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ES&H
Manual Radiation Control Supplement |
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Chapter 5 – Radiological Health Support Operations |
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511
Types of
Personnel Dosimetry
At Jefferson Lab, monitoring of personnel exposed to ionizing radiation is accomplished by use of personnel dosimetry devices. The types currently in use are:
- Accredited personnel dosimeters (i.e., optically stimulated luminescence
(OSL)
badge),
- Supplemental, self-reading dosimeters (SRD), typically of the
digital, programmable type.
Currently, Jefferson Lab uses dosimeters that are sensitive to beta, gamma and neutron radiation. The personnel dosimeters provide “dose of record” measurements for gamma rays, neutrons, x-rays and charged particle exposures.
511-01)
Personnel dosimeters are provided and
processed by an outside lab and are normally changed semiannually. Personnel dosimeters are available through
the Radiation
Control Department (RCD). Personnel
external dosimetry programs shall be adequate to demonstrate compliance with
the occupational exposure limits and monitoring requirements in 10 CFR 835. The program shall include routine dosimeter calibration
and conformance with the requirements of the Department of Energy (DOE)
Laboratory Accreditation Program (DOELAP) for Personnel Dosimetry (or shall be
determined by the Secretarial Officer responsible for environmental, safety,
and health matters to have substantially equivalent performance). Jefferson Lab maintains a DOELAP-accredited
external dosimetry program [§835.402(b)].
511-02)
The digital self-reading dosimeter (SRD) is
a supplemental device used for real-time dose tracking in conjunction with
RWPs, and for issuance to visitors needing access to RCAs for short
periods. The SRD can be programmed with
dose and dose-rate alarm levels to alert the wearer when predetermined limits
are being approached. This type of dosimeter
is available through the RCD. The
digital dosimeter should not be worn in areas where pulsed radiation fields are
known or expected to occur.
511-03)
Individual exposures
are tracked during each monitoring period via SRD results, and OSL-badge doses
are reviewed after each dosimeter exchange.
In keeping with the Jefferson Lab design goal alert notification system,
individuals who receive more than 120 mrem during a semiannual monitoring period
(based on either SRD or OSL badge) are notified in writing (along with their
supervisor) and are placed on a more frequent dosimeter processing cycle –
normally monthly. The Radiation Control
Manager (RCM) may designate individuals for monthly processing at his/her
discretion based on dose history,
nature and location of work, and expected exposure levels for upcoming
periods.
512-01)
Personnel dosimeters
are issued on a permanent basis to Jefferson Lab Radiological Workers who
routinely enter and work in Radiologically
Controlled Areas.
512-02)
Personnel dosimeters shall be provided
to and worn by Radiological Workers who, under typical
conditions are likely to receive one or more of the following:
a)
An effective dose
of 100 mrem
in one year;
b)
An equivalent
dose to the skin or to any extremity of 5 rem or more in a year;
c)
An equivalent dose to
the lens of the eye of 1.5 rem or more in a year [§835.402(a)(1)].
512-03)
Personnel
dosimeters shall be provided to and used by:
a)
Declared pregnant
workers who are like to receive in excess of 10% of the applicable limit in 10
CFR 835.206(a);
b)
Occupationally
exposed minors who are like to receive in excess of 50% of the applicable
limits in 10
CFR 835.207;
c)
Members of the
public entering a controlled area who are like to receive in excess of 50% of
the limit in 10
CFR 835.208 in a year from external sources; and
d)
Individuals entering a High
or Very High Radiation Area [§835.402(a)(2), (3), (4), (5)].
512-04)
Supplemental dosimeters shall be worn for entry
into a posted High Radiation or Very High Radiation Area, when there is a potential for
whole-body exposure to a radiation field of 100 mrem/h or greater, or as required by any work permit
or technical work procedure.
512-05)
Dosimeters shall be worn
between the neck and waist unless otherwise specified by the RCD. When an SRD is worn with a personnel dosimeter,
the dosimeters should be placed next to each
other. The dosimeter should be worn consistently at the same location on the body
unless otherwise instructed by the RCD. It should be worn on the outside of all
clothing.
