Beta/Gamma Direct Monitoring - hdbk110697

DOE-HDBK-1106-97

Radiological Contamination Control Training

for Laboratory Research

Student's Guide

Beta/Gamma Direct Monitoring

1. Window: Use a thin-window probe, detector window thickness (mylar) should not be

more than 2.0 mg/cm2.

2. Scanning: Scan the surface; in most cases, scanning will cover nearly 100 percent of

accessible surfaces.

3. Distance: Maintain detector window no more than 1/2 inch from surface.

4. Speed: The number of counts produced in the detector is inversely proportional to the

scanning speed. ANSI 13.12 (1987) describes a formula for calculating scan speed.

5. Audio: If at any point a perceivable audible or visual response is detected, perform a

stationary evaluation of count rate.

Smear Surveys for Releasing Material

1. An initial screening evaluation (not for final release) may be conducted by wiping

100 percent of surface.

2. These large-area wipes may be evaluated by holding the probe up to the swipe (~5 sec.)

3. If initial screening evaluation indicates presence of contamination, take representative

disc smears (100 cm2 area) of up to 100 percent of accessible surface areas.

Documentation

All surveys for release shall be documented in writing. Documentation of release from

controlled areas should include information required by RCM Article 421.5.

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