This is measured in Rads. You have a Radiation Threshold (RT) of 100. Whenever your RT reaches a multiple of 100 your RL (Radiation Level) increases by 1 Sievert (Sv).
-At 1 Sv you begin suffering from Radiation Sickness. In addition to a 20 pt penalty to all skills, the Radiation Sickness makes an attack roll against you once per day with a 15% “skill” and base lethality of Minor. Toughness may be rolled to resist. Resulting wounds do not heal on their own or with natural medicine.
-At 2 Sv you suffer from Extreme Radiation Sickness. The base lethality increases to non-lethal and It’s attack “skill” increases to 30%. In addition, the character continues to suffer a 20 pt penalty on all rolls and must roll vs. nausea once per round during combat or similarly taxing endeavors.
-At 3 Sv you begin suffering from Radiation Poisoning. The radiation’s base lethality remains non-lethal but its “attack skill” increases to 45% and increases another 15% for every additional Sv. Additionally, you must roll vs Nausea once per hour during mildly taxing endeavors and you suffer a 1 level of success penalty per Sv over 2 in place of the previous 20 pt flat penalty.