SARAD Aer 5400 User manual
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Content
1. Applications and general information................................................................................................. 4
2. Power supply....................................................................................................................................... 6
3. Filter replacement and flow control.................................................................................................... 6
3. 1. Filter sealing mechanism............................................................................................................. 7
3. 2. Replacing the filter ...................................................................................................................... 7
3. 2. 1. Filter replacement for instruments with filter cartridge..................................................... 7
3. 2. 2. Replacing the filter tape ...................................................................................................... 8
3. 3. Flow control............................................................................................................................... 10
3. 4. End of filter and protection of the stepper drive ...................................................................... 10
4. Tube connector ................................................................................................................................. 10
5. Data storage .................................................................................................................................. 11
6. Instrument operation by menus ....................................................................................................... 11
6. 1. Main page.................................................................................................................................. 11
6. 2. Module information and options .............................................................................................. 12
6. 3. Component configuration ......................................................................................................... 12
6. 4. Selecting the cycle..................................................................................................................... 12
6. 5. Recent readings display............................................................................................................. 13
6. 6. Displaying the data stored at the memory card........................................................................ 13
6. 7. Results shown on the display .................................................................................................... 13
7. Instrument set-up.............................................................................................................................. 14
7. 1. Clock switch............................................................................................................................... 14
7. 2. Synchronized start of a measurement ...................................................................................... 14
7. 3. Display standby.......................................................................................................................... 14
8. Alert functions................................................................................................................................... 14
9. Gamma background compensation for the beta channel ................................................................ 15
9. 1. Static gamma background compensation................................................................................. 15
9. 2. Dynamic gamma compensation, dose rate measurement ....................................................... 16
9. 2. 1. Dynamic gamma compensation ........................................................................................ 16
9. 2. 2. Measurement of local dose rate ....................................................................................... 16
10. Natural Uranium separation............................................................................................................ 17
11. Calculation of the average activity concentration .......................................................................... 17
12. Operation conditions....................................................................................................................... 18
13. Communication with a PC ............................................................................................................... 18
14. Alert outputs ................................................................................................................................... 19
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15. User specific settings....................................................................................................................... 19
15. 1. Changing the alert settings for radiometric measures............................................................ 19
15. 2. Changing the threshold level for the count rate ..................................................................... 20
15. 3. Adjusting parameters for the gamma background compensation ......................................... 20
15. 4. Changing units (US/SI) and dose coefficients.......................................................................... 20
15. 5. Controlling the filter stepper drive.......................................................................................... 21
16. Test and maintenance..................................................................................................................... 23
17. Technical Data Aer 5400.................................................................................................................. 24
18. Detection Limits............................................................................................................................... 28
19. Possible modifications of Air Monitor Aer 5X00-XXXX.................................................................... 29
20. Appendix.......................................................................................................................................... 30
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1. Applications and general information
The online continuous air sampler Aer 5400 allows the measurement of the exposure of workers and
first responders with respect to radioactive aerosols. Typical application fields are nuclear facilities,
the NORM industry, mines and nuclear medicine (e.g. DIN ISO 16639 / VDE 0493-1-6639).
The instrument comes with an IP65 protected stainless steel enclosure with plain surfaces which can
be easily de-contaminated. The unit can be mounted either at a wall or on a trolley.
The air inlet (KF/DN16 vacuum flange) is placed on the top of the unit. Particle losses at the inlet
become negligible by the special construction. An electric valve regulates the flow rate automatically
and ensures a uniform and low-loss deposition of the aerosols on the filter surface. This solution
allows the user to connect the unit either to a pump or a central vacuum supply. In this case, the
central vacuum supply should be able to generate a pressure difference of 400 mbar at the desired
flow rate, which is 35 l/min per instrument as a standard.
