T.O. 33B-1-1
could result in an individual receiving a dose in excess of 5 mrem (50 mSv) one hour at 30 centimeters
(one foot) from the radiation source or from any source that the radiation penetrates.)
c.
Compliance with radiation dose limits applicable to the general public and to occasionally exposed
individuals requires that access to areas in which radiation doses could exceed 2 mrem (20 mSv) in any
one hour or 100 mrem (1 mSv) in a year must be restricted. ‘‘Radiation Area’’ postings shall be
extended out from the X-ray tube such as to encompass such areas, or alternative arrangements made
to restrict access to this area.
d.
If the beam orientation or technique factors change between exposures, the radiation and high
radiation area boundaries must be reestablished and the boundaries of radiation areas re-verified.
e.
Rotating/f lashing strobe-type (blinking, low intensity, warning lights shall not be used) red warning
lights should be used on the perimeter. A rotating/f lashing strobe-type (blinking, low intensity,
warning lights shall not be used) red warning light shall be positioned at the source and shall be
rotating/f lashing only when the source is energized.
f.
An X-ray interlock (NSN 6635-00-292-7637 or equivalent) or gamma shutter, as applicable, shall be
installed between the control unit and the rotating/f lashing strobe-type X-ray (or gamma) ‘‘on’’ light.
The interlock assembly enables electrical power to the ‘‘X-ray on’’ power circuits only after the
rotating/f lashing strobe type ‘‘X-ray on’’ warning light is attached. X-ray/gamma radiography
interlocks shall be inspected by radiographers each day that the X-ray equipment is used to verify
their proper operation. They shall be tested every six months by verifying that they do indeed de-
energize the X-ray tube head when tripped.
g.
If the perimeter is of such a size or is so arranged that the operator cannot readily determine whether
the radiation area is unoccupied, a sufficient number of radiographers and/or radiation safety
monitors shall be strategically located to provide adequate visual surveillance over the entire area.
These personnel shall have in their possession an adequate and properly calibrated, operable survey
meter. This requirement for additional monitors may not be necessary if the radiographic procedures
are to be accomplished in a fenced-in or locked area to which access is controlled by the radiographer
and not less than one radiation safety monitor. (X-ray and gamma-ray controls should be placed so
that all monitors of the entire perimeter of the barrier can be seen and heard by the radiographer. If
this is not possible, a hand held battery powered communication device of intrinsically safe design
shall be utilized.)
h.
The radiation source and equipment essential to the use of the source shall be inaccessible to
unauthorized use, tampering or removal when not in use. This shall be accomplished by such means
as a locked enclosure.
i.
At least two qualified radiographers and as many radiation safety monitor assistants shall be used. If
two qualified radiographers are not available, at least one qualified radiographer and as many
radiation safety monitor assistants (see page 6-119, paragraph 6.9.6) as required to prevent radiation
barrier penetration. Training for radiation safety monitor assistants shall be conducted IAW page
6-119, paragraph 6.9.6.1. This applies to standard industrial X-ray systems only. No radioactive
material (RAM) used as the source.
j.
If the unshielded installation is in remote area and if entry into the enclosed area can be absolutely
prevented during irradiation, the source and all objects exposed thereto may be within a conspicu-
ously posted perimeter that limits the area in which the exposure can exceed 100 mR (1 mSv) in an
hour provided:
(1)
The perimeter is posted with a sufficient number of ‘‘Caution, (or Danger) High Radiation Area’’
signs so as to be conspicuous from any direction of approach.
(2)
The boundary of the restricted area can be determined where applicable.
(3)
The requirements of paragraph 6.9.18.3.2 can be met.
k.
No person, either within a controlled area or in the environs of the installations, is exposed to more
than appropriate basic radiation protection standards prescribed 6.9.10 of this TO.
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