Nuclear Fallout
THe eND is an interactive map that models the consequences of a nuclear explosion at a specific point. The user selects the yield, burst type, places a target, launches the detonation, and sees the distribution of damage factors and radioactive fallout on the map. At any point, mortality, accumulated dose, and contamination level can be measured.
All calculations are performed directly in the browser. The server provides only weather data and map tiles.
For any point around the epicenter, three factors are calculated: thermal radiation, shockwave, and initial radiation. Each factor has a "value → probability of death" table based on open sources: Glasstone & Dolan (1977), FEMA recommendations, DTIC and SSK reports. Burst type is taken into account — ground or air. For air bursts, radiation is computed by slant range from the burst point, which gives a "ring" of maximum on the ground rather than a point directly below the epicenter.
The mushroom cloud is modeled as an ellipsoid (cap) plus a truncated cone (stem). Dimensions come from an empirical table by yield, from 1 kt to 30 Mt. The cloud grows over time, then drifts with the wind. Trajectories of 12 points at each altitude level are tracked.
Fallout is formed from soil lifted by the explosion. Particles are divided into four size fractions: F1 (light, 50–90 µm), F2 (fine, 90–200 µm), F3 (medium, 200–500 µm), F4 (coarse, 500–1000 µm). Smaller particles have higher specific activity. Superheavy particles (>800 µm) are tracked separately — they settle fastest and produce the densest spot near the epicenter.
Particles do not leave the cloud instantly. A Weibull distribution is used: for each combination of fraction, altitude, and cloud zone there is a specific delay period. Heavy particles fall quickly and close to the epicenter, light ones — slowly and far.
Calculated using Stokes' law with Cunningham correction for the smallest particles and turbulent flow correction for the larger ones.
Weather data — NOAA GFS, updated every 6 hours, ten altitude levels from 100 m to 42 km. Wind at any point is computed by four-dimensional linear interpolation over latitude, longitude, altitude, and time.
Rain washout and random particle walk under turbulence are taken into account. Both factors noticeably widen the fallout footprint.
Dose rate decreases by a power law with time since the explosion. Accumulated dose at a point is computed as the sum of contributions from all particles, taking into account distance and arrival time.
Burns, blast trauma, and radiation interact. Combined injuries produce higher mortality than each factor alone. The model combines the three probabilities not by sum or maximum, but by a non-linear formula with amplification. This matches clinical data on reduced survival thresholds in combined injuries.
Each type of shelter attenuates each factor by its own coefficient. Trench, house (frame, brick, brick with shuttered windows), basement, bunker with adjustable depth. The house has three states determined dynamically: destroyed, burned down, windows blown out. For the bunker, depth is taken into account, and separately — crater, air wave attenuated by soil, and seismic impact.
Detailed physical documentation with formulas, constants, and source references — in the file PHYSICS.md.
Questions and suggestions: theend@thnd.ru