The DONA neutron spectrometer concept is based on the measurement of neutron induced activity in a series of small metal disks that have been exposed to a neutron field. The induced activity is measured and the neutron spectrum is calculated using and unfolding technique, based on environmental neutron spectra. A complete measurement is performed in three steps: 1. Placement of the detector device (the holder with the metal disks) at the measurement site. 2. Transport of the detector to a gamma-ray measurement laboratory where the neutron induced activity is detected. 3. Calculation of the neutron intensity and spectrum using unfolding algorithms and an environmental neutron spectrum library. The novelty of the approach lies in the concept as such, including usage of carefully selected metal disks arranged in a holder, high performance gamma-ray spectrometry and spectrum unfolding using a library of environmental neutron spectra. In 2004, a first study was carried out within the frame of an IRMM exploratory research project. Several detectors were developed and successfully tested in laboratory neutron fields. This report covers the IRMM exploratory research prolongation project for 2006 in which the same detector concept is used, however, now in environmental neutron fields with considerably lower neutron fluence rates. The result shows that after further refinement of the detector device and the data evaluation program the detector can very well be used for environmental neutron fluence measurements. Tests were done at PTB, Germany, using their calibrated neutron source and at the MOX fuel fabrication plant Belgonuclearire in Mol, Belgium. How to obtain EU publications Our priced publications are available from EU Bookshop (http://bookshop.europa.eu), where you can place an order with the sales agent of your choice. The Publications Office has a worldwide network of sales agents. You can obtain their contact details by sending a fax to (352) 29 29-42758. The mission of the JRC is to provide customer-driven scientific and technical support for the conception, development, implementation and monitoring of EU policies. As a service of the European Commission, the JRC functions as a reference centre of science and technology for the Union. Close to the policy-making process, it serves the common interest of the Member States, while being independent of special interests, whether private or national. L A N A 2 3 3 0 5 E N C
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