Shigemasa Enomoto

Measurement of salt surface density on polluted insulators using a simple x-ray fluorescence technique

Abstract A simple x-ray fluorescence technique using a low power x-ray tube and a neon gas-filled proportional counter following a multichannel analyzer has been developed for the nondestructive and rapid measurement of the density of salt deposited on the surface of power insulators. To detect faint Cl K x-rays accurately interfering x-rays such as K x-rays from argon in the air and from composite elements of the insulator glazing material are eliminated by using an x-ray filter of 30 μm thick polyvinylidene chloride placed in front of the counter window. The technique was applied for crevis type suspension insulators of 250 mm dia, having surfaces which were artificially deposited with NaCl of 0.01 to 0.1 mg/cm2 surface density. The relative statistical error for a surface salt density of 0.1 mg/cm2 was 1.1% using a 100 s measurement time. The positional distribution of deposited salt and the time variation of salt accumulation on the insulator surfaces were also observed with the technique.

Real-time position measuring technique for a moving object with a sealed gamma-ray source attached

The position of a moving object can be noncontactually measured in real time by observing intensity from a γ-ray source attached to the object. Experimental position measurements are carried out for linear (1-dimensional) and rotary (2-dimensional) motion, and the results obtained are compared with theoretically calculated ones. On this occasion, the statistical characteristics of the γ-ray count rate observed will be varied with time. The dynamic error in the position measurement increases with increasing velocity of the object. The statistical error increases in comparison with the stationary one when the object is closing up to a detector, and decreases in the opposite motion. The system with short time constant permits quick response for change of the object position, but increases the statistical error. When a 3.4 MBq 241Am γ-ray source is used with a time constant = 94 ms, an object velocity < 100 mm/s and a detector-to-source distance < 500 mm, a dynamic/statistical (1σ) error of less than ±1022mm is obtained in the 1-dimensional measurement.

Neutron and Gamma Simultaneous Radiography Using a 2 5 2Cf Isotopic Neutron Source

In the 2 5 2Cf-based thermal neutron radiography, a thermal neutron beam always contains some gamma radiation. The resulting gamma beam will be collimated to a similar extent to the neutron beam. Attempts were therefore made to obtain neutron and gamma radiographs simultaneously. A combination of scintillator and film, showing a superior gamma-discrimination was used as a thermal neutron image recorder. A combination of lead foil and film, insensitive to thermal neutrons, was used as a gamma image recorder. These recorders were held together in a single cassette and were exposed at the same time. Successful neutron and gamma radiographs which might aid interpretation of the radiographic images were obtained. On the basis of the study, a mobil neutron radiography equipment capable of using 1 mg of 2 5 2Cf was designed and fabricated, with which the practical effectiveness of the new technique is being evaluated.

Intensification Factor of Lead Screen for γ-Ray Radiography

The intensification of gamma radiation emitted by Cs137 and Co60, as a result of multiple interactions in Pb screens, is analyzed photometrically.