Vermen event at the Neckarwestheim nuclear power plant

Im Neckarwestheim nuclear power plant (GKN II) was noticed on December 23, 2022 during a routine tour that coolant had escaped from the cooling water system of an emergency power unit. The amount was so low with less than
100 milliliters that it was not yet recognizable by the automatic monitoring of the cooling water level.

The cause of the leakage was a damaged rubber compensator in a pipeline. The function of the rubber compensator is to buys vibrations in the transition area to the pipes of the cooling water system when operating the emergency power diesel engine.

classification by the approval holder: registration category n (normal message); Ines 0 (no or very low safety importance).

The event has not had any effects on people or the environment.

measures of the approval holder

The operator exchanged the damaged rubber coatator. After a successful test run to check the tightness of the new compensator, the emergency power diesel unit was again ready for use in the course of December 23, 2022. As a precaution, the operator carried out visual tests of the other compensators on all emergency power diesel units. There were no further findings.

First examinations of the operator indicate a material defect of the affected compensator. The exact cause is examined even further.

Security assessment of the Ministry of the Environment, Climate and Energy Industry Baden-Württemberg

The affected emergency power diesel unit is one of four aggregates of the so -called emergency power generation system 1, which is available in order to supply important systems and components of the nuclear power plant with electricity if their normal power supply would fail. For example from the electricity production of the nuclear power plant or from the external power grid. Two of the four emergency power diesel units are needed to ensure that the security -related functions are sufficiently ensured; Also when the same occurrence of interpretation stoors.

It cannot be ruled out that the damage when operating the engine would have expanded and ultimately leaded to a failure of the emergency power diesel unit. Since three other redundant emergency power diesel units are generally available, the safety meaning is still very low.

reporting levels

The events that are important for core security are the nuclear regulator of the countries according to the nationwide criteria of Nuclear Safety Commissioning and Reporting regulation - ATSMV. The aim of the reporting procedure is to monitor the safety status of the nuclear power plants, to prevent the occurrence of similar errors in other nuclear power plants and to incorporate the knowledge gained into safety improvements. The reportable events are assigned to different categories (explanations on the reporting criteria for reporting events):

• category S (immediate report): Events that the supervisory authority must be reported immediately so that they can initiate exams or take measures if necessary. This also includes the events that show acute safety -related defects.
• Category E (message within 24 hours): Events that the supervisory authority must be reported within 24 hours so that you can take exams or take measures if necessary. This also includes the events, the cause of which, for security reasons, has to be clarified in a short period of time and, if necessary, remedied in a reasonable time. As a rule, these are potentially potential - but not directly - significant events.
• category N (message up to the fifth working day): Events that the supervisory authority must be reported within five working days in order to be able to identify any weaknesses in safety at an early stage. This is usually of low level of safety, which go beyond routine individual events in the event of a state -of -the -art system condition and operation. Unavailations of components/systems that are temporarily intended by procedures specified in the operating manual are not subject to reporting if this is also taken into account in the safety specification of the operating manual.

International rating scale Ines

Due to an agreement between the operators of the nuclear power plants and the Federal Minister for the Environment, Nature Conservation and Nuclear Safety, reportable events in nuclear power plants will also be based on the evaluation scale Ines (International Nuclear and Radiological Event) of the international atomic energy organization (iaeo) and the nuklearergie agency for organization for organization Economic cooperation and development evaluated. It aims to evaluate an event that is understandable for the public.

The scale comprises seven stages

1. fault
2. accident
3. serious accident
4. Accident with locally limited effects
5. accident with further effects
6. serious accident
7. catastrophic accident

reportable events that cannot be classified in the scale (1 to 7) according to the Ines manual are assigned to the national assessment of the "level 0" regardless of the security significance.