Development and testing of modular inflammable glass-paper fine-purification filters

Abstract

The operation of a nuclear object necessarily entails the release of radioactive substances by technological setups into a gas phase. In this case, efficient nnd reliable operation of gas-purification systems is a necessity to ensure the radiation safety of the general public and workers. Petryanov filters (LAIK type) are now widely used at the Mayak Industrial Association to purify the exhaust air and process discharges. However, the Petryanov fabrics (FPP-15-1.5, FPA-15-2.0) used in such filters are flammable because of the polymer base and the gauze substrate, which makes it impossible to use them in technical alterations where the filters must satisfy stringent fire-safety requirements. In addition, according to NP-021 [1] the aerosol filters and materials which are used in their fabrication must not support combustion processes. In this connection, specialists at the company Plazmofil’tr (St. Petersburg) have proposed as alternatives to Petryanov filters the inflammable filters of the FTOV-Bm type made of glass paper based on microthin glass fibers [2]. Subsequently [3], the Mayak Industrial Association working jointly with the Plazmofil’tr company developed and prepared working drawings of another 14 size-types of modular-type modified glass-paper fine-purification air filters (FTOV-SBM) (see Table 1). In addition, specialists at Mayak developed a design for a quickly dismountable glass-paper filter of the D-19F (FP 30.266.000SB) type ‐ an analog of the D-19M filter. To decrease flammability and to meet the requirements of first-class fire protection, the plywood case and the wooden components of the filters were covered, during fabrication, with three layers of the biopyrene Pirilaks [4]. One advantage of the modified filters is that the dimensions and connecting components are the same as those of standard Petryanov filters. This permits using the modified filters in the currently used ventilation systems without any additional assembly work. A special feature of the FTOV-SBM filters is the Λ- and M-shape configuration of the filtering componets. The working drawings were used to fabricate an experimental batch of FTOV-Bm, FTOV-SBM, and D-19F filters. Glass-paper filtering components were used in the modules of the experimental-prototype FTOV-Bm filters. These components were fabricated by the Plazmofil’tr company using domestic microthin glass fiber. A filtering material manufactured by the J. C. Binzer Company (Germany) for high-efficiency purification of air was used to fabricate the FTOV-SBM modified filters. Modules with aluminum cases, instead of wooden cases, can also be used to assemble filters of this type. As reported previosuly [2], to perform prototype tests in 1996 two glass-paper filters of the FTOV-Bm type (Nos. 1 and 4) were placed on a system for purifying exhaust air from the rooms in the first zone of a plant reprocessing spent nuclear fuel. Standard D-9U Petryanov filters (Nos. 2 and 3), equipped with FPP-15-4.5 fabric, are mounted in parallel with the experimental filters.