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M Prata - One of the best experts on this subject based on the ideXlab platform.

  • Neutron Flux and gamma dose measurement in the BNCT irradiation facility at the TRIGA reactor of the University of Pavia
    2018
    Co-Authors: S. Bortolussi, M Prata, N. Protti, M. Ferrari, I. Postuma, S. Fatemi, F. Ballarini, M..p. Carante, R. Farias, S..j. González
    Abstract:

    University of Pavia is equipped with a TRIGA Mark II research nuclear reactor, operating at a maximum steady state power of 250 kW. It has been used for many years to support Boron Neutron Capture Therapy (BNCT) research. An irradiation facility was constructed inside the thermal column of the reactor to produce a sufficient thermal Neutron Flux with low epithermal and fast Neutron components, and low gamma dose. In this irradiation position, the liver of two patients affected by hepatic metastases from colon carcinoma were irradiated after borated drug administration. The facility is currently used for cell cultures and small animal irradiation. Measurements campaigns have been carried out, aimed at characterizing the Neutron spectrum and the gamma dose component. The Neutron spectrum has been measured by means of multifoil Neutron activation spectrometry and a least squares unfolding algorithm; gamma dose was measured using alanine dosimeters. Results show that in a reference position the thermal Neutron Flux is (1.20±0.03)×1010 cm−2 s−1 when the reactor is working at the maximum power of 250 kW, with the epithermal and fast components, respectively, 2 and 3 orders of magnitude lower than the thermal component. The ratio of the gamma dose with respect to the thermal Neutron fluence is 1.2×10-13 Gy/(n/cm2)

  • measurement of the Neutron Flux parameters f and α at the pavia triga mark ii reactor
    2017
    Co-Authors: Marco Di Luzio, M Prata, M Oddone, D Alloni, G Dagostino
    Abstract:

    In this paper, evaluation of Neutron Flux parameters of TRIGA Mark II reactor in Pavia was carried out. For any of the three irradiation positions investigated, this work represented the first experimental evaluation of α. Moreover, in addition to α, values of other parameters such as f, Φ th and Φ e were also calculated and compared with the existent literature data from other TRIGA Mark II reactors and the Pavia’s facility. Results obtained in the present study represent a mandatory step ahead for future application of k 0-Neutron Activation Analysis method (k 0-NAA) at Pavia’s facility.

  • measurement and simulation of the Neutron Flux distribution in the triga mark ii reactor core
    2015
    Co-Authors: D Chiesa, M Clemenza, Massimiliano Nastasi, Stefano Pozzi, E Previtali, Giuseppe Scionti, M Sisti, M Prata, A Salvini, Antonio Cammi
    Abstract:

    Abstract The Neutron Flux distribution in the TRIGA Mark II reactor core installed at the Applied Nuclear Energy Laboratory (L.E.N.A.) of the University of Pavia was measured through the Neutron activation technique, irradiating Al–Co samples in different positions among the fuel elements and in the Central Thimble. The fast and integral Fluxes were simultaneously measured in the same positions analyzing the 27 Al(n, α ) 24 Na threshold reaction and the (n, γ ) activation of 59 Co, respectively. These measurements were then compared with the Neutron Fluxes evaluated through the MCNP5 reactor model which was developed in the last years, obtaining a good agreement of the results.

  • triga reactor absolute Neutron Flux measurement using activated isotopes
    2014
    Co-Authors: Borio A Di Tigliole, D Chiesa, M Clemenza, Massimiliano Nastasi, Stefano Pozzi, Antonio Cammi, S Manera, L Pattavina, Roberto Ponciroli, M Prata
    Abstract:

