Non-physical conditions and effects of ageing

Research reactors were built according to the standards and with the equipment available at the time of construction. Since then progress in technology, especially in electronics has been made. Even if the original instrumentation and control systems of the reactor still function well, getting spare parts becomes difficult. This may make it necessary to replace the entire instrumentation and control system in order to facilitate a proper maintenance programme. 

For many research reactors, the time elapsed since their construction has brought many new safety requirements. The modification of the hardware and the updating of the documentation of the reactor should be considered accordingly. Such modifications are usually called backfitting activities. 

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