The unit measures long lived radioactive dust (LLRD) as well as natural occurring Radon daughter
products. Both values are presented separately. The influence of Radon daughters is dynamically
compensated for LLRD detection. Following results are achieved from the acquired energy spectrum
•Alpha exposure, dose and average concentration for LLRD
•Beta exposure, dose and average concentration for LLRD
•Equilibrium equivalent concentration for Radon (Rn-222) daughters
•Equilibrium equivalent concentration for Thoron (Rn-220) daughters
If any of the user-adjustable thresholds is exceeded, audible and optical alerts are generated. Special
attention has been paid on quality assurance. Air flow and filter status are logged in parallel with the
radiation results. A complete energy spectrum is saved for each single sampling interval. The unit is
equipped either with a manually replaceable filter or with an automatic filter stepper drive resulting
in high reliability and low effort for maintenance.
The instrument offers various measurement cycles to fit for several applications. The configuration
and operation software package dCONFIG/dVISION will be delivered with the unit.
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The following picture shows the operational controls of the Aer 5400.
a) Signal lights
b) Air inlet
c) Door-lock
d) Push button to exit display standby
a
b
c
d
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a) Tube connection to pump or vacuum supply
b) Socket vor switch outputs related to alert signals
c) Buzzer
d) Fuse
e) Mains power connection
f) RS232 or RS484 connector
g) Optional sensors for CH4 und CO
2. Power supply
The unit is powered by mains power supply. There is an internal battery which ensures the operation
(several hours) of the electronics (not the pump) even if the power fails. The battery will be charged
as soon as the mains power is present. If the battery remains without recharging of longer periods, a
deep discharge prevention circuit will disconnect the entire electronics. Then, the display switches
completely off. After connecting the power supply it takes a few minutes to reach the battery voltage
threshold which is required to turn on the unit again.
3. Filter replacement and flow control
The aerosols are accumulated at a manually replaceable filter or at a filter tape which will be
positioned automatically above the air inlet of the instrument. The detector located above the filter
measures simultaneously the decay of collected activity. The stepper drive ensures that exhausted
filter pieces move in to the housing. Two optical sensors detect the end of the filter tape. A warn
signal will be generated but it remains a piece of filter for one more step.
The filter drive can be controlled by several events which can be defined by the configuration of the
instrument:
a
b
c
d
e
f
g
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•Exhausted filter (flow rate cannot longer maintained by the flow controller)
•Collected activity exceeds a pre-set limit
•Fixed period (e.g. each interval, each day)
In delivery state, the filter only will step in case of exhaustion. Please read chapter “User specific
settings” for more information regarding additional stepping conditions.
3. 1. Filter sealing mechanism
The filter sealing mechanism avoids the partial bypass of the air stream trough the filter. A soft
rubber sealing will be pressed onto the backside of the filter while sampling. As soon as the pump
stops, the filter sealing will be released (e.g. during automatic filter stepping). Please take care that
the rubber sealing (O-Ring) is always placed correctly in the notch of the filter holder. The filter
holder must be easily movable within the guideway.
3. 2. Replacing the filter
The measurement has to be stopped before changing the filter. The filter unit can be accessed
opening the door of the enclosure.
3. 2. 1. Filter replacement for instruments with filter cartridge
The picture below shows the filter unit with manually replaceable filter cartridge.
Unit with filter cartridge
1) Air inlet connection
2) Detector cap
3) Filter sealing plate
4) Filter cartridge
5) Filter support
6) Filter sealing mechanism
5
3
2
6
1
4
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The filter cartridge has to be pushed into the slot between filter-
support and filter sealing plate. The position of the cartridge is
locked by a small pin which also avoids wrong filter insertion. After
removing the pin, the filter cartridge can be pulled out and a new
one can be inserted. The positioning hole of the cartridge (picture
left) must be located at the left side. Plug in the pin again and
check if the cartridge is correctly locked.
3. 2. 2. Replacing the filter tape
The following pictures show the stepper drive with and without tube connector. Only manufacturer
specified, 66mm wide filter tapes must be used.
Stepper unit
1) Coil with fresh filter
2) Coil with exhausted filter
3) Filter tension
4) Filter support
5) Optical sensors
6) Encoder for filter stepping distance
7) Locking screws
8) Detector cap
9) Filter sealing plate
1
2
3
4
9
6
7
7
8
5
10
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10) Filter sealing mechanism
At first remove the both locking screws (7) from the axles. Now, both coils can be detached. The
empty fresh filter coil acts as new coil for the exhausted part of the filter. When inserting the coil,
take care for correct fitting of the tappet (A) at the axle and the slot (B) at the coil (picture below).
