Basalt Fiber Based Filters
Development of Highly Effective Filtering Systems on the Basis of a Super-Thin Basalt Fiber for Radioactive Aerosols Purification and Creation of a Work Cycle for Filters Manufacturig with the Purpose of Their Operation at the Nuclear Power Plants
Tech Area / Field
- FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
- ENV-APC/Air Pollution and Control/Environment
8 Project completed
Senior Project Manager
Rudneva V Ya
A.I. Alikhanyan National Science Laboratory, Armenia, Yerevan
- Research Center For The Problem Of The Non Proliferation Of Weapons Mass Destruction, Armenia, Yerevan
- Nuclear Safety Solutions Limited, Canada, ON, Toronto
Project summaryThe Armenian highland is one of classical regions of ancient volcanism. Among the typical rocks, a most unique position holds basalt. In 2003 fabrication of super-thin basalt fiber was developed in Armenia. Super-thin basalt fiber is characterized by the following technical parameters:
- Average fiber diameter: 2-3 microns;
- Density: 20-23 kg/m3;
- Water content: 2 %
- Operating temperature: from -2600С to +7500С.
Basalt fibers are widely known and used in construction, engineering, shipbuilding, power engineering, etc. Super-thin basalt fiber can be successfully used in nuclear power industry for decontamination of radioactive aerosols. Nuclear power plants of Russia and the former USSR countries widely use filter materials "FP" (Petrjanov filters) consisting of ultra-dispersed fibers of polymeric resins deposited on a fabric substrate. Petrjanov filters provide high efficiency of decontamination at rather low aerodynamic resistance.
Annually nuclear power plants use 200 batch filters (with a volume of 0.5 m3 each) of D-23L type which provide efficient air purification and decrease of released activity to allowable norms. In recent years permissible rates of NPP radioactive discharges become more and more rigorous. It causes to search low-cost filter materials with high performance of decontamination. At normal NPP operation, when radioactive releases are mainly aerosols with particles sized 1-20 microns at low concentration (approximately 0.1-0.5 mg/m3), Petrjanov filters function efficiently enough. FP filters at NPPs are changed once a year. The change of Petrjanov filters is a complicated and expensive operation. Besides, the problem of utilization of used filters is not solved till now. They cannot be burned because of emission of toxic substances. As for their burial, the questions of fire hazard, emission of toxic substances, and large volumes remain open.
To catch aerosols, various methods and materials have been proposed for NPPs. At present as a rule, the methods of fine cleaning of ventilation air of NPPs from highly dispersed aerosols is based fibrous filters. Introduction of filters on the basis of super-thin basalt fiber will lead to the following advantages in comparison with FP:
- Higher operating temperature. Super-thin basalt fiber can operate constantly at 7500С and for a brief time up to 9000С.
- It does not disintegrate under effect of "heating-cooling" thermal cycling and preserves its characteristics and geometrical shape at heat cycling.
- Low density and high thermal stability.
- Chemical resistance.
- Incombustibility, fire and explosion safety.
- Ecological cleanness. It does not contain organic and carcinogenic substances.
- Nonsusceptibility to fungi and mildew.
- Resistance to ultraviolet light and vibrations.
To protect the population and environment from NPPs radioactive releases, it is proposed to investigate efficiency of the filter systems on the basis of super-thin basalt fiber for decontamination of radioactive aerosols for the Armenian NPP, determine their optimum parameters and - on the basis of the obtained data – to develop an effective and rather inexpensive method of their manufacture. Besides, it is proposed to develop production a method of utilization of used filters after their removal from service.
Numerous works in this sphere are known which were carried out in EU and other countries, building their energy policy upon NPP operation and putting new blocks in operation. It seems expedient to use in the proposed project the achievements of organizations having wide experience and developments in the area of designing and implementation of measures on protection of the population, personnel and environment from radioactive discharges from nuclear power plants.
The final objective of the project is creation of a functional highly efficient filtering system for decontamination of radioactive aerosols from nuclear power plants. To realize the objective, it is necessary to:
- Study - on the basis of physical models - inertial, diffusion, sedimentation effects, as well as entanglement effect and sieving effect of filters on the basis of super-thin basalt fiber.
- Carry out study of the dependence of filtration coefficient on parameters of the filtering systems to be created.
- Calculate optimum parameters of filtering systems as well as air flow velocities at which the filter effectiveness reaches maximum values.
- Specify all technical characteristics of filtering systems and - on their basis - obtain needed licenses from regulating authorities of the Republic of Armenia.
- Manufacture a pilot batch of filters, sufficient for operation of one of the exhaust systems of Armenian NPP.
- Install the filters in one of the exhaust systems of Armenian NPP and to carry out designer's technical supervision of the system during 1 year.
- Carry out measurements of initial activity of aerosols, their concentrations after passing the decontamination system, as well as activity of filters with deposited aerosols, using low background spectrometric devices.
- Develop a method of manufacture filters on the basis of super-thin basalt fiber.
- Develop a method of utilization of used filters after their removal from service.
Taking into account considerable cheapness of manufacturing these systems (in comparison with Petrjanov filters and other high performance systems) it is possible to expect an increased that demand for such filtering systems.
Participant organizations have sufficient experience in carrying out the above stated works. It is natural that reorientation of activity of scientists and engineers involved earlier in production and testing of nuclear weapon will allow to realize their scientific and technical potential in the area of protection of the population and environment.
Implementation of the project will allow to solve the tasks meeting ISTC goals and objectives:
- Reorientation and supporting of long-term professional of activity scientists and specialists, involved earlier in defense programs, for the solution of essential civil tasks.
- The project will allow former weapons scientists to reorient their activity and gain knowledge of environment protection. This fact is essential for Armenia, as the country operates NPP.
The project collaborators are recognized leaders in the area of filter system development, protection of the population and environment from NPP radioactive releases. Their participation in the project will ensure continuity in methodological and technical approach to the tasks to be solved by the project.
Experience gained during the project implementation could be used by the countries building their energy policy upon operation and construction of new NPPs.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.