IR-40

In the mid-1980s, Iran's leadership decided to construct a natural uranium (i.e. not requiring enrichment to produce fuel) nuclear power plant, using heavy water as moderator and coolant. The reactor design was 90% complete in 2002. By then the existing Tehran Research Reactor, after 35 years operation, was reaching its design safety limits, and had been enveloped by the suburbs of Tehran.{{cite book|last1=Great Britain Foreign and Commonwealth Office|author-link=Foreign and Commonwealth Office|title=Iran's Nuclear Programme: A Collection of Documents|date=2005|publisher=The Stationery Office|location=London|isbn=9780101644327|url=https://books.google.com/books?id=5QzVKbA_Ma4C&pg=PA64|access-date=22 May 2018}}{{cite web|title=Research Reactor Details - TRR|url=http://www.iaea.org/cgi-bin/rrdb.page.pl/rrdeta.htm?country=IR&site=TRR&facno=214|date=1998-10-01|publisher=International Atomic Energy Agency|access-date=2009-08-19}}

The reactor was originally going to be constructed at a location in Esfahan. In 2002, it was decided to build at the current location near Arak.Alexander (146) Civil works for the construction began in October 2004.{{cite book|last1=Samore|first1=Gary|author-link=Gary Samore|title=Iran's Strategic Weapons Programmes: A Net Assessment|date=2005|publisher=Routledge|location=Abingdon, UK|isbn=9781136776731|url=https://books.google.com/books?id=Ea9FAAAAQBAJ&pg=PT60|access-date=22 May 2018}}

In August 2006, mixed reports came out about when the reactor would go into operation, one stating that the plant would start up in 2009, while another reported that operation would be postponed until 2011.Alexander (147) Reportedly, the Russian firm Nikiet assisted with portions of the design but stopped in the late 1990s following U.S. pressure.{{Cite web|url=http://www.isisnucleariran.org/sites/facilities/arak-ir-40/|title = Institute for Science and International Security}}

Press reports indicate that Iranian President Mahmoud Ahmadinejad visited the reactor in June 2013, on the occasion of the reactor vessel installation, which is the final precursor prior to commencement of operation.{{cite news|url=https://news.yahoo.com/ahmadinejad-visits-iran-heavy-water-reactor-101509632.html |title=Ahmadinejad visits Iran heavy water reactor site |publisher=Yahoo |date=June 9, 2013 |access-date=2013-06-09 |agency=Associated Press}}

In July 2015, under the Joint Comprehensive Plan of Action, Iran agreed to redesign the IR-40 reactor, with assistance from the P5+1, to minimize its plutonium production and avoid production of weapons-grade plutonium. Iran also agreed to remove the reactor core or calandria and fill it with concrete to render it unusable, and to export all spent fuel within one year of its removal from the reactor.[http://isis-online.org/uploads/isis-reports/documents/Plutonium_Pathway_Final.pdf The Plutonium Pathway: Arak Heavy Water Reactor and Reprocessing], Institute for Science and International Security, July 21, 2015.

In January 2016, Iran stated that the core of the reactor had been removed, and that it would be filled up with concrete.{{Cite news |date=2016-01-11 |title=Iran fills heavy water nuclear reactor core with cement: Fars |url=https://www.reuters.com/article/world/iran-fills-heavy-water-nuclear-reactor-core-with-cement-fars-idUSKCN0UP1Y1/ |access-date=2025-06-19 |work=Reuters |language=en-US}} In January 2019, in a Channel 4 TV (Iran) interview, Ali Akbar Salehi, the head of the Atomic Energy Organization of Iran, claimed that Iran had purchased spares to replace the core, and the pictures of the pouring of concrete into the reactor’s pit were photoshopped.{{Cite web |title=Iran's Nuclear Chief Salehi: We Had Secretly Purchased Replacements for Nuclear Equipment That the JCPOA Had Required Us to Destroy; Yellowcake Production Facilities are Operational; We Are Advancing in Nuclear Propulsion |url=https://www.memri.org/tv/iranian-atomic-energy-chief-ali-akbar-salehi-secret-purchase-nuclear-tubes-jcpoa-destroy-yellowcake-propulsion-arak-reactor |access-date=2025-06-19 |website=MEMRI |language=en}}

In 2017, the reactor was renamed as the 'Khondab Heavy Water Research Reactor'.{{Cite web |date=2017-06-12 |title=Iran's Arak heavy water reactor to undergo redesign |url=https://www.azernews.az/region/114613.html |access-date=2025-06-22 |website=Azernews.Az |language=en}}

In June 2025 the reactor containment building was damaged in a direct hit by Israel during the Iran-Israel war, as were distillation towers at the adjacent heavy water production plant.