512-06)
Dosimeters shall be
returned to their appropriate storage location at the end of the work day. Personnel dosimeters shall be stored in the
designated rack, and SRDs shall be logged in by RCD
staff members and stored for reuse.
512-07)
The RCD determines the need for special configuration dosimetry. Special configuration dosimeters (rings, bracelets, etc.) are available from the RCD. A lead time of
approximately 72 hours should be anticipated if a special configuration is
required.
512-08)
Personnel whose duties
make them radiological workers are provided permanent
dosimetry. The worker shall complete the
Jefferson Lab Personnel Dosimeter Request and an Ionizing Radiation Record Transfer Request (if applicable). A Line
Management representative shall sign the form to indicate that the person needs
a personnel dosimeter. The form(s) shall
then be forwarded to the RCD for dosimeter issuance. These steps may be conducted through an
electronic system having secure access and electronic signature
capability. The RCD will review the
dosimeter application and if applicable, establish a special control level in
accordance with Article
217 of this Manual. The radiological
worker and his/her supervisor are responsible for ensuring that the worker does
not exceed this limit.
512-09)
Dosimeters shall be
issued only to personnel formally instructed in their use and shall be worn
only by those to whom the dosimeters were issued.
512-010) Part of the success of an organization’s efforts to reduce total exposure is ensuring that as few people as necessary are authorized to receive radiation exposure. Periodically, a review should be performed to confirm that all persons so authorized actually have a need to be so authorized. The RCM shall make recommendations through the JRRP or other Line Management mechanisms for adjustments to policies and procedures that may cause significant unnecessary assignments of dosimetry or designation of individuals as radiological workers.
512-011)
Personnel shall return dosimeters for processing as scheduled or upon request.
512-012) A person, whose dosimeter is lost,
damaged, or contaminated while working should place work in a safe condition,
immediately exit the area, and report the occurrence to the RCD.
513
Circumstances
Requiring an Exposure Investigation
An exposure investigation is required in the following circumstances:
513-01)
Missing exposure record (i.e., personnel dosimeter is
lost or damaged).
513-02)
Suspected inaccuracy in
the exposure record.
If there is a serious discrepancy between the personnel dosimetry report and the person’s expected exposure, the dosimetry records shall be reviewed and adjusted if
necessary. Other circumstances of
suspected inaccuracies requiring exposure
investigations include discrepancies between multiple badges (when they are
worn at the same time), exposures occurring when the
person was not wearing a badge, and in accidental exposure situations.
513-03)
Unusual exposures or a large increase in reported exposure for a personnel dosimeter reading period as compared to previous
exposures.
513-04)
Any personnel
dosimeter result exceeding the Alert Level (250 mrem), when not anticipated
based on supplemental dosimeter results during the period.
514
Self-Reading Dosimeters
Self-reading dosimeters are supplemental dosimeters that
provide real-time indication of exposure to radiation and assist in maintaining personnel doses less than Administrative Control Levels. The digital dosimeter should not be worn in areas where there is the likelihood of
encountering pulsed radiation fields, high magnetic
fields, or radio frequency
radiation.
514-01)
Supplemental dosimeters should be read periodically while in use.
514-02)
Routine work on a
Radiological
Work Permit shall be stopped when supplemental dosimeter readings indicate total exposure or a
rate of exposure substantially greater than
planned. The RCD shall be consulted prior to continuation of work.
514-03)
Routine comparisons and
evaluations should be made of individual and collective exposures from
RWP-related supplemental dosimeter readings and dose-of-record monitoring
results. These comparisons are useful in
evaluating radiological performance and ALARA efforts.
514-04)
The energy and pulse
rate dependence of supplemental dosimeters should be
considered in determining their applicability.
515
Area Monitoring
Dosimeters
Establishment
and maintenance of a comprehensive area monitoring
program minimizes the number of areas requiring the issuance of personnel dosimeters and demonstrates that doses inside Controlled
Areas are negligible.
Minimizing the number of personnel dosimeters
issued saves in the costs of operating the dosimetry program and reduces costs
associated with maintaining personnel with enhanced training and
qualifications.