Attach the lock screws again after inserting the fresh filter coil too. Make sure that the fresh filter coil
can be turned without strain.
Now, the filter tape can be inserted as shown in the picture. Please take care for the correct
guidance. In case of a standard instrument with open face air inlet the access can be simplified by
removing the filter sealing plate (the plate can be shifted to left). In addition, the detector head can
be slewed sideward if the knurled screw to fix the swivel arm has been removed before. Feed the
filter tape into the slot between filter support (4) and filter sealing plate (9) in case of an instrument
with tube connector.
The filter has a smooth and a rough side. The smooth side must point
towards the detector head. Make sure that the tape runs at the outer
side of the both optical detectors (5). Check if the filter tape will be
tightened between coil and filter support by the filter tension (3). Fix
the end of the filter tape with a piece of duct tape at the empty coil
(pic. right).
Insert the filter sealing plate (9) into the notches of the filter support (4)
in case of a standard instrument. Shift it to the right to the final position
(centred with the filter support). Take care that the mark on the filter
sealing plate points in direction of the hatch.
Before starting an aerosol sampling use the cycle “Insert filter” to wrap the filter tape a few times
around the coil. This procedure shows whether the tape runs correctly through the stepper drive or
not. Finally, the front hatch can be closed.
A
B
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3. 3. Flow control
The air flow rate determines mainly the calibration factor of any aerosol monitor. A constant flow
rate ensures reliable results because not only the sampled volume but also the collection
characteristics do not underlie variations. For this reason, the air flow of the instrument is regulated
to the nominal flow rate set-point even if the filter becomes exhausted. If the flow regulator cannot
longer maintain the flow at the nominal rate, the filter will be stepped. This is always done
synchronously with the beginning of a new sampling interval. Filter exhaustion and flow rate will
appear later on in the stored data. There is also an indication when the filter was stepped.
The instrument uses a mass flow meter to measure and control the flow rate with respect to the set-
point using a proportional valve. As the result, the mass of sampled air remains stable even if the air
pressure changes.
The filter movement is controlled by the upper alert limit of the analogous input AIN2. The input
monitors continuously the control voltage of the pump regulator. If the control voltage reaches 80%
of its maximum, the filter will be moved. Therefore, the analogous input AIN2 must be activated
within any used sampling cycle. Take care for that when defining own sampling cycles.
Instruments with manually replaceable filters will activate the yellow signal light in case of an
exhausted filter.
ATTENTION: Do not change the set-point of the flow regulation without matching the aerosol
calibration factor!
3. 4. End of filter and protection of the stepper drive
The end of the filter tape will be detected by optical sensors. The one located in front of the air inlet
generates a warn signal (yellow light) as soon as the end of the filter has passed the sensor. A second
one is located in front of the encoder to stop the motor and the measurement. The warn signal is
controlled by the alert of the digital status input DIN1. This input must be activated for any used
cycle. Do not change the configuration of the DIN1.
A protection mechanism has been implemented which will protect the stepping motor against
damages. If it takes more than two seconds to move the filter over the required distance, the system
considers this condition as a serious error and stops the measurement. The motor signal is connected
to the digital status input DIN2, which measures the time span of motor operation. The input will
generate an alert if the pre-set period is exceeded. The alert results in the stopping of the whole
measurement. Due to this implementation, the input DIN2 must be activated for any used cycle. Do
not change the pre-set alert threshold (one second) in the configuration of DIN2.
4. Tube connector
Tubes, pipes or hoses must be elastically mounted at the connector. Do not transfer larger
mechanical forces from the pipes/tubes to the connection flange of the instrument. The connection
must be realised by a centring/sealing ring, a clamp and an adapter. The adapter must meet the
dimensions of the standard small vacuum flange KF16 (16mm inner diameter). Thera are many
options like hose adapter for hoses with 19mm inner diameter or tapered adapters for KF25 vacuum
systems (see pictures below).
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5. Data storage
All acquired data is saved on an internal SD memory card (2GB). Data stored on the card can be read
via PC either completely or for a selectable period (manual dVISION).
