Sievertach

Sievertach is a fictional unit of radiation exposure used in science fiction and speculative world-building to quantify the total accumulated radiation dose an individual receives over an extended period, such as a space mission or long-term habitat stay. It is presented as a derivative concept of the sievert, the real-world unit of ionizing radiation dose with biological effect weighting, but with an explicit emphasis on the accumulation of dose over time within a defined interval.

In fictional settings, a sievertach corresponds to the integrated dose received during a specified mission window, allowing writers and game designers to discuss risk management without relying on instantaneous dose figures. Because it is not an official unit, numerical values, conversion rules, and safety thresholds vary between works, and the term carries no standard definition outside its narratives.

Etymology-wise, sievertach combines sievert with a fictional suffix -ach, intended to hint at measurement over duration. It is sometimes explained as a contextual shorthand for “dose accumulated over time,” though implementations differ.

Measurement and use: In stories and games, dosimeters or wearable sensors may report dose rates in sieverts per hour, with the total sievertach calculated by applying the mission timeframe. The unit often features in discussions of shielding, mission planning, and crew safety to illustrate cumulative risk.

Status: The sievertach has no standing in real-world radiation protection or SI units. It remains a storytelling or game-world construct rather than a recognized measure of exposure.

See also: Sievert, Dose, Radiation dose, Shielding, Space radiation.