{{cite web |last=Gritten |first=David |date=19 June 2025 |title=Israel strikes unfinished Arak heavy water reactor in Iran |url=https://www.bbc.com/news/articles/c8rpd6p7v0po |website=BBC |access-date=19 June 2025}}

Israel previously told residents of the surrounding areas to evacuate, specifically from Arak and Khonddab.{{Cite web |title=Israel Strikes Iran’s Heavy-Water Reactor in Arak |url=https://www.wsj.com/livecoverage/iran-israel-conflict-news/card/israel-strikes-iran-s-heavy-water-reactor-in-arak-tqjqjoWMTsGuw74VePuh |access-date=2025-06-19 |website=WSJ |language=en-US}}

{{main|Nuclear program of Iran}}

File:Arak Heavy Water5.JPG production plant near Arak]]

Iran states that the reactor will only be used for research and development, medical and industrial isotope production. On June 16, 2010 Iran announced plans to fabricate fuel for the Tehran Research Reactor by September 2011 and to build a new 20 MW reactor for radioisotope production within five years.http://www.ajc.com/news/nation-world/iran-plans-more-powerful-549480.html {{dead link|date=January 2020}}{{cite web |url=https://www.google.com/hostednews/afp/article/ALeqM5iQhYOH0V3xqCh-VJFxkigLrF-WgA |title=AFP: Iran to build 'powerful' new nuclear reactor |website=Google News |url-status=dead |archive-url=https://web.archive.org/web/20100619141635/http://www.google.com/hostednews/afp/article/ALeqM5iQhYOH0V3xqCh-VJFxkigLrF-WgA |archive-date=2010-06-19}}

Aspects of IR-40's design will also serve as a prototype and testbed for the larger 336 megawatt Darkhovin Nuclear Power Plant under construction near Ahvaz.{{citation needed|date=September 2011}}

There are some proliferation concerns about the reactor's ability to produce enough plutonium for several nuclear weapons each year. However the IAEA has reported that it found no indication of ongoing reprocessing activities, required to extract plutonium from the spent fuel.[http://www.iaea.org/Publications/Documents/Board/2008/gov2008-38.pdf GOV/2008/38], September 15, 2008, Implementation of the NPT Safeguards Agreement and relevant provisions of Security Council resolutions 1737 (2006), 1747 (2007) and 1803 (2008) in the Islamic Republic of Iran In full operation, it is expected that the reactor will produce from {{convert|10|kg|lb}} to {{convert|12|kg|lb}} of plutonium a year within its spent nuclear fuel.

Natural-uranium fueled heavy-water reactors were originally designed for producing weapons-grade plutonium usable for construction of nuclear weapons. Analysis suggests that Iran could extract 8–10 kilograms of high purity Pu-239Weapons-grade plutonium is at least 93% Pu-239. annually from fuel irradiated in IR-40. This, according to the IAEA, is sufficient weapons-grade material to produce 1 to 2 nuclear weapons annually.{{cite web|url=http://brage.bibsys.no/umb/bitstream/URN:NBN:no-bibsys_brage_29337/1/master.pdf|title=Feasibility and benefits of converting the Iranian heavy water reactor IR-40 to a more proliferation-resistant reactor|publisher=Norwegian University of Life Sciences (UMB)|work=masteroppgåva|date=14 December 2011|access-date=2013-06-09|author=Willig, Thomas Mo}} In August 2009, the IAEA was granted access to IR-40 and was able to carry out Design Information Verification, where the IAEA confirmed that the facility "at its current stage of construction conforms to the design information provided by Iran as of January 24, 2007."[http://www.nti.org/learn/facilities/177/ Implementation of the NPT Safeguards Agreement and the Relevant Security Council Resolutions 1737 (2006), 1747 (2007), 1803 (2008) and 1835 (2008) in the Islamic Republic of Iran], Nuclear Threat Initiative, 2009-08-28. Retrieved 2025-06-

As a result of concerns that this plutonium would support weapons development, former IAEA Deputy Director-General for Safeguards, Olli Heinonen, proposed a reactor redesign to a reactor using slightly enriched uranium fuel rather than natural uranium.{{cite web|url=https://foreignpolicy.com/articles/2011/01/27/can_the_nuclear_talks_with_iran_be_saved|title=Can the Nuclear Talks With Iran Be Saved?|publisher=Foreign Policy|date=24 June 2011|access-date=2013-06-09}} Use of enriched uranium fuel combined with extended operations would reduce the reactor's ability to produce weapons-grade plutonium.

