United States Nuclear Regulatory Commission - Protecting People and the Environment
Home > NRC Library > Document Collections > NRC Regulations (10 CFR) > Part Index > § 140.84 Criterion I--Substantial discharge of radioactive material or substantial radiation levels offsite.

§ 140.84 Criterion I--Substantial discharge of radioactive material or substantial radiation levels offsite.

The Commission will determine that there has been a substantial discharge or dispersal of radioactive material offsite, or that there have been substantial levels of radiation offsite, when, as a result of an event comprised of one or more related happenings, radioactive material is released from its intended place of confinement or radiation levels occur offsite and either of the following findings are also made:

(a) The Commission finds that one or more persons offsite were, could have been, or might be exposed to radiation or to radioactive material, resulting in a dose or in a projected dose in excess of one of the levels in the following table:

Total Projected Radiation Doses

Critical Organ Dose (rems)
Thyroid 30
Whole body 20
Bone marrow 20
Skin 60
Other organs or tissues 30

Exposures from the following types of sources of radiation shall be included:

(1) Radiation from sources external to the body;

(2) Radioactive material that may be taken into the body from its occurrence in air or water; and

(3) Radioactive material that may be taken into the body from its occurrence in food or on terrestrial surfaces.

(b) The Commission finds that:

(1) Surface contamination of at least a total of any 100 square meters of offsite property has occurred as the result of a release of radioactive material from a production or utilization facility and such contamination is characterized by levels of radiation in excess of one of the values listed in Column 1 or Column 2 of the following table, or

(2) Surface contamination of any offsite property has occurred as the result of a release of radioactive material in the course of transportation and such contamination is characterized by levels of radiation in excess of one of the values listed in column 2 of the following table:

Total Surface Contamination Levels1

Type of emitter Column 1 Offsite property, contiguous to site, owned or leased by person with whom an indemnity agreement is executed Column 2 Other offsite property
Alpha emission from transuranic isotopes. 3.5 microcuries per square meter. 0.35 microcuries per square meter.
Alpha emission from isotopes other than transuranic isotopes. 35 microcuries per square meter. 3.5 microcuries per square meter.
Beta or gamma emission. 40 millirads/hour @ 1 cm.2 4 millirads/hour @ 1 cm.2

1 The maximum levels (above background), observed or projected, 8 or more hours after initial deposition.

2 Measured through not more than 7 milligrams per square centimeter of total absorber.

[33 FR 15999, Oct. 31, 1968, as amended at 40 FR 8794, Mar. 3, 1975]

Page Last Reviewed/Updated Thursday, July 25, 2013