- Nuclear installations in Germany
- Safety in nuclear energy
- Legal bases
- Licensing and supervision
- Safety philosophy
- Precautions and emergency response
- National committees
- International co-operation
- Reportable events
- Reporting procedure
- Incident registration centre
- International Nuclear Event Scale (INES)
- Reportable events in nuclear installations
- Reports on reportable events
- Shutdown and decommissioning
- Nuclear accidents
- What is nuclear waste management?
- Design approvals of transport packages
- Interim storage facilities
- What are interim storage facilities?
- Licensing of interim storage facilities for nuclear fuels
- Central interim storage facilities
- Decentralised interim storage facilities
- Interim storage facilities for radioactive waste with negligible heat generation
- Federal custody of nuclear fuels
- What is nuclear waste management?
- Foundation and development
- President of the BfE
- Laws and regulations
- Frequently applied legal provisions
- Handbook nuclear safety and radiation protection
- 1A Nuclear and radiation protection law
- 1B Other laws
- 1C Transport law
- 1D Bilateral agreements
- 1E Multilateral agreements
- 1F EU law
- 2 General administrative provisions
- 3 Announcements of the BMU and the formerly competent BMI
- 4 Relevant provisions and recommendations
- 5 Nuclear Safety Standards Commission (KTA)
- 6 Key committees
- Annex to the NS Handbook
- A 1 English translations of laws and regulations
- Dose coefficients to calculate radiation exposure
- Legal Basis
- BfE Topics in the Bundestag
Preventive measures against power failure
Nuclear power plants depend on electric energy supply ("power"), because they have numerous electrically driven systems. These systems include those that are vital for safety. Therefore, preventive measures are taken in the event of the external power supply of a nuclear power plant failing.
Power supply in a nuclear power plant
A nuclear power plant produces electricity and feeds it into the public grid. At the same time it consumes electricity since it needs power for its electrically driven components (such as pumps, valves, ventilation, etc.). Generally, nuclear power plants in Germany can get power via three different paths:
In normal operation, the power plants provide themselves with the power required for their own use. The remaining power produced is fed into the public grid.
Via main off-site power connection from the public grid
When the power plant is not operated or has been shut down (for example during an inspection or after an incident), the nuclear power plant is supplied with power for its own use by the public grid via the main off-site power connection.
Via spare off-site power connection from the public grid
If the main off-site power connection fails, one switches to a spare off-site power connection that is connected with another voltage level of the public grid and is independent of the main off-site power connection.
Failure of external power supply
If the connection to the external power supply fails completely, a nuclear power plant can no longer release its generated power into the grid. In that case, the nuclear power plant reduces its capacity drastically to a level that corresponds with its own use of electrical power. Thus, the nuclear power plant can generate its own electricity in isolated operation separated from the public grid. This process is called "load rejection to auxiliary power".
If the load rejection to auxiliary power fails, the nuclear power plant is automatically shut down and covers its demand of electric power gradually via
Emergency diesel power
German nuclear power plants have several emergency diesel power aggregates which supply power to all systems required for safety (e.g. cooling water pumps, instrumentation and control). Their number and performance varies depending on the respective plant. Generally, the plants have fuel reserves available for several days. If required, more fuel can be added.
Neighbouring power plant
A neighbouring power plant (e.g. gas turbine or hydroelectric power plant) or a neighbouring nuclear power plant unit (in the case of several power plant units present on the plant premises) can provide power. Some plants have a direct connection.
Station blackout: Additional failure of emergency diesel power
If the external diesel power has failed and if the emergency diesel power aggregates fail on top of that, this is referred to as a “station blackout”. In that case battery-supported power supply is available for all areas of instrumentation and control as well as selected, smaller electrical devices. This battery supply can provide the aforementioned areas with power for a limited period of time, even in the event of a failure of the emergency diesel power. However, the battery supply cannot provide larger electrical devices with power, e.g. cooling water pumps.
Furthermore, each nuclear power plant has mobile, protected diesel aggregates available that can be used in the event of a station blackout and reload the batteries and provide selected systems with power.
State of 2017.02.28