some of the radar hazards you may encounter inside the
CATHODE-RAY TUBES (CRTs)
Cathode-ray tubes can be very dangerous and
should always be handled with extreme caution. The
glass envelope encloses a high vacuum, and because of
its large surface area, is subject to considerable force
by atmospheric pressure. (The total force on the
surface of a 10-inch CRT is 3,750 pounds or nearly 2
tons; over 1,000 pounds is exerted on its face alone.)
Proper handling and disposal instructions for a CRT
are as follows:
Avoid scratching or striking the surface.
Do not use excessive force when you remove or
replace the CRT in its deflection yoke or its
Do not try to remove an electromagnetic CRT
from its yoke until you have discharged the high
voltage from the anode connector (hole).
Never hold a CRT by its neck.
When you set a CRT down, always place its face
down on a thick piece of felt, rubber, or smooth
Always handle the CRT gently. Rough handling
or a sharp blow on the service bench can displace
the electrodes within the tube, causing faulty
Wear safety glasses and gloves whenever you
handle a CRT.
RADIOACTIVE ELECTRON TUBES
Electron tubes containing radioactive material are
common to radar equipment. These tubes are known as
Transmit-Receive (TR), antitransmit-receive (ATR),
spark-gap, voltage-regulator, gas-switching, and
cold-cathode gas-rectifier tubes. Some of these tubes
contain radioactive material that has a dangerous
intensity level. Such tubes are so marked according to
military specifications. In addition, all equipment
containing radioactive tubes must have a standard
warning label attached where maintenance personnel
can see it as they enter the equipment.
As long as these electron tubes remain intact and
are not broken, no great hazard exists. However, if they
are broken, the radioactive material may become a
The radioactivity in a normal collection of electron
tubes in a maintenance shop does not approach a
dangerous level, and the hazards of injury from
exposure are slight. However, at major supply points,
the storage of large quantities of radioactive electron
tubes in a relatively small area may create a hazard. If
you work in an area where a large quantity of
radioactive tubes is stored, you should become
thoroughly familiar with the safety practices contained
in Radiation Health Protection Manual, NAVMED
P-5055. By complying strictly with the prescribed
safety precautions and procedures of this manual, you
should be able to avoid accidents and maintain a work
environment that is conducive to good health.
The hazardous materials information system
(HMIS) contains a listing of radioactive tubes, along
with proper stowage techniques and disposal
procedures. Afloat Supply Procedures, NAVSUP
P-485 contains detailed custody procedures. Be sure
you use proper procedures whenever you dispose of a
radioactive tube. Also, be aware that federal and state
disposal regulations may vary.
Any time you handle radioactive electron tubes,
take the following precautions:
1. Do not remove a radioactive tube from its carton
until just before you actually install it.
2. When you remove a tube containing a
radioactive material from equipment, place it in
an appropriate carton to keep it from breaking.
3. Never carry a radioactive tube in your pocket, or
elsewhere on your person, in such a way that
could cause the tube to break.
4. If you do break a radioactive tube, notify the
appropriate authority and obtain the services of
qualified radiological personnel immediately.
The basic procedures for cleaning the area are
covered in the EIMB, General, Section 3. If you
are authorized to clean the area, get a radioactive
spill kit with all the materials to clean the area
quickly and properly. The ship must have at least
one radioactive spill disposal kit for its
electronic spaces. It may have more, depending
on the number and location of spaces in which
radioactive tubes are used or stored. Each kit
should contain the following items:
ContainerMust be large enough to hold all
cleanup materials and pieces of broken