Biomedical subjects

G Pelcot

Publications and source records attributed to G Pelcot.

7 recordsLinked to original sources

PubMed2005

French comparison exercise with the rotating neutron spectrometer, 'ROSPEC'.

The French laboratories in charge of 'neutron' dosimetry using the spectrometer 'ROSPEC', formed a working group in 2001. The participants began to study the behaviour of the instrument with a comparison exercise in broad energy neutron fields recommended by the International Organisation for Standardisation (ISO) and available at the LMDN in Cadarache. The complete version of the ROSPEC is made up of six spherical proportional counters fixed to a rotating platform. These counters cover different energy ranges which overlap each other to provide a link between the detectors, within the energy range from thermal neutrons to 4.5 MeV. The irradiation configurations chosen were ISO standard sources (252Cf, (252Cf+D2O)(/Cd), 241Am-Be) and the SIGMA facility. The results show that the 'thermal and epithermal' neutron fluence was widely overestimated by the spectrometer in all configurations.

Dose-Response Relationship, Radiation↗

PubMed2004

AMANDE: a new facility for monoenergetic neutron fields production between 2 keV and 20 MeV.

The variation of the response of the instruments with the neutron energy has to be determined in well-characterized monoenergetic neutron fields. The AMANDE facility will deliver such neutron fields between 2 keV and 20 MeV in an experimental hall designed with metallic walls for neutron scattering minimisation. The neutrons will be produced by nuclear interaction of accelerated protons or deuterons on thin targets of selected materials. The measuring devices to be characterised will be accurately placed with a fully automated detector transport system. The energy of the neutron field will be validated by time-of-flight experiments and a large set of standard detectors and fluence monitors will be used to determine the neutron fluence references. The scattered neutron fluence and dose equivalent were calculated by the MCNP Monte Carlo code at several measuring points in order to determine their contribution to the neutron field.

Body Burden↗

PubMed2004

Inter-laboratory test program (PTI) in 'neutron dosimetry'.

The Laboratory of External Dosimetry Studies and Researches (LRDE), associated laboratory to the Bureau National de Métrologie, is strongly involved in the reference establishment and calibration of instruments in neutron radiation fields provided by 241Am-Be, 252Cf and (252Cf + D2O)/Cd sources. In 1997, on the request of COFRAC, the LRDE has managed an Inter-Laboratory Test Program in 'neutron dosimetry' to compare the different standard calibration methods. The transfer instrument used was a "Harwell Monitor N91". The results of the participant were in good agreement but the associated uncertainties need to be revised by some of laboratories. According to the Mutual Recognition Arrangement signed in 1999, laboratories for metrology will have to assure the traceability of their references. In 2003-2005, the LRDE organises, with National Physical Laboratory (UK) and Physikalisch-Techische Bundesanstalt (Germany), an international comparison in 'neutron dosimetry'. Two transfer instruments, a "2202D" rate metre and a "Harwell Monitor N91", will be sent in turn to the participant laboratories for measurements at their own neutron sources facilities.

Body Burden↗

PubMed2004

Individual neutron monitoring in workplaces with mixed neutron/photon radiation.

EVIDOS ('evaluation of individual dosimetry in mixed neutron and photon radiation fields') is an European Commission (EC)-sponsored project that aims at a significant improvement of radiation protection dosimetry in mixed neutron/photon fields via spectrometric and dosimetric investigations in representative workplaces of the nuclear industry. In particular, new spectrometry methods are developed that provide the energy and direction distribution of the neutron fluence from which the reference dosimetric quantities are derived and compared to the readings of dosemeters. The final results of the project will be a comprehensive set of spectrometric and dosimetric data for the workplaces and an analysis of the performance of dosemeters, including novel electronic dosemeters. This paper gives an overview of the project and focuses on the results from measurements performed in calibration fields with broad energy distributions (simulated workplace fields) and on the first results from workplaces in the nuclear industry, inside a boiling water reactor and around a spent fuel transport cask.

Artifacts↗

PubMed2004

Characterisation of the IRSN CANEL/T400 facility producing realistic neutron fields for calibration and test purposes.

The new CANEL/T400 facility has been set-up at the Institute for Radiological Protection and Nuclear Safety (IRSN) to produce a realistic neutron field. The accurate characterisation of this neutron field is mandatory since this facility will be used as a reference neutron source. For this reason an international measuring campaign, involving four laboratories with extensive expertise in neutron metrology and spectrometry, was organised through a concerted EUROMET project. Measurements were performed with Bonner sphere (BS) systems to determine the energy distribution of the emitted neutrons over the whole energy range (from thermal energy up to a few MeV). Additional measurements were performed with proton recoil detectors to provide detailed information in the energy region above 90 keV. The results obtained by the four laboratories are in agreement with each other and are compared with a calculation performed with the MCNP4C Monte-Carlo code. As a conclusion of this exercise, a reliable characterisation of the CANEL/T400 neutron field is obtained.

Algorithms↗

PubMed2004

Criticality accident dosimetry systems: an international intercomparison at the SILENE reactor in 2002.

In criticality accident dosimetry and more generally for high dose measurements, special techniques are used to measure separately the gamma ray and neutron components of the dose. To improve these techniques and to check their dosimetry systems (physical and/or biological), a total of 60 laboratories from 29 countries (America, Europe, Asia) participated in an international intercomparaison, which took place in France from 9 to 21 June 2002, at the SILENE reactor in Valduc and at a pure gamma source in Fontenay-aux-Roses. This intercomparison was jointly organised by the IRSN and the CEA with the help of the NEA/OCDE and was partly supported by the European Communities. This paper describes the aim of this intercomparison, the techniques used by the participants and the two radiation sources and their characteristics. The experimental arrangements of the dosemeters for the irradiations in free air or on phantoms are given. Then the dosimetric quantities measured and reported by the participants are summarised, analysed and compared with the reference values. The present paper concerns only the physical dosimetry and essentially experiments performed on the SILENE facility. The results obtained with the biological dosimetry are published in two other papers of this issue.

Body Burden↗

PubMed2004

Reference dosimetry measurements for the international intercomparison of criticality accident dosimetry SILENE 9-21 June 2002.

An international intercomparison of criticality accident dosimetry systems took place in the SILENE reactor, in June 2002. Participants from 60 laboratories irradiated their dosemeters (physical and biological) using two different configurations of the reactor. In preparation for this intercomparison, the leakage radiation fields were characterised by spectrometry and dosimetry measurements using the ROSPEC spectrometer associated with a NE-213 scintillator, ionisation chambers, GM counters, diodes and thermoluminescence dosemeters (TLDs). For this intercomparison, a large area was required to irradiate the dosemeters both in free air and on phantoms. Therefore, measurements of the uniformity of the field were performed with activation detectors and TLDs for neutron and gammas, respectively. This paper describes the procedures used and the results obtained.

Equipment Design↗