Nuclear transformations and some electronic rearrangements can yield highly energetic particles and photons. Colloquially these are called 'radiation'.
The damaging effects produced by radiation arise from molecular disruption (direct effect) and energy transfer leading to the production of charged species called free radicals (indirect effect) which can bind to other molecules, impairing their function.
There are dose-dependent (nonstochastic) effects which are an inevitable consequence of a given dose (e.g. skin burns). Stochastic effects are those whose probability of occurrence is related to dose, e.g., leukaemia or thyroid cancer.
Dosage is the amount of energy absorbed per unit mass. It is measured in rads (radiation absorbed dose) (1 rad = 0.01J/kg) or grays (Gy) (1 Gy = 1J/kg).
Biological effect is related to the amount of energy and the way in which it is transferred along the trajectory of the particle or photon.
Dose equivalent = absorbed dose * quality factor
The units of dose equivalent are the rem (one rad of radiation with a quality factor of one) and the sievert (Sv - one gray of radiation with a quality factor of one).
|Radiation Types and Quality Factors|
|Radiation Type||Quality Factor||Comments|
|X-rays and Gamma rays||1||High-energy photons|
|Beta particles||1||Energy > 0.03 MeV|
|1.7||Energy < 0.03 MeV|
|Alpha particles||10||Helium (He) nuclei|
|neutrons||2||Energy < 1 keV|
|2.5||Energy 1 - 10 keV|
|7.5||Energy 10 - 100 keV|
|11||Energy 500 keV - 1 MeV|
|10||Energy unknown or not specified|
- Alpha particles
- Alpha particles have 2 protons and two neutrons. They are therefore quite large (large damage potential) and have poor penetrative ability.
- Beta particles
- Beta particles are electrons or positrons. The slower they are the more damage they can cause (more chance to form free radicals or gamma rays in tissue).
- Neutrons are uncharged and therefore have good penetrative ability. Their damage potential is high because of this and their size.
- Electron Volts (eV)
- The electron volt is an energy unit. An electron which moves across a potential difference of one volt has a kinetic energy of one electron volt. It is equal to 1.6 X 10^(-19)J.
We are continually bathed in low-level radiation. The discovery of nuclear energy and electronics adds several new sources to the mix.
There are two sources in this category, cosmic rays and terrestrial radiation (originating from radioactive material in the planet and in our bodies).
- Cosmic Radiation
- The origin of cosmic radiation is still not yet understood. There is a background throughout known space of high energy protons (~87%), alpha particles (~11%) and other nuclei and electrons. Energy levels range between 10^8 and 10^20 eV, with the majority between 10^8 and 10^11eV.
- Baseline 2.7 rem per year (unprotected) - range 27 mrem to 7.3 rems per year. (mrem = millirem or 1/1000 rem)
- Radiation belts, particularly around gas giants, can have levels up to a *thousand times* greater than this.
- Standard atmospheres absorb most of the incident cosmic radiation. Secondary particles are generated (neutrons, photons and pions). The radiation flux varies with altitude and latitude. At 'sea level' (1 atmosphere pressure), 27 mrem per year. This doubles with every 1600m increment in altitude.
- Near the magnetic poles of a world, the exposure rate varies with the strength of the local field.
- Terrestrial radiation
- Of the elements found on or in a given world, about a fifth are radioactive. Heavy core worlds usually have larger concentrations of radioactives than are the average. Gamma rays account for nearly all terrestrial radiation. The range varies from 15 to 200mrem per year, depending on local conditions.
- Internal Radioactivity
- Internal radioactivity arises from potassium 40 (which comprises 0.0118% of body potassium - some 0.0157g in a 70kg human), and ingested environmental nuclides such as carbon 14 and radon 222. The typical exposure is 28mrem per year.
|Sources of Artificial Radiation Exposure|
|Source||Exposure in mrem per year|
|Medical||3 - 300|
|Building Materials (brick, masonry)||7|
|Power plants (plant workers)||400|
|Air and space travel||3 (passengers)|
|Television and cathode-ray displays||0.2 - 1.5|
Occupational exposures should not exceed 400mrem per year.
For character generation, assume base exposure 100mrem per year (200 if heavy core world, 50 if icy body) and 400mrem per year of service in any spacefaring or nuclear energy related field. Exposure cannot be 'rolled back' by conventional means (but see below).
Roughly 15% of the energy of a detonating nuclear weapon is high energy radiation. 'Enhanced radiation weapons' or neutron bombs are designed to increase this fraction to nearly 50%. This refers to detonations within an atmosphere ; in space, 90% of the explosion's energy is dissipated in this manner. Particle and meson beams also produce significant radiation effects at their points of impact. Almost all of a meson beam's energy is converted to gamma radiation when the mesons decay.
