Saphymo Minitrace csdf User manual

www.saphymo.de

Manual

Type CSDF

Instruction Manual for MiniTRACE CSDF

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0 Contents

0Contents...............................................................................................................2

1Foreword ..............................................................................................................4

2Description ...........................................................................................................5

2.1 Display ..........................................................................................................5

2.2 Alarm function ...............................................................................................6

2.3 Operation Modes of the MiniTRACE CSDF ..................................................6

2.4 Measurements...............................................................................................9

2.4.1 Information for your own radiation protection.........................................9

2.4.2 Examples of natural radionuclides in food and limits for artificial

radionuclides in food.............................................................................................9

2.4.3 Measurement tasks for the MiniTRACE CSDF ....................................10

2.5 Accessories for measuring..........................................................................21

2.5.1 MiniTRACE function test using a small test source..............................25

2.6 The design of the instrument.......................................................................27

2.7 Protective rubber casing..............................................................................28

3Standard calibration for Co-60 and Cs-137 ........................................................29

4Maintenance and care........................................................................................30

4.1 Changing the batteries ................................................................................30

4.2 Cleaning (Decontaminating) MiniTRACE CSDF .........................................30

4.2.1 Removing the grid................................................................................30

4.2.2 Cleaning the case ................................................................................31

4.3 Technical properties and functions..............................................................31

4.3.1 Calibration factors and efficiency .........................................................33

5MiniTRACE user software ..................................................................................34

6Warranty information ..........................................................................................35

7Appendix ............................................................................................................36

7.1 DKD certificate for the Co-60 radiation emitter............................................36

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Figures

Figure 1: Information shown on the display .............................................................5

Figure 2: MiniTRACE CSDF display – alarm is activated ........................................6

Figure 3: Using the mode button to select an operation mode ................................8

Figure 4: Opened protective lid..............................................................................10

Figure 5: Display in dose rate mean mode ............................................................11

Figure 6: Display in cps mean mode......................................................................12

Figure 7: Measuring device for wipe tests .............................................................15

Figure 8: Wipe test measurement..........................................................................16

Figure 9: Counting up measurement .....................................................................17

Figure 10: Food measurement flow chart ................................................................18

Figure 11: Food measurement ................................................................................18

Figure 12: Display for background (control) measurement in the “Food” menu.......19

Figure 13: Result display for background (control) measurement

in the “Food” menu .................................................................................19

Figure 14: Display in the “Food” menu.....................................................................20

Figure 15: Result display in the “Food” menu..........................................................20

Figure 16: Food measurement kit (See Chapter 2.4.3.7).........................................22

Figure 17: Accessories for the wipe test (See Chapter 2.4.3.5.4)............................22

Figure 18: Belt case.................................................................................................22

Figure 19: Transparent plastic pouch ......................................................................23

Figure 20: Transportation box..................................................................................23

Figure 21: Peli Box ..................................................................................................24

Figure 22: Emergency case.....................................................................................24

Figure 23: Test source (see Chapter 2.5.1).............................................................25

Figure 24: Communication kit with MiniTRACE .......................................................25

Figure 25: Dose rate of the test source....................................................................26

Figure 26: “CMean” menu........................................................................................26

Figure 27: Side view ................................................................................................27

Figure 28: Front view ...............................................................................................27

Figure 29: Protective rubber casing.........................................................................28

Figure 30: Changing the batteries ...........................................................................30

Figure 31: Removing the grid (part 1)......................................................................30

Figure 32: Removing the grid (part 2)......................................................................31

Figure 33: Energy response of the MiniTRACE CSDF (based on Cs-137,

with lid closed and GM tube energy compensated)................................32

Figure 34: Energy response of the MiniTRACE CSDF

(with open lid, NOT energy compensated) ............................................32

Tables

Table 1: Status reports in the 5-digit alphanumeric portion of the LCD display ......5

Table 2: Overview of measurements....................................................................10

Table 3: 1-Sigma statistical uncertainty with different background dose rates .....18

Table 4: List of accessories..................................................................................21

Table 5: Technical data ........................................................................................31

Table 6: 4 π-Efficiency [Bq] MiniTRACE CSDF for different radionuclides..........33

Table 7: Calibration factors and efficiency [Bq/cm

2

] MiniTRACE CSDF

based on ISO 7503-1 .............................................................................33

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1 Foreword

Thank you for purchasing the MiniTRACE CSDF contamination and survey meter. In order to

gain a better understanding of its functions, please take a little time to read through this

instruction manual.