Area monitoring dosimeters should be used to record
and document radiation levels in routinely occupied
areas adjacent to areas where radiation or
operations with radiation exist.
521
Individual Monitoring
521-01)
For the purpose of monitoring individual exposures to internal radiation, internal dosimetry programs (including routine bioassay programs) shall be conducted for:
a)
Radiological workers
who, under typical conditions, are likely to receive a committed effective
equivalent dose of 100 mrem or more from all occupational radionuclide intakes in a year;
b)
Declared
pregnant workers likely to receive an intake or intakes
resulting in an equivalent
dose to the embryo/fetus in excess of 10% of the
limit stated in 10
CFR 835.206(a);
c)
Occupationally exposed
minors who are likely to receive a dose in excess of
50% of the applicable limit stated in 10
CFR 835.207 from all
radionuclide intakes in a year; or
d)
Members of the public
entering a controlled area who likely to receive a dose in excess of 50% of the limit stated in 10 CFR
835.208 from all
radionuclide intakes in a year [§835.402(c)].
521-02)
Internal
dose monitoring programs
implemented to demonstrate compliance with Article 521-01 shall be adequate to demonstrate compliance with the dose limits established in Tables
2-1A and 2-1B and (if applicable) shall be:
a)
Accredited, or excepted
from accreditation, in accordance with the Department of Energy (DOE)
Laboratory Accreditation Program for Radiobioassay; or
b) Determined by the Secretarial Officer responsible for environment, safety and health matters to have performance substantially equivalent to that of programs accredited under the DOE Laboratory Accreditation Program for Radiobioassay [§835.402(d)].
Respiratory protection equipment includes National
Institute for Occupational Safety and Health (NIOSH) -
approved respirators with particulate or gas-filtering cartridges, supplied air
respirators, self-contained breathing apparatus, and airline supplied-air suits
and hoods.
531-01)
Use of respiratory
protection shall be reduced to the minimum practicable by implementing engineered
controls and work practices to contain radioactivity at the source.
531-02)
Respirators shall
be issued only to personnel who are trained, fitted, and medically qualified to
wear the specific type of respirator.
Training and qualification testing shall be performed as specified in ES&H Manual Chapter 6630
Respiratory Protection.
531-03)
The use of respiratory
protection for radiological controls shall be in accordance with the Jefferson
Lab respiratory protection program, and should be tailored for consistency with
applicable guidance specific to radiological respiratory protection, such as
NRC Regulatory
Guide 8.15, “Acceptable Programs for Respiratory Protection”.
541-01)
When personnel detect
skin contamination, they shall notify the RCD.
541-02)
The extent of skin
contamination should be determined prior to initiating decontamination procedures.
541-03)
Skin decontamination methods should be non-invasive.
Skin abrasion should be avoided during the decontamination process. Any decontamination with the possibility of causing injury shall be performed under
the auspices of Jefferson Lab Occupational Medicine personnel. See National Council on Radiation Protection
and Measurements Report Number 65.
Medical treatment of injuries takes precedence over radiological
considerations.
541-04)
Personnel with skin
contamination that may cause a dose greater than the
alert level in Tables 2-1A and 2-1B shall be assessed and should be informed of their initial dose estimate as soon as practicable.
An assessment of skin exposure requires time
to conduct a detailed evaluation. Final dose assessments should be explained to the persons affected as soon
as practicable.
541-05) The treatment of contaminated injuries should be coordinated with Jefferson Lab Occupational Medicine or other appropriate medical personnel.
Monitoring of radiation is performed using fixed
(area) or portable radiation instruments, or a
combination thereof. Both the fixed and
portable instruments must be readily available and capable of measuring ambient
radiation dose rates for
the purpose of controlling radiation exposures. Prior to starting any
operation that could produce radiation, all
stationary instruments should be checked to ensure their proper operation. A review of the central computer data logging
system for area monitor malfunction is adequate to verify proper
operation. Periodic surveys outside of
the operating area are typically performed according to a schedule. Portable instruments should be source checked
prior to and after a survey if possible.
All portable instruments shall undergo a periodic source check performed
by a qualified Radiological Control Technologist (RCT)
or Assigned
Radiation Monitor (ARM). This source check shall be documented on the portable
instrument.
