Joe-1 (RDS-1)
USSR · 1949 · 22 kilotons · pure fission
Overview
First Soviet nuclear test.
With a yield of 22 kilotons, the Joe-1 (RDS-1) is comparable in yield to the Hiroshima bomb. As a pure fission weapon, it derives its energy from nuclear fission of uranium or plutonium.
Joe-1 (RDS-1) 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 | 0.50 km | 0.40 km |
| Severe blast (20 PSI) | 1.34 km | 0.74 km |
| Moderate blast (5 PSI) | 2.86 km | 1.57 km |
| Light blast (1 PSI) | 8.13 km | 4.47 km |
| 3rd-degree thermal burns | 2.38 km | 1.43 km |
| 2nd-degree thermal burns | 4.26 km | 2.56 km |
| Lethal fallout zone | minimal | ~41.3 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 Joe-1 (RDS-1) on a City
Use the interactive simulator to detonate the Joe-1 (RDS-1) 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 Joe-1 (RDS-1)Related Weapons
FAQ
How big is the Joe-1 (RDS-1) blast radius?
In an air burst, the Joe-1 (RDS-1) produces a fireball roughly 0.50 km in radius and a 5 PSI moderate-blast zone of about 2.86 km — the area in which most residential buildings would collapse. The 1 PSI light-damage radius extends to roughly 8.13 km, where windows shatter.
What is the yield of the Joe-1 (RDS-1)?
The Joe-1 (RDS-1) has a yield of 22 kilotons of TNT equivalent. That is comparable in yield to the Hiroshima bomb.
Is the Joe-1 (RDS-1) bigger than the Hiroshima bomb?
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The Joe-1 (RDS-1) at 22 kilotons is comparable in yield to the Hiroshima bomb.
What thermal burn radius does the Joe-1 (RDS-1) produce?
Thermal radiation from the Joe-1 (RDS-1) can cause 3rd-degree burns out to roughly 2.38 km and 2nd-degree burns out to 4.26 km in an air burst. Surface bursts reduce these radii by approximately 40 percent due to ground absorption.