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Lesson 2 covers Radiation and contamination surveys as well as how to properly tag them. Radiation and contamination surveys are essential processes used to assess and monitor the presence of radioactive materials in various environments. These surveys are conducted to ensure the safety of workers, the public, and the environment in areas where radioactive materials are used, stored, or potentially released. You can click this link for the next lesson.
Here's an overview of radiation and contamination surveys:
1. Purpose:
Radiation Protection: To assess and control radiation exposure to individuals in a given area, ensuring that it remains within acceptable limits.
Environmental Monitoring: To evaluate the impact of radioactive materials on the surrounding environment.
Nuclear Facility Safety: To identify and mitigate potential sources of contamination or radiation leaks in nuclear facilities.
Emergency Response: To quickly assess and manage radioactive contamination in the event of accidents or incidents involving radioactive materials.
2. Types of Surveys:
Radiation Surveys: These surveys measure radiation levels in the environment using instruments such as Geiger-Muller counters, scintillation detectors, or ionization chambers. They provide information on the level of ionizing radiation present.
Contamination Surveys: Contamination surveys are focused on identifying the presence of radioactive contamination, which may include radioactive particles or substances adhering to surfaces or materials. These surveys often involve swipes, wipes, or direct measurements with contamination detectors.
3. Survey Equipment:
Radiation Detectors: Instruments used to measure radiation levels and types, including Geiger-Muller counters, scintillation detectors, and ionization chambers.
Contamination Detectors: Instruments designed to detect and measure radioactive contamination on surfaces. These can include smear detectors, swipe tests, and wipe tests.
4. Survey Locations:
Surveys are conducted in areas of interest, such as nuclear power plants, research facilities, medical institutions, and contaminated areas, as well as locations with potential radiation hazards.
5. Survey Frequency:
The frequency of surveys varies depending on factors like the type of facility, regulatory requirements, and the potential for contamination or radiation exposure. Routine surveys are often conducted, especially in high-risk environments.
6. Data Analysis:
Survey data is analyzed to determine whether radiation levels and contamination levels are within acceptable limits. If levels exceed established criteria, corrective actions are taken to mitigate the risks.
7. Reporting and Regulatory Compliance:
Survey results are reported to regulatory authorities to demonstrate compliance with safety standards and regulations. Authorities may set specific limits for allowable radiation and contamination levels.
8. Emergency Response:
In emergencies or incidents involving radioactive releases or accidents, surveys are crucial for assessing the extent of contamination and guiding response efforts, such as decontamination and evacuation procedures.
9. Training and Safety Measures:
Personnel conducting radiation and contamination surveys must receive proper training in the use of survey equipment and safety procedures to minimize their radiation exposure and ensure accurate results.Radiation and contamination surveys are fundamental to maintaining the safety of nuclear facilities and protecting the health and well-being of individuals and the environment in areas where radioactive materials are present. These surveys help identify and manage potential hazards associated with ionizing radiation and radioactive contamination.
This procedure describes the process for performing
and documenting radiological surveys.
This procedure provides
instructions to survey for radiation and contamination levels. Instructions for air sampling are provided in
NISP-RP-03, Radiological Air Sampling. Air sampling results are documented on survey
maps as described in this procedure.
Member utilities are
expected to use this standard to enable supplemental workers to transition
between nuclear power plants with minimal site-specific training. Adherence to these instructions is expected
without additional site requirements or process deviations being imposed that
may require additional training or challenge the performance of supplemental
workers.
This procedure will be
used to train and instruct supplemental radiological protection
technicians. Member utilities will
implement these process requirements in site procedures and update site
procedures whenever requirements or process steps in this Nuclear Industry
Standard Process (NISP) are revised.
Current revisions are maintained on the INPO website.
Terms, acronyms, and
definitions are provided in NISP-RP-13, Radiological
Protection Glossary.
Clarifying notes for
requirements and process steps are provided in Section 4.0 using superscript
numbers.
2.1
Prior to performing a survey, review the most
current survey information for the expected plant conditions to:
2.1.1
Understand the range of radiological conditions
that can be expected.
2.1.2
Obtain the most appropriate survey instruments.
2.1.3
Identify where the highest dose rates and
contamination levels may be located.
2.1.4
Identify abnormal or changing conditions after
completing the survey.
2.2
Surveys of radiation levels, surface
contamination, and airborne radioactivity are required to:
2.2.1
Evaluate the potential radiological hazards in
the workplace.
2.2.2
Inform workers on the radiological hazards to
which they are exposed.
