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Thermo Electron EPD MK2, Technical Manual

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EPD/HB/40521/

 

000                                      

ELECTRONIC PERSONAL DOSEMETER HANDBOOK

 

TECHNICAL DESCRIPTION 

ISSUE 5 

Page 54 

 

 

Thermo

 

Averaging time constants used to calculate penetrating dose rate Hp(10)/h 
maximise at 60 seconds below 70uSv/h and therefore the statistical errors 
increase as the dose rate drops below 70uSv/h.  Additional processing is used to 
provide faster response but with reduced accuracy when rapid changes in dose 
rate are observed.  The algorithm is a compromise that reduces statistical errors 
but gives a fast response time.  The dose rate displays on the LCD are limited to 2 
significant digits.  
 
Longer time constants have to be used when averaging the beta dose due to the 
lower sensitivity of the beta detectors.  The time constant used maximises at 100 
seconds below 1mSv/h.  Due to limitations in the processing and memory 
available, this time constant cannot be reduced when rapid changes are 
observed, and the Hp(0.07)/h dose rate is approximated as the sum of Hp(10)/h 
and the beta dose rate.  This approximation means that at low gamma energies 
(below 50 keV) the Hp(0.07)/h dose rate typically under-responds by up to 25% in 
comparison to the Hp(0.07) dose response.  However, above 25 keV the dose 
rate response remains within 

±

30% accuracy criteria. 

 

Peak Dose Rate 

 
The highest dose rate calculated by the EPD since this value was last cleared is 
termed the peak dose rate.  The peak dose rates and the times at which these 
peak rates occur are recorded and can be displayed on the LCD or read over the 
IR communications link. 
 

Note

:  Peak dose rate times are stored to 1 second resolution. 

 

4.6.6 Counts 

The EPD has four internal counters: 

 

♦ 

HG: Hard 

Gamma 

♦ 

SG: Soft 

Gamma 

♦ 

FB: Full 

Beta 

♦ 

BC: Beta 

Compensating 

 

These record the pulses output by each of the radiation detectors. 
 
The EPD calculates the Hp(10) and Hp(0.07) doses by weighted summing (ratios 
set during calibration) of the counts received on the four detector channels.   
 
Counts can only be read via the IR communications link, although the least 
significant digits are visible on the internal counts display ( section 3.5 ).  

Summary of Contents for EPD MK2

Page 1: ...EPD HB 40521 000 EPD MK2 Beta Gamma Sensitive Electronic Personal Dosemeter Technical Manual February 2004 ...

Page 2: ......

Page 3: ...ON CORPORATION AND IS SUPPLIED FOR USE ONLY IN CONNECTION WITH THE OPERATION AND OR MAINTENANCE OF THE EQUIPMENT TO WHICH IT RELATES AS SUPPLIED BY THERMO ELECTRON CORPORATION THE CONTENTS MUST NOT BE USED FOR OTHER PURPOSES NOR DISCLOSED TO ANY THIRD PARTY WITHOUT THE PRIOR WRITTEN CONSENT OF THERMO ELECTRON CORPORATION Thermo Electron Corporation Sopers Lane Poole Dorset BH17 7ER England Tel 012...

Page 4: ......

Page 5: ...om BH17 7ER e mail service epd uk thermo com Tel 01202 782740 Fax 01202 782056 USA Sales Office Thermo Electron Corporation Environmental Instruments Division Radiation Measurement Protection 105C Hembree Park Drive Roswell Georgia 30076 U S A e mail epdsupport rmp thermo com Tel 770 521 4500 Fax 770 521 4535 ISSUE STATE Pages Issue Type Part ID File ID Change Ref Front Sheet 5 ESERS EPD HB 40521 ...

Page 6: ......

Page 7: ... VISIBLE ALARMS 16 3 2 1 Alarm features 16 3 2 2 Dose Alarms 20 3 2 3 Dose Rate Alarms 20 3 2 4 Over Range Indication 21 3 2 5 Alarm Muting 22 3 3 BUTTON OPERATION AND DISPLAY SELECTION 23 3 4 LCD DISPLAY LOCK ON FACILITY 24 3 5 DISPLAY OPTIONS AND BUTTON FUNCTIONS 26 3 5 1 Displaying Hp 10 Dose Dose Rate and User ID 26 3 5 2 Displaying Hp 0 07 Doses Dose Rate and ADS User ID 27 3 5 3 Displaying T...

Page 8: ...8 4 5 2 EPD Configuration via the IR Communications Links 49 4 6 EPD INTERNAL PROCESSING FACILITIES 51 4 6 1 Memory Characteristics 51 4 6 2 Alarm Characteristics 52 4 6 3 Default Display 52 4 6 4 User Identification 52 4 6 5 Dose and Dose Rate 53 Dose 53 Dose Rate 53 4 6 6 Counts 54 4 6 7 Dose Quality Flags 55 i Reset Count 55 ii Knock Time Seconds 55 iii Dose Over range 55 iv Dose Rate Over rang...

Page 9: ...ing Data 72 5 8 2 Clearing faults 72 SECTION 6 79 MAINTENANCE 79 6 1 CALIBRATION 79 6 2 THE EPD BATTERY 82 6 2 1 Replacement Batteries 82 6 2 2 Battery Leakage 82 6 2 3 Lithium Thionyl Chloride Battery Warning 82 6 2 4 Replacing the EPD Battery 84 6 3 EPD CLIP ASSEMBLY 86 6 3 1 Removing the EPD Lanyard Plate Clip Assembly 87 6 3 2 Replacing The EPD Lanyard Plate Clip Assembly 88 6 4 CLEANING 89 6 ...

Page 10: ......

