Eighth Symposium on Neutron Dosimetry

Abstract

This symposium was jointly organised by the European Commission (EC), the Institut de Protection et de Sûreté Nucléaire (IPSN), the Physikalisch-Technische Bundersanstalt (PTB) and the US Department of Energy (DOE). Over 140 posters and papers were presented on topics ranging from recent advances in bubble and passive detectors to monitoring requirements and experiences in the nuclear industry. The symposium was divided into several topic sessions which are outlined below. The first session of the symposium `Physical Data for Radiation Protection and Therapy Dosimetry' opened with a presentation by Dr L Court (EDF, France) who discussed the neutron dosimetry requirements of health physicists, radiotherapists, radiobiologists and risk assessment experts in the light of the new ICRP radiation weighting factors, WR and the dose quantity, effective dose, E. During the next two sessions the nuclear industry expressed their environmental and personal monitoring requirements. An invited paper by Dr Ross Hirning (Ontario Hydro, Canada) expressed one view of an ideal survey meter and personal neutron dosemeter. Researchers at the symposium responded by presenting papers on the development of bubble and passive neutron detectors. The researchers and practitioners came head to head at a panel discussion later in the week, where an initial attempt at bridging the gap between research and practical dosimetry was made. It was evident that research funds are available and that it is imperative that the needs of the practitioners are taken into consideration at a very early stage of any proposed dosimetry development. During the mid week sessions industry presented a variety of posters and papers on their individual experiences and developments which included posters by Dr L Tommasino (ANPA, Italy) on the combined use of bubble dosemeters and electrochemically etched track detectors and by Dr C Wernli (PSI, Switzerland) on a personal neutron dosimetry system based on track etch and automatic readout by Autoscan 60 reader. Neutron Spectrometry is still an essential requirement of any neutron monitoring device as the ideal device, with a flat angular and energy response, has yet to be developed. There appear to be two main schools of thought on how to compensate for the response of a device. Dr J Chartier (IPSN, France) presented a paper on calibrating devices using realistic neutron calibration fields, whereas Ms O Naismith (NPL, UK) discussed the use of correction factors to compensate for the energy and angular response of the device. The two concepts were discussed in detail by other participants. A session was devoted to `Dosimetry for High Energy Radiations', an area which has been considered in the past but has been revisited due to several factors: previous underestimates of the radiobiological effectiveness of the neutron component; a trend for airlines to cruise at higher altitudes and ICRP 60 recommendations. Dr D Bartlett (NRPB, UK) discussed the findings of a working group of the European Dosimetry Group (EURADOS) on the exposure of aircraft crews to cosmic radiation. One such finding was that aircraft crew in the UK receive a significant collective annual radiation dose, second only to that from radon. The working group concluded that flight route assessment doses should be made available by airlines as a means of assessing doses to crew and frequent fliers. Accident dosimetry was also discussed briefly and the session included two international intercomparisons, by Dr R Médioni (IPSN, France) and Dr W Casson (Los Alamos, USA), of criticality accident dosimetry; one participant apparently could not actually open the criticality locket for assessment. The final sessions of the symposium discussed the requirements of neutron dosimetry in the field of radiotherapy. Boron neutron capture therapy and proton therapy were the main topics discussed. K Barlow and M Jackson