551-01)
Monitoring of
individuals and areas shall be routinely performed, as necessary, to identify
and control potential sources of personnel exposure
to radiation and/or radioactive
material. Monitoring of individuals and areas shall be performed to:
a)
Demonstrate compliance
with 10
CFR 835
b)
Document radiological
conditions;
c)
Detect changes in
radiological conditions;
d)
Detect the gradual
buildup of radioactive material;
e)
Verify the effectiveness
of engineered and process controls in containing radioactive
material and reducing radiation exposure; and
f)
Identify and control
potential sources of individual exposure to radiation and/or radioactive material [§835.401(a)].
551-02)
Instruments and
equipment used for monitoring shall be:
a)
Periodically maintained
and calibrated on an established frequency;
b)
Appropriate for the
type(s), levels, and energies of the radiation(s)
encountered;
c)
Appropriate for existing
environmental conditions; and
d)
Routinely tested for
operability [§835.401(b)].
551-03)
Only trained and
qualified personnel shall perform monitoring.
551-04)
The cognizant
radiological supervisor shall review monitoring
results. The review should ensure that
all required surveys have been performed and that the documentation is accurate
and complete.
551-05)
Results of current
surveys or survey maps should be conspicuously posted to inform personnel of
the radiological conditions.
551-06) Monitoring results should be made available to line management and used in support of pre- and post-job evaluations, as low as reasonably achievable (ALARA) preplanning, contamination control and management of radiological control operations.
552
Controlled Area Radiation Monitors (CARMs)
Fixed
instruments are used to provide an indication of area radiation levels, provide a record of area dosimetry for ALARA program purposes, and for protective trip functions (where they
prevent situations that could cause persons to exceed certain dose limits). Only RCD staff may direct the movement or placement of CARM probes. The calibration, use, and functional certification of these instruments in
safety related systems are the responsibility of the RCD.
552-01)
The need and placement
of area radiation monitors shall be documented and
assessed when changes to facilities, systems, or equipment occur.
552-02)
Area radiation monitors shall be tested at least semi-annually to verify
audible alarm system operability and audibility under ambient working
conditions and operability of visual alarms when so equipped. Interlock function shall be tested at least annually.
552-03) If installed instrumentation is removed from service for maintenance or calibration, a radiation monitoring program providing at least equal detection capability should be maintained, consistent with the potential for unexpected increases in radiation dose rates.
553
Contamination
Control Surveys
Appropriate
controls shall be maintained and verified to prevent the inadvertent transfer
of removable contamination to locations outside of radiological
areas under normal operating conditions. Any area in which contamination levels exceed
the values specified in 10
CFR 835 Appendix D shall be
controlled in a manner commensurate with the physical and chemical
characteristics of the contaminant, the radionuclides present, and the fixed
and removable contamination levels.
553-01)
In addition to the
requirements of Article 551, routine contamination surveys should be conducted as follows:
a)
Prior to transfer of
equipment and material from Contamination
Areas or High
Contamination Areas
b)
Daily, at contamination
area control points, change areas, or step-off pads when in
use, or per shift in high use situations
c)
Weekly, or upon entry if
entries are less frequent, where contamination boundaries or postings are
located
d)
During initial entry
into a known or suspected Contamination
Area, periodically during work, at completion of job,
or as specified in a Radiological Work Permit
e)
After a leak or spill of
radioactive materials.
553-02)
Items with
inaccessible surfaces which were located in known or suspected contamination
areas and have the potential to become contaminated at
levels likely to exceed 10
CFR 835 Appendix D values should be
treated as potentially contaminated and subject to administrative
controls unless the items are dismantled and monitored
or special survey techniques are used to survey all surfaces.
553-03)
Appropriate methods
shall be used for assessing representative samples of bulk material, such as
sand, sweeping compounds, or plate steel, that are not suitable for normal
loose and fixed contamination-level assessment techniques.
553-04)
Swipe surveys for
removable contamination shall be reported in units of disintegrations per
minute per 100 cm2 (dpm/100 cm2). For swipe surveys of
small items covering less than 100 cm2, the results shall be reported in units of dpm per area swiped.
