EWGRD: The European Working Group on Reactor Dosimetry

The European Working Group of Reactor Dosimetry (EWGRD) started around 1960, under the sponsorship of EURATOM, with members designated by the governments from each European Union (EU) laboratories working in the field of reactor physics and technology. The goal was to exchange directly experience and know-how in reactor dosimetry and connected programmes. The fields covered were the measurements of thermal and epithermal fluences and fluence rate, the measurement of fast neutron spectra and fluences of thermal and fast reactors, and later the measurement of fusion and spallation neutron spectra.

The major applications of neutron dosimetry in fission reactors was and still is the monitoring of irradiation experiments. The knowledge of the neutron and gamma-ray fields and fluences as well as the temperature during irradiation, is necessary to understand and to assess the embrittlement of the structural materials and mainly the pressure vessel steel due to the neutron exposure.

Radiation damage units had to be introduced, i.e. dpa, flux > 1 MeV, or flux > 0.5 MeV to correlate the life time of a material under radiation to the exposure dose.

Soon the need for normalisation was felt in order to guarantee that some nuclear data were used, that measurements in different laboratories gave the same results (need for inter-calibration experiments and standards), and that results were expressed such that a comparison with results from other laboratories were possible. In sub-group specific arguments were discussed resulting in final recommendations. These final recommendations were then discussed in a plenary meetings and accepted as recommendations for European use. Following documents were produced:

• the "Co-norm" which recommended a procedure to measure thermal and epithermal neutron fluences, including nuclear data to be used (1965).
• EUR documents concerning normalisation in the radiation damage field: "Recommendation for neutron dosimetry in irradiations of reactor materials" EUR 5274 defn (1975) "Introduction of neutron metrology for reactor radiation damage" EUR 6182 (1992) "Radiation damage dosimetry for fusion materials" EUR 14630 (1992)
• A "nuclear data guide" with recommended values for "nuclear data for neutron metrology" revised and completed when necessary: "Nuclear data guide for neutron metrology" EUR 12354 (1989)
• The latest activity concerns the standardisation of materials to be used as detector materials: "A European Community source of reference materials for neutron metrology requirements" Nucl. Inst. Meth. in Phys. Res. A236, 600-603 (1985)

The large programme on pressure vessel steels dosimetry, at which a large number of European laboratories participated started practically in discussions at the first ASTM-EURATOM Symposium on Reactor Dosimetry, Petten 1975. It was fully activated by ASTM and has achieved very successful results, leading to a number of ASTM standards. This programme has emphasised the importance of the collaboration between metallurgists, reactor operators, and reactor physicists, as well theoretical as experimental researchers. The role of neutron and gamma dosimetry has been of major importance in this research programme. It is proven to be of major importance for the industrial application of pressure vessel steels and lifetime predictions under radiation.

The EWGRD is presently chaired by P. D'hondt (SCK•CEN, Mol, Belgium).

Since 1991, the EWGRD enlarged, its activities, to the former East bloc countries which have organised their specific activities in a form of a working group normally the WGRD-VVER.

The Working Group on Reactor Dosimetry for VVER Reactors

The development of recommended standard practical for VVER reactors pressure vessel exposure monitoring is an important part of WGRD-VVER activity. Two plenary meetings were held in October 1991 and October 1992 in NRI. The European Working Group on Reactor Dosimetry and the WGRD-VVER organised both the workshop on "Pressure Vessel Surveillance Programmes and Their Applications" which was held in NRI in March 1993.

Members of the EWGRD Programme Committee

Participant Institutes

The state of the art in all reactor dosimetry aspects such as techniques, calculations and adjustment methods, damage correlation, neutron data, etc. are fully reported in the proceedings, listed below, of international symposia on Reactor Dosimetry organised alternatively in EUROPE and in the USA:

EWGRD Activities

• 11th International Symposium on Reactor Dosimetry, Brussels (Belgium), 18-23 August 2002.
• EWGRD-PC meeting, Budapest, Hungary, 31 March 2004.
• EWGRD-PC meeting, Brussels, Belgium, 9-10 September 2004.
• 12th International Symposium on Reactor Dosimetry, Gatlinburg (Tennessee, USA), 8-13 May 2005.
• EWGRD-PC meeting, Akersloot, 12-13 November 2007.
• 13th International Symposium on Reactor Dosimetry, Akersloot (The Netherlands), 25-30 May 2008.
• 14th International Symposium on Reactor Dosimetry, Bretton Woods (New Hampshire, USA), 22-27 May 2011

Contact:

• Jan Wagemans: jan.wagemans@sckcen.be