GAMMA RADIATION DETECTION UNIT

BDG1-РМ1403

OPERATION MANUAL

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CONTENTS 1 General ....................................................................................................................................4 2 BDG1 delivery set....................................................................................................................5 3 Technical specifications...........................................................................................................6 4 Design and operation principle.............................................................................................10

4.1 BDG1 design .....................................................................................................................10 4.2 Handle. Telescopic extension bar.......................................................................................11 4.3 Operation principle ............................................................................................................12 4.4 BDG1 marking and sealing ................................................................................................12 4.5 Packaging ..........................................................................................................................12

5 Making BDG1 ready for operation.......................................................................................13 5.1 General notes.....................................................................................................................13 5.2 BDG1 power .....................................................................................................................13 5.3 Safety measures.................................................................................................................13

6 Proper use of BDG1 ..............................................................................................................14 6.1 Switch BDG1 On/Off ........................................................................................................14 6.2 Operability control BDG1 .................................................................................................16 6.3 Connect BDG1 to PC ........................................................................................................16 6.4 BDG1 operation ................................................................................................................17

6.4.1 Photon radiation DER measurement mode...................................................................17 6.4.2 Scintillation spectrum registration mode ......................................................................18 6.4.3 Radionuclide matter composition identification mode..................................................21 6.4.4 Photon radiation sources search mode..........................................................................22

6.4.4.1 Detection of gamma RS ......................................................................................23 6.4.4.2 Localization of gamma RS ..................................................................................23

6.4.5 PC communication mode.............................................................................................23 6.4.6 Settings of BDG1 external detection unit .....................................................................24

7 Technical maintenance..........................................................................................................26 8 Troubleshooting ....................................................................................................................27 9 Verification method...............................................................................................................28 10 Disposal.................................................................................................................................37 Appendix A................................................................................................................................38

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Thank You for purchasing a BDG1-РМ1403 gamma radiation detection unit manufactured by Polimaster.

Current Operation manual provides information on the design, construction, operation

principle of BDG1-РМ1403 (further BDAB) gamma radiation detection unit. The Operation Manual contains key technical specifications of the instrument, operation and maintenance guidelines, and procedures for metrological examination as well as other necessary information for correct instrument operation and full utilization of its capabilities.

BDG1 is documented as follows (according to state standard of manufacturer country): "Gamma Radiation Detection Unit BDG1-РМ1403 ТУ BY 100345122.060-2012". Documented BDG1 and their electric circuit, internal and external design and software are

subject to change in the manufacturing process with no substantial effect on their functionality or technical and metrological performance. Hence, Polimaster reserves the right not to mention such changes in the current Operation Manual.

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1 General

1.1 Designation and application range

1.1.1 BDG1 detection unit is designed to:

- measure ambient dose equivalent rate Н

*(10) (further DER) of roentgen and gamma radiation (further photon radiation);

- searching of the photon radiation sources; - registration and accumulation of scintillation photon radiation spectra. BDG1 provides programming modes. BDG1 can be used by radiological and isotope tracing laboratories, emergency services,

customs officers to identify radionuclide isotope compositions, measure DER of gamma radiation, search of ionization sources so that to prevent unauthorized transfer of radioactive sources and materials. Instrument is as well used by specialists engaged in different industry branches, agriculture, transport, medicine and so on, i.e. everywhere where nuclear-engineering facilities and ionizing radiation sources are used.

BDG1 is being connected to detection and information processing unit BDOI-РМ1403 (further BDOI) or personal computer (further PC) by RS-485 or USB interface.

BDG1 operation conditions: - ambient air temperature from -20 to +50 °С; - relative air humidity up to 95 % at 35 °С; - atmospheric pressure from 84 to 106,7 kPa.

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2 BDG1 delivery set Instrument delivery set corresponds to Table 2.1. Table 2.1

Name, type Quan-ty

Gamma radiation detection unit BDG1-РМ1403 1 Telescopic extension bar 1) 1 Clamp 1) 1 Handle 1) 1 Cable # 2 (1,5 m) 1) 1 Cable # 2-2 (0,25 m) 1) 1 Cable # 3 1 Certificate 1 Data storage (Software, Operation Manual2)) 1) 1 Packaging 3) 1

1) Supplied by user request, by separate order 2) Verification Method is included 3) Another packaging can be used according to consumer requirements and delivery conditions according to state standard requirements

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3 Technical specifications

Table 3.1

3.1 Operation modes: - measurement of photon radiation DER; - searching (detect and localize) of the photon radiation sources; - registration, accumulation of the scintillation spectra of photon radiation; - identification of gamma radiation sources; - programming modes

3.2 DER measurement mode* from 0.1 to 100 Sv/h

3.3 Limits of permissible main relative DER measurement error

%H/K20

,

where

H – DER value, µSv/h; К – coefficient = 2,0 µSv/h

3.4 BDG1 in the programming mode enables recording data into non-volatile memory and continuous control over DER threshold value, as well as sound and light alarming when set threshold is exceeded. When in the photon radiation DER measurement mode threshold level is exceeded – discontinuous signal 3.5 Threshold level setting discreteness unit of least significant indicated bit. Setting range of DER thresholds

from 0.01 to 100 µSv/h

3.6 Energies range of registered photon radiation

from 0.03 to 3.0 MeV

3.7 Energy dependence relative to 0,662 MeV energy, no more than

± 20 %

3.8 Unstable BDG1 readings when measuring DER during 8 hours of continuous working, no more than

5 %

3.9 Typical instrument sensitivity to gamma radiation

900 s-1/(μSv/h) (9.0 s-1/(μR/h)) for 137Cs

3.10 Count rate indication range during photon radiation registration in the search mode

from 1,0 to 70000 s-1

3.11 False operation rate of the BDG1 in the gamma radiation registration mode at radiation background no more than 0,25 μSv/h during 10 min of continuous operation, no more than

1* *

3.12 Setting range of quantity of mean square deviations of current gamma background (further n coefficient) within the limits

from 1 to 9.9

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Table 3.1 continued

3.13 Limits of permissible additional relative DER measurement error must be no more than:

when ambient air temperature changes from normal to -20°С, and from normal to +50 °С;

at ambient air relative humidity 95 % at 35 °С;

when power supply voltage changes from nominal to extreme during photon radiation DER measurement;

at exposure of 400 A/m magnetic-field strength during photon radiation DER measurement;

at radiofrequency magnetic fields effect during photon radiation DER measurement;

10 % 10 % 10 % 10 % 10 %

3.14 BDG1 with set n coefficient value at which instrument false operations rate is no more than one event during 10 min of continuous operation, and gamma background level no higher than 0.25 μSv/h, detects standard radioactive sources (SS) and alternative gamma sources, according to Table 3.1.1, with probability more than 0.5

Table 3.1.1 Source type Parameter name 133Ba 137Cs 60Co

Gamma source activity, kBq (μCi), 30% 55.0 (1.5) 100.0 (2.7) 50.0 (1.35) Movement speed (source/instrument), m/s 0.50.05 0.50.05 0.50.05 Distance between the source and detector’s sensitive surface, m 0.20.005 0.20.005 0.20.005

