Control of Oxygen Content in Lead Coolants
Development of Oxygen Sensors, Systems of Control of Oxygen Content in Lead Coolants for Test Loops and Facilities
Tech Area / Field
- MAN-MAT/Engineering Materials/Manufacturing Technology
8 Project completed
Senior Project Manager
Mitina L M
FEI (IPPE), Russia, Kaluga reg., Obninsk
- Royal Institute of Technology, Sweden, Stockholm\nMcMaster University, Canada, ON, Hamilton\nEURATOM-Ciemat, Spain, Madrid\nENEA, Italy, Bologna\nRamon Llull University / Institut Quimic de Sarria, Spain, Barcelona\nSCK-CEN, Belgium, Mol\nCEA / DEN / Département de Technologie Nucléaire, France, Saint-Paul-lez-Durance\nForschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft / Institut fuer Hochleistungsimpuls- und Mikrowellentechnik, Germany, Eggenstein-Leopoldshafen
Project summaryThe main goals of the Project are as follows: development of technology of fabrication of oxygen sensors on the basis of galvanic concentration cell for the control of content of oxygen dissolved in lead melts; development of systems of oxygen content control in lead coolants.
The following problems are supposed to solve within the framework of the Project: 1) Development of oxygen sensors on the basis of galvanic concentration cell. 2) Development of principles and devices for measurement and control of oxygen content in lead coolants. 3) Taking measures aimed at the achievement of goals and solution of the problems of the Project.
Amount of oxygen in lead-bismuth eutectic (as well as in lead) and in the circuit as a whole is quite important factor, which is responsible for normal operation of experimental static facility or experimental circuit using steel as structural material. Excess of oxygen would result in slagging in the circuit (i.e. disturbance of their thermal and hydraulic characteristics), while at low oxygen content, dissociation of the oxide protective coating on the structural materials and corrosion processes. Therefore, on the stages of construction and operation of circuits with Pb-Bi eutectic and implementation of any processes in these circuits, it is necessary to control oxygen content in the eutectic. Both oxygen content (C0) and its thermodynamic activity (a0) are usually controlled in lead-bismuth (lead). Relationship of these parameters is as follows:
where С0S – oxygen saturation content in lead-bismuth (lead).
Current status of technology makes it possible to implement such control using oxygen sensors based on galvanic concentration cell (GCC) with solid oxide electrolyte. Use of this GCC assures high speed of response of sensors, their high sensitivity, presentation of output signal as voltage, reliability and stability of operation within the wide range of temperature and oxygen partial pressure values under condition of moisture and radiation. Oxides of zirconium, germanium, thorium and calcium with various stabilizing additions and their compositions are used as solid oxide electrolytes. Properties of each type of oxide electrolyte are determined by its chemical composition, ratio of structural forms (cubic, monoclinic, etc.) of each oxide, amount of impurities and stabilizing additions. Specific type of electrolyte and its properties are chosen proceeding from technical and operating requirements to oxygen sensors, namely: corrosion activity of medium under study, the range of measured a0 values, temperature and hydrodynamic conditions, pressure, required time of continuous operation of sensors, conditions of their decommissioning and putting into operation and many other factors. Sensor design is also determined by these factors, as well as by required operating reliability, number of sensors, their permissible cost and possible overall dimensions. In principle, a variety of sensor designs can be considered including test-tube type sensors (with oxide electrolyte made as test-tubes of various configuration and size) and pellet type sensors (electrolyte as various size pellets). These sensors are quite different in terms of manufacture problems and cost (from several tens to several thousand USD).
Irrespective of the choice of the type of electrolyte and sensor design, the following additional problems should be solved in the process of each development: a) Analytical and experimental justification of structural materials of vessel, current terminals, sealant, etc. b)Choice of reference electrode (basic standard) for sensor. c)Development of technology of fabrication of solid electrolyte. d)Development of technology of solid electrolyte connection to the sensor body. e) Development of technology of fabrication of sensor as a whole. f) Fabrication of sensors and experimental confirmation of correctness of chosen approaches on the stage of sensor tests under conditions modeling working parameters.
All above problems should be solved by the Project applicants at the SSC RF – IPPE in the course of fulfillment of Task 1. As a result of it, technology of fabrication of «test-tube» type oxygen sensors will be developed to assure proper operation and carry out studies in the flowing and static lead containing coolants. Tested sensors (at least, 3 items) will be used for tests on the development of oxygen TDA automatic control system (Task 2).
Within the framework of studies on justification of set of technological means of lead coolant, tests of four designs of mass exchangers using solid-phase method of oxygen TDA control in lead coolant were performed at the SSC RF-IPPE in 2000-2001. These mass exchangers are designed for lead coolant test facilities of the SSC RF–IPPE and other organizations. Use of pressed lead oxide spheroids as solid-phase source of dissolved oxygen has been justified.
