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Study of the radiation resistance of cables with mineral insulation

Project Status: 6 Project underway
Commencement Date: 05.03.2022
Duration in months: 0 months

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Participating Institutions



Institute of Nuclear of Physics of the Ministry of Energy of the Republic of Kazakhstan



Japan Atomic Energy Agency



In the modern world, the role of nuclear energy and nuclear technologies is of great importance. Nuclear power is a permanent source of energy and characterized by zero carbon dioxide emissions into the atmosphere, which is an important factor in combating against global warming. Nuclear technologies have become widespread and are used in many areas of human life. For example, diagnostics and treatment of cancer diseases is performed with radiopharmaceuticals, which are also produced in the nuclear reactors. The method of neutron-transmutation doping of silicon, implemented in the nuclear reactors, makes it possible to obtain semiconductors for further use in power electronics and solar batteries. With the help of nuclear reactors, special radioisotopes are produced, which are the main element of the "eternal" batteries that produce electricity. The area of application of nuclear reactors is wide and for implementation of all these tasks it is necessary to provide their safe operation. The systems for monitoring physical and technological parameters are used to control the state of the nuclear reactor. The main part of these systems (detectors) is located in the places of radiation field, which reduces the operation resource of this equipment. The measuring equipment is located in the control rooms and/or experimental rooms and it is necessary to provide their connection with the detectors. Signal cables are used for this purpose, which are also located in the radiation fields, leading to destruction of their insulation, followed by a break. Therefore, research and development of the radiation-resistant cables are relevant and in demand all over the world.

Vinyl, polyvinyl chloride (PVC), rubber or polyethylene are typically used as insulation material for signal cables. These materials are destroyed as a result of interaction with neutron and gamma radiation and high temperature, leading to a change in electrical characteristics and to further cable breakage. Radiation-resistant signal cables can be used not only during normal operation of any nuclear reactor, but also in emergency situations. For example, after the severe accident at the Fukushima-Daichi nuclear power plant at the end of 2012, the issue of monitoring the situation at the nuclear power plant became acute in Japan. The cables available at that time did not withstand the operating conditions characterized not only by radiation environment, but also by high temperatures.

Mineral insulation has been accepted as a candidate heat-resistant insulation material for signal cables. Insulation materials are high purity magnesium oxide (MgO) or aluminum oxide (Al2O3). Preliminary assessments of the study feasibility were carried out by the Japanese Atomic Energy Agency. The studies were carried out at high temperatures. The test cables (experimental samples) were fabricated for this purpose. Research results have confirmed the stable operation of the mineral-insulated cables and a sufficient insulation resistance value even at 1000 °C.

In the proposed study, it is planned to investigate the radiation resistance of two types of mineral-insulated cables (MgO and Al2O3) at high temperatures. Such electrical characteristics as current conductivity, insulation resistance, voltage and current will be studied during irradiation of the cables in the core of the reactor WWR-K. It should be noted that all measurements will be performed online, i.e. in the process of irradiation, which increases the worth of the obtained results. At this stage, the temperature of cable irradiation at the level of 500 °C is considered due to the fact that this temperature is the average temperature of the planned operation at the nuclear power facilities and intensive formation of the radiation-induced defects is possible in the cable insulation material at such temperature.

It is planned to irradiate the signal cables in one of the irradiation channels of the research reactor WWR-K until the fast neutron fluence (>0.1 MeV) of 10^20 сm^(-2) is reached. For this purpose, the experimental device will be specially designed to provide the required conditions and to perform online measurements of electrical characteristics of the cables with mineral insulation.

The obtained results will make it possible to qualify a cable with mineral insulation and make conclusions about the possibility of its further application at the nuclear power facilities. The results will be interesting and in demand not only in the area of nuclear energy, but also in the area of thermonuclear energy, also characterized by radiation field and high temperatures. In thermonuclear fusion plants, it is mainly planned to use fiber optic fibers to transmit signals, which are also subject to the influence of radiation on their properties, so many countries are performing research and development works on development of the radiation-resistant optical fibers. Mineral insulated cable can become an alternative to optical fiber for application in the thermonuclear facilities.

The proposed project is fully consistent with the development goals of the Republic of Kazakhstan until 2025, indicated in the Strategic Development Plan of the Republic of Kazakhstan until 2025. Kazakhstan joined the Paris Climate Agreement and now pledges to reduce greenhouse gas emissions by 15% by 2030. And the sustainable development of nuclear energy will make its contribution to reducing carbon dioxide emissions into the environment. The obtained results will contribute to technological modernization of the global nuclear power industry and provide its sustainable development.