Objectif
Deficiencies in the dosimetry of weakly penetrating radiation in radiation protection have been identified which are obstacles to the acceptance of the Commissions guidance given in its radiation protection recommendations. The deficiencies will be eliminated by the proposed project with the joint effort of the most experienced experts in this field within the EU. About one million workers are occupationally monitored with personal dosemeters within the EU, and the reliable and accurate measurement of their radiation exposure is an extremely important requirement. Up to now, however, there is no agreement on the measuring quantities for individual monitoring which are the same for all radiation types, are fail safe for the effective dose equivalent, and are relatable to an appropriate phantom. The recent report EUR 14852 EN fills this gap by recommending new operational quantities, in particular the personal dose equivalent quantities, and the implementation of these quantites is therefore of global interest for radiation protection practice within the EU.
The application of the air kerma-to-dose-conversion coefficients, as recommended in the EUR report, for determining the personal dose equivalent at 10 mm depth for the calibration and type testing of personal dosemeters has a number of practical difficulties which impede the introduction of the quantity when photons of lower energies are involved. The development of an ionisation chamber for measuring the personal dose equivalent at 10 mm depth directly and not determining this operational quantity via conversion coefficients (which needs detailed spectral information) is expected to overcome these problems. Such a personal dose equivalent chamber does not yet exist.
The exposure to beta radiation in particular has played an important role in the Chernobyl and other radiation accidents. Operational beta dosimetry of surface contamination and hot particles after accidents and in workplaces is an import task and has been neglected so far by established techniques. Therefore, a portable and rugged active beta dosemeter-spectrometer combination with semiconductor detectors is proposed to be developed which enables the immediate measurement of the doses and energies of the beta particles even in the presence of photon radiation. Such an instrument does not yet exist. In the case of hot particles, due to their highly non-uniform spatial dose distribution, measurements with this instrument will be supplemented by other techniques (extrapolation chamber, radiochromic dye, thermoluminescence and optically stimulated luminescence foil measurements) and Monte Carlo and semi empirical calculations previously developed for this specific problem (CEC and EURADOS projects).
The experimental and calculational methods in this work will be collated, validated and documented in a form suitable for QA applications, with emphasis on extrapolation chambers. Special, well characterized sources will be produced and used for an in-vitro transformation experiment (sub-contract) to clarify inconsistencies reported about hazards posed by hot particles. Summing up, the project serves to develop adequate instrumentation and calculational methods for implementing updated radiation protection recommendations of the Commission for occupational exposure and to substantially improve the level of operational beta dosimetry (in compliance with programme areas D.2.4 D.2.5 Dl.l and E.1.3). Two instruments (personal dose equivalent chamber and beta dosemeter-spectrometer combination) will be developed to an advanced stage. Further development would produce marketable products.
Programme(s)
Appel à propositions
Data not availableRégime de financement
CSC - Cost-sharing contractsCoordinateur
38023 Braunschweig
Allemagne