An experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy.

A radiation streaming experiment has been carried out at the Takasaki Ion Accelerator Facility for Advanced Radiation Application at the Japan Atomic Energy Research Institute in a room housing a Cu target irradiated with 68 MeV protons and in a labyrinth of three-legs having a total length of 29 m. In the experiment, neutron and gamma ray energy spectra, neutron reaction rates, and neutron and gamma ray dose equivalent rates were measured using various counters and dosimeters. The experimental data show the applicability of some empirical formulas for estimating the thermal neutron flux in a room and neutrons streaming in a labyrinth designed for a proton accelerator operating in the intermediate energy region. The data suggest that it is mandatory to estimate the gamma ray dose equivalent rate in a labyrinth, which is dominated by the secondary gamma rays due to the neutron capture reaction.

[1]  Y. Uwamino,et al.  Two types of multi-moderator neutron spectrometers: Gamma-ray insensitive type and high-efficiency type , 1985 .

[2]  W. N. McElroy,et al.  A COMPUTER-AUTOMATED ITERATIVE METHOD FOR NEUTRON FLUX SPECTRA DETERMINATION BY FOIL ACTIVATION. VOLUME I. A STUDY OF THE ITERATIVE METHOD. Technical Report, April 1966--July 1967. , 1967 .

[3]  Kazuo Shin,et al.  Semiempirical Formula for Energy-Space Distributions of Streamed Neutrons and Gamma-Rays in Cylindrical Ducts , 1988 .

[4]  G. T. Seaborg,et al.  Table of the Isotopes , 1948 .

[5]  L. Greenwood.  Extrapolated neutron activation cross sections for dosimetry to 44 MeV , 1978 .

[6]  John Hale,et al.  Data for Protection Against Ionizing Radiation from External Sources: Supplement to ICRP Publication 15 , 1974 .

[7]  J. Cossairt,et al.  Radiation measurements in a labyrinth penetration at a high-energy proton accelerator. , 1985, Health physics.

[8]  Takashi Nakamura,et al.  Measurement and calculation of neutron leakage through labyrinth from 35 MeV proton accelerator room , 1992 .

[9]  T. Nakamura,et al.  Thermalization of accelerator-produced neutrons in a concrete room. , 1991, Health physics.

[10]  C. E. Clifford,et al.  PHENOMENOLOGICAL THEORY OF THE ATTENUATION OF NEUTRONS BY AIR DUCTS IN SHIELDS , 1952 .

[11]  H. Yamakawa,et al.  Measurement of Response Functions of Organic Liquid Scintillator for Neutron Energy Range Up to 390-MeV , 1995 .

[12]  T. Nakamura,et al.  Measurement and calculation of neutron leakage from a medical electron accelerator. , 1986, Medical physics.

[13]  H. Nakashima,et al.  Monte Carlo calculation and measurement of energy response of a solid state nuclear track detector to neutrons from 100 keV to 20 MeV , 1997 .

[14]  K. Tesch,et al.  THE ATTENUATION OF THE NEUTRON DOSE EQUIVALENT IN A LABYRINTH THROUGH AN ACCELERATOR SHIELDING , 1981 .

[15]  T. Nakamura,et al.  [Shielding design and detection of neutrons from medical and industrial electron accelerators--simple method of design calculation for neutron shielding]. , 1986, Radioisotopes.

[16]  D. Rogers,et al.  EGS4 code system , 1985 .

[17]  C. L. Dunford,et al.  ENDF-102 Data For-mats and Procedures for the Evaluated Nuclear Data File ENDF-6 , 1997 .

[18]  W. Schimmerling,et al.  3-GeV Protons on Pb Neutrons Streaming through a Labyrinth , 1969 .

[19]  S. Selvī,et al.  Albedo Analytical Method for Multi-Scattered Neutron Flux Calculation in Cavity , 1986 .

[20]  H. W. Patterson,et al.  Accelerator Health Physics , 1973 .

[21]  Y. Uwamino,et al.  Propagation of Errors from Response Functions to Unfolded Spectrum , 1981 .

[22]  K Goebel,et al.  Evaluating dose rates due to neutron leakage through the access tunnels of the SPS , 1975 .

[23]  Y. Uwamino,et al.  Transmission of Intermediate-Energy Neutrons and Associated Gamma Rays Through Iron, Lead, Graphite, and Concrete Shields , 1991 .

[24]  J. F. Briesmeister.  MCNP-A General Monte Carlo N-Particle Transport Code , 1993 .

[25]  Richard B. Firestone,et al.  Table of Radioactive Isotopes , 1986 .

[26]  G. R. Stevenson,et al.  Attenuation of radiation in tunnels penetrating the shield of an extracted beam of the 7 GeV proton synchrotron Nimrod. , 1973, Health physics.