Page 11: ... EPD LCD nomenclature for personal dose Hp 10 H07 EPD LCD nomenclature for personal dose Hp 0 07 H10 h EPD LCD nomenclature for dose rate Hp 10 h H07 h EPD LCD nomenclature for dose rate Hp 0 07 h Hp 10 Personal dose equivalent at a depth of 10mm of tissue penetrating deep or whole body dose Hp 0 07 Personal dose equivalent at a depth of 0 07 mm of tissue superficial shallow or skin dose Hp 10 h H...

Page 12: ...erence Short press A short press and release of the button Sv Sievert SI unit of dose equivalent T Tesla TLD Thermoluminescent Dosemeter Total Dose Intended to be a secure record of the total accumulated dose received since Dosemeter issue alarms do not apply to total dose User ID A numeric code of up to 12 digits that may be written to the EPD to define the current user or wearer By convention a ...

Page 13: ... READ AND TAKE NOTE OF THE MANUFACTURERS WARNINGS ON THE BATTERY CASE READ ALSO THE DETAILED LTC BATTERY WARNINGS IN THIS HANDBOOK Sulphurous Oxychloride SOCL2 Cautions EPD batteries Batteries are susceptible to fire and abuse Some manufacturers provide batteries with a safety vent which allows a controlled release of electrolyte if fire and abuse conditions prevail If the EPD has been damaged in ...

Page 14: ......

Page 15: ...de detectors Each detector feeds a chain of dedicated amplifiers and counter circuits to measure soft gamma hard gamma and beta radiation The outputs from each detector chain are processed to calculate and display penetrating and superficial dose and dose rate Other functions include EEPROM storage of detected radiation annunciation of alarm conditions LED and sounder Infra red IR communication an...

Page 16: ...86 x 62 x 18 5 mm excluding clip Alarm sounder 98 101 dB on loud 4kHz setting Quiet and 2 kHz settings available Dose chirp function on Hp 10 dose The EPD also has the following major features Improved immunity to radio frequency interference RFI Display Backlight EPD communication via an infra red interface up to a range of approximately 1 metre Improved dose profile facility Real time dose chirp...

Page 17: ...s displayed to the user on a LCD display on the top of the EPD see Figure 2 1 To minimise the loss of data from battery or other failure data is saved to secure memory within the EPD every 15 minutes Data is written to and read from the EPD via an integral infra red communications interface The Thermo supplied EasyEPD2 program reads and writes data to the EPD via the Infra red communications link ...

Page 18: ... Removing replacing the EPD battery Removing replacing the EPD clip assembly Clearing fault conditions where possible Checking the functionality and calibration of the EPD Keeping the unit clean Note 1 This manual deals with Sieverts Sv throughout To convert to rem multiply all values by 100 ...

Page 19: ...orrectly and is functionally operational 2 1 Setting up The EPD requires very little setting up Setting up is primarily confined to 1 Unpacking the EPD 2 Inserting the battery 3 Checking the initialisation sequence 4 Checking the default settings 5 Performing a confidence test A general view of the EPD is shown in Figure 2 1 External features are described in Table 2 1 Figure 2 1 External View Of ...

Page 20: ...n EPD alarm Clip Assembly Provides a means of attaching the EPD to clothing or for attaching a lanyard as an alternative means of wearing the EPD Table 2 1 EPD External Features 2 1 1 Unpacking The EPD There are no special unpacking instructions Depending on customer requirements the EPD may or may not be shipped with a battery and or a clip assembly Alternatively the EPD may be shipped with just ...

Page 21: ...es a special tool The coin type battery cap should be rotated using a small coin circa 20 mm diameter and 2 mm thick Figure 2 2 Battery Cap Types and Special Tool The battery cap also provides the return path for the EPD s power supply Therefore during fitment of either type of battery cap the EPD will begin its start up sequence see Section 2 1 3 If the battery cap is not fitted cleanly and conta...

Page 22: ...ype locate the coin in the groove in the battery cap iii Maintain steady pressure on the special tool or coin so as to keep it fully engaged in the battery cap and rotate the battery cap through approximately 85 in a counter clockwise direction to remove cap see Figure 2 3 If a battery is already fitted the cap will normally release from the case under the action of the battery cap compression spr...

Page 23: ...l tool or coin as required maintain pressure on the battery cap against its compression spring and rotate the battery cap in a clockwise direction through approximately 85 to its end stop Rotate the cap slowly to the point where the resistance of the end stop is felt Avoid use of excessive force 2 1 3 Start up Sequence When a battery is inserted into the EPD fitment of the battery cap will automat...

Page 24: ...uence is automatic and should be visually confirmed as each step initiated 1 All segments of the display are activated for approximately 5 seconds This allows the user to check that all segments are functional see Figure 3 2 2 The alarm will sound and the LED will flash for approximately 2 seconds This indicates that the sounder and LED are functional 3 The all segment display will disappear The a...

Page 25: ...thing has the major advantage that the user can read the EPD s LCD display and operate the button as required Typically the EPD should be worn on the chest or the waist The type of outer protective clothing will determine how the EPD is attached i e the EPD clip or lanyard For example if the protective clothing has no breast pocket or the use of a belt is prohibited the lanyard may be the most pra...

Page 26: ...NDBOOK GETTING STARTED ISSUE 5 Page 12 Thermo WARNING DURING OPERATIONAL USE THE EPD MAY BECOME EXPOSED TO RADIOACTIVE CONTAMINATION THE EPD MUST BE SUBJECT TO ALL RELEVANT DECONTAMINATION PROCEDURES LAID DOWN BY THE RADIOLOGICAL PROTECTION AUTHORITY ...

