A Nuclear Physicist Explains the Science Behind the Iran Deal


(music) Ernie Moniz: Building a
nuclear weapon starts with uranium or plutonium – these
are different pathways. Uranium is found is
nature with about 99.3 % of uranium-238 and
0.7% of uranium-235. The uranium-235 is the key
ingredient for nuclear power plant fuel and for weapons. The raw uranium is
mined and enriched, bringing the uranium-235 to
between 4 and 5% to create fuel for a nuclear reactor
to produce electricity. About 1/5 of American
electricity comes from nuclear power plants
using fuel like this. In order to create a
uranium nuclear bomb, you can’t just use
that fuel as it is. Nuclear weapons use uranium
enriched up to about to 90% uranium-235. We are dramatically
restricting the amount of enriched uranium that
they can have on hand. Iran will reduce its stockpile
of enriched uranium by 98%; from 12,000 kilograms
to only 300 kilograms. Iran will reduce the
number of centrifuges; enriching uranium
to just over 5,000 for the next decade
from almost 20,000 today. And for the next ten
years, only the oldest and least capable model
of centrifuges will be allowed to operate. Right now Iran has enough
enriched uranium for about ten bombs, and if Iran wanted to
acquire a nuclear weapon, it would take only two
or three months for it to enrich enough
uranium to a high enough level to produce a bomb. If Iran did decide that it
wanted to race to a weapon, it would start with so few
machines and so little uranium that it would take them a year
to reach enough material for even a single first bomb. Plutonium on the other hand,
does not exist in nature. It is generated in the fuel
of a normally operating nuclear reactor when a
uranium-238 atom absorbs a neutron. When used solely to
produce electricity, reactors would not
produce plutonium with the quality of that used
in a nuclear weapon. But just to make sure,
Iran has agreed to take all of the irradiated
fuel that contains the plutonium and send
it out of the country. So we feel very, very secure
that the plutonium pathway is very, very well blocked. To be clear, this deal is not
built on trusts – Iran has agreed to extraordinary
transparency and verification. The International Atomic
Energy Agency, the IAEA, is the premiere organization
in the world for detecting and monitoring nuclear
activity in all the countries that have signed up to the
Non-Proliferation Treaty. At declared sites,
inspectors will have regular access with as
little as two hours’ notice. International inspectors
will have access not just to enrichment facilities, but also
to the full uranium supply chain; from mines to centrifuge
manufacturing and operation. And this access to the
uranium supply chain comes with a 25 year commitment. To evade detection, Iran would
need to successfully hide an entire supply chain and that
would be an extremely risky and difficult undertaking. At undeclared sites suspected
of nuclear activity, inspectors would have access
in as few as 24 hours. If Iran disputes
access to a site, this agreement provides a
crucial new tool by providing a specified time: 24
days to gain access. To be clear, the duration of
the agreement is indefinite. Some provisions will be
in place for 10 years, others for 15, and still
others for 20 or 25. But transparency requirements
and Iran’s most fundamental obligation – it’s commitment to the
United States and our partners to forego a nuclear weapons
program are permanent. The science that underpins this
agreement gives me confidence that this is the best possible
opportunity to eliminate the existential threat of
an Iranian nuclear weapon and protect America, our
allies, and global security. Thanks for watching.

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