All measured values will be stored as a data record at the end of each sampling interval. Dependent
on the type of sensor, the record will contain also the minimum and the maximum of a value within
an interval in addition to the interval result. The instrument saves only raw data to guarantee
traceability for quality assurance. This raw data includes also entire spectra for each sampling
interval.
For online display as well as for later generation of time distributions in dVISION, the raw data will be
interpreted with respect to the recent instrument configuration. This procedure allows a simple
retrospective analysis of data, for example if dose coefficients needs to be changed by statutory
regulations.
6. Instrument operation by menus
The Aer 5400 is controlled by touch screen menus. The power consumption of the display as well as
the backlight is very high compared with the other electronics. Therefore, the display will be
switched off automatically after an adjustable period. The time span (max. 255 Seconds) can be set
by the instrument set-up function of the operation software. To activate the display, press the small
push button below the display. All other required inputs are realized by dynamic touch buttons on
the screen. The screen will show always the display page which has been selected before the display
was switched off. In case of a pending alert, the display turns on automatically.
6. 1. Main page
If the display wakes up the main page appears on the screen. In standby mode, this page shows the
instrument name, the name of the actual configuration (with the date of the last update) and the
selected measurement cycle. Touch the CYCLE button to call a list containing all pre-defined cycles to
select another cycle.
Now the measurement can be started by pressing the START button. It is necessary that a memory
card is inserted and a valid cycle has been selected before. All information about the status of
sampling is displayed during cycle execution:
•Date/time (with black background if the clock needs to be set)
•Name of the processed cycle
•Time span from the start of the whole sampling period (total sample time)
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•Time span from the begin of the running interval
•Number of the executed step and step count of the running cycle
•Remaining data memory (number of data records which can be stored)
Several buttons are present at the main page to enable the access to various display pages. It is
possible to show recent readings, data already stored on memory card, component configuration etc.
The cycle execution can be stopped by the button STOP.
6. 2. Module information and options
These pages show the module information as well as the actual setting of the module options. The
menu can be called from the main menu by touching the INFO button. Use the TOGGLE button to
toggle between the several pages.
Module information:
•Software version
•Serial number
•Date of manufacturing
•Date of the last software update
Options with TOGGLE button:
•Pre-set start time if the option “Synchronized start” is enabled
•Operation mode and time scheduling of the clock switch
Use the BACK button to return to the main menu or the CONFIG button to show the actual
configuration of the various components.
6. 3. Component configuration
This menu shows the actual settings of the configuration parameters of each component. The user
can check them for validity but it is not possible to make any changes. Components can be selected
by the buttons NEXT and LAST. If not all parameters can be shown on one page, the others are
accessible using the TOGGLE button. Back to the main menu by pressing BACK button.
6. 4. Selecting the cycle
This menu allows the selection of the sampling cycles which have been transferred to the instrument
before. A touch sensitive list with the names of all available cycles appears after calling from main
menu by the button CYCLE. If more than five cycles have been stored, the list can be scrolled by the
TOGGLE button. A touch at the desired cycle name will select the cycle for execution. Touch the
BACK button to return to the main menu without a new selection. There are a number pre-defined
cycles available in delivery state:
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"1 min“/"5 min“/"15 min“/"1 hour“:
Measurement cycles with 1, 5, 15 or 60 minute sampling interval. Longer
intervals resulting in lower detection limits while shorter intervals give faster
response in case of detected activity. To optimize both parameters for your
application use the table with the detection limits stated in the data sheet.
"Alert test“: Test of all available alert signals.
"Insert filter": Steps the filter two times
“Detector test”:Measurement cycle without pumping. Alpha/Beta calibration sources may be
inserted for function test
6. 5. Recent readings display
This page is only available if a cycle is in progress. Use the button RECENT to call the recent readings
page from the main menu. The results are updated once per second to show the actual sampling
results. The display shows only data of components which are used and activated within the
executed cycle. To select the different components for display, the buttons NEXT and PREVIOUS
must be used. The order of components is defined by the order of component indexes (see appendix).
The name of the selected component appears in the headline of the screen. Some components
calculate more than one result from the acquired basic data. In that case, the TOGGLE button toggles
between the various results. To return to the main page touch the BACK button.