3.15 Quantity of accumulation channels of gamma radiation scintillation spectra

1024

3.16 Energy resolution at scintillation spectra registration by 0.662 MeV (137Cs), no more than 8.5 %

3.17 Limit of permissible main error of conversion response (integral nonlinearity) when registering scintillation spectra, no more than

0.5 %

3.18 Maximum input statistical load of the BDG1 when registering scintillation spectra, no more than 75103 с-1

3.19 Data exchange with BDOI or PC USB or RS-485

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Table 3.1 continued

3.20 Detection efficiency at the total-absorption peak for the gamma-radiation energy 662 keV radionuclide 137Cs point source OSGI-3 type, located close to the end surface of the detection unit BDG1 no less than

0.3 ± 0.03

3.21 Instability calibration characteristics BDG1 transformation during continuous operation 24 hours must be no more than 1 %

3.22 Power supply: - from BDOI; - from external power supply (USB)

5,0 (- 0,1; + 0,7) V

3.23 Instrument is resistant to: ambient air temperature from -20 to 50 оС; ambient air relative humidity up to 95 % at 35 оС; atmospheric pressure from 84 to 106.7 kPa; frosting

3.24 BDG1 is resistant to commercial frequency magnetic fields (400 A/m) 3.25 BDG1 is resistant to radiofrequency electromagnetic fields, test level 4 (30 V/m) within frequencies range 80-1000 МHz, from 800 to 960 МHz, and from 1.4 to 2.5 GHz (when there is electromagnetic emission of digital radiophones), performance criterion А 3.26 BDG1 is resistant to electrostatic discharges, test level 3 (air discharge of 8 kV, contact discharge of 6 kV), performance criterion В 3.27 BDG1 corresponds to ANSI 42.34, section 9.11 requirements by the level of emitted radio-noise 3.28 Operation conditions: ambient air temperatures range relative humidity atmospheric pressure

from -20 to 50 °С; up to 95 % at 35 С; from 84 to 106.7 kPa

3.29 BDG1 is resistant to: sinusoidal vibrations within 5-500 Hz frequencies range with shift amplitude for frequency lower than crossover frequency 0.075 mm; blows with 100 m/s2 impact acceleration, shock pulse time 2 - 50 ms, blows repetition rate 60 - 180 per minute

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Table 3.1 continued

3.30 Ingress protection IP65 3.31 BDG1 in transport packaging is resistant to:

ambient air temperature from -50 to 50 оС; ambient air relative humidity up to 100 % at 40 оС; sinusoidal vibrations within frequencies range 10-55 Hz shift amplitude for frequency lower than crossover frequency 0.35 mm

3.32 BDG1 weight, no more than 1.56 kg 3.33 packaged BDG1 weight, no more than 3 kg 3.34 BDG1 overall dimensions (size), no more than 290x70 3.35 Reliability values: - mean time between failures, no less than

20000 hours

- mean life time, no less than 10 years - mean recovery time, no more than 60 min

* Manufacturer guarantees instrument’s technical accuracy when detecting radiation sources, and instrument false operations rate at factory preset n coefficients: for gamma radiation n=4.0 * * Standard dependence of the upper limit of the measuring range DER of gamma radiation energy Eγ scintillation detection channel is given in Appendix A

Additional information on the BDG1 can be obtained from the manufacturer or after visiting the

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4 Design and operation principle

4.1 BDG1 design

Constructed as a monoblock, BDG1 is enclosed in a shockproof container. Detector is based on the scintillation block with photo amplifier. Scintillation block is based on the NaI monocrystal.

General BDG1 construction is given in the Figure 4.1.

Figure 4.1 – General BDG1 construction

Front panel bears: 1 – LED:

- yellow – BDG1 testing mode indication; - green – BDG1 calibration mode indication;

2 – Sound (audio) alarm – for sound alarms when set thresholds levels are exceeded; 3 – LED display "ALARM" (blue) – for light alarms when set thresholds levels are exceeded; 4 – Connector for PC or BDOI (RS485 or USB interfaces). Geometrical (effective) center of the counter surface is marked with the “X” sign on the front

panel, on the back panel, as well as on the counter window covering, Figure 4.2.

1 3

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2

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Figure 4.2 – Graduation direction (1) and location of the BDG1 geometrical (effective) center (2)

4.2 Handle. Telescopic extension bar

BDG1 is equipped with a handle (Figure 4.1) to enable convenient operation, and a telescopic extension bar to enable access to hard-to-reach areas (up to 1.7 m) (Figure 4.3).

Figure 4.3

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4.3 Operation principle

Operation principle of BDG1 in the search mode is based on the comparison of count rates of

photon radiation with a threshold value calculated on the basis of count rate measurement of current gamma background and set n coefficients.

Detector impulses processing as well as audible and visual alarm control is realized by BDG1 microcontroller.

BDG1 operation algorithm ensures the continuity of the measurement process, statistical processing of measurement results, rapid adaptation to radiation intensity changes (measurement time is inversely proportional to the radiation intensity).

Data communication channel enables information exchange with BDOI by RS-485 interface. BDG1 is powered from BDOI or PC USB.

4.4 BDG1 marking and sealing

Front panel of BDG1 bears a plate representing the following: - unit’s name – BDG1-РМ1403; - manufacturer’s name; - manufacturer’s trademark; - year (of the manufacturing); - serial number; - instrument’s body protection level IP65; - state register mark.

4.5 Packaging

BDG1 is packaged into a polyethylene pack and placed into a carton box with operation documentation and delivery kit.

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5 Making BDG1 ready for operation

5.1 General notes Before starting to work with BDG1, carefully read current Operation Manual and Operational

Manual on BDOI, if BDG1 will be used with BDOI. Illustrations given in the Manual represent the information displayed on the BDOI LCD; they

are used to explain BDG1 operation together with BDOI. When purchasing BDG1, check the completeness of the BDG1 delivery kit, according to the

Table 2.1. During operation protect BDG1 against blows and mechanical injuries, corrosive substances,

organic solvents, open fire sources.

5.2 BDG1 power

BDG1 is powered from BDOI or PC USB. POWER LED on the BDG1 front panel starts blinking (Figure 4.1, position 4) when BDG1 is

being connected to BDOI or PC.

5.3 Safety measures

BDG1 is electrically safe. All settings, checking, repairs, technical maintenance and verification procedures of BDG1

when radiation sources are used, must be done according to state and local safety instructions for radioactive sources and other ionizing radiation sources valid at the verification site.

When any radioactive sources are detected, observe current operational rules when working with radioactive sources.

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6 Proper use of BDG1 6.1 Switch BDG1 On/Off 6.1.1 BDG1 detection unit is connected to BDOI by cable # 2 or to PC by RS-485 or USB

interface 6.1.2 Connect BDG1 to BDOI. Connect BDG1 to BDOI using the cable # 2. Switch BDOI on. To switch BDOI on: press the ON/OFF key on the BDOI case (Figure 6.1, position 11). When BDOI is switched on, the power is automatically applied to BDG1. At that the POWER

LED will light on the front panel of BDG1 (Figure 4.1, position 1).

