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Occupational Radiation Exposure Monitoring

Purpose

The work on Occupational Radiation Exposure Monitoring contributes to the fulfillment of the following statutory responsibilities of the Agency:

  • To provide for the application of the Agency's radiation safety standards (the Standards) to its own operations as well as to operations under its control or supervision
  • To provide for the application of the Standards, at the request of a State, by rendering appropriate radiation safety services
  • To provide guidance and assistance for the strengthening of occupational radiation protection infrastructures in Member States

The focus is on developing and maintaining the operational services for radiation safety of the Agency and ensuring the quality of its Radiation Protection Testing Laboratory to enable the Agency's Radiation Safety Regulations, derived from the BSS, to be implemented in an effective and consistent manner.

High priority is assigned to the development, supervision and implementation, mostly under the Agency's Technical Co-operation programme, satisfaction of regulatory and operational needs and provision of services for the application the IAEA Safety Standards. The work is divided into the following main areas:

Assessment of occupational exposure by individual monitoring

A testing laboratory is in place with the following objectives:

  • To assess the occupational exposure due to radiation of IAEA staff and Technical Co-operation experts, on the basis of individual monitoring
    To assist Member States in the field of individual monitoring
  • To provide, in the framework of the Technical Cooperation Programme, on-the-job training and scientific visits on individual monitoring
  • To carry out these objectives two specialized service laboratories are available: an External Dosimetry laboratory and an Internal Dosimetry laboratory

Assessment of occupational exposure due to external sources of radiation

The main task of the External Dosimetry Services is to assess the occupational exposure due to external radiation sources. Measurement techniques are available for whole body and extremity monitoring of photon, neutron and beta radiation. A large range of radiation fields in nuclear fuel cycle facilities, research facilities, medical and industrial applications as well as in emergency situations are covered. External monitoring services are provided routinely (monitoring period of one to three months) or on an ad-hoc basis according to the customers’ requests. Currently more than 15000 dosimeters are evaluated per year. Since 1981 the IAEA individual monitoring services are based on a Thermoluminescence Dosimetry System.

The Laboratory is managed by one professional, 2 technicians, and a clerk.

External Dosimetry Services

  • Measurement techniques available for whole body and extremity monitoring of photon, neutron and beta radiation
  • Routine and ad-hoc monitoring for IAEA staff, external experts and trainees at Agency and non-Agency premises
  • Large range of radiation fields in nuclear fuel cycle facilities, research facilities, medical and industrial applications as well as emergency response covered
  • Evaluation of more than 15000 dosimeters/year. Reporting level at 0.05 mSv and investigation level at 5 mSv
  • Quality Management System based on ISO 17025
  • Technical assistance to IAEA Member States in the fields of individual monitoring

Measurement techniques

  • Two HARSHAW TLD Reader 6600 workstations
  • 2- and 4 element cards (TLD-100, TLD-600, TLD-700) and extremity dosimeters (TLD-700H)
  • TLD cardholders HARSHAW 8814 and 8806
  • One HARSHAW TLD Reader 5500 workstation
  • HARSHAW TLD chips (TLD-100)
  • One Thermo EPD system

 

 

 

 

Assessment of operational quantities Hp(10) and Hp(0.07)

  • IAEA dose management system – algorithm based on performance testing according to ISO/IEC 1066
  • DOELAP algorithm (modified version) for neutron dose calculation
  • Methods validated and uncertainty budget established
  • Traceability to IAEA SSDL for photon fields and to PTB (Germany) for neutron and beta fields
  • QA through regular quality control and intercomparison exercises

Dosimeters

Passive dosimeters

 

 

 

Whole body dosimeters

The thermoluminescent dosimeters (TLD) are fabricated from Lithium fluoride elements assembled in barcoded cards encapsulated in Teflon. Dosimeter assemblies are configured for the dose assessment from beta, gamma and neutron radiation. The dosimeter cards are labeled with the user’s ID and the monitoring period.

Specifications
Detector materials: Li:Mg,Ti (Li isotopes)
Measurement range:
0.05 mSv – 10 Sv
Energy range:

Photons 33 keV (N-40) to 1250 keV(S-Co) 6.6 MeV (R-F)
Beta 230 keV (Pm) to 2.2 MeV (Sr)
Neutrons 0.025 eV – 5 MeV
Measurement quantity: Ηρ (10)  

Extremity dosimeters

The extremity dosimeter consists of an adjustable plastic ring, the TL element, i.e. TLD powder bonded to a Kapton film surrounded by a unique 5-digit identification number, and a plastic cap to provide sealing of the TLD material.

 

Specifications
Detector material: Li:Mg,Cu,P
Measurement range:
0.05 mSv – 10 Sv
Energy range:

Photons 33 keV (N-40) to 1250 keV(S-Co) 6.6 MeV (R-F)
230 keV (Pm) to 2.2 MeV (Sr)
Measurement quantity: Ηρ (0.07)


Active dosimeters

Electronic Personal Dosimeters

Active dosimeters are provided as operational devices in addition to the TL dosimeters to obtain a real-time logging of dose data.

Specifications
Dosimeter EPD Mk2 , Workstation and Reader
Detectors: 3 silicon diodes
Energy range:
Photons 33 keV (N-40) to 1250 keV(S-Co) 6.6 MeV Beta- from 230 keV (Pm) to 2.2 MeV (Sr)
Measurement range:

0.001 mSv – 10 Sv
Measurement quantity: Ηρ (10) and Ηρ (0.07)

 

Customers

Customers are workers who are normally employed in a controlled area or who occasionally work in a controlled area and may receive significant occupational exposure. The nature, frequency and precision of individual monitoring is determined with consideration of the magnitude and possible fluctuation of exposure levels and the likelihood and magnitude of potential exposure.

  • IAEA staff with duty station at Vienna Headquarters, in Tokyo, Toronto, Seibersdorf and Monaco
  • Any other worker for whose occupational exposure monitoring the Agency is responsible according to the Agency’s Radiation Protection Regulations, the International Basic Safety Standards (BSS) for Protection against Ionizing Radiation and for the Safety of Radiation Sources and related safety publications, e.g. Technical Co-operations experts, trainees.

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| Last update: Thursday, 02 July, 2015.