Iran has indicated they do not intend to reprocess IR-40 spent fuel to recover weapons-grade plutonium, nor operate under a low burnup regime that could produce weapons-grade plutonium.{{cite news |url=https://www.google.com/hostednews/afp/article/ALeqM5jH0CCkmmqqb9Zhc5hYRNLMO8Z6cA?docId=bd818f75-3600-4a71-a71b-582794f47642 |archive-url=https://web.archive.org/web/20140305100019/http://www.google.com/hostednews/afp/article/ALeqM5jH0CCkmmqqb9Zhc5hYRNLMO8Z6cA?docId=bd818f75-3600-4a71-a71b-582794f47642 |url-status=dead |archive-date=March 5, 2014 |title=Arak reactor cannot make plutonium for bomb: Iran |publisher=AFP |date=27 December 2013 |access-date=27 December 2013}} Originally a hot cell facility at the Arak site was planned, described as capable of handling irradiated fuel and targets (such as targets for production of medical radioisotopes) from the IR-40. In 2004, plans for hot cells at Arak were removed.{{cite web |url=http://www.isisnucleariran.org/sites/detail/arak/ |title=Nuclear Sites - Arak Complex |publisher=ISIS |access-date=23 December 2013}} However some proliferation experts have expressed concern that once sufficient fuel has been irradiated Iran may modify this facility or build a separate reprocessing facility to recover weapons-grade plutonium.{{cite web|url=http://isis-online.org/uploads/isis-reports/documents/Arak_Update_25_August2009.pdf|title=Update on the Arak Reactor in Iran|publisher=Institute for Science and International Security|date=August 25, 2009|access-date=2013-06-09}}

• Bushehr Nuclear Power Plant
• Darkhovin Nuclear Power Plant
• Fordow Fuel Enrichment Plant
• Isfahan Nuclear Technology/Research Center
• List of power stations in Iran
• Natanz Nuclear Facility
• Nuclear program of Iran
• Supreme Nuclear Committee of Iran

{{Reflist|30em}}

• {{cite book|last=Alexander|first=Yonah|author2=Milton M Hoenig|title=The New Iranian Leadership Ahmadinejad, Terrorism, Nuclear Ambition, and the Middle East|publisher=Greenwood Publishing Group|year=2008|pages=344|url=https://books.google.com/books?id=_ac30INKAu4C|isbn=978-0-275-99640-6}}
• {{cite web|url=http://www.iranwatch.org/privateviews/First%20Watch/perspex-fwi-ir40reactor-1203.htm|title=Iran's IR-40 Reactor: A Preliminary Assessment|access-date=2008-12-30|last=Boureston|first=Jack |author2=Charles Mahaffey |author3=Yana Feldman |author4=Charles Ferguson|date=November 2003|format=Web page|publisher=Iran Watch|archive-url=https://web.archive.org/web/20081205121502/http://www.iranwatch.org/privateviews/First%20Watch/perspex-fwi-ir40reactor-1203.htm|url-status=dead|archive-date=2008-12-05}}
• {{cite web|url=http://www.iranwatch.org/privateviews/org/perspex-org-barnaby-nuclear-activities-0206.pdf|title=Iran's Nuclear Activities|access-date=2008-12-30|author=Barnaby, Frank|date=February 2006|publisher=Oxford Research Group|archive-url=https://web.archive.org/web/20080913103851/http://www.iranwatch.org/privateviews/org/perspex-org-barnaby-nuclear-activities-0206.pdf|url-status=dead|archive-date=2008-09-13}}
• {{cite web|url=http://www.isis-online.org/publications/iran/IAEAreport23May2007.pdf|title=Implementation of the NPT Safeguards Agreement and Relevant Provisions of Security Council Resolutions in the Islamic Republic of Iran|access-date=2008-12-30|date=2007-05-23|publisher=IAEA}}
• {{cite web|url=http://www.isisnucleariran.org/sites/facilities/arak-ir-40/|title=ISIS NuclearIran > Nuclear Sites > Facilities > Arak IR-40 Heavy Water Reactor|access-date=2008-12-30|publisher=ISIS NuclearIran|archive-url=https://web.archive.org/web/20090424124826/http://www.isisnucleariran.org/sites/facilities/arak-ir-40|url-status=dead|archive-date=2009-04-24}}
• {{cite web|url=http://www.nti.org/e_research/profiles/Iran/3119_3216.html|title=NTI: Country Overviews: Iran: Nuclear Facilities|access-date=2008-12-30|date=January 2006|publisher=NTI|archive-url=https://web.archive.org/web/20081011132318/http://www.nti.org/e_research/profiles/Iran/3119_3216.html|url-status=dead|archive-date=2008-10-11}}

{{commons category|Arak heavy water reactor}}

• [http://www.globalsecurity.org/wmd/library/news/iran/2006/iran-060826-irna07.htm President inaugurates Arak heavy water plant ]
• [http://www.globalsecurity.org/wmd/world/iran/arak-nrr.htm Iran Nuclear Research Reactor (IR-40)]

;Videos

• [https://www.youtube.com/watch?v=Ro0wHhtoFNs Arak Nuclear Complex] - Nuclear Threat Initiative (2014)

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Category:Nuclear program of Iran

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