SCO
Surface Contaminated Object (SCO) means a solid object that is not itself classed as radioactive material, but which has radioactive material distributed on any of its surfaces. SCO must be in one of two groups with surface activity not exceeding the following limits:
(1) SCO-I: A solid object on which:
(i) The nonfixed contamination on the accessible surface averaged over 300 cm
2 (or the area of the surface if less than 300 cm
2) does not exceed 4 Bq/cm
2 (10−4 microcurie/cm
2) for beta and gamma and low toxicity alpha emitters, or 0.4 Bq/cm
2 (10−5 microcurie/cm
2) for all other alpha emitters;
(ii) The fixed contamination on the accessible surface averaged over 300 cm
2 (or the area of the surface if less than 300 cm
2) does not exceed 4 × 10
4 Bq/cm
2 (1.0 microcurie/cm
2) for beta and gamma and low toxicity alpha emitters, or 4 × 10
3 Bq/cm
2 (0.1 microcurie/cm
2) for all other alpha emitters; and
(iii) The nonfixed contamination plus the fixed contamination on the inaccessible surface averaged over 300 cm
2 (or the area of the surface if less than 300 cm
2) does not exceed 4 × 10
4 Bq/cm
2 (1 microcurie/cm
2) for beta and gamma and low toxicity alpha emitters, or 4 × 10
3 Bq/cm
2 (0.1 microcurie/cm
2) for all other alpha emitters.
(2) SCO-II: A solid object on which the limits for SCO-I are exceeded and on which:
(i) The nonfixed contamination on the accessible surface averaged over 300 cm
2 (or the area of the surface if less than 300 cm
2) does not exceed 400 Bq/cm
2 (10−2 microcurie/cm
2) for beta and gamma and low toxicity alpha emitters or 40 Bq/cm
2 (10−3 microcurie/cm
2) for all other alpha emitters;
(ii) The fixed contamination on the accessible surface averaged over 300 cm
2 (or the area of the surface if less than 300 cm
2) does not exceed 8 × 10
5 Bq/cm
2 (20 microcuries/cm
2) for beta and gamma and low toxicity alpha emitters, or 8 × 10
4 Bq/cm
2 (2 microcuries/cm
2) for all other alpha emitters; and
(iii) The nonfixed contamination plus the fixed contamination on the inaccessible surface averaged over 300 cm
2 (or the area of the surface if less than 300 cm
2) does not exceed 8 × 10
5 Bq/cm
2 (20 microcuries/cm
2) for beta and gamma and low toxicity alpha emitters, or 8 × 10
4 Bq/cm
2 (2 microcuries/cm
2) for all other alpha emitters.
Source
10 CFR § 71.4
Scoping language
The following terms are as defined here for the purpose of this part. To ensure compatibility with international transportation standards, all limits in this part are given in terms of dual units: The International System of Units (SI) followed or preceded by U.S. standard or customary units. The U.S. customary units are not exact equivalents but are rounded to a convenient value, providing a functionally equivalent unit. For the purpose of this part, either unit may be used.