APPLICATION OF WHOLE BODY COUNTER TO NEUTRON DOSE ASSESSMENT IN CRITICALITY ACCIDENTS

  • Kurihara, O. (Radiation Protection Division, Tokai Works, Japan Nuclear Cycle Development Institute) ;
  • Tsujimura, N. (Radiation Protection Division, Tokai Works, Japan Nuclear Cycle Development Institute) ;
  • Takasaki, K. (Radiation Protection Division, Tokai Works, Japan Nuclear Cycle Development Institute) ;
  • Momose, T. (Radiation Protection Division, Tokai Works, Japan Nuclear Cycle Development Institute) ;
  • Maruo, Y. (Radiation Protection Division, Tokai Works, Japan Nuclear Cycle Development Institute)
  • Published : 2001.09.30

Abstract

Neutron dose assessment in criticality accidents using Whole Body Counter (WBC) was proved to be an effective method as rapid neutron dose estimation at the JCO criticality accident in Tokai-mura. The 1.36MeV gamma-ray of $^{24}Na$ in a body can be detected easily by a germanium detector. The Minimum Detectable Activity (MDA) of $^{24}Na$ is approximately 50Bq for 10miniute measurement by the germanium-type whole body counter at JNC Tokai Works. Neutron energy spectra at the typical shielding conditions in criticality accidents were calculated and the conversion factor, whole body activity-to-organ mass weighted neutron absorbed dose, corresponding to each condition were determined. The conversion factor for uncollied fission spectrum is 7.7 $[(Bq^{24}Na/g^{23}Na)/mGy]$.

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