Within the framework of declared ISTC Project, MX designs with automatic control system will be developed (this development has just been started at the SSC RF-IPPE). Design of mass exchanger for the loop-type facilities implies a combination of reaction vessel filled with PbO spheroids with one or more electric heaters or a pump embedded in the vessel. Thus, dissolving of oxygen source in mass exchanger may be intensified depending on the circuit needs (analysis of readings of oxygen TDA sensors) by either internal heater or related pump (increase of coolant flow rate), or by the use of combination of the heater and pump. Dissolving of oxygen source in mass exchanger may be intensified depending on the circuit needs (analysis of readings of oxygen TDA sensors) by either internal heater or related pump (increase of coolant flow rate), or combination of the heater and pump. Three mass exchangers will be manufactured for the loop-type facility of the SSC RF-IPPE proposed for the use in the Project (coolant mass ~ 2000 kg): one mass exchanger with the built-in pump, one with the internal heater and one using combination of pump and heater.
Small size static facility (coolant mass 5 to 10 kg) will be created within the framework of the Project. Small size chuck-type MX will be created for this facility: MX filled with PbO spheroids having neither internal heater nor pump.
Task 2 of the Project implies development of the system of automatic control of oxygen TDA (TDA ACS). It should be noted that all MX designs will be tested in specially prepared facilities (circuit and static facilities) first in the mode of manual control (by the operator), and then using TDA ACS now under development. Parameters of tests are as follows: reckoned time of continuous operation – 1000 hours; max temperature (test section) – 550 °С; min temperature (heat exchanger and pump) – 420 °С (200 °С – for lead-bismuth); coolant velocity (in the circuit) – 1–2 m/s; specified TDA range: Е = 350–370 mV at Т = 550 °С. As a result of solution of the second task of the Project, devices of automatic control of oxygen potential of lead-bismuth (lead) coolant will be developed. These devices would make it possible to carry out experimental studies on heavy liquid metal coolants in static and dynamic facilities under conditions excluding corrosion and slagging processes.
Large experience gained by the SSC RF-IPPE during more than 30 years of activities related to design and successful operation of nuclear power plants and experimental facilities with liquid metal coolant is a basis for successful fulfillment of tasks of this Project. Qualification level of the SSC RF-IPPE specialists involved in the Project is rather high: there are three Doctors of Technology (including two Professors) and 9 Candidates of Technology or Physics and Mathematics, as well as many high qualification engineers. These specialists have patents, publications and papers on the topics related to the control of impurities in the liquid metals (lead, lead-bismuth and gallium). Research equipment is available in the laboratory for preparation and carrying out tests of oxygen sensors, mass exchangers and pilot systems of automatic control of oxygen TDA for both static and dynamic conditions of lead coolant.
The following results of the Project are expected: full scientific and technological justification of manufacture of «test-tube» type oxygen sensors to assure reliable operation of lead coolant facilities under static and dynamic conditions; batch of pilot oxygen sensors (3 items); one modified and one new static facilities for testing oxygen sensors in liquid lead (lead-bismuth); justification of solid-phase method of oxygen TDA control in lead-containing coolants and various mass exchanger designs for its implementation under static and dynamic conditions; manufacture of pilot MX with built-in heaters, pump and their combination (2 items of each design); creation of pilot systems of oxygen TDA automatic control for static and dynamic test facilities with coolants on the lead base.
Applied significance of proposed Project is in that its results will make it possible to use “oxygen” technology for assuring efficient and reliable operation of research and commercial facilities with lead coolants.
Proposed Project fully meets the main goals and tasks of the ISTC, since this Project:
- provides the opportunity for scientists and engineers of the Russian Federation involved in weapons area of industry (in particular, those who had knowledge and skills in weapons of mass annihilation and missile delivery systems) to change for the peaceful activity;
- supports basic and applied research and development of technologies for peaceful purposes aimed finally at the scientific and technological progress in the area of creation of new materials and environment control;
- facilitates solution of national and international technical problems (others than those mentioned above).
The role of foreign collaborators in the implementation of the Project is as follows: direct participation (or participation in the form of consultations) in the statement of theoretical and experimental problems; information exchange in the course of implementation of the Project; making comments to technical reports submitted by the Project participants; participation in technical inspection of activity on the Project; holding joint workshops; evaluation of methods and technologies developed in the course of implementation of the Project; discussion on the ways of application of Project results. Joint activity with the foreign collaborators on this Project will undoubtedly facilitate integration of the Russian scientists in the world scientific association.
Time required for the work fulfillment on this Project is 24 months.