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April 26, 1986

Untitled notice about the categories of the population and body parts most susceptible to radiation

This document was made possible with support from Carnegie Corporation of New York (CCNY)



1 roentgen equals 103 milliroentgens, and 106 microrentgens


At a level of radioactivity of 20-25 microroentgens per second, the dose of radiation is 0.072-0.093 roentgens per hour for the territory of the station. For the city of Pripyat, the level of radioactivity is 4-14 microroentgens of 0.0144 roentgens an hour and 0.05 roentgens an hour.


Standards of radioactive safety highlight two [of the following three] categories of individuals:


-Category A – personnel

-Category B – limited part of the population

-Category C – population of the Oblast and of the Republic


Three groups of critical organs are established in decreasing order of radioactive sensitivity:


- Group I - the whole body, gonads, and red bone marrow

- Group II - muscles, thyroid glands, fatty tissue, liver, kidney, gastrointestinal tract, and lungs

- Group III - the epidermis, bone tissue, hands, forearms, and ankles


The maximum allowable doses of external and internal radiation is:


Category of Individual

Organ Group





Category A

per year



30 bars

Category B

per year



3 bars


During the completion of activities to eliminate the consequences of the accident, external radiation two times higher than the annually permitted doses is permitted in every concrete case, or five times higher for the extent of the entire period of work. Personnel are warned that work is permitted only with written permission from the administration and personal agreement by the worker.


It is forbidden to permit individuals to work who have earlier been exposed to radiation exceeding the annual dose by five times, or women aged less than 40.


For Category B, the equivalent radiation dose should not exceed the annual standard.


Permissible levels are established with standards for each of the radionuclides.


At a level of radioactivity of 0.072 roentgens per hour, the dose sustained in a year consists of around 680 roentgens.


The indicated information is laid out in the RSS-76 [i.e. radiation safety standard] radiation safety standard.


Note: 1 bar / biological equivalent of roentgen / for gamma and beta radiation equal to 1 roentgen, for alpha radiation a scale ratio is used.


Subdivision Director






This document discusses how radioactivity is measured, radiation safety norms and categories, and the permissible dose of radiation for different groups (i.e., accident responders, plant personnel, the regional population)


Document Information


HDA SBU, f. 11, spr. 992, t. 29. Originally published by the Center for Research into the Liberation Movement (TsDVR) together with the Ivan Franko National University of Lviv at


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Carnegie Corporation of New York (CCNY)