2.2.3
Identify the presence of licensed radioactive
material to ensure controls are established to minimize exposure to personnel
and the public.
2.2.4
Evaluate changes in radiological conditions due
to work activities or changing plant conditions.
2.2.5
Ensure compliance with NISP-RP-04, Radiological Posting and Labeling.
2.2.6
Ensure personnel are provided with the
appropriate dosimetry considering the magnitude, gradient, and types of
radiation present.
2.2.7
Estimate potential doses to personnel and
identify the need for protective measures to prevent unplanned dose.
2.2.8
Determine the radiological risk of work
activities per site procedures.
2.3
Site procedures establish the areas and
frequencies for routine surveys.
2.3.1
Survey frequencies for specific areas are based
on the potential for changing radiological conditions and ALARA considerations.
2.3.2
Routine surveys are performed to verify that radiological
conditions have not extended into areas that are not posted and controlled.
2.3.3
Routine verifications are performed to verify
the integrity of Locked High Radiation Area barricades for preventing unauthorized
access.
2.3.4
Routine surveys are only performed in Locked
High Radiation Areas if routine access is required or if directed by RP
supervision.
2.3.5
Tools and equipment are routinely surveyed and
labeled per NISP-RP-04, Radiological
Posting and Labeling to prevent unnecessary exposure to workers and to
appropriately contain radioactive materials.
The diagram below shows the process steps used by RP
technicians to perform radiological surveys, communicate the results, and document
radiological conditions.
3.1
Survey Dose Rates in an Area
3.1.1
Minimize dose during the survey to the extent
practicable by considering use of the following:
a. Using
extendable probes to maintain distance from the source.
b. Standing
behind shielding materials or structures when possible.
3.1.2
Select and use portable survey instruments that
are suitable to the specific job with respect to the type, energy, and range of
the anticipated radiation fields and expected dose rates.
3.1.3
Set the instrument on a scale representative of
expected dose rates prior to entering the area if the instrument does not have
an automatic scaling feature.
a. If
entering areas with unknown dose rates, use the highest anticipated scale and
adjust as needed.
3.1.4
Extend the instrument in front of the body upon entering the area and slowly
scan the work area and travel paths.
3.1.5
Measure contact and 30 cm dose rates from known
and potential sources, e.g. pipes,
elbows, valves, penetrations, spills, transfer lines, etc.
3.1.6
Measure dose rates approximately chest high to
assess dose rates where dosimetry is normally placed.
3.1.7
If dose rates exceed 100 mrem/hour between the
knees and the head close to a source of high radiation levels, determine if a
dose rate gradient exists that may require relocation of the chest dosimetry or
additional dosimetry as described in NISP-RP-10, Radiological Job Coverage.
a. Identify
the source of the high radiation levels, e.g. overhead piping, floor piping, or
highly contaminated surfaces.
b. Measure
dose rates at heights approximating a worker’s knees, waist, chest, and head in
close proximity to the source of high radiation levels where a worker may be
positioned.
c. If
the highest dose rate is not at chest level, record dose rates as follows:
1) Record
the chest dose rate on the survey record along with the locations of higher
dose rates.
2) Annotate
each dose rate based on body location, i.e. knees, waist, chest, or head per
Attachment 2.
3.1.8
Verify the adequacy of current postings and
change postings as needed to comply with NISP-RP-04, Radiological Posting and Labeling.
a. Notify
RP supervision of any changes in area postings.
3.1.9
Compare measured dose rates to those stated in
applicable RWPs and notify RP supervision if the actual dose rates deviate from
the range recorded on an RWP.
3.1.10 Measure
beta dose rates in known or suspected areas with contamination levels in excess
of 500,000 dpm/100 cm2, e.g. open primary reactor system components
or drained radwaste tanks and reactor cavities.
a. Scan
the surface with an open window ion chamber instrument and obtain static
measurements where the radiation levels are the highest.
b. Obtain
a closed window (CW) and open window (OW) measurement as close to the surface
as possible without contaminating the instrument.
c. Calculate
the beta dose rate by using the following formula:
d. The
beta correction factor is provided by RP supervision; the factor may be located
on the instrument calibration label.
e. Also
obtain CW and OW measurements at 30 cm and determine the gamma and beta dose
rates as described above.
3.1.11 Survey
areas greater than 7 feet above the floor only if ladders, scaffolds, or platforms
are in place to gain access.
a. Survey
permanent installations and post per NISP-RP-04, Radiological Posting and Labeling.
b. If
access is allowed on a temporary installation without a pre-job survey, place a
survey tag at the base of the ladder such as that shown in Attachment 1.
c. If
a pre-job survey is required for accessing a temporary installation, post or tag
the base of the ladder to contact RP prior to entry.
