Castle Yankee
USA · 1954 · 13.5 megatons · thermonuclear (hydrogen bomb)
Overview
Second Castle series test.
With a yield of 13.5 megatons, the Castle Yankee is 900× more powerful than the Hiroshima bomb. As a thermonuclear (hydrogen bomb) weapon, it derives its energy from a fission primary that ignites a much larger fusion secondary stage.
Castle Yankee Blast Effects
The table below shows the calculated radius of each effect zone for an air burst (optimal altitude, maximum blast spread) and a surface burst (ground level, with massive radioactive fallout). Formulas are scaling laws from The Effects of Nuclear Weapons (Glasstone & Dolan, 1977).
| Effect zone | Air burst | Surface burst |
|---|---|---|
| Fireball radius | 6.51 km | 5.21 km |
| Severe blast (20 PSI) | 11.12 km | 6.12 km |
| Moderate blast (5 PSI) | 23.76 km | 13.07 km |
| Light blast (1 PSI) | 67.59 km | 37.17 km |
| 3rd-degree thermal burns | 33.08 km | 19.85 km |
| 2nd-degree thermal burns | 59.24 km | 35.54 km |
| Lethal fallout zone | minimal | ~538.7 km |
All values are 1-D ground-distance estimates from the detonation point. Real-world effects depend on terrain, weather, and building construction.
Run the Castle Yankee on a City
Use the interactive simulator to detonate the Castle Yankee on any city worldwide. Click any location on the map to see the fireball, blast, and thermal radii overlaid on real geography with population-density-based casualty estimates.
🎯 Simulate Castle YankeeRelated Weapons
FAQ
How big is the Castle Yankee blast radius?
In an air burst, the Castle Yankee produces a fireball roughly 6.51 km in radius and a 5 PSI moderate-blast zone of about 23.76 km — the area in which most residential buildings would collapse. The 1 PSI light-damage radius extends to roughly 67.59 km, where windows shatter.
What is the yield of the Castle Yankee?
The Castle Yankee has a yield of 13.5 megatons of TNT equivalent. That is 900× more powerful than the Hiroshima bomb.
Is the Castle Yankee bigger than the Hiroshima bomb?
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The Castle Yankee at 13.5 megatons is 900× more powerful than the Hiroshima bomb.
What thermal burn radius does the Castle Yankee produce?
Thermal radiation from the Castle Yankee can cause 3rd-degree burns out to roughly 33.08 km and 2nd-degree burns out to 59.24 km in an air burst. Surface bursts reduce these radii by approximately 40 percent due to ground absorption.