Direct or In Vivo Measurement - doe-hdbk-1113-98_reaffirm_2005

DOE-HDBK-1113-98

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