Page 27: ...ettings and other display controls are changed using a suitable IR communications link and software e g EasyEPD2 For example the display can be configured to display values in either Sieverts or rems The EPD is provided with many different displays in order to provide a powerful stand alone facility for users not having direct access to communications software such as EasyEPD2 However for many use...

Page 28: ...EPD HB 40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK OPERATING INSTRUCTIONS ISSUE 5 Page 14 Thermo The backlight activation causes a temporary alarm muting effect see section 3 2 5 ...

Page 29: ...ELECTRONIC PERSONAL DOSEMETER HANDBOOK EPD HB 40521 000 OPERATING INSTRUCTIONS ISSUE 5 Thermo Page 15 Figure 3 2 LCD Display Segments ...

Page 30: ... operation for example for office or hospital environments Alarms are acknowledged by pressing the button long press This action will extinguish the alarm LED and mute the sounder It is possible to disable the mute function via the EPD IR communications link see section 3 2 5 Note that certain operations and events will automatically mute the audible alarm for a short period because of the high el...

Page 31: ... duration is set in increments of 4 seconds Assuming an alarm is not acknowledged then following this period the alarm is replaced by a single beep every 30 seconds This feature avoids wasting battery power The timeout can be disabled if desired and the alarm output is not then so curtailed Alarm Feature Configuration Options Alarm Sound Off Volume Loud Quiet Continuous Single Tone LED Enabled Dis...

Page 32: ...arm is activated the new alarm starts The user mutes alarms with a long button press all mute able alarms are muted Alarms are cleared via the communications links A self cancelling condition de activates the alarm e g falling dose rate Care should be taken if the alarm configurations are altered from the defaults set by Thermo and the following points should be noted 1 The alarm priorities are fi...

Page 33: ...____ High Loud 5 Hp 10 Dose Alarm 1 Continuous Single Tone ____________ High Loud 6 Hp 10 h Dose Rate Alarm 2 Continuous Single Tone ____________ High Loud 7 Hp 0 07 h Dose Rate Alarm Intermittent Single Fast Tone _ _ _ _ _ _ High Loud 8 Hp 10 h Dose Rate Alarm 1 Intermittent Single Fast Tone _ _ _ _ _ _ High Loud 9 Battery Alarm Intermittent Single Slow Tone __ __ __ __ Low Quiet 10 Return Alarm ...

Page 34: ...ser silence is inhibited The four most significant digits of the alarm thresholds can be viewed on the EPD LCD and changed using the function button see Section 3 5 8 3 2 3 Dose Rate Alarms Dose rate alarms are checked and updated every second except at low dose rates where this period increases to a maximum of 14 seconds Alarms can be adjusted or inhibited via the IR communications link The dose ...

Page 35: ...r a temporary dose rate over range condition has cleared The over range conditions are recorded in the EPD EEPROM and must be cleared over the IR communications link before the display will stop flashing 2 The over range alarm can be muted if enabled The EPD audible and Led alarm will not recur after muting should over range conditions re occur e g in the case of a second dose rate over range alar...

Page 36: ...te alarms are self muting when the dose rate falls below the alarm off threshold level Similarly dose alarms are self muting if the dose is cleared or the thresholds suitably increased over the IR communications link Note that if the display backlight is enabled a short press of the button turns the back light on and temporarily silences any active alarm This is because the EPD unit battery cannot...

Page 37: ...are disabled are removed from the sequence Some displays are usefully disabled if their retention might confuse the wearers of the EPD Other displays should be disabled if their retention might cause an operational risk for example the ability to zero dose or adjust alarm thresholds Such display configuration is easily done using the EasyEPD2 software package A batch write facility is available in...

Page 38: ...times out The colon will only appear for approximately two seconds To accept the lock on facility press the button when the colon appears If the lock on facility is not required allow the selected display to time out To deselect the lock on facility press the button The display will move on to the next display selection but will thereafter revert to the default display after time out The seconds c...

Page 39: ...tdown Timer 5 Power Saving 6 Peaks Rate High 7 Test 8 Clear Peak H10 Dose Rate Peak H07 Dose Rate H10 and H07 Dose Clear Clr 9 Dose Alarm Thresholds 1st H10 Dose Alarm 2nd H10 Dose Alarm H07 Dose Alarm 1st H10 Dose Rate Alarm ON 2nd H10 Dose Rate Alarm ON H07 Dose Rate Alarm ON 10 Dose Rate Alarm ON Thresholds Rate On 11 Dose Rate Alarm Off Thresholds Rate Off 12 Sound Settings 1st H10 Dose Rate A...

Page 40: ...ton within the display default time out 3 5 1 Displaying Hp 10 Dose Dose Rate and User ID To display Hp 10 doses press and hold the button until this top level display appears Three sub displays are available in the following sub display order Hp 10 Dose Hp 10 h Dose Rate User ID Digits Hp 10 Dose Display Short press the button to display the current dose This dose parameter is used for tactical d...

Page 41: ...y a User ID will have fewer than 12 digits but it must be an integer between 1 and 999999999999 For example a User ID 9012 will be shown on the LCD display as follows First Display Second Display Third Display In systems using 8 or fewer digits for the User ID it is usual to disable and thereby remove the unused displays e g the first and second display in the above example For software version 11...

Page 42: ... 0Sv h auto ranging Note Over range 1 0 Sv h is indicated with a flashing LCD display see section 3 2 4 This condition is latched to warn the user that the dose value may be inaccurate ADS User ID Digits An additional User ID is provided called Approved Dosimetry Service ADS User ID This is password protected and is used by ADS systems for permanent issue EPDs The ADS User ID may be displayed in a...

Page 43: ...OOK EPD HB 40521 000 OPERATING INSTRUCTIONS ISSUE 5 Thermo Page 29 In systems using 8 or fewer digits for the ADS User ID it is usual to disable and thereby remove the unused displays e g the first and second display in the above example ...