3.1.12 Identify
any areas with radiation streaming and evaluate the dose rates, the source, and
the configuration.
a. Notify
RP supervision to assess the need for mitigating actions.
3.2
Directly Frisk a Surface
3.2.1
Select the appropriate instrument based on the
following:
a.
Use a zinc sulfide or gas flow proportional
detector to frisk for transuranic nuclides.
b.
Use a pancake GM detector to frisk for βγ
emitters.
3.2.2
If verifying the absence of contamination,
ensure background does not exceed the following:
a.
Less than 200 cpm to detect with a pancake GM
detector.
b.
Less than 1 cpm to detect transuranic nuclides.
3.2.3
Slowly move the probe over the surface (e.g., 1
to 2 inches per sec) as closely as possible without contacting the surface (approximately
¼ inches for alpha detector, approximately ½ inches for a GM detector). Upon noticing an increased count rate,
perform the following:
a.
Stop the probe.
b.
Move the probe as close as possible to the area
of interest.
c.
Observe the instrument reading long enough to
determine the count rate above background (ncpm).
d.
Consider contamination as being present if the
count rate is above background.
3.2.4
If the count rate exceeds 50,000 ncpm when
frisking with a pancake GM detector, determine if the cause is a discrete
radioactive particle (DRP) by the following method:
a.
Determine if the count rate rapidly drops as the
probe is slowly moved approximately 1 inch from the centerline geometry. This is a characteristic of a DRP.
b.
Attempt to remove the DRP with tape or other
suitable media and repeat the direct frisk after each attempt to determine if
it has been removed.
c.
Verify if the particle has been isolated with
the tape by frisking the tape.
d.
Notify RP supervision if a DRP was present.
e.
Ensure areas are posted for Discrete Radioactive
Particles per NISP-RP-04, Radiological
Posting and Labeling.
3.3
Perform a Smear Survey
|
NOTE Department of
Transportation (DOT) regulations require smearing a minimum of 300 cm2
for shipment surveys. Refer to site
shipping procedures for required DOT surveys. |
3.3.1
Wipe or rub a disc smear over a surface area of
approximately 100 cm2 using moderate pressure.
a.
If an object has less than 100 cm2 of
surface area, wipe all of the surface area.
1)
Estimate the surface area and ratio to 100 cm2
to document survey results in units of dpm/100 cm2 OR
2)
Document the results as dpm/smear.
3.3.2
Smear enough locations to adequately assess the
locations and quantities of surface contamination in the area.
a.
Number the smears and their location on the survey
map.
b.
If a map or drawing is not available, record
information sufficient to recall where each smear was taken.
c.
Comply with site procedures for smear surveys in
Foreign Material Exclusion (FME) areas.
3.3.3
Take precautions to avoid cross-contaminating
smears.
3.3.4
Analyze smears using one or more of the methods
in section 3.6.
3.4
Perform a Large Area Smear Survey
|
NOTE Large area smears (also
called wipes or sweeps) provide a qualitative assessment that is used to
verify the absence of removable contamination in a relatively large area;
large area smears have a detection threshold but they are not used to
quantify removable contamination levels. |
3.4.1
Wipe one side of the survey cloth on the surface
area as follows:
a.
Wipe floors with a cloth mop to obtain a
representative sampling of the area.
b.
Wipe the entire surface of items such as boxes,
containers, equipment, etc.
c.
Suspend wiping the surface if the survey cloth
becomes wet or loaded with debris, dust, or dirt.
d.
Do not use wipes if the surface is so rough that
the cloth is torn by rubbing it on the surface.
e.
Use multiple wipes as needed.
f.
Wipe an area greater than 5 times the surface
area of the wipe to achieve a detection threshold less than 1,000
dpm/100 cm2 of loose surface contamination.2
3.4.2
Directly frisk the surface of the wipe in an
area where the background is less than 200 cpm.
3.4.3
If an increase above background is observed but
the count rate is less than 100 ncpm, then take either of the following
actions:
a.
Repeat wipes in the area until contamination is
not detected above background.
b.
Perform a smear survey to identify areas that
need cleaning and initiate actions to clean affected areas.
3.4.4
If the direct frisk yields greater than 100 ncpm,
take the following actions:
a.