1 – emits sound (audio) alarm when set DER, DE thresholds are exceeded; 2 – "ALARM" LED – for alarming; 3 – "BAT" LED – for On/Off state indication or BDOI charging; 4 – GPS receiver; 5 – color LCD 3,5” (89 mm); 6 – keypad keys; 7 – Wi-Fi antenna; 8 – fastening for removable clip, bracket; 9 – GPRS antenna, GSM; 10 – RESET key - restart BDOI operation system; 11 – ON/OFF key – switch BDOI On/Off; 12 – battery compartment; 13 – connector for external detection units (RS485 interface); 14 – connector for PC connection and accumulators charge (USB interface); 15 fastening for removable clip, bracket.

Figure 6.1 – External view of BDOI

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External view of BDOI keypad and keys functional purpose are given in the Figure 6.2.

1, 2 – , (<<, >>) – quick switching between menu items or parameters;

3 – (MENU/SELECT) – enter selected operation mode of BDOI or highlighted option of the MENU;

4 – (MODE/BACK/OK) – open the list of BDOI operation modes. Exit or return to the previous operation mode or option.

Directional pad keys:

5 – (UP), 6 – (DOWN) – vertical cursor scrolling along menu options;

7 – (LEFT), 8 – (RIGHT) – horizontal cursor scrolling; 9 – (ENTER) – this key pressing executes the EXECUTE command, and enables

switching to some program or option.

Figure 6.2 – External view and functional purpose of BDOI keypad keys

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When BDOI testing and calibration are finished, the BDOI LCD will indicate a connected BDG1 external detector, in the line "Detector NaI [BDG1]", Figure 6.3 (2).

If BDG1 is connected to the switched on BDOI, then in the indication mode of the BDOI operation modes select the "Find Detectors" line, Figure 6.3 (1).

To enter the indication mode of the BDG1operation modes: select the "Detector NaI [BDG1]" line. A window displaying the operation modes of BDG1will be opened, Figure 6.3 (3).

1) 2) 3)

Figure 6.3 Use keypad to control BDOI (Figure 6.2). BDG1 is switched on and ready for operation. BDG1 switches off when the cable is disconnected from it, or after BDOI is switched off. To switch BDOI off: press key ON/OFF and wait till the BDOI switches off. 6.2 Operability control BDG1 Switch on BDG1 as stated in 6.1. Green LED must light on the BDG1 front panel. Check every BDG1 operation mode operability: LED lights green – indicates that the BDG1 test mode is activated (Figure 4.1, position 1); LED lights yellow – indicates that the BDG1 calibration mode is activated (Figure 4.1,

position 1); Switch off BDG1 as stated in 6.1. 6.3 Connect BDG1 to PC Connect BDG1 to the USB port of the working PC using the cable # 3. BDG1-PC operation procedure is described in the user program supplied on the CD. Start user program. Switch BDG1 into the measurement mode of photon radiation DER.

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6.4 BDG1 operation BDG1 enables following operation modes:

- measurement of photon radiation DER; - registration and accumulation of photon radiation scintillation spectra; - identification of gamma radiation sources; - search of photon radiation sources; - connection to the PC.

Use BDOI keypad keys to select the line in the following order: Search Mode → Measurement

Mode →Spectra accumulation → Continue accumulation → Quick identification. Use SELECT key to switch to the operation mode.

BDG1 automatically enters test mode every time when connected to BDOI. At that the BDOI

LCD will indicates a linear scale that indicates time left till test process termination, Figure 6.4 (1). After termination of testing, BDG1 automatically enters the gamma background calibration

mode, Figure 6.4 (2). Linear scale in relative units indicates the time passed since the calibration beginning. Filling of the scale means the end of the calibration. At the end of the calibration BDG1 enters the search mode of photon radiation sources.

1) 2)

Figure 6.4 6.4.1 Photon radiation DER measurement mode

To enter photon radiation DER measurement mode “Measurement mode” it is necessary to

select “Measurement mode” menu option, Figure 6.3 (1-3), in the window displaying operation modes of the "Detector NaI [BDG1]".

The instrument in the DER measurement mode "Measurement mode" displays continuously measured DER values of photon radiation in "μSv/h", "mSv/h", "Sv/h" or "μR/h", "mR/h", "R/h", Figure 6.5 (1).

Statistical error of measured DER is displayed in percents with 0.95 probability under indicated measurement units on LCD. User can start reading DER measurement data when statistical error is 10 % or less. The less statistic error, the more accurate measurement result will be.

Level of measured DER is also displayed graphically on analogue scale. Quantity of lighting analog scale segments corresponds to the measured DER value according to the set DER threshold value.

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1) 2)

Figure 6.5

When set DER threshold is exceeded, the analogue scale will be filled completely, and audio

alarm (monotonous single signals being repeated every 3 s) will be activated. The "Threshold is exceeded" message will be displayed on LCD; measured DER value will be indicated in red blinking digits. DER threshold exceeded event will be recorded to the instrument’s non-volatile memory.

When DER measurement range is exceeded (overload), BDG1 emits sound alarm (monotonous single signals being repeated every 3 s) and indicates the "OVL" message on the LCD.

DER measurement mode menu enables following functions, Figure 6.5: – "Clear Statistic" – start of the count rate and DER measurement; – "Save To History" - save the history to the BDOI memory; – "Sound On/Off" – audible alarm on/off switching; – "Thresholds" – set the detection level thresholds; – "Send To NPNET".

6.4.2 Scintillation spectrum registration mode

To enter the menu of scintillation spectrum registration mode "Accumulation Spectrum"/"Continue Accumulation" select in the window displaying operation modes of the "Detector NaI [BDG1]", Figure 6.6 (1-3), following items:

- "Accumulation spectrum" – to reset the statistics and start new spectrum accumulation; - "Continue accumulation" – to continue accumulation of the spectrum being accumulated

last, even if this spectrum was saved and processed.

1) 2) 3)

Figure 6.6

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N o t e Before spectrum accumulation: take reference spectrum from reference source under the same conditions that will be applied when taking spectra from tested object. As a reference source can be used sources such as OSGI-3-2 152Eu, 228Th activity from 50 to 100 kBq. To take the reference spectrum: place a reference source as close as possible to the geometrical (effective) center of the gamma detector, and do the following procedure. Take the reference source away from the BDG1 when the reference spectrum accumulation is over, and the spectrum is saved into BDG1 memory.

LCD will display average count rate of the registered photon radiation impulses. Over the area of the display the measured value display of count rate is analogue scale that

shows the relative value of the measured count rates, Figure 6.7.

1) 2) 3)

Figure 6.7

Pink scale (Figure 6.7 (1)) means that average count rate of gamma channel is low "Low

Count Rate" (less than 200 cps). Low gamma channel load results in uncertain spectrum. Green scale (Figure 6.7 (2)) means that average count rate of gamma channel corresponds to

optimal load (from 200 to 20000 cps). Optimal gamma channel load results in reliable and undistorted spectrum.

