radiochemical laboratory[¦rad·ē·ō′kem·ə·kəl ′lab·rə‚tȯr·ē]
a specially equipped laboratory for carrying out chemical operations with radioactive substances. (Investigations using tracer atoms that are carried out in various branches of science and industry, such as metallurgy, machine building, and biology, are conducted in radioisotope laboratories with special features, including smelting furnaces, vivariums, and arboretums.) All work with radioisotopes and the radiochemical laboratories themselves are divided into three classes, depending on the toxicity group of the isotope used, the radioactivity (activity) of the isotope at the workplace, and the complexity of the chemical operations. The class of a radiochemical laboratory determines the protective measures to be used in providing safe working conditions for personnel and preventing contamination of the environment. The protective measures include a rational layout and separation of areas, efficient systems for ventilation and plumbing, adherence to the norms and rules of radiation safety, the organization of a system for transporting, receiving, storing, and accounting for radioisotopes and for collecting and removing radioactive wastes, the selection and development of safety techniques and equipment, and the prediction of possible accidents and the development of contingency plans to deal with such accidents. The unregulated disposal of gaseous, liquid, and solid radioactive wastes from radiochemical laboratories of all classes is prohibited.
Radiochemical laboratories of the third class are designed for working with minimal, or tracer, activities. In these laboratories, most analytical, chemical, and biological investigations are carried out using radioisotopes as isotope tracers. Protective clothing, plastic or stainless steel cells, simple remote-control devices (forceps, tongs), and screens made of lead or polyme-thyl methacrylate are used to protect personnel from radioactive radiation and contamination. Work with emanating substances, which form radioisotopes of radon, and with volatile or powdery substances is carried out in boxes or ventilation hoods. Respirators, gas masks, and special plastic clothing are examples of the additional protection that is provided. It is recommended that radiochemical laboratories of the third class have a shower and a place for storing and packing radioactive substances.
Radioactive laboratories of the second class are designed for work involving a moderate level of radioactivity. Included here are certain types of radiochemical, physicochemical, metallo-physical, physical, and biological work. These laboratories are located in separate buildings or in insulated sections of buildings. Facilities are provided for the rapid and effective decontamination of the room and equipment with detergent solutions. Operations with radioactive substances are carried out in boxes or ventilation hoods with the aid of various devices for remotecontrol manipulation. Gloved openings can be built into the side wall. The laboratory should have a decontamination center or shower for decontaminating personnel and the special plastic clothing, a radiation control (dosimetric) point at the exit, and a storage area for radioisotopes and wastes.
Radiochemical laboratories of the first class (hot laboratories) are designed for work involving high levels of radioactivity, levels that do not possess an upper limit. They are equipped to handle operations that separate radioisotopes from the fission products of nuclear fuel, irradiated materials and targets, and the accumulated fuel elements of nuclear reactors and other operations requiring the hermetic sealing of the equipment. Such radiochemical laboratories are located in separate buildings or in insulated sections of buildings, entry into which must be through a decontamination center.
To increase operational safety, class 1 laboratories have a three-zone layout. Zone 1, which is the main source of radioactive contamination, has cells and boxes housing the equipment that actually works with radioactive substances. These housings are not entered by personnel. Zone II includes areas, periodically entered by personnel, for repairing the equipment, transporting, loading, and unloading radioactive materials from zone 1, and storing radioactive wastes. Zone III includes the control panels and the operational areas normally entered by personnel. In order to prevent the transfer of contamination from zone II to zone III, a special gate is set up as a point of dosimetric control. All work with radioactive substances is carried out in the hermetically sealed boxes and cells using remote-control manipulators. The work can be observed through periscopes, lead-glass windows, and closed-circuit television. The extent to which the equipment is sealed and the reliable biological safeguards ensure complete safety for personnel working in zone III. The service personnel in zone II work in hermetically insulated suits for periods of time that are within permissible limits. Service personnel enter zone I only in the case of accidents or after decontamination to permissible levels has been effected by remote-control devices. The safety of the laboratory and the protective measures used are supervised by the radiation safety service.
REFERENCESReformatskii, I. A. Laboratorii dlia rabot s radioaktivnymi veshchestvami. Moscow, 1963.
Osnovnye sanitamye pravila raboty s radioaktivnymi veshchestvami i drugimi istochnikami ioniziruiushchikh izluchenii (OSP-72). Moscow, 1972.
Normy radiatsionnoi bezopasnosti (NRB-69), 2nd ed. Moscow, 1972.
V. K. VLASOV