Radiation Exposure from
Nuclear Weapon Detonation
|Within Total Destruction Radius (obliteration)||6000|
|Within Primary Destruction Radius (unreinforced buildings flattened)||600|
|Within Secondary Destruction Radius (flash)||60|
Multiply by 3 for neutron weapon OR Multiply by 6 for detonation in space
|Radiation Exposure from Nuclear Weapon Detonation Aftereffects|
|Aftereffect||Exposure (rems per day)|
|Fallout (within blast area)||1|
(Total Destruction Radius)
(Primary Destruction Radius)
(Secondary Destruction Radius)
Multiply by 3 for neutron weapon OR Multiply by 6 for detonation in space
The half life for fallout is two hours.
The half life for induced radiation is one year.
Fallout activity is about half the radiation load of aconventional nuke, 1/10 that of a neutron bomb.
Tables have been listed in FF&S(1 and 2?), Striker and JTAS 23 for blast radii with yield.
from Particle/Meson Weapon Discharge
|Weapon Type||Exposure in rems|
(CPAW or NPAW)
|10 * intensity|
from Power Plants
due to Shielding Failure
|Type of Material||Exposure|
|Generation unit, Fission plant||(plant output in MW)/10 rem/min|
|Generation unit, Fusion plant||(plant output in MW)/5 rem/min|
|Waste or other material, High level||1 - 10 rem/hr|
|Waste or other material, Med. level||0.1 rem/hr|
|Waste or other material, Low level||1 mrem/hr|
The values above assume that you're standing right next to the source, unshielded.
- High level : highly enriched fuel or weapons grade material.
- Medium level : reactor grade fuel, 'tailings' from reprocessing plant, activated materials from within reactor vessel (e.g., old shielding, coolant).
- Low level : reactor or mine worker's protective clothing. Ores.
Distance and shielding are the primary protection methods after exposure minimisation. Radiation intensity falls with the square of distance from the source. (1/4 at 2m, 1/9 at 3m, etc..)
Efficacy depends on material and its thickness. The table below shows the thickness of material required to reduce the intensity of gamma radiation by 50%. Alpha particles travel 5-7cm in air, betas 2-8m. Fast neutrons (energy > 500keV ) may have more penetration than gamma rays.
for 50% Reduction
in Gamma Radiation Intensity
|Material||Thickness in cm|
|Dose Reduction Multiplier for Personal Armour|
|Type of Armor||Standard||Hostile Environment|
|Vacc Suit, TL7 - TL9||0.9||0.8|
|Vacc Suit, TL10 - TL11||0.8||0.6|
|Vacc Suit, TL12 - TL13||0.7||0.5|
|Vacc Suit, TL14 - TL15||0.6||0.4|
|Battle Dress, TL13||0.3|
|Battle Dress, TL14||0.2|
|Combat Environment Suit, TL10||0.7|
|Combat Armour, TL11||0.4|
|Combat Armour, TL12||0.3|
|Combat Armour, TL14||0.2|
|NBC*/Hazmat Suit, TL6 - TL7||0.9|
|NBC/Hazmat Suit, TL8||0.8|
|*NBC - nuclear-biological-chemical|
Composites or plastics containing elements with good neutron capture or absorption properties e.g., boron, cadmium, silver, indium, graphite, beryllium, and hydrogen will have better values than plain composite laminate.
Alloys containing depleted uranium and similar heavy atoms will be at a penalty due to induced radiation (e.g., neutrons may cause fission).
Crystaliron, superdense materials and electropolymorphic plastics may have an extra advantage in protecting from cosmic radiation, due to the presence of the stabilising current, or its magnetic properties (crystaliron hulls are effectively a single magnetic domain). A protective belt of charged particles may form around the ship.
Whole body exposures are the most problematic. Doses which would be lethal if applied to the entire body are routinely used in radiotherapy.
Radiation most readily damages dividing cells. Those tissues which turn over rapidly are the most radiosensitive e.g., bone marrow, gonads, gut lining, cornea of the eye, and skin.
|Effects of Acute Exposure to Radiation|
|Exposure (rems)||Probable Effect on Population|
|5 - 70||Headache, nausea, vomiting for 6 - 12 hours in 10%|
|70 - 150||Nausea, vomiting for 2 - 20 hours in 30%|
|150 - 300||Nausea, vomiting, fatigue in 20% - 70%,
onset 2 hrs - 2 days after exposure
|300 - 530||Nausea, vomiting, fatigue in 50% - 90%,
onset 2 hrs - 3 days.
