Nuclear Weapon Factsheet and FAQ

Women with confused expression

CND Peace Education work in schools and colleges throughout England. Young people have lots of great questions about nuclear weapons. So CND thought a factsheet covering such questions might be useful, and that’s the aim of this post.

Hiroshima & Nagasaki

What type of bombs fell on the cities?

A single atom bomb fell on each city. Each had about the same power. But they had very different designs.

The Hiroshima bomb used uranium. Two lumps of uranium joined to make a bigger lump. The extra weight made the bomb explode.

The Nagasaki bomb used plutonium. The bomb first compressed the plutonium. The extra density made the bomb explode.

How far did the damage extend?

Nearly everything lay in ruins up to three miles[1]. Roughly the same area of ten thousand football pitches.

Roof tiles dislodged up to five miles. Glass broke up to twelve miles.

How long did radiation on the ground last?

Black radioactive rain fell on large regions of both cities.

At Hiroshima, it took one year for the radiation on the ground to drop to a safe level.

At Nagasaki, it took nine years for radiation to drop[2].

Nagasaki took longer because of the different bomb design[3].

How many people lived in the cities?

In Hiroshima 350,000 people. Nearly all civilians[4].

In Nagasaki 240,000 people. Nearly all civilians[5],[6].

How many people died?

In the first few months after the bombs, over 210,000 people died4,5.

How can we comprehend this number? Picture the victims lay down on the ground, shoulder to shoulder. That line would stretch out over fifty miles. To count each victim one by one would take three days non-stop[7].

In later years, thousands continued to die from their injuries[8].

Any photos from within the cities?

At Hiroshima, seven photos survive from the day of the bomb[9],[10].

In Nagasaki, about a hundred photos survive from one day after the bomb[11].

Many more photos exist from later times (eg. see and

Nuclear Weapons (nukes)

What’s an A-bomb?

An atom bomb (A-bomb) is a weapon that gets its immense power from nuclear fission.

In fission, the nucleus of an atom splits. With enough nuclei close together, one atom split causes other atoms to split – a ‘chain reaction’.

Fission only happens in heavy metals like uranium and plutonium. Plutonium is the substance of choice, as less is needed to make a bomb.

What’s an H-bomb?

The hydrogen bomb (H-bomb) gets its power from nuclear fusion.

Fusion happens when two hydrogen nuclei bind together. It has to be very hot for fusion to happen. An A-bomb within the H-bomb produces that heat.

H-bombs are up to a thousand times the power of A-bombs.

Does an H-bomb produce radiation?

The A-bomb part makes the radiation; the hydrogen part does not.

Why does the chain reaction stop when a nuke explodes?

The chain reaction carries on as long as the warhead stays in one piece. Once the bomb explodes, it shatters into many pieces. So the chain reaction stops.

What’s a warhead?

An A-bomb or an H-bomb

What’s a missile?

A rocket attached to one or more warheads.

Sometimes ‘missile’ refers to the rocket and warhead combined.

How long does the radiation last on the ground?

It depends on the power of the bomb and how far above the ground it explodes. Here are three cases.

  • A few weeks before Hiroshima, the US tested a nuke close to the ground at a New Mexico desert. It sucked up a lot of sand, which melted and mixed with radiation. Radioactive liquid glass rained down on the local area. Radiation today is still 90 times above the safety limit[12].
  • Hiroshima took one year to reach a safe level, and Nagasaki nine years2.
  • Over sixty years ago, the US tested over sixty nukes in the Marshall Islands. Four islands are still radioactive (Bikini, Runit, Enjebi and Naen). Bikini is a thousand times worse than Chernobyl or Fukushima[13]. (Naen island isn’t even nearby – it’s one hundred miles away).

Is it easy to make a nuke?

It takes a vast amount of time and effort.

The first two A-bombs cost billions of dollars to make. They employed over 130,000 people and took more than three years to finish[14].

Do nukes produce nuclear waste?

To make and maintain nukes creates a certain amount of nuclear waste.

It’s like other nuclear wastes[15], but there’s much less of it[16].

How do you get rid of a nuke?

The warhead is first taken off its missile and put into storage. Then it’s taken apart piece by piece, in the reverse order to its build[17].

The US had a neat way to get rid of warheads. They burnt old Russian warheads in power stations to produce electricity. Enough to power one in ten light bulbs[18]. And dispose of twenty thousand warheads. Sadly, this no longer happens.

