Stress tests of nuclear power plants in Slovakia
The accident at the NPP Fukushima Dai-ichi has forced the whole world to reflect on whether the nuclear power plants are operated safely and whether their level of safety and reliability is appropriate. Immediately after the accident the European politicians, ministers from the Member States, representatives of the nuclear industry and the regulated entities agreed at the European diplomatic level to carry out safety reviews of nuclear power plants. All 15 Member States of the European Union (EU) operating NPPs acceded to this process and also the neighbouring states to the EU, Switzerland and Ukraine joined in.
In order to achieve equal access to safety reviews, the European Nuclear Safety Regulators Group (ENSREG) and the European Commission (EC) issued a Declaration containing the specification of the stress tests (ST).
Objective of the Testing
The aim of the stress tests was to determine to what degree of external threat the NPP is able to withstand without serious damage to the nuclear fuel in the reactor core, or without significant release of radioactive material to the environment.
Another objective was to evaluate the ability of existing NPPs and their staff to cope with extreme weather conditions, which may ultimately result in the loss of essential safety functions of the power plant. In other words, to demonstrate that the NPPs operating in the EU, have an appropriate level of safety and do not represent an unreasonable risk to people and the environment even under extreme external influences.
What was tested on the Slovak NPPs
Testing of the Slovak NPPs, which included NPP Bohunice V-2 and NPP Mochovce 1&2 and NPP Mochovce 3&4 was carried out mostly in a form of engineering analyses, calculations and reports.
During the stress tests, extraordinary external events were analysed, such as earthquakes, floods and consequences of other initiating events potentially leading to multiple loss of safety functions of an NPP. A combination of events was also assessed, including power failure, long-term water supply interruption, but also loss of power supply due to extreme weather conditions.
Terrorist attack and plane crash
Prevention and coping with the consequences of malicious plane crash to an NPP are not part of the stress tests for the nuclear safety area. To assess the physical nuclear security, which also includes assessment of the risk of terrorist attacks, at the EU level a special working group was established that will deal with the above issues.