    Abstract The Neutron Flux is a crucial parameter for the analysis of nuclear reactors, because it affects the reaction rate and thus the fuel burnup. Moreover, a very precise knowledge of the Flux in the irradiation positions is helpful for benchmarking the simulation models of the reactor. In particular, an MCNP model of the TRIGA Mark II reactor installed at LENA (Laboratory of Applied Nuclear Energy) of the University of Pavia was developed in the recent years, describing the geometries and the materials of the whole reactor with very good accuracy. In this article, we present the results of the Neutron Flux measurements in four irradiation positions. The Neutron activation technique was used to perform an absolute measurement of the Flux. Various samples containing a known amount of elements were irradiated in the reactor facilities and the activation rate of a large number of isotopes was measured through γ -ray spectroscopy with very low background HPGe detectors. In order to accurately calculate the activation rate, Monte Carlo codes based on GEANT4 were developed to evaluate the γ -ray detection efficiency for every radioisotope of interest. The samples were measured with three different HPGe detectors and the measurements were repeated in various geometric configurations in order to assess the reliability and repeatability of this analysis technique. The MCNP reactor model was used to evaluate the energetic Neutron Flux distributions in the irradiation positions. The effective activation cross sections were computed from these distributions, testing the dependence on the MCNP simulation results. Finally, the Neutron Flux was calculated from the data of activation rate and effective cross section of each isotope. The good agreement in the results of the Flux calculations from the many different activated samples confirms the reliability of the adopted methodology.

Tieshan Wang - One of the best experts on this subject based on the ideXlab platform.

  • performance testing of the Neutron Flux monitors from 10 kev to 1 mev developed for bnct a preliminary study
    2017
    Co-Authors: Xingcai Guan, Isao Murata, Masanobu Manabe, Shingo Tamaki, Fuminobu Sato, Tieshan Wang
    Abstract:

    The Neutron Flux monitors from 10keV to 1MeV designed for boron Neutron capture therapy (BNCT) were experimentally tested with prototype monitors in an appropriate Neutron field produced at the intense deuterium-tritium Neutron source facility OKTAVIAN of Osaka University, Japan. The experimental test results and related analysis indicated that the performance of the monitors was good and the Neutron Fluxes from 10keV to 1MeV of practical BNCT Neutron sources can be measured within 10% by the monitors.

  • design study of Neutron Flux intensity monitor between ten and several hundred kev for bnct
    2016
    Co-Authors: Xingcai Guan, Isao Murata, Tieshan Wang
    Abstract:

    Based on the activation method using 71Ga(n,γ)72Ga reaction, two spherical monitors with gallium nitride (GaN) wafers as activation material were designed by Monte Carlo simulations to precisely measure the absolute integral Neutron Flux intensity between ten and several hundred keV. The two monitors are almost the same in shape and have an absorber/moderator/absorber/GaN arrangement from outside to inside. The differences between the two monitors are the kind of materials, the thicknesses of the absorbers and the diameter of the moderator. By making difference of the sensitivities between these two monitors, the contributions of thermal, epithermal and very high energy fast Neutrons were removed completely, and constant monitor sensitivity to Neutrons between ten and several hundred keV was extracted. The simulation results and related analysis indicated that the absolute integral Neutron Flux intensity between ten and several hundred keV could be precisely measured by the presently designed two monitors.

  • design of an epi thermal Neutron Flux intensity monitor with gan wafer for boron Neutron capture therapy
    2014
    Co-Authors: Xingcai Guan, Isao Murata, Masanobu Manabe, Tieshan Wang
    Abstract:

    Boron Neutron capture therapy (BNCT) is a promising cancer therapy. Epi-thermal Neutron (0.5 eV < En < 10 keV) Flux intensity is one of the basic characteristics for modern BNCT. In this work, based on the 71Ga(n,γ)72Ga reaction, a new simple monitor with gallium nitride (GaN) wafer as activation material was designed by Monte Carlo simulations to precisely measure the absolute integral Flux intensity of epi-thermal Neutrons especially for practical BNCT. In the monitor, a GaN wafer was positioned in the center of a polyethylene sphere as Neutron moderator covered with cadmium (Cd) layer as thermal Neutron absorber outside. The simulation results and related analysis indicated that the epi-thermal Neutron Flux intensity could be precisely measured by the presently designed monitor.