Page 44: ...the total Hp 10 dose Display Range Hp 10 0µSv to 16Sv auto ranging Hp 0 07 Total Dose Short press the button again to display the total Hp 0 07 dose Display Range Hp 0 07 0µSv to 16Sv auto ranging Each display represents a record of the total dose received by the EPD over multiple tasks e g per day per week etc 3 5 4 Starting Stopping The Seconds Count Down Timer To start stop the seconds count do...

Page 45: ...maximum count down time available is 99 minutes 59 seconds The count down function continues when the display reverts to the default display after the display timeout period However it is useful to lock on to this display as described in section 3 4 Stopping the Timer To stop the timer double press the button again The digits will stop decreasing Reset Short press the button to select the display ...

Page 46: ...the IR communications link 3 5 6 Displaying Peaks Rate High To display peaks high rate press and hold the button until this top level display appears Two sub displays are available in the following sub display order Peak Hp 10 h Dose Rate Peak Hp 0 07 h Dose Rate These displays show the highest dose rate that the EPD has measured since the peaks were last cleared The peak dose rates measured are r...

Page 47: ...seconds This allows the user to check that all segments are functional see Figure 3 2 2 The alarm will sound and the LED will flash for approximately 2 seconds This indicates that the sounder and LED are functional 3 The all segment display will disappear The alarm will continue to sound and the LED will continue to flash at an increased rate for approximately 6 seconds This indicates that the LCD...

Page 48: ...ose Alarm Thresholds To display and or set dose alarm thresholds press and hold the button until this top level display appears Three sub displays are available in the following sub display order 1st Hp 10 Dose Alarm 2nd Hp 10 Dose Alarm Hp 0 07 Dose Alarm The EPD can be used as a personal alarming dosemeter with alarm thresholds for accumulated dose alarms This mode displays the current settings ...

Page 49: ...following with the digits flashing Alarm Set Limits 10µSv to 1Sv Pressing the button will increase the alarm threshold in the following steps 10µSv 50µSv 100µSv 500µSv 1mSv 5mSv 10mSv 50mSv 100mSv 500mSv 1 0Sv When the required threshold is reached double press the button to confirm the value and the flashing display will stop If you start to change the threshold and change your mind this option c...

Page 50: ...arm OFF The EPD can perform the role of a personal alarming EPD with alarm thresholds for dose rate There are two Hp 10 h dose rate alarms and a single Hp 0 07 h dose rate alarm that can de displayed The 2nd Hp 10 h dose alarm has the higher priority and should always be set to a higher value than the 1st Hp 10 h alarm The alarm thresholds can be modified by the user if required but only when the ...

Page 51: ...he following and the digits will flash Alarm Set Limits 10µSv h to 1Sv h Pressing the button will increase the alarm threshold in the following steps 10µSv h 50µSv h 100µSv h 500µSv h 1mSv h 5mSv h 10mSv h 50mSv h 100mSv h 500mSv h 1 0Sv h When the required threshold is reached double pressing the button to confirm the value and the flashing display will stop If you start to change the threshold a...

Page 52: ...eep Enable Disable Dose Chirp Adjustment Internal Counters Display Note This option will not enable disable the alarm sounder Enabling disabling the sounder under alarm conditions can only be set via the IR communications link see Section 3 2 4 Button Beep Enable Disable The EPD can be configured to beep every time the button is pressed This feature may be toggled on and off via the button or via ...

Page 53: ... current dose per chirp An increment set to 1µSv is shown opposite With a chirp sensitivity of 1µSv chirp and a dose rate of 10mSv h the sounder will average 2 8 chirps every second To change the chirp rate double press the button at current dose chirp display The display digits will flash Dose Chirp Limits 0 01µSv to 100µSv Note 0 Off no chirp function Pressing the button will increase the dose p...

Page 54: ...d If the ESC screen is displayed and the button is not pressed after default time out the display will return to dose chirp adjustment display Again if the button is not pressed the display will return to the top level default screen after a further time out period Internal Counters Display Short press the button to display the current internal counters display The display is in hexadecimal format...

Page 55: ...specification is given in Appendix A to this handbook Sensitivity to X and γ radiation β particles Multiple PIN diode detectors 4 channel parametric algorithm processing Direct readout of personal dose equivalents Hp 10 penetrating deep whole body and Hp 0 07 superficial shallow skin Neutron response 2 Meets relevant parts of BS EN ISO61526 for dose equivalent monitors unless otherwise specified D...

Page 56: ...ng is inhibited during detector test for a period of 1 to 2 ms Battery Test Configurable time interval between 1 to 60 minutes 15 minutes recommended Alarm sounder 98 dB A to 101 dB A at 20 cm 4kHz loud mode 80 dB A to 90 dB A at 20cm 4kHz quiet mode 4 2 2 Battery Management The EPD circuitry is designed to operate at 3 6V DC The EPD can be powered by either a 3 6V Lithium Thionyl Chloride LTC Sul...

Page 57: ...he following information available over the IR comms link Type of battery currently fitted Low volts Alkaline or high voltage Lithium Thionyl Chloride The current battery voltage measured at the last battery load test normally every 15 minutes The current regulated circuit voltage measured within the last 14 seconds The battery voltage threshold at which the battery low warning is raised for low v...

Page 58: ... off see also Section 3 5 5 In the EPD OFF condition battery drain is reduced to approximately 20 of the drain when the EPD is in the ON condition i e fully operational The EPD does not measure radiation when it is OFF Alternative OFF Display EPDs of software version 11 and later may be configured to display a 4 digit Hexadecimal value instead of the OFF display The 4 digit hex value may be writte...

