ESTABLISHMENT OF A LOW DOSE RATE GAMMA RAY CALIBRATION FIELD FOR ENVIRONMENTAL RADIATION MONITORING DEVICES.

For routine calibration of dosemeters used for environmental radiation monitoring, a low dose rate 137Cs gamma ray calibration field that fully satisfies the requirement of the ISO 4037 series was established in the Facility of Radiation Standards in Japan Atomic Energy Agency. Two different methods were employed to determine the reference air kerma rate, namely a conventional ionisation chamber and a G(E) function method used a newly developed scintillation spectrometer. To fulfil the requirement of the ISO 4037 and suppress scattering of Cs gamma ray within the room as far as possible, a suitable lead collimator was introduced to limit the irradiation area at test points and placed at the middle height in an irradiation room with a grating floor.

Metrology for Radiological Early Warning Networks in Europe ("METROERM")-A Joint European Metrology Research Project.

As a consequence of the Chernobyl nuclear power plant accident in 1986, all European countries have installed automatic dosimetry network stations as well as air sampling systems for the monitoring of airborne radioactivity. In Europe, at present, almost 5,000 stations measure dose rate values in nearly real time. In addition, a few hundred air samplers are operated.

EURADOS INTERCOMPARISONS IN EXTERNAL RADIATION DOSIMETRY: SIMILARITIES AND DIFFERENCES AMONG EXERCISES FOR WHOLE-BODY PHOTON, WHOLE-BODY NEUTRON, EXTREMITY, EYE-LENS AND PASSIVE AREA DOSEMETERS.

The European Radiation Dosimetry Group (EURADOS) has been organising dosimetry intercomparisons for many years in response to an identified requirement from individual monitoring services (IMS) for independent performance tests for dosimetry systems. The participation in intercomparisons gives IMS the opportunity to show compliance with their own quality management system, compare results with other participants and develop plans for improving their dosimetry systems. In response to growing demand, EURADOS has increased the number of intercomparisons for external radiation dosimetry.

Deep underground measurements of 60Co in steel exposed to the Hiroshima atomic bomb explosion.

When using gamma-ray spectrometry performed deep underground, it is possible to measure 60Co activities down to 0.1 mBq in steel samples of some 100 g without any pre-concentration. It is thus still possible to measure 60Co induced by neutrons from the atomic bomb explosion in Hiroshima in pieces of steel collected at distances up to about 1200 m slant range.

Deep underground gamma spectrometric measurement of 26Al in meteorite samples.

26Al is routinely measured in meteorite samples by accelerator mass spectrometry (AMS). PTB participates in an international intercomparison between laboratories using AMS and gamma-ray spectrometry to improve the quality of such measurements. We performed gamma spectrometric measurements at the underground laboratory UDO using the GESPECOR software to calculate corrections for efficiency transfer, self-attenuation and coincidence summing.