T.O. 33B-1-1
6-144
f. A qualified radiographer shall be present at the control panel during all radiographic exposures and will
be the only person authorized to operate radiographic equipment. An operational, calibrated, survey
instrument shall be available for immediate use by the radiographer during all radiographic operations.
g. Except when making daily verification of safety interlock operation and in emergencies, door interlocks
will not be used to terminate the exposure. The exposure shall be terminated at the control panel.
h. When radiographic exposures have been competed, the safety-switch key shall be removed from the
control panel. The radiation-producing equipment and power safety-switch key shall be placed in
secure areas separate from one another. Only radiographers specifically authorized by the Commander
shall have access to the storage areas.
6.9.18.2
Enclosed Installations (Air Force: N/A).
6.9.18.2.1
Features
a. This class usually offers the greatest advantage for fixed installations with low use and low occupancy
factors. This is particularly true for high-energy sources where the reduction in shielding may result in
significant savings.
b. The shielding requirements are considerably lower than for the protective installations, as much as 4.3
half-value layers (HVL) less; yet, the inherent protection is such that the possibility of significant
overexposure is remote.
c. With proper supervision, this class of installation offers a degree of protection similar to the protective
installation.
6.9.18.2.2
Requirements.
An installation shall be classified as "enclosed" when it conforms to all of the following mandatory requirements:
a.
The source of radiation and all objects exposed thereto are within a permanent enclosure, within which
no person is permitted to remain during irradiation.
b.
Each entrance that is used for personnel access to the enclosure/high-radiation area shall have both
visible and audible warning signals to warn of the presence of radiation. The visible signal shall be
actuated by radiation whenever the source is exposed/in operation. The audible signal shall be actuated
when an attempt is made to enter" the enclosure while radiation is being produced (10 CFR 34.29(b)).
In addition, reliable dual independent interlocks are desirable on each door to prevent access to the
enclosure during irradiation. A single interlock system on each door to prevent access to the enclosure
during irradiation is a mandatory requirement.
c.
Each of the following shall be provided (except where specifically noted) without regard to the size
and/or configuration of the enclosure.
NOTE
A time delay interlock may be locally fabricated in order to meet this requirement.
The suggested design is optional and not mandatory since numerous design
approaches can be used. Note that the wiring harnesses are similar to the harnesses
used with X-ray Interlock Assembly, NSN 6635-00-292-7637. All time delay
interlock systems installed shall be compatible with all X-ray units commonly
available.