6. 6. Displaying the data stored at the memory card
If available, all data stored data at the memory card can be displayed. This page can be called from
the main page by the INTERVAL button even if the sample execution has been finished. The selection
of the components and results is implemented in the same kind like in the recent data menu. If a
component generates more than one result, an additional page with all results in parallel has been
implemented.
There is an additional navigation menu directly above the control buttons. These buttons are used to
select any data record within the card memory for display. The button in the middle selects the last
acquired record while the other buttons scroll the data memory forward and backward by a factor of
1 or 10. If the current cycle has been finished, the new data appear immediately on the screen.
The headline of the display shows the time stamp and if available the GPS coordinates of the selected
data record. To return to the main page touch the BACK button.
6. 7. Results shown on the display
Which results are presented on display depends on the definition of the used sampling cycle. In case
of the pre-defined cycles "1 min” …"1 hour” following results are available:
•Exposure, dose and average concentration for long lived Alpha emitters (only interval result)
•Exposure, dose and average concentration for long lived Beta emitters (only interval result)
•Radon (Rn-222) and Thoron (Rn-220) daughter product concentrations (EEC - only interval
result)
•Accumulated number of counts within the running interval for Alphas and Betas (only recent
results)
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•Gross count rate of the detector (separate comparator/counter module)
•Measured air flow rate
•Filter exhaustion
•Filter movement
•Temperature, humidity and barometric pressure(internal sensors)
•Charge status of the internal battery
•Dose rate for versions with additional GM tube or NaI detector
•Status of alert signals
7. Instrument set-up
These options can be adjusted by the operation software dVISION (please refer software manual).
7. 1. Clock switch
The integrated clock switch is internally connected to the input of the filter stepper. Please read the
chapter "User specific settings" how to use this feature for periodical filter movement. If the clock
switch is not used, it should be deactivated.
7. 2. Synchronized start of a measurement
Sometimes it is required to synchronize the sampling points of several instruments at different
locations. This can be done easily by the synchronized start capability of the instrument. Select the
cycle which shall executed from the cycle selection menu. Use dVISION to set the day time when the
cycle shall start. Check out if all instruments which have to be synchronized are set to the same time
base.
7. 3. Display standby
The display is switched off after a certain period to save power. The period counts from the moment
of the last touch to any of the soft buttons and may be set to a value between 1 and 255 Seconds.
8. Alert functions
Several types of alerts can arise while the unit is in operation. In parallel to the radiometric measures,
flow rate and filter contamination are monitored continuously. All alert thresholds are adjustable by
the user. It is also possible to disable one or more alerts. These settings can be done with the PC
configuration software dCONFIG.
The instrument is equipped with a signal tower (on top) with green, yellow and red lights. An acoustic
alert generator (rear) will be activated always together with the red light. Additionally to the optical
and acoustic signals, a touch button with an alert message appears at the screen. Touching the
button leads to a list containing all pending alerts. The alert list has to be confirmed by pressing the
CONFIRM button. The behaviour of the signal devices can be configured by the user for each alert
source independently. Two options are available:
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„Disable auto alert reset“
X
Signal devices will be switched off after the user confirms the
alerts by the associated menu function.
-
Signal devices will be switched off if the alert situation is no longer
present.
„Alert confirmation“ *)
X
The alerts appear in the menu list for confirmation.
-
The alerts do not appear in the menu list for alert confirmation.
*) If “Disable auto alert reset” is activated, the alert always appears in the menu list independent on
status of “Alert confirmation”.
After delivery, following alerts are pre-defined:
Alert source
Signal/check period
Pre-set threshold
Displayed phrase
Alpha dose
Red/Interval
> 2.5DACh
Aerosols
Beta dose
Red/Interval
> 2.5DACh
Aerosols
Flow rate
Yellow
< 15Lpm
Flowmeter
Filter stepping drive
(optical sensor)
Yellow
> 5s
Filter status
Filter stepping drive
(Motor signal)
Stop sampling
> 1s
Motor
The green light signalizes the proper operation of the instrument and will light only if sampling is
started. The configuration procedure for alerts will be explained in the chapter “User specific
settings”.