Today’s Threats

How many countries have nukes?

Nine countries own nukes (UK, France, US, China, Russia, North Korea, India, Pakistan and Israel).

Other countries might be trying to get them[19].

Could a random fire cause a nuke to explode?

British nukes are designed not to explode in a fire[20].

But they are not fully immune. A fire can spread radiation over a wide area[21]. That’s why people worry about the routine transport of nukes on British roads[22]. Especially people living nearby.

What’s the Doomsday Clock?

The Doomsday Clock is a symbol. It warns about the threat of nuclear war and other man-made disasters. The closer to midnight, the closer to disaster.

Right now (2020) it’s a hundred seconds to midnight – the closest to midnight ever.

Could a cyber-attack launch a nuke?

A cyber-attack might fool leaders to think an attack had started[23]. In reply, thousands of nukes might launch for real.

Could terrorists get a nuke?

Some have already tried [24]. One day they might succeed[25].

That it has not happened yet is not an excuse for complacency. It’s a chance to prevent it. And the only way to do so is to get rid of nukes and their materials.

What happens if a nuke explodes in a city?

The online tool Nukemap draws a map of the damage from a nuke.

Type in an address, and Nukemap displays the blast, fire and radiation zones. It also gives the number of dead and injured.

What happens if a nuke explodes near the sea?

Nukemap (see above) maps out the main damage[26].

Also, the mushroom cloud sucks up vast amounts of seawater. The water picks up radiation, then floods the local area with black radioactive rain[27].

What’s fallout?

Radioactive dust or rain falling to the ground after a nuke explodes.

How far can fallout travel?

Lethal fallout can cover an area up to 350 miles long and sixty miles wide[28]. That’s more than twice the size of Wales.

How many nukes does it take to destroy the planet?

There must be a nuclear war of some type. This could be a ‘small’ war, with a hundred or so nukes, say between India and Pakistan. Or it could be a large war with thousands of nukes, say between US and Russia.

Even a small nuclear war will badly damage the planet. Cities and forests burn out of control. Vast amounts of smoke rise into the sky and surround the earth with a shroud of soot. Sunlight is blocked, temperatures plummet and crops fail. Two billion people might starve[29].

The chance of a small nuclear war is higher now that the US plan to use Hiroshima-type weapons in ordinary war.

A large nuclear war will cause a full-blown Ice Age. Most would not survive[30].

Could I survive if a nuke explodes near me?

In 1980, the UK produced the pamphlet Protect and Survive[31]. If the worst should happen, the pamphlet tells us to shelter in a nearby building and await help. The US has similar advice[32].

But will buildings exist in which to take shelter? It’s doubtful – not up to twenty-five miles from the blast[33].

And don’t count on any help. Radiation on the ground would prevent rescue workers from getting to you. The whole country would probably be in ruins.

If there’s enough distance between you and the blast you will survive. But life will be grim, like never before.

Ban Treaty

Is there a law that bans nukes?

The Ban Treaty is an international law that bans nukes. Sixty-three per cent of nations support the Treaty[34].

It’s not quite law yet. It needs fifty countries to ‘ratify’ it (give formal consent). So far forty have done so (August 2020).

Even when it becomes law, countries with nukes won’t have to give them up.

But as more and more countries ratify, it’s hoped that nuclear countries will come to their senses.

Why should a country sign?

Reasons include:

  • Vision. The very first resolution of the first meeting of the United Nations in 1946 pledges to ban nukes[35]. Deep inside, we all want a world of amity and trust and peace, so why not work towards it?
  • Money. The US alone would save over a trillion dollars if it scrapped its nukes[36].
  • Law. Using them is already a war crime in most cases[37].
  • Morality. The Church of England makes a strong moral case in support of the Ban Treaty. Bruce Kent makes a striking analogy to Nazi concentration camps.
  • See also ‘Arguments Against Trident‘.

Is a ban likely?

The world has banned biological and chemical weapons, so why not nukes?

Some say a ban cannot work as ‘the genie’s out of the bottle’. We can’t uninvent nukes – the knowledge is out there.

But knowledge is not enough. It takes a huge amount of time, effort and equipment. Time enough to prevent their build.

More Questions?



  1. The Manhattan Engineer District, 1946. The Atomic Bombings Of Hiroshima And Nagasaki. [online] United States Army, pp. 4,24. Available at: <> [Accessed 3 August 2020].

