Nuclear Security: FAQ

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What is nuclear terrorism?
There is no singular agreed-upon definition for nuclear terrorism. However, a reasonable definition is that it is when a terrorist detonates a nuclear bomb, disperses radioactive material in a so-called “dirty bomb,” or sabotages a major nuclear facility. Some would also include threats, attempts, or assistance in carrying out such acts.

Can terrorists make nuclear bombs?
Unfortunately, it does not take a Manhattan Project to make a nuclear bomb; more than 90 percent of the effort in that project was focused on making the needed nuclear material. Numerous government studies in the United States and other countries have concluded that if they got the needed plutonium or highly enriched uranium (HEU) it is plausible that a sophisticated terrorist group could make a crude nuclear bomb. Such a bomb could potentially turn the heart of a major city into a smoldering radioactive ruin. Making a crude, unsafe, unreliable terrorist bomb that might be delivered in the back of a truck is far easier than making a safe, reliable nuclear warhead for delivery by missile or aircraft.

Have terrorists tried to build nuclear weapons?
Yes. Al Qaeda and Aum Shinrikyo both tried to get nuclear weapons, and there is some evidence that terrorists from Chechnya and nearby regions of the North Caucasus have tried as well. Al Qaeda had a focused nuclear weapons program reporting directly to Ayman al-Zawahiri, now the group’s leader. This effort included repeated attempts to purchase nuclear material and recruit nuclear expertise, and got to the point of carrying out crude explosive tests for their nuclear program in the Afghan desert.

What is nuclear material? What makes some nuclear material usable in a nuclear bomb?
Nuclear material is material that contains atoms that can readily be split, or fissioned, by being struck by a neutron, primarily uranium or plutonium. Fission releases energy (roughly 10 million times as much for each atom as is released in chemical reactions), and each atom split by a neutron typically releases two or more neutrons, creating the potential for a chain reaction. Nuclear material can be used to make a nuclear bomb, if there are enough atoms that can be fissioned to support a chain reaction that grows explosively. Such material is often known as “weapons-usable” nuclear material. Nuclear material of the quality weapons designers prefer for nuclear weapons is known as “weapon-grade” material (typically containing 90-93% or more uranium-235 or plutonium-239), but nuclear weapons can be made from material that is not weapons-grade. Ironically, the bomb that destroyed Hiroshima in 1945 was made from material with an average enrichment of about 80% U-235 and would not be considered “weapon-grade” today.

What nuclear materials are used in nuclear bombs?
Highly enriched uranium (HEU) – defined as uranium containing 20 percent or more U-235 -- and plutonium are the nuclear materials used in today’s nuclear weapons. These materials do not exist in nature in any significant quantity and are so difficult to produce that it is implausible that terrorists would be able to do so.

How much HEU would a terrorist likely need to make a nuclear bomb?
To get a substantial explosion out of the simplest type of nuclear bomb, known as a “gun-type” bomb, requires 50-60 kilograms of 90% enriched HEU metal, an amount that would fit into two 2-liter bottles. If the terrorists were able to make a crude “implosion-type” bomb, less material would be needed. But if the HEU was less than 90% enriched, somewhat more would be needed.

What is the global stockpile of HEU?
At the end of 2012, the best available estimates suggest there were still nearly 1400 tons of HEU in the world, enough for some 25,000 simple gun-type bombs. Nearly all of this stock was produced for military uses, but there are scores of civilian sites around the world that still use HEU as well. Most of the world’s stock of HEU is in Russia or the United States, but it exists in over two dozen countries.

How much plutonium would be required for a nuclear bomb?
The bomb used to destroy the city of Nagasaki reportedly used only about 6 kilograms of plutonium. That amount would almost fit into a soda can.

What is the global stockpile of separated plutonium?
As of January 2014, there were more than 500 tons of separated plutonium, mostly located in the United Kingdom, France, United States, Russia, and Japan. This material is roughly half military and half civilian.

What is “nuclear security”?
The prevention and detection of, and response to, theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving nuclear material, other radioactive substances or their associated facilities. (International Atomic Energy Agency)

What is “nuclear safety”?
Preventing an accident at a facility where nuclear material is located. It can be at a reactor accident like the one in Fukushima, Japan. It can also be at a facility like the one in Oak Ridge, where nuclear material is processed. (International Atomic Energy Agency)

What is “nuclear nonproliferation”?
Preventing the spread of nuclear weapons to additional countries or groups.

What is a “dirty bomb”?
A dirty bomb is a device to spread radioactive material, for example with conventional explosives, to contaminate an area.

Is a “dirty bomb” a nuclear weapon?
No. A dirty bomb does not result in a nuclear explosion, but simply spreads radioactive material. It could create panic, force the evacuation of a substantial area, and result in an expensive and disruptive mess, but it could not incinerate the heart of a major city as a nuclear bomb could.

How many nuclear weapons are there in the world?
As of 2013, declassified estimates state that the total number of deployed, reserve, and retired nuclear weapons is approximately 17,000.

How many countries have eliminated their nuclear material?
30 countries have eliminated their stockpiles of nuclear material since 1992.

How many nuclear buildings are there worldwide containing HEU or separated plutonium?
Hundreds; no complete accounting is available.

Is there enough missing nuclear material to make a bomb?
No one knows for sure. In the United States, over two tons of plutonium is officially unaccounted for. Probably none of that material was stolen, but the accounting was so poor no one will ever be able to tell for sure. The nuclear material accounting system in the Soviet Union was even less accurate. In 2005, the director of the U.S. Central Intelligence Agency testified that it was the agency assessed that “there is sufficient material unaccounted for [from Russian nuclear facilities] so that it would be possible for those with know-how to construct a nuclear weapon.”

How could terrorists deliver a nuclear weapon to its targets?
Through the same routes as drugs, illegal immigrants, and legal goods.

What could be the physical effects of a nuclear terrorist attack?
A 10-kiloton nuclear bomb set off at Times Square on a typical workday could kill half a million people and spread deadly fallout many miles downwind.

What would be the economic impact?
A study by the RAND Corporation estimated that the early, direct economic costs of a nuclear terrorist attack on a US port would exceed $1 trillion, about ten times the cost of 9/11. There would be immediate pressure to close all US ports to prevent another attack. Given that US ports carry out 7.5% of all global trade activity, the consequences for the world economy would be catastrophic. Former UN Secretary-General Kofi Annan has argued that a nuclear terrorist attack “would stagger the world economy and thrust tens of millions of people into dire poverty,” creating “a second death toll throughout the developing world.”

Can nuclear terrorism be prevented?
Yes. The most important single step to prevent nuclear terrorism is to secure all nuclear weapons and nuclear weapons useable material, so they can't be stolen and fall into terrorist hands. No nuclear material available to terrorists – no nuclear terrorism.

What is the purpose of the nuclear security summit in Washington, DC?
As with previous summits held in Washington in 2010, Seoul in 2012, and The Hague in 2014, the 2016 nuclear security summit in Washington, DC will serve to raise awareness of the nuclear terrorism threat and focus government on actions to reduce it. This will likely be the last nuclear security Summit. States will present plans to sustain momentum behind the international nuclear security effort after the summit process has ended.

See also: Q&A