Rad (metric)

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Flare Star With Prominences.jpg

A rad is a unit of measurement of radiation.

Description (Specifications)[edit]

A Rad is a unit of absorbed dose of ionizing radiation equal to an energy of 0.1 newtons per gram of irradiated material.

  • One rad is equal to 10 millisieverts
  • The common Imperial usage is simply rad: the name is short enough to make an abbreviation unnecessary.

Larger units may be denoted by the prefixes k (for kilo) or m (for mega):

  • A krad is equal to 1,000 rads
  • An mrad is equal to 1,000,000 rads

The rad is related to the millisievert, a unit measuring the radiation dose defined as that producing the same biologic effect in a specified tissue as 1 gray of high-energy x-rays received either from a radioactive source or from other sources such as medical procedures.

  • A millisievert is generally a whole body effective dose, but it may also be an equivalent dose received by a particular tissue or organ.
  • The common Imperial abbreviation is mSv.

A Radiation Counter is able to measure the local ambient radiation levels.

Harmful radiation is most commonly caused by x-rays, beta particles and gamma rays.

Generalized Rad Level Table[edit]

Rad Levels
Exposure Effect Typical Source
0.001 rads / hour No negative long term effects. Dental x-ray
0.01 rads / hour No negative long term effects. Chest x-ray
10 rads / hour Radiation sickness, nausea, eventual recovery likely. Airborne fallout as a result of a detonated thunderball device.
25 rads / hour Lowest dose to cause clinically observable blood changes. Can be caused by stellar flares on planets with less protective atmospheres.
200 rads / hour Local dose for onset of erythema (reddened skin) in humans.
400 rads / hour Acute radiation syndrome in humans. Levels experienced around Flare Stars
1 krad / hour Organ failure, death within hours.
Typical radiation tolerance of ordinary microchips.
Levels seen within the crater of a detonated thunderball device.
6 krads / hour Rapid cellular necrosis. Typical radiotherapy dose, locally applied.
10 krads / hour Rapid fatal whole-body dose, death within an hour. Highest levels encountered around a Flare Star.
400 krads / hour Rapid organ failure, death within minutes. Within the magnetospheres of large gas giants and stars.
1 mrad / hour Typical tolerance of radiation-hardened microchips.

Term Usage Example[edit]

A Fission power plant may produce hundreds of rads per hour.

History & Background (Dossier)[edit]

Effects on health are observed only beyond 10 rads (100 mSv), though long term exposure to substantially lower levels of radiation still presents a severe risk to health. It takes a dose of hundreds of rads to cause injuries that can be fatal in the short term.

The rad was first defined as a unit of measurement on Terra prior to the foundation of the Terran Confederation. Technologists found the rad useful as the concept of the Technology Level and standardized ideas about sophont society development began to take form.[1]

Image Repository[edit]

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References & Contributors (Sources)[edit]

This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Far Future Enterprises or by permission of the author. The page history lists all of the contributions.
  1. An unpublished factoid written by Maksim-Smelchak