Xingcai Guan - One of the best experts on this subject based on the ideXlab platform.

  • performance testing of the Neutron Flux monitors from 10 kev to 1 mev developed for bnct a preliminary study
    2017
    Co-Authors: Xingcai Guan, Isao Murata, Masanobu Manabe, Shingo Tamaki, Fuminobu Sato, Tieshan Wang
    Abstract:

    The Neutron Flux monitors from 10keV to 1MeV designed for boron Neutron capture therapy (BNCT) were experimentally tested with prototype monitors in an appropriate Neutron field produced at the intense deuterium-tritium Neutron source facility OKTAVIAN of Osaka University, Japan. The experimental test results and related analysis indicated that the performance of the monitors was good and the Neutron Fluxes from 10keV to 1MeV of practical BNCT Neutron sources can be measured within 10% by the monitors.

  • design study of Neutron Flux intensity monitor between ten and several hundred kev for bnct
    2016
    Co-Authors: Xingcai Guan, Isao Murata, Tieshan Wang
    Abstract:

    Based on the activation method using 71Ga(n,γ)72Ga reaction, two spherical monitors with gallium nitride (GaN) wafers as activation material were designed by Monte Carlo simulations to precisely measure the absolute integral Neutron Flux intensity between ten and several hundred keV. The two monitors are almost the same in shape and have an absorber/moderator/absorber/GaN arrangement from outside to inside. The differences between the two monitors are the kind of materials, the thicknesses of the absorbers and the diameter of the moderator. By making difference of the sensitivities between these two monitors, the contributions of thermal, epithermal and very high energy fast Neutrons were removed completely, and constant monitor sensitivity to Neutrons between ten and several hundred keV was extracted. The simulation results and related analysis indicated that the absolute integral Neutron Flux intensity between ten and several hundred keV could be precisely measured by the presently designed two monitors.

  • design of an epi thermal Neutron Flux intensity monitor with gan wafer for boron Neutron capture therapy
    2014
    Co-Authors: Xingcai Guan, Isao Murata, Masanobu Manabe, Tieshan Wang
    Abstract:

    Boron Neutron capture therapy (BNCT) is a promising cancer therapy. Epi-thermal Neutron (0.5 eV < En < 10 keV) Flux intensity is one of the basic characteristics for modern BNCT. In this work, based on the 71Ga(n,γ)72Ga reaction, a new simple monitor with gallium nitride (GaN) wafer as activation material was designed by Monte Carlo simulations to precisely measure the absolute integral Flux intensity of epi-thermal Neutrons especially for practical BNCT. In the monitor, a GaN wafer was positioned in the center of a polyethylene sphere as Neutron moderator covered with cadmium (Cd) layer as thermal Neutron absorber outside. The simulation results and related analysis indicated that the epi-thermal Neutron Flux intensity could be precisely measured by the presently designed monitor.

C Jammes - One of the best experts on this subject based on the ideXlab platform.

A L Costa - One of the best experts on this subject based on the ideXlab platform.

  • modelling effects on axial Neutron Flux in a tokamak device
    2015
    Co-Authors: Carlos E Velasquez, C Pereira, Maria Auxiliadora F Veloso, A L Costa
    Abstract:

    Abstract Using Monte Carlo N-Particle (MCNP5), three different Tokamak models using different geometries were simulated, maintaining some basic parameters from the ITER design. The Neutron Flux and the reaction rates were obtained over different volumes: FW, divertor and along the different device walls. The three geometries were compared under the same conditions. The results showed the behaviour of the Neutron Flux spectra along the different walls, as well as, the most suitable model taking in consideration the different analyses and the final purpose of adding a transmutation layer. Finally, the chosen geometry will be used to analyse the burnup, buildup, decay, and processing of material under irradiation.