons. The Midan Project was responsible for creating a nuclear test site for a 10 kiloton detonation and methods to estimate the yield of a nuclear detonation. The Simulation Project was involved in theoretical and software aspects of developing and manufacturing nuclear weapons, and the Warhead Project was charged with fitting the nuclear warhead into the re-entry vehicle of a Shahab-3 ballistic missile, including fusing, arming, and firing mechanisms.

Based on an Amad Plan table prepared in about 2002, the start date of Project 110 was March 20, 2000, and the expected completion date was given as four years later, on March 17, 2004. This table lists the start date for the Shock Generator Project as May 15, 2000, with a completion date of July 20, 2003, making it a three-year project. As of the date of the 2002 table, the Shock Generator Project had completed 58 percent of its tasks, versus 64 percent expected to be completed by this time.

Functions of Shock Generator Project

The major task of the Shock Generator Project was the development and manufacture of shock wave generators for use in nuclear weapons. However, the project appears to have also had some responsibility for the development and use of detonators (e.g. Exploding Bridgewires (EBWs)) and the main high explosive charge used in Iran’s planned nuclear weapon.

A stacked set of four PowerPoint slides titled “Report of the Shock Generator Project,” dated November 14, 2002, shows discussions on:

• Domestic production and testing of Octol, a high explosive composed of HMX and TNT used as the main charge in nuclear weapons.
• Signing a contract for domestic Octol production and evaluating foreign produced Octol for gradation (particle size analysis), detonation velocity, and detonation pressure.
• “Main Charge” slides showing hemispherical objects and an unidentified cylindrical object.

Figure 3 from the archive shows a high explosive hemispherical casting mold. After casting, a CNC machine tool was used to shape it into its final form (a hemispherical shell).

Background on the Shock Wave Generator

The shock wave generator in Project 110 is a spherical multipoint initiation system that was designed to fit inside a nuclear warhead carried in the payload chamber of the Shahab-3 missile nose cone. The basic design is a distributed, explosive-filled channel system for initiating hemispherical high explosive charges. A detonation front initiated at one point via an exploding bridgewire or spark gap is made to arrive simultaneously at a multitude of points on a surface.

The assembled system consists of two hemispherical shells and requires only two detonation points, in contrast to the 32 initiation points on early U.S. nuclear weapons. It eliminates the need for high explosive lenses and reduces the warhead size.

Foreign assistance from Russian expert Vycheslav V. Danilenko aided Iran’s development of MPI technology and diagnostic configurations. U.S. patent 3,430,563 (Richard Stresau, 1969) and Russian patents (VNIIEF) outline similar distributed-channel principles.

In IAEA reporting, the Iranian shock wave generator was referred to as the R265 generator (inner diameter of 265 mm, outer diameter of 550 mm). The shell was made of aluminum, approximately 1 cm thick, with 1x1 mm channels cut into the surface filled with PETN and plasticizer (PIB). Each channel terminated in a 5 mm hole drilled through the shell containing an explosive pellet.

Large-Scale Testing at Marivan

In 2003, Iran conducted a large-scale hemispherical MPI experiment at Marivan. In this experimental setup, 50 kilograms of Composition B explosives in the form of a shell were placed inside a hemispherical shock generator system. The detonation front arrival time was monitored using hundreds of fiber optic cables drilled into a thin inner holder shell and transmitted to a high-speed framing/streak camera at a safe distance of 40 meters, using explosive argon flash lighting (raster method).

The Sanjarian Facility and Nour-Abad Blast Chambers

The Sanjarian facility (coordinates: 35.691 N, 51.7000 E, also known as METFAZ / Nour-Abad) manufactured high-explosive components and conducted explosive testing. The facility housed a manufacturing line for plasticized PETN sheets (including recrystallization reactors, mixers, extruders, and hydraulic rollers) and two blast chambers (Upper and Lower Nour-Abad).

Archive records document extensive tests in Aban and Azar 1381 (October–December 2002):

• Multiple photodiode tests
• Synchronized tests of EBW detonators (firing 7 to 8 detonators simultaneously)
• Detonator cable length testing (220-meter cable)
• Synchronized tests of R80 and flat φ80 distributors with and without primary charges
• Framing camera and argon flash photometric testing
• 1 Mbar gun tests

Post-Amad Reorientation Activities

Following the fall 2003 decision to reorient the Amad Plan, Iranian leadership prioritized preserving the personnel, capabilities, and equipment of the Sanjarian site. The activities were transitioned under cover of civilian/non-nuclear military applications, described as the ‘Center for research and modeling of military and non-military explosives (such as cladding)’ at Malek-Ashtar University of Technology (MUT) and the Explosion Center.

Later successor organizations within the Organization of Defensive Innovation and Research (SPND), such as the Shahid Karimi Group (headed by Mohammad Reza Mehdipur and previously Akbar Motallebizadeh), retained key personnel and responsibilities related to explosion, shock, and detonator research.

Findings and Recommendations

1. Iran’s Shock Wave Generator project advanced well beyond scientific feasibility into production and full-scale testing before the downsizing of the Amad Plan.
2. The IAEA’s 2015 assessment that Iran had not moved beyond feasibility studies is contradicted by Nuclear Archive documentation.
3. The IAEA must inspect the Sanjarian site and related successor facilities under SPND, examine equipment, and interview key personnel.
4. Proliferation-sensitive equipment, materials, and documentation must be verifiably and irretrievably destroyed or removed under Article II of the NPT.