MiniTRACE CSDF is a multifunctional contamination and survey meter that has been

developed by Saphymo GmbH in Frankfurt/Main.

MiniTRACE CSDF is especially suited for use in nuclear plants, reprocessing sites, research

centers, hospitals, and for occupational groups such as the armed forces, police or fire

department.

MiniTRACE CSDF offers ease of use. It is the ideal instrument for identifying possible

contamination simply and quickly (values are displayed in Bq, Bq/cm

2

or cps, depending on

the mode). You can also use it as a multifunctional survey meter. With its energy compen-

sated Geiger-Mueller pancake detector you can determine the ambient dose rate equivalent

(H*(10)), displayed in µSv/h. The device is also suitable for food measurements and wipe

tests.

The MiniTRACE CSDF enables the user to select different measurement cycles for the count

up mode directly on the instrument or to choose between different radionuclides.

Additionally, the optional MiniTRACE software enables you to set the alarm thresholds or

calibrate the instrument (see additional software manual).

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2 Description

2.1 Display

The display is composed of a 6-digit 7-segment display for the measurement results as well

as a 5-digit alphanumeric display. The MiniTRACE CSDF shows the unit in “cps”, “Bq”,

“Bq/cm

2

”, “µSv/h”, “counts” and Bq/l.

Note: The dose rate displayed is energy compensated to the ambient dose rate

equivalent (H*(10)). To measure the dose rate correctly the lid must be closed.

The following status reports can be displayed on the MiniTRACE CSDF display:

Bq/cm2

se c

µSv/h

Figure 1: Information shown on the display

Display Acoustic

Alarm

Note

Unit: Bq,

Bq/cm

2

, cps,

µSv/h or Bq/l

-

Available measurement units

CAPT Yes

Detector error:

If the detector is defective, the message “CAPT” will appear in the display.

The warning is triggered when the detector fails to send an impulse for a

period of 40 seconds.

SAT Yes

Saturation:

If the measurement range is saturated (value out of range), the message

“SAT” will appear in the display. This message will remain until the

measurement area is no longer saturated.

No

Battery warning:

If the battery symbol appears in the display, the battery should be

changed. The instrument can still be operated for 10 hours after the battery

symbol appears.

E < % No

Statistical uncertainty in the mean value mode:

The mean value is determined for a user-defined period. The default is set

to 3 Sigma and adjustable by software.

Table 1: Status reports in the 5-digit alphanumeric portion of the LCD display

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2.2 Alarm function

One alarm threshold for the MiniTRACE CSDF can be set via software for the following units:

•Alarm 1: Dose rate mode in µSv/h (default: 20 µSv/h)

•Alarm 2: Counts in cps (default: 0, meaning deactivated)

•Alarm 3: Activity in Bq (default: 60 Bq)

•Alarm 4: Surface contamination in Bq/cm

2

(default: 4 Bq/cm

2

)

The alarm can be activated or deactivated using the mode button (See Figure 3). If you

would like to activate the alarm, go to the “AL oN” menu and wait three seconds. If you would

like to deactivate the alarm, go to the “AL oFF” menu and wait three seconds. The value of

the alarm threshold is shown on the display.

Figure 2: MiniTRACE CSDF display – alarm is activated

Note: After one of the operation modes has been selected, the status (here alarm

activated) and the value (here 20.00 µSv/h) of the alarm setting are displayed.

2.3 Operation Modes of the MiniTRACE CSDF

The following measurement modes can be set:

•Rate mode (RATE): Dose rate in “µSv/h”. To use this function properly the lid must

be closed. The results will then be energy compensated to the ambient dose

equivalent (H*(10)).

