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Radiation Safety Training Module
Refresher Training
ISU Technical Safety Office
Campus Box 8106
Pocatello, ID 83209
(208) 282-2311
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Dose Limits

Federal and State Authorities establish legal dose limits that an employee should not exceed in a calendar year.  Administratively, ISU establishes more conservative values than allowed by Federal and State authorities and the ALARA goals (explained in the next section) are set and self imposed by the ISU Radiation Safety Committee in order to minimize personnel exposure.

The Idaho State University's Administrative Occupational Dose Limits (legal limits set by ISU) are as follows:

The annual adult occupational dose limit is the more limited of:

  • The total effective dose equivalent being equal to 2,000 mrem (2 rem); or
  • The sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue, being equal to 10,000 mrem (10 rem). 
ISU's administrative occupational dose limits are far less than the occupational dose limits set by the NRC or the State of Idaho.

Idaho State University's ALARA Goals
The ALARA goals are included here as a comparison to the legal limits.  The ALARA concept is explained in the next section. 

All Radiation Safety Programs:
  • 1000 mrem/calendar year
  • 300 mrem/calendar quarter (notification level)
NRC Occupational Annual Dose Limits (applies to radioactive materials users)
The annual adult (persons 18 years of age or older) occupational dose limit established by the United States Nuclear Regulatory Commission is the more limiting of:
  • The total effective dose equivalent being equal to 5,000 mrem (5 rem); or 
  • The sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue other than the lens of the eye being equal to 50,000 mrem (50 rem).
  • An eye dose equivalent of 15,000 mrem (15 rem), and
  • A shallow dose equivalent of 50,000 mrem (50 rem) to the skin or to each of the extremities.

Idaho Quarterly Occupational Dose Limits  (applies to X-ray and accelerator users only)

  • Whole body; head and trunk; active blood-forming organs; lens of eye or gonads 1,250 mrem/cal qtr
  • Hands and forearms; feet and ankles 18,750 mrem/cal qtr
  • Skin of whole body 7,500 mrem/cal qtr
General Public Dose Limits
The dose limit for members of the general public, including all persons who are not classified as radiation users, is a total effective dose equivalent not to exceed 100 mrem per year.  In addition, the dose in any unrestricted area from external sources cannot exceed 2 mrem in any one hour. 

Fetal Dose
The embryo-fetus may be more susceptible to radiation effects than an adult and is, therefore, subject to a lower dose limit.  The dose limit for the embryo-fetus is 500 mrem (5 mSv) during the entire gestation period.  As a further precaution, this limit should not be experienced in an acute fashion, but rather distributed relatively uniformly during the gestation period if it is to be experienced (Regulatory Guide 8.13). This degree of protection for the embryo-fetus can only be achieved with the cooperation of the employee. It is recommended that she notifies her supervisor or the RSO as soon as the pregnancy is known. In order for a pregnant worker to take advantage of the lower exposure limit and dose monitoring provisions, the woman may declare her pregnancy in writing to the TSO. A form letter can be obtained from TSO or by clicking here. This notification is optional, and at the discretion of the employee the TSO encourages the act of notification, when appropriate. Unless a woman declares her pregnancy, ISU can not set special dose equivalent limits for her.

Dose Limits for Minors
The dose limits for minors (persons under 18 years of age) are 10% of the adult occupational dose limits.

  Key Words: NRC occupational annual limits, Idaho quarterly occupational dose limits, general public dose limits; fetal dose limits, Idaho quarterly occupational dose limits, dose limits for minors
Page: 4 of: 12
  Quiz:  May a pregnant worker declare her pregnancy to the University?
a)  Yes, if she wants the lower exposure limits and
additional dose monitoring.
b) No. c)  Yes, in all cases. d) I don't know.
  10 CFR 20.1201 Occupational Dose Limits for Adults
10 CFR 20.1207 Occupational Dose Limits for Minors
10 CFR 20.1208 Dose to Embryo/Fetus
Health Physics Society Ask the Experts - FAQ Measuring Occupational Exposures
Health Physics Society Ask the Experts - Doses and Dose Calculations
Health Physics Society Ask the Experts - Personnel Monitoring

This web based training was developed for use within Idaho State University.  It is intended for use by, and applies to ISU employees, staff, visitors, and students.  If this web site or any part of it is used elsewhere, neither its authors nor the University accept responsibility for its contents.  This information may NOT be used for commercial development or profit.