A modified integral counting method (MICM) with various quenched samples (MICM-VQ) has been investigated for its applicability for different scintillators using β emitters, 14C and 35S. To assess the influence of scintillators, three sets of 14C quenched standards and two 35S cocktail series were prepared. Two sets of 14C quenched standards were used for the toluene-compatible scintillator, the other for the Ultima GoldTM scintillator. Sulfur-35 cocktail series were prepared with either EcoscintTM XR or Ultima GoldTM AB. The radioactivity of these samples was determined using the MICM-VQ, with the results conforming to assayed values. Hence the MICM-VQ can assay the radioactivity of sample cocktails with various scintillators and requires no standard sample.
The seabed soil was collected at the Soya Strait of Hokkaido in September 2015, and 134Cs derived from Fukushima Daiichi Nuclear Power Plant accident was detected at the seabed soil. It was suggested that this 134Cs migrated from the Japan Sea to the Okhotsk Sea by the Tsushima Warm Current and the Soya Warm Current.
Radiophotoluminescence (RPL) photography has been proposed for the measurement of the spatial dose distribution of high radiation fields. A pulsed UV-LED illuminator was prepared as an excitation light source for the RPL photography. The fluorescence image of RPL material was observed by a gated intensified CCD camera. In a preliminary experiment, several tens of spherical RPL detectors were placed near an intense 60Co source. The pulsed UV-LED illuminator and the gated intensified camera were pulse-operated to obtain the RPL photograph of the ball-shaped RPL detectors. The spatial dose distribution was calculated from the brightness of obtained RPL images.