•Rate mean mode (RMEAN): Dose rate mean value in “µSv/h”. To use this function

properly the lid must be closed. The results will then be energy compensated to the

ambient dose equivalent (H*(10)). To reset the calculated mean value, press the

mode button. This function is used to gain measurement results of a higher precision

in a stable radiation environment. The longer the measurement, the higher the

accuracy.

•CPS mode (CPS): Count rate in “cps”.

•CPS mean mode (CMEAN): Count rate mean value, no unit is displayed. To reset

the calculated mean value, press the mode button. This function is used to gain

measurement results of a higher precision in a stable radiation environment. The

longer the measurement, the higher the accuracy.

•Bq mode (BQ): Activity in “Bq”. You can use the mode button to choose between

different radionuclides (along with their appropriate calibration factors; 4π-calibration).

See Table 6.

•Bq/cm^2 mode (BQCM2): Surface contamination in “Bq/cm

2

”. You can use the mode

button to choose between different radionuclides (along with their appropriate cali-

bration factors). See Table 7. Calibration based on ISO 7503-1.

Indicates

whether the

alarm is

activated

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•Count up mode (CNTUP): Pulses are counted during the selected time interval. The

interval can be set via the mode button. Possible intervals are: 60, 120, 300, 600,

1,800 and 3,600 seconds.

•Food mode: Contamination of food in “Bq/L”.

Note: If you turn on the instrument the last selected operation mode is still activated.

The default calibration factors are set for a distance of 3 mm between grid and

surface. For more details see Chapter 3.

The MiniTRACE CSDF is UNABLE to identify radionuclides!

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press I-buttonpress mod e button

activate

RATEmode

turn on

pressI-button

Rate mode

Rate mean mode

(E < XX % in the displa y)

CPS mode

CPS mean mode

(E < XX % in the display)

Bq mode (BQ)

Bq/cm^ 2 mode (BQCM2)

Count up mode (CNTUP)

Food

Speaker on (SP ON)

Speaker off (SP OFF)

Ala rm (ALON)

Ala rm off (ALOFF)

OFF

press

mode button

press

mode button

press

mode button

press

mode button

press

mode button

press

mode button

press

mode button

press

mode button

press

mode button

press

mode button

press

mode button

wait 3 sec.

unit µSv/h

alarm on/off

alarm threshold

in the display

activate

RATEm ean

mode

wa it 3 sec.

reset mean value

press

mode button

activate

CPSm ode

wa it 3 sec.

unit CPS, a la rm on/off

alarm threshold

in the d isplay

activate

CPSmea n

mode

wait 3 sec.

Reset mean value

press

mode-button

activate

Bq mode

wa it 3 sec.

unit Bq, used rad ionuc lude

in the display

press

mode button

select

radionuc lide

wa it 3 sec.

activate

Bq/cm ^ 2

m ode

wa it 3 sec.

unit Bq/c m^ 2, used ra dionuclude

in the d isplay

press

mode button

select

radionuc lide

wa it 3 sec.

activate

count up

m ode

wa it 3 sec.

measurement time

in the display

press

mode button

selec t measurement cycle

(60, 120, 300, 600, 1800, 3600 sec .

wait 3 sec.

Reset

measurement

cyc le

press

mode-button

Reset mean value

press

mode button

See flowchart in c hap ter “Food m easurement”

wa it 3 sec.

activate

sp eaker

wa it 3 sec.

deac tivate

speaker

wa it 3 sec.

activate

alarm

wait 3 sec.

Dea c tivate

alarm

wait 3 sec.

Note:

a la rm threshold can be set via MiniTRACE Software)

pressI-button

(2 times short)

pressI-button

(2 times short)

pressI-button

(2 timesshort)

pressI-button

(2 times short)

press I-button

(2 times short)

turn off

instrument

pressI-button

IR

press

mode button

activate

IR-c omm unic ation

wa it 3 sec.

pressI-button

(2 times short)

Figure 3: Using the mode button to select an operation mode

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2.4 Measurements

2.4.1 Information for your own radiation protection

•Protect yourself from an unnecessary dose. The easiest way is to reduce the length

of exposure.

