Blog Post - Iran Matters

How to Make Sure Iran's One Year Nuclear Breakout Time Does not Shrink

| June 20, 2015

Olli Heinonen, Senior Fellow at the Belfer Center for Science and International Affairs, and Simon Henderson, Baker Fellow at the Washington Institute for Middle East Policy, write for the Washington Institute for Near East Policy that the final agreement with Iran over its nuclear program needs to take into account the efficiency of Iranian centrifuges when calculating breakout time, and not just the number of centrifuges allowed to enrich. They note that the exact efficiency in Separative Work Units (SWUs) of the Iranian IR-1 centrifuge is not exactly known, and therefore it is very possible that American estimates of Iran's enrichment capacity dangerously underestimates how much Iran is able to enrich, meaning that estimates putting its breakout time at one year are are inaccurate. They argue that it is necessary to understand exactly how efficient the Iranian centrifuges are in order to understand how many Iran needs to maintain a breakout time of about one year, and that this figure cannot only be calculated from the number of centrifuges Iran possess.

For more information on this publication: Belfer Communications Office
For Academic Citation: Heinonen, Olli and Simon Henderson.How to Make Sure Iran's One Year Nuclear Breakout Time Does not Shrink.” Iran Matters, June 20, 2015,

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