Red scale (Figure 6.7 (3)) means that average count rate of gamma channel is too high "High Count Rate" (more than 20000 cps). Too high gamma channel load results in distorted spectrum.

Move to BDG1 as close as necessary to the tested object so that the count rate by detection unit is within 200-20000 cps and then press OK.

During spectrum accumulation the LCD will display a graph of accumulated spectra in progress, and time (Figure 6.8 (1)) that passes from the accumulation start. Displayed spectrum is renewed every 10 s.

1) 2)

Figure 6.8

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BDG1 accumulates spectrum by 1024 channels. Channel capacity is 65536. It is necessary to accumulate not less than 104 pulses in the maximum count channel to get a good quality spectrum. Besides, you can visually determine the time of spectrum accumulation by the graph on LCD: if you can see clearly distinguishable peaks on the graph, you can stop the spectrum accumulation and start processing of the spectrum.

Menu of scintillation spectrum registration mode enables the following functions, Figure

6.8 (2): "Clear Statistic". Manual statistics reset enables reset of measurement data buffer

accumulated by the BDG1. Instrument starts new spectrum accumulation after statistics are cleared; "Identify". Starts process of radionuclide matter composition identification by

accumulated spectrum. Identified radionuclides are classified into groups: - special nuclear materials; - medical; - industrial; - natural; "View Library" view the radionuclides library; "Set Absorber". To obtain more reliable results of the radionuclide composition

identification it is necessary to enter the security settings: o "Height, mm" – set the material thickness, in mm; o "Material" – set the material;

"Options". Select identification report format and graphical spectrum representation on the BDOI LCD;

"Save As…". Saving accumulated spectrum; "Send to NPNET" By user command the following data will be sent to the Web-server:

accumulated spectrum file with geographical coordinates (latitude/longitude) of instrument’s location, current date and time;

"Spectrum info" View supplemental information on spectrum; "Peak Info" Information view about the peak spectrum in the position of the marker;

Figure 6.9 Following information is displayed in the lower LCD area (Figure 6.9): - set speed of marker moving along the spectrum (х2/х4/х8/х16/х32); - channel number (or energy in KeV (kiloelectronvolt)) where the marker is placed; - quantity of impulses in this channel; - spectrum accumulation time.

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6.4.3 Radionuclide matter composition identification mode To enter the radionuclide matter composition identification mode select the "Quick Identify"

option (6.10 (1)) in the window displaying operation modes of the built-in detection unit "Detector NaI [BDG1]".

1) 2) 3)

Figure 6.10

Instrument will enter the radionuclide matter composition identification mode "Quick

Identify". LCD will display average count rate of photon radiation impulses being registered. Graphical scale of gamma channel load will be displayed on the LCD simultaneously with digital count rate indication. Move the instrument as close as necessary to the tested object so that the count rate by detection unit is within 200-20000 cps. It corresponds to green area on the scale (Figure 6.10 (2)). Press OK key to start spectrum accumulation and identification.

If gamma channel load is sufficient (within range 200-20000 cps), the instrument will take about 150-300 s to display the identification result in the upper LCD area. If gamma channel load is less or more than stated one, then the instrument will take more time to identify.

During spectrum accumulation the lower LCD area displays the image of accumulated spectrum in progress and analogue scale of time passing from the spectrum start (Figure 6.10 (3)). LCD renews spectrum every 10 s. At that the BDG1 every 10 s will attempt to identify nuclides accumulated during this time.

When instrument accumulates statistical data enough for radionuclide matter composition identification attempt, the identification results will be immediately displayed in the upper LCD area, Figure 6.10 (3).

Identification mode menu enables the following functions: "Clear Statistic" - manual statistics reset enables reset of measurement data buffer

accumulated by the instrument and start of the new spectrum accumulation; "View Library" of the radionuclides; "Set Absorber": to obtain more reliable results of the radionuclide composition

identification it is necessary to enter the security settings: o "Height, mm" – set the material thickness, in mm; o "Material" – set the material.

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6.4.4 Photon radiation sources search mode BDG1 with BDOI can be used for photon radiation sources searching. BDOI can be used for

gamma radiation sources searching. If BDG1 is in search mode and pulse count rate exceeds the upper limit, BDOI LCD displays

message "OVL". To search for gamma radiation sources connect BDG1 to BDOI, according to the item 11.2.1

of the BDOI-RM1403User Manual, and select gamma radiation sources search mode - "Search Mode".

To enter BDG1 search mode - "Search Mode" select in the window displaying operation modes of the "Detector NaI [BDG1]", Figure 6.3 (1-3) item “Search mode”.

Instrument in the search mode calculates current value of average count rate of impulses coming from BDG1. It indicates the value in cps in the upper line, and in the lower line average statistical error of the average gamma radiation count rate (%), Figure 6.11 (1).

BDOI LCD during photon radiation DER measurement displays continuously measured DER values in "Sv/h", "mSv/h", "Sv/h" or "μR/h", "mR/h", "R/h", Figure 6.11 (1).

1) 2)

Figure 6.11 Count rate current value is compared with the threshold calculated in the calibration mode. If

the count rate current value exceeds a threshold value, then the alarm (sound and light) goes on. Constant repetition rate of the signals increases with the count rate threshold excess, with approaching to the gamma radiation source.

Operation threshold of gamma channel can be changed by setting a new n coefficient by gamma channel. Setting range of n coefficient is 1 - 9.9. Obviously, the lower is the coefficient n value, the lower is the operation threshold, and the higher is the BDG1 sensitivity in search mode. However, this increases the false operation rate.

Search mode menu, Figure 6.11 (2), enables following functions: "Clear Statistic". Instrument starts count rate and DER measurement;; – "Calibration" – after recalibration BDG1 enters automatically the search mode; – "Save To History" – save current measurement results into the BDOI memory; − "Thresholds" – set the detection threshold; − "Sound On/Off" – temporarily switch on/off audio alarm; − "Send To NPNET".

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6.4.4.1 Detection of gamma RS

To detect gamma radiation sources (further RS) BDG1 should be placed so that the graduation direction (Figure 4.2) of the built-in detection unit coincides with the direction to the tested object. The closer the effective center of the BDG1 detector is placed to the object under examination (luggage, person, container, vehicle, etc.) and the slower it moves alongside the object, the higher the RS detection rate will be.

Use light alarms and watch LCD indication to detect RS in noisy environments (BDG1 sound (audio) signals might not be heard)).

Instrument sensitivity and false operation rate depends on: - set n coefficient; - background level calculated by BDG1 in calibration mode. Since natural radiation background level fluctuations can be significant, calibrate instrument

to background level just before starting detection of RS (11.1.2). Note, that the instrument during misoperation emits nonsystematic light and sound alarms.

Such alarms can be easily differed form the signals emitted by the instrument when RS are detected (the signals are characterized by constant repetition rate). The rate increases when RS gets closer to the instrument.