•

Increasing the distance reduces the dose due to the inverse square law.

•Radiation doses should all be kept as low as reasonably achievable.

•Protect yourself against contamination by using the rubber gloves and the tweezers.

•Do not touch the surface with your hand or the MiniTRACE to prevent the spread of

contamination.

•Avoid incorporation and inhalation. Incorporation or inhalation of radioactivity is much

more dangerous than contamination of the skin.

For more information see:

Euratom: http://www.euratom.org

IAEA: http://www.IAEA.org

WHO: http://www.who.int

2.4.2 Examples of natural radionuclides in food and limits for artificial

radionuclides in food

In all foods you will find some natural radionuclides, mainly the long-lived K-40 and the long-

lived radionuclides of the uranium-radium and thorium decay series. Alongside the nutrients

necessary for growth, plants and animals also absorb radionuclides, due to their similar

chemical properties. The level of radionuclide concentration in food is determined by the

radioactivity of the source media used (soil, water), the availability of nutrients and other

substances from soil and water and other conditions at the location of the plant or animal

production.

Higher radionuclide concentrations are found in the livers and kidneys of animals (in

comparison to the meat) due to their function as "pollution filters" as part of the metabolism of

various elements, above all radionuclides.

Some interesting numbers (literature source BfS/Germany):

•Natural K-40 in:

ofruits: approx. 50 Bq/kg

omilk: approx. 50 Bq/l

omeat: approx. 100 Bq/kg

opeas/beans: approx. 380 Bq/kg

oman: approx. 40-60 Bq/kg

The national threshold for food differs from country to country.

In Germany the following thresholds apply: Regulation 1707/86 dated 30.5.86

(2) for:

•Total Cesium 370 Bq/kg for milk and baby food

•600 Bq/kg for other food.

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More information can be found at:

Japan:

http://www.mhlw.go.jp/english/topics/foodsafety/index.html

http://www.mhlw.go.jp/english/topics/foodsafety/dl/110318-1.pdf

Germany:

http://www.bmu.de/atomenergie_sicherheit/doc/47216.php

2.4.3 Measurement tasks for the MiniTRACE CSDF

With the MiniTRACE CSDF you choose between the following operation modes:

Mode Unit Lid open Lid closed

Dose rate H*(10) (Menu RATE)

Preferred direction observed, see Figure 27

µSv/h - X

Dose rate mean value H*(10) (Menu RMEAN)

Preferred direction observed, see Figure 27

µSv/h - X

Count rate (Menu CPS) cps X (α, β, γ) X (γ)

Count rate mean value (Menu CMEAN) cps X (α, β, γ) X (γ)

Activity (Menu BQ) Bq X (α, β, γ) Not

recommended

Surface contamination (Menu BQCM2) Bq/cm

2

X (α, β, γ) Not

recommended

Count up (Menu COUNTUP) cps X (α, β, γ) X (γ)

Food (Menu FOOD) Bq/l - X (γ)

Table 2: Overview of measurements

Note: Measurement results in the “Surface contamination” (Bq/cm

2

) mode are based

on ISO 7503-1. For the activity mode (Bq) we have calibrated the instrument in

a 4 πgeometry.

The internal calibration factors are default values and not individually calibrated.

Figure 4: Opened protective lid

Protective

grid

Pancake Geiger-

Mueller detector

behind the grid

Lid open,

includes serial

number, infor-

mation and

energy filter

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2.4.3.1 Ambient dose rate equivalent measurement – H*(10) in

µSv/h

Select the “RATE” menu by using the mode button. Once “RATE” is displayed, wait 3

seconds; the menu will start automatically. For further details see Figure 3.

This mode reacts very quickly to changes in the radiation level.

To determine the ambient dose rate equivalent (H*(10)) correctly, the lid must be closed!

When the lid is open, the ambient dose rate equivalent is NOT calculated correctly.

The value is given in µSv/h.

Note: The ambient dose rate equivalent gives you important information for radiation

protection.

