Recommended Instruments for Use in RF Fields.
Victoreen Model 440RF-D Survey Meter.
The Model 440 RF/D Survey Meter is specially designed to be used in strong radiofrequency radiation fields
up to 20 mW/cm2. It detects gamma and X-ray radiation above 12 keV. The Model 440 RF/D has 5 operating
ranges, measuring from 0-1 mR/hr (0-50 mSv/hr) to 0-100 mR/hr (0-5000 mSv/hr). The detector is a cylindrical
3.56-cm diameter, 10-cm2 cross-section air ionization chamber that has a 1.5 mg/cm2 mylar window and a 13-
mg/cm2 magnesium window. It operates continuously for about 200 hours on a set of five new 9-volt
batteries. The model 440 RF/D includes an internal check source to verify correct system operation. The
instrument does have a significant variation in energy response, requiring the instrument reading to be
corrected dependent on the kVp of the x-ray system being surveyed.
Calibration and Use of Radiation Survey Instruments.
Radiation survey meters used for X-radiography shall be calibrated as follows:
Air Force radiation survey meters shall be calibrated in accordance with T.O. 33K-1-100-2.
Army radiation survey meters shall be calibrated in accordance with T.B. 43-180.
Navy radiation survey meters shall be calibrated not to exceed six months.
Radiation survey meters used for source radiography shall be calibrated at intervals not to exceed three
months. In addition, all meters shall be calibrated after each instrument servicing. A record shall be
maintained of the results of each instrument for three years after the date of calibration (10 CFR 34.24).
The calibration of all radiation survey instruments shall be checked by the user with a radiation check source
prior to the first monitoring operation of the day and at two-week intervals for instruments not in daily use
as per its operational manual.
Army. Consult AR 750-43 (Army Test Measurement and Diagnostic Equipment Program), TB 750-25
(TMDE Calibration and Repair Support Program) and TB 43-180 (Calibration and Repair Require-
ments for the Maintenance of Army Materiel) for detailed information on the calibration and repair
programs. X-ray survey instrumentation can only be calibrated by the US Army TMDE Activity,
ATTN: AMXTM-SR, Redstone Arsenal, AL 35898-5400, DSN: 746-7666. (To preclude unnecessary
delays, instruments should be shipped direct without regard to local TMDE activities.)
Air Force: Reference T.O.s 11H4-7-15-1 and 33K-1-100 for record keeping information.
Guidelines for Use.
Whenever radiographic operations are performed, at least one calibrated and operable radiation survey
instrument shall be available at shielded installations and at least two operable radiation survey instru-
ments shall be available at unshielded installations. The instrument(s) SHALL be turned ON and available
for immediate use by the radiographer during all radiographic operations. The instrument(s) used SHALL
have an adequate instrument response for the range of radiation energies encountered.
Survey meters are delicate instruments. It is essential that reasonable care be taken in their use to assure
reliability. Most survey instruments are not waterproof. If it should rain when you are working outdoors a
clear plastic bag will have no appreciable effect on the radiation and it will not hamper the operating of the
control switches. If the components of the survey meter become wet, the instrument may have to be serviced
and recalibrated. When survey meters are transported in vehicles they should be placed in the drivers
compartment with adequate support and restraint to prevent damage during transit.