9. Gamma background compensation for the beta channel
Increased background radiation results in an increased count rate for betas. The reason is the
generation of conversion electrons by interaction of gamma quants with matter (e.g. detector
housing). These conversion electrons cannot be distinguished physically from the electrons emitted
by the collected aerosols. Thus, the instrument would show a beta exposure even if no air-born
aerosols are present. This “virtual” exposure disappears as soon as the instrument leaves the gamma
radiation field while the real collected filter activity cannot decrease.
9. 1. Static gamma background compensation
The standard instrument offers the possibility of static background compensation if the gamma
radiation field on site is known (work place). The best way is to measure the background count rate
directly with the instrument (sampling without pump). Then, the achieved value can be set as one
configuration parameter using the configuration software dCONFIG. The background count rate can
also be estimated if the local dose on site is known. For a natural radiation field, the following
formula may be used:
Background count rate = 250cpm/(µSv/h) * Dose rate (µSv/h)
The pre-set background count rate will be subtracted from the beta gross count rate, taking the
statistical fluctuations in consideration. If the unit with pre-set background is operated in areas
without gamma radiation, the configuration needs to be changed again. Otherwise, the detection
limit would be increased.
To set the background count rate see the chapter "User specific settings“.
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9. 2. Dynamic gamma compensation, dose rate measurement
9. 2. 1. Dynamic gamma compensation
Instrument versions with the option “G” are equipped with a second detector with identical
geometry and orientation for dynamic compensation of the gamma background radiation. An
aluminium absorber between the detectors avoids the detection of beta activity by the
compensation detector which has been collected on the filter. The beta count rates generated by
gamma background are expected to be similar for both detectors. Because the measurement
detector counts the sum of real collected beta activity and gamma induced beta activity while the
compensation detector counts only gamma related activity, the collected filter activity can be
obtained by subtraction of both detector signals.
Directed or in-homogeneous radiation fields (e.g. sources very close to the detectors) result in
differences between the gamma related count rates of both detectors. For incidence angles more
than ±30° related to the detector surface a significant over- or under-compensation will appear. This
will result either in an increase of the detection limit or in the detection of a not really present beta
activity. The configuration of the instrument allows the compensation of this difference by an
additional factor:
RN beta = RMD –K * RCD
•RN beta count rate of real beta activity collected on the filter
•RMD gross count rate of the measurement detector
•RCD count rate of the compensation detector
•K correction factor
To check if such conditions are present and to determine the correction factor K, a test measurement
without filter activity (RN beta = 0; new filter, pump off by disconnected mains power plug) should be
carried out. The count sums per interval are available in the spectrum view of dVISION after reading
them from the instrument (“Total Lo-E”= measurement detector, “Gamma background”=
compensation detector). The correction factor K can be determined by the simple formula
K = NMD / NCD
To obtain a sufficient statistical uncertainty, the count sum of each detector should be more than
10,000 counts (can be achieved also by adding of a few intervals). The calculated correction factor
(called as “Ratio Gamma Filter/Compensation” in the parameter table of the spectrometer
configuration) can be transferred to the instrument (see chapter “User specific settings”).
After delivery this factor can be slightly different from one due to slight differences of the beta pulse
threshold of both detectors.
9. 2. 2. Measurement of local dose rate
The count rate of the compensation detector is simultaneously used to determine the local dose rate.
The counter channel (CNT1) is configured in the manner that an average dose rate will be calculated
beginning at the start of the current interval. Thus, the statistical variance will be reduced with
advancing interval.
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10. Natural Uranium separation
From radiation protection point of view, it makes sense to distinguish between the isotopes of the
natural U-238 decay chain (Unat) and others. The dose coefficient (respective DAC values) for Unat is
much lower than for Plutonium while the natural Thorium decay chain includes nuclides with dose
coefficients similar to Plutonium. In many mines and Uranium facilities, Unat is the single carrier of
LLRD activity.