Dose limits for radiation protection in Germany are (in 2011):

•Population 1 mSv/a

•Professionally exposed persons: 20 mSv/a

2.4.3.2 Mean value of the ambient dose rate equivalent – H*(10) in

µSv/h

Select the “RMEAN” menu by using the mode button. Once RMEAN is displayed, wait 3

seconds; the menu will start automatically. For further details see Figure 3.

We recommend this menu if the ambient dose rate equivalent is “stable” in your environment

and you would like to determine the dose rate more precisely. The longer the measurement,

the higher the accuracy. This mode does NOT react to rapid changes in the radiation level.

To determine the mean value of the ambient dose rate equivalent (H*(10)) correctly, the lid

must be closed! When the lid is open, the mean value of the ambient dose rate equivalent is

not calculated correctly. The value is given in “µSv/h”. In the top left corner of the display,

statistical uncertainty is given. By default a statistical uncertainty of 3 sigma is calculated.

You can change the sigma value using the MiniTRACE software. For more details see the

software manual.

Note: The ambient dose rate equivalent gives you important information for radiation

protection.

Figure 5: Display in dose rate mean mode

2.4.3.3 Count rate measurement in cps

Select the “CPS” menu by using the mode button. Once “CPS” is displayed, wait 3 seconds;

the menu will start automatically. For further details see Figure 3.

This mode reacts very quickly to changes in the radiation level.

With this menu you can check the contamination of a surface, for example. The value is

given in counts per second (cps). With the lid closed only γ-radiation is measured. If you

open the protective lid (material: aluminum, thickness: 1 mm) you will see the Geiger-Mueller

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pancake detector. With the lid open you can measure α-, β- and γ-radiation. This detector is

very sensitive and protected by a grid.

Note: All given measurement values are gross values. This means that background

values are NOT subtracted.

Basically you should do contamination measurements (i.e. on surfaces) in 2 steps:

1. Measurement with lid closed to determine the γ-contamination

2. Measurement with lid open to determine the α-, β- and γ-contamination

To determine the β-component another step is necessary:

3. Measurement with lid open and a sheet of paper on the detector. Subtract the value

from measurement 3 from measurement 1; the result contains the β-contamination.

To determine the α-component another step is necessary:

Measurement with lid open and a sheet of paper on the detector. Subtract the value from

the result without and with paper and you will get the α-contamination.

To determine the α- and β-components another step is necessary:

Subtract the value from measurement 2 from measurement 1; result contains the α- and

β–contamination.

Note: For a higher precision of the measurement result the radiation background has

to be measured first and then subtracted from the final result.

α–radiation can be shielded with a piece of paper.

β-radiation is almost completely shielded by closing the lid.

2.4.3.4 Mean value of the count rate in cps

Select the “CMEAN menu” by using the mode button. Once “CMEAN” is displayed, wait 3

seconds; the menu will start automatically. For further details see Figure 3.

With this menu you can check the contamination of a surface, for example. If the count rate

is “stable” in your environment and you would like to determine the count rate more precisely

you can use this menu. The longer the measurement, the higher the accuracy. This mode

does NOT react to rapid changes in the radiation level.

The value is given in counts per second (cps). In the top left corner of the display, the

statistical uncertainty is given. By default a statistical uncertainty of 3 sigma is calculated.

You can change the sigma value using the MiniTRACE software. For more details see the

additional software manual.

With the lid closed only γ-radiation is measured. If you open the protective lid (material:

aluminum, thickness: 1 mm) you will see the Geiger-Mueller pancake detector. With the lid

open, you can measure α-, β-, and γ-radiation. This detector is very sensitive and protected

by a grid. See also 2.4.3.3.

Figure 6: Display in cps mean mode

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2.4.3.5 Measurement of surface contamination

2.4.3.5.1 Measurement of the activity in Bq

With this menu you can check the contamination of a surface, for example, based on a 4 π-

calibration.

Select the “BQ” menu by using the mode button. Once “BQ” is displayed, wait three seconds.

You can select the radionuclide you would like to measure by pressing the mode button.