Start RS localization when RS is detected or there is some indication of possible RS presence. 6.4.4.2 Localization of gamma RS To localize RS: place BDG1 near the tested object at a distance of no more than 10 cm.

Move the instrument alongside the object no faster than 10 m/s. The closer RS is, the faster the signals repetition rate is.

Sound (audio) signals, accompanied by blinking blue ("ALARM") LED, are heard when sound (audio) alarm function is switched on.

When frequency of light and sound (audio) alarms becomes extreme (right up to continuous light and sound signal), further localization procedure is possible only after the instrument is calibrated to new gamma background level. To do this, keep the same distance to the object (if possible) and switch to the calibration mode. The instrument will enter the mode of calibration by gamma background level. BDOI LCD can show message warning that the calibration process may take some time. In this case user should decide whether to interrupt the calibration process. After that the calibration to new gamma background level is completed the RS localization procedure can be continued.

6.4.5 PC communication mode

BDG1 enables information exchange with PC running under WINDOWS. Operation

sequence for working in the mode of communication with PC by USB or RS-485 interface is given in the “Help” file of the current program. Do the following to enable BDG1 operation in the PC-communication mode:

- install user program from the supplied CD onto the PC; - connect BDG1 to PC using the USB-cable; - start user program; - PC takes control over BDG1. Working with PC is described in the annotation.

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6.4.6 Settings of BDG1 external detection unit In “Instrument settings” −> "Detector NaI [BDG1]", Figure 10.12 (1), user can view or change

the external detector settings: "General" tab, Figure 10.12 (2): − read BDG1 number; − allow/prohibit sound and light alarms. "Thresholds" tab, Figure 10.12 (3): − set the "Coefficient n" – n coefficient determines operation threshold (minimum detection

level of gamma radiation) of gamma channel. Operation threshold of gamma channel can be changed by setting a new n coefficient by gamma channel. Setting range of n coefficient is 1 - 9.9, 0.1 discreteness.

− set the "Measurement Threshold, mSv/h" – DER threshold – when BDG1 will reach set DER value in the DER measurement mode, it will display a warning message: "Threshold is exceeded". DER threshold setting range corresponds to DER measurement range (Table 3.1). Enter DER threshold value which is equivalent to "mSv/h" measurement unit.

"Energy Calibration" tab, Figure 10.12 (4): − coefficients А, В, C, К1 and К2 coefficients values are calculated and recorded into

BDG1 by representatives of Polimaster for every temperature individually. The coefficients are used by the instrument for calibration.

Attention! Untrained user is not recommended to change energy autocalibration

parameters, since it may result in instrument malfunction. "FWHM Calibration" tab, Figure 10.12 (5): − "FWHM – First point" – Width at half-height of first calibration point in keV.

Recommended initial value is 38.0 (for 122 keV energy); − "Energy – First point" – First calibration point energy. Recommended energy value is

122 keV; − "FWHM – Second point" – Width at half-height of second calibration point in keV.

Recommended initial value is 58.0 (for 662 keV energy)' − "Energy – Second point" – Second calibration point energy. Recommended energy

value is 662 keV. "Autocalibration" tab, Figure 10.12 (6): − "Name" – select spectrometric reference gamma radiation source for autocalibration; − "FWHM coeff" – coefficient of peak half-width. The coefficient corrects estimated peak

half-width at autocalibration. It enables increase of peak half-width if its value is more than 1, or decrease it if coefficient value is less than 1;

− "First point": − "Min:" – channel number of first peak start boundary (70); − "Max:" – channel number of first peak decrease boundary (140); − "Ener. (keV)" – energy value of the line for the first calibration peak (344 keV). Energy

values of lines corresponding to calibration peaks within the set limits can be found in the nuclides library for the given calibration source.

− "Second point": − "Min:" – channel number of second peak start boundary (330); − "Max:" – channel number of second peak decrease boundary (440); − "Ener. (keV)" – energy value of the line for the second calibration peak (1408 keV).

Energy values of lines corresponding to calibration peaks within the set limits can be found in the nuclides library for the given calibration source.

25

1) 2) 3)

4) 5) 6)

Figure 6.12

26

7 Technical maintenance Purpose of BDG1 technical maintenance is to provide its constant operability and reliable

operation during its long service life. Preventive maintenance includes external examination, dust removal and deactivation (if

radioactive dust gets on BDG1). To deactivate BDG1, wipe it with soft cloth wetted with ethyl alcohol. Alcohol volume on the BDG1 decontamination 70 ml is required.

27

8 Troubleshooting A list of possible problems and troubleshooting is given in the Table 8.1. Table 8.1

Possible problem Possible reasons Troubleshooting

1) Green "MODE" LED doesn’t light when BDG1 is connected to BDOI or PC

Cable is faulty BDOI or PC is switched off

Replace the cable

Switch BDOI or PC on

2) Sound alarm doesn’t work

Sound is OFF Detector is faulty

Switch on sound in the PC or BDOI communication mode; Repaired by manufacturer

3) No detector is found during connection to BDOI or PC Cable is faulty Replace the cable

28

9 Verification method

9.1 Introduction 9.1.1 This verification procedure defines methods and tools of primary and periodic

verification procedure of the dosimeter-radiometer PM1403. 9.1.2 Produced instruments and instruments repaired because of non-compliance of

metrological performance with specification requirements are subject to primary verification. Instruments in operation are subject to periodic verification. 9.1.3 Verification is carried out by local state metrological services according to current

standards, or by authorized companies. Verification frequency of instruments in use 12 months.

9.2 Verification procedure operations During the verification following operations specified in Table 9.1 should be carried out. Table 9.1

Carrying out at Operation name Verification procedure

chapter number primary verification

periodic verification

External examination 9.8.1 Yes Yes Testing 9.8.2 Yes Yes Metrological performance

characterization: - estimation of the photon radiation

DER permissible intrinsic relative error

9.8.3.1, 9.8.3.3, 9.8.3.5

Yes Yes Yes

Yes Yes Yes

- estimation of the neutron radiation DER permissible intrinsic relative error

9.8.3.7

Yes

Yes

- estimation of the photon radiation DE permissible intrinsic relative error

9.8.3.6

Yes

Yes

- estimation of the relative energy resolution in the scintillation spectra accumulation mode

9.8.3.2, 9.8.3.4

Yes Yes

Yes Yes

- estimation of the intrinsic relative error of the alpha- radiation flux density

9.8.3.8

Yes

Yes

- estimation of the intrinsic relative error of the beta- radiation flux density

9.8.3.9

Yes

Yes

9.3 Verification tools Verification has to be performed with the means of the tools with following characteristics as

specified in the Table 9.2. Table 9.2

Verification procedure chapter number at Names of the reference and

auxiliary verification tools Main characteristics primary verification

periodic verification

Reference verification assembly with 137Cs sources set, according to local government standards

DER measurement range from 0.1 μSv/h to 10 Sv/h. Accuracy of the assembly calibration no more than ± 6 %