  2. Radiation Effects Research Foundation, Hiroshima (Japan) Roesch, William C. (Ed.). (1987). US-Japan joint reassessment of atomic bomb radiation dosimetry in Hiroshima and Nagasaki DS86 Dosimetry System 1986 Vol 1. Japan: The Radiation Effects Research Foundation, pp. 207,209,211,223. Available at: <> [Accessed 10 August 2020]. [Hiroshima Ground Dose Calculation: Koi-Takasu is the worst affected area. It is 2 miles west of the epicentre. Black rain fell on the region. The report estimates the total exposure between 1 to 3R. From Table 4 this gives a value of Io as 0.6 R/hr. The internationally recognised dose limit to the public is 100 mrem/yr, which is 1.14 x 10-5 R/hr. The time to reach the safe limit is given by the 1.2 root of 0.6/1.14 x 10-5, which is 8,590 hours (0.98 years)]. [Nagasaki Ground Dose Calculation: Nishiyama is the worst affected area. It is 2 miles east of the epicentre. Black rain fell on the region. The report estimates the total exposure between 20 to 40R. From Table 2 this gives a value of Io as 8.4 R/hr. The internationally recognised dose limit to the public is 100 mrem/yr, which is 1.14 x 10-5 R/hr. The time to reach the safe limit is given by the 1.2 root of 8.4/1.14 x 10-5, which is 77,500 hours (8.8 years)].

  3. Pace, N. and Smith, R.E., 1959. Measurement Of The Residual Radiation Intensity At The Hiroshima And Nagasaki Atomic Bomb Sites. ABCC technical report series, 26-59. [online] Hiroshima: Atomic Bomb Casualty Commission, p.2. Available at: <> [Accessed 13 August 2020].

  4. Hiroshima Peace Memorial Museum, 2004. The Outline Of Atomic Bomb Damage In Hiroshima. Hiroshima: Hiroshima Peace Memorial Museum, pp.1,4.

  5. The City of Nagasaki, 2011. Records Of The Nagasaki Atomic Bombing. Nagasaki: The City of Nagasaki, p.14.

  6. Johnston, W., 2005. Nagasaki Atomic Bombing, 1945. [online] Available at: <> [Accessed 30 January 2019].

  7. Moran, L., 2017. Watch This Guy Count To 100,000 For No Reason Whatsoever. [online] The Huffington Post. Available at: <> [Accessed 15 August 2020]. [It took 40 hours to count to 100,000. Extrapolating to 210,000 gives 84 hours (3.5 days)].

  8. UN News. 2015. No More Hiroshimas. No More Nagasakis, Ban Declares On Anniversary Of Atomic Bombing. [online] United Nations. Available at: <> [Accessed 4 August 2020]. A staggering 400,000 more deaths occurred after 1946 as a result of the bombs.

  9. Selwyn-Holmes, A., 2010. Hiroshima, 6th August 1945. [online] Available at: <> [Accessed 8 August 2020].

  10., 2020. Yoshito Matsushige. [online] Available at: <> [Accessed 7 August 2020].

  11. Gye, H., 2014. Haunting Photographs Of Nagasaki In The Wake Of Atomic Bomb Attack. [online] Daily Mail. Available at: <> [Accessed 7 August 2020].

  12. US Army, 2018. White Sands Missile Range: Trinity Site: Radioactivity. [online] US Army. Available at: <> [Accessed 4 August 2020]. [Calculation Of Ground Dose Rate: The current dose rate is 1mrem/hour at ground zero. The internationally recognised dose limit to the public is 100 mrem/yr, which is 1.14 x 10-2 mrem/hr. So the dose rate at ground zero is 1/1.14 x 10-2, which is 87.7 times greater than the safety limit.]

  13. Abella, M. et al., 2019. Background Gamma Radiation And Soil Activity Measurements In The Northern Marshall Islands. [online] Proceedings of the National Academy of Sciences, 116(31), p.15432. Available at: <> [Accessed 4 August 2020].

  14. CTBTO Preparatory Commission, 2012. History Of Nuclear Testing: Manhattan Project. [online] Comprehensive Nuclear Test Ban Treaty Organization. Available at: <> [Accessed 25 January 2019].

  15. Nuclear Decommissioning Authority, 2014. Factsheet: Wastes From Defence Activities. [online] NDA. Available at: <> [Accessed 19 March 2020].

