Iran
Light Water Sub-Critical Reactor (ENTC-LWSCR)
About
The Light Water Sub-Critical Reactor (LWSCR) is a zero power reactor that runs on uranium metal fuel. 1 China supplied the reactor and the fuel to Iran in 1988, and it first became operational in 1992. 2 Iran uses the reactor for training purposes, and on average keeps it online for two hours per day. 3
In June 2025, the ENTC was attacked by Israeli airstrikes aimed at Iranian nuclear and missile infrastructure. While the ENTC was attacked, the LWSCR did not suffer any damages in this attack.4
Glossary
- Nuclear reactor
- Nuclear reactor: A vessel in which nuclear fission may be sustained and controlled in a chain nuclear reaction. The varieties are many, but all incorporate certain features, including: fissionable or fissile fuel; a moderating material (unless the reactor is operated on fast neutrons); a reflector to conserve escaping neutrons; provisions of removal of heat; measuring and controlling instruments; and protective devices.
- Uranium
- Uranium is a metal with the atomic number 92. See entries for enriched uranium, low enriched uranium, and highly enriched uranium.
Sources
- “Nuclear Research Reactors in the World, Research Reactor Details - ENTC LWSCR,” International Atomic Energy Agency, www.iaea.org; “Nuclear Sites, Esfahan Nuclear Technology Center/Research Reactors," Institute for Science and International Security, www.isisnucleariran.org.
- “Nuclear Research Reactors in the World, Research Reactor Details - ENTC LWSCR,” International Atomic Energy Agency, www.iaea.org.
- “Nuclear Research Reactors in the World, Research Reactor Details - ENTC LWSCR,” International Atomic Energy Agency, www.iaea.org.
- According to satellite analysis by Sam Lair at the James Martin Center for Nonproliferation Studies, June 2025.