9.8.3.1, 9.8.3.3, 9.8.3.5, 9.8.3.6

9.8.3.1, 9.8.3.3, 9.8.3.5, 9.8.3.6

29

Reference alpha sources with 239Pu radionuclide of the type 4П9, 5П9 or 6П9, with working surface 40, 100 or 160 cm2, respectively

Flux density from 10 to 5105 min-1cm-2. Accuracy of the assembly calibration no more than ± 6 %

9.8.3.8

9.8.3.8

Reference beta sources with 90Sr+90Y radionuclide of the type 4СО, 5СО or 6СО with working surface 40, 100 or 160 cm2, respectively

Flux density from 10 to 106 min-1cm-2. Accuracy of the assembly calibration no more than ± 6 %

9.8.3.9

9.8.3.9

Verification assembly, creating collimated neutron field, with neutron source with first-class reference neutron Pu--Be radionuclide sources kit

Calibrated by the neutron radiation DER in the range from 510-10 to 10-6 Sv/s. Accuracy of the reference sources calibration no more than 9 %

9.8.3.7

9.8.3.7

Reference spectrometric gamma sources OSGI 3-2 (137Cs, 57Co)

Accuracy of the reference sources calibration no more than 4 %

9.8.3.2, 9.8.3.4

9.8.3.2, 9.8.3.4

Thermometer Scale interval 1.0 С. Measurement range 10 - 40 С

9.6.1

9.6.1

Barometer Scale interval 1.0 kPa. Measurement range 60 – 120 kPa. Intrinsic error no more than 0.2 kPa

9.6.1

9.6.1

Hydrometer Measurement range 30 - 90 %. Measurement accuracy no more than ± 5 %

9.6.1

9.6.1

Dosimeter DER measurement range of the external gamma background from 0.1 to 10 μSv/h. Permissible intrinsic relative measurement error no more than ± 20 %

9.6.1

9.6.1

9.4 Verification officers qualification requirements 9.4.1 Only persons certified as state verification officers in accordance with established

procedure are allowed to conduct measurements during verification and (or) to analyze measurement results.

9.5 Safety requirements 9.5.1 Any works with radioactive sources must be done according to state and local safety

instructions for radioactive sources and other ionizing radiation sources valid at the verification site. The verification process should be considered as work under special conditions.

30

9.6 Verification conditions 9.6.1 Instrument verification is carried under normal environmental conditions:

- ambient air temperature (20 5) С; - relative air humidity 60 (+20;- 30) %; - atmospheric pressure 101.3 (+5.4; -15.3) kPa; - external gamma background radiation no more than 0.2 μSv/h.

9.7 Pre-verification procedure 9.7.1 Instrument verification procedure is carried out with fully charged accumulator

batteries. 9.7.2 The following pre-verification procedures are required: - study carefully Certificate and Operation Manual before working with the Detection and

Information Processing Unit (BDOI), Gamma Radiation Detection Unit (BDG1), Gamma Radiation Detection Unit (BDG2), Neutron Radiation Detection Unit (BDN), Alpha-Beta Radiation Detection Unit (BDAB) to prevent errors and ensure safe instrument operation.

- prepare Instrument for operation according to the “Make Instrument Ready for use” chapter of current Operation Manual for each detection unit.

- prepare instrument and auxiliary equipment for verification procedure in accordance with their technical documentation.

9.8 Verification procedure 9.8.1 External examination 9.8.1.1 External examination must prove that instrument meets following requirements: - delivery kit corresponds to Operation Manual requirements; - there is a note in the Operation Manual about primary verification or certificate of recent

verification; - there are clear markings on the Instrument surface; - there is no dirt or mechanical damage that can affect Instrument operation. 9.8.2 Testing 9.8.2.1 Do the following when testing BDOI: - check BDOI operability according to “Instrument Operability control” chapter of the BDOI

Operation Manual; - set maximum values of DER equivalent thresholds according to “Instrument Settings Mode”

chapter of the BDOI Operation Manual. 9.8.2.2 Do the following when testing BDG1: - connect BDG1 detection unit to BDOI or to PC; - switch BDOI or PC on and check BDG1 operability according to the “Instrument

Operability control” chapter of the BDG1 Operation Manual; - set maximum DER values thresholds according to “Instrument Settings Mode” chapter of

the BDG1 Operation Manual. 9.8.2.3 Do the following when testing BDG2: - connect BDG2 detection unit to BDOI or to PC; - switch BDOI or PC on and check BDG2 operability according to the “Instrument

Operability control” chapter of the BDG2 Operation Manual; - set maximum DER values thresholds according to “Instrument Settings Mode” chapter of

the BDG2 Operation Manual.

31

9.8.2.4 Do the following when testing BDN: - connect BDN detection unit to BDOI or to PC; - switch BDOI or PC on and check BDN operability according to the “Instrument Operability

control” chapter of the BDN Operation Manual; - set maximum DER values thresholds according to “Instrument Settings Mode” chapter of

the BDN Operation Manual. 9.8.2.5 Do the following when testing BDAB: - connect BDAB detection unit to BDOI or to PC; - switch BDOI or PC on and check BDAB operability according to the “Instrument

Operability control” chapter of the BDAB Operation Manual. 9.8.3 Determination of the metrological characteristics 9.8.3.1 Calculate permissible intrinsic relative error of photon radiation DER measurement for

BDOI in the following way: 1) switch BDOI and set maximum DER threshold levels; 2) switch BDOI off; 3) place BDOI on the verification assembly with 137Cs gamma source so that the instruments’

panel faces the radiation source, and the line going through the geometrical center of the detector aligns with the irradiation flow axis. Geometrical center of the detector is marked by “+” sign on instrument’s surface. Switch BDOI on;

4) at set statistical error value of less than 10 % take five DER measurement readings at an interval of at least 60 s when there is no radiation source. Then calculate average DER value of the

external gamma radiation background bH.

(further – gamma background), μSv/h, using the Formula

5

5

..

51

ibib НН , (9.1)

where biH.

– i-th reading of instrument while measuring DER of gamma background, μSv/h; 5) place sequentially the instrument onto the dosimetric assembly so that geometrical center of

the detector coincides with the reference point where reference DER value equals 0.8; 8.0 and 80.0 μSv/h,;

6) at set statistical error value of less than 5 % take five DER measurement readings at an

interval of at least 30 s. Then calculate average DER value j

.H using Formula

5

1

..

51

ijij HН , (9.2)

where .

jiН – i-th reading of the instrument when measuring DER in the verifiable point, μSv/h;

7) calculate relative DER measurement error Qj, %, in every reference point, using Formula

100)(.

...

oj

ojbjj

H

HHHQ , (9.3)

where ojH.

– reference DER value in the tested point, μSv/h;

jH.

– average DER value in the tested point, μSv/h;

bH.

– average value of gamma background DER, calculated using the Formula (9.1), μSv/h;

32

8) calculate confidence limits of permissible intrinsic relative error of DER measurement

DER, %, at confidence probability 0.95 using Formula 221,1 joDER QQ , (9.4)

where Qo − error of dosimetric assembly, %; Qj − relative measurement error calculated using the Formula 9.3.