Post the area where the large area smear was
obtained as a Contaminated Area per NISP-RP-04.
b.
Perform a smear survey (100 cm2
smears) within the posted area to identify specific areas that need cleaning.
c.
Initiate actions for decontamination as desired
for removal of Contaminated Area postings.
d.
Record a survey to show the following:
1)
The area that was smeared by the large area
smear and subsequently posted.
2)
The highest ncpm reading from the direct frisk
of the large area smear.
3)
Results from the follow-up smear survey (100 cm2
smears).
4)
Post-decontamination results to justify removal
of Contaminated Area postings.
3.4.5
If an increase above background is not observed,
the removable contamination levels are less than the detection threshold of 1,000
dpm/100 cm2.2
3.5
Survey for Discrete Radioactive Particles
3.5.1
Wipe the surface with a survey cloth or other
tacky material where contamination levels are greater than 100,000 dpm/100 cm2,
i.e. a High Contamination Area.
3.5.2
Directly frisk the wipe material using the
audible function if available to help discern quick increases and decreases in
count rate.
a.
If available, use a collimator cover for the
detector with a small hole or slit to help identify the exact location of the
particle.
3.5.3
Attempt to isolate and contain the particle as
described in section 3.2.4. If the
particle cannot be removed, it is sufficiently entrained where it is located.
3.5.4
Survey the particle with an ion chamber
instrument to obtain both closed window (CW) and open window (OW) measurements.
a.
An OW/CW ratio less than 10 normally indicates a
fuel fragment.
b.
An OW/CW ratio greater than 30 normally
indicates a corrosion product.
3.5.5
Ensure areas with discrete radioactive particles
are posted and controlled per NISP-RP-04, Radiological
Postings and Labeling.
3.5.6
Submit the particle for gamma spectroscopy
analysis as directed by RP supervision.
|
CAUTION Wet or oily smears can
result in significant self-absorption of alpha particles. Dry wet smears prior to analysis using a
method that will not result in losing contamination from the smear. Consult RP supervision for direction to analyze
oily smears. |
3.6.1
Analyze a smear using a pancake GM detector to
measure βγ emitting nuclides.
a.
The detector may be connected to a rate meter or
scaler.
b.
Ensure background is less than 200 cpm if the
purpose of the smear is to verify contamination levels are less than 1,000
dpm/100 cm2.
c.
Center the detector over the smear within ½ inch
from the smear.
d.
Subtract background from the gross count rate to
obtain ncpm above background.
e.
Divide the ncpm by the efficiency factor to
obtain dpm/100 cm2. Use an efficiency
factor of 0.1 unless otherwise directed by RP supervision.
3.6.2
Analyze a smear using a portable ion chamber
survey instrument to measure βγ emitting nuclides.
a.
Obtain closed window (CW) and open window (OW)
measurements with the instrument as close to the smear as possible without
contaminating the instrument.
b.
Calculate the beta dose rate by using the
following formula:
c.
The beta correction factor is provided by RP
supervision; the factor may be on the instrument calibration label.
d.
The gamma dose rate is the closed window
measurement.
3.6.3
Analyze smears for transuranic nuclides as
follows:
a.
For Alpha Level I Areas AND a High Contamination Area, analyze at least 10%, or 3 at
a minimum, of the smears with the higher contamination levels.
b.
For Alpha Level II Areas AND removable contamination levels are greater than 20,000
dpm/100 cm2, analyze at least 10%, or 3 at a minimum, of the smears
with the higher contamination levels.
c.
For Alpha Level III Areas, analyze at least 50%
of the smears to evaluate the magnitude and extent of the alpha contamination.
3.6.4
Analyze smear samples for transuranic nuclides
using an instrument capable of quantifying alpha emission.
a.
The detector may be connected to a rate meter or
scaler.
b.
Ensure background complies with posted limits to
provide the required MDA value and to ensure light is not penetrating the zinc
sulfide detector covering.
c.
Center the detector over the smear within ¼ inch
from the smear without contacting the surface.
d.
Subtract background from the gross count rate to
obtain ncpm above background.
e.
Divide the ncpm by the efficiency factor posted
with the detector to obtain dpm/100 cm2.
|
CAUTION Prevent
contamination of smear counters by complying with site limits for the
maximum amount of contamination that can be on a smear. Limits are based on the highest allowed
cpm measurement from the smear using a frisker. |
3.6.5
Analyze a smear using an automated smear counter.
|
NOTE Most automated counters
have operating software that calculates both alpha and beta dpm values
during one pass through the counter. |
a.