The separation algorithm uses the circumstance that the maximum emission energy of the whole Unat
decay chain is about 4.7MeV. All nuclides or decay chains with higher dose coefficients emit their
alpha particles with energies above 4.7MeV. That means, if some LLRD activity appears in the energy
region above 4.7MeV, we can assume that nuclides with high dose coefficients are present. In this
case, the Plutonium dose coefficient will be applied to calculate the dose from the measured
exposure - otherwise the instrument applies the one for Unat. In both cases, the presented dose value
covers the whole LLRD activity even if a mixture of Unat and other nuclides has been collected. This
implementation may result in a dose overestimation for such situations.
The configuration of the instrument allows the definition of two separate dose coefficients for Unat
and Plutonium. If a user knows that only Unat or only Plutonium (or other) is present at the place of
operation, both coefficients could be set either for Unat or Plutonium.
If the instrument applies the Unat dose coefficient, the phrase “*Unat*” appears on the display (if
alpha dose value is shown). Please note: Due to statistical deviations and Radon background
rejection, a misinterpretation of a single value (especially in the surrounding of the detection limit) is
possible. Therefore, the user should always take care for the frequency of “Unat”appearances during
sampling. Just one single “Unat” reading within a number of LLRD results indicates definitely a
statistical fluctuation.
11. Calculation of the average activity concentration
The LLRD activity collected on the filter is proportional to the exposure and finally to the dose.
Therefore, the exposure is the primary result for the calculation of the average activity concentration
by division by the exposure time. The accumulated exposure time remains in the memory even if the
measurement will be interrupted. The recently calculated result of the average concentration is
always related to the whole exposure period. It is necessary to make sure that filter activity and
exposure period are always consistent. Therefore, the exposure timer will be re-set after each filter
step. That means, a new exposure period starts automatically with a filter movement. Triggering the
filter movement by a fixed (short) interval allows to measure actual concentrations. Please note that
the exposer time will be re-set also in case of power off/on using the key switch.
Please note that any presented result within the stored time distribution represents always the
average concentration of the period from the last filter movement to the related time stamp. The
result does not represent the actual concentration in that moment.
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12. Operation conditions
The instrument has been designed as a robust unit for portable use in nuclear and mining facilities.
Because of the sampling method, the detector head is directly exposed to the ambient conditions.
Therefore, the user should mind a few limitations.
•The temperature range from 0°C to 50°C should not be exceeded. An extended range can be
provided on request.
•Condensation of water must be avoided. After strong temperature changes (moving a cold
unit in warm environment) the instrument should be tempered for a while before using.
•Avoid beats onto the enclosure or detector head. The microphonic (piezo-electric) effect
generates electronic signals similar to decay events. The instrument is equipped with
dynamic shock suppression (electronic pulse shape analyses). Frequently shocks or
permanent vibration must still be avoided.
•Do not use any strong source of electro-magnetic fields in the immediate vicinity of the
detector head (e.g. mobile phones, Wi-Fi adapter/router).
•The instrument should never be operated without filter. Particles in the air loop resulting in
an increased abrasion of the pump.
13. Communication with a PC
The instrument is equipped with an internal USB interface for service purposes which is located
directly at the cover of the display unit. A nine-pin SUB-D connector at the bottom of the enclosure is
configured either for RS232 or RS485 (bus) interface depending on customers request. Both
interfaces can be used for all required data transfer from and to the instrument. If the USB interface
is connected, the RS232 interface will be disconnected (USB priority). The standard transfer rate is
9600 baud. If no sampling is in progress, the transfer speed can be increased significantly using the
"Card Reader" function. Push simply the touch area at the top of the main menu to enter this mode.
Please make sure that the card reader mode has been selected in dVISION too. Increased transfer
speed is only available for the USB interface.
The instrument offers a simple proprietary communication protocol which allows the user to access
the unit by own software solutions. For more detailed information please contact the manufacturer
or your retailer.
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14. Alert outputs
The instrument offers in total four alert outputs which are accessible through a circular connector at
the bottom panel of the enclosure. Three of the outputs are paralleled with the green, yellow and
red signal lights. That means, if one of the signals is activated a 12V control voltage will be applied
the related pin of the connector. The voltage may be used for a second signal light or other alarm
devices. Make sure that the current drawn from this outputs will be not higher than 100mA each.
The fourth output (DOUT3) offers potential-free contacts (Opto-MOS relay, max. 24V/0.4A). The
output can be used as a measurement cycle-controlled switch to control external equipment.
