The unit, symbol Sv, of equivalent and effective dose: joules per kilogram after weighting for radiation type and tissue sensitivity. One sievert equals 100 rem. Everyday protection work uses millisieverts and microsieverts: average natural background is roughly 2 to 3 mSv a year, a chest X-ray a small fraction of 1 mSv, and the common occupational limit 20 mSv a year averaged over five years.
Collective for the outage came in at 0.42 person-sievert, best we've done on a steam generator outage.
Natural background differs several-fold between regions, a useful sense check when explaining an occupational dose to family.
Also heard as
- Sv
Related terms
Gray
The SI unit of absorbed dose, equal to one joule of energy deposited per kilogram.
Rem
The US customary unit of dose equivalent, equal to one hundredth of a sievert.
Effective dose
A whole-body dose figure that adds up organ doses weighted by each tissue's sensitivity to radiation risk.
Equivalent dose
Absorbed dose to an organ multiplied by a weighting factor for the type of radiation, measured in sieverts.
Dose limit
The maximum dose a worker or member of the public may legally receive from regulated sources in a set period.