This Demonstration simulates a nuclear power plant meltdown on Mars and calculates the required time for a base near the plant to become habitable again. The pink disk represents the uninhabitable zone (area where radiation levels are greater than 500 millirems), the red disk represents the area that has radiation levels twice the level deemed habitable, and the maroon disk represents the area that has radiation levels four times the level deemed habitable. The black circle represents the distance between home and the nuclear power plant, which is located at the origin.
You can select the type of radioactive particles emitted, the number and half-life of the radioactive atoms, the distance between home and the nuclear power plant, and the number of years after the nuclear meltdown has occurred.
On a planet with an atmosphere, the ranges would be much shorter for alpha particles.
This Demonstration describes a theoretical power plant where the radioactive elements remain in the plant and only radioactive particles are allowed to escape. The simulation does not factor in the interactions between the radioactive particles and any gases present in the Martian atmosphere. It also assumes that the mass of a human is 70 kg, that an particle travels at 7.5% of the speed of light, and that a particle travels at 90% of the speed of light.