Page 59: ...er conductive liner an outer case assembly and lid The inner liner houses the EPD s electronic components The outer case consisting of a moulded front and back fits around the inner liner and is fused together to provide physical protection The lid which is fitted to the top of the outer case has a tight tolerance and is locked in place as an integral part of the EPD assembly The outer case and li...

Page 60: ...EPD HB 40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK TECHNICAL DESCRIPTION ISSUE 5 Page 46 Thermo Figure 4 1 EPD Dimensions ...

Page 61: ...inst dust and against low pressure jets of water from all directions Vibration IEC 1526 2g 15 min 10 33 Hz Shock 1 5 m drop on each surface onto concrete EMI EMC Exceeds MIL STD 461D RS103 see Appendix B 4 4 2 Brief Environmental Description The EPD is designed for use in the following environments Office and Laboratory environment Industrial environments Hospitals Military environments including ...

Page 62: ...unctionality can be set During the read write process the EPD can be configured for any or all of the display selections shown in Figure 3 4 to be made available to the user as required Only limited functions can be configured via the EPD button On the front of the EPD there is an IR communications link for reading and writing data Communication with the EPD is usually via an IR adapter which is c...

Page 63: ...entification Dose and Dose Rate Alarms and Alarm Thresholds Counts Dose Quality Control of the EPD Status Scratch Pad Timed Events Dose Profile Special Total Dose Store ADS Issue Calibration Parameters Access to these configuration parameters is restricted as follows 1 CALIBRATION FACTORS Write access to calibration parameters is prevented unless the EPD is configured by the manufacturer with cali...

Page 64: ...m the EPD The alarm times cannot be set to less than 10 minutes The following Alarm Control settings may also not be changed from the factory configuration Battery alarm level 1 Battery Alarm Level 2 Battery Type Discriminator Regulated voltage alarm level LCD Decimal Point position and display units PTB EPDs are configured such that the settings for decimal places dose units off display wearer di...

Page 65: ...re short term Hp 10 and Hp 0 07 Can be reset after each controlled area entry day month etc by health physics staff or dose management system according to local procedures Total Dose Store Separate total dose store Special Total Dose Store 12 entries e g for automatic recording of end of month dose etc Event Log 23 entries for time recording of alarms etc for incident assessments ADS Dose Store Ap...

Page 66: ...lternative default display as specified by the customer User selected displays have a time out period which can be set between 10 to 99 seconds This time out is the period of time that any display selected by the user will stay active before reverting to the default display The time out period may be adjusted via the IR communications link The default display can be changed to any of the displays ...

Page 67: ... heavily dropped or a passivated battery fitted up to 15 minutes of accumulated dose may be lost Such events however are detected and a count of resets provided as quality data associated with the accumulated dose see section 4 6 7 Note that from software version 11 EPDs it is possible to configure the EPD to make additional logs to the non volatile memory at 1 minute intervals if the dose receive...

Page 68: ...e is approximated as the sum of Hp 10 h and the beta dose rate This approximation means that at low gamma energies below 50 keV the Hp 0 07 h dose rate typically under responds by up to 25 in comparison to the Hp 0 07 dose response However above 25 keV the dose rate response remains within 30 accuracy criteria Peak Dose Rate The highest dose rate calculated by the EPD since this value was last cle...

Page 69: ...communications link d by a software reset e by a fault condition Note that the EPD loses recent dose received since the last log of dose to non volatile memory as described in section 4 6 5 ii Knock Time Seconds The EPD detectors are susceptible to large mechanical shocks This is overcome by detecting the shock with a piezo knock detector The EPD continues to accumulate dose during the shock perio...

Page 70: ...inuously for greater than 15 seconds see Knock Time Seconds vii CRC Failure The CRC failure flag is set as a result of an integrity check on a set of data indicating that the EPD detected a checksum error in the dose data Checksum failures are corrected by retrieving the last stored dose from secure store EEPROM During the correction process up to 15 minutes of dose may be lost viii Low Voltage EP...

Page 71: ...nd dose alarms and the Hp 0 07 h dose rate alarm are each provided with separate ON and OFF thresholds When the dose rate equals or exceeds the alarm ON threshold the EPD will set an alarm flag and the sounder will sound and the LED flash if enabled The alarm is self cancelling when the dose rate falls below the alarm OFF threshold but the alarm flag remains set Alarm thresholds are set via the IR...

Page 72: ...ed This is the present state of the issued flag either EPD Issued or EPD Not Issued 3 Detectors State This is the current state of the EPD s operating mode i e ON or OFF Alarms The EPD retains a record defining which of the following alarms has occurred The record is normally cleared by system software at the start of an issue period 1 3 Dose Alarm Flags As section 4 6 8 2 3 Dose Rate Alarm Flags ...

Page 73: ...ximum of nine spare sectors 6 Detector Test Fail The EPD detector test was run and the number of counts received were less than required to pass the test 7 Detector Threshold Fail The EPD detector thresholds failed to load successfully 8 Radio Fail Reserved for future use 9 Other Fault A fault occurred causing the EPD to reset 10 Disabled The EPD is not calculating dose ...

Page 74: ...s a dose profile the minimum interval between entries in the dose profile is adjustable between 2 seconds to 35 hours in 2 second intervals The store holds up to 579 records for transitions up to 127 µSv or less Note A dose profile interval of zero seconds turns off the dose profile function Dose profile can only be read via the IR communications link Dose profile may be synchronised to a particul...