Achieve familiarity with operating the software
for the smear counter.
b.
Ensure background is within posted parameters for
the counter.
c.
Exercise extreme care in placing and removing
smears in planchets to avoid contaminating the counter and detector, causing an
increase in background.
3.7.1
If a smear has been analyzed for transuranic
nuclides, determine the βγ/α Ratio of
each smear as follows:
3.7.2
If the βγ/α Ratio is
less than or equal to 30,000 and the total transuranic alpha activity is
greater than or equal to 20 dpm/100 cm2, verify the smeared location
is properly posted as an Alpha Level 2 or 3 Area as required by NISP-RP-04.
a.
If the current posting does not sufficiently encompass
the hazards from transuranics, immediately take the following actions:
1)
Upgrade the posting consistent with NISP-RP-04.
2)
Notify RP supervision.
3.7.3
If the βγ/α Ratio is
less than or equal to 50 and the total transuranic alpha activity is greater
than or equal to 20 dpm/100 cm2, verify that an alpha frisker is available
and the area has been posted to require alpha frisking per NISP-RP-04.
3.7.4
If the smear was taken on equipment or material removed
from an area and the βγ/α Ratio is
less than or equal to 300 and the total transuranic alpha activity is greater
than or equal to 20 dpm/100 cm2, take the following actions:
a.
Verify the container with the equipment or material
is tagged “Level 3 Alpha Area” as required by NISP-RP-04.
1)
If the container tag has to be revised,
immediately notify RP supervision.
b.
Verify the area from which the equipment was
removed is posted as an Alpha Level 3 Area as required by NISP-RP-04.
1)
If the posting is not for an Alpha Level 3 Area,
immediately upgrade the area posting and notify RP supervision.
3.8
Respond to Abnormal Survey Results
3.8.1
Immediately notify RP supervision for any of the
following conditions:
a.
Changes in radiological conditions that require
changes in postings or RWPs.
b.
Dose rates greater than the site limit outside
an RCA.
c.
Discovery of radioactive material outside the
RCA.
3.8.2
If the criteria in NISP-RP-10 are met, stop
work.
3.9
Document a Radiological Survey
|
NOTE Programs and software used
to document radiological surveys vary among plant sites. Surveyors must become accustomed to site
expectations for using survey maps and software applications. The nomenclature described in Attachment
2 includes accepted industry standards. |
3.9.1
Document survey results in a timely manner using
site-specific forms, maps, and software with the symbols and abbreviations
listed in Attachment 2.
3.9.2
Annotate station unique symbols on surveys as
appropriate. Common nuclear accepted
acronyms and abbreviations do not need to be defined.
3.9.3
Ensure the recorded data provides sufficient
detail to effectively communicate the radiological conditions within the
surveyed area.
3.9.4
Evaluate the recorded information and posted
conditions to ensure compliance with NISP-RP-04, Radiological Postings and Labeling.
3.9.5
Ensure radiological survey documents meet the
following criteria prior to submittal for RP supervision review and approval:
a.
Hot Spots as defined in NISP-RP-04, RadiologicalPosting and Labeling are identified with contact and 30 cm measurements.
b.
Radiological postings as defined in NISP-RP-04
are accurately aligned with the radiological measurements recorded on the
survey.
c.
If a contaminated system was breached during the
survey, measurements are provided for:
1)
Contact and 30 cm gamma measurements on exposed
system internals.
2)
Contact and 30 cm beta dose rates if
contamination levels exceed 500,000 dpm/100 cm2.
3)
Air sample results during the breach as required
by site supervision.
4)
Smear results from the exposed internal surface.
5)
Smear results from the area around the breached
component.
d.
Posted boundaries are delineated and labeled
with any changes identified and explained.
e.
Air sample results are provided as required for
job coverage.
f.
Smear surveys are representative of the area to
sufficiently assess general area contamination levels.
g.
The survey date, time, and location are clearly
recorded.
h.
The survey instrument used is identified by a
serial number.
i.
The RWP number is referenced if the survey was
performed in support of an RWP.
j.
The surveyor’s printed name and signature are
recorded for hand written surveys.
1)
Names and approvals for electronic survey
systems are entered based on the software application in use.
5.1
NISP-RP-03, Radiological Air Sampling
5.2
NISP-RP-04, Radiological Posting and Labeling
5.3
NISP-RP-10, Radiological Job Coverage
5.4
NISP-RP-13, Radiological Protection Glossary
5.5
Blue L.
Detection Threshold of Large Area Wipes.
