EC/IAEA/ISOE WorkshopPortoroz Slovenia April 2002
Electronic Personal Dosimetry
Presented by Andy Weeks
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Personal Electronic Dosimetry
UK Regulatory Framework For Dosimetry ServiceApproval
Clients of the Service
Operation of the Service
Summary of Performance
The Future
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UK Regulations Governing theApproval of Dosimetry Services
UK Health and Safety at Work Act 1976
Ionising Radiations Regulations 1999. (IRR)
Basis Safety StandardsICRP 60Basis Safety StandardsICRP 60
EURATOM DirectivesEURATOM Directives
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UK IRR’s Governing theApproval of Dosimetry Services
Regulation 35 - Enables Health and Safety Executive(HSE) to approve suitable dosimetry Services forsome or all of the following :
Regulation 21 - Routine assessment and recordkeeping for classified persons.
Regulation 23 - Accident dosimetry.
Regulation 12 - Provision of dosemeters or otherdevices for contingencies.
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Dosimetry Services Clients.
lClients are made up of UK operational and decommissioningreactor sites.
lBritish Energy Generation Ltd
l 5 operating AGR reactor sites and 1 PWR.
lBritish Nuclear Fuels plc (BNFL)
l5 operating Magnox reactor site.
l5 decommissioning Magnox reactor sites.
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Dosimetry Services Clients.Approval Status
l5 Operating sites fully approved by HSE.
l7 Sites with approvals pending
l4 Sites processing applications.
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Siemens - Electronic PersonalDosemeter (EPD)
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Siemens - Access ControlWorkstation
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Typical Site HardwareRequirements
Average EPD's per site - 100-200
Average During Outage - 400 (Peak on some site 600)
Average Number of ACW's per site 4 - 7
3- 6 for Controlled Area Access
1 for Training / Spare
1 File Servers per site
2 held centrally as hot spares
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Central Approved Assessment Service
Demonstrates Independence from the employer
Self issue and return of EPD
Secure database on client LAN to accommodate ADSData
Legal dose assessment performed by summation ofworking session and manually assessed doses
Working Sessions doses (a few minutes to severalhours)recorded with personal details to Secure ADSdatabase
The BNFL EPDApproved Dosimetry Service
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Client Sites to demonstrate compliance with ADSStatement of Service
Client sites to provide ADS with Operating Manualand systems of work for EPD dosimetry on theirsite
Demonstrable audit trail for transfer of informationfrom EPD to ADS
Quality Assurance
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Quality Assurance
Clients systems and documentation audited by theADS.
Audit report submitted to Health and SafetyExecutive (HSE) with application to become a clientof the ADS
HSE will visit Client site before approval is given
New certificate of approval issued to the ADS foreach new client.
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Common Corrective Actions
Recording of Training
Specific Work instructions.
External Courses and generic TrainingPackages
Systems for dealing with Computer failure.
Manual Entry Systems.
Disaster recovery.
Interaction with other internal service providers.
IT department providing computer back-upservices.
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EPD Diagnostics
Ability to recalculate dose from raw data
Ability to identify spurious doses caused by e.g.:-
Non ionising radiation. (e.g. RFI)
Drops
EMC interference
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EPD Diagnostics
Siemens EPD has 3 detectors
Counts registered in 4 channels
Hard Gamma (HG)
Soft Gamma (SG)
Beta (B)
Beta Compensated (BC)
Ratios of Channels (HG/SG) (SG/B) and (B/BC)give indication of problems from spurious doses.
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EPD Diagnostics
EPD counter Ratios - HG/SG
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Management of DoseEstimates
Manual Amendments.
Amendments made due to EPD Failure forexample physical damage or battery Failure.
Site Amendments.
Amendments made by the site due to spuriousdoses caused for example by RFI, electrostaticconduction or light leakage through the betawindow.
ADS Amendments.
Anomalous doses identified by the Servicesdiagnostics software.
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Dose Amendments for 2001
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Oldbury-on-Severn PowerStation
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Summary of Performance
Application for approval submitted to HSE February 1997
First Certificate of approval January 2000.
Oldbury Power Station first Client June 2000
By 31/12/2002 Service will have 16 Clients.
Enabled Client sites to control doses to much lower levels
Significant improvement in statistical uncertainties in calculatingsite and group collective dose statistics.
Has proved to be cost affective due to reduced manpowerrequirements for Service and Clients.
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Summary of Performance
EPD Mk 1.2 Performs well in all radiological environmentsencountered on nuclear power plants.
Access control Work Stations and computer systems very reliableand robust.
EPD not as reliable as expected circa 20% return rate for repair.(compared to Hinkley Point Mk 2 EPD’s at circa 2%)
Sensitivity to RFI, EMC, etc irritating.
Poor battery performance.
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The Future
Application to be made to the UK Health and SafetyExecutive for the Mk 2 EPD during 2002.
First Client will be British Energy Hinkley Point BPower Station (AGR)
During financial year 2003 /2004 BNFL will consider aproject to upgrade from Mk 1.2 EPD to Mk 2EPD.
EC/IAEA/ISOE WorkshopPortoroz Slovenia April 2002
Electronic Personal Dosimetry