Verification results are considered satisfactory if values of confidence limits of intrinsic

relative DER measurement error for all verifiable points, calculated using the Formula (9.4), do not exceed the limits of permissible intrinsic relative error add = 30 %.

9.8.3.2 Check ability to accumulate scintillation spectra of gamma radiation and relative

energy resolution during BDOI operation in the scintillation spectra accumulation mode as follows: 1) switch BDOI on and set into the spectrum accumulation mode according to the chapter

11.1.5 of the Operation Manual; 2) place gamma sources 137Cs and 57Со (104 - 105) Bq from the reference spectrometric

gamma sources set of OSGI-3 type at such a distance from the scintillation detector surface against the geometrical center so that the count rate was from 150 to 900 cps;

3) press OK button and continue spectrum accumulation till a well-defined spectrum will be displayed on LCD, or continue accumulation during 100 s at least. The LCD will display accumulated spectrum;

4) stop spectrum accumulation by pressing the MENU button and record accumulated spectrum into BDOI memory under the selected number as specified in Operation Manual, chapter 11.11;

5) send accumulated spectrum to PC according to the chapter 11.11 of the Operation Manual; 6) see information on working with spectra saved in the PC in “Read Me” file of the user

program “РМ1403 spectra”; 7) calculate the relative energy resolution 1, %, using the Formula

10021

Е

, (9.5)

where Е − energy value of total absorption peak of low-energy line 137Cs, keV; 2 − value of absolute energy resolution in keV, calculated using the Formula

2 = n К , (9.6) where n − width value of total absorption peak of mono-energy line 137Cs at its half-height

in channels; К − values of the channel energy width, keV/channel, calculated using the Formula

К = Е Еn nc c

2 1

2 1

, (9.7)

where Е2, Е1 − energy values corresponding to total absorption peaks 137Cs and 57Co correspondingly;

nc2, nc1 − channels numbers corresponding to peaks’ centroids with Е1 and Е2 energies. Verification results are considered satisfactory if relative energy resolution 1, %, calculated

using the Formula (9.5) doesn’t exceed 7,5 %. 9.8.3.3 Calculate permissible intrinsic relative error of photon radiation DER measurement for

BDG1 in the following way: 1) connect BDG1 detection unit to BDOI; 2) place BDG1 on the verification assembly with 137Cs gamma source so that the instruments’

panel faces the radiation source, and the line going through the geometrical center of the detector aligns with the irradiation flow axis. Geometrical center of the detector is marked by “+” sign on

33

instrument’s end surface and by annular groove on the side surface. Switch BDOI on. Select the DER measurement mode with the BDG1;

3) at set statistical error value of less than 10 % take five DER measurement readings at an interval of at least 30 s when there is no radiation source. Then calculate average DER value of the external gamma background, μSv/h, using the Formula (9.1).

4) place sequentially BDG1 onto the dosimetric assembly so that geometrical center of the detector coincides with the reference point where reference DER value equals 0.8; 8.0 and 80.0 μSv/h;

5) at set statistical error value of less than 5 % take five gamma DER measurement readings

in every reference point at an interval of at least 10 s. Then calculate average DER value jH.

using Formula (9.2).

6) calculate relative DER measurement error Qj, % using Formula (9.3). 7) calculate confidence limits of permissible intrinsic relative error of DER measurement

DER, %, at confidence probability 0.95 using Formula (9.4). Verification results are considered satisfactory if values of confidence limits of intrinsic

relative DER measurement error for all verifiable points, calculated using the Formula (9.4), do not exceed the limits of permissible intrinsic relative error calculated using the Formula

)%,20(.

HKadd (9.8)

where .

H − DER value, μSv/h; К – coefficient, equal 2,0 μSv/h.

9.8.3.4 Check ability to accumulate scintillation spectra of gamma radiation and relative

energy resolution during BDG1 operation in the scintillation spectra accumulation mode as follows: 1) connect BDG1 to BDOI; 2) switch BDOI on and set into the spectrum accumulation mode according to the chapter

11.1.5 of the Operation Manual; 3) place gamma sources 137Cs and 57Со (104 - 105) Bq from the reference spectrometric

gamma sources set of OSGI-3 type at such a distance from the scintillation detector surface against the geometrical center so that the count rate was no more than 10000 cps;

4) press START button and carry out spectrum accumulation till a well-defined spectrum will be displayed on LCD, or continue accumulation during 100 s at least. The LCD will display accumulated spectrum;

5) stop spectrum accumulation by pressing the MENU button, record accumulated spectrum into BDOI memory and send accumulated spectrum to PC as specified in Operation Manual, chapter 11.11;

6) see information on working with spectra saved in the PC in “Read Me” file of the user program “РМ1403 spectra”;

7) calculate the relative energy resolution 1, %, using the Formula (9.5). Verification results are considered satisfactory if relative energy resolution 1, %, calculated

using the Formula (9.5) doesn’t exceed 8.5 %. 9.8.3.5 Calculate permissible intrinsic relative error of photon radiation DER measurement for

BDG2 in the following way: 1) connect BDG2 detection unit to BDOI; 2) place BDG2 on the verification assembly with 137Cs gamma source so that the instruments’

panel faces the radiation source, and the line going through the geometrical center of the detector aligns with the irradiation flow axis. Geometrical center of the detector is marked by “+” sign on instrument’s end surface and by annular groove on the side surface. Switch BDOI on. Select the DER measurement mode with the BDG2;

3) at set statistical error value of less than 10 % take five DER measurement readings at an interval of at least 30 s when there is no radiation source. Then calculate average DER value of the

34

external gamma background, μSv/h, using the Formula (9.1). 4) place sequentially BDG2 onto the dosimetric assembly so that geometrical center of the

detector coincides with the reference point where reference DER value equals 3.0; 30.0; 300.0 μSv/h, 3.0; 30.0; 300.0 mSv/h, 3.0; 8.0 Sv/h,

5) at set statistical error value of less than 5 % take five gamma DER measurement readings

in every reference point at an interval of at least 10 s. Then calculate average DER value jH.

using Formula (9.2).

6) calculate relative DER measurement error Qj, % using Formula (9.3). 7) calculate confidence limits of permissible intrinsic relative error of DER measurement

DER, %, at confidence probability 0.95 using Formula (9.4). Verification results are considered satisfactory if values of confidence limits of intrinsic

relative DER measurement error for all verifiable points, calculated using the Formula (9.4), do not exceed the limits of permissible intrinsic relative error calculated using the Formula

)%,20(.

HKadd (9.9)

where .

H − DER value, μSv/h; К – coefficient, equal 2,0 μSv/h.

9.8.3.6 Calculate permissible intrinsic relative error of photon radiation DE measurement for

BDG2 in the following way: 1) connect BDG2 detection unit to BDOI, switch BDOI on, switch DE measurement mode on

and set maximal DE thresholds value; 2) place BDG2 on the verification assembly so that geometrical center of the detector

coincides with the reference point where reference DER value equals 8.0 μSv/h. 3) take initial DE value; 4) irradiate BDG2 during T = 1.0 h; 5) after that take the final DE value; 6) calculate permissible intrinsic relative error of Qj measurement, % using Formula

100)(

.