Page 75: ... by EasyEPD2 200 Failure Alarm on 220 Clear Faults 201 Over Range Alarm on 221 Over Range Alarm off 202 Hp10 Dose Alarm 2 on 222 Hp10 Dose Alarm 2 off 203 Hp07 Dose Alarm on 223 Hp07 Dose Alarm off 204 Hp10 Dose Alarm 1 on 224 Hp10 Dose Alarm 1 off 205 Hp10 Rate Alarm 2 on 225 Hp10 Rate Alarm 2 off 206 Hp07 Rate Alarm on 226 Hp07 Rate Alarm off 207 Hp10 Rate Alarm 1 on 227 Hp10 Rate Alarm 1 off 20...

Page 76: ...EPD HB 40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK TECHNICAL DESCRIPTION ISSUE 5 Page 62 Thermo This page intentionally blank ...

Page 77: ...s the fault conditions that can occur and describes the recovery procedure if any to be taken to restore the EPD to operational use The section is organised as follows 1 Fault indication via sounder alarm Led LCD 2 Internal logging of fault conditions 3 Blank display and other uncontrolled faults 4 Communications Error over the IR link 5 LCD Display error codes 6 Recovery Procedures ...

Page 78: ...low intermittent rate If alarm mute is enabled for the fault alarm the sounder can be silenced and the alarm Led extinguished by the action of pressing and holding the button The fault alarm can also be set to self mute after a timeout period in order to preserve battery life If this happens the unit will give a short sound every 30 seconds thereafter An EPD conveys faults to the user by a number ...

Page 79: ...red 5 Bad Sectors The number of bad EPD secure store sectors There is a maximum of nine spare sectors 6 Detector Test Fail The EPD detector test was run and the number of counts received were less than required to pass the test 7 Detector Threshold Fail The EPD detector thresholds failed to load successfully 8 Radio Fail Reserved for future use 9 Other Fault A fault occurred causing the EPD to res...

Page 80: ...tors A number of faults and events are counted and recorded in association with the measured dose They are zeroed when the dose is zeroed and are subsequently read with the dose These are referred to as the dose quality factors and are described in section 4 6 7 Non zero dose quality factors imply that there may be an error in the dose reading due to the way the product has been used rather than d...

Page 81: ...ttery and restart unit see section 2 1 2 Communicate with the EPD via the IR communications link to access stored data Remove and replace battery cap see Section 2 1 2 Use a recommended battery Static Screen Heart Beat indication not flashing 1 second timer error Attempt to communicate with the EPD via the IR communications link Replace battery and restart unit see section 2 1 2 Communicate with t...

Page 82: ...D No visual alarm during Confidence Test LED fails to operate in alarm condition Hardware fault LED Disabled Contact supplier Enable LED if required Faulty Display Missing or additional segments on LCD display Hardware fault Confirm fault by running a CONFIDENCE TEST Contact supplier Table 5 1 Blank LCD other faults ...

Page 83: ...dicates a communications error This condition usually occurs when a data write operation fails to complete The typical cause is that the EPD unit is removed from the IR field before a critical write operation has completed for example an Issue of the EPD to a person The error which is accompanied by an audible alarm alerts the user that the EPD is not in a valid operational state However as descri...

Page 84: ...clear the alarm and LCD display automatically when the EPD is re presented to the IR media The system software then checks the status of the EPD completes any necessary data write operations advises the user what to do and clears the alarm The display then returns to normal If the condition arises regularly then this may indicate a problem in the design of the system software i e the user interfac...

Page 85: ...owed by a 3 digit error The error code number is also logged in the Event History store with date time data As an example the following shows fault F095 A list of EPD error codes is given in Table 5 2 They are divided into blocks according to the software module that generates them Epd Action This describes what the EPD does in addition to attempting to display the fault and record the fault in th...

Page 86: ...e EPD Status Faults record 3 Contents of internal Event History store 4 Dose and peak dose rate time data if a spurious dose fault is suspected 5 Dose profile data if a spurious dose fault is suspected Where possible the data should be obtained as screen dumps from EasyEPD2 and attached to the completed Fault Log Form Appendix D If a faulty unit is to be returned to Thermo it must be returned in a...

Page 87: ...ther problems may well occur before this time 014 Control Module Stack Overflow Reset ditto Only runs from self test typically every 15 minutes Other problems may well occur before this time 015 Control Module Asic Fault Halt Return to supplier This test performs a read write test on the digital ASIC Unrecoverable other knock on errors may occur Replace ASIC 016 Control Module Unexpected Battery L...

Page 88: ...ice Module stAdsData CRC faulty Reset unit Return to supplier if recurs 035 Service Module Seconds Timer Array overflow Reset Reset unit Return to supplier if recurs This indicates a software fault 036 Service Module Fine Timer Array overflow Reset Reset unit Return to supplier if recurs This indicates a software fault 037 Service Module Long Timer Array overflow Reset Reset unit Return to supplie...

Page 89: ...e entry number is invalid Return to supplier This fault is unlikely to occur Sector Access Table is corrupted or EEPROM read failed 063 EEPROM could not read from the sector access table area Return to supplier Executes a Deferred Log Fault with RECOVERED option with the given fault code but only if the EEPROM fail bit is not set If the EEPROM fail bit is set the fault is ignored to stop the error...

Page 90: ... This is not possible unless clock is written with new value or incremented at wrong rate 085 Count too large HG or SG 300 000 or FB or BC 26 000 Reset Ditto This fault can occur by inputting a very large number of counts only possible under test conditions or severe interference 086 Detector threshold load failed Reset into comms mode only counts processing disabled Reset unit Return to supplier ...

Page 91: ...first This means that good data is read back from the EEPROM For the ADS and Dose data the QF bits are also set This is done by reading the data from EEPROM setting the bit calculating the new checksum restoring the data to EEPROM and then doing a reset The correct values will then be restored on program restart Reset unit Return to supplier if recurs Indicates corruption of data in RAM Up to 15 m...