After additional three seconds, the display will indicate whether an alarm threshold has been

activated for the activity measurement. Then the measurement starts automatically. For

further details see Figure 3. The activity is given in “Bq”. See also 2.4.3.3, 2.4.3.5.32.4.3.5.4.

You can select the following radionuclides with the built-in calibration factors (4 π-

calibration):

•Am-241

•C-14

•Cl-36

•Co-60

•Cs-137

•Sr-90

•U-238

•User (see below)

If you would like to select another radionuclide, press the mode button once, wait three

seconds, and then select the radionuclide. The display will indicate whether an alarm

threshold has been activated for the activity measurement. The measurement will then start

automatically.

You can assign your own calibration factor for the radionuclide “User” using the software. For

further information see the software manual.

Note: MiniTRACE CSDF can not determine the radionuclide. Selection of the

radionuclide has to be done by the user.

2.4.3.5.2 Measurement of surface contamination in Bq/cm

2

With this menu you can check the contamination of a surface, based on ISO 7503-1

calibration. The measurement of the surface contamination can be done in two different

ways. For more information see Chapters 2.4.3.5.3 and 2.4.3.5.4.

Select the “BQCM2” menu using the mode button. Once “BQCM2” is displayed, wait three

seconds. You can then select the radionuclide you would like to measure by pressing the

mode button. After an additional three seconds, the display will indicate whether an alarm

threshold has been activated for the activity measurement. The measurement will then start

automatically. For further details see Figure 3. Activity is given in Bq/cm

2

.

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You can select the following radionuclides. Associated built-in calibration factors are based

on ISO 7503-1:

•Am-241

•C-14

•Cl-36

•Co-60

•Cs-137

•I131

•Sr-90

•U-238

•User (see below)

If you would like to select another radionuclide, press the mode button once, wait three

seconds, and then select the radionuclide. The display will indicate whether an alarm

threshold has been activated for the activity measurement. The measurement will then start

automatically.

You can assign your own calibration factor for the radionuclide “User” using the software. For

further information see the software manual.

Note: MiniTRACE CSDF cannot determine the radionuclide. Selection of the

radionuclide must be carried out by the user.

2.4.3.5.3 Surface contamination with a direct measurement

Select the “BQCM2” menu or “Bq” mode. For further details see Figure 3. To measure the

surface contamination with a direct measurement you will need to open the lid. With this

method you measure the nonadherent and adherent surface contamination.

With the lid open, move the detector slowly over the surface, without allowing the

MiniTRACE to touch the surface. We recommend activating the acoustic registration of

impulses (“SP oN” menu). If you find a contaminated area, position the MiniTRACE at this

point. The distance between the surface and the MiniTRACE grid should be as little as

possible; we recommend approx. 3 mm.

Before you start with this measurement you need to determine the background radiation and

subtract it from the later result. For further information see ISO 7503-1 or your national

guidelines.

Note: The closer you are to the surface, the better the results will be. Be sure not to

touch the surface with the MiniTRACE CSDF. In the event of contact, the

MiniTRACE CSDF could be contaminated and the contamination could be

spread.

2.4.3.5.4 Surface contamination with a wipe test

To work with this menu select “BQCM2” mode. For further details see Figure 3. The wipe test

is a common method for measuring surface contamination. It is an indirect measurement

technique; only nonadherent surface contamination can be determined. This test is useful if

external radiation levels are too high, if surfaces are inaccessible or if the radiation would not

be detectable. In these cases activity on the surface is sampled on wipe test smears. They

provide an efficient, convenient means of sampling contaminated areas with radioactivity on

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either wet or dry surfaces. Afterwards the activity on wipe test smears is measured with

MiniTRACE CSDF.

The surface contamination is measured in “Bq/cm²“ and it is proportional to the net counting

rate and a calibration factor. The calibration factor is a function of the instrument's efficiency

for the specified radionuclide, the area wiped, the source efficiency and the removal factor.

Frequently the removal factor is unknown.

Note: Use only the supplied measuring cup and holder. Otherwise the result will be

inaccurate.

Procedure:

•Perform a background measurement and go to the “BQCM2” menu.