  16. Nuclear Decommissioning Authority, 2017. Radioactive Wastes In The UK: A Summary Of The 2016 Inventory. [online] Cumbria: NDA, p.7. Available at: <> [Accessed 3 August 2020].

  17. Atomic Weapons Establishment (AWE), 2018. Why Dismantle A Perfectly Good Warhead?. New Discovery Magazine, Spring/Summer Edition Issue 2. [online] Berkshire: AWE Aldermaston, p.29. Available at:

    <> [Accessed 4 August 2020].

  18. Rosen, A., 2015. Until 2013, 10% Of US Electricity Came From Disassembled Russian Nuclear Warheads. [online] Business Insider. Available at: <> [Accessed 4 August 2020].

  19. Lockey, R., 2016. Which Countries Today Will Likely Develop Nuclear Weapons In The Future And Why?. [online] Available at: <> [Accessed 8 August 2020].

  20. Gilbey, M., 2017. Local Authority and Emergency Services Information (LAESI) Edition 11. [online] London: Ministry of Defence, p.4. Available at: <> [Accessed 3 August 2020].

  21. Brooke-Holland, L., 2016. Nuclear Convoys. [online] London: House of Commons Library, p.7. Available at: <> [Accessed 5 August 2020].

  22. Edwards, R., 2016. Nukes Of Hazard. [online] ICAN-UK and the Acronym Institute for Disarmament Diplomacy. Available at: <> [Accessed 7 August 2020].

  23. Unal, B. and Lewis, P., 2018. Cybersecurity of Nuclear Weapons Systems: Threats, Vulnerabilities And Consequences. London: The Royal Institute of International Affairs Chatham House, p2. Available at: <> [Accessed 3 August 2020].

  24. Bunn, M. and Roth, N., 2017. The Effects Of A Single Terrorist Nuclear Bomb. [online] Bulletin of the Atomic Scientists. Available at: <> [Accessed 1 August 2020].

  25. Allison, G., 2004. Nuclear Terrorism: The Ultimate Preventable Catastrophe. 1st ed. New York: Henry Holt & Company, p.17.

  26. Wellerstein, A., 2020. Nukemap And The Sea. [Personal Email].

  27. Rimmer, A., 2012. Between Heaven And Hell., p.149.

  28. Glasstone, S. and Dolan, P., 1977. The Effects Of Nuclear Weapons. 3rd ed. Washington: U.S. Dept. of Defense, p. 436.

  29. Helfand, I., 2013. Nuclear Famine: Two Billion People At Risk?. [online] International Physicians for the Prevention of Nuclear War, Physicians for Social Responsibility, p.2. Available at: <> [Accessed 1 August 2020].

  30. Toon, O., Robock, A. and Turco, R., 2008. Environmental Consequences Of Nuclear War. [online] Physics Today, 61(12), p.41. Available at: <> [Accessed 3 August 2020].

  31. Home Office & Central Office of Information, 1980. Protect And Survive. [online] London: Her Majesty’s Stationary Office. Available at: <> [Accessed 3 August 2020].

  32. FEMA (Federal Emergency Management Agency), 2018. Be Prepared For A Nuclear Explosion. FEMA V-1015, Catalog No. 17233-16. [online] US Department of Homeland Security. Available at: <> [Accessed 3 August 2020].

  33. Home Office and Scottish Home and Health Department, 1974. Nuclear Weapons. [online] London: Her Majesty’s Stationary Office, p.25. Available at: <> [Accessed 7 August 2020].

  34. 2017. United Nations Conference To Negotiate A Legally Binding Instrument To Prohibit Nuclear Weapons, Leading Towards Their Total Elimination. [online] United Nations. Available at: <> [Accessed 8 August 2020].

  35. United Nations, 1946. Resolutions Adopted By The General Assembly During The First Part Of Its First Session From 10 January To 14 February 1946. [online] London: United Nations, p.9. Available at: <> [Accessed 11 August 2020].

  36. Stone, M. and Ali, I., 2017. U.S. Nuclear Arsenal To Cost $1.2 Trillion Over Next 30 Years: CBO. [online] Reuters. Available at: <> [Accessed 19 August 2020].

  37. Moxley, C., Burroughs, J. and Granoff, J., 2011. Nuclear Weapons and Compliance with International Humanitarian Law and the Nuclear Non-Proliferation Treaty. [online] Fordham International Law Journal, 34(4), p.642. Available at: <> [Accessed 4 August 2020].

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