Rapid, in situ measurements were used for quantitative monitoring of gaseous fission products around the nuclear power stations
in Taiwan. A portable high-resolution germanium detector with portable multichannel analyzer was used in the field monitoring
work. The detecting unit was calibrated using activated Ar, Kr, and Xe isotopes dispersed in a large chamber to obtain absolute
efficiency curve in terms of γ-counts per m3 versus gamma-ray energy. The calibrated detecting unit was brought to the nuclear power plants for in situ monitoring for
both normal operation and nuclear accidental exercise. In a typical four-hour measurement, the detection limits for most Kr
and Xe fission product isotopes were 0.0028%≈0.98% of the derived air concentration (DAC) imposed by the local authority.
The dose rate caused by gaseous radioisotopes released from nuclear power stations and dispersed to the surroundings can be
quantitatively monitored in a short period using this portable unit.