Glossary cont'd - DOE-HDBK-1109-97

DOE-HDBK-1109-97

Radiological Safety Training for Radiation-Producing (X-Ray) Devices

Student's Guide

GLOSSARY (continued)

Skyshine: Radiation emerging from a shielded enclosure which then scatters off air molecules to increase

radiation levels at some distance from the outside of the shield.

Stem radiation: X-rays given off from parts of the anode other than the target, particularly from the

target support.

Stray radiation: Radiation other than the useful beam. It includes leakage and scattered radiation.

Survey: An evaluation of the radiological conditions and potential hazards incident to the production, use,

transfer, release, disposal, or presence of radioactive material or other sources of radiation. When

appropriate, such an evaluation includes a physical survey of the location of radioactive material and

measurements or calculations of levels of radiation, or concentrations or quantities of radioactive material

present. (10 CFR 835.2(a)).

System barrier: The portion of an X-ray installation that clearly defines the transition from a Controlled

Area to a Radiation Area and provides such shielding as may be required to limit the dose rate in the

Controlled Area during normal operation.

Tenth-value layer (TVL): The thickness of a specified substance that, when introduced into a beam of

radiation, reduces the dose rate to one-tenth of the original value. One TVL is equivalent to 3.3 HVLs.

Unattended installation: An industrial installation that consists of equipment designed and manufactured

for a specific purpose and that does not require personnel in attendance for its operation.

Units: In accordance with 10 CFR 835.4, for all radiological units, the quantities used for records required

by 10 CFR 835 shall be the curie (Ci), rad or rem. SI units, Becquerel (Bq), gray (Gy), and sievert (Sv)

may be included parenthetically for reference to scientific standards, but are not authorized for required

records. To convert conventional radiation units to SI units, the following factors are used:

1 rad = 0.01 gray (Gy)

1 rem = 0.01 sievert (Sv)

1 Ci = 3.7 X 1010 Bq