[en] A multi-filter cassette designed and developed for personnel monitoring of radiation workers is described. This cassette incorporates six filters; 1 mm Cd, 1 mmPb, 1 mmCu, 0.15 mm Cu, 1 mm plastic and open window. The aim of bis multi-filter system is to identify the type or types of radiation to which a person is exposed and thus to avoid the normal errors encountered in film dosimetry because of the frequent absence of definite information on the quality of the incident radiation. The advantage of this multi-filter system is that it can be used for monitoring X-rays of all qualities, gamma rays, beta particles, and thermal neutrons. Experience has shown that the ready identification of the type or types of radiation to which a person is exposed is an extremely Important step In limiting future exposures. The film used is the Kodak PM type 2, which Incorporates two emulsions of widely different sensitivities, thus enabling the coverage of a wide range of exposures. The dose ranges covered by this system are 10 mrem to 1000 rem for gamma rays, 1 mrem to 50 rem for low-energy X-rays and 15 mrem to 1500 rem for beta particles. Thermal-neutron doses up to 200 rem can be measured by this system when such thermal-neutron exposures occur in conjunction with gamma exposure, as in a reactor environment. A separate Kodak type A film In a separate holder is used for estimating fast-neutron doses up to about 5 rem. Problems such as the minimum doses measurable, the accuracy of dose estimation, and dose estimations In cases of mixed radiation exposures, are discussed. The methods followed in the maintenance of dose records are also mentioned. These records have been analysed to obtain the radiation dose per week per worker for each institution In India. Yearly data of institutions show a gradual lowering of the occupational exposure levels. (author)

[en] A composite high-level radiation monitoring system has been developed for personnel monitoring in cases of criticality accidents and other high radiation exposure Incidents. This system incorporates (1) a chemical threshold detector containing tetrachloroethylene overlayered with an aqueous solution of bromocresol purple dye which changes colour at a threshold of 20 rad of cobalt-60 gamma exposure, (2) a lead-shielded silver activated phosphate glass for measuring gamma dose from 50 to 1000 rad, (3) a sulphur pellet for the estimation of fast neutron dose down to one rad, (4) bare and cadmium-covered gold foils for the estimation of thermal-neutron dose, and (5) an Indium foil for the immediate sorting out of persons subjected to high neutron exposures. This system is used in conjunction with a six-filter film badge which uses a Kodak Type-II film. This film is capable of measuring gamma doses up to 1000 rad. The performance characteristics of this system are discussed. (author)