Page 92: ...EPD HB 40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK FAULTS AND RECOVERY ACTIONS ISSUE 5 Page 78 Thermo This page intentionally left blank ...

Page 93: ...ation other than by Thermo However where expressly requested by customers in their purchase order EPDs may be supplied with the calibration factors in the unlocked sate This is to enable such customers to modify the calibration of these EPDs In such cases the customers attention is drawn to the following Disclaimer DISCLAIMER The EPDs within this shipment have been calibrated using the factors as ...

Page 94: ...07 SGSens07 FBSens07 BCSens07 Where EPDs are provided with calibration in the unlocked state see above it is these six factors which may be adjusted within the defined percentages from the manufacturers original calibration These gain adjustments are made using software facilities available via Thermo Electron but should only be considered in consultation with Thermo Detector Thresholds Detector t...

Page 95: ...rmo Page 81 A change in EPD calibration is usually indicative of a fault in the EPD and due to the complexity of achieving calibration over the full energy range it is recommended that any EPDs that fail calibration checks are returned to the manufacturer for repair or replacement ...

Page 96: ...cell Procell Alkaline 1 5 V MN 1500 Other AA batteries may be suitable but Thermo should first be consulted especially in the case of Lithium batteries The user is also advised that 1 The length of the battery including the battery anode pip should be in the range of 49 0 mm to 51 0 mm 2 The diameter of the battery should be in the range of 13 9 mm to 14 6 mm 3 The diameter of the anode pip should...

Page 97: ... HB 40521 000 MAINTENANCE ISSUE 5 Thermo Page 83 Lithium Thionyl Chloride LTC Sulphurous Oxychloride SOCl2 batteries are potentially dangerous and can be harmful The following warnings are to be observed when inserting replacing the EPD battery ...

Page 98: ...e EPD has been damaged in a manner that could affect the battery care must be exercised during battery replacement The battery may have vented into the EPD case and caused the EPD to become pressurized 5 Electrolyte leakage can normally be detected by the smell of sulphur dioxide and or the presence of electrolyte solutes If a leakage is suspected i the battery should be removed from the EPD using...

Page 99: ...ents The security type battery cap helps to prevent unauthorised removal of the cap and requires a special tool see Section 2 Figure 2 2 During fitment of the battery cap the EPD will begin its initialisation sequence This is intentional and performs the function of EPD start up The procedure to replace insert an EPD battery is described in Section 2 1 2 The initialisation start up sequence is des...

Page 100: ...o the EPD by the lanyard plate The lanyard plate slots into a recess in the EPD case see Figure 6 1 Retaining lugs secure the lanyard plate in position Figure 6 1 EPD Case Clip Assembly Recess The lanyard plate may not be fitted with the spring clip again depending on customer requirements see Figure 6 3 This makes the unit more comfortable to wear with the lanyard when the clip is not required If...

Page 101: ...d plate A view of the lanyard plate spring clip removed is shown in Figure 6 3 Note the tang on the lanyard plate it is not necessary to remove the spring clip from the lanyard plate in order to gain access to the tang Figure 6 3 EPD With Lanyard Plate Bu tto n Pr es s s ee Ha nd bo ok Lo ng Ne xt M en u or M ut e Al ar m Sh ort Ne xt Di spl ay or Lo ck on Do ubl e St art or Se lec t P H O T O N E...

Page 102: ...rity Figure 6 4 Removing The EPD Lanyard Plate Clip Assembly 6 3 2 Replacing The EPD Lanyard Plate Clip Assembly Set the lanyard plate into the recess on the rear of the EPD body This will be found to be much easier if the clip and lanyard plate is kept slightly open using a suitable small separator The plate should sit with its lugs in the lug recesses Push the plate towards the top of the EPD LC...

Page 103: ...he sounder aperture to restore the alarm noise level 6 4 2 Radiological Cleaning WARNING DURING OPERATIONAL USE THE EPD MAY BECOME EXPOSED TO RADIOACTIVE CONTAMINATION THE EPD MUST BE SUBJECT TO ALL RELEVANT DECONTAMINATION PROCEDURES LAID DOWN BY THE RADIOLOGICAL PROTECTION AUTHORITY If radioactive deposits are present the unit should be decontaminated by carefully wiping it over using a disposab...

Page 104: ... DOSEMETER HANDBOOK MAINTENANCE ISSUE 5 Page 90 Thermo 6 4 4 Periodic Cleaning The EPD should be cleaned by wiping it over periodically with a cloth lightly dampened with a solution of water and up to 5 of a neutral water based detergent ...

Page 105: ...7 20 17keV to 1 5MeV Ref Cs 137 30 1 5MeV to 6MeV Ref Cs 137 50 6MeV to 10MeV Ref Cs 137 Photon Hp 0 07 30 20keV to 6MeV Ref Cs 137 50 6MeV to 10MeV Ref Cs 137 Beta Hp 0 07 30 250keV to 1 5MeV average beta energy ref Sr 90 Angular response Hp 10 Cs 137 20 up to 75 Hp 10 Am 241 50 up to 75 Hp 0 07 Sr 90 30 up to 55 Accuracy Hp 10 Cs 137 10 Hp 0 07 Sr 90 20 Dose rate linearity Hp 10 Cs 137 10 0 5Sv ...

Page 106: ...40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK APPENDIX A ISSUE 5 Page 92 Thermo Typical EPD Mk2 Energy Response Kr Sr Y 0 0 2 0 4 0 6 0 8 1 1 2 1 4 10 100 1000 10000 Photon Energy keV Response Hp 10 Hp 0 07 ...