553-05)
Large area wipes should
be used to supplement standard swipe techniques in areas generally assumed not
to be contaminated. If an evaluation
indicates that an area wiped is contaminated, a thorough contamination swipe
survey should be performed.
554
Airborne Radioactivity
Monitoring
In addition
to the requirements of Article 551, air monitoring equipment should be
used in situations where airborne radioactivity
levels can fluctuate and early detection of airborne radioactivity could prevent or minimize inhalation of radioactivity by personnel. Selection
of air monitoring equipment should be based on the
specific job being monitored. Air monitoring equipment includes portable and fixed air sampling equipment and
continuous air monitors. Samples are
taken as necessary to detect and evaluate the level or concentration of
airborne radioactive material at work locations.
554-01)
Monitoring of airborne radioactivity shall be performed:
a)
Where an individual is
likely to receive an exposure of 40 or more derived air
concentration
(DAC)-hours in a year; or
b)
As necessary to
characterize the airborne radioactivity hazard where
respiratory
protective devices for protection against airborne
radionuclides have been prescribed [§835.403(a)].
554-02)
Real-time air monitoring shall be performed as necessary to detect and provide warning of
airborne radioactivity concentrations that warrant
immediate action to terminate inhalation of airborne radioactive
material [§835.403(b)].
554-03)
Air sampling equipment
should be positioned to measure air concentrations to which persons are
exposed. If this cannot be achieved, a
program of personal breathing-zone air sampling will be initiated.
554-04)
Air monitoring equipment shall be routinely calibrated and maintained at a
frequency of at least once per year.
Continuous air monitors should be capable of measuring 1 DAC when averaged over 8 hours (8 DAC-hours).
554-05)
For the airborne radioactive
material that could be encountered, real-time air monitors
shall have alarm capability and sufficient sensitivity to alert exposed or
potentially exposed individuals that immediate action is necessary in order to
terminate or minimize inhalation exposures.
554-06) The proper operation of continuous air monitoring equipment should be periodically verified by observing relevant computer records of continuously logged operational parameters. Operational checks should include positive air-flow indication, non-zero response to background activity, and internal check sources.
561
Availability at Jefferson Lab
The RCD is responsible for the
maintenance, calibration, and operability of radiation detection equipment used for personnel radiation protection. Instruments used for monitoring and contamination control shall be:
·
Maintained and periodically
calibrated on an established frequency of at least once per year;
·
Appropriate for the type(s),
levels, and energies of the radiation(s) expected;
·
Appropriate for existing
environmental conditions; and
· Routinely tested for operability.
For
fixed instrumentation, when appropriate, the annual calibration frequency may
be extended, if determined through documented analysis that periods longer than
one year can be used without degradation in equipment reliability and
accuracy. Such evaluations should be
conducted in accordance with National Conference of Standards Laboratories
Recommended Practice RP-1,
“Establishment and Adjustment of Calibration Intervals”.
562
Use of Radiation
Monitoring Instruments
562-01)
Prior to using an
instrument, checks should be made by the Radiological
Control Technologist (RCT) or Assigned Radiation
Monitor (ARM):
a)
Visual check – Check for
physical integrity of the instrument.
Discrepancies include loose or broken knobs and switches, broken probe
cords, broken probes, and cracked meters.
b)
Check instrument calibration due date. Do not use an
instrument that is overdue for calibration.
c)
Battery check – All
battery powered instruments with a “battery check” switch position shall be
checked prior to use. A meter reading in
the indicated range is the indication of a successful battery check.
d)
Function check – Where
provided, follow posted instructions and perform a source check on the
instrument. Sources are installed in a
test rig and a list of acceptable responses is provided.
562-02)
If any discrepancies are
noted during the performance of the above checks, a “Faulty Instrument” tag
should be filled out and attached to the instrument. The instrument should be returned to the RCD and a replacement obtained.
UNDER NO CIRCUMSTANCES SHALL A FAULTY INSTRUMENT BE USED.
