Performance of the electronic personal dosemeter for neutron "Saphydose-N" at different workplaces of nuclear facilities
T. Lahaye, Q.Chau, V. Lacoste, H. Muller, M. Luszik-Bhadra, P. Bruguier, 14th International conference on solid state dosimetry, 27/06-02/07 2004, Yale.
According to the transposition of the Directive 96/29/EURATOM into the french legislation, any worker operating in a controlled area has to be monitored by “passive” and “active” dosemeters. Electronic personal dosemeters are especially needed for optimisation of workplaces. In nuclear facilities, some of the workers are likely to be exposed to mixed neutron-photon fields. If the dosimetry of the photons is relatively well controlled, the neutron dosimetry raises more difficulties. In this context, the Institute for Radiological Protection and Nuclear Safety (IRSN) has developed an electronic device based on a silicon detector: The "Saphydose-N" dosemeter, composed of several detectors, covers more than eight energy decades. The variation of this dosemeter response with neutron energy does not exceed ±38% over the energy range 0.1 – 15 MeV and -8% for the thermal neutron field. The horizontal and vertical angular responses do not exceed ±30%, except for the point at +60° vertical which presents a variation of -36%. The Saphydose-N device complies with recommendations of standard IEC 1323. As the radiation fields produced in laboratory are not strictly representative to those encountered at workplaces, IRSN had to evaluate the response of Saphydose-N at various workplaces from nuclear industry. During a first campaign, carried out at a french fuel processing plant, measurements were performed at 16 different locations (representative of places where workers use to stand). Two other campaigns were led in the frame of the European contract EVIDOS (“Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields”). The first one was performed at the Krümmel Nuclear Power Plant (Germany) close to the boiling water reactor and to a spent fuel transport cask ; the second one was realized at MOL (Belgium), at the VENUS Research Reactor and at Belgonuclear, a fuel processing factory. This paper mainly aims at presenting the measurements and the results obtained with the electronic personal dosemeter Saphydose-N at these facilities. In almost all cases, the discrepancies between the Saphydose-N responses and the reference values do not exceed 50 %. A higher disagreement was observed for the SAR and TOP position at Krümmel, because of the particular exposure conditions.