Radiological Safety Training for Uranium Facilities
Module 104 Internal Dose Control
Indirect measurements are made by sampling material eliminated by the body
for the presence of uranium. It is possible to analyze both feces and urine for the
presence of uranium, but due to the ease of collection and handling, the most
common method used is urinalysis.
2. Direct or In Vivo Measurement
Direct measurements are performed using whole body counters or lung
counters. These instruments detect gamma and X-rays emitted from radioactive
material inside the body. For example, the 235U and uranium-234 (234U)
isotopes of uranium present in enriched uranium emit X-rays that can be
detected. Alpha and beta radiation emitted by material inside the body is
shielded by body tissue and cannot be detected.
Direct measurement is useful for detecting uranium that is not easily eliminated
by the body. This method may also be used to estimate an internal dose.
Because of the very low energy and intensity of gamma radiation emitted from
depleted uranium, direct measurements are not effective in detecting depleted
uranium in the body.
Internal Dose Reduction and Control Techniques
The hierarchy for minimization of internal dose is given in the RCS, Article 316.
Engineering controls should be the primary method of minimizing airborne
contamination and internal exposure to workers, where practicable. Administrative
controls, including access controls and specific work practices, should be used as
the secondary method to minimize internal exposure. If the potential for airborne
radioactivity still exists after engineering and administrative controls have been
applied, respiratory protection should be considered. Other specific controls, such