562-03)
When choosing an
instrument, care should be taken to select one with a range high enough for the
expected conditions. Not only will
having the incorrect instrument waste time, but it will also unnecessarily
increase radiation exposure.
562-04)
The correct instrument
for use on any given survey shall be determined by the RCD.
562-05)
When entering an area
where the level of the radiation field is unknown,
the instrument should be set to operate on the highest range until it is seen
that the meter reads less than one quarter of the full scale. The operating switch should then be moved to
successively lower ranges until the indicated reading is between one quarter
and three quarters of the full scale or the lowest range is reached. Note that auto-ranging instruments will
select the correct range for the user.
562-06) After use, the instrument should be returned to its appropriate storage location. Ensure that the instrument is turned off prior to storage. Instruments that appear damaged, that failed response checks, or that may otherwise be unfit for future use shall be tagged and returned to the RCD and a replacement obtained.
563
Inspection, Calibration,
and Performance Tests
563-01)
Radiological instruments
shall be used only to measure the radiation for
which their calibrations are valid. Records of calibration and repair will be kept for each instrument. National Institute of Standards Technology
(NIST) traceable sources shall be used for calibrations.
563-02)
Calibration procedures shall be maintained for each instrument type, and include
frequency of calibration, recalibration
requirements, primary calibration requirements,
periodic performance test requirements, calibration
record requirements and maintenance requirements.
563-03)
Radiation
instrumentation response to interfering ionizing and
non-ionizing radiation and environmental conditions
should be known prior to use.
563-04)
Functional tests shall
be used to assess instrumentation designs that include alarms or that involve a
process control. A functional test shall
be performed to test all components involved in an alarm or trip function and
should be performed at least annually.
563-05)
In unusual and limited
situations, it may be necessary to use an instrument in an application other
than that envisioned by the manufacturer.
The instrument shall be adjusted, calibrated and/or labeled as
appropriate to identify the special conditions and used only under the special
conditions for which it was calibrated.
563-06)
Instruments shall bear a
label or tag with the date of calibration and date calibration is due.
563-07)
Instruments whose “as found”
readings indicate that the instrument may have been used while out of calibration
shall be reported to the RCD. The RCD should
review surveys performed with the instrument while it was out of calibration
and determine if additional surveys are needed.
564-01)
A program for preventive
and corrective maintenance of all radiological instrumentation shall be
maintained and documented.
564-02)
Preventive and
corrective maintenance should be performed using components and procedures at least as stringent as those specified by the manufacturer of
the instrument.
564-03)
Radiological
instruments shall undergo calibration prior to use
following any preventive or corrective maintenance or any adjustment that voids
the previous calibration. A battery change is not normally considered
maintenance.
565
Calibration
Facilities
565-01)
Calibration facilities
should perform inspections, calibrations,
performance tests, calibration equipment selection
and quality assurance in accordance with the recommendations of ANSI N323A and
take the following actions:
a)
Locate activities in a
manner to minimize radiation exposure to operating personnel and to personnel in adjacent areas.
b)
Minimize sources
of interference, such as backscatter and non-ionizing radiation, during the calibration of instrumentation
and correct for interferences as necessary.
c)
Operate in accordance
with the referenced standards.
d)
Generate records of calibration, functional tests and maintenance in accordance with the
referenced standards.
565-02)
For calibrations
that cannot be performed by Jefferson Lab, contracted calibration services should be performed in accordance with Jefferson Lab
approved procedures.
566
Radiation Safety Interlocks
Safe
operations require that a number of electrical and mechanical conditions be
satisfied before radiation production can
begin. As described in ES&H Manual Chapter 6311 Prompt Radiation Control, interlock systems are designed to ensure that these conditions are satisfied. Interlocks are
designed to be “fail safe” and to have considerable redundancy in the system.
Interlock
systems shall be described in the work control document approved for
the operation. Periodic testing of the interlock systems shall be used to verify system integrity.
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ISSUING
AUTHORITY |
CHAPTER
AUTHOR |
APPROVAL
DATE |
EFFECTIVE
DATE |
EXPIRATION
DATE |
REV. |
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RadCon Dept |
07/01/10 |
07/01/10 |
07/01/13 |
4 |
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