1
DOUT3 contact A
2
DOUT3 contact B
3
GND –signal ground
4
Signal “green”
5
Signal “yellow”
6
Signal “red”
7
Not connected
View at the connector
15. User specific settings
The instrument is based on the DACM platform, which provides flexible tools for custom specific
configurations. Each of the functional blocks, the so-called components, can be configured and
controlled separately using the PC software dCONFIG. Changing the configuration requires caution
and should be carried out by skilled persons only (administrator). Erroneous settings may result in a
male function of the instrument. Before changing anything, the operator should read the recent
configuration from the unit and save it on PC as configuration file. If necessary, this file can be
written back to the unit in case of trouble. Each component offers a specific configuration window in
dCONFIG for all available configuration parameter. The dCONFIG software manual informs of the
procedures to access the various configuration windows.
15. 1. Changing the alert settings for radiometric measures
Configuration window of component SPEC1
It is possible to define two independent alert levels. The threshold values must be entered into the
edit fields “Alarm 1 threshold” and “Alarm 2 threshold”. Several measures can be assigned to each of
the alert levels. These measures must be selected by marking the items within the list boxes “Alarm 1
source” and “Alarm 2 source”. The threshold level is always related to the physical unit of the
selected measure. For example, one could use the first threshold for the dose value and the other
one for Radon and Thoron concentration. In delivery state the alert is routed to the red signal light
(switch output DOUT4). To disable the alert function, select the item “inactive” from the list.
1
2
34
7
6
5
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15. 2. Changing the threshold level for the count rate
Configuration window of components CMP1 and CNT1
Two components, a voltage comparator (CMP1) and a counter input (CNT1) are used for gross count
rate measurements. The comparator output is internally connected to the counter input. A digital
pulse will appear at the counter input if the detector signal exceeds the threshold level of the
comparator. Because the height of the detector signal is related to the emission energy of the decay
event, the count rate contains only events above the energy corresponding with the threshold. This
allows the configuration of the counter either as gross alpha or total event counter. The threshold
level can be adjusted in the component window of CMP1, edit field “Threshold voltage”. To count
alpha and beta decays, enter 100mV, for alphas only, enter 350mV.
The alert threshold for the count rate can be configured in the configuration window of component
CNT1 (“Alarm if count rate becomes higher than”). The alert is disabled in delivery state (“inactive”
selected from the list box “Alarm index higher than”).
15. 3. Adjusting parameters for the gamma background compensation
Configuration window of component SPEC1
Instruments without dynamic gamma compensation
To enter the background count rate, the parameter “Fixed Background Count Rate” is available in the
table “Calibration constants”. The unit is cpm (counts per minute).
Instruments with dynamic gamma compensation (double detector)
The parameter table contains in that case the item “Ratio Gamm Filter/Compensation” instead of the
“fixed background Count Rate”. This parameter can be calculated according the chapter ”Dynamic
gamma compensation”.
15. 4. Changing units (US/SI) and dose coefficients
Configuration window of component SPEC1
The activity and dose results can be presented either in traditional US units or in international SI units,
depending on the selection in the list box “Unit scheme”. Changing the unit scheme requires always
the changing of the dose coefficients. Dose coefficients must be stated in relation to the selected
dose unit. That means for US unit scheme, the unit of dose coefficients is DACh/(Bqh/m³). The dose
coefficient unit in case of SI unit scheme is µSv/(Bqh/m³). The values can be entered into the table
“Calibration constants”. There, the parameters "Dose Coefficient Alpha", "Dose Coefficient Beta" and
“Dose coefficient Unat” are available.
The factory-set coefficients are adjusted with respect to the normative 10CRF20 of the US-DOE.
Because there are specific laws for various applications and countries, the user must change these
constants in accordance with the local regulations.
Coefficient for
in DACh/(Bqh/m³)
in µSv/(Bqh/m³)
10CRF20
10CRF835
German StrlSchV §§63 u. 63a Anlage 3
Plutonium
9,01
5,4
192
Natural Uranium
1,35
0,34
76,8
Strontium
0,014
0,0039
0,84
Table of contents
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