Neutron Source: Iran’s Uranium Deuteride Neutron Initiator

May 13, 2019

Weapon Program: 

  • Nuclear


Institute for Science and International Security

The Iranian Nuclear Archive shows that Iran planned on using a relatively sophisticated neutron source, or initiator, to trigger a chain reaction in the weapon-grade uranium core of its nuclear weapons. This source was made by combining natural uranium and deuterium into uranium deuteride (UD3). In essence, the natural uranium serves as the carrying material for the deuterium. UD3 sources have a long life, meaning they do not need to be replenished due to radioactive decay, like other common types of neutron initiators used in nuclear weapons. Figure 1 shows the placement of a neutron source in a schematic of a nuclear weapon design from Iran’s Nuclear Archive, a significant portion of which was seized by Israel in January 2018. According to documents in the Nuclear Archive, the neutron source design, development, testing, and production was under the Operating System Project of Project 110 of the Amad Plan. A Gantt diagram from the archive, detailing the major tasks of the Operating System Project, states that Iran’s neutron source project started in the spring of 2000 and was expected to finish by early November 2003. Overall, Project 110 expected to have built five nuclear weapons by March 2004.

Under international pressure, starting in the fall of 2003, Iran downsized the entire Amad program and reoriented it into better camouflaged, overt and covert parts.2 The work on the neutron initiator does not appear to have been completed on schedule, but continued in the reoriented nuclear weapons program that may continue into the present.

The Nuclear Archive documents Iran’s development, testing, and production of a neutron initiator that is intrinsic to an effort to produce nuclear weapons. This project was inconsistent with, if not a violation of, Article II of the Nuclear Non-Proliferation Treaty (NPT).


Read the full report at the Institute for Science and International Security.