Health Phys Op Rad Safety 106(Supp 2): S5-S11; 2014.
Attachment 1: Temporary Survey Tag – Example
Attachment 2: Radiological Survey Map Symbols & Abbreviations
Survey information in the form of maps, signs,
radiation work permits (RWPs), or status boards should be readily available via
computer or at the RCA access area and, as appropriate, at the entrances to
work areas. The information should be up to date, clearly written and displayed
in format that is easily understandable by workers. Radiological survey information should
provide workers with a clear understanding of the hazards and low-dose zones in
their work areas. Date the survey
information so radiological protection technicians and workers can evaluate its
applicability based on known system changes.
Workers review this information, attend job briefings, or self-brief for
low radiological risk activities that include appropriate survey information,
and use the information to control their doses.
Consistent
radiological survey symbols enhance the radiation worker’s and radiation
protection technician’s ability to interpret surveys and identify hazards.
Standardized survey symbols reduce training needs for traveling workers and
radiation protection technicians.
Whole Body Dose Rates
Record chest high dose rates at the approximate
locations of the measurements. No
additional symbols or annotation is required unless the measurement is for a
dose rate gradient.
Record measurements of a dose rate gradient
identifying the source of the gradient, the location of the highest radiation
levels, and noting the approximate measurement heights as follows:
·
Knees
·
Waist
·
Chest
·
Head
Symbols
Δ – Indicates air sample
data. The type of A/S may be designated
by placing a letter inside the “Δ” (except for breathing zone air samples it is
assumed the others are general area air samples).
·
Particulate A/S is designated by placing a “P”
inside the “Δ”.
·
Iodine A/S is designated by placing an “I”
inside the “Δ”.
·
Noble Gas A/S is designated by placing an “G” inside
the “Δ”.
·
Breathing Zone, A/S is designated by placing a
“BZ” inside the Δ.
Ο – Indicates contamination
data. A number should be placed inside
the “Ο” corresponding to referenced smear location.
__*#__/___#___ – Indicates contact and
30 cm gamma dose rate readings; where the numerical value with the asterisk
shall display the contact gamma dose rate and the second numerical value shall
display the 30 cm gamma dose rate.
HS – Indicates a hot spot. Contact and 30 cm dose rate (same format as
above) of the hot spot may be placed adjacent to the HS.
N – Indicates dose rates due to neutron
radiation.
·
50N indicates 50 mrem/hr general area due to
neutron radiation.
Î’ – Indicates the dose rate
due to beta radiation, applying a beta correction factor.
·
50 β indicates 50 mrad/hr corrected beta dose
rate; contact and 30 cm readings should be displayed using the same format as
above
XXX or ----- – Designates a radiological area boundary. Used in conjunction with RCA, RA, HRA, LHRA,
VHRA, ARA, CA, HCA, RMA, etc.
Additional
Information
Other information
displayed on radiological postings such as “keep out” or a range of gamma dose
rates found in the area may be added.
Other information should be standardized as follows:
· “KO”
for keep out
· “NRP”
for notify RP prior to entry
· “LDWA”
for low dose waiting area
· A
rectangle with the letters “SOP” shall be placed at the entrance to a
contaminated area to designate a step off pad
Radiological Units
· “mR/hr or mrem/hr,” or unit variations, should
be used to designate dose rates due to gamma radiation.
· “mrad/hr”
should be used to designate dose rates due to beta radiation.
· “N”
for dose rates due to neutron radiation in mrem/hr.
o 50
N indicates 50 mrem/hr general area due to neutron.
· Percent
DAC should be used when designating the airborne radioactivity in an area.
· “dpm/100
cm2” should be used when designating the contamination level in a
specific location using a standard disc smear.
· “<1,000
dpm/100 cm2” should be used to record large area smear results if
direct frisking of the smear did not yield ≥ 100 ncpm.
· “ncpm
/ LAS” (large area smear) should be used when designating the contamination
level if a direct frisk of the large area smear yielded ≥ 100 ncpm. The abbreviation, LAS, should be spelled out
on the survey map.
· “mrad/hr/100
cm2” should be used when designating the contamination level in a
specific area that has been determined using a dose rate meter and a standard
disc smear or “mrad/hr/LAS” if an area larger than 100 cm2 was
surveyed.
· “K”
should be used for thousands of dpm; for example, 1K dpm/100 cm2 is
equal to 1000 dpm/100 cm2.
· “ND”
(non-detectable) or “<ND dpm/100 cm2” should be used when
contamination is below detectable levels.
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