In Figure no. 32 general safety solution system is presented. As first place it indicates to the best possible and proven technology with high quality workmanship and good localisation. After that it concerns methods to accident prevention, early failure's detection and control systems in case of design basis accident and severe accident as well. The 5th element of defence in depth is not a technical solution, but human organisation and management requirements. Possible and several commonly impossible scenarios should be predicted, and emergency plans for it have to be set. Generally defence in depth is to obtain the lowest possible radioactivity release probability factor by controlling both technical design's aspect and quality of service. Next points include necessary testing procedures and requirements for the test's results. Apart from safety of the reactor, general security system is to ensure no danger with nuclear power plant service. For this reason rigorous regulatory offices, good legislation and responsible human activity are crucial. [19], [82]