Embodiment of concept of operational quantity. Area monitoring

Appricable laws of radiation protection hazard were revised and delivered in the official gazette on May 18th, 1988. On an operational quantity of area monitoring, an ambient dose equivalent H*(10)(unit Sv) has been used by the equipments in connection with radiation protection and an absorbed dose in air (unit Gy) was used by meters for monitoring environmental radiation. Aloka's progress of remedy for equipment of area monitoring was explained. The present conditions of standards of these equipments in Japan and other countries are arranged. Two methods were used as remedy. One of them is reconstruction of usual survey meter and another is to supply new instruments. Plate, panel, electric pole and software were changed for each detector. The radioactive sources for calibration were unified to 137Cs unless 60Co and 226Ra in degree with JIS. New direct reading type 1 cm dose equivalent rate meter was developed. The historical changes of JIS and IEC standards for area monitoring were explained. (S.Y.)