.

TH

THHHQ

oj

ojHjKjj , (9.10)

where Нкj – final DE value; Ннj – initial DE value;

ojH.

– reference DER value in reference point; Т – irradiation time, h;

7) repeat measurement for reference points where reference DER value equals 8.0; 800 mSv/h. 8) calculate confidence limits of permissible intrinsic relative error of DE measurement DE, %,

at confidence probability 0.95 using Formula 22 )()(1.1 joDE QQ , (9.11)

where Qo − error of dosimetric assembly, %; Qj − relative DE measurement error calculated using the Formula (9.10), %.

Verification results are considered satisfactory if values of confidence limits of intrinsic relative DE measurement error for all verifiable points, calculated using the Formula (9.11), do not exceed the limits of permissible intrinsic relative error add= ± 10 %.

9.8.3.7 Calculate permissible intrinsic relative error of neutron radiation DER measurement in

the following way: 1) connect BDN detection unit to BDOI, switch BDOI on and select neutron radiation DER

measurement mode;

35

2) place verified BDN on the calibration bench of the reference assembly gage carriage so that the position of neutron field point for which the reference value of measured DER was calculated,

ojH.

, coincides with the direction of detection unit geometric center. Geometric center of BDN neutron detector must coincide with symmetry axis of neutrons collimated beam. At that longitudinal axis of the detector must be perpendicular to the symmetry axis of neutrons collimated beam;

3) successively place the gage carriage with BDN on the reference assembly so that the

detector’s geometric center coincides with the reference points where the reference value ojH.

, equals 3.0; 30.0; 300.0; 1500 and 4000 μSv/h. When statistical error is less than 5 %, read five neutron radiation DER values in every reference point with the interval no less than 30 s. Then calculate

average DER value jH.

for every verifiable point, using the Formula (9.2). 4) calculate the instrument readings caused by direct radiation, using the Formula

RijijB BHH ..

, (9.12) where ВR – coefficient taking into account the effect of scattered neutron radiation on the

instrument readings (the coefficient is calculated during the assembly verification); 5) calculate the measurement error Qj, %, using the Formula

oj

ojijBj

H

HHQ.

..

; (9.13)

6) calculate permissible limits of intrinsic relative measurement error at confidence probability 0,95, using the Formula

2max

2max

2

3 jjo

s SQQ

K

, (9.14)

where Кs – coefficient depending on random errors equal to 2; Qo − error of reference dosimetric assembly, %; Sjmax – value of the relative average deviation of measurements result Sj, % calculated

using Formula

%100)1(

)(1

5

1

2..

.

nn

HH

HS

jBijB

jB

j . (9.15)

Verification results are considered satisfactory, if values of confidence limits of intrinsic relative DER measurement error for all reference points, calculated using Formula (9.14), do not exceed the limits of permissible intrinsic relative error add calculated using Formula

)%30(.

HKadd , (9.16)

where

H – DER value, μSv/h; К – coefficient = 10.0 μSv/h.

9.8.3.8 Calculate permissible intrinsic relative error of - radiation flux density measurement

for BDAB in the following way: 1) connect BDAB to BDOI, switch BDOI on and select - radiation flux density

measurement mode; 2) open β- filter. Place the detector successively very close to the reference sources, 239Pu,

second category, 4P9, 5P9 or 6P9 type so that the detector surface is parallel to the source surface. At that detector geometrical center must be perpendicular to geometric center of detector sensitive surface with 2 mm accuracy. Press the START button. Read measured values of - radiation flux density when statistical error is less than 5 %;

36

3) test intrinsic relative error in the reference points according to the Table 9.3 Table 9.3

Flux density at reference point, оj, min-1cm-2 Measurements quantity, n Statistical error, %, no

more than 10-30 5 5

400-600 5 5 4000-6000 5 5

40000-60000 5 5 200000-400000 5 5

4) do five measurements of alpha- radiation φij, as stated in item 2) in every reference point.

For every next measurement turn the reference source around the source geometric surface for 72 approximately (relative to the previous source position);

5) calculate average value j of - radiation flux density for every reference point, using Formula

5

151

iijj ; (9.17)

6) calculate intrinsic relative measurement error of flux density Qj, %, for every point, using the Formula

oj

ojjjQ

, (9.18)

where oj – density of particle flux from active surface of the reference source as of the test time, min-1см-2;

Verification results are considered positive if values of confidence limits of the intrinsic relative measurement error of BDAB - radiation flux density for all verifiable points, calculated using the Formula (9.18), don’t exceed the limits of permissible intrinsic relative error add, calculated using the Formula

)%20( Aadd , (9.19) where А − coefficient equal to 10 min-1·cm-2;

φ – measured value of - radiation flux. 9.8.3.9 Calculate intrinsic relative measurement error of β- radiation flux density for BDAB in

the following way: 1) connect BDAB to BDOI. Switch BDOI on and select β- radiation flux density

measurement mode; 2) close β- filter on the detection unit and place the detector very close to the reference source

90Sr+90Y of the type 4SО, 5SO or 6SO, second category, so that the detector surface is parallel to the source surface. At that the geometric center of the source surface must be perpendicular to the geometrical center of the detector sensitive surface with 2 mm accuracy. Press OK button. When statistical error value will be less than 5 %, press the STOP button;

3) open β- filter on the detection unit and install -filter. Install detector in the same position on the same reference source and press the START button. Read measured values of β- radiation flux density ij when statistical error will be less than 5 %;

4) using the same source, do measurements according to items 2), 3) in the four mutually perpendicular directions when the detector center moves by 15 mm relative to the source center;

5) do verification according to items 2) – 4) in reference points according to the Table 9.4

37

Table 9.4 Flux density at reference

point, оj, min-1cm-2 Measurements

quantity, n Statistical error, %, no

more than 10-60 5 5

200-600 5 5 2000-6000 5 5

20000-60000 5 5 600000-900000 5 5

6) calculate average value of β- radiation flux density j for every reference point, using Formula (9.17);

7) calculate confidence limits of permissible intrinsic relative measurement error of , flux density, %, at confidence probability 0.95, using Formula (9.18).

Verification results are considered positive if values of confidence limits of intrinsic relative measurement error of β- radiation flux density of BDAB detection unit for all verified points, calculated using the Formula (9.18), don’t exceed the limits of permissible intrinsic relative error add., calculated using Formula

)%20( Aadd , (9.20) where А – coefficient equal to 100 min-1·cm-2;

φ – measured density of β- radiation flux density.

10 Disposal

BDG1 constitutes no danger to life, health and the environment, so disposal is performed in a regular way.

38

Appendix A

(reference)

Standard dependence of the upper limit of the measuring range of DER of gamma radiation energy Eγ scintillation detection channel

0

20

40

60

80

100

120

0 500 1000 1500 2000 2500 3000 3500

Energy gamma radiation Еγ , keV

DE

R,

uSv/

h

Figure A.1