Page 107: ...d Mil 461D RS101 30Hz 100KHz See Chart 1 Note 1 Electrostatic Discharge EN61000 4 2 ESD N A 8KV Radiated Electric Field Emissions EN 50081 1 N A 30MHz 1 Ghz 30dB below Limit Radiated Susceptibility E Field High Field Spot Frequencies CW N A 100kHz 40 Ghz See Chart 2 Note 2 Radiated Susceptibility E Field High Field Spot Frequencies CW with 1kHz 1 µS square wave N A 500MHz 40 Ghz See Chart 3 Note 2...

Page 108: ...F requency H z Amps Metre Chart 1 The tested Mk2 EPDs were not susceptible to H field radiation below the above graph Chart 2 0 200 400 600 800 1000 1200 1400 0 1 1 10 100 1000 10000 100000 Frequency MHz Volts Metre Chart 2 The tested Mk2 EPDs were not susceptible to E field radiation below the above spot frequencies 100kHz 100GHz carrier wave ...

Page 109: ...0521 000 APPENDIX B ISSUE 5 Thermo Page 95 Chart 3 0 500 1000 1500 2000 2500 0 1 1 10 100 Frequency GHz Volts Metre Chart 3 The tested Mk2 EPDs were not susceptible to E field radiation below the above spot frequencies 0 1GHz 100GHz pulsed 1kHz 1µS ...

Page 110: ...EPD HB 40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK APPENDIX B ISSUE 5 Page 96 Thermo This page is intentionally blank ...

Page 111: ...EMC seal Sounder Output Alarms 98 dB A to 101 dB A at 20cm 4kHz loud 80 dB A to 90 dB A at 20cm 4kHz quiet Configuration per alarm High low tone loud quiet off volume control in seven combinations of continuous or fast slow intermittent User mute enable disable control Dose Chirp Real time chirp function with programmable sensitivity 0 01 µSv chirp to 100 µSv chirp From firmware version 11 the chi...

Page 112: ... data transfer Memory Large non volatile store for dosemeter control parameters dose data storage dose profile system scratchpad etc 10 year data retention Issue Return Issue and return times of circa 1 second EPD communications time only Incident assessment Internal event alarm historical log 23 entries for time recording of alarms etc Peak dose rate recording Dose Profile Interval programmable f...

Page 113: ...ay be permanently issued by ADS but also used on an access control system by the same wearer ADS Store Dose and supporting data is accumulated in an additional password protected ADS store System Integration Facilities Messaging Interface A powerful and efficient messaging interface allows fast and secure data transfer and speedy issue and return times Data is protected by 16 bit crc Issue and Ret...

Page 114: ... Scratch Pad A large scratch pad is available in the non volatile store to support various system applications This is especially useful for non networked reader stations and can be used to store wearer access data interim dose readings worker access permissions etc Teledosimetry Virtually all data accesses and transfers available over the normal IR link are also available over the teledosimetry i...

Page 115: ...DIX C ISSUE 5 Thermo Page 101 A a B b C c D d E e F f G g H h I i J j K k L l M m N n O o P p Q q R r S s T t U u V v W w X x Y y Z z 0 1 2 3 4 5 6 7 8 9 Seven Segment Display representation of the character s to the left WEARER NAME EPD LCD LETTER REPRESENTATION ...

Page 116: ...EPD HB 40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK APPENDIX D ISSUE 5 Page 102 Thermo This page intentionally left blank ...

Page 117: ...ELECTRONIC PERSONAL DOSEMETER HANDBOOK EPD HB 40521 000 APPENDIX D ISSUE 5 Thermo Page 103 APPENDIX D EPD FAULT LOG FORM SEE OVER ...

Page 118: ...EPD HB 40521 000 ELECTRONIC PERSONAL DOSEMETER HANDBOOK APPENDIX D ISSUE 5 Page 104 Thermo This page intentionally blank ...

Page 119: ...occurred Fault type e g Display fault Code Customer fault reference EPD returned to supplier Date battery installed Do IR communications still work EPD Status Faults attached Event History attached Dose Profile attached Extracted from EasyEPD2 DESCRIPTION OF FAULT DETAIL OF ACTIONS TAKEN TO RECTIFY FAULT Did fault recur after battery replacement or EPD Reset CONDITIONS PRIOR TO FAULT Environment e...

Page 120: ...EPD FAULT LOG FORM HB40521 ...

Page 121: ...y Management 42 Battery storage 84 Beep button enabling disabling 38 Beta radiation 3 Button Operation 23 C Calibration 79 Falibration factors 49 Case material 45 Cleaning 89 Clearing Dose Displays 34 Clip 45 86 Communicating with the EPD 48 Confidence Test 10 Running the Confidence Test 33 CONTENTS ii CRC Failure 56 D Decontamination 89 Default Display 52 Dimensions 2 46 Display 15 Display Lock o...

Page 122: ... Fault Codes 71 Faults 63 Firmware version 11 21 27 42 43 44 53 56 80 97 100 G gamma radiation 3 General maintenance 3 Getting Started 5 Glossary vi I Infrared IR communication 1 infrared communications interface 98 Infra red Interface 48 Introduction 1 Issue Document i Issuing an EPD 10 K Knock Detector 55 L LCD display 1 15 LCD letter representation 101 LED 17 Lithium Thionyl Chloride 42 83 84 M...

Page 123: ...w 1 P Pocket Clip Lanyard 86 Power 1 PTB Approved EPDs 50 R Recovery Procedures 72 Rem 4 Run Time 58 S Secure Memory 3 Sieverts 3 Silicon Diode detectors 1 3 Start up Sequence 9 T TECHNICAL DESCRIPTION 41 thresholds 34 U USA Sales Office i W Warnings viii 6 7 12 84 89 Wearing an EPD 11 Weight 2 45 X X rays 2 ...

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