The Atomic Bomb Dome in Hiroshima. The atomic bombings at the end of the Second World War demonstrated the devastating effects of nuclear weapons and ionising radiation. The peaceful use of nuclear energy therefore developed with a strong emphasis on nuclear safety.

Electricity must be generated economically and in sufficient quantities, but also with due regard for people and the environment. The energy of fire has been known to humanity since the dawn of civilisation. People gradually learned about its potentially harmful effects and how to use fire safely. Nuclear energy, however, is a much more recent discovery, and public awareness of its enormous power was strongly shaped by the atomic bombings at the end of the Second World War. Quite naturally, people were concerned about what would happen if a nuclear fission reaction got out of control.

From the very beginning of the peaceful use of nuclear energy, strict safety measures have therefore been applied. The set of principles and measures referred to as nuclear safety is intended to ensure that nuclear energy is used safely. Safety systems and procedures are continuously improved as experience is gained from the operation of nuclear power plants and lessons are learned from incidents and accidents. Operator training and safety culture have also developed considerably.

Nuclear power plants use multiple independent levels of protection so that the failure of a single component or system does not compromise safety.

What is Nuclear Safety?

A very important part of the nuclear power plant operator’s practical training is simulator training. It takes place in an accurate copy of the actual control room where operators learn how to handle various standard, as well as non-standard, situations.

Nuclear safety is the ability of a nuclear facility and its operators to keep the fission process under control, ensure adequate cooling of the nuclear fuel and prevent the uncontrolled release of radioactive substances into the environment. Its goal is to prevent accidents and minimise their consequences. In the event of an accident, any release of radioactive substances into the environment and its harmful effects on people and the environment must be minimised.

The easiest and most effective method is accident prevention, and every nuclear power plant implements numerous measures to achieve this. Firstly, the plant is designed with multiple levels of protection and redundant safety systems that complement the inherent safety characteristics of the reactor. In many situations, inherent physical characteristics and passive safety features can help stabilise the reactor without operator intervention or external power. In addition, safety-related equipment is regularly inspected, tested and maintained in order to detect possible failures. Critical safety functions are generally provided by redundant and, where appropriate, diverse systems.

Operator training and testing are also very important to ensure that personnel are able to respond correctly to abnormal situations. Automation, operating procedures and engineered safety features also help to prevent or mitigate the consequences of human error.

A nuclear power plant is designed to cope with a wide range of postulated equipment failures and accident conditions. Safety systems are provided to prevent such events from escalating and to mitigate their consequences. Events considered in the design include design basis accidents, for which the plant must meet specified safety criteria and prevent unacceptable radiological consequences. Modern nuclear power plants also consider more severe accident conditions in their design and provide additional measures to prevent large radioactive releases and mitigate the consequences of severe accidents.

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Safety systems use redundancy and, where appropriate, diversity to ensure that essential safety functions remain available even if individual components fail.