Thermonuclear · United Kingdom · 1957
Grapple X
Grapple X test
The success that made the United Kingdom the third thermonuclear power.
See Grapple X in the 3D simulator- Yield
- 1.8 MtDocumented
- Energy
- 7.53 PJ
- Type
- First true British thermonuclear device
- Period
- Cold War
- Status
- Single test
Grapple X releases about 120 times the energy of Little Boy (Hiroshima, 1945).
Key points
- The United Kingdom then carried out Grapple Y (~3 Mt), its most powerful test.
History
After disappointing first Grapple tests, Grapple X exceeded expectations. It paved the way for the Mutual Defence Agreement with the United States (1958).
- May 1957 First Grapple tests (yields below expectations).
- 8 November 1957 Grapple X: 1.8 Mt.
- 1958 US–UK Mutual Defence Agreement.
How does it work?
A thermonuclear weapon (“H-bomb”) first uses a fission explosion, which creates the extreme conditions needed to fuse light nuclei (hydrogen isotopes).
Fusion releases a lot of energy per unit of mass and is not limited by a critical mass: this is what makes the megaton range and beyond possible.
One megaton (Mt) is the energy of one million tons of TNT, about 4.2 × 10¹⁵ joules.
Deliberately general explanations: the application provides no design or manufacturing information.
Frequently asked questions
How powerful is Grapple X?
Grapple X has an estimated yield of 1.8 Mt of TNT equivalent, about 7.53 PJ of energy.
What is the history of Grapple X?
Single test, on 8 November 1957, near Christmas Island (Kiritimati). After disappointing first Grapple tests, Grapple X exceeded expectations. It paved the way for the Mutual Defence Agreement with the United States (1958).
What does the Grapple X explosion look like?
The Bomb Simulator shows the fireball, shock wave and cloud of Grapple X at real scale, over Paris, London or New York, with the sources and reliability of each value.
Sources
- Operation Grapple — Wikipedia (overview, to be cross-checked)
Other weapons
- Trinity — 25 kt
- Little Boy — 15 kt
- Fat Man — 21 kt
- RDS-1 — 22 kt
- Hurricane — 25 kt
- RDS-6s — 400 kt
- Gerboise Bleue — 70 kt
- 596 — 22 kt
- Davy Crockett — 20 t
- Ivy Mike — 10.4 Mt
- Castle Bravo — 15 Mt
- RDS-37 — 1.6 Mt
This application is an educational tool. The animations and effect zones are simplified representations meant to illustrate orders of magnitude. They are neither a prediction of the effects of a real weapon nor a military planning tool.