Field photon energy spectra in Fukushima after the nuclear accident

SIMPLIFIED PRACTICAL TEST METHOD FOR PORTABLE DOSE METERS USING SEVERAL SEALED RADIOACTIVE SOURCES

Sealed radioactive sources which have small activity were employed for the determination of response and tests for non-linearity and energy dependence of detector responses. Close source-to-detector geometry (at 0.3 m or less) was employed to practical tests for portable dose meters to accumulate statistically sufficient ionizing currents. Difference between response in the present experimentally studied field and in the reference field complied with ISO 4037 due to non-uniformity of radiation fluence at close geometry was corrected by use of Monte Carlo simulation. As a consequence, corrected results were consistent with the results obtained in the ISO 4037 reference field within their uncertainties.

Application of a CZT detector to in situ environmental radioactivity measurement in the Fukushima area

Instead of conventional Ge semiconductor detectors and NaI(Tl) scintillation spectrometers, an application of a CdZnTe semiconductor (CZT) whose crystal has the dimension of 1 cm cubic to the in situ environmental radioactivity measurement was attempted in deeply affected areas in Fukushima region. Results of deposition density on soil for (134)Cs/(137)Cs obtained seemed consistent, comparing obtained results with those measured by the Japanese government.