Preliminary results of fusion neutron streaming benchmark experiment in 1986 for polyethylene shield

The fusion neutron streaming through bent ducts, bent slits, offset slits and multi-holes in polyethylene shields was measured with TLD (thermoluminescent dosimeter), CR-39 recoil proton solid state track recorder, miniature NE213 scintillators and a proton recoil gas proportional counter. The energy dependence of the sensitivity was measured by the company at the Electro Technical Laboratory where national neutron sources were kept. The results is depicted in Fig 3.3.1. We found the sensitivity at 14 MeV should be revised to that of the dotted line. The effect of the dosimeter case which was not used in the present experiment was included in the sensitivity of the solid line. The sensitivity at lower energies is found to be valid from our calibration by a Cf-252 and a Am-Be source. The angular dependence of sensitivity was measured and depicted in Fig 3.3.2. The experimental results are shown in from Fig 3.3.3 to Fig 3.3.6 and Table 3.3.I. The miniature NE213 scintillator of Kyoto University has a small spherical head of 1 cm in diameter. The block diagram of the measurement system is shown in Fig 3.4.1. The measured results in the offset slits and multi-holes are shown in Table 3.4.III, IV and V and Fig 3.4.2 and 3.4.3. The fast neutron spectrum in the bent ducts was measured by a proton recoil spherical proportional counter. The miniature NE213 scintillator of Tokyo Institute of Technology has a spherical head of 1 inch in diameter. The block diagram of the measurement system is shown in Fig 1. It was used for the fast neutron measurement in the 40 cm square bent duct and the 5 cm wide bent slit. The experimental results are sumarized in from Table 1 to Table 3 for neutrons and from Table 4 to Table 6 for gamma-rays. The increase in counts at 90 cm in the first leg of the bent duct (Fig 5) may be due to the error of the calibration of the source. (author)