Thorium oxide-- The radioactive decay of
thorium (thorium daughter products) and
thorium oxide are considered carcinogenic
agents.
Barium acetate-- A small residual remains after
manufacture, TLV 0.5 mg/m3.
Barium getters-- Composition unknown, 10-12
Figure 1-17.--Cathode-ray tube base structure.
grams.
RADIOACTIVE ELECTRON TUBES
Several manufacturers will dispose of returned
tubes. Instructions for the return of tubes are available
Electron tubes containing radioactive material are
from the manufacturer. If unable to return the CRT to
now commonly used. Some tubes containing
radioactive material contain dangerous intensity levels.
the manufacturer for disposal, make it harmless by
These tubes are marked according to military
breaking the vacuum glass seal. The safest method of
specifications. Most tubes contain radioactive cobalt
making a CRT harmless is to place the tube in an empty
(Co-60), radium (Ra-226), or carbon (C-14); several
carton, with its face down. Then, carefully break off the
contain nickel (Ni-63). Some tubes contain cesium
locating pin from its base (fig. 1-17). Complete disposal
barium (CsBa-137).
instructions may be found in Navy Electricity and
No hazard exists when an electron tube containing
Electronics Training Series (NEETS), NAVEDTRA
radioactive material remains intact. However, a
potential hazard exists when the electron tube is broken
172-06-00-82, Module 6.
Figure 1-18.--CAUTION tag (colored YELLOW).
1-28