•Take one wipe test sample from the filter roll by tearing along the perforation. Do not

disconnect the filter from the foil.

•Protect yourself against contamination by using the rubber gloves and the tweezers.

•Wipe very carefully with the supplied filter over the averaging area.

•In Germany the averaging area should not be larger than 100 cm

2

. Please check the

guidelines in your country.

•Put the filter in the filter cup with the side that is possibly contaminated facing up.

•Put the filter cup in the measurement device.

•Position the CSDF on the measurement device. The lid must be open.

•Now you can start the measurement.

•After measurement is done, remove the wipe test sample from the cup carefully, if

you have found any contamination.

•For the exact procedure see ISO 7503-1 “Evaluation of surface contamination” or

your national guidelines.

Figure 7: Measuring device for wipe tests

Wipe test

sample in the

measuring

cup

Measurement

device for

exact positi-

oning of

MiniTRACE

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Figure 8: Wipe test measurement

Calculation of the final result:

backgound

theoftotal

valuemeasuredvaluemeasuredcmBqvaluenet −=]/[

2

Note: To determine the background value put the CSDF in the measurement holder. It

is not necessary to use a new (uncontaminated) wipe test sample; put only the

measurement cup in the measurement holder.

Example:

Measurement result of the background: 5 Bq/cm

2

Measurement result of surface measurement: 105 Bq/cm

2

Net value = 105 Bq/cm

2

– 5 Bq/cm

2

= 100 Bq/cm

2

][

2

5.15]/[

2

cmareawiped

cmxcmBqvaluenet

resultFinal =

Example:

Net value = 100 Bq/cm

2

Wiped area = 100 cm

2

Area of the window of the GM-detector: 15.5 cm

2

/5.15

100

2

5.15/100 cmBq

cm

cmxcmBq

resultFinal ==

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2.4.3.6 Count up mode

To work with this menu select “CNTUP” mode. For further details see Figure 3.

This mode

is the summation of pulses at a predetermined time interval. The following time

intervals are available: 60, 120, 300, 600 (10 min.), 1800 (30 min.) and 3600 (60

min.) seconds. When you select the count up mode, the display will indicate which

measurement interval has been selected. To keep this measurement interval, wait

three seconds. To change the measurement interval, press the mode button. The

end of the measurement is indicated by an acoustic signal (beep).

Figure 9: Counting up measurement

This menu is very helpful in conveying to students an insight into the statistical correlations

between the radioactivity measurements.

2.4.3.7Food measurement

The instrument is calibrated to measure Cs-137 contamination in liquid or solid food. The

results are only precise if the food is contaminated with Cs-137 and when determined using

the procedure described here.

For more information about radionuclides in food and limits for radiation in various products

see Chapter 2.4.2.

To check radioactivity in food, only two steps are necessary:

1. Determination of the background radiation (control measurement)

2. Food measurement

All measurements must be carried out with the lid closed.

Note: Due to limited sensitivity the instrument is not suitable for verifying official limits

for baby food. With any measurement errors, the manufacturer cannot be held

responsible for any damage.

Sum of the

pulses

Remaining

measurement

time

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Page 18 08/2012

food mode

(Food)

activate

food

mode

wait 3 sec.

end of food m easurem ent

activate

control

result of the

measurement

after approx. 2 h.

starts autom.

dose rate < 300 nSv/h

press mode button

press

mode button

saved c ontrol measurement

in the memory is OK

no control measurement in the memory

or last measurement is > 300 nSv/h

dose ra te > 300 nSv/h

end off food mea surement

ac tiva te

food

result of the

measurement

after approx. 1.5 h

Figure 10: Food measurement flow chart

Note: You can change the duration of the background (control) measurement using

the MiniTRACE software. But note: the shorter the measurement, the higher the

uncertainty. If you work with a 2-hour measurement time, the result will contain

a 1-sigma uncertainty of 30 % at a background level of 0.1 µSv/h. Be sure to

use an area with a low radiation background, as the lower the background level

the more certain the result. If you do need to measure with a high background

level, try to use a lead castle to shield the measurement system from back-

ground radiation. If your background level is higher than 0.3 µSv/h, food mea-

surement will be blocked and you will get an error message (C ERR) on the

display.

