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Miniature Neutron Source Reactor (MNSR)

  • Location
    Isfahan Nuclear Technology Center
  • Type
    Nuclear-Research Reactors
  • Facility Status

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The 30KW Miniature Neutron Sources Reactor (MNSR) is a light water cooled and moderated research reactor that runs on 900 grams of 90% highly enriched uranium (HEU). 1 China supplied the reactor to Iran in 1991, and it first reached criticality in 1994. 2 The China National Nuclear Corporation supplied the reactor’s fuel. Iran uses the reactor for neutron activation analysis. 3


Research reactor
Research reactor: Small fission reactors designed to produce neutrons for a variety of purposes, including scientific research, training, and medical isotope production. Unlike commercial power reactors, they are not designed to generate power.
Highly enriched uranium (HEU)
Highly enriched uranium (HEU): Refers to uranium with a concentration of more than 20% of the isotope U-235. Achieved via the process of enrichment. See entry for enriched uranium.
Critical: A state where the number of neutrons in each period of time, or generation, remains constant. When a nuclear reactor is “steady-state,” or operating at normal power levels for extended periods of time, it is in this state.
Neutron: An uncharged particle with a mass slightly greater than that of the proton, and found in the nucleus of every atom heavier than hydrogen-1.


  1. “Iran: Map and Chart,” Carnegie Endowment for International Peace, www.carnegieendowment.org.
  2. “Iran: Nuclear Research Reactors of the World,” International Atomic Energy Agency, www.iaea.org.
  3. “Nuclear Research Reactors in the World, Research Reactor Details - ENTC MNSR,” International Atomic Energy Agency, www.iaea.org.


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