Inability to perform complex tasks (prompt onset).
Hospitalization 10% - 80% after 2 - 5 weeks.
Fatalities 50% at upper dose range
|530 - 830||Nausea, vomiting, fatigue in 80% - 100,
onset 2 hrs - 2 days. Skin erythema.
Hospitalization 100% within 5 weeks.
Fatalities 50% - 99%
|830 - 3000||Nausea, vomiting, weakness, diarrhoea in 100%,
onset 30 min - 2 days.
At 1000 rems: Hospitalization 100% within 6 days. Fatalities 100% within 2 - 3 weeks
At 3000 rems: Hospitalization 100% within 4 days. Fatalities 100% within 5 - 10 days
|3000 - 8000||Nausea, vomiting, diarrhoea, headache in 100%,
onset 30 min - 2 days. Partial thickness burns. Hospitalization 100% within 2 days.
Fatalities 100% within 3 days.
|Above 8000||Nausea, vomiting, headache in 100%,
onset 30 min - 1 day.
Fatalities 100% within 24 hrs.
|Optimal treatment assumed below TL13|
- Haemopoietic syndrome
- 100 to 1000 rems.
The bone marrow is suppressed or destroyed. There are few or no functional white blood cells to fight infection.
- Gastrointestinal syndrome
- 1000 to 5000 rems.
The cells lining the gut are suppressed or destroyed. Diarrhoea results from inability to absorb and exaggerated secretion of fluid. Infection is common as gut bacteria enter the body.
- Central nervous system syndrome
- 5000+ rems.
An acute inflammatory reaction takes place in the blood vessels of the brain, as well as the brain itself. The brain suffocates as oxygen can't diffuse across the inflamed vessel walls.
Effective treatment of high levels of radiation exposure are not available until TL 13.
Treatments of High-Level Radiation Exposure
Available Prior to TL13
|TL of Availability||Treatments Available (includes all lower TL treatments)|
|TL5||Antibiotics, heavy metal binders (chelators)|
|TL8||Bone marrow transplantation|
|TL10||Broad-spectrum vaccines to protect against opportunistic infections|
|Game Effects of High-Level Radiation Exposure|
|Damage level||Dose in rems||Damage||Task Penalty*||Catastrophe Check|
|Superficial||5 - 150||1D||-2||once, at 24 hrs after exposure|
|Minor||150 - 300||2D||one level of difficulty||once per week for 1D weeks|
|Major||300 - 530||4D||two levels of difficulty||once per day for one week|
|Destroyed||Above 530||6D||character incapacitated||impose 1D damage daily|
|*Task Penalty is imposed on all tasks attempted by character from exposure until treatment.|
Make consciousness check (Difficult, End).
Establish venous access, volume resuscitate (Minor+).
- To treat high-level radiation exposure
- (Difficulty), Medical, Edu, uncertain
Treatment of Radiation Exposure
Lab investigations can be ordered as per trauma articles
(These measures contribute to both success and certainty checks)
|Treatment at TL13||+4|
|Antibiotics, chelators||+1 (requires IV access)|
|Bone marrow transplantation||+2 (requires hospitalization)|
Chelation therapy is used for ingested or inhaled material (exposure to fallout, usually).
|Recovery Task Modifiers from Certainty in Treatment|
|Certainty Level||Modifier to Recovery Tasks|
Recovery rates as per trauma articles.
Some effects of radiation exposure may be delayed.
- The lens of the eye becomes cloudy and/or opaque. Check the following task 3 months after exposure:
- To avoid developing cataracts
- (exposure severity), End
Failure leads to the development of cataracts.
Treatment is required as blindness will ensue within 2D months.
Cancerous tumors develop and spread. Check the following task at each aging point after exposure
- To avoid developing a malignancy
- (exposure severity), End.
Failure leads to the detection of a malignancy.
Roll 2D to determine system
|Location of Malignancy|
|Roll 2d||System affected|
|2 - 5||Skin|
|6 - 8||Blood (bone marrow)|
|11||Central Nervous System (including brain)|
- The reproductive system is affected such that viable offspring cannot be created. May be temporary or permanent.
|Dose in rems||Duration of Sterility|
|150||1 - 6 weeks|
|250||1 - 2 years|
|500-600||Permanent in 75%|
|800||Permanent in 100%|
Rolling back radiation damage
Cloned or regenerated parts, or reanimation will reduce total exposure. For simplicity, replacement parts reduce exposure by 10% per part.
Reanimation returns total exposure to the level before the lethal dose. Cataract and malignancy checks are one level of difficulty easier.