True value At 100 nSv/h At 200 nSv/h At 300 nSv/h

500 Bq/L 500 +/- 30 % 500 +/- 40 % 500 +/- 50 %

Table 3: 1-Sigma statistical uncertainty with different background dose rates

Figure 11: Food measurement

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08/2012 Page 19

If you measure something other than a liquid the sample will need to be prepared. Solid food

must be mashed and the measuring cup filled precisely to the 0.6 l mark.

Note: The calibration is only valid with the supplied measuring cup and holder.

Otherwise the result can be incorrect.

Measurement steps in detail:

Step 1: Determination of the background radiation (control measurement)

•Place the empty cup and the MiniTRACE CSDF in the measurement device.

•Go to the “Food” menu.

•MiniTRACE will start with the measurement of the background. The display will

indicate how long this measurement will take (in seconds). The result of the

background measurement will be given in the dose rate unit “µSv/h”. You can

interrupt this automatic measurement by pressing the mode button. On the display

the last measured value will be shown. If no value is available in the memory of the

MiniTRACE, you will get an error message (C ERR). In this case, you will need to

conduct a background measurement. We recommend not interrupting background

measurement if you have changed measurement location, or if the last background

measurement was conducted on the previous day.

•Background (Control) measurement takes about 2 hours (7,200 seconds) and is

important for the accuracy of the final result.

Figure 12: Display for background (control) measurement in the “Food” menu

•The end of the background (control) measurement is indicated by a 1 second beep.

On the display “C ok” is shown.

Figure 13: Result display for background (control) measurement in the “Food” menu

For further measurements the background (control) measurement is only required once at

the beginning. Do the background (control) measurement:

•If you change the location of the measurement.

•For measurements on another day.

C = Control

(background)

measurement

Value of the

background dose

rate in µSv/h

(here 0.13 µSv/h)

Remaining measure-

ment time in seconds

(2,700 sec = 45 min)

Result of the

background dose

rate in µSv/h

(here 0.06 µSv/h)

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Step 2: Food measurement

The measurement result is always given in “Bq/L”. For a result in “Bq/kg” you will need to

carry out two steps:

1. Weigh the food. To do so, subtract the weight of the measurement cup (0.148 kg)

from the total weight.

2. Convert the result from “Bq/L” into “Bq/kg”.

Formula:

[ ] [ ] [ ]

L0.6SaphymofromcuptmeasurementheofVolume*

[kg]foodsolidofNet weight

Bq/LfoodtheofresulttMeasuremen

Bq/kgActivity =

Example:

The net weight of the 0.6 L chopped food sample is 1.2 kg, and the result of the food

measurement was 800 Bq/L.

gBq/k400kg0.6*

L1.2

Bq/L800

Bq/kg ==

•Fill the measurement cup with the food, taking care to reach an exact capacity of

0.6 L by filling precisely to the measuring line in the cup!

•Start the measurement of the sample (food) by pressing the mode button. After

approx. 1 minute (“Wait - - - - -“ is displayed) measurement starts automatically. In the

display the remaining measurement time (in seconds) is given as well as the possible

measurement limit (e.g. L2500) that can be achieved.

Figure 14: Display in the “Food” menu

•The end of the measurement will be indicated by a beep and in the display the result

given in “Bq/L”.

Figure 15: Result display in the “Food” menu

•The mode button enables the user to cancel the measurement and go back to the

menu.

•After the end of measurement or canceling of the menu you can start another

measurement by pressing the mode button again. If the measurement result is higher

than 500 Bq/L, a result is given on the display. If the result measurement is lower

Remaining

measurement

time

Limit

(L = LOWER THAN)

that can be achieved

(e. g. 2,500 Bq/L)

F = Food

measurement

Measurement

unit

Limit

(L = LOWER THAN)

that can be achieved

(e. g. 300 Bq/L)

SAPHYMO MiniTRACE CSDF User manual

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