Section III - Discussion
III. DISCUSSION
10 CFR 835.401(c)(2&3) and 403(b) require, in part, that "appropriate"
instruments be used to control exposure to radiation. They also require
that these instruments be routinely calibrated, maintained, and tested
(10 CFR 835.401(c)(1&4)). American National Standards Institute (ANSI)
Standard N323, "Radiation Protection Instrumentation Test and
Calibrations" (ANSI, 1983) is referenced in DOE Order 5480.11 and is
cited as a mandatory environment, safety, and health standard in DOE
Order 5480.4, "Environmental Protection, Safety, and Health Protection
Standards" (DOE, 1984). The measurement ranges of the instruments can be
inferred from the control levels in 10 CFR 835 and the expected
workplace conditions; however, 10 CFR 835 does not address the accuracy
of calibrations or measurements. ANSI N323 requires an accuracy of +-2%
for sources used in calibrations and an accuracy of +-10% for the
calibrated instruments.
Radiation monitoring instrumentation is one of the principal tools for
protecting workers and the public from excess exposure to ionizing
radiation. Instruments are used to establish controls for worker or
public access to the radiation environment, while a personnel dosimeter
provides a legal record of a worker's dose. Except for certain
electronic dosimeters, conventional dosimeters provide only a
retrospective record of dose; they provide the integrated dose over a
period of time prior to readout. Survey instruments are important for
indicating exposure dose rates, controlling radiation exposures, and for
verifying the dose received by workers. Neither an emergency response
program, nor the ALARA program required by 10 CFR 835.101(c), can be
operated effectively without the appropriate quantity of properly
functioning instruments that are appropriate for measuring the
radiation(s) of interest and for operation in the facility's physical
environment. In addition to measuring dose or dose rate to control
direct personnel exposure, instruments are used: (1) to control the
spread of contamination (e.g., surface-contamination monitors); and (2)
to assess the adequacy of radiological controls (e.g., survey meters or
environmental monitors). Contamination monitoring is important in the
control of contact exposures, personnel contamination, and internal
exposures through inhalation or ingestion.
DOE facilities are expected to maintain the quality of measurements in
their daily operations by establishing procedures required to ensure the
proper operation and calibration of the equipment. Thus, instruments
"shall" be selected for the task, properly calibrated, properly
maintained, and routinely tested (10 CFR 835.401(c)).
A. Instrument Selection
Instruments "shall" be selected to measure the types and energies of
radiation and the range of radiation dose rates or surface contamination
activities present within the facility (10 CFR 835.401(c)(2)). The
instruments "shall" also be selected to perform adequately under the
environmental and physical conditions that prevail within the facility
(10 CFR 835.401(c)(3) and RCM 562.4). Initial instrument selection "shall"
be made using knowledge of facility radiation types, energies,
anticipated or known ranges, and results of available instrument
performance and testing data (vendor or independent) (10 CFR
835.401(c)(2)). The selection process includes Type Testing and
Acceptance Testing.
Type Testing
Implementation of a formal instrument qualification (type testing)
process in accordance with the relevant portions of ANSI N42.17A,
"Performance Specifications for Health Physics Instrumentation -
Portable Instruments for Use In Normal Environmental Conditions"
(ANSI, 1989a), and ANSI N42.17C, "Performance Specifications for
Health Physics Instrumentation - Portable Instruments for Use In
Extreme Environmental Conditions" (ANSI, 1989b), is encouraged. It
is recognized, however, that independent contractor qualification
efforts to meet these requirements may result in significant
duplication of effort and resources. To assist the development of
this process and to avoid such duplication, the Office of Health is
developing a program for the coordinated qualification and testing
of radiological instruments used within the DOE complex (RCM 561).
Acceptance Testing
Prior to use, new instruments should be tested against selected
specifications of ANSI N42.17A as well as other specifications as
set forth in the purchase agreement. Instruments which do not meet
the selected specifications should not be accepted or used by the
facility. Acceptance testing may be based on only a sample of the
instruments purchased for the more difficult-to-test specifications
(temperature, energy response, etc.) but should involve 100%
testing for basic specifications.
B. Instrument Calibration
The instrument shall be calibrated within acceptable limits against a
standard with a known relation to national standards (ANSI N323 & RCM
562.1). The calibration "shall" be performed at the required frequency to
maintain an acceptable accuracy for measurements and "shall" not exceed
one year (10 CFR 835.401(c)(1)). ANSI N323 and NIST Special Publication
812, "Criteria for the Operation of Federally-Owned Secondary Calibration
Laboratories (Ionizing Radiation)" (NIST, 1991), have set forth criteria
for proper calibration.
C. Functional testing
The instrument "shall" be routinely tested during its use (10 CFR
835.401(c)(4) and RCM 551.2), and periodically examined and tested to
ensure that it maintains the required performance. This may require
detailed ANSI N42.17 testing or simple functional tests performed during
routine calibrations (ANSI N323, Section 3). During use in the field,
instruments "shall" be tested frequently with a check source to ensure
that the readings remain within prescribed limits, as required by 10 CFR
835.401(c)(4) and ANSI N323 (Section 4.6). Functional tests will also
include battery checks and other field checks, as prescribed by the
manu- facturer or facility. Damaged or malfunctioning instruments
should be promptly returned for maintenance.
D. Maintenance
Maintenance of portable survey instruments "shall" be provided (10 CFR
835.401(c)(1)) and a program for both preventive and corrective
maintenance should be established and documented (RCM 563.1).
Instruments shall undergo calibration prior to use following any
maintenance or any adjustment that voids the previous calibration (RCM
563.3).