Management of Ageing and Modifications for Research Reactors

Egypt has two research reactors, the first reactor was designed by the Former Soviet Union, it has a power of 2MW, tank type, light water moderated and reflected and the fuel type is EK-10 that consists of Uo2 fuel rods with 10% enrichment. The reactor was commissioned on 1960, and still working until 2010, from that time it was in extended shutdown state due to ageing of mechanical systems and the termination of the fresh fuel, in the international market. Based on the in-service inspection which was implemented for the 1st reactor the following systems were modernized: 1. Computerized Safety Logic System. 2. Process parameters measurements 3. Neutron parameters measurements 4. Control circuits for the movement of control rods. 5. Control circuits for opening and closing the horizontal channels 6. Power supply systems. ( transformer and circuits) 7. Radiation protection system. A brief description and learned lessons for each modernized activity will be presented, showing the steps which were implemented to achieve the high performance and availability of the first reactor during its operation period. The second reactor was went critical in 1997, which have a good ageing management program, for all the mechanical, electrical, Instrumentation and control systems. The ageing process may lead to an increase in the failure probability of a safety barrier of a component and ultimately to the failure of the barrier. The ageing mechanism can accelerate the material degradation as, change in physical properties, irradiation embrittlement, thermal embrittlement, creep, fatigue, corrosion assisted cracking and wear. The safety principles can be achieved by protecting the defence in depth concept and preserving the safety barriers with the implementation of ageing management program. The ETRR-2 ageing management program includes; periodic maintenance activities, periodic calibration and testing program, in-service inspection. In addition, there is a program to avoid the cooling system ageing effects such as corrosion by using special chemicals to control the water quality. The ageing management program for the second Egyptian research reactor will be presented. This program was the main contributor to avoid operational deviations, anticipated operational occurrences, preserves the high availability and reliability of the reactor